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1. PACIFIC NANOTECHNOLOGY advancing nanotechnology PACIFIC NANOTECHNOLOGY PRODUCT WARRANTY COVERAGE Pacific Nanotechnology warrants that products manufactured by Pacific Nanotechnology will be free of defects in materials and workmanship for one year from the date of shipment The product warranty provides for all parts excluding consumables and maintenance items labor and software upgrades Instruments parts and accessories not manufactured by Pacific Nanotechnology may be warranted by Pacific Nan otechnology for the specific items and periods expressed in writing on published price lists or quotes However all such warranties extended by Pacific Nanotechnology for those specific items and periods expressed in writing on published price lists or quotes are limited in accordance with all the conditions terms and other requirements not ed in this warranty Pacific Nanotechnology makes no warranty whatsoever concerning products or accessories not of its manufacture except as noted Customers outside the United States and Canada should contact their local Pacific Nanotechnology representative for warranty information that applies to their locales CUSTOMER RESPONSIBILITIES e Complete ordinary maintenance and adjustments as stated in Pacific Nanotechnology manuals e Use only Pacific Nanotechnology replacement parts e Use only Pacific Nanotechnology approved consumables such as filters lamps cantilevers etc
2. Figure 3 6 Calibration routine complete r q 6 Select Align Frequency Tip Scan Image Tip aes Sec ID co a Sweep gt Sage gt Approach gt Sample gt Processing gt Retract El gt 9 Click Select Mode on the toolbar select Close Contact and click OK Select Mode Mode Contact Close Contact Figure 3 7 Select mode 10 If the PNI AFM reference is already loaded on the sample puck skip ahead to page 45 to load a probe or to page 52 if a contact probe is already loaded Revision 1 1 Nano R AFM User s Manual 43 LOAD A SAMPLE r ib Fea Align Frequency al ose Tip Scan Image Sar Mode Saa m o a Sweep aye m Approach Sample Processing Retract 1 Click Tip Retract from the EZMode toolbar 2 Click Stage from the EZMode toolbar 3 Click mi to raise the Z motor until there is at least a few millimeters of clearance between the probe and the sample surface monitor by eye a AFM Stage Controls FOCUS OOM 2 1 Step Load Sample um b m m me m 152 4 Change Tip OUT D E re X 115 658 53 um El mm ls Y 15 810 97 um ME Y 14 9 um Focus Step Position 11 069 78 um Figure 3 8 Raise the probe tip away from the sample ANANS CAUTION To prevent damage to your scanner probe and sample be sure you have retracted e J gt the tip and raised the Z scanner as described in the preceding steps before moving the puck 4 Click Load Sample E The motorized
3. The probe may not have been installed properly Repeat the probe installation procedure to make sure the probe is seated squarely in the L mount page 51 adjust screws e The objective s field of view may need to be adjusted in X Y using the adjust screws This is usually necessary when switching between a contact and close contact probe due to the difference in size You can confirm that you have installed a contact cantilever by noting the differ ence in length between contact and close contact cantilevers as shown in Figure 3 25 saanee S eauauuaws 400000945 S eeaeueaitiinzsaeaus 16D unn nana non nan AUD asas ass unn nn naaa t o a XP close contact cantilever contact cantilever Figure 3 23 Contact vs close contact probes 3 Click Scan Sample from the toolbar and make sure l the Setpoint value in the Feedback Controls box is 0 Setpoint 0 4 Click Align on the EZMode toolbar Laser 5 Turn on the laser The red dot alignment procedure has 3 goals e position the laser spot on the back of the cantilever e position the photodetector in the center of the reflected laser beam e achieve a minimum overall measured signal strength Revision 1 1 54 Chapter 3 Tutorial Close Contact EZMode 6 Watch the video monitor as you adjust the laser alignment knobs on the scanner head to bring the laser spot onto the back of the cantilever The laser spot should be cen
4. HM Range 3 gt mi e Auto ad Offset 7337 mW e Auto a P tse 6168 mv Figure 2 33 Line scan settings Revision 1 1 Nano R AFM User s Manual 6 Click LA to take a scan s Scan Image 19 31 um 38 63 um 0 00 um 19 31 um 38 63 um Z SEN gt e Forward Reverse V Histogram correction V Auto leveling Scanner Controls Scan Size um 39 52 _ 19 31 um 38 63 um Scan Rate Hz 2 Resolution 256 Scan Angle p Y DERE Acq Channels 4 H ESA Extra Zoom nO ene Topography Gain 1x 4x 19 31 um 38 63 um Z ERR Forward Reverse V Histogram correction V Auto leveling il H 7 Shading H I Shading Line 256 256 Line 256 Feedback Controls 163 48 nm Setpoint 0 Gain E Proportional ih 0 p 3862 0 00 nm Integral fig 0 38 63 um 0 38 63 um Derivative ho Full Z SEN y HalfRange 116 mV Full Z ERR y HalfRange 2m mv ES Figure 2 34 Taking a scan The images of the selected channels will build up line by line in the displays If no data is generated the detector may be out of alignment In this case click the HH button click Tip Retract from the toolbar re align the red dot page 23 and try another scan e Toadjust the Z scale of the images left click and drag in the bar to the left of each display to select a Z height range e To view a single line scan hold down
5. a a on r r Pr s Suuueuwstvueeweeeeeeaeen eee reese eeeee i rr BOND NUNMAAO LEC POC CR REE SES TECH C ECR SSeS AAA AEREOS TIE Teer TTT errr re BURRS eeeuueee aw wo E Figure 2 29 Positioning the probe over the scan area If necessary you can orient the sample by simply rotating the puck by hand Revision 1 1 28 Chapter 2 Tutorial Contact EZMode 4 Focus on the cantilever ope CAUTION Be careful not to drive the probe all the way into the sample surface 5 While carefully monitoring the probe sample distance by eye use the yo button to lower the Z scanner until the probe is about 1 2 mm above the sample surface 6 Focus on the sample surface and make sure the probe is positioned somewhere near the center of the pattern 7 Click the Tip Approach button on the toolbar C _ __ Select Ali F Ti 5 l Ti stare m Saee mp Lagar S pl staae A apriac MED sano E prerccciny ED koae 8 Click OK when the tip approach is complete 2 XL CAUTION Once the tip approach is complete and the tip is in contact with the sample surface 3 Z do not exit the SPM Cockpit software or turn off the Controller without first retracting the tip Doing so may cause damage to the tip scanner and sample PIL Lai Figure 2 30 Tip approach confirmation The PID indicator at the bottom of the window will turn green to indicate that the probe tip is in contact with the sample surface
6. e Provide safe and adequate working space for servicing of the products by Pacific Nanotechnology personnel REPLACEMENTS AND REPAIRS e Any product part or assembly returned to Pacific Nanotechnology for examination or repair must have prior approval e It must be identified by a Return Materials Authorization or RMA number obtained from Pacific Nanotechnol ogy prior to shipment e It must be returned freight prepaid to the designated address by the customer e Return freight costs will be prepaid by Pacific Nanotechnology if the product part or assembly is defective and under warranty e Pacific Nanotechnology will either replace or repair defective instruments or parts at its option e Repair and replacement of instruments or parts does not extend the time of the original warranty e Replacement parts or products used on instruments out of warranty are themselves warranted free of defects in materials and workmanship for 90 days with the exception of consumables such as filters lamps cantile vers etc WARRANTY LIMITATIONS This warranty does not cover 1 Any loss damage and or product malfunction caused by shipping or storage accident abuse alteration mis use or use of user supplied software hardware replacement parts or consumables other than those specified by Pacific Nanotechnology 2 Parts and accessories that are expendable and replaceable in the course of normal operation 3 Products not properly plac
7. Left button Right button Activate Trackball The sample should be mounted so that it is stable and relatively flat The magnet at the center of the puck is a convenient way to stabilize the sample Double sided tape is another method Revision 1 1 85 86 Chapter 5 X Pert Mode 8 More SCANNING Revision 1 1 magnet The height of the sample puck can be adjusted to accommodate samples of varying heights The puck is composed of 5 layers each measuring 1 4 in height Therefore if your sample is taller than 1 4 you should remove one layer for each 1 4 of height in your sample SCrews Figure 5 4 Sample puck Use a 1 16 Allen wrench to loosen one of the screws on the top of the puck Loosen it only until you feel some resistance then loosen the other screw com pletely Finally finish loosening the first screw and remove the puck layer To add a layer tighten the screws in the same way The button on the X Pert Mode toolbar opens the Scan image window While this is the same window used in EZMode this section provides additional details about the meaning of the various settings Scan Size The maximum scan area that your instrument s scanner can accurately scan is au tomatically entered in the Scan Size field each time the calibration routine is per formed Nano R AFM User s Manual 87 Scan Rate scanner Controls As a general rule the slower the scan rate the Scan Size um 33
8. above the sample puck 3 Use the X Y stage controls to navigate to the largest of the four patterns on the PNI AFM reference 10 um squares 20 um pitch Revision 1 1 Nano R AFM User s Manual 27 Increase or decrease the X Y step size as desired to facilitate both coarse and fine movements s AFM Stage Controls Sel FOCUS 700M A AY sli Load Sample i 152 4 sl Change Tip OUT I a i lt a A 15 658 53 um ET et Ey 15 810 97 um qg ido Focus Step de z AE SE Z Position 11 069 78 um Figure 2 28 X Y stage controls PPCPEPEDAROES A on q rere ree eee eee Seen we Y i s PEPPERS 000m7 a ToT T SCR See eee EHHE 10 um squares 20 pitch AAA AAA EEES ere eereeeeeeee a as Y 1 Y D SiS Y Y TTTTTTTTTTT TP CCE EERE Ae MAESE TE EEEE O664 666666646 CEE RHOO Oe AAA EA BALLLLLLLL LL 6666646660006 eUeeauanuuaakvee 6666 eb ee ee eee bbb eeseceeeceee annnunnuas iow l Br o o o e o 4 ana am Lorrro oo o e o s S8eeneen r or r eirrsrrrrsr9 nn0n M40 IAINMODOAOONQA eee eee ee eeeee CTC C SSeS eee SBuenrpeneewenuarhAi saeeeue m EAEPPEAIEALALI L a Serre r rr err seueen A LEGAL A 6666 6664645545 saanue y LELLALLLALI ee d E 666 b6bbebeeee n n un 1 l Cee eee ee Hees be seeeeeeeee i 4 64o000 011100045 IM Len o o s arar 4444090374 EEEE ES 3 Lao r onooo UL OO 44W4u n
9. FReSOMMON idas a ld dea eae eee XXVil Probe Surface Interactions civic adan XXVii AFM Imaging Modes 000 eee eee eee eee xxviii Chapter 1 Instrument Overview Nano R AFM Instrument System 2 2 0 0 00 0 1 Hardware Components nanan aaa aaa 2 NaNO R Slade ia da a td da E 2 AFM Scanner Meadas odres anida ada ores 3 AFMIPODO Suera A A Aree adem ardid e 5 Sample PUCK ses e e e ee eae 6 PIN TRCIONCNGS ida be a beret Ol eddy ha 7 SOWA e Modules siria 8 ACQUISIWO arado a ee pees ote eae ee ee 9 ARIY SIS dc o desma AR Ai dico oe id S 10 Basic Imaging Procedure 00 10 Revision 1 1 vill Revision 1 1 Chapter 2 Tutorial Contact EZMode BeIOke YOU DCOIN st wee rad de aid od tad de eee he ee oe ee de Powering Up the System 2 0 ce eee SOMWare SC UDan oooh Sees osa tee ened eb oad A Sames era Ae casado ds stalla PrODO es 05 gus creativa ee o de ora Alon TNC Detector ajos aia id iii aid Approaching the Sample o ooocooococococoo eee SCanine Sample 2 303 ita eae etek acs Mage Proces SNG asalta ba a eo aa ee ee Chapter 3 Tutorial Close Contact EZMode BOr VOU BCCI ses ai A ee ies ee SE Powering Up the Systent 2 2 vti0 2 40d Peo hdwldae eo dG RES Eee ewe ees Sotware SCD ice pd a eee ewes sees Lada Samples amp donee Awe dae ee aie lt b a eee ES TVS UAL SEA PODO ide nig ia ica aiii civic ANO the Detti gt ise eae A A ee AA Frequency West Approaching the Sample
10. Place the probe onto the magnetic mount so the side of the substrate opposite the cantilever fits into the L Figure 3 20 Mounting the probe d Use the tweezers to push the substrate flush against the L as shown in Figure 3 21 Figure 3 21 Push the probe substrate flush against the L mount 12 Hold the scanner head by the handles and rotate it back to the level position Revision 1 1 52 Chapter 3 Tutorial Close Contact EZMode 13 Gently slide the scanner back towards the stage until you feel some resistance 14 Turn the probe exchange knobs up 1 4 turn to lock the scanner head into place Now you can replace the sample puck as described above page 44 ALIGN THE DETECTOR Select r q Align Frequency Stage m Tip Scan m Image mi Tip Laser Sweep Approach Sample Processing Retract C El e e san Mode 1 Click Stage from the EZMode toolbar 2 Use the focus controls to bring the probe tip into focus on the video monitor AFM Stage Controls 2 1 Step Load Sample 1524 um gt Change Tip X 115 658 53 um Y 15 810 97 um Position i 11 069 78 um Figure 3 22 Focus controls Focus controls Click to adjust the focus a single step or hold it down for continuous motion Click to initiate a large continuous movement of pre set duration 0 Revision 1 1 Nano R AFM User s Manual 53 If you cannot find the probe on the monitor
11. and the instrument is now ready to perform a scan Revision 1 1 SCAN THE SAMPLE 1 Click the Scan Sample button on the toolbar Nano R AFM User s Manual 29 C Start Select Align Frequency Stage Es Tip gt Scan m Image a Tip E i Mode Laser SWEER Approach 7 Sample Processing Retract Scan Image 19 31 um 38 63 um 19 31 um 38 63 um 0 00 um 0 00 um 12 025 19 31 um 19 31 um 38 63 um 38 63 um Z SEN gt Forward C Reverse ge 24 Histogram correction V Auto leveling 7 4 T Shading Z ERR gt e Forward Reverse e Histogram correction V Auto leveling H Shading 3 761 42 nr 6168 10000 0 00 nm 6165 0 38 63 um 0 38 63 um Full ZISEN y Half Range 2669 mv Full ZERR y Half Range 3 m I Auto Auto leveling V Offset 7331 mv Y Auto Offset 6168 mv Figure 2 31 Scan image window 2 Set the scanner controls as follows Scan Size leave as is Scan Rage 2 Hz e Resolution 256 Scan Angle 0 e Acq Channels 4 e Topography Gain 1x The default scan size which is entered by the system when the calibration routine is performed is the maximum scan area for your scanner Scanner Controls Scan Size um 39 52 Scan Rate Hz la Resolution 256 pe Scan Angle fo ad D a 10 270 Acq Channels 4 Zoom Extra zoom Tip Force Approach Curve Topography Gain a 1xC 4
12. 1 24 Chapter 2 Tutorial Contact EZMode AFM Stage Controls 2 1 Step Load Sample i524 um i l Change Tip BAB Y 115 810 97 um ME e 149 Elm Focus Ste a A Eels Ela a ap Position y a Or A of i 11 069 78 um Figure 2 24 Focus controls If you cannot find the probe on the monitor The probe may not have been installed properly Repeat the probe installation procedure to make sure the probe is seated squarely in the L mount page 17 adjust screws e The objective s field of view may need to be adjusted in X Y using the adjust screws This is usually necessary when switching between a contact and close contact probe due to the difference in size You can confirm that you have installed a contact cantilever by noting the differ ence in length between contact and close contact cantilevers as shown in Figure 2 25 Revision 1 1 Nano R AFM User s Manual close contact cantilever contact cantilever Figure 2 25 Contact vs close contact probes 3 Click ul on the toolbar 4 Turn on the laser The red dot alignment procedure has 3 goals e position the laser spot on the back of the cantilever e position the photodetector in the center of the reflected laser beam e achieve a minimum overall measured signal strength 5 Watch the video monitor as you adjust the laser alignment knobs on the scanner head to bring the laser spot onto the back of the cantilev
13. AE AURA eas Pee PARRA mse e s a s AA a e a a aa a PRA range 1160 16 nm range 0 00 nm Select Correction Model Select Area to Analyze SS a C 3 Paoint Plane Correction eee sural I EP MAREE I u i Esla Include Area g Rectangle gt 5 Average data inthe proximity of fo pixels f Exclude Area o E E Correction Scope le Correct All a Keep original data in excluded area C Polynormial surface X leveling C Assign mean value to excluded area C Polynormial surface Y gt a See f Polynomial X line levellin Do not change Z offset f Polynomial Y line levelling ps C Subtract plane offset Polinomial orde ge 1 C Set Minimum Z to zero e 1 i s wu P Apply Done Clear Markers Update 1S ee e 7 Cancel C Polynomial surface levelling C Polynomial surface X Y levelling Figure 2 39 Plane leveling tool a Under Select Correction Model select e Polynomial X line leveling e Polynomial order 1 b Under Select Area to Analyze select e Exclude Area e Area marker Rectangle Revision 1 1 36 Chapter 2 Tutorial Contact EZMode c To exclude the features on the PNI AFM reference use the mouse to left click and drag in the image display so that every feature both whole and partial is completely covered d Click Apply and the leveled image appears in the right hand display A RA a ee A al al ERA AAA A aes de on r
14. Chapter 2 and Chapter 3 NANO R AFM INSTRUMENT SYSTEM computer monitor video microscope monitor Nano R Master Controller AFM stage Computer AFM control trackball electronics AFM scanner amp probe Figure 1 1 Block diagram of Nano R instrument system Revision 1 1 2 Chapter 1 Instrument Overview Nano R Stage Includes the AFM scanner probe sample puck video optical microscope and the AFM scanner s real time calibration sensors Master Computer The IBM PC type computer is the virtual interface to the Nano R AFM stage Pacific Nanotechnology software programs resident on the computer s hard disk are used for measuring visualization and analysis of AFM images Nano R stage Controller Contains most of the electronics required for operating the Nano R stage It is connected to the Master Computer by a standard Ethernet cable and to the Nano R stage by five cables Video Monitor Displays the optical microscope image of the probe sample area In some cases the computer monitor may be used as the video monitor Track ball Provides an optional way to activate Controller many of the motorized features of the Nano R stage including the X Y stage positioning and the video microscope zoom and focus HARDWARE COMPONENTS NANO R STAGE Revision 1 1 The AFM scanner head rests on three motorized posts which are used to perform a coarse Z approach of the probe
