FLOSFIA INC.

Patent Trials and Appeals Board

Apr 1, 2022

2021003734 (P.T.A.B. Apr. 1, 2022)

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. 15/717,145 09/27/2017 Masaya ODA 2017-1478A 5764 513 7590 04/01/2022 WENDEROTH, LIND & PONACK, L.L.P. 1025 Connecticut Avenue, NW Suite 500 Washington, DC 20036 EXAMINER GONDARENKO, NATALIA A ART UNIT PAPER NUMBER 2891 NOTIFICATION DATE DELIVERY MODE 04/01/2022 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): eoa@wenderoth.com kmiller@wenderoth.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte MASAYA ODA, RIE TOKUDA, HITOSHI KAMBARA, KATSUAKI KAWARA, and TOSHIMI HITORA Appeal 2021-003734 Application 15/717,145 Technology Center 2800 Before TERRY J. OWENS, LINDA M. GAUDETTE, and LILAN REN, Administrative Patent Judges. GAUDETTE, Administrative Patent Judge. DECISION ON APPEAL1 The Appellant2 appeals under 35 U.S.C. § 134(a) from the Examiner’s decision finally rejecting claims 1, 2, 5, 6, 8, 10-12, 14, 17-19, and 21-34.3 We affirm. 1 The following documents are of record: Specification filed September 27, 2017, as amended (“Spec.”); Final Office Action dated May 20, 2020 (“Final Act.”); Appeal Brief filed January 19, 2021 (“Appeal Br.”) and Claims Appendix (Appeal Br. 24-28) filed; and Examiner’s Answer dated March 22, 2021 (“Ans.”). 2 “Appellant” refers to “applicant” as defined in 37 C.F.R. § 1.42. The Appellant identifies the real party in interest as FLOSFIA, INC. Appeal Br. 3. 3 We have jurisdiction under 35 U.S.C. § 6(b). Appeal 2021-003734 Application 15/717,145 2 CLAIMED SUBJECT MATTER Claim 1, reproduced below, is illustrative of the claimed subject matter: 1. A semiconductor device comprising: a semiconductor layer comprising a crystalline oxide semiconductor with a corundum structure comprising α-Ga2O3 or a crystalline oxide semiconductor with a corundum structure comprising a mixed crystal of α-Ga2O3, the mixed crystal of α- Ga2O3 further comprising aluminum and/or indium; and a Schottky electrode that is positioned on the semiconductor layer, the semiconductor layer comprising a surface area that is 3 mm2 or less, and the semiconductor layer comprising a dielectric breakdown field that is 10 MV/cm or more. Appeal Br. 24. REFERENCES Girdhar US 2011/0156682 A1 Jun. 30, 2011 Lutz US 9,070,571 B2 Jun. 30, 2015 Oda ‘005 US 2016/0149005 A1 May 26, 2016 Hilsenbeck US 2016/0155714 A1 Jun. 2, 2016 Tomai US 2016/0211386 A1 July 21, 2016 Aketa US 2016/0254357 A1 Sept. 1, 2016 Oda ‘439 US 9,966,439 B2 May 8, 2018 Sasaki US 2019/0148563 A1 May 16, 2019 Oda ‘202 WO 2015/005202 A1 Jan. 15, 2015 Appeal 2021-003734 Application 15/717,145 3 Shinohara, Heteroepitaxy of Corundum-Structured α-Ga2O3 Thin film on a- AlzO3 Substrates by Ultrasonic Mist Chemical Vapor Deposition, Japanese Journal of Applied Physics, Vol. 47, No. 9, pp. 7311-7313 (2008). Lee, Enhanced thermal stability of alpha gallium oxide films supported by aluminum doping, Japanese Journal of Applied Physics 54, 030301 (2015) HTTP://DX.DOI.ORG/10.7557/JJAP64.030301 Masataka, Development of gallium oxide power devices, Phys. Status Solidi A 211, No. 1, 21-26 (2014) REJECTIONS4 The Examiner maintains the following rejections under 35 U.S.C. § 103: 1. Claims 1, 2, 5, 8, 10, 11, 17, 18, 21, 22, 24, and 30-32 over Tomai in view of Shinohara, Aketa, and Sasaki, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 2-3. 2. Claims 6 and 19 over Tomai in view of Shinohara, Aketa, Sasaki, and Lutz, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 14. 3. Claim 12 over Tomai in view of Shinohara, Aketa, Sasaki, and Girdhar, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 16. 