First, 250 K-Ohm cm seems like an unrealistically high value. I've seen
silicon up to 12 KOhm-cm, and have used material up to 6KOhm-cm. Looking at
the web site, they don't actually seem to produce this value - it might just
be the theoretical resistivity of pure silicon with no dopants that they are
quoting.
There are other suppliers of high-resistivity silicon, for example wacker
and topsil.
Next, I've heard (but can't say for sure) that if you grow a thermal oxide,
the resistivity will never be higher than a few thousand ohm-cm when your
done, no matter how good it was to start. Any thermal treatment will
diffuse some impurities into the wafer, depending on the time and
temperature of the treatment.
If you need to end up with 2000 ohm-cm, your probably fine. If you need to
end up with 6000 ohm-cm, you will need to be careful about your thermal
processing and may have problems. If you need 250000 ohm-cm, your probably
out of luck.
David Nemeth
Senior Process Engineer
Sophia Wireless, Inc.
14225-C Sullyfield Circle
Chantilly, VA
Ph: (703) 961-9573 x206
Fax:(703) 961-9576
-----Original Message-----
From: [email protected] [mailto:[email protected]]On
Behalf Of Fred Hussain
Sent: Monday, May 20, 2002 6:47 AM
To: [email protected]
Subject: [mems-talk] Highest resistivity silicon?
Dear all,
I am looking for silicon substrates which can be machined using conventional
MEMS type processes, but at the same time are highly insulating. I've found
a web page with silicon of 250Kohm-cm resistivity -
http://www.tydex.ru/materials/materials2/Si.html.
Does anybody:
have any experience of working with such materials?
know of any issues, for example the stability of the resistivity with
temperature?
micromachined it without any major issues?
know of any suppliers?
Thanking you in advance.
Regards,
Fred.
--------------------------------------------
Dr Fred Hussain
The Technology Partnership plc
Melbourn Science Park
Cambridge Road
Melbourn
Royston
Hertfordshire
SG8 6EE
Tel: 01763 262626
Fax: 01763 261582
www.ttpgroup.com
---------------------------------------------
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