Hi,
Do you use double layers of PMMA with different molecular rate?
If so, you should be able to lift off even withouth ultrasonic.
Also, you should not deposit Nickel thicker than first PMMA layer.


-----Original Message-----
From: "madhav rao"<madhavrrao@yahoo.co.in>
To: mems-talk@memsnet.org
Cc:
Sent: 07-05-10(¸ñ) 11:02:41
Subject: [mems-talk] Liftoff
Hi,
I was trying liftoff of PMMA resist. I had
deposited Nickel on PMMA, which is exposed. The
pattern was of 100nm scale. However even after 3 hours
of Ultrasonic Acetone Liftoff, I was not able to get
complete liftoff. I used sonic bath at 40C. If any one
knows to do liftoff at faster rate, please let me know
the procedure.