Hi Shah,

As long as you consider a good ratio of metal/resist, you can easily lift it
off. The best condition is ratio 1:10 and you can lift it off in less than one
minute even without ultrasonic bath. So, My suggestion is that to ensure a good
ratio, use a thicker resist (lower spin speed or for example use SPR-7). Also,
make sure you measure the resist thickness properly. Another point is that you
can immerse the wafer in Toluene for 3 minutes after lithography to make the
resist edges sharper (it is better for small features).

Good lock,
Reza Rashidi

________________________________
From: "Shah, Forum N" 
To: General MEMS discussion 
Sent: Tuesday, July 14, 2009 11:06:37 AM
Subject: [mems-talk] Correct way of doing Lift-off process

Hello everyone,

I am trying to do the lift-off process for the first time but am not able to
achieve it. Its been over 24 hrs that the wafer is immersed in acetone but the
gold film is not leaving the Si substrate.

Details of the process are:
I have spun SPR 220-3 on a SI wafer near 3 micron of a thickness. After exposing
and developing it, I sputtered 100 angstrom gold film.

Please guide me on how to do a lift off process. And if acetone is sufficient
for doing lift-off or do I need any other solvent or chemical?

Thanks
Forum