I have read 2 papers on a similar problem, maybe thise will help a bit...
They use a so-called Post Dry Etch Cleaning for removal of umwanted
Fluor-based plasma etch damage.

[1]: Characterization of the post dry-etch cleaning of silicon for
Ti-self-aligned silicide technology, Kim e.a., Journal of Electr. Soc. Vol
146, Issue 4 1999 pag. 1549-1556
[2]: limitations of Hf-based chemistry for deep-suibmicron contact hole
cleaning on silicides, Baklonov e.a., Journal of Electr. Soc. Vol 145, Issue
9 1998 pag. 3240-3246

Hope it will help you on your way.

Regards,
Marc
------
Ing. Marc van den Boogaart
PhD-Student
Laboratoire des Microsystemes
EPFL - STI - IMM - LMIS1;   BM 3.217
1015 Lausanne
Switzerland
Tel.:   +41 (0)21 693 6742
Fax.:  +41 (0)21 693 6670
http://lmis1.epfl.ch

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Message: 3
From: "Ken Kwon" 
To: [email protected]
Date: Tue, 25 Jun 2002 18:57:36 -0700
Subject: [mems-talk] fluorocarbon residue removal in silicon DRIE
Reply-To: [email protected]

Hi,  I have a problem with removing fluorocarbon reside off a deep silicon
trench sidewall after a DRIE process (SF6, C4F8 gases used).  Lot of papers
suggest that the polymer can be removed by O2 plasma, but it seems like the
polymer on my wafer get hardened by oxygen plasma.

If you know why sidewall polymer can harden(?) or know how to remove a such
tough polymer, please email to me at [email protected]

Thank you

Ken