Ivan,
     One comment if you decide to pursue positive photo resist as the chosen
layer.  Using either image reversal or silylation both simple chemical
treatments produce a resist that resists heat flow.  One colleague used image
reversal to produce 0.5 micron diameter pillars in resist 1.2 microns high.  He
then deposited TEOS at 405 degrees around the pillars with no thermal
degradation of the resist.  Silylation which diffuses a silicon rich layer into
the exposed resist, about 3,000 angstroms deep works even better.  I like to
think of it as our equivalent to an M@M.  A soft resist center with a hard
crispy shell of Silicon that holds the defined resist in place.  I can send you
papers on both if you have any interest contact me.  Bill Moffat

-----Original Message-----
From: Ivan Shubin [mailto:[email protected]]
Sent: Wednesday, April 09, 2003 12:15 PM
To: [email protected]
Subject: [mems-talk] Photosensitive passivation layer


Dear colleagues:
I appreciate your comments on options available to us for photosensitive
passivation materials.
We have difficulty resolving 2um features on the Durimide 75xx series
polyimide  (or BCB) that is 4-6um thick.
I know some use PMGI or other photoresists when it comes to a resolution. I
wasn't sure although if photoresist passivation layer would behave well
under temperatures as high as 350'C, what achievable dark currents are
under high fields and how well they do under reliability/long term
stability tests. Let us know, please, if any of you have successful
experience with application of photoresists for passivation or any other
material for that matter.
Thank you very much.

Ivan Shubin,
Research Scientist,
ECE Department, University of California at San Diego
La Jolla, CA 92093
ph. 858-534-6570
fax 858-534-0556



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