Photolithography Recipes
az2020 Photoresist on Lithium Niobate
Spin 20-25 drops @ 3000rpm for 1min
Soft bake in the oven in a glass dish @ 100C for 15 min
Expose on North aligner for 10 sec
Develop for ~30 sec
Hard bake for 15 min in oven in a glass dish @ 100C
az2020 Photoresist Bake Time for Lithium Niobate
Positive Photoresist
Spin HMDS @ 3000 rpm, 1min
Spin AZ3330
Bake at 110C for 1m30s (120C works fine)
Expose on south aligner for 11 sec, hard contact
Develop for ~40 sec
Hard bake for 1 min
Negative Photoresist
Spin HMDS @ 3000 rpm, 1min
Spin AZ2020
Bake at 110C for 1 min
Expose on south aligner for 25 sec, hard contact
Hard bake for 1 min
Develop for ~90 sec
SU8-10 Recipe
spin 500rpm @ 100rpm/s 6s, 4400rpm @ 1200rpm/s 60s, 6000rpm @ 6000rpm/s 2s; or just whatever program is on the spinner
Soft bake, 65C 10min → 95C 10min → 65C
Exp 30s on filtered aligner;
Hard bake, 65C 6min → 95C 6min → 65C, Dev ~45s
RT → 200C, 200C 10min → 65C
RT→250C, 250C 5min → 65C
NR8 Resist
Get a clean silicon wafer.
Spin HMDS
Spin NR8 at 3krpm
bake at 100C in the oven in a glass dish for 7minutes
below is the characterization of the photoresist NR8. Going from right to left of the 4 different areas we have 10 sec exposure, 20 sec, 30 sec, 40 sec.
for lithium niobate, process is simular, except i baked it for 15 min and i did 6 different areas. going from left to right we have 60 sec, 50, 40, etc to 10 seconds. (click for better view)
Negative Resist
use az2020, ~20-30 drops, 3000 rpm for 1 min, bake at 110 for 1 min. Expose mask for ~7-10 sec. Bake for another minute. Develop for 1 min. Check under microscope before cleaning off photoresist or etching metal.
Bake times vary in the oven.
Device Prep
Adding Resist
Spin LOR 3A onto Wafer (Really douse the thing) @ 2000 RPM for 1 min
Bake 150 degrees for 15 min
Spin PMMA onto Wafer @ 3000 RPM for 1 min
Bake 150 degrees for 15 min
Spin VERY SMALL AMOUNT of Aquasafe onto wafer (ONLY IF LiNbO3) @ 1000 RPM for 1 min
NOTE: for spinner, use program S. you can rewrite that. Also, make sure nobody turns off the vacuum. (if anybody to your left is reaching awkwardly behind the wafer development bench, stop them).
Development
Rinse off Aquasafe with Water [use spray] (ONLY IF LiNbO3) and Air spray dry
Dip sample into 1:2 MIBK:IPA for 2 minutes (hold and move back and forth gently)
At 2 minutes, begin to rinse with IPA
Dry using Air Spray
(LOR only) Dip sample into MIF 300 for 4 seconds
At 4 seconds, begin to rinse in water
Air Spray dry
Liftoff
Put samples into NMP bath
Place large water dish on hot plate at 90 degrees
Insert buffer (Piece of plastic)
Put NMP container with sample onto plastic buffer
Cover and let sit until Al liftoff is complete (Overnight)
Remove sample from NMP (shoot with pipette water gun to clean off large chunks)
While still wet, insert into Acetone bath
Sonicate for 10 seconds
Or brush with a cleanroom swab
Rinse in IPA
Air Spray dry