Appeal No. 1999-1871 Page 4
Application No. 08/688,337
As claim 1 is the only independent claim within the group containing claims 1 and 5-7,
we select claim 1 to decide the issues on appeal with respect to this group. In general terms,
claim 1 is directed to a method including steps of generating a sacrificial layer with certain
bonding properties, depositing a membrane layer, opening a via in the membrane layer, removing
the sacrificial layer with a first etchant, and etching the substrate with a second etchant.
Higashi describes a process including the steps of claim 1 with the exception that Higashi
does not specifically identify a sacrificial layer material that will remain bonded to the substrate
at a temperature greater than 450BC as required by claim 1. Rather, Higashi teaches an
“aluminum or other selectively etchable layer” for use as the sacrificial layer (Higashi at col. 1, ll.
12-17). Appellant argues that the bonding limitation of claim 1 excludes aluminum and this is
not disputed by the Examiner. Instead, the Examiner finds that, as evidenced by the specification
at page 1, silicon dioxide was known in the prior art as a selectively etchable sacrificial layer
(specification at 1, ll. 18-23). We agree with the Examiner’s conclusion that it would have been
obvious to one of ordinary skill in the art at the time of invention to use a sacrificial layer of
silicon dioxide in the process of Higashi (Answer at 3). Higashi contains a suggestion to use
“other . . . selectively etchable layer[s],” silicon dioxide was a known “other” selectively etchable
layer and thus the substitution would have been obvious to accomplish the same end result.
Appellant does not dispute that the silicon dioxide of the prior art has the bonding property
required by claim 1.
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