Hi

Sputtering will always cover the side wall. An evaporative process is
required for clean lift off.

Proper resist processing (a number of ways to do this) to achieve a
negative edge profile is also required for clean lift off.

But with 3um SPR resist and only 100A Au, soaking in acetone ought to at
least get the resist and gold off, at worst resulting in imperfect edges
due to missing the above two points.

So, are you sure you have only 100A Au?

Did the resist see temperature above 120C?

Excessively thick Au, or permanently baked resist, would give the result
you describe.

Good luck,
Linas.

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Dongxiao Li
Sent: Tuesday, July 14, 2009 2:36 PM
To: General MEMS discussion
Subject: Re: [mems-talk] Correct way of doing Lift-off process

Hi,

The aspect ratio seems ok, so you may need to check the sputtering
direction. If the gold was not sputtered normally on the PR, the side
wall was also possibly covered by the gold. Thus it was difficult to
lift off PR in acetone.

Dongxiao