Ex Parte ZHANG et alDownload PDFPatent Trials and Appeals BoardMar 13, 201914286202 - (D) (P.T.A.B. Mar. 13, 2019) Copy Citation UNITED STA TES p A TENT AND TRADEMARK OFFICE APPLICATION NO. FILING DATE 14/286,202 05/23/2014 23494 7590 03/15/2019 TEXAS INSTRUMENTS IN CORPORA TED PO BOX 655474, MIS 3999 DALLAS, TX 75265 FIRST NAMED INVENTOR YONGXI ZHANG 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. TI-72758 1687 EXAMINER PARK, SAMUEL ART UNIT PAPER NUMBER 2818 NOTIFICATION DATE DELIVERY MODE 03/15/2019 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): uspto@ti.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte YONGXI ZHANG, PHILIP L. HOWER, SAMBER P. PENDHARKAR, JOHN LIN, GURU MATHUR, SCOTT BALSTER, and VICTOR SINOW Appeal2017-005556 Application 14/286,202 Technology Center 2800 Before CATHERINE Q. TIMM, WESLEY B. DERRICK, and CHRISTOPHER L. OGDEN, Administrative Patent Judges. DERRICK, Administrative Patent Judge. DECISION ON APPEAL Appeal2017-005556 Application 14/286,202 STATEMENT OF THE CASE 1 Appellant2 seeks review under 35 U.S.C. § I34(a) from the maintained rejection under 35 U.S.C. § 103 of claims 10-13, 15, and 18-20 over Lotfi3 in view ofChen. 4' 5 We have jurisdiction under 35 U.S.C. § 6(b). We REVERSE. THE INVENTION The subject matter of the claims on appeal relates to a semiconductor device. Spec., Abstract. Claim 10, the sole independent claim, is representative: 10. A method, comprising: providing a transistor having double isolation formed in a semiconductor surface of a substrate doped with a first dopant type, said transistor including: a source region doped with a second dopant type; a drain region including a drain drift region doped with said second dopant type; a gate stack including a gate electrode on a gate dielectric between said source region and said drain region; 1 We refer to the Specification filed May 23, 2014 ("Spec."), the Final Office Action dated October 30, 2015 ("Final Act."), the Appeal Brief filed September 14, 2016, the Advisory Action dated September 23, 2016 ("Adv. Act."), the Examiner's Answer dated December 15, 2016 ("Ans."), and the Reply Brief filed February 15, 2017 ("Reply Br."). 2 Appellant is the Applicant, Texas Instruments Incorporated, which, according to the Appeal Brief, is the real party in interest. Appeal Br. 2. 3 Lotfi et al., US 2011/0049621 Al, published March 3, 2011. 4 Chen et al., US 2014/0061731 Al, published March 6, 2014. 5 Prior pending claims 1-9, 14, 16, and 17 were cancelled (Adv. Act.), obviating previously pending rejections of claims 1-9 and of claim 17 (Final Act. 3-10, 16-17). 2 Appeal2017-005556 Application 14/286,202 a first isolation region doped with said first dopant type; said source region and said drain region being enclosed by said first isolation region, and a second isolation region doped with said second dopant type enclosing said first isolation region, and electrically floating said second isolation region while operating said transistor. App. Br. (Claims Appendix), 10. DISCUSSION On this record, having reviewed the grounds set forth by the Examiner, Appellant's arguments, and the Examiner's response, we are persuaded that the Examiner has failed to establish that the claims are unpatentable. For any ground of rejection, "the [E]xaminer bears the initial burden ... of presenting a prim a facie case of unpatentability." In re Oetiker, 977 F.2d 1443, 1445 (Fed. Cir. 1992). The Examiner relies on Lotfi for its disclosure to provide a transistor, N-LDMOS, formed in a semiconductor surface of substrate. Final Act. 10 (citing Lotfi ,r,r 120-132, Fig. 18). The Examiner cites Lotfi for element 530 as a p-type element, which is relied on for the substrate being doped with a first dopant. Id. (citing Lotfi ,r 120, Fig. 18). As to the transistor, the Examiner cites to element 562 for a source region doped with a second doping type (id. (citing Lotfi ,r 122, Fig. 18)), element 545 for a drain region including a drain drift region (id. (citing Lotfi ,r,r 121, 128, Fig. 18)), and elements 535 and 545 for a gate stack including a gate electrode 540 on a gate dielectric 535 (id. at 10-11 (citing Lotfi 120, Fig. 18)). The Examiner 3 Appeal2017-005556 Application 14/286,202 notes that elements 545 & 562 are on both the left and right of element 540. Id. at 11 ( citing Lotfi, Fig. 18). Id. The Examiner concedes that Lotfi does not disclose a first isolation region doped with a second dopant type; said source region and said drain region being enclosed by said first isolation region, and a second isolation region doped with said second dopant type enclosing said first isolation region, and electrically floating said second isolation region while operating said transistor. The Examiner turns to Chen to remedy the identified deficiencies. Id. at 11-12. The Examiner relies on Chen as disclosing a first isolation region----elements 42, 44, and 46 in combination----doped with said first dopant type, i.e., with p-type doping. Id. at 11 ( citing Chen ,r,r 20, 31, Fig. 1 ). The Examiner maintains that the first isolation region, formed from elements 42, 44, and 46, enclose device area element 28. Id. ( citing Chen ,r 31, Figs. 1, 2). As to the second isolation region, the Examiner maintains that substrate contact region 7 4 meets the claim limitation because Chen, in stating