A possible answer.  IBM developed a process incorporating plasma and HMDS in
the same system to deposit various compounds of HMDS.  It was a thick think
many microns of sticky goop that was totally Hydrophobic.  The concept was for
protection of Hybrid circuits in a submarine.  The part had to protected for
ever against moisture but the material had to be easily removable.  I ran some
experiments at that time combining one our plasma systems with a HMDS delivery
system.  The thick goop was totally Hydrophobic, removable with a simple
eraser, but if undisturbed remained hydrophobic for ever.  Down side the
equipment I was using had the goop deposited every where and was difficult to
clean.  Let me Know if I can help to find original IBM patents etc.  Bill
Moffat

-----Original Message-----
From: Robert Dean [mailto:rdean@Eng.Auburn.EDU]
Sent: Wednesday, June 05, 2002 8:11 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] SiN passivation problem


>Hello,

I have a MEMS sensor that has aluminum traces covered with 0.4um of
silicon-nitride, for passivation, that must operate in a moist-salty
environment.  The part has failed, and I suspect that the moist-salty air
has permeated through the SiN layer and damaged the aluminum traces
underneath.  Any suggestions?


Robert Dean

Research Associate IV
Center for Advanced Vehicle Electronics
Auburn University
200 Broun Hall
Auburn, AL 36849

Voice: 334-844-1838
Fax:   334-844-1898
Email: rdean@eng.auburn.edu
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