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ATLAS User`s Manual - UH Petroleum Engineering

1. Table 15 1 Complete list of available C Interpreter functions in ATLAS Statement Parameter Template Description MATERIAL F TAUP taup Hole SRH lifetime as a function of position MATERIAL F COPT copt Radiative recombination rate as a function of com position and temperature MATERIAL F GAUN gaun Electron Auguer rate as a function of composition and temperature MATERIAL F GAUP gaup Hole Auger rate as a func tion of composition and temperature INTERFACE F QF int fixed charge Interface fixed charge as a function of position DEGREDAT F NTA devdeg nta Interface acceptor trap density as a function of location DEGREDAT F NTD devdeg ntd Interface donor trap den Sity as a function of location DEGREDA F SIGMAE devdeg sigmae Interface electron c apture cross section DEGREDA F SIGMAH devdeg sigmah Interface hole capture cross section INTTRAP F DENSITY inte trap Interface acceptor donor trap density as a function of location DEFEC F TFTDON tftdon FT donor trap densit yas a function of energy DEFEC F TFTACC tftacc FT acceptor trap density as a function of energy IMPACT F EDIIN ediin Electron temperature coef ficients for impact ion ization IMPACT F EDIIP ediip
2. DEVEDIT Fine Grid only in Key Areas 2450 nodes SILVACO International Figure C 8 Fine Grid only in Key Areas 2450 nodes C 8 SILVACO International Hints and Tips File 7 View Plot Tools Print Properties Help ATLAS Id Vds Curves for Two MOSFET Meshes drain current A micron 1 IET eed a a D 2 arain bias VP SILVACO International Figure C 9 Id Vds Curves for two MOSFET Meshes View Plot Tools Print Properties Help ATLAS Breakdown Voltage for Two MOSFET Meshes Pre breakdown leakage is reduced with coarse mesh but breakdown voltage is the same s ki S 2 5 s g E3 d 5 8 d a 2 drain bia V ds SILVACO International Figure C 10 Breakdown Voltage for Two MOSFET Meshes Demonstration of optimized griding using constraint boxes in DEVEDIT Both very fine and optimized mesh produces equivalent results SILVACO International C 9 ATLAS User s Manual Volume 2 Question How can solution quantities such as Electric Field be saved for plotting against applied bias Answer There are two types of output files saved
3. Table B 19 Band Parameters for Miscellaneous Semiconductors Material Eg 0 eV Eg 300 eV Silicon Poly silicon Ge 0 7437 4 17 1074 235 0 0 2225 0 2915 4 0 Diamond 5 45 4 77x1074 0 0 a b 7 2 6H SiC 2 9 2 9 0 0 0 0 0 454 0 33 4H SiC 2 2 252 0 0 0 0 0 41 0 165 1 2 43 2 43 0 0 0 0 AlAs 2 16 2 16 0 0 0 0 A1Sb 1 6 2 69 107 2 788 0 4 GaSb 0 81 3 329 1074 27 6622 0 24 3 65 InSb 0 235 2 817x104 90 0003 0 014 0 4 4 06 ZnS 3 8 3 8 0 0 0 0 0 4 4 59 ZnSe 2 58 2 58 0 0 0 0 0 1 0 6 ZnTe 2 28 0 0 0 0 0 1 0 6 4 09 Cds 2 53 2253 0 0 0 0 0 21 0 8 3 5 CdSe 1 74 1 74 0 0 0 0 0 13 0 45 4 5 CdTe 1 5 1 5 0 0 0 0 0 14 0 37 HgS 245 2 5 0 0 0 0 4 28 HgSe HgTe SILVACO International B 15 ATLAS User s Manual Volume 2 Table B 19 Band Parameters for Miscellaneous Semiconductors Material Eg 0 eV Eg 300 eV Me my xev PbS 012431 0 37 0 0 0 0 0 25 0 25 PbSe 0 26 0 26 0 0 0 0 0 33 0 34 PbTe 0 29 0 29 0 0 0 0 0 17 0 20 4 6 SnTe 0 18 0 18 0 0 0 0 ScN 2 15 2 15 0 0 0 0 GaN 3 45 3 45 0 0 0 0 01772 0 259 A1N 6 28 6 28 0 0 0 0 0 314 0 417 InN 1 89 1 89 0 0 0 0 0 11 Body BeTe 2i 8 2287 0 0 0 0 Notes Nc300 5 0 1018 b Nv300 1 8 1019 c 20 39 m G 0 09 Nc Nc X Nc G 9 0 047 m L 0 36 Nc Nc G Nc L Misc
4. 12 7 More Information roce Mer ER 12 7 13 Fee SA set Opes ttiv fortia eoa alus 13 1 OVGLVIOW cec ntu Dus ien s VeL E Da asta ata 13 1 3D Str cture Generation 7 2255 AeA oA er e a AL d cedo E Eua 13 1 Defining HeaESQUICBS sio cos t 13 1 Defining FEATS INKS cs os eorom bor Erro bie EO espe kac vg eeu 13 1 Model and Material Parameter 13 2 Setting Thermal Conductivity Pede cto tha c ra bmc db eate IRR 13 2 Suggested Parameters For Thermal Conductivity 13 3 Numerical Methods iter rtr De eens 13 3 Obtaining Solutions In THERMAL3D 13 3 Interpreting The Results From 13 4 More Information xo x o e RI CR ROCA XD ARCU UR D ORC Wap CU REUS wh are 13 4 Chapter 14 Numerical Techniques Ec xe eme tea Eh fem 14 1 OVervieW cerne et
5. Syntax SINGLEEVENTUPSET lt parameters gt Parameter Type Default Units Al Real 2 1 1 4 1 Bl Real B2 Real B3 Real B4 Real B DENSITY Real 0 cm BEAM RADIUS Real 0 um DENSITY Real cm ENTRYPOINT Real vector um EXITPOINT Real vector um PCUNITS Logical False RADIALGAUSS Logical False RADIUS Real um RESCALE Logical False TFINAL SEU Real TO Real TC Real 1 UNIFORM Logical False Description 1 2 and A4 are the first set of parameters for the length dependence of the charge generation pulse B1 B2 B3 and B4 are the second set of parameters for the length dependence of the charge generation pulse SILVACO International 15 125 ATLAS User s Manual Volume 2 SINGLEEVENTUPSET Statement B DENSITY specifies the number of electron hole pairs per unit volume or generated charge in pico Coulumbs per micron if the PCUNITS parameter is specified BEAM RADIUS is the radius of the beam where the generation rate is maintained constant Beyond this point the generation will decay by either an exponential or by a Gaussian function DENSITY specifies the number of electron hole pairs per unit volume generated along the alpha particle track ENTRYPOINT specifies the x y and z coordinates of the beginning of the alpha particle track The specified point should belong to the semiconductor region
6. 2 4 4 2 24 1 2 B 14 Miscellaneous Semiconductors B 15 Miscellaneous Semiconductor Band Parameters B 15 Miscellaneous Semiconductor Dielectric Properties B 16 Miscellaneous Semiconductor Mobility Properties B 17 InsulatorS et er B 19 Insulator Dielectric Constants 2222 2 B 19 insulator Thermal Properties th een B 17 Optical Properes ELEM TE B 19 User Defined Materials 22 Appendix Hiliis TIPS S REI d C 1 Appendix D ATLAS Version IN Ee eee D 1 Bibliography Volume 1 Volume 2 Index Volume 1 Volume 2 SILVACO International XV ATLAS User s Manual Volume 2 This page intentionally left blank xvi SILVACO International List of Figures Figure Page No Caption Title No 11 1 Source beam coordinate rotation around 2 11 9 11 2 Source beam coordinate rotation around Y axis
7. 15 60 Oxide Material Parameters 15 61 15 61 LASER Parameters iceren Xe Yee eal ee ien 15 61 Material Coefficient Definition Examples 15 62 MEASURE dono on Deor OON ue MED tales mains Manisa hewn take Pad EA qut 15 63 DOSCHDIDOD e ox eto deae aae ore set 15 64 D ta Type Paramete v dE a de chee obe par gatis 15 64 Boundary Parameters b x ERREUR RE ow RE RA WERE EA RE RR 15 65 Resistanc E rei vane ots ta 15 65 Gate Charge Example PE Ye Rede MP Qr iS 15 65 lonization Integral Example eens es o vad a lak old 15 65 15 66 DSSCIHpDOIT Ei hc Sue EAT PER NARNIA ERO 15 66 SILVACO International Xi ATLAS User s Manual Volume 2 Parameters related to reading in an existing mesh file 15 66 Parameters Related to Creation of a New 15 67 Output Parameters
8. 14 1 Numerical Solution ProcedureS s ot uer ped tana stone Ana du MA 14 1 MeSsh68 oec xo pcena a ata neo sl ca ea E D RI 14 1 Mas sos desertas iod ox ona salts atem cid dt deua Us md a 14 2 MeSH saeua eite ne RR CS SO a e Ce UR tO e 14 3 Disctetizalioni cae 14 3 The Discretization 0 55 2 2 44 4 4 4 4 4 440 14 3 Non Linearlteration Dex YYTUE SUR REA DOx Re Dar Dacus entered DP tans o 14 4 Newton vasto tc e tcs tnu a t E 14 4 14 4 dI 14 5 Combining The Iteration Methods _ 14 5 Solving Linear Subproblems 14 5 Convergence Criteria for Non linear 5 14 6 5 5 VEA 14 6 Carrier Concentrations and CLIM DD CLIMIT 14 6 DISCUSSION o CLIM ER us nett t actor 14 7 Terriinal C rrent Criteria ke er oe
9. sce 12 1 Model Descriplioli 47255344 ida ea deca ecd sale aca was aer 12 1 Capacitance and Conductance 12 1 Boundary COMMONS de tlla fte ost ees tate deh ate ty dics deeded 12 1 Structure Definition 1 4 2 2 2 2222 2 12 3 Tutorial For The MaskViews 1 12 4 Saving Mask Data For INTERCONNECT3D 12 4 Loading Mask Data Into INTERCONNECT3D 12 4 Defining Electrodes a Porra 12 4 Model And Material Parameter Selection 12 6 Conductivity Calculations DR RC Nb RO P RO n e RR em P Redes 12 6 SILVACO International vii ATLAS User s Manual Volume 2 Capacitance Calculations 12 6 Applying CD Variations and Misalignment 12 7 Numerical Methods vocet rere a eee en Ra 12 7 Obtaining 5006 hae iudei ue i AU 12 7 interpreting the Results 5447s
10. SOLVE Statement Statements SOLVE SOLVE instructs ATLAS to perform a solution for one or more specified bias points Syntax SOLVE lt ion gt dc lt fp gt lt gt lt tp gt lt ac gt lt photo gt lt thermal gt Parameter Type Default Units AC ANALYSIS Logical False ANAME Character AR INDEX Real 1 0 AR THICKNESS Real 0 0 microns ASCII Logical False AUTO Logical True B lt n gt Real 0 0 W cm CNAME Character COMPLIANCE Real CURVETRACE Logical False CYCLES Integer 1 CYCLIC BIAS Logical False CYCLIC RELAX Real 0 2 CYCLIC TOL Real 1 0 1072 DECAY Real 5 DELTAV Real 0 1 V DIRECT Logical False DT Real 0 S E COMPL Real E CRIT Real 1 0x1078 ELECTRODE Integer ENDRAMP Real 5 FREQUENCY Real Hz FSTEP Real 0 Hz GRAD Logical False I lt n gt Real A um SILVACO International 15 127 ATLAS User s Manual Volume 2 SOLVE Statement Parameter Type Default Units IFINAL Real A um IMULT Logical False INAME Character INDEX CHECK Logical False INITIAL Logical False ION CRIT Real 1 0 ION ELEC Integer see Description IONIZINT Logical False IONLINES Integer 50 none IONSTOP Logical True ISTEP Real 0 0 A um LAMBDA1 Real um LIT STEP Real W cm LOCAL Logical False LRATIO Real 1 0 L WAVE Real um MASTER Logical False INNER Integer 25 MLOCAL Logical True ULT FREQ Logical False N BI
11. dae Lucky Electron LUMINOUS itis iint LUMINOUS Luminous IF tensity ss Luminous Wavelength Lumped Capacitance Lumped Element ipe Lumped Resistance acean eie ct ied ees M askVIews eran d 12 4 aterial Parameters 2 17 Material Properties 2 20 athiesen s 3 38 3 44 eU 2 9 4 8 14 1 15 64 ETHOD Statement em 2 29 RS nta 9 5 IXEDMODE 13i deett tin cei tete eet 10 1 112 OCA aoro ait 14 16 mobility 3 31 4 5 4 8 5 15 5 19 5 24 5 26 15 57 15 82 15 96 onochromatic OS acca dee i t o SM cusa nci gant at ead ER E ultispectral N negative differential mobility een 5 16 negative differential resistance sseeeenn e 4 9 Neumann boundary NEWTON Newton method Newton Richardson Non volatile Memory eee Numerical Methods seen 0 OHMIC CONTA aca t eoa P De 3 23 Open Circuit Voltage ssseeeennnnn 4 6 8 16 Optical
12. 15 48 SILVACO International LOG Statement Statements Parameter Type Default Units WIDTH Real 1 microns Y PARAM iogica False Z PARAM iogical False File Output Parameters OUTFILE specifies the log file that will be used to store DC AC or transient I V information MASTER specifies that AC data and I V information will be saved in a standard structure file format This is the default format J ELECTRON specifies that electron currents are to be written into the log file J HOLE specifies that hole currents are to be written into the log file APPEND specifies that the output I V information should be appended to an existing log file Care should be taken to ensure that the existing log files contain the same type of data eg DC AC transient as the subsequent SOLVE statements OFF specifies that any currently open log file will be closed and log file output is discontinued OLD specifies that AC data and IV information will be saved in the original PISCES II file format Synonym PISCES Note The older ACFILE syntax is not supported and should not be used AC results are stored in the file specified by OUTFILE as long as the first SOLVE statement after the LOG statement contains analysis RF Analysis Parameters If S PARAM H PARAM Z PARAM GAINS or ABCD PARAM is specified the capacitance and conductance data will be converted into the requested set of AC parameters
13. SOLVE T1 300 POWER2 0 35 NSTEPS 3 ELECTRODE 1 TEMPFINAL 600 OUTFILE thermal_out0 increments the temperature on electrode 1 from 300 K to 600 K in 3 steps Thermal power and temperature can be simultaneously sweep If more than one region power is specified during a sweep the region to be stepped must be specified by STEPREGION as shown in the first example above If the STEPREGION parameter is not specified the smallest numerical value of POWER is stepped During temperature and power sweeps the output filename is modified according to the following rule The rightmost character is incremented using the sequence 0 9 A Z a z When a character is incremented beyond 2 the character is set to 0 gt and the character to the left smaller than 27 is incremented SILVACO International 13 3 AT LAS User s Manual Volume 2 Complete syntax information for the SOLVE statement can be found in Chapter 15 Statements The SOLVE statement is used in THERMAL3D for heat flow solutions much as it is used in other ATLAS simulations for electrical biases Thetemperature in Kelvin on each heat sink in the device must be set on the SOLVE statement The parameter Tn where n is the number of the heat sink is used to set the temperature For example SOLVE T1 300 T2 500 This sets 300K on heat sink 1 and 500K on heat sink 2 Only one SOLVE statement is allowe
14. define any electrodes In this case the program finds connected blocks of metal for each interconnect Each interconnect is assigned a different electrode number The position of a point in each conductor is printed to the run time output to enable users to tell the number of each interconnect This method is typical when the MASK Views interface is used e Specify the point which is inside any conductor using the ELECTRODE statement ELECTRODE NUM lt integer gt X PNT lt val gt Y PNT lt lt val gt Z PNT lt val gt All the metal conductors of the interconnect structure connected to that point will assume the same electrode number X PNT 7 defaults y PNT has a default of zero Specify parallelopiped which intersects electrode with boundaries x MIN X MAX Y MAX Z MIN Z MAX in the ELECTRODE statement then all the connected points of interconnect structure will refer to the same electrode ELECTRODE NUM lt integer gt xX MIN lt val gt yY MIN lt val gt z MIN lt val gt X MAX lt val gt y MAX lt val gt Z MAX lt val gt In this case default values of these parameters differ from the usual ATLAS case They has no default has no default Y MIN 0 Y MAX layer thickness Z MIN 0 Z MAX 0 SILVACO International 12 5 ATLAS User s Manual Volume 2 Model And Material Parameter Sele
15. B 9 B 12 Default Recombination Parameters for AlGaAs B 10 B 13 Impact lonization Coefficients for GaAs B 10 B 14 Default Thermal Parameters for B 11 B 15 Thermal Resistivities for InGaAsP B 12 B 16 Default Thermal Properties of InP InAs GaP and GaAs B 12 B 17 Impact lonization Coefficients for 5 B 14 B 18 Default Thermal Parameters for SiC B 14 B 19 Band Parameters for Miscellaneous Semiconductors B 15 B 20 Static Dielectric Constants for Miscellaneous 5 B 16 B 21 Mobility Parameters for Miscellaneous Semiconductors B 17 B 22 Default Static Dielectric Constants of Insulators B 19 B 23 Default Thermal Parameters for Insulators B 19 B 24 Wavelength Ranges for Default Complex Index of Refraction B 21 SILVACO International ATLAS User s Manual Volume 2 This page intentionally left blank i SILVACO International Chapter 11 3D Device Si
16. inttrap e level 0 32 donor density 1 e10 degen 1 sign 1 00e 16 sigp 1 00e 17 Note For semiconductor bulk trap levels see the TRAP statement SILVACO International 15 45 ATLAS User s Manual Volume 2 LOAD Statement LOAD LOAD loads previous solutions from files as initial guesses to other bias points Syntax LOAD ASCII MASTER NO CHECK lt files gt Parameter Type Default Units ASCII Logical False INFILE Character INIFILE Character IN2FILE Character MASTER Logical False NO CHECK Logical False TWOD Logical False Description ASCII specifies that any original PISCES format files read or written by this statement will be in an ASCII rather than in a binary format MASTER specifies that any files read by this statement will be in a standard structure file rather than the original PISCES format If you are using TONYPLOT to plot simulation results this parameter should be specified TWOD allows loading of a 2 D solution into a 3 D structure Note The values from the 2 D solution are loaded uniformly in the Z direction NO CHECK prevents checking material parameter differences between loaded binary files and the values set in the current input file File Parameters The LOAD statement requires that one of the following file parameter syntaxes be used LOAD INFILE lt filename gt LOAD INIFILE lt filename gt IN2FILE lt fil
17. nj LAS OMEGA LAS SIN LAS SPECSAVE LAS TAUSS LAS TIMERATE LAS TOLER MATERIAL MIN SURF MOBMOD OX RIGHT OX BOTTOM CONCANNON Real Real Real Integer Real Logical Real Character Logical Integer Logical Real Real Real Real Real Real jogical jogical Character Logical Logical Real Real Real jogical jogica l Real Real Real Default 3 57 2 16 1015 1 0 104 1 0 05 True 0 001 False False 481 0 591 0 1270 0 92 8 124 534 False False False False 0 0 False False 3 4x107 2 38x107 S22 Units 1 sec cm cm Vs cm Vs cm Vs cm Vs cm Vs cm Vs mm um um microns microns ev 15 96 SILVACO International MODELS Statement Statements Parameter PEFF P U HOTON ENERGY POST SCHRO PRINT PROGRAM QUANTUM OX MIN OX MAX SCHRO 5120 SHI SPEC NAME SRH SURFMOB TATUN TAUMOB TAUTEM TE LDMB1 TFLDMB2 THETA N THETA P YAMAGUCHI Description Type Real Real jogica l Logical jogical jogical Real Real Logical Logical Logical Character Logical Logical Logical jogica l jogical Real jogical jogical
18. 15 33 EXTRACT OAS trac ce Ce 15 34 Terminal Current Extraction Example 15 34 Extraction Example from Previously Generated 15 34 Solution Quantities Extraction Example ate ete we 15 34 FOURIER Red Read Ux 15 35 DII dtc TT uc 15 36 Example 257 REPE FERE D 15 36 co 15 37 Example starting a given ATLAS 15 37 Parallel ATLAS Example AY RR RO ROUES 15 37 ler cS 15 38 Desenpton dues e iude ML 15 39 Model Selection Flags REOR ue xd Rut P ones Rusted dade 15 39 Model Localization Parameters 15 40 Selberrherr Model Parameters 15 40 Temperature Dependence Parameters 15 40 Parameters for use with Energy Balance 15 40 Concannon Model Parameters 15 41 Selberrherr Model Example et Ny aie ag Ganda warty ana oes 15 41 X SILVACO Intern
19. 6 2 13 2 15 59 Thetmal Contacts h Thermal ResiStance i iiit Thermal Velocities Thermionic Emission Threshold Voltage TODVDIOE TOnVplot3D ftierit ter prin Transient Simulation Transient Solutions rei treten Transient T FADS sec cec o tet dinate Transmission Coefficient 8 4 ove ad imo Re rate 2 33 3 11 15 149 rap Assisted Tunneling 3 14 3 62 7 5 TR BDF 11 8 14 18 U UTMOST reU 15 151 valence band density 15 56 velocity Saturdtloll ei cmt 4 5 5 16 5 26 W wavelength ce eet amer ec a a e nets 15 6 Workfunction sse 2 17 3 24 4 3 5 2 15 11 C 5 SILVACO International Index 4
20. pea eme Len ed Ert eU blc een add 14 7 Summary of Termination Criteria 14 8 Detail d Gonvergence Criteria sani waitin C Ma dr tc ie d th 14 10 Convergence Criteria For Gummel s 14 10 Convergence Criteria For Newton s Algorithm 14 12 Convergence Criteria For Block Iteration 14 14 viii SILVACO International Table of Contents hiickcelllrc onqns wee 14 15 Recommendations And Defaults e 22 ence bid e Fera v ECL d I ed qus 14 16 The DC Curve Tracer Algorithm recien cee etr eL em Rx RE RE ERE RETE X 14 16 Transient SimulallOn 225 c ies aX ray xcu aa RARE EO ERREUR ede RN Rn 14 17 Small Signal and Large Signal Analysis 14 18 Frequency Domain Perturbation 515 14 18 Fourier Analysis Of Transient Responses cese cec Cp e eO Sed t oa ts 14 19 Overall Recommendations 14 20 Differences Between 2D and 3D Numerics 4 21 Chapter 15 Slatemells 4450s eun suis bears ess es Pa x f
21. DEDE E OOR EE AE OARA 15 118 Ree Ree EEE eee LEE EEEE 15 119 Variable Parameters xs Eee angen Re rte ide Ea tb ea hc oes 15 119 ene Sate ates 15 119 Control Parameters cce 15 120 E Crib 15 120 Doping Regrid Examples queer sse trc ba orit enfe aur aor a 15 121 Potential Regnd Example Po Oded Shak NER Rex RU RR Tenn 15 121 Re initializing after regrid 15 121 SET vta vue auc IRR mice od kb Rp wi ust Pale 15 122 N rmenc aM eai detta ec o C nnt tena gt tentus 15 122 String Variable Examples satu es iussa phu cto Cres be Ine ILC LIN I sagt d 15 122 SAVE sees Axe pea a ats naa Atv eres uat ie ew ae ag eae 15 123 iaa iu api TTE ISAE EGG EGG GG ESTREN 15 123 Basie Save Example a sou cae ia 15 123 Example with User defined Output 15 123 SINGELEEVENTUPSET 2 teca Deas a sce eae Es eee eed 15 125 easels eae ens RENS LEVA
22. Rn ME TE 15 21 SOT aed 2a des pu uia dd 15 21 Description s eu titer 15 23 Analytical Profile Types paa c RR TUR ee e a s 15 23 File Import Profile Types sc re eed uk DUX Ra ede 15 24 Parameters that Specify the Dopant 15 24 Vertical Distribution Parameters 15 25 eic 15 25 Lateral Extent Parameters DRE 15 26 Lateral Distribution 15 26 uut 15 26 ELECTRODE 5 da teen CHR DER do 15 29 15 29 MON Neri OM dos OM td cM 15 29 Position Parameters 2s rss verre n ER ER Rer 15 30 R gion Parameters vs we e PR E Ta 15 29 MOS Electrode Definition Example 15 31 3D Electrode Definition Example cito ev crc oc bb ON CECI CRDI ts 15 31 ELIMINATE 55 55 Eme 15 32 Substrate Mesh Reduction Example
23. 13 2 14 1 User Specifiable Parameters for Convergence 14 9 14 2 User Specifiable Parameters for Equation 9 2 14 19 15 1 Types ol Parameters i D ROLE 15 2 1 Complete list of available C Interpreter functions in ATLAS A 3 B The ATLAS Materials 224 E RIVER EET ease ees NET B 3 B 2 Band parameters for Silicon and B 6 B 3 Static dielectric constants for Silicon and Poly B 6 B 4 Lattice Mobility Model Defaults for Silicon and Poly B 6 B 5 Parallel Field Dependent Mobility Model Parameters for Silicon and B 6 B 6 Bandgap Narrowing Parameters for Silicon and Poly B 7 7 SRH Lifetime Parameter Defaults for Silicon and Poly B 7 B 8 Auger Coefficient Defaults for Silicon and B 7 B 9 Impact lonization Coefficients for Silicon and Poly B 8 B 10 Effective Richardson Coefficients for Silicon and Poly B 8 B 11 Effective Richardson Coefficients for Silicon and
24. B 4 SILVACO International Material Systems SiGe The composition fraction x applies to the Ge component SiGe is then specified as Si 1 Ger an exception to rule 4 AlGaAs This is specified as 1 5 This is an exception to rule 2 InGaAsP The convention 1 5 1 as set forth by Adachi is used This is an exception to rule 4 SILVACO International B 5 ATLAS User s Manual Volume 2 Silicon and Polysilicon The material parameters defaults for Polysilicon are identical to those for Silicon The following paragraphs describe some of the material parameter defaults for Silicon and Polysilicon Note Within the Physics section of this manual a complete description is given of each model The parameter defaults listed in Chapter Three are all Silicon material defaults Silicon and Polysilicon Band Parameters Table B 2 Band parameters for Silicon and Poly Material P8300 a 300 Nv300 X eV per cc per cc eV Silicon 1 08 4 73x10 4 636 0 8 Benge 1 04 1019 17 5527 1508 4 73 1074 636 0 2 8 1019 1 04 1019 4 17 Silicon and Polysilicon Dielectric Properties Table B 3 Static dielectric constants for Silicon and Poly Material Dielectric Constant Silicon 11 8 Poly 11 8 Silicon and Polysilicon Default Mobility Parameters The default mobility parameters for Silicon and Poly are identical in
25. E E a E Ea ded dd 15 108 lonization Integral Parameters 15 110 Averaging Parameters for Vector Quantities 15 110 Example of combining OUTPUT with SOLVE and SAVE 15 110 ie lcd 15 111 Description secrets Faro o xo dap der Gars pe pats 15 112 Example of Probing the Maximum Value 15 113 Example or PROBE ata location 15 113 Vector Quan Example en cro cho WERT ERE De vor RR MT A 15 113 QUIT i cte 15 114 SILVACO International Table of Contents Description ies 15 114 REGION ints 15 115 Ou ce 15 115 Positi n Parameters 15 116 Grid Inidices Tas d quant ao 15 117 Non Rectangular Region 15 117 Typical MOS anh 15 117 3D Region Definition Example 15 117 REGRID MTM tents
26. EXTRACT NAME integrated area from curve depth n conc material Silicon mat occno 1 x val 1 0 Note EXTRACT commands are generally case sensitive 15 34 SILVACO International FOURIER Statement Statements FOURIER FOURIER enables the ability to do Fourier transformations in ATLAS Syntax FOURIER INFILE OUTFILE OPTIONAL PARAMETERS 1 Parameter Type Default Units COMPLEX Logical False UES FUNDAMENTAL Real Hz INFILE Character INTERPOLATE Logical False MAX HARMONIC Real Hz NUM SAMPLES Integer 64 OUTFILE Character T START Real S T STOP Real S Description The FOURIER statement performs a Fast Fourier Transform on log file data COMPLEX VALUES specifies that the real and imaginary components are saved to file as well as the magnitude and phase values synonym REAL VALUES FUNDAMENTAL specifies the fundamental frequency If this is not specified then the fundamental frequency is set to T STOP T START NUM SAMPLES If the fundamental frequency is specified then T STOP is set to T START 1 FUNDAMENTAL INFILE specifies the input log file This should contain data from a transient simulation INTERPOLATE specifies that the input data should be linearly interpolated such that data at uniform time steps are created Interpolation of data can introduce addition inaccurate harmonic values into the Fourier tr
27. Gl COMMO CON RESIST CURRENT DEVICE TUNNEL ELE CAP F ETUNNEL FACTOR FLOATING FG CAP INDUCTANCI Gl TUNNEL O DISILICID MOLYBDENUM ULT NAME NEUTRAL N POLYSILICON lt gt 1 Real ogical ogical Real Character Real Logical Character Logical Integer Character Real Logical Real Real Real ogical ogical Logical Character ogical E ename ALL Default False 0 False False False False False False False True False lt wfp gt lt be gt lcr lt link gt Units cm F um F um H um 15 10 SILVACO International CONTACT Statement Statements Parameter Type Default Units NUMBER Integer 5 Logical False RESISTANCE Real 0 Q um SHORT iogical False SURF ogical False TU DISILICIDE iogical False TUNGSTEN iogical False VSUREN Real see descrip cm s tion VSURFP Real see descrip cm s tion WORKFUN Real 0 V Description NAME specifies the name of a previously defined electrode See ELECTRODE statement NUMBER specifies the contact number to be defined It must be the number
28. ER n position EXT TEMPER lt n gt ALPHA lt n gt Type Default Units Real W 2 Character Integer Real 300 K Character Integer 1 Real Right side of structure Um Real Left side of structure um Real Bottom of structure Real Top of structure um Real Front microns Real Back microns E position is set of the position parameters described below Either X MIN and parameters are used to specify the exact postion of the contact or the ELEC NUMBER parameter to specify an electrode number that the thermal contact coincides with NUMBER specifies a thermal contact number from 1 to 20 Contact numbers should be specified in increasing order This parameters must be specified on all THERMCONTACT statements ALPHA specifies the reverse value of thermal resistance 0 1 This parameter may not be used if ELEC NUMBER parameter has been specified EXT TEMPER specifies the external temperature Synonym TEMPERATURE Position Parame ters NAME specifies which region the THERMCONTACT statement applies to Note that the name must match the name specified in the NAMI E parameter of the RI EGION statement DEVICE specifies which device in MIXEDMODE simulation the THERMCONTACT statement applies to ELEC NUMBER specifies an electrode number that the thermal contact is coincident
29. SILVACO International 15 99 ATLAS User s Manual Volume 2 MODELS Statement Quantum Carrier Statistics Model Flags EIGENS specifies the number of eigenstates solved for by the Poisson Schrodinger solver CALC FERMI specifies that the Fermi level used in calculation of the quantum carrier concentration in the Schrodinger Poisson model is calculated from the classic carrier concentrations FIXED FERMI specifies that a constant Fermi level is used along each individual slice in the Y direction for carrier concentration calculation in the Schrodinger Poisson model HANSCHQM turns on the Hansch quantum effects approximation model for N channel MOS devices POST SCHRO specifies to calculate the Schrodinger equation for quantum effects as a post processing step SCHRO enables the Poisson Schrodinger solver This can be used for zero carrier solutions only specified by METHOD CARRIERS 0 This is typically combined with the EIGENS parameter to control the number of eigenstates calculated This is a 1D solver that is solved within the mesh between limits setby OX MIN and QX MAX N DORT turns on the Van Dort quantum effects approximation model for N channel MOS devices P DORT turns on the Van Dort quantum effects approximation model for P channel MOS devices QUANTUM enables the quantum moments model QX MIN QX MAX specify the minimum and maximum extent of the Poisson Schrodinger solver along the x axis direction
30. ovo io RC ERO ATUS RI 15 67 Mesh Definition Example ocn itu drole PEU 15 67 ATHENA Interface Example cs prr ero Ve TU eH Neve UELDERDP YS CUP EV iaa 15 68 METHOD c 15 69 Description fie cest eta P anata 15 71 Parameters to select the Solution Method 15 71 Parameters to select which equations are solved 15 72 Solution Tolerance 5 15 72 General Parameters niian en EA a N qp AE EE a 15 73 G mmel Parameters ute ancient arte Rod a greco dud irt eg ds RE Lila apa cit 15 74 Newton 5 15 74 Numerical Method Defintion 15 74 TRAP Parameter Example 15 75 Transient Method Example nesens tet tieu d 15 75 TEC E 15 76 Description 15 84 Mobility MOUSE AGS nd 15 84 Example Selecting the Modifed 15 91 MODELS Be leis deg nade Seem
31. 15 86 SILVACO International MOBILITY Statement Statements MULN YAMA see Table 3 29 MULP YAMA see Table3 29 ASN YAMA see Table 3 29 ASP YAMA see Table 3 29 VSN YAMA see Table 3 29 VSP YAMA see Table 3 29 ULN YAMA see Table 3 29 ULP YAMA see Table 3 29 GN YAMA see Table3 29 GP YAMA see Table 3 29 CVT Transverse Field Dependent Model Parameters BN CVT see Table 3 28 see Table 3 28 CN CVT see Table 3 28 CP CVT see Table 3 28 TAUN CVT see Table 3 28 TAUP CVT see Table 3 28 GAMN CVT see Table 3 28 GAMP CVT see Table 3 28 MUON CVT see Table 3 28 MUOP CVT see Table3 28 MUIN CVT see Table 3 28 MUIP CVT see Table 3 28 MUMAXN CVT see Table 3 28 MUMAXP CVT see Table 3 28 CRN CVT see Table 3 28 CRP CVT see Table 3 28 CSN CVT see Table 3 28 CSP CVT see Table 3 28 ALPHN CVT see Table 3 28 ALPHP CVT see Table 3 28 BETAN CVT see Table 3 28 BETAP CVT see Table 3 28 PCN CVT see Table 3 28 PCP CVT see Table 3 28 DELN CVT see Table 3 28 DELP CVT see Table 3 28 SILVACO International 15 87 ATLAS User s Manual Volume 2 MOBILITY Statement Watt Effective Transverse Field Depenedent Model Parameters ETAN WATT see Table 3 31 see Table 3 31 MREFIN WATT 3 31 MREFI1P WATT 3 31 MREF2N WATT see Table 3 31 MREF2P WATT see Table3 31 MREF3N WATT see Table 3 31 MREF3P WATT see Table 3 31 ALIN WATT see Table 3 31 see Table 3 31
32. DOP REGION 1 MASTER ATHENA 1D BORON RATIO LAT 0 7 INF bipolar exp EMITTER DOP REGION 1 MASTER ATHENA 1D ARSENIC RATIO LAT 0 6 INF bipolar exp X LEFT 12 0 X RIGHT 13 0 DOPOFF 1e16 Athena Doping Interface Example This example demonstrates how to use an SSF format ATHENA file to interpolate doping onto a ATLAS grid and save the doping information for subsequent regrid operations This is an alternative the prefered Athena Atlas interface which is documented in the Getting Started Chapter DOPING ATHENA MASTER INFILE NMOS DOP OUTFILE NMOS DOP REGRID DOPING ABS LOG RATIO 4 OUTFILE NMESH1 STR DOPFILE NMOS DOP SILVACO International 15 27 ATLAS User s Manual Volume 2 DOPING Statement 3D Doping Defintion Example The following example illustrates the formation of a Gaussian highly doped n type area in a three dimensional structure DOPING GAUSS 1 20 PEAK 0 0 CHAR 0 2 X LEFT 0 5 X RIGHT 1 0 Z LEFT 0 5 Z RIGHT 1 0 15 28 SILVACO International ELECTRODE Statement Statements ELECTRODE ELECTRODE specifies the locations and names of electrodes in a previously defined mesh Syntax ELECTRODE lt gt NUMBER lt n gt SUBSTRATE lt pos gt lt reg gt Parameter Type Default Unit
33. Version 2 0 0 R 1 10 11 12 13 14 15 16 17 Improved Standard Structure Output The standard structure output format has been improved to account for multiple values at region interfaces e g contours projecting into regions where they did not apply Reliable Metal Regions Fixed bug that caused metal regions on standard structure format structures that are read into ATLAS to be lost following modification in ATLAS by either addition of electrodes or regridding MEASURE Statement Because of conflicts with the DECKBUILD extract compatibility syntax the ATLAS EXTRACT statement has been changed to MEASURE Error Messages Fixed bug that caused infinite loop of error messages during write of structures containing isolated triangles Larger Allocation Fixed bug for large version altas E for dynamic allocation to allow up to 6 000 nodes Ramping Fixed bug for case where frequency is ramped in AC analysis during a static ramp The frequency is now properly reset to its base value after each static solution Maximum Time Step Added DT MAX parameter tothe METHOD statement to limit the maximum time step size during transient solutions Electron Current Vectors Fixed bug that caused electron current vectors to point in the wrong direction in TONYPLOT lonization Printout Removed spurious printout during ionization integral calculation Incomplete Ionization Fixed bug in incomplete ion
34. 11 6 SILVACO International 3D Device Simulation Table 11 2 User Specifiable Parameters for Equations 11 1 11 2 11 7 and 11 8 Statement Parameter Default Units SINGLEEVENTUPSE DENSITY 0 0 din SINGLEEVENTUPSE B DENSITY 0 0 cm or pC Bm SINGLEEVENTUPSE TO 0 0 5 SINGLEEVENTUPSE TC 0 0 5 SINGLEEVENTUPSE RADIUS 0 05 micron User defined SEU in 3D In addition to the model described by the SINGLEEVENTUPSET statement users can use the C INTERPRETER to specify an arbitrary generation profile This is specified using the syntax BEAM NUM 1 F3 RADIATE myseu c SOLVE 1 1 0 RAMPTIME 1e 12 DT 1e 14 TSTOP 1e 7 The F3 RADIATE parameter indicates an external c language subroutine conforming to the template supplied The file myseu c returns a time and position dependent value of carrier generation in 3 D The value returned by myseu c is multiplied by the parameter B1 at each timestep Boundary Conditions in 3D External Passive Elements It is possible to attach external lumped resistors capacitors and inductors to any contact The syntax is the same as for the 2D products CONTACT NAME drain RES 1e3 CAP 1e 12 L 1e 6 It is also possible to apply distributed resistances to contacts The algorithm used for estimating contact area for 3D distributed contact resistance m
35. 15 84 SILVACO International MOBILITY Statement Statements 4 Use the CVT transverse field dependent model P specifies transverse field degradation for electrons as follows No transverse degradation Use the Watt or Tasch transverse field models depending on the settings of FIELDMOB1 and FIELDMOB2 CH pev ES Use the Yamaguchi transverse field dependent model 4 Use the CVT transverse field dependent model KLA N turns on Klaassen s mobility model for electrons see Equations 3 132 through 3 157 KLA P turns on Klaassen s mobility model for holes see Equations 3 132 through 3 157 MOD WATT N turns on modified Watt mobility model for electrons see page 3 194 MOD WATT Pturns on modified Watt mobility model for holes see page 3 195 EXP WATT N turns on exponertial modification to Watt s mobility model for electrons see Equation 3 194 EXP WATT P turns on exponential modification to Watt s mobility model for holes see Equation 3 195 SHLN turns on Shirahata s mobility model for electrons see Equation 3 196 turns Shirahata s mobility model for holes see Equation 3 197 Temperature Dependent Low Field Mobility Parameters MUN see Table 3 16 MUP see Table 3 16 TMUN see Table 3 16 TMUP see Table 3 16 Arora Concentration Dependent Mobility Model Parameters MUIN ARORA see Table 3 19 MUIP ARORA see Table 3 19 MU2N ARORA see Table 3 19 MU2P ARORA see Table 3 19 ALPHAN ARORA
36. DENSITY sets the maximum density of states of the trap level F DENSITY specifies the name of a file containing a C INTERPRETER function describing the density of donor acceptor interface traps as a function of position E LEVEL sets the energy of the discrete trap level It is equal to the energy distance between conductance band and trap level for acceptor trap and to energy distance between trap level and valence band for donor trap 15 44 SILVACO International INTTRAP Statement Statements E level for acceptor trap E level for donor trap Capture Parameters Either the cross section or lifetime parameters should be used to define the capture parameters SIGN speccifies the capture cross section of the trap for electrons SIGP specifies the capture cross section of the trap for holes TAUN specifies the lifetime of electrons in the trap level TAUP specifies the lifetime of holes in the trap level Example setting Multiple Interface Trap States The following example sets three discrete interface trap levels within the silicon bandgap These trap levels will capture carriers slowing the switching speed of any device In this example the capture cross sections are used to define the properties of each trap inttrap e level 0 49 acceptor density 2 e10 degen 12 sign 2 84e 15 sigp 2 84e 14 inttrap e level 0 41 acceptor density 1 e10 degen 12 sign 7 24e 16 sigp 7 24e 15
37. Energy Balance Simulation Flags E TAUR VAR specifies that electron temperature dependent energy relaxation time is used Use parameters IRE T1 TRE T2 TRE T3 TRE W1 TRE W2 and TRE W3 on material statement to specifie the energy relaxation time H TAUR VAR specifies that hole temperature dependent energy relaxation time is used Use parameters TRH T1 TRH T2 TRH T3 TRH W1 TRH W2 and TRH W3 on material statement to specifie the energy relaxation time HCTE specifies that both electron and hole temperature will be solved HCTE EL specifies that electron temperature will be solved HCTE HO specifies that hole temperature will be solved F KSN specifies the name of a file containing a C INTERPRETER function specifying the electron Peltier coefficient as a function of electron energy F KSP specifies the name of a file containing a C INTERPRETER function specifying the hole Peltier coefficient as function of hole energy KSN specifies which hot carrier transport model will be used for electrons KSN 0 selects the hydrodynamic model and KSN 1 selects the energy balance model KSP specifies which hot carrier transport model will be used for holes KSP 0 selects the hydrodynamic model and KSP 1 selects the energy balance model TAUMOB specifies the dependence of relaxation times with carrier temperature in the mobility definition If TAUMOB is specified the values of MATERIAL statement parameters TAUMOB EL
38. Real Real Logical Default Units 4 8 False False False False LHS of device RHS of device 1 1 1 Spectrum log False False False False False 300 K False False 60 0 degrees 60 0 degrees False mf is one or more of the model flags described below Model flags are separated into mobility recombination generation energy balance and lattice heating sections gp is one or more of the general parameters described on page 15 97 These parameters are used to specify general information used during the simulation mdp is one or more of the model dependent parameters described on page 15 100 SILVACO International 15 97 ATLAS User s Manual Volume 2 MODELS Statement Mobility Model Flags Note See the MOBILITY statement for alternative ways to set mobility models ANALYTIC specifies an analytic concentration dependent mobility model for silicon which includes temperature dependence see Equations 3 124 and 3 125 ARORA specifies an analytic concentration and temperature dependent model according to Arora see Equations 3 126 and 3 127 CCSMOB specifies carrier carrier scattering model according to Dorkel and Leturq see Equation 3 128 3 131 CONMOB specifies that a concentration dependent mobility model be used for silicon and gallium arsenide This model is a doping versus mobility table valid for 300K only CVT spec
39. TONYPLOT TONYPLOT starts the graphical post processor TONYPLOT Note The TONYPLOT statement is executed by DECKBUILD and is fully documented in the VWF INTERACTIVE TOOLS MANUAL VOLUME ONE Examples All graphics in ATLAS is performed by saving a file and loading the file into TONY PLOT The command TONYPLOT causes ATLAS to automatically save a structure file and plot it in TONYPLOT The tonyplot window will appear displaying the material boundaries Use the Plot Display menu to see more graphics options This command will display the file myfile str tonyplot st myfile str This command will overlay the results of myfilel str and myfile2 str tonyplot overlay myfilel str myfile2 str Note For documentation of the extensive features of TONYPLOT for graphical display and analysis consult the TONYPLOT chapter of the VWF INTERACTIVE TooLs MANUAL VOLUME ONE 15 146 SILVACO International TITLE Statement Statements TITLE specifies the title up to 29 characters that will appear in the standard output If used the TITLE command should be the first statement inthe ATLAS input file Syntax TITLE lt string gt Example This example causes the text CMOS p channel device to be printed at the top of all ATLAS printouts and screen displays Note TITLE CMOS p channel device TITLE cannot be used with the automatic ATHENA to ATLAS interface feature of DECKBUILD SILVAC
40. jogical Logical Real Real jogical jogica l jogical jogical jogica l Character jogica l jogica l jogica l Real Integer Real Default 1 2 5x10 False 4 61x1077 1 52 1015 1 0 101 6 295x10 False 0 5025 150 0 5 5 0 104 4 6 104 False False False 1 0 2 5x10 False False False False False True False False 4000 0 15 0 0025 Units um V cm SILVACO International 15 93 ATLAS User s Manual Volume 2 MODELS Statement Parameter ERASE ETAN ETAP EVSATMOD FERMIDIRAC FIXED FERMI FLDMOB nj gt nj w 5 F KSP FNORD FNPP GAINMOD ANSCHOM H BENDING HCTE HCTE EL HEAT FULL I lt D O IG ELINR IG HLINR IG ELINF IG HLINF H TAUR VAR HEAT PETHOM Type Logical Real Real Integer jogica l jogical Real Real Real Real Character Character Logical Logical jogical jogical jogica l jogical Logical ijogica jogical jogical jogical Logical Logical Integer Real Real Real Real Default False 0 50 0 33 0 False False False 82 107 90x108 1 82 107 90 10 Fals
41. system command and the UNIX commands are case sensitive UNIX commands may be concatentated on a single line using the semicolon operator For example to run a third party program that reads and writes Silvaco format files with fixed names input str and output str SAV sys E OUTF mysave str tem mv mysave str input str source myprog exe mv output str myrestart str EXT The used Smy RACT INIT INF myrestart str UNIX re direct symbol gt is not supported by the system command The UNIX echo and sed syntax can be instead to output values or variables to a given filename For example to save the extracted value of variable variable to the file myfile system echo myvariable sed n w myfile 15 143 SILVACO International ATLAS User s Manual Volume 2 THERMOCONTACT Statement THERMCONTACT THERMCONTACT specfies the position and properties of thermal contacts This statement must be used when lattice heating solutions are specified using GIGA or GIGA3D Syntax THERMCONTACT NUMBI Parameter ALPHA DEVICE ELEC NUMBER EXT TEMPER NAME NUMBER X MAX X MIN Y MAX Y MIN 2 2 Description At least one thermal contact statement must be specified when simulating lattice heating effects MODE LAT TEMP THERMCONTACT statement must appear in the input deck before any METHOD statement
42. 2 Use Fourier analysis of transient responses for high frequencies when FPDA is not available but transient calculations are possible 14 20 SILVACO International Numerical Techniques Differences Between 2D and 3D Numerics With respect to numerical techniques there are several differences between 2D and 3D simulations First with respect to the nonlinear iteration strategies all three strategies NEWTON GUMMEL and BLOCK are supported in 2D simulation whereas only NEWTON and GUMMEL are supported for 3D simulations mplementation of the BLOCK strategy is expected in a future release Second solution of the linear subproblem is handled differently for 2D and 3D simulations As previously noted the computational burden of solving the linear subproblem increases with the size of the solution domain For smaller problems direct methods are quicker while for larger problems iterative methods are preferred It turns out that the point at which the iterative methods become less burdensome roughly coincides with the transition between 2D and 3D domains As such the default method for 2D simulations is a direct solver For 3D simulations the default method is an iterative solver By default ILUCGS is applied to 3D simulations ILUCGS is an acronym for incomplete lower upper decomposition conjugate gradient squared Two alternative iterative solvers are also available for 3D simulations BICGST BICGST on the METHOD statement is
43. 5 Char 5 Char NTA Real 1 0x1011 1 1 0 1019 cm SIGMAE Real 1 0 1017 omn SIGMAH Real 1 0 101 cm Description NTA specifies the uniform acceptor like trap density on the interface NTD specifies the uniform donor like trap density on the interface SIGMAE specifies the acceptor like trap capture cross section SIGMAH specifies the donor like trap capture cross section F NTA specifies the file name for a C INTERPRETER function that specifies arbitrary density distribution of the acceptor like traps on the interface F NTD specifies the file name for a C INTERPRETER function that specifies arbitrary density distribution of the donor like traps on the interface F SIGMAE specifies the name of a file containing a C NTERPRETER function specifying the distribution of acceptor trap cross sections F SIGMAH specifies the name of a file containing a C INTERPRETER function specifying the distribution of donor trap cross sections MOS Interface State Example DEGRADATION NTA 1 E 12 SIGMAE 5 E 18 This syntax defines a density of acceptor states uniformly distributed along the silicon oxide interface The trapping cross section is also defined Traps will be filled by gate current in transient mode simulations leading to a shift in device parameters 15 20 SILVACO International DOPING Statement Statements DOPING DOPING specifies doping profiles either analyt
44. 5000 nodes oue qd cea Rex awa ous ete Xu sesamiae C 8 C 8 Fine Grid only in Key Areas 2450 nodes C 8 C 9 Id Vds Curves for two MOSFET Meshes C 9 C 10 Breakdown Voltage for Two MOSFET Meshes C 9 C 11 Electric field in MOS gate oxide during a high current pulse on the C 11 C 12 Mobility normalized rolls off as a high gate electric field is C 11 C 13 Using a PROBE of electron concentration allows a study of MOS width effect using 2D simulation An enhanced electron concentration is seen along slice 2 C 12 C 14 3D device simulation of MOS width effect can be performed on structures created ATHENA C 13 SILVACO International xi ATHENA User s Manual Volume 2 This page intentionally left blank SILVACO International List of Tables Table Page No Caption Title No 11 1 User Specifiable Parameters for Equations 11 3 and 11 4 11 5 11 2 User Specifiable Parameters for Equations 11 1 11 2 11 7 and 11 8 11 7 13 1 User Specifiable Parameters For Equations 13 2 to 13 5
45. Volume 2 OUTPUT Statement Parameter Type Default Units U AUGER Logical False U RADIATIVE Logical False U SRH Logical False VAL BAND Logical False VECTORS Logical False Logical True Y COMP Logical False Description BAND PARAM specifies that the band parameters Eg ni Ne Nv and c are included in the standard structure file CHARGE specifies that the net charge will be included in the standard structure file CON BAND specifies that the conduction band edge will be included in the standard structure file DEVDEG causes the distribution of acceptor donor like traps on the interface hot electron hole current density on the interface and trapped electron holes to be written to the structure file E FIELD or EFIELD specifies that total electric field will be included in the standard structure file E LINES specifies the elecrtric field lines will be included in the standard structure file E MOBILITY specifies that electron mobility will be included in the standard structure file E TEMP specifies that the electron temperature will be included in the standard structure file E VELOCITY specifies that the total electron velocity will be included in the standard structure file EIGENS specifies the maximum number of eigen energies and eigen functions to be written to the structure file from a Poisson Schrodinger solution EX FIELD specifies that the x component of electric field will be included in
46. ernationa ATLAS User s Manual DEVICE SIMULATION SOFTWARE Volume Il ti 4701 Patrick Henry Drive Bldg 1 February 2000 5054 Telephone 408 567 1000 FAX 408 496 6080 ATLAS User s Manual Copyright 2000 SILVACO International 4701 Patrick Henry Drive Building 1 Santa Clara CA 95054 Phone 408 567 1000 FAX 408 496 6080 Notice The information contained in this document is subject to change without notice SILVACO International MAKES NO WARRANTY OF ANY KIND WITH REGARD TO THIS MATERIAL INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTY OF FITNESS FOR A PARTICULAR PURPOSE SILVACO International Inc shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material This document contains proprietary information which is protected by copyright All rights are reserved No part of this document may be photocopied reproduced or translated into another language without the prior written consent of SILVACO International Simulation Standard TCADDrivenCAD Virtual Wafer Fab Analog Alliance Legacy ATHENA ATLAS FASTATLAS ODIN VYPER CRUSADE RESILIENCE DISCOVERY CELEBRITY Production Tools Automation Tools Interactive Tools TonyPlot DeckBuild DevEdit Interpreter ATHENA Interpreter ATLAS Interpreter Circuit Optimizer MaskViews PSTATS SSuprem3 SSuprem4 Elite Optolith Flash Sil
47. 2 12 1 08 0 5 6 4 2 0 2 4 6 8 Gate Bias V Click to place P changes alignment or drag to get leader SILVACO International 1995 Figure C 5 High frequency CV curve showing poly depletion effects at positive Vgs TonyPlot V2 4 1 View Plot Tools Print Properties Help ATLAS DEPLETION OF POLYSILICON GATE IN A MOS STRUCTURE 21 VOLTAGE APPLIED HERE THROUGH ELECTRODE ON TOP OF POLYSILICON 20 anan x 7 H 3 T 1 8 8 18 DEFEEHION IN POLY IN SILICON g 8 X 8 8 17 16 POLYSILICON GATE SILICON 15 EPEA m a DON REE Emt APR TEE FAE aE 01 02 0 3 0 4 0 5 Depth microns Click to place P changes alignment or drag to get leader lt DEBUG MODE Figure C 6 Figure 2 Electron concentration profile of an NMOS transistor poly depletion occurs at the poly gate oxide interface C 6 SILVACO International Hints and Tips Question How 1 remesh my process simulation result for device simulation Answer The structure editing and griding tool DEVEDIT provides an effective way to remesh structures between process and device simulation DEVEDIT is able to read and write files to both ATHENA and ATLAS In addition to the graphical user interface DEVEDIT can operate batch mode under DECKBUILD The batch mode DEVEDIT features a powerfu
48. 3 Silicon 1 1 0x1077 5 0x101 5 0x1016 Poly 1 0x107 1 0x107 5 0 1016 5 0 101 The default parameters for Auger recombination are given in Table 8 Table B 8 Auger Coefficient Defaults for Silicon and Poly Material AUGN AUGP Silicon 8 3x1073 1 8 107 Poly 8 3 10732 1 8 10731 SILVACO International B 7 ATLAS User s Manual Volume 2 Silicon and Polysilicon Impact lonization Coefficients The default values for the SELB impact ionization coefficients are given in Table B 9 Table B 9 Impact lonization Coefficients for Silicon and Poly Parameter Value EGRAN 4 0x10 BETAN 1 0 1 0 AN1 7 03x10 AN2 7 03 10 BN1 jo 291107 BN2 1 231 10 1 6 71x10 AP2 1 582x10 1 693x10 BP2 2 036x10 Silicon and Polysilicon Thermal Parameters The default values used for thermal conductivity and capacity are given in Table B 10 Table B 10 Effective Richardson Coefficients for Silicon and Poly Material TCA TCB TCC HCA HCB HCC HCD Silicon 0 03 1 56x10 1 65x10 9 1 97 3 6x1074 0 0 3 7 104 1 0 03 1 56 1073 1 65x10 9 1 97 3 6 1074 0 0 3 7 104 Silicon And Polysilicon Effective Richardson Coefficients B 8 SILVACO International Material Systems Table B 11 Effective Richardson Coefficients for
49. AL2N WATT see Table 3 31 AL2P WATT see Table 3 31 AL3N WATT see Table 3 31 AL3P WATT see Table 3 31 Tasch Mobility Model Parameters RN TAS see Table 3 30 RP TAS see Table 3 30 MUBN TAS see Table 3 30 MUBP TAS see Table 3 30 TMUBN TAS see Table 3 30 TMUBBP TAS see Table 3 30 DN TAS see Table 3 30 DP TAS see Table 3 30 PIN TAS see Table 3 30 P1P TAS see Table 3 30 BIN TAS see Table 3 30 BIP TAS see Table 3 30 P2N TAS see Table 3 30 P2P TAS see Table 3 30 B2N TAS see Table 3 30 B2P TAS see Table 3 30 Z11N TAS see Table 3 30 Z11P TAS see Table 3 30 Z22N TAS see Table 3 30 Z22P TAS see Table 3 30 ESRN TAS see Table 3 30 15 88 SILVACO International MOBILITY Statement Statements ESRP TAS see Table 3 30 BETAN TAS see Table 3 30 BETAP TAS see Table 3 30 N2N TAS see Table 3 30 N2P TAS see Table 3 30 NIN TAS see Table 3 30 NIP TAS see Table 3 30 ALPHAN TAS see Table 3 30 ALPHAB TAS see Table 3 30 Klaassen s Mobility Model Parameters MUMAXN KLA see Table 3 21 MUMAXP KLA see Table 3 21 MUMINN KLA see Table 3 23 MUMINP KLA see Table 3 23 NREFIN KLA see Table 3 22 NREFIP KLA see Table 3 22 ALPHAIN KLA see Table 3 22 ALPHAIP KLA see Table 3 22 THETAN KLA see Table 3 21 THETAP KLA see Table 3 21 CD KLA see Table 3 27 CA KLA see Table 3 27 NREFD KLA see Table 3 27 NREFA KLA see Table 3 27 FCW KLA see Table 3 26 FBH KLA see Table 3 26 SL KLA see Table 3 24 S2 KLA see Table 3 24 S3 KLA see Table
50. C S Rafferty J E Oristian and R W Dutton Velocity Saturation Effect on Short Channel MOS Transitor Capacitance IEEE Electron Device Letters EDL 6 pp 120 122 March 1985 S Tam P K Ko and C Hu Lucky electron Model of Channel Hot electron Injection in MOSFET s IEEE Trans on Electron Devices Vol ED 31 9 September 1984 C R Crowell and S M Sze Current Transport in Metal Semiconductor Barriers Solid State Electronics 9 pp 1035 1048 1966 E Sangiorgi C S Rafferty M R Pinto and R W Dutton Non planar Schottky Device Analysis and Applications Proc International Conference on Simulation of Semiconductor Devices and Processes Swansea U K J uly 1984 C S Rafferty M R Pinto and R W Dutton Iterative Methods in Semiconductor Device Simulation IEEE Trans on Electron Devices E D 32 pp 2018 2027 October 1985 R S Varga Matrix Iterative Analysis Prentice Hall Englewood Cliffs NJ 1962 D L Scharfetter and H K Gummel Large Signal Analysis of a Silicon Read Diode Oscillator IEEE Trans on Electron Devices ED 16 pp 64 77 J anuary 1969 C H Price Two Dimensional Numerical Simulation of Semiconductor Devices Ph D Dissertation Stanford University May 1982 B A Carre Computer J ournal 4 1961 p 73 E M Buturla and P E Cotrell Simulation of Semiconductor Transport Using Coupled and Decoupled Solution Techniques Solid State Electronics 23 No 4 pp 331 334
51. Continuity Equations Convergence Criteria Current Boundary Current Boundary Conditions noe CURVE CUrV ITaCeT Cylindrical Coordinates cttm tente D tat es DeckBuild Defect defect states degener cy ea degradation eerie ten e e eb Density Of States Detection Efficiency DeVE GIB Dit Tieren eed dde Ed d a Device Degradation eb dielectric constant cct cette dilecte tror tt n dipole eer rec rtc ttt nece Direct methods nnns Dirichlet Discretization Displacement Current Distributed Contact Resistance SILVACO International Index 1 ATLAS User s Manual Volumes 1 amp 2 iioc cicer ene cites 5 12 H Drift diffusion Model tcs 32 Haltimplicit Scheme E Heat Capacitance reete per ag an NUS effective 55 2004 4 44 400 a 522 572 f MEME effecti
52. Deman Measurement of the onization Rates in Diffused Silicon p n J unctions Solid State Electronics 13 pp 583 608 1970 W T White et al IEEE Trans on Electron Devices ED 37 p 2532 1990 O S Heavens Optical Properties of Thin Solid Films Dover New York D M Caughey and R E Thomas Carrier Mobilities in Silicon Empirically Related to Doping SILVACO International BIB 1 ATLAS User s Manual 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 andField Proc IEEE 55 pp 2192 2193 1967 S Selberherr Process and Device Modeling for VLSI Microelectron Reliab 24 No 2 pp 225 257 1984 Barnes R J Lomax G I Haddad Finite element Simulation of GaAs MESFET s with Lateral Doping Profiles and Sub micron Gates IEEE Trans on Electron Devices ED 23 pp 1042 1048 September 1976 Littlejohn J R Hauser and T H Glisson Velodity field Characteristics of GaAs with 16 Conduction Band Ordering J Applied Physics 48 11 pp 4587 4590 November 1977 D H Rose and R E Bank Global Approximate Newton Methods Numerische Mathematik 37 pp 279 295 1981 T Wimp Sequence Transformation and their Application Academic Press 1981 D G Anderson Iterative Procedure for Nonlinear Integral Equations ACM J ournal Vol 12 No 4 pp 547 560 H Iwai M R Pinto
53. Hole temperature coeffi cients for impact ioniza tion MATERIAL F TAURN taurn Energy dependent electron relaxation time MATERIAL F TARUP taurp Energy dependent hol relaxation time MODELS F KSN fksn Energy dependent electron Peltier coefficient A 4 SILVACO International C Interpreter Functions Table 15 1 Complete list of available C Interpreter functions in ATLAS Statement Parameter Template Description MODELS F KSP fksp Energy dependent hol Peltier coefficient w D F OXGENERATFE oxgenerate Generation rate as a func tion of position time and field ORCHID DOPING F OXCHARGE oxcharge Position and current dependent net doping ORCHID INTTRAP F INTDONOR intdonor Initial interface donor trap density etc as a function of position INTTRAP F INTACCEPTO intacceptor Initial interface acceptor trap density etc as a function of position INTTRAP F INTPASSIVA intpassivated Initial passivated trap density tec as a func tion of position INTTRAP F INTRATE intrate Interfere passivation rate equation versus proton flux ORCHID MODELS F ALPHAA bulk absorb Bulk absorption coeffi cient versus carrier den sity and photon energy SILVACO International A 5 ATLAS User s Manual
54. IY HIGH IZ HIGH specifies the maximum z value of the grid index IZ LOW pecifies the minimum z value of the grid index MOS Electrode Definition Example This example defines electrodes for a typical MOS structure 0 5 L 0 25 NAME gate 0 25 Y MIN 0 LEE T NAME source H 0 25 Y MIN 0 RIGHT NAME drain LENG LENG SUBSTRATE 3D Electrode Definition Example The following example illustrates electrode defintion for a 3 D structure EL ECTRODE NAM E ANODE X MIN 0 5 X MAX 1 0 Z MIN 0 5 2 1 0 Note In ATLAS it is prefered to refer to functions might require the electrode number The syntax MODELS PRINT can be used to echo electrode numbers to the run time output EL ECTROD ES by name rather than number However some SILVACO International 15 31 ATLAS User s Manual ELIMINATE Statement ELIMINATE ELIMINATE terminates mesh points along lines in a rectangular grid defined within ATLAS in order to reduce the local mesh density Syntax ELIMINATE X DIRECTION Y DIRECTION lt boundary gt Parameter Type Default Units COLUMNS Logical False IX LOW Integer IX HIGH Integer TY LOW Integer IY HIGH Integer ROWS Logical False Real um X MAX Real um Y MIN Real um Y MAX Real um Description
