ASML NETHERLANDS B. V.

Patent Trials and Appeals Board

Dec 17, 2020

2020000225 (P.T.A.B. Dec. 17, 2020)

UNITED STATES PATENT AND TRADEMARK OFFICE
UNITED STATES DEPARTMENT OF COMMERCE
United States Patent and Trademark Office
Address: COMMISSIONER FOR PATENTS
P.O. Box 1450
Alexandria, Virginia 22313-1450
www.uspto.gov
APPLICATION NO. FILING DATE FIRST NAMED INVENTOR ATTORNEY DOCKET NO. CONFIRMATION NO.
15/023,330 03/18/2016 Duan-Fu Stephen HSU 081468-0446230 1084
92703 7590 12/17/2020
Pillsbury Winthrop Shaw Pittman LLP(ASML)
P.O. Box 10500
McLean, VA 22102
EXAMINER
ASFAW, MESFIN T
ART UNIT PAPER NUMBER
2882
NOTIFICATION DATE DELIVERY MODE
12/17/2020 ELECTRONIC
Please find below and/or attached an Office communication concerning this application or proceeding.
The time period for reply, if any, is set in the attached communication.
Notice of the Office communication was sent electronically on above-indicated "Notification Date" to the
following e-mail address(es):
docket_ip@pillsburylaw.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte DUAN-FU STEPHEN HSU, RAFAEL C. HOWELL,
and FENG-LIANG LIU

Appeal 2020-000225
Application 15/023,330
Technology Center 2800
____________

Before ROMULO H. DELMENDO, JEFFREY B. ROBERTSON, and
MONTÉ T. SQUIRE, Administrative Patent Judges.

DELMENDO, Administrative Patent Judge.

DECISION ON APPEAL
The Appellant1 appeals under 35 U.S.C. § 134(a) from the Primary
Examiner’s final decision to reject claims 1, 3–15, and 17–22.2 We have
jurisdiction under 35 U.S.C. § 6(b).
We affirm.

1 We use the word “Appellant” to refer to “applicant” as defined in
37 C.F.R. § 1.42—i.e., “ASML Netherlands B.V.” (Application Data Sheet
filed March 18, 2016 at 1), which is also identified as the real party in
interest (Appeal Brief filed October 30, 2018 (“Appeal Br.”) at 2).
2 See Appeal Br. 2, 4–27; Reply Brief filed October 8, 2019 (“Reply Br.”) at
2–27; Final Office Action entered January 24, 2018 (“Final Act.”) at 2–8;
Examiner’s Answer entered August 8, 2019 (“Ans.”) at 3–16.
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I. BACKGROUND
The subject matter on appeal relates to (i) a computer-implemented
method to improve a lithographic process for imaging a portion of a design
layout onto a substrate using a lithographic projection apparatus having an
illumination source and projection optics and to (ii) a non-transitory
computer program product (Specification filed March 18, 2016 (“Spec.”)
Abstract and ¶¶ 57–77; Drawings filed March 18, 2016, Fig. 7).
Representative claim 1 is reproduced from the Claims Appendix to the
Appeal Brief, as follows:
1. A method to improve a lithographic process for imaging a
portion of a design layout onto a substrate using a lithographic
projection apparatus comprising an illuminator and projection
optics, the method comprising:
computing, by a hardware computer device, a multi-
variable cost function of a plurality of design variables that are
characteristics of the lithographic process, at least some of the
design variables being characteristics of the illumination
produced by the illuminator and of the design layout, wherein the
multi-variable cost function is (i) a function of a first
characteristic and a second characteristic of a three-
dimensional resist profile on the substrate, the first and second
characteristics of the three-dimensional resist profile associated
with portions of the three-dimensional resist profile at different
distances from the substrate, or (ii) a function of a first
characteristic and a second characteristic of a three-
dimensional radiation field projected from the projection optics,
the first and second characteristics of the three-dimensional
radiation field associated with portions of the three-dimensional
radiation field at different distances from the substrate, or (iii)
both (i) and (ii); and
reconfiguring one or more of the characteristics of the
lithographic process by adjusting the design variables until a
predefined termination condition is satisfied.
(Appeal Br. 29 (emphasis added)).
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II. REJECTION ON APPEAL
Claims 1, 3–15, and 17–22 stand rejected under 35 U.S.C. § 103 as
unpatentable over Tao et al.3 (“Tao”) in view of Liu4 (Final Act. 2–8; Ans.
3–16).
III. DISCUSSION
1. Grouping of Claims
Unless separately argued within the meaning of 37 C.F.R.
§ 41.37(c)(1)(iv), as discussed below, the rejected claims stand or fall with
claim 1, which we select as representative pursuant to the rule.
2. The Examiner’s Position
With respect to claim 1, the Examiner finds that Tao describes a
method for improving a lithographic process for imaging a portion of a
design layout onto a substrate, wherein the method includes steps with most
of the limitations recited in the claim (Final Act. 2–3). The Examiner states
that “Tao does not explicitly teach” (emphasis added) the disputed
limitations highlighted in reproduced claim 1 above (id. at 3). The Examiner
finds further, however, that Liu teaches lithography processes and a method
for modeling a three-dimensional spatial intensity distribution of radiation
formed within a resist layer and a three-dimensional resist image that meets
at least function (i) recited in claim 1 (id.). Based on these findings, the
Examiner concludes that “it would have been obvious to one of ordinary
skill in the art . . . to use a three-dimensional spatial intensity distribution
simulation method as disclosed by Liu in the method of the lithography

