You could try a 'Piranha cleaning'. This mixture is know for its voracious
ability to remove organics, so it might help solve your problem. Typically,
mixtures of 98% H2SO4 (sulfuric acid) and 30% H2O2 (hydrogen peroxide) in
volume ratios of 2-4:1 are used at temperatures of 100?C and higher.

Regards,
Jason Viotty
___________________________________________________________
Jason Viotty
Senior Process Engineer
C2V
http://www.c2v.nl



-----Original Message-----
From: [email protected] [mailto:[email protected]]
Sent: Thursday, April 03, 2003 8:14 PM
To: [email protected]
Subject: [mems-talk] C4F8 etchant


Hi MEMS Community,

I would like to know if anyone knows of a chemical that
would etch C4F8 (octofluorocyclobutane)

During the DRIE process, C4F8 is deposited for sidewall
passivation and mask protection in the alternate deposit and
etch cycles. After the DRIE I remove the photoresist AZ4620
by putting the wafers in a Barell Asher with O2 plasma
(40mTorr, 300 Watts for 10mins) and subsequent treatment
with resist strips EKC for 10 mins at 60C and AZ300T for 10
mins at 75C.
This I believe should remove the C4F8 deposits as well.

However from our SEM pictures we find that, possibly the
unremoved C4F8 acts as a mask for further Silicon etching
(in RIE)and this mask is undercut resulting in the loss of
our structures.

I would appreciate very much if someone on the list could
get back to be with an idea of how to strip the C4F8.

Sincerely
Anupama

Anupama V. Govindarajan
Graduate Student - EE MEMS laboratory
Department of Electrical Engineering
University of Washington
Campus Box 352500, Seattle WA 98195
Phone: (206)-221-5340
email: [email protected]

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