55. NAM E channel mobility x 1 y 0 001 PROBE NAM E channel field x 1 y 0 001 FII N MOB DIR 0 ELD DIR 90 SILVACO International 15 113 ATLAS User s Manual Volume 2 QUIT Statement QUIT QUIT stops execution of ATLAS Syntax QUIT Synonyms END EXIT Description The QUIT statement may be placed anywhere in an input file ATLAS will stop execution upon encountering the QUIT statement All input lines after the occurrence of the QUIT statement will be ignored for that execution of ATLAS Note To quit and immediately restart ATLAS inside of DECKBUILD the GO ATLAS statement should be used Full details on the Go syntax are in the VWF INTERACTIVE TOOLS MANUAL VOLUME ONE 15 114 SILVACO International REGION Statement Statements REGION REGION specifies the location of materials in a previously defined mesh Every triangle must be defined as a material Syntax REGION NUMBER lt n gt lt material gt lt position gt Parameter Type Default Units GRAD 12 Real um GRAD 23 Real mm GRAD 34 Real um GRAD 41 Real um IX LOW Integer left of structure IX HIGH Integer right of structure IY LOW Integer top of structure IY HIGH Integer bottom of structure IZ HIGH Real IZ LOW Real MATERIAL Character NAME Character NUMBER Integer X COMP Real 0 0 Y COMP Real 0 0 X MIN Real left of structure um X MAX Real right of structure Y MIN
56. STEP CONT Logical STEP INIT Real STEPS Real TURNINGPOINT Logical VOLT CONT Logical Default Units 5 10 159 Fal Fal se se Note The curvetracer functionality of ATLAS creates several temporary files in the local directory in which it is run Two simultaneous ATLAS runs using curvetrace in the same directory will interfere with each other Description ANGLE1 ANGLE2 and ANGLE3 are critical angles in degrees affecting the smoothness and step size of the trace If the difference in slopes of the last two solution points is less than ANGLE1 the step size will be increased for the next projected solution If the difference lies between ANGLI difference is greater than ANGLE2 the step size is reduced ANGLI E1 and ANGLE2 the step size remains the same If the E3 is the maximum difference allowed unless overridden by the MINDL parameter ANGLE2 should always be greater than ANGLE1 and less than ANGLE3 BEG VAL is the value of the voltage at the starting point of the curve trace for the controlling electrode CONTR ELEC is the number of the electrode that is designated as a control electrode SILVACO International 15 15 ATLAS User s Manual Volume 2 CURVETRACE Statement CONTR NAME is the name of the control electrode CURR CONT denotes that a maximum current on the control electrode specified by END VAL is used as the upper bound on the trace END
57. The DIR parameters should also be specified if P MOB is used P TEMP specifies that the probe will operate on hole temperature POLARIZATION specifies that the probe will operate on ferroelectric polarization The DIR parameter should also be specified if POLARIZATION is used POTENTIAL specifies that the probe will operate on electrostatic potential QFN specifies that the probe will operate on the electron quasi Fermi level QFP specifies that the probe will operate on the hole quasi Fermi level RAUGER specifies that the probe will operate on Auger recombination rate RECOMBIN specifies that the probe will operate on net recombination rate RRADIATIVE specifies that the probe will operate on radiative recombination rate RSRH specifies that the probe will operate on SRH recombination rate 15 112 SILVACO International PROBE Statement Statements Example of Probing the Maximum Value The following line will cause the maximum electron concentration on the grid to be output to the log file PROBE NAM E peak electrons MAX N CONC Example of PROBE at a location This syntax will cause the potential at the location 0 5 Y 0 1 to be output to the log file PROBE NAM Vector Quantitiy Example E mypotential X 0 5 Y 0 1 POTENTIAL For vector quantities the direction parameter DIR must be specified These two lines allow a lateral mobility and vertical field in a MOSFET PROBE
58. Volume 2 This page intentionally left blank A 6 SILVACO International Appendix B Material Systems Overview ATLAS understands a library of materials for reference to material properties and models of various regions in the semiconductor device These materials are chosen to represent those most commonly used by semiconductor physicists today Users of BLAZE or BLAZE3D will have access to all of these materials S PiscEs or DEVICE3D users will have only access to Silicon and Polysilicon S PISCES is designed to maintain backward compatibility with the standalone program SPISCES2 version 5 2 In the SPISCES2 syntax certain materials could be used in the REGION statement just by using their name as logical parameters This syntax is still supported Semiconductors Insulators and Conductors All materials in ATLAS are strictly defined into three classes as either semiconductor materials insulator materials or conductors Each class of material has particular properties to which all users should be aware Semiconductors All equations specified by the user s choice of models are solved in semiconductor regions All semiconductor regions must have a band structure defined in terms of bandgap density of states affinity etc The parameters used for any simulation can be echoed to the run time output using MODELS PRINT For complex cases with mole fraction dependent models these quantities can be seen in Tonyplot by spe
59. e z lt o 07 Ooo 100000 600000 200000 300000 400000 500000 ELECTRIC FIELD PERPENDICULAR TO CHANNEL Vicm SILVACO International Figure C 12 Mobility normalized rolls off as a high gate electric field is applied SILVACO International C 11 ATLAS User s Manual Volume 2 File v View v Plots Tools Print Properties Help v ATLAS ATLAS LOCATION OF 3 SLICES ACROSS MOS WIDTH SURFACE ELECTRON CONCENTRATION FROM THREE SLICES 12 18 4 4 SLICE2 4 SLICE1 1 18 1 y SLICES E S ten 4 z 4 7 1 g g 6ed7 Xx 1 4 g 4 1 8 4 045 4 h 4 Q 41 1 6272 Y 1 ff 06 4 5 Materials 2 17 1 Silicon 1 5102 1 24 Polysilicon o 5 5 5 5 5 5 5 A 1 Aluminum 08 06 04 02 0 02 04 06 08 I 0 r 15 25 Microns GATE VOLTAGE V SILVACO International Figure C 13 Using a PROBE of electron concentration allows a study of MOS width effect using 2D simulation An enhanced electron concentration is seen along slice 2 Question What are the options for generating 3D structures for ATLAS device simulation Answer Currently there are three options for generating 3D device structures In all cases the prismatic meshing of ATLAS DEVICE3D permits arbitrary shaped device regions in 2 dimensions typically X and Y and rectangular
60. jogica l jogica l jogica l 1 jogica l jogical Default Fal Fal Fal Fal Fal Fal Fal Fal Fal se se LSe LSG LSG LSe LSe se True Fal Fal LSC LSe True Fal True Fal Fal Fal LSG se LSe True Fal Fal Fal True False True Units Volts 15 106 SILVACO International OUTPUT Statement Statements Parameter Type Default Units INAME Character JX ELECTRON iogical False J ELECTRON iogical True JX ELECTRON iogical False J CONDUC jogica l True J DISP Logical False J HOLE Logical True J TOTAL Logical True JX CONDUC jogica l False JX HOLE Logical False JX TOTAL iogical False JY CONDUC jogica l False JY HOLE Logical False JY TOTAL Logical False KSN Logical False KSP Logical False LRATIO Real 1 0 MINSET Logical False N LINES Integer 5 iogical False OX CHARGE iogical False OLD AVG Logical False PERMITTIVITY jogical False PHOTOGEN jogica l True QFN Logical True QFP Logical True QSS Logical False RECOMB Logical True TAURN Logical False TAURP Logical False TOT DOPING Logical False TRAPS Logical True SILVACO International 15 107 ATLAS User s Manual
61. 1 2 1 4 1 3 BA L2 1 B1 B2 1 B3 11 4 where the parameters A1 A2 A4 B1 B2 and B4 are user definable as shown in Table 11 1 SILVACO International 11 5 ATLAS User s Manual Volume 2 Table 11 1 User Specifiable Parameters for Equations 11 3 and 11 4 Statement Parameter Default Units SINGLEEVENTUPSE Al 1 SINGLEEVENTUPSE 2 0 Sie SINGLEEVENTUPSE 0 SINGLEEVENTUPSE 4 0 a SINGLEEVENTUPSE 1 SINGLEEVENTUPSE B2 1 SINGLEEVENTUPSE B3 0 ci SINGLEEVENTUPSE B4 0 Thefactor R r is the radial parameter which is defined by one of two equations The default is R r 11 5 where is the radial distance from the centre of the track to the point and RADIUS is a user definable parameter as shown in Table 11 2 An alternative expression may be chose if the RADIALGAUSS parameter is specified on the SINGLEEVENTUPSET statement In this case R r is given by r 2 R r exp zxprus 11 6 The time dependency of the charge generation T t is controlled by the user with the parameter TC through two functions For Tc 0 T t deltafunction t TO 11 7 For Tc gt 0 T t 11 8 rc nerfc 72 where To and Tc are parameters of the SINGLEEVENTUPSET statement
62. 100 0 HgS HgSe 5500 0 HgTe 22000 0 100 0 PbS 600 0 700 0 PbSe 1020 0 930 0 PbTe 6000 0 4000 0 SnTe ScN GaN 400 0 8 0 2 0x107 AlN 14 0 InN 3000 0 BeTe Notes a Uses Equation B 4 with TMU N 1 66 b Uses Equation B 4 with TMUP 2 33 B 18 SILVACO International Material Systems Insulators The default material parameters for insulator materials are given in the following sections As noted the Semiconductors nsulators and Conductors section the only parameter required for electrical simulation in insulator materials is the the dielectric constant Thermal and optical properties are required GIGA and LUMINOUS respectively Insulator Dielectric Constants Table B 22 Default Static Dielectric Constants of Insulators Material Dielectric Constant Vacuum 1 0 Air 1 0 Ambient 1 0 Oxide 3 9 5102 3 9 Nitride SiN 1525 Si3N4 7 55 Sapphire 12 0 Insulator Thermal Properties Table B 23 Default Thermal Parameters for Insulators Material Thermal Capacity J cm Thermal Conductivity deg cm W Reference Vacuum 0 0 0 0 Air 1 0 0 026 7 Ambient 1 0 0 026 7 Oxide 3 066 0 014 4 5102 3 066 0 014 4 Nitride 0 585 0 185 4 SILVACO International B 19 ATLAS User s Manual Volume 2 Table B 23 Default Thermal Parameters for Insulators Material Thermal Capacity J cm Thermal Conductivi
63. 12 23 34 and 41 These correspond to the point indices around the rectangular region working clockwise from top left e 2 top surface e 23 right hand side e 34 bottom surface e 4 left hand side Position Parameters You may use grid indices to define a region only when the mesh is rectangular To define a region with a rectangular mesh 1 The X MESH and Y MESH statements must be used to specify grid indices 2 The IX HIGH IX LOW IY HIGH and IY LOW parameters may be used to specify x and y mesh line number values Note To add regions to irregular meshes such as those read from ATHENA boundaries must be specified using the X MAX X MIN Y MAX and Y MIN parameters IX HIGH specifies the maximum x value of the grid index IX LOW Specifies the minimum x value of the grid index IY HIGH specifies the maximum y value of the grid index IY LOW specifies the minimum y value of the grid index IZ HIGH specifies the maximum z value of the grid index IZ LOW specifies the mimimum z value of the grid index X COMP is the composition fraction X for a region with a composition dependent cations e g AlGaAs X MAX specifies the maximum x boundary X MIN specifies the minimum x boundary Y COMP is the composition fraction Y for a region with a composition dependent anions e g InGaAsP 15 116 SILVACO International REGION Statement Statements Y MAX specifies the maximum y boundary Y MI
64. 1980 S C Eisenstat M C Gursky M H Schultz A H Sherman Computer Science Department YaleUniv Tech Rep 112 1977 R E Bank and A H Sherman A Refinement Algorithm and Dynamic Data Structure for Finite Element Meshes University of Texas at Austin Technical Report CS TR 159 CNA Tr 166 October 1980 B S Baker E M Grosse and C S Rafferty Non obtuse Triangulation of General Polygons to be published C W Gear Numerical Initial Value Problems in Ordinary Differential Equations Prentice Hall 1971 A De Mari An Accurate Numerical One dimensional Solution of the P N J unction Under Arbitrary Transient Conditions Solid State Electronics 11 pp 1021 1053 1968 BIB 2 SILVACO International Bibliography 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 J Lambert Computational M ethods in Ordinary Differential Equations Wiley 1973 R Bank W M Coughran W Fichtner Grosse D J Rose R K Smith Transient Simulation of Silicon Devices and Circuits IEEE Trans on Electron Devices ED 32 pp 1992 2007 October 1985 S E Laux Techniques for Small Signal Analysis of Semiconductor Devices IEEE Trans on Electron Devices ED 32 pp 2028 2037 October 1985 Polsky and J Rimshans Half Implicit Scheme for Numerical Simulation of Transient Processes in Semic
65. 3 25 5 3 te n tee 15 70 Shockley R ead Hall R 3 60 15 97 Short Circuit Silicon Carbide Silvaco s Virtual Wafer Fab Single Event Upset adobe ree Small signal Small Signal AC occi n 2 14 14 3 15 65 15 121 Index 3 SILVACO International ATLAS User s Manual Volumes 1 amp 2 cce a eciam SOL strettamente tior ite te ato Solar Cells Solution F iles SolutionTolerances acp 15 70 Source PhotoCUfteht oe erect 8 8 Space Charge xa sce tate e tin aan aie rea Ssparalmieter u ecce ce ite meet prebuit beer in dn Spectral Response nennen SPICE SPISCES2 SSUPREM3 Statements Stiffness Stimulated E mission Surface Recombination 3 65 15 11 15 41 SYNTAX 2 5 15 1 T Temperature Dependent Mobility 3 56 termiriation critefia ccrtc ter tec salen cere ete teur 14 8 FT astitit ir i i iil p D E bn fecta 7 1 TET3D Gcr HR 11 2 Thermal Boundary Conditions sse 6 6 Thermal
66. A Intrinsic Concentration Effective Densities of States and Effective Mass in Silicon J Appl Phys V 67 No 6 March 6 1990 Law M E et al Self Consistent Model of Minority Carrier Lifetime Diffusion Length and Mobility IEEE Electron Device Letters Vol 12 Nol 8 1991 Muller R S and Kamins T I Device Electronics for Integrated Circuits 2nd Ed J ohn Wiley and Sons New York 1986 Pejcinovic B et al Numerical Simulation of Semiconductor Devices Springer Verlag Wien New York 1984 Sze S M Physics of Semiconductor Devices 2nd Ed J ohn Wiley and Sons New York 1981 Yoshida J et al Emitter Base Bandgap Grading Effects on GaAlAs GaAs Heterojunction Bipolar Transistor Characteristics IEEE Trans on Elect Devices Vol ED 32 No 9 Sept 1985 Nomenclature of Inorganic Chemistry J ournal of the American Chemistry Society No 82 p 5525 1960 K Mayaram CODECS A Mixed Level Circuit and Device Simulator Memo No UCB ERL 88 71 University of California Berkeley CA K Mayaram and D O Pederson Coupling Algorithms for Mixed Level Circuit and Device Simulation IEEE Transactions on Computer Aided Design Vol 11 No 8 August 1992 pp 1003 1012 Semiconductor device modeling with SPICE Ed by P Antogneti and G Massobrio McGraw Hill Book Company 1987 UTMOST 111 Modeling Manual SILVACO International 1993 Rhoderick E H and Williams R H Metal Se
67. ATLAS allows the user to specify continuation lines To continue a line put a backslash character at the end of the line that is to be continued When ATLAS encounters the backslash it will interpret the next line to be a continuation of the current line The PISCES continuation of using at the start of the subsequent line is not supported in ATLAS Comments Comments are indicated either by COMMENT command or by a pound sign All characters on a line which follow a comment indicator COMMENT or will not be analyzed by ATLAS Synonyms Some parameters have synonyms parameters which have a different name but the same functionality A parameter s synonym if it exists is listed in the parameter descriptions for each statement Pseudonyms Throughout the statement descriptions in the remainder of this chapter pseudonyms are used either to indicate a group of parameters or to indicate the value of a particular parameter A lt symbol indicates the start of a pseudonym s A gt symbol indicates the end of a pseudonym s Pseudonyms will be separated from one another by a space character SILVACO International 15 2 Statement Statements For example LOC might indicate a group of location parameters and FILENAME might indicate the name of a file which must be specified Symbols The following symbols are used in the statement descriptions throughout the rest of this chapter lt Indicates the
68. DEVDEG H activates the device degradation caused by hot hole injection current HHI should also be specified in this case DEVDEG B activates the device degradation caused by both the hot electron and hot hole injection currents HET and HHI should also be specified in this case Note The specification of either DEVDEG E DEVDEG H or DEVDEG B Will initialize the density of electron hole like traps on the interface and will clear out the trapped electron hole density on the interface if any E BENDING specifies that electron band bending will be taken into account for electron injection see Equation 3 279 FNORD selects a self consistent Fowler Nordheim tunneling model see Equation 3 274 This is the recommended approach for calculating Fowler Nordheim current FNPP selects a post processing Fowler Nordheim tunneling model see Equation 3 275 Generally the Fowler Nordheim current does not cause convergence problems so this appraoch is not required H BENDING specifies that hole band bending will be taken into account for hole injection see Equation 3 282 HEI specifies the calculation of hot electron injection into oxides This parameter can be used to simulate MOS gate current or EPROM programming In transient mode the oxide current is self consistently added to the floating gate charge See Equation 3 277 HHI specifies the calculation of hot hole current into an oxide in a similar mann
69. Logical Integer Real Real Real Real Logical Real Real Logical Logical Logical Real Real Real Real Real Logical Real Real Real Real Default False False False False False False All False False False False left of structure right of structure bottom of structure False top of structure Units cm cm um um um um um um um um SILVACO International DOPING Statement Statements Parameter Type Default Units Z FRONT Real Z MIN Real Z MAX Real ZLAT CHAR Real ZSLICE LAT Real ZRATIO LAT Real 0 7 Description The DOPING statement is used to define doping profiles in the device structure Typically a sequence of DOPING statements is given each building on the others OUTFILE specifies the name of an output file for use with REGRID The first DOPING statement should use this parameter to specify a filename All doping information from the first DOPING statement and all subsequent DOP ING statements in the input file are saved to this file The REGRID statement can read this file and interpolate doping on the new grid Note The file from OUTFILE cannot be used in TONPLOT or in the MESH statement The SAVE command should be used after all of the DOPING commands required to save a file for plotting the doping profile Analytical Profile Types These parameters specify how ATLAS will generate a dopi
70. Logical False X Real um Y Real um Description DEVICE specifies which device in mixed mode simulation the probe statement should apply to DIR specifies the direction relative to the x axis in degrees associated with certain directed quantities These quantities include FIELD N MOB P MOB and POLARIZATION Note The algorithm used finds the triangle in the mesh containing the specified X and Y values Then the value of the DIR parameter is used to find which edge of the triangle lies in the direction nearest that value FIELD specifies that a value of electric field is probed The DIR parameter should also be specified if FIELD is used GENERATION specifies that the generation rate due to impact ionization is probed LAT TEMP specifies that the probe will operate on lattice temperature MAX specifies that the probe will find the maximum value on the mesh MIN specifies that the probe will find the minimum value on the mesh NAME sets a character string that allows the user to specify the description displayed by TONYPLOT N CONC specifies that the probe will operate on electron concentration N MOB specifies that the probe will operate on the electron mobility The DIR parameter should also be specified if N MOB is used N TEMP specifies that the probe will operate on electron temperature P CONC specifies that the probe will operate on hole concentration P MOB specifies that the probe will operate on the hole mobility
71. M Yeric A F Tasch and C M Maziar Physically based Models for Effective Mobility and Local field Mobility of Electrons in MOS Inversion Layers to be published S P Gaur and D H Navon Two Dimensional Carrier Flow in a Transistor Structure Under Nonisothermal Conditions IEEE Trans on Electron Devices ED 23 1 pp 50 57 1976 D J Roulston N D Arora S G Chamberlain Modeling and Measurement of Minority Carrier Lifetime versus Doping in Diffused Layers of n p Silicon Diodes IEEE Trans on Electron Devices E D 29 pp 284 291 Feb 1982 A S Grove Physics and Technology of Semiconductor Devices Wiley 1967 S M Sze Physics of Semiconductor Devices Wiley 1981 J W Slotboom The PN Product in Silicon Solid State Electronics 20 pp 279 283 1977 Z Yu Ph D dissertation Stanford Electronic Laboratories Stanford University Z Yu and R W Dutton SEDAN III A Generalized Electronic Material Device Analysis Program Stanford Electronics Laboratory Technical Report Stanford University J uly 1985 W B J oyce and R W Dixon Analytic Approximation for the Fermi Energy of an ideal Fermi Gas Appl Phys Lett 31 pp 354 356 1977 R C J aeger and F H Gaensslen Simulation of Impurity Freezeout through Numerical Solution of Poisson s Equations and Application to MOS Device Behavior IEEE Trans on Electron Devices E D 27 pp 914 920 1980 R Van Overstraeten and
72. More Information Examples using INTERCONNECT3D have been installed on your distribution tape or CD More information about the use of INTERCONNECT3D be found by reading the text associated with each example SILVACO International 12 7 ATLAS User s Manual Volume 2 This page intentionally left blank 12 8 SILVACO International Chapter 13 THERMAL3D Overview THERMAL3D solves the steady state heat equation to find the equilibrium temperature distribution in planar and nonplanar three di mensional structures The user specifies the heat sinks and sources and also chooses from several temperature dependent models for thermal conductivity within each region A typical application for THERMAL3D is a package simulation for a power circuit or 111 ICs Before reading the following sections users are advised to read the 3D device simulation chapter 3D Structure Generation THERMAL3D supports structure defined on 3 D prismatic meshes Structures may have arbitrary geometries in two dimensions and consist of multiple slices in the third dimension There are two methods for creating a 3 D structure that can be used with THERMAL3D Oneis through the command syntax of ATLAS and the other through an interface to b Please see documentation on both of these methods in the DEVI CE 3D chapter Defining Heat Sources Heat sources are identified with regions in the 3D structure Regions are defined in the manner documente
73. NTERPRETER function describing the values of the parameters in Equation 3 239 as a function of hole temperature LENGTH REL specifies the use of energy relaxation length for the impact ionization model with the energy balance model 15 40 SILVACO International IMPACT Statement Statements LREL EL specifies an energy relaxation length for electrons if LENGTH REL 15 specified LREL HO specifies an energy relaxation length for holes if LENGTH REL is specified TAUSN specifies the relaxation time for electrons in the temperature dependent impact model TAUSP specifies the relaxation time for holes in the temperature dependent impac model Concannon Model Parameters CSUB N is an empirical tuning factor used in Concannon s Substrate Current Model eq 3 264 for electrons CSUB P is an empirical tuning factor used in Concannon s Substrate Current Model eq 3 265 for holes ETH N specifies the ionization threshold energy for electrons used in Concannon s Substrate Current Model eq 3 264 specifies the ionization threshold energy for holes used in Concannon s Substrate Current Model eq 3 265 specifies the electron distribution weight factor used in Concannon s Substrate Current Model eq 3 268 CHIA specifies the electron distribution function constant used in Concannon s Substrate Current Model eq 3 268 CHIB specifies the electron distribution function constant used in Concannon s Substrate Current Mod
74. Parameter A TEMP ACC SF ALN1 ALN2 ALN3 ALP1 ALP2 ALP3 ANALYTIC 1 AR MU2N AR MU1P AR MU2P ARORA AUGE A AUGGEN BB A BB B BB GAMMA BBT KL BBT STD BGN BGN SLOTBOOM BIPOLAR BOLTZMANN B ELECTRONS lt gp gt Type Logical Real Real Real Real Real Real Real Logical Real Real Real Real Logical Logical Logical Real Real Real jogical ijogica Logical jogical ijogica Real Default Units False 0 87 0 160 0 296 1 62 False 88 1252 54 3 407 False False False 4 0 101 em M yr gl 1 97x107 en eu eed 235 V cm False False False False False True 15 92 SILVACO International MODELS Statement Statements Parameter B HOLES CO CALC FERMI CAVITY LENGTH CCS CCS B CCS HA CCS HB CCSMOB CHIA CHIB CHI HOLI Gl CONSRH CVT B DORT D DORT N DORT P DORT DEVDEG E DEVDEG H DEVDEG B DEVICE RIFT DIFF BENDING E TAUR VAR ECRIT EIGENS EN I RGY STEP Type Real Real Logical Real Real Real Real Real Logical Real Real Real Real Real jogical
75. Print Properties Help v TonyPlot V2 4 1 ATLAS PHOTOGENERATION RATE WITH ANGLED LIGHT BEAM OXIDE SILICON Microns 5 Microns Printing complete SILVACO International H Figure C 3 Photogeneration contours based on ray trace in Figure C 2 Question What choices of numerical methods are available in ATLAS When should each type of method be used Answer The latest release of ATLAS features more choices of numerical methods for users It also has a new more logical syntax that clears up some of the previously confusing issues with the choice of numerical method for ATLAS solutions ATLAS has the ability to solve up to six equations on the simulation mesh These are the Poisson equation two carrier continuity equations two carrier energy balance equations and the lattice heat flow equation The choice of numerical technique in solving these equations can strongly affect both the convergence and CPU time required to complete a simulation run In general equations can either be solved in a coupled manner with all equations solved at once or a decoupled manner with a subset of the equation solved whilst others are held constant The coupled solutions are best when the interactions between the equations is strong i e high current producing significant local heating However they require a good initial guess to the solution variable
76. Real 522 cm V s MUMINP KLA Real 44 9 cm s NREFIN KLA Real 9 68x16 cm NREFIP KLA Real 223817 cm ALPHAIN KLA Real 0 68 ALPHA1P KLA Real 0 719 THETAN KLA Real 2 285 THETAP KLA Real 2 247 CD KLA Real 0 21 CA KLA Real 0 50 15 82 SILVACO International MOBILITY Statement Statements Parameter NREFD KLA NREFA KLA FCW KLA FBH KLA S1 KLA S2 KLA S3 KLA S4 KLA S5 KLA S6 KLA S7 KLA R1 KLA R2 KLA R3 KLA R4 KLA R5 KLA R6 KLA UON SHI UOP SHI PlP SHI P2N SHI P2P SHI THETAN SHI THETAP SHI Type Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Default Units 4 25 0x20 ems 2x20 eS 459 828 289233 41372 19778 28227 005978 80618 72169 7643 2999 5502 3670 0 8552 0 6478 1430 0 500 0 0 2363 8 0e3 0 77e6 3 9e5 0 28 2 285 2 247 cm V s cm V s V cm V cm V cm V cm SILVACO International 15 83 ATLAS User s Manual Volume 2 MOBILITY Statement Description MATERIAL specifies which material from the table B 1 that the MOBILITY statement should apply to If a material is specified then all regions defined as being composed of that material will be affecte
77. Real top of structure um Y MAX Real bottom of structure m Z MAX Real Z MIN Real Description n specifies a region number from 1 to 200 material is one or more of the material names described below position is one or more of the position parameters described below SILVACO International 15 115 ATLAS User s Manual Volume 2 REGION Statement Material Parameters MATERIAL specifies the material used for the region Valid material names are listed in the table in Appendix materials are divided into three classes semiconductors insulators and conductors See Appendix B for important information about requirements for each material class NAME specifies the name of the region The name can be used in the MODELS MATERIAL and IMPACT statements to provide regionally dependent models This name is just a label any does not imply any material parameter settings NUMBER assigns a region number Multplie REGION lines with the same number can be used to define region shapes made from several rectangles Note If REGION definitions overlap the highest region number takes precedence GRAD lt n gt specifies the compositional gradings for heterojunctions along each side of the region rectangle or quadrillateral The value of the GRAD parameters specifies the distance at which the composition fraction reduces to zero A value of 0 0 specifies that the heterojunction is abrupt The value of lt n gt can be the numbers
78. S PARAM elects s parameter analysis For s parameter analysis the user may also choose to set any of the parasitic element parameters H PARAM selects h parameter analysis Y PARAM selects Y parameter analysis Z PARAM selects z parameter analysis ABCD PARAM selects ABCD parameter analysis GAINS selects the calculation of several types of gains used in RF analysis These are the stability factor unilateral power gain GUmax maximum unilateral transducer power gain GI max maximum available power gain and the maximum stable power gain Gms The magnitude of H21 is also calculated IMPEDANCE specifies the matching impedance for s parameter calculation INPORT specifies the electrode name for the primary input port used when performing any AC parameter calculations IN2PORT specifies the electrode name of the secondary input port SILVACO International 15 49 ATLAS User s Manual Volume 2 LOG Statement OUTPORT specifies the electrode name for the output ports used when performing any AC parameter calculations OUT2PORT specifies the electrode n of the secondary output port Parasitic Element Parameters For RF parameter extraction the user may also set any of the parasitic element parameters By setting the parasitic element parameters the user can apply lumped parasitic resistances or inductances to the terminal of the two port device during the RF parameter extraction These parameters will not affect the
79. SRH lifetime model KSRHTP coefficient for Klaassen s concentration and temperature dependent SRH lifetime model KSRHCN coefficient for Klaassen s concentration and temperature dependent SRH lifetime model KSRHCP coefficient for Klaassen s concentration and temperature dependent SRH lifetime model KSRHGN coefficient for Klaassen s concentration and temperature dependent SRH lifetime model KSRHGP coefficient for Klaassen s concentration and temperature dependent SRH lifetime model KAUGCN coefficient for Klaassen s concentration dependent Auger model KAUGCP coefficient for Klaassen s concentration dependent Auger model KAUGDN coefficient for Klaassen s concentration dependent Auger model KAUGDP coefficient for Klaassen s concentration dependent Auger model NSRHN specifies the SRH concentration parameter for electrons see Equation 3 215 NSRHP specifies the SRH concentration parameter for holes see Equation 3 216 TAUNO specifies SRH lifetime for electrons see Equation 3 215 TAUPO specifies SRH lifetime for holes see Equation 3 216 VTHN specifies the thermal velocity for electrons for use in TRAP recombination VTHP specifies the thermaln velocity for holes for use in TRAP recombination SILVACO International 15 59 ATLAS User s Manual Volume 2 MATERIAL Statement Carrier Statistics Model Parameters ASYMMETRY specifies the relative degree to which band gap narrowing applies to the conduction band versus
80. Simulation When transient simulation is performed the carrier continuity equations are integrated in the time domain Time integration schemes differ in their accuracy in the number of previous time levels they employ and in their stability properties Accuracy is usually referred to as being nth order wheren is usually an integer between 1 and 4 In the limit of a small timestep the magnitude of the local truncation error LTE introduced by the time integration scheme is proportional to the nth power of the timestep Schemes that require the storage of solutions at timesteps previous to the most recent one are unattractive due to storage requirements Single step integration schemes that usethe solution at only one previous time level have a maximum order of 2 The continuity equations are stiff i e they are impacted by phenomena with very short timescales Stiffness imposes stringent requirements on the stability of time integration schemes Two forms of stability A stability and L stability are important A stability guarantees that errors introduced at one time step will not increase at the next timestep L stability guarantees that errors will decay even SILVACO International 14 17 ATLAS User s Manual Volume 2 for large time step values A stability is a requirement for any practical scheme L stability is extremely desirable to avoid non physical ringing Most device simulation codes use a simple first
81. a sinusoidal or square pulse frequency for transient simulations FSTEP specifies a frequency increment which is added to the previous frequency If MULT FREQ is specified the frequency will be multiplied by FSTEP MAX INNER specifies the maximum number of SOR iterations MULT FREQ specifies that the frequency will be multiplied by F STEP instead of added to FSTEP NFSTEPS specifies the number of times that the frequency is to be incremented by FSTEP S OMEGA specifies the SOR parameter This parameter is not the AC frequency SOR selects the SOR AC solution method Although SOR is fast it should only be used when you are performing simulations at low frequencies Low frequency can be defined here as at least an order of magnitude below the cutoff frequency TERMINAL specifies the electrode number to which the AC bias will be applied Although more than one contact number may be specified via concatenation each will be solved separately Each contact that is specified generates a column of the admittance matrix If no TERMINAL is specified all electrodes have AC bias applied in turn See also ANAME TOLERANCE specifies SOR convergence criterion VSS specifies the magnitude of the applied small signal bias The approach used for small signal analysis constructs a linear problem based on derivatives calculated during Newton iterations so adjusing VSS will generally not affect the results loniza
82. all cases The defaults used depend on the particular mobility models in question A full description of each mobility model and their coefficients are given in Chapter 3 Table B 4 contains the silicon and polysilicon default values for the low field constant mobility model Table B 4 Lattice Mobility Model Defaults for Silicon and Poly Material MUN MUP TMUN TMUP cm2 Vs cm Vs Silicon 1000 0 500 0 1 5 125 Poly 1000 0 500 0 l5 11 5 B 6 SILVACO International Material Systems Table B 5 contains the silicon and polysilicon default values for the field dependent mobility model Table B 5 Parallel Field Dependent Mobility Model Parameters for Silicon and Poly Material BETAN BETAP Silicon 2 1 1 2 1 Silicon and Polysilicon Bandgap Narrowing Parameters The default values used in the bandgap narrowing model for 511 and Polysilicon are defined in Table B 6 Table B 6 Bandgap Narrowing Parameters for Silicon and Poly Statement Parameter Defaults Units MATERIAL BGN E 6 92 10 3 V MATERIAL BGN N 1 3 1017 end MATERIAL BGN C Silicon and Polysilicon Recombination Parameters The default parameters for Schockley Read Hall recombination are given in Table 7 Table B 7 SRH Lifetime Parameter Defaults for Silicon and Poly Material TAUNO s TAUPO s NSRHN cm NSRHP
83. any bias ramp is stopped and the program continues withthe next line of the input file The COMPLIANCE parameter is normally specified in A If the GRAD parameter is specified COMPLIANCE is specified in A V 15 132 SILVACO International SOLVE Statement Statements E COMPLIANCE specifies the electrode number to be used by the COMPLIANCE parameter See also CNAME CNAME specifies the name of the electrode used by the COMPLIANCE GRAD specifies that the compliance value is a current voltage gradient and not a current value Transient Parameters CYCLES specifies the number of periods to be simulated both FREQUENCY and TRANS ANALY must be specified when this parameter is used synonym PERIODS CYCLIC BIAS specifies that a cyclic 140 simulation is being performed Cyclic biasing allows the effects of repeated trapazodial square transient pulses see SQPULSE on the output characteristics to be determined without having to do the extremely large numbers of cycles When CYCLIC BIAS is specified ATLAS will calculate a series of trapazodial square pulses using the SQPULSE parameters At the end of the third cycle and at all subsequent cycles the values of the potential V electron concentration n hole concentration p and trap probability of occupation fr will be modified according to the equation 1 x k CY CLIC RELAX x k x k 1 dx k dx k dx k 1 wher
84. are used to set the solution technique specify options for each technique and tolerances for Note Details of the different solution methods can be found in the Numerical Techniques Chapter BLOCK specifies that the block Newton solution method will be used as a possible solution method in subsequent solve statements until otherwise specified The BLOCK method only has meaning when either lattice heating or energy balance is included in the simulation For isothermal drift diffusion simulations BLOCK is equivalent to NEWTON BICGST switches from the default ILUCGS iterative solver to the BICGST interative solver for 3 D simulations DIRECT specifies that a direct linear solver should be used to solve the linear problem during 3 D simulation By default the ILUCGS iterative solver is used for 3 D problems GMRES switches from the default ILUCGS iterative solver to the GMRES interative solver for 3 D simulations GUMMEL specifies the Gummel method will be used as a solution method in subsequent SOLVE statements until otherwise specified If other methods BLOCK or NEWTON are specified in the same method will be applied in succession until convergence is obtained The order tha applied is GUMMEL then BLOCK then NI ETHOD statement each solution t the solution methods will be EWTON If no solution methods are specified NEWTON is applied by default HALFIMPLICIT specifies that a semi implicit scheme will be used for tran
85. be expressed as the simultaneous satisfaction of the following conditions K 1 K I I lt E 14 4 and 3p 0 01 maxi Qr LES 1 1 s where is the current through contact i K is the iteration number and E gt are specified tolerances ncis the number of contacts SILVACO International 14 7 ATLAS User s Manual Volume 2 Summary of Termination Criteria A summary of the termination criteria that is enough for most purposes will now be given Detailed reference information is provided in the next section The non linear iteration is terminated when one of the following four criteria is satisfied 1 TheX norm for every equation falls below a specified tolerance The specified tolerances for X norms are P for potential equation c for concentration equations TE for lattice temperature equation for carrier temperature equation 2 TheRHS for all equations and X norms for energy balance falls below a specified tolerance The specific tolerances are for potential equations for concentration equations r TL for lattice temperature equations TC for carrier temperature equations 3 For every equation either the X norm or the RHS norm falls below a specified tolerance this case both the XNORM and RHSNORM parameters must be specified true 4 f either 1 or 2 or 3 criterion is f
86. bias is now determined as a function of the electrode refered to by COMMON SHORT specifies that the electrode referred to by NAME is shorted to the electrode specified by the COMMON parameter This implies that the two electrodes will be treated as one and only one value will be written to log files and in the run time output FACTOR specifies the constant offset voltage or current between the electrodes refered by by NAME and COMMON By default FACTOR is added the defined voltage MULT specifies that FACTOR is a multiplier Floating Gate Capacitance Parameters In same cases it is desirable to simulate floating gate structures in 2D which have control gates that are longer in the unsimulated dimension than the floating gate In these cases the user can specify the following parameters to account for addition capacitance between the floating gate and the control gate and other electrodes Up to four extra capacitances are allowed so in the following lt n gt is an integer number between and 4 EL lt n gt CAP specifies the name of the electrode to which the extra capacitance is linked FG lt n gt CAP specifies the additional capacitance per unit length to be added between the floating gate and electrode specified in EL lt n gt CAP Schottky Barrier and Surface Recombination Example This example defines all electrodes except number 2 aluminum to be neutral Electrode number 2 also includes finite surface recombina
87. capacitance or conductance matrices calculated by ATLAS RIN specifies the lumped parasitic resistance on the input to the two port device for s parameter extraction The value of RIN isin Ohms ROUT specifies the lumped parasitic resistance on the output to the two port device for s parameter extraction The value of ROUT is in Ohms RGROUND specifies the lumped parasitic resistance on the ground or common side of the two port device for s parameter extraction The value of RGROUND is in Ohms RCOMMON is an alias for RGROUND LIN specifies the lumped parasitic inductance on the input to the two port device for s parameter extraction The value of LIN isin Henrys LOUT specifies the lumped parasitic inductance on the output to the two port device for s parameter extraction The value of LOUT is in Henrys LGROUND specifies the lumped parasitic inductance on the ground or common side of the two port device for s parameter extraction The value of LGROUND is in Henris LCOMMON is an alias for LGROUND SIM TIME saves the time taken for a bias point into the log file and measured in seconds Note that if multiple jobs are using the same cpu that this method may not be a true reflection of processor speed WIDTH specified an output width in z direction to apply during the s parameter calculation Note that this parameter affects only the derived RF parameters and not currents capacitances or conductances The WIDTH parameter of the MESH stat
88. cm Vs SN YAMA Real 350 SP YAMA Real 81 0 VSN YAMA Real 1 036 107 cm s VSP YAMA Real 1 200 107 cm s ULN YAMA Real 4 9x10 cm s ULP YAMA Real 2 928108 cm s ALPHN CVT Real 0 680 ALPHP CVT Real 0 71 BN CVT Real 4 75 107 cm K s BP CVT Real 9 925x10 cm K s Real 2 00 BETAP CVT Real 2 00 CN CVT Real 1 74x10 CP CVT Real 8 842x10 CRN CVT Real 9 68x1019 cm CRP CVT Real 2 23 10 7 CSN CVT Real 3 43x10 9 cm CSP CVT Real 6 10 1020 cm 3 SILVACO International 15 79 ATLAS User s Manual Volume 2 MOBILITY Statement Parameter Type Default Units DELN CVT Real 5 82 1014 V s DELP Real 2 0546 1014 V s CVT Real 25 GAMP CVT Real 2 2 MUON CVT Real 52 2 cm V 8 MUOP CVT Real 44 9 cm s MUIN CVT Real 43 4 cm V 8 U1P CVT Real 29 0 2 5 MUMAXN CVT Real 1417 0 cm V 8 MUMAXP CVT Real 470 5 cm V s PCN CVT Real 0 0 cm PCP Real 0 23 1016 cm TAUN CVT Real Q2 12 5 TAUP CVT Real 0 0317 DEVICE Character MATERIAL Character NAME Character ECRITN Real 4 0 103 V cm ECRITP Real 4 0x10 V cm GAMMAN Real 4 0 GAMMAP Real 1 0 RN TAS Real 2 RP TAS Real 3 MUBN TAS Real 1150 MUBP TAS Real 270 TMUBN TAS Real 5 1 1 4 DN TAS Real 3 2 1077 DP TAS Real 2 35x10 1 5 Real 0 09 15 80 SILVACO International MOB
89. densities as a function of energy F TFTDON specifies the name of a file containing a C INTERPRETER function describing the distribution of donor state densities as a function of energy NGA specifies the total density of acceptor like states in a Gaussian distribution NGD specifies the total density of donor like states in a Gaussian distribution NTA specifies the density of acceptor like states in the tail distribution at the conduction band edge NTD specifies the density of donor like states in the tail distribution at the valence band edge NUMBER or REGION specifies the region index to which the DEFECT statement applies NUMA specifies the number of discrete levels that will be used to simulate the continuous distribution of acceptor states NUMD specifies the number of discrete levels that will be used to simulate the continuous distribution of donor states SIGGAE specifies the capture cross section for electrons in a Gaussian distribution of acceptor like states SIGGAH specifies the capture cross section for holes in a Gaussian distribution of acceptor like states SIGGDE specifies the capture cross section for electrons in a Gaussian distribution of donor like states SIGGDH specifies the capture cross section for holes in a Gaussian distribution of donor like states SIGTAE specifies the capture cross section for electrons in a tail distribution of acceptor like states SIGTAH specifies the capture cross section f
90. developing reliable default convergence criteria for ATLAS The default parameters work well for nearly all situations and most users will never need to change them Error Measures A single positive number that characterizes error is obtained by taking a norm of the errors associated with each unknown The quantity that ATLAS tries to reduce to zero is the difference between the left and right hand sides of the equation It is natural to usethis quantity as the measure of the error The associated error norm is called the right hand side RHS norm The units of the RHS norm are C um for the Poisson equation and A um for the continuity equations Carrier Concentrations and CLIM DD CLIMIT Another measure of error is provided by the size of the calculated corrections for each unknown Since the updates are the unknown xs at each step this is called the X norm Potential updates are measured in units of kT q Updates to carrier concentrations are measured relative to the previous value at the point This relative error is defined as K 1 K Ce c 14 1 e max Co Cm where C n or p for electrons and holes respectively m is the node identifier 14 6 SILVACO International Numerical Techniques is a characteristic concentration K is the iteration number is specified as or as CLIM DD or as CLIM c CLIM DD CLIMT c 14 2 where c 14 3 CLIM DD or CLIMIT is specified
91. different regions D 12 SILVACO International Bibliography 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 Crowell S M Sze Temperature Dependence of Avalanche Multiplication in Semiconductors Applied Physics Letters 9 pp 242 244 1966 W N Grant Electron and Hole Ionization Rates in Epitaxial Silicon at High Electric Fields Solid State Electronics 16 pp 1189 1203 1973 S Selberherr Analysis and Simulation of Semiconductor Devices Springer Verlag Wien New York 1984 Pinto Conor S Rafferty and Robert W Dutton PISCES2 Poisson and Continuity Equation Solver Stanford Electronics Laboratory Technical Report Stanford University September 1984 J T Watt Ph D Thesis Stanford University 1989 S A Schwarz and S E Russe Semi Empirical Equations for Electron Velocity in Silicon Part II MOS Inversion Layer IEEE Trans on Electron Devices ED 30 N12 pp 1634 1639 1983 H Shin Tasch C M Maziar and S K Banerjee A New Approach to Verify and Derive Transverse field dependent Mobility Model for Electrons in MOS Inversion Layers IEEE Trans Electron Devices ED 36 No 6 pp 1117 1123 1989 J T Watt and J D Plummer Universal Mobility Field Curves for Electrons and Holes MOS Inversion Layers presented at 1987 Symposium on VLSI Technology Karuizawa J apan H Shin G
92. double dmde return 0 0 ok Here we see that the function is passed the electric field the saturation velocity and the low field mobility The function returns the field dependent mobility and the derivative of mobility with respect to electric field SILVACO International 1 ATLAS User s Manual Volume 2 Note It is important to properly calculate and return derivative values when specified since the convergence algorithms in ATLAS require these derivatives The return value is an error flag In this case it is set to zero indictating that the function was succesful O OK 1 fail In this example the electron saturation velocity characteristic is changed to one which is akin to that used for holes in silicon This model could be specified by setting the B ELE parameter to 1 but for example purposes the C INTERPRETER function munsat is used instead This will enable comparison between the built in model and the C INTERPRETER model To implement the model two lines additional lines of c code in the body of the function are specified as follows Electron velocity saturation model Statement MATERIAL Parameter F MUNSAT xf e electric field V cm saturation velocity cm s low field mobility cm 2 Vs mu return field dependent mobility cm 2 Vs dmde return derivative of mu with e int munsat double e double
93. e when used alone it specifies ASCII data files containing concentration versus depth information In the second meaning this parameter must be written in the form ASCII INFILE lt filename gt where filename is the name of the ASCII input file The data file must be in the following format depth concentration depth concentration depth concentration where depth is specified in um and concentration is specified in An input file name a dopant type and boundary parameters must be specified Positive concentrations are assumed to be n type and negative concentrations are assumed to be p type unless the N TYPE or P TYPE parameters are used MASTER specifies that the INFILE is written in the Silvaco standard structure file format This file format is the default output format of ATHENA and SSUPREM3 This parameter is typically combined with the SSUPREM3 ATHENA 1D or ATHENA parameters If neither of these are used the default is SSUPREM3 SUPREMG specifies the INFILE was produced by SSUPREM3 in standard structure SSF format or binary or an ASCII export format Export format is an obsolete file format If this profile type is used an input file name a dopant and boundary parameters must be specified When SSU PRE M3 produces an output file the doping profiles are stored by dopant Therefore a dopant parameter should be specified in order to import the correct doping profile into ATLAS If a specific do
94. electron continuity is not being solved If N BIAS is not specified then local quasi Fermi potentials based on bias and doping are used However if FIX OF is set in the METHOD statement quasi Fermi levels will be set to the maximum bias NB lt n gt allows region by region specification of N BIAS The n index corresponds to the region index for which the specified value of electron quasi fermi level applies NAME specifies that the named electrode is to be ramped Custom electrode names are supported by name See also the V lt name gt parameter NSTEPS specifies the number of DC bias increments P BIAS specifies fixed hole quasi Fermi potentials if hole continuity is not being solved If P BIAS is not specified then local quasi Fermi potentials based on bias and doping are used However if FIX OQF is set in the METHOD statement quasi Fermi levels will be set to the minimum bias PB n allows region by region specification of P BIAS The n index corresponds to the region index for which the specified value of hole quasi fermi level applies Q lt name gt specifies the charge on a named electrode These names are as follows gate gg fgate cgate ngate pgate No other user defined names are allowed This parameter is used when floating or charge boundary conditions are selected see the CONTACT statement Q lt n gt specifies the charge on electrode number n It is more usual to use electrode names rather than numbers Thi
95. form a 3D structure using DEVEDIT3D In this mode DEVEDIT3D can be used to add extra regions and doping if required This mode us commonly used for modeling MOS width effects in 3D see Figure C 14 An ATHENA simulation of the isolation bird s beak and field stop implant is performed The 2D structure is loaded into DEVEDIT3D and extended in Z direction The polysilicon gate is truncated in Z and aluminum source drain contacts are added The source drain doping profiles can be read from analytical functions or other process simulation results A worked example named mos2ex04 in is supplied with the Fall 96 release CDROM TONYPLOT3D 2 0 3 Athena to DeveditSD to Atlas Interface 3D MOSFET STRUCTURE Figure C 14 3D device simulation of MOS width effect can be performed on structures created ATHENA For devices with non rectangular regions in the XZ plane such as pillar MOSFETs or cylindrically designed power structures DEVEDIT3D can also be used by drawing in the XZ plane and projecting into the Y direction The future release of Silvacos 3D process device simulator opiN will provide a fourth option for 3D simulation problems ODIN is based on tetrahedral mesh elements and will overcome the mesh restrictions described above SILVACO International C 13 ATLAS User s Manual Volume 2 This page intentionally left blank C 14 SILVACO International Appendix D ATLAS Version Histo
96. hetereojunctions and energy transport This version also does not support compositional variation in the z direction C MixedMode3D e This improvement allows simulation of 3D devices embedded in lumped element circuits MixedMode3D contains all the functionality of 2D MixedM ode simulator d TFT3D e This model allows modeling of poly and amorphous semiconductor devices such as TFTs in 3D This model has all the functionality of the 2D TFT simulator e Quantum3D e This allows modeling of the effects of quantum confinement using the quantum moment approach This model has all the functionality of the 2D Quantum model Orchid Orchid is a new product used in conjunction with SPisces to model the effects of total radiation dosage on MOS devicereliability Key tothis capability is the ability to model the gate oxide as a semiconductor The user may then define carrier pair generation in the oxide as a function of position time and electric fields using a new C interpreter function Another C interpreter function can be used to calculate the cumulative fixed charge density as a function of position and electron and hole current densities in the oxide The deduced fixed oxide charge density directly effects the threshold degradation of the device Introduced SiC e SiC is a new simulation capability for simulating anisotropic materials such as silicon carbide The basis of this model is the incorporation of a new anisotropic mobility mode
97. inganas InGaNAs inGaNP AIGaNAs AIGaNP AllnNAs nNP InA1GaAs InA1GaP and InA1AsP e Added the following new gain output parameters ATLAS will now ouput the maximum available gain Bma as well as the maximum stable gain Gms e Added capability to add sheet charge along region interfaces for simulation of piezoelectric strain effects e Added temperature dependence to the Shirahata mobility model e Added capability for multiple trapazodial square transient pulses e Added a more general parameterized temperature dependent model for saturation velocity for field dependent mobility e Changed the calculation of effective mass used in calculation of thermal velocity for traps in noo silicon materials The new approach calculates mass based on the material density of states SILVACO International D 1 ATLAS User s Manual Volume 2 Version 5 0 0 R 1 4 5 Introduced several new 3D products a Giga3D e Giga3D contains most of the functionality of the 2D Giga but works with 3D products This allows modeling of heatflow and self heating effects in 3D devices The only functionality not supported in this version of Giga3D that is supported in 2D is the BLOCK method b Blaze3D e This version accounts for spatial variations in band gap due to spatial variations in material composition in 3D This version supports all the same models that are supported in Blaze 2D with the exception of thermionic emission at
98. is used to provide a good initial guess to subsequent solutions LOCAL specifies that the initial approximation should use local values of quasi Fermi levels Refer to the Initial Guesses section of the Numerical Techniques Chapter for more detailed information MLOCAL specifies the modified local initial guess This parameter is used when solved for carrier temperatures in the energy balance models If any energy balance model is specified MLOCAL defaults to true PREVIOUS specifies that the previous solution as the initial approximation PROJ specifies that an extrapolation from the last two solutions will be used as an initial approximation This parameter may be used if there are two or more existing solutions and equivalent bias steps are taken on any electrodes that are changed Note If no initial guess parameters are specified ATLAS will use PROJ wherever possible QFACTOR specifies as scaling factor to improve initial guesses when the QUANTUM model is used This parameter should be ramped slowly from zero to unity at the start of quantum effect simulations Compliance Parameters Compliance parameters define a current limit for a DC bias ramp or transient simulation Simulation can be terminated by monitoring the current and checking against a user defined limit COMPLIANCE sets a limit on the current from the electrode which has been specified by the CNAME or E COMPLIANCE parameter When the COMPLIANCE value is reached
99. layout has been correctly entered in to MAsKVIEWS 1 Set the simulator in MAskViEWS to ATLAS Usethe Properties menu to change the simulator to ATLAS Press Save if you want to have ATLAS as the default interface from MASKVIEWS N Press the button write File onthe main MASKVIEWS window Go to the top left of the area of your layout you wish to simulate Press the left mouse key and hold it down Drag the mouse over the area you wish to load into INTERCONNECT3D A new menu will appear with the coordinates of the box you have drawn Enter the name of a cross section file e g myfile sec Press Preview on this menu BL OY wr A graphics window will appear with the mask layout in 3 D Use this to check that your chosen area is correct The resolution of complex mask scan be controlled using the resolution setting under the MASKVIEWS menu Define Screen 8 Press Write A fileis written to your disk This file will be used INTERCONNECT3D Loading Mask Data Into INTERCONNECT3D The section of the layout file saved by MASKViEws should be loaded into ATLAS through the MESH statement in the form MESH NX lt INTEGER gt NZ lt INTEGER gt THREE D LAYFILE lt FILENAME gt Note that the THREE D parameter is required The LAYFILE parameter specifies the name of the file saved by MaskViEWws Most importantly notice that the Ny parameter is not specified on the MESH statement T
100. lines to be calculated Ionization integrals are calculated along each line IONSTOP stops the bias ramp if integral is greater than 1 0 LRATIO specifies the ratio between the starting points of the electric field lines An LRATIO value of between 0 5 and 1 5 is recommended LRATIO 1 means that the spacing between the starting points of the electric field lines is equal LRATIO 1 means more lines start towards the left hand side of the structure LRATIO gt 1 means more lines start towards the right hand side Photogeneration Parameters All these parameters require LUMINOUS to be licensed for correct operation AR INDEX specifies the index of refraction for an antireflective coating AR THICKNESS specifies the thickness in microns of an antireflective coating B lt n gt specifies the optical spot power associated with optical beam number n The beam number must be an integer from 1 to 10 BEAM specifies the beam number of the optical beam when AC photogeneration analysis is performed Unlike the ELECTRODE parameter this parameter can only be used to specify a single beam INDEX CHECK specifies that the real and imaginary refractive indices used in the ray tracing of each beam will be printed to the run time output This parameter can be used as confirmation of the input of user defined refractive indices or to check the default parameters L WAVE specifies the luminous wavelength to use to calculate the luminous powe