3 US 2013/0000505 A1, published January 3, 2013.
4 US 2013/0204594 A1, published August 8, 2013.
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process of Tao in order to optimize the result of the lithography process” (id.
at 4).
3. The Appellant’s Contentions5
The Appellant contends that the Examiner did not ascertain the level
of ordinary skill in the art as required under 35 U.S.C. § 103 (Appeal Br. 5–
6). According to the Appellant, the Examiner’s reasoning is based on
conclusory statements and uses the claimed invention as a “blueprint” in
reaching a conclusion of obviousness based on hindsight reconstruction (id.
at 6). Specifically, the Appellant argues that “[w]hat is at issue here is how
the cost function itself is configured[,]” emphasizing that the “claim refers to
configuration of the cost function, not to a simulation used to provide, e.g.,
simulated results to a cost function” (id. at 8). Regarding the combination of
Tao with Liu, the Appellant argues that “there is no proper reason presented
for why a person of ordinary skill in the art would consider applying the
three-dimensional spatial distribution simulation of Liu in Tao’s source and
mask optimization techniques” when “Tao already uses a simulation and
already performs an optimization” (id.). In the Appellant’s view, the
Examiner’s articulated reasoning is an aspirational goal that is not supported

5 In the Reply Brief, the Appellant alleges that the Examiner relies on new
findings in the Answer and that, therefore, a new ground of rejection should
have been designated (e.g., Reply Br. 3). 37 C.F.R. § 41.40(a) states,
however, that a request to seek review of a primary examiner’s failure to
designate a rejection as a new ground of rejection in an answer must be by
way of a timely petition pursuant to 37 C.F.R. § 1.181 and that the “[f]ailure
of appellant to timely file such a petition will constitute a waiver of any
arguments that a rejection must be designated as a new ground of rejection.”
Therefore, we do not address such a petitionable matter, which has been
waived.
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by evidence of record (id. at 8–9). Furthermore, the Appellant argues that
“there is no disclosure or teaching in Tao to make the claimed cost function
be a function of first and second characteristics of anything at different
distances from a substrate” (id. at 9; see also id. at 11–12 (arguing the same
with respect to Liu)).
4. Opinion
We have fully considered the Appellant’s arguments but find them
insufficient to identify reversible error in the Examiner’s rejection. In re
Jung, 637 F.3d 1356, 1365 (Fed. Cir. 2011).
With respect to the level of skill in the art, the Examiner focuses on
the teachings of the prior art references in analyzing obviousness (e.g., Ans.
3–4). We discern no reversible error in that approach, as both Tao and Liu,
which the Appellant states are assigned to it (Appeal Br. 8), establish the
relatively high level of ordinary skill in this art that is commensurate with
the level shown in the current Specification. In re GPAC Inc., 57 F.3d 1573,
1579 (Fed. Cir. 1995) (finding no error in the Board’s approach that the level
of skill in the art was best determined by the references of record); cf. In re
Basell Poliolefine Italia S.P.A., 547 F.3d 1371, 1379 (Fed. Cir. 2008) (“[W]e
find no basis for reversing the Board’s decision merely because the Board
failed to expressly set forth each of the Graham factors in its analysis. The
Board carefully considered claim 1 . . . and the claims of the [conflicting
patent] and determined that a person of ordinary skill in the art would have
found [claim 1’s subject matter] to have been obvious.”).
As for the articulated reasoning in support of the obviousness
conclusion, we turn to the prior art references. Consistent with the
Examiner’s detailed findings (Final Act. 2–3; Ans. 6), Tao describes a
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computer-implemented method for obtaining a preferred layout for a
lithographic process in which the method includes identifying an initial
layout including a plurality of features and reconfiguring the features until a
termination condition is satisfied, wherein reconfiguring comprises
evaluating a cost function that measures how a lithographic metric is
affected by a set of changes to the features for a plurality of lithographic
process conditions, and expanding the cost function into a series of terms at
least some of which are functions of characteristics of the features (Tao
¶¶ 15, 36, 58). Tao teaches using an optical model that may include the
effect of imaging into a thin-film resist or the effect of the mask topography,
wherein the resist model describes changes in the resist after being
illuminated by the mask pattern in the exposure tool (id. ¶ 31). According to
Tao, a model-based optical proximity correction (OPC) software is used to
determine a cost function in which the software simulates resist images to
