Ex Parte Kuchiyama et alDownload PDFPatent Trial and Appeal BoardApr 5, 201813816216 (P.T.A.B. Apr. 5, 2018) Copy Citation UNITED STA TES p A TENT AND TRADEMARK OFFICE APPLICATION NO. FILING DATE 13/816,216 02/08/2013 145327 7590 04/09/2018 Alleman Hall Creasman & Tuttle LLP 900 SW 5th A venue Suite 2300 Portland, OR 97204 FIRST NAMED INVENTOR Takashi Kuchiyama 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 ATTORNEY DOCKET NO. CONFIRMATION NO. IZN12304PCTUS 7119 EXAMINER MEKHLIN, ELIS ART UNIT PAPER NUMBER 1721 NOTIFICATION DATE DELIVERY MODE 04/09/2018 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): patentdocket@allemanhall.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte T AKASHI KUCHIY AMA, 1 Kenji Yamamoto, and Masashi Y oshimi Appeal2016-004570 Application 13/816,216 Technology Center 1700 Before ROMULO H. DELMENDO, MARK NAGUMO, and WESLEY B. DERRICK, Administrative Patent Judges. NAGUMO, Administrative Patent Judge. DECISION ON APPEAL Takashi Kuchiyama, Kenji Yamamoto, and Masashi Y oshimi ("Kuchiyama") timely appeal under 35 U.S.C. § 134(a) from the Final Rejection2 of all pending claims 1--4 and 8. We have jurisdiction. 35 U.S.C. § 6(b)(l). We affirm. 1 The real party in interest is identified as Kaneka Corporation. (Appeal Brief, filed 9 October 2015 ("Br."), 3.) 2 Office Action mailed 9 March 2015 ("Final Rejection"; cited as "FR"), as modified by the Advisory Action (27 May 2015, "Adv."), entering amendments filed after the Final Rejection under 3 7 C.F .R. § 1.116 on 11 May 2015 ("AAF"). Appeal 2016-004570 Application 13/816,216 A. Introduction 3 OPINION The subject matter on appeal relates to heterojunction solar cells, which, according to the '216 Specification, are solar cells that have a conductive amorphous silicon-based thin film having a band gap different from the band gap of the [conductive] crystalline silicon substrate to form a diffusion potential. (Spec. 1 [0002].) A cross-sectional diagram of an inventive solar cell is shown in the Figure, reproduced below. -~·"·· ·.·.·.·.·.·.···.·············--·······--· ti -~ {The Figure shows a cross section of a solar cell} 3 Application 13/816,216, Crystalline silicon-based solar cell, 8 February 2013 as the national stage under 35 U.S.C. § 371 of PCT/JP2011/067783, filed 3 August 2011, claiming the benefit of an application filed in Japan on 9 August 2010. We refer to the "'216 Specification," which we cite as "Spec." 2 Appeal 2016-004570 Application 13/816,216 The solar cell comprises conductive crystalline silicon substrate 14, with, on the external, light-facing side, silicon-based thin film 41 of a first conductivity type (typically amorphous p-type silicon (id. at 5---6 [0019])), transparent electrode 61, and collecting electrode 71. (Id. at 5 [0018].) On the opposite (base) side of substrate 1 are silicon-based thin film 42 of the opposite conductivity type, transparent electrode 62, and collecting electrode 72. (Id.) The Specification teaches that it is known to provide intrinsic 5 amorphous silicon thin films 21, 22, between substrate 1 and conductive amorphous silicon thin films 41, 42, in order to terminate dangling bonds on conductive substrate 1 with hydrogen, thereby reducing the generation of new defect levels as well have preventing impurity diffusion through the overlying layers during their formation. (Id. at [0003].) The Specification teaches further that the transparent electrodes are critical to the extraction of photoinduced carriers, and improvements are said to require improving the electrical junction between the silicon-based thin-film and the transparent electrode layer. (Id. at 2- 3 [0007].) Merely decreasing the resistance of the transparent electrode is said to be insufficient. (Id. at 2 [0005].) More specifically, the Specification discloses an improvement in which the "first transparent electrode"-i.e., electrode 61, facing the light 4 Throughout this Opinion, for clarity, labels to elements are presented in bold font, regardless of their presentation in the original document. 5 We understand the term "intrinsic," in this context, to refer to a "pure' material that contains, at most, a slight amount of n- or p-type impurity, such that "the silicon-based thin-film can function as an intrinsic layer (i-type layer)." (Spec. 8 [0028].) 