Appeal 2007-0488
Application 10/071,809
25, and 27, the only claims pending in this application, under 35 U.S.C.
§ 112, first paragraph (Supplemental Examiner’s Answer dated May 24,
2006, p. 2). Appellant has submitted a Reply Brief dated July 24, 2006, in
response to the Examiner’s rejection, requesting the “appeal be maintained”
(Reply Br. cover letter). Accordingly, this is a decision on this appeal
(Appeal No. 2007-0488). We have jurisdiction pursuant to 35 U.S.C. § 134.
According to Appellant, the invention is directed to a method of
etching a metal silicide layer while fabricating an integrated circuit using a
chlorine/oxygen gas environment at a pressure of about 2 to 40 mili-Torr
and an oxygen concentration of greater than or equal to 25% by volume to
selectively etch the metal silicide over polysilicon at a ratio of at least 30:1
(prior Decision, pp. 1-2; Reply Br. 1). Independent claim 1 is illustrative of
the invention and is reproduced below:
1. A method comprising, etching a metal silicide layer during
fabrication of an integrated circuit in a Cl2/O2 environment having an O2
concentration of greater than or equal to 25% by volume,
wherein the Cl2/O2, environment is provided at a pressure of
approximately 2-40 mili-Torr, and wherein the etching is a metal silicide
etch that is selective to poly-silicon with a ratio of etch rates of at least 30.
The Examiner has relied upon the following reference as evidence to
support the rejection:
Nojiri , “High rate and highly selective anisotropic etching for WSix/poly-Si
using electron cyclotron resonance plasma,” 14 J. Vac. Sci. Technol., B,
1791-95 (May/June 1996).
2
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