in Re: X-Fab Semiconductor Foundries Gmbh v. Neenah, Inc., 82 F.4th 1371, 1381 Fed. Cir. 2023 . X-Fab asserts the Board was put…

NOTE: This disposition is nonprecedential.
United States Court of Appeals
for the Federal Circuit
______________________
IN RE: X-FAB SEMICONDUCTOR FOUNDRIES
GMBH,
Appellant
______________________
2024-1337
______________________
Appeal from the United States Patent and Trademark
Office, Patent Trial and Appeal Board in No. 15/648,728.
______________________
Decided: October 22, 2025
______________________
ELANA ARAJ , Greenberg Traurig LLP, New York, NY,
argued for appellant. Also represented by ROBERT A. K ING ,
TRENTON A. WARD , Atlanta, GA.
M ONICA BARNES LATEEF, Office of the Solicitor, United
States Patent and Trademark Office, Alexandria, VA, ar-
gued for appellee John A. Squires. Also represented by
ROBERT M CBRIDE.
______________________
Before M OORE, Chief Judge, D YK and CUNNINGHAM,
Circuit Judges.
M OORE, Chief Judge.
Case: 24-1337 Document: 57 Page: 1 Filed: 10/22/2025

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IN RE: X - FAB SEMICONDUCTOR FOUNDRIES GMBH 2
X-Fab Semiconductor Foundries GmbH (X-Fab) ap-
peals a decision of the Patent Trial and Appeal Board
(Board) affirming an examiner’s rejection of certain claims
of U.S. Patent Application No. 15/648,728 as obvious. Be-
cause X-Fab forfeited the arguments it raises on appeal, we
affirm the Board’s decision.
BACKGROUND
The ’728 application discloses carrier substrates used
to manufacture semiconductor components, which are
transferred from the carrier substrate to integrated cir-
cuits. J.A. 187. The carrier substrate has (1) an active re-
gion and (2) trench isolation regions including dielectric
material formed by local oxidation of the carrier substrate’s
semiconductor material. J.A. 192. Claim 1 is representa-
tive:
1. A method for producing semiconductor structures on
a carrier substrate, suitable to be transferred from the
carrier substrate, the method comprising:
providing a carrier substrate comprising a semiconduc-
tor material with a first crystal orientation;
producing an active region having an exposed semicon-
ductor surface and is almost completely delimited by
trench isolation regions comprising an isolating dielec-
tric material formed by local oxidation of the semicon-
ductor material of the carrier substrate;
forming a semiconductor structure by depositing at
least one semiconductor layer on the active region;
removing at least a portion of the dielectric material;
performing an etching to remove semiconductor mate-
rial beneath the semiconductor structure to enable the
semiconductor structure to be transferred from the car-
rier substrate.
Case: 24-1337 Document: 57 Page: 2 Filed: 10/22/2025

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IN RE: X - FAB SEMICONDUCTOR FOUNDRIES GMBH 3
The Board affirmed the examiner’s rejection of claims
1, 4–7, 12, 13, and 23–29 based on Nakahata1 and Whis-
ton2 and entered a new ground of rejection of claims 14–17
based on the same combination. J.A. 2–13. The Board also
affirmed the examiner’s rejection of claims 8–11 based on
various combinations of Nakahata, Whiston, and addi-
tional prior art references. J.A. 10–12. X-Fab appeals. We
have jurisdiction under 28 U.S.C. § 1295(a)(4)(A).
D ISCUSSION
We review the Board’s legal determinations de novo
and its underlying factual findings for substantial evi-
dence. In re Constr. Equip. Co., 665 F.3d 1254, 1255 (Fed.
Cir. 2011). What a reference teaches and whether a skilled
artisan would be motivated to combine references are ques-
tions of fact we review for substantial evidence. Id.
X-Fab argues the Board erred in determining claim 1
would have been obvious over the Nakahata-Whiston com-
bination. X-Fab Br. 19–22. Specifically, X-Fab argues the
Board’s finding that Whiston’s LOCal Oxidation of Silicon
(LOCOS) regions are trench isolation regions that would
extend into Nakahata’s substrate was not supported by
substantial evidence because the portions of Nakahata the
Board cited did not disclose a silicon starting substrate.
See id. at 20–22. This argument is forfeited because X-Fab
failed to raise it before the Board, and “we do not consider
such forfeited arguments on appeal.” Schwendimann v.
Neenah, Inc., 82 F.4th 1371, 1381 (Fed. Cir. 2023).
X-Fab asserts the Board was put on notice of this argu-
ment below when X-Fab argued the Nakahata-Whiston
combination failed to disclose the claimed trench isolation
regions. X-Fab Reply Br. 2–6 (citing J.A. 708–14; J.A. 780–
82). We do not agree. Nowhere did X-Fab argue below that
1 U.S. Patent Appl. Pub. No. 2010/0207138.
2 U.S. Patent No. 6,835,627.
Case: 24-1337 Document: 57 Page: 3 Filed: 10/22/2025

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IN RE: X - FAB SEMICONDUCTOR FOUNDRIES GMBH 4
Nakahata failed to disclose a silicon starting substrate. X-
Fab argued that neither Nakahata nor Whiston disclose
trench isolation regions formed by local oxidation of semi-
conductor material. J.A. 702–03, 708–14. X-Fab did not
raise the argument that Nakahata does not disclose the sil-
icon starting material. We therefore see no reversible error
in the Board’s failure to make a specific fact finding about
whether Nakahata disclosed the silicon starting material.
See Schwendimann, 82 F.4th at 1380 (explaining that for-
feiture “deprives the court of the benefit of the Board’s in-
formed judgment” (cleaned up)). If we were to reach X-
Fab’s argument that “Nakahata does not disclose or sug-
gest that its starting substrate is inherently silicon,” X-
Fab. Br. 21, we would reject this as well. While we do not
make such fact findings in the first instance, it seems quite
clear that Nakahata expressly discloses a silicon starting
substrate. J.A. 956 ¶ 176 (“300 μm thick Si substrate was
used as the starting substrate”); J.A. 957 ¶ 181 (same);
J.A. 963 ¶ 202 (“10.08 cm diameter silicon sub-
strate . . . was used as the starting substrate”).
X-Fab also argues the Board’s finding that a skilled ar-
tisan would have been motivated to combine Nakahata and
Whiston was not supported by substantial evidence. X-Fab
Br. 22–25. This argument is forfeited as well. Before the
Board, X-Fab argued only in the most superficial manner
that the Nakahata-Whiston combination was based on
hindsight. J.A. 702–03. Nothing in X-Fab’s arguments be-
low put the Board on notice that X-Fab was challenging the
sufficiency of the Board’s motivation to combine findings,
and it cannot raise the argument for the first time here.
See Schwendimann, 82 F.4th at 1380.
CONCLUSION
We have considered X-Fab’s remaining arguments and
find them unpersuasive. Because X-Fab forfeited the ar-
guments it makes on appeal, we affirm the Board’s deci-
sion.
Case: 24-1337 Document: 57 Page: 4 Filed: 10/22/2025

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IN RE: X - FAB SEMICONDUCTOR FOUNDRIES GMBH 5
AFFIRMED
COSTS
Costs to appellee.
Case: 24-1337 Document: 57 Page: 5 Filed: 10/22/2025

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