Ex Parte Gambino et al

Patent Trial and Appeal Board

Dec 19, 2013

12142094 (P.T.A.B. Dec. 19, 2013)

UNITED STATES PATENT AND TRADEMARK OFFICE
________________

BEFORE
THE PATENT TRIAL AND APPEAL BOARD
________________

Ex parte JEFFREY P. GAMBINO1
and Anthony K. Stamper
________________

Appeal 2011-003470
Application 12/142,094
Technology Center 2800
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Before CHUNG K. PAK, CHARLES F. WARREN, and
MARK NAGUMO, Administrative Patent Judges.

NAGUMO, Administrative Patent Judge.

DECISION ON APPEAL
Jeffrey P. Gambino and Anthony K. Stamper (“Gambino”) timely
appeal under 35 U.S.C. § 134(a) from the final rejection2 of claims 1, 2,
5-11, 13, 15, 18, 20, 22, 24, 26, 27, and 29-31, which are all of the pending

1 The real party in interest is listed as International Business Machines
Corporation. (Appeal Brief, filed 19 July 2010 (“Br.”), 2.)
2 Office action mailed 15 March 2010 (“Final Rejection”; cited as “FR”).
Appeal 2011-003470
Application 12/142,094

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claims. We have jurisdiction. 35 U.S.C. § 6. We reverse substantially for
reasons given by Gambino.
OPINION
A. Introduction3
The subject matter on appeal relates to an improved method of
damascene processing in which, for example, bulk conductive material
forming a conductive “wire” (i.e., a conductive path in an integrated circuit)
and a barrier layer that lines the trench in the dielectric material in which the
wire is formed and that covers the surface of the dielectric surrounding the
trench, are removed to a coplanar level by exposure to a Gas Cluster Ion
Beam (“GCIB”). In certain embodiments, the GCIB is modified to be
selective for the bulk metal or for the barrier layer material, depending
which layer is exposed to the beam. The selectivity, compared to standard
chemical-mechanical polishing (“CMP”) planarizing techniques, is said to
permit the formation of lower aspect trenches, which in turn reduces the
number of defect voids in the wires. (Spec. 2 [0007] - 4 [0016].)
The 094 Specification teaches that Gas Cluster Ion Beams are charged
clusters of atoms or molecules (collectively “atoms”) that may include up to
about 5000 atoms per cluster and provide an average flux equivalent
to 7 mA/cm2. The atoms in the cluster may be selected so they interact

3 Application 12/142,094, Reducing wire erosion during damascene
processing, filed 19 June 2008, as a continuation of 10/906,013,
filed 31 January 2005, now U.S. Patent 7,405,152. The specification is cited
as “Spec.”
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selectively with material to be removed from a substrate. The kinetic energy
of the cluster is shared among the loosely bound atoms of the cluster, and the
resulting etching is said to be distinct from other types of etching processes.
(Spec. 7 [0030] - 8 [0032].)
Claim 1 is representative and reads:
A method of reducing erosion in a damascene process,
comprising the steps of:
arranging a first layer [254] in a trench [20] in a
dielectric [15] formed on a substrate [10] and directly on a
surface of the dielectric [40] adjacent to the trench;
depositing a bulk conductor [30] on the first layer in the
trench and adjacent to the trench; and
selectively removing an upper portion [35] of the bulk
conductor with a gas cluster ion beam (GCIB) process that
is selective to the bulk conductor by impacting large
clusters of preselected types of atoms on the upper portion
of the bulk conductor to be removed,
wherein the GCIB process exposes a surface
portion [40] of the first layer that is arranged directly on
the surface of the dielectric adjacent to the trench such
that an upper surface of the surface portion is coplanar
with an upper surface of the bulk conductor in the
trench.
(Claims App., Br. 22; some indentation, paragraphing, square bracketed
labels to elements illustrated in Fig. 3 (infra at 5), and all emphasis added.)

4 Throughout this Opinion, for clarity, labels to elements in figures are
presented in bold font, regardless of their presentation in the original
document.
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The Examiner maintains the following grounds of rejection:5
A. Claims 1, 2, 5-7, 8-11, 13, 15, 18, 20, 22, 24, and 26-28 stand
rejected under 35 U.S.C. § 103(a) in view of the teachings of
Chooi6 or Tsai,7 combined with Hautala,8 Ghandhi,9 or
Wolf.10
A1. Claims 29-31 stand rejected under 35 U.S.C. § 103(a) in view
of the teachings of Chooi or Tsai, combined with Hautala,
Ghandhi, or Wolf, and with Hautala 511,11 and Gates.12

5 Examiner’s Answer mailed 7 October 2010 (“Ans.”).
6 Simon Chooi et al., Deposition of barrier metal in damascene
interconnects using metal carbonyl, U.S. Patent Application
Publication 2004/0082169 Al (29 April 2004), based on an application
filed 29 October 2002.
7 Teng-Chun Tsai et al., U.S. Patent Application Publication
2002/0068435 Al (2002).
8 John J. Hautala et al., Copper interconnect wiring and method of forming
thereof, U.S. Patent Application Publication 2006/0105570 Al (18 May
2006), based on an application filed 8 November 2004.
9 Sorab K. Ghandhi, VLSI Fabrication Principles, Silicon and Gallium
Arsenide, pp. 477 and 517-520 Wiley-Interscience, New York (1983).
10 Stanley Wolf and Richard N. Tauber, Silicon processing for the VLSI era,
Vol. 1: Process Technology, p. 519, and Vol. 2: Process Integration, p. 6,
Lattice Press, CA (1990).
11 John J. Hautala, U.S. Patent 7,115,511 B2 (3 October 2006), based on an
application filed 8 November 2002.
12 Stephen McConnell Gates and Roy Edwin Scheuerlein, U.S.
Patent 6,351,023 Bl (2002).
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B. Discussion
Findings of fact throughout this Opinion are supported by a
preponderance of the evidence of record.
The critical steps of the process covered by claim 1 are illustrated in
Figures 3 and 4 of the 094 Specification, which are reproduced below:

