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Eric Sundholm's Recipe

Eric is an EE grad student who used to TA the ECE418 class on semiconductor processing & has made hundreds of devices in the Owen clean room. His advice should be heeded.

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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