Tokyo Electron Limited

Patent Trials and Appeals Board

Sep 10, 2020

15191956 - (D) (P.T.A.B. Sep. 10, 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.
15/191,956 06/24/2016 Subhadeep Kal 4284-0129 6351
172453 7590 09/10/2020
TEL/RFEM
607 14th Street NW
Suite 800
Washington, DC 20005
EXAMINER
DAHIMENE, MAHMOUD
ART UNIT PAPER NUMBER
1713
NOTIFICATION DATE DELIVERY MODE
09/10/2020 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):
pto-pat-email@rfem.com
PTOL-90A (Rev. 04/07)
UNITED STATES PATENT AND TRADEMARK OFFICE
____________

BEFORE THE PATENT TRIAL AND APPEAL BOARD
____________

Ex parte SUBHADEEP KAL, NIHAR MOHANTY,
ANGELIQUE D. RALEY, AELAN MOSDEN, and SCOTT W. LEFEVRE1
____________

Appeal 2019-006576
Application 15/191,956
Technology Center 1700
____________

Before CATHERINE Q. TIMM, DONNA M. PRAISS, and
CHRISTOPHER C. KENNEDY, Administrative Patent Judges.

KENNEDY, Administrative Patent Judge.

DECISION ON APPEAL
This is an appeal under 35 U.S.C. § 134(a) from the Examiner’s
decision rejecting claims 1, 3–15, 17, and 19–21.2 An oral hearing was held
on August 25, 2020. We have jurisdiction under 35 U.S.C. § 6(b).
We AFFIRM IN PART.

1 We use the word “Appellant” to refer to “applicant” as defined in
37 C.F.R. § 1.42. The Appellant identifies the real party in interest as Tokyo
Electron Limited. Appeal Br. 1.
2 In the Examiner’s Answer, the Examiner withdraws the rejection of
claim 16. Ans. 10.
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BACKGROUND
The subject matter on appeal relates to methods for the dry removal of
a material on a microelectronic workpiece, such as a semiconductor. E.g.,
Spec. ¶¶ 1, 7, 21; Claim 1. Claim 1 is reproduced below from page 23
(Claims Appendix) of the Appeal Brief (some formatting added):
1. A method for the dry removal of a material on a microelectronic
workpiece, comprising:
receiving a workpiece having a multi-layer mask that includes:
(i) a patterned layer and (ii) a surface exposing a target layer
composed of silicon and either (1) organic material or (2) both
oxygen and nitrogen;
placing the workpiece in a processing chamber consisting of a
dry, non-plasma etch chamber and locating the workpiece on a
workpiece holder; and
operating the dry, non-plasma etch chamber to selectively
remove at least a portion of the target layer from the workpiece
by performing the following:
exposing the surface of the workpiece to a chemical
environment containing a gaseous mixture that includes N, H,
and F at a first workpiece setpoint temperature to chemically
alter a surface region of the target layer and to chemically
alter a depth within the target layer such that, after the
exposing, the target layer includes a chemically altered
surface region and a chemically altered depth within the target
layer, wherein the N, H, and F are introduced to the dry, non-
plasma etch chamber simultaneously,
establishing the surface of the workpiece at the first
workpiece setpoint temperature by flowing a heat transfer
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fluid through the workpiece holder at a first fluid setpoint
temperature;
monitoring, by a temperature sensing device, a temperature of
the workpiece holder; and
after establishing the surface of the workpiece at the first
workpiece setpoint temperature, elevating the temperature of
the workpiece to a second workpiece setpoint temperature by
adjusting a flow rate of the heat transfer fluid flowing through
the workpiece holder based on the monitored temperature of
the workpiece holder by the temperature sensing device,
wherein prior to elevating the temperature of the workpiece
to the second workpiece setpoint temperature, the target layer
includes the chemically altered surface region and the
chemically altered depth within the target layer, and elevating
the temperature of the workpiece to the second workpiece
setpoint temperature volatilizes and selectively removes the
chemically altered surface region and the chemically altered
depth of the target layer without removing the patterned layer.
ANALYSIS
Claims 1, 3–15, 17, and 19–21 stand rejected under 35 U.S.C. § 103
as unpatentable over Tang (US 8,501,629 B2, issued Aug. 6, 2013), Wang
(US 2014/0308818 A1, published Oct. 16, 2014), and Tabuchi (WO
2014/014127 A1, published Jan. 23, 20143). The Appellant presents
separate arguments only as to claims 1 and 17. See generally Appeal Br.
We address those claims below. The remaining claims on appeal will stand
or fall with claim 1.
After review of the cited evidence in the appeal record and the
opposing positions of the Appellant and the Examiner, we determine that the

