Cymer, LLC

Patent Trials and Appeals Board

Jun 9, 2020

14681675 - (D) (P.T.A.B. Jun. 9, 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.
14/681,675 04/08/2015 Rahul Ahlawat 2014P00140US/002-114001 2017
86823 7590 06/09/2020
ASML CIP (San Diego) / DMIPG
c/o ASML Netherlands B.V.
PO Box 324
Veldhoven, 5500 AH
NETHERLANDS
EXAMINER
HAGAN, SEAN P
ART UNIT PAPER NUMBER
2828
NOTIFICATION DATE DELIVERY MODE
06/09/2020 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):
contact@dmipgroup.com
docketing@dmipgroup.com
sarah.briggs@asml.com
PTOL-90A (Rev. 04/07)

UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte RAHUL AHLAWAT
____________

Appeal 2019-003536
Application 14/681,675
Technology Center 2800
____________

Before JEFFREY T. SMITH, KAREN M. HASTINGS, and
DONNA M. PRAISS, Administrative Patent Judges.

PRAISS, Administrative Patent Judge.

DECISION ON APPEAL1
Appellant2 appeals under 35 U.S.C. § 134(a) from the Examiner’s
decision rejecting claims 1–5, 7–13, 15–30, 32, and 33. We have jurisdiction
over the appeal under 35 U.S.C. § 6(b).
We REVERSE.

1 Our Decision refers to the Specification (“Spec.”) filed Apr. 8, 2015, the
Final Office Action dated May 18, 2018 (“Final Act.”), Appellant’s Appeal
Brief (“Appeal Br.”) filed Dec. 17, 2018, the Examiner’s Answer (“Ans.”)
dated Feb. 8, 2019, and Appellant’s Reply Brief (“Reply Br.”) filed Apr. 2,
2019.
2 We use the word “Appellant” to refer to “applicant” as defined in
37 C.F.R. § 1.42. Appellant identifies Cymer, LLC as the real party in
interest. Appeal Br. 1.
Appeal 2019-003536
Application 14/681,675

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STATEMENT OF THE CASE
The invention relates to wavelength stabilization of an optical source.
Spec. 1:4. Claim 1, reproduced below from the Claims Appendix to the
Appeal Brief, is illustrative (disputed limitations italicized).
1. A method comprising:
receiving a pulsed light beam emitted from an optical
source, the pulsed light beam comprising at least a first burst of
pulses of light and a second burst of pulses of light, the first
burst of pulses comprising a first subset of pulses and the
second burst of pulses comprising a second subset of pulses;
determining a wavelength error for each pulse in the first
subset of pulses;
determining a correction signal based on the determined
wavelength error, the correction signal comprising a correction
signal associated with each pulse in the first subset of pulses;
applying a correction based on the determined correction
signal to each pulse in the second subset of pulses, wherein
the correction signal is determined during
operation of the optical source and without prior
knowledge of an operating condition of the optical
source, and
applying the correction to a pulse in the second
subset of pulses reduces the wavelength error of the pulse
in the second subset of pulses;
after the correction is applied, determining whether the
wavelength error of each pulse in the second subset of pulses is
outside of a wavelength error range defined by an upper
wavelength error bound and a lower wavelength error bound;
and
if the wavelength error for more than a threshold number
of pulses in the second subset of pulses is outside of the
wavelength error range, determining a second correction
signal based on the wavelength error of the second subset of
pulses to apply to a subset of pulses in a subsequent burst of
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Application 14/681,675

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pulses, wherein
the wavelength error for any particular pulse is a
difference between a wavelength of that particular pulse
and a target wavelength.
Claims 18, 23, and 24 are also independent. Claim 18 is directed to a
method that also requires “applying a correction based on the correction
signal to a second subset of pulses.” Claim 23, directed to a controller, and
claim 24, directed to a light system, both require determining a correction
signal if more than a threshold number of pulses is outside a wavelength
error range.
ANALYSIS
We review the appealed rejections for error based upon the issues
Appellant identifies. Ex parte Frye, 94 USPQ2d 1072, 1075 (BPAI 2010)
(precedential) (cited with approval in In re Jung, 637 F.3d 1356, 1365 (Fed.
Cir. 2011) (“[I]t has long been the Board’s practice to require an applicant to
identify the alleged error in the examiner’s rejections.”)). After considering
the positions of both the Examiner and Appellant, we are persuaded the
Examiner reversibly erred for the reasons set forth in Appellant’s briefs and
discussed below.
The Examiner rejects the claims as follows:
Claim(s) 35 U.S.C. § References
1–5, 9, 10, 12, 13,
15–23, 28–30, 32, 33 103 Spangler,
3 Everage4
7, 11 103 Spangler, Everage, Riggs5