101. models are CVT SRH and FERMI PROGRAM specifies a default set of models used when writing to EEPROMS When PROGRAM is specified the MOS HEI and IMPACT models will be used General Parameters DEVICE specifies which device in MIXEDMODE simulation that the MODELS statement should apply to DRIFT DIFF specifies that the drift diffusion transport model is to be used This implies that the electron and hole carrier temperature equations will not be solved MATERIAL specifies which material from the table in Appendix B the MODELS statement should apply to If a material is specified then all regions defined as being composed of that material will be affected NAME specifies in which region the MODELS statement should apply Note that the name must match the name specified in the NAME parameter of the REGION statement PRINT prints the status of all models a variety of coefficients and constants It is recommended to include this parameter in all ATLAS runs SI20 sets a compatibility mode for the materials Si and SiGe with ATLAS versions prior to version 3 0 TEMPERATURE specifies the temperature in Kelvin Model Dependent Parameters ARORA Model Parameters which may be used only with the ARORA model see Equations 3 126 and 3 127 include AR MU1N AR MU2N AR MUIP and AR MU2P BBT KL and BBT STD Models Parameter used with the BBTKL model are BB A1 and BB B Parameters used with the BBT STD model are BB A
102. more complex simulation with energy balance or lattice heating other techniques are also available in ATLAS A mixed technique where the poisson and continuity equations are solved coupled and then the other equations are decoupled can be applied The syntax for this is method block Typically this mixed technique is quicker and more robust at low lattice and carrier temperatures whereas the fully coupled technique is better for high lattice and carrier temperatures The mixed method can be combined very effectively with the fully coupled technique to provide improved speed and convergence for all ranges using method block newton As an example of this Figure C 4 shows the CPU time taken for individual biasing points for a non isothermal energy balance simulation of second breakdown of a sub micron MOSFET The device was constructed using ATHENA and the mesh contains a low number of obtuse triangles not zero The graph clearly shows that at initially the coupled method takes much longer to converge This is because the initial guess is not good until two bias points are solved so that projection can be used As the voltage is increased the block method has increasing convergence difficulty whereas the time taken for the newton method is flat The time for the mixed method has the advantages of block at lower currents but without the severe increases of block The ideal solution for most problems is the use of the mixed block newton meth
103. number of the current solution VOLT CONT denotes that a maximum voltage on the control electrode specified by END VAL is used as the upper bound on the trace Diode Breakdown Example To trace a diode breakdown curve using current value as a termination criteria the following statement may be used CURVETRACE CURR CONT END VAL 0 01 CONTR NAME anode MINCUR 5E 12 NEXTST RATIO 1 1 STEP INIT 0 1 SOLVE CURVETRACE 15 16 SILVACO International DEFECT Statement Statements DEFECT Syntax DEFECTS Parameter AFILE CONTINUOUS DEVICE DF ILE F TFTDON NUMBI 2 NUMA NUMD SIGGA Gl SIGGAH SIGGDI Gl SIGGDH SIGTA Gl SIGTAH SIGTD Gl SOGTDH WGA lt parameters gt Type Character Logical Character Characater Real Real Character Character Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Default True 0 4 0 4 5 0x10 7 1 5x1018 1 12x10 1 4 0 10 11 12 12 0 10714 Los 1 0 10716 08109 0 10714 0 10714 s0x1 0 22 Oat DEFECT activates the band gap defect model and sets the parameter values This model can be used when thin film transistor simulations are performed usi
104. of a previously defined electrode It is recommended that electrode names be used rather than numbers ALL defines the same properties for all electrodes DEVICE specifies which device the CONTACT statement applies to in MIXEDMODE wfp is one of the work function parameters described below It is permitted to either specify the name of a material or a Work function value WORKFUN parameter bc is one or more of the boundary condition parameters ler is one or more of the external parasitic element parameters link is one or more of a set of parameters that allow the user to associate two or more electrodes electrically Workfunction Parameters ALUMINUM specifies aluminum as the contact material for the electrode This sets the workfunction to 4 10V Note that this parameter should not be set if an ohmic contact is required MOLYBDENUM specifies molybdenum as the contact material for the electrode This sets the work function of the electrode to 4 53V MO DISILICIDE specifies molybdenum disilicide as the contact material for the electrode This sets the work function of the electrode to 4 80V NEUTRAL specifies that the electrode is ohmic This is the deafult characteristic of an electrode N POLYSILICON specifies n doped polysilicon as the contact material for the electrode This sets the work function to 4 17V P POLYSILICON specifies p polysilicon as the contact material for the electrode This sets the work function to 4 1
105. of temperature and compostion dependent electron saturation velocity models F VSATP specifies the name of a file containing a C NTERPRETER function for the specification of temperature and compostion dependent hole saturation velocity models GSURE specifies a factor by which mobility is reduced at the semiconductor surface This is a simple but not accurate alternative to the transverse field dependent or surface mobility models set on the MODELS statement MUN specifies low field electron mobility This parameter is only used if no concentration dependent mobility model is specified MUP specifies low field hole mobility This parameter is only used if no concentration dependent mobility model is specified VSATURATION specifies the saturation velocity for the electric field dependent mobility VSATN specifies the saturation velocity for electrons VSATP specifies the satruation velocity for holes Recombination Model Parameters AUGN specifies the Auger coefficient cn see Equation 3 227 AUGP Specifies the Auger coefficient cp see Equation 3 227 15 58 SILVACO International MATERIAL Statement Statements AUGKN parameter of the narrow band gap electron Auger recombination coefficient model AUGKP parameter of the narrow band gap electron Auger recombination coefficient model COPT specifies the optical recombination rate for the material This parameter has no meaning unless MODELS OPTR has been specified see Equ
106. order implicit backward difference formula for time integration This scheme which is known as BDF 1 is both A stable and L stable Unfortunately the scheme is inaccurate for typical timesteps of interest Second order accuracy is obtained using the the trapezoidal rule TR for time integration This scheme is A stable but it is not L stable This means that solutions exhibit non physical ringing unless very small timesteps much smaller than those dictated by LTE considerations used The BDF 2 scheme is second order and both A stable and L stable but it uses solutions from two previous time levels and is alsoless accurate than TR For drift diffusion calculations ATLAS uses a composite TR BDF2 scheme that was developed by Bank et 46 This method is one step second order and both A stable and L stable An estimate of theLTE is obtained at each timestep and this estimate is used to automatically adapt the timestep Different schemes are used for transient solutions that include lattice heating or energy balance If lattice heating is included the block iterative procedure is organized at each time step in the same way as for the steady state case If energy balance is selected the absolutely stable half implicit scheme is used Automatic timestep selection with local error control is implemented in this case The tolerance may be specified using the TOL TIME parameter in the METHOD statement Note The user norma
107. recently computed values Solving this linear subsystem provides corrections for one solution variable One step of Gummel iteration is completed when the procedure has been performed for each independent variable Gummel iteration typically converges relatively slowly but the method will often tolerate relatively poor initial guesses The Gummel algorithm can not be used with lumped elements or current boundary conditions Two variants of Gummel s method can improve its performance slightly These both limit the size of the potential correction that is applied during each Gummel loop The first method called damping truncates corrections that exceed a maximum allowable magnitude It is used to overcome numerical ringing in the calculated potential when bias steps are large greater than 1V for room temperature calculations The maximum allowable magnitude of the potential correction must be carefully 14 4 SILVACO International Numerical Techniques specified too small a value slows convergence while too large a value can lead to overflow The DVLIMIT parameter of the METHOD statement is used to specify the maximum allowable magnitude of the potential correction By default the value of this parameter is 0 1 V Thus by default Gummel iterations are dampped To specify undamped Gummel iterations the user should specify DVLIMIT to be negative of zero The second method limits the number of linearized Poisson solutions per Gummel iterat
108. regions in the other dimension typically Z Definition though the ATLAS syntax This limits the user to defining box shaped regions Region definition is though statements such as region num 1 silicon x min 0 1 y min 0 y max 1 z min 0 z max 1 Mesh generation is handled though the z MESH statement which is analogous to the x MEsH and Y MESH statement used in 2D ATLAS simulations Electrodes and doping can be defined using the same syntax as 2D ATLAS but with z MIN and 2 parameters to control the Z extent Doping profiles can be read from the formats supported in 2D ATLAS ssuprem3 athena ascii e UseDEVEDIT to create a mesh structure DEVEDIT3D is a 3D structure generation and meshing tool used to generate the mesh regions electrodes and doping used in ATLAS DEVEDIT It allows users to draw regions by hand in 2D and project them into the third direction DEVEDIT3D contains all the sophisticated meshing options available to 2D DEVEDIT These include mesh constraints by region mesh constraints by a user defined box refinement on doping and other C 12 SILVACO International Hints and Tips quantities mouse controlled refine and unrefine boxes DEVEDIT3D has both interactive and batch mode operation This is the recommended approach for 3D power device simulation USeATHENA and DEVEDIT3D to extend a 2D process simulation to 3D A 2D process simulation from ATHENA can be extruded to
109. simulations use Amperes micron The solution files produced by 3D ATLAS should be plotted using TONYPLOT3D These files cannot be read directly into the 2D TONYPLOT program TONYPLOT3D contains features that allow slices of the 3D structure to be made which can be plotted in 2D More Information Many examples using 3D ATLAS have been installed on your distribution tape or CD More information about the use of 3D ATLAS can be found by reading the text associated with each example 11 12 SILVACO International Chapter 12 INTERCONNECT3D Overview INTERCONNECT3D solves Laplace s equation in a non planar 3D region It solves for the capacitance between metal conductors or the conductance of metal conductors Before reading this section users should read the Getting Started section Model Description Capacitance and Conductance Calculation Capacitance and conductance analysis in INTERCONNECT3D is based on the solution of the Laplace equation to determine three di mensional potential and electric field distributions Laplace s equation is V nVy 20 12 1 where is electrostatic potential is a parameter that may vary spatially and be discontinuous This parameter corresponds to dielectric permittivity in capacitance calculations and to electrical conductivity in conductance calculations Boundary Conditions Boundary conditions are needed to complete the mathematical specific
110. specifies that optical intensity is included in the standard structure file OX CHARGE specifies that fixed oxide charge is inclued in the standard structure file PERMITTIVITY specifies the dielectric permittivity is saved PHOTOGEN specifies that the photogeneration rate will be included in the standard structure file QFN specifies that the electron quasi fermi level will be included in the standard structure file QFP specifies that the hole quasi fermi level will be included in the standard structure file QSS specifies that the surface charge will be included in the standard structure file RECOMB specifies that the recombination rate will be included in the standard structure file TAURN specifies that electron relaxation times are to be written to any saved structure file specifies that hole relaxation times are to be written to any saved structure file TOT DOPING specifies that total doping will be included in the standard structure file TRAPS specifies that trap density information will be included in the standard structure file U AUGER specifies that the Auger component of recombination is to be written to solution files U RADIATIVE specifies that the radiative component of recombination is to be written to solution files U SRH specifies that the SRH component of recombination is to be written to solution files VAL BAND specifies that the valence band edge will be included in the standard structure file VECTORS specifies tha
111. statement It allows specification of the radial length and time dependence specification of generated charge along tracks Each track is specified by Entry Point x0 y0 z0 E xit Point 1 1 21 and is assumed to be a cylinder with the radius rO The entry and exit points are specified by the ENTRYPOINT and EXITPOINT parameters of the SINGLEEVENTUPSET statement These are characer parameters that represent the ordered triplet coordinates of the entry and exit points of the particle track The electron hole pairs generated at any point is a function of the radial distance r from the centre of the track to the point the distance along the track and the time t This equation takes the form G r t Z DENSITY L1 I S B DENSITY L 2 I R r T t 11 1 where DENSITY is the number of generated electron hole pairs per cm and the other terms are defined as follows If the user defined parameter PCUNITS isset the SINGLEEVENTUPSET statement then B DENSITY is the generated charge in pC um and the scaling factor S is 5 112 qT RADIUS where RADIUS is a user defined parameter on the SINGLEEVENTUPSET statement as shown in Table 11 1 If the parameter PCUNITS is not set then B DENSITY is the number of generated electron hole pairs cm and the scaling parameter S is unity The factor L1 and L2 are defined by the equations L1 l
112. statement Specifying DOPFILE avoids linear interpolation of doping values at newly created grid points by using the initial doping specification to apply doping to the new grid points 15 120 SILVACO International REGRID Statement Statements IN GREEN specifies a triangle tree for the mesh which will be used in this regrid If this parameter is not specified the program will look for a with the same name as the current mesh plus at the end If no such file exists the program will not use a triangle tree for the previous mesh MASTER OUT saves mesh and doping information in a standard structure file format OUTFILE specifies the name of a standard structure output file where mesh information will be stored This parameter must be specified if the mesh is to be used for subsequent runs OUT GREEN specifies the name of the file that holds the history of the triangle tree This history is used in further regrid steps PISCES OUT saves mesh and doping information in a binary PISCES I format Files in this format cannot be displayed in TONY PLOT Doping Regrid Examples Starting with an initial grid we refine twice so that all triangles with large doping steps are refined REGRID LOG DOPING RATIO 6 OUTF gridl DOPF dopxx SMOOTH 4 REGRID LOG DOPING RATIO 6 OUTF grid2 DOPF dopxx SMOOTH 4 A similar effect could be obtained with just one regrid statement REGRID LOG DOPING RATIO 6 OUTF grid2 DOPF dopx
113. the METHOD statement Non linear iteration solution methods are specified in the METHOD statement using the parameters NEWTON GUMMEL Or BLOCK Combinations of these parameters may also be specified order to understand the effect of these parameters it is helpful to briefly review how numerical solutions are obtained The non linear algebraic system that results from discretization on a mesh is solved iteratively starting from an initial guess Linearized subproblems are set up and solved These provide corrections that are used to update the current estimate of the solution Different sequences of linear subproblems correspond to different non linear iteration strategies Iteration continues until convergence criteria are met in which case the solution is accepted or until a preset maximum allowable number of iterations is reached in which case a different technique is tried or the solution procedure is abandoned When a solution fails to converge a user normally tries a different grid a different initial guess strategy or a different non linear iteration technique Newton Iteration Each iteration of the Newton method solves a linearized version of the entire non linear algebraic system The size of the problem is relatively large and each iteration takes a relatively long time However the iteration will normally converge quickly in about three to eight iterations so long as the initial guess is sufficiently close to the
114. the standard structure file EX VELOCITY specifies that the x component of electron velocity will be included in the standard structure file EY FIELD specifies that the y component of electric field will be included in the standard structure file EY VELOCITY specifies that the y component of electron velocity will be included in the standard structure file FLOWLINES specifies that the current flowlines will be included in the standard structure file H MOBILITY specifies that hole mobility will be included in the standard structure file H TEMP specifies that the hole temperature will be included in the standard structure file H VELOCITY specifies that the total hole velocity will be included in the standard structure file HX VELOCITY specifies that the x component of hole velocity will be included in the standard structure file HY VELOCITY specifies that the y component of hole velocity will be included in the standard structure file IMPACT specifies that the impact ionization rate will be included in the standard structure file J CONDUC specifies that the total conduction current density will be included in the standard structure file J DISP specifies that the total displacement current density will be included in the standard structure file J ELECTRON specifies that the total electron current density will be included in the standard structure file 15 108 SILVACO International OUTPUT Statement Statements J HOLE specifies that th
115. v double mu0 double mu double dmde mu mu0 1 04mu0 e v dmde mu mu v return 0 0 ok The function then needs to be stored in a file For example the function may be stored in the file test lib The function is then introduced into a specific example by specifying the file name on the F MUNSAT parameter the MATERIAL statement as follows MATERIAL F MUNSAT test lib When the input deck is executed the user s C INTERPRETER functions will be used in place of the built in function When trying this example it is useful to place print statements using the printf c command in the function to check that the function is working correctly A complete list of all the interpreter functions avialable in ATLAS is given in table 15 1 below Table 15 1 Complete list of available C Interpreter functions in ATLAS Statement Parameter Template Description MATERIAL F MUNSAT munsat Electron velocity satura tion model A 2 SILVACO International C Interpreter Functions Table 15 1 Complete list of available C Interpreter functions in ATLAS Statement Parameter Template Description MATERIAL F MUNSAT mupsat Hole velocity saturation model MATERIAL F BANDCOMP bandcomp Temperatu
116. with 15 144 SILVACO International THERMCONTACT Statement Statements X MIN specifies the left edge of the contact X MAX specifies the right edge of the contact Y MIN specifies the top edge of the contact Y MAX specifies the bottom edge of the contact Z MIN specifies the location of the front edge of the thermal contact Z MAX specifies the location of the rear edge of the thermal contact Coordinate Definition Example A thermal contact is located where y coordinate values range from 10 um to the bottom side of the structure and x ccordinate values range from the left edge of the structure to the right edge of the structure be default The external temperature is set to and a thermal resistance of 1 is added Thus the temperature at y 10 um will be greater than 300K once lattice heating effects occur THERMCONTACT NUM 1 Y MIN 10 EXT TEMP 300 ALPHA 1 Example Setting Thermal and Electrical Contacts Coincident The next statement line creates a thermal contact at the location of electrode 4 An external temperature of 400K is specified THERMCONTACT NUM 2 ELEC NUM 4 EXT TEMP 400 Note Location and Parameters of thermal contacts are not stored in the ATLAS solution files Therefore THERMCONTACT statements must be defined in each ATLAS run involving lattice heating SILVACO International 15 145 ATLAS User s Manual Volume 2 THERMOCONTACT Statement
117. 0 cm s Real 0 0 cm REGION Integer THERMIONIC Logical False X MAX Real right hand side of structure um X MIN Real left hand side of structure um 1 bottom of structure um Y MIN Real top of structure um Z MIN Real um Z Real um Description The INTERFACE statement consists of a set of boundary condition parameters for the interface and a set of parameter to localise the effect of these parameters Boundary Condition Parameters S N specifies the electron surface recombination velocity S P specifies the hole surface recombination velocity QF specifies the fixed charge density CHARGE specifies interface charge density F QF specifies the name of a file containing a C I NTERPRETER function describing the density of the interface fixed charge as a function of position 15 42 SILVACO International INTERFACE Statement Statements THERMIONIC specifies that carrier transport across the interface by determined by thermionic emission See the BLAZE Chapter for details This parameter applied only at semiconductor semiconductor boundaries AR INDEX specifies the real component refractive index for the anti reflective coating model in LUMINOUS This model assumes the imaginary component of refractive index is zero so that the layer is non absorbing This model is only applicable for normal illumination AR THICK specifies the thickness of an anti reflective coating layer for the reflection model in L
118. 1 1994 e Edition 4 October 30 1996 Edition 5 April 30 1997 e Edition 6 November 1998 e Edition 7 February 2000 SILVACO International V ATLAS User s Manual This page intentionally left blank vi SILVACO International Table of Contents Chapter 11 3D Device Simulation E 11 1 Overview of 3D Device Simulation Programs 11 1 Wee pas 11 1 Blaze 3 Shag efe sav SEM 11 1 Giga Di 11 1 TESI is eua epe 11 2 MIXEDMODE3D beh inthis ead ecd obe a Te ER Shins 112 11 2 sro ERA A ied de bbb eatin n 11 2 3D Structure Generation ai disc 50 amie aera SOR A 11 3 ATLAS Syntax For 3D Structure Generation 11 3 ap ch DER ec osa Raa 11 3 Model And Material Parameter Selection in 3D _
119. 11 4 Simulation of Single Event Upset is vee Lk runes he wane e RR xe s kaa amas 11 5 SEM Ifi oua uocat 11 7 Boundary Conditions 3D crossed acid acts ug eoe up ax td 11 7 Ext imal Passive Elements titu oar deo ee dot aut cd doter dns eon 11 7 Thermal Contacts a Ub tante Aca d d Vie tret drin 11 7 Models is oiu rubi EXER equ ER ER 11 8 MOIS tem dd M a ats Rica nd Anar dealer des ace das ac dae 11 8 059 fd os ovd usto dar t 11 8 EUMINOUS 3T Ei Sr Nee Latet EDU DES Bit incense ete MIS pd 11 8 Numerical Methods for 3D 11 12 DC Solutiofls isse CR AU US eC 11 12 Transient Solutions atta Cod ete Ma rad vitae 11 12 Obtaining Solutions In 3D ac neu sp Abacus anion 11 12 Interpreting the Results From 3D 6 od ue tst ue 20s o Lact 11 12 476 d eost scia tat 11 12 Chapter 12 INTERCONNECT enna nae ewan sere 12 1 MI WERT
120. 11 9 11 3 Source beam sampling oorrexi ite ore nl Seed da 11 10 11 4 LUMINOUS3D Lenslet Specification 1 1 11 12 1 The structure to be simulated 12 2 12 2 What INTERCONNECTSD actually simulates 12 2 12 3 Information flow for parasitic extraction from IC layout 12 3 14 1 Load the algorithm used in the Curve 14 17 15 1 LUMINOUS Optical Source Coordinate System 15 5 C 1 Simple trace in LUMINOUS C 2 C 2 Addition of back and sidewall reflection to Figure 1 C 2 C 3 Photogeneration contours based on ray trace Figure 2 C 3 C 4 Comparison of CPU time showing advantages of decoupled methods at low current and coupled methods at higlrcurfents s cea V nates C 4 C 5 High frequency CV curve showing poly depletion effects at positive Vgs C 6 C 6 Figure 2 Electron concentration profile of an NMOS transistor poly depletion occurs at the poly gate oxide interface C 6 C 7 Fine Girid
121. 136 137 138 139 140 Feigna C Venturi F Simple and Efficient Modelling of EPROM Writing IEEE Trans Elect Dev Vol 38 pp 603 610 1991 Cassi C and Ricco B An Analytical Model of the Energy Distribution of Hot Electrons IEEE Trans Elect Dev Vol 37 pp 1514 1521 1990 Wada M et al A Two Dimensional Computer Simulation of Hot Carrier Effects in MOSFETs Proc IEDM Tech Dig pp 223 225 1981 Hall R N Electron Hole Recombination in Germanium Phys Rev 87 pp 387 1952 Shockley W and Read W T Statistics of the Recombination of Holes and Electrons Phys Rev 87 pp 835 842 1952 Beattie A R and White A M An Analytical Approximation with a Wide Range of Applicability for Electron Initiated Auger Transitions in Narrow gap Semiconductors Appl Phys Vol 79 No 12 pp 802 813 1996 G L Bewtra N Lee and Xu J M A Two Dimensional Nonisothermal Finite Element Simulation of Laser Diodes IEEE J ournal of Quantum Electronics Vol QE 29 No 3 pp 822 835 March 1993 Lindefelt U Equations for Electrical and Electrothermal Simulation of Anisotropic Semiconductors J Appl Phys 76 pp 4164 4167 1994 Lades M and Wchutka G Extended Anisotropic Mobility Model Applied to 4H 6H SiC Devices Proc IEEE SISPAD pp 169 171 1997 Yang K East and Haddad G Numerical Modeling of Abrupt Heterojunctions Using a Thermionic F
122. 2 and BB B Parameters BB A1 and 2 are the pre exponential coefficients in the band to band tunneling models The parameter BB B is the exponential coefficient used in both models The default value of BB B depends on which model is chosen see Equation 3 270 CCSMOB Model SILVACO International 15 101 ATLAS User s Manual Volume 2 MODELS Statement The parameters CCS EA CCS EB CCS HA and CCS HB describe the dependendence of mobility on doping carrier concentration and temperature See Equations 3 128 3 131 FLDMOB Model B ELECTRONS is used in the field dependent mobility expression for EVSATMOD 0 see Equation 3 198 B HOLES is used in the field dependent mobility expression for EVSATMOD O see Equation 3 199 EO is used in the field dependent mobility model for EVSATMOD 1 see Equation 5 50 EVSATMOD specifies which parallel field dependent mobility model see Equations 3 198 and 5 50 should be used for electrons as follows 0 Use the standard saturation model 1 Use the negative differtial velocity saturation model 2 Use a simple velocity limiting model In most cases the default value of 0 should be used HVSATMOD specifies which parallel field dependent mobility model see Equations 3 199 and 5 51 should be used for holes as follows 0 Use the standard saturation model 2 Usea simple velocity limiting model In most cases the default value of 0 should be used Fowler Nordhe
123. 2 546 2 546 1 432 10 2 67 10 88 0 54 3 1252 0 407 0 Units Degrees Degrees microns microns microns microns microns microns 15 76 SILVACO International MOBILITY Statement Statements Parameter ALPHAP CAUG BETAN CAUG BETAP CAUG DELTAN CAUG DELTAP CAUG GAMMAN CAUG GAMMAP CAUG NCRITN CAUG NCRITP CAUG MUI1N CAUG U2N CAUG U2P CAUG ALIN WATT AL1P WATT AL2N WATT AL2P WATT AL3N WATT AL3P WATT ETAN WATT ETAP WATT MREFIN WATT REFIP WATT REF2N WATT MREF2P WATT REF3N WATT MREF3P WATT OD WATT N OD WATT P P WATT N Type Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real jogica l ogical ogical Default 1 072x10 7 1 606x10 7 55 24 49 7 1429 23 479 37 0 16 0 296 x 1 07 1 02 481 0 92 8 591 0 124 0 1270 0 534 0 False False False Units SILVACO International 15 77 ATLAS User s Manual Volume 2 MOBILITY Statement Parameter XMINN XMAXN YCHARN WATT YCHARP WATT ETAN AN CCS AP CCS BN CCS BP CCS ANALYT ANALYT ARORA ARORA CONMOB CONMOB CCSMOB CCSMOB FLDM
124. 3 24 S4 KLA see Table 3 24 S5 KLA see Table 3 24 S6 KLA see Table 3 24 S7 KLA see Table 3 24 R1 KLA see Table 3 25 R2 KLA see Table 3 25 R3 KLA see Table 3 25 SILVACO International 15 89 ATLAS User s Manual Volume 2 MOBILITY Statement R4 KLA see Table 3 25 R5 KLA see Table 3 25 R6 KLA see Table 3 25 The Modified Watt Mobility Model Parameters MINN WATT see pege 3 52 MAXN WATT see page 3 52 MAXN WATT see page 3 52 MINP WATT see page 3 52 MAXP WATT see page 3 52 MAXP WATT see page 3 52 YCHARN WATT see page 3 52 YCHARP WATT see page 3 52 X X Y X X Y Shirahata s Mobility Model Parameters MUON SHI see Table 3 32 MUOP SHI see Table 3 32 E1N SHI see Table 3 32 E1P SHI see Table 3 32 E2N SHI see Table 3 32 E2P SHI see Table 3 32 P1N SHI see Table 3 32 P1P SHI see Table 3 32 P2N SHI see Table 3 32 P2P SHI see Table 3 32 THETAN SHI see Table 3 32 see Table 3 32 SCHWARZ and TASCH Transverse Field Dependent Model Parameters ACCN SF specifies the accumulation saturation factor which describes the ratio of the electron concentration in the accumulation layer before and after bending of conductivity and valence bands for electron mobility ACCN SF specifies the accumulation saturation factor which describes the ratio of the hole concentration in the accumulation layer before and after bending of conductivity and valence bands for hole mobility INV
125. 5 110 SILVACO International PROBE Statement Statements PROBE PROBE allows users to output the minimum value maximum value or value at a specified location of any of several distributed quantities to the LOG file The quantities will be saved at each bias point of timestep in the LOG file Note PROBE is the most accurate way to determine the value of many parameters calculated by ATLAS Parameters stored on node points in the structure files for Tonyplot are often interpolated and subject to noise Syntax PROBE MIN MAX X lt n gt Y lt n gt DIR lt n gt POTENTIAL N CONC P CONC N TEMP P TEMP LAT TEMP GENERATION RECOMBINATION Parameter Type Default Units DEVICE Character DIR Real 0 0 degrees FIELD iogical False LAT TEMP iogical False AX iogical False IN iogical False N CONC ogical False N MOB iogical False N TEMP iogical False NAME Character P CONC False P MOB False P TEMP iogical False POLARIZATION iogical False POTENTIAL iogical False QFN 1 False QFP Logical False RAUGER iogical False RECOMBIN iogical False RRADIATIVE ogical False SILVACO International 15 111 ATLAS User s Manual Volume 2 PROBE Statement Parameter Type Default Units RSRH
126. 7V Eg Si TU DISILICIDE specifies tungsten disilicide as the contact material for the electrode This sets the work function to 4 80V SILVACO International 15 11 ATLAS User s Manual Volume 2 Contact Statement TUNGSTEN specifies tungsten as the contact material for the electrode This sets the work function to 4 63V WORKFUN specifies the work function of the electrode in V This parameter must be specified in the form WORKFUN n where n is real number This specification is absolute workfunction and not workfunction difference to the semiconductor Note If no WORKFUN or material type parameter is specified the electrode is assumed to be an ohmic contact Boundary Conditions CURRENT specifies current boundary conditions If specified CAPACITANCE CON RESIST INDUCTANCE or RESISTANCE may not be specified FLOATING specifies a charge boundary condition This parameter is used to specify the floating gate in EPROM devices This parameter can only be used for insulated contacts If specified CAPACITANCE CON RESIST INDUCTANCE or RESISTANCE may not be specified but special syntax exists for adding capacitances to a floating contact See EL lt n gt CAP and FG n CAP Synonym CHARGE ALPHA specifies the linear dipole lowering coefficient This parameter has no effect unless the BARRIER parameter has been specified BARRIER turns on the barrier lowering mechanism for Sc
127. 80 81 82 83 84 85 86 87 88 89 Temperature Doping and Injection Level Solid State Electronics 24 pp 821 825 1981 Hurkx de Graaf W J Klosterman et al A Novel Compact Model Description of Reverse Biase Diode Characteristics including Tunneling ESSDERC pp 49 52 1990 D B M Klaassen Physical Modeling fro Bipolar Device Simulation In Simulation of Semiconductor Devices and Processes Edited by W Fichtner and D Aemmer Harting Gorre 1991 Vol 4 pp 23 43 S Keeney F Piccini M Morelli A Mathewson et al Complete Transient Simulation of Flash EEPROM Devices IEDM Technical Digest pp 201 204 1990 J Sutherland and F Hauser A Computer Analysis of Heterojunction and Graded Composition Solar Cells IEEE Trans E D 24 pp 363 373 1977 M Lundstrom and R Shuelke Numerical Analysis of Heterostructure Semiconductor Devices IEEE Trans ED 30 pp 1151 1159 1983 C M Wu and E S Yang Carrier Transport Across Heterojunction Interfaces Solid State Electronics 22 pp 241 248 1979 R L Anderson Experiments on Ge GaAs Heterojunctions Solid State Electronics Vol 5 pp 341 351 1962 Kernighan and Ritchie The C Programming Language Prentice Hall 1978 Adachi S Physical Properties of Semiconductor Compounds InP InAs GaAs GaP InGaAs and InGaAsP J ohn Wiley and Sons New York 1992 Green Martin
128. A and extend them non uniformly to create 3D structures for ATLAS ATLAS Syntax For 3D Structure Generation Mesh generation The Getting Started chapter covers the generation of 2D and 3D mesh structures using the ATLAS command language The z MESH statement and the Nz and THREE D parameters of the MESH statement are required to extend a 2D mesh into 3D By convention slices are made perpendicular to the Z axis The mesh is triangular in XY but rectangular in XZ or YZ planes Region Electrode and Doping definition The Getting Started chapter covers the definition of 2D regions electrodes and doping profiles In order to extend the regions into 3D the z MIN and z MAX parameters are used For example REGION NUM 2 MATERIAL Silicon X MIN 0 X MAX 1 Y MIN 0 Y MAX 1 Z MIN 0 2 1 ELECTRODE NAME gate 0 1 Y MIN 0 1 2 0 2 1 DOPING GAUSS CONC 1E20 JUNC 0 2 2 0 0 2 1 0 For 2D regions or electrodes defined using the command language geometry is limited to rectangular shapes Similarly in 3D regions and electrodes are composed of rectilinear parallelopipeds DEVE DITS3D Interface DEVEDIT3D is a graphical tool that allows users to draw 3D device structures and create 3D meshes It can also read 2D structures from ATHENA and extend them into 3D These structures can be saved from DEVEDIT3D as structure files for us
129. ANALY Logical False TSTOP Real TWOFILESONLY Logical False V n Real V VFINAL Real V VSTEP Real 0 0 V VSS Real 0 1 V Description Each SOLVE statement must specify an initial bias condition Once any DC condition has been solved either a transient or AC analysis may be performed You may also solve for carrier generation due to incident light under DC or AC analysis transient conditions dc is one or more of the DC bias parameters fp is one or more of the file parameters ep is one or more of the initial guess or estimate parameters Estimate parameters are used to specify how the initial approximation for the solution is to be obtained tp is one or more of the transient parameters These parameters are used to specify data for transient analysis ac is one or more of the AC parameters AC parameters are used to specify data for AC analysis ion is a set of the ionization integral parameters photo is one or more of the photogeneration parameters Photogeneration parameters are used to specify illumination data therm is one or more of the thermal parameters Thermal parameters are used for obtaining solutions in THERMAL3D 15 130 SILVACO International SOLVE Statement Statements DC Parameters CURVETRACE initiates curve tracing See also the CURVETRACE statement ELECTRODE specifies electrodes that you wish to add voltage and current increments VSTEP and ISTEP to Ifn electrodes are to be step
130. AS Real V NAME Character NB1 Real V NB2 Real V NB3 Real V NB4 Real V NB5 Real V NB6 Real V NB7 Real V B NB8 Real V NFSTEPS Integer 0 15 128 SILVACO International SOLVE Statement Statements Parameter NLAYERS NSTEPS ONEFILEONLY OUTFILE P BIAS 1 PB2 PB3 PB4 PB5 PB6 7 PB8 POWER n POWERFINAL PREVIOUS PROJECT PULSE WIDTH O n OFACTOR OFINAL OSTEP RAMPTIM Gl RAMP LIT SCAN SPOT 5 SINUAMP COMP SINUVAR COMP SOR SQPULS Ej SS LIGHT Type Real Integer Logical Character Real Real Real Real Real Real Real Real Real Real Real Logical Logical Real Real Real Real Real Real Logical Real Real Real Real Logical Logical Real Default Units 15 0 See Description V V V V V V V V W W False False S C um 1 0 or previous value C um C um S False 1 0 0 0 0 0 False False 0 001 W cm SILVACO International 15 129 ATLAS User s Manual Volume 2 SOLVE Statement Parameter Type Default Units SS PHOT Logical False T lt n gt Real K 1 0 K T SAVE Real 0 0 5 TDELAY Real 0 0 5 TFALL Real 0 0 S TRISE Real 0 0 S TSAVE MULT Real 1 0 TERMFINAL Real K TERMINAL Integer all contacts TOLERANCE Real 1 0 1072 TRANS
131. ASCH specifies a transverse electric field dependent mobility model for electrons and holes based on a semi empirical equation 7 9 YAMAGUCHI specifies that the Yamaguchi transverse field dependent mobility model is used in the simulation Recombination Model Flags AUGER specifies Auger recombination see Equation 3 227 AUGGEN specifies that the Auger recombination model will be used as a generation term as well as a recombination term CONSRH Specifies Shockley Read Hall recombination using concentration dependent lifetimes see Equations 3 215 and 3 216 KLAAUG enables Klaassen s model for concentration dependent auger coefficients KLASRH enables Klaassen s model for concentration dependent lifetimes for Shockley Read Hall recombination OPTR selects the optical recombination model see Equation 3 226 When this parameter is specified the COPT parameter of the MATERIAL statement should be specified SRH specifies Shockley Read Hall recombination using fixed lifetimes see Equation 3 213 TATUN enables the Klaassen trap assisted tunneling model 15 98 SILVACO International MODELS Statement Statements Generation Model Flags BBT KL specifies a band to band tunneling model according to Klaassen BBT STD specifies a standard band to band tunneling model see Equation 3 270 activates the device degradation caused by hot electron injection current should also be specified in this case
132. B 6 Silicon and Polysilicon Dielectric Properties B 6 Silicon and Polysilicon Default Mobility Parameters B 6 Silicon and Polysilicon Bandgap Narrowing Parameters B 7 Silicon and Polysilicon Recombination Parameters B 7 Silicon and Polysilicon Impact lonization B 8 Silicon and Polysilicon Thermal Parameters B 8 Silicon and Polysilicon Effective Richardson Coefficients B 8 The Al x Ga 1 x As Material System B 10 A1GaAs Recombination Parameters B 10 GaAs and A1GaAs Impact lonization Coefficients B 10 SILVACO International Table of Contents AiGaAs Thermal Parameters B 11 GaAs Effective Richardson Coefficients B 11 The In 1 x Ga x As y P 1 y System B 12 silicon Carbide SiC retur gx Mex ex dais wena E xa bodie eect eae B 14 SiC Thermal Parameters
133. Barrier Lowering Batch Mode BDF dte i a Pu HER Ea cee Bias Steppind iie oculos 15 137 BICGST i tr rer tiec wt 11 8 14 21 15 69 mat Antv eil Y 4 5 6 1 Blize D iini i ni c cao ipe dts 11 1 BLOCK ou etse emm titu 11 8 14 4 15 69 Block Methods eere 2 21 C 4 Boltzmann statistics sess Boltzmann Carrier Statistics Boundary Conditions Breakdowm Breakdown Voltage esee Bulk Absorption 4 Bulk Traps C Capacitance i 12 1 Capture Cross Sections 3 13 7 13 4 4 4 9 Carrier carrier Scattering 1 22 024 4 4000 3 36 CD C Interpreter creer nien trat rtc tr fine 10 1 DD irt ehe fea 14 7 CLM EBS e e coii e 14 7 GEIM IT seccion tier ec reps 2 36 14 7 15 71 Command 2 7 Corments itm o im tera cR 152 Compliance 35 15 ent ade tete ed tad 2 37 15 133 Conductafic8 itecto et deris 12 1 Conduction Band Density sse 15 56 Conductivity Contact Contact Resistance CONTINUATION 0 22 0440 nennen
134. DMODE3SD is an extension of DEvICE3D or BLAZE3D that allows the simulation of physical devices embedded in lumped element circuits Spice circuits MIXEDMODE3D is completely analogous to the MixEDMODE simulator described in the Chapter 10 The complete functionality of the MIXEDMODE simulator is available in MIXEDMODE3D for three dimensional devices QUANTUM3D QuUANTUM3D is an extension of DEvICE3D or BLAZE3D that allows the simulation of the effects of quantum confinement using the quantum transport model see Chapter 3 QUANTUM3D is completely analogous to the QUANTUM model but applies to three dimensional devices LUMINOUS3D LUMINOUS3D is an extension of DEvicE3D that allows the simulation of photodetection in three dimenstions LUMINOUS3D is analogous to the LuMINOUS simulator described in Chapter 8 with a few significant differences described later in this chapter 112 SILVACO International 3D Device Simulation 3D Structure Generation All 3 D programs in ATLAS supports structures defined on 3D prismatic meshes Structures may have arbitrary geometries in two dimensions and consist of multiple slices in the third dimension There are two methods for creating a 3D structure that can be used with ATLAS One is through the command syntax of ATLAS and the other through an interface to DEVEDIT3D A direct interface from ATHENA to 3D ATLAS is not possible however DEVEDIT3D provides the ability to read in 2D structures from ATHEN
135. EE Trans Computer Aided Design V 11 No 9 pp 1114 1119 Sept 1992 Concannon A Piccinini F Mathewson A and Lombardi C The Numerical Simulation of Substrate and Gate Currents in MOS and EPROMS to be published Miller et al Device modeling of ferroelectric capacitors Appl Phys 68 12 15 Dec 1990 Klaassen D B M A Unified Mobility Model for Device Simulation 1 Model Equations and Concentration Dependence Sol St Elec V 35 No 7 pp 953 959 1992 Klaassen D B M A Unified Mobility Model for Device Simulation Temperature Dependence of Carrier Mobility and Lifetime Sol St Elec V 35 No 7 pp 961 967 1992 Klaassen D B M Slotboom J W and De Graaff H C Unified Apparent Bandgap Narrowing in n and p type Silicon Sol St Elec V 35 No 2 pp 125 129 1992 Wang Fundamentals of Semiconductor Theory and Device Physics Prentice Hall Inc p 521 Yu Z Chen D So L and Dutton R W Pisces 2ET Two Dimensional Device Simulation for Silicon and Heterostructures Integrated Circuits Laboratory Stanford University 1994 p 27 Arora N D Hauser J R Roulston Electron and Hole Mobilities in Silicon as a funcion of Concentration and Temperature IEEE Trans Electron Devices E D 29 292 295 1982 Zhou J R and Ferry D K Simulation of Ultra small GaAs MESFET Using Quantum Moment Equations IEEE Trans Electron Device
136. EIE 15 92 Description vaste cad ies dead ters 15 97 Mobility Model Flags 15 98 Recombimatiom Model Flags DER A ORDENA I De a 15 98 Generation 05 15 aea orc pecia chc cote e d aa qucd quic P 15 99 Classical Carrier Statistics Model FlagS 15 99 Quantum Carrier Statistics Model Flags 15 100 Energy Balance Simulation FlagS 15 100 Lattice Heating Simulation FANS sad ce Perens 12 8 15 101 Model Macros RUP MEI NUM Pd 15 101 General doo REIR S Ea er d EOM OD E e LX 15 101 Model Dependent Parameters 15 101 Model Selection Example 2 5 sisse ob ERE ERR ER ERR RED CRAT RE 15 104 Confirming Model Selection 15 104 OPTIONS A NA 15 105 a a does td NR Ants ye dura 15 105 CELA E E boe EE EEN IN d EEEE 15 105 OUTPUT nni a tas A E O E Rms 15 106 eG datar
137. EX INDEX FILE KLASRH KLAAUG KSRHTN KSRHTP KSRHCN KSRHCP KSRHGN KSRHGP KAUGCN KAUGCP KAUGDN KAUGDP LT TAUN LT TAUP ASS VTHN ASS VTHP ATERIAL Type Real Real Real Real Real Real Real Real Character Real Real Real Real Real Real Real Real Real Real Real Real Real Real Character Real Real Character Real Default 1 0 See Appendix B See Appendix B See Appendix B See Appendix B See Appendix B False False 2 5x107 2 5x07 3 0x10 79 11 76x10 i by 0 57 i B3xT0 77 ggg s 1 18 0 72 See Appendix B See Appendix B See Appendix B Units cm J Kcm J K cm J Kem JKcm cm cm 5 cm s cm SILVACO International 15 55 ATLAS User s Manual Volume 2 MATERIAL Statement Parameter NSRHN NSRHP NUE EXTR NUH EXTR NV300 OXCH ONLY PERMITTIVITY TAUMOB Et TAUNO TAUPO TAUREL EL TAUR Tel LC TC CO TC NPOW To TC D TCON CONST TCON POWER TCON POLYNOM TCON RECIPRO TMUN TMUP TRI ERI 1 Real Real Real Real Real Logical Real Real Real Logical Real Real R
138. EX F BGN F CONMUN F CONMUP F COPT F TAUN F TAUP F GAUN and F GAUP In defining new materials there exists a minimum set of parameters that should be defined This set includes bandgap EG300 electron and hole density of states NC300 and NV300 dielectric permitivity PERMITIVITY and electron and hole mobilities MUN and For bipolar devices certain recombination parameters should also be defined such as lifetimes TAUN and TAUP radiative recombination rates and Auger coefficients AUGN and AUGP For devices with variations in material composition certain band edge alignment parameters should also be defined either electron affinity AFFINITY or edge alignment ALIGN If impact ionization is considered the impact ionization coefficients should also be defined As an example consider the case where the user is simulating a device with an AlInGaP region Consulting table B 1 we see that this material system is not defined in ATLAS We then choose a materal that is defined in ATLAS which has default material parameters that best approximate the material parameters of the new material In this case we choose InGaAsP since at least for example purposes we feel that this material is closest to the AlTInGap Next we must specify InGaAsP as the material of the region s that is are composed of AlInGap This can be done either on the REGION statement if the structure is defined in ATLAS syntax or from th
139. EXITPOINT specifies the x y and z coordinates of the end of the alpha particle track The specified point should belong to the semiconductor region PCUNITS sets the units of B DENSITY to be pC per micron RADIALGAUSS specifies the Gaussian radial dependence of the charge generation pulse By default the exponential dependence is used RADIUS specifies the radius of the alpha particle track RESCALE causes nodal generation rates to be scaled by the ratio of the integral of the analytic generation rate divided by the numerically intergrated value NOTE this may cause problems when the track radius approaches device dimensions TFINAL SEU specifies the finish time for the track this defaults to the finish time of the transient simulation if TFINAL SEU is not specified TO specifies the peak in time of the charge generation pulse TC specifies the width of the charge generation pulse UNIFORM specifies that a uniform generation rate corresponding to that specified by the DENSITY parameter is applied SEU Example This statement specifies a track path radius and density SINGLEEVENTUPSET ENTRYPOINT 1 5 2 0 0 0 EXITPOINT 1 0 1 0 4 0 RADIUS 0 05 DENSITY 1E18 Note For user defined Single Event Generation profiles the C INTERPRETER function F3 RADIATE on the BEAM statement can be used 15 126 SILVACO International
140. Either the cross section or lifetime parameters should be used to define the capture parameters SIGN speccifies the capture cross section of the trap for electrons SIGP specifies the capture cross section of the trap for holes TAUN specifies the lifetime of electrons in the trap level TAUP specifies the lifetime of holes in the trap level Multiple Trap Level Definition Example The following example sets three discrete trap levels within the silicon bandgap These trap levels will capture carriers slowing the switching speed of any device In this example the capture cross sections are used to define the properties of each trap trap e level 0 49 acceptor density 2 e15 degen 12 sign 2 84e 15 sigp 2 84e 14 trap e level 0 41 acceptor density 1 e15 degen 12 sign 7 24e 16 sigp 7 24e 15 trap e level 0 32 donor density 1 e15 degen 1 sign 1 00e 16 sigp 1 00e 17 Note For distributed trap levels see the DEFECT statement Note For interface traps see the INTTRAP Statement Note Spatial TRAP distributions in x y or z directions must be defined on the DOPING statement SILVACO International 15 149 ATLAS User s Manual Volume 2 UTMOST Statement UTMOST UTMOST converts data from a ATLAS logfile format into an UTMOST logfile format Note UTMOST 72 3 4 or later can read ATLAS format logfiles directly in batch mode This statement is obsolete and its use is not
141. F P specifies an effective barrier height for holes in the Concannon gate current model 15 102 SILVACO International MODELS Statement Statements THETA N specifies the critical rejection angle for electrons in the Concannon gate current model THETA P specifies the critical rejection angle for electrons in the Concannon gate current model specifies the electron distribution weight factor in the Concannon gate current model CHIA specifies the electron distribution function constant in the Concannon gate current model CHIB specifies the electron distribution function constant in the Concannon gate current model CHLHOLES specifies the hole distribution function constant in the Concannon gate current model ENERGY STEP specifies the energy step for numeric integration in the Concannon gate current model INFINITY specifies the highest energy in numeric integration in the Concannon gate current model PATH N specifies the mean free path in the oxide for electrons in the Concannon gate current model PATH P specifies the mean free path in the oxide for holes in the Concannon gate current model HEI Model Parameters The parameters which may be used with the model include IG ELINR IG HLINR IG ELINF IG HLINF IG EBETA IG HBETA IG EETA IG HETA IG EEOX IG HEOX IG EBO IG HBO N DORT and P DORT Model parameters B DORT user specifiable model parameter for t
142. GER U RADIATIV U SRH U TOTAL X MIN Gl E statement lt boundary gt Type Integer ReallE 8 ogical Real ogical 1 Integer ogical ogical ogical Character ogical ogical Integer Character ogical jogica l jogica ogical Real extracts selected electrical data from the solution OUTFILE lt filename gt Default Fal Fal 15 50 Fal Fal Fal Fal Fal All Fal Fal Fal Fal Left of device lse lse lse se se se se se se se regions se se se se Units um EXTRACT statement SILVACO International 15 63 ATLAS User s Manual Volume 2 MEASURE Statement Parameter Type Default Units Real Right of device um Y MIN Real Top of device um Real Bottom of device um Description dt is one of the data type parameters described on the following page These parameters are used to specify the type of information to be measured boundary is one of the boundary parameters described on page 15 63 These parameters specify which nodes will be measured OUTFILE specifies a filename in which simulation results and bias information will be written Data Type Parameters Net carrier concentration charge concentration elect
143. ILITY Statement Statements Parameter Type Default Units 5 Real 0 334 BIN TAS Real 1 75 5 Real 145 P2N TAS Real 4 53x10 9 P2P TAS Real 3 14x10 7 B2N TAS Real 025 2 5 Real 023 211 5 Real 0 0388 Z11P TAS Real 0 039 Z22N TAS Real 1 73x10 222 5 1 1 51 1075 ESRN TAS Real 2 449x107 ESRP TAS Real 1 0 107 5 Real 2 BETAP TAS Real 1 N2N TAS Real 1 1 1021 2 5 Real 1 4x1018 1 5 Real 2 0x101 5 Real 8 4x1019 ALPHAN TAS Real 2 ALPHAP TAS Real 3 4 BETAN Real 2 30 BETAP Real 1 0 VSATN Real cm s VSATP Real cm s ALPHAN FLD Real 2 4x107 cm s ALPHAP FLD Real 2 4x107 cm s THETAN FLD Real 0 8 THETAP FLD Real 0 8 TNOMN FLD Real 600 0 K SILVACO International 15 81 ATLAS User s Manual Volume 2 MOBILITY Statement Parameter Type Default Units TNOMP FLD Real 600 0 K EVSATMOD Real 0 HVSATMOD Real 0 F CONMUN Character F CONMUP Character F MUNSAT Character F MUPSAT Character F VSATN Character F VSATP Character MUDEG N Real 1 0 MUDEG P Real L0 MUN Real 1420 cm V s MUP Real 1 0 cm V 8 TMUP Real 1 0 TMUN Real 1 0 KLA N 1 False KLA P False SHI N ogical False SHI P False MUMAXN KLA Real 1417 0 cm Vs MUMAXP KLA Real 470 5 0 cm V s UMINN KLA
144. In degenerately doped polysilicon a voltage drop is seen across this region from top to bottom The workfunction difference between the gate and the substrate can be derived from a potential profile through the channel region It is also possible for the polysilicon to be depleted starting at the gate oxide interface Figure C 5 shows a comparison of high frequency CV curves between a MOS device with a uniform degenerately doped poly gate typical when tube doping is used and a lighter non uniformly doped gate typical when source drain implants are used to dope the polysilicon the accumulation region the poly begins to deplete leading to an effectively thicker gate dielectric This effect is illustrated in Figure C 6 The amount of poly depletion observed is dependent on the doping level Accurate polysilicon diffusion models are available in ATHENA to simulate the doping In addition the STLICIDE module allows simulation of the dopant redistribution during gate silicidation Silicides can typically reduce the effective gate doping making poly depletion more likely SILVACO International C 5 ATLAS User s Manual Volume 2 mi TonyPlot V2 4 1 Files View Plot Tools Print Properties Help E ATLAS POLY DEPLETION EFFECT IN MOS CURVE 24 UNIFORMLY DOPED N POLY See 22 4 e E POLY DOPED BY N IMPLANT 8 t 18 RI g E E 15 3 E 14 5
145. ME 15 125 dE aant tasted satus Toten oen E t er a kad 15 126 2 ex aor gea 15 127 eot Mese 15 130 DO Parameters TTE 15 131 File Output Parameters 2 tke CARO E dee dts 15 132 Initial Guess Parameters 15 132 Compliance 5 15 132 ac ea cto b baut la bes ao 15 133 servantes tan ep reat ede es mat aes dd qua hows 15 134 lonization Integral Parameters 15 134 Photogen ration Parameter Ss ura cde deir ct bte ie eal o oet baa rbd Ee ic 15 135 Thermal3D parameters uoces his eene be pr B n ed ub o d out de do 15 136 DC Conditoris EXdIDIB di dante ah ead al uc RO uu de eai deca gis fe 15 136 Bias Stepping Parts te ttis oe parte oris 15 136 Transient Simulation Example 15 136 AC a a ait p dar ac aie 15 137 Photogeneration Examples 23 225 RS AO P OE HER da een
146. N SF specifies the inversion saturation factor which describes the ratio of the electron concentration in the inversion layer before and after the bending of conductivity and valence bands for electron mobility INVN SF specifies the inversion saturation factor which describes the ratio of the hole concentration in the inversion layer before and after the bending of conductivity and valence bands for hole mobility OXBOTTOMN specifies the coordinate of the bottom edge of the gate oxide for a MOSFET transistor for electron mobility 15 90 SILVACO International MOBILITY Statement Statements OXBOTTOMP specifies the coordinate of the bottom edge of the gate oxide for a MOSFET transistor for hole mobility OXLEFTN specifies the coordinate of the left edge of the gate oxide fora MOSFET transistor for electron mobility OXLEFTP specifies the coordinate of the left edge of the gate oxide for a MOSFET transistor for hole mobility OXRIGHTN specifies the coordinate of the right edge of the gate oxide for a MOSFET transistor for electron mobility OXRIGHTP specifies the coordinate of the right edge of the gate oxide for a MOSFET transistor for hole mobility Interpreter Functions F CONMUN specifies the name of a file containing a C INTERPRETER function for the specification of temperature composition and doping dependent electron mobility model F CONMUP specifies the name of a file containing a C INTERPRETER function for the specification
147. N specifies the minimum x boundary Z MIN specifies the minimum z boundary Z MAX specifies the maximum z boundary Grid Inidices Example Define a silicon region extending from nodes 1 to 25 in the x direction and from nodes 1 to 20 in the y direction REGION NUM 1 IX Non Rectangular Region Exampl Define a region which is composed of two effect REGION NUM 1 IX REGION NUM 1 IX Typical MOS Example Define regions for a typical MOS structure REGION NUM 1 Y MAX 0 MATERIAL OXIDE LO 1 IX HI 25 IY LO 1 IY HI 20 MATERIAL SILICON e separate retangular areas Note that region statements are cumulative in LO 4 IX HI 5 IY LO 1 IY HI 20 MATERIAL OXIDE LO 1 IX HI 30 IY LO 1 IY HI 37 MATERIAL OXIDE REGION NUM 2 Y MIN 0 MATERIAL SILICON 3D Region Definition Example Define a cube of oxide within a region silicon in 3D REGION NUM 1 MATERIAL SILICON X MAX 1 0 Z MIN 0 5 Z MAX 1 0 MATERIAL OXID REGION NUM 2 Y MAX 0 5 X MIN 0 5 N Gl Graded Heterojunction Defintion Example Define a graded heterojunction of AlGaAs GaAs REGION NUM 1 MAT ERIAL GaAs Y MIN 1 REGION NUM 2 MAT In this case the area between y 0 9 and 1 0 ERIAL AlGaAs Y MAX 0 9 X COMP 0 2 GRAD 34 0 1 is graded in composition from 0 2 to 0 0 The parameter Y MAX refers to the bottom of the uniform composition region The actual bottom of the AlGaAs region is Y MAX G
148. O International 15 147 ATLAS User s Manual Volume 2 TRAP Statement TRAP TRAP activates bulk traps at discrete energy levels within the bandgap of the semiconductor and sets their parameter values Syntax TRAP DONOR ACCEPTOR E LEVEL lt r gt D Parameter Type ACCEPTOR Logical DEVICE Character DEGEN FAC Real DENSITY Real DONOR Logical E LEVEL Real FAST Logical REGION Integer SIGN Real SIGP Real TAUN Real TAUP Real Description ENSITY lt r gt D Default False undefined False EGEN lt v gt lt capture parameters gt Units cm eV DEVICE specifies which device the statement applies to in MIXEDMODE simulation DONOR specifies a donor type trap level ACCEPTOR specifies an acceptor type trap level REGION specifies which region the traps apply to If unspecified the traps apply to all regions DENSITY sets the maximum density of states of the trap level DEGEN FAC specifies the degeneracy factor of the trap level used to calculate the density E LEVEL sets the energy of the discrete trap level For acceptors E LEV for donors it is relative to the valence band edge EL is relative to the conduction band edge 15 148 SILVACO International TRAP Statement Statements E level for acceptor trap E level for donor trap Capture Parameters
