Ex Parte Lu et al

Board of Patent Appeals and Interferences

Dec 20, 2010

10708748 (B.P.A.I. Dec. 20, 2010)

UNITED STATES PATENT AND TRADEMARK OFFICE
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BEFORE THE BOARD OF PATENT APPEALS
AND INTERFERENCES
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Ex parte WEI LU and CHESTER WASIK
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Appeal 2009-002846
Application 10/708,748
Technology Center 2800
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Before JOSEPH F. RUGGIERO, THOMAS S. HAHN, and
ELENI MANTIS MERCADER, Administrative Patent Judges.

HAHN, Administrative Patent Judge.

DECISION ON APPEAL1

1 The two-month time period for filing an appeal or commencing a civil
action, as recited in 37 C.F.R. § 1.304, or for filing a request for rehearing,
as recited in 37 C.F.R. § 41.52, begins to run from the “MAIL DATE”
(paper delivery mode) or the “NOTIFICATION DATE” (electronic delivery
mode) shown on the PTOL-90A cover letter attached to this decision.
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Appellants invoke our review under 35 U.S.C. § 134(a) from the final
rejection of claims 1-3, 6-8, 10, 13-15, 17, 19, and 20. We have jurisdiction
under 35 U.S.C. § 6(b). We affirm.

STATEMENT OF THE CASE2
Appellants claim a method for directing an electron beam onto a hole
sidewall in a structure, e.g., a partially completed integrated circuit, to
produce secondary electrons. The incident electron beam is angled onto the
sidewall so that the electron beam does not reach the bottom of the hole.
The produced secondary electrons break down a metal gas that surrounds the
structure to form a metal coating (Abstract). Claim 1 is illustrative:
1. A method of inspecting topographical features of the top
layer of a structure, said method comprising:
surrounding said structure with a precursor metal gas;
directing an angled electron beam at said structure where an
angle of said angled beam is selected to create secondary electron
beams as said angled electron beam strikes sidewalls of said
topographical features, comprising directing said electron beam at an
angle sufficient to cause said electron beam to strike the sidewalls of
said topographical features and prevent said electron beam from
reaching the bottom of said topographical features, wherein said
secondary beams have less energy than said angled electron beam,
and wherein said secondary electron beams break down said precursor
metal gas to form a metal coating on said structure;
directing an ion beam at said structure to form a groove within
said top layer of said structure, wherein said metal coating is adapted
to protect said topographical features from said ion beam; and

2 Throughout this opinion we refer for their respective details to the
Specification filed Mar. 23, 2004, the Appeal Brief filed Jan. 18, 2008, and
the Examiner’s Answer mailed May 8, 2008.
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inspecting said topographical features exposed by said groove
in said top layer of said structure.
Rejection
The Examiner rejected claims 1-3, 6-8, 10, 13-15, 17, 19, and 20
under 35 U.S.C. § 103(a) as being unpatentable over the combination of
Fujii, U.S. 5,574,280, and Kadyshevitch, U.S. 2004/0021076 A1.
Appellants’ Contentions
Appellants group independent claims 1, 8, and 15, and assert
patentability without separately arguing any identified claim (Br. 11-13).
We, accordingly, select independent claim 1 as representative for this group,
pursuant to our authority under 37 C.F.R. § 41.37(c)(1)(vii). Appellants
contend that Kadyshevitch, as relied on by the Examiner, teaches generation
of secondary electrons that are forced down into hole bottoms rather than
being moved out of holes where they could react with a metal gas to form a
metal coating. Appellants rely on this contention to argue that Kadyshevitch
teaches away from the invention recited in representative claim 1 (Br. 12).
Appellants group dependent claims 6, 13, and 19 and argue that these
claims are patentable because the prior art of record fails to teach or suggest
using an electron beam having an energy level approximately between 100
and 10,000 electron volts as recited in the claims (Br. 13-14).
Appellants separately argue dependent claim 7 (Br. 14-15) and rely on
the claim 7 asserted argument for further contending patentability for
grouped dependent claims 14 and 20 (Br. 15-16). The argument asserted for
claim 7 is that the prior art of record fails to teach or suggest directing an
electron beam onto a structure top layer surface at an angle between
approximately 20 and 70 degrees (Br. 14-15).

