Ex Parte Zeng

Board of Patent Appeals and Interferences

Sep 22, 2008

10679787 (B.P.A.I. Sep. 22, 2008)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
____________

Ex parte KEJUN ZENG
____________

Appeal 2008-3929
Application 10/679,787
Technology Center 1700
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Decided: September 22, 2008
____________

Before BRADLEY R. GARRIS, CHARLES F. WARREN, and
ROMULO H. DELMENDO, Administrative Patent Judges.

DELMENDO, Administrative Patent Judge.

DECISION ON APPEAL
STATEMENT OF THE CASE
Appellant appeals under 35 U.S.C. § 134 from a final rejection of
claims 32 and 33 (Appeal Brief filed April 16, 2007, hereinafter “Br.”; Final
Office Action mailed February 13, 2006). We have jurisdiction under 35
U.S.C. § 6(b).
We AFFIRM.
Appeal 2008-3929
Application 10/679,787

Appellant states that the invention relates to solder joints
(Specification, “Spec.,” ¶001).
Claim 32 on appeal reads as follows:
32. A solder joint structure for a semiconductor
apparatus having a top surface, comprising:
a two-layered copper structure at the top surface of the
semiconductor apparatus, having a bottom layer and a top layer,
the top layer about 0.6 µm thick;
a nickel layer sandwiched between and contacting the
two copper layers; and
a solder ball formed on and contacting the about 0.6 µm
thick copper layer.

The Examiner relied upon the following prior art references in support
of the rejections:
Erickson 6,180,265 B1 Jan. 30, 2001
Ling 6,445,069 B1 Sep. 3, 2002
Huang 6,452,270 B1 Sep. 17, 2002
The Examiner rejected the claims under 35 U.S.C. § 103(a) as
follows: (i) claim 32 as unpatentable over the combined teachings of
Erickson and Ling; and (ii) claim 33 as unpatentable over the combined
teachings of Erickson, Ling, and Huang (Examiner’s Answer mailed August
13, 2007, hereinafter “Ans.,” 3-8).

ISSUE
Has Appellant demonstrated error in the Examiner’s determination
that a person a having ordinary skill in the art would have found the subject
matter of the appealed claims obvious in view of the applied prior art?

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Application 10/679,787

FINDINGS OF FACT
1. Appellant’s Figure 2A is reproduced below:

2. Appellant’s Figure 2A is said to depict a cut-away partial side
view of a portion of a circuit board (PCB or component
substrate) including a bond pad illustrating an example
embodying the invention, wherein 16 is a solder ball (Spec.
¶¶016, 020).
3. Appellant’s Specification states: “A copper layer 22 thickness
in excess of about 6 microns, however, provides abundant
copper to diffuse through the intermetallic compounds formed
at the interface of the solder joint, forming a great amount of
Kirkendall voids and thus resulting in a weak bond” (¶023).
4. Erickson describes a flip chip solder bump pad (Figure 3).
5. Erickson’s Figure 3 is reproduced below:
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Application 10/679,787

6. Erickson’s Figure 3 is said to depict a flip chip solder bump
pad, wherein 10 is an IC device, 12 aluminum wire bond pad,
14 is a square-shaped opening, 16 is a passivation layer of a
dielectric material, 24 is a nickel layer, 22 is a copper bond pad,
and 26 is a solder bump (col. 3, l. 27 to col. 4, l. 28).
7. Ling teaches (col. 1, ll. 6-12):
Manufacturers of semiconductor integrated
circuits have been experimenting with the use of
copper to form the interconnect metallization upon
integrated circuits. Copper has much better
conductivity than the traditional aluminum
metallization that has been used in past years, and
improved conductivity is essential to achieve
higher speed operation. [Emphasis added.]
8. Ling further teaches that “solder bumps are often formed on
integrated circuit wafers of the type that are used in providing
so-called flip chip integrated circuit packages and/or chip scale
packages” (col. 1, ll. 20-23).
9. In describing Figure 1 (col. 3, l. 48 to col. 4, l. 46), Ling teaches
that “metal interconnect layers have been formed of aluminum,
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Application 10/679,787

though copper is now being used to enhance the conductivity,
reliability and speed of circuitry, especially for very fine line
geometries used in advanced generations of integrated circuit
technologies” (col. 4, ll. 16-20).
10. Ling teaches that it is known that a nickel layer serves as a
barrier layer between copper and gold (col. 1, ll. 36-38).

