Robert,

a late reply, I've been travelling.
Pinholes in nitride are always a concern. Stacks of Nitride/Oxide/
Nitride have been used. Also, reactively sputtered Tantalum Pentoxide
has been successfully used to protect pressure sensors in aggressive
media, see e.g. J.Microtech. MicroEng. 9,1999, p.113-118

best regards,
klaus


             (TEEL)        Tokyo Electron Europe Limited
                     PVD Process Support  (ex MRC)
Klaus Beschorner                   Tel +49-7033-45683
Drosselweg 6                       Fax +49-7033-45631
71120 Grafenau, Germany            Mobile +49-174 315 7754



>>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