PMMA lift off 50 60 nm feature size, 110 nm pitch - NanoLabStaff/nanolab GitHub Wiki
PMMA lift off 50 60 nm feature size, 110 nm pitch Protocol
by Simen Martinussen ([email protected])
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Spin coat PMMA (~80 nm)
200K PMMA A3.5 3500rpm for 120s Ramp: 1000rpm/s for 3.5s -
Soft bake
180°C for 60s -
Spin coat PMMA (~120 nm)
950K PMMA A4 3000rpm for 120s Ramp: 1000rpm/s for 3s -
Soft bake
180°C for 60s -
Exposure
Features: dots HV: 20kV Current: 42pA Dose: 6 fC Settling time: 100 µs -
Develop
9:1 IPA:DI water for ~15s (gently stirring) Rinse in DI water for >30s Dry with N2(g)
Lift-off successfully performed for evaporated 5 nm Ti/30 nm Au. Lift-off performed by immersion in acetone followed by acetone airbrushing.
Process writing speed with 100 µm write field: 5 hours and 45 minutes per square mm. EBL software stability problems was a serious issue for areas over 500x500 µm.
Pitch can possibly be reduced to 90 nm, but defocusing over large distances might be an issue. Settling time can possibly be reduced further as well.
Resist thickness values may be significantly inaccurate.