PRINCIPLES OF LAW
On appeal to this Board, Appellant must show that the Examiner erred
in finally rejecting the claims. Cf. In re Kahn, 441 F.3d 977, 985-986 (Fed.
Cir. 2006) (“‘On appeal to the Board, an applicant can overcome a rejection
by showing insufficient evidence of prima facie obviousness or by rebutting
the prima facie case with evidence of secondary indicia of
nonobviousness.’”) (quoting In re Rouffet, 149 F.3d 1350, 1355 (Fed. Cir.
1998)); see also 37 C.F.R. § 41.37(c)(1)(vii).
“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).
KSR reaffirms the analytical framework set out in Graham v. John
Deere Co., 383 U.S. 1 (1966), which states that an objective obviousness
analysis includes: (1) determining the scope and content of the prior art; (2)
ascertaining the differences between the prior art and the claims at issue; and
(3) resolving the level of ordinary skill in the pertinent art. KSR, 127 S. Ct.
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at 1734. Secondary considerations such as commercial success, long felt but
unsolved needs, or failure of others “‘might be utilized to give light to the
circumstances surrounding the origin of the subject matter sought to be
patented.’” Id. (quoting Graham, 383 U.S. at 17-18).
KSR disapproved a rigid approach to obviousness (i.e., an analysis
limited to lack of teaching, suggestion, or motivation). KSR, 127 S. Ct. at
1741 (“The obviousness analysis cannot be confined by a formalistic
conception of the words teaching, suggestion, and motivation, or by
overemphasis on the importance of published articles and the explicit
content of issued patents.”). See also DyStar Textilfarben GmbH & Co.
Deutschland KG v. C.H. Patrick Co., 464 F.3d 1356, 1367 (Fed. Cir. 2006)
(“Our suggestion test is in actuality quite flexible and not only permits, but
requires, consideration of common knowledge and common sense”); Alza
Corp. v. Mylan Labs., Inc., 464 F.3d 1286, 1291 (Fed. Cir. 2006) (“There is
flexibility in our obviousness jurisprudence because a motivation may be
found implicitly in the prior art. We do not have a rigid test that requires an
actual teaching to combine...”).
KSR further instructs “that when a patent claims a structure already
known in the prior art that is altered by mere substitution of one element for
another known in the field, the combination must do more than yield a
predictable result.” KSR, 127 S. Ct. at 1740.
Any need or problem known in the field of endeavor at the time of the
invention and addressed by the prior art can provide a reason for combining
the elements in the manner claimed. KSR, 127 S. Ct. at 1742. See also In re
Kemps, 97 F.3d 1427, 1430 (Fed. Cir. 1996); In re Dillon, 919 F.2d 688, 693
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(Fed. Cir. 1990)(en banc) (the motivation to combine the prior art references
need not be identical to that of Applicants).
Also, mere attorney arguments or conclusory statements do not take
the place of evidence. See, e.g., In re Geisler, 116 F.3d 1465, 1470 (Fed.
Cir. 1997).