149. OB FLDMOB EXP WATT P WATT WATT WATT WATT WATT WATT IC N IG P N P N SCHWARZ N SCHWARZ P TASCH TASCH MOBMOD MOBMOD N P N sE OLDSURF N Type Logical Real Real Real Real Real Real Real Real Real Real Real Real Real ogica l 1 1 1 1 1 1 1 1 1 1 1 1 1 Real Real Logical Default False 1 0 32 1 0 32 1 0 32 1 0 32 1 0 32 1 0 32 1 0 32 1 0 32 4 61x10 1 0x10 7 1 52 1015 6 25 1014 False False False False False False False False False False False False False False False Units micro micro micro micro micro micro micro micro ns ns ns ns ns ns ns ns 15 78 SILVACO International MOBILITY Statement Statements Parameter Type Default Units OLDSURF P jogica False SURFMOB N 1 False SURFMOB P ogical False ASN YAMA Real 1 541075 cm V ASP YAMA Real 5 35x10 cm V GN YAMA Real 8 8 cm s Real 1 6 cm s NREFN YAMA Real 3 0 1016 em NREFP YAMA Real 4 0x101 cm ULN YAMA Real 1400 0 cm V s MULP YAMA Real 480 0
150. OL RATIO is ignored if Y LOWER is specified Y MIDDLE specifies the physical location in the distorted grid to which the line specified by MIDDLE will be moved Examples This example spreads a uniform 400 of oxide to 1000 on the left side of the device This increases oxide thickness by 600 A Because VOL RATIO is not specified the default 0 44 is used Therefore 0 44 X 600 264 A of the net increase will lie below the original 400 A and 0 56 X 600 336 A of the net increase will lie above the original 400 A The width of the spread region is 0 5 Um and the oxide taper is quite gradual because of the high encroachment factor The grid is left uniform in the spread region Mesh definition ESH NX 30 NY 20 RECT N 1 1 0 N 30 L 5 N 5 1 0 N 20 L 1 R 1 4 Mi X X N 1 1 04 Y Y Thin oxide RI EGION IY H 5 OXIDE NUM 1 15 140 SILVACO International SPREAD Statement Statements d Silicon substrate REGION IY L 5 SILICON NUM 2 Spread SPREAD LEFT W 0 7 UP 1 LO 4 0 1 MID 2 Y MID 0 05 In the second example the right side of the grid is distorted in order to follow a junction contour The initial grid is assumed to be above Y LOWER is used so that there is no increase in the size of the device just grid redistribution When Y LOWER is set to the junction the ENCROACH parameter should be chos
151. OUTA Transient Method Example In this transient simulation example second order discretization is used by default but the required LTE 1073 15 smaller than the default Because the Jacobian is exact for the second part BDF 2 of composite timestep there should be very few factorizations for the BDF 2 interval when AUTONR is specified METHOD NEWTON TOL TIME 1E 3 AUTONR Note For recommendations on METHOD parameters for different simulations see the Getting Started Chapter or the on line examples SILVACO International 15 75 ATLAS User s Manual Volume 2 MOBILITY Statement MOBILITY MOBILITY allows specification of mobility model parameters Syntax MOBILITY Parameter ACCN SF ACCP SF INVN SF INVP SF N ANGLI Gl P ANGLE OXLEFTN OXLEFTP OXRIGHTN OXRIGHTP OXBOTTOMN OXBOTTOMP ALPHAN ARORA ALPHAP ARORA BETAN ARORA BETAP ARORA GAMMAN ARORA GAMMAP ARORA NCRITN ARORA NCRITP ARORA MUIN ARORA U1P ARORA MU2N ARORA MU2P ARORA ALPHAN CAUG NUMBER lt n gt REGION lt n gt MATERIAL lt name gt NAME lt region_name gt lt parameters gt Type Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Real Default 0 87 0 87 0 75 0 75 0 57 0 57 2 33 2 33
152. RAD 34 SILVACO International 15 117 ATLAS User s Man ual Volume 2 REGRID Statement REGRID than a specified criteria Syntax Parameter ABSOLUT Gl ASCII CHANGE COS ANG DOPFILE DOPING E TEMP EL FIELD ELECTRON HOLI IGNOR Gl IN GREEN LOCALDOP LOGARITHM AX LEVEL MIN CARR NET CARR NET PISCES OUT OUT GREEN OUTFILE POTENTIAL QFN QFP Type Logical Logical Logical Real Character Logical Logical Logical Logical Logical Logical Integer Character Logical Logical Integer Logical Logical Logical Logical Character Character Logical Logical Logical EGRID RATIO lt n gt var lt lp gt lt cp gt lt gt Default False False True False False False True 1 maximum level of grid False T value of OUTFILE REGRID allows the user to refine a crude mesh A triangle is refined when the chosen variable changes by more Units cm V cm cm cm cm 15 118 SILVACO International REGRID Statement Statements Parameter Type Default Units REGION Integer All SMOOTH K Integer STEP Real Real Right um 1 Left um Y MAX Real Bottom um Y MIN Real Top um Description RATIO or
153. Recombination 15 97 nr NP 2 41 P Parallel ATEAS x eo ec RE pd 2 3 Parameter Extraction c cincta futt 2 40 e ume ten alant atomis 2 5 15 1 Parasite Element acetate 15 49 Peltier coelficlenE teet E SE 6 8 PNOLOCONGUCIOR t 8 1 8 9 sicco circ inei Photodetectors Photodiodes Photogeneration Photon Density Photon Rate Equations PISCES IL s mara 5 0 2 Poisson S chrodinger PolariZaton iir e Pn en ta ci PoWer Device PREVIOUS Probability Of Occupation PROJECTION voaa mast eec Q Quantum Efficiency see 0 6 8 8 8 13 15 16 Quantum Moments 15 98 Quantum3D Quasi F ermi e e e de Naa R Radiative Direct Recombination Ray e etn ea me esee ar ect te eae Recombirialioni cce Reflection Coefficient sss ReMACIVE ctr cn tn Er n c c rad Refractive Index RHSNORM ee ee ett ies Richardson Constant eene R fi Tiie O UtpUL a c necant casei tieni 5 Saturation Velocity 3 56 15 57 C OL bag 3 31 SChOUKY zia ede duds 2 17 3 24
154. STEP specifies the maximum allowed variance across one element var is one of the variable parameters described below The selected parameter is used as the basis for regridding lp is one of more of the location parameters described below These parameters are used to select the areas which are to be refined cp is one or more of the control parameters These parameters are used to control the plotted output io is one or more of the File I O parameters Variable Parameters DOPING selects net doping E TEMP select electron temperature EL FIELD selects electric field ELECTRON selects electron concentration H TEMP selects hole temperature HOLE selects hole concentration MIN CARR selects minority carrier concentration NET CARR selects net carrier concentration NET CHRG selects net charge POTENTIAL selects mid gap potential QFN selects the electron quasi Fermi level QFP selects the hole quasi Fermi level Location Parameters If no location parameters are specified refinement will include 1 All regions for potential and electric field regrids 2 All semiconductor regions for regrids which depend on the other variables IGNORE specifies regions that are not to be refined SILVACO International 15 119 ATLAS User s Manual Volume 2 REGRID Statement REGION specifies regions which are refined according to the specified critierion Other regions may be refined to maintain well shaped triangles X MAX uses dev
155. Silicon and Poly Material ARICHN 2 2 ARICHP 2 2 Silicon 110 0 30 0 Poly 110 0 30 0 SILVACO International B 9 ATLAS User s Manual Volume 2 The 1 Material System AlGaAs Recombination Parameters The default recombination parameters for AlGaAs are given in Table B 12 Table B 12 Default Recombination Parameters for AlGaAs Parameter Value Equation TAUNO 1 0 1077 3 213 TAUPO 1 0 1078 3 213 1 5 10719 3 226 AUGN 5 0x1073 3 227 AUGP 1 0 10 31 3 227 GaAs and AlGaAs Impact lonization Coefficients The default values for the 51 AlGaAs uses the same values as GaAs Table B 13 Impact lonization Coefficients for GaAs Parameter Value EGRAN 0 0 BETAN 1 82 BETAP 1 75 EGRAN 0 0 AN1 1 889x10 AN2 1 889x10 BNI 5 75x10 BN2 5 75x10 AP1 2 215 10 2 2 215 10 1 6 57x10 2 6 57 105 ELB impact ionization coefficients used for GaAs are given in Table 13 B 10 SILVACO International Material Systems AlGaAs Thermal Parameters The default thermal parameters used for AlGaAs are given in Table B 14 Table B 14 Default Thermal Parameters for GaAs Parameter Value TCA 2227 1 738 GaAs Effective Richardson Coefficients The default values for the effective Richa
156. T rgummel routine ROUTINE 29 specifies vs Vgc plot Each input file holds I V data for a solution with a fixed base current and Vgc stepped UTMOST IE VEC routine MOS Technology ROUTINE 1 specifies a Ip vs plot Vg is constant and is stepped UTMOST ID VD VG routine ROUTINE 2 specifies a Ip vs Vgs plot Vp is constant and Vg is stepped UTMOST ID VG VB routine ROUTINE 3 specifies the Leff Rsd routine Two devices of different lengths are needed The Ip V s data should be used ROUTINE S specifies a Ip vs Vgs plot Vp is constant and 0 UTMOST VTH routine ROUTINE 9 specifies a Ip vs plot Vp is constant and Vg is stepped UTMOST NSUB routine ROUTINE 10 specifies the IS routine The forward diode characteristics of the drain to bulk junction are required ROUTINE 11 specifies the LAMBDA routine An Ip Vp curve is required 15 152 SILVACO International UTMOST Statement Statements ROUTINE 12 specifies the ETA routine A set of Ip Vgs data for different VDS is required ROUTINE 13 specifies the VMAX routine set of Ip V gs curves for small changes in Vpg are required ROUTINE 14 specifies the UO routine set of Ip Vgs data is required ROUTINE 26 specifies a Ip vs Vgs plot Vg is constant and Vp is stepped UTMOST ID VG VD routine MOS Capacitances The following routines may be specified if both MOS and AC parameters are selected ROUTINE 1 specifies the CGSO routine Cos v
157. TEP and NFSTEPS determine the frequencies for which solutions are obtained FREQUENCY specifies the initial frequency FSTEP and NFSTEPS define a loop on frequencies If MULT FREQ is specified the frequency is multiplied by FSTEP at each increment This is useful for characterizing the small signal response over several decades of frequency The solution method can be specified using the SOR DIRECT and AUTO parameters AUTO starts out using SOR but switches to DIRECT if convergence problems are encountered Fourier Analysis Of Transient Responses FATR is a post processing step which must be performed on a roc file which contains transient data The FOURIER statement performs a Fast Fourier Transform FFT on the time domain data transforming it into the frequency domain The syntax of the FOURIER statement is shown in Table 14 2 Table 14 2 User Specifiable Parameters for Equation 9 2 Statement Parameter Default FOURIER INFILE FOURIER OUTFILE FOURIER START FOURIER STOP FOURIER FUNDAMENTAL FOURIER MAX HARMONIC FOURIER NUM SAMPLES 64 FOURIER INTERPOLATE FALSE FOURIER COMPLEX VALUES FALSE The explanation for the FOURIER parameters are as follows NFILE input log file This should contain data from a transient simulation OUTFILE file output filefor the Fourier tra
158. The ELIMINATE statement is used to remove points along every other line within the chosen range Successive eliminations of the same range remove points along every fourth line For horizontal elimination the vertical bounds should be decreased by one at each re elimination of the same region For vertical elimination the horizontal bounds should be decreased by one at each re elimination of the same region ROWS or X DIR eliminates points along horizontal lines COLUMNS or Y DIR eliminates points along vertical lines Boundary Parameters X MIN X MAX Y MIN and Y MAX specify the location of the boundaries of an area in user coordinates where the elimination is applied The following are provided for backward compatibility only Their use is not recommended IX HIGH specifies the mesh line number high boundary in the x direction IX LOW specifies the mesh line number low boundary in the x direction IY HIGH specifies the mesh line number high boundary in the y direction IY LOW specifies the mesh line number low boundary in the y direction 15 32 SILVACO International ELIMINATE Statement Statements Substrate Mesh Reduction Example This example removes vertical points between the depth of 10Um and 20 ELIM ELIM Y DIR Y MIN 10 Y MAX 20 X MIN 1 X MAX 8 Y DIR Y MIN 10 Y MAX 20 X MIN 1 X MAX 7 Note In some cases applications of the ELIMINATE statement can cause internal inconsistencies in the mesh Whe
159. This model accounts for redistribution of carriers near abrupt material transitions due to the effects of quantum confinement It is also useful when simulating heterojunction devices such as HBTs and HEMTs as well as short channel thin gate oxide MOS devices 2 Introduced Improvements to the Ferroelectric Model This release includes modifications which allow better modeling of unsaturated loop simulation of ferroelectric materials It also includes the capability to characterize the AC ferroelectric permitibity affected by the polarization as a fraction of the DC case 3 Log File Improvements have been Made for Capturing Data PROBE has been enhanced to add the capability of probing minimums and maximums of the directional quantities electric field electron mobility hole mobility and polarization PROBE has been enhanced to allow the measurement of dielectric permitivity and the band to band tunneling rate Added the capability to capture simulation time in the log file D 4 SILVACO International ATLAS Version History 4 Structure File Improvements The default method of averaging for capture of impact ionization rate the electron and hole mobilities to the structure file has been changed The new averaging techniques provide smoother plots in TonyPlot 5 Improved Parameterization of Band to Band Tunneling Models This release allows user accessibility to the gamma parameter of the standard band to band tunneling mod
160. UMINOUS This layer should generally not exist in the device mesh structure Position Parameters X MIN Y MIN and Y MAX define a bounding box Any semiconductor insulator interfaces found within this region are charged If there is only one interface in a device a nonplanar surface may be defined using a box which contains the whole device X MIN specifies the left x coordinate of the bounding box X MAX specifies the right x coordinate of the bounding box Y MIN specifies the bottom y coordinate of the bounding box Y MAX specifies the top y coordinate of the bounding box Z MIN specifies the front z coordinate of the bounding box It is used in 3 D modules only Z MAX specifies the back z coordinate of the bounding box It is used in 3 D modules only DEVICE specifies which device in a MIXEDMODE simulation the statement applies to REGION specifies which the region number the statement applies to MOS Example This example defines an interface with both fixed charge and recombination velocities INTERFACE X MIN 4 X MAX 4 Y MIN 0 5 Y MAX 4 N 1 10 S N 1E4 S P 1E4 SOI Example To define different fixed charge on the front and back interfaces of an SOI transistor two INTERFACE statements are required In the syntax below the first statement will apply 5 1019 cm charge to any silicon oxide interface above 0 01 The second statement applied a higher charge to any interface below Y 0 01um Not
161. UTMOST file format APPEND specifies that I V data should be appended to the output file specified by OUTFILE2 WIDTH is used to specify the width of the device Electrode current is multiplied by the value of WIDTH before being saved in the logfile Technology Parameters BIP creates an UTMOST bipolar transistor log file DIODE creates an UTMOST diode log file MOS creates an UTMOST MOSFET log file MESFET creates an UTMOST MESFET log file Electrode Parameters Different electrode parameters may be specified with different technologies BIP Technology BASE specifies the base electrode number COLLECTOR specifies the collector electrode numb EMITTER specifies the emitter electrode numb POLARITY indicates the device type Polarity 1 specifies npn Polarity 1 specifies pnp MOS And MESFET Technologies Note If you have used the NAME parameter of the ELECTRODE statement to assign standard electrode names bulk drain gate and source it is not necessary to re specify these names in the UTMOST statement BULK or SUBSTRATE specifies the bulk electrode number DRAIN specifies the drain electrode number SILVACO International 15 151 ATLAS User s Manual Volume 2 UTMOST Statement GATE specifies the gate electrode number POLARITY indicates the device type POLARITY 1 specifies nmos POLARITY 1 specifies pmos SOURCE specifies the source electrode number Control Parameters The optional c
162. VAL is used to stop tracing if the voltage or current of control electrode equals or exceeds END VAL NEXTST RATIO specifies which factor to use to increase the voltage step on the smooth parts of the I V curve MINCUR may be used to set a small current value in order to switch from internal control electrode bias ramping to external ramping with load resistor This parameter is recommended for small current breakdown simulation MINDL is the minimum normalized step size allowed in the trace Usually the user does not need to adjust this parameter Increasing MINDL will reduce the smoothness of the trace by overriding the angle criteria resulting in more aggressive projection and fewer simulation points Reducing MINDL will enhance the smoothness and increase the number of points in the trace STEPS is the number of operational points on a trace if STEP CONT was specified STEP CONT specifies that the trace will proceed for a certain number of simulation points STEP INIT specifies initial voltage step size Note To set a sweep of increasingly negative voltage in CURVETRACE it is only necessary to set STEP INIT to be negative Since all parameters are multiplier of STEP INIT the whole voltage sweep will be negative TURNINGPOINT specifies that binary output solution files will be saved whenever the slope of the IV curve changes sign i e there is a turning point The name of the output file is soln num where num is the
163. a p VA RP RE ee aw ones 15 49 RF Analysis Parameters ae orca Cre CHER dea Dew d inen 15 49 Parasitic Element Parameters 15 50 Simple Logfile Defintion Example 15 50 RRNA WS EXIME 15 50 Transient AC Logfile Example Nose ER Ut eed 15 50 aito text ERA X CENE NI ERR subset aed eke 4 whee 15 52 Sa els ches ard a 15 52 LASER Mesh Example 1265 dv cts REIR a sa 15 52 MATERIAE 1h pod ho A AN 15 53 Description CPC 15 57 Localization of Material Parameters 15 57 Band Structure Parameters 15 57 Mobility 5 15 58 Recombination Model Parameters 15 58 Carrier Statistics Model Parameters 15 60 Energy Balance Parameters casa otras teu Sept b PL 15 60 Lattice Temperature Dependence Parameters
164. able 15 1 Types of Parameters Parameter Description Value Req Example Character Any character string Yes INFILE NMOS DOP Integer Any whole number Yes REGION 2 Logical A true or false condition No GAUSSIAN Real Any real number Yes X MIN 0 52 Any parameter which does not have a logical value must be specified in the form PARAM VAL where PARAM is the name of the parameter and VAL is the value of the parameter Logical parameters must be separated from other parameters or commands by a space For example in the statement DOPING UNIFORM CONCENTRATION 1E16 P TYPE parameters UNIFORM and P TYPE have logical values and the CONCENTRATION parameter has a value of 1 10 6 real Logical parameters can be turned off switched from true to false by placing a caret 7 in front of the logical parameter For example in the statement DOPING UNIFORM CONCENTRATION 1E16 P TYPE the parameter has been set to false Mnemonics It is not always necessary to input the entire statement or parameter name ATLAS requires only that you input enough letters to distinguish that command or parameter from other commands or parameters For example DOP may be used to abbreviate the DOPING command Excessive truncation is not recommended since future ATLAS syntax might make short abbreviations become ambiguous Continuation Lines Since it may be necessary for a statement line to contain more than 256 characters
165. actions on Electron Devices V 39 No 2 Feb 1992 pp 331 338 This model accounts for tunneling via trap transitions using an analytic approximation that modifies the lifetimes in the standard Schockley Read Hall recombination model Modified the models for hot electrons and holes and Fowler Nordheim tunneling currents The new models account for the flow of the electrons holes in the insulating layers to arbitrary electrodes based on one of two primitive models The first is the default model and trys to force the currents to follow the maximum potential gradients to find the proper electrode the second model insulator currents go the the nearest electrode With these modifications the electrode current run time outputs are modified to better reflect the new models Enabled correct small signal simulation when simulating with bulk and interface traps Distinction made between active and chemical dopant densities Small signal analysis with interface traps now works properly Moved the C Interpreter function F COMPOSIT from the MATERIAL statement to the DOPING statement In previous releases this function did not work as advertised since material composition needed to be defined at structure creation In order to make the function work properly it had to be moved to the DOPING statement In addition to CLIMIT parameter which existed earlier new parameters CLIM DD and CLIM EB were added in METHOD statement CLIM DD is exact analog
166. ag must be enabled The complex values as well as the magnitude and phase values are stored in log FOURIER INFIL Exampl E hemtl log FUNDAMENTAL 5e8 MAX HARMONIC 1 6E10 OUTFILE fftoutl log INTERPOLATE COMPLEX VALUES e 2 In this example the log file values between 31 25 ps and 2ns are transformed into the frequency domain The fundamental frequency is automatically determined from the time period set by T START and 5 The data values from this time period are interpolated into 64 samples giving a maximum harmonic frequency of 15 5 GHz The magnitude and phase values are then stored in fftout2 log FOURI INFIL OUTFILE fftout2 log INTERPOLATE E hemtl log T START 3 125e 11 T STOP 2e 9 NUM SAMPLES 64 15 36 SILVACO International GO Statement Statements GO GO quits and restarts ATLAS and also defines certain global parameters for ATLAS execution Note This command is executed by DECKBUILD This statement is documented in the VWF INTERACTIVE TOOLS MANUAL VOLUME ONE Example starting a given ATLAS Version To start a given version of ATLAS the syntax is set by the simflags argument To start version 4 3 0 R go atlas simflags V 4 3 0 R Parallel ATLAS Example To define the number of processors to be used in parallel ATLAS the P flag is used For example to start parallel ATLAS using 4 processors g
167. al The IMP REFINE statement allows users to select the critical value of a quantity for refinement and an associated minimum grid spacing This type of refinement is useful when key effects are located very close to junctions For example the emitter base junction in bipolar transistors The final level of grid refinement are manual refine boxes defined using Refine Mode Both x y 1 1 1 P2 x2 y2 These are boxes with a diagonal from x1 y1 to x2 y2 inside which the grid spacing is halved in the given direction These can be used as a final customization to the mesh In general however the constraint boxes described above are easier to use As a demonstration of the effectiveness of regriding using devedit Figures C 7 and C 8 show meshes created from the same process simulation structure Figures C 9 and C 10 show the Id Vds and breakdown characteristics respectively of the device for each mesh The mesh at the silicon surface is identical in both cases to a depth of 100A H owever the mesh below this is much coarser in Figure C 8 However the device results show no significant change despite the reduction in the node count by a factor of two SILVACO International C 7 ATLAS User s Manual Volume 2 File View Plot Tools Print Properties Help DEVEDIT Fine Grid 5000 nodes drain source 0 2 eee ATA Nl
168. an acronym for biconjugate gradient squared stabilized GMRES GMRES on the METHOD statement is an acronym for generalized minimum residual Direct methods can be used for 3D simulation by specifying DIRECT on the METHOD statement Practical experience shows that for 3D simulations either of the iterative methods are faster than the direct method H owever in some cases the accuracy produced by the iterative methods can prevent convergence in the nonlinear outer loop For 2D simulations only direct methods are supported The DC aurve tracer algorithm and small signal AC analysis are also not currently supported for 3D simulations SILVACO International 14 21 ATLAS User s Manual Volume 2 This page intentionally left blank 14 22 SILVACO International Chapter 15 Statements Overview Input Language This chapter contains a complete description in alphabetical order of every statement and parameter used by any of the ATLAS products except for MIXEDMODE MIXEDMODE specific parameters are documented in the MIXEDMODE Chapter The following documentation is provided for each statement e statement name e The product for which the statement is applicable e The syntax of the statement Alist of all statement parameters their type default value and units e description of each parameter Anexample of the correct usage of each statement Note An error message will be generate
169. and TAUMOB HO are dependent on the carrier temperature TAUTEM specifies the dependence of relaxation times with carrier temperature If TAUTEM is specified the values of MATERIAL statement parameters TAUREL EL and TAUREL HO are dependent on carrier temperature N TEMP or HCTE EL specifies that the electron temperature equation will be solved P TEMP or HCTE HO specifies that the hole temperature equation will be solved 15 100 SILVACO International MODELS Statement Statements Lattice Heating Simulation Flags Note These parameters should only be specified if GIGA or GIGA3D is enabled on your system HEAT FULL enables all thermal sources and sinks Joule heat generation recombination heat and Peltier Thomson heat HEAT PETHOM can be used to turn off the Peltier Thomson heat source in the HEAT FULL option LAT TEMP or L TEMP specifies that the lattice temperature equation will be solved For lattice heating simulation there must be at least one thermal contact defined using the THERMCONTACT statement Model Macros BIPOLAR selects a default set of models which are used when simulating bipolar devices The bipolar models are CONMOB FLDMOB BGN CONSRH and AUGER ERASE specifies a default set of models which are used to simulate EEPROM erasure When is specified the MOS FNORD IMPACT and BBT KL models will be used MOS specifies a default set of models for MOS devices The MOS
170. ansform INTERPOLATE must be used if the log file contains non uniform time steps MAX HARMONIC specifies the maximum harmonic frequency that the Fourier transform should calculate This will automatically calculate the correct number of samples NUM SAMPLES required to generate this frequency FUNDAMENTAL must be specified when MAX HARMONIC is used NUM SAMPLES specifies the number of discrete samples This should be an integer power of 2 i e 2 where n is a positive integer The default value is 64 unless the MAX HARMONIC parameter is specified In this case the number of samples is set to the nearest integer power of 2 which will generate this frequency OUTFILE specifies the output file for the Fourier transform data T START specifies the start of time data to be used for the Fourier transform The default value is the first time point in the input log file SILVACO International 15 35 ATLAS User s Manual Volume 2 FOURIER Statement T STOP specifies the end of time data to be used for the Fourier transform The default value is the last time point in the input log file Exampl e1 In this example the transient data previously written to log file hemt1 log is transformed from the time domain to the frequency domain The fundamental frequency is set to 0 5 GHz and harmonic frequencies up to 16 GHz are calculated Since the data in hemt1 log has non uniform time steps the INTERPOLATE fl
171. apability A new statement has been implemented which allows users to write local scalar quantities e g potential electron concentration hole concentration etc and vectors eg field etc to the log file as a function of bias time etc The user may specify the probe by location minimum or maximum and type 6 Modifications to the Watt mobility model Several modifications were madetothe Watt mobility model First the user may now apply the model to grid nodes below the interface down to a user specified depth Also the user can use an exponential scaling on the effective field Finally the user can make the models only apply to minority carriers 7 Improved vector averaging Certain quantities used in ATLAS are not defined on grid points but between points e g electric fields To write these quantities into the structure files they must be averaged In this implementation an improved averaging scheme was introduced which produces smoother results The user also has control over various weighting schemes for the averaging 8 Trapsin MIXEDMODE New parameters were introduced to the TRAP INTTRAP DEFECT and INTERFACE statements to enable proper handling of these physical models in MIXEDMODE SILVACO International D 5 ATLAS User s Manual Volume 2 9 Modified run time outpu The ATLAS run time output was modified to be more concise and informative 10 Misalignment and delta CD in INTERCONNECT3D INTERCONNECT3D now a
172. at sinks form boundary conditions for equation 13 1 The solution of the heat equation by THERMAL3D is invoked by the following syntax MODELS THERMAL Setting Thermal Conductivity The value of thermal conductivity k for each region should be specified in the MATERIAL statement Because thermal conductivity is in general temperature dependent the following four models are available k T W cm K 13 2 k T k0 T 300 W cm K 13 3 k T 1 A C T W cm K 13 4 k T E T D W cm K 13 5 Table 13 1 User Specifiable Parameters For Equations 13 2 to 13 5 Symbol Parameter Statement 0 TC CONST ATERIAL n TC NPOW ATERIAL A TC A ATERIAL B TC B ATERIAL C D C E ATERIAL To choose the model in Equation 13 2 the parameter TCON CONST should be specified default To choose the model in Equation 13 3 the parameter TCON POLYN should be specified To choose the model in Equation 13 5 the parameter RECIP should be specified 132 SILVACO International THERMAL3D Example MATERIAL REGION 2 TCON POWER TC CO 1 0 TC NPOW 1 2 means that the temperature dependent thermal conductivity for region 2 is expressed as ee 13 6 T 300 Suggested Parameters For Thermal Conductivity There are no pre set material defaults
173. ation 3 226 ETRAP specifies the trap energy for SRH recombination F COPT specifies the name of a file containing a C INTERPRETER function for the specification of composition and temperature dependence of the radiative recombination rate F GAUN specifies the name of a file containing a C NTERPRETER function for the specification of composition and temperature dependence of the electron Auger coefficient F GAUP specifies the name of a file containing a C INTERPRETER function for the specification of composition and temperature dependence of the hole Auger coefficient F TAUN specifies the name of a file containing a C INTERPRETER function for the specification of position dependent electron lifetime models F TAUP specifies the name of a file containing a C INTERPRETER function for the specification of position dependent hole lifetime models F TAURN specifies the name of a file containing a C INTERPRETER function specifying the electron relaxation time as a function of electron energy specifies the name of a file containing a C I NTERPRETER function specifying the hole relaxation time as a function of hole energy F RECOMB specifies the name of a file containing a 1 NTERPRETER function for the specification of temperature composition electron and hole concentration dependent recombination rate models KLASRH and KLAAUG Model parameters KSRHTN coefficient for Klaassen s concentration and temperature dependent
174. ation of the problem INTERCONNECT3D uses Dirichlet boundary conditions for contacts and Neumann boundary conditions for all other boundary planes When capacitances are being investigated Equation 12 1 is solved with e Defined potentials on conductors e 1 set to the dielectric permittivity e of insulator regions A normal electric field is set to 0 except for contacts at the external boundaries of the structure This boundary condition is artificial It assumes that each face of the structure has reflectional symmetry in every direction This situation is illustrated in Figures 12 1 and 12 2 The structure simulated is shown in Figure 12 1 and the boundary conditions are shown in Figure 12 2 Once the electric field distribution is known the energy and or total electric charge of the interconnection environment can be calculated The capacitance matrix of the system is determined by calculating the energy and or total electric charge for a sufficient number of different bias conditions INTERCONNECT3D uses the energy conservation principle to calculate capacitance data because the energy conservation principle is more precise than the charge conservation principle A system of n conductors is described by a set of n n 1 2 capacitances Every potential calculation with respect to a specific bias set yields one energy balance equation Therefore n n 1 2 3 D potential solutions are needed to obtain the minimal set of equations necessary to f
175. ational Table of Contents INTERFACE bane a Ma antares 15 42 Description 15 42 Boundary Condition Parameters 15 42 occa PaL Ie pipes eite dtes pa pub ik e bt aol 15 43 MOS Example uo br ehe Yt dee tian eda YN aud ra ad ca 15 43 SOLE XIII erg antt eis ica eto oc te Eee alien 15 43 Interface Charge for IIl V Devices 15 43 INTTRAP ert a aa n A erases R 15 44 Description ELTE 15 44 Capture ond gas maa pa cid AA ace aeo aea 15 45 Example setting Multiple Interface Trap States 15 45 EORD iiia isa Sin Widen Race Sos WN AS rire aue a ata aaa 15 46 BFA l a 25 ee ae te tite Ree ee ee ee opa ene RUM eC 15 46 Fils 15 46 Simple Save and Load Examples 15 47 Binary Format Example 1 2r sedans ohn EUER a VEEE ERR 5 47 Bole E Sad E PEE tease aaa 15 48 File Output Parameters Jeu uror vates Odes Salen EY verr
176. ations with TFT The models for continuous defect or trap densities are documented in Chapter 7 QUANTUM3D Models Models for simulating quantum effects semiconductors are supported in QUANTUM3D The definition of the quantum moments solver is the same as in 2D simulations with QUANTUM The models for simulating quantum effects and the parameters to control the model are documented in QUANTUM Models section of Chapter 3 LUMINOUS3D Models Many of the models for simulating photodetection in LUMINOUS3D are similar to those for simulating photodetection in Luminous thus it is useful for the user to first read Chapter 8 regarding the use of LUMINOUS There are however several important differences between LUMINOUS and LUMINOUS3D as descri bed below Optical source specification The specification of the optical source in 3D is similar to the specification of the source described in Chapter 8 LUMINOUS with a few additions to account for the third dimension Referring to Figures 11 1 and 11 2 the complete specification of the optical source in 3D indudes the specification of the three coordinates of the source origin using the X ORIGIN Y ORIGIN and Z ORIGIN parameters of the BEAM statement as well as two angles of rotation using the THETA and PHI parameters The parameter PHI is analogous to the LUMINOUS parameter ANGLE and specifies the direction of propogation relative to the device x axis see Figure 11 1 In face PHI and ANGLE are synonomo
177. b Arora Analytical longitudinal and transverse electric field dependent mobility models Caughey Thomas CVT Yamaguchi Band Gap Narrowing BGN Boltzman statistics F ermi Dirac statistics and incomplete ionization F owler Nordheim current calculation Lucky electron model for hot carrier injection and transient programming and erasing of EPROM devices e Thethree dimensional simulated structure can be specified using DEVEDIT3D e Uses ToNYPLOT3D for postprocessing e Single Event Upset simulation is feasible with DEVICE3D The capability of single event upset photogeneration transient simulation has been introduced It allows specification of multiple tracks and radial length and time dependence specification of generated charge along tracks 3 THERMAL3D introduced THERMAL3D is introduced as new capability for three dimensional simulation using ATLAS The Poisson equation for temperature is solved in three dimensional regions of specified heat conductivity with defined temperatures on thermal contacts which are ideal heat conductors The user may specify the thermal properties of regions heat sources and heat sinks e Four models of temperature dependent thermal conductivity e User may specify independent temperatures on all thermal sinks thermal electrodes e User may specify multiple independent heat sources e Completely compatible with ATLAS e Thesimulated structure is specified using DEVEDIT3D including thermal elec
178. by ATLAS Solution files contain physical quantities mapped to the simulation grid One solution file is saved per bias point Logfiles which traditionally have saved the terminal characteristics for all bias points A new feature of ATLAS 4 0 is the addition of a capability to save physical quantities at user specified locations within the device grid to the log files A new statement PROBE is used to specify the quantity to be saved and the location For example to save the electron concentration rate at a location 1 0 1 the syntax is PROBE NAME my_e_conc N CONC X 1 0 Y 0 5 The label specified by the NAME parameter is used to label the saved quantity in TONYPLOT and subsequent EXTRACT statements For vector quantities the PROBE statement also requires a direction to be given using the DIR parameter This is specified as an angle in degrees with the X axis DIR 0 To find the electric field across an oxide layer the syntax is PROBE X 1 2 Y 0 2 FIELD DIR 90 NAME oxide_field Figure C 11 shows the resultant plot of electric field MOSFET gate oxide during a transient ESD pulse This result shows the probability of oxide breakdown during the ESD stress without the need to examine many separate solution files Another advantage of the probe for vector quantities is that it reads the values directly from the simulator at the closest location to the specified XY coordinates This avoids
179. cal False THICKNESS Real um UPPER Integer VOL RATIO Real 0 44 WIDTH Real um Y LOWER Real um Y MIDDLE Real 0 50 um Description SPREAD can reduce the grid complexity of specific simulations Since the SPREAD statement is somewhat complicated we suggest that you follow the supplied examples very carefully until you are confident that you understand the workings of this statement Mandatory Parameters LEFT distorts the left side of the grid If LEFT is specified RIGHT must not be specified LOWER specifies the lower y grid line above which distortion will take place RIGHT distorts the right side of the grid If RIGHT is specified LEFT must not be specified SILVACO International 15 139 ATLAS User s Manual Volume 2 SPREAD Statement THICKNESS specifies the thickness of the distorted region Unless VOL RATIO is set to 0 or 1 THICKNESS will usually move the positions of both the UPPER and LOWER grid lines The Y LOWER and THICKNESS parameters define the distorted grid region Only one of these parameters should be specified UPPER specifies the upper y grid line under which distortion will take place WIDTH specifies the width from the left or right edge depending on whether LEFT or RIGHT is selected of the distorted area The actual x coordinate specified by WIDTH min x WIDTH for LEFT max x WIDTH for RIGHT will lie in the middle of the transition region between distorted and undisto
180. cifying OUTPUT BAND PARAM and saving a solution file Any semiconductor region that is defined as an electrode is then considered to be a conductor region This is typical for polysilicon gate electrodes Insulators In insulator materials only the Poisson and lattice heat equations are solved Therefore for isothermal simulations the only parameter required for an insulator is dielectric permittivity defined using MATERIAL PERM lt n gt Materials usually considered as insulators 5105 be treated as semiconductors using BLAZE however all semiconductor parameters are then required Conductors All conductor materials must be defined as electrodes Conversely all electrode regions are defined as conductor material regions If a file containing regions of a material known to a conductor are read in these regions will automatically become un named electrodes As noted bellow if the file contains materials that are unknown these region will become insulators During electrical simulation only the electrode boundary nodes are used Nodes that are entirely within an electrode region are not solved Any quantities seen inside a conductor region in TONYPLOT are spurious Only optical ray tracing and absorption for Luminous and lattice heating are solved inside of conductor electrode regions SILVACO International B 1 ATLAS User s Manual Volume 2 Unknown Materials If a mesh file is read containing mat
181. ction Conductivity Calculations In conductivity calculations the conductance of each region needs to be set using the GCOND parameter of the MATERIAL statement For example MATERIAL REGION 2 GCOND 1 E3 To select that a conductance calculation is required the following statement is used MODEL EX RES Capacitance Calculations For capacitance calculation the relative permittivity of insulator regions can be set using the MATERIAL statement If the DEVEDIT3D interface is used this can be done using MATERIAL REGION integer PERM lt value gt If the MAskViEWs interface is used INTERCONNECT3D assumes that all insulators are silicon dioxide and havea relative permittivity of 3 9 To overridethis the MATERIAL statement is used For example to set a nitride dielectric between two conductors in layers M1 and M2 ADDLAYER MASK M1 1 0 DIV 5 ADDLAYER THICK 1 0 DIV 5 ADDLAYER MASK M2 1 0 DIV 5 MATERIAL LAYER 2 PERM 7 2 The value of the LAYER parameter is counted from the bottom upwards To select that a capacitance calculation is required the following statement should be included in the command file MODELS EX CAP 12 6 SILVACO International INTERCONNECT3D Applying CD Variations and Misalignment The ADDLAYER statement supports the use of parameters to model variations in the interconnect structure The DELTA CD X a
182. ctrode has been defined in the ELECTRODE statement U AUGER specifies that the integrated Auger recombination rate is to be extracted U RADIATIVE specifies that the integrated radiative recombination rate is to be extracted U SRH specifies that the integrated SRH recombination rate is to be extracted U TOTAL specifies that the integrated total recombination rate is to be extracted 15 64 SILVACO International MEASURE Statement Statements Boundary Parameters Boundary parameters X MIN X MAX Y MIN and Y MAX define a bounding box Only nodes falling within this bounding box are included in the integration The default bounds are the boundaries of the entire device CONTACT specifies the contact number For electrode quantities current and metal charge a contact must be selected Only nodes falling within the bounds and belonging to the contact are included in the integration When IONIZINT is specified this is the electrode used to start electric field lines REGIONS specifies a particular set of regions If REGIONS is specified only nodes within the specified bounds that are part of a particular set of regions will be integrated X MAX specifies the x coordinate of the right edge of the bounding box X MIN specifies the x coordinate of the left edge of the bounding box Y MAX specifies the y coordinate of the top of the bounding box Y MIN specifies the y coordinate of the bottom of the bounding box Resi
183. d X MAX specifies the maximum x boundary of the electrode X MIN specifies the minimum x boundary of the electrode Y MAX specifies the maximum y boundary of the electrode Y MIN specifies the minimum y boundary of the electrode Z MIN specifies the minimum z boundary of the electrode Z MAX specifies the maximum z boundary of the electrode Note If an electrode has been shortened to fit the current mesh a warning message will be generated by ATLAS Electrode placement can only occur at previously defined mesh nodes Grid Indices As an alternative to the region parameters above it is permitted to use grid indices to define a region only when the mesh is rectangular although these parameters are not recommended To define a region with a rectangular mesh 1 The X MESH and Y MESH statements must be used to specify grid indices 2 The IX HIGH IX LOW IY HIGH and IY LOW parameters may be used to specify x and y values IX HIGH specifies the maximum x value of the grid index IX LOW specifies the minimum x value of the grid index 15 30 SILVACO International ELECTRODE Statement Statements IY HIGH specifies the maximum y value of the grid index IY LOW specifies the minimum y value of the grid index Nodes which have x and y grid indices between IX LOW and IX HIGH and between IY LOW and IY HIGH designated electrode nodes Normally horizontal planar electrodes will be used In this case IY LOW equals
184. d DEVICE specifies the device in MIXEDMODE simulation that the MOBILITY statement should apply to NAME specifies the name of the region that the MOBILITY statement should apply Note that the name must match the name specified in the NAME parameter of the REGION statement Mobility Model Flags N ANGLE specifies angle for application of electron mobility parameters in simulation of anisotropic mobility P ANGLE specifies angle for application of hole mobility parameters in simulation of anisotropic mobility FLDMOB N specifies a lateral electric field dependent model for electrons see Equation 3 198 FLDMOB P specifies a lateral electric field dependent model for holes see Equation 3 199 CONMOB N specifies that doping concentration dependent model to be used for electrons CONMOB specifies that a doping concentration dependent model 15 to be used for holes CCSMOB N specifies that carrier carrier scattering model is to be used for electrons see Equations 3 128 3 131 CCSMOB P specifies that carrier carrier scattering model is to be used for holes see Equations 3 128 3 131 ANALYTIC N specifies that the analytic concentration dependent model is to be used for electrons see Equation 3 124 specifies that the analytic concentration dependent model is to be used for holes see Equation 3 125 ARORA N specifies that the Arora analytic concentration dependent model is to be used for electrons see Eq
185. d if you attempt to specify a statement for a simulator which you have not purchased For example the BEAM statement may only be used if you have purchased LUMINOUS or LUMINOUS3D Syntax Rules In this manual we refer to statements and parameters An input deck line is referred to as a statement or statement line Since statements and parameters are not case sensitive they may be entered using either uppercase or lowercase letters A statement is specified in the general format STATEMENT lt PARAMETER gt lt VALUE gt where STATEMENT is the statement name PARAMETER is the parameter name and VALUE is the parameter value The space character is used to separate the parameters in a statement The words and numbers which follow a statement are parameters of that statement A word is an alphanumeric string which is terminated either by a space or by a carriage return A number is a numeric or alphanumeric string which is terminated either by a space or by a carriage return Numerical values may range from 10738 to 1038 A number may contain the symbols positive negative and or E decimal notation For example 10 1 234E5 003 12E 10 Four types of parameters are used by the ATLAS products real integer logical and character These parameter types are explained in Table 15 1 SILVACO International 15 1 ATLAS User s Manual Volume 2 Statements T
186. d in any THERMAL3D input file Interpreting The Results From THERMAL3D The output of thermal simulation consists of the minumum and maximumcalculated temperature of each region and its location The three di mensional temperature distribution can be saved an ouput structure file by setting the OUTFILE parameter in the SOLVE statement and visualized using TONYPLOT3D The output of thermal simulation consist of the minimum and maximum calculated temperature of each region and its location The three dimensional temperature distribution can be saved in a output structure file by setting the OUTFILE parameter in the SOLVE statement and visualized using TONYPLOT3D More Information Many examples using THERMAL3D have been installed on your distribution tape or CDROM More information about the use of THERMAL3D can be found by reading the text associated with each example 134 SILVACO International Chapter 14 Numerical Techniques Overview This chapter describes the overall process of obtaining a numerical solution the subtasks involved and the options and defaults available in ATLAS Users do not need to master this material in order to use ATLAS Chapter Two presents the information about numerical techniques that is needed by most users This chapter provides additional information that will mainly be of interest to advanced users Numerical Solution Procedures Semiconductor device operation is modeled i
187. d in the Getting Started and 3D device simulation chapters A region has a unique number which is used to identify the region on the MATERIAL statement The POWER parameter of the MATERIAL statement is used to set the power of the heat source in watts MATERIAL REGION 2 POWER 0 35 The POWER parameter must be set on the SOLVE statement if the user wishes to step the power through a range of values See the section OBTAINING SOLUTIONS IN THERMAL3D in this chapter for the proper syntax Defining Heat Sinks Heat sinks are identified as electrodes in the 3 D structure Heat sink areas should be defined as electrodes in the manner documented in the Getting Started and 3 D Device Simulation chapters Each electrode heat sink has a unique number which is used to set the temperature on the heat sink during simulation Setting the temperature of the heat sink is documented in the Obtaining Solutions section of this chapter SILVACO International 13 1 ATLAS User s Manual Volume 2 Model and Material Parameter Selection Thermal Simulation Model To obtain steady state solutions for the temperature distribution THERMAL3D solves Poisson s equati on for temperature V K T VT q 13 1 where T represents the steady state temperature k the temperature dependent thermal conductivity and q the power generation per unit volume in the medium heat sources The prescribed temperatures at the he
188. d small signal AC simulation in MIXEDMODE 34 Energy Balance for Heterojunctions Modifications to to the ATLAS energy balance formulas were introduced to account for positionally dependent band structures 35 Improved Material Defaults Some material model parameter defaults were changed to reflect better models in literature In particular these improvements affect InGaAsP and related compounds AlGaAs and SiGe 36 Improved DevEdit Interface Donor and acceptor impurities were added to the DEVEDIT interface for doping specification in DEVEDIT SILVACO International D 11 ATLAS User s Manual Volume 2 MIXEDMODE Version 2 0 0 R 37 User definition of how often solutions are saved during transient simulation 38 Thecylindrical coordinate system may now be used with MIXEDMODE 39 Schottky contacts are now supported in MIXEDMODE 40 Tabulated time dependent voltage and current sources may be specified 41 Previously calculated device solutions can be loaded into MIXEDMODE 42 Circuits may include lossless transmission lines 43 User defined two terminal elements may be specified TFT Version 2 0 0 R 44 User Specifiable Thermal Conductivities of Metals GIGA now recognizes metals electrodes as different materials from semiconductors and insulators Users can now specify metal thermal conductivity 45 Regional DOS Specification Added REGION parameter to the DEFECT statement to allow DOS to be defined differently in
189. d when METHOD GUMMEL NEWTON is specified GUMITS specifies the maximum number of Gummel iterations LUICRI LU2CRI specifies amount of work per Poisson loop The inner norm is required to 1 decrease by at least LUI1CRI before returning or 2 reach a factor of LU2CRI below the projected Newton error whichever is smaller If the inner norm is exceeds the projected Newton error quadratic convergence is lost SINGLEPOISSON specifies that only a single Poisson iteration is to be performed per Gummel loop In the default state the continuity equation is only treated after the Poisson iteration has fully converged This technique is useful where the carrier concentration and potential are strongly coupled but the initial guess is poor precluding the use of NEWTON Newton Parameters 2NDORDER specifies that second order discretization will be used when transient simulations are performed AUTONR implements an automated Newton Richardson procedure which attempts to reduce the number of LU decompositions per bias point We strongly recommend that you use this parameter to increase the speed of NEWTON solutions Iterations using AUTONR will appear annotated with an A in the run time output Often an extra iteration is added when using this parameters since the final iteration of any converged solution cannot be done using AUTONR DT MAX specifies the maximum time step for transient simulation DT MIN specifies the minimum time step f
190. ded as a convenience Due to the restriction of prismatic elements in 3D the user cannot accurately specify focusing elements using the device mesh In Luminous3D the user can specify a virtual lenslet as illustrated in Figure 11 4 11 10 SILVACO International 3D Device Simulation T LENSLET zl E SOA LENS X N 3NY Id SN31 N M DEVICE lt lt Figure 11 4 Luminous3D Lenslet Specification As shown in Figure 11 4 the lenslet is represented by a spherical section atop a plane The center of the sphere is specified by the LENS X LENS Y and LENS Z parameters of the BEAM statement radius of the sphere is specified by the LENS RADIUS parameter of the BEAM statement The location of the planar part surrounding the lenslet relative to the y 0 plane is specified by the LENS PLANE parameter The index of refraction of the lenslet as well as the volume between the lens plane and the device surface is specified by the LENS INDEX parameter of the BEAM statement It should be noted that the volume associated with the lenslet is not meshed or considered in the solution of the device equations It is meerly used in the ray tracing Also the user should keep in mind that lenslet can only be specified in planes perpendicular to the y axis Other differences between LUMINOUS and LUMINOUS3D LUMINOUS3D has several other differences with LUMINOUS For example in Lumino
191. del for continuity equations allows the accurate prediction of avalanche breakdown for many devices Since impact ionization is a two carrier process the following statement must be specified after setting impact ionization models METHOD CARRIERS 2 Model Selection Flags CROWELL specifies the Crowell and Sze formulae SELB selects the impact ionization model described by Selberherr N CONCANNON P CONCANNON set the Concannon substrate current model SILVACO International 15 39 ATLAS User s Manual Volume 2 IMPACT Statement Note If no model selection flag is set then the model parameters from Grant are used See the Physics Chapter for details Model Localization Parameters DEVICE specifies the device MIXEDMODE simulation to which the statement should apply MATERIAL specifies what material from the Table B 1 the statement should apply If a material is specified then all regions defined as being composed of that material will be affected NAME specifies what region that the IMPACT statement should apply Note that the name must match the name specified in the NAME parameter of the REGION statement REGION specifies that index of the region to which the impact parameters apply Crowell Model Parameters LAMBDAE specifies the mean free path for electrons LAMDAH specifies the mean free path for holes Selberrherr Model Parameters ANI AN2 BN1 BN2 EGRAN specify the basic set of parameters for Se
192. dent energy relaxation time model based on table data from Laux Fischetti Monte Carlo simulation see Table 3 9 Lattice Temperature Dependence Parameters EGALPHA specifies the alpha coefficient for temperature dependence of bandgap see Equation 3 36 EGBETA specifies the beta coefficient for temperature dependence of bandgap see Equation 3 36 HC A HC B HC C and HC D specify the values of the four coefficient of the heat capacity equation see Equation 6 6 LT TAUN specifies the temperature dependence for electron lifetimes see Equation 6 9 LT TAUP specifies the temperature dependence for hole lifetimes see Equation 6 20 POWER specifies the value of thermal power generated in a power source associated with a region in THERMAL3D TC A TC B and TC C specify the three thermal conductivity coefficients see Equation 6 4 TC CO specifies the equilibrium value of thermal conductivity 0 in equation 13 2 Synonym TC CONST TC D specifies the value of the parameter D in equation 13 5 TC E specifies the value of the parameter E in equation 13 5 TCON CONST specifies that thermal conductivity should be modeled as constant with respect to temperature The value of the thermal conductivity is given by the value of the TC CO parameter TCON POWER specifies that the temperature dependence of thermal conductivity should be modeled using equation 13 3 TCON POLYNOM specifies that the temperature dependence of thermal conductivity sho
193. ditions essc dedo toad ben 15 12 Contact P arasiticS Ee e ER a 15 13 P arameteles rud qua a tie Vei ace aao Cd de e did 5 13 Floating Gate Capacitance Parameters 15 13 Schottky Barrier and Surface Recombination Example 15 13 Parasitic Resistance Example 15 14 Floating Gate Example eo Rr RR HR PRI RR RN S SR et 15 14 CURVETRACE cer TT 15 15 dc cep M DP ETC ITE 15 15 Description sue So Ao Bota LAO Bees bp a CIR MERI eati acti te Wee 15 15 Diode Breakdown Example 15 16 DEFECT mte ETT 15 17 SYNAR ees eben ER tte anti ac aue emt aie t tetra e data ish nia tle eda enn ate 15 17 SILVACO International ix ATLAS User s Manual Volume 2 15 18 15 19 DEGRADATION rd x EORUM a EN ER UP es valla 15 20 ers NE EN E EC 15 20 PUSS CP EE 15 20 MOS Interface State Example 2 trem dont te e vee RR 15 20 aches ledge
194. e False 0 False False False False False False False False False False 0 6 16 1076 6 16 1076 9 2 107 9 2 107 Units CV 5 V cm CV 5 V cm cm cm cm cm SILVACO International MODELS Statement Statements Parameter IG EBETA IG HBETA IG EETA IG HETA IG EEOX IG HEOX IG EBO IG HBO IMPACT INCOMPLETE INFINITY IONIZ INV SF KSN KSP KLA KAUGDP LAT TEMP LASER LMOD LAS ABSORPTION LAS EINIT LAS ESEP LAS EFINAL LAS FCARRIER LAS ITMAX LAS LOSSES LAS MAXCH LAS MIRROR 1 LAS MULTISAV Type Real Real Real Real Real Real Real Real jogical jogical Real Logical Real Integer Integer Logical Real jogica l jogica l Logical Logical Logical Real Real Real Logical Integer Real Real Real Logical Default 2 59x10 2 59x10 2 0x10 2 0x10 9 0x10 9 0x10 3 2 4 0 False False 0 001 False False False False False False False 30 90 False 5 5 Units V cm 9 5 V cm 9 5 y1 3 cm 3 yi 3 2 3 V cm V cm ev ev ev cm SILVACO International 15 95 ATLAS User s Manual Volume 2 MODELS Statement Parameter LAS NI
