RIE instructions
Contents
1. Pumps Turbo Susceptor Material Graphite or Ardel Temperature C 25 Electrode Size 6 8 11 Gases sccm O2 5 8 10 He 5 8 10 Pressure mTorr 10 10 10 Power Watts 150 175 200 DC bias Volts 500 500 500 Typical Etch Rate A min 1000 Notes Optimum performance is obtained using a silicon dioxide mask Metal masks can cause grass to form in the bottom of the etched features due to re deposition of the mask material The He is necessary in order to obtain a high degree of anisotropy if this is not essential the He can be omitted with a resultant increase in the etch rate 2 8 Silicon Dioxide Etch Mode Reactive Ion Etch RIE Pumps Turbo or Mechanical Susceptor Material Graphite or Ardel Temperature C 25 Electrode Size 6 8 11 Gases sccm CHF 22 5 36 45 Or 2 3 4 5 Pressure mTorr 40 40 40 Power Watts 150 175 200 DC bias Volts 440 440 440 Typical Etch Rate A min 400 500 Notes This process will etch thermal oxide PECVD oxide TEOS oxide PSG and BPSG at approximately the same rates Also SiN and SiON can be etched using this chemistry with etch rates varying somewhat from the oxides The process is highly ion driven and is well suited for anisotropic removal of interlevel dielectrics during failure analysis For applications requiring pattern definition an increase in the percentage of oxygen will reduce polymer formation but will also reduce the2. of photoresist and a selectivity of 10 1 is easily achievable Some mask undercutting is present but etch factors of 5 1 can be obtained 2 14 Zinc Sulfide Etch Mode Pumps Susceptor Material Temperature C Electrode Size Gases sccm Ar H2 Pressure mTorr Power Watts Typical Etch Rate A min Notes This process requires a hard mask material to be used due to the high power levels Reactive Ion Etch RIE Turbo or Mechanical Graphite or Ardel 25 6 10 10 30 300 250 required to etch the ZnS g 20 20 30 400 11 25 25 30 500
3. selectivity to photoresist At high oxygen percentages the selectivity over silicon or metals that etch in fluorine is reduced 2 9 Silicon Nitride Etch High Rate Mode Reactive Ion Etch RIE Pumps Turbo or Mechanical Susceptor Material Graphite or Ardel Temperature C 25 Electrode Size 6 8 11 Gases sccm CF 22 5 36 45 Or 2 3 4 5 Pressure mTorr 40 40 40 Power Watts 150 175 200 DC bias Volts 425 425 425 Typical Etch Rate A min 1000 2000 Notes This high rate process can be used when the underlying layer is not attacked by fluorine The etch rate increases with increasing oxygen at the expense of photoresist etch rate 2 10 Silicon Nitride Etch Selective to Si Mode Pumps Susceptor Material Temperature C Electrode Size Gases sccm CHF O2 Pressure mTorr Power Watts DC bias Volts Typical Etch Rate A min 400 500 Notes Reactive Ion Etch RIE Turbo Graphite or Ardel 25 6 22 5 2 3 40 150 440 g 40 175 440 11 40 200 440 This SiN etch process is selective to aluminum silicon and other materials that etch in atomic fluorine These include molybdenum niobium tantalum and tungsten The silicon nitride etch rate increases with increasing oxygen at the expense of the above selectivities 2 11 Silicon Nitride Etch Passivation Removal Mode Reactive Ion Etch RIE Pumps Turbo or Mechanical Susce
4. system are shown on bottom left of screen ON start up and main pumps on off STAND BY manual operation READY auto operation to run a program i e recipes If under Process in system auto mode ON amp READY processes are in queue ready to run or are running check log book and do not abort if you are not authorized to do so On schematic diagram i e valves chamber tubes gases pumps ect White OFF not active Blue ON active If menu option letters are grey line is not an option disabled If menu option letters are black line is an option enabled To choose a recipe to run in automatic mode click Process Load Process Files Right Chamber File Name Directories OK pre C sysmon process Cancel BIGCLEAN PRC C FIRSTCLN PRC sysmon MRCLEAN PRC process user name List of File Types Drives Process Files PRC c ms dos_6 TO RUN SYSTEM IN AUTOMATIC MODE Info PROCESS Turbo is ON Process FIRSTCLN Warning Date 1 27 80 Alarm Time 11 41 06 System Status Process ON STANDBY READY ABORT END STEP HOLD RUN ALARM SILENCE Process Run Information Lot Run Comment OK RUN Automatic Initial Data FIRSTCLN Step 1 Description usercln Name FIRSTCLN Request Actual Pump Down TURBO Base Pressure 10 0 Hold Time 0 10 Time Remaining Automatic Process FIRSTCLN Step 2 then Step 3 Description Gas Channels RF Generators Process PumpTURBO Setpt Actual RF Control POWE
