SOI grating definition

Back to Process_Hybrid_Silicon.

Past Processes

Sweeper Vertical Grating Coupler Process - (ZEP:Anisol(2:1) Soft mask, limited to shallow ~150-200nm Si gratings, used in SWEEPER for gratings <100nm)

   Pre-clean: Remove native oxide and/or dielectric hardmask
       HF dip
   Ebeam PR spin coat (2:1 ZEP)
       ACE,ISO,DI   
       PEII - O2 Descum (100W, 300mTorr, 60sec)   
       Dehydration Bake (150C, 5min)   
       N2 Gun (1min)    Cools and cleans wafer
       Spin 2:1 ZEP (3000rpm, 30sec) - Recipe 5    ~225nm, Use a filtered syringe
       Pre-Exposure Bake (180C, 4min)    Cover hotplate top to prevent additional particulate
   Thermal Au Evaporation       
       Evaporate 11nm Au
   Ebeam Writing Conditions       
       4th Lens   
       Dose 350uC/cm2 (Please be aware this is pitch dependent, but has shown good results over a range of pitches if the substrate is not highly doped)
   Development       
       Remove Au in wet Au etchant    10s
       DI Rinse   
       N2 Dry   
       1:1 MIBK:ISO Development - 60s    Use a fresh batch
       9:1 MIBK:ISO Rinse - 15s    DO NOT RINSE WITH DI
       N2 Dry    DO NOT RINSE WITH DI
   Grating Etch       
       AFM etch depth calibration recommended   
       Single Step Bosch Etch Process - JTB_GR
       Rates:
       ~170nm/min w/o Sanovac 5
       ~141nm/min w/ Sanovac 5
   Strip ZEP (2:1)
       1165 Soak at 80C - 10min
       PEII - O2 Descum (100W, 300mTorr, 60sec)

Standard Hybrid Si Process

link to .xls

Process Development Summary

Dose/Duty Cycle Analysis with Proximity Effect Observations

File:2010-03-01 Grating Update.pptx

File:2010-12-07 Grating Update.pptx

Future Untested Processes

Sweeper Two Etch Depth Grating Process (UNTESTED)

