Appeal 2007-2490
Application 09/846,255
Independent Claim 1
Regarding independent claim 1, the Examiner's rejection essentially
finds that Mehta teaches a substrate surface cleaning method that brings a
mixed gas of anhydrous hydrogen fluoride (HF) and heated inert gas into
contact with the substrate surface to remove a low-density film without
impairing a high-density film, as claimed. According to the Examiner,
Mehta teaches every claimed feature except for continuously exposing the
anhydrous gas with the substrate. The Examiner cites Verhaverbeke as
teaching etching using a “dynamic mode,” a mode that utilizes a continuous
flow of process gases. The Examiner further notes that Verhaverbeke
teaches that either pulsing (static) or continuous (dynamic) modes may be
used to selectively etch silicon oxides (i.e., they are interchangeable). The
Examiner then concludes that it would have been obvious to one of ordinary
skill in the art at the time of the invention to modify Mehta to continuously
flow process gases (Answer 3-4, 7, and 8).
Appellants argue that although Verhaverbeke discusses both static and
dynamic modes in the context of traditional vapor etching techniques,
Verhaverbeke prefers the static mode given the reference’s overall emphasis
on static mode etching (Br. 4-5). In any event, Appellants argue, it is
unclear why the skilled artisan would combine Mehta with Verhaverbeke.
According to Appellants, Verhaverbeke’s preference for the static mode, in
essence, teaches away from the dynamic mode. Appellants further contend
that not only is Verhaverbeke not concerned with selective removal of a
low-density film present with a high-density film, the respective treatment
compositions in Mehta and Verhaverbeke are different. According to
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