Here's one foolproof recipe for patterning sputtered metallization layers (on
silicon) as thick as 500-nm using image reversal with AZ5214E (no YES oven used)
and requires no dry etching.

Acetone+Methanol spin rinses followed by drying spin (you may also wish to do a
piranha clean first if stored in plastic chip cases for more than a month)

Dispense AZ
Spin at 4000 rpm 45 sec (1.4 micron)
Use razor blade to skim off excess PR near chip edges (if other than wafers) -
this prevents chip sticking to photomask during soft contact exposure!
Pre-bake 100 C 60 sec
Expose 320 nm @ 50 mJ (using MA-6 in soft contact mode => 3 micron lines are
easy).
Post-bake 117 +/- 2 C @60 sec
Flood Expose: 1 Joule at 365 nm AOI
Sputter up to 500 nm thick metal (I haven't pushed it to higher thicknesses)
Lift-off: Acetone soak 15 min, followed by 1-2 min sonication with acetone in
beaker floating in water bath of ultrasonicator

Thomas Wilson
Department of Physics
Marshall University