Dear Michael (or Haixin?),

I don't know of the particular resist that you're using, but in our lab
that we have the hotplate about 10-15 degrees hotter when using 1 mm
quartz substrates compared to 300 micron silicon substrates, in order to
get the same temperature on the top surface of the substrate (we
measured this directly). Also, we have a steel chuck on our mask
aligner, and when using transparent substrates like quartz we put red
tape on the chuck to stop reflections, or else the resist gets exposed
from the light reflected from the chuck which can affect the exposure
dose and can cause undesirable undercut profiles.

Hope that helps, it's not exactly a recipe but it might shed some light
on your problems.

Jason Milne
Microelectronics Research Group
The University of Western Australia



-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org] On Behalf Of Haixin Zhu
Sent: Wednesday, 19 November 2008 8:26 AM
To: General MEMS discussion
Subject: [mems-talk] AZ50XT single coat

Dear all,

I am trying to have 60um thick AZ 50XT on top of quartz substrate, and
having some issues with the pattern undercut and film stress, is there
anyone who can provide a working recipe since the protocol from the
vendor seems not working well.

Appreciate the help

Michael