Appeal No. 95-3557
Application No. 07/833,417
make relatively thick boss and relatively thin flexure sections of a structured silicon diaphragm by
chemical etching in the manner claimed, wherein the desired thickness of the boss is x, the desired
thickness of the flexure is y, the first diffusion depth is x-y and the epitaxial growth depth is y (brief,
pages 8-9). According to the examiner, x in Wise is equal to rim 20 (x-y) plus polycrystalline silicon
layer 34 (y) (answer, page 8) and the issue is whether it would have been obvious to provide
polycrystalline silicon layer 34 of Wise as an epitaxial growth layer so as to provide a relatively thin
flexure section (answer, page 4).
However, the examiner has failed to establish on this record why a self-supporting thermopile
comprised of a plurality of thermocouples would have reasonably disclosed or suggested a structured
silicon diaphragm, i.e., why one of ordinary skill in the art would have reasonably expected Wise’s
electrically conductive polycrystalline silicon layer 34 to form a flexure section given (a) that layer 34,
along with metal layer 36, etc. forms a thermocouple and (b) that omission of the only positively recited
diaphragm structure in Wise, i.e., dielectric diaphragm 40, requires polycrystalline silicon layer 34 to
support the device after etching (col. 6, lines 60-65). The examiner has also failed to explain why the
skilled artisan would have selected the same dopant to dope both polycrystalline silicon layer 34 and
rim area 20. Rather, the only place we find a suggestion to machine silicon to form a boss diaphragm
structure having relatively thick boss sections and relatively thin flexure sections by (1) providing a
substrate of a first type doped silicon, (2) deeply diffusing a second type dopant only into selected areas
on a surface of the first type doped silicon where the boss sections are to be formed and only to a
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