15. Chapter 3 Tutorial Close Contact EZMode c To exclude the features on the PNI AFM reference use the mouse to left click and drag in the image display so that every feature both whole and partial is completely covered d Click Apply and the leveled image appears in the right hand display A RA a ee A al al ERA AAA A aes de on range 1160 16 nm range 260 41 nm Select Correction Model pselect Area to Analyze Entire Scan Area Area marker C 3 Paoint Plane Correction Include Area Rectangle l Average data inthe proximity of f Exclude Area Correction Scope C Polynomial surface levelling Correct All C Polynomial surface X Y levelling Keep original data in excluded area Polynormial surface X leveling Assign mean value to excluded area O Polynormial surface Y leveling F Offset f Polynomial X line levelling Do not change Z offset C Polynomial Y line levelling C Subtract plane offset Polinomial order a Clear Markers Update Set Minimum Z to zero Figure 3 43 Leveled image right Revision 1 1 5 Click Py to open the line profile tool Profile Mode O l Profiles 19 31 um 19 31 um Figure 3 44 Line profile tool a b f Horizontal sa Vertical Oblique Clear Polygonal Circular Average Display Mode I
16. X Y stage will move the puck towards you to the limit of its range 5 Being careful not to touch the probe slide the sample puck towards you and lift it up out of the groove Revision 1 1 44 Chapter 3 Tutorial Close Contact EZMode 6 Use tweezers to mount the PNI AFM reference on the center of the puck The sample disk is held in place magnetically 7 Replace the puck on the stage by setting it down so the protruding piece on the bottom fits into the wide part of the groove and then slide it into position groove Figure 3 9 Fitthe sample puck into the groove on the X Y stage 8 Rotate the puck so that the PNI reference sample is square with the scanner head 9 Select Tools Nanok Stage to open the AFM Stage Controls window AFM Stage Controls Z MOTORS Fp m mm E E E E Run to the TOP rF 2 1 Center Position Set en a A RERI sz z Position am 0 00 um TRANSLATE XY LIGHT Load Sample X Y Step 0 On Change Tip_ 21 3 Jum OR F m Center Postion gt p Xy OPTICS X position 1 00 um z Or PE FOCUS ZOOM He Y position 00 um T U MN h Cl ector Translation Angle Translation Xfi7o73 jm foco pm gt NS Y fiea02 Sum 45 00 Hea 0 00 deg is X Forward Small Step Activate Trackball TOF Move XY__ Move Angle 64 6 um IV Log Position Offset a Figure 3 10 Return sampl
17. a new value you must click gt gt to apply it Nano R AFM User s Manual 17 Force Distance Curve A ae A stepper motor E Z ERR 7 Current position E m m mom r Pee a EES z 1 vertical travel Offset 2 ad my D asic 1298 D 5285 40 UM E OR A 4t curve Start End y Number of end curve End Start 65535 1 2 steps 10000m i Force Units Start Stop Sel Markers to minimax En Int L Marker 1 Marker 2 Start lo Ei on Z DAC End HH o000 aan on DAC en Force Calibration x Lo 728 79 6 237 24 NM full scale z ia 984 00 hm ond 0 00 m nz Io fm l fm Y 214 00 156 12 nit 2 492 21 nh Deflection Limit E E e Rate ons pix gt Distance x L nimi F A f J P 2000 m on Z ERR eevee spring Constant or command to not exceed the above Y _57 88 nt i 02 APR fi Time p curve value of Z ERR signal 10 Slope dy dx nhim Ma i al Measure the average of Pale pulse ehai Pixels 128 y h curve s 0 132 omni gt gt f 605 minim Note Z DAC 0 m Mote lt OAL U r ig fully RETRACTED 1 fully EXTENDED 4stcurve 2nd curve Figure 4 7 Force distance curve settings 7 Click Start to generate a force distance curve The first curve displayed in green represents the deflection of the cantile ver as it approaches the sample surface The second curve displayed in red represents the retraction of the cantilev
18. a straight edge to measure orthogonal lines in the image The lines drawn on the test pattern image in Figure A 18 show no measurable cross talk between the X and the Y axis E 11 20 30 40 um Hm T LESS PET 5 EBS BEBE ESOO Bias le sau ee eE 0 2 15 VLESDODOSO O 0 18 Ta VA 0 16 x LESA 0 14 5 25 pe 0 12 30 Leon o nss Se See ee 8 8 l 0 08 LESA 0 06 40 DOGO 0 04 EEEE E e 46 Se BSB BBs A um Figure A 18 AFM image of a test pattern with lines drawn to measure any error in orthogonality Z ANGLE MEASUREMENTS Mechanical coupling between the piezoelectric ceramics that move the probe in the Z direction and those that move the probe in the X or Y directions can cause substantial errors when trying to measure side wall angles This error can best be measured with a sample that has repeating triangular structures as illustrated in Figure A 19 and Figure A 20 A NA N A NA N line profile Figure A 19 Asymmetry caused by mechanical coupling between Z and X or Y piezoelectric ceramics Revision 1 1 0 0 4 0 MM Bb 0 NY O o T 3 Nano R AFM User s Manual 103 8 10 um um um Length 10 456 ym Pt 1 8728 ym Scale 2 pm 0 2 0 1 2 3 4 5 6 7 3 9 10 ym Figure A 20 AFM image of a sample with a repeating triangle pattern and the extracted line profile IMAGE PROCESSING LEVELING This section presents some of the common artifacts that can be introduced into AFM images by image processing softwar
19. are often less than a nanon ewton the probe is minimally touching the surface Figure g Contact mode AFM the probe directly follows the topography of the surface as it is scanned while a constant force is maintained Nano R AFM User s Manual XX X Vibrating Mode The cantilever in an AFM can be vibrated using a piezoelectric ceramic When the vibrating cantilever comes close to the sample surface the amplitude and phase of the vibrating cantilever may change The feedback unit keeps either the vibration amplitude or phase constant Changes in the vibration amplitude or phase are easily measured and the changes can be related to the force on the surface This technique has many names including non contact and intermittent contact mode It is important that the tip not tap the surface as this may break the probe or damage the sample Paura Figure h In vibrating methods changes in probes vibrations are monitored to establish the force of the probe onto the surface Material Sensing Modes The interaction of the probe with the surface depends on the chemical and physical properties of the surface It is therefore possible to measure these inter actions and thus sense the materials at a sample surface Vibrating Material Sensing Mode The AFM cantilever may be vibrated to measure the force between the probe and sample during a scan The magnitude of amplitude damping and the amount of phase change of
20. features The line scan profile for the Z SEN channel should resemble the scale shape and size of the 10 um features adjust Revision 1 1 64 Chapter 3 Tutorial Close Contact EZMode Line 256 36 163 48 nm 3062 0 00 nm 39 63 um 0 Ful SEN Half Range 116 mv Figure 3 38 Viewing a single line scan Z SEN channel When the feedback controls are properly set the forward and reverse line scan profiles for the Z ERR channel will roughly mirror each other Line 56 212 30 63 um 0 Full ZIERR Half Range 2p pee ih Figure 3 39 Z ERR channel line profile TROUBLESHOOTING If you do not see any features it may be due to one of the following e feedback controls improperly set use the defaults e setpoint is too low increase slowly a maximum of 2 4 clicks at a time and watch for a response in the display increasing too much can break the tip or damage your sample e resonant frequency not properly set open the Frequency sweep window and perform the frequency sweep procedure again e dull probe tip replace tip e broken tip replace tip e poor mechanical coupling between the probe and scanner reseat probe Revision 1 1 Nano R AFM User s Manual 65 7 To take additional scans click again or check Repeat Scan to take continuous scans of the same region 8 To zoom to a new scan region a Left click and drag in the image display to define a scan area b Left c
21. high pass filtering the dimensions like the step in Figure A 22 can appear distorted The amount of distortion depends on the amount of filtering applied to the image Other image artifacts can appear as a sharpness at the edge of steps surface feature resulting image Figure A 22 Image distortion due to high pass filtering FOURIER FILTERING Fourier filtering can easily introduce periodic structures into images For example an image of white noise can be filtered to give periodic structure that looks like atomic structure MATRIX FILTER SMOOTHING Revision 1 1 Matrix filtering is a very effective way of smoothing images and removing noise However the filtering process often reduces the resolution As a rule of thumb if the image has no noise in it the data has probably been compromised The example in Figure A 23 shows how filtering can reduce the noise as shown in the line profiles but also cause the shape of the nanospheres to be altered 0 um Nano R AFM User s Manual 0 um 105 Profile Mode re Profile Mode ee Diff 2 4 Horizontal Horizontal gt al Pd A e Vertical Vertical z C Oblique Clear C Oblique Clear z C Polygonal C Polygonal z 121 um Circular Fom Circular Average Average Diff 4 3 Display Mode Display Mode aj IV Fit Vertical Scale IV Fit Vertical Scale z IV Fit Horizontal Scale IV Fit Horizontal Scale z Invert Z da
22. substrate and carefully rotate the tweezers so the cantilever side of the substrate lifts up off the magnetic strip first as shown in Figure 2 21 Figure 2 20 Nudge the probe into position Revision 1 1 22 Chapter 2 Tutorial Contact EZMode Figure 2 21 Lift the probe cantilever side first c Place the probe onto the magnetic mount so the side of the substrate opposite the cantilever fits into the L Laser Light nite L iT Arii Figure 2 22 Mounting the probe Revision 1 1 Nano R AFM User s Manual 23 d Use the tweezers to push the substrate flush against the L as shown in Figure 2 23 Figure 2 23 Push the probe substrate flush against the L mount 11 Hold the scanner head by the handles and rotate it back to the level position 12 Gently slide the scanner back towards the stage until you feel some resistance 13 Turn the probe exchange knobs up 1 4 turn to lock the scanner head into place Now you can replace the sample puck as described above page 16 ALIGN THE DETECTOR z D z z ston p Soge P asor SS JD stoe aportar PM sore JD processing neta 1 Click Stage from the EZMode toolbar 2 Use the focus controls to bring the probe tip into focus on the video monitor Focus controls Click Fi to adjust the focus a single step or hold it down for continuous motion Click to initiate a large continuous movement of pre set duration 0 Revision 1
23. the SHIFT key and left click in either image display to define a horizontal line across 4 nr the image make sure the line includes the square features The line scan profile for the Z SEN channel should resemble the Seale shape and size of the 10 um features adjust Revision 1 1 32 Chapter 2 Tutorial Contact EZMode Line 256 236 163 48 nm J062 0 00 nm 39 63 um 0 Fui SEN Half Range 116 mV Figure 2 35 Viewing a single line scan When the feedback controls are properly set the forward and reverse line scan profiles for the Z ERR channel will roughly mirror each other Line 256 212 30 63 um 0 Full ZIERR Half Range 2p ee ih Figure 2 36 Z ERR channel line profile 7 To take additional scans click again or check Repeat Scan to take continuous scans of the same region 8 To zoom to a new scan region a Left click and drag in the image display to define a scan area b Left click again to position the box within the scan region c Right click to confirm the new scan region Revision 1 1 Nano R AFM User s Manual 33 d Click OK to zoom to the new scan area The probe will move to the new 2 s offset 3098m Y offset 3059m oom 24 scan region where you can start anew scan Additional zoom ok l features are accessible via the Zoom and Extra Zoom buttons Zoom confirm or by simply double clicking in the display al Scan Image 139 31 um
24. the cantilever depends on the surface chemical composition and the physical properties of the surface Thus on a non homogeneous sample contrast can be observed between regions of varying mechanical or chemical composition Typically in vibrating material sensing mode if the amplitude is fixed by the feedback unit then the contrast of the material is observed by measuring phase changes This technique has many names including phase mode phase detection and force modulated microsco py Torsion Modes In contact mode AFM it is possible to monitor the torsion motions of the cantilever as it is scanned across the surface The amount of torsion of the cantilever is affected by changes in topography as well as changes in surface chemical properties If a surface is perfectly flat but has an interface between two different materials it is often possible to image the change in material properties This technique is similar to lateral force microscopy LFM Revision 1 1 xxx AFM Tutorial Revision 1 1 Figure i Torsion mode changes in the torsion of the cantilever are an indication of changes in the surface chemical composition Chapter 1 Instrument Overview WARNING Before operating the Nano R AFM make sure you are familiar with the safe ty information on page vi x EX CAUTION To prevent damage to your instrument probe and sample observe all the caution 3 A statements in the tutorial chapters
25. tip to the sample surface The sample puck rests on a motorized X Y stage for positioning the sample under the probe The puck can be easily removed for mounting a sample Nano R AFM User s Manual 3 video microscope with motorized zoom amp focus AFM scanner head motorized X Y positioning sample puck Z approach motor 1 of 3 Figure 1 2 Stage components AFM SCANNER HEAD The AFM scanner head contains the components that 1 measure the force between the probe and the sample and 2 control the precise positioning of the probe in X Y and Z The Z piezo component moves the probe vertically in response to changes sensed in the sample surface The X and Y piezos move the probe over the sample in a raster pattern which defines the scan region Revision 1 1 4 Chapter 1 Instrument Overview photodetector cantilever Figure 1 3 Light lever sensing system The Nano R AFM scanner uses a light lever design A red laser is focused on the back of the cantilever and then projected onto a quad photodiode photodetec tor Two pairs of manual adjustment knobs on the scanner head are used to align the sensing system One pair controls the position of the laser light on the backside of the cantilever the other pair moves the photodetector into the light path detector adjust knobs laser adjust knobs Figure 1 4 Adjustment knobs for laser and detector Revision 1 1 AFM PROBES EN a w kari z
26. will re scale to the new voltage range for subsequent curves Measurements can be taken as follows e Left click anywhere on the curve to measure Z height e Right click anywhere on the curve to measure the signal level Left click to grab and move the two measurement markers To take continuous measurements check the box next to the Start button Iv Start Revision 1 1 Nano R AFM User s Manual 79 Force Distance Curve 8 022 09 nm 2 396 80 nm zen y stepper motor cent AETR z Current position Half Range 2798 mi t 2 220 20 UM ial Vertical travel Offset p dm eee ES D 5 285 40 LIT GR al Number af 65535 12 steps HH Y Y E Set Markers to minimax Force Units int Marker 1 barker 2 y a Force Calibration 4 252 25 44 72 nm Full scale X Y 200 87 104228 nN 3 766 48 nh Distance x f4 207 53 nm E 4st curve Start End M 2na curve End Start SDE m e000Mm E Start Stop Start 3306 ity on Z DAC End a000 h on Z DAC 6 022 09 fim onz 2 396 80 fm onz Deflection Limit j Rele E pen E Spring Constant or Y 841 62 nh 2 Aire slope dyide lo 200 2000 me on Z ERR command to not exceed the above Time 0 26 curve value of ERR signal Measure the average of Sensitivity Pixels fi 28 f curve s 1 062 ES 1 062 minim Note DAC 10000 my lt piezo Mote DAC 0 m 2 pieza is is fully RETRACTED fully EXTENDED dstcurve 2nd curve Fig
27. 279 92 kHz below above Full Range Set Setpoint below mark at 2000 of oscillation amplitude Phase shift Sweep Rate A Tune driving amplitude to zen Y deg p 2 ma poaint obtain oscillation amplitude 1500 MY Figure 3 30 Confirm setpoint APPROACHING THE SAMPLE 1 Click Stage from the EZMode toolbar 2 Use the focus controls to bring the sample surface into focus on the video monitor x EX CAUTION Whenever you engage the motorized X Y stage be sure the probe is a safe distance o above the sample puck 3 Use the X Y stage controls to navigate to the largest of the four patterns on the PNI AFM reference 10 um squares 20 um pitch Increase or decrease the X Y step size as desired to facilitate both coarse and fine movements If necessary you can orient the sample by simply rotating the puck by hand 4 Focus on the cantilever Revision 1 1 Nano R AFM User s Manual 59 AFM Stage Controls FOCUS ZOOM PY Step LoadSample za 4 si I Change Tip O x 115 658 53 um J l TO NEL i i f 5 810 97 um 149 um Focus Step dh A En U Position 0 On w Off f 069 78 um Figure 3 31 X Y stage controls esuunpeneene 10 ums uares MAD anp EELITTTTTITT p e de SSS E ELLE NTE Sessi EELEETETTE bast anos 333 Bassas I ETETTETEETTI SiR uan Pebeees Prepa TET uvas nun H lemmvauunas etre nea ion t es amie o
28. 3 226 69 574 i 2 000 H a 3 H ML LE AN 3 UHI a a 3 ip ip a 3 Left click in the image display to select a line Left click in the line display to make measurement markers In the example above measurements are made between the edges of two consecutive features on the PNI AFM reference The measurements displayed to the right confirm a pitch of 20 um and a Z height of approximately 70 nm NOTE These measurements should not be used to calibrate your instrument Revision 1 1 38 Chapter 2 Tutorial Contact EZMode 6 Click illi to open the histogram tool and use the slider bars to mark the middle of the two ranges where the Z data points are clustered rt Histogram 2 Scan Data 7 SEN fwd Plane Correction 110 21 nm Apply Auto Done Unda Cancel Figure 2 42 Histogram tool The Z Diff measurement on the vertical bar confirms the 70 nm height of the PNI AFM reference features 7 To save any of your processed images select File gt Save Image s 8 Click to return to the acquisition module 2 EX CAUTION To prevent damage to your scanner probe and sample be sure to retract the tip gt before exiting the SPM Cockpit software or turning off the Controller 9 Click Tip Retract It is now safe to exit the SPM Cockpit software Revision 1 1 Chapter 3 39 Tutorial Close Contact EZMode BEFORE YOU BEGIN This tutorial follows the s
29. 30 63 um ER wate E 1953 um 4 on a F ish os 30 63 UM SEN ze J e Forward Reverse 200m ex jv Histogram correction wv Auto leveling 4 Shading region Figure 2 37 Selecting a zoomed in scan region 9 Toend your session now click Tip Retract on the EZMode toolbar Once the tip is retracted it is safe to turn off the Master Computer and the Controller Revision 1 1 34 Chapter 2 Tutorial Contact EZMode IMAGE PROCESSING 1 Click Image Processing on the EZMode tool bar r gt q e Align FI2Qquenty Tip scan Image Tip ia Start mp Mode oe SWEER Sage Approach Ld sample Processing m Retract 2 Click MM to open an image for processing j Pacific Nanotechnology SPM Cockpit Mode File Device Settings Tools Process Display Window Help B Select Source Image for Proce El Acquisition Direction Forward Reverse Acquisition Channel z sen Z Sensor Cancel Figure 2 38 Image processing module 3 Select the desired acquisition channel and direction for the image to be processed i 10 Scan Data Z HGT 1 E The raw image data will not resemble the image in the scan image window as some basic real time image processing was applied as it was being acquired 4 Click ed to apply a plane correction YO 400358 um Y 40 58 um 2 1160 18 nm Revision 1 1 Nano R AFM User s Manual 35 excluded areas A E o