5. IN USE is flipped down over the computer screen the system is in use by another user which should also be obvious from the log book Log in EMERGENCY SHUT OFF switch is the large red button on the upper left corner of the main unit chamber is on top The system has a 550 Watt RF Radio Frequency induced plasma auto impedance matching power source The vacuum system has a turbo pump and backing rough pump with small N2 bleed The system has continuous water chiller cooling no user action necessary On the bottom of the system diagram page on the computer are three status log lines Info PUMPING WITH TURBO PUMP example Warning Alarm The audio part of the Alarm System is turned off but an alarm warning registers on the Alarm line If the alarm is on and or something is in the Alarm line at the bottom of the screen you will have to acknowledge the warning before you go on Make sure there still is not a problem Go to the bottom right of the screen and click on ALARM silence to move on You might have to also click on HOLD in Process bar at bottom of screen The RIE chamber should have been left under vacuum turbo pumping chamber by the last user Use gloves when handling anything going into system and clean items The schematic diagram page on the computer should show the main chamber a turbo pump a rough pump a butterfly valve main valve four gases CF4 02 SF6 CHF3 and a purge leak gas N2 Three modes of
6. R CF4 10 10 0 RF Config RIE O2 10 10 0 Setpt Actual Power 200 199 Ref 0 0 DC 341 RF 0 Setpt Elapsted Time 20 00 0 19 50 0 Automatic End FIRSTCLN Step 4 Description usercin Name FIRSTCLN Request Actual Pump Down TURBO Base Pressure 10 0 Hold Time 0 10 Time Remaining Process Complete STOP Automatic proscess FIRSTCLN Completed at 13 32 12 OK RIE PROCESS SAMPLE RECIPES 2 6 Polyimide Etch Isotropic Mode Reactive Ion Etch RIE Pumps Mechanical Susceptor Material Graphite or Ardel Temperature C 25 Electrode Size 6 8 11 Gases sccm O2 20 32 40 CF 5 8 10 Pressure mTorr 200 200 200 Power Watts 175 200 250 Typical Etch Rate A min 5000 Notes This process produces undercut and a sloped sidewall using a mask material that can withstand etching in a fluorine chemistry The etch rate is dependent on the CF flow and increases with increasing flow until a maximum is obtained at 30 CF4 CHF or SF can be substituted for the CF with subtle affects on the sidewall profile For failure analysis applications this process can be used to remove thick polyimide passivation layers Because of the fluorine content of the process silicon nitride and to a lesser extent silicon dioxide will also be etched Where this is important the CF can be eliminated at the expense of the polyimide etch rate 2 7 Photo Resist Polyimide Etch Anisotropic Mode Reactive Ion Etch RIE
7. Reactive lon Etching RIE System STEP BY STEP INSTRUCTIONS To run in manual mode Stand by enables manual mode Utility Vent Insert Sample Utility Pump Chamber lon Gauge On check vacuum lon Gauge Off Wait until vacuum lt 3 x 10 Torr before etching When ion gauge is on the real chamber pressure is monitored Service Manual Gas Flow Chamber Pressure Config RIE Power Time Gas On Pressure On IRF Power On Process over RF Power Off Exit N2 Purge On if desired Purge Off or All Off Utility Vent Take out sample Utility Pump Chamber CF R14 Freon 14 SiO etching O2 Oxygen Polymer etching SFs SulfurHexaFluoride Silicon etching CHF R23 Freon 23 SiO etching TriFluoroMethane Chamber Cleaning de scum by O2 Regular de scum higher values Light de scum in parentheses pressure 200 mTorr 50mT light flow 20 sccm 10sccm light Plasma colors standard cubic cm min pink gt Nb or air leak power 300 W 200 W light yellow gt O2 time 10 min 5 min light purple gt F chemistry RIE Reactive Ion Etch DETAILED INSTRUCTIONS If the computer needs log in it is Operator STUDENT Password STUDENT If paper reading
8. ptor Material Graphite or Aluminum Temperature C 25 Electrode Size 6 8 11 Gases sccm SF6 16 25 33 Or 4 5 7 Pressure mTorr 75 75 75 Power Watts 65 75 85 Typical Etch Rate A min 1000 Notes This etch is designed primarily for removal of silicon nitride passivation films for failure analysis de layering applications although it can be used for other appropriate etches The process operates at low dc bias and is chemically driven consequently the etch is isotropic and also results in very low etch rates for materials such as SiO2 TEOS oxide PSG BPSG and metals such as Al and Au The etch rate is area dependent and lower etch rates will be found when etching whole wafers as compared to individual chips When etching large areas few square in optical emission can be used to determine the end point of the etch Emission at 337nm N2 is observed during etching and decreases at end point 2 13 Silicon Trench Etch Fluorine Mode Reactive Ion Etch RIE Pumps Mechanical or Turbo Susceptor Material Graphite or Ardel Temperature C 25 Electrode Size 6 8 11 Gases sccm SF6 12 20 25 O2 12 20 25 Pressure mTorr 100 100 100 Power Watts 135 155 180 DC bias Volts 150 150 150 Typical Etch Rate 5000 7500 A min Notes This process is load dependent This means the more exposed silicon there is the lower the etch rate The recommended mask is SiO2 instead
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