4. Claims 23, 27, and 28 over Tomai in view of Shinohara, Aketa, Sasaki, and Oda, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 17. 4 The Examiner withdraws the rejection of claims 1, 2, 5, 6, 8, 10-12, 14, 17-19, and 21-34 as indefinite under 35 U.S.C. § 112. See Ans. 3. Appeal 2021-003734 Application 15/717,145 4 5. Claims 14, 26, 29, and 34 over Tomai in view of Shinohara and Sasaki, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 19. 6. Claim 25 over Tomai in view of Shinohara, Sasaki, and Oda, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 22. 7. Claim 33 over Tomai in view of Shinohara, Sasaki, and Aketa, as evidenced by Lee, Higashiwaki, and Hilsenbeck. See Final Act. 23. ISSUES The Appellant argues the rejection of independent claim 1, and relies on the same arguments in addressing the rejections of independent claims 17 and 29. See Appeal Br. 11-21. In addressing the rejections of various dependent claims, the Appellant merely asserts that the secondary references fail to cure the deficiencies in the references cited in the rejections of independent claims 1, 17, and 29. See generally Appeal Br. 19-22. The Appellant’s arguments raise the following issues for our consideration: Has the Appellant identified reversible error in the Examiner’s findings that the applied prior art discloses or suggests a semiconductor layer comprising (1) “a crystalline oxide semiconductor with a corundum structure comprising α-Ga2O3, or a crystalline oxide semiconductor with a corundum structure comprising a mixed crystal of α-Ga2O3, the mixed crystal of α-Ga2O3 further comprising aluminum and/or indium” (2) “a surface area that is 3 mm2 or less,” and (3) “a dielectric breakdown field that is 10 MV/cm or more” (claim 1)? See Ans. 3; see generally Appeal Br. 11-19. For the reasons explained in the Answer, we are not persuaded that the Examiner reversibly erred. Therefore, we sustain all grounds of rejection Appeal 2021-003734 Application 15/717,145 5 based on the Examiner’s fact finding and reasoning in the Final Office Action and the Answer. OPINION The Examiner found that Tomai discloses a Schottky electrode positioned on a crystalline oxide semiconductor layer comprising Ga2O3. Final Act. 3. As found by the Examiner (id.), Tomai discloses that “[w]hen the gallium oxide is polycrystalline, the gallium oxide may have an α, β, γ, δ, or ε crystal form, or may be a mixture thereof” (Tomai ¶ 70). A crystalline oxide semiconductor with a corundum structure comprising α- Ga2O3 or a crystalline oxide semiconductor with a corundum structure comprising a mixed crystal of α-Ga2O3, the mixed crystal of α-Ga2O3 further comprising aluminum and/or indium The Appellant argues that although Tomai lists more than one crystal form, Tomai indicates a preference for β-Ga2O3. If, by this statement, the Appellant is contending that Tomai teaches away from using α-Ga2O3, we do not find the argument persuasive because Tomai does not clearly discourage the use of α-Ga2O3. See Santarus, Inc. v. Par Pharm., Inc., 694 F.3d 1344, 1356 (Fed. Cir. 2012); Syntex (U.S.A.) LLC v. Apotex, Inc., 407 F.3d 1371, 1379-80 (Fed. Cir. 2005); In re Fulton, 391 F.3d 1195, 1201 (Fed. Cir. 2004). The Appellant also argues that Tomai fails to enable α-Ga2O3. Appeal Br. 13. “[B]oth claimed and unclaimed materials disclosed in a patent are presumptively enabling.” In re Antor Media Corp., 689 F.3d 1282, 1287 (Fed. Cir. 2012) (citing Amgen Inc. v. Hoechst Marion Roussel, Inc., 314 F.3d 1313, 1354 (Fed. Cir. 2003)). That presumption places the burden on the Appellant to rebut the presumption of