The HF etch of silicon nitride depends strongly on what type of silicon
nitride is exposed. LPCVD silicon nitride, both stoichiometric and
silicon-rich, etches slowly. PEVCD silicon nitride is really SixNyHz,
containing a lot of hydrogen, and can etch rapidly.

   --Kirt Williams

-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf
Of Morrison, Richard H., Jr.
Sent: Wednesday, June 08, 2011 3:24 AM
To: General MEMS discussion
Subject: Re: [mems-talk] Ti wet etch with selectivity to Si3N4

You should be able to etch Ti on Nitride, the HF etch rate of Nitride in 10%
HF should be very low and 1000A of Ti will etch in 40 seconds. The mixture
of NH4OH:H2O2:H2O (1:1:5) will etch Ti very fast and it will not etch
Nitride at all. However, resist will not stand up to the mixture.

Rick Morrison
Senior Member Technical  Staff
Acting Group Leader Mems Fabrication
Draper Laboratory
555 Technology Square
Cambridge, MA  02139