Appeal No. 95-3557
Application No. 07/833,417
As noted by the examiner, Wise fails to disclose or suggest forming polysilicon layer 34 by
epitaxial growth (answer, page 3). However, since Huster discloses growing an epitaxial layer of n-
type silicon on a p-type wafer (silicon substrate) to fabricate diaphragms of identical and controllable
thickness (page 899, col. 2, first full paragraph) and Mauger describes forming a silicon diaphragm by
etching away a p-type silicon substrate beneath an n-type doped layer of desired thickness formed by
epitaxy (col. 3, lines 42-60; col. 4, lines 12-20; and col. 5, lines 15-25), the examiner concludes
[i]t would have been obvious to one of ordinary skill in the art to modify Wise et al.
process with an epitaxial layer on a silicon substrate as taught by Huster et al. or
Mauger because a diaphragm (flexure) with rim (boss) of desired thickness on the
silicon substrate can be obtained. [Answer, page 4, last full para.]
To establish a prima facie case of obviousness, there must be both some suggestion or
motivation to modify the reference or combine reference teachings and a reasonable expectation of
success. The prior art must teach or suggest all the claim limitations. In re Vaeck, 947 F.2d 488, 493,
20 USPQ2d 1438, 1442 (Fed. Cir. 1991).
Here, there is no dispute that the individual steps of diffusion, ion implantation and epitaxy are
well known, art recognized techniques for providing a doped silicon layer (see e.g., Mauger, col. 4,
lines 17-20) or that Huster discloses using two diffusion steps to make thick (i.e., boss) and thin (i.e.,
flexure) portions of vertically structured silicon diaphragm by electrochemical etching (brief, pages 5-6).
Appellants argue neither Wise, Huster and/or Mauger discloses or suggests using a first diffusion step
followed by a second epitaxial growth step to
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