Hi Dayong:
I think somebody has discussed this problem for 10um PSG. You can check the
archive of  MEMS talk.
BR
Bob

 wrote:
I want a sacrificial layer with a thickness about 4 micro. Because the commonly
used PSG is 2 micro, i wonder whether PSG can be desposited with a thickness of
4
micro in LPCVD equipment? If YES, anybody can tell me the detail or tip of
deposition process? I mean how to protect the PSG against stress induced crack?