Ex Parte Avanzino

Board of Patent Appeals and Interferences

Sep 29, 2008

10726992 (B.P.A.I. Sep. 29, 2008)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte STEVEN C. AVANZINO
____________

Appeal 2008-3570
Application 10/726,992
Technology Center 1700
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Decided: September 29, 2008
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Before EDWARD C. KIMLIN, THOMAS A. WALTZ, and
KAREN M. HASTINGS, Administrative Patent Judges.

WALTZ, Administrative Patent Judge.

DECISION ON APPEAL
Appellant seeks review under 35 U.S.C. § 134 from the Examiner’s
rejections of pending claims 1-20 in the final Office Action, dated June 5,
2006. This Board has jurisdiction under 35 U.S.C. § 6(b). For the reasons
given below, the rejections of the Examiner are REVERSED.
Appeal 2008-3570
Application 10/726,992

The present application is directed to a method of etching a copper
material, comprising steps of contacting the material with a first and a
second solution. Claim 1 is illustrative and reproduced below.
1. A method of etching a copper containing
material, comprising:
contacting the copper containing material
comprising at least about 10 % by weight copper
with a first solution to convert at least a portion of
the copper containing material to a passivating
film, the first solution comprising a peroxide
compound, a first organic acid, and water and
having a pH from about 2 to about 6; and
contacting the passivating film with a second
solution to remove the passivating film, the second
solution comprising a second organic acid and
water.
In addition to the admitted prior art, the Examiner relies on the
following prior art references as evidence of unpatentability:
Uozumi 6,261,953 B1 July 17, 2001
Kondo 6,596,638 B1 July 22, 2003
Singh 6,594,024 B1 July 15, 2003
Shimazu 6,547,843 B2 Apr. 15, 2003
Miller 6,719,920 B2 April 13, 2004

The pending claims stand rejected and are presented for review as
follows:
1. Claims 1-3, 5, 7-11, 14 and 16 stand rejected under 35 U.S.C. §
103(a) as obvious over Uozumi in view of Kondo.
2. Claim 12 stands rejected under 35 U.S.C. § 103(a) as obvious
over Uozumi in view of Kondo, as applied to claim 10, and further in view
of Miller.
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3. Claim 13 stands rejected under 35 U.S.C. § 103(a) as obvious
over Uozumi in view of Kondo, as applied to claim 10, and further in view
of Shimazu.
4. Claims 17-20 stand rejected under 35 U.S.C. § 103(a) as
obvious over Uozumi in view of Kondo and in view of Singh.
5. Claims 4, 6, and 15 stand rejected under 35 U.S.C. § 103(a)
over Uozumi in view of Kondo and further in view of the admitted prior art.
FINDINGS OF FACT (FF)
The following findings of fact are made based on substantial evidence
in the record.
1. Uozumi teaches a two-step etching process for copper
materials. The first step involves exposing the surface of the copper material
to an aqueous solution of hydrogen peroxide and ammonia. This causes a
reaction with the copper, forming a layer of copper oxide on the surface.
The copper oxide layer includes an ammonium complex. This layer does
not etch out the copper. Col. 9, ll. 42-50.
2. Uozumi further teaches that the oxide layer formed in the first
solution is subsequently removed, or etched, with a solution having a weak
oxidation potential, such as dilute hydrochloric acid or dilute aqueous
ammonia. Col. 9, ll. 50-55.
3. The inventor in Uozumi found “with pH of 10 or less, an oxide
film is formed on the surface of the copper film[,] whereas with pH of
greater than 10, copper is etched.” Col. 9, ll. 55-59.
4. In Kondo, Fig. 9 illustrates that a citric acid-based polishing
solution is within the domain of corrosion, forming soluble Cu2+ ions and
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Application 10/726,992

having a pH of about 2 and a weakly positive oxidation-reduction potential.
It further shows an aminoacetic acid-based polishing solution is within the
domain of passivation, forming insoluble copper oxide (CuO), having a pH
of about 7-8 and a weakly positive oxidation-reduction potential. See col. 6,
ll. 36-48; col. 12, ll. 61-65. Kondo teaches the desirability of using a
polishing solution in the corrosive, rather than passivating, domain. Col. 6,
ll. 48-50.

