Appeal No. 2003-2130
Application 08/159,461
claim 66: 3
patterning the polysilicon, nitride, and oxide layers to expose portions of the
substrate: and
reoxidizing the exposed substrate and polysilicon layer, forming oxide on exposed
surfaces of the patterned polysilicon layer and the exposed substrate,
wherein the oxide formed on the exposed substrate during reoxidation has a
thickness greater than the patterned oxide layer and includes a portion extending under
oxide formed on a peripheral surface of the patterned polysilicon layer during
reoxidation.
The disclosure of Geipel pertains to these limitations, with respect to which the examiner
contends that this reference shows
forming an oxide layer using thermal growth at a thickness of 150 to 800 angstroms on
a semiconductor substrate for a gate electrode (see col. 4 lines 36-38); depositing
phosphorous doped polysilicon on said gate insulator to a thickness of about 1000 to
5000 angstroms; patterning the oxide and the polysilicon to form a gate electrode and a
gate oxide (see col. 4-lines 42-57); and reoxidizing the exposed substrate and the
polysilicon layer to a thickness of 2500 angstroms, thereby forming oxide on exposed
surfaces of the patterned polysilicon layer and the exposed substrate (see col. 6-lines
22-26), and furthermore note that the oxide formed during the reoxidation step is
thicker than the previously patterned oxide layer, and since the structure of [Geipel]
and the instant application are the same inherently a portion of the oxide formed
during the reoxidation process extends under oxide formed on a peripheral surface of
the patterned polysilicon layer during reoxidation. [Answer, pages 4-5.]
Appellant argues that Geipel and Haddad do not show or suggest the second limitation
quoted above, and that “the reoxidation need NOT necessarily be thicker than the gate oxide”
(brief, page 11). The examiner responds that “the gate electrode oxide has a thickness of from
150 to 800 angstroms and the reoxidation oxide has a thickness of 2500 angstroms, which would
inherently lead to any undercut around an edge of the gate electrode (resulting from patterning)
be filled by the reoxidation oxide” (answer, page 8). In reply, appellant notes col. 6, lines 25-26
of Geipel, and argues that the reference “does not expressly state or depict formation of a
corresponding thickness of oxide either on the gate electrode sidewalls or over regions adjacent
3 We note here that a ground of rejection under § 103(a) based on this same combination of
references was affirmed by a prior panel of this Board in a decision entered February 28, 2001, in
the present application (Paper No. 27) in Appeal No. 1998-1439, which ground of rejection
involved different claims than now before us in the present appeal.
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