I know of no rie type process that will give you the selectivity numbers you are
requesting even low pressure chlorine type etching of nitride I don't think will
give those results. Only hot phosphoric acid in a reflux bath can obtain those
selectivity numbers and you can't use photoresist as a pattern since it will go
away. Bob Henderson

-----Original Message-----
From: iamacalbear@hotmail.com
To: mems-talk@memsnet.org
Sent: Wed, 25 Apr 2007 11:29 AM
Subject: [mems-talk] Nit and Oxide etching.


hello,

I am trying to find a way to etch Nit faster than silicon oxide layer (under the
same conditions).
I am hoping get 50:1 type of etching ratio (more nitride removal than the oxide
layer). We have tried a couple of things but nothing has really panned out...any
suggestions?

Mike