195. e Appendix B use AFFINITY see Appendix B see Appendix B see Appendix B see Appendix B 1 0 10 9 0 1073 0 045 0 044 see Appendix see Appendix B see Appendix B 0 0 Units A cm K A cm K 5 cm s cm cm cm cm s eV eV eV eV eV eV K SILVACO International 15 53 ATLAS User s Manual Volume 2 MATERIAL Statement Parameter F TAUP F TAURN F TAURP F MUNSAT 5 F BANDCOMP F EPSILON F VSATN F VSATP F RECOMB F IND X FCN FCP FERRO EPSE GAINO GAINOO GAININ GAINIP GAIN2NP GAMMA GCB Type Charac Charac Charac Charac Charac Charac Charac Charac Charac Charac Charac Ler Cer Ler Cer Cer LEGI Cer Ler Ler Character Charac Charac Charac Charac Charac Real Real Real Real Real Real Real Real Real Real Real Real Real Real Ler Cer Ler wer Ler Default 3 0 10718 7 0 1071 2000 0 200 0 3 0x10 19 Units V cm C sqom C sqom cm cm cm 15 54 SILVACO International MATERIAL Statement Statements Parameter G SURF GVB G CONDUCTIVITY HC C HC D IMAG IND
196. e by ATLAS When using DEVEDIT3D it is important to also save a command file This is used to recreate the 3D structure inside DEVEDIT3D and is important since DEVEDIT3D does not read in 3D structure files ATLAS can read in structures generated by DEVEDIT3D using the command MESH INF lt filename gt The program is able to distinguish automatically between 2D and 3D meshes read in using this command Defining Devices with Circular Masks DEVEbDIT3D makes a triangular mesh in the XY plane and uses z plane slices This means that normally the Y direction is vertically down into the substrate However in the case of using circular masks it is necessary to rotate the device For defining devices using circular masks in DEVEDIT3D the XY plane should be the surface of the device and the Z direction should be into the substrate SILVACO International 11 3 ATLAS User s Manual Volume 2 Model And Material Parameter Selection in 3D Models and material parameters are chosen in 3 D in common with other 2 D modules using the MODELS IMPACT MATERIAL MOBILITY INTERFACE and CONTACT statements The models available in 3D device simulation programs are 1 Mobility Table for 300K CONMOB Thomas ANALYTIC Arora s Model ARORA Klaassen s Model KLAASSEN Lombardi s Model CvT Yamaguchi Model vAMA Parallel Field Dependence FLDMOB Parallel Field Dependence with negative differen
197. e is defined as an electrode in ATHENA The electrode statement is used with the X and Y parameters acting as crosshairs to target a particular region of the structure The whole region irrespective of shape is then defined as an electrode ELECTRODE NAME gate X x value Y y value A region defined this way is now treated as equipotential in ATLAS The potential of this region will be defined by the VGATE parameter of the SOLVE statement Hence poly depletion cannot be modeled gate contacts defined this way The workfunction of this region must be set by the user For example a heavily n doped polysilicon contact can be defined by either of the two following statements CONTACT NAME gate N POLY CONTACT NAME gate WORK 4 17 The second approach of treating the polysilicon gate region as a semiconductor is achieved by placing contact on the top of the gate ATHENA this is done be depositing a metal or silicide layer on top of the polysilicon The ELECTRODE statement is then used to define this metal region as the gate electrode ATLAS a workfunction for the gate should not be specified on the statement as this would give an undesirable workfunction difference between the metal and polysilicon the potential on the metal region is defined by the vGATE parameter of the SOLVE statement The potential within the polysilicon gate region will depend on the doping level of the polysilicon
198. e material menu when the region is defined in DEVEDIT Supposing that we are satisfied with the default values of the parameters from the minimum set discussed above and that we are principally concerned with the recombination and heat flow parameters defaults the following section of the input deck illustrates how these parameter defaults may be modified new material AlInGaP ATERIAL MATERIAL InGaAsP SRH ATERIAL MATERIAL InGaAsP TAUN0 1 1e 9 TAUPO 2 3e 8 Auger ATERIAL MATERIAL InGaAsP AUGN 5 8e 30 AUGP 1 1e 31 Optical material material InGaAsP COPT 1 7e 30 B 22 SILVACO International Material Systems Thermoconductivity MATERIAL MATERIAL InGaAsP TC A 2 49 Heat capacity MATERIAL MATERIAL InGaAsP HC A 1 9 SILVACO International B 23 ATLAS User s Manual Volume 2 B 24 SILVACO International Appendix C Hints and Tips This appendix is a collection of answers to commonly asked questions about the operation of ATLAS This information has been previously published in articles The Simulation Standard Silvaco s trade publication The original articles can be viewed at Silvacos home page at http silvaco con simstd Question Can ATLAS handle photogeneration from non normally incident light What syntax is used to determine the correct photogeneration rate Answer The models with Luminous allow simulation of photogeneration with
199. e that charges are only applied at the material interfaces so the Y coordinate needs only to be somewhere within the silicon film INTERFACE 0 01 QF 5e10 INTERFACE Y MIN 0 01 2 11 Interface Charge for Ill V Devices Interface charge can be at the interfaces between two semiconductor regions or at the edges of semiconductor regions using the CHARGE parameter The location of the added charge can be controlled using the Position Parameters described above SILVACO International 15 43 ATLAS User s Manual Volume 2 INTTRAP Statement INTTRAP INTTRAP activates interface defect traps at discrete energy levels within the bandgap of the semiconductor and sets their parameter values Syntax Parameter ACCEPTOR DEGEN FAC DENSITY DEVI DONO CE R F L EV EL F DENSITY REGION SIGN SIGP TAUN TAUP Description INTTRAP type E LEVEL r DENSITY r capture parameters Type Default Logical False Real 1 Real Char Logical False Real Char Integer Real Real Real Real Units cm cm2 cm2 DEVICE specifies which device the statement applies to in MIXEDMODE simulation DONOR specifies a donor type trap level ACCEPTOR specifies an acceptor type trap level DEGEN FAC specifies the degeneracy factor of the trap level used to calculate the density
200. e the quality of the mesh With triangle smoothing which is also referred to as diagonal flipping each adjoining pair of triangles is examined If appropriate the diagonal of the quadrilateral is flipped to stabilize the discretization The diagonal is never flipped when two elements are composed of different materials When elements are of the same material but have different region numbers the user can specify whether or not to flip the diagonals Triangle smoothing is desirable in almost all cases and should be performed on both the initial grid and on subsequent regrids The only exception to this rule arises from a undesirable interaction of three elements regrid high aspect ratio triangles and smoothing This situation frequently occurs in gate oxide regions that involve long thin triangles In these cases smoothing may produce large triangles surrounded by many smaller triangles giving the appearance of a hole in the mesh To overcome this the smoothing command 4 can be used to limit the formation of the large triangles Discretization The Discretization Process The discretization process yields relationships between the variables defined at mesh points order to be useful a discretization must be consistent i e it must limit to the underlying equation in the limit that the mesh size tends to zero All of the discretizations used in ATLAS have this property Different discretizations can have different prop
201. e total hole current density will be included in the standard structure file J TOTAL specifies that the total current density will be included in the standard structure file JX CONDUC specifies that the x component of the total conduction current density will be included in the standard structure file JX ELECTRON specifies that the x component of electron current density will be included in the standard structure file JX HOLE specifies that the x component of hole current density will be included in the standard structure file JX TOTAL specifies that the x component of total current density will be included in the standard structure file JY CONDUC specifies that the y component of the total conduction current density will be included in the standard structure file JY ELECTRON specifies that the y component of electron current density will be included in the standard structure file JY HOLE specifies that the y component of hole current density will be included in the standard structure file JY TOTAL specifies that the y component of total current density will be included in the standard structure file KSN specifies that electron Peltier coefficients are to be written to any saved structure file KSP specifies that hole Peltier coefficients are to be written to any saved structure file MINSET that a minimum set of data potential carrier concentration and electric field will be included in the standard structure file OPT INTENS
202. e x is a parameter such as V n p fp at every node point x k is the updated value calculated from the equation k is the cycle number with k 1 being the new update for parameter x CYCLIC RELAX is the relaxation factor dx k is the difference between the simulated values of x at the start and beginning of the current cycle while 5x k 1 is the equivalent for the previous cycle Steady state cyclic convergence is determined by comparing the normalizing sum of the updated values of V n p and fT with a tolerance value CYCLIC TOL CYCLIC RELAX specifies the CYCLIC BIAS relaxation factor the recommended range for this parameter to ensure stable convergence is between 0 2 and 1 CYCLIC TOL specifies the CYCLIC BIAS tolerance factor DECAY specifies the time constant used for defining an exponential change in bias for transient simulation ENDRAMP applies any bias changes as linear ramps ENDRAMP specifies the exact end of the ramp in running time i e the ramp will start at t t and end at tZENDRAMEP NSTEPS can be used to signal the end of the run i e the final time would be t t NSTEPS DT This parameter may be used instead of the TSTOP parameter PULSE WIDTH specifies the time constant used for sinusoidal nonlinear time domain simulation If SOPULSE is specified PULSE WIDTH is the width of the trapazodial square pulse not including the rise and fall times RAMPTIME applies any bias changes as l
203. eal Real Real Real Real Real Real Real Real Real Real ogical ogical jogica l jogica l Real Real Real Default See Appendix See Appendix See Appendix False See Appendix See Appendix All regions False 0 4x10 0 4x10 See Appendix See Appendix 0 4x10 i 0 4x10 1 See Appendix See Appendix See Appendix Units cm F cm cm K W cm WK cm WK 15 56 SILVACO International MATERIAL Statement Statements Parameter TRH TRH VSAT VSAT VSAT VSATURATION VTHN VTHP Description The MAT 2 E T3 E W1 E W2 E W3 ST 2 T3 W1 W2 W3 N P Type Real Real Real Real Real Real Real Real Real Real Real Real Real Default Units ev ev ev cm s cm s cm s cm s See Appendix B cm s See Appendix B cm s ERIAL statment is used set basic material parameters related to band structure and parameters for certain mobility recombination or carrier statistics models Parameters for temperature dependence are noted in a separate section below Localization of Material Parameters DEVICE specifies which device the MAT ERIAL statement should apply to in MIXEDMODE simulation MATERIAL specifies which material from the table in Appendix B that the MATERIAL statement should apply If a material
204. eel boe Dat aded 15 1 DL RTL EI 15 1 Input Larig age x sies e tem Rick Y RD ERR ERR E RO EUR E 15 1 Syntax RUES onc tete Aen fort 15 1 quid 15 2 a atest ye eine qa i oo 15 2 a pase a A Le 15 2 kee apna 15 2 oad 15 2 REPE A ES ER Reb ia 15 3 EXDISSSIUDS m ee esee e c 15 3 BEAM mcer 15 4 15 4 15 6 Monochromatic deer RED E ipd 15 8 Multispectral Bed EXIT DIG datas ced ont abo den ec Qt dcr i dat va id en en 15 8 COMMENT cT 15 9 S ntes de th Si Ne hc 15 9 Gon PH Q 15 9 4 5 ere ea 4 DON eau edades 15 10 ecc 15 10 lt ond acp 15 11 Workf nction 5 15 11 Bounda Con
205. el Version 4 0 0 R 1 Introduced a ferroelectric permitivity model This model accounts for ferroelectric polarization and hysteresis This release includes a new model to model ferroelectric materials It is useful for simulating ferroelectric devices such as ferroelectric capacitors and FETs 2 Introduced Klaassen s mobility model This release includes a new model for low field electron and hole mobilities in silicon This model accounts for lattice impurity and carrier scattering and screening as a function of temperature doping and carrier concentrations This model has been calibrated over a wide range of conditions and should be used as the default low field model for silicon simulations Introduced Concannon s gate and substrate current models This release indudes a new model for EPROM simulation This model estimates the gate current in EPROM devices as a function of carrier temperature by integrating a non maxwellian distribution function The model also uses a impact ionization model that uses the same distribution function to ensure a direct relationship between gate and substrate currents 4 Introduced Shirahata s mobility model This release indudes a new surface mobility model which accounts for carrier screening effects in the channel This is done largely by using Klaassen s model for the low field mobility The model also accounts for parallel and perpendicular fields in the channel 5 Introduced a Probe c
206. el eq 3 268 CHLHOLES specifies the hole distribution function constant used in Concannon s Substrate Current Model eq 3 269 ENERGY STEP specifies the energy step for numeric integration used Concannon s Substrate Current Model INFINITY specifies the limit for the highest energy in numeric integration used in Concannon s Substrate Current Model Selberrherr Model Example This example shows an IMPACT statement which specifies all parameters used by the model selected by the SELB parameter In this case only parameters for holes are field dependent Parameters AP1 and BP1 correspond to parameters at field values more than EGRAN Parameters AP2 and BP2 correspond to field values less than EGRAN Coefficients for electrons should be repeated IMPACT SELB AN1 7 03E5 AN2 7 03E5 BN1 1 231E6 BN2 1 231E6 AP1 6 71E5 AP2 1 58E6 BP1 1 693E6 BP2 2 036E6 BETAN 1 BETAP 1 EGRAN 4 0E5 SILVACO International 15 41 ATLAS User s Manual Volume 2 INTERFACE Statement INTERFACE INTERFACE specifies interface parameters at semiconductor insulator boundaries All parameters apply only at the boundary nodes except where stated Syntax INTERFACE lt params gt Parameter Type Default Units AR INDEX Real 1 none AR THICK Real 0 um CHARGE Real 0 0 cm DEVICE Char cm s Char S N Real 0 0 cm s S P Real 0
207. ellaneous Semiconductor Dielectric Properties Table B 20 Static Dielectric Constants for Miscellaneous Semiconductors Material Dielectric Constant Ge 16 0 Diamond 5 25 6H SiC a 9 66 4H SiC b 9 72 1 9 8 AlAs 12 0 AlSb 11 0 B 16 SILVACO International Material Systems Table B 20 Static Dielectric Constants for Miscellaneous Semiconductors Material Dielectric Constant GaSb i5 InSb 18 0 ZnS 8 3 ZnSe 8 1 Cds 8 9 CdSe 10 6 CdTe HgS HgSe 25 0 HgTe 20 PbS 170 0 PbSe 250 0 PbTe 412 0 5 SCN GaN 9 5 AlN 9 14 InN L9 3 6 BeTe Miscellaneous Semiconductor Mobility Properties Table B 21 Mobility Parameters for Miscellaneous Semiconductors Material MUNO cm2 Vs MUPO cm2 Vs VSATN cm s VSAT cmcm s Ge 3900 0 a 1900 0 b Diamond 500 0 300 0 2 0x107 SiC 330 0 300 0 2 0x107 SiC b 1000 0 50 0 2 0 107 1 80 0 SILVACO International ATLAS User s Manual Volume 2 Table B 21 Mobility Parameters for Miscellaneous Semiconductors Material cm2 Vs MUPO cm2 Vs VSATN cm s VSAT cmcm s AlAs 1000 0 100 0 AlSb 200 0 550 0 GaSb 4000 0 1400 0 InSb 7800 0 750 0 ZnS 165 0 5 0 ZnSe 100 0 16 Cds 340 0 50 0 CdSe 800 0 CdTe 1050 0
208. ement can be used to scale these Using both these WIDTH parameters will lead to a multiplication of the two widths for the RF parameters Simple Logfile Defintion Example This example saves all I V data in file myfile log LOG OUTF myfile log Results should be plotted using TONYPLOT RF Analysis Example To generate s parameters assuming the input is gate source and the output is drain source A width of 100 microns is also defined along with 100ohm resistance on the input LOG OUTF mysparams log S PARAM INPORT gate OUTPORT drain IN2PORT source OUT2PORT source WIDTH 100 100 Transient or AC Logfile Example The contents of LOG files varies for different types of simulations eg DC transient AC The content is set by the first SOLVE statement after the LOG statement Therefore the following syntax is required SOLVE VDRAIN 0 5 LOG OUTF myfile log SOLVE VDRAIN 3 0 RAMPTIME 1e 9 DT 1e 11 TSTOP 1e 7 15 50 SILVACO International LOG Statement Statements Correct transient parameters would not have been stored if the LOG statement had been placed before the first SOLVE statement which is DC SILVACO International 15 51 ATLAS User s Manual Volume 2 LX MESH LY MESH Statement LX MESH LY MESH L lt n gt MESH specifies the location of grid lines along the lt n gt axis in a rectangular mesh used in LASER simulation The syntax is equivalent for x and y directions S
209. en such that the lower grid line LOWER 10 follows the junction as closely as possible The grid is graded so that grid lines are spaced closer together as they approach the junction Because the point specified by WIDTH lies in the middle of the transition region it should be chosen to be slightly larger than the width of the doping box Doping DOPING UNIFORM N TYPE 1 15 DOPING GAUSS X LEFT 1 5 X RIGHT 2 PEAK 1 19 RATIO 75 JUNC 0 3 Spread SPREAD RIGHT W 0 7 UP 1 LO 4 0 3 MID 2 Y MID 0 10 SILVACO International 15 141 ATLAS User s Manual Volume 2 SYMBOLIC Statements SYMBOLIC Note In versions 3 0 and greater the SYMBOLIC statement is no longer needed All functions are moved to the METHOD statement 15 142 SILVACO International SYSTEM Statement Statements SYS SYS Not TEM TEM allows execution of any UNIX command within an input file e The SYSTEM statement is executed by DECKBUILD and is fully documented in the VWF INTERACTIVE TOOLS MANUAL VOLUME ONE Note The SYSTEM command must be enabled using an option on the DECK BUILD Main Control menu under Category Options Examples The is us The T following command will remove all files test str beforea SOLVE statement where the OUTF parameter ed system rm rf test str SOLVE OUTF test0
210. ename gt INFILE specifies a single input filename for solution data This parameter should be used when you wish to load only one solution which is the most common case INIFILE specifies a filename for present solution data Use this parameter if two input files are needed to perform extrapolation for an initial approximation 1 the PROJECT parameter of the SOLVE statement IN2FILE specifies an input filename for previous solution data Use this parameter if two input files are needed to perform an extrapolation for an initial approximation i e the PROJECT parameter of the SOLVE statement The solution specified by this parameter is the first to be overwritten when new solutions are obtained 15 46 SILVACO International LOAD Statement Statements Simple Save and Load Examples This example saves and later loads master format solution file SOL STR SAVE OUTF SOL STR LOAD INFILE SOL STR MASTER As before but using the SOLVE syntax SOLVE OUTF SOL STR MASTER LOAD INF SOL STR MASTER When the save and load operations are not done within the same ATLAS run see the Note below Binary Format Example Saving and loading using the binary format This is quicker but these files cannot be plotted in TONY PLOT SOLVE OUTF SOLVE_TMP LOAD INF SOLVE_TMP Note The function to calculate the difference between two files is now inside TONYPLOT It has been discontinued fr
211. ength n real index n imaginary index Where n is the number of lines to be read REAL INDEX specifies the real portion of the refractive index of the semiconductor Wavelength dependent defaults exist for certain materials as documented in Appendix B LASER Parameters ALPHAA specifies the bulk absorption coeffiecient in Equation 9 2 ALPHAR specifies the line width broadening factor in Equation 9 2 EPSINF specifies the high frequency relative dielectric permittivity see Equation 9 2 If this parameter is not specified it will be set equal to the static dielectric permittivity of the material F ALPHAA specifies the name of a file containing a C INTERPRETER function for the bulk absorption coeffiecient FCN parameter in the LASER free carrier loss model FCP parameter in the LASER free carrier loss model GAINO specifies the parameter 20 in Equations 9 3 and 9 11 GAIN00 specifies the parameter g00 in Equation 9 6 GAININ specifies the parameter g1n in Equation 9 6 GAINIP specifies the parameter glp in Equation 9 6 GAINIMIN specifies the parameter min in Equation 9 6 GAIN2NP specifies the parameter g2np in Equation 9 6 SILVACO International 15 61 ATLAS User s Manual Volume 2 MATERIAL Statement GAMMA specifies the parameter in Equation 9 3 If this parameter is not specified it will be calculated using Equation 9 5 Material Coefficient Definition Examples Numbered region This exa
212. er to HEI see Equation 3 278 IMPACT invokes the empirical impact ionization model with ionization coefficients taken from 1 More rigorous impact ionization models may be specified with the IMPACT statement NEARFLG specifies the model used for oxide transport when HEI or HHI are used The default is false which sets a purely drift based model assigning gate current to the electrodes where the electric field lines through the oxide terminate Setting NEARFLG replaces this model with one assuming the gate current is flowing the electrode physically nearest the point of injection This assumes a purely diffusion transport mechanism Setting NEARF LG for devices with only one gate or a coarse mesh is advised N CONCANNON enables the Concannon gate current model for electrons P CONCANNON enables the Concannon gate current model for holes Classical Carrier Statistics Model Flags BGN specifies band gap narrowing see Equation 3 38 BGN SLOTBOOM specifies band gap narrowing using the original Slotboom coefficients see Equation 3 38 BOLTZMANN specifies that Boltzmann carrier statistics be used see Equations 3 25 and 3 26 FERMIDIRAC specifies that Fermi Dirac carrier statistics be used see Equations 3 25 3 62 INCOMPLETE accounts for incomplete ionization of impurities in Fermi Dirac statistics see Equations 3 43 and 3 44 IONIZ accounts for complete ionization of heavily doped silicon when using INCOMPLETE
213. erials not in Table B 1 these will automatically become insulator regions with a relative permittivity of 3 9 All user defined materials from ATHENA irrespective of the material name chosen by the user will also become such insulator materials B 2 SILVACO International Material Systems ATLAS Materials ATLAS materials are listed in Table B 1 below Table B 1 The ATLAS Materials Single Element Semiconductors Silicon Poly Germanium Diamond Binary Compound Semiconductors GaAs GaP CdSe SnTe SiGe InP CdTe ScN a SiC InSb HgS GaN b SiC InAs HgSe AIN AlP ZnS HgTe InN AlAs PbS BeTe AlSb ZnTe PbSe GaSb Cds PbTe Ternary Compound Semiconductors AlGaAs InGaAs InGaP GaSbP GaSbAs InGaN InAlAs InAsP AlGaN Quaternary Compound Semiconductors InGaAsP InGaNAs AlInNAs InAlAsP AlGaAsP InGaNP A InNP AlGaAsSb AlGaNAs InAlGaAs GaAsP HgCdTe InAlGaN AlGaNP InAlGaP SILVACO International B 3 ATLAS User s Manual Volume 2 Insulators Vacuum Oxide Nitride Si3N4 Air 5102 SiN Sapphire Ambient Conductors Polysilico Palladium TiW TaSi 2 Aluminum Cobalt Copper PaSi Gold Molybdenum Tin PtSi Silver Lead Nickel MoSi AlSi Iron WSi ZrSi Tungsten Tantalum TiSi 151 Titanium AlSiTi NiSi Conductor Platinum AlSiCu CoSi Contact Notes The material models and parameters of Silicon are identical to those of S PISCES version 5 2 Users shou
214. erties with respect to accuracy The most important measure of accuracy is the order of the scheme i e how errors scaled as the difference between mesh points tends to zero Discretization schemes used in device simulation are often second order i e as the mesh becomes very fine the discretization error varies as the square of the separation between mesh points The discretizations implemented in ATLAS use the box integration method to approximate differential operators on a general triangular grid Each equation is integrated over a small polygon which encloses each node The set of all polygons completely covers the solution domain The integration procedure equates fluxes into a polygon with sources and sinks inside the polygon which means that quantities that are conserved physically are also conserved by the numerical solution The fluxes must be discretized carefully for the carrier continuity and energy balance equations otherwise nonphysical oscillations and negative carrier concentrations and temperatures may arise Scharfetter and Gummel introduced approximations for current densities that overcome this SILVACO International 14 3 ATLAS User s Manual Volume 2 problem Generalizations of this approach are used in ATLAS for the discretization of current densities and energy fluxes Non Linear Iteration The non linear solution method and associated parameters such as iteration and convergence criteria are specified in
215. ese solutions also produce eigen energies and eigen functions Added Hansch s model for quantum mechanical correction for carrier distributions in N channel MOSFETs inversion layers Added van Dort s model for quantum mechanical correction for carrier distributions in N and P channel MOSFETs in inversion and accumulation layers 13 Miscellaneous ATLAS Improvements Reconfigured small signal AC post processing to include the effects of parasitics in gain calculations Changed functionality of C interpreter functions F CONMUN F CONMUP to account for donor and acceptor concentrations separately Added trap concentrations to concentration dependent mobility models and band gap narrowing models Added new C interpreter functions for energy dependent relaxation times for electrons and holes Added new C interpreter functions for energy dependent Peltier coefficients for electrons and holes Added a new C interpreter function to specify doping in 3D as a function of position Added extra checking to the AC memory allocation If there is insufficient memory for the factorization more will be allocated A warning message will also be printed Enabled multiple contacts with the same name to have the same work function and other parameters Modified the DOPING statement so that ATHENA master files can now be used in 2D ATHENA doping is interpolated onto the ATLAS mesh Version 4 3 0 R 1 Introduced Quantum Transport Model
216. fficient matrix of the complex linear system is simply the J acobian associated with the DC operating point with some terms on the leading diagonal supplemented by jw The J acobian is available for free if the DC solution was calculated using Newton iteration This is a very attractive feature of the Newton method The resulting linear complex system can be solved by an iterative or a direct method A form of successive over relaxation SOR works well for frequencies significantly below the cutoff frequency but fails at higher frequencies More sophisticated iterative techniques can 14 18 SILVACO International Numerical Techniques be used at higher frequencies but it is simpler and more reliable to switch to direct sparse matrix methods if SOR fails to converge Frequency domain perturbation analysis is extremely attractive when the full Newton method is used to calculate a DC solution The method works for all frequencies It requires a predictable amount of computation which is quite low with respect to other calculations since only a single linear system is solved Frequency domain perturbation analysis is invoked in ATLAS by specifying the appropriate parameters in the SOLVE statement The Ac ANALYSIS parameter specifies that this analysis is to be performed TERMINAL specifies the contact whose terminal voltage is to be perturbed A full characterization requires that all but one of the device terminals is perturbed FREQUENCY FS
217. final solution Strategies that use automatic bias step reduction the event of non convergence loosen the requirement of a good initial guess Newton s method is the default for drift diffusion calculations in ATLAS There are several calculations for which ATLAS requires that Newton s method is used These are DC calculations that involve lumped elements transient calculations curve tracing and when frequency domain small signal analysis is performed The Newton Richardson method is a variant of the Newton iteration that calculates a new version of the coefficient matrix only when slowing convergence demonstrates that this is necessary An automated ewton Richardson method is available ATLAS and improves performance significantly on most problems The automated Newton Richardson method is enabled by specifying the AUTO parameter of the METHOD statement If convergence is obtained only after many Newton iterations the problem is almost certainly poorly defined The grid may be very poor i e it contains many obtuse or high aspect ratio triangles or a depletion region may have extended into a region defined as an ohmic contact or the initial guess may be very poor Gummel Iteration Each iteration of Gummel s method solves a sequence of relatively small linear subproblems The subproblems are obtained by linearizing one equation of the set with respec to its primary solution variable while holding other variables at their most
218. finition Structures for INTERCONNECT3D be defined in the same manner as described for DEvICE3D using the command language of ATLAS or an interface from DEVEDIT3D The only exception is in electrode definition which is described in this section INTERCONNECT3D also has an interface to IC layout using MASKVIEWS Commercial Layout Package 2D Cutlines 3D Cutlines ATHENA 3D Layer Generation ATLAS DevEdit3D Interconnect Solver SPICE Netlist Figure 12 3 Information flow for parasitic extraction from IC layout Figure 12 3 shows how the information from layout can be used in INTERCONNECT3D The left hand option uses 2D process simulation and is described in the ATHENA and MASKVIEWS manuals In this option the interface from DEVEDIT3D to INTERCONNECT3D is as documented in the Getting Started chapter SILVACO International 12 3 ATLAS User s Manual Volume 2 The right hand branch of Figure 12 3 shows the direct layout to INTERCONNECT3D interface This is documented below Tutorial For The MaskViews Interface The MASKVIEWS INTERCONNECTSD interface is a two step process Firstly the mask data must be extracted and saved in MAskViEWs After this the layer structure of the interconnect is defined ATLAS Saving Mask Data For INTERCONNECT3D The operation of MaskViEws including the GDS II interface is described in the MaAskViEWS documentation This tutorial assumes the
219. gical False SCALEY Integer 1 SMOOTH KEY Integer SPACE MULT Real 1 0 WIDTH Real 1 0 Description prev is a set of parameters that allow the user to read a previously generated mesh type new is a set of parameters that allow the user to initiate the generation of a rectangular mesh output is a set of the parameters for saving the mesh Parameters related to reading in an existing mesh file CYLINDRICAL specifies that the mesh being read in contains cylindrical symmetry Since this information is not saved in the mesh file the CYLINDRICAL parameter must be specified each time a structure with cylindrical symmetry is loaded FLIP Y reverses the sign of the y coordinate INFILE specifies the name of a previously generated mesh that has been saved to disk 15 66 SILVACO International MESH Statement Statements specifies a filename from which to read mesh and doping information in the SILVACO standard structure file SSF format This parameter is used to read in ATHENA or DEVEDIT structure files Typically such files contain all REGION ELECTRODE and DOPING information although ATLAS allows users to modify the structure using these statements This parameter is true by default and is the only file format supported by Silvaco PISCES IN indicates that the mesh file is in the old PISCES II format This is not recommended or supported by Silvaco SCALE Y specifies a factor by which all x and y coordinates are multip
220. he applied bias to the specified values and changes the majority carrier quasi F ermi levels in heavily doped regions to be equal to the bias applied to that region This choice is effective with Gummel iteration particularly in reverse bias It is less effective with Newton iteration MLOCAL starts from the currently loaded solution and solves a form of the total current continuity equation that provides an improved estimate of the new potential distribution All other quantities remain unchanged MLOCAL is more effective than LOCAL because it provides a smooth potential distribution in the vicinity of p n junctions It is usually more effective than PREVIOUS because MLOCAL provides a better estimate of potential This is especially true for highly doped contact regions and resistor like structures When a regrid is performed the solution is interpolated from the original grid onto a finer grid This provides an initial guess that can be used to start the solution of the same bias point on the new grid Although the initial guess is an interpolation of an exact solution this type of guess does not provide particularly fast convergence Recommendations And Defaults It is not normally required for the user to specify any initial guess parameter The INITIAL parameter is normally used only to obtain a thermal equilibrium solution The PREVIOUS PROJECT LOCAL and MLOCAL parameters are used for other bias points PREVIOUS and PROJECTION are t
221. he capability to specify multiple TRAN statements in a single input deck Added the extraction of network parameters S Z Y H ABCD stability factor unilateral power gain and maximum unilateral transducer power gain in MIXEDMODE e Added the capability to use the PROBE in MIXEDMODE 8 Modification to GIGA e Enabled simulations of floating gate structures with heat flow in GIGA 9 New Physical models e Added Klaassen s concentration and temperature dependent SRH lifetime and Auger rate models e Implemented new continuous trap level model TFT e Added new carrier concentration dependent Auger coefficient model e Added the capability to calculate the band to band tunneling coeffiicients from principles e Added the capability to model thermionic field emission tunneling in Schottky contacts e Added two new parameters to the single event upset model The generated electron holes pairs or charge will not be calculated after seconds if this parameter is specified in the input deck The width of the beam can now be specified as a constant value followed by an exponential or Gaussian function by using the beam radius parameter For radi greater than beam radius either the Gaussian or exponential functions is used if they are specified 10 New Numerical Techniques e Two sparse matrix reordering techniques are now available Minimum Degree MD Reverse Cuthill McKee RCM They are used in the 2D linear solver MD
222. he filename of a spectrum file Spectrum file must be in the format number of pairs wavelength 1 power 1 wavelength 2 power 2 wavelength n power n Note The power file must contain at least two power wavelengths pairs QUANTUM EFF is quantum efficiency factor which specifies the number of carrier pairs generated per photon absorbed RAYTRACE specifies the name of a file where the results of a ray trace are saved The ray trace may be viewed using TONY PLOT3D LUMINOUS3D only RAYS specifies the number of rays the user wishes to split the optical beam into LUMINOUS will automatically split the beam into enough rays to resolve the geometry Use of the number parameter will cause further splitting of the optical beam LUMINOUS only REFLECTS specifies the number of reflections that will be traced When the value of the REFLECTS parameter is increased the total number of rays traced increases non linearly We recommend that this parameter be used judiciously For example a single ray incident on three material layers will produce 4 rays if REFLECTS 0 is specified 10 rays if REFLECTS 1 is specified and 24 rays if REFLECTS 2 is specified REL POWER specifies the relative power in the beam when mono spectral simulations are performed This factor is multiplied by the power parameters specified in the SOLVE statement to give the total optical power in the beam THETA specifies the ang
223. he most frequently used PROJECTION is normally prefered to PREVIOUS when it is available i e when there are two previous solutions differing in the bias applied to the appropriate terminal PREVIOUS is required for transient simulations and for simulations that use current boundary conditions LOCAL and MLOCAL tend to work well for reverse biased devices and are especially efficient when trying to increase very large voltage increments By default PROJECTION is used whenever two appropriate solutions are available Otherwise the PREVIOUS guess is used unless there is no previous solution in which case INITIAL is used The DC Curve Tracer Algorithm Tracing l V curves for complicated device phenomena such as breakdown or latchup can be very difficult using conventional methods ATLAS includes a special purpose DC curve tracing algorithm that overcomes these problems This algorithm is based on a dynamic load line technique that adapts the boundary conditions for each step The approach implemented in ATLAS for curvetracing is based on the work describe in Reference 118 The key idea is that bias conditions can evolve smoothly between the limits of pure voltage control and pure current control This is achieved using external resistors that adapt dynamically to the shape of the I V curves to ensure that at each point the load line is perpendicular to the local tangent of the trace With this value for the external resisto
224. he trap level TAUP specifies the lifetime of holes in the trap level Analytical Doping Defintion Example This example describes a 1 0um n channel MOSFET using Gaussian source and drain profiles The lateral extent of the source is given by X RIGHT 2 This corresponds to the mask edge for the implant Sub diffusion is determined by an error function based on the RATIO LAT and JUNCTION parameters For both source and drain the n doping is added to the uniform p well concentration to ensure a junction depth of 0 3um DOP UNIF CONC 1E16 P TYPE DOP GAUSS CONC 9E19 N TYPE X RIGHT 2 JUNC 0 3 RATIO LAT 0 6 ERFC LA DOP GAUSS CONC 9E19 N TYPE X LEFT 3 JUNC 0 3 RATIO LAT 0 6 ERFC LA 1D ATHENA or SSUPREMS Interface Example This example reads a 1D ATHENA bipolar profile and adds it to a uniform substrate concentration The base and emitter doping are loaded from the same file by specifying the impurity required for each area boron in the base and arsenic in the emitter The DOPOFF parameter is used to subtract the substrate arsenic dopant out of the 1 D profile that is loaded since this dopant was already specified in the substrate doping line Versions of SSUPREM 3 later than 5 0 use standard structure files as default when saving data These can be loaded in ATLAS with the syntax below by replacing ATHENA 1D with SSUPREM3 SUBSTRATE DOP REGION 1 UNIF CONC 1E16 N TYPE
225. he van Dort quantum effects approximation model D DORT user specifiable model parameter for the van Dort quantum effects approximation model LASER Simulation Parameters CAVITY LENGTH specifies the cavity length in the longitudinal direction in um GAINMOD specifies the local optical gain model to be used e GAINMOD O specifies that no optical gain model will be used e GAINMOD I specifies that the complex frequency dependent gain model will be used see Equation 9 3 e GAINMOD 2 specifies that the simple gain model will be used see Equation 9 6 LASER enables LASER simulation LMODE specifies that multiple longitudinal models are to be taken into account during LASERT simulation LAS ABSORPTION enables the absorption loss model in LASER LAS EINIT LAS EFINAL specify the lower and upper photon energies LASER will calculate multiple longitudinal photon rates within this range Using wide ranges can slow down simulation LAS ESEP specifies the photon energy separation If this is not specified LASER will automatically calculate the number of longitudinal modes based on the cavity length and the energy range LAS FCARRIER enables the free carrier loss model in LASER LAS ITMAX specifies the maximum number of iterations allowed for LASER simulation at each bias point LAS LOSSES specifies the total losses in Equation 9 8 LAS MAXCH specifies the maximum allowable relative charge in photon densities between iterations Rapid change
226. his is because the y direction mesh is built up using the ADDLAYER statement The ADDLAYER statement makes a layer of the specified thickness in microns with the number of mesh points in the y direction specified by the DIVISION parameter ADDLAYER thick lt VALUE gt mask lt layer_name gt division lt INTEGER VALUE gt The MASK parameter tells ATLAS which mask to use from the MaskViews layout The layer name must correspond exactly with the layer name in MAskViEWS ATLAS assumes the drawn features are metallic regions and the clear regions insulator If no MASK parameter is used ATLAS assumes the layer is completely formed from insulator Defining Electrodes Electrode specification in INTERCONNECT3D is different from other ATLAS simulations Typical structures for INTERCONNECT3D consist of many metal conductors embedded in blocks of insulator Some of the metal conductors are connected to make an interconnect Each interconnect needs to be 12 4 SILVACO International INTERCONNECT3D defined by a unique electrode number or name INTERCONNECT3D connectivity between conductors is done automatically with no user intervention required There are several methods electrodes can be defined for INTERCONNECT3D e Define electrodes as usual in ATHENA DEVEDIT3D or ATLAS See Getting Started for details This method is typical if the DEVEDIT3D interface is used for conductance calculations
227. hottky contacts E TUNNEL specifies that the Schottky tunnelling model for electrons will be used E TUNNEL will also enable the SURF REC boundary condition which models the thermionic emission in a Schottky contact F ETUNNEL specifies the name of a file containing a C INTERPRETER function that specifies electron tunnelling at a Schottky contact ME TUNNEL specifies the relative effective mass for use in the electron tunneling mode see E TUNNEL SURF REC specifies that finite surface recombination velocities are used at the respective contact This parameter must be specified in the form SURF REC VSURFN n VSURFP lt p gt where n and p are real numbers VSUREN specifies the actual surface recombination velocities for electrons V If this parameter is not specified its default value is calculated by Equation 15 1 ARI cau T Augur 15 1 where ARICHN is the effective Richardson constant for electrons This constant accounts for quantum mechanical reflections and tunneling VSURFP specifies the actual surface recombination velocities for holes V If this parameter is not specified its default value is calculated by Equation 15 2 2 ARICHPT 15 2 where ARICHP is the effective Richardson constants for holes This constant accounts for quantum mechanical reflections and tunneling 15 12 SILVACO International CONTACT Statement Statements Contac
228. i 14 43 C both the XNORM RHSNORM parameters are true the convergence criteria for Equations 14 36 14 37 for carrier temperature are fulfilled and for the inequalities Equations 14 32 and 14 38 Equations 14 33 and 14 39 Equations 14 34 and 14 40 Equations 14 35 and 14 41 one of the conditions is fulfilled for every pair d if the current convergence criteria are satisfied and condition a or condition b or condition c is fulfilled for w w WEAK Convergence Criteria For Block Iteration For the potential equation and the continuity equations the X norms and RHS norms are defined as for the Newton method by Equations 14 19 to 14 21 and Equations 14 26 to 14 27 With s as an index that denotes the number of block iterations update errors between successive pairs of block iterations for lattice and carrier temperature are defined by the following expression For lattice temperature stl 5 _ nmax nmax 14 44 sl n where mmax is the number of the node where TL has its maximum value For electron temperature 5 1 5 py T 14 45 41 m T 14 14 SILVACO International Numerical Techniques For hole temperature 5 1 5 max E B m Ts r 14 46 p max stl m Block iterations are terminated if r S TLl 14 47 B lt TC r STC 14 48 Bi lt TI 14 49 and one of the foll
229. ial guess strategies that are not optimum When solving general systems of non linear equations there are no guarantees that any particular method will always work It is also the case that different methods can work better for different problems Fortunately there is now a lot of practical experience concerning the numerical techniques that are effective for device simulation This practical experience has been captured in ATLAS in the form of default methods and parameters that work well in almost all circumstances This chapter provides advanced information of interest to users who want to change the defaults Meshes The specification of meshes involves a trade off between the requirements of accuracy and numerical efficiency Accuracy requires a fine mesh that can resolve all significant features of the solution Numerical efficiency requires a coarse mesh that minimizes the total number of grid points This trade off between accuracy and numerical efficiency is frequently a source of problems for beginners Fortunately enough experience to define reasonable meshes is soon acquired ATLAS uses triangular meshes Some triangulations yield much better results than others Mesh generation is still an inexact science but guidelines and heuristics for defining satisfactory meshes exist Good triangulations have the following features They contain enough points to provide the required accuracy They do not contain too many unnecessary po
230. ical HALFIMPLICIT jogica l HCIR TOL Real HCIX TOL Real HOLES jogica ICCG jogica IR TOL Real ITLIMIT Integer IX TOL Real LUICRI Real LU2CRI Real L2NORM Logical AXTRAPS Integer MAX TEMP Real MEINR Logical MIN TEMP Real NEG CONC ogical NEWTON 1 Integer NRCRITER Real NO POISSON Logical PR TOL Real PX TOLER Real RHSNOR RXNORM ogical QUASI ogical SEMIIPLICIT jogica l SINGLEPOISSON ogical TAUTO ogical TCR TOL Real Default Units 100 False False 5 0x10 5 0x10 4 True False 530310 1 25 2 0 107 3 0x10 3 0 1072 True 2000 K False 120 K False True LS False 1 0x10 9 1 0 1075 False False True False False True 100 15 70 SILVACO International METHOD Statement Statements Parameter TCX TOL TLR TOL TLX TOL TMIN FACT TOL LTEMP TOL RELAX TOL TIME TRAP TSETP INCR V TOL VSATMOD INC XNORM WEAK Description Type Real Real Real Real Real Logical Real Real Real Logical Real Default 0 001 5 0x10 True Units The METHOD statement is used to set the numerical methods for subsequent solutions All structure and model defintions should precede the covergence Parameters to select the Solution Method ETHOD statement and all biasing conditions should follow it Parameters on the METHOD statement
231. ically or from an input file Syntax DOPING lt prof gt lt psp gt lt bound gt lt loc gt lt sprea gt gt OUTFILE lt fn gt lt trps gt Parameter Type Default Units ACTIVE Logical True ANTIMONY Logical False ARSENIC Logical False ASCII Logical False ATHENA Logical False ATHENA 1D Logical False BORON Logical False CHARACTERISTIC Real um CHEMICAL Logical False CONCENTRATION Real 0 cm DEGEN Real DEVICE Char 1 DIRECTION Character DOPOFF Real 0 cm DOSE Real cm ERFC LATERAL Logical False E LEVEL Real eV F COMPOSIT Character F DOPING Character F3 DOPING Character F OXCHARGE Character GAUSSIAN Logical False INDIUM Logical False INFILE Character JUNCTION Real um LAT CHAR Real um SILVACO International 15 21 ATLAS User s Manual Volume 2 DOPING Statement Parameter MAST Gl N TYP ti NET OUTFILE JU HOSPORUS Gl RATIO LAT REGION RESISTI Gl REGION SIGN SIGP SLICE LAT START SUPREM3 TAUN TAUP TRAP UNIFORM X MIN X RIGHT Y BOTTOM Y COMP Y MAX Y MIN Y TOP Z BACK ERAL Type Logical Logical Logical Character Logical Logical Real Real Real
232. ice coordinates to specify the maximum x value for refinement X MIN uses device coordinates to specify the minimum x value for refinement Y MAX uses device coordinates to specify the maximum y value for refinement Y MIN uses device coordinates to specify the minimum y value for refinement Control Parameters ABSOLUTE specifies that the absolute value of the variable be used CHANGE determines whether to use the magnitude or the difference of a triangle variable as the refinement criterion This parameter defaults to difference COS ANGLE limits the creation of obtuse angles in the mesh by specifying obtuse criterion If this parameter is used nodes are added to the mesh so that the number of obtuse triangles is reduced Note Be careful when using the COS ANGLE parameter Recommended values are from 0 8 to 0 95 Smaller values may dramatically increase the number of nodes LOCALDOP specifies that if minority carrier concentration exceeds local doping the grid will be refined This parameter is used in conjunction with minority carrier regrids LOGARITHM specifies a logarithmic refinement scale Since many of the quantities may become negative numerical problems are avoided by using log x sign x log10 1 Ixl If you wish to obtain the true logarithm of a quantity the ABSOLUTE parameter must be specified before the LOGARITHM parameter is specified The absolute value of a quantity is computed first thereby eliminating negat
233. icides SPDB CMP MC Deposit MC Implant Process Adaptive Meshing S Pisces Blaze Device3D Thermal3D Interconnect3D Blaze 3D Giga3D MixedMode3D TFT Luminous Giga MixedMode ESD Laser FastBlaze FastMixedMode FastGiga FastNoise MOCASIM UTMOST UTMOST II UTMOST III UTMOST IV PROMOST SPAYN SmartSpice MixSim Twister F astSpice SmartLib SDDL EXACT CLEVER STELLAR HIPEX Scholar SIREN Escort Starlet Expert Savage Scout Guardian and Envoy trademarks of SILVACO International 1990 1991 1992 1993 1994 1995 1996 1997 1998 2000 by SILVACO International Inc SILVACO International ii Reader Comment Sheet We welcome your evaluation of this manual Your comments and suggestions help us to improve our publications If you have any responses to the questions below please let us know Write your observations complaints bug reports suggestions or comments below e this manual technically accurate e Are the concepts and wording easy to understand e Is the size of this manual convenient for you e Is the manual s arrangement convenient for you Do you consider this manual to be easily readable Please add any additional relevant comments Please fax your comments to SILVACO International Attention Technical Publications at 408 496 6080 iv SILVACO International Introduction Intended Audience The information presented is based on the assumptions that the reade
234. ield Emission Boundary Condition Solid State Electronics Vol 36 No 3 pp 321 330 1993 Vendelin G D Design of Amplifiers and Oscillators by the S parameter Method Wiley New York 1982 ISBN 0471092266 Takahashi Y Kunihiro K and Ohno Y Two Dimensional Cydic Bias Device Simulator and Its Applications to GaAs HJ FET Pulse Pattern Effect Analysis IEICE J ournal C J une 1999 SILVACO International BIB 7 ATLAS User s Manual This page intentionally left blank BIB 8 SILVACO International Index Symbols 4 9 Numerics EDE E 11 1 13 1 ADSOMDUOM 8 6 Absorption LOSS s 1 neca tente 9 2 9 5 AC ANALYSIS 15 134 15 138 Affinity ze hentai ded MRS e aed 3 24 5 3 E 5 20 AIG AAS 5 20 ALIGN ci aro tco rei rm a aan 2 21 Anti Reflective 05 1 020 8 5 15 42 Auger Auger Available Photocurrent Avalanche breakdown Bandgap Narrowing ees 3 3 3 7 4 5 4 8 5 18 5 23 EE 5 25 15 58 15 98 Band to Band Tunneling Barbier actrice ett tt eec tuat ete d et
235. ifies that the CVT transverse field dependent mobility model is used for the simulation FLDMOB specifies a lateral electric field dependent model see Equations 3 198 and 5 50 The EVSATMOD parameter may be used to define which field dependent equation is used KLA specifies that the Klaassen mobility model See Equations 3 132 3 157 will be used for electrons and holes MIN SURF specifies that the WATT TASCH or SHI mobility models should only apply to minority carriers MOBMOD specifies mobility degradation by longitudinal electric field only MOBMOD 1 or by both longitudinal and transverse electric fields MOBMOD 2 When MOBMOD 2 the parameters ACC SF INV SF OX BOTTOM OX LEFT and OX RIGHT This parameter is only used with TFLDMB1 and TFLDMB2 SHI specifies that the Shirahata mobility model See Equation 3 197 will be used for electrons and holes SURFMOB or WATT invokes the effective field based surface mobility model see Equations 3 190 and 3 191 SURFMOB parameters are used in the calculation of surface mobility according to the J T Watt model Do not specify this parameter unless S PISCES is installed on your system TFLDMBI or SCHWARZ specifies the use of transverse electric field dependent mobility models The electron model is based on the Schwarz and Russek equations 6 and is implemented in 7 The hole model which is used only when MOBMOD 2 is based on the Watt and Plummer equations TFLDMB 2 T
236. ilibrium at each timestep Numerical Method Defintion Example The default numerical method is the equivalent of METHOD NEWTON CARRIERS 2 For more complex problems including those involving floating regions the following is recommended METHOD GUMMEL NEWTON GUM INIT 5 15 74 SILVACO International METHOD Statement Statements When impact ionization is combined with floating regions as in SOI or guard ring breakdown simualation the above syntax can also be used However quicker solutions can be obtained using the SINGLEPOISSON technique METHOD GUMMEL NEWTON GUM INIT 5 SINGLE TRAP Parameter Example This example illustrates the trap feature often used to capture knees of I V curves for junction breakdown The first SOLVE statement solves for the initial zero bias case In the second SOLVE statement we attempt to solve for V2 3 volts and V3 5 volts If such a large bias change caused the solution algorithms to diverge for this bias point the bias steps would be multiplied by ATRAP 0 5 An intermediate point V2 1 5 volts V3 2 5 volts would be attempted before trying to obtain V2 3 volts and V3 5 volts again If the intermediate point can not be solved for either case then the program will continue to reduce the bias step the next would be V2 0 75 volts and V3 1 25 volts up to MAXTRAPS times METHOD TRAP ATRAP 0 5 SOLVE INIT SOLVE V2 3 V3 5 OUTFILE
237. im Tunneling Model Parameters used in this model are F AE and F BE F AE is the pre exponential factor and F BE is the exponenential coefficient see Equation 3 274 WATT or SURFMOB Model The parameters which may be used with the WATT model include ALN1 ALN2 ALN3 ALP1 ALP2 ALP3 ETAN ETAP MREFN1 MREFN2 MREFN3 MREFP1 MREFP2 and MREFP3 see Equations 3 190 and 3 191 TFLDMB1 and TFLDMB2 Models ACC SF specifies the accumulation saturation factor which describes the ratio of the majority carrier concentration in the accumulation layer before and after bending of conductivity and valence bands INV SF specifies the inversion saturation factor which describes the ratio of the majority carrier concentration in the inversion layer before and after the bending of conductivity and valance bands OX BOTTOM specifies the coordinate of the bottom edge of the gate oxide for a MOSFET transistor OX LEFT specifies the coordinate of the left edge of the gate oxide for a MOSFET transistor OX RIGHT specifies the coordinate of the right edge of the gate oxide for a MOSFET transistor CONCANNON Model Parameters CGATEN specifies an empirical tuning factor for electrons in the Concannon gate current model CGATE P specifies an empirical tuning factor for holes in the Concannon gate current model PEFF N specifies an effective barrier height for electrons in the Concannon gate current model PEF
238. in ATLAS Arbitrary light sources are available within Luminous using the BEAM statement The program uses geometric ray tracing to determine the path of a light beam indudingrefraction and reflection of non normally incident light It then applies models for the absorption of the light to determine the photogeneration rate To use luminous the use should first define a light source using the BEAM statement and then choose the light intensity using a SOLVE statement The BEAM statement can be explained by a simple example The following syntax generates the ray tracein Figure C 1 BEAM NUM 1 X ORIGIN 3 0 Y ORIGIN 5 0 ANGLE 60 0 MIN W 1 MAX W 1 WAVEL 0 6 REFLECT 2 The parameter NUM sets the beam number LUMINOUS can applications up to 10 independent beams X ORIGIN and vy ORIGIN define the initial starting point for the light beam This must be outside the device coordinates and for non normal beams it is important to keep this point well away from the device The ANGLE parameter determines the direction of the light beam relative to the x axis ANGLE 90 gives normal incidence from the top of the device The light is defined as coming from a line perpendicular to the direction set by ANGLE and passing through X ORIGIN Y ORIGIN and MIN W set a window along this line through which the light passes The default for these parameters is infinity The wavelength of the light beam is defined in micron
239. in THERMAL3D The following values are recommended for thermal conductivity of GaAs and Si For GaAs use model B with MATERIAL TCON POWER TC CO 0 44 TC POW 1 25 For Si use model B C or D with model B MATERIAL TCON POWER TC CO 1 55 TC POW 1 33 model C MATERIAL TCON POLYN TC A 0 03 TC B 1 56e 3 TC C 1 65e 6 model D MATERIAL TCON RECIP TC E 320 TC D 80 Numerical Methods No special numerical methods are required for thermal simulation A METHOD statement with no parameters is assumed by default Obtaining Solutions In THERMAL3D The SOLVE statement in used in THERMAL3D for heat flow solutions much the same as it is used in other ATLAS simulations involving electrical biases The temperature in kelvin on each heat sink is used to prescribe the boundary condition temperatures For example SOLVE T1 300 T2 500 sets the temperature at 300 K and 500 K on heat sink 1 and 2 respectively Multiple SOLVE statements are allowed in THERMAL3D This is useful for obtaining solutions for several combinations of heat sinks and thermal power sources A range of solutions can also be obtained by stepping the value of a heat sink or power source For example SOLVE 1 300 POWER2 0 35 POWER3 0 4 NSTEPS 5 STEPREGION 3 POWERFINAL 0 8 OUTFILE thermal_out0 increments the thermal power source region 38 from 0 4 watts to 0 8 watts 5 steps and
240. in the METHOD statement It is difficult to specify a reasonable default value for the parameter CLIM DD in all situations In many difficult cases the round off numerical errors do not allow for the resolution of very low concentrations The default value of c 1M1T is set at 10 the corresponding default value for CLIM DD in Silicon i s 4 5 1013 In simulation of breakdown a lower value of CLIM DD 108cm3 for Silicon diodes should be specified otherwise a false solution may be obtained Discussion of CLIM EB To estimate errors in the lattice temperature equation and the energy balance equations corresponding RHS norms and X norms are calculated in ATLAS Updates to temperature are measured relative to some characteristic value of temperature The parameter CLIM EB can be viewed as a regularization parameter for the case of very small electron or hole densities in the energy balance equations The CLIM EB parameter specifies the minimum value of concentration for which the relaxation term in the energy balance equation will be properly resolved The temperatures for points where the concentration is much less than CLIM EB are equal to the lattice temperature The units of CLIM are cm and the default is 0 0 Terminal Current Criteria Another qualification for convergence is derived from the relative changes in terminal currents and the satisfaction of total current conservation This qualification can
