Dear Kishang
The wrinkles suggest that you have a stress in the nitride. either internal
and/or
because of the TCE mismathc with the substrate.
Shay

kishang wrote:

> 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
>
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