ANALYSIS
Appellant has argued the two rejections together, focusing on claim
32. Accordingly, we confine our discussion to claim 32. See 37 C.F.R. §
41.37(c)(1)(vii).
The Examiner found that Erickson describes a flip chip solder bump
pad structure including every element recited in appealed claim 32 except
that: (1) the prior art structure has an aluminum wire bond pad instead of the
here claimed copper pad; and (2) the prior art copper layer 22 thickness is
not disclosed (Facts 1, 2, and 4-6; Ans. 3-4). To account for the first
difference, the Examiner relied on the teachings of Ling, which states that
“[c]opper has much better conductivity than the traditional aluminum
metallization that has been used in past years, and improved conductivity is
essential to achieve higher speed operation” (Facts 7-9). Based on the
collective teachings of the prior art references, the Examiner concluded that
“[i]t would have been obvious to one of ordinary skill in the art at the time
of the invention to modify the pad material to utilize copper in order to
provide better thermal conductivity...” (Ans. 4). With respect to the
thickness of the copper layer 22, the Examiner held that it would have been
obvious for one of ordinary skill in the art to arrive at the claimed thickness
through routine optimization (Ans. 4).
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Appellant advances three arguments against the Examiner’s position
that a person having ordinary skill in the art would have found it obvious to
arrive at the here claimed subject matter. First, Appellant contends that
“[h]ad a person skilled in the art replaced the aluminum pad [of Erickson]
with a copper pad, as suggested in the Office Action, then the solderability
would have been realized, without the additional nickel layer and the top
layer” (Br. 3). Second, Appellant argues that “copper bond pads are difficult
for wire-bonding because the oxide layer formed on copper does not break
up during wire-bonding and reliable wire-bonds are difficult to make” (Br.
4). Third, Appellant urges that the prior art references do not recognize the
same problem solved by the present invention (Br. 4-5). Specifically,
Appellant asserts that “[t]he nickel layer is to reduce the out-diffusion of the
copper atoms from the top surface of the bottom copper pad where the
formation of excessive Kirkendall voids tends to degrade the reliability of
the [semiconductor] devices” (Br. 4).
None of Appellant’s arguments are persuasive to show error. Ling
provides strong evidence that copper wire bond pads have been used
advantageously, and interchangeably with aluminum pads, to form solder
joint structures when combined with other layers including a nickel layer.
Here, Ling teaches that copper wire bond pads exhibit superior conductivity,
reliability, and speed of circuitry (Facts 7-9). Thus, we share the Examiner’s
view that a person having ordinary skill in the art would have found it
obvious to replace the aluminum wire bond pad with a copper wire bond pad
in order to obtain the known advantages of copper wire bond pads. “[W]hen
a patent claims a structure already known in the prior art that is altered by
mere substitution of one element for another known in the field, the
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combination must do more than yield a predictable result.” KSR, 127 S. Ct.
at 1740.
We are also unpersuaded by Appellant’s allegation that “copper bond
pads are difficult for wire-bonding” (Br. 4). This allegation is
unsubstantiated by evidence and is therefore ineffective to rebut the
Examiner’s prima facie case of obviousness. In this regard, mere attorney
arguments or conclusory statements do not take the place of evidence. See,
e.g., In re Geisler, 116 F.3d at 1470.
Lastly, Appellant’s argument that the prior art does not recognize the
same problem (reduction of Kirkendall voids) is likewise unpersuasive.
Appellant’s Specification states: “A copper layer 22 thickness in excess of
about 6 microns, however, provides abundant copper to diffuse through the
intermetallic compounds formed at the interface of the solder joint, forming
a great amount of Kirkendall voids and this resulting in a weak bond” (Fact
3). Appellant has not shown that the problems addressed by the prior art are
in fact different from that of the present invention.1 Indeed, Ling teaches
that the nickel layer, like Appellant’s nickel layer, serves as a barrier layer
between copper and gold (Fact 10). Moreover, any need or problem known
in the field of endeavor at the time of the invention and addressed by the
prior art can provide a reason for combining the elements in the manner
claimed. KSR, 127 S. Ct. at 1742. See also In re Kemps, 97 F.3d at 1430; In
re Dillon, 919 F.2d at 693 (the motivation to combine the prior art references
need not be identical to that of applicant).

1 To the extent that Appellant relies on the claimed top copper layer
thickness, we have not been directed to any evidence demonstrating any
unexpected criticality for the claimed thickness.
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For these reasons, we uphold the Examiner’s obviousness rejections.

CONCLUSION
On this record, we determine that Appellant has failed to demonstrate
any error in the Examiner’s determination that claim 32 is unpatentable over
the combined teachings of Erickson and Ling and claim 33 is unpatentable
over the combined teachings of Erickson, Ling, and Huang.

DECISION
The Examiner’s decision to reject appealed claims 32 and 33 is
affirmed.
No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a)(1)(iv).
AFFIRMED

PL Initial:
sld

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Appeal 2008-3929
Application 10/679,787

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