{Fig. 3 shows a trench 20 in dielectric 15, which is covered by liner 25 and
surface covering 40, and then by bulk conductor 30. Fig. 4 shows removal
by GCIB of “upper” bulk conductor 35, leaving covering material 40
coplanar with remaining conductor 30 in trench 20.}
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The Examiner finds that both Chooi and Tsai disclose conventional
damascene processes for forming wires in trenches with CMP planarization
to remove the barrier layer and the upper portions of the bulk conductor.
The Examiner finds that Hautala discloses, particularly in paragraph [0032]
and Figures 4B and 4C, removal of element 502, the copper conductor, by
etching. (Ans. 5-6, and 8, 1st para.) As further support of this notion, the
Examiner cites the disclosure by Hautala of the “use of GCIBs for corrective
etching of an initially non-uniform thin film to improve its spatial
uniformity.” (Ans. 8, ll. 5-6, quoting Hautala [0008], penultimate sentence;
emphasis omitted.) The Examiner concludes that it would have been
obvious to substitute the GCIB processes described by Hautala for the CMP
planarizing processes described by Chooi or Tsai.
The difficulty with this reasoning is that the GCIB process described
by Hautala 570 in Figures 4B-4C involves the removal of contaminants 503
on the surface of conductor 502 and dielectric 508. Consistently, Hautala
discloses that
The gas-clusters disintegrate on impact, with each individual
molecule carrying only a small fraction of the total gas-
cluster ion energy. Consequently, the impact effects of large
gas-cluster ions are substantial, but are limited to a very
shallow surface region. This makes gas-cluster ions
effective for a variety of surface modification processes,
without the tendency to produce deeper subsurface damage
characteristic of conventional monomer ion beam processing.
(Hautala [0008]; emphasis added; quoted by Gambino at Br. 8.) As
Gambino argues, this passage indicates that Hautala discloses GCIB to be
useful for “small-scale operations that take place on or at a surface of a
semiconductor structure. This passage does not teach that GCIB can be used
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for large scale, bulk material removal, such as removing an upper portion of
a bulk conductor as recited in the claimed invention.” (Br. 8, ll. 21-25.)
Indeed, as Gambino argues (Br. 7-8), the Examiner has not directed our
attention to any disclosure in Hautala that GCIB was recognized as being
useful for selective removal of bulk conductors.
The Examiner argues that the passage quoted from Hautala [0008] in
the final rejection is supported by Allen13 et al., the entire content of which is
incorporated by reference into Hautala. (FR 13.) Although Allen is not
listed on the Notices of References cited (PTO-892) or Information
Disclosure Statements by Applicant (PTO-1449), the Examiner cites a
passage at column 14 as support for the argument that Hautala teaches
selective etching, including removing bulk conductor. (Ans. 17, 2d full
para.) This passage, however, refers to the use of GCIB to “continuously
and simultaneously react with surface contaminants and etch them away.”
(Allen, col. 14, ll. 33-34.) It does not mention removal of bulk conductors.
Moreover, Allen is directed to “the surface quality of the top, ultra-thin
silicon layer on SOI substrates.” (Id. at col. 2, ll. 8-9.) Thus, Allen supports
the arguments of Gambino, not those of the Examiner.
The Examiner has not directed our attention to credible evidence that
indicates that GCIB would have been regarded as useful for the larger scale
removal required by the claimed invention. At best, the Examiner has
indicated passages in Hautala that are not inconsistent with the possibility
that GCIB might be adapted for the selective removal of bulk conductors as

13 Lisa P. Allen and David B. Fenner, System and method for improving thin
films by gas cluster ion beam processing, U.S. Patent 6,537,606 B2 (2003).
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required by the appealed claims. But the possibility of enablement of a
claimed process is not the same as the suggestion that such a process be
done.
Similar limitations are required by independent claims 8 and 15. The
Examiner’s findings regarding the remaining references do not cure the
inadequacy of Hautala.
Accordingly, we reverse the rejections of record.
C. Order
We reverse the rejection of claims 1, 2, 5-11, 13, 15, 18, 20, 22, 24,
26, 27, and 29-31.
REVERSED

cdc

Notice of References Cited

Application/Control No.

12/142,094
Applicant(s)/Patent Under
Reexamination
Jeffrey P. Gambino et al.
Examiner

Thanh Pham
Art Unit

2800

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*A copy of this reference is not being furnished with this Office action. (See Manual of Patent Examining Procedure, Section 707.05(a).)
**APS encompasses any electronic search i.e. text, image, and Commercial Databases.
U.S. Patent and Trademark Office
PTO-892 (Rev. 03-98Notice of References Cited Part of Paper No. 16
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