30. 76 2 m Offset Z Setpoint 267 Y fa nm Phase shift a60 deg EA A L Start Frequency 259 92 kHz End Frequency 279 92 kHz Full Range SWEEP Rate ji T gt ma point EE olx Full Luto Tune Amplitude a E Previous E Current Close Advanced Legend 1 279 92 kHz Auto Set Set Frequency mark away from resonace at down from max amplitude e below C above Set Setpoint below mark at loo e of oscillation amplitude Tune driving amplitude to obtain oscillation amplitude f 300 mv 5 00 T Figure 3 29 Confirm the frequency and drive amplitude 10 Confirm that the frequency and amplitude values correspond to the values in the Frequency sweep window and click Yes 11 Click Yes in the Auto Setpoint Value confirmation box The system will enter the new setpoint value in the Z Setpoint field as well as in the Setpoint field in the Scan Image window Revision 1 1 58 Chapter 3 Tutorial Close Contact EZMode A Frequency sweep Autoset Setpoint Value E El x E 2 Apply new Setpoint 789 42 mi Previous Full Full Auto IS Auto m E Current Close Tune mplitude Advanced Legend 293 92 kHz 279 92 kHz Half Range Drive Amplitude Start Frequency Auto set RES rn 176 rey 259 92 al kHz Set Frequency mark away from resonace at 5 00 o Offset Setpoint End Frequency down from max amplitude 267 pm 42 H mv
31. AA 255 92 fed from resonace at Eno ae Offset Z Setpoint End Frequency down from max amplitude 27 Pa 279 92 kHz below C above Full Range Set Setpoint below mark 20 00 To of oscillation amplitude Phase shift sweep Rate Tune driving amplitude to 360 H deg fo E msfpoint obtain oscillation ampitude 1500 me Figure 3 26 Frequency sweep window 2 Set the Drive Amplitude to 100 3 Make sure the Z Setpoint is 0 4 Make sure the Auto Set values are set as follows Set Frequency mark 5 0 Set Setpoint below mark 20 0 e Tune driving amplitude to 1500 mV 5 Check the Auto option Revision 1 1 56 Chapter 3 Tutorial Close Contact EZMode 6 Click Full Auto oe Frequency SWEEP El Previous E Current Close Tune Amplitude Advanced Legend ov 209 92 kHz 273 92 kHz EI Mw ze gt m Half Range Drive Amplitude Start Frequency Auto Set atl mv l my I kH Set Frequency mark awa 342 Mm 38 m 259 92 z q Y Yy from resonace at 5 00 aL Offset Setpoint End Frequency down from max amplitude ja m 33 dmv 279 92 kHz below C above Full Range Set Setpoint below mark at 20 00 p of oscillation amplitude Phase shift Sweep Hate Tune driving amplitude to 360 eet deg ji D ps mes point obtain oscillation amplitude f 500 E Figure 3 27 Initial frequency peak 7 When the sweep is complete click Tune Amplitude ER Frequ
32. ACE FEATURES APPEAR TOO LARGE __ _ Figure A 1 AFM probe scanning over a spherical surface feature Often the size of surface features such as nanotubes and nanospheres look larger than expected In the measurement illustrated in Figure A 1 the side of the probe will cause a broadening of features in the image However the height of the feature is correct when measured by a line profile In Figure A 2 the line profile of the image shows a diameter of 92 nm and a height of 8 nm The broadening in the image is caused by the shape of the probe Z range 9 55 nm eu Profile Mode a Profiles orizonta ho y C vertical Oblique Clear C Polygonal 020 um Circular Average W Fit vertical Scale W Fit Horizontal Scale Invert Z data Level Line Profilet 0 40 um Line Roughness 3 61 nm 431 nm Figure A 2 AFM image and line profile of an 8 nm diameter sphere Scan size 400 X 400 nm Revision 1 1 Nano R AFM User s Manual 93 SUB SURFACE FEATURES APPEAR TOO SMALL When the probe measures a feature below the sample surface the size of the feature can appear too small The line profile in these cases is established by the geometry of the probe rather than the geometry of the sample For example in the measurement illustrated in Figure A 3 the width of the probe prevents it from reaching the bottom of the feature Figure A 3 AFM probe scanning over a depression in the surface topograph
33. Background BOW TIN y sensu ae oe eee deni Sees Bde ake ee 98 Z EGOE OVEIsnOOl usada a 100 ocan DMM lt uci A ees ee ah ee 101 X Y Angle Measurements 0 0c cee cee eee ees 102 Z Angle Measurements 0 00 cece eee eee ees 102 Image Processing aii dk w ivse les ook ds adie Bib ed ee ee Ae a ee 103 ESVSIMO eya St ite AO A Be ea E etre So E 103 PUGMEP ASS PINCH atar hace aha te aa ee ks we NE Necks bo Weta a 104 POUR FINGON sesse Wks te ed Ma Be eg hie ak dae ia 104 Matrix Filter Smoothing 0 000 cece eee ee ees 104 Image LOOKS TOO Odds wir rias POS oe Mae ee oe ee 105 Revision 1 1 Revision 1 1 MIDA Sora iia iii iio 106 FIOOF VIDIALIONS vada dd a ed eee ak 106 ACOUSTIC VIDIAQUONS 3 3 parada Eo 106 Other SourceS iaa e A A a 107 A AA Sic i exceed austin Galena O 107 surface Contamination lt 224c lt t4a 4eicieaidesdee dine deeds 107 VACUUM LeaKS ramae aras name a keen E oe ae 108 Xi Preface INTRODUCTION The Nano R AFM is an easy to use high performance atomic force microscope AFM While the Nano R can be operated with little or no understanding of the components of an AFM Pacific Nanotechnology recommends that those who are new to AFMs first take the time to read the AFM Tutorial on page xxi Some un derstanding of the components and theory of an AFM system will greatly facili tate your ability to get optimal results from the Nano R AFM AFM HISTORY When we think of mic
34. Computer 3 My Network File name Ear Places save as type Digital Surf sur Cancel Figure 5 5 Saving images To save every scan that 1S File Device Settings Tools Process Display Window Help taken select the Auto save Open Configuration File Ctrl 0 PIN SER scanned images option Save Configuration As CtrleS Te A Edit Configuration File Ctrl E Images will be saved in the Save Image s Save Images in Topometris format folder that was selected the Open Image Save Image s in Manozcope format last time an image Was Save raw scan data Save Image s in DigitalS urt format Open raw scan data Auto save scanned images saved Revision 1 1 90 Chapter 5 X Pert Mode amp More By default four channels are selected in the Scan image window So when an image is saved a total of eight files are saved both the forward and reverse scan data for each channel selected Acq Channels 1 If some channels are not necessary for your appli cation you may want to reduce the number of Channel 1 Z SEN z active acquisition channels in order to reduce the number of files generated To make sure the channels you are interested in are active select Set Channel 3 tings gt Input Selects to ADC and make sure these are listed as the primary channels For example if Channel 4 F DEM the Acq Channels setting in the Scan image window is set to 2 the signals designated a
35. Move 0 Angle Mowe y Figure 5 2 Advanced stage controls window Hano R Click da to access the advanced stage controls Buttons in the Translate XY box provide quick automated ways to perform the stage translations for changing the probe and sample The Load Sample button automatically moves the puck to the limit of the X Y stage range to facilitate changing the sample Once a sample has been mounted and the puck replaced you can click the Center Position button to return the puck to its original position The Change Tip button will run the Z motors to the top of their range both the scanner head and the video objective to facilitate installing a new probe The Run to the TOP button in the Z Motors box does the same thing Nano R AFM User s Manual TRANSLATE Y p Load Sample y XY Step i Change Tip 21 3 jum i Center Position Hl A f lt A _ 0 00 um al iG 0 00 um A E 0 vector Translation Angle Translation hroz hooo am Y fio fas 00 pea 0 00 deg is lt Forward Move Angle Move Y Figure 5 3 X Y Stage controls Trackball A trackball is supplied with the Nano R system as an al ternative way of accessing the motorized stage controls The trackball can be activated from the stage controls window in either EZMode stage D or X Pert Mode day ia or Tools gt NanoR Stage SAMPLE MOUNTING Trackball Stage Controls
36. Nano R AFM User s Manual 73 Topography LFM Figure 4 2 6x6 um image of composite material PHASE IMAGING Phase imaging is done in close contact mode The Z DEM channel one of the four channels available in close contact mode provides phase information This channel can be set to represent changes in either the phase or the amplitude of the cantilever vibration while holding the other constant INN CAUTION To prevent damage to your instrument probe and sample make sure you are famil e J gt iar with the caution statements in Chapter 3 Set up the Nano R to take an image in close contact mode as described in Chapter 3 FREQUENCY SWEEP When setting the resonant frequency in the Frequency Sweep e window first set the Phase Shift to 270 a den Revision 1 1 74 Chapter 4 Material Sensing Modes SCANNING Revision 1 1 Set the scanner and feedback controls as described on page 29 Select the Z SEN and Z DEM channels from the drop down menus beneath the two image displays and for each display select Forward Histogram correction and Auto leveling Select Settings gt Demod Selects Set Demodulation to Amplitude When set to Amplitude the default setting the Z DEM channel represents changes in the phase while a constant amplitude is maintained Settings fel ES scan Image Setup AY Control feedback Input Selects to ADC ZPiezo PID On Off LaseriMotors XYZ Scales Y Nonlinearty X
37. UK Patent 2 009 409 Nano R AFM User s Manual xiii In 1971 Russell Young demonstrated a non contact type of stylus profiler In his profiler called the Topographiner Young used the fact that for electrically conductive samples the electron field emission current between a sharp metal probe and a surface is very dependent on the probe sample distance In the To pographiner the probe was mounted directly on a piezoelectric ceramic used to move the probe in a vertical direction above the surface An electronic feedback circuit monitoring the electron emission was then used to drive the piezoceramic and thus keep the probe sample spacing fixed Then with piezoelectric ceramics the probe was used to scan the surface in the horizontal X Y dimensions By monitoring the X Y and Z position of the probe a 3 D image of the surface was constructed The resolution of Young s instrument was controlled by the instru ment s vibrations SCANNING TUNNELING MICROSCOPES AND ATOMIC FORCE MICROSCOPES In 1981 researchers at IBM were able to utilize the methods first demonstrated by Young to create the scanning tunneling microscope STM Bennig and Rohrer demonstrated that by controlling the vibrations of an instrument very similar to Young s Topographiner it was possible to monitor the electron tunneling current between a sharp probe and a sample Since electron tunneling is much more sensitive than field emissions the probe could be used to scan ve
38. Used for setting the scanning parameters such as scan size scan speed and feedback control response and for visualizing images captured with the microscope F Frame A solid frame supports the entire AFM instrument The frame must be very rigid in order to prevent vibrations between the tip and the surface NOTE Not shown in Figure e is an optical microscope which is essential for locating features on the sample surface and for monitoring the probe approach process TAKING IMAGES Revision 1 1 Taking an image of a sample with an AFM involves the following basic steps 1 Install a probe in the microscope and align the light lever sensing system 2 Position the region of interest on the sample directly under the AFM probe using the X Y translation stage and the optical microscope 3 Engage the Z translation stage to bring the probe to the surface 4 Start the scanning of the probe over the surface and monitor the resulting AFM image on the computer screen 5 Save the image on a computer disk RESOLUTION Nano R AFM User s Manual xxvii Traditional microscopes have only one measure of resolution the resolution in the plane of an image An AFM has two measures of resolution in the X Y plane of the measurement surface in plane resolution and in the direction perpendic ular to the surface vertical resolution In Plane Resolution The in plane resolution depends on the geometry of the probe used for scanning In ge
39. Y Frequency Synth AUX 1 amp 2 Outputs Demod Selects Demod Gain F Demod Filter f1000Hz Demodulation AMPLITUDE PHASE AMPLITUDE Ok Cancel Apply Figure 4 3 Z DEM channel settings 5 Click LA to take a scan The Z SEN and Z DEM channels were used to generate the images of the PNI AFM reference shown below While the surface of the PNI AFM refer ence is composed of a nominally homogeneous material the phase image right reveals surface contaminants 10 82 um 0 00 wm Z SEN e Forward Reverse iW Histogram correction w Auto leveling Nano R AFM User s Manual 15 10 82 um a e r AA 7 wo al ae P w zm aye y eng oF aes gt i C E an 5 IA ro TE S ert ne Ta Tir i de ode a af E e El de er T oes 7 Festi f En Pad ant ita EE 10 82 um ae BE E DEM Forward Reverse j IW Histogram correction w Auto leveling H D Shading Figure 4 4 PNI AFM reference Topography left and Phase right The following images of a sample of SBS film compare the topography Z SEN channel information with the phase Z DEM channel information Topography Figure 4 5 1 5x1 5 um image of SBS film Revision 1 1 76 Chapter 4 Material Sensing Modes Note that phase information is a convolution of several factors with contribu tions from material properties as well as topography Phase ima
40. ange 1160 16 nm range 260 41 nm Select Correction Model pselect Area to Analyze Entire Scan Area Area marker C 3 Paoint Plane Correction Include Area Rectangle l Average data inthe proximity of f Exclude Area Correction Scope C Polynomial surface levelling Correct All C Polynomial surface X Y levelling Keep original data in excluded area Polynormial surface X leveling Assign mean value to excluded area O Polynormial surface Y leveling F Offset f Polynomial X line levelling Do not change Z offset C Polynomial Y line levelling C Subtract plane offset Polinomial order a Clear Markers Update Set Minimum Z to zero Figure 2 40 Leveled image right Revision 1 1 5 Click Py to open the line profile tool Profile Mode O l Profiles 19 31 um 19 31 um Figure 2 41 a b Line profile tool f Horizontal sa Vertical Oblique Clear Polygonal Circular Average Display Mode Iv Fit Vertical Scale Fit Horizontal Scale Invert Z data E E gt Y Y HE EE la Level Line Protilefs Line Roughness 38 63 Um Under Profile Mode select Horizontal Under Display Mode e Check Fit Vertical Scale e Uncheck Invert Data c d Nano R AFM User s Manual 37 Markers Marker 1 5 623 Marker 2 d 20 301 25 974 21
41. as described below page 96 However the probe sample angle would have to be extreme to explain this artifact The artifact can be easily seen in the line profile REPEATING STRANGE PATTERNS If the surface features are much smaller than the probe it is possible to see large numbers of repeating patterns in the image The patterns will often appear as tri angles especially if silicon probes are used Figure A 7 shows AFM images of colloidal gold particles that reflect the shape of the tip rather than their own geometry Compare the AFM images of the nano spheres which should be perfect spheres with the SEM images of the tips used to take the AFM images Because the chipped tips are much larger than the nano spheres the geometry of the probes is reflected in the AFM images 03 04 05 0 6 pm nm o Ot z 03 OF S 0 6 um nm Acc Y Spot Magn Det WD Exp Hl Acc Y Spot Magn Det WD Exp 100kY30 27539x SE 34 0 1 Close Contact 4 100kY3 0 60000x SE 260 2 Close Contact 2 ant Figure A 7 AFM images of nanospheres top and SEM images of the probes used bottom Diameter of nanospheres 5 nm left and 28 nm right Scan size 700 nm X 700 nm Revision 1 1 96 Appendix A Guide to AFM Image Artifacts SCANNER ARTIFACTS The scanners in an atomic force microscope that move the probe in the X Y and Z directions are typically made from piezoelectric ceramics As electromechani cal transducers piezoelectric ceramics are capable of
42. better the feedback loop is able to track the sample topography Therefore the scan rate aa kicie a a will largely depend on how rough or smooth Resolution abi the sample is For example if the sample is very Scan Angle p bs flat scanning at a slow rate is of no benefit and if a rough sample is scanned too quickly infor 180 270 mation is likely to be lost Acq Channels 4 Zoom Extra Zoom Resolution Force This value represents the number of pixels per Sure line in the image The default setting 256 will Topography Gain 1x0 2x result in a 256x256 pixel image i e 256 line Repeat Scan E scans each consisting of 256 data points Si The scan region is a square area that can be E rotated as desired rather than having to physi cally rotate the sample Note that the scan size may be automatically reduced in the event that the rotation causes some of the scan area to extend beyond the range of your scanner s maximum range Scan Angle Zoom The zoom windows provide tools for defining and fine tuning your scan area These windows can also be accessed by double clicking in the image display Simple zooms can be accomplished by clicking and dragging in the image display to define a new scan area Topography Gain Increasing the topography gain to 2x may be useful when imaging very small features lt 5 nm This is a way of increasing the gain without losing resolution The Z HGT channel should be monitor
43. d i 10 Scan Data Z HGT E E The raw image data will not closely resem ble the image in the scan image window as some basic real time image processing was applied as it was being acquired 4 Click KA to apply a plane correction 40 36 um Y 40 58 um 1160 18 nm Revision 1 1 Nano R AFM User s Manual 67 Plane Correction 10 Scan Data Z HGT fwd excluded E i a i lt a e tl range 1160 16 nm range 0 00 nm Select Correction Model gt Select Area to Analyze mH HE EE la al Entire S Area marker C 3 Point Plane Correction a Mos I i ad Include Area g Rectangle g Average data inthe proximity of jo pixels e Exclude Area k ae Sage L Correction Scope le Correct All a Keep original data in excluded area C Polynormial surface X leveling C Assign mean value to excluded area C Polynormial surface Y gt a gt f Polynomial X line levellin Do not change Z offset f Polynomial line levelling rs Subtract plane offset Polinornial ordet g 1 Set Minimum Z to zero I P I s w V Apply Done Clear Markers Update a Cancel C Polynomial surface levelling C Polynomial surface X levelling Figure 3 42 Plane leveling tool a Under Select Correction Model select e Polynomial X line leveling e Polynomial order 1 b Under Select Area to Analyze select e Exclude Area e Area marker Rectangle Revision 1 1 68