operability by a preponderance of the evidence. See id. at 1288 (citations omitted). “[T]o be enabling, the specification of a patent must teach those skilled in the art how to make and use the full scope of Appeal 2021-003734 Application 15/717,145 6 the claimed invention without ‘undue experimentation.’” In re Wright, 999 F.2d 1557, 1561 (Fed. Cir. 1993). The following factors are considered in determining whether undue experimentation would have been required to make and use an invention: “(1) the quantity of experimentation necessary, (2) the amount of direction or guidance presented, (3) the presence or absence of working examples, (4) the nature of the invention, (5) the state of the prior art, (6) the relative skill of those in the art, (7) the predictability or unpredictability of the art, and (8) the breadth of the claims.” In re Wands, 858 F.2d 731, 737 (Fed. Cir. 1988). The Appellant argues that Tomai does not enable α-Ga2O3 because “Examples 1-24 shown in Tables 1-3 and discussed in paragraphs [0129]- [0178] of Tomai, and the X-ray diffraction charts (XRD) of the oxide semiconductor film show polycrystalline, amorphous, or micro-crystalline structures,” but “Tomai is silent about a specific crystal structure of a corundum structure.” Appeal Br. 13. The Appellant’s argument is not sufficient to overcome the presumption of enablement because it addresses only one of the seven factors relevant to enablement: absence of working examples. Cf. Hybritech Inc. v. Monoclonal Antibodies, Inc., 802 F.2d 1367, 1384 (Fed. Cir. 1986) (“[A] patent need not teach, and preferably omits, what is well known in the art.”). The Examiner found that the ordinary artisan would have modified the semiconductor device of Tamai by forming a corundum- structured α-Ga2O3 with wider band gap using mist chemical vapor deposition (CVD) as taught by Shinohara (and evidenced by Lee) to have a crystalline oxide semiconductor with a corundum structure comprising α-Ga2O3 in order to provide improved power semiconductor device comprising wide- bandgap corundum-structured oxide crystal having high quality, Appeal 2021-003734 Application 15/717,145 7 excellent crystallographic properties and smooth surface morphologies. Final Act. 4 (citing Shinohara Abstract, p. 7311, col. 1, p. 7313, col. 1; Lee, Abstract, p. 030301-1, col. 1). The Appellant argues that the ordinary artisan would not have been motivated to use, or had a reasonable expectation of success in using, a corundum-structured α-Ga2O3 layer. Appeal Br. 14-15. The Appellant argues that Shinohara describes “success in forming heteroepitaxy of corundum- structured α-Ga2O3 thin films on α-Al2O3 substrates by mist chemical vapor deposition (CVD) at low temperatures of 430-470°C,” but “indicates that even with slightly changed condition(s) of forming films, α-Ga2O3 films were not obtained.” Id. at 14. The Appellant argues that Lee discloses enhanced thermal stability of α-Ga2O3 films by aluminum doping, but, like Shinohara, does not disclose using an α-Ga2O3 film as a layer in a semiconductor device. Id. The Appellant’s arguments are not persuasive of reversible error because they focus on individual reference teachings, and fail to consider what the ordinary artisan would have understood from the combined references’ teachings. Tomai discloses that, “from the viewpoint of operational stability,” the gallium oxide preferably includes β-Ga2O3 as the main component. Tomai ¶ 70. But Shinohara specifies that the β-phase is more stable than the other phases only at temperatures higher than 450 °C. Shinohara p. 7311, col. 1. Shinohara discloses that α-Ga2O3 