The sputtered gold may thermally affect the PMMA.  Then you are exposing
through the gold?  Then removing gold and developing.  Are you aiming
for 1) A standard technique where you put down gold then resist then
pattern resist and etch patterned gold.  Or 2) A lift off technique
where you put down resist, pattern then, then put down gold.  Then
develop to remove the resist with gold on top leaving gold in the
developed clear areas?  Bill Moffat

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of li shifeng
Sent: Wednesday, November 26, 2008 8:50 AM
To: [email protected]
Subject: [mems-talk] EBL on the glass (more details)

Hi, All

I posted a message about EBL on the glass substrate couple days ago. I
got several valuable replys. In order to get more help, I would like to
talk a bit of detail about my case.

I try to write patterns on the glass substrate. In order to get rid of
surface charge problem, I sputtered 5nm gold on the top of PMMA. I used
30KV ebeam to expose the patterns. Meanwhile, I used multiple dosage to
find the optimal exposure parameters. The dose factors I used are 1,
1.5, 2.0, 2.5, 3.0. After exposure, I have to strip gold layer to
develop PMMA.  I put some large features in the design so that I can
easly identify the position of the patterns. But, after development, I
cannot find any patterns on the glass substrate. I may believe this
maybe due to underexposure because the layer of gold may absorb some
electrons during exposure.

I am looking for any experiences similar like my case or any working
receipe to share.