241. in the manual as well as the code Referring to the ATLAS Users manual E dition 2 in the equations B 36 and B 37 the y s should be replaced by 1 y This fix was introduced into the code for this release e Fixed a bug in the calculation of electric fields for output to structure files for examination in TONY PLOT This bug caused the estimates of the X and Y components of the electric field to be calculated based on the dielectric constant of silicon for all semiconductors Although the calculation properly handled insulators it used the dielectric constant of silicon for all semiconductors regardless of composition This has been fixed in this version Fixed bug causing extra spacein UTMOST format output log files SILVACO International D 9 ATLAS User s Manual Volume 2 16 New examples In this release the standard examples were completely reworked and improved The ATLAS examples are now divided into 21 application specific areas There are now 117 ATLAS examples in all which illustrate virtually all the functionality of ATLAS 17 Improved quality control In this version new quality control tools and procedures for automated testing were implemented used that greatly simplify and expanded ATLAS testing This version of ATLAS represents the most thoroughly tested version to date Continued application of the improved quality control procedures will ensure that future versions will continue to be of the highest quality
242. ind all the capacitances of the system This computational effort is reduced drastically by 1 Calculating and storing the potential distributions with respect to a set of n orthogonal bias sets SILVACO International 12 1 ATLAS User s Manual Volume 2 2 Constructing further potential distributions through linear superposition of potential values from the existing solutions In this way the number of full calculations required to solve the 3D problem is reduced from n n 1 2 calculations to n calculations Pte X ense mus Ei coset mim CE e drm m em INSULATOR contact 1 E PM SIMULATED REGION pes ssl Figure 12 2 What INTERCONNECTSD actually simulates These image conductors influence the simulation results if they are too close to the conductors in the simulated region To minimize this influence you must make the structure large enough so that there is enough distance between the image conductors to make the effect negligible 12 2 SILVACO International INTERCONNECT3D When conductances are being investigated equation 12 1 is solved in conducting regions with defined potentials on contacts and with 7 set to the electrical conductivity The local current density is calculated as oVy Structure De
243. inear ramps RAMPTIME specifies a ramp interval in seconds i e the ramp will begin at and ends at t tg RAMPTIME SINUAMP COMP specifies that sinusoidal amplitude compliance will be used The transient simulation will stop if the amplitude of a sinusoidal waveform is less than the value of SINUAMP COMP SINUVAR COMP specifies that sinusoidal variance compliance will be used The transient simulation will stop if the change in amplitude of a sinusoidal waveform is less than SINUVAR COMP SQPULSE specifies that multiple trapazodial square transient pulses will be applied The pulse is controlled by the parameters TDELAY TRISE PULSE WIDTH TFALL and FREQUENCY T COMP specifies a temperature for temperature compliance Once the specified temperature is obtained at some location on the mesh the solution process is discontinued T SAVE specifies a time increment at which the device structure files are saved Note Actual time steps may not correspond to the user specified increment TDELAY specifies the time delay before the first cycle of multiple trapazodial square transient pulses SOPULSE will be applied wm SILVACO International 15 133 ATLAS User s Manual Volume 2 SOLVE Statement TFALL specifies the fall time for trapazodial square transient pulses SQPULSE TRISE specifies the rise time for trapazodial square transient pulses SQPULSE TRANS ANALY specifies that transien
244. ing Gummel loop iterations with lattice temperature These parameters help insure that lattice temperatures converge during the outer loop iterations NBLOCKIT specifies the maximum number of BLOCK iterations If METHOD BLOCK NEWTON is specified the solver will switch to Newton s method after NBLOCKIT Block Newton iterations NEG CONC flag allows negative carrier concentrations NO POISSON flag allows omission of Poisson s equation in solution TMIN FACT specifies the minimum electron or hole temperature allowable during non linear iteration updates TMIN FACT is normalized to 300K TRAP specifies that if a solution process starts to diverge the electrode bias steps taken from the initial approximation are reduced by the multiplication factor ATRAP VSATMOD INC specifies that the derivatives of the negative differential mobility MODEL FLDMOB EVSATMOD 1 will not be included into the Jacobian until the norm of Newton update for potential is less than the value specified by VSATMOD INC This is useful since the nagative differential mobility model is highly nonlinear and causes numerical stability problems SILVACO International 15 73 ATLAS User s Manual Volume 2 METHOD Statement Gummel Parameters DVLIMIT limits the maximum potential update for a single loop GUMLINIT specifies the maximum number of Gummel iterations in order to obtain an initial approximation for successive Newton iterations This parameter is use
245. ints that impair efficiency SILVACO International 14 1 ATLAS User s Manual Volume 2 They avoid or at least minimize the number of obtuse triangles Obtuse triangles tend to impair accuracy convergence and robustness They avoid or at least minimize the number of long thin triangles These triangles also tend to impair accuracy convergence and robustness They allow the average size of triangles to change smoothly in transition from a region where very small triangles must be used to a region where the use of much larger triangles is acceptable The error associated with a mesh can beinvestigated systematically by repeating a calculation using a sequence of finer meshes This is very time consuming and is hardly ever done Thetypical approach is to adequately resolve structural features including doping with an initial or base mesh and then add nodes as required to resolve significant features of the solution The insertion of additional nodes regridding is normally done by the program using criteria specified by the user Theinitial mesh used by ATLAS can be specified in several ways it can be inherited from ATHENA it can be constructed using DEVEDIT or it can be specified using the ATLAS command language Meshes can be refined using ATLAS commands or using DEVEDIT The remainder of this section will focus on the capabilities available using ATLAS commands The capabilities provided by DEVEDIT documen
246. ion usually to one This leads to under relaxation of the potential update This single Poisson solution mode extends the usefulness of Gummel s method to higher currents It can be useful for performing low current bipolar simulations and simulating MOS transistors in the saturation region It is invoked by specifying the SINGLEPOISSON parameter of the METHOD statement Block Iteration ATLAS offers several block iteration schemes that are very useful when lattice heating or energy balance equations are included Block iterations involves solving subgroups of equations in various sequences The subgroups of equations used in ATLAS have been established as a result of numerical experiments that established which combinations are most effective in practice In nonisothermal drift diffusion simulation specifying the BLOCK method means that Newton s method is used to update potential and carrier concentrations after which the heat flow equation is solved in a decoupled step When the carrier temperature equations are solved for a constant lattice temperature the BLOCK iteration algorithm uses Newton s method to update potential and concentrations The carrier temperature equation is solved simultaneously with the appropriate continuity equation to update the carrier temperature and again carrier concentration When both the heat flow equation and the carrier temperature equations are included the BLOCK scheme proceeds as described previ
247. ion for the specification of temperature and composition dependent static dielectric constant models MASS VTHN specifies the electron effective mass for calculation of thermal velocity in the thermionic heterojunction model see Equation 5 45 MASS VTHP specifies the hole effective mass for calculation of thermal velocity in the thermionic heterojunction model see Equation 5 46 NC300 specifies the conduction band density at 300K see Equation 3 29 NV300 specifies valence band density at 300K see Equation 3 30 PERMITTIVITY specifies dielectric permittivity of the material All materials in an ATLAS structure must have a defined permittivity Mobility Model Parameters F CONMUN specifies the name of a file containing a C INTERPRETER function for the specification of temperature composition and doping dependent electron mobility models F CONMUP specifies the name of a file containing a C INTERPRETER function for the specification of temperature composition and doping dependent hole mobility models F MUNSAT specifies the name of a file containing a C INTERPRETER function for the specification of parallel field dependent electron mobility model for velocity saturation F MUPSAT specifies the name of a file containing a C INTERPRETER function for the specification of parallel field dependent hole mobility model for velocity saturation F VSATN specifies the name of a file containing a C INTERPRETER function for the specification
248. is more detailed information concerning error estimation and the specification of convergence criteria needed The material is organized by algorithm Convergence Criteria For Gummel s Algorithms Relative update errors are defined as follows for potential max K 1 K cp g om M m 14 6 K 1 max 1l K 1 K where mmax is the node where le has its maximum value For electrons 1 14 7 nm For holes max K 1 m Leld llc MI 14 8 max Cp For lattice temperature 1 J CI nidi 14 9 1 Pas K 1 where nmax is the node where Tj has its maximum value For carrier temperature Er max Er er 14 10 where max K 1 K me Ny Ep 14 11 n max T m nm 14 10 SILVACO International Numerical Techniques max K E g e 14 12 m pum For drift diffusion iterations are terminated if the following criteria are satisfied x lt 14 13 X Se 14 14 lt C 14 15 v tol In nonisothermal drift diffusion iterations are terminated if Equations 14 10 to 14 12 are satisfied the current convergence criteria in Equations 14 4 14 5 are met and x tol 14 16 r TL In Gummel s method with energy balance equations NI1TGUMM iterations in which only the non linear Poisson equation is solved will always be d
249. is specified then all regions defined as being composed of that material will be affected NAME specifies which region the MAT specified in the NAME parameter of the REGION statement ERIAL statement should apply Note that the name must match the name REGION specifies the region number to which these parameters apply If there is more than one semiconductor region specification of different parameters for each region is allowed If REGION is not specified all regions in the structure are changed Band Structure Parameters AFFINITY specifies the electron affinity ALIGN specifies the fraction of the bandgap difference that is applied to the conduction band edge relative to the minimum bandgap material in the device Note that specifying this parameter overrides any electron affinity specification See the BLAZE chapter for notes on setting the band alignment SILVACO International 15 57 ATLAS User s Manual Volume 2 MATERIAL Statement ARICHN specifies the effective Richardson constant for electrons ARICHP specifies the effective Richardson constant for holes EG300 specifies energy gap at 300K see Equation 3 36 All semiconductor materials in ATLAS must have a defined EG300 FBANDCOMP specifies the name of a file containing a C INTERPRETER funciton for the specification of temperature and composition dependent band parameter models F EPSILON specifies the name of a file containing a C NTERPRETER funct
250. is the default Choosing RCM instead of MD sometimes solves the problem of having a zero on the diagonal which is indicated by the error message Internal error in linear solver Z If this happens the user should switch from MD to RCM or vice versa e For Parallel ATLAS two new mesh partitioning techniques are now available Natural Ordering NO and Multi level Graph Partitioning MGP These are used to assign sub meshes to different processor MGP is the default and should always outperform NO On the other hand NO requires less preprocessing time and might perform as well as MGP in the case of meshes generated by the ATLAS statement e Madeit possible to use projection for initial guesses in conjunction with current boundaries 11 Structures and Log File Improvements e Added the capability to write X G rhs errors in a standard structure file for subsequent visualization using TONYPLOT e Added the capability to save electron hole relaxation times and Peltier coefficients to SILVACO International D 3 ATLAS User s Manual Volume 2 structure files Added the capability to save electron hole and displacement currents to log files 12 New Quantum models Implemented a new self consistent Schrodinger Poisson solver This model interactively solves Poisson s and Schrodinger s equations to calculate the potential and carrier concentration including the effects of quantum confinement Th
251. it in a calculation and substitute it into the ATLAS syntax for REGION definition SET MYLENGTH 0 1 SET HALFLENGTH MYLENGTH 0 5 REGION NUM 1 MATERIAL SILICON X MIN S HALFLENGTH X MAX S MYLENGTH String Variable Example Define a string variable to use as part of a filename SET LABEL testcasel LOG OUTF S LABEL log I SAVE OUTF bias S S LABEL 25 str This will produce files called testcasel log and bias testcasel 25 str 15 122 SILVACO International SAVE Statement Statements SAVE SAVE saves all node point information into an output file Note In all cases the region boundaries electrodes mesh and doping are saved If a SOLVE statement has preceded the SAVE statement all electrical data from the last solution is stored Syntax SAVE OUTFILE lt filename gt MASTER Parameter Type Default Units OUTFILE Character MASTER Character True PISCES Logical False PATTERNS Character STRUCTURE Character False Description OUTFILE specifies the name of an output file name MASTER specifies that the output file will be written in a standard structure format Files in this format can be plotted in TONYPLOT STRUCTURE Synonym for save PISCES specifies that the output file will be written in the original 5 5 11 format PATTERNS specifies a character string representing the root of the file names
252. ive arguments MAX LEVEL specifies the maximum level of any triangle relative to the original mesh This parameter defaults to one more than the maximum level of the grid but can be set to a smaller value to limit refinement Values less than or equal to zero are interpreted relative to the current maximum grid level SMOOTH KEY specifies a smoothing index The digits of the index are read in reverse order and interpreted as follows 1 Triangle smoothing All region boundaries remain fixed 2 Triangle smoothing Only material boundaries are maintained 3 Node averaging 4 Improved triangle smoothing method This method uses diagonal flipping to reduce the number of obtuse triangles 5 Aligns triangles with electric field gradient Usually option 1 is sufficient Option 2 is useful only if a device has several regions of the same material and the border between different regions is unimportant Option 3 is not recommended when the initial mesh is basically rectangular such as mesh information usually obtained from SSU PRE M4 Option 4 is similar to option 1 but option 4 usually creates less obtuse triangles File I O Parameters ASCII specifies that mesh files and triangle trees will be written in an ASCII rather than a binary format This parameter has no effect on the device doping file see the DOPFILE parameter DOPFILE specifies the name of a file which contains device doping information This file is created on the DOPING
253. ization Bug caused lack of convergence Interpreter Fixed bug in F DOPING Interpreter function for specifying doping Material Fixed bug to allow Interpreter functions in material statement to be defined for given material Region Interface Fixed bug to resolve ambiguities in definition of region membership of nodes at interface between two regions Holes Fixed bug that caused holes in regions or embedded regions to be improperly displayed in TonyPlot Trap Recombination Fixed bug in recombination calculation for regionally specified traps Transient Projection Algorithm Installed transient projection algorithm Improved Interpreter Function for Complex Index of Refraction The Interpreter function for complex index of refraction was changed to account for material composition and temperature D 10 SILVACO International ATLAS Version History 18 New Built in Index Data Added built in complex index of refraction data for AlAs GaAs InSb InP Polysilicon and 5102 19 Light Intensity Contours Added interface to TONY PLOT for optical intensity To enable set the OPT INTENS parameter of the OUTPUT statement 20 New Interpreter Function Added Interpreter function for general generation rate as a function of position 21 Cylindrical Coordinates LUMINOUS now supports cylindrical coordinates Specify CYL on the MESH statement 22 Energy Balance Modeling LUMINOUS is now supported in e
254. l increase to 35 W cm and beam 3 will increase to 45 W cm SOLVE LIT STEP 5 0 NSTEP 4 In the next example the beams are ramped in the time domain Beam 1 is ramped down to 0 W cm and beam 3 is ramped up to 100 W cm The duration of the ramp is 1 ns After the ramp simulation will continue for 4 ns SOLVE 1 0 3 100 RAMP LIT TSTEP 2E 11 RAMPTIME 1E 9 5 5 9 Next the small signal response of a single beam is analyzed First ATLAS will solve the DC characteristics at the specified optical spot powers Then the AC response of beam 1 will be calculated at a frequency of 10 MHz SOLVE 1 10 B3 20 BEAM 1 FREQUENCY 1e7 SS PHOT SS LIGHT 0 01 Finally frequency stepping is used to look at the small signal AC frequency response of one of the beams AC response is calculated at frequencies from 1kHz to 100MHz at each decade The MULT F parameter is used to geometrically increase the frequency SILVACO International 15 137 ATLAS User s Manual Volume 2 SOLVE Statement SOLVE 1 10 B3 5 BEAM 1 SS PHOT SS LIGHT 0 01 MULT F FR lonization Integral Example EQU ENCY 1 E3 FST EP 10 NFSTI EP 6 Ionization integrals are used to estimate the breakdown voltage from analysis of the electric field They can be used in Zero carrier mode providing much faster simulation that conventional breakdown analysis The ioni
255. l syntax that can be applied to remesh structures read directly from ATHENA DEVEDIT employs a heirachical method for remeshing existing structures Users specify mesh parameters at each stage Initially a base mesh is applied with the command BASE MESH lt 1 gt WIDTH lt wl gt This mesh of h1 by w1 microns provides the coarsest mesh in the structure On top of this base level mesh DEVEDIT determines which points must be added to ensure the geometry of all regions is preserved Optional boundary conditioning to smooth region boundaries can be applied using the BOUND COND statement Mesh constraints can be applied to arbitrary boxes with the device using the syntax constr mesh lt gt x2 n yl n y2 lt n gt max height h2 max width lt w2 gt This sets the maxi mum mesh size to h2 by w2 microns the box with diagonal from x1 y1 to x2 y2 Using the constraint boxes in critical areas of the device is the most effective way to use DEVEDIT In MOSFETS the constraint boxes can be applied to the silicon region under the gate Typically vertical grid spacings of 5 are required for accurate simulation of channel conduction in sub micron MOSFETs Use of multiple constraint boxes can be applied For MOSFET breakdown constraint boxes can be applied to the drain gate overlap area addition to constraint boxes DEVEDIT can refine on quantities such as individual doping species net doping potenti
256. l that allows users to define separate mobilities along normal directions e Also added a new default value for thermal conductivity and electron saturation velocity of silicon carbide Modifications to Laser Included additional functionality into Laser The new features are e transient mode time dependent photon rate equation e far field patterns e addtitional loss mechanisms including mirror loss free carrier loss absorption loss including C interpreter function for bulk absorption New Large Lignal and Simulation Capabilities e Added specifications of sinusoidal waveforms to the SOLVE statement e Implemented post processing Fourier analysis This performs a Fast Fourier Transform FFT on data within a log file to convert time domain data into frequency domain data D 2 SILVACO International ATLAS Version History e Added solution compliance based on sinusoidal analysis In this mode transient simulation will stop if the amplitude of a sinusoidal waveform is less than the user specified value 6 Modifications to LUMINOUS e Added capability to print the complex indices of refraction as they are calculated for the various materials during the ray trace in Luminous e Added functionality to simulate single layer antireflective coatings in Luminous This capability calculates the reflection coefficient for a single layer coating under conditions of normal incidence 7 Modifications to MixEDMODE e Added t
257. lberherr s impact ionization model Index 1 AN1 and BN1 corresponds to field values less than EGRAN and index 2 AP2 BP2 AN2 and BN2 corresponds to field values greater than EGRAN BETAN for electrons and BETAP for holes correspond to coefficients for the power of ECRIT E Temperature Dependence Parameters A NT specifies the value of the temperature dependent parameter in Equation 3 240 specifies the value of the temperature dependent parameter in Equation 3 241 B NT specifies the value of the temperature dependent parameter in Equation 3 242 B PT specifies the value of the temperature dependent parameter in Equation 3 243 M ANT specifies the value of the temperature dependent parameter in Equation 3 240 M APT specifies the value of the temperature dependent parameter in Equation 3 941 M BNT specifies the value of the temperature dependent parameter in Equation 3 242 M BPT specifies the value of the temperature dependent parameter in Equation 3 243 Parameters for use with Energy Balance Note When energy balance simulations are run the Toyabe impact ionization model is used This model is used irrespective of the settings SELB or CROWELL See the Physics Chapter for details F EDIIN specifies the name of the file containing a C INTERPRETER function describing the values of the parmeters in Equation 3 238 as a function of electron temperature F EDIIP specifies the name of the file containing a C I
258. ld be aware that although these band parameters may be physically inaccurate compared to bulk silicon measurements most other material parameters and models are empirically tuned using these band parameters Polysilicon is treated differently depending on how it is used In cases where it is defined as an electrode it is treated as a conductor It can also be used as a semiconductor such as in a polysilicon emitter bipolars The composition of SiGe is the only binary compound that can be varied to simulate the effects of band gap varia tions Conductor names are only associated with electrodes They are used for the specification of thermal conductivities and complex index of refraction and for display in TonyPlot Rules for Specifying Compound Semiconductors Therules for specifying the order of elements for compound semiconductors are derived from the rules used by thelnternational Union of Pure and Applied Chemistry 1 Cations appear before anions 2 When more than one cation is present the order progresses from the element with the largest atomic number to the element with the smallest atomic number 3 The order of anions should be the order of the following list B Si C Sb As N Te Se S At Br Cl and F 4 Thecomposition fraction x is applied tothe cation listed first 5 Thecomposition y is applied to the anion listed first To accomodate popular conventions there are several exceptions to these rules
259. le of rotation for the source beam direction of propogation relative to the x y plane see Fig 11 2 LUMINOUS3D only THINEST specifies the width of the thinnest ray to be traced LUMINOUS only MIN POWER specifies the minimum intensity relative to the source that a given ray will be traced This is useful for limiting the numbers of rays traced WAVELENGTH specifies the optical wavelength of the source beam in the vacuum for mono spectral simulations WAVEL END specifies the maximum wavelength of the source beam in the vacuum when multi spectral simulations are performed SILVACO International 15 7 ATLAS User s Manual Volume 2 BEAM statement WAVEL NUM specifies the number of wavelengths which will be used when multi spectral simulations are performed Spectral illumination is selected when the WAVEL NUM parameter is greater than 1 Once multi spectral simulations are selected you must specify the POWER FILE WAVEL START and WAVEL END parameters WAVEL SCAL specifies the scale factor for the wavelengths which are used in multi spectral simulations Each of the wavelengths in the spectrum file is multiplied by this scale factor WAVEL START specifies the minimum wavelength of the source beam in the vacuum when multi spectral simulations are performed XMAX specifies the maximum x coordinate in the source beam coordinate system for ray tracing in LUMINOUS3D see figure 11 3 XMIN specifies the minimum
260. lied SPACE MULT is a scale factor that is applied to all specified grid spacings This parameter can be used to produce a coarse mesh and therby reduce the simulation time ATHENA reads mesh and doping data generated by the ATHENA PISCES II format file This parameter and file format is obsolete Parameters Related to Creation of a New Mesh RECTANGULAR initiates the generation of a rectangular mesh CYLINDRICAL specifies that the mesh contains cylindrical symmetry Since this information is not saved in the mesh file the CYLINDRICAL parameter must be specified each time a grid with cylindrical symmetry is loaded Structures defined as cylindrical will be rotated 360 degress about the y axis The coordinate 0 must be on the extreme left hand side of the structure DIAG FLIP flips the diagonals in a square mesh about the center of the grid If the parameter is negated using DIAG FLIP is specified all diagonals will be in the same direction NX specifies the number of nodes in the x direction NY specifies the number of nodes in the y direction NZ specifies the number of nodes in the z direction used in DEVICE3D or BLAZE3D only WIDTH specifies a scale factor to represent the unsimulated dimension for 2 D simulations This scale factor is applied to all run time and log file outputs Output Parameters OUTFILE specifies the output filename to which the mesh is written MASTER OUT specifies the format of the output file This parame
261. llows users to specify misalignment and variations in critical dimensions with interconnects specified by mask sets from MASKVIEWS 11 Lumped elements and current boundary conditions in DEVICE3D DEVICE3D now supports lumped element and current boundary conditions 12 GaAs in DEVICE3D DEVICE3D now supports GaAs material models 13 Electric field lines Electric field lines can now be plotted in TONYPLOT The specification of where to elines lines are calculated was improved for both plotting and for evaluation of ionization integrals 14 Energy dependent impact ionization coefficients Two new C interpreter functions were introduced to enable user specification of impact ionization coefficients as a function of carrier temperature for Selberherr s model 15 Removed obsolete syntax The FIT COLOR CONTOUR LABEL LOOP L END PLOT 1D PLOT 2D and PLOT 3d statements are no longer supported by ATLAS Equivalent functionalities are available through DECKBUILD and TONYPLOT 16 DEVICE3D improvements for SEU simulation Introduced a new C interpreter function F3 RADIATE This function allows users to specify arbitrary generation rate versus spatial position and time The SINGLEEVENTUPSET statement was changed to allow users to control whether the generation rate is scaled by the ratio of the numerical and analytic integrals of the analytic generation function This permits conservation of total generation rate in a device By default the
262. lly specifies only the initial timestep with the TSTEP parameter of the SOLVE Statement After this time steps are derived from the LTE and will typically increase Small Signal and Large Signal Analysis There are several ways to predict the small signal and large signal high frequency properties of semiconductor devices review of these different techniques was presented by Frequency domain perturbation analysis F PDA can be used to determine the small signal characteristics while Fourier analysis of transient responses FATR can be used for both small signal and large signal response E ach technique has advantages and disadvantages Frequency Domain Perturbation Analysis Frequency domain perturbation analysis of a DC solution can be used to calculate small signal characteristics at any user specified frequency The calculation proceeds in the following manner l Variables are represented as the sum of the known DC component and a small unknown sinusoidal AC component 2 All equations are expanded 3 Differentiation in time becomes multiplication by the value of 2 frequency 4 Products of AC quantities are neglected since they are small with respect to other quantities 5 TheDC solution is subtracted What remains is a complex linear system whose unknowns are the AC components of the solution Solving this linear system with appropriate boundary conditions yields small signal characteristics The coe
263. many issues of interpolation and averaging of vector quantities onto the simulation grid If two physical quantities are probed at the same location it is possible to plot them against each other to examine model settings For example impact ionization rate or mobility versus electricfield Figure C 12 shows a plot of channel electron mobility in a submicron NMOS transistor versus the transverse electric field from the gate All of the primary solution quantities can be probed A full list is given in the manual under the PROBE statement In addition to values at point locations the PROBE statement also supports MIN and MAX parameters to find the minimum and maximum of a given quantity C 10 SILVACO International Hints and Tips File View Plot Tools Print Properties Help ATLAS ELECTRIC FIELD IN MOS GATE OXIDE DURING ESD PULSE OxideField 700000 600000 500000 400000 300000 Electric Field V cm 200000 100000 ref Gi beer be beh id Lien Dos UTE fA RITE TIR Pa GUTI AA T8 AEE URLE Fe 7 1 E 10 9 8 ET amp 5 Time s SILVACO International Figure C 11 Electric field in MOS gate oxide during a high current pulse on the drain File View Plots Tools Print Properties E ATLAS ELECTRON MOBILITY ROLLOFF vs FIELD IN MOS CHANNEL 4 8 e a e g
264. me steps e COMPLEX VALUES prints the real and imaginary components to file as well as the magnitude and phase Note FFT works best with uniform time steps therefore DT MIN pT MAx on the METHOD statement should be set to the same value The time step should be set to time step 1 number of samples fundamental frequency FFT can then calculate harmonic frequencies up to number of samples 2 1 fundamental frequency Small signal data at high frequencies can be obtained by calculating the terminal current responses to terminal voltage perturbations The currents and voltages should then Fourier analyzed Their ratio at each frequency provides admittance data for that frequency The voltage perturbations are normally selected to have an analytic form with a known Fourier transform Care must be taken to self consistently account for geometric capacitances when step function voltage perturbations are used The advantages of this technique arethat it can be used whenever transient calculations are possible and each transient solution gives information over a broad range of frequencies The main disadvantage is that transients become very long when low frequency effects are investigated Overall Recommendations 1 Use frequency domain perturbation analysis when it is available The method works for arbitrary frequencies and does not require transient calculations
265. miconductor Contacts Second Ed Oxford Science Publications 1988 W Hansch et al A New Self Consistent Modeling Approach to Investigating MOSFET Degradation IEEE Trans ED 11 p 362 1990 S Odanaka A Hiroki A Numerical Simulation of Hot Carrier Induced Device Degradation BIB 4 SILVACO International Bibliography 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 P Roblin A Samman S Bibyk Simulation of Hot Electron Trapping and Aging of nMOSFET s IEEE Trans ED 35 p 2229 1988 D P Wilt and A Yariv A Self Consistent Static Model of the Double Heterostructure Laser IEEE J ournal of Quantum Electronics Vol QE 17 No 9 1981 pp 1941 1949 K B Kahen Two Dimensional Simulation of Laser Diodes in Steady State IEEE J ournal of Quantum Electronics Vol 24 No 4 April 1988 T Ohtoshi K Yamaguchi C Nagaoka T Uda Y Murayama and N Chinone A Two Dimensional Device Simulator of Semiconductor Lasers Solid State Electronics Vol 30 No 6 pp 627 638 1987 G Hugh Song K Hell T Kerkhoven and U Ravaioli Two Dimensional Simulator for Semiconductor Lasers Proc of the Int IEEE Electron Device Metting Washington 1989 p 143 A Yariv Optical Electronics CBS College Publishing 1985 S Seki T Yamanaka and K Yokoyama Two Dimensional Analysis of Current Blocki
266. mple specifies SRH lifetimes and concentration independent low field mobilities for region number 2 All other parameters use default values and parameters in other regions are unaffected MATERIAL TAUN0 5 0E 6 5 0 6 MUN 3000 MUP 500 REGION 2 All regions This example defines carrier lifetimes and the refractive index for all semiconductor regions MATERIAL TAUPO 2 E 6 TAUNO 2 E 6 REAL INDEX 3 7 IMAG INDEX 1 0E 2 Named Material This shows the definition of bandgap for all InGaAs regions in the structure MATERIAL MATERIAL InGaAs EG300 2 8 Note The command MODEL PRINT can be used to echo back default material parameters or MATERIAL parameter settings to the run time output Note All materials are divided into three classes semiconductors insulators and conductors See Appendix B for important information about parameters required for each material class 15 62 SILVACO International MEASURE Statement Statements MEASURE M Note This statement is mostly obsolete and functions are replaced by the 1 OUTPUT statement or PROB EASURE Syntax MEASUR Parameter CONTACT E CRIT ELECTRON HOLE IONIZINT LRATIO ETAL CH N CURRENT N LAYER N LINES N RESIST NET CARR NET CHAR OUTFILE P CURRENT P RESIST REGIONS SUBSTR U AU
267. mulation Overview of 3D Device Simulation Programs Note This chapter aims to highlight the extra information required for 3 D simulation as compared to 2 D Users should be familiar with the equivalent 2 D models before reading this chapter This chapter describes the set of ATLAS products that extends 2D simulation models and techniques and applies them to general non planar 3D structures The structural definition models and material parameters settings and solution techniques are similar to 2D Users should be familiar with the simulation techniques described in the Getting Started and equivalent 2D product chapters before reading the sections that follow The products that form 3D device simulation in ATLAS are DEVICE3D silicon simulation equivalent to S PISCES BLAZE3D compound material and heterojunction simulation e GIGA3D non isothermal simulation MIXEDMODE3D mixed device circuit simulation TFT3D thin film transistor simulation e QUANTUM3D quantum effects simulation e LUMINOUS3D photodetection simulation Two other 3D modules INTERCONNECT3D and THERMAL3D are documented in separate chapters In a similar manner to the 2D products GIGA3D MIXEDMODE3D LUMINOUS3D QUANTUM3D should be combined with both DEvICE3D or BLAzE3D depending on the semiconductor materials used DEVICE3D Device3D provides semiconductor device simulation of silicon technologies It s use is anagous to the 2 D simula
268. n Shaw M Shur and P Yap Physics of Novel Amorphous Silicon High Voltage Transistor Mat Res Soc Symp Proc Vol 95 p 457 1987 T Shaw and M Hack An Analytical Model for Calculating Trapped Charge in Amorphous Silicon J ournal of Applied Physics 6419 p 4562 1988 J Smith Ph D Thesis Pennsylvania State University 1992 G K Wachutka Rigorous Thermodynamic Treatment of Heat Generation in Semiconductor Device Modeling IEEE Trans Computer Aided Design Vol 9 No 11 pp 1141 1149 1990 R Stratton Semiconductor Current Flow Equations Diffusion and Degeneracy IEEE Trans ED Vol ED 19 No 12 pp 1288 1292 1972 A Nakagawa and H Ohashi A Study on GTO Turn off Failure Mechanism A Time and Temperature Dependent 1 D Model Analysis IEEE Trans ED Vol ED 31 No 3 pp 273 279 1984 P Mars Temperature Dependence of Avalanche Breakdown Voltage in p n J unctions International J ournal of Electronics Vol 32 No 1 pp 23 27 Handbook of Chemistry and Physics Editor R C Weast M Klausmeier Brown M Lundstrom M Melloch The Effects of Heavy Impurity Doping on AlGaAs GaAs Bipolar Transistors IEEE Trans ED 36 No 10 pp 2146 2155 1989 J Dorkel and Ph Leturcg Carrier Mobilities in Silicon Semi Empirically Related to SILVACO International BIB 3 ATLAS User s Manual 67 68 69 70 71 72 73 74 75 76 77 78 79
269. n this parameter specifies only an initial estimate of the photon energy Instead of using this parameter LAS OMEGA can be used to specify the lasing frequency SPEC NAME specifies the name of a spectrum file which LASER will produce for each bias point if the LMODES parameter has been specified Model Selection Example This example selects concentration and field dependent mobilities SRH recombination and Auger recombination This is a typical model set for bipolar simulation The simulation temperature is 290K MODELS CONMOB FLDMOB SRH AUGER TEMP 290 Confirming Model Selection To echo back model selections parameters and material constants use MODELS PRINT Note For the best MODEL selection for different applications consult the Standard Example set 15 104 SILVACO International OPTIONS Statement Statements OPTIONS OPTIONS sets options for an entire run Syntax OPTIONS lt rcp gt Parameter NORMAL QUIET VERBOSE Description Type ogical Default True False False Units rcp is one or more of the run control parameters described below These parameters which are not normally used specify debugging options NORMAL is the default specification for run time output filtering At this setting ATLAS prints out the most relevant information e g mesh statistics terminal voltages curren
270. n 10 and 108 Fortunately the matrices are sparse i e most of the entries are zero and need not be stored explicitly The sparsity arises because the variables at each node are coupled to only a few neighboring nodes Special direct techniques are available for solving sparse matrices Direct techniques are preferred for relatively small problems They provide reliable solutions that are exact to within roundoff error in a timethat is predictable Iterative techniques are preferred for very large probl ems because they are faster and require less memory Direct techniques for solving sparse matrices have a competitive performance for the problem sizes typically encountered in 2 D device simulation and are used by ATLAS to solve most of the linear subproblems that arise Convergence Criteria for Non linear Iterations After a few non linear iterations the errors will generally decrease at a characteristic rate as the iteration proceeds Non linear iteration techniques typically converge at a rate that is either linear or quadratic The error decreases linearly when Gummel iteration is used i e it is reduced by about the same factor at each iteration For Newton iteration the convergence is quadratic i e small errors less than one are approximately squared at each iteration The non linear iteration is terminated when the errors are acceptably small The conditions required for termination are called convergence criteria Much effort has gone into
271. n ATLAS by a set of anywhere from one to six coupled non linear partial differential equations PDEs ATLAS produces numerical solutions of these equations by calculating the values of unknowns on a mesh of points within the device An internal discretization procedure converts the original continuous mode to a discrete non linear algebraic system that has approximately the same behavior The set of PDEs the mesh and the discretization procedure determine the non linear algebraic problem that must be solved The non linear algebraic system is solved using an iterative procedure that refines successive estimates of the solution Iteration continues until the corrections are small enough to satisfy convergence criteria or until it is clear that the procedure is not going to converge The non linear iteration procedure starts from an initial guess The corrections are calculated by solving linearized versions of the problem The linear subproblems are solved by using direct techniques or iteratively Different solution procedures exhibit different behavior with respect to convergence accuracy efficiency and robustness The two main aspects of convergence are whether a solution is obtained and if so how rapidly it is approached Accuracy is how closely the computed solution approximates the true solution Efficiency is the time required to produce a solution Robustness is the ability to converge for a wide range of structures using meshes and init
272. n fraction by linear interpolations from these binary compounds SILVACO International B 13 ATLAS User s Manual Volume 2 Silicon Carbide SiC SiC Impact lonisation Parameters The default values for the 51 ELB impact ionization coefficients used for SiC are given in Table B 17 Table B 17 Impact lonization Coefficients for SiC Parameter Value EGRAN 0 0 BETAN 1 0 BETAP 15 0 AN1 1 66 106 AN2 1 66x10 BN1 1 273x10 BN2 1 293300 1 5 18 106 AP2 5 18x10 1 1 4x107 BP2 1 4 10 SiC Thermal Parameters The default thermal parameters used for both 6H and 4H SiC are shown in Table B 18 Table B 18 Default Thermal Parameters for SiC Parameter Value 4H SiC 6H SiC TCA 0 204 0 385 HCA 0 0 B 14 SILVACO International Material Systems Miscellaneous Semiconductors The remainder of the semiconductors available have defined default parameter values to various degrees of completeness The following sections describe those parameter defaults as they exist Since many of the material parameters are not available at this time it is recommended that care be taken in using these materials It is important to make sure that the proper values are used Note The syntax MOD Miscellaneous Semiconductor Band Parameters EL PRINT can be used to echo the parameters used to the run time output
273. n this occurs an error message will be issued warning of the existence of triangles that are not associated with any region Note ELIMINATI E statement only works on meshes defined using ATLAS syntax Elimination of mesh points on arbitrary meshes is possible in DEVEDIT SILVACO Inter national 15 33 ATLAS User s Manual Volume 2 EXTRACT Statement EXTRACT EXTRACT statements are used to measure parameters from both LOG and Solution files Note These commands are executed by DECKBUILD This statement is documented in the VWF INTERACTIVE TooLs MANUAL VOLUME ONE Terminal Current Extraction Example By default EXTRACT works on the currently open LOG file For example to extract peak drain current from a run immediately after solution LOG OUTF myfile log SOLVE EXTRACT NAME peak Id max i drain Extraction Example from Previously Generated Results To extract the same data from a previously run simulation the INIT parameter is required EXTRACT INIT INFILE myfile log EXTRACT NAME peak Id max i drain Solution Quantities Extraction Example To use EXTRACT with solution files it is always required to use the INIT parameter To find the integrateed number of electrons in a 1D slice at X 1 0 use SAVE OUTF mysolve str or SOLVE MASTER OUTF mysolve str EXTRACT INIT INFILE mysolve str
274. nate system of the optical beam see Figure 15 1 The illumination window is always clipped to the device domain Synonym XMAX METAL REFLECT sepcifies that all metals are to be treated as perfect reflectors LUMINOUS3D only MIN WINDOW specifies the minimum x value of the illumination window relative to the coordinate system of the optical beam Synonym XMIN 15 6 SILVACO International BEAM Statement Statements NUMBER specifies the beam number from 1 to 10 This number is used by the SOLVE statement to specify the relative intensity of different beams You may specify beam numbers in any order that you desire NX specifies the number of rays traced along the source beam s x axis for LUMINOUS3D see fig11 3 NZ specifies the number of rays traced along the source beam s z axis for LUMINOUS3D see fig11 3 PERIODIC specifies that for ray tracing the structure is to be treated as periodic in the x and z directions Rays exiting the sides of the device are wrapped around to the other side of the device LUMINOUS3D only POLARIZE specifies the polarization of the optical beam at the origin The polarization angle is the angle between the E vector and the device plane POWER SCALE specifies a scale factor This factor is multiplied by each of the relative powers in the spectrum file when multi spectral simulations are performed The POWER SCALE parameter can be used to perform unit conversions POWER FILE specifies t
275. nd DELTA CD Z parameters are used to define a offset to the size of any metal feature on that layer in the indicated direction The units are microns Negative values will increase the metal width with the X or Z direction positive values will decrease it Similarly the parameters MISALIGN X and MISALIGN Z are used to misalign layers relative to the positions in the Maskviews section file Separate misalignments in X and Z can be specified to model the worst case alignment of multi layer interconnects The default values are 0 0 Numerical Methods No special numerical methods are required for either conductance or capacitance simulations No METHOD statement is required Obtaining Solutions A solution is obtained for both capacitance and conductance modes with the simple statement SOLVE OUTF lt filename gt Only one SOLVE statement is allowed in each run of INTERCONNECT3D Interpreting the Results The output of INTERCONNECT3D simulation consist of a SPICE sub circuit netlist of the capacitance or conductance of the structure For capacitance calculations this is the capacitance between each pair of conductors in Farads For conductance calculations it is the resistance between each pair of electrodes in ohms The three dimensional structure and potential distribution can be saved in an output structure file by setting the OUTFILE parameter in statement This structure can be plotted using Tony PLOT3D
276. nergy balance simulations 23 Loading and Saving Optical Sources LOAD and SAVE statements act to save and restore optical sources BLAZE Version 2 0 0 R 24 Improved DevE dit Composition Fixed bug that caused DEVE DIT composition fraction information to be lost when the DevEDIT structure is loaded in MESH statement followed by any ELECTRODE statement 25 Composition Fraction Modification Fixed bug to allow composition fraction modification on loaded structures 26 Thermionic E mission Added capability to specify thermionic emission for heterojunctions in loaded structures GIGA Version 2 0 0 R 27 Quasi Fermi Level Fixed bug that caused improper display of the hole quasi fermi level in GIGA generated structure files 28 Outer Block Iteration Fixed bug in GIGA that caused premature exit from the outer block iteration when the maximum temperature update exceeded the starting temperature during the initial solution 29 Material Thermal Parameters The ability to specify the GIGA thermal parameters dependently for different materials regions was added in this version 30 Improved Thermal Dependencies The temperature dependencies of many models were improved LASER Version 2 0 0 R Initial Release of LASER Under The ATLAS Framework 31 This version supports simulation of various types of F abry Perot semiconductor diode lasers BLAZE Version 2 0 0 R 32 Now supports running MIXEDMODE decks under DECKBUILD 33 Implemente
277. ng Mechanism in InP Buried Heterostructure Lasers J Appl Phys 71 7 April 1992 pp 3572 3578 G Baccarani M Rudan R Guerrieri and P Ciampolini Physical Models for Numerical Device Simulation European School of Device Modeling University of Bologna 1991 J W Slotboom and H C De Graaf Measurements of Bandgap Narrowing in Silicon Bipolar Transistors Solid State Electronics Vol 19 pp 857 862 1976 Fossum and D S Lee A Physical Model for the Dependence of Carrier Lifetime on Doping Density in Nondegenerate Silicon Solid State Electronics Vol 25 pp 741 747 1982 J Dziewior W Schmid Auger Coefficient for Highly Doped and Highly Excited Silicon Appl Phys Lett Vol 31 pp 346 348 1977 W L Engl and H K Dirks Models of Physical Parameters in an Introduction to the Numerical Analysis of Semiconductor Devices and Integrated Circuits J J H Miller Ed Dublin Boole Press 1981 K K Thornber Relation of Drift Velocity to Low Field Mobility and High Field Saturation Velocity J Appl Phys Vol 51 pp 2127 2136 1980 K Yamaguchi A Mobility Model for Carriers in the MOS Inversion Layer IEEE Trans Elect Devices Vol E D 30 pp 658 663 1983 G A M Hurkx H C de Graaf W J Klosterman et al A Novel Compact Model Description of Reverse Biased Diode Characteristics including Tunneling ESSDERC pp 49 52 1990 D B M Klaasen Physical Modeli
278. ng for Bipolar Device Simulation Simulation of Semiconductor Devices and Processes Edited by W Fichter and D Aemmer Zurich Harting Gorre 1991 Vol 4 pp 23 43 G A M Hurkx D B M Klaasen M P G Knuvers and F G O Hara A New Recombination Model Describing H eavy Doping Effects and Low Temperature Behaviour IEDM Technical Digest pp 307 310 1989 A l Adamsone and B S Polsky 3D Numerical Simulation of Transient Processes Semiconductor Devices COMPEL The International Journal for Computation and Mathematics in Electrical and Electronic Engineering Vol 10 No 3 pp 129 139 Lombardi et al A Physically Based Mobility Model for Numerical Simulation of Non Planar Devices IEEE Trans on CAD Nov 1988 p 1164 B Meinerzhagen K Bach Bozk and W L Eugl A New Highly Efficient Nonlinear SILVACO International BIB 5 ATLAS User s Manual 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 Relaxation Scheme for Hydrodynamic M OS Simulations Proe NUPAD IV p 91 1992 RJ Gossens S Beebe Z Yu and R W Dutton An Automatic Biasing Scheme for Tracing Arbitrarily Shaped I V curves IEEE Trans Computer Aided Design vol 13 No 3 pp 310 317 Shirahata M Kusano H Kotani N Kusanoki S and Akasaka Y A Mobility Model Including the Screening Effect in MOS Inversion Layer IE
279. ng profile from analytical functions GAUSSIAN specifies the use of a gaussian analytical function to generate the doping profile If GAUSSIAN is specified the following parameters must also be specified Polarity parameters N TYPE or P TYPE One of the following groups of profile specifications Group 1 CONCENTRATION and JUNCTION Group 2 DOSE and CHARACTERISTIC Group 3 CONCENTRATION and CHARACTERISTIC UNIFORM specifies the use of uniform constant analytical functions to generate the doping profile If Uniform is specified the N TYPE P TYPE and CONCENTRATION parameters must be specified Doping is introduced into a box defined by the boundary parameters see page 15 25 The box by default includes the entire region F DOPING specifies the name of a file containing a C INTERPRETER function specifying the spatial distribution of dopants F3 DOPING specifies the name of a file containing a C INTERPRETER function specifying the spatial distribution of dopants for a 3D device SILVACO International 15 23 ATLAS User s Manual Volume 2 DOPING Statement File Import Profile Types These parameters specify how ATLAS will generate a doping profile from a file Files can be user defined or from process simulation INFILE specifies the name of the appropriate input file ASCII has two separate meanings e when combined with other format parameters is specifies the filetype is ASCII
280. ng the TFT product Units SILVACO International 15 17 ATLAS User s Manual Volume 2 DEFECT Statement Parameter Type Default Units WGD Real Qd WTA Real 0 025 WTD Real 0 05 ev Description The DEFECTS statement is used to describe the density of defect states in the band gap Up to four distributions can be specified two for donor like states and two for acceptor like states Each type of state may contain one exponential tail distribution and one Gaussian distribution AFILE specifies the file name in which the acceptor state density distribution as a function of energy will be stored This file can be examined using TONYPLOT CONTINUOUS specifies that the continuous defect integral model will be used DEVICE specifies which device the statement applies in mixed mode simulation DFILE specifies the file name in which the donor state density distribution as a function of energy will be stored This file can be examined using TONYPLOT EGA specifies the energy that corresponds to the Gaussian distribution peak for acceptor like states This energy is measured from the conduction band edge EGD specifies the energy that corresponds to the Gaussian distribution peak for donor like states This energy is measured from the valence band edge specifies the name of a file containing a C NTERPRETER function describing the distribution of acceptor state
281. nsform Thefollowing parameters are optional e T START start of time data to be used for the FFT The default value is the first time point in theinput log file SILVACO International 14 19 ATLAS User s Manual Volume 2 T STOP end of time data to be used for the FFT The default value is the last time point in the input log file FUNDAMENTAL fundamental frequency If this is not specified then the fundamental frequency is set to 1 T STOP T START If the fundamental frequency is specified then T STOP is set to T START 1 FUNDAMENTAL MAX HARMONIC maximum harmonic frequency that the FFT should calculate This will automatically calculate the correct number of samples NUM SAMPLES required to generate this frequency FUNDAMENTAL must be specified when MAX HARMONIC is used e NUM SAMPLES number of samples This should be an integer power of 2 i e 270 where is a positive integer The default value is 64 unless the MAX HARMONIC parameter is specified In this case the number of samples is set to the nearest integer power of 2 which will generate this frequency INTERPOLATE performs linear interpolation on input data with non uniform timesteps This interpolates the data on to uniform timesteps Interpolation of data can introduce addition inaccurate harmonic values into the FFT which would not occur if uniform time is taken INTERPOLATE must be used if the log file contains non uniform ti
282. nverse of the size of the angle of triangles intersecting at the node AREA specifies that averaging of current and fields will be weighted by the areas of triangles intersecting at the node INV AREA specifies that averaging of current and fields will be weighted by the inverse of areas of triangles intersecting at the node Note Certain quantities that can be output into the structure file and subsequently displayed using TONYPLOT need special mention These quantities are evaluated within ATLAS along the links between grid points They are represented in the structure file at the grid points themselves As such these quantities are subject to averaging In particular electric field and currents are averaged so as to take into account the vector nature of these values Mobility is simply summed up over all the links surrounding the grid point and divided by the total number of links Carrier velocities are derived by dividing the averaged current by the carrier density at the grid point and the fundamental electron charge q Example of combining OUTPUT with SOLVE and SAVE The OUTPUT statement is often used in conjuction with the SAVE statement The following statement lines specify that current flowlines and electron velocity components are saved in all subsequent standard structure solution files OUTPUT FLOWLINES EX VELO EY VELO SOLVE PREVIOUS V5 2 OUTF datal str MASTER SAVE OUTF data2 str 1
283. o atlas simflags V 4 3 2 C P 4 SILVACO International 15 37 ATLAS User s Manual Volume 2 IMPACT Statement IMPACT IMPACT specifies and set parameters for impact ionization models Syntax IMPACT lt model gt Parameter Type Default Units A NT Real 0 588 A PT Real 0 588 AN1 Real 7 03x10 AN2 Real 7 03x10 cm AP1 Real 6 71x10 2 Real 1 682x10 cm B NT Real 0 248 B PT Real 0 248 BETAN Real 1 0 BETAP Real 1 0 BN1 Real 1 231 106 V cm BN2 Real 1 231 10 V cm BP1 Real 1 231 106 V cm BP2 Real 2 036x10 V cm CO Real 2 5x10 10 CHIA Real 3 0x10 CHIB Real 5 0 104 CHI HOLES Real 4 6 104 CROWELL Logical False CSUB N Real 2 0 1014 CSUB P Real 4 0 1012 DEVICE Character EGRAN Real 4 0x10 V cm ENERGY Real 0 0025 Real 1 8 15 38 SILVACO International IMPACT Statement Statements Parameter Type Default Units ETH P Real Su F EDIIN Character F EDIIP Character ICRIT Real 4 0 107 A cm INFINITY Real 0 001 LAMDAE Real 6 2 1077 cm LAMDAH Real 3 8 107 cm LENGTH REL Logical False LREL EL Real 3 35 1072 LREL HO Real 2 68 1072 Real 1 20 Real 1 0 BNT Real 1 0 BPT Real 1 0 ATERIAL Character NAME Character REGION Integer SELB Logical False TAUSN Real 0 4x10 1 S TAUSP Real 0 4 10712 5 Description The impact ionization mo
284. od initially switching tothe fully coupled newton method as the simulation proceeds Of course the cross over point which is at x 2 5 in Figure C 4 varies from case to case To avoid excessive user interaction the block newton could be used throughout the simulation without a very excessive hit in terms of CPU time File View Tools Print Properties Help 8 TonyPlot V2 4 1 ATLAS Comparison of CPU Time During A Voltage Ramp el METHOD BLOCK METHOD BLOCK NEWTON METHOD NEWTON LOG CPU time s 1 1 6 3 4 BIAS ARBITRARY SCALE Printing complete SILVACO International 1995 4 Figure C 4 Comparison of CPU time showing advantages of decoupled methods at low current and coupled method at high currents C4 SILVACO International Hints and Tips Question Can the workfunction of the MOS polysilicon gate contact be calculated by ATLAS based on the doping Can poly depletion effects be simulated in ATLAS Answer The polysilicon gate contact in MOS devices can be simulated in two distinct ways using ATLAS These correspond to treating the polysilicon region as metal like equipotential region with a specified workfunction A semiconductor region with a potential defined by the doping level Most commonly the former approach is adopted The polysilicon region acting as the gat
