Robert,

>From the brief description you have given, it sounds as if you may have
a leak in your vacuum system somewhere, and moisture is leaking into the
process and reacting with the silane.  This will produce a brown
rusty-colored film.  You may want to do a leak back test on the system,
to check for excessive leaks.  Ideally the leak-back would be 0
mTorr/min, but a reasonable target would be <10 mTorr/min.

Best Regards,

Tim Watson
Microfabrication Technician
MicroMD laboratory
1381 Kinnear Road, Suite 100
Columbus, OH 43212
Tel: 614-688-8474
Fax: 614-688-3379
www.micromd.org





-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of
bob barker
Sent: Tuesday, November 25, 2003 3:56 PM
To: [email protected]
Subject: [mems-talk] Brown LPCVD Polysilicon


Can anyone tell me why my LPCVD polysilicon is brown and/or black?  I am
depositing it at 620 C and 300 mTorr with a flow rate of 50 sccm of
silane.  The inside of the quartz furnace tube is coated with silicon,
so I'm not sure the temperature inside the tube is really 620 C.  Do I
need to clean it?  If so, how do I do that?

Thanks,

Robert Barker





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