You really have to do a process characterisation studies to arrive at the
stress levels you are looking for. It depends on the feature size, film
thickness and LPCVD process parameters. One my earlier works revealed a
compressive stress of 220 MPa for a thickness of 650nm of nitride. If your
nitride layer gets thinner the stress might still go up.

When you say your beams have to straight, you need to define the achievable
stress levels. Getting it down to a few MPa throughout the wafer is reallly
a challenge although you can control the stress levels to certain tens of
MPa by varying the process parameters.

Regards,
Prasanna

On Mon, Aug 17, 2009 at 9:34 PM, antwi nimo  wrote:

> still LPCVD will be able to do the trick.  you probably can try to an
> annealing process after the deposition process.  that can help.  but how
> thick should the nitride be? it depends what thickness of nitride you are
> looking for, for your beams.
>
> just a little help for you to consider.
>
> regards,
> Nimo

--
Thanks & Regards,
Prasanna Srinivasan