Hi Anupama,
Is your DRIE process for deep silicon trench structure? If yes,
what is the aspect ratio of the trench? Your O2 ashing process should be
able to remove the polymer deposit but it is aspect ratio dependent if the
ratio is high. Same for solvent stripper, if your opening size very small,
the surface tension of the solution may not allow it to reach the whole
trench. But if you are not doing this work, then something else like other
people suggested may be needed. Hope this helps.
Isaac Chan
On Thu, 3 Apr 2003 anupama@ee.washington.edu wrote:
> 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: anupama@ee.washington.edu
>
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Yours sincerely,
Isaac Chan
Ph.D. Candidate
Dept. Electrical & Computer Engineering
University of Waterloo
200 University Ave. W
Waterloo, Ontario, Canada
N2L 3V1
Tel: (519) 729-6409, ext. 6014
Fax: (519) 746-6321
iwchan@venus.uwaterloo.ca
http://www.ece.uwaterloo.ca/~a-sidic