Appeal No. 1999-2347
Application 08/892,560
discussion of sputtering of the metallization interconnect, which
is not persuasive. The Examiner, likewise, did not appreciate
the prevention of the sputtering teaching of Erie. Although we
believe the reason Barber and Kim use etch stop layers is also to
prevent sputtering of the underlying conductors, whether the
conductors are made of metal or polysilicon, it is not necessary
to rely on such a finding.
We conclude that it would have been obvious to modify Barber
in view of Erie and Kim to arrive at the subject matter of
claim 21. Appellants do not address why it would have been
unobvious to use metal interconnections in Barber in view of the
metal interconnections taught in Erie and Kim as stated by the
Examiner. Instead, Appellants rely on the argument that none of
Barber, Erie, or Kim teaches metal sputtering. We have shown
Appellants' argument to be in error because overcoming the
problem of metal sputtering is taught by Erie. It was well known
in the semiconductor art to use metal interconnections, as
evidenced by Erie and Kim. The fact that Barber, Erie, and Kim
all teach an electrically conductive interconnect layer covered
by an etch stop layer covered by a dielectric layer, where a via
is created by etching the dielectric layer down to the etch stop
layer and then etching the etch stop layer down to the conductive
layer would have suggested (i.e., provided motivation for) the
substitution of materials for the various layers. Moreover, Kim
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