I used many distinct recipes for my ITO/glass substrate (single layer of PMMA) but I can only partially remove the photo-resist, and gold mostly covered entire sample and I have my pattern appeared only on the edges of my pattern.

I tried different exposure dosages (e-beam lithography) from 300uC/cm2 to 500uC/cm2 , different developing times (MIBK:IPA = 3:1 developer), different soft baking temperatures (150-190C) and time, and finally different spin coat rpm for PPMA ( 2000rpm(PR thickness 290nm) to 6000rpm(PR thickness 180nm)), none worked yet!

I tried warm acetone and also PG remover soaking, both result the same!!

I used e-beam evaporator (I tried high (0.6-1 A/s) and small depo rate(0.1A/s)) and also thermo-coating machine (depo rate 1.5 A/s), the problem is still there. The result looks better when e-beam evaporator was employed!

Surprisingly, I got a better result for thinner photo-resist (6000rpm-180nm) and 2 minutes of developing and two steps e-evaporator deposition process (10nm at 0.1A/s and 90nm at 0.7 A/s).

P.S: I measured the thickness of deposited gold with alpha-step profiler, SEM and AFM (it is 100nm).

I would appreciate if you would help me to figure this out, thanks.