Ex Parte Xing et al

Board of Patent Appeals and Interferences

Mar 25, 2005

09901416 (B.P.A.I. Mar. 25, 2005)

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The opinion in support of the decision being entered
today was not written for publication in a law journal
and is not binding precedent of the Board.
UNITED STATES PATENT AND TRADEMARK OFFICE

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES

Ex parte GUOQIANG XING,
KENNETH D. BRENNAN and PING JIANG

Appeal No. 2005-0811
Application No. 09/901,416

ON BRIEF

Before KIMLIN, GARRIS and JEFFREY T. SMITH, Administrative Patent
Judges.
KIMLIN, Administrative Patent Judge.
DECISION ON APPEAL
This is an appeal from the final rejection of claims 1-13.
Claim 1 is illustrative:
1. A method for forming interconnects, comprising:
providing a silicon substrate containing one or more
electronic devices;
forming a first dielectric layer over said silicon
substrate;
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Application No. 09/901,416
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forming a second dielectric layer over said first dielectric
layer wherein the dielectric constant of the second dielectric
layer is less than 3.0;
forming a first hardmask layer over said second dielectric
layer;
forming a second hardmask layer on said first hardmask layer
wherein said second hardmask layer comprises a material selected
from the group consisting of titanium aluminide (TiAl), titanium
aluminum nitride (TiAlN), titanium nitride (TiN), aluminum
nitride (AlN), tantalum aluminide (TaAl), and tantalum aluminum
nitride (TaAlN);
forming a trench in said second dielectric; and
filling said trench with a conducting material.
The examiner relies upon the following references as
evidence of obviousness:
Blosse et al. (Blosse) 6,399,512 B1 June 4, 2002
(filed June 15, 2000)
Flanner et al. (Flanner) 6,410,437 B1 June 25, 2002
(filed June 30, 2000)
Appellants' claimed invention is directed to a method for
forming interconnects comprising first and second dielectric
layers and first and second hardmask layers on a silicon
substrate. The first hardmask layer may be SiN and the second
hardmask layer may be TiN.
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Application No. 09/901,416
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Appealed claims 1-13 stand rejected under 35 U.S.C. § 103(a)
as being unpatentable over Flanner in view of Blosse.
Appellants submit at page 3 of the principal brief that
"[c]laims 1-13 stand or fall together." Accordingly, all the
appealed claims stand or fall together with claim 1.
We have thoroughly reviewed each of appellants' arguments
for patentability. However, we are in complete agreement with
the examiner that the claimed subject matter would have been
obvious to one of ordinary skill in the art within the meaning of
§ 103 in view of the applied prior art. Accordingly, we will
sustain the examiner's rejection for essentially those reasons
expressed in the Answer.
Appellants do not dispute the examiner's factual
determination that Flanner, like appellants, discloses a method
of forming interconnects on a silicon substrate by forming the
presently claimed first and second dielectric layers, as well as
cap and antireflective layers. Appellants also do not contest
the examiner's legal conclusion that it would have been obvious
for one of ordinary skill in the art to substitute the hard
inorganic layer of Blosse for the organic antireflective layer of
Flanner. Indeed, Blosse teaches the equivalency of organic
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Application No. 09/901,416
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antireflective layers and an inorganic dielectric layer of TiN
(column 5, lines 50 et seq.).
It is appellants' principal contention that Flanner uses
photoresist layer 2 as the mask, and not the cap and
antireflection layers, 6 and 4, respectively. Appellants
maintain that layers 4 and 6 of Flanner are not hardmask layers
and that "[t]hey serve no masking function as that term is used
in the instant invention" (page 4 of principal brief, penultimate
sentence). Also, although appellants submit that a photoresist
layer is not present during the etch process, they do agree with
the examiner that the "comprising" language of claim 1 does not
preclude the presence of a photoresist masking layer over the
first and second hardmask layers.
Since cap layer 6 of Flanner may comprise SiN (column 4,
line 65), and appellants do not contest the examiner's conclusion
that antireflective layer 4 of Flanner may be TiN, the argued
difference between the claimed method and the modified method of
Flanner is one that is more semantical than substantive. While
Flanner does not refer to layers 4 and 6 as mask layers, it is
clear from Flanner's Figure 5 that layers 4 and 6, in addition to
layer 2, function as a mask layer during the etching of layers 8
and 12. Inasmuch as appellants do not take issue with the
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examiner's finding that layers 4 and 6 of Flanner may comprise
the same material as appellants' first and second hardmasks, we
perceive no meaningful distinction between methods encompassed by
claim 1 on appeal and methods fairly taught by Flanner,
particularly when one of the methods embraced by claim 1 includes
a photoresist mask over the first and second hardmask layers.
Although we agree with appellants' analysis of the
examiner's citation of Figures 20 and 21 of Flanner, we concur
with the examiner that methods within the scope of claim 1 on
appeal would have been obvious to one of ordinary skill in the
art in view of the collective teachings of Flanner and Blosse.
As a final point, we note that appellants base no argument
upon objective evidence of nonobviousness, such as unexpected
results.
In conclusion, based on the foregoing, the examiner's
decision rejecting the appealed claims is affirmed.
Appeal No. 2005-0811
Application No. 09/901,416
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No time period for taking any subsequent action in
connection with this appeal may be extended under 37 CFR
§ 1.136(a)(1)(iv) (effective Sep. 13, 2004; 69 Fed. Reg. 49960
(Aug. 12, 2004); 1286 Off. Gaz. Pat. Office 21 (Sep. 7, 2004)).
AFFIRMED
EDWARD C. KIMLIN )
Administrative Patent Judge )
)
)
)
)
BRADLEY R. GARRIS ) BOARD OF PATENT
Administrative Patent Judge ) APPEALS AND
) INTERFERENCES
)
)
)
JEFFREY T. SMITH )
Administrative Patent Judge )
ECK:clm
Appeal No. 2005-0811
Application No. 09/901,416
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Texas Instruments Inc.
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