can be successfully grown on α-Al2O3 (sapphire) substrates using ultrasonic mist chemical vapor deposition, “which is a simple, safe, cost-effective, and environmentally friendly growth method.” Id. at 7311, cols. 1-2. Shinohara discloses that “α-Ga2O3 epilayers Appeal 2021-003734 Application 15/717,145 8 have exhibited excellent crystallographic properties and smooth surface morphologies.” Id. at 7311, col. 1. Lee likewise discloses that “high-quality single-crystalline α-Ga2O3 films can be synthesized on sapphire (α-Al2O3) substrates by the mist chemical vapor deposition (CVD) method.” Lee p. 030301-1, col. 1. Lee evidences that at the time of the invention, it was known that a small amount of “Al doping allows the higher temperature growth of α- Ga2O3, followed by a higher thermal stability.” Lee p. 030301-2, col. 1. Tomai discloses that an “oxide semiconductor that includes Ga as the main component . . . may be formed by . . . a mist CVD method” (Tomai ¶ 112) and the substrate may be sapphire (id. at Table 3 (Example 18)). Despite Tomai’s stated preference for β-Ga2O3, the above disclosures support the Examiner’s finding that the ordinary artisan would have been motivated to use an α-Ga2O3 layer in Tomai’s semiconductor device to achieve the benefit of an “improved power semiconductor device with improved performance characteristics by utilizing a wider-bandgap corundum-structured oxide crystal having high quality, excellent crystallographic properties and smooth surface morphologies” (Ans. 5). The ordinary artisan would have had a reasonable expectation of success in making this modification to Tomai’s device based on the secondary references’ teachings of methods for improving α-phase stability. A surface area that is 3 mm2 or less The Examiner found that the ordinary artisan would have modified the Tomai/Shinohara semiconductor device by using the specific range of sizes of wide bandgap semiconductor element as taught by Aketa[, i.e., a square chip shape having a size between 0.5 mm and 20 mm so that a surface area is between 0.25 (sic, 2.5) mm2 and 400 mm2,] to Appeal 2021-003734 Application 15/717,145 9 have a semiconductor device comprising the semiconductor layer of Ga2O3 comprising a surface area that is 3 mm2 or less in order to provide a Schottky barrier diode comprising a semiconductor material that has high mobility and wide energy gap, and to be used for a power device having small size and that allows an improvement in breakdown voltage. Final Act. 4. The Appellant argues that Aketa paragraph 86, relied upon by the Examiner for a teaching of the diode dimensions, relates to the dimensions of a 4H-SiC Schottky barrier diode, and Aketa does not disclose or suggest what dimensions should be used for a Ga2O3 Schottky barrier diode. Appeal Br. 16. The Appellant’s argument is not persuasive because it does not address the Examiner’s finding as to the understanding of the ordinary artisan. Specifically, the Examiner finds that the ordinary artisan would have understood from Tomai that, because an “oxide semiconductor that includes Ga as the main component has a wide band gap as compared with crystalline Si as well as SiC” (Tomai ¶ 111; see also id. ¶ 5 (“Ga2O3 has attracted attention as a material having a band gap wider than that of SiC.”)), a Ga2O3 Schottky barrier diode’s dimensions would be smaller than those specified for the 4H-SiC Schottky barrier diode (see id. at ¶ 4 (“[S]ince the band gap of Si is as narrow as 1.1 eV, it is necessary to increase the size of the element in order to improve the breakdown characteristics.”)). Ans. 7. In other words, the