Eric Sundholm's Recipe

WARNING: Manufacturer's recommended softbake is 115 C for 60 s on a hotplate. The manufacturer does not recommend baking inbetween exposuring/developing. Such bakes are only used for the more modern 'chemically amplified photoresists'. See Ethan for the 1800 series datasheet.

Eric is an EE grad student who used to TA the ECE418 class on semiconductor processing & has made lots of devices in the Owen clean room.

SiO2 Wet Etching

  • Spin 1818 photoresist at 3000 rpm for 30 seconds (~2.5 um layer)
  • Bake at 85C for 2 minutes
  • Expose for 6-8 seconds
  • Bake at 85C for 2 minutes (skip this step for lift off)
  • Develop 15-25 seconds in diluted 351 developer (4 DI water : 1 developer) (Develop 8-10 seconds for lift off)
    • Rinse quickly & 'like crazy' afterward (important)
  • Bake at 85C for 5 minutes (skip this step for lift off)
    • Eric says 5 minutes may be too long. Watch for cracks in the photoresist around the edges, cracks mean the bake is too long.

More Advice

  • For liftoff, apply metal deposition layer quickly after development. Don't wait longer than a few hours.
  • When cleaning masks rinse with Acetone, then IPA & quickly blow dry with N2 gas. This leaves less residue than rinsing with IPA & then DI water.

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