3 Appeal 2016-004570 Application 13/816,216 source---comprises a two-layer structure in which both layers are amorphous transparent conductors, wherein substrate-side layer 61A has a higher carrier density than surface-side layer 61B. (Id. at 3 [0009]-[0010].) The thickness of first transparent electrode layer 61A is 50 to 120 nm, to optimize transparency as well as to provide adequate conductivity to transport carriers to the collecting electrode 71. (Id. at 12 [0040].) Too high a conductivity in surface-side transparent electroconductive layer 61B is said to reduce the transparency and thereby lower the light capture efficiency of the solar cell. (Id. at 14 [0046].) The higher carrier concentration at substrate side transparent electroconductive layer 61A, however, is said to provide a good electrical junction with the conductive silicon-based thin film 41. (Id.) The Specification reveals further that when the thickness of conductive single-crystal silicon substrate 1 is 250 nm or less, warpage may occur upon formation of the transparent electrodes 61, 62, of differing thicknesses on the light-incident side (which is optimized for transmitting light into the cell) and the back surface side (which is optimized for electricity extraction efficiency). (Id. at 18 [0056]-[0057].) A film of crystalline indium oxide doped with tin oxide ("ITO"), for example, is said to generally have residual compressive stress. (Id. at 19 [0059].) An amorphous ITO film, however, is said to have less or no compressive stress (id.), and is therefore preferred as both the first (light-incident side) and second (back-side) transparent electroconductive layer. (Id. at [0060].) The Specification teaches that such layers may be prepared by decreasing the power density during deposition or by increasing the deposition pressure. (Id. at 21 [0066].) 4 Appeal 2016-004570 Application 13/816,216 Sole independent claim 1 is representative and reads: A crystalline silicon-based solar cell comprising a silicon based thin-film of a first conductivity type [ 41] and a first transparent electrode layer [61], in this order, on one surface of a conductive single-crystal silicon substrate [1] of the first conductivity type or an opposite conductivity type; and a silicon-based thin-film of the opposite conductivity type [ 42] and a second transparent electrode layer [62], in this order, on another surface of the conductive single-crystal silicon substrate [1 ], wherein the first transparent electrode layer [ 61] and the second transparent electrode layer [ 62] are each formed of a transparent conductive metal oxide, the first transparent electrode layer [ 61] satisfies requirements (i) to (iii): (i) at least two layers, including a substrate-side electroconductive layer [ 61A] and a surface-side electroconductive layer [61B], are provided in the first transparent electrode layer [61 ], and the substrate-side electroconductive layer [ 61A] and the surface-side electroconductive layer [61B] are amorphous layers; (ii) a total thickness of the first transparent electrode layer [ 61] is 50 to 120 nm; and (iii) a carrier density of the substrate-side electroconductive layer [61A] is higher than a carrier density of the surface-side electroconductive layer [61B], and the carrier density of the surface-side electro conductive layer [61B] is 1 to 4 x 1020 cm-3, and a thickness of the conductive single-crystal silicon substrate [1] is 250 µm or less. (Claims App., Br. 21; some indentation, paragraphing, emphasis, and bracket labels to the Figure added.) 5 Appeal 2016-004570 Application 13/816,216 It may be noted that claim 1 requires the first and second transparent electrode layers 61, 62, to be transparent conductive metal oxides, but only first transparent electrode layer 61 is required to have the recited dual- amorphous layer structure. The Examiner maintains the following grounds of rejection6' 7, 8 : A. Claims 1--4 and 8 stand rejected under 35 U.S.C. § 103(a) in view of the combined teachings ofNakashima, 9 Wada, 10 Nishioka, 11 Kariya, 12 and Sun. 13 B. Claims 1--4 and 8 stand rejected under 35 U.S.C. § 103(a) in view of the combined teachings of Nakashima, Nakano, 14 Nishioka, Kariya, and Sun. 6 Examiner's Answer mailed 28 January 2016 ("Ans."). 