3 US 2002/0006149 A1, published Jan. 17, 2002. We adopt the Examiner’s
reference to “Spangler 2” for citations to a second process described in
paragraph 78 of Spangler. See, e.g., Final Act. 9.
4 US 6,078,599, issued June 20, 2000.
5 US 2011/0116522 A1, published May 19, 2011.
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Application 14/681,675

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Claim(s) 35 U.S.C. § References
8 103 Spangler, Everage, Takeda6
24–27 103 Spangler, Heintze7

Final Act. 7–24. We address each of the rejections below.
Rejection over Spangler and Everage
The Examiner rejects claims 1–5, 9, 10, 12, 13, 15–23, 28–30, 32, and
33 over Spangler’s method for correcting wavelength error as modified by
Everage’s disclosure that the correction signal is determined without prior
knowledge of an operating condition of optical source, thereby allowing
minor adjustments to be eliminated, and further modified by, inter alia,
Spangler’s second disclosed process (Spangler 2) comparing the average
deviation in determining if a correction is to be made. Final Act. 7–19.
Appellant argues that the Examiner erred in modifying Spangler’s
first process (Spangler, Fig. 11), which uses a feed forward algorithm, with
Spangler’s separate embodiment (Spangler ¶ 78), which relates to a
feedback control algorithm. Appeal Br. 7–9. Appellant contends that even if
Spangler 2 teaches “a wavelength error of each pulse in the second subset of
pulses is outside of a wavelength error range defined by an upper
wavelength error bound and a lower wavelength error bound,” which
Appellant disputes (Appeal Br. 14–16), paragraph 78 does not disclose that
the adjustment is applied to a subset of pulses in a subsequent burst of
pulses. Id. at 9. Regarding Everage, Appellant contends that neither of those
claim limitations is disclosed by Everage either. Id. at 10. According to
Appellant, Everage’s “learning step 54” dynamically determines a number

