Appeal No. 1998-0129 Page 7
Application No. 08/438,062
over PZT because BST has stable electrical characteristics and
has no fatigue problems.
Appellants note (brief, page 6) that the ferroelectric
layer 30 of Miller is made of PZT or PLZT, and that Miller is
silent as to any express or implied problems with respect to
PZT ferroelectrics. Appellants assert that Miller does not
teach the use of a BST dielectric, and that (brief, page 7)
the references relied upon by the examiner are completely
devoid of any reference to gallium arsenide substrates.
From our review of the references, we find that Miller
teaches (col. 3, lines 25-38) a ferroelectric capacitor
designed for fabrication into MOS structure on a semiconductor
substrate. Specifically, Miller teaches (col. 3, lines 37-39)
that the capacitor is fabricated on a “semiconductor substrate
12, which is typically silicon or gallium arsenide.” From
these teachings of Miller, we are not in agreement with
appellants’ statement (brief, page 13) that Miller mentions
the use of gallium arsenide as a substrate “only as an
afterthought.” We consider the statement in Miller (col. 3,
lines 37-39) that the semiconductor layer is “typically”
silicon or gallium arsenide to clearly teach the use of a
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