Has anyone had significant experience etching nitride windows on silicon using
a KOH etch? I am trying to create very thin (4200 Angstroms) Silicon Nitride
windows, but my yield goes below 50%. My KOH bath is composed of KOH pellets
and water at 80 degrees C. Are there any ways to reduce wrinkles in windows? I
currently dip my wafers in cool DI water for 10 minutes and then dry them in a
120 degree oven with my pits opening upward (i.e. window surface downward).

Any help would be great. Thanks.

-- Kishan Gupta
UC Berkeley