6 US 5,473,409, issued Dec. 5, 1995.
7 US 2004/0021840 A1, published Feb. 5, 2004.
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of pulses that constitute the wavelength chirp, then determines the
wavelength shift of each sampled pulse to determine a pattern or shape of
the wavelength chirp. Id. (citing Everage 4:39–44).
Regarding the difference between Spangler and Spangler 2, Appellant
contends Spangler’s adaptive feed-forward algorithm separates a burst of
pulses into two regions: an L region and a K region. Appeal Br. 11. The K
region is said to have a wavelength with relatively high variation pulse-to-
pulse, and the L region of the burst has a relatively low wavelength variation
pulse-to-pulse. Id. at 12 (citing Spangler ¶ 26). According to Appellant,
because the L region has different characteristics than the K region, the
technique applied to the K region is intentionally different from the
technique applied to the L region, thus a skilled artisan would have had no
reason to modify the K region processing of Spangler’s feed-forward
algorithm with the alternative L region processing technique of Spangler 2.
Id. (citing Spangler, Fig. 11 in which “proportional constant Pk” and
“integral constant Ik” is not applied to each pulse in the L region).
The Examiner responds that Spangler 2’s technique may be
implemented prior to execution of the correction signal calculation step for
the K region of pulses in Spangler, thus requiring only a change in input to
the process of Spangler rather than a process redesign. Ans. 8. The Examiner
finds that Spangler 2 teaches the determined error signal may first be filtered
according to a deviation from a desired value such that the correction signal
is only computed in the case of a large deviation and this can be employed in
computing the feed forward correction signal for correcting the K region
pulses. Id. at 7.
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Regarding an average of some sort with Spangler’s single pulse, the
Examiner responds that application of Spangler 2’s technique to the process
of creating a correction signal for the K region, consideration of the line
center error of the kth pulse would necessarily be performed for calculating
the wavelength correction to be applied to the kth pulse of the subsequent
burst. Id. at 10–11. The Examiner also finds an average can be determined
from a list of numbers, including a list having a singular number. Id. at 14–
15.
Regarding modification of Spangler’s process shown in Figure 11, the
Examiner finds the creation of a correction signal created for the L region
determines deviation based on average deviations of previous pulses, thus
fewer pulses results in greater sensitivity to deviations whereas the use of
more pulses results in lesser sensitivity. Id. at 11–12. Modifying the
teachings of Spangler with the technique of Spangler 2, the Examiner finds a
different correction signal for the K region of pulses will be produced for
each burst until no pulse in the K region exceeds the upper or lower
threshold deviation. Id. at 12. The Examiner also explains that modification
of Spangler 2’s technique is a consequence of fitting the technique to the
available resources in Spangler and, thus, obvious. Id. at 13.
In the Reply Brief, Appellant contends incorporating Spangler 2 into
the process of Spangler’s Figure 11 is not simply a “change in the input” to
Equation 1 as the Examiner finds. Reply Br. 5. Appellant argues it would be
a substantial redesign because the K region processing of Spangler’s Figure
11 uses line center error (LCE) values, deviations from a target wavelength,
and the sum of LCEs for pulses up to and including current pulse k in burst t
which requires determining LCE for each distinct pulse, which Spangler 2
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does not produce. Id. at 6. According to Appellant, Spangler 2 is therefore
not applicable to determining the LCE value for each pulse k in Spangler’s
correction signal calculation because Spangler 2 is a feedback algorithm that
relies on data related past pulses, thus it would be contrary to Spangler 2’s
purpose to average only the wavelength of the current pulse k then find the
deviation of the wavelength of the current pulse k absent impermissible
hindsight. Id. at 6–7.
Appellant’s arguments are persuasive of harmful error. The
Examiner’s rejection does not adequately explain why a person having
ordinary skill in the art would modify Spangler with Spangler 2’s feedback
system absent hindsight from Appellant’s disclosure. Appellant’s position
that there is no reason, based on the Spangler 2 embodiment, for a skilled
artisan to average only the wavelength of the current pulse k absent
impermissible hindsight because Spangler 2 is a feedback system is
supported by the record. Spangler ¶ 78. Even if Spangler 2 performs a
calculation pulse to pulse (Ans. 8), the Examiner does not adequately
explain why a skilled artisan would understand Spangler 2 to broadly
suggest modifying Spangler’s process to insert error deviation appropriate to
the K region prior to the step of calculating the correction for the K region.
We also find the Examiner’s reasoning to lack rational underpinnings
because the Examiner acknowledges a mathematical average does not
require more than two numbers or values (Ans. 14), but nevertheless
determines Spangler 2’s averaging technique can be applied to a single pulse
on the basis that an average is of a list of numbers and a list may consist of
only one number (id. at 14–15).
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In view of the above, we reverse the Examiner’s rejection of
independent claim 1 over Spangler and Everage.

Remaining Rejections
Appellant relies on the same arguments presented with respect to
claim 1 in asserting that claims 7, 8, 11, and 24–27 are patentable over the
modification of Spangler with Spangler 2. Appeal Br. 17–21. The
Examiner’s additional findings regarding dependent claims 7, 8, and 11 do
not cure the deficiencies discussed above with regard to independent claim
1. Therefore, we do not sustain the Examiner’s rejection of dependent claims
7, 8, and 11 under § 103 over the combination of Spangler and Everage with
secondary references. Because claim 24, and claims 25–27 which depend
from claim 24, require determining a correction signal if more than a
threshold number of pulses is outside a wavelength error range as discussed
above in connection with claim 1, we reverse the Examiner’s rejection of
claims 24–27 for the same reason.

CONCLUSION
For these reasons, we reverse the Examiner’s rejection of claims 1–5,
7–13, 15–30, 32, and 33 under 35 U.S.C. § 103.

Appeal 2019-003536
Application 14/681,675

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DECISION SUMMARY
In summary:
Claim(s)
Rejected
35 U.S.C.
§ Reference(s)/Basis Affirmed Reversed
1–5, 9, 10,
12, 13, 15–
23, 28–30,
32, 33
103 Spangler, Everage
1–5, 9, 10,
12, 13, 15–
23, 28–30,
32, 33
7, 11 103 Spangler, Everage, Riggs 7, 11
8 103 Spangler, Everage, Takeda 8
24–27 103 Spangler, Heintze 24–27
Overall
Outcome
1–5, 7–13,
15–30, 32,
33

REVERSED