PRINCIPLES OF LAW
“Section 103 forbids issuance of a patent when ‘the differences
between the subject matter sought to be patented and the prior art are such
that the subject matter as a whole would have been obvious at the time the
invention was made to a person having ordinary skill in the art to which said
subject matter pertains.’” KSR Int'l Co. v. Teleflex Inc., 127 S. Ct. 1727,
1734 (2007)
The question of obviousness is resolved on the basis of underlying
factual determinations including (1) the scope and content of the prior art,
(2) any differences between the claimed subject matter and the prior art, (3)
the level of skill in the art, and (4) where in evidence, so-called secondary
considerations. Graham v. John Deere Co., 383 U.S. 1, 17-18 (1966)
A proper analysis under § 103 requires, inter alia, consideration of
two factors: (1) whether the prior art would have suggested to those of
ordinary skill in the art that they should make the claimed composition or
device, or carry out the claimed process; and (2) whether the prior art would
also have revealed that in so making or carrying out, those of ordinary skill
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would have a reasonable expectation of success. Velander v. Garner,
348 F.3d 1359, 1363 (Fed. Cir. 2003).
“A reference may be said to teach away when a person of ordinary
skill, upon reading the reference, would be discouraged from following the
path set out in the reference, or would be led in a direction divergent from
the path that was taken by the applicant. The degree of teaching away will
of course depend on the particular facts; in general, a reference will teach
away if it suggests that the line of development flowing from the reference’s
disclosure is unlikely to be productive of the result sought by the applicant.”
In re Gurley, 27 F.3d 551, 552-53 (Fed. Cir. 1994).

DISCUSSION
In the Final Office Action, claim 1 was rejected as obvious over
Uozumi in view of Kondo. The Examiner contends that Uozumi teaches a
method of etching copper. The method involves first exposing a copper
material to a hydrogen peroxide, and then removing the copper oxide formed
using an acid solution., where the acid may be an organic acid. Ans. 3. The
Examiner finds that the difference in Uozumi from claim 1 is Uozumi’s first
solution of aqueous ammonia and hydrogen peroxide instead of an aqueous
organic acid and peroxide. Ans. 3-4.
The Examiner finds that Kondo discloses a method of polishing
copper, using aqueous citric acid and hydrogen peroxide, the solution having
a pH in the range of 2 – 6. The Examiner finally contends that a person of
ordinary skill would find it obvious to replace the first solution of Uozumi
(aqueous ammonia and hydrogen peroxide) with that of Konda (aqueous
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citric acid and peroxide). The Examiner’s rationale is that one skilled in the
art would have been motivated to replace the first solution of Uozumi with
the more corrosive one of Konda because the higher etch rate and a wide
range of stability of the Kondo solution would provide better process
control. Ans. 4.
The Examiner also notes Uozumi’s second solution is an mineral
acid, rather than the organic acid of claim 1. The Examiner then asserts that
one skilled in the art would have substituted the Kondo organic acid
solution, without peroxide, because the organic acid solution would dissolve
any byproduct of the first reaction and, lacking peroxide, would stabilize the
surface from further oxidation. Ans. 15.
Appellant disputes the Examiner’s conclusion of obviousness, both to
the substitution of the Kondo solution for the first Uozumi solution, and for
the modified (i.e., without peroxide) Kondo solution for the second Uozumi
solution.
As to the first Uozumi solution substitution, Appellant argues that the
substitution would not be obvious because (1) it would fundamentally
change the process of Uozumi, (2) Kondo is directed to a corrosive solution
to achieve high etch rates for removing large amounts of material, and (3)
Kondo teaches against the use of citric-acid/hydrogen peroxide solutions for
the purpose of forming an insoluble passivation layer. App. Br. 5-6.
Appellant then argues that one skilled in the art would not find substituting
the Kondo solution for the second Uozumi solution obvious because it
would contradict the basic requirements of the second Uozumi solution.
Uozumi’s second solution is specified as a weakly oxidizing solution, which
Uozumi achieves with a dilute inorganic acid. In contrast, an organic acid,
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as used in Kondo, has no oxidation potential. Appellant asserts that organic
and inorganic acids are not equivalent. App. Br. 9.
We find Appellant’s arguments persuasive. A critical limitation of the
first solution of claim 1 is that this solution must convert a portion of a
copper material to a passivating film. One of ordinary skill in the art would
have understood passivation of a metallic material as the reaction of metal at
the surface with formation of a protective oxide film that inhibits further
corrosion.1 In contrast, one of ordinary skill in the art would have
distinguished this from corrosion, which is gradual destruction of a metal or
alloy due to chemical processes such as oxidation.2 One skilled in the art
would understand passivation as the formation of a thin film of oxidation
products on the surface, serving as a barrier to further oxidation or corrosion.
Uozumi discusses the prior art of etching, noting that aqueous
solutions of ammonia/hydrogen peroxide or hydrochloric acid/hydrogen
peroxide are used to etch copper, but these leave a rough surface. These
etch copper (i.e., are corrosive). Uozumi addresses this problem with a two-
step etching process, the first step using a mildly alkaline aqueous solution
of hydrogen peroxide and ammonia. This forms a thick oxide film including
an ammonia complex on the surface, which does not etch out the copper.
FF 1. This oxide film is then etched out using either an acid with weak
oxidizing properties, such as dilute hydrochloric acid or an alkali with weak
oxidizing properties, such as dilute aqueous ammonia. FF 2. Though not
using the term, one of ordinary skill in the art would have recognized this

