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