44. d when imaging very flat samples Sometimes the vibrations can be started by an external event such as an elevator in motion a train going by or even people walking in a hallway ACOUSTIC VIBRATIONS Revision 1 1 Z range 100 82 nm Sound waves can cause artifacts in AFM images The source of the sound may be from an airplane going over the building or from the tones in a person s voice The images and line profiles in Figure A 25 illustrate the effects of noise derived from a person talking in the same room as the microscope Profile Mode Tirk Pare Profile Mode Fiai Profiles clio Profiles me Horizontal A a al Horizontal d C Vertical 3 z C Vertical i z Oblique Clear zj C Oblique Clear z C Polygonal z C Polygonal Z C Circular Circular FT Average FT Average al Display Mode Display Mode A IV Fit Vertical Scale zj IV Fit Vertical Scale zj IV Fit Horizontal Scale pon IV Fit Horizontal Scale 5 FT Invert Z data PF Invert Z data z z Level Line Profile s Level Line Profile s Line Roughness Z range 85 00 nm 7 Line Roughness a an Oum 0 30 um 0 59 um Figure A 25 High resolution images of a test grid with acoustic noise present in the room left and without noise right Nano R AFM User s Manual 107 OTHER SOURCES ELECTRONICS Faulty electronics can be a cause of artifacts in AFM images Most often these appear as oscillations o
45. diation For example x ray techniques make it possible to recreate the positions of atoms in a complex matrix or lattice Tunneling electronic micro scopes TEM make it possible to directly image atoms in a lattice However these techniques cannot see single atoms as they rely on the scattering of electro magnetic radiation from a collection of atoms Another important innovation is the laser tweezer By using the momentum of photons itis possible to isolate collections of several hundred molecules or atoms in a single location Prior to this invention the possibility of isolating a few molecules or even a few hundred molecules was not considered possible The drive to make smaller computer chips amp higher density information storage Moore s law popularized in the late 20th century dictates that there is a relation ship between time and the size of electronic devices such as transistors This re lationship has been very effective in predicting advances in the world of microelectronics for almost thirty years However physicists are predicting that Moore s law will begin breaking down when the size of electronic devices becomes less than 100 nanometers There is a great effort therefore to discover new methodologies for creating electronic devices of this size and smaller The storage of information is considered an essential advancement of modern civilization At first recording information and ideas on written paper was a
46. e Almost all AFM images require some image processing before viewing or analysis and most AFM products are supplied with very powerful image display and analysis software Properly used the image processing software will typically not introduce artifacts into an image Most AFM images have some tilt and bow caused by the scanner or stage config uration as described above on page 98 A number of background subtraction options are possible The two most common types are Line by line leveling 0 to 4 order e Plane Leveling 0 to 4h order Image processing software typically allows you to exclude areas from the leveling When an area is excluded it is not used for the calculation of the back eround in the image A typical leveling routine is illustrated in Figure A 21 In the original image A before any image processing tilt is easily recognized the right side of the image appears darker than the left side The second image B is the result of line by line leveling with a first order background correction The dark band is caused by the image processing and is not a real structure The third image C was derived by excluding particles from the background subtraction process Revision 1 1 104 Appendix A Guide to AFM Image Artifacts A B C Figure A 21 Leveling of a 1 6 X 1 6 um AFM image of nanospheres HIGH PASS FILTER A high pass filter is often used to smooth data before it displays In images with substantial
47. e features The features in each block have uniform size and pitch with each block containing features of a different size as illustrated in Figure 1 9 This pattern is repeated at 15 locations on the reference The pattern for optical microscope reference is composed of a series of four sets of parallel lines and a second series perpendicular to the first SOFTWARE MODULES Revision 1 1 The SPM Cockpit software modules serve three functions e acquire AFM data e process and analyze the acquired data display AFM images contained in the analysis modules EZMode Acquisition X Pert SPM Cockpit PNI Analysis Analysis NanoRule Figure 1 10 SPM Cockpit software modules The interfaces for the image acquisition and analysis modules feature tool bars that provide convenient access to the most commonly used software functions for the given mode of operation However regardless of the module acquisition or analysis or mode EZ or X Pert you are in all of the SPM Cockpit software functions are always accessible via the menu items Note that the PNI Analysis software is included with all Nano R AFM systems and NanoRule a more full featured analysis software package is available as an option Nano R AFM User s Manual ACOUISITION NE ade File De When you launch the SPM Cockpit software the acquisition module opens by Y E T 4 default You will be in either EZMode or X Pert Mode depending on the mode mode Exp
48. e linear so that the distances measured from the images are accurate With no correction the features on an image will typically appear smaller on one side of the image than on the other Nano R AFM User s Manual O00 Joug OOO OOO LT JL JE JL 4 JL JL IL OOo UUL Figure A 9 A test pattern of squares left will appear severely distorted right if the piezoelectric scanner in the AFM is not linear The AFM image of the test pattern in Figure A 10is very linear It appears as it should with consistent spacing of the squares on all sides 0 10 20 30 40 um pm ESOO E 5 BESOS FEROE a CHA 050000080000 0 2 45 BREE SSBB BEES SE 0 18 I O 0 16 HANNA 0 14 SSCeeeseeeees ae BESS SSB S888 888 AAA ae EEE BBB SSBB RRB SB 0 08 SS ae eee es ee ee ee 0 06 40 EDO 0 04 RPE ERE ESP SBE BSH EE 0 0 45 aaa e eee ee es pm Figure A 10 Linear AFM image of a test pattern Once the scanner is properly linearized it is also critical that it be calibrated If it is linear but not calibrated correctly the X Y values measured from line profiles will be incorrect A common method for correcting the problems of X Y non linearity and calibra tion is to add calibration sensors to the X Y piezoelectric scanners These sensors can be used to correct the linearity and the calibration in real time Revision 1 1 97 98 Appendix A Guide to AFM Image Artifacts Z CALIBRATION LINEARITY Accurate AFM height measurements depend o
49. e puck to initial X Y position Revision 1 1 Nano R AFM User s Manual 45 10 Click Genter Position The motorized X Y stage will return the puck to its original position INSTALL A PROBE To operate in close contact mode you need to use a close contact probe Probes should be stored in the supplied boxes which are marked Contact and Close contact as the differences between the two types of probes is not visible to the naked eye 1 First remove the sample puck as described in the section above 2 Click Stage from the EZMode toolbar and click Change Tip in the AFM Stage Controls dialog s AFM Stage Controls FOCUS ZOOM X Y Step Load Sample El 132 4 5 J Change Tip i OUT 5 E a Lo ma ol z TH W 15 658 53 um Y 15 810 97 um N 20a 149 um Focus Step de F up Position 0 a Or we att HE 11 069 78 um Figure 3 11 Raise the probe tip away from the sample The Z motors will raise the scanner to the top of its range 3 Click the 4 focus button to raise the video objective to the top of its range The upper indicator will turn from green to red when the objective reaches the top of its range Revision 1 1 46 Chapter 3 Tutorial Close Contact EZMode 4 Click Align Laser from the tool bar ry Select gt Align Frequency Stage Tip Scan Image 5 Tip Mode Laser Sweep Approach sample Processing Retract L El a 5 Turn off the laser E Red Dot Alignm
50. eading and trailing edges of the structure as shown in Figure A 14 and Figure A 15 10 15 20 25 30 pm nm MA A AA A A 400 350 300 250 200 150 100 50 10 12 14 16 15 Figure A 15 This AFM image of a test pattern appears to have no artifacts but the line profile shows overshoot at the top of each line Nano R AFM User s Manual 101 SCANNER DRIFT Drift in AFM images can be due to thermal drift in the piezoelectric scanner and the susceptibility of AFMs to external temperature changes In AFM imaging it is common to zoom in to a small area of a scanned region and take a new scan in order to get a higher magnification The most common type of drift shows up as distortion at the beginning of such a scan as shown in Figure A 16 Drift artifacts are most easily observed when imaging test patterns lines that should appear straight have curvature Figure A 16 Distortion due to drift in the initial part of a scan of a zoomed in area pm Figure A 17 Zoomed image showing a distortion at the beginning of the scan scan angle 45 Revision 1 1 102 Appendix A Guide to AFM Image Artifacts X Y ANGLE MEASUREMENTS Errors in the horizontal measurements in an image can result if the motion generated by the X Y scanner is not orthogonal This error or artifact can best be seen when imaging a test pattern with squares The error in orthogonality can be measured by using
51. early visible The piezoelectric scanner is often supported at the top by a mechanical assembly as shown in Figure A 12 and the motion of the probe is therefore nonlinear in the Z axis as itis scanned across a surface The motion can be spherical or even par abolic depending on the type of piezoelectric scanner Nano R AFM User s Manual 99 XYZ scanner i O curved motion of scanner Figure A 12 Nonlinear Z scanner motion In Figure A 13 the bow introduced into the image is seen at the edges The line profile across the image shows the magnitude of the bow ase fhar arios E past SEN Figure A 13 Bow in AFM image and line profile of a flat piece of silicon Scan size 85 X 85 um Revision 1 1 100 Appendix A Guide to AFM Image Artifacts Z EDGE OVERSHOOT 10 15 20 25 Revision 1 1 Hysteresis in the piezoelectric ceramic that moves the probe in the Z direction can cause what is known as edge overshoot This problem is most often observed when imaging micro fabricated structures such as patterned Si wafers or compact discs The effect can visually improve the images by making the edges appear sharper However a line profile of the structure shows errors pa Figure A 14 Overshoot in scan top is apparent in the line profile bottom Any overshoot that occurs as the probe is scanned over a surface feature would be apparent in the line profile of the resulting image at the l
52. easing this value making it less negative brings the tip closer to the sample Gain The gain should be adjusted 1 2 steps at a time Increasing the gain too quickly can result in damage to the scanner PID Use the following guidelines for tuning the proportional integral and derivative gains PID Incontact mode the derivative should be kept at 0 otherwise the scan will be unstable Nano R AFM User s Manual 89 e For relatively flat samples use a relatively high proportional gain while keeping the derivative low e For relatively rough samples use lower proportional values while increasing the integral SAVING IMAGES The Ya button on the X Pert toolbar accesses the save options By default images are saved in the ScanData folder Save Image s in DigitalSurf format Save jni E ScanD ata CF Ez zl CO CarbonNanoTubes EG Ey SlipTraces_ LLL My Recent E Charis_cc_6um_ithz_512_Odeg_n2615setptGSPi412000_C 2 HGT RE sur Charis_ cc _Sum_dhz 512 Odeg_n2455setpiG5P1412000_17 2 DEM Fut sur Charis cc Bum the 512 Odeg_n2 55setpiG5P1412000_ 17 A HGT Fw sur Charis _cc_8um_ihz_5i2_0deg_nz465setptG5SP i H2000 17 ADEM FW sur Desktop Charis_ cc 20um_1hz 512 Odeg n2455setptG5P1412000_17 Z DEM F sur Charis_ cc Oum_dhz 512 Odeg_n2455setptG5P14I2000 17 Z2 HG TH F sur Documents m d mt Charis cc Oum_dhz 512 Odeg n2455setphGSP1412000_ 17 205EN F sur My Documents a a 5 My
53. ed and installed per Pacific Nanotechnology installation instructions Revision 1 1 4 Products not operated within the acceptable parameters noted per Pacific Nanotechnology installation instruc tions 5 Products that have been altered or customized without prior written authorization from Pacific Nanotechnol ogy 6 Products that have had their serial number removed altered or otherwise defaced 7 Improper or inadequate care maintenance adjustment alteration or calibration by the user Binary License Agreement The use of the Pacific Nanotechnology instruments per the instructions in this manual includes executing a pro gram The Licensee assumes responsibility for the executed program chosen for your purposes and for the use installation and results received from it YOUR LICENSE WILL BE TERMINATED AUTOMATICALLY IF YOU COPY MODIFY USE OR TRANSFER THE PROGRAM OR ANY COPY MODIFICATION OR MERGED PORTION COMPLETELY OR PARTIALLY EX CEPT AS SPECIFICALLY PROVIDED IN THIS LICENSE License The licensee may use the program on a single machine and copy the program into any machine readable or printed form for the support or the backup of the use of the program on the single machine The licensee may modify the program and or merge it into another program for your use on the single machine Any portion of the program that is merged into another program will continue to be subject to the terms of this Agreement The licensee m
54. ed in this situation instead of Z SEN as the z sensor will not be sensitive enough to resolve the small features Revision 1 1 88 Chapter 5 X Pert Mode More Repeat Scan When this option is checked the system will take a continuous scan of the same region This allows you to keep adjusting the scanner and feedback controls until they are optimized FEEDBACK CONTROLS Revision 1 1 When you begin scanning use the default feedback control settings These can then be Feedback Controls adjusted while scanning to optimize image ac Setpoint 0 quisition The parameters should be adjusted one at a time in small increments Allow the Gain 2 system to scan a few lines after each adjust ment so you can see the result before adjusting Proportional 5 further Integral 5 Dervative 0 _ Adjust these settings carefully as it is possible to damage your scanner tip and sample Setpoint The setpoint represents the tip sample distance that the feedback electronics maintains as the tip is scanned over the sample surface In contact mode this is expressed as a force in nanonewtons raising the value brings the tip closer to the sample In close contact mode the setpoint is expressed as a voltage which is related to the voltage required to oscillate the cantilever at or near its resonant frequency The setpoint in close contact mode is set automatically when the frequency sweep is performed Incr
55. ely high resolution imaging the entire field of view of the image may be 100 nm In this case the magnification on a 500 mm computer screen is Magnification 500 mm 100 nm 1 mm 1 000 000 nm 5 000 000x PIEZOELECTRIC CERAMIC TRANSDUCER Precise mechanical motion in an AFM is created from electrical energy using an electromechanical transducer The electrical motor used in a washing machine is the most common example of an electromechanical transducer The electrome chanical transducer most commonly used in an AFM is the piezoelectric ceramic A piezoelectric material undergoes a change in geometry when it is placed in an electric field The amount and direction of motion depends on the type of piezo electric material the shape of the material and the field strength Figure b shows the motion of a piezoelectric disk when exposed to an electric potential apply 5 voltage Figure b When a voltage is applied to the top and bottom surface of the piezoelectric disc the disc expands A typical piezoelectric material will expand by about 1 nm per applied volt Therefore larger motions can be attained by making piezoelectric transducers with hundreds of layers of piezoelectric materials as illustrated in Figure c apply voltage gt wa Figure c When a voltage is applied to the top and bottom surface of a stack of piezoelectric disks the entire stack expands Revision 1 1 Nano R AFM User s Manual xxiii The amo
56. ency sweep Legend M Previous Full Auta ea Close Advanced 259 92 kHz efdde kHz ZIERR gt lv ze gt Hall Range Drive Amplitude Start Frequency Auto Set l mm l my 259 go kHz Set Frequency mark away e atid ed from resonace at zo Offset Z Setpoint End Frequency down from max amplitude aso mo as mW 279 92 kHz below above Full Range Set Setpoint below mark at 2000 of oscillation amplitude Phase shift Sweep Aate i Tune driving amplitude to 360 po deg fi 0 ms point obtain oscillation amplitude iso mv Figure 3 28 Tuned frequency peak Revision 1 1 Nano R AFM User s Manual 57 8 Check the quality of the peak and repeat the frequency sweep if necessary The resulting peak should be clean and sharp as shown in Figure 3 28 If the line is noisy or there are multiple peaks it probably means the contact between the probe and the scanner is faulty To remedy this repeat the pro cedure for installing a probe making sure that the probe substrate is flush with the L shaped mount If you have not already done so remove the probe apply a small droplet of glycerol to the probe mount and then install the probe 9 Click Ea to accept the selected peak Frequency Synthesizer Selects QD apply Frequency 4 270 50 kHz Amplitude 176 mv TETEE A y L 932 Full Iv Auto 259 92 kHz ZERR Halt Range Drive Anggilitude ess me 1
57. ength is 670nm and the maximum power is 3 mW In addition to the above please follow laser safety control measures in American National Standards Institute Z136 1 1986 HIGH VOLTAGE AN Wherever high voltage is present on the system extreme care should always be taken to avoid direct contact while the instrument hardware is powered on Always power off the equipment before attempting to remove any panels or PC boards and before touching any connectors by hand or with electrically conductive tools Pacific Nanotechnology Inc 2004 3350 Scott Blvd Building 29 e Santa Clara California 95054 Phone 408 982 9492 e Fax 408 982 9151 Revision 1 1 Nano R AFM User s Manual vil Contents Preface MroauUCION vir e da ts ade dla a ee e ie edo xi AFM AISlOLY eree e AAA AA AA RAR wee ASE ee Xi SLVIUS PrOllelS lt tri da is xii Scanning Tunneling Microscopes and Atomic Force Microscopes xiii Nanoscience amp Nanotechnology Overview 0000 eee XV AFM Tutorial ARO CC UO serere Bs ati honk tes ge atlas oie Gath race tats enka ts geet aca let ane XX Concepts 8 TechnologieS RENE naar xxi Dimensions and Magnification o ooooooooooo XXI Piezoelectric Ceramic Transducer o ooo ooocoonoooo ooo xxii FOCE SENSO A ET A xxiii Feedback CONTO leticia whee E Aa XXIV AFM Theory amp Instrumentation 0 0 00 cc eee XXV PAG IVAG SS Y aras US a aed aetna de rs ea get hd ee elon xXvi
