Appeal No. 2001-2503
Application No. 09/075,767
6) Claims 43, 44, 46 and 47 under 35 U.S.C. §103 as unpatentable over the combined
teachings of Tsukude, the admitted prior art, Jolly, Yamada and Chew.
OPINION
We have carefully reviewed the claims, specification and prior art, including the
arguments presented by the examiner and appellants in support of their respective positions.
This review has led us to conclude that the examiner has not provided sufficient evidence to
establish a prima facie case of unpatentability. Accordingly, we reverse each of the examiner’s
section 103 rejections.
Appellants contend that the prior art references do not teach or suggest, inter alia, the
claimed etch selectivity ratio of the dielectric material to the anti-reflecting coating of
approximately 1:1 (1.2:1 to 0.8:1) 3. Thus, the dispositive question is whether it would have
been prima facie obvious to employ the claimed etch ratio in the process of Tsukude. On this
record, we answer this question in the negative.
As acknowledged by the examiner, Tsukude and the allegedly admitted prior art do not
describe the employment of the claimed etch ratio in the fabrication of their semiconductor
devices. Although the examiner relies on Jolly to show the claimed etch ratio, it only teaches an
etch ratio of approximately four times greater than that claimed.4 When, as here, the prior art
references would have suggested a range of etch ratios outside the one claimed, the
determination of optimum values thereof would not have led one of ordinary skill in the art to
the claimed subject matter. See In re Sebek, 465 F.2d 904, 907, 175 USPQ 93, 95 (CCPA 1972)
3 The etch rate of dielectric material is within 20% of the etch rate of the anti-reflecting coating.
4 We also note that the Jolly reference teaches a device materially different from those described in Tsukude and the
allegedly admitted prior art.
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