Balaji,
       The problem is that you are wetting the quartz and the HMDS reacts with
the hydrogen in the moisture on the quartz surface.  Partial cure is a very
good dehydration bake and a very fast move to spin on HMDS.  At a previous
company I had a problem layer with 17,000 angstroms of thermal Silicon Dioxide
with a 15 minute BOE.  If we waited over 4 hours for the HMDS spin the resist
lifted off.  The total cure is vacuum vapor prime, when we put this in we did
the following test.  35 wafers with thermal silicon dioxide, ran through
H2SO4/H2O2 to emulate a rework and get the wafers moist.  Then we vacuum vapor
primed all 35 wafers and left them in a work station exposed to room air.
Every 24 hours we coated 5 wafers and at the end of 7 days took all 35 wafers
and processed them together.  Soft bake, expose, develop, hard bake and etch.
Not a single problem with the 7 day old wafers.  The act of vacuum vapor
priming dehydrates the wafers under vacuum and while still in a vacuum the
prime takes place.  This produced a Hydrophobic wafer that resists moisture
attacks for weeks.  Let me know if you have any further adhesion questions, or
if you want to test vacuum vapor prime.  Bill Moffat

-----Original Message-----
From: Balaji Lakshminarayanan [mailto:lakshmin@eng.usf.edu]
Sent: Wednesday, July 03, 2002 5:04 AM
To: mems-talk@memsnet.org
Cc: mems-talk-admin@memsnet.org
Subject: [mems-talk] Problems with liftoff(on quartz)


Hi,

I am having problems with developing photoresist on quartz wafer. The
photoresist is not sticking to the quartz. Has anyone experienced similar
problems. In particular, with AZ 5214E which i want to use for patterning
metal using liftoff. The procedure that i followed is

a) 1.50 HF dip for 15sec
b) spin-on HMDS+AZ5214
c) soft back @ 90C/60sec
d) Expose for 8sec
e) Hard bake for 110C/45sec
f) Flood expose for 85sec.

I followed the above procedure on glass and it worked well. Any help on the
same will be appreciated

thanks

bala
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