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ISSUES
Appellants’ contentions present us with the following issues:
1. Did the Examiner err in rejecting representative claim 1 as being
obvious because the relied on prior art fails to teach or suggest
generating secondary electrons that are brought out of holes to react
with a precursor metal gas to form a metal coating?
2. Did the Examiner err in rejecting claims 6, 13, and 19 as being
obvious because the relied on prior art fails to teach or suggest using
an electron beam having an energy level approximately between 100
and 10,000 electron volts?
3. Did the Examiner err in rejecting claims 7, 14, and 20 as being
obvious because the relied on prior art fails to teach or suggest
directing an electron beam onto a structure top layer surface at an
angle between approximately 20 and 70 degrees?

FINDINGS OF FACT
The following findings of fact (FF) are supported by a preponderance
of evidence:
Invention
1. Appellants disclose that:
The optimal angle of the incoming direct beam
will be dependent on the aspect ratio of height to
diameter of the contact. The beam should be angled so
that the direct beam does not hit the bottom of the contact
hole. . . . The best angle will have a reasonably rapid and
uniform metal deposition with minimized damage to
contact profile. For example, the angle could be around
45 degrees (in the range of 70 degrees to 20 degrees).
(Spec. ¶ [0034].)
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Kadyshevitch
2. Kadyshevitch discloses that a primary electron beam may be used to
precharge a wafer surface. Further Kadyshevitch discloses that
making the surface a “positive charging domain” causes secondary
electrons generated by the primary electron beam in a hole below the
surface to yield a greater secondary electron concentration about the
surface than that of the entering primary electron beam. Alternatively,
if the surface is made to be a “negative charging domain” then the
yield of secondary electrons about the surface reverses to be less than
that of the entering primary electron beam (¶ [0163]).
3. Kadyshevitch further discloses that:
The tilt angle of [an electron] beam 130 is preferably
chosen so that a majority of primary beam electrons do
not strike the bottom of the contact hole. This condition
can be achieved when the following geometrical
condition is satisfied:
α > arctan (1/AR),
wherein α is the tilt angle, and AR is the aspect
ratio (ratio of depth to diameter) of the contact hole.
(¶¶ [0198]-[0199].)

PRINCIPLE OF LAW
The Supreme Court has stated that obviousness “analysis need not
seek out precise teachings directed to the specific subject matter of the
challenged claim, for a court can take account of the inferences and creative
steps that a person of ordinary skill in the art would employ.” KSR Int’l Co.
v. Teleflex Inc., 550 U.S. 398, 418 (2007).