58. ent Max FOCUS q pd po O z TaT a oe 3 149 um Focus Step Min a AMT up Z Position SUM q e mE Seale Gi Cx Ca Ce U E di STOP 3 421 22 um m e e E E C Off LASER 2 SUM 1 78 5 A o Core ZERRI 0 03 Y doi E 4 ZILA E 0 07 W Figure 3 12 Turning off the laser WARNING To avoid potentially hazardous laser exposure be sure to turn off the laser before rotating the scanner into the probe exchange position 6 Turn the probe exchange knobs on the side of the scanner head down away from you 1 4 turn Figure 3 13 The scanner head will slide out about an inch Revision 1 1 Nano R AFM User s Manual 47 Figure 3 13 Turn the knobs to disengage the scanner head 7 Grasp the handles on the front of the scanner head Figure 3 14 and gently slide the scanner head all the way towards you Figure 3 14 Slide the scanner head toward you Revision 1 1 48 Chapter 3 Tutorial Close Contact EZMode 8 Carefully rotate the scanner head up about 90 degrees as shown in Figure 3 15 Figure 3 16 Probe exchange position Revision 1 1 a mn c o Nano R AFM User s Manual 49 N CAUTION Handle AFM probes with care The cantilever can break off easily if it touches any i thing or snaps down too forcefully on the magnetic mounting surface on either the scanner or in the probe box Probe handling When loading or removing a probe pivot the substrate on the edge opp
59. er 8 Zoom in on a range of interest by left clicking on the curve and dragging to define the zoom region 9 Right click to define the eee DAC sweep range select EZ second limit of the range and then click Yes to apply it 2 Apply DAC sweep range Start 0 m End 0 m values Confirm sweep range Revision 1 1 78 Chapter 4 Material Sensing Modes Force Distance Curve 6 990 40 2167 7 A i Z stepper motor Current position b Half Range 3463 mv t 22220 um Vertical travel Offset a Lim Lee l D 5 285 40 LIT OR E 18t curve Start End a E 2nd curve End Start b i 65535 1 2 steps 4759 ni A 2498m 10000m Force Units E Start Stop Set Markers to minimax m nh eT oats Mili Force Calibration 21272879 623724 AM Full scale E 954 00 on Z 0 00 on Z fm pm y A 4 00 f 5612 nih l 492 21 nN Deflection Limit Rate l malpi Distance x f nm 4 2 5 2000 mv on Z ERR AORA Spring Constant or command to not exceed the abowe y 57 88 nih jo 2 Pedir i value of ERR signal Time 0 26 3 curve gral Slope cele bos o Measure the average of Sensitivity Fisel 128 f curve s jo 32 m in gt gt f BOS my Arn Note DAC 10000 mv 2 piezo Mote DAC 0 m 2 piezo is is fully RETRACTED fully EXTENDED dstcurve 2nd curve Start lo on Z DAC End Eoooo h on Z DAC Figure 4 8 Zooming in on a voltage sweep range The force distance curve window
60. er The laser spot should be centered on the cantilever not too close to the end as shown in Figure 2 26 FETEI n a B ae i eye y he pa a ae nuu wane JUN A E seen pa rr Death oo gt g oud hs odbel 3 ed j pa nnan N Whe te ed ed ud Figure 2 26 Centering the laser spot on the cantilever Revision 1 1 25 26 Chapter 2 Tutorial Contact EZMode 6 Watch the red dot in the Red Dot Alignment window as you turn the detector alignment knobs to bring the red dot into the top of the green box The red dot should be positioned just below the upper border of the box and be centered along the vertical axis as shown in Figure 2 27 ES Red Dot Alignment Secs Max FOCUS Z00M eee 7 0 EEE TeS t 143 um an i in e Focus Step feat pee i l nee oy Mini lt lt a a Zz N a up Z Position 2 su w fe Scale i Ca Ck Coa a 4 ae Ap 1 06 78 um r Pe SUM 178 Vv es y e ON t OFF ZERRI 2 00 W maT I Da R 006V Figure 2 27 Aligning the detector 7 Make sure the Z SUM value signal intensity is above the minimum If it is not you need to re seat or replace the probe APPROACHING THE SAMPLE 1 Click Stage from the EZMode toolbar 2 Use the focus controls to bring the sample surface into focus on the video monitor a w a y XL CAUTION Whenever you engage the motorized X Y stage be sure the probe is a safe distance g
61. ert used in the last session Use the Mode menu to switch between the two MW Pacific Nanotechnology SPM Cockpit Mode File Device Settings Tools Process Display Window Help Start Select Align Frequency Stage gt Tip Ga Scan gt Image Tip E e Mode Laser Sweep Approach Sample Processing Retract Figure 1 11 Acquisition module main screen in EZMode EZMode is intended for new and occasional AFM users A set of short cut buttons forms an easy to follow flow chart that takes you through the basic steps for taking an AFM image Each button opens a dialog offering the choices necessary for accomplishing that step Select Align Frequency Stage Tip Scan Image Tip Laser Sweep Approach Sample Processing Retract Sel Mode Figure 1 12 EZMode short cut buttons X Pert Mode is oriented toward advanced AFM users who want to take advantage of a wider range of choices and features for acquiring an image The X Pert Mode short cut buttons access the functions for accomplishing the same required steps in EZMode as well as other functions but the buttons are not nec essarily organized into sequential steps Figure 1 13 X Pert mode short cut buttons Revision 1 1 9 10 Chapter 1 Instrument Overview ANALYSIS From the acquisition module you can switch to the PNI Analysis module by clicking e A series of short cut buttons is displayed for easy access to the most commonly used image p
62. ert r Select Align FIequenty Tip Scan Image Tip Start Stage El i Mode Laser SWEER Approach sample Processing Retract C 3 Click Retract Tip and click OK when complete Revision 1 1 12 Chapter 2 Tutorial Contact EZMode Tip Retract Load Configuration Linearize Figure 2 1 Retracting the tip 4 Click Load Configuration select the PNI supplied contact mode configuration file and click Open 01 29 con chg 201 29 050 cfg File name feo 29 con Files of type a Cancel we Figure 2 2 Loading a configuration file This file should be located in the ConfigFiles folder in the SPM Cockpit directory It has the format sxxxx con cfg where xxxx is the serial number of your Nano k system 5 Click Linearize check both boxes and click OK confirm communication between controller and user PC Scanner uto Linearity checks Y full scale linearity Ok Cancel Figure 2 3 Initiate connection confirm and calibration routines Revision 1 1 Nano R AFM User s Manual 13 6 Click OK when the communication between the Master Computer and the Controller is confirmed Ping the Controller Ping the Controller PIH iti y 2 Waiting for Controller s response Figure 2 4 Connection confirmed If there is no connection you need to exit the SPM Cockpit software and restart both the Master Computer and the Controller 7 Click Yes to proceed with the calibratio
63. evision 1 1 Nano R AFM User s Manual 41 5 Click Linearize check both boxes and click OK E Linearize Calibrate confirmes communication between controller and user PC Scanner Auto Linearity checks Y full scale linearity Ok Cancel Figure 3 3 Initiate connection confirm and calibration routines 6 Click OK when the communication between the Master Computer and the Controller is confirmed Ping the Controller PIH iti Ay Waiting for Controller s response Figure 3 4 Connection confirmed If there is no connection you need to exit the SPM Cockpit software and restart both the Master Computer and the Controller 7 Click Yes to proceed with the calibration procedure Automatic X amp Y linearizer range select 2 This action will put the Controller into scan line mode and automatically adjust X Y Control parameters Would you Y like to continue Figure 3 5 Proceed with calibration routine Revision 1 1 42 Chapter 3 Tutorial Close Contact EZMode 8 Click OK when the last step of the calibration process is complete and then click OK to proceed E Automatic X amp Y linearizer range select E Final Step 8 of Done The 48 linearizer range is selected offset 1224 mw Yoffset 968 mv foom 126 azoom 132 Yzoom 1246 Automatic X amp Y linearizer range select 1 Application will now restore original INPUT SELECTS amp SCAN IMAGE settings and close Line Scan windows
64. eye AFM Stage Controls FOCUS ZOOM X T Step Load Sample gt um mu Change Tip 152 4 OUT gt L a ES 115 658 53 um Y 15 810 97 um Focus Step 0 f Or V gt of Position A 11 069 78 um Figure 2 8 Raise the probe tip away from the sample Revision 1 1 Nano R AFM User s Manual 15 E aN CAUTION To prevent damage to your scanner probe and sample be sure you have retracted ty 24 lt the tip and raised the Z scanner as described in the preceding steps before moving the puck 4 Click Load Sample The motorized X Y stage will move the puck towards you to the limit of its range 5 Being careful not to touch the probe slide the sample puck towards you and then lift it up out of the groove Figure 2 9 Remove puck 6 Use tweezers to mount the PNI AFM reference on the center of the puck The sample disk is held in place magnetically Figure 2 10 Mounting the sample Revision 1 1 16 Chapter 2 Tutorial Contact EZMode 7 Replace the puck on the stage by setting it down so the protruding piece on the bottom fits into the wide part of the groove and then slide it into position groove Figure 2 11 Fit the sample puck into the groove on the X Y stage 8 Rotate the puck so that the PNI reference sample is square with the scanner head 9 Select Tools Nanok Stage to open the AFM Stage Controls window AFM Stage Controls Z MOTORS Run to t
65. ging typically enhances fine feature contrast and provides some qualitative information about visco elasticity hardness adhesion and contaminations FORCE DISTANCE CURVES Revision 1 1 Single point measurements can be taken at selected locations on your sample surface The probe is moved toward the sample surface to a pre set voltage defined position and then retracted The amount of cantilever deflection over the course of this movement is expressed by the Z ERR signal which is used to generate a curve CAUTION To prevent damage to your instrument probe and sample make sure you are famil lar with the caution statements in Chapter 2 1 Take an image of your sample in contact mode as described in Chapter 2 2 To select a point on the sample to take a measurement hold down the CTRL key and left click in the image display in the Scan Image window A black dot marks the location Tip XY positioning 2 Apply new Tip position DAC 7976 mv Y DAC 1150 mv x Figure 4 6 Selecting a measurement location When you click OK the tip will move to the selected location 3 Click f to open the Force Distance Curve window 4 Check the Auto option 5 Make sure Z ERR is the selected signal from the signal drop down menu 6 Make sure the correct spring constant value for the cantilever you are using is entered in the Spring Constant field For PNI pre mounted contact probes this value is 0 2 N m When entering
66. great achievement books and newspapers allowed the flow of knowledge and information throughout the world Today information is stored digitally and transmitted electronically Digital bits with dimensions of less than a micron are stored on magnetic disks and compact discs There is an ever increasing need to store and transmit information on smaller spaces and transmit information with faster methodologies Emerging belief that it is possible to mimic the mechanisms of biology Researchers in the life sciences have discovered over the past few decades that there are many fundamental mechanisms that facilitate the recreation and support of all life forms At a distance these mechanisms can be characterized as machines or engines They absorb energy and in a very efficient way cause events to occur For example a virus will permeate a cell and then integrate with the genetic material of the cell Nano R AFM User s Manual xvii Presently we can observe these activities on a macroscopic scale In many cases we do not understand how they work or why they work But there is a belief that we can understand emulate and even use these fundamental activities or machines that occur in biological systems Creation of mechanical devices having nanometer tolerances and motions MEMS To a great extent the industrial revolution occurred because it became possible to shape mechanical objects and thus create new types of machines Before the in du
67. he TOP VVill set Z position to 0 00 Set 0 F mm mm E E E E E E MN aaj E mw 1 Center Position Is ay Jur A TRANSLATE KY LIGHT Load Sample X Y Step 9 f On E L Change Tip 21 3 gjum wre X position P 00 um 2 a z FOCUS ZOOM o a 00 um O a Cl U x Yector Translation Angle Translation E x 7073 Sum fro 0o am N Y fisso2 fm J4500 peg i 0 00 deg is X Forward Small Step Activate Trackball TOF Movexy Move Angle 64 6 um IV Log Position Offset single click Figure 2 12 Return sample puck to initial X Y position 10 Click Genter Position The motorized X Y stage will return the puck to its original position Revision 1 1 Nano R AFM User s Manual 17 INSTALL A PROBE To operate in contact mode you need to use a contact probe Probes should be stored in the supplied boxes marked Contact and Close contact as the dif ference between the two types of probes is not visible to the naked eye 1 First remove the sample puck as described in the section above 2 Click Stage from the EZMode toolbar and click Change Tip in the AFM Stage Controls dialog a W AFM Stage Controls FOCUS 00M 2 1 Step Load Sample F 4 El um p i k aaa Y 115 810 97 um E Y 149 um Focus Step de TI up Position A 11 069 78 um Figure 2 13 Raise the probe tip away from the sample The Z mot
68. he acquisition module ook CAUTION To prevent damage to your scanner probe and sample be sure to retract the tip e J gt before exiting the SPM Cockpit software or turning off the Controller 9 Click Tip Retract It is now safe to exit the SPM Cockpit software Revision 1 1 71 Chapter 4 Material Sensing Modes INTRODUCTION A A The Nano R AFM is capable of providing much more than topographical infor mation about your sample By monitoring other signal channels which are available when taking an AFM image information about the properties of your sample surface can be obtained Material sensing modes include but are not limited to lateral force microscopy LFM phase imaging and force vs distance curves Refer to the AFM Tutorial page xxix for more information WARNING Before operating the Nano R AFM make sure you are familiar with the safe ty information on page vi LATERAL FORCE MICROSCOPY LEM LFM studies are done while operating in contact mode The Z L R channel one of the four channels available in contact mode provides lateral force information The resulting LFM image can then be compared to the images generated by the other channels CAUTION To prevent damage to your instrument probe and sample make sure you are famil lar with the caution statements in Chapter 2 1 Set up the Nano R to take an image in contact mode as described in Chapter 2 2 Set the scanner and feedback control
69. hose features leaving the horizontal plane and extending in the vertical direction have historically been measured by a stylus profiler Figure a illustrates an example of an early profiler This profiler invented by Schmalz in 1929 utilized an optical lever arm to monitor the motion of a sharp probe mounted at the end of a cantilever A magnified profile of the surface was generated by recording the motion of the stylus on photographic paper This type of microscope generated profile images with a magnification of greater than 1000x photographic film mirror light source moving stage flexure Figure a Example of a surface profiler made in 1929 A common problem with stylus profilers was the possible bending of the probe due to collisions with surface features Such probe bending was a result of hor izontal forces on the probe caused when it encountered large features on the surface This problem was first addressed by Becker in 1950 and later by Lee Both Becker and Lee suggested oscillating the probe from a null position above the surface to make contact with the surface Becker remarked that the detail of images measured using this vibrating profile method would depend on the sharpness of the probe 10 Uber Glatte und Ebenheit als physikalisches und physiologishes Problem Gustev Shmalz Zeitchrift des Vereimes deutscher Ingenieurte Oct 12 1929 pp 1461 1467 11 U S Patent 2 7288 222 12
70. ic forces Insulating surfaces can store charges on their surface which can interact with charges on the probe or cantilever Such forces can be so strong that they bend the cantilever when scanning a surface Surface material properties Heterogeneous surfaces can have regions of varying hardness and friction As the probe is scanned across a surface the probe surface interaction can change when moving from one region to another Such changes in forces can give a contrast that is useful for differentiating between materials on a heterogeneous surface AFM IMAGING MODES Revision 1 1 Topography Modes As the probe at the end of the cantilever is scanned over the sample surface a constant force between the probe and the sample is maintained There are two methods for measuring the force on the cantilever as the probe encounters changes in the sample topography In deflection or contact mode the deflec tion of the cantilever is measured directly In vibrating mode the cantilever is vibrated and changes in the vibration properties are measured Deflection Mode Using the feedback control in the AFM it is possible to scan a sample with a fixed cantilever deflection Because the deflection of the cantilever is directly proportional to the force on the surface a constant force is applied to the surface during a scan While this scanning mode is often called contact mode because the forces of the probe on the surface
71. ion with the exception of archival purposes or for the specific use of the program with Pacific Nanotech nology equipment is prohibited by law and is a punishable violation of the law PACIFIC NANOTECHNOLOGY INCORPORATED PROVIDES THIS PUBLICATION AS IS WITHOUT WAR RANTY OF ANY KIND EITHER EXPRESS OR IMPLIED INCLUDING BUT NOT LIMITED TO THE IMPLIED WARRANTIES OR CONDITIONS OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE IN NO WAY SHALL PACIFIC NANOTECHNOLOGY INCORPORATED BE LIABLE FOR ANY LOSS OF PROFITS LOSS OF BUSINESS INTERRUPTION OF BUSINESS LOSS OF DATA LOSS OF USE OR FOR SPECIAL INCI DENTAL INDIRECT OR CONSEQUENTIAL DAMAGES OF ANY KIND EVEN IN THE EVENT OF SUCH DAM AGES ARISING FROM ANY DEFECT OR ERROR IN THIS PUBLICATIONS OR IN THE SPM COCKPIT SOFTWARE The trademarks or registered trademarks of Pacific Nanotechnology include the Pacific Nanotechnology logo Nano R SPM Cockpit NanoRule X Pert Mode and EZ Mode Revision 1 1 vi Safety Statement LASER OPERATION AFM SCANNING HEAD LASER WARNING NEVER LOOK DIRECTLY INTO THE LASER BEAM CDANGER gt IN ORDER TO AVOID THE POSSIBILITY OF THE USER INADVERTENTLY LOOKING INTO THE LASER ALWAYS USE THE SOFTWARE OR HARD PRTI WARE TO SWITCH THE LASER OFF BEFORE RAISING THE HEAD TO EYE AVOID DIRECT LEVEL EYE CONTACT The diode laser in the Nano R scanning head complies with US 21 CFR 1040 10 and is cer tified as a Class Illa laser The laser wavel
