Ruilin,
       One way to handle this is to make the mask more hydrophobic.  With the
correct treatment the mask can be totally resistaphobic and SU8 will not stick.
Bill Moffat

-----Original Message-----
From: [email protected] [mailto:[email protected]] On
Behalf Of ???(Ruilin Zheng)
Sent: Tuesday, October 21, 2008 4:23 AM
To: [email protected]
Subject: [mems-talk] SU-8 layer stick to mask after exposure

Hello, everyone,

I met a problem in SU-8 process recently, the SU-8 layer stick to the mask after
exposure.
I rarely have this problem before. Two weeks ago, I applied an Omega UV filter
for the exposure step to filter out short wavelength UV light.
And this problem appear every time during exposure.
At first I think it may be caused by insufficient soft-bake dose, but after I
tried to prolong the baking time and use higher temperature, SU-8 layer still
sticked to the mask.
Does anyone have some ideas about this problem? Please help me out.

By the way, the photoresist is SU-8 2150 by microchem, will be expired at
Dec,2008.