Appeal No. 2002-0102
Application No. 09/298,879
2. Claims 6, 7, 10 and 15 stand rejected under 35 U.S.C.
§ 103 as unpatentable over El-Diwany in view of Lin and Sun and
further in view of Pong.
We reverse.
Background
The invention relates to a method of simultaneously forming
both a high voltage and a low voltage transistor in the
manufacture of an integrated circuit. Claims 1, 10 and 18. The
method involves a two-step wet oxidation using H2, O2 and N2 in
specified ratios. Id. The claims require that the second gate
oxide layer underlies the first gate oxide layer. Id. According
to appellants,
[t]he significance of forming the second gate oxide
under the first gate oxide is that the substrate in
this area is not damaged by the process of removing the
first gate oxide and then regrowing a second gate
oxide. The substrate is protected by the first gate
oxide, thus maintaining high quality.
Appeal brief, Paper No. 10, received April 23, 2001, page 8.
Discussion
The initial burden of presenting a prima facie case of
obviousness rest on the examiner. In re Oetiker, 977 F.2d 1443,
1445, 24 USPQ2d 1443, 1444 (Fed. Cir. 1992). Where an
obviousness determination is based on a combination of prior art
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