I thought there was a concencus that stoichiometric LPCVD films of
silicon nitride have high tensile stress (~1GPa). Nitride films with
compressive stress are more likely deposited using PECVD.

Michael P.
The MEMS Exchange

Dave Kharas wrote:
> The wrinkling you're seeing in the silicon nitride
> is most likely stress. If you're depositing a 4000A
> thick stoichiometric LPCVD nitride you will definitely
> have a compressive stress 300MPa and up, 4000A is on
> the thicker side as well.