285. of CLIMIT parameter but in comparison with CLIMIT it specifies dimensional value of minimal concentration which can be resolve using ATLAS By default CLIM DD is not specified and ATLAS uses default value of CLIMIT as in previous versions Parameter CLIM EB can be treated as regularization parameter for the case of very small electron hole concentration for energy balance model It specifies the mimimal value of concentration for which relaxation term in energy balance equation will be still properly resolved otherwise D 8 SILVACO International ATLAS Version History temperature for the points where concentration is much less than CLIM EB will tend to lattice temperature 12 New syntax With this release the ATLAS syntax was augmented to simplify and somewhat rationalize some of the more confusing problems e TheSYMBOLIC statement is no longer needed e numerical method can now be specified on the MODEL statement The user may choose from Gummel Block and Newton methods More than one method can be chosen and ATLAS provides automatic switching between the methods e ATLAS now supports a new syntax for specifying which equations are simulated The syntax is now supported on either the MODEL or METHOD statement and is the preferred syntax for future compatibility The new syntax provides a more rational intuitive way of choosing which equations are solved e ATLAS still supports syntax from previous versions 13 Imp
286. of temperature composition and doping dependent hole mobility model F MUNSAT specifies the name of a file containing a C INTERPRETER function for the specification of parallel field dependent electron mobility model for velocity saturation F MUPSAT specifies the name of a file containing a C INTERPRETER function for the specification of parallel field dependent hole mobility model for velocity saturation F VSATN specifies the name of a file containing a C INTERPRETER function for the specification of temperature and composition dependent electron saturation velocity models F VSATP specifies the name of a file containing a C NTERPRETER function for the specification of temperature and composition dependent electron saturation velocity models Example Selecting the Modifed Watt Model The following example set the Modified Watt Surface mobility model for MOSFETs This is the best model for planar MOS simulation The MOBILITY statement is used to set the models and to specify the value of the depth of action of the Modified Watt model MODELS CONMOB FLDMOB SRH MIN SURF PRINT MOBILITY WATT N MOD WATT N YMAXN WATT 0 01 SILVACO International 15 91 ATLAS User s Manual Volume 2 MODELS Statement MODELS MODELS specifies model flags to indicate the inclusion of various physical mechanisms and models Various other parameters such as the global temperature for the simulation Syntax MODELS lt mf gt
287. of these defaults can be overriden using the MATERIAL IMPACT MODEL and MOBILITY statements The key to defining new materials is choosing a material name that is defined in ATLAS then modifying the material parameters of that material to match the user material Here it is best to choose a material that has default parameter values that might best match the user material while being sure to choose a material that is not already in the user device Next the user must associate this material name with the device regions where the new material is present This is done by either specifying the chosen material name on the appropriate REGION statements when the device is defined in the ATLAS syntax or choosing the material name from the materials menu when defining the region in DEVEDIT Next the user should modify the material statements using MATERIAL IMPACT MOBILITY and MODEL statements When doing this the MATERIAL parameter of the given statement should be assigned to the chosen material name For materials with variations in composition fraction the user should choose a defined material with X and or Y composition fractions i e a terniary or quaterniary material The user may also find it convenient to use C interpreter functions to define the material parameters as a function of composition The C interpreter functions that are useful for this approach are F MUNSAT F MUPSAT F BANDCOMP F VSATN F VSATP F RECOMB F IND
288. om the LOAD statement Note The LOAD statement loads only the saved solution quantities into ATLAS The mesh electrodes doping regions contact settings material parameters models and numerical methods must all be specified in advance of any LOAD statement See the Re Initializing ATLAS section of the Getting Started Chapter SILVACO International 15 47 ATLAS User s Manual Volume 2 LOG Statement LOG LOG allows all terminal characteristics of a run to be Isaved to a file Any DC transient or AC data generated by SOLVE statements after the LOG statement is saved Any parameters specified by the PROBE statement are also stored in the logfile If a log file is already open the open log file is closed and a new log file is opened Syntax LOG OUTFILE lt filename gt MASTER acparams Parameter Type Default Units ABCD PARAM 1 False APPEND iogical False GAINS ogical False H PARAM ogical False IMPEDANCE Real 50 ohms INPORT Character IN2PORT Character J ELECTRON ogical False J HOLE iogical False LCOMMON Real 0 H LGROUND Real 0 H LIN Real 0 H LOUT Real 0 H MASTER iogical True OFF iogical False OLD iogical False OUTPORT Character OUT2PORT Character OUTFILE Character RCOMMON Real 0 ohms RGROUND Real 0 ohms RIN Real 0 ohms ROUT Real 0 ohms S PARAM iogical False SIM TIME iogical False 5
289. on in a series of bias points In this case an intial solution is obtained for equilibrium conditions There is no need to solve the current continuity equations at equilibrium and a solution of Poisson s equation is quickly obtained It is also possible to modify the initial guess in a way that makes some allowance for the new bias conditions Typical strategies include Using two previous solutions and interpolation to project a new solution at each mesh point Solving a form of current continuity equation with carrier concentrations held constant This strategy yields an improved estimate of new potential distribution Modifying the majority carrier quasi F ermi levels by the same amount as the bias changes SILVACO International 14 15 ATLAS User s Manual Volume 2 Parameters on the SOLVE statement can be used to specify an initial guess strategy Five initial guess strategies are available INITIAL starts from space charge neutrality throughout the device This choice is normally used to calculate a solution with zero applied bias PREVIOUS uses the currently loaded solution as the initial guess at the next bias point The solution is modified by setting a different applied bias at the contacts PROJECTION takes two previous solutions whose bias conditions differ at one contact and extrapolates a solution for a new applied bias at that contact This method is often used when performing a voltage ramp LOCAL sets t
290. onductor Devices Solid State Electronics Vol 29 pp 321 328 1986 R Stratton Phys Rev 126 6 p 2002 1962 Blotekjaer IEEE Trans ED 17 p 38 1970 B Meinerzhagen and W L Engl The Influence of Thermal Equilibrium Approximation on the Accuracy of Classical Two Dimensional Numerical Modeling of Silicon Submicrometer MOS Transistors IEEE Trans ED 35 No 5 pp 689 697 1988 K Katayama and T Toyabe A New Hot Carrier Simulation Method Based on Full 3D Hydrodynamic Equations IEDM 89 Technical Digest 135 1989 G Liu and S Fonash Low Thermal Budget Poly Si Transistors on Glass J J AP Vol 30 p 269 1991 K Fujii Y Tanaka K Honda H Tsutsu H Koseki and S Hotta Process Techniques of 15 inch Full Color and High Resolution a Si TFT LCD 5th Int MicroProcess Conf Kawasaki J apan 1992 F Hayashi and M Kitakata A High Performance Polysilicon TFT Using RTA and Plasma Hydrogenation Applicable to Highly Stable SRAM s of 16 Mbit and Beyond Digest of VLSI Technology Symposium p 36 1992 N Lifshitz S Fang and A Kornblit Novel Thin Film Transistor for SRAM Applications Proceedings International Semiconductor Device Research Symposium Charlottesville VA p 529 1991 R Ditizio S Fonash and B C Hshieh Examination of The Optimization of TFT Passivation with Hydrogen ECR Plasma J Vacuum Science and Technology Vol 10 p 59 1992 M Hack H Tua
291. one Gummel s method with energy balance equations is terminated if 14 16 is fulfilled the carrier temperature convergence criteria X r S TC 14 17 is achieved and one of the following conditions is valid NITGUMM lt 1 lt NITGUMM NT1 and 14 13 is fulfilled b NITGUMM lt 1 lt NITGUMM NT3 and x CSF 14 18 where w 10 C NITGUMM lt K 1 lt NITGUMM the current convergence criteria 14 4 14 5 are satisfied and inequality 14 18 is valid for w 100 d NT1 NITGUMM lt 14 18 is valid for w 100 NT1 NITGUMM lt K 1 the current convergence criteria 14 4 and 14 5 are satisfied and 14 18 is valid for w 500 The default values of the iteration parameters are NITGUMM 5 NTO 4 NT1 10 NT3 100 SILVACO International 14 11 ATLAS User s Manual Volume 2 Convergence Criteria For Newton s Algorithm Relative update errors are defined as follows For potential K 1 K E 14 19 For electron concentration K 1 max lr E 14 20 max Co nm For hole concentration K 1 K p 14 21 K max Co Pm For lattice temeprature and carrier temperature max K 1 K a A 14 22 scale max K 1 K i UE ecole 14 23 scale max K 1 K m Erp a 14 24 scale where the scaling temperature Tscale is by defaul
292. ons and return values are fixed in ATLAS Thus care should betaken to ensure that the arguments and the return values for the functions match those expected by ATLAS To help the user this release of ATLAS includes a set of templates for the available functions The C iNTERPRETER function template can be obtained by typing atlas T filename where filename is the name of a file where you want the template to be copied The C INTERPRETER function template can also be obtained by accessing the template file through DEckBuiLD This template file should be copied and edited when implementing user defined C INTERPRETER functions n order to use the C INTERPRETER function the file name containing this function must specified in the appropriate ATLAS statement The relevant statement names and parameters are listed in the template file The following example shows how the C INTERPRETER function munsat be used to describe velocity saturation for electrons First examine the template file and find the template for munsat The template should look something like this Electron velocity saturation model Statement MATERIAL Parameter F MUNSAT xf electric field V cm saturation velocity cm s low field mobility cm 2 Vs mu return field dependent mobility cm 2 Vs dmde return derivative of mu with e int munsat double e double v double mu0 double mu
293. ontrol parameters are used to specify what type of information will be converted to an UTMOST logfile AC specifies that input logfiles contain AC parameters and that the UTMOST routine numbers refer to the UTMOST capacitance routines DEVICE specifies the device or row number used to identify different devices in UTMOST Synonym ROW INTERNAL specifies that internal contact voltage will be used instead of applied bias LENGTH specifies the length of the device MINSTEP specifies the minimum voltage step between data points TEMPERATURE specifies the simulation temperature ROUTINE specifies which UTMOST routine number data will be saved for The following routines are supported BIP Technology ROUTINE 1 specifies vs Vcg curves Each input file holds I V data for a solution with a fixed base current and Veg stepped UTMOST IC VCE routine ROUTINE 9 specifies a vs plot Each input file holds I V data for a solution with constants Vcg and stepped UTMOST BFvsIC routine ROUTINE 10 specifies vs Vgc plot Each input file holds I V data for a solution with constants Vcg and stepped UTMOST BR routine ROUTINE 14 specifies vs Vgg Gummel plot Each input file holds I V data for a solution with constant Vcg and Vgg stepped UTMOST gummel routine ROUTINE 15 specifies a Ig Ig vs Vgc Reverse Gummel plot Each input file holds I V data for a solution with constants Vgc and Vgc stepped UTMOS
294. or holes in a tail distribution of acceptor like states SIGTDE specifies the capture cross section for electrons in a tail distribution of donor like states SIGTDH specifies the capture cross section for holes in a tail distribution of donor like states WGA specifies the characteristic decay energy for a Gaussian distribution of acceptor like states 15 18 SILVACO International DEFECT Statement Statements WGD specifies the characteristic decay energy for a Gaussian distribution of donor like states WTA specifies the characteristic decay energy for the tail distribution of acceptor like states WTD specifies the characteristic decay energy for the tail distribution of donor like states TFT Example The following statement lines specify distributed defect states which would typically be used for polysilicon DEFECTS 1 21 NTD 1 E21 WTA 0 033 WTD 20 049 1 5 15 NGD 1 5E15 0 62 EGD 0 78 WGA 0 15 WGD 0 15 SIGTAE 1 E 17 SIGTAH 1 E 15 SIGTDE 1 E 15 SIGTDH 1 E 17 SIGGAE 2 E 16 SIGGAH 2 E 15 SIGGDE 2 E 15 SIGGDH 2 E 16 SILVACO International 15 19 ATLAS User s Manual Volume 2 DEGRADATION Statement DEGRADATION DEGRADATION specifies parameters for MOS device degradation modeling Syntax DEGRADATION lt params gt Parameter Type Default Units F NTA Char F NTD Char F NTD Char
295. or transient simulations DVMAX sets the maximum allowed potential update per Newton iteration Large voltage steps are often required when simulating high voltage devices If any simulation requires voltage steps of 10V or more set DVMAX to 100 000 Reducing DVMAX may serve to damp oscillations in solutions in some cases leading to more robust behavior However excessive reduction in DVMAX is not recommended since the maximum voltage step allowed will be limited by DVMAX ITLIMIT EXTRAPOLATE specifies the use of second order extrapolation to compute initial estimates for successive time steps for transient simulations L2NORM specifies the use of L2 error norms rather than infinity norms when calculating time steps for transient simulations NRCRITER specifies the ratio by which the norm from the previous Newton loop must decrease in order to be able to use the same Jacobian LU decomposition for the current Newton loop TAUTO selects automatic adaptive timesteps for transient simulations from local truncation error estimates Automatic time stepping is the default for second order discretization but is not allowed for first order TSTEP INCR specifies the maximum allowable ratio between the time step sizes of successive increasing time steps during transient simulation QUASI specifies a quasistatic approximation for transient simulations This is useful in simulating transient simulations with long timescales where the device is in equ
296. ous programs into ATLAS Note Please see the Getting Started Chapter or the on line examples for details of the interfaces from ATHENA or DEVEDIT to ATLAS 15 68 SILVACO International METHOD Statement Statements METHOD algorithms Syntax Parameter 2NDORDER ATRAP AUTONR BIGGEST BLOCK CARRIERS C ITLIMIT C STABIL C RESID CLIM DD CLI CR TOL CUR PROJ CX TOLER DIRECT DT MAX DT MIN DVLIMIT DVMAX ELECTRONS EXTRAPOLATI Gl FIX OF GMRES GUM INIT METHOD lt gp gt lt mdp gt Type Logical Real jogica Real Integer Real Real Real Real Real Real Logical Real Logical Real Real Real Real ogica l ogical ogical jogica Integer Default Units True 0 5 False False True 500 1 0x10 19 1 0x10 9 4 5x101 cm 10000 5 0x10 18 False 1 0 1075 False True False False False 15 METHOD sets the numerical methods to be used to solve the equations and parameters associated with the these SILVACO International 15 69 ATLAS User s Manual Volume 2 METHOD Statement Parameter Type GUMITS Integer GUMMEL iog
297. ously for the carrier temperature case and then performs one decoupled solution for lattice temperature as a third step of each iteration Combining The Iteration Methods It is possible to start with the GUMMEL scheme and then switch to BLOCK or NEWTON if convergence is not achieved within a certain number of iterations One circumstance where this can be very helpful is that Gummel iteration can refine initial guess to a point from which Newton iteration can converge The number of initial GUMMEL iterations is limited by INIT It can also be desirable to use BLOCK iteration and then switch to NEWTON if convergence is not achieved This is the recommended strategy for calculations that include lattice heating or energy balance The number of initial BLOCK iterations is limited by NBLOCKIT Any combination of the parameters GUMMEL BLOCK and NEWTON may be specified on the METHOD statement ATLAS will start with GUMMEL if it is specified If convergence is not achieved within the specified number of iterations it will then switch to BLOCK if BLOCK is specified if convergence is still not achieved the program will then switch to NEWTON Solving Linear Subproblems Thelinear subproblems generated by non linear iteration can be solved by direct or iterative methods Direct methods produce solutions in a predictable number of arithmetic operations Solutions are affected by roundoff error but are otherwise exact Ite
298. owing criteria is fulfilled 1 parameter xNORM is true and Equations 14 32 14 33 and 14 34 are valid for w 2 parameter RHSNORM is true and Equations 14 38 14 39 and 14 40 are valid for 1 3 both XNORM and RHSNORM are true and for the pairs of inequalities Equations 14 32 and 14 38 Equations 14 33 and 14 39 Equations 4 34 and 14 40 one of the conditions is satisfied for each pair 4 thecurrent convergence criteria are satisfied and condition 1 condition 2 or condition 3 is fulfilled for w 2w4 WEAK Initial Guess Strategies Non linear iteration starts from an initial guess The quality of the initial guess i e how close it is to the final solution affects how quickly the solution is obtained and whether convergence is achieved Users of ATLAS are not required to specify an initial guess strategy If no strategy is defined ATLAS follows certain rules that implement a sensible although not necessarily optimum strategy There is some interaction between the choice of non linear iteration scheme and the initial guess strategy Decoupled iteration usually converges linearly although perhaps slowly even from a relatively poor initial guess Newton iteration converges much faster for a good initial guess but fails to converge if started from a poor initial guess One very simple initial guess strategy is to use the most recent solution as the initial guess Of course there is no previous solution for the first calculati
299. pant is not specified the total donors and acceptor concentrations are loaded 1 specifies that the doping file is ATHENA 10 export file This parameter acts in a similar way to the 55 parameter ATHENA reads 2D doping information from ATHENA standard structure SSF or PISCES II format files The PISCES II format is an obsolete file format Doping information obtained from this file will be added to each point of the current ATLAS mesh If points in the ATLAS mesh do not coincide with points in the ATHENA mesh doping for ATLAS mesh points will be interpolated from ATHENA doping information If this profile type is used the INFILE parameter must also be specified Note The X STRETCH function available in previous versions of ATLAS has been replaced by similar more powerful functions in DEVEDIT This feature should no longer be used in ATLAS Parameters that Specify the Dopant Type These parameters give information about the dopant species or type to be used inthe specified profile Different profile types require different profile specifications ACTIVE specifes that for the dopant specified the active concentration as opposed to the chemical concentration is added This is true by default Files from ATHENA or SSUPREM 3 contain both active and chemical concentrations for each dopant ANTIMONY specifies that antimony dopant information be extracted from an imported file ARSENIC specifies that ar
300. ped ELECTRODE should be an n digit integer where each of the digits is a separate electrode number See also NAME I lt name gt specifies the applied current for a named electrode One of several commonly used terminal names should be specified These names are as follows gate gg drain dd source bulk substrate emitter ee collector cc base bb anode cathode fgate cgate ngate pgate well nwell pwell channel and ground No other user defined names are allowed This parameter is used when current boundary conditions are selected see the CONTACT statement I lt n gt specifies the terminal current for electrode n This parameter is used when current boundary conditions are selected see the CONTACT statement Normally I defaults to the current from the previous bias point It is more usual to use electrode names rather than numbers This parameter is superceded by I lt name gt IFINAL specifies the final current value for a set of bias increments If IFINAL is specified either ISTEP or NSTEPS must be specified IMULT specifies that the current for current boundary conditions be multiplied by ISTEP rather than incremented ISTEP specifies a current increment to be added to one or more electrodes as specified by the electrode name applied to the NAME parameter If ISTEP is specified either IFINAL or NSTEPS must also be specified N BIAS specifies fixed electron quasi Fermi potentials if
301. pwell channel and ground NUMBER specifies an electrode number from 1 to 50 Electrode numbers may be specified in any order If NUMBER is not specified electrodes will be automatically numbered in sequential order This parameter cannot renumber electrodes already defined in ATLAS or other programs SUBSTRATE places the specified electrode at the bottom of the device and names the electrode substrate pos is one of the position parameters described below reg is a set of the region parameters described on the next page Position Parameters BOTTOM or SUBSTRATE specifies that the electrode is positioned along the bottom of the device LEFT specifies that the electrode starts at the left hand edge of the device The electrode will be positioned from left to right along the top of the device RIGHT specifies that the electrode starts at the right hand edge of the device The electrode will be positioned from right to left along the top of the device TOP specifies that the electrode is positioned along the top of the device Region Parameters Device coordinates may be used to add regions to both rectangular and irregular meshes In either case boundaries must be specified with the X MAX X MIN Y MAX and Y MIN parameters LENGTH specifies the length of the electrode in the x direction It is not necessary to specify X MIN X MAX and LENGTH If two of these parameters are specified the value of the third parameter willbe calculate
302. r the solution is projected to the next operating point by stepping the external voltage Once the solution has converged a new external resistance is calculated based on the new tangent information and the process repeats itself 14 16 SILVACO International Numerical Techniques tangent Vint Vapp V Figure 14 1 Load the algorithm used in the Curve Tracer The curve tracing capability is activated by specifying the CURVETRACE parameter in the SOLVE statement Prior to this the CURVETRACE statement is used to set the parameters for the tracing algorithm These parameters are the name CONTR NAME of the ramped electrode which will be referred to as a control electrode the initial voltage increment STEP INIT the upper bound of the tracing curve and additional parameters if they differ from the default values The Upper bound parameter END VAL is used to stop tracing If the voLT CONT parameter is specified END VAL isa voltage If the CURR CONT parameter is specified END VAL is a current The applied voltage at each step is altered in accordance with the slope of the 1 curve The resistor between the applied voltage and the semiconductor is also changed dynamically to ensure the voltage at the semiconductor VINT is smoothly varied along the I V curve If STEP CONT is specified the number of operational points on a trace will not exceed specified parameter STEPS Transient
303. r a Gaussian profile JUNCTION specifies the location of a p n junction within the silicon region of a Gaussian profile When JUNCTION is specified the characteristic length is computed by examining the doping at a point halfway between the end of the constant box and the given depth The JUNCTION location is evaluated considering all previous DOP ING statements only This means that in some cases the order of DOPING statements is important PEAK specifies the depth location of the peak doping in a Gaussian profile Location Parameters DIRECTION specifies the axis along which a one dimensional profile is directed in a two dimensional device x or y DIR y will typically be used for implanted profiles REGION specifies the region number where doping is to be added SILVACO International 15 25 ATLAS User s Manual Volume 2 DOPING Statement START specifies the depth in the y direction where the profile should start Lateral Extent Parameters These parameters must be specified when a 1 D doping profile type is used MASTER GAUSSIAN or ASCII These boundary parameters set the doping boundaries before applying lateral spreading This is equivalent to setting implant mask edges X MIN X MAX Y MIN Y MAX Z MIN and Z MAX specify the x y and z bounds of a rectangular shaped region or box in the device The dopant profile within this box will be constant with a density equal to the value specified by the CONC parameter Out
304. r estimate for radiative recombination If a positive value of L WAVE is specified the luminous power will be saved in any log file specified for that solution LAMBDAIL specifies the wavelength of the optical source beam number 1 for this solution This parameter can be used to perform analysis of spectral response as a function of wavelength LIT STEP selects the light intensity increment of all optical beams which have been specified This parameter is used when light intensity varies by stepping similar to the VSTEP parameter If LIT STEP is specified the NSTEP parameter should be used to select the number of steps RAMPLLIT specifies that the light intensity is to be ramped when transient simulations are performed If RAMP LIT is specified transient mode parameters such as RAMPTIME TSTEP and TSTOP must also be specified The RAMP LIT parameter affects all specified optical beams i e all beams are ramped SCAN SPOT specifies a beam number for spot scanning Spot scanning requires that the user specify the RAYS parameter of the BEAM statement with this specification the incident light is split into the user specified number of rays During the spot scan solutions are obtained with the beam energy applied to each of the rays in sequence SILVACO International 15 135 ATLAS User s Manual Volume 2 SOLVE Statement SS LIGHT specifies the intensity in the small signal part of the optical beam when
305. r is 1 familiar with the basic terminology of semiconductor processing and semiconductor device operation and 2 understands basic operation of the computer hardware and operation system being employed Introduction ATLAS is a modular and extensible framework for one two and three dimensional semiconductor device simulation It is implemented using modern software engineering practices that promote reliability maintainability and extensibility Products that use the ATLAS Framework meet the device simulation needs of all semiconductor application areas SILVACO International makes no warranty of any kind with regard to this material including but not limited to the implied warranty of fitness for a particular purpose SILVACO International shall not be liable for errors contained herein or for incidental or consequential damages in connection with furnishing performance or use of this material This document contains proprietary information protected by copyright All rights are reserved No part of this document may be photocopied reproduced or translated into another language without the prior written consent of SILVACO International Editions are recorded below under History and are individually listed as Edition 1 through 6 The basic issue of the manual is Edition 1 The date is also noted A completely revised manual results in a new edition History e Edition 1 July 1 1993 e Edition 2 March 1 1994 e Edition 3 June
306. rap Level Definition Example 15 149 UTMOST uta eae O eee 15 150 Description sesin a 15 151 X MESH Y MESH 2 2525 hana IRE RR ADS RA Ga 15 154 Description heme Cae LA SICH EORR CERT 15 154 Example Setting Fine Grid at A 15 154 Appendix A C Interpreter FUNCHONS arat 1 eem 1 Appendix Material SySIems sess ta dee des Mix Rs Id B 1 OVERVIEW MEMOREM rr B 1 Semiconductors Insulators and Conductors B 1 Semiconductors ean add 8 1 T iat poat ris ed yis 8 1 erre EUST B 1 Unknown Materials aser cR rr uad d dp SEM B 2 s E eese eed ee any d E ERE bees B 3 Rules for Specifying Compound Semiconductors B 4 Sillcon and POlySiICOM 525052 aeea NET A E a a B 6 Silicon and Polysilicon Band Parameters
307. rative methods obtain solutions by making a series of corrections to an initial guess Iteration proceeds until the calculated corrections satisfy specified convergence criteria The results are not exact to within roundoff error and convergence is not guaranteed for general problems However iterative methods can be more efficient than direct methods for large linear systems and generally require less memory SILVACO International 14 5 ATLAS User s Manual Volume 2 There are mathematical proofs regarding the types of linear system for which iterative techniques converge All common iterative schemes converge for linear systems that are symmetric positive definite SPD The linearized form of Poisson s equation is of this type The continuity equations are not SPD but they can be reliably solved by modern advanced iterative methods The size and structure of the coefficient matrix of the linear system plays an important role in the choice of direct or iterative methods The overall problem size is determined by the number of variables per node m and the number of nodes The number of unknowns is m x n The linear sub problems associated with Newton iteration have a coefficient matrix with m x n elements Each linearized subproblem which is used Gummel iteration has a coefficient matrix with n elements For practical 2 D device simulation problems the number of elements in the coefficient matrix is typically betwee
308. rdson coefficients for GaAs are 6 2875 A cm2 K2 for electrons and 105 2 A cm K for holes SILVACO International B 11 ATLAS User s Manual Volume 2 The Ing x GAAS yP y System InGaAsP Thermal Parameters The default material thermal models for InGaAsP assumes lattice matching to InP The material density is then given by 4 791 0 575y composition 0 138y composition The specific heat for InGaAsP is given by C 0 322 0 026y composition 0 008 y composition The thermal resistivities of InGaAsP are linearly interpolated from Table B 15 Table B 15 Thermal Resistivities for InGaAsP Lattice Matched to InP Composition Fraction y Thermal Resistivity deg cm w 0 0 1 47 0 1 7 05 0 2 11 84 0 3 15 83 0 4 19 02 0 5 21 40 0 6 22 96 D 23471 0 8 23 63 0 9 22T 1 0 20 95 The default thermal properties of the binary compounds in the InGaAsP system are given in Table B 16 Table B 16 Default Thermal Properties of InP InAs GaP and GaAs Material Thermal Capacity J cm3 Thermal Resistivity deg cm W InP 1 543 1 47 InAs 1 994 3 70 GaP 1 292 1 30 GaAs 1 7386 25201 12 SILVACO International Material Systems The default thermal properties for the terniary compounds in the InGaAsP system 1 1 5 1 GaAsiy P z y are given as a function of compositio
309. re and composi tion dependent band param eters DOPING F DOPING doping Position dependent net doping DOPING F3 DOPING doping3 Position dependent net doping DOPING 5 composition Position dependent compo sition fractions MATERIAL F EPSILON epsilon Composition and tempera ture dependent permittiv ity MATERIAL F FERRO ferro Position and field depen dent permittivity MATERIAL F VSATN vsatn Composition and tempera ture dependent electron saturation velocity MATERIAL F VSATP vsatp Composition and tempera ture dependent hole satu ration velocity MATERIAL F RECOMB recomb Position temperature and concentration dependent recombination MATERIAL F INDEX index Wavelength dependent com plex index of refraction BEA F REFLECT reflect Reflection coefficient MATERIAL F BGN bgn Composition temperature and doping dependent band gap narrowing MATERIAL F CONMUN conmun Composition temperature and doping dependent elec tron mobility MATERIAL conmup Composition temperature and doping dependent hole mobility BEA F RADIATE radiate Generation rate as func tion of position BEA F3 RADIATE radiate3 Generation rate as func tion of position 3D MATERIAL F TAUN taun Electron SRH lifetime as a function of position SILVACO International A 3 ATLAS User s Manual Volume 2
310. recommended Syntax UTMOST BIP DIODE MOS lt input gt OUTFILE lt fn gt WIDTH lt n gt lt elec gt lt cntrl gt TRANSLATE INFILE1 lt filename gt lt analysis gt lt parasites gt Parameter Type Default Units AC Logical False ANODE Integer 1 APPEND Logical False BASE Integer BIP Logical False BULK Integer CATHODE Integer COLLECTOR Integer DEVICE Integer 1 DIODE Logical False DRAIN Integer EMITTER Integer GATE Integer INFILE Character INTERNAL Logical False LENGTH Real 1 0 um MESFET Logical False MINSTEP Real 0 01 y MOS Logical False OUTFILE Character POLARITY Integer 1 n type ROUTINE Integer 1 SOURCE Integer 15 150 SILVACO International UTMOST Statement Statements Parameter Type Default Units TEMPERATURE Real 300 K WELL Integer WIDTH Real 1 0 um Description You must specify a technology parameter DIODE or MOS an input file INFILE1 and an output file OUTFILE You may specify one or more of the optional electrode parameters The INFILE parameter is used to convert up to nine ATLAS logfiles into a single UTMOST logfile The ATLAS logfiles must be specified in the form INFILE1 lt fn gt INFILE2 lt fn gt INFILE3 lt fn gt where fn is the name of the logfile that you wish to convert OUTFILE specifies the name of a file in which I V data will be stored in an
311. red in A um RXNORM specifies that both relative and absolute convergence criteria will be used in the solution method This is the equivalent of specifying both XNORM and RHSNORM This is the default and it is not recommended to change this TCR TOL specifies the absolute RHS norm tolerance for convergence of the carrier temperature equations TCX TOL specifies the relative X norm tolerance for convergence of the carrier temperature equations TOL TIME specifies maximum local truncation error for transient simulations TOL LTEMP specifies the temperature convergence tolerance in block iterations using the lattice heat equation 15 72 SILVACO International METHOD Statement Statements TOL RELAX specifies a relaxation factor for all six Poisson continuity and current convergence parameters PX TOL CX TOL PR TOL CR TOL IX TOL and IR TOL TLR TOL specifies the relative X norm tolerance for convergence of the lattice temperature equation TLX TOL specifies the relative X norm tolerance for convergence of the lattice temperature equation WEAK specifies the multiplication factor for weaker convergence tolerances applied when current convergence is obtained XNORM specifies that only the relative errors will be used to determine convergence for the drift diffusion equations If XNORM is used Poisson updates are measured in kT q and carrier updates are measured relative to the local carrier concentration General Parameter
312. rees POLARIZE Real 0 0 Degrees POWER FILE Character 15 4 SILVACO International BEAM Statement Statements Parameter POWER SCAL QUANTUM EFF RAYS RAY TRACE REFLECTS REL POWER WAVELENGTH WAVEL END WAVEL NUM WAV Gl L SCAL WAVEL START X ORIGIN XMAX XMIN Y ORIGIN Z ORIGIN ZMAX ZMIN Type Real Real Integer Character Integer Real Real Real Real Real Integer Real Real Real Real Real Real Real Real Real Default 0 623 0 0 0 0 1 0 1029 1 0 1020 0 0 0 0 1 0 1020 1 0x102 Units Degrees um um um 3 SILVACO International 15 5 ATLAS User s Manual Volume 2 BEAM statement Description X ORIGIN X Woe x SEO gt gt AUTOMATIC CLIPPING TO EDGE OF DEVICE Figure 15 1 LUMINOUS Optical Source Coordinate System ANGLE is the angle of propogation of the optical beam see Figure 15 1 and 11 1 ANGLE 90 is vertical illumination from the top of the device Synonym PHI BACK REFL specifies that back side reflections are to be taken into account When BACK REFL is specified the area outside the device domain is assumed to be a vacuum ie n 1 0 k 0 0 DEVICE is used to specify the name of the device that the beam is associa
313. rescaling is now turned off 17 MIXEDMODE Improvements The DC statement now allows linear logarithmic stepping of sources and nested sweeps Version 3 0 0 R 1 First release of six equation solver version of ATLAS In this release an advanced Non I sothermal Energy Balance Model was implemented The model allows self consistent solution of a set of up to 6 partial differential equations for electrostatic potential electron and hole concentrations electron and hole carrier temperatures and lattice temperature All the important combinations of equations are supported 2 DEVICE3D introduced DEVICE3D is introduced as the first truly 3D simulator in the ATLAS framework It is a virtual analogy to S PISCES With it three dimensional steady state silicon device simulation can be performed to calculate electrical behavior of bipolar and MOS transistors as well as EPROM devices e Syntactically and behaviorally like ATLAS S PISCES e Poisson one carrier or two carrier analysis can be performed e Uses Gummel Newton or combined Gummel N ewton algorithms e Supports semi implicit scheme for transient simulation Significantly faster than TR BDF D 6 SILVACO International ATLAS Version History Supports the essential set of physical models for silicon modeling including SRH recombination Auger recombination and radiative recombination concentration dependent mobility models Conmo
314. riangles of level 1 become level 2 gt triangles The grid is checked for consistency at each level and is updated to avoid abrupt changes of size from one triangle to the next The regrid process continues until no more triangles meet the refinement criteria or until a specified maximum level of refinement is reached Grids used in practice are often coarser than is required to meet desirable refinement criteria and so the maximum level is the key factor in determining the size of the grid after refinement The MAX LEVEL parameter of the REGRID statement is used to limit the amount of refinement at each step By default ATLAS sets the maximum level equal to one more than the highest level in the existing mesh To update a coarse region without regridding the finer regions after a mesh has already been refined several times set the maximum level below the level of the finer regions in the existing grid several levels of regrid are performed in immediate succession interpolated data is used to make the refinement decisions at higher levels Since semiconductor problems are non linear this interpolation may not produce satisfactory results It is often a good idea to calculate a new solution between regrid operations i e to regrid only one level at a time and obtain a new solution each regrid operation Two popular choices of quantities to be used for mesh refinement are potential and doping Ideally variations of electros
315. rofile can be used to change the composition fraction of cations in terniary and quaterniary materials over a spatial distribution Y COMP specifies a profile of composition fraction y as defined in Appendix B This profile can be used to change the composition fraction of anions in terniary and quaterniary materials over a spatial distribution RESISTI can be used to specify resistivity which is converted to carrier concentration in silicon i e this parameter replaces the CONC parameter This conversion uses tables of resistivity versus concentration for donors and acceptors These tables currently make no distinction between specific changes of the same type The Arora mobility model is the basis of these tables Vertical Distribution Parameters CHARACTERISTIC specifies the principal characteristic length of the implant If this parameter is left unspecified the principal characteristic can be computed from the values of the Polarity Parameters e Boundary Parameters e Concentration and Junction parameters CONCENTRATION specifies the peak concentration when a Gaussian profile is used If this parameter is not specified peak concentration may be computed from the values of the polarity boundary DOSE or RESISTI CHARACTERISTIC concentrations When a uniform profile is specified the CONCENTRATION parameter sets the value of the uniform doping level Concentrations must be positive DOSE specifies the total dose fo
316. ron concentration or hole concentration may be integrated over a section of a device The charge on part of an electrode can be calculated as can the current through that part This is useful for capacitance studies in conjunction with the difference mode of the LOAD statement The resistance of a structure cross section such as a diffused line may be calculated E CRIT specifies the critical electric field used to calculate integration integrals ELECTRON extracts integrated electron concentration HOLE extracts integrated hole concentration IONIZINT enable the calculation of ionization integrals Other integral ionization parameters will be ignored unless IONIZINT is specified LRATIO specifies the ratio between electric field lines used in ionization integral calculation The value of this parameter should be set from 0 5 to 1 5 METAL CH extracts integrated charge on a contact N CURRENT extracts n current through an electrode N LINES specifies the number of ionization integrals N RESIST extracts n resistance of a cross section NET CARR extracts integrated carrier concentration NET CHAR extracts integrated net charge NLAYERS controls the distance from the contact where electric field lines start P CURRENT extracts p current through an electrode P RESIST extracts p resistance of a cross section SUBSTR selects the substrate electrode for electric field lines You do not need to specify this parameter if a substrate ele
317. roved run time output Many improvements have been made to the run time outputs of ATLAS e Added multiple levels of verbosity Improved printing of mesh statistics region and electrode summaries and models e Printing of error messages was made more consistent and informative in many places in ATLAS e Removed spurious printout from S parameter extraction with the UTMOST statement 14 New platforms ATLAS has now been ported to DEC Alpha and SGI workstations 15 Miscellaneous bug fixes Inthis release many bugs were removed that existed in the previous version e Fixed bug that caused setting the value of the MODEL statement parameter CCS EA to also set the value of the MATERIAL statement parameter COPTR e Fixed bug causing improper association of nodes with regions BLAZE structures read from DevEdit some instances nodes would be assigned a region at the interface then the composition fraction e g from the opposing region thus causing distortions in the band diagram at the interface e Fixed bug in static projection Bug caused by two consecutive bias steps of opposite polarity e Fixed bug in TFT Caused the midgap Gaussian donor defects to have the same distribution as the midgap acceptor defects e Fixed bug in UTMOST interface Bug caused ATLAS not to recognize routines 2 3 5 12 13 14 and 26 e Thecalculations for the electron and hole mobilities in the InGaAsP system were found to be error both
318. rrier Concentration Floating Field Plates e D 6 8 Inversion Layer Mobility Floating Gates 4 6 4 7 15 11 15 12 lonization Floating GUard RINGS e ee cte ate eek 6 8 Iterative Fourier Analysis essere 14 19 Fowler Nordheim tunneling enn 4 7 15 97 K tien dd E nd tein 9 2 Klaassen s Carrier Concentration fr escalTi rl058 ende ridi 9 5 Dependent Model rere rtt 3 64 Ffegz7e OUL seriei a a EET HRS 3 9 3 10 L G Laplace s equation into tr nein ee 12 1 U 5 20 LASER rada qued tetas 9 1 15 102 081 5 ft eto i Oe ea ian 2 37 Ale CUTE MN ty 3219 4 1 15 98 Lattice Heating eere terere teet 2 21 4 4 4 9 6 1 j 12 4 Leakage Current cete trit ita 4 9 Qeneratioris s a ERO EE DRE REIR RES 5 18 3 eas Ea altel dat 11 1 GMRES rer RM erst otia 14 21 15 69 GUMMEL 4 9 11 8 14 4 15 69 method 944 44 490 90944920904 94 9 2 KI PM 2 1 2 40 15 47 SILVACO International Index 2 low field mobility
319. rs MASTER specifies that the output file selected by the OUTFILE parameter will be written in a standard structure file rather than in the older PI SCES II binary format ONEFILEONLY specifies that only one filename will be used to save solutions during a bias ramp If this parameter is specified filename incrementation described under OUTF ILE is not applied This parameter is true by default unless the NAME or ELECTRODE parameters or transient simulationis specified When CURVETRACE is used it is necessary to explicitly set this parameter to false using ONEFILEONLY to save a different filename at each bias point OUTFILE specifies the name of the output file in which bias point solution information will be stored If an electrode is stepped so that more than one solution is generated by the SOLVE statement the ASCII code of the last non blank character of the supplied file name will be incremented by one for each bias point in succession resulting in a unique file per bias point Note The output file specified by OUTFILE has a limit of 132 characters on a UNIX system and eight characters on a PC system Initial Guess Parameters INITIAL sets all voltages to zero If this parameter is not specified for the first bias point in a given structure a SOLVE INIT statement is automatically inserted The SOLVE INIT statement is always solved in zero carrier mode with no external elements attached It
320. rted grid regions Y LOWER specifies the physical location in the distorted region to which the line specified by LOWER will be moved The line specified by UPPER is not moved The Y LOWER and THICKNESS parameters define the distorted grid region Only one of these paramaters should be specified Optional Parameters ENCROACH defines the abruptness of the transition between a distorted and nondistorted grid The transition region becomes more abrupt with smaller ENCROACH factors the minimum is 0 1 Note Depending on the characteristics of the undistorted grid long thin or obtuse triangles may result if too low an ENCROACH value is used GRADING specifies a grid ratio which produces a non uniform grid in the distorted region This parameter is identical to the RATIO parameter in the X MESH and Y MESH statements and GR2 may be used instead of the GRADING parameter GR1 and GR2 may be specified in conjunction with MIDDLE y grid line and Y MIDDLE location so that GR1 specifies grading in the spread region from UPPER to MIDDLE and GR2 specifies grading from MIDDLE to LOWER MIDDLE specifies the y grid line that serves as a boundary between the grading specified by GR1 and the grading specified by GR2 VOL RATIO specifies the ratio of the downward displacement of the lower grid line to the net increase in thickness The default 0 44 should be used for oxide silicon interfaces V
321. ry Version History Version 5 2 0 R 1 Introduced LUMINOUS3D e LUMINOUSS3D provides a similar functionality to 20 LUMINOUS This allows simulation of interaction between arbitrary optical sources and semiconductor devices in three dimensions 2 Smartlib e Implemented the SmartSpice Compact Device Model Library Smartlib These models replaces the old MIXEDMODE Diode MOSFET and BJ T Models Additional device models such as TFT and SOI can now be used Also additional devices such as FETS and MESFETs can now be used 3 Implemented a New and Improved C Interpreter e Implemented a new C Intrepreter This completely replaces the old version of the C Interpreter The new C Interpreter is faster than the old version and supports more C functions The new C I nterpreter conforms more to the ANSI standard 4 Hetereojunction Thermionic E mission and Field E mission e Introduced a new implementation of thermionic emission models for hetero interfaces This implementation supercedes the previous one which is nolonger supported e Also introduced a new heterojunction tunneling thermionic field emission model that is compatible with the new thermionic emission model 5 Cyclic Biasing e Implemented cyclic biasing model to simplify prediction of steady state conditions cyclically biased devices exhibiting long time constants 6 Miscellaneous Improvements e Added the following new material names InGaN AlGaN InAIGaN
322. s data is required ROUTINE 2 specifies the routine vs data is required ROUTINE S specifies the CJ routine vs data is required ROUTINE 6 specifies the CJSW routine Cpp vs Vps data is required ROUTINE 12 specifies the CJ CJSW routine vs Vgs data is required for two different size drain areas Diode Technology ROUTINE 1 specifies an I vs V plot V is stepped UTMOST ID vs VD routine Note UTMOST 12 3 4 or later can read ATLAS format logfiles directly in batch mode This statement is obsolete and its use is not recommended SILVACO International 15 153 ATLAS User s Manual Volume 2 X MESH Y MESH Z MESH Statement X MESH Y MESH Z MESH lt n gt MESH specifies the location of grid lines along the lt n gt axis in a rectangular mesh for 2 D or 3 D simulation Note The commands are equivalent in the x y or z directions Syntax X MESH LOCATION 1 NODE lt n gt RATIO lt r gt SPACING lt v gt Parameter Type Default Units LOCATION Real um NODE Integer RATIO Real 1 SPACING Real um Description LOCATION specifies the location of the grid line NODE specifies mesh line index There is a limit of 120 mesh lines These mesh lines must be assigned in increasing order RATIO specifies the ratio to use when interpolating grid lines between given locations Spacing between adjacent gridlines will increase or decrease by the factor assigned
323. s ATRAP specifies the multiplication factor which reduces the electrode bias steps when a solution starts to diverge This parameter has no effect unless the TRAP parameter is specified CLIM DD is analogous to CLIMIT except it is expressed in a dimensional value representing the minimum carrier concentration that can be resolved CLIM EB can be treated as a regularization parameter for the case of very small carrier concentrations for energy balance simulation It specifies the minimum value of carrier concentration for which the relaxation term in the energy balance equation will still be properly resolved Carrier temperatures for points where the concentration is much less than CLIM EB will tend to the lattice temperature CLIMIT specifies a concentration normalization factor See the Numerical Techniques chapter for a complete description CUR PROJ enables the use of projection method for initial guesses with current boundary conditions FIX QF fixes the quasi Fermi potential of each non solved for carrier to a single value instead of picking a value based on local bias ITLIMIT or GITLIMIT specifies the maximum number of allowed outer loops Newton loops or Gummel continuity iterations MAXTRAPS specifies the number of times the trap procedure will be repeated in case of divergence The value of MAXTRAPS may range from 1 to 10 MIN TEMP and MAX TEMP are specified to control the absolute range of lattice temperatures allowed dur
324. s BOTTOM Logical False IX HIGH Integer right side of structure IX LOW Integer left side of structure IY HIGH Integer TY LOW TY LOW Integer top of structure IZ HIGH Real IZ LOW Real LEFT Logical False LENGTH Real length of structure um MATERIAL Character Contact NAME Character NUMBER Integer defined electrodes 1 RIGHT 1 False SUBSTRATE iogical False TOP ogical False X MAX Real right side of structure X MIN Real left side of structure um Y MAX Real Y MIN um Y MIN Real top of the structure um Z MIN Real 2 Real um Description MATERIAL specifies a material for the electrode see Table B 1 This material will be displayed in TONYPLOT The electrode material can also be used to define the electrode thermal characteristics thermal conductivity and optical characteristics complex index of refraction Setting the material here does not apply any electrical property such as workfunction to the terminal All electrical properties of electrodes are set on the CONTACT statement SILVACO International 15 29 ATLAS User s Manual Volume 2 ELECTRODE Statement NAME specifies an electrode name Since other parts of the program use standard electrode names it is suggested that these names be used The list of allowed names by other syntax is gate gg drain dd source bulk substrate emitter ee collector cc base bb anode cathode fgate cgate ngate pgate well nwell
325. s Vol 39 Mar 1992 pp 473 478 Zhou J R and Ferry D K Simulation of Ultra small GaAs MESFET Using Quantum Moment Equations II Volocity Overshoot IEEE Trans Electron Devices Vol 39 Aug 1992 pp 1793 1796 Yamada T Zhou J R Miyata H and Ferry D K In Plane Transport Properties of Si Si 1 x Ge x Structure and its FET Performance by Computer Simulation IEEE Trans Electron Devices Vol 41 Sept 1994 pp 1513 1522 Van Dort J Woerlee P and Walker A J A Simple Model for Quantisation Effects Heavily Doped Silicon MOSFETs at Inversion Conditions Solid State Elec Vol 37 No 3 pp 411 414 1994 Hansch W Vogelsang Th Kirchner R and Orlowski M Carrier Transport Near the Si SiO2 Interface of a 5 Solid State Elec Vol 32 No 10 pp 839 849 1989 Hurkx G A M Klaassen D B M Knuvers M P G A New Recombination Model for Device Simulation Induding Tunneling IEEE Trans Electron Devices Vol ED 39 Feb 1992 pp 331 338 Simmons J G and Taylor G W Phys Rev B 4 p 502 1971 Chynoweth A G lonisation Rates for Electrons and Holes in Silicon Phys Rev 109 pp 1537 1540 1958 Baraff G A Distribution Functions and lonisation Rates for Hot Electrons in Semiconductors Appl Phys Rev 128 pp 2507 2517 1962 BIB 6 SILVACO International Bibliography 129 130 131 132 133 134 135
326. s parameter is superceded by Q lt name gt QFINAL specifies the final charge for a set of bias increments If OF INAL is specified either OSTEP or NSTEPS must also be specified QSTEP specifies a charge increment to be added to one or more electrodes as specified by the electrode name applied to the NAME parameter If OSTEP is specified either OFINAL or NSTEPS must also be specified lt gt specifies the bias voltage for a named electrode One of several commonly used terminal names should be specified These names are as follows gate gg drain dd source bulk substrate emitter ee collector cc base bb anode cathode fgate cgate ngate pgate well nwell pwell channel and ground No other user defined names are allowed V n specifies the bias voltage for electrode n Normally Vn defaults to the potential from the previous bias point It is more usual to use electrode names rather than numbers This parameter is superceded by V name SILVACO International 15 131 ATLAS User s Manual Volume 2 SOLVE Statement VFINAL specifies the final voltage for a set of bias increments If VF INAL is specified either VSTEP or NSTEPS must also be specified VSTEP specifies a voltage increment to be added to one or more electrodes as specified by the electrode name applied to the NAME parameter If VSTEP is specified either VF INAL or NSTEPS must also be specified File Output Paramete
327. s 15 137 lonization Integral Example 15 138 SPREAD viii E a P bean woos ven bis ees ar eee v aa d a 15 139 acean Arar ara doc duca a a 15 139 Mandatory Parameters ori conoi i 2 15 139 EXAMPIES I Se LSU EI ESI wee RU AR aa A C UR ER EA DUCERE 15 139 SILVACO International Xiii ATLAS User s Manual Volume 2 SYMBOLIC PE 15 142 SYSTEM CIE FO 15 143 EXaihiBleS evite E Ed roto cb Me ire Ch DA M 15 143 THERMCONTACT 43 537 inire e be eA e edel codo ss 15 144 SHOULD darte De e Fan od ae ied 15 144 Position Parameters 1 oos so Sepe me eR Rr EROR RARE 15 144 Coordinate Definition Example 15 145 TONYPLOT a Fed a re E 15 146 Examples ena onan EE a ace ete E 15 146 TT r C E EN a 15 147 EXAINDIG Pianta de a 15 147 TRAP a a a a aa a a a a DE EEE 15 148 ette vacas 15 148 Capture Parameters 15 149 Multiple T
328. s for reliable convergence Unless special techniques such as projection are used for calculating initial guesses this would mean that the voltage step size during a bias ramp might have to be rather small Decoupled methods can have advantages when the interaction between the equations is small typically low current and voltage levels They do not require such good initial guesses for convergence They tend to either not converge or take excessive CPU time once the interactions become stronger ATLAS uses the METHOD only statement to define numerical methods The older syMBOLICc statement is no longer required although existing input files will run as before To select the decoupled method for two carriers use method gummel carriers 2 To select the coupled method for two carriers use method newton carriers 2 SILVACO International C 3 ATLAS User s Manual Volume 2 This is the default fact users do not need to specify a METHOD statement at all for this case For the majority of isothermal drift diffusion simulations this choice of numerics is the recommended one ATLAS has the ability to switch automatically between different numerical methods The syntax method gummel newton would start each bias point using a decoupled method and then switch to a coupled solution This technique is extremely useful when the initial guess is not good Typically this happens for devices with floating body effects i e SOI For
329. s of the photon densities can cause convergence problems LAS MIRROR specifies the percentage facet reflectivity both facets are assumed to have this value of reflectivity for the mirror loss in Laser 100 reflectivity is equalivent to no mirror loss SILVACO International 15 103 ATLAS User s Manual Volume 2 MODELS Statement LAS MULTISAVE specifies the whether or not to save the transient LASER spectrum as one file or multiple files LAS NEFF specifies the effective refractive index in Equation 9 2 LAS OMEGA specifies the lasing frequency to be used in Equation 9 1 If model 2 is used for simulation then this parameter specifies an estimate of the lasting frequency Instead of using this parameter PHOTON ENERGY can be used to specify photon energy LAS SIN specifies an initial photon density in the fundamental lasing mode This value provides an initial guess for subsequent iterations This parameter is used only when the single frequency model has been selected LAS SPECSAVE the spectrum file will be saved after every LAS SPECSAVE LASER solution steps LAS TAUSS specifies the iteration parameter to be used for the photon rate equation when solving Equation 9 8 LAS TIMERATE specifies that the time dependent photon rate equation will be used in a transient laser simulation LAS TOLER specifies the desired accuracy in photon areas PHOTON ENERGY specifies the energy of photons If model 2 is used for simulatio