72. lick again to position the box within the scan region c Right click to confirm the new scan region The probe will move to the new scan region where you can start a new scan Additional zoom features are accessible via the Zoom and Extra Zoom buttons or by simply double clicking in the display nl Scan Image 19 31 um 30 63 um 7 3 TESTER Pia a Pe 1953 um E F s 30 63 UM zrseN e Forward Reverse 700m e jv Histogram correction v Auto leveling s 7 Shading region Figure 3 40 Selecting a zoomed in scan region 9 Toend your session now click Tip Retract on the EZMode toolbar Once the tip is retracted it is safe to turn off the Master Computer and the Controller Revision 1 1 66 Chapter 3 Tutorial Close Contact EZMode IMAGE PROCESSING 1 Click Image Processing on the EZMode tool bar 4 Select Align FRequeniny Tip m Scan gt Image m Tip E star mp Mode e SWEEP rage Approach sample Processing Retract I 2 Click OK to load the Z SEN image into the image processing display M Pacific Nanotechnology SPM Cockpit Mode File Device Settings Tools Process Display Window Help ical Se S IA afraid ES B Select Source Image for Proce E Acquisition Direction ie Forward Reverse Acquisition Channel Z SEN Sensor Figure 3 41 Image processing module 3 Select the desired acquisition channel and direction for the image to be processe
73. moving a probe very small distances However when a linear voltage ramp is applied to piezoelectric ceramics the ceramics move in a nonlinear motion Furthermore the piezoelec tric ceramics exhibit hysteresis effects caused by self heating Artifacts can also be introduced into images due to the geometry of the scanner and the positioning of the scanner relative to the sample PROBE SAMPLE ANGLE If the surface features are much smaller in profile than the probe and the image does not seem correct the artifact may be caused by anon perpendicular probe surface angle Ideally the probe tip should be perpendicular to the surface AA Li Figure A 8 A sharp probe scanning at an angle In the measurement illustrated in Figure A 8 the probe is much sharper than the feature so the image should be correct However because of the extreme probe sample angle the line profile will show an artifact at the left edge of the feature Solving this problem is achieved by adjusting the angle between the probe and the sample so it is perpendicular In some AFM microscopes the probe is designed to be at a 12 degree angle with respect to the sample Some microscopes do not have mechanical adjustments to control the probe sample angle X Y CALIBRATION LINEARITY Revision 1 1 All atomic force microscopes must be calibrated in the X Y axis so that the images presented on the computer screen are accurate Also the motion of the scanners must b
74. n only imagine what is possible Imagine e All of recorded history will fit in a package small enough to carry in our pockets This includes all written documents music and movies e Our world will be safer because the computers and sensing systems that fit in a package the size of a pill will be able to warn us of dangers e Life will be extended because we can create systems and modules that replicate the functions and systems in our bodies e New types of quantum computers will make calculations billions of times faster than today s digital computers e Wecan create new types of molecules with the mechanical assembly of chemical systems instead of today s assembly by thermodynamic chemical reactions Nano R AFM User s Manual X X WHAT IS THE AFM S CONTRIBUTION TO NANOTECHNOLOGY Measurement An atomic force microscope AFM creates a highly magnified three dimension al image of a surface The image is generated by monitoring the motion of an atomically sharp probe as it is scanned across a surface With an AFM scientists and engineers can directly view and measure surface features having dimensions on the order of a few nanometers including single atoms and molecules An AFM makes it possible to measure more than the physical dimensions of a surface as there is a physical interaction of the probe with the surface For example by lightly pushing against the surface with the probe it is possible to measure
75. n procedure Automatic XE Y linearizer range select 2 This action will put the Controller into scan line mode and automatically adjust X Y Control parameters Would you like to continue Figure 2 5 Proceed with calibration routine 8 Click OK when the last step of the calibration process is complete and then click OK to proceed ti Automatic X amp Y linearizer range select E Final Step 8 of 8 Done The X amp Y linearizer range is selected Xoffset 1224 mv Yoffset 968 mW Zoom 126 Xzoom 132 Yzoom 126 Figure 2 6 Calibration routine complete AA Start Select m Align Ereguenty Stage Tip m Scan Image m Tip E Mode Laser SWEEP Approach sample Processing Retract L Revision 1 1 14 Chapter 2 Tutorial Contact EZMode 9 Click Select Mode on the toolbar select Contact in the dialog and click OK Select Mode Mode Contact fe Close Contact s E Cancel Advanced Figure 2 7 Select mode 10 If the PNI AFM reference is already loaded on the sample puck skip ahead to page 17 to load a probe or to page 23 if a contact probe is already loaded LOAD A SAMPLE HL store bl ga acer 0 C ose up SAS a El EM 1 Click Tip Retract from the EZMode toolbar 2 Click Stage from the EZMode toolbar a 3 Click cea to raise the Z motor until there is at least a few millimeters of clearance between the probe and the sample surface or puck if no sample is loaded monitor by
76. n the piezoelectric ceramics in the Z axis being both linear and calibrated If the microscope is calibrated at only one height the height measurements will only be correct if the relationship between the measured Z height and the actual Z height is linear Measured Z Height Actual Z Height Figure A 11 Z calibration at only one point The graph in Figure A 11 shows the relationship between an actual Z height and a measured Z height in an AFM In cases where only one calibration point is measured as represented by the grey circle the Z ceramic is assumed to be linear as shown by the straight line However as is often the case the ceramic is nonlin ear as shown by the bowed line When this is the case the microscope will measure incorrect Z heights unless the feature being measured is close to the cal ibration measurement BACKGROUND BOW TILT Revision 1 1 The piezoelectric scanners that move the probe in an atomic force microscope typically move the probe in a curved motion over the surface The curved motion results in a bow in the AFM image Also a large planar background or tilt can be observed if the probe sample angle is not perpendicular In cases where a background bow and background tilt are larger than the features of interest the background must be subtracted from the image This is often called leveling or flattening the image Typically leveling the image should make the desired features cl
77. neral the sharper the probe the higher the resolu tion The theoretical line scans in Figure f illustrate the difference between using a sharp probe and a dull probe to measure two spherical features on a sample surface The sharper probe will result in a higher resolution image DO UNO SVE FV Figure f Using a dull probe vs a sharp probe to measure spherical features Vertical Resolution The vertical resolution in an AFM is established by relative vibrations of the probe above the surface Sources of vibrations include acoustic noise floor vibrations and thermal vibrations Getting the maximum vertical res olution requires minimizing these vibrations PROBE SURFACE INTERACTIONS The strongest forces between the probe and surface are the mechanical forces that occur when the atoms on the probe physically interact with the atoms on a surface However other forces between the probe and surface can have an impact on an AFM image These include surface contamination electrostatic forces and surface material properties Surface contamination In ambient air all surfaces are covered with a very thin layer lt 50 nm of contamination This contamination which can be comprised of water and hydrocarbons depends on the microscope s operating environment Revision 1 1 xxviii AFM Tutorial When the probe comes into contact with the surface contamination capillary forces can pull the probe towards the surface Electrostat
78. ng Retract al al Scan Image 0 00 um 19 31 um 38 63 um Z SEN Forward Reverse ri 4 Histogram correction V Auto leveling 4 I Shading H D Shading 4662 3 761 42 nr 6171 7331 6168 10000 0 00 nm 6165 0 38 63 um 0 Full 2 SEN Half Range 2669 mv Offset 7331 mV I Auto Auto Auto leveling V Figure 3 34 Scan image window 2 Set the scanner controls as follows e Scan Size leave as is e Scan Rage 2 Hz e Resolution 256 Scan Angle 0 e Acq Channels 4 e Topography Gain 1x 19 31 um 38 63 um 19 31 um Line 0 256 0 Line 0 38 63 um 0 00 um 19 31 um 38 53 um Z ERR Forward Reverse H Y Histogram correction Y Auto leveling 256 38 63 um Full ZERR Half Range 3 gt mv Offset 6168 mv The default scan size which is entered by the system when the calibration routine is performed is the maximum scan area for your scanner Nano R AFM User s Manual aok Scan Size um 39 52 Scan Rate Hz 2 r Scanner Controls Resolution 256 y Scan Angle fo E 0 90 180 270 Acq Channels 4 H Zoom Extra Zoom Tip Force Approach Curve Topography Gain 1x 4x Repeat Scan p Feedback Controls Setpoint 789 E Gain 5 am Proportional fi 0 Integral 10 sn Derivative 5 Lines Remaining Scanner Controls Scan Size um 3952 Scan Rate Hz B Resol
79. ntrol the position of the Z piezoelectric ceramic The motion of the probe over the surface is generated by piezoelectric ceramics that move the probe and force sensor across the surface in the X and Y directions See Figure e Figure e Main components and subsystems of an AFM system Z coarse Z motion translator Moves the AFM head towards the surface so that the force sensor can measure the force between the probe and sample The motion of the translator is usually about 10 mm T coarse X Y translation stage Positions the section of the sample to be imaged directly under the probe Revision 1 1 xxvi AFM Tutorial X P 8 Y P X and Y piezoelectric transducers Move the probe over the surface in a raster motion when an image is measured FS Force Sensor Measures the force between the probe and the sample by monitoring the deflection of the cantilever Z P Z piezoelectric ceramic Moves the force sensor and probe in the vertical direction in response to the measured deflection of the cantilever as the probe is scanned across the surface FCU Feedback control unit Takes in the signal from the light lever force sensor and outputs the voltage that drives the Z piezoelectric ceramic This voltage refers to the voltage required to maintain a constant deflection of the cantilever while scanning SG X Y signal generator Controls the raster motion of the probe in the X Y plane when an image is measured CPU Computer
80. o o oocoococococnoe eee Scan INE Sample sones dt we eee e a eo eee Image Processing 2 0446 tos das ida eh Peewee TS Chapter 4 Material Sensing Modes IMUFOCUCHON s atado tweet eee eo Lateral Force Microscopy LEM 000 0c eee eee eee nee Phase Imagin en aca en sica Setter dete ie ed Mako pise poi denia SUD Gee a het eee dort hae bea a hea aoe Frequency SWCCD 2 22474 ae tee ee hoses Seed Seeks eee SCANNING os espro Es E See ae Force Distance Curves 2 02622 adria da eee ee Nano R AFM User s Manual ix Chapter 5 X Pert Mode amp More MOUGU ei da e bd ds bdo da lid dad do 81 AA O A eee eR 81 CONTO MOSCA READER eee 83 OPENING ace tar e iaa de dese 83 O A NE 83 Sage COn Suda id a da a e dd 84 Sample MOUMUN dana o aio cos disk 85 SCANMNG Sessa pe du ds 86 Feedback CONTOS anera E a a a ee eee 88 Savia Made See s td an a 89 Appendix A Guide to AFM Image Artifacts lalo o LAA A Os Sear ks gue ee eos es 91 FOO A Sash Sen telco op a yh ae Sob eee sate eee 91 Surface Features Appear too Large ooooooooooooo 92 Sub surface Features Appear too Small 93 Strangely Shaped Objects 0 0 0 0 ce es 94 Repeating Strange Patterns 0 0 cee ee 95 A Bite tae au e eke tine tel yee oe heme ee ale 96 Probe Sample Angles i008 2442 0 bade eatin oo eee eee 96 X Y Calibration Linearity n naaa aana aaa ee 96 Z Galibration LINCanty ese raso ea cad oS nd Eo eas oars 98
81. ons to combine several types of atoms to create new types of molecules With the advent of quantum physics physicists chemists and biologists can routinely study the spectra of atoms and molecules Several decades ago biochemists began to discover the usefulness of particular types of molecules such as proteins enzymes and DNA Until recently however working with and controlling atoms and molecules was limited to large quantities of these nanometer sized objects Realistically chemists would modify hundreds of trillions of molecules in a typical chemical reaction When chemists synthesize new molecules they make them in large quantities by using macroscopic methods such as heat to initiate chemical reac tions Biologists can identify and create new types of genetic material but only for a large number of molecules SO WHAT S NEW All the revolutions in science and technology are facilitated by many driving forces occurring simultaneously The nanotechnology revolution too is being driven by a number of developments ideas and technical advancements the primary ones being Revision 1 1 xvi Preface Revision 1 1 Instruments that measure amp manipulate atoms and molecules The invention of the Scanning Tunneling Microscope STM permitted us to see single atoms on a surface for the first time Before this it was possible to view and create images of lattices of many molecules using techniques based on electro magnetic ra
82. ors will raise the scanner to the top of its range 3 Click the 4 focus button to raise the video objective to the top of its range The upper indicator will turn from green to red when the objective reaches the top of its range 4 Click Align Laser from the tool bar eel align F Ti 5 Ti ele ign equenty ip can mage ip Start mp Mode ae mb SWEER aye Approach sample Processing gt Retract Es dl 5 Turn off the laser Revision 1 1 18 Chapter 2 Tutorial Contact EZMode ES Red Dot Alignment Max FOCUS 3 E Al TOR 149 um Focus Step e Min E a e I a gt LU i up a Z Position Z SUM a f EP Scale Gi Ca Ca Ce SM e E AN 11 069 78 um p m e e my i Cot LASER SUM 1 78 E Hh ro morr Ena 2 58 v doi E gF J 0 06 W Figure 2 14 Turning off the laser WARNING To avoid potentially hazardous laser exposure be sure to turn off the laser before rotating the scanner into the probe exchange position 6 Turn the probe exchange knobs on the side of the scanner head down away from you 1 4 turn Figure 2 15 The scanner head will slide out about an inch Figure 2 15 Turn the knobs to disengage the scanner head Revision 1 1 Nano R AFM User s Manual 19 7 Grasp the handles on the front of the scanner head Figure 2 16 and gently slide the scanner head all the way towards you Figure 2 16 Slide the scanner head toward you 8 Carefully rotate the
83. osite the cantilever as shown in Figure 3 17 This will protect the cantilever from striking the magnetic mounting surface and it will prevent the substrate from snapping down too forcefully which may damage the probe Figure 3 17 Probe handling 9 10 11 To remove a probe a Use tweezers to grasp the metal substrate as indicated in Figure 3 20 b Carefully rotate the tweezers so the cantilever side of the substrate lifts up off the magnetic mount first c Set the probe down onto the magnetic strip in the probe box so that the side of the substrate opposite the cantilever makes contact first d Carefully rotate the tweezers so the cantilever side of the substrate comes down onto the magnetic surface as gently as possible Apply a small amount of glycerol to the probe mount This will ensure proper mechanical coupling between the probe and the mount which is essential for close contact vibrating cantilever operation To install a new probe a Use tweezers to nudge a probe so that the substrate extends over the edge of the magnetic strip in the probe box Figure 3 18 b Grasp the metal substrate and carefully rotate the tweezers so the cantilever side of the substrate lifts up off the magnetic strip first as shown in Figure 3 19 Revision 1 1 50 Chapter 3 Tutorial Close Contact EZMode i Figure 3 19 Lift the probe cantilever side first Revision 1 1 Nano R AFM User s Manual 51 c
84. peceras GIN oops ha H T Figure 3 32 Positioning the probe over the scan area Revision 1 1 60 Chapter 3 Tutorial Close Contact EZMode SN CAUTION Be careful not to drive the probe all the way into the sample surface 5 While carefully monitoring the probe sample distance by eye use the yo button to lower the z scanner until the probe is about 1 2 mm above the sample surface 6 Focus on the sample surface and make sure the probe is positioned somewhere near the center of the pattern 7 Click the Tip Approach button on the toolbar Select Ali F md al 5 l Ti Sele ign requency ip can mage ip aah PALA Sweep Stage gt Approach m Sample Processing Retract 8 Click OK when the tip approach is complete do not exit the SPM Cockpit software or turn off the Controller without first retracting the tip Doing os CAUTION Once the tip approach is complete and the tip is in contact with the sample surface so may cause damage to the tip scanner and sample PIL T Figure 3 33 Tip approach confirmation The PID indicator at the bottom of the window will turn green to indicate that the probe tip is in contact with the sample surface and the instrument is now ready to perform a scan Revision 1 1 SCAN THE SAMPLE 1 Click the Scan Sample button on the toolbar r q SERET Select Align Frequency Stage Tip me Scan m Image Tip Mode Laser Sweep Approach Sample Processi