3 The Examiner relies on corresponding U.S. Publication
No. 2015/0176928 A1, published June 25, 2015, as an English language
translation.
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Appellant has not identified reversible error in the Examiner’s rejection of
claim 1. Accordingly, we affirm that rejection for reasons set forth below, in
the Final Action dated October 31, 2018, and in the Examiner’s Answer
dated July 3, 2019. However, as set forth below, we reverse as to claim 17.
Claim 1. The Examiner’s rejection appears at pages 2–8 of the Final
Action. Of particular relevance to the issues raised by the Appellant in this
appeal, the Examiner finds that Tang discloses a SiConi™ etch process in
which a workpiece with a target layer of silicon oxide is etched at a first
temperature by being exposed to a chemical environment as recited by
claim 1, resulting in the formation of by-products on the workpiece. Final
Act. 3, 5. The Examiner finds that etching by exposure to a chemical
environment that falls within the scope of the chemical environment recited
by claim 1 corresponds to the “exposing” step of claim 1, and that the by-
products formed by the etching correspond to the “chemically altered
surface region” and “chemically altered depth within the target layer,” as
recited by claim 1. Id. at 3–5, 8. The Examiner finds that Tang discloses
that those by-products are then removed by heating the workpiece to a
second temperature, which sublimates the by-products. Id. at 5; Ans. 10.
The Examiner acknowledges that “Tang does not expressly
disclose . . . a target layer composed of silicon and both oxygen and
nitrogen.” Id. at 3. The Examiner finds, however, that Wang teaches a
similar SiConi™ etch process, and that Wang discloses that the silicon oxide
in its process “may include minority concentrations of other elemental
constituents such as nitrogen, hydrogen, carbon, and the like.” Id. at 3–4.
The Examiner determines:
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Therefore, it would have been obvious to one of ordinary skill in
the art, at the time the invention was filed to expect “Silicon
oxide” may include minority concentrations of other elemental
constituents such as nitrogen, hydrogen, carbon and the like since
perfectly pure silicon oxide does not exist.
Id. at 4.
In view of those and other findings less relevant to the issues raised by
the Appellant, the Examiner concludes that the subject matter of claim 1
would have been obvious to a person of ordinary skill in the art.
The Appellant argues that Tang’s process does not “chemically alter a
surface region of the target layer” and “chemically alter a depth within the
target layer,” as required by claim 1, because Tang’s process actually
removes the target layer and forms a new by-product layer that is
subsequently removed via sublimation. Appeal Br. 9–12 (“Tang repeatedly
makes clear that its method is not chemically altering an existing target
layer, followed by removal of the chemically altered surface and depth of the
target layer, but rather, Tang first performs a plasma etch removal, during
which new by-products are formed, followed by sublimation removal of the
by-products.”).
Under the applicable claim interpretation standard (broadest
reasonable construction consistent with the specification, see In re ICON
Health & Fitness, Inc., 496 F.3d 1374, 1379 (Fed. Cir. 2007)), we are not
persuaded of reversible error in the Examiner’s determination that the prior
art process falls within the scope of claim 1. Consistent with the Appellant’s
argument, we recognize that, in some instances, Tang uses language
indicating that its target layer is removed and replaced with a different (by-
product) layer, e.g., Tang at 1:41–43 (“The SiConi™ process produces solid
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by-products which grow on the surface of the substrate as substrate material
is removed.”), 9:42–43 (using the word “accumulation” to describe by-
products); see also Reply Br. 5.
However, when Tang describes in more detail how its process works,
Tang’s description is consistent with the Examiner’s rejection. Tang
explains that Tang’s effluent gaseous mixture, which includes N, H, and F,
“react[s] readily with low temperature substrates” (i.e., chemically alters the
substrates). Tang at 9:34–37. Tang goes on to disclose that the effluents
“may react with a silicon oxide surface to form (NH4)2SiF6, NH3, and H2O
products.” Id. According to Tang, “[a] thin discontinuous layer of
(NH4)2SiF6 solid by-products is left behind on the substrate surface.” Id. at
9:39–41. That layer of solid by-products is then removed by sublimation
when subjected to heat. Id. at 9:42–43, 55–59. Those disclosures indicate
that, rather than physically removing a silicon oxide target layer and forming
a completely new by-product layer, as argued by the Appellant, Tang’s
effluents “react with” the silicon oxide target layer to yield a chemically
altered layer. Id. at 9:34–41.
Additionally, we observe that it is unclear why the combined prior
art—which involves the exposure of a workpiece falling within the scope of
claim 1 to a chemical environment falling within the scope of claim 1—
would not yield the result recited by claim 1, i.e., a chemically altered
surface region of the target layer and a chemically altered depth within the
target layer. At oral argument,4 the Appellant identified Tang’s use of
“plasma effluents” as a potentially material difference between Tang and

