Dear MEMS Experts
        Hello! I am trying to make diaphragms of SiO2 and Si3N4. The SiO2
is dry grown on Si and is 8000A. Si3N4 ( on a different sample)is LPCVD
deposited (1500A) on a grown buffer oxide layer(500A). I am releasing
these diaphragms by opening trenches along four sides of the diaphragm
(diaphragm remain hinged to four corners) and subsequently bulk
micromachining in KOH/TMAH.
        The diaphragm breaks from the corners (where it is hinged) in case
of Si3N4. Whereas in case of SiO2 in breakage take place in the diaphragm,
in front of hinge.
        This happens when sufficient release has taken place.

I am suspecting the stress is making it. Any suggestion is welcomed.

Sincerely yours

   RAJKUMAR
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