7 Because this application was filed before the 16 March 2013, effective date of the America Invents Act, we refer to the pre-AIA version of the statute. 8 Claim 7 was canceled and incorporated into claim 1 as the final limitation (AAF 2-3), rendering the separate rejections of claim 7 moot, but requiring that the additional reference Sun be applied in the rejections of claim 1. 9 Takeshi Nakashima and Eiji Maruyama, Photovoltaic device, U.S. Patent Application Publication 2005/0150543 Al (2005). 1° Katsuhito Wada, Photovoltaic element and its manufacturing method, JP 2002-208715 Al (2002) (JPO translation). 11 Yukiya Nishioka et al., Method for forming a transparent conductive ITO film, U.S. Patent No. 5,538,905 (1996). 12 Toshimitsu Kariya et al., Photovoltaic element, U.S. Patent Application Publication 2002/0002992 Al (2002). 13 Hai-Lin Sun et al., Solar cell, U.S. Patent Application Publication 2009/0250113 Al (2009). 14 Kengo Nakano et al., Photoelectric conversion device, JP1205474 A (1989) (USPTO translation). 6 Appeal 2016-004570 Application 13/816,216 B. Discussion The Board's findings of fact throughout this Opinion are supported by a preponderance of the evidence of record. Initially, we find that Kuchiyama bases all arguments for patentability on limitations recited in claim 1. We therefore focus on that claim, with which all remaining claims stand or fall. 37 C.F.R. § 41.37(c)(l)(iv) (2014). The Examiner finds, and Kuchiyama does not dispute, that Nakashima describes a crystalline silicon-based solar cell comprising layers corresponding to those recited in claim 1, but for (first) the two-layer structure required of first transparent electrode layer 61. (Adv., para. bridging 3--4 and first full para. at 4.) The Examiner finds that Wada discloses two-layer ITO transparent electrodes. (Id. at 4, 2d full para.) The Examiner finds further that Wada discloses that the substrate-side ITO layer 106 has a lower oxygen density than the surface-side ITO layer 107. The Examiner determines that the lower oxygen density results in a higher conductivity at the interface with the doped silicon layer, allowing for decreased contact resistance. (Id.) Moreover, the Examiner finds that the higher oxygen density at the surface-side ITO layer "maintains the light transmittance of the film." (Id.) The Examiner finds that these references are silent as to the amorphous state of the first transparent electrode (id. at 6, last para.), but finds (id. at 7, 1st para.), that Kariya discloses that ("[t] he transparent conductive layers employed in the present invention are comprised of indium tin oxide (ITO) and may be in a polycrystalline, microcrystalline, or amorphous state" (Kariya 5 [0058], emphasis added). The Examiner reasons that a person having ordinary skill in the art would 7 Appeal 2016-004570 Application 13/816,216 have had a reasonable expectation of successfully combining these teachings to obtain a useful solar cell, and that the teachings of Wada and Nishioka 15 provide sufficient basis to conclude that the carrier concentration was recognized as a result effective variable, such that routine optimization would have resulted in arriving at the recited carrier concentrations. (Adv., para. bridging 5---6.) Finally, the Examiner finds that Sun teaches that conductive single crystal silicon substrates are useful in solar cell applications at a thickness of 200 to 300 µm (id. para. bridging 7-8, citing Sun [0022]). The Examiner concludes that a solar cell having required thickness of the silicon crystal substrate would have been obvious. (Id. at 8, 1st full para.) Kuchiyama urges that the teachings of Kari ya must be considered in context, and that Kariya teaches a dual-layer ITO transparent electrode with a lower tin content on the substrate side than the surface-side. "Thus," Kuchiyama concludes, "it is inherent in Kariya's disclosure that, in Kariya's solar cell, the carrier density of the substrate-side layer is less than the surface-side layer, since the higher the tin content in ITO, the higher the carrier density." (Br. 13, 2d para.) In response to the Examiner's reasoning that Kariya's disclosure of a multi-layer transparent electrode is independent of the tin concentration variation of the layers, Kuchiyama argues that "amorphousness and carrier density gradient (tin concentration relationship) are