nLOF 2020 Spin & Bake

  1. Clean PR off mask (if needed):
    1. Acetone
    2. IPA
    3. DI SRD
    4. O2 RIE 3min 100 W Technics Etcher
    5. DI SRD again (so PR doesn’t stick to mask in contact mode)
  2. Clean and Dehydrate Si Wafer immediately prior to spinning
    1. O2 plasma 200W
    2. 2 min
    3. Technics RIE Etcher
  3. Spin CEE 100 Spinner
    1. Use chuck that is slightly smaller than substrate
    2. Coat inside of spinner bowl with aluminum foil for easy cleanup after spinning
    3. HMDS 3000 rpm 30 sec
    4. nLOF 2020 3000rpm 60 sec
  4. Hot plate bake wafer 110C 1 min (Prebake)
  5. Suss Aligner
    1. Hard N2 contact
    2. 15 sec expose 7mW/cm^2 (~105 mJ/cm^2)
  6. Hot plate wafer post exposure bake (PEB)
    1. 110 C
    2. 2 min
  7. Develop 300MIF 3 minutes
  8. DI rinse 2 min, then place inside spin rinse drier (SRD)
  9. Microscope inspection and measurements
  10. Liftoff deposition
    1. Sputter
      1. Keep total film thickness less than 1/3 of photoresist height (PR ~2um, so film max ~670nm)
      2. Denton 80: keep power less than or equal to 50W
      3. Denton 635: keep power less than or equal to 100 W
      4. TMV: keep power less than or equal to 100 W
    2. E-gun: Keep temperature readout below 40C
  11. Liftoff in Lauda bath
    1. Heat Kwik strip to 80C
    2. Place wafer inside thin vertical wafer dipper and submerge in Kwik strip for >2 hours or until all nLOF photoresist is dissolved
    3. Isopropyl Alcohol (IPA) dip in IPA tank
    4. Ultrasonication in water if necessary (do not allow wafer to dry until all the film is lifted off)
    5. SRD