Michael,
            Process input from years ago.  One of the difficult to etch =
layers on one layer I had years ago at AMD was 17,000 Angstroms of =
thermally grown Silicon Dioxide.  It took 15 minutes in buffered HF to =
etch it but we consistently had problems with delamination.  Especially =
if there was a long time of exposed surface before we applied the =
resist.  After switching to vacuum vapor prime we found no problems with =
surfaces that sat around for weeks after vacuum vapor prime.  Bill =
Moffat.=20

________________________________

From: [email protected] on behalf of Michael A Gingras
Sent: Thu 11/15/2007 9:13 AM
To: [email protected]
Subject: [mems-talk] Best resist for HF etching



Hello,

Me and my colleagues are trying to etch a 4 micron Pyrex layer with HF =
using photoresist as a mask. We've seen delamination of the mask as seen =
by others. We are currently using a Shipley 7 micron resist and 4:1 =
HF:H2O etch.

Any recommendations on the best resist and HF concentration to help us =
get the whole film etched before delamination? Current the Pyrex is =
etching about 300A/s, so we'd need something that would last 2-3 =
minutes.

Thanks
-Mike