Gu,

We use CF4 gas in a RIE system to pattern nitride.

There are some sections about wet etching of Si3N4 in Wolf and Tauber's book
and in Runyan and Bean's book and in Ghandi's book.

But you are correct, getting resist to last may be a problem. Ghandi suggests
an intermediate molybdenum film. Pattern that with resist and then transfer it
to the nitride. Others suggest an intermediate oxide film.

If you get any good feedback, please forward them to me.

Dr. Kevin M. Walsh
Electrical Engineering Department, Speed Scientific School
University of Louisville, Louisville, KY 40292
(502) 852-0826
Internet address: kmwals01@starbase.spd.louisville.edu