evidence supports a finding that Tomai and Aketa suggest a Ga2O3 Schottky barrier diode surface area that overlaps to an even greater extent with the claimed “3 mm2 or less” than the explicitly-described 4H-SiC Schottky barrier diode’s surface area. A dielectric breakdown field that is 10 MV/cm or more Relying on Sasaki’s and Shinohara’s teachings, and supporting evidence in Higashiwaki, the Examiner found that the ordinary artisan would Appeal 2021-003734 Application 15/717,145 10 have recognized that “by optimizing the thickness of the wider band gap (α- Ga2O3) semiconductor layer and the donor concentration in the wider band gap semiconductor layer, [a] semiconductor Schottky device would have a high withstand voltage and a high breakdown field.” Final Act. 5. In the Answer, the Examiner further finds that the Specification evidences that “a crystalline α-Ga2O3 oxide semiconductor film of Tomai/Shinohara formed by a mist CVD method would inherently have a dielectric breakdown field of 10 MV/cm or more as one of the properties of the α-Ga2O3 oxide semiconductor. Ans. 9. The Appellant’s arguments do not address and, therefore, fail to identify error in the Examiner’s inherency finding, which is supported by the Specification disclosure relied on by the Examiner. Specifically, the Examiner quotes Specification page 37, lines 1-3 and page 40, lines 11-13, which state, respectively, “[a] crystalline oxide semiconductor film may be preferably formed by a mist CVD” and “[i]f conditions that are preferable are applied to the processes to form the semiconductor layer, a dielectric breakdown field of the semiconductor layer is expected to be 10 MV/cm or more.” Ans. 9. See Millennium Pharm., Inc. v. Sandoz Inc., 862 F.3d 1356, 1364-65 (Fed. Cir. 2017) (“A result is obvious when it is . . . a ‘property that is necessarily present’ when applying a process disclosed in the prior art.” (quoting Par Pharm., Inc. v. TWI Pharm., Inc., 773 F.3d 1186, 1195 (Fed. Cir. 2014))); In re Kubin, 561 F.3d 1351, 1357 (Fed. Cir. 2009) (“Even if no prior art of record explicitly discusses the . . . [limitation], [Appellants’] application itself instructs that [the limitation] is not an additional requirement imposed by the claims on the [claimed invention], but rather a property necessarily present in [the claimed invention].”); Ex parte Obiaya, Appeal 2021-003734 Application 15/717,145 11 227 USPQ 58, 60 (BPAI 1985) (“The fact that appellant has recognized another advantage which would flow naturally from following the suggestion of the prior art cannot be the basis for patentability when the difference would otherwise have been obvious.”). DECISION SUMMARY Claims Rejected 35 U.S.C. § Reference(s)/Basis Affirmed Reversed 1, 2, 5, 8, 10, 11, 17, 18, 21, 22, 24, 30-32 103 Tomai, Shinohara, Aketa, Sasaki, Lee, Higashiwaki, Hilsenbeck 1, 2, 5, 8, 10, 11, 17, 18, 21, 22, 24, 30-32 6, 19 103 Tomai, Shinohara, Aketa, Sasaki, Lutz, Lee, Higashiwaki, Hilsenbeck 6, 19 12 103 Tomai, Shinohara, Aketa, Sasaki, Girdhar, Lee, Higashiwaki, Hilsenbeck 12 23, 27, 28 103 Tomai, Shinohara, Aketa, Sasaki, Oda, Lee, Higashiwaki, Hilsenbeck 23, 27, 28 14, 26, 29, 34 103 Tomai, Shinohara, Sasaki, Lee, Higashiwaki, Hilsenbeck 14, 26, 29, 34 25 103 Tomai, Shinohara, Sasaki, Oda, Lee, Higashiwaki, Hilsenbeck 25 Appeal 2021-003734 Application 15/717,145 12 Claims Rejected 35 U.S.C. § Reference(s)/Basis Affirmed Reversed 33 103 Tomai, Shinohara, Sasaki, Aketa, Lee, Higashiwaki, Hilsenbeck 33 Overall Outcome: 1, 2, 5, 6, 8, 10-12, 14, 17-19, 21-34 TIME PERIOD FOR RESPONSE 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