330. s using the WAVEL parameter It is also possible to specify spectral sources of light by replacing WAVEL with POWER FILE filename where the file is a UNIX text file defining the spectrum in terms of an XY list of wavelength vs intensity LUMINOUS automatically chooses the number of rays needed to resolve the geometry In the case of FigureC 1 only one initial ray is needed The number of rays used by LUMINOUS is purely a function of the geometry and is not related to optical intensity photogeneration rate or MIN W MAx w The REFLECT parameter is used to limit the number of reflections the light beam is allowed In ATLAS Version 3 0 0 R an alternative parameter MIN POWER is used to set a relative intensity below which no more rays aretraced Theuser has a choice in LUMINOUS as to whether the rays should reflect from the sidewalls and bottom of the device structure If the simulation is of a partial wafer such as is typical for CCD simulation the light should not reflect This is the default shown in Figure C 1 If the simulation is of a complete device such as is typical for solar cells the light should reflect The parameter BACK REFL is used to enable back and side reflection The result of adding this to the previous syntax is shown in Figure C 2 this figure the limit set by REFLECT 2 is also dear as each ray reflects only two times SILVACO International C 1 ATLAS User s Manual Volume 2 The ray
331. see Table 3 19 ALPHAP ARORA see Table 3 19 BETAN ARORA see Table 3 19 BETAP ARORA see Table 3 19 GAMMAN ARORA see Table 3 19 GAMMAP ARORA see Table 3 19 NCRITN ARORA see Table 3 19 NCRITP ARORA see Table 3 19 Caughey Thomas Concentration Dependent Model Parameters MUIN CAUG see Table 3 18 MUIP CAUG see Table 3 18 MU2N CAUG see Table 3 18 SILVACO International 15 85 ATLAS User s Manual Volume 2 MOBILITY Statement MU2P CAUG see Table 3 18 ALPHAN CAUG see Table 3 18 ALPHAP CAUG see Table 3 18 BETAN CAUG see Table 3 18 BETAP CAUG see Table 3 18 GAMMAN CAUG see Table 3 18 GAMMAP CAUG see Table 3 18 DELTAN CAUG see Table 3 18 DELTAP CAUG see Table 3 18 NCRITN CAUG see Table 3 18 NCRITP CAUG see Table 3 18 Carrier Carrier Scattering Model Parameters AN CCS see Table 3 20 AP CCS see Table 3 20 BN CCS see Table 3 20 BP CCS see Table 3 20 Parallel Field Dependent Model Parameters BETAN see Table 3 33 BETAP see Table 3 33 GAMMAN see Table 5 3 GAMMAP see Table 5 3 ECRITN see Table 5 3 ECRITP see Table 5 3 VSATN see Tables 3 33 and 5 3 VSATP see Tables 3 33 and 5 3 ALPHAN FLD see Table 3 33 ALPHAP FLD see Table 3 33 THETAN FLD see Table 3 33 THETAP FLD see Table 3 33 TNOMN FLD see Table 3 33 TNOMP FLD see Table 3 33 Yamaguchi Transverse Field Dependent Model Parameters SN YAMA see Table 3 29 SP YAMA see Table 3 29 NREFN YAMA see Table 3 29 NREFP YAMA see Table 3 29
332. senic dopant information be extracted from an imported file 15 24 SILVACO International DOPING Statement Statements BORON specifies that boron dopant information be extracted from an imported file CHEMICAL specifies that the chemical concentration as opposed to the active concentration will be read from the imported file This is generally not advisable DOPOFF subtracts a background doping value from the ATHENA or SSUPREM 3 doping INDIUM specifies that indium dopant information be extracted from an imported file NET specifies that net doping information be extracted from an imported file This is usually not advisable It is better to use several DOPING statements to extract data dopant by dopant from a file N TYPE DONOR specifies an n type or donor dopant This parameter may be used with GAUSSIAN and UNIFORM profile types ACCEPTOR specifies a p type or acceptor dopant This parameter may be used with GAUSSIAN and UNIFORM profile types PHOSPHORUS specifies that phosphorus dopant information be extracted from an imported file TRAP specifies that the dopant concentration is to be treated as a trap state density OX CHARGE specifies a fixed oxide charge profile Oxide charge can only be placed in any insulator region The N TYPE P TYPE parameters are not used hence a negative concentration implies a negative charge X COMP specifies a profile of composition fraction x as defined in Appendix B This p
333. side this box the profile decreases from the peak CONC with distance from the box along the principal axes The relationship between the concentration outside the box to distance will depend upon the profile type as specified by the GAUSSIAN MASTER ATHENA ATLAS and UNIFORM parameters X LEFT XMIN specifies the left boundary of a vertical 1 D profile X RIGHT X MAX specifies the right boundary of a vertical 1 D profile Y BOTTOM Y MAX specifies the bottom boundary of a horizontal 1 D profile Y TOP Y MIN specifies the top boundary of a horizontal 1 D profile Z BACK Z MIN specifies the back boundary of a z directed 1 D or 2 D profile Z FRONT Z MAX specifies the front boundary of a z directed 1 D or 2 D profile Lateral Distribution Parameters These parameters specify how a vertical 1 D profile is extended outside the box defined by the lateral extent parameters LAT CHAR specifies the characteristic length of the lateral profile If this parameter is not specified the characteristic length is defined by CL RL x where CL is the lateral characteristic length in the x direction RL is the value of RATIO LATERAL OCL is the characteristic length of the original profile in the y direction ERFC LATERAL specifies an error function used for lateral spreading If two dimensional spreading parameters are used in conjunction with a Gaussian profile the lateral impurity profile may be transformed into an error func
334. sient solutions in 3 D In most cases this method is significantly less time consuming that the default TR BDG method SILVACO International 15 71 ATLAS User s Manual Volume 2 METHOD Statement MEINR specifies the Meinerzhagens method whereby carrier temperature equations will be coupled with the associated carrier continuity equation will be used during GUMMEL iterations NEWTON specifies that Newton s method will be used as the solution method in subsequent SOLVE statements until otherwise specified Certain models and boundary conditions settings require that Newton s method is used If no solution methods are specified NEWTON is applied by default Parameters to select which equations are solved CARRIERS specifies the number of carrier continuity equations that solutions will be found for Valid values are 0 1 and 2 CARRIERS 0 implies that only Poisson s equation is solved for CARRIERS 1 implies that only one carrier solution will be obtained When this is specified one should also specify either HOLES or ELECTRONS CARRIERS 2 implies that solutions will be obtained for both electrons and holes ELECTRONS specifies that only electrons will be simulated for single carrier simulation HOLES specifies that only holes will be simulated for single carrier simulations Solution Tolerance Parameters Note Generally the solution tolerances should not be changed Convergence problems should be tackled b
335. small signal AC photogeneration analysis is performed SS PHOT specifies that small signal AC analysis will be performed on the optical beam selected by the BEAM parameter When 55 is specified other AC parameters e g FREQUENCY 5 MAX INNER MULT FREQ NFSTEPS S OMEGA and TOLERANCE should also be specified It is not necessary to specify the AC ANALYSIS parameter when performing small signal AC analysis on optical beams Thermal3D parameters See also the section Obtaining Solutions in THERMAL3D of this manual POWER lt n gt specifies the power in watts on the n th heat source POWERFINAL specifies the final power for a linearly ramped heat source T lt n gt specifies the temperature in K on the n th heat sink TEMPFINAL specifies the final temperature for a linearly ramped heat sink DC Conditions Example The following statement solves for a defined bias point and saves the solution to output file OutA The voltages on electrodes other than the gate will keep the value from the previous SOLVE statement SOLVE VGATE 0 1 OUTFILE OutA Bias Stepping Example In the next example bias stepping is illustrated The two SOLVE statements produce the following bias conditions Bias Point Vgate Vdrain Vsub 1 0 0 0 5 or 2 1 0 0 5 OS 3 2 0 0 5 103 4 3 0 0 5 2035 5 4 0 0 5 FOLS 6 5 0 0 5 20 9 The solutions for these bias points will be sa
336. spectrum is discretized into our wavelengths between 0 4 um and 0 6 um BEAM NUM 2 X 0 0 Y 1 0 ANG 45 0 POWER FILE SOURCE SPC WAVEL START 0 4 WAVEL END 0 6 WAVEL NUM 4 LUMINOUSS3D Lens Example BEAM NUM 1 X ORIGIN 2 5 Y ORIGIN 1 0 Z ORIGIN 2 5 ANG 90 0 WAVEL 0 6 NX 10 NZ 10 LENS X 2 5 LENS Y 0 5 LENS Z 2 5 LENS INDEX 2 03 LENS RADIUS 0 25 LENS PLANE 0 5 15 8 SILVACO International COMMENT Statement Statements COMMENT COMMENT allows comments to be placed an ATLAS input file ATLAS will print and display comment lines Syntax COMMI ENT lt string gt lt string gt string is any alphabetic numeric or alphanumeric sequence of characters Synonyms Example COMMI ENT ATLAS is a copyright of Silvaco International ATLAS is a copyright of Silvaco International Note The was allowed as a comment character in previous versions of ATLAS This should be avoided and replaced by the or COMMENT statement 15 9 SILVACO International ATLAS User s Manual Volume 2 Contact Statement CONTACT CONTACT specifies the physical attributes of an electrode Note If the CONTACT statement is not used for a given electrode the electrode is assumed to be charge neutral ohmic Syntax CONTACT NUMB Parameter ALL ALPHA ALUMINUM BARRIER CAPACITANCI
337. stance Example This example extracts the resistance of a p type line diffused into a lightly doped n substrate Since the p conductivity of the substrate is negligible the integration bounds can include the whole device MEASURE P RESIST Gate Charge Example In this example the charge on the lower surface of a gate electrode is integrated There is 0 05 um of gate oxide on the surface which is located at y 0 MEASURE METAL CH 1 2 0 X MAX 2 0 Y MAX 0 0499 Y MIN 0 0501 lonization Integral Example This example shows how to extract the maximum ionization integral in the device MEASURE IONIZINT CONTACT 3 SUSTR 4 N LINES 200 NLAYERS 15 LRATIO 1 1 This syntax was the original implementation of ionization integrals in early ATLAS versions It has been superceded See the SOLVE and OUTPUT statements for the recommended approach to extract ionization integrals SILVACO International 15 65 ATLAS User s Manual MESH Statement MESH MESH generates a mesh or reads a previously generated mesh Syntax MESH lt prev gt lt new gt lt output gt Parameter Type Default Units ATHENA Logical False CYLINDRICAL Logical False DIAG FLIP Logical True FLIP Y Logical False INFILE Character MASTER IN Logical True MASTER OUT Logical True NX Integer NY Integer NZ Integer OUTFILE Character PISCES VIN Lo
338. start of a list of pseudonyms gt Indicates the end of a list of pseudonyms Separates parameters or pseudonyms which are mutually exclusive Only one of these parameters may be used in a statement Indicates the start of an optional command parameter or pseudonym Indicates the end of an optional command parameter or pseudonym Expressions ATLAS does not support arithmetic expressions in the syntax Expressions can be evaluated and used using the SET or EXTRACT statements however SILVACO International 15 3 ATLAS User s Manual Volume 2 BEAM statement BEAM BEAM specifies an optical input signal in the form of a collimated beam of light This statement is used with LUMINOUS or LUMINOUS3D Syntax BEAM parameters Parameter Type Default Units ANGLE Real 0 0 Degrees BACK REFL Logical False DEVICE Character Character F RADIATE Character F RADIATES3D Character F REFLECT Character FRONT REFL Logical False ITERATION Integer 20 LENS INDEX Real d LENS PLANE Real 0 0 um LENS RADIUS Real 0 0 um LENS X Real 0 0 um LENS Y Real 0 0 um LENS Z Real 0 0 um MAX WINDOW Real 1 0x1029 um ETAL REFLECT Logical False IN POWER Real 0 0 um IN WINDOW Real 1 0 1029 um NUMBER Integer 1 NX Interger 10 NZ Integer 10 PERIODIC Logical False PHI Real 0 0 Deg
339. t Parasitics Note There are restrictions on the allowed numerical methods and types of analysis possible when any form of parasitic element is attached to a contact See the Getting Started section for details RESISTANCE specifies a lumped resistance value You may not specify both RESISTANCE and CON RESIST INDUCTANCE specifies an external inductance which is related to the specified electrode A synonym is L CAPACITANCE specifies a lumped capacitance value to be attached to the contact CON RESIST specifies a distributed contact resistance You cannot specify both CON RESIST and RESIST Electrode Linking Parameters These parameters allow one electrode to be biased as a function of another electrode This allows separate regions of the same physical contact to be linked together For example in the statement CONTACT NAME MYDRAIN COMMON DRAIN FACTOR 4 6 Electrode mydrain is linked to the electrode drain The bias on mydrain will always be equal to the bias on the drain plus 4 6 If the optional MULT parameter had been specified the bias on my drain would be equal to the bias on the drain multiplied by 4 6 COMMON specifies the electrode name to which the contact refered to by NAME is linked Although the electrodes are linked separate currents will be saved for both electrodes unless SHORT is also specified The electrode refered to in NAME should not appear on any SOLVE statments since it s
340. t analysis is being performed and that a sinusoid with a frequency specified by the FREQUENCY parameter should be applied TSAVE MULT specifies a multiplier the save time increment SAVE is multiplied by after each time a structure is saved TSTEP or DT specifies the time step to be used For automatic time step runs DT is used to select only the first time step see the METHOD statement TSTOP specifies the end of the time interval If simulation begins at t tg it will end at t TSTOP to AC Parameters AC ANALYSIS specifies that AC sinusoidal small signal analysis should be performed after solving for the DC condition The full Newton method must be used for this analysis This is typically specified with the statement METHOD NEWTON CARRIERS 2 ANAME specifies the name of the electrode to which the AC bias will be applied See also TERMINAL If no ANAME is specified all electrodes have AC bias applied in turn AUTO selects an automatic AC analysis method This method initially uses SOR The DIRECT method will be used if convergence problems occur We strongly recommend the use of the AUTO parameter DIRECT selects the direct AC solution method This method is robust at all frequencies but slow FREQUENCY specifies the AC analysis frequency Analysis may be repeated at a number of different frequencies without solving for the DC condition again by specifying FSTEP FREQUENCY can also be used to specify
341. t equal to 300K To define the RHS norms used in ATLAS first represent the non linear equations obtained after discretization at every node as ag 0 14 25 where can be v n p TL and for the potential equation electron continuity equation hole continuity equation lattice temperature equation electron temperature equation and hole temperature equation respectively X represents the vector of unknowns 14 12 SILVACO International Numerical Techniques The RHS norms in ATLAS is then defined as follows For the potential equation ef Mg For the electron and continuity equations Cr m I f Cr where CT 10 4 4 N N kT For the lattice temperature and carrier temperature equations ef Newton iterations are terminated if one of the following criteria is satisfied a the parameter XNORM is true and 5 W S i Ww lt Er S TL W Er lt T tol W x Er lt TL W where w 1 14 26 14 27 14 28 14 29 14 30 14 31 14 32 14 33 14 34 14 35 14 36 14 37 SILVACO International 14 13 ATLAS User s Manual Volume 2 b the parameter RHSNORM is true conditions for Equations 14 36 14 37 are satisfied for w 1 and r S Pi Wi 14 88 e lt Mig 14 39 e S Poi Wp 14 40 lt TE Wa 14 41 lt Wi 14 42 er W
342. t only vector components will be included in the standard structure file X COMP specifies that the composition fraction x is to be written to solution files specifies that the composition fraction is to be written to solution files SILVACO International 15 109 ATLAS User s Manual Volume 2 OUTPUT Statement lonization Integral Parameters Note See the SOLVE statement and the on line examples for instructions on using ionization integrals INAME specifies the name of a contact for which electric field lines are calculated CONTACT specifies a contact number for which electric field lines are calculated LRATIO specifies the spacing ratio between adjacent electric field lines Defaults to 1 0 for uniform spacing N LINES specifies the number of electric field lines DELTAYV since the electric field is near zero at the contact the electric field line calculations begin at a distance from the contact at which the contact voltage has changed by DELTAV Defaults to 0 1 V Averaging Parameters for Vector Quantities OLD AVG specifies that the current and field quantities will be averaged using an older algorithm from version 3 0 0 R and back By default the new method is used ANGLE specifies that averaging of current and fields will be weighted by the size of the angle of triangles intersecting at the node INV ANGLE specifies that averaging of current and fields will be weighted by the i
343. tatic and quasi F ermi potentials across an element would be limited to no more 14 2 SILVACO International Numerical Techniques than kT q and variations in doping would be no more than a factor of 5 or so In practice the refinement criteria are often significantly coarser around 10 20 kT q for potential and two to three orders of magnitude for doping In high level injection situations it is a good idea to regrid when the value of minority carrier concentration exceeds the local doping concentration Mesh Smoothing Although every step of grid generation can introduce obtuse triangles two steps in particular can cause problems The first is that distorting a rectangular mesh introduces a very large number of obtuse elements The second is that when regridding a rectangular grid that contains triangles with an aspect ratio of 4 1 or greater very obtuse triangles are created in the transition region between high and low grid density The REGRID statement allows several procedures to be used when dealing with poorly shaped elements such as obtuse triangles The two techniques are node smoothing and triangle smoothing With node smoothing several iterative passes are carried out during which each node is moved to a position which improves the angles of the triangles surrounding it Node smoothing should only be used for grids that are already irregular If node smoothing is used for nearly rectangular grids it may significantly degrad
344. ted in the VWF INTERACTIVE TOOLS manual There are limits on the maximum number of nodes that can be specified Two dimensional ATLAS simulations may have up to 9 600 nodes Three dimensional simulations may have up to 200 000 nodes 400 000 elements with no more than 20 000 in a single plane and a maximum of 200 planes in the z direcction Most devices can be adequately simulated in two dimensions using meshes that contain from several hundred to around 3000 nodes Mesh Regridding The REGRID statement supports refinement of regions of the mesh according to specified criteria Refinement can occur when a specified solution variable exceeds some value or when the change in that variable across a triangle exceeds a value The variable can be any of the key quantities in a problem such as potential carrier concentration doping concentration or electric field The regrid algorithm searches the initial grid for triangles that meet the criterion specified for refinement Each triangle that is identified is divided into four congruent subtriangles Grid quantities doping potential carrier concentrations and so forth are interpolated onto the new nodes using linear or logarithmic interpolation as appropriate for that quantity The initial grid is referred to as being on level 0 and the new triangles are referred to as on level 1 After all level 0 triangles have been examined the same procedure is applied to level 1 triangles and any subt
345. ted with in MIXEDMODE simulation F REFLECT specifies the name of a file containing a C INTERPRETER function for specifying reflection coefficient models as a function of wavelength position and angle incidence LUMINOUS only F RADIATE specifies the name of a file containing a C INTERPRETER function for specifying generation rate as function of position and optionally time This function can be used to simulate single event upset LUMINOUS only F3 RADIATE is the same as the RADIATE parameter but is applied in 3 D This is typicallyused for single event or photogeneration simulations with LUMINOUS3D FRONT REFL specifies that front side reflections are to be taken into account When FRONT REFL is specified the area outside the device domain is assumed to be a vacuum ie n 1 0 k 0 0 LENS INDEX sepcifies the index of refraction of a lenslet LUMINOUS3D only LENS PLANE sepcifies specifies the minimum y cordinate of the lenslet sphere LUMINOUS3D only LENS RADIUS sepcifies the radius of the spere defining a lenslet LUMINOUS3D only LENS X sepcifies the x coordinate of the center of the spere defining a lenslet LUMINOUS3D only LENS Y sepcifies the y coordinate of the center of the spere defining a lenslet LUMINOUS3D only LENS Z sepcifies the z coordinate of the center of the spere defining a lenslet LUMINOUS3D only MAX WINDOW specifies the maximum x value of the illumination window relative to the coordi
346. ter is true by default so the output file will conform to SILVACO Standard Structure File Format and can be plotted in TONY PLOT SMOOTH KEY specifies a smoothing index digits of the index are read in reverse order and interpreted as follows 1 Triangle smoothing All region boundaries remain fixed 2 Triangle smoothing Only material boundaries are maintained 3 Node averaging 4 Improved triangle smoothing method This method uses diagonal flipping to reduce the number of obtuse triangles 5 Triangle smoothing by flipping diagonals according to electric field Usually option 1 is sufficient Option 2 is useful only if a device has several regions of the same material and the border between different regions is unimportant Option 3 is not recommended when the initial mesh is basically rectangular such as mesh information usually obtained from SSU PRE M4 Option 4 is similar to option 1 but option 4 usually creates less obtuse triangles Mesh Definition Example This example initiates a rectangular mesh and stores the mesh in file MESH1 STR SILVACO International 15 67 ATLAS User s Manual MESH Statement MESH RECTANGULAR NX 40 NY 17 OUTF MESH1 STR ATHENA Interface Example This syntax reads in a mesh from ATHENA or DEVEDIT MI ESH E NMOS STR When the auto interface feature is used in DECKBUILD the program will automatically insert the MESH statement to load the result of previ
347. the valence band The value of the ASYMMETRY parameter is multiplied by the total change in band gap due to band gap narrowing and that product is applied to the conduction band edge For example if the ASYMMETRY parameter has a value of 1 0 then the change in band gap due to band gap narrowing is applied only to the conduction band edge and the valence band edge remains unaffected BGN E BGN N and BGN C specify the parameters of the band gap narrowing model given in Equation 3 38 EAB specifies acceptor energy level see Equation 3 44 EDB specifies donor energy level see Equation 3 43 F BGN specifies the name of a file containing a C INTERPRETER function for the specification of temperature composition and doping dependent bandgap narrowing models GCB specifies the conduction band degeneracy factor see Equation 3 43 GVB specifies the valence band degeneracy factor see Equation 3 44 Energy Balance Parameters TAUMOB EL specifies the relaxation time for electrons in the temperature dependent mobility model TAUMOB HO specifies the relaxation time for holes in the temperature dependent mobility model TAUREL EL specifies the relaxation time for electrons in the energy balance model see Equation 3 95 TAUREL HO specifies the relaxation time for holes in the energy balance model see Equation 3 96 TRE T1 TRE T2 TRE T3 TRE W1 TRE W2 TRE W3 TRH T1 TRH T2 TRH T3 TRH W1 TRH W2 and TRH W3 are used in the temperature depen
348. tial mobility FLDMOB EVSATMOD 1 2 Recombination Shockley Read Hall SRH Concentration dependent lifetime SRH CONSRH Klaassen s concentration dependent lifetime SRH KLASRH Auger AUGER Klaassen s concentration dependent Auger recombination model KLAAUG Optical Recombination OPTR e Bulk interfacetraps TRAP INTTRAP Continuous defect states DEFECT 3 Generation Selberherr Impact lonization IMPACT SELB e Crowell Impact Ionization IMPACT CROWELL Hot Electron Injection HET Fowler Nordheim Tunneling FNORD Single Event Upset SINGLEEVENTUPSET 4 Carrier Statistics Boltzmann default Fermi FERMI Band Gap Narrowing BGN e Incomplete Ionization INCOMPLETE Quantum Mechanical Effects QUANTUM 5 Boundary Conditions e Ohmic Schottky Current Boundary Conditions Lumped Element Boundary Conditions Distributed Contact Resistance 114 SILVACO International 3D Device Simulation 6 Interface and Bulk Traps Discrete and Continuous 7 Photogeneration with Ray Tracing LUMINOUS3D All these models with the exception of SINGLEEVENTUPSET are documented in the Physics or 2D product chapters of this manual Simulation of Single Event Upset The capability of single event upset photogeneration transient simulation is included in 3D using the SINGLEEVENTUPSET
349. tion RATIO LATERAL is the ratio of characteristic lengths in the x and y directions SLICE LAT specifies the point at which the doping is examined to compute the characteristic length of a Gaussian profile after JUNCTION has been specified The default for this parameter is a point halfway between the end of the constant box and the given depth ZLAT CHAR specifies the characteristic length of the laterial profile in the z direction See also LAT CHAR ZRATIO LATERAL is used analogously to RATIO LATERAL but applies to lateral spreading in the z direction See also LAT CHAR ZSLICE LAT is analogous to SLICE LAT but applies to profiels in the z direction Trap Parameters Note See the TRAP statement for more information on each of these parameters 15 26 SILVACO International DOPING Statement Statements DEVICE specifies which device the statement applies to MIXEDMODE simulation REGION specifies which region the traps apply to If unspecified the traps apply to all regions E LEVEL sets the energy of the discrete trap level For acceptors E LEVEL is relative to the conduction band edge for donors it is relative to the valence band edge DEGEN FAC specifies the degeneracy factor of the trap level used to calculate the density SIGN speccifies the capture cross section of the trap for electrons SIGP specifies the capture cross section of the trap for holes TAUN specifies the lifetime of electrons in t
350. tion Integral Parameters Ionization parameters are used to calculate ionization integrals No calculation will take place unless the IONIZINT parameter is specified 15 134 SILVACO International SOLVE Statement Statements DELTAYV since the electric field be near zero at electrodes the electric field line calculations begin at a distance from the electrode A potential contour is drawn around the electrode at a distance where the potential is DELTAV less than the applied bias on the contact Defaults to 0 1 V but will typically need to be increased especially for power devices and heavily doped contact regions E CRIT specifies the minimum electric field used to calculate integration integrals Field lines will terminate when the field drops below E CRIT INAME specifes the electrode name from which the electric field lines are calculated The default is to use the same as electrode as specified in NAME ION CRIT specifies the critical value of the ionization integral used by IONSTOP to terminate the simulation When the critical value is reached any bias ramp will be terminated and the next line of the input file will be executed ION ELEC specifies the electrode from which the electric field lines are calculated This parameter defaults to the electrode which is being ramped if any IONIZINT enables the calculation of ionization integrals along electric field lines IONLINES specifies the number of electric field
351. tion is again saved in a separate file DOWN1 DOWN2 etc No initial timestep was required since one had been estimated from the last transient solution from the previous SOLVE statement Finally the fourth SOLVE statement performs the steady state solution at Vbe 0 5V and 2V METHOD 2ND TAUTO AUTONR SOLVE Vbase 1 Vcollector 2 SOLVE Vbase 2 DT 1E 12 TSTOP 25E 9 RAMPTIME 10E 9 OUTF UP1 lt SOLVE Vbase 0 5 TSTOP 100E 9 RAMPTIME 20E 9 OUTF DOWN1 SOLVE Vbase 0 5 Vcollector 2 AC Analysis Example The following example illustrates an application of the SOLVE statement for AC analysis It is assumed that the device has three electrodes This analysis is being performed after DC conditions are solved at V1 OV 0 5V 1 0V 1 5 and 2 0V A series of 10mV AC signals with frequencies of 1 MHz 10 MHz 100 MHz 1 GHz 10 GHz and 100 GHz are applied to each electrode in the device Ninety AC solutions will be performed 5 X 6 X 3 90 SOLVE V120 V220 V320 5 0 5 NSTEPS 4 ELECT 1 AC FREQ 1E6 FSTEP 10 MULT F NFSTEP 5 VSS 0 01 Photogeneration Examples The following statement simulates two DC optical beams incident on the device with optical spot powers of 15 and 25 Wlcm SOLVE 1 15 B3 25 The next example shows how DC spot power of the two optical beams can be stepped simultaneously Beam 1 wil
352. tion velocities and barrier lowering A definition in the second statement overrides that definition in the first statement CONTACT ALL NEUTRAL CONTACT NUMBER 2 ALUMINUM SURF REC BARRIER SILVACO International 15 13 ATLAS User s Manual Volume 2 Contact Statement Parasitic Resistance Example This example attaches a lumped resistor with a value of 10 Qum to the substrate A distributed contact resistance of 10 Q cm is included on the drain CONTACT NAME substrate RESISTANCE 1E5 CONTACT NAME drain CON RESIST 1E 6 Floating Gate Example This syntax defines a floating contact with a workfunction equal to 4 17eV An extra 1fF um capacitance is added between this electrode and the electrode named cgate CONTACT NAME fgate FLOATING N POLY EL1 CAP cgate FG1 CAP le 15 Note The command MODI ELS PRINT can be used to echo the back contact workfunction and parasitic elements settings to the run time output 15 14 SILVACO International CURVETRACE Statement Statements CURVETRACE CURVETRACE sets the parameters for the automatic curve tracing routine Syntax CURVETRACE lt params gt Parameter Type ANGLE1 Real ANGLE2 Real ANGLE3 Real BEG VAL Real CONTR ELEC Integer CONTR NAME Character CURR CONT Logical END VAL Real INCUR Real INDL Real NEXTST RATIO Real
353. tions in S PiscEs See Chapter 4 for more information on particular simulation techniques BLAZE3D BLAZE3D allows simulation of semiconductor devices with semiconductor compositional variations heterojunction devices Blaze3D is completely analogous to Blaze see Chapter 5 with some exceptions First the current version of Blaze3D does not allow or account for compositional variations in the Z direction Second the current version does not account to thermionic interfaces at abrupt heterojunctions GIGA3D Giga3D is an extension of Device3D or Blaze3D that accounts for lattice heat flow in 3D devices Giga3D has all the functionality of GIGA see Chapter 6 with a few exceptions First additional syntax has been added to account for the three dimensional nature of thermal contacts The parameters 7 MIN and 7 MAX can be specified on the THERMCONTACT statement to describe the extent of the contact in the Z direction The other exception in the current version is that there is no BLOCK method available in the 3D version SILVACO International 11 1 ATLAS User s Manual Volume 2 TFT3D TFT3D is an extension of DEvicE3D that allows the simulation of amorphous and polycrystalline semiconductor materials in three dimenstions TFT3D is completely analogous to the TFT simulator described in Chapter 7 The complete functionality of the TFT simulator is available in TFT3D for three dimensional devices MIXEDMODE3D M1XE
354. tions of lattice temperature with electron and hole temperatures e GIGA now supports static projection for initial guesses for lattice temperature 9 LUMINOUS improvements In this release many improvements were made to LUMINOUS e LUMINOUS now supports extraction of spatial response to optical sources AMIN POWER parameter of the BEAM statement can now be used limit the number of rays traced in LUMINOUS e LUMINOUS now recognizes metals electrodes as bulk regions e Optical properties of bulk metal electrodes region can now be defined e The C Interpreter function RADIATE for user definable photogeneration was enhanced to indude time dependence 10 TFT improvements Several enhancements were made in this release for TFT e Parameters were introduced to allow control of the number of mid gap states used for TFT simulations e TFT now supports output of donor and acceptor trap state densities and energies to user specifiable files for examination by ToNYPLOT now provides two new Interpreter functions for specifying the donor and acceptor densities as a funcion of energy 11 Miscellaneous new features A host of new features were introduced into ATLAS in general ATLAS now properly handles touching electrodes and electrodes with the same name Incorporated the trap assisted tunneling model given in Hurkx G A M Klassen D B M and Knuvers M P G A New Recombination Model for Device Simulation Induding Tunneling IEEE Trans
355. to the RATIO parameter A RATIO value of between 0 667 and 1 5 is recommended RATIO should not be used if SPACING is specified SPACING specifies the mesh spacing at the mesh locations specified by the LOCATION parameter If the SPACING parameter is specified the NODE and RATIO parameters should not be specified If the SPACING parameter is used to specify mesh spacings the NX NY and NZ parameters of the MESH statement should not be specified When the mesh spacings are specified using the SPACING parameter the mesh size will be calculated Example Setting Fine Grid at A Junction This example shows how to space grid lines closely around a junction at y 0 85 microns Y MESH LOC 0 0 SPAC 0 2 Y MESH LOC 0 85 SPAC 0 01 Y MESH LOC 2 SPAC 0 35 15 154 SILVACO International Appendix A C Interpreter Functions Introduction ATLAS has a built in c language interpreter that allows many of the models contained in ATLAS to be modified order to use the SILVACO C INTERPRETER C language functions containing analytic descriptions of the model must be written The C INTERPRETER uses the ANSI standard definition of c If you are not familiar with the c language we suggest you refer to any of the popular c language references such as the one written by Kernighan and Ritchie 74 Additional information about the C INTERPRETER Can be found in the SILVACO C INTERPRETER MANUAL The function arguments of the C INTERPRETER functi
356. trace is only done once a SOLVE statement is used to turn on the light beam For example the syntax SOLVE B1 0 5 sets the power of beam 1 to 0 5W cm DC and transient ramps of light intensity can also be performed The refraction and reflection are determined by the real portion of the refractive index for each material The imaginary portion on the refractive index controls the absorption of the light Wavelength dependent defaults exist in ATLAS for common materials but can be defined by the user as follows MATERIAL MATERIAL Silicon REAL INDEX value IMAG INDEX value From the ray trace information and the imaginary refractive indices the photogeneration rate is calculated at each node in the structure An integration method is used to ensure the charge generated is independent of the mesh density The photogeneration rate from the ray trace in Figure C 2 is shown in Figure C 3 The electrons and holes generated are included in electrical simulations in ATLAS to determine collection efficiency spectral response and other device parameters ATLAS Rav TRACE FROM NON NORM AL LIGHT Hicrons Figure C 1 Simple ray trace in LUMINOUS ATLAS RAY TRACE WITH BACK REFLECTION icons Hicrons Figure C 2 Addition of back and sidewall reflection to Figure C 1 C 2 SILVACO International Hints and Tips File 7 View Plot v Tools v
357. trodes e Temperature distributions can be examined using TONYPLOT3D 4 INTERCONNECT3D introduced INTERCONNECT3D has been introduced as another 3D capability the ATLAS framework This simulator is used to extract parasitics from arbitrary 3D interconnect structures e extract parasitic capacitance and conductance for arbitrary 3D interconnect structures e Provides an interface to MASK Views for simple mask layer definition of interconnect structure e Completely compatible with ATLAS 5 Curvetracer introduced Allows automatic tracing of complex IV behavior including functions that are multivalued without user intervention Automatically varies an external resistance on a given contact to ensure optimal steps are chosen 6 Enhancements for Energy Balance Model Aside from the introduction of the Six Equation Solver several other improvements were made with respec to the E nergy Balance Model EBM e Fermi statistics can be used with the EBM The GaAs like mobility model can be used with the EBM e Theenergy relaxation length can be specified for impact ionization in the EBM e Carrier temperature projection for initial guesses is supported 7 New solution methods 8 GIGA improvements Aside from the introduction of the Six Equation Solver several other enhancements were made to GIGA SILVACO International D 7 ATLAS User s Manual Volume 2 e GIGA now allows self consistent 5 and 6 equation solu
358. ts warnings and error messages QUIET specifies the maximum of filtering of run time output VERBOSE specifies the mimimum filtering of run time output You should specify VERBOS residual norms Example The following syntax can be used to provide extra debugging output OPTION VE RBOSE Note The VERBOSE output is of little interest to most users E if you want output of SILVACO International 15 105 ATLAS User s Manual Volume 2 OUTPUT Statement OUTPUT OUTPUT allows the user to specify the data that will be stored in standard structure format files Syntax OUTPUT lt parameters gt Parameter Gl ANGLI AREA BAND PARAM CHARGI Gl CON BAND CONTACT DELTAV DEVDEG E FIELD E LINES MOBILITY E TEMP E VELOCITY EFIELD EIGENS EX FIELD EX VELOCITY EY FIELD EY VELOCITY FLOWLINES H MOBILITY H TEMP H VELOCITY HX VELOCITY HY VELOCITY IMPACT INV AREA INV ANGLI Gl Type Logical Logical jogical jogica l jogical Integer Real jogica l jogica l jogica l jogical Ogica 1 Integer jogica l jogical jogical jogica l jogical
359. ty deg cm W Reference SiN 0 585 0 185 4 513 4 0 585 0 185 4 B 20 SILVACO International Material Systems Optical Properties The default values for complex index of refraction in LUMINOUS are interpolated from tables from the Handbook of Optical Constants first and second editions Rather than print the tables here the ranges of optical wavelengths for each material are listed in Table B 24 Table B 24 Wavelength Ranges for Default Complex Index of Refraction Material ae Composition Fraction Wavelengths microns Silicon 300 NA 0 0103 2 0 AlAs 300 NA 0 2213 50 0 GaAs 300 A 0 0 0 9814 InSb 300 NA 0 2296 6 5 InP 300 NA 0 1689 0 975 Poly 300 A 0 1181 18 33 5102 300 0 1145 1 7614 Note The parameter INDEX CHECK can be added to the SOLVE statement to list the values of real and imaginary index being used in each solution SILVACO International B 21 ATLAS User s Manual Volume 2 User Defined Materials The current version of ATLAS does not directly support user defined materials A simple workaround can be done using the already existing user specifications This workaround is based on the use of an already existing material name and modifying the material parameters as appropriate In ATLAS material names are defined to give the user a reasonable set of default material parameters Any
360. uation 3 126 ARORA specifies that the Arora analytic concentration dependent model is to be used for electrons see Equation 3 127 SURFMOB N invokes the effective field based surface mobility model for electrons see Equation 3 190 SURFMOB P invokes the effective field based surface mobility model for holes see Equation 3 191 SCHWARZ N specifies the use of transverse electric field dependent mobility models for electrons See TFLDMB1 or SCHWARZ in the MODELS statement SCHWARZ P specifies the use of transverse electric field dependent mobility models for holes See TFLDMB1 or SCHWARZ in the MODELS statement TASCH N specifies a transverse electric field dependent mobility model for electrons based on Tasch see Equations 3 171 through 3 189 TASCH P specifies a transverse electric field dependent mobility model for holes based on Tasch see Equations 3 171 through 3 189 EVSATMOD specifies which parallel field dependent mobility model see Equations 3 198 and 5 50 should be used for electrons as follows Use the standard saturation model Equation 3 198 2 Use the negative differential mobility saturation model Equation 5 50 MOBMOD N specifies transverse field degradation for electrons as follows No transverse degradation 2 Use the Watt or Tasch transverse field models depending on the settings of FIELDMOB1 and FIELDMOB2 3 Use the Yamaguchi transverse field dependent model
361. uld be modeled using equation 13 4 15 60 SILVACO International MATERIAL Statement Statements TCON RECIPRO specifies that the temperature dependence of thermal conductivity should be modeled using equation 13 5 TC NPOW specifies the value of the coefficient of temperature dependence of thermal conductivity n in equation 13 3 TMUN and TMUP specify the temperature coefficients for the temperature dependence of electron lattice mobility and of hole lattice mobility respectively Oxide Material Parameters SEMICONDUC specifies that an oxide region is to be treated as a semiconductor OXCH ONLY specifies that electron and hole concentrations are omitted from Poisson s equation in oxides Photogeneration Parameters F INDEX specifies the name of a file containing a C INTERPRETER function for the specification of wavelength dependent complex index of refraction models IMAG INDEX specifies the imaginary portion of the refractive index of the semiconductor see Equation 8 12 Wavelength dependent defaults exist for certain materials as documented in Appendix B INDEX FILE specifies the filename from which refractive indices for a material are read This parameter is useful to load wavelength dependent refractive indices for use with both mono and multi spectral light sources The format of this file is n wavelength 1 real index 1 imaginary 1 wavelength 2 real index 2 imaginary index 2 wavel
362. ulfilled for weaker values of tolerances i e for specified tolerances multiplied by the parameter W and current criteria 14 4 and 14 5 are satisfied To exclude the X norm criterion xNORM should be specified in the METHOD statement to exclude RHS norm criterion RHSNORM should be specified to exclude the current criterion E1 and E2 should be made very small All the above mentioned tolerances can be changed simultaneously by specifying the relaxation factor TOL RELAX in the METHOD statement 14 8 SILVACO International Numerical Techniques Table 14 1 User Specifiable Parameters for Convergence Criteria Symbol Statemen Parameter Default x ETHOD PX TOL 1079 Pol x ETHOD CX TOL 1075 x ETHOD TLX TOL 10 5 TL x ETHOD TCX TOL 1079 PR TOL 5 0x10 9 tol ETHOD CR TOL 5 0x10718 tol r ETHOD TLG TOL 100 TL r ETHOD TCR TOL 100 TC Ey ETHOD IX TOL 2 0 1072 ETHOD IR TOL 5 0x10725 ETHOD WEAK 200 TOL RELA ETHOD TOL RELAX X XNORM ETHOD XNORM RUE RHSNORM ETHOD RHSNORM RUE CLIMIT ETHOD CLIMIT 104 CLIM DD ETHOD 4 5x1013 CLIM EB ETHOD CLIM EB 0 SILVACO International 14 9 ATLAS User s Manual Volume 2 Detailed Convergence Criteria Only in very difficult situations
363. ultiplies the contact perimeter in a given Z plane by the displacement in the Z direction This algorithm will only work properly for planar contacts that do not vary in the Z direction They may however abruptly terminate or start in the Z direction The units of lumped extrnal passive elements are ohms for resistors F arads for capacitors and Henrys for inductors Distributed contact resistance is defined in ohms am Thermal Contacts for GIGA3D Thermal contacts for non isothermal simulation in GIGA3D are defined an analagous manner to the 2D thermal contacts in GIGA The Z MIN Z MAX parameters are used to define the extent of the thermal contact in the z plane The units of the thermal resistance parameter ALPHA are scaled in 3D to W cm K SILVACO International 11 7 ATLAS User s Manual Volume 2 BLAZE3D Models Models for simulating materials are supported BLAZE3D The material parameters for all compound semiconductors the same as used 2 D simulations with BLAZE Specialized models for III V materials including heterojunction transport optical recombination and negative differential field dependent mobility are documented in Chapter 5 Models Models for simulating thin film transistors made from amorphous or polycrystalline semiconductors are supported in TFT3D The definition of the continuous defect states in the bandgap is performed using the same parameters as in 2D simul
364. us The parameter THETA specifies the rotated angle of propogation relative to the x y plane see Figure 11 2 11 8 SILVACO International 3D Device Simulation X ORIGIN Y ORIGIN DEVICE Figure 11 1 Source beam coordinate rotation around Z axis THETA Z ORIGIN X ORIGIN Figure 11 2 Source beam coordinate rotation around Y axis Ray tracing The discrete sampling of the source beam into rays in Luminous3D is unlike that done in Luminous Luminous the source beam is automatically broken up into a set of rays that resolve the device topology and variations in the interior of the device In 3D this process is much more complex and introduces an excessive computational burden As such in LuMiNOUS3D the user must specify a discrete sampling of the source beam This sampling is described in Figure 11 3 SILVACO International 11 9 ATLAS User s Manual Volume 2 Figure 11 3 Source beam sampling In Figure 11 3 the extent of the source sampling is specified by the XMIN ZMIN and ZMAX parameters of the BEAM statement Even samples are taken along each of the beam front principal axes The number of samples in the x and Z directions are given by the Nx and Nz parameters of the BEAM statement Lenslet specification Another significant difference between LUMINOUS and LUMINOUS3D is that 3 D the user may specify a virtual lenslet This capability is provi
365. us the rays generated during ray tracing are stored in all subsequent structure files In LUMINOUS3D this is not true In order to savetherays in LUMINOUS3D the RAYTRACE parameter of the BEAM statement should be set to the name of a file wherethe results of the ray trace are to be stored LUMINOUS3D also has an option to cause all metal regions to act as perfect reflectors This option is enabled by specifying METAL REFLECT on the BEAM statement Finally LUMINOUS3D allows the user to simulate periodicity with respect to ray tracing by specifying PERIODIC on the BEAM statement This causes rays exiting the sides of the device perpendicular to the x z plane to re enter the opposite side of the device SILVACO International 11 11 ATLAS User s Manual Volume 2 Numerical Methods for 3D DC Solutions There are several differences between the default numerical methods applied in 2D ATLAS and thos applied in 3D ATLAS Firstly with respect to non linear iteration strategies the current version of the 3D simulatior does not support the BLOCK method The NEWTON and GUMMEL iteration strategies are supported for 3D simulations whereas NEWTON GUMMEL and BLOCK are all supported for 2D simulations In solving the linear subproblem the default approach in 3D is to use an iterative solver This is believed to be the most computationally efficient method for general 3D problems In 2D the direct solver is
366. used by default The user may find it desirable to use direct methods in 3D problems due to improved convergence of computational efficiency He may select the direct method by specifying DIRECT on the METHOD statement Also in 3D there are two linear iterative solution methods available The default is ILUCGS incomplete lower upper decomposition conjugate gradient system and BICGST bi conjugate gradient stabilized Historically tests have shown that the current implementation of 1LUcGs is slightly more stable that BICGST and it is the default iterative solver in 3D The BICGST solver can be specified by the user by specifying BICGST on the METHOD statement Transient Solutions In transient mode a semi implicit scheme is used in addition to the default TR BDF algorithm This algorithm is recommended for complex simulations such as Single Event Upset To select this method use METHOD HALFIMPL Obtaining Solutions In 3D ATLAS3D programs can perform DC and transient analysis in an equivalent manner to 2D The SOLVE statement is used to define the solution procedure The syntax used is exactly as that documented in the Getting Started chapter Interpreting the Results From 3D The Log files produced by 3D ATLAS can be plotted TONYPLOT exactly as those that result from S PISCES or BLAZE The only difference is the units of the currents produced Log files from 3D simulations save current in Amperes whereas the 2D
367. ve refractive Index ttt tt oat j Eigen 5 QNEM c MMOL Eigen Values wae 9 1 Einstein relationship senes 3 3 HeterojunC ONS Electrode VIDEAR MCN Hole Injection Electron Affinity a Hot Carrier Injection Mode Hot Electron Injection ELIMINATE HotHole Injectiofi ipn Fonti nro eR aces Emission Rates Energy Balance 2 22 2 28 3 4 3 17 3 19 3 30 3 56 4 4 4 6 4 9 5 17 15 99 Energy Dependent Mobilities IG BT ien Energy totg Mas nus Tug impact ionization rea 3 incomplete ionization eene 3 9 15 98 ETOR eat aaraa InGaASP Lt 5 22 Se Initial GUESS RE 2 32 14 15 15 133 Examples anran TEE 5 22 Insulating contacts 5 in nn itat 3 27 Interactive Mode Fast Fourier 15 34 Interface s F rmi DITaC iioi ione Interface Charges asse c eco dn odas Fermi Dirac carrier statistics Interface Trapped Charge QUE co D d Run Interface Eloatirig C Ortacls rtu 2 18 3 26 Intrinsic Ca
368. ved to the files OUT1 OUTA OUTB OUTC OUTD and OUTE The initial approximation for each bias point is obtained directly from the preceding solution For bias points 4 5 and 6 the program will use PROJ to obtain an initial approximation Since starting with bias point 4 both of its preceding solutions bias points 2 and 3 only had the same electrode bias number 1 altered SOLVE Vdrain 5 Vsub 5 OUTF OUT1 SOLVE Vgate 1 VSTEP 1 VFINAL 5 NAME gate OUTF OUTA Transient Simulation Example The following sequence is an example of a time dependent solution The METHOD statement specifies second order discretization automatic time step selection and an automated Newton Richardson procedure 15 136 SILVACO International SOLVE Statement Statements The first SOLVE statement then computes the solution for a device with 1V on the base electrode and 2V on the collector in steady state The second SOLVE statement specifies that the base electrode is to be ramped to 2V over a period of 10 ns and is left on until 25 ns Each solution is written to a file The name of the file is incremented in a manner similar to that described for a DC simulation UP1 UP2 etc Note that an initial time step had to be specified in this statement The third SOLVE statement ramps ther base down from 2V to 0 5V in 20 ns end of ramp is at 45 ns The device is then solved at this bias for another 55 ns out to 100 ns Each solu
369. where near and far field patterns are written for LASER The near field pattern file is appended with the string nfp and the far field pattern file is appended with the string Basic Save Example SOLVE V1 5 SAVE OUTF datal str is equivalent to SOLVE V1 5 OUTF datal str MASTER Example with User defined Output In the second example the SAVE and OUTPUT commands are used to produce two output files for the same bias The OUTPUT statement selects which data will be stored in each file The first file datal str contains the default contents total electric field and components of electron velocity The second file data2 str contains components of hole velocity and band edge potentials Note that the EX VELO and VELO parameters are used to prevent electron velocity components from being stored in file data2 OUTPUT E FIELD EX VELO EY VELO SILVACO International 15 123 ATLAS User s Manual Volume 2 SAVE Statement SAVE OUTF datal str OUTPUT HX VELO HY VELO CON BAND VAL BAND EX VELO EY VELO SAVE OUTF data2 str Note Contents of the saved file can be customised using the OUTPUT statement 15 124 SILVACO International SINGLEEVENTUPSET Statement Statements SINGLEEVENTUPSET SINGLEEVENTUP SET specifies the values of parameters used in Single Event Upset modeling in DEVI CE 3D or BLAZE 3D
370. x MAX LEVEL 2 In both cases two levels of refinement are performed The first example is recommended because new doping information is introduced at each level of refinement This produces better refinement criterion and fewer triangles Potential Regrid Example Next an initial solution is produced and triangeles which exhibit large potential steps are refined SOLVE INI REGRID POTENTIAL RATIO 0 2 OUTF grid3 str SMOOTH 4 Re initializing after regrid example Often it is necessary to re solve the same bias point after a REGRID using the following style of syntax SOLVE VDRAIN 3 0 REGRID POTENTIAL RATIO 0 25 SMOOTH 4 OUTF mygrid str SOLVE PREV Occasionally it is necessary to quit and restart ATLAS with the new mesh This is done using syntax such as SOLVE VDRAIN 3 0 REGRID POTENTIAL RATIO 0 25 SMOOTH 4 OUTF mygrid str go atlas MESH INF mygrid str After this MESH statement all models material parameters and numerical methods have to be respecified before any SOLVE statement SILVACO International 15 121 ATLAS User s Manual Volume 2 REGRID Statement SET The SET statement is used to define variables for substitution into ATLAS syntax SET commands are executed by DECKBUILD Note Full documentation of the SET statement is in the VWF INTERACTIVE TOOLS MANUAL VOLUME ONE Numeric Variable Example Define a numerical variable Use
371. x coordinate in the source beam coordinate system for ray tracing in LUMINOUS3D see figure 11 3 X ORIGIN specifies the x coordinate of the optical beam origin see Figures 15 1 and 11 1 The beam must originate outside all device regions Y ORIGIN specifies the y coordinate of the optical beam origin see Figures 15 1 and 11 1 The beam must originate outside all device regions ZMAX specifies the maximum z coordinate in the source beam coordinate system for ray tracing in LUMINOUS3D see figure 11 1 ZMIN specifies the minimum z coordinate in the source beam coordinate system for ray tracing in LUMINOUS3D see figure 11 1 Z ORIGIN specifies the z coordinate of the optical beam origin see Figure 11 1 The beam must originate outside all device regions LUMINOUS3D only Monochromatic Beam Example This beam has a monochromatic spectrum with a wavelength of 0 6 um The beam originates at 0 5 and y 2 0 It has a 90 degree propogation angle and a beam width of 0 2 um which is centered at the beam origin During the ray trace calculation the rays will be terminated when the power level along the ray falls to 5 of the original power BEAM NUM 1 WAVELENGTH 0 6 0 5 Y 2 0 ANG 90 0 MIN 0 1 0 1 MIN POWER 0 05 Multispectral Beam Example A multispectral beam at a 45 degree angle which originates at x 0 0 and y 1 0 The multi spectral source is imported from the spectrum file source spc The
372. y improving the mesh or checking the model and method combinations The Getting Started Chapter has useful hints The default convergence criteria used in ATLAS consists of a combination of relative and absolute values The program will converge if either criterion is met This is particularly useful when low carrier concentrations would not converge using just relative criteria Current convergence criteria are also used Terminal currents are monitored at each iteration and overall convergence is allowed if currents converge along with absolute potential error CR TOL specifies an absolute tolerance for the continuity equation CX TOL or C TOL is the relative tolerance for the continuity equation The XNORM parameter uses parameters CX TOL and PX TOL to calculate convergence criteria HCIR TOL is the absolute current convergence criteria for energy transport models HCIX TOL is the relative current convergence criteria for energy transport models IR TOL specifies absolute current convergence criteria IX TOL specifies relative current convergence criteria PR TOL specifies an absolute tolerance for the Poisson equation PX TOL is the relative tolerance for the potential equation The XNORM parameter uses parameters CX TOL and PX TOL to calculate convergence criteria RHSNORM specifies that only absolute errors will be used to determine convergence If RHSNORM is selected Poisson error are measured in C um and the continuity error is measu
373. yntax LX MESH NODE lt n gt LOCATION lt n gt Parameter Type Default Units LOCATION Real um NODE Integer Description NODE specifies the mesh line index These mesh lines are assigned consecutively LOCATION specifies the location of the grid line LASER Mesh Example This syntax defines a mesh of 33x33 covering the area bounded by 0 3 0 0 to 2 4 1 0 LX M n 1 1 0 3 LX M n 33 1 2 4 n 1 1 0 0 33 1 1 0 Note The mesh defined these statements for the LASER Helmholtz Solver is entirely separate from the electrical device simulation mesh defined on the ESH statement 15 52 SILVACO International MATERIAL Statement Statements MATERIAL MATERIAL associates physical parameters with materials in the mesh The parameter default values for standard semiconductors are shown in Appendix B Syntax MATERIAL lt localization gt Parameter AFFINITY ALIGN ALPHAA ALPHAR ARICHN ARICHP ASYMMETRY AUGN AUGP AUGKN AUGKP BGN C BGN N BGN DEVICE EAB EDB EG300 EGALPHA EGBETA ETRAP EPSINF F ALPHAA F TAUN Type Real Real Real Real Real Real Real Real Real Num Num Real Real Real Real Character Real Real Real Real Real Real Real Character Character material definition Default se
374. zation syntax uses the parameter IONIZ to enable the ionization integral calculation An equipotential contour is calculated at a potential DELTAV from the contact NAME or INAME Hlectric field lines are started at distances along this potential contour IONLINES sets the number of lines and LRATIO is the ratio of the distance between the starting points of the lines The following syntax is for a PMOS transistor See the on line examples for other cases using ionization integrals IMPACT SELB METHOD CARR 0 SOLVE VDRAIN 1 VST Gl P 1 VFINAL 20 0 IONIZ IONLINES 50 LRATIO 0 9 DELTAV 1 2 NAME DRAIN Note There are over 300 on line examples supplied with ATLAS to provide examples of sequences of SOLVE statements applied to practical problems for a variety of device technologies 15 138 SILVACO International SPREAD Statement Statements SPREAD SPREAD distorts rectangular grids defined by ATLAS in the vertical direction to follow surface and junction contours Note The use of this parameter is not recommended by SILVACO Syntax SPREAD LEFT RIGHT WIDTH lt r gt UPPER lt i gt LOWER lt i gt Y LOWER THICKNESS lt options gt Parameter Type Default Units ENCROACH Real 1 0 GRADING Real 42 20 GR1 Real 120 GR2 Real 1550 LEFT Logical False LOWER Integer MIDDLE Integer Halfway between UPPER and LOWER RIGHT Logi

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