Jeff,

      The real answer is any of them it depends upon the design of the plasma
chamber.  If a capacitive system, two plates produce the plasma usually the
plasma flows down stream through a grounded plate, electrons, get deviated to
the ground grid and only ions attack your part.  No electron damage, but low
frequency, as high frequency looses power in a capacitive system. Best frequency
is a low frequency below 100 KH/Z.   If you have a barrel system you wrap a coil
arround it and you have an Inductive system.  Best frequency is a higher
frequency like 13.54 MH/Z.  If you want to use a single wafer system and just
fire in the energy a microwave works well 2.54 GH/Z is a common industrial
microwave frequency.  It all depends an what you wish to do with the plasma when
you have formed it.  Email direct and I will go into more detail. Look into the
reactive impedance of a capacitor and an inductor.

Bill Moffat C.E.O. Yield Engineering Systems.

________________________________________
From: mems-talk-bounces+bmoffat=yieldengineering.com@memsnet.org [mems-talk-
bounces+bmoffat=yieldengineering.com@memsnet.org] on behalf of Wolinski, Jeffrey
P [JPWolinski@GCC.EDU]
Sent: Monday, February 20, 2012 9:23 AM
To: mems-talk@memsnet.org
Subject: [mems-talk] Frequency for oxygen plasma cleaner/etcher?

Hi,

When purchasing an oxygen plasma cleaner/etcher, what's the optimal frequency?
I've seen units available with 50 kHz, 100 kHz, 13.56 MHz, and 2.45 GHz.  I
primarily intend to use it to remove photoresist (AZ P4620) from 2" diameter Si
wafers containing Cu and Au structures.  I may also want to use it in the future
for parylene removal and Si3N4 etching (using CF4 + oxygen).

Any comments on the best frequency?  Some vendors have told me that 13.56 MHz is
best for PR removal but the yieldengineering web site recommends 50 kHz.

Also, is electrode shape (parallel plates vs. circular coil) critically
important?

Thanks.

Jeff

Prof. Jeffrey P. Wolinski
Department of Physics
Grove City College, Faculty Box 3137
100 Campus Drive
Grove City, PA 16127-2104

Voice: 724-458-2201
Fax: 724-458-2181