If one side of the wafer has 1um PECVD nitride, nitride will prevent
oxidation.
Duan, do you mean get 0.4um oxide from the backside
of the wafer?


> Hi Duan,
>
> One sided films can do that to you.  I'm assuming it was one sided. If
> not,
> was it a prime wafer to start with?
>
> Jeff
>
> -----Original Message-----
> From: Duan [mailto:brokenspoon@gmail.com]
> Sent: Thursday, October 06, 2005 7:51 AM
> To: General MEMS discussion
> Subject: [mems-talk] silicon nitride stress problems
>
> Hello all,
>  I have encountered some problems with the stress in thin films.
> What I have done is that, I first got 1 micron PECVD silicon nitride on a
> 6
> inch silicon wafer(400 um thick), then I put it in the oxidation furnace
> at
> 1100 degree to get 0.4 um oxide film. After this, the wafer was bent very
> much, which was flat before oxidation. I don't know what the reason is. So
> could someone kind enough to tell me why and possiblly tell me the way to
> get rid of that. Any comments or literatures are quite appreciated
>
>