4 A transcript of the hearing will be added to the publicly accessible file
history when available.
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claim 1, which recites a “non-plasma etch chamber.” But, as discussed
below, the Specification expressly defines the term “non-plasma” in a way
that encompasses Tang’s process. See Spec. ¶ 20. The Specification
expressly contemplates a chemical environment created by “a remote plasma
generator . . . arranged to supply the dry, non-plasma etch chamber
with . . . F, N, or H.” Id. ¶ 33.
Thus, although we acknowledge some support in the record for the
Appellant’s position, we find that the record as a whole supports the
Examiner’s finding that a person of ordinary skill would have understood the
process of the combined prior art to yield a “chemically altered surface
region” and a “chemically altered depth within the target layer” as recited by
claim 1.
In the Reply Brief, the Appellant emphasizes the fact that the claim
recites that both a “surface region” of the target layer and a “depth within”
the target layer must be “chemically altered.” E.g., Reply Br. 3. The
Appellant does not identify any requirement for how deep the recited “depth
within” must be, and, under its broadest reasonable interpretation, the claim
language appears to encompass even minimal depths such that the “thin
discontinuous layer,” formed when Tang’s effluent gases react with Tang’s
target layer, falls within the scope of claim 1. A “thin . . . layer” is
reasonably understood as a having both a surface and at least some minimal
(i.e., “thin”) depth, indicating that both the surface of Tang’s target layer and
at least some minimal “depth within” Tang’s target layer are chemically
altered by reaction with Tang’s effluent gases.
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The Appellant also argues that Tang’s process “relies upon plasma to
etch the target layer” and, therefore, falls beyond the scope of the term “non-
plasma etch chamber” recited by claim 1. Appeal Br. 12, 15.
That argument is not persuasive for the reasons explained by the
Examiner in the Answer. See Ans. 11 (explaining that the Appellant’s
Specification defines the term “non-plasma” in a way that encompasses
Tang’s process). Although the Appellant files a Reply Brief, the Appellant
does not address or otherwise attempt to show error in that reasoning.
The Appellant also argues that the Examiner has not shown that
Tang’s target layer includes “silicon and either (1) organic material or
(2) both oxygen and nitrogen,” as required by claim 1. Appeal Br. 17–18.
Specifically, the Appellant argues that Wang teaches only that silicon oxide
“may” include carbon or nitrogen; not that carbon or nitrogen is “necessarily
present.” Id. The Appellant also argues that Wang’s disclosure that carbon
or nitrogen may be present is not “a global definition of the term silicon
oxide, but rather” is a disclosure “as to how that term is to be understood
within” Wang. Id.
That argument is not persuasive of reversible error. As noted above,
both Tang and Wang disclose SiConi™ etch processes. See, e.g., Tang at
Abstract; Wang ¶¶ 3, 17. Tang discloses the use of silicon oxide
workpieces. E.g., Tang Fig. 1 (element 130), 1:35. Wang also discloses the
use of silicon oxide workpieces, e.g., Wang at Abstract, ¶ 6, and Wang
discloses that silicon oxide workpieces in its SiConi™ etch process “may
include minority concentrations of other elemental constituents such as
nitrogen, hydrogen, carbon and the like,” id. ¶ 53.
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We do not understand a finding that nitrogen and/or carbon are
inherent in all silicon oxide workpieces to be necessary to the Examiner’s
rejection. See Reply Br. 9 (raising arguments about inherency). Rather, we
understand the Examiner’s findings to indicate that, because both Tang and
Wang concern SiConi™ etch processes, and Wang discloses that silicon
oxide target layers known to be suitable for such processes may include
carbon and/or nitrogen, it would have been obvious to use a silicon oxide
including carbon and/or nitrogen in Tang’s process because it is simply the
use of a known element (silicon oxide with carbon and/or nitrogen)
according to its established function (target layer in a SiConi™ etch
