Ex Parte Buynoski

Board of Patent Appeals and Interferences

Jun 24, 2003

09252186 (B.P.A.I. Jun. 24, 2003)

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was not written for publication and is not binding precedent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. 22
UNITED STATES PATENT AND TRADEMARK OFFICE
__________
BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
__________
Ex parte MATTHEW S. BUYNOSKI
__________
Appeal No. 2001-1093
Application 09/252,186
__________
ON BRIEF
__________
Before HAIRSTON, RUGGIERO, and DIXON, Administrative Patent
Judges.
HAIRSTON, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal from the final rejection of claims 1
through 10 and 21 through 33. In a first Amendment After Final
(paper number 12), claim 28 was amended, and claims 32 and 33
were canceled. Accordingly, claims 1 through 10 and 21 through
31 remain before us on appeal.
Appeal No. 2001-1093
Application No. 09/252,186
2
The disclosed invention relates to the use of a metal
silicide liner on metal features and vias of a semiconductor
device.
Claim 1 is illustrative of the claimed invention, and it
reads as follows:
1. A semiconductor device comprising:
a substrate having active regions; and
an interconnection system comprising:
a first patterned metal layer, comprising metal
features, over the substrate;
a plurality of patterned metal layers, each patterned
metal layer containing metal features, above the first patterned
metal layer terminating with an uppermost patterned metal layer;
vias electrically connecting metal features of
different patterned metal layers;
contacts electrically connecting active regions to metal
features of the first patterned metal layer;
air gaps between the patterned metal layers, metal features,
and vias; and
a metal silicide liner on the metal features and vias,
wherein the air gaps are substantially continuous throughout the
interconnection system.
Appeal No. 2001-1093
Application No. 09/252,186
1The provisional double patenting rejection of claims 1
through 10 is no longer before us as a result of the submission
of a terminal disclaimer (paper number 20).
3
The references relied on by the examiner are:
Ho (‘841) 4,898,841 Feb. 6, 1990
Ho (‘214) 4,954,214 Sept. 4, 1990
Hause et al. (Hause) 5,953,626 Sept. 14, 1999
(filed June 5, 1996)
Ahn 6,037,248 Mar. 14, 2000
(filed June 13, 1997)
Claims 1 through 101, 21 through 24 and 28 through 31 stand
rejected under 35 U.S.C. § 103(a) as being unpatentable over
Hause in view of Ahn and Ho ‘214.
Claims 25 through 27 stand rejected under 35 U.S.C. § 103(a)
as being unpatentable over Hause in view of Ahn, Ho ‘214 and
Ho ‘841.
Reference is made to the briefs (paper numbers 16 and 19)
and the answer (paper number 18) for the respective positions of
the appellant and the examiner.
OPINION
We have carefully considered the entire record before us,
and we will reverse the obviousness rejections of claims 1
through 10 and 21 through 31.
Appellant and the examiner agree that Hause fails to
Appeal No. 2001-1093
Application No. 09/252,186
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disclose a metal silicide liner on the metal features and the
vias of a semiconductor device (brief, page 8; answer, page 5).
According to the examiner (answer, page 6), “Ahn teaches in
figure 10 a plurality of patterned metal layers comprising
aluminum, copper or an alloy thereof (column 4, line 65)
containing metal features and vias (column 1, lines 23-28), and
air gaps 56, substantially continuous throughout the
interconnection system, between the patterned metal layers, metal
features and vias, and a conductive liner 44, 52 used as an
adhesion promoter layer (column 4, lines 60-62) substantially
enveloping metal features and vias,” and “Ho [’214] teaches in
figure 2e a conductive liner 200, 208 being an adhesion promoter
layer (column 4, lines 27-29) and comprising tungsten silicide
(column 7, line 44) of thickness between 500 to 1000 A, on and
around interconnect structures 210.” Based upon the teachings of
Ahn and Ho, the examiner is of the opinion (answer, pages 5 and
6) that:
