I like Avi's input more than mine.  I gave a quick answer and did not read 150
C.  Vacuum Vapor Prime protects against long harsh etches but I have not run
high temperature as well.  It may work if you want to test it, send wafers.
Bill Moffat

-----Original Message-----
From: avilaker@gmail.com [mailto:avilaker@gmail.com]
Sent: Wednesday, July 27, 2011 9:57 AM
To: Bill Moffat; General MEMS discussion
Subject: Re: [mems-talk] Si3N4 etching using H3PO4

If possible try a hi temp oxidation of the nitride, pattern resist, quick boe
etch then etch th nitride.