Hi

If your dose is not proper you may not get the patterns on PMMA.
You may try the gold film at the bottom of PMMA  expose the PMMA at various=
 doses and  get your  correct dose first .
Then use this dose by keeping the gold layer on top of PMMA.

Good luck.
Indusekhar

________________________________

From: li shifeng [mailto:david_lee77@hotmail.com]
Sent: Wed 11/26/2008 10:19 PM
To: mems-talk@memsnet.org
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 s=
everal valuable replys. In order to get more help, I would like to talk a bi=
t of detail about my case.

I try to write patterns on the glass substrate. In order to get rid of surfa=
ce charge problem, I sputtered 5nm gold on the top of PMMA. I used 30KV ebea=
m to expose the patterns. Meanwhile, I used multiple dosage to find the opti=
mal 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 lar=
ge features in the design so that I can easly identify the position of the p=
atterns. But, after development, I cannot find any patterns on the glass sub=
strate. I may believe this maybe due to underexposure because the layer of g=
old may absorb some electrons during exposure.

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

Thanks!