   Oxide Hardmask Deposition - PlasmaTherm PECVD 
       50+50nm SiO2
       Add Si watch sample
   VASE Si Watch Sample - Note Oxide Height 
   Cr Deposition - Ebeam #1
       100nm - This is a value that has been calibrated, but there would be value in using 25nm to decrease the undercut
       Add a watch sample with orange vacuum tape in the middle
   Dektak the watch sample after removing tape
   Oxide Hardmask Deposition - PlasmaTherm PECVD 
       50nm SiO2
       Add Si watch sample
   VASE Si Watch Sample - Note Oxide Height 
   Ebeam Resist spin coat (2:1 ZEP)
       ACE,ISO,DI   
       PEII - O2 Descum (100W, 300mTorr, 30sec)   
       Dehydration Bake (150C, 5min)   
       N2 Gun (1min)    Cools and cleans wafer
       HMDS 5000rpm 30s - Let sit on chip for 30s before spinning
       Spin 2:1 ZEP:Anisol (3000 rpm, 30sec) - Recipe 5    ~225nm, Use a filtered syringe
       Pre-Exposure Bake (180C, 4min)    Cover hotplate top to prevent additional particulate
   Conductive polymer spin coat
       Aquasave (3000 rpm, 30sec) - Recipe 5
       Pre-Exposure bake (90C, 30sec)
   Ebeam Writing Conditions       
       4th Lens - 2nA  
       Dose 500uC/cm2 (Please be aware this is pitch dependent, but has shown good results over a range of pitches with a ~45nm undercut in the 100nm of Cr)
   EBL Development       
       DI Rinse - 60s Removes Aquasave   
       N2 Dry - Be gentle the resist can move under high pressure 
       1:1 MIBK:ISO Development - 60s    Use a fresh batch
       9:1 MIBK:ISO Rinse - 15s    DO NOT RINSE WITH DI
       N2 Dry    DO NOT RINSE WITH DI - Be gentle the resist can move under high pressure
   Microscope Inspection - 
   AFM Pattern Acknowledgement -
   Hardmask Etch - ICP#2
       O2 Clean - 10min
       2min season - ICP#2 recipe #104 - CF4/CHF3/02 - 5/35/10sccm  - 500Wicp, 50Wccp, 0.5Pa
       Oxide Nano Etch - ~80nm/min - over etch 25% (50s for 50nm) 
           ICP#2 recipe #104 - CF4/CHF3/02 - 5/35/10sccm  - 500Wicp, 50Wccp, 0.5Pa
   Strip ZEP:Anisol (2:1)
       1165 Soak at 80C - 10min
       PEII - O2 Descum (100W, 300mTorr, 60sec)
   AFM Pattern Acknowledgement - Save grating cross-sections confirm height with oxide thickness measured earlier
       Cr Etch - ~35nm/min - over etch 25% (3m45s for 100nm) 
           ICP#2 recipe #145 - Cl2/02 - ?/?sccm  - ?Wicp, ?Wccp, ?Pa
   AFM Pattern Acknowledgement - Save grating cross-sections confirm height with Cr and top oxide thickness measured earlier 
       Oxide Nano Etch - ~80nm/min - over etch 25% (100s for 100nm) 
           ICP#2 recipe #104 - CF4/CHF3/02 - 5/35/10sccm  - 500Wicp, 50Wccp, 0.5Pa
   AFM Pattern Acknowledgement - Save grating cross-sections confirm height with Cr and lower oxide thickness measured earlier top oxide should be gone.
   Grating Shallow Etch - Si Deep RIE Etcher (50nm)        
       Chamber Prep (no sample):
         O2 Clean - 30min - Click standby, then enter manual mode. 
           (the electrode temp must be with in bounds to enter standby mode)
            Load Clean wafer. Parameters 10C,30mTorr,He=10,Ar=10,O2=30,Power RF2=800
         2min season - BOV_J_01 - C4F8/SF6/Ar = 56/24/20sccm @ ICP/CCP = 850/18W
       Single step Bosch etch process - BOV_J_01 - C4F8/SF6/Ar = 56/24/20sccm @ ICP/CCP = 850/18W
           Rates: ZEP ~ 35-40nm/min, ~63-141nm/min w/ Sanovac 5    
   AFM Pattern Acknowledgement - Save grating cross-sections Cr mask will show a negligible etch so the Si depth should be clear.
   Add GRAT1 layer (Protects Sweeper gratings)
       Spin AZ4210 (4000rpm, 30sec)
       Pre-Exposure Bake (95C, 1min)
       Lithography - Pattern a window in the deep etch region 
           Litho Tool: GCA Stepper / Autostepper
           Exposure: 3sec / 1sec 
           Focus Offset: 0
           NO POST-EXPOSURE BAKE
           Develop (AZ400K 1:4 diluted, 2min(way over-developed)
           DI Rinse
       PEII - O2 Descum (100W, 300mTorr, 30sec) - Do not repeat this because this oxidizes the Cr and will enlarge the grating pattern
   Microscope Inspection - 
   Grating Finish Deep Etch - Etch the difference in depths (deep target (275nm) - shallow target (50nm) = 225nm)      
       AFM etch depth calibration recommended   
       Chamber Prep (no sample):
         O2 Clean - 30min - Click standby, then enter manual mode. 
           (the electrode temp must be with in bounds to enter standby mode)
            Load Clean wafer. Parameters 10C,30mTorr,He=10,Ar=10,O2=30,Power RF2=800
         2min season - BOV_J_01 - C4F8/SF6/Ar = 56/24/20sccm @ ICP/CCP = 850/18W
       Single step Bosch etch process - BOV_J_01 - C4F8/SF6/Ar = 56/24/20sccm @ ICP/CCP = 850/18W
           Rates: ZEP ~ 35-40nm/min, Si ~170nm/min w/o Sanovac 5, ~63-141nm/min w/ Sanovac 5    
   Strip PR
       1165 Soak at 80C - 10min
       PEII - O2 Descum (100W, 300mTorr, 60-120sec)
   AFM Pattern Acknowledgement - Save grating cross-sections from AFM test structure shallow and deep  
       Cr Etch - ~35nm/min - over etch 25% (3m45s for 100nm) 
           ICP#2 recipe #145 - Cl2/02 - ?/?sccm  - ?Wicp, ?Wccp, ?Pa
   AFM Pattern Acknowledgement - Save grating cross-sections from AFM test structure shallow and deep  
   BHF Dip
   AFM Pattern Acknowledgement - Save grating cross-sections from AFM test structure shallow and deep  
   SEM - Save top down SEMs for different locations and different grating types.