1 See McGraw-Hill Dictionary of Scientific and Technical Terms 1455
(Sybil P. Parker ed. 1994).
2 See McGraw-Hill Dictionary of Scientific and Technical Terms 467 (Sybil
P. Parker ed. 1994).
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Application 10/726,992

first step as forming a passivation layer. As noted in Uozumi, “The
experiments conducted by the present inventor demonstrated such a property
that with pH of 10 or less, an oxide film is formed on the surface of the
copper film [passivated], whereas with pH of greater than 10, copper is
etched [corroded].” FF 3. The second solution of Uozumi is then used to
dissolve, or “etch” this oxide or passivation layer. FF 2.
In contrast, the solution in Kondo is intended to be corrosive and not
passivating. Fig. 9 of Kondo indicates that the citric acid and nitric acid-
based polishing solutions having pHs of 2 and 3, respectively, and positive
oxidation –reduction potentials are within the domain of corrosion, in which
soluble Cu2+ is formed, whereas an aminoacetic acid-based polishing
solution has an alkaline pH and is in the domain of passivation in which
insoluble copper oxide (CuO) is formed. FF 4. Thus, we determine that one
of ordinary skill in the art would not have expected that a substitution of the
Kondo solution (citric acid / hydrogen peroxide, pH 3) for the first Uozumi
solution (ammonia / hydrogen peroxide, pH 8-10) would likely succeed in
producing the desired insoluble passivation (oxide) layer on the copper
surface. Velander v. Gardner, 348 F.3d at 1363. Kondo, we further
determine, teaches away from such a combination, as it indicates its solution
is corrosive, not passivating, and would discourage one skilled in the art
from following the line of development of the Appellants. Gurley, 27 F.3d
at 552-53.
Accordingly, we determine that Appellant has established that the
Examiner committed reversible error in rejecting claim 1 as obvious over
Uozumi in view of Kondo. The remaining claims depend on claim 1 and
thus the rejection of these claims is not sustained since Miller, Shimazu,
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Singh, and the “admitted prior art” have been applied to show limitations of
the dependent claims and do not cure the deficiencies discussed above. The
decision of the Examiner is reversed.

REVERSED

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