Biggest difference is that BCl3 and SiCl4 are mainly used for etching Al. CF4
will not etch Al and is usually used in etching oxides and nitrides.  What
material are you trying to etch?  This will really determine what gas you should
use.

-Dave Marx

-----Original Message-----
From: mems-talk-bounces@memsnet.org
[mailto:mems-talk-bounces@memsnet.org]On Behalf Of Oray Orkun Cellek
Sent: Monday, September 20, 2004 9:11 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] RIE gases


Dear Mems-Talk users,

For safety reasons we plan to establish an RIE system that uses safe
CH4/H2/Ar plasma for etching GaAs and other compund semiconductors.

I wonder what is the disadvantage of this chemistry when compared to
the popular and toxic BCl3 and SiCl4 ?

Can you compare these in terms of etch rate and isotropy for an
ordinary RIE system ?

Does CH4/H2/Ar really demand RF supply systems like ICP or ECR ?

Thank you in advance,

Best Regards,

Oray Orkun Cellek
Research Assistant, Ph.D. Candidate
Electrical & Electronics Engineering Department
Middle East Technical University
06531
Ankara, Turkey
e-mail : o.o.cellek@ieee.org
Tel : +90 312 210 4579
Fax: +90 312 210 1261
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