evaluate whether a function that measures edge placement errors (EPE) is
minimized or below a certain threshold (id. ¶¶ 10, 32, 36, 54).
Liu teaches a method for simulating a three-dimensional spatial
intensity distribution of radiation formed within a resist layer on a substrate
resulting from an incident radiation, in which the simulation is for accurately
predicting, for example, edge placements, aerial image intensity slopes, and
critical dimensions, which can then be compared against an intended design
(Liu ¶¶ 14, 23, 35; Fig. 3). According to Liu, a “sufficiently accurate three-
dimensional resist image can help detection of patterning defects that
traditional two-dimensional resist image cannot detect” (id. ¶ 35).
Given the collective teachings found in these references, we agree
with the Examiner that a person having ordinary skill in the art would have
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been prompted to implement Liu’s simulation technique using three-
dimensional resist images and spatial intensity distribution of radiation in the
resist layer in Tao’s method, which calls for simulation, with a reasonable
expectation of improving pattern defect detection as taught by Liu. KSR
Int’l Co. v. Teleflex Inc., 550 U.S. 398, 416 (2007) (“[W]hen a patent claims
a structure already known in the prior art that is altered by the mere
substitution of one element for another known in the field, the combination
must do more than yield a predictable result.”); id. at 417 (“[I]f a technique
has been used to improve one device, and a person of ordinary skill in the art
would recognize that it would improve similar devices in the same way,
using the technique is obvious unless its actual application is beyond his or
her skill.”).
Thus, the interrelated teachings found in Tao and Liu amply support
the Examiner’s well-articulated reason for concluding that a person having
ordinary skill in the art would have combined these references in the manner
claimed by the Inventors. Id. at 418 (“Often, it will be necessary for a court
to look to interrelated teachings of multiple patents; the effects of demands
known to the design community or present in the marketplace; and the
background knowledge possessed by a person having ordinary skill in the
art.”).
We find no merit in the Appellant’s contention that claim 1 “refers to
configuration of the cost function, not to a simulation used to provide, e.g.,
simulated results to a cost function” (Appeal Br. 8). The current
Specification states that a “person skilled in the art will recognize that,
especially in the context of lithography simulation/optimization, the term
‘mask’/‘patterning device’ and ‘design layout’ can be used interchangeably”
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(Spec. ¶ 8). Given that claim 1 recites “design layout” in the context of a
“cost function” (Appeal Br. 29), the Appellant’s argument is directly
contradicted by the claim language itself.
As for the Appellant’s argument that “there is no disclosure or
teaching in the cited portions of Liu (or Tao) regarding, for example, a
multi-variable cost function that is a function of first and second
characteristics at different distances from the substrate” (Appeal Br. 11), we
find this argument to be contradicted by both references, which explicitly
disclose changes in the resist’s physical features (e.g., corner rounding
corrections), critical dimensions, or edge placement errors that, prima facie,
would necessarily involve characteristics at different distances from the
substrate (Tao ¶¶ 31–32, 36, 54; Liu ¶¶ 2, 13–14, 23, 35 and Fig. 3).
The Appellant provides arguments for certain other claims (Appeal
Br. 14–27). These additional arguments, however, are similar to those
offered for claim 1, and, in any event, are skeletal and lacking in detailed
analyses relative to the teachings found in the prior art references. In this
regard, merely pointing out what a claim recites or providing a skeletal
argument asserting that the prior art does not disclose or suggest the claimed
subject matter is not an argument for separate patentability that requires our
separate consideration. In re Lovin, 652 F.3d 1349, 1357 (Fed. Cir. 2011).
Even if we assume that the Appellant’s additional arguments are
arguments in support of separate patentability of certain additional claims,
the Examiner provides sufficient analyses (Final Act. 2–7; Ans. 8–16),
which we adopt as our own. In re Cree, Inc., 818 F.3d 694, 698 n.2 (Fed.
Cir. 2016); In re Brana, 51 F.3d 1560, 1564 n.13 (Fed. Cir. 1995).

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IV. CONCLUSION
For these reasons, and those well-stated by the Examiner, we uphold
the Examiner’s rejection.

V. DECISION SUMMARY
In summary:
Claims
Rejected
35 U.S.C. § Reference(s)/Basis Affirmed Reversed
1, 3–15,
17–22
103 Tao, Liu 1, 3–15,
17–22

No time period for taking any subsequent action in connection with
this appeal may be extended under 37 C.F.R. § 1.136(a).

AFFIRMED