85. r unexplainable repeating patterns Electronic ground loops and broken components are usually the source of electronic noise The elec tronic noise in the image in Figure A 26 was the result of not having a ground wire attached to the stage The artifact is identified by the oscillations Profile Mode Profiles Horizontal Pos C Vertical Oblique C Polygonal 5 33 um O Circular Average Display Mode e Fit vertical Scale Fit Horizontal Scale Invert Z data Level Line Profile s range 41 94 nm Line Roughness O um 5 33 Um 10 65 um Figure A 26 Test pattern image with electronic noise at the top and bottom of the scan SURFACE CONTAMINATION Substantial contamination at the sample surface such as a fingerprint or oil film can cause AFM image artifacts Such artifacts appear as streaks on the image as seen in the top of the image in Figure A 27 Streaks tends to appear in areas of the sample surface having sharp features and edges Often the streaking can be reduced or even eliminated by cleaning the sample with a high purity solvent Revision 1 1 108 Appendix A Guide to AFM Image Artifacts Figure A 27 SEM image left and AFM image right of a contaminated test pattern VACUUM LEAKS Atomic force microscopes that are designed for imaging wafers and discs often use a vacuum chuck to hold the wafer or disc while scanning images A leak in the vacuum be
86. ration Oscillation amplitudes of between 0 3 nm and 100 nm were achieved with this optical technique Because the probe came into close contact with the surface upon each oscillation Wickramsinghe was able to sense the surface materials the differences between photo resist and silicon were readily observed 16 Y Martin C C Williams H K Wickramasinghe Atomic Force Microscope Force Map ping and Profiling on a sub 100 A scale J Appl Phys Vol 61 No 9 1987 p 4723 Nano R AFM User s Manual XV NANOSCIENCE amp NANOTECHNOLOGY OVERVIEW Approximately 15 years ago scientists and engineers began discussing a techno logical revolution that would be as dramatic and far reaching to society as the in dustrial revolution the nanotechnology revolution At first the primary promoters of the nanotechnology revolution were considered eccentric at best and a little crazy at worst However their ideas and visions are now becoming accepted by the mainstream intellectual scientific and engineering communi ties Recently governments and major corporations around the world have committed several billion dollars per year for the advancement of nanotechnolo gy and nanoscience research and development ATOMS AND MOLECULES The systematic study manipulation and modification of atoms and molecules having nanometer sized dimensions began several hundred years ago Society has benefited greatly because chemists are able to use chemical reacti
87. rocessing and analysis tools Figure 1 14 Analysis module short cut buttons To return to the acquisition module click E BASIC IMAGING PROCEDURE Revision 1 1 Acquiring an image with the Nano R AFM requires the following basic steps whether you are a new occasional or advanced user 1 10 11 12 Launch the SPM Cockpit software Open a configuration file contact or close contact Retract the tip and raise the AFM scanner to provide safe clearance between the probe tip and the sample puck Load a sample on the sample puck Install a probe on the AFM scanner Align the detector For close contact mode only set the resonance frequency for the installed cantilever Locate features for imaging Bring the probe into contact with the sample Scan the sample Perform image processing and analysis routines Retract the probe from the sample 11 Chapter 2 Tutorial Contact EZMode BEFORE YOU BEGIN This tutorial follows the steps for an taking a contact AFM image of the PNI AFM reference in EZMode WARNING Before operating the Nano R AFM make sure you are familiar with the safe ty information on page vi A POWERING UP THE SYSTEM 1 Turn on the Master Computer 2 Launch the SPM Cockpit software 3 Turn on the Controller 4 Turn on the video monitor SOFTWARE SETUP 1 Select Mode gt EZMode Mode File De w EZmode 2 Click the Start button from the EZMode toolbar Exp
88. roscopes we typically think of optical or electron micro scopes Such microscopes create a magnified image of an object by focusing elec tromagnetic radiation such as photons or electrons on its surface Optical and electron microscopes can easily generate two dimensional magnified images of an object s surface with a magnification as great as 1000x for an optical micro scope and as large as 100 000x for an electron microscope Although these are powerful tools the images obtained are typically in the plane horizontal to the surface of the object Such microscopes do not readily supply the vertical dimen sions of an object s surface the height and depth of the surface features The atomic force microscope AFM developed in the mid 1980 s uses a sharp probe to magnify surface features With an AFM it is possible to image an object s surface topography with extremely high magnifications up to 1 000 000x Fur thermore the magnification of an AFM is made in three dimensions the horizon tal X Y plane and the vertical Z dimension As acknowledged by Bennig and Roher the inventors of the tunneling microscope sucha powerful technique has its origins in the stylus profiler 9 G Bennig and H Rohrer Scanning Tunneling Microscopy From Birth to Adolescence Rev of Mod Phys Vol 59 No 3 1987 P 615 Revision 1 1 xii Preface STYLUS PROFILERS Revision 1 1 Magnification of the vertical surface features of an object t
89. ry close to the surface The results were astounding Bennig and Rohrer were able to see individual silicon atoms on a surface Although the STM was considered a fundamental advancement for scientific research it had limited applications because it only worked on electrically conductive samples A major advancement in profilers occurred in 1986 when Bennig and Quate demonstrated the AFM Using an ultra small probe tip at the end of a cantilever the AFM could achieve extremely high resolutions Initially the motion of the cantilever was monitored with an STM tip However it was soon realized that a light lever similar to the technique first used by Schmalz could be used for measuring the motion of the cantilever In their paper Bennig and Quate proposed that the AFM could be improved by vibrating the cantilever above the surface 13 R Young J Ward F Scire The Topografiner An Instrument for Measuring Surface Microtopography Rev Sci Inst Vol 43 No7 p 999 14 G Bennig H Rohrer Ch Gerber E Weibel Surface Studies by Scanning Tunneling Microscopy Vol 49 No 1 1982 p 57 15 G Bennig C F Quate Ch Geber Atomic Force Microscope Phys Rev Letters Vol 56 No 9 p 930 Revision 1 1 XIV Preface Revision 1 1 The first practical demonstration of the vibrating cantilever technique in an AFM was made in 1987 by Wickramsinghe using an optical interferometer to measure the amplitude of a cantilever s vib
90. s Channel 1 and Channel 2 will be used Channel 2 ZIHGT Z ERF ule Revision 1 1 91 Appendix A Guide to AFM Image Artifacts INTRODUCTION All measurement instrumentation used by scientists and engineers for research development and quality control generates results that may have artifacts This appendix serves as a guide to identify common artifacts that occur in AFM images It is organized into the following sections covering the four primary sources of AFM artifacts Probes Scanners Image Processing Vibrations PROBE ARTIFACTS Images measured with an atomic force microscope are always a convolution of the probe geometry and the shape of the features being imaged If the probe is much smaller than the features of the images being measured then the probe generated artifacts will be minimal and the dimensional measurements derived from the images will be accurate Avoiding artifacts from probes is achieved by using the optimal probe for the ap plication For example if the features of interest on the sample are in the 100 nanometer range a probe with a diameter as large as 10 nanometers will be adequate for getting good images with no artifacts In some cases even if the probe is not as sharp as the object being imaged it is still possible to get accurate information from the image Following are some of the more common probe artifacts Revision 1 1 92 Appendix A Guide to AFM Image Artifacts SURF
91. s as a new configuration file Save image file Select the device directory Test the connection with the Controller Display the tabs for all the Settings menu items Open the Red Dot Alignment window Time mode oscilloscope Line mode oscilloscope Open Frequency sweep window Dual trace storage scope Perform X Y scanner calibration routine Automatic tip approach and retract Manual tip up down control with signal monitoring Advanced AFM stage controls Open Scan image window Open Force distance curve window Nano R AFM User s Manual CONFIG FILES OPENING SAVING Config Two configuration files are supplied with the Nano R one for contact operation and one for close contact These files contain information that is unique to your particular instrument Therefore it is very important that back up copies of these files be kept in a safe place in the event that the ones on your Master Computer are accidentally altered or deleted These files also contain the factory default values for all the software settings that control your instrument At the start of each session you need to load a configuration file The filenames for the two supplied configuration files are in the following format xxxx is the serial number of your Nano R instrument e for contact mode sxxxx con cfg e for close contact mode sxxxx osc cfg You can use one of the supplied files or a user created file containing the
92. s as described on page 29 Revision 1 1 72 Chapter 4 Material Sensing Modes Revision 1 1 3 Select the Z SEN and Z L R channels from the drop down menus beneath the two image displays and for each display select Forward Histogram correction and Auto leveling 4 Select Settings Input Selects to ADC E Settings f LaserMotors XWZScales Nonlinearity XY Frequency Synth AUX 1 amp 2 Outputs Demod Selects Scan Image Setup XY Control feedback Input Selects to ADC PID Ont Channel 1 ZSEM Z Sensor SEN Gain i Oftsetfo 4 Filter Full Range ala zom y Error Signal APOS o m m m e E E Filter 100H2 Lateral Force L R Gain MF Offset 255 ZHGT Gain i H il Filter FullRange fj E es k Ok Cancel Apply Channel 2 Z HGT Channel 3 Z ERF Figure 4 1 LFM settings 5 For Lateral Force Z L R set the Gain to 1 and the Offset to 255 6 Click LA to take a scan While scanning you can monitor the image and line scan of any of the four channels Normally the gain and offset values for the Z L R channel should be sufficient for most lateral force imaging situations If a higher gain is needed open the Red Dot Alignment window and align the photodetector so that the red dot is to the left of the vertical mid line near the left border of the green zone The gain offset and filter can then be adjusted while scanning for optimal image acquisition
93. s so the height of the puck can be adjusted to accommodate different sample sizes see page 85 for details The protruding piece on the bottom of the puck fits into the groove on the X Y stage so it can be safely and easily guided into position under the probe Figure 1 8 Sample puck Revision 1 1 Nano R AFM User s Manual 7 PNI REFERENCE The Nano R system is supplied with the PNI AFM reference which is helpful for establishing the performance of your instrument s AFM scanners as well as the optical microscope The reference also serves as a useful test sample when learning how to use your instrument the tutorials in this manual are based on this sample AFM Reference A 1 micron square 2 micron pitch 2 5 micron square 5 micron pitch 5 micron square 10 micron pitch 10 micron square 20 micron pitch U O UU Notes Feature height nominal 75 nm Feature width within 0 3 microns Optical Reference 15 lines in each a b c d a 1 micron line 2 micron pitch b 2 5 micron line 5 micron pitch c 5 micron line 10 micron pitch d 10 micron line 20 micron pitch Figure 1 9 PNI reference Revision 1 1 8 Chapter 1 Instrument Overview The patterns in the reference are made in a silicon nitride film deposited on a silicon substrate This combination gives optimal color contrast when viewed with an optical microscope The pattern for AFM measurements is composed of four blocks of squar
94. s the user to feel and touch a surface Revision 1 1 XX Preface Revision 1 1 XXi AFM Tutorial INTRODUCTION This section serves as an introduction to how an AFM works With a basic under standing of the technologies employed in an AFM and how they are implement ed in the design and operation of the instrument you can obtain optimal results from your Nano R AFM CONCEPTS amp TECHNOLOGIES DIMENSIONS AND MAGNIFICATION An AFM is optimized for measuring surface features that are extremely small therefore it is important to be familiar with the dimensions of the features being measured An AFM is capable of imaging features as small as a carbon atom 0 25 nanometers in diameter and as large as the cross section of a human hair 80 microns in diameter The common unit of dimension used for making measurements in an AFM is the nanometer nm one billionth of a meter 1 meter 1 000 000 000 nanometers 1 micron um 1 000 nanometers Another common unit of measure is the Angstrom A a tenth of a nanometer 1 nanometer 10 Angstroms Magnification in an AFM is the ratio of the actual size of a feature to the size of the feature when viewed on a computer screen Thus when an entire cross section of a human hair is viewed on a 500 mm 20 inch computer monitor the magnification can be expressed as Magnification 500 mm 08 mm 6 250x Revision 1 1 xxii AFM Tutorial In the case of extrem
95. scanner head up about 90 degrees as shown in Figure 2 17 Figure 2 17 Rotate the scanner head Revision 1 1 20 Chapter 2 Tutorial Contact EZMode Revision 1 1 Figure 2 18 Probe exchange position CAUTION Handle AFM probes with care The cantilever can break off easily if it touches any thing or snaps down too forcefully on the magnetic mounting surface on either the scanner or in the probe box Probe handling When loading or removing a probe pivot the substrate on the edge opposite the cantilever as shown in Figure 2 19 This will protect the cantilever from striking the magnetic mounting surface and it will prevent the substrate from snapping down too forcefully which may damage the probe Figure 2 19 Probe handling Nano R AFM User s Manual 21 9 To remove a probe a Use tweezers to grasp the metal substrate as indicated in Figure 2 22 b Carefully rotate the tweezers so the cantilever side of the substrate lifts up off the magnetic mount first c Set the probe down onto the magnetic strip in the probe box so that the side of the substrate opposite the cantilever makes contact first d Carefully rotate the tweezers so the cantilever side of the substrate comes down onto the magnetic surface as gently as possible 10 To install a new probe a Use tweezers to nudge a probe so that the substrate extends over the edge of the magnetic strip in the probe box Figure 2 20 b Grasp the metal
96. ser s Manual 63 6 Click LA to take a scan Scan Image 19 31 um 38 63 um 19 31 um 38 63 um Scanner Controls 7 Scan Size um 3352 Y Scan Rate Hz 2 4 Resolution 255 Scan Angle 0 19 31 um ate 19 31 um 2 1 am Acq Channels 4 4 Zoom Extra Zoom Ti Fo Nean pls Topography Gain 1x 4x 38 63 um Md gt 38 63 um Repeat Scan T z sen gt e Forward Reverse Z ERR gt e Forward Reverse 3 v Histogram correction V Auto leveling H J Shading 0 00 um 1 V Histogram correction V Auto leveling H I Shading Line 256 256 163 48 nm Line 256 Feedback Controls Setpoint 789 Gain 5 Proportional f 0 3862 0 00 nm o E 38 63 um 38 63 um Derivative 5 E 0 0 Full Z SEN y HalfRange 116 mv Full ZERR y HalfRange 2q mv Figure 3 37 Taking a scan The images of the selected channels will build up line by line in the displays If no data is generated the detector may be out of alignment In this case click the EH button click Tip Retract from the toolbar re align the red dot page 52 and try another scan e To adjust the Z scale of the images left click and drag in the bar to the left of each display to select a Z height range e To view a single line scan hold down the SHIFT key and left click in either image display to define a horizontal line across 6 54 nr the image make sure the line includes the square
97. settings from a previous session However the type of configuration file contact or close contact must match the imaging mode for your session see below Once you have loaded a configuration file in X Pert mode there is no need to also select the imaging mode as in EZMode In the course of taking images you will invariably change many settings and pa rameters At any point the current settings which may apply to a particular sample and or application can be conveniently saved for future use by saving them in a new configuration file When saving new configuration files the filename should identify the file as either contact or close contact If you load a contact configuration file and attempt to operate in close contact mode using a close contact probe for example you will not be able to do so Revision 1 1 83 84 Chapter 5 X Pert Mode More STAGE CONTROLS AFM Stage Controls Revision 1 1 Activate Trackball TOF JY Log Position Offset MOTORS Run to the TOP Mil set Z position to 0 00 Sel oe de de OT u rl Z Position mm 0 00 um Y La TRANSLATE 4 p i A Load Sample x Y Step Change Tip 213 lum i Center Position I A AI ae 0 00 um PJ i o f 00 un MN E 2 Vector Translation Angle Translation mH x firoza jm hooo jm Y heso hm fas 00 heg i Small Step 645 um single click t 0 00 deg is 2 Forward
98. strial revolution it was possible to routinely make objects that had dimensions on the order of a few hundredths of an inch An artist could paint pictures a potter could make dishes and pots With the industrial revolution it became possible to routinely make machines with tolerances of a few thousandths of an inch 25 to 100 microns which gave way to the invention of the steam engine railroads the car and the airplane With MEMS technology it is now possible to use machining technologies to create machines smaller than the width of a human hair This ability is presently used in the sensors that activate airbags in cars set the frequency of computers and allow digital projection NANOSCIENCE Applying the scientific method to further understand the behavior of atoms and molecules at the nanometer scale will push forward the frontiers of human knowledge Currently our vision of the nano world is based only on evidence we collect from the macroscopic world in which we live Presently biologists chemists physicists and engineers have only a mental picture of what is occurring on the nanometer scale In fact only very recently have they actually seen or directly observed nano events As an analogy suppose you were presented with a gift in a box wrapped with paper In an effort to guess what is in the package you could shake it or maybe drop it Based on how the package behaves under this interrogation you may get an idea of
