Ex parte Tseng

Board of Patent Appeals and Interferences

Sep 14, 2000

08720645 (B.P.A.I. Sep. 14, 2000)

1
The opinion in support of the decision being entered today was not written for
publication and is not binding precedent of the Board.
Paper No. 13
UNITED STATES PATENT AND TRADEMARK OFFICE
_____________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
_____________
Ex parte HORNG-HUEI TSENG
_____________
Appeal No. 1998-1100
Application No. 08/720,645
______________
ON BRIEF
_______________
Before HAIRSTON, FLEMING, and LEVY, Administrative Patent
Judges.
HAIRSTON, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal from the final rejection of claims
20 through 25.
The disclosed invention relates to a storage electrode of
a capacitor for a DRAM cell on a semiconductor substrate. The
storage electrode has an upright lower cylindrical portion,
and a solid hemispherically-shaped upper portion that is
Appeal No. 1998-1100
Application No. 08/720,645
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centered over the cylindrical lower portion.
Appeal No. 1998-1100
Application No. 08/720,645
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Claim 20 is illustrative of the claimed invention, and it
reads as follows:
20. A capacitor for a DRAM cell on a semiconductor
substrate; said semiconductor substrate having a MOS
transistor with a source region and a drain region;
comprising:
a storage electrode having an upright lower
cylindrical portion and a hemispherical shaped upper
portion; said hemispherical shaped upper portion
having
a hemispherical cross-sectional shape and a solid inside;
said upright lower cylindrical portion in electrical
contact with said source region in said substrate; said
hemispherical shaped upper portion centered over said
cylindrical lower portion; a capacitor dielectric
layer
and a top electrode covering said storage electrode.
The references relied on by the examiner are:
Ahn 5,386,382 Jan. 31, 1995
Suganaga et al. (Suganaga) 5,539,231 Jul. 23, 1996
(filed Mar. 2,
1995)
Claims 20 through 25 stand rejected under 35 U.S.C. § 103
as being unpatentable over Ahn in view of Suganaga.
Reference is made to the brief and the answer for the
respective positions of the appellant and the examiner.
Appeal No. 1998-1100
Application No. 08/720,645
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OPINION
The obviousness rejection of claims 20 through 25 is
reversed.
All of the claims on appeal are directed to a capacitor
for a DRAM cell that has a storage electrode with a solid
hemispherically-shaped upper portion.
Ahn discloses a capacitor for a DRAM cell (Figures 1, 3B,
4C and 4D) that has a storage electrode with a square-shaped
upper portion 100. A cavity is formed in the upper portion
100.
According to the examiner (Answer, pages 4 and 5),
Suganaga discloses a hemispherically-shaped electrode. In
view of the lack of any specifics, we assume the examiner is
referring to the hemispherically-shaped portion 4 (Figures 1
and 10 through 13). In view of these teachings, the examiner
concludes (Answer, pages 4 and 5) that it would have been
obvious to one of ordinary skill in the art to substitute
Suganaga’s hemispherically-shaped electrode for the square-
shaped upper portion 100 in Ahn because they are both
functionally equivalent electrode shapes.
Appeal No. 1998-1100
Application No. 08/720,645
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Appellant argues (Brief, page 9) that “Suganaga happens
to show a long bitline interconnect 4 with rounded sidewalls -
not hemispherical - in a contact area 10.” Appellant also
argues (Brief, page 10) that:
Even if combined, the references do
not suggest applicant’s hemispherical shaped
capacitor. It is not obvious to extrapolate
the combination of Ahn’s square capacitor 100
and Suganaga’s linear bit-lines 4 with rounded
sidewalls to form applicant’s hemispherical
capacitors 50. It is not clear what the
combination of the Ahn’s square capacitor
and Suganaga[’s] long interconnect line with
rounded corners would yield since neither patent
shows a hemispherical shape.
We agree with appellant’s arguments. The above-noted
figures in Suganaga appear to show a hemispherically-shaped
electrode 4, but the plan view of Figure 15 reveals that the
so-called hemispherically-shaped portion 4 is, as argued by
appellant, a long interconnect line with rounded edges. In
summary, we agree with appellant’s argument (Brief, pages 10
and 11) that the examiner has used hindsight to make a
“strained interpretation of the combination of Ahn and
Suganaga,” and that the examiner “has not presented a
convincing line of reasoning as to why the claimed subject
matter as a whole . . . would have been obvious.”
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Application No. 08/720,645
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Appeal No. 1998-1100
Application No. 08/720,645
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DECISION
The decision of the examiner rejecting claims 20 through
25 under 35 U.S.C. § 103 is reversed.
REVERSED
)
KENNETH W. HAIRSTON )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
MICHAEL R. FLEMING )
Administrative Patent Judge ) APPEALS AND
)
) INTERFERENCES
)
STUART S. LEVY )
Administrative Patent Judge )
KWH:hh
Appeal No. 1998-1100
Application No. 08/720,645
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