2020004577 (P.T.A.B. Jul. 22, 2021)

Texas Instruments Incorporated

Patent Trials and Appeals BoardJul 22, 2021

2020004577 (P.T.A.B. Jul. 22, 2021)

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. 15/597,769 05/17/2017 Naveen Tipirneni TI-75141A 6300 23494 7590 07/22/2021 TEXAS INSTRUMENTS INCORPORATED P O BOX 655474, MS 3999 DALLAS, TX 75265 EXAMINER REAMES, MATTHEW L ART UNIT PAPER NUMBER 2896 NOTIFICATION DATE DELIVERY MODE 07/22/2021 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 NAVEEN TIPIRNENI and SAMEER PENDHARKAR Appeal 2020-004577 Application 15/597,769 Technology Center 2800 Before DONNA M. PRAISS, BRIAN D. RANGE, and SHELDON M. MCGEE, Administrative Patent Judges. MCGEE, Administrative Patent Judge. DECISION ON APPEAL Pursuant to 35 U.S.C. § 134(a), Appellant1 appeals from the Examiner’s decision to reject claims 1–21. We have jurisdiction. 35 U.S.C. § 6(b). We affirm. 1 We use the word “Appellant” to refer to “applicant” as defined in 37 C.F.R. § 1.42. Appellant identifies the real party in interest as Texas Instruments Incorporated. Appeal Br. 3. Appeal 2020-004577 Application 15/597,769 2 CLAIMED SUBJECT MATTER The claims are directed to semiconductor devices and methods of forming such devices. See independent claims 1, 11, 21. Independent claim 1, reproduced below, is illustrative of the claimed subject matter: 1. A semiconductor device, comprising: a substrate of a first conductivity type; a gallium-nitride layer formed over the substrate; a barrier layer comprising III-N semiconductor material formed on the gallium-nitride layer; a cap layer comprising gallium-nitride on the barrier layer; a doped layer of a second, opposite conductivity type between the gallium-nitride layer and the substrate, wherein the doped layer is in direct contact with the first conductivity type of the substrate; a source contact; a drain contact; a gate contact between the source contact and the drain contact; a first dielectric filled trench along a first edge of the gallium-nitride layer, a first edge of the barrier layer, and a first edge of the doped layer; and a second dielectric filled trench along a second edge of the gallium-nitride layer, a second edge of the barrier layer, and a second edge of the doped layer. STATEMENT OF THE CASE The Examiner rejects claims 1–21 under 35 U.S.C. § 103 as unpatentable over the combined disclosures of Lidow2, Tipirneni3, and Plumton4. Final Act. 2–6. Specifically, the Examiner finds that Lidow’s 2 US 2012/0153300 A1, published June 21, 2012. 3 US 8,759,879 B1, issued June 24, 2014. 4 US 5,077,231, issued December 31, 1991. Appeal 2020-004577 Application 15/597,769 3 Figure 4 discloses all the limitations recited in claim 1 except for the cap layer, and the first and second dielectric filled trenches. Id. at 2–4. To address these differences between Lidow and claim 1, the Examiner turns to Tipirneni, which the Examiner undisputedly finds discloses an “optional cap to adjust threshold voltage out of GaN.” Id. at 3. The Examiner also undisputedly finds that Lidow’s Figure 7 embodiment discloses a dielectric filled trench. Id. at 4. Based on these combined teachings, the Examiner provides reasons why it would have been obvious to make these changes to Lidow’s Figure 4 embodiment. Id. at 3–4. Additionally, regarding independent method claim 11, the Examiner finds that “Plumton shows an isolation element item 32 extending through the surface of the substrate,” and determines that the skilled artisan would have been motivated to provide two dielectric filled trenches extending into the substrate to provide total isolation for the device. Id. at 4. OPINION We review the appealed rejection for reversible error based on the arguments and evidence presented by Appellant. 37 C.F.R. § 41.37(c)(1)(iv); Ex parte Frye, 94 USPQ2d 1072, 1075 (BPAI 2010) (precedential) cited with approval in In re Jung, 637 F.3d 1356, 1365 (Fed. Cir. 2011) (explaining that even if the Examiner had failed to make a prima facie case, “it has long been the Board’s practice to require an applicant to identify the alleged error in the examiner’s rejections”). Claims 1–10 and 21 The dispositive issue raised by Appellant’s arguments on appeal is whether the Examiner reversibly erred in determining that the skilled artisan Appeal 2020-004577 Application 15/597,769 4 would have been motivated to add two dielectric filled trenches to Lidow’s embodiment depicted in Figure 4. Upon consideration of Appellant’s arguments in light of the evidence in the appeal record, we determine that Appellant has identified no such error. We therefore affirm the obviousness rejection of claims 1–10 and 21 for the reasons expressed by the Examiner. Final Act. 2–6; Ans. 3–5.5 We add the following for emphasis. Appellant’s main argument on appeal is that Lidow teaches to use trenches when the device’s layers have the same conductivity type, i.e., not when the layers have opposite conductivity. See Appeal Br. 4–5 (identifying the device depicted in Figure 4A as having “a conductive substrate where regions are doped with opposite-polarized conductivity” and the Figure 7A device as having the same doping type); id. at 5 (asserting that “trenches are only taught in [] Lidow when the doped region 71 and the substrate 72 have the same doping type ([0050], [0067])”); id. at 6 (asserting “[t]he Examiner has provided no reasonable rationale for” the skilled artisan to “modify Lidow to include the trenches of FIG. 7 (provided for isolation when the same doping types are used for 71 and 72) in the embodiment of FIG. 4 (opposite doping types of 51, 52).”). This line of argument is unpersuasive because Appellant has not established that Lidow’s Figure 7––containing substrate 72, well 71, and trench 70––must always contain the same doping type or conductivity. 5 We do not, however, agree with the Examiner’s statement in the Answer that Appellant argues that Lidow teaches away from adding trenches to the Figure 4 embodiment. Ans. 4. No such argument appears in the Appeal Brief. See Reply Br. 1 (explaining that the argument was that the skilled artisan would not have been motivated to combine the trenches of Figure 7A to the device of Figure 4A). Appeal 2020-004577 Application 15/597,769 5 Indeed, Appellant’s argument is undermined by Lidow’s express disclosure, which allows substrate 72 and well 71 to “consist of similar materials as substrate 52 . . . and well 51, respectively.” Lidow ¶ 67. Here, we emphasize that substrate 52 and well 51 may have an opposite-polarized conductivity––a point which Appellant acknowledges. Id. ¶¶ 53–54; Appeal Br. 4. It follows that substrate 72 and well 71 may also have such an opposite-polarized conductivity. Id. ¶ 67. Thus, the entire premise of Appellant’s argument is unsupported, and is contradicted by Lidow’s express disclosure. We also observe that Appellant advances an untimely argument in the Reply Brief. Reply Br. 1–2 (citing Lidow ¶¶ 54, 69–74). Specifically, Appellant discusses the purported “junction isolation” in Figure 4A vis-à-vis “oxide isolation” in Figure 7A, and asserts “[t]he only suggestion in Lidow is to use one or the other. There is no suggestion to use them both in the same device.” Id. Because Appellant has not shown good cause why this argument could not have been raised in the Appeal Brief, we do not consider it. 37 C.F.R. § 41.41(b)(2). Claims 11–20 For method claim 11, Appellant repeats the same line of argument as provided in the Appeal Brief for claim 1, which we find unpersuasive for the same reasons given supra. Appeal Br. 6–7. Appellant also argues that the Examiner fails to provide a suitable rationale that would have suggested extending the trenches into the substrate as claimed. