Ex Parte COUSINSDownload PDFPatent Trials and Appeals BoardMay 9, 201914504771 - (D) (P.T.A.B. May. 9, 2019) Copy Citation UNITED STA TES p A TENT AND TRADEMARK OFFICE APPLICATION NO. FILING DATE FIRST NAMED INVENTOR 14/504,771 10/02/2014 Peter John COUSINS 74254 7590 05/09/2019 Okamoto & Benedicto LLP P.O. Box 641330 San Jose, CA 95164-1330 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. 10031.004211 3342 EXAMINER PILLAY, DEVINA ART UNIT PAPER NUMBER 1726 MAIL DATE DELIVERY MODE 05/09/2019 PAPER 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. PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte PETER JOHN COUSINS Appeal 2018-005 662 Application 14/504,771 Technology Center 1700 Before KAREN M. HASTINGS, JEFFREY R. SNAY, and DEBRA L. DENNETT, Administrative Patent Judges. DENNETT, Administrative Patent Judge. DECISION ON APPEAL 1 1 In our Decision, we refer to Application 14/504,771 filed October 2, 2012 as the "'771 Specification" ("Spec."); the Final Office Action dated October 2, 2017 ("Final Act."); the Appeal Brief filed November 8, 2017 ("App. Br."); the Examiner's Answer dated March 19, 2018 ("Ans."); and the Reply Brief filed May 8, 2018 ("Reply Br."). Appeal2018-005662 Application 14/504,771 STATEMENT OF THE CASE Appellant2 appeals under 35 U.S.C. § 134(a) from a rejection of claims 1--4, 7, 9--12, and 14. We have jurisdiction under 35 U.S.C. § 6(b). We AFFIRM. The subject matter on appeal relates to bipolar solar cells that include a backside junction formed by an N-type silicon substrate and a P-type polysilicon emitter formed on the backside of the solar cell, and an anti- reflection layer formed on a textured front surface of the silicon substrate. Spec. 2, 11. 14--16. The Specification describes a negative polarity metal contact on the front side of the solar cell making electrical connection to the substrate, and a positive polarity metal contact on the backside of the solar cell making electrical connection to the polysilicon emitter. Spec. 2, 11. 17- 19. The '771 Specification explains that front contact solar cells with electrical connection to a diffusion region on the front side of the solar cell are less aesthetic, and thus less preferred, for residential applications. Spec. 2, 11. 3-8. Where aesthetics are not a major requirement, such as in power plants and other applications where power generation is the main concern, front contact solar cells such as the disclosed structures are said to provide a relatively efficient and cost-effective device. Spec. 2, 11. 6-11. Figure 1 of the '771 Application, reproduced below, shows a schematic cross-section of solar cell 1003 in accordance with an embodiment of the invention. Spec. 4, 11. 3--4. 2 Appellant identifies SunPower Corporation as the real party in interest. App. Br. 1. 3 Labels to elements are presented in bold font thru out this Decision, regardless of their presentation in the original document. 2 Appeal2018-005662 Application 14/504,771 F!G.1 --···H)2 Solar cell 100 has a front side where metal contact 102 is located and a backside on a same side as metal contact 110. Spec. 4, 11. 4--5. The front side faces the sun during normal operation to collect solar radiation. Spec. 4, 1. 5. Solar cell 100 includes a backside junction formed by a P-type doped polysilicon emitter 108 serving as a P-type diffusion region and an N-type silicon substrate 101 serving as an N-type diffusion region. Spec. 4, 11. 7-9. The front side surface of the substrate 101 is randomly textured (labeled as 113) and includes N-type doped regions 105 and 106 formed in the substrate. Spec. 4, 11. 12-14. N-type doped region 105 provides low front surface recombination and region 106 provides low contact resistance and minimizes contact recombination. Spec. 4, 11. 14--17. Anti-reflective coating of silicon nitride layer 103 is formed on the textured front side surface of the substrate 101. Spec. 4, 11. 22-23. Passivating oxide 124 may comprise silicon dioxide thermally grown on the front side surface of the substrate 101. Spec. 5, 11. 1-2. Polysilicon emitter 108 may be formed on tunnel oxide layer 107. Spec. 5, 11. 4--5. Metal contact 110 electrically connects to polysilicon emitter 108 and provides a positive polarity terminal to allow an external electrical circuit to be coupled to and be powered by 3 Appeal2018-005662 Application 14/504,771 solar cell 100. Spec. 5, 11. 10-14. On the front side of solar cell 100, metal contact 102 electrically connects to region 106 through contact holes through the silicon nitride layer 103 and provides a negative polarity terminal to allow an external electrical circuit to be coupled to and be powered by solar cell 100. Spec. 5, 11. 19-22. Claim 1, reproduced below, illustrates the claimed subject matter: 1. A solar cell, comprising: a substrate having a front surface that faces the sun to collect solar radiation during normal operation and a back surface opposite the front surface; an oxide layer disposed on the front surface of the substrate; an anti-reflective coating on the oxide layer; a tunnel dielectric disposed over the back surface of the substrate; an emitter disposed over the tunnel dielectric, the emitter forming a backside junction with the substrate; a doped diffusion region in the substrate; a front electrode that is coupled to the doped diffusion region on the front surface of the substrate; and a back electrode that is coupled to the emitter on the back surface of the substrate. App. Br. 13 (Claims App.). 4 Appeal2018-005662 Application 14/504,771 REFERENCES The Examiner relies on the following prior art in rejecting the claims on appeal: Meier et al. ("Meier") Wenham et al. ("Wenham") Foglietti et al. ("F o glietti") Okayasu et al. ("Okayasu")4 Borden US 6,262,359 B 1 US 6,429,037 Bl US 20002/0142500 Al JP 07106611 WO 2009/094578 A2 July 17, 2001 Aug. 6,2002 Oct. 3, 2002 Apr. 21, 1995 July 30, 2009 Gan and Swanson, POLYSILICON EMITTERS FOR SILICON CONCENTRATOR SOLAR CELLS, Stanford Electronics Laboratories, Electric Power Research Institute, 1 Conf. Record of IEEE Photovoltaic Specialists Conf., 245-250 (1990) REJECTIONS The Examiner maintains the following rejections under 35 U.S.C. § I03(a)5: (1) claims 1--4, 7, 9-12, and 14 over Meier in view of Okayasu, Borden, and Wenham; and (2) claims 1--4, 7, 9-12, and 14 over Meier in view of Okayasu, Foglietti, Gan, and Wenham. Final Act. 2-8. 4 The Examiner refers to a human translation of Okayasu (see Final Act. 2) to which Appellant does not object. 5 Because this application was filed before the March 16, 2013, effective date of the America Invents Act, we refer to the pre-AIA version of the statute. 5 Appeal2018-005662 Application 14/504,771 OPINION Rejection 1 over Meier in view of Okayasu, Borden, and Wenham Appellant argues for patentability of claim 1 and its dependent claims 2--4 and 7 as a group, and for claim 9 and its dependent claims 10-12 as a group. App. Br. 3-7. However, Appellant's arguments regarding claim 9 do not differ substantively from those made in support of patentability of claim I. Compare App. Br. 3---6 with App. Br. 7. We, therefore, select claim 1 as representative of the group. 37 C.F.R. § 4I.37(c)(l)(iv). With respect to claim 1, the Examiner finds that Meier teaches the majority of the limitations. Final Act. 3. The Examiner finds that Meier teaches a method of forming a junction consisting of a p-type emitter on an n-type substrate which comprises using an aluminum electrode asap-type dopant material and driving the dopant in through annealing. Ans. 11 (citing Meier col. 6, 11. 35-50). The Examiner further finds that Meier discloses the presence of a front surface field formed through thermal diffusion and comprised of the same type of dopant as then-type substrate. Id. (citing Meier col. 5, 11. 43--49). The Examiner finds that Okayasu discloses an alternative method for forming a doped emitter or a surface field on a dope substrate. Id. The Examiner finds that Okayasu teaches depositing a doped polysilicon emitter and dope surface field on a doped single crystalline substrate. Id. ( citing Okayasu ,r,r 14, 43). The Examiner finds that Okayasu teaches that its method of depositing doped polysilicon layers is preferable to that of thermal diffusion (as taught in Meier) because it can be performed at lower temperatures, preventing damage to the substrate, and allows more accurate control of the emitter thickness. Id. ( citing Okayasu ,r 8). 6 Appeal2018-005662 Application 14/504,771 The Examiner concludes that one of ordinary skill in the art at the time of the invention would have found it obvious to employ Okayasu's method of forming an emitter or surface field in Meier's back junction solar cell for the advantages articulated by Okayasu. Id. at 12. The Examiner finds that Meier as modified by Okayasu does not disclose a tunneling dielectric oxide between the emitter/front surface field and the substrate. Final Act. 4. However, the Examiner finds that Borden discloses that tunnel oxides can be used in solar cells between doped polysilicon and monocrystalline substrates on both front and back surfaces of the monocrystalline substrate. Id. The Examiner finds that Borden teaches that the tunnel oxide prevent epitaxial growth of amorphous silicon and provides a layer to protect the surface from plasma damage of the deposited emitter layer. Id. 6 The Examiner concludes that it would have been obvious to the skilled artisan to modify the interface between polycrystalline layers and a monocrystalline substrate front and back surface by having a tunneling oxide at the interfaces for the benefits expressed by Borden. Id. The Examiner provides annotated figures, reproduced on the next page, in support of the rejection: 6 The Examiner cites to paragraph 15 of Borden in support of the finding, however, the disclosure is found at paragraph 8. 7 Appeal2018-005662 Application 14/504,771 ....,......tf~ - poht:~f':t$t;;'l~fi~~~ ~\f::H;{~~.f%:•<.tt~~n tJ\,i~" th~· t~~:~3r · · 2/2 ·>!::~·14 •~-~;1i,~~~=1-l~l1~&1'w~ t ..... .1cf~ ~ ~ ~--~~ .~ ... t~ .<'f;,,§ ,~~~~~~~~~~~::~~-:~~'£~~~~ ~z::,~~ .i2i:;) f,., 1 l 1 ·. <,. J ,, . m lLl,"'>'C't:=m, "' ( ~'\..,._..,,l_ ¥~ .., ,t ·" ~ / .\c A~ ,....,,. ·: ·,..,~·,s;:. ~:-~ ··t··'" ] · .. p~p~;h/t::r~'$-l*~H:=-iE~ s: · :-~.<,.-.J~r~ .. d. 'l ~.,:-: .. -~. :,t~l'.'. ~- ' . r , • .. . . , ,· ·j ... "' , .. h:i)·~i: ~'., ~~1~:.::t.i <. ::1:t.t(l~"::.iO:i ,:;i~ .. .,.~ '3·.:71 Of W3rVf~'-~;~~~~~ i t'*~~(~·.~- ~i ~:~;~:t.J i~i(i:-.1~ t~~w-:::~r: l p;;.~:vr:~)·:sti:!~n;s; foy~r ~!1ri r;:, .. S:i ~: ... 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