99. surface hardness Also the degree of ease with which the probe glides across the surface is a measure of the surface friction Modification An AFM can be used to write on a surface just as a pen is used to write on paper This new type of lithography is a completely new method for making surface modifications at the nanometer scale It is already possible to modify surfaces by physically scratching the surface directly depositing molecules on the surface and using electric fields to modify surfaces Presently this use of the AFM is in a very exploratory phase but it is showing tremendous promise One of the important technological issues that must be solved is the writing speed of AFM lithography systems Manipulation An AFM probe can be used to directly move objects across a surface The objects may be pushed rolled around or even picked up by the probe With such methods it is possible to create nanometer sized objects One of the important aspects of using an AFM for direct manipulation is the user interface for generat ing the motions of the probe Some interfaces measure the locations of particles such as microspheres on a surface and then automatically move the spheres to a pre established location In another type of interface called the nanomanipula tor the motion of the probe follows the motion of the user s hand When you move your hand up and down the probe moves up and down This kind of interface also allow
100. ta PF Invert Z data Z Level Line Profile s FT Level Line Profile s 2 42 um 2 42 um Z range 24 74 nm Line Roughness Z range 19 73 nm TF Line Roughness Figure A 23 AFM image of nanospheres before and after matrix smoothing IMAGE LOOKS TOO GOOD If an AFM image looks too good to be true it probably is All measurement tech niques have some noise associated with them Because AFM data is completely electronic it is possible to take an image and alter it with image enhancement techniques to create a beautiful picture that does not represent the structure of the surface The image in Figure A 24 was derived from an image with substantial noise Filtering has added the nodules which make it seem like a much higher reso lution image Figure A 24 AFM image of a nanotube showing nodules due to filtering Scan size 850 X 850 nm Revision 1 1 106 Appendix A Guide to AFM Image Artifacts VIBRATIONS Vibrations in an AFM s operating environment can cause the probe to vibrate resulting in image artifacts Typically the artifacts appear as oscillations Both floor and acoustic vibrations can excite vibrational modes in an AFM and cause artifacts FLOOR VIBRATIONS Often the floor in a building can vibrate up and down several microns at fre quencies below 5 Hz The floor vibrations if not properly filtered can cause periodic structure in an image This type of artifact is most often notice
101. teps for an taking a contact AFM image of the PNI AFM reference in EZMode A POWERING UP THE SYSTEM 1 2 3 Turn on the Master Computer Launch the SPM Cockpit software Turn on the Controller Turn on the video monitor SOFTWARE SETUP Mode File De 1 Select Mode gt EZMode Emad i E Cie dhe Stunt let Mederos WARNING Before operating the Nano R AFM make sure you are familiar with the safe ty information on page vi r q Start Select m Align Ereguenty Stage Tip m Scan Image m Tip E i Mode Laser SWEER Approach sample Processing Retract E oe 4 Revision 1 1 40 Chapter 3 Tutorial Close Contact EZMode 3 Click Retract Tip and click OK when complete Tip Retract Retract Tip Load Configuration Linearize mi Figure 3 1 Retracting the tip 4 Click Load Configuration select the PNI supplied close contact mode configuration file and click Open Open Configuration File Look in ConfigFiles ci EJ ac_ampl ini pe ac_phase ini My Recent contact ini Documents demo cfg pscan_nanoR cfg 50129 con chg AMEE Slave cfg Test_Zx lut Test_zZy lut hy Network File name a 29 080 cfg Placez Files of type Cancel Figure 3 2 Loading a configuration file This file should be located in the ConfigFiles folder in the SPM Cockpit directory It has the format sxxxx osc cfg where xxxx is the serial number of your Nano k system R
102. tered on the cantilever not too close to the end as shown in Figure 3 24 Figure 3 24 Centering the laser spot on the cantilever 7 Watch the red dot in the Red Dot Alignment window as you turn the detector alignment knobs to bring the red dot into the center of the green box as shown in Figure 3 25 O Red Dot Alignment Sele a eee se ete a ar S AAA hea aa 149 um de me E de de Focus Step i i Min I Y a A BER RA Position ZEUM Sole Gi Cx Ox Cae se mH HE EE Pasen TuM 1 78 W F I ON OFF Bere 0 03 W y BNE gerv Figure 3 25 Aligning the detector 8 Make sure the Z SUM value signal intensity is above the minimum If it is not you need to re seat or replace the probe Revision 1 1 Nano R AFM User s Manual 55 FREQUENCY SWEEP After aligning the detector the resonant frequency for the installed cantilever must be set 1 Click Frequency Sweep on the EZMode tool bar to open the Frequency sweep window ARO som Select Align Frequency Stage m Tip Scan m Image Tip Mode Laser Sweep Approach Sample Processing Retract L A aa Ges Z ERR a U R Legend Full Auto M Previous El current Lo EPA Close Tune Amplitude Advanced a E 259 92 kHz 279 92 kHz Fama PP vz qm Half Range Drive Amplitude Start Frequency Auto Set e63 l my il mv 259 92 l kHz Set Frequency mark avay B63 E es
103. tions as small as 1 nm are routinely measured by AFMs using this method FEEDBACK CONTROL Revision 1 1 Feedback control is commonly used for keeping the motion of one object in a fixed relationship to another object A simple example of feedback control occurs when you walk down a sidewalk As you walk you constantly control your motion by viewing the edge of the sidewalk If you begin to walk off the sidewalk you correct your motion so that you stay on the sidewalk Feedback control is used for many everyday applications including the automatic controls in airplanes and the thermostat controls in buildings In an AFM feedback control is used to keep the probe in a fixed relationship with the surface while a scan is measured Nano R AFM User s Manual XXV AFM THEORY amp INSTRUMENTATION The theory and operation of an AFM is similar to that of a stylus profiler The primary difference is that probe forces on the surface are much smaller in the AFM Because of this smaller probes can be used and a much higher resolution can be achieved In an AFM a constant force is maintained between the probe and sample while the probe is raster scanned across the surface By monitoring the Z motion of the probe as it is scanned a three dimensional image of the surface is constructed The constant force is maintained by measuring the force on the cantilever with the light lever sensor and by using a feedback control electronic circuit to co
104. tween the specimen holder and the specimen can introduce image artifacts which cause a loss of resolution Cleaning the vacuum chuck and sample often eliminates this problem part number 65 00614 Revision 1 1
105. unt of expansion of the whole stack depends on the applied voltage the piezo material and the number of disks By using one thousand layers of piezo electric material it is possible to get motions as large as 1000 nm per volt or 0 1 mm of motion with 100 volts FORCE SENSORS The construction of an AFM requires a force sensor to measure the forces between a small probe and the surface being imaged A common type of force sensor utilizes the relationship between the motion of a cantilever and the applied force The relationship is given by Hook s law F K D where e Kisa constant which depends on the material and dimensions of the cantilever e Dis the motion of the cantilever For a cantilever made of silicon that has dimensions of L 100 um W 20 um T 1 um the force constant K is approximately 1 newton meter Therefore a force of 1 nanonewton is required to move the cantilever 1 nm photodetector cantilever Figure d The light lever method for sensing the motion of the cantilever Revision 1 1 xxiv AFM Tutorial The motion of the cantilever can be measured with the light lever method as illustrated in Figure d A laser beam is reflected off the back side of the cantilever and onto a photo detector Deflection of the cantilever causes the laser beam to move across the surface of the photo detector The motion of the cantilever is then directly proportional to the output of the photo detector Mo
106. ure 4 9 Taking measurements Revision 1 1 80 Chapter 4 Material Sensing Modes Revision 1 1 81 Chapter 5 X Pert Mode amp More INTRODUCTION The tutorials in Chapter 2 and Chapter 3 guide you through the minimal steps required to take an AFM image This chapter takes you a little further exploring some of the Nano R features and functions that can help you take better images The contents are organized functionally roughly following the basic steps for taking an image outlined on page 10 WARNING Before operating the Nano R AFM make sure you are familiar with the safe ty information on page vi 2 XL CAUTION To prevent damage to your scanner probe and sample make sure you are familiar E 7 with the caution statements in Chapter 2 and Chapter 3 X PERT MODE Mode File De Once you are comfortable taking images in EZMode you may find it more con EZmode venient to operate in X Pert Mode Select Mode Expert to display the X Pert w Espert Mode short cut buttons which provide access to all the steps required for taking an AFM image as well as other functions and tools Figure 5 1 X Pert Mode short cut buttons ji Display the image processing toolbar a Conf Open the configuration file to be used for this session Revision 1 1 82 Chapter 5 X Pert Mode More Revision 1 1 E le Ele AY 1 1 E a E W J 7 E E e Save the current parameters and setting
107. ust reproduce and include the copyright notice on any copy modification or portion merged into another program If the licensee transfers the program and license to another party within your organization said party must agree to accept the terms and conditions of this Agreement The licensee must when transferring the program either transfer all copies in any form machine readable or printed to the same party and destroy any copy machine readable or printed or copies not transferred The licensee may not transfer the program to anyone outside of the licensee s organization without the written and express permission of Pacific Nanotechnology This license is effective from the date you take delivery of the software as purchased from Pacific Nanotechnology and remains in effect until terminated as indicated above or until the licensee terminates it The licensee agrees to destroy or return the program together with all copies modifications and merged programs in any form on their termination of this license Revision 1 1 Co pyright Notice covers all attached documents Pacific Nanotechnology Incorporated 2004 All rights reserved Pacific Nanotechnology retains all ownership rights to this documentation and all revisions of the SPM Cockpit and NanoRule computer programs and other related software options Reproduction of any portion of this document or any image depicted in this publication without prior written au thorizat
108. ution 256 ka Scan Angle ic DERE Acq Channels 4 00m Extra Zoom Tip Force eal Curve Topography Gain 1x0 4s Repeat Scan Revision 1 1 61 62 Chapter 3 Tutorial Close Contact EZMode 3 Set the feedback controls as follows O aae e Setpoint leave as is set automatically when Setpoint 789 I the frequency sweep was performed e Gain 5 oon i Proportional 10 fee evs TO Integral io E Integral 10 Derivative 5 e Derivative 5 4 Select the Z SEN and Z ERR channels from the drop down menus beneath the two image displays and for each display select Forward Histogram correction and Auto leveling 19 31 um 38 63 um 19 31 um 38 63 um 0 00 um 0 00 um 19 31 um 19 31 um SGP Ue 38 63 um MET le Foward Reverse Z ERR le Forward C Reverse J 1 ha Histogram correction V Auto leveling 1 V Histogram correction V Auto leveling a H MT Shading H Shading m E E E Y E E E E E E E E E E E ee ee Figure 3 35 Image display settings 5 Select the Z SEN and Z ERR channels from the drop down menus of the two corresponding line scan displays Line 0 Line 0 3 761 42 nr 0 00 nm 6165 a 38 63 um O Full ZIERA HMF ange 3 P Auto mm am Offset 616g EmN a 38 63 um 0 Ful Z SEN H amp Range 2669 mh W Auto Masain Offset 7337 o Figure 3 36 Line scan settings Revision 1 1 Nano R AFM U
109. v Fit Vertical Scale Fit Horizontal Scale Invert Z data E E gt Y Y HE EE la Level Line Protilefs Line Roughness 38 63 Um Under Profile Mode select Horizontal Under Display Mode e Check Fit Vertical Scale e Uncheck Invert Data c d Nano R AFM User s Manual 69 Markers Marker 1 5 623 Marker 2 d 20 301 25 974 213 226 69 574 i 2 000 H a 3 H ML LE AN 3 UHI a a 3 ip ip a 3 Left click in the image display to select a line Left click in the line display to make measurement markers In the example above measurements are made between the edges of two consecutive features on the PNI AFM reference The measurements displayed to the right confirm a pitch of 20 um and a Z height of approximately 70 nm NOTE These measurements should not be used to calibrate your instrument Revision 1 1 70 Chapter 3 Tutorial Close Contact EZMode 6 Click ll to open the histogram tool and use the slider bars to mark the middle of the two ranges where the z data points are clustered rt Histogram 2 Scan Data 7 SEN fwd Plane Correction 110 21 nm Apply Auto Done Unda Cancel Figure 3 45 Histogram tool The Z Diff measurement on the vertical bar confirms the 70 nm height of the PNI AFM reference features 7 To save any of your processed images select File gt Save Image s 8 Click to return to t
110. what is in it i e is it heavy does it make a noise With the nano revolution scientists will be able to open the package and really see what is inside With new ideas and methods scientists are beginning to further understand how a single atom or molecule behaves Even more interesting is the direct under standing of how collections of two or three or even a dozen atoms or molecules behave Revision 1 1 xviii Preface NANOTECHNOLOGY Revision 1 1 The fundamental knowledge gained through nanoscience and developments in nanotechnology will certainly accelerate over the next several decades With the control of materials at the nanometer dimension engineers are already able to create new types of products and services For example the smallest transistors we make in a factory today are about 130 nanometers wide With future nano technology advancements engineers will be able to make chips that have transis tors 2 3 nanometers wide Today cosmetic manufacturers use liposomes with diameters of a few tens of nanometers to reduce the dehydration of skin We expect that the nanotechnology revolution will result in the creation of new types of products and services that will greatly benefit our lives What is Possible When the ideas and concepts discussed as part of the nanotechnology revolution are fully implemented what is possible At this point many of the possibilities being discussed seem like science fiction We ca
111. x E gt Scan ot gt Lines Remaining Feedback Controls Setpoint lo Gain 5 a Proportional fi 0 Integral 15 gt Derivative 0 gt Scanner Controls Scan Size um 39 52 Scan Rate Hz Lo 256 scan Angle lo oF o so an Acq Channels 4 gt 00m Extra Zoom Resolution Tip Force Approach Curve Topography Gain Es Tet dy a Scan Revision 1 1 30 Chapter 2 Tutorial Contact EZMode 3 Set the feedback controls as follows Feedback Controls Setpoint 0 Setpoint 0 e Gain 2 Gain p e Proportional 5 Proportional 5 Integral 5 Integral j e Derivative 0 ee M L 4 Select the Z SEN and Z ERR channels from the drop down menus beneath the two image displays and for each display select Forward Histogram correction and Auto leveling 19 31 um 30 63 Um 19 31 um 1931 um 4 158 38 63 um LL F E MEE E Forward Reverse Z ERR Forward Reverse i Baxi Histogram correction ff Auto leveling e Histogram correction 4 Auto leveling a Shading Shading m ee E ee ee ee ee ee e ee ee ee ee ee ee ee ee Figure 2 32 Image display settings 5 Select the Z SEN and Z ERR channels from the drop down menus of the two corresponding line scan displays Line 0 Line 0 3 761 42 nr 10000 0 00 rim ie OA 38 63 um 0 as m 38 63 um Fully Z15EN y HW Range 2669 pe Fl ZERP
112. y However it is still possible to measure the opening of the hole from this type of image Also the pitch of repeating patterns can be accurately measured with probes that do not reach the bottom of the features In Figure A 4 the SEM image shows the sides of the squares in the test pattern to be equal In the AFM image because the probe is not sharp the squares appear much smaller than they are and as rectangles not squares A Acc Y SpotMagn Det WD Exp 2m oo 0 5 00 kY 3 0 15607x SE 283 1 TGXO1 side Figure A 4 SEM left and AFM right images of a test pattern of squares NT MDT TXO1 Revision 1 1 94 Appendix A Guide to AFM Image Artifacts STRANGELY SHAPED OBJECTS If the probe is broken or chipped the resulting image may have strangely shaped objects that are difficult to explain The chipped probe in Figure A 5 follows the surface geometry in a way which creates an image with a substantial artifact Figure A 5 Chipped AFM probe scanning over a sample surface 20 40 50 50 pm Hm 0 7 0 65 0 6 0 55 0 5 0 46 0 4 035 0 3 025 0 2 0 45 0 4 0 05 pm Length 90 533 um Pt 0 47184 um Scale 1 pm Figure A 6 AFM image of a semiconductor test pattern and the line profile showing an artifact Scan size 91 X 91m Revision 1 1 Nano R AFM User s Manual 95 The dark right edges in the image in Figure A 6 would indicate that the tip was scanned at a large angle to the surface
113. z gt o Nano R AFM User s Manual CAUTION Use care when handling AFM probes as they can break very easily Always handle with tweezers and never touch the cantilever The Nano R AFM is shipped with probes for the two basic imaging modes contact and close contact vi ar qe brating cantilever The probes come in yn Zz gt gt cameo W i Sia eau ag ea Y two marked boxes 10 probes to a box SS o x mode ina a peN AFM probes cantilever amp probe lt lt cantilever chip metal substrate Figure 1 5 PNI AFM probe top view The probe tip extends from the end of a cantilever which is mounted to a chip The metal substrate that holds the cantilever chip is mounted in the AFM scanner it is magnetically coupled to the bottom of the scanner cantilever chip cantilever EEE as A metal substrate Figure 1 6 PNI AFM probe side view not to scale Revision 1 1 5 6 Chapter 1 Instrument Overview The two types of probes appear identical to the naked eye but under the instru ment s optical microscope you can see that contact cantilevers are significantly longer than close contact cantilevers anar aaa Seseesecsssus contact cantilever close contact cantilever Figure 1 7 The two cantilever types as seen on the video microscope monitor SAMPLE PUCK The sample to be imaged is mounted on the sample puck The puck is composed of removable layer

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