that "semiconductor substrate 22 may be biased via one or more substrate contact regions 74," means that "it may also not be biased" and that this "would make element 74 floating) [sic]." Id. As to being doped with a second dopant, the Examiner relies on element 74 being an n-type because "substitution of semiconductor regions of opposite conductivity type can be performed." Id. ( citing Chen ,r 20, Fig. 1 ). The Examiner concludes: It would have been obvious to one of ordinary skill in the art at the time of the invention to incorporate the isolations & metal layers of Chen into the semiconductor device of Lotfi because the combined device would help in preventing breakdown 4 Appeal2017-005556 Application 14/286,202 during, e.g., high-side operation, and punch-through prevention, as well as, support the formation of an integrated device .... Id. at 12 ( citing Chen ,r,r 27-29). Appellant contends that the Examiner has failed to establish a prima facie case of obviousness. App. Br. 3-9. Appellant argues that Chen discloses a single isolation tub 40 formed from an NBL layer 42, n-type isolating wells 44, and link regions 46. Id. at 5-6 (citing Chen ,r,r 7, 21, 27, 37, 43, Fig. 1). Further, Appellant argues that because then-type buried layer (NBL) 42 in Chen does not have the same doping as the substrate, i.e., p-type, it does not correspond to the "first isolation region" of claim 10 as relied on by the Examiner. Id. at 6. The example device depicted in Chen's Figure 1 is disclosed as having a "semiconductor substrate 22 includ[ing] a single p-type epitaxial layer 24 grown on an original substrate 26 ... [which] may be a lightly or heavily doped p-type substrate." Chen ,r 21. The Examiner does not squarely address Appellant's position, but rather maintains that Lotfi "discloses a substrate with the first dopant type and the combination of Chen ... incorporates a first isolation region with the first dopant type." Ans. 4. The relied on substrate from Lotfi (element 530), however, is also a p-type element and, thus, raises the same issue with the NBL layer 42 in the combination as it does in Chen. See Final Act. 10 ( citing Lofti ,r 120, Fig. 18). Appellant also argues that the substrate contact regions 7 4 do not meet the recited "second isolation region" because they do not function as isolation regions and they are not doped with different dopant types than the substrate. App. Br. 7. The substrate contact regions 74 in Chen's Figure 1 are P+ (Chen, Fig. 1) and the substrate, as explained above, is p-doped (id. ,r 21 ). 5 Appeal2017-005556 Application 14/286,202 The Examiner responds that Appellant's argument is conclusory and not sufficiently supported, that the claims do not require a particular type of isolation, and that the conductivity type can be switched to opposite conductivity type, that is, that the "isolation region of element 7 4 is incorporated as a second conductivity type n-type." Ans. 5 ( citing Chen ,r 20, Fig. 1 ). The Examiner further relies on "element 7 6 [being] the same conductivity type as element 7 4, and elements 44 & 46 & 42 [being] the opposite conductivity type as that of elements 7 4 & 7 6 such that there is a junction of opposite conductivity for isolation, PN-junction." Id. ( citing Chen ,r 43). The Examiner's positions are not well founded on this record. As highlighted by Appellant, it is manifest that the contact regions 7 4 in Chen function to bias the semiconductor substrate and that is contrary to functioning as an isolation region. Reply Br. 2; see also App. Br. 7-8. As to the type of isolation, while contending it is not limited to any particular type, the Examiner relies on electrical isolation in that the lack of biasing suffices. Final Act. 11. The Examiner fails, however, to establish a sufficient basis for any combination in which element 7 4 functions, alone or with other elements, as an isolation region, including that grounded on a lack of biasing. As to switching the conductivity type of element 74 to an n-type, it is grounded on a general disclosure in paragraph 20 of Chen, but there is no particular reasoning set forth by the Examiner sufficient to support that it would have been obvious to do so within the meaning of 35 U.S.C. § 103. See, e.g., Belden v. Berk-TekLLC, 805 F.3d 1064, 1073 (Fed. Cir. 2015) ("[O]bviousness concerns whether a skilled artisan not only could have made but would have been motivated to make the combinations or 6 Appeal2017-005556 Application 14/286,202 modifications of prior art to arrive at the claimed invention."). Further, the Examiner has not sufficiently explained how incorporating n-type material as element 74 would provide an opposite conductivity type as that of elements 42, 44, & 46 where, as explained above, element 42 is an n-buried layer (NBL ). Still further, as highlighted by Appellant, the Examiner has failed to sufficiently establish a basis for forming a PN junction that would function as an isolation element, and citation to Chen's paragraph 43 does not suffice. Ans. 5; Reply Br. 2-3. For these reasons, we do not sustain the rejection of independent claim 10. Accordingly, we reverse the rejection of all claims on appeal. DECISION The Examiner's decision rejecting claims 10-13, 15, and 18-20 is REVERSED. REVERSED 7 Copy with citationCopy as parenthetical citation