both related to the features of the multi-layer transparent electrode layer, 15 The Examiner cites Nishioka, column 2, lines 1-3 ("[t]he carrier density of the thus formed ITO film is reduced as the oxygen partial pressure of the ITO film is increased, or the oxygen deficiency of the ITO film is lowered.") as further support. (Id. at 5, 1st full para.) 8 Appeal 2016-004570 Application 13/816,216 and thus these features are not independent." The opposite carrier density gradients of Wada and Kariya are incompatible, Kuchiyama urges, and the person of ordinary skill in the art would therefore not have been motivated to combine the teachings of the references. (Id. at 14.) We do not find these arguments persuasive of harmful error. As the Examiner finds, Kariya states unequivocally that the transparent conductive layers may be polycrystalline, microcrystalline, or amorphous. While there is no dispute that Kariya prefers the crystalline state, Kuchiyama has not directed our attention to any teaching in the record indicating that the amorphous state of the ITO transparent electrode would have been considered inoperable. Nor, perhaps equivalently, has Kuchiyama demonstrated that the functions of the preferred crystalline ITO layer are so tightly related to the presence of the tin gradient in that layer that a person having ordinary skill in the art would have disregarded Kariya's clear statement that any of the three states would be suitable, and concluded that only the crystalline layer would be suitable. We are thus not persuaded that the Examiner erred harmfully in concluding that the subject matter of claim 1 would have been prima facie obvious in view of the combined teaching of the references cited in Rejection A. The reasoning and arguments regarding the teachings of Nakano (Adv. 10-13; Br. 16-20) are essentially parallel to those regarding the teachings of Wada, and we are accordingly not persuaded of harmful error in the prima facie case of obviousness in Rejection B. 9 Appeal 2016-004570 Application 13/816,216 Kuchiyama does not raise any other arguments for patentability in the principal Brief on Appeal. The citation in the Reply 16 of new evidence, namely, the translation of the Japanese priority document underlying Kari ya, is belated under the rules governing appeals 17 and we decline to consider it in the absence of a showing of good cause why that evidence was not presented earlier, i.e., in the amendment-after-Final-Rejection filed 11May2015, under 37 C.F.R. § 1.116. In any event, it is not unreasonable to interpret the allegedly critical passage in the record copy of Kariya, paragraph [0058], namely, "it is necessary to optimize the forming temperature for the concerned layers in order to obtain even a little higher conversion efficiency," as elaborating why the crystalline state of the transparent electrode is preferred, as Kuchiyama urges in the Reply. But, as we explained supra, such a preference does not amount to a teaching away from less preferred, but still operable, embodiments. See, e.g., In re Mouttet, 686 F.3d 1322, 1334 (Fed. Cir. 2012) ('just because better alternatives exist in the prior art does not mean that an inferior combination is inapt for obviousness purposes.") Similarly, the argument regarding unexpected results (Reply 5-7) is belated and there is no plausible showing of good cause why that argument was not presented in the principal Brief on appeal. Our principal role is review. Such an inquiry would involve a fact-intensive analysis of the evidence of record, which we decline to undertake de novo, without the 16 Reply Brief filed 28 March 2016 ("Reply"). 17 37 C.F.R. § 41.41(b )(2) (2015) ("A reply brief shall not include ... any new or non-admitted affidavit or other Evidence."); see also 37 C.F.R. § 1.116(e). 10 Appeal 2016-004570 Application 13/816,216 evaluation of that evidence in the first instance by the Examiner, who, by dint of experience in this and related fields, is better positioned to make such findings. We therefore are not persuaded of harmful error in the Examiner's legal conclusion of obviousness, which we affirm. C. Order It is ORDERED that the rejection of claims 1--4, 7, and 8 is affirmed. 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 11 Copy with citationCopy as parenthetical citation