I suspect your photoresist isn't being etched.  It's probably just
falling off.  However concentrated HF does seems penetrate photoresist.
BOE is ok.  I've gotten around this problem in the past by sputtering
~1K Angstroms of Cr on the glass before applying the resist.  The Cr
also makes a good mask if you want to RIE the glass.

Roger Shile

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Rupesh Sawant
Sent: Thursday, March 02, 2006 8:14 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] photoresist adhesion on soda lime glass

I am using a positive photoressit AZ P4620 for making a soft mask on
glass
slide. Usage of HMDS is not assuring me a good adhesion of photoresist
on
glass surface. The photoresist is getting etched in 5 min after I keep
the
slide in concentrated HF. My main aim is to get 20u microchannel in the
glass slide. Which procedure will guarantee me a strong adhesion which
can
make the photoresist soft mask to withstand concentrated HF for 30 min?.
The
thickness of my photoresist soft mask if 6.5u.