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ANALYSIS
Claims 1-3, 8, 10, 15, and 17
We are not persuaded by Appellants’ argument that Kadyshevitch
teaches away from representative claim 1 (Br. 12). In particular, we are not
persuaded by Appellants’ implied contention that Kadyshevitch’s teachings
are limited to generation of secondary electrons that are forced down into
hole bottoms rather than being moved out of holes where they could react
with a precursor metal gas to form a metal coating (id.). For example, the
Examiner finds that:
[O]ne of ordinary skill in the art would . . . interpret that
Kadyshevitch discloses using an electron beam to charge the
sample surface either positively or negatively, and that a
positively charged surface would not drive secondary electrons
to the bottom, but would provide an attractive potential to the
secondary electrons drawing them to the surface and making
them available for dissociation of a metal gas flooding the
surface.
(Ans. 9.) The Examiner cites Kadyshevitch, paragraph [0163], as authority
for these findings (Ans. 11). As does the Examiner, we also find from
Kadyshevitch that if a surface layer is made to be a “positive charging
domain” then the yield of secondary electrons about the surface is greater
than that of the primary electron beam (FF 2). Accordingly, we do not find
Appellants’ argument to be convincing, because we, as does the Examiner,
find that Kadyshevitch discloses an alternative embodiment that brings
generated secondary electrons out of holes as opposed to forcing them into
holes. We do not find any disclosure criticizing, discrediting, or otherwise
discouraging the Kadyshevitch taught embodiment for bringing secondary
electrons out of holes. Accordingly, despite Appellants’ contention, we do
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not find that Kadyshevitch teaches away. In re Fulton, 391 F.3d 1195, 1201
(Fed. Cir. 2004).
In the absence of a challenge from Appellants to the Examiner’s
conclusion that Kadyshevitch teaches “drawing [secondary electrons] to the
surface and making them available for dissociation of a metal gas flooding
the surface” (Ans. 9), we will sustain the rejection of representative claim 1.
We also will sustain the rejection of the other independent claims 8 and 15,
and we will sustain the rejection of dependent claims 2, 3, 10, and 17 that
are not separately argued (Br. 16).
Claims 6, 13, and 19
Each of these dependent claims, which are not separately argued,
recite “using an electron beam having an energy level of approximately
between 100 and 10,000 electron volts.” Appellants contend that the prior
art of record fails to teach or suggest using an electron beam having an
energy level approximately between 100 and 10,000 electron volts (eV) (Br.
13-14).
The Examiner cites Kadyshevitch, paragraph [0163], as disclosing use
of an electron beam having energy “typically between about 100 and 5,000
eV,” and the Examiner concludes that this teaching is included in the
claimed range between 100 and 10,000 eV (Ans. 10). On reviewing
Kadyshevitch, we agree with and adopt the Examiner’s finding, and we also
agree with the Examiner’s conclusion. Accordingly, we will sustain the
Examiner’s rejection of these claims.
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Claims 7, 14, and 20
Each of these dependent claims recites “directing said electron beam
at an angle between approximately 20 and 70 degrees with respect to the
surface.”
The Examiner finds Kadyshevitch “teaches directing said angled
electron beam at an angle sufficient to cause said electron beam to strike the
sidewalls of said topological features, and comprises tilting a stage . . . at an
angle between approximately 20 and 70 degrees with respect to the surface
of the top layer of said structure” (Ans. 7). The Examiner prefaces this
quoted statement with reference to “Fuji [sic] as described above regarding
claims 1, 8, and 15” (id.). However, on searching for the referred to
discussion, we fail to find Fujii identified, but instead find Kadyshevitch
identified. We specifically are referring to the Examiner’s statement that
“Kadyshevitch teaches angled irradiation of contact hole 26 by an electron
beam 130, where the tilt angle of beam 130 is preferably chosen so that a
majority of primary beam electrons do not strike the bottom of the contact
hole. See [0198] and Figure 11 . . . ” (Ans. 6). We, accordingly, treat the
Examiner’s reference to Fujii to be a typographical error that should instead
be a reference to Kadyshevitch.
Appellants contend:
Kadyshevitch fails to disclose an electron beam angled between
approximately 20 and 70 degrees with respect to the surface of
the top layer of the partially completed integrated circuit
structure. Instead, Kadyshevitch merely discloses that “the
particle beam irradiates the surface of the sample at a non-
normal angle, i.e., with at least a slight tilt” (Kadyshevitch,
para. 0017). Nevertheless, nothing within Kadyshevitch
discloses that the “slight tilt” can be between 20 and 70
degrees.
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(Br. 16.) We do not find that Appellants address the Kadyshevitch teachings
at paragraph [0198] that are cited by the Examiner.
Before turning to Kadyshevitch we note that Appellants’ Specification
discloses that (i) the electron beam should be angled so as not to hit a target
hole bottom; (ii) the optimal angle for directing an electron beam is
dependent on the aspect ratio, i.e. height to diameter of the hole; and (iii)
“the angle could be around 45 degrees (in the range of 70 degrees to 20
degrees)” (FF 1).
From Kadyshevitch, we find that a tilt angle for directing an electron
beam is taught as being chosen (i) “so that a majority of primary electrons
do not strike the bottom of the contact hole” and (ii) from a geometric
algorithm that is dependent on the “aspect ratio (ratio of depth to diameter)
of the contact hole” (FF 3).
We thus find that Kadyshevitch teaches Appellants’ disclosed
requirement that an electron beam be directed to not strike a target hole
bottom (FF 1, 3). Further, we find that Kadyshevitch teaches Appellants’
disclosure for selecting an optimal directing angle to achieve this result as a
function of aspect ratio for a target hole (id.). Finally, we do not find
evidence or persuasive argument that an optimal directing angle or range of
angles produces any unexpected result.
Based on the record, we conclude from Kadyshevitch’s teachings that
determination of a range for an electron beam directing angle, including the
recited “angle between approximately 20 and 70 degrees,” would have been
obvious to an ordinarily skilled artisan. KSR, 550 U.S. at 418.
For the foregoing reasons, we will sustain the Examiner’s rejection of
claims 7, 14, and 20.
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ORDER
The Examiner’s decision rejecting claims 1-3, 6-8, 10, 13-15, 17, 19,
and 20 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

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FREDERICK W. GIBB, III
Gibb Intellectual Property Law Firm, LLC
844 West Street
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