process). The use of known elements according to their established function
typically does not result in nonobvious subject matter. See KSR Int’l Co. v.
Teleflex Inc., 550 U.S. 398, 416–21 (2007) (“The combination of familiar
elements according to known methods is likely to be obvious when it does
no more than yield predictable results.” / “[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.”). Accordingly, we are not persuaded of
reversible error in the Examiner’s rejection on the basis of the Appellant’s
arguments concerning the presence of nitrogen and/or carbon in Tang’s
silicon oxide layer.
We have carefully considered the Appellant’s arguments, but we are
not persuaded of reversible error in the Examiner’s rejection of claim 1. See
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 . . . .”).
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Claim 17. Claim 17 depends from claim 1 and further recites, inter
alia, that “the target layer comprises SiOxNy.” In other words, whereas
claim 1 requires only the presence of silicon and either organic material or
oxygen/nitrogen in the target layer, claim 17 specifically requires the
presence of the compound SiOxNy.
In the Final Action, the Examiner does not appear to specifically
address claim 17, apparently finding (implicitly) that Wang’s disclosure
discussed above (i.e., that silicon oxide may include “elemental constituents
such as nitrogen, hydrogen, carbon, and the like”) adequately teaches or
suggests the subject matter of claim 17. See generally Final Act.
In the Appeal Brief, the Appellant argues that “claim 17 requires the
target layer to include a silicon oxynitride compound . . . in other words, a
molecular structure of SiOxNy. . . . [T]here is no disclosure of SiOxNy in
Tang or Wang.” Appeal Br. 19–20 (emphases in original).
In the Examiner’s Answer, the entirety of the Examiner’s response is
as follows: “As discussed above, ‘Silicon oxide’ may include minority
concentrations of other elemental constituents such as nitrogen, hydrogen,
carbon, and the like. Both Tang and Wang teach that SiConi.TM. process is
a selective process meaning the etch selective relative [to] silicon is greater
than unity (1).” Ans. 14.
In the Reply Brief, the Appellant argues that “Claim 17 does not
merely recite that some nitrogen is present, but rather, that nitrogen is
present in molecular form in SiOxNy . . . . Wang merely discloses that
nitrogen could possibly be present, but fails to disclose or suggest the use of
a compound of SiOxNy in Tang’s process.” Reply Br. 12.
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“[T]he examiner bears the initial burden, on review of the prior art or
on any other ground, of presenting a prima facie case of unpatentability.” In
re Oetiker, 977 F.2d 1443, 1445 (Fed. Cir. 1992). The Examiner has failed
to carry that burden as to claim 17. Merely identifying a disclosure in the
prior art that silicon oxide may include “other elemental constituents” such
as nitrogen is not adequate to show the presence of the specifically claimed
compound, SiOxNy. That is particularly true here because, in the Appeal
Brief, the Appellant specifically identifies that apparent deficiency in the
Examiner’s analysis, but in the Answer, the Examiner fails to offer any
persuasive explanation as to how the relied-on disclosure of Wang teaches or
suggests the specific compound recited by claim 17. The Examiner made no
finding, for example, that, if nitrogen and silicon oxide are present together,
they will necessarily and inherently react to form an SiOxNy compound. At
the oral hearing, the Appellant argued that the record failed to establish that
the presence of silicon oxide and nitrogen inherently and inevitably results in
an SiOxNy compound. We agree that the present record does not establish
inherency, and the Examiner has not otherwise provided adequate reasoning
to support the Examiner’s rejection.
On this record, a preponderance of the evidence does not support the
Examiner’s rejection of claim 17.
CONCLUSION
In summary:
Claims
Rejected
35
U.S.C. § References Affirmed Reversed
1, 3–15, 17,
19–21 103
Tang, Wang,
Tabuchi 1, 3–15, 19–21 17
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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 IN PART