It would have been obvious to a person of ordinary
skill in the art at the time the invention was made to
form a metal silicide liner on the metal features and
the vias in Hause et al.’s device in order to enhance
the conductivity of the device, improve the reliability
of the device and to prevent the formation of open
circuits and short circuits during the etching process
of making the device. The combination is motivated by
the teachings of Ahn who points out the advantages of
Appeal No. 2001-1093
Application No. 09/252,186
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using a conductive liner (adhesion promoter layer) to
envelope interconnection system having an air gap
therein. Ahn further teaches an artisan that the
adhesion promoter layer can be formed of metals other
than refractory metals (column 5, lines 64-65). Ho
teaches the advantages of using a metal silicide liner
as an adhesion promoter layer on interconnect
structures (column 4, lines 22-29), wherein an adhesion
promoter metal silicide liner can replace an adhesion
promoter liner comprising aluminum and refractory metal
(column 7, lines 49-54).
The examiner’s contentions to the contrary notwithstanding,
the evidentiary record before us does not support any of the so-
called motivational statements (e.g., enhancing the conductivity
of the device, improving the reliability of the device and
preventing the formation of open circuits and short circuits
during an etching process) for modifying the teachings of Hause
with those of Ahn and Ho. As stated in In re Lee, 277 F.3d 1338,
1343-44, 61 USPQ2d 1430, 1434 (Fed. Cir. 2002) (“The examiner’s
conclusory statements . . . do not adequately address the issue
of motivation to combine. This factual question of motivation is
material to patentability, and could not be resolved on
subjective belief and unknown authority. It is improper, in
determining whether a person of ordinary skill would have been
led to this combination of references, simply to ‘[use] that
which the inventor taught against its teacher.’”). Although Ahn
discloses the use of copper alloys formed from a refractory metal
Appeal No. 2001-1093
Application No. 09/252,186
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(e.g., titanium) in adhesion promoter layers 44 and 52
(Figure 10; column 4, line 53 through column 5, line 24), and Ho
uses a refractory metal (e.g., tungsten) in a metal silicide seed
layer 200 and 208 for a subsequent deposit of tungsten in an
opening 204 of a semiconductor device (Figure 2e; column 4,
lines 2 through 30 and column 7, lines 3 through 54), the
examiner has not successfully demonstrated via substantial
evidence in the record how and why the skilled artisan would have
found it obvious to rely on the disparate copper alloy teachings
of Ahn and the metal silicide teachings of Ho to provide the
“metal features and vias” in Hause with a metal silicide liner.
Thus, the obviousness rejection of claims 1 through 10, 21
through 24 and 28 through 31 is reversed because we agree with
the appellant’s argument (reply brief, page 5) that “[t]he
Examiner’s interpretation of the seedlayer of Ho ‘214 and
photoresist adhesion promoter of Ahn as a conductivity enhancing
feature for the system of Hause et al., when viewed in light of
Appellant’s disclosure, is clearly an improper retrospective
assessment of the applied prior art in light of Appellant’s
disclosure.”
The obviousness rejection of claims 25 through 27 is
reversed because the metal silicide teachings of Ho ‘841 fail to
Appeal No. 2001-1093
Application No. 09/252,186
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cure the noted shortcoming in the teachings of Hause, Ahn and Ho
‘214.
DECISION
The decision of the examiner rejecting claims 1 through 10
and 21 through 31 under 35 U.S.C. § 103(a) is reversed.
REVERSED

KENNETH W. HAIRSTON )
Administrative Patent Judge )
)
)
) BOARD OF PATENT
JOSEPH F. RUGGIERO ) APPEALS AND
Administrative Patent Judge ) INTERFERENCES
)
)
)
JOSEPH L. DIXON )
Administrative Patent Judge )
KWH:svt
Appeal No. 2001-1093
Application No. 09/252,186
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