Hi
If you are using positive resist, it might be because the developer attacks
aluminum so you get different reflections from areas that were exposed
before.
Shay

-----Original Message-----
From: mems-talk-bounces@memsnet.org [mailto:mems-talk-bounces@memsnet.org]
On Behalf Of Sreemanth M Uppuluri
Sent: ה 20 יולי 2006 23:07
To: mems-talk@memsnet.org
Subject: [mems-talk] Al Thin Film & Contact Lithography!

Hello Everyone,

I am trying to perform contact lithography experiments and for my
experiments I am using patterns defined in Aluminum thin films as the mask
features (in other words the mask is made of Aluminum) and g-line
photoresist for the resist. Now for the first few runs I get features as
expected in the resist after lithography. However after the first few runs I

see diffraction occuring that is causing the patterns in the resist to be
much larger than the patterns on the mask. I tried using solvent clean to
remove any trace photoresist that may be sticking to the mask. But it
doesn't help. I am not sure if there are any other factors causing the
problem.

Please let me know if you have any ideas for solving this problem.