Variations are caused by variations in atmospheric humidity.  Vacuum
vapor prime.  Vacuum dehydrates totally.  HMDS vapor reacts with
Hydroxyl ions on wafer and creates an inorganic molecule/organic
molecule bridge. Perfect resist adhesion always.

Bill Moffat
________________________________

From: mems-talk-bounces@memsnet.org on behalf of madhav rao
Sent: Fri 8/15/2008 10:39 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Photolithography - Resist peeling

Hi,
       I am experiencing a problem in patterning on silicon-di-oxide =
wafers; I am using SHIPLEY 1818 resist to get a thickness of 2.5 micron; =
6 seconds of exposure time. After developing for 60 seconds, I observe, =
the resist layer peels off; leaving no patterns on the wafer. Also I had =
soft-baked the resist at 95 C for 2 minutes in hot-plate.
This seems strange to me, as a month ago, I had successfully transferred =
the patterns on to silicon-di-oxide wafers.
I am using mylar film masks.
Please let me know, if any one had experienced similar problems before; =
and if so, could you let me know suggestions to solve ?

Thanks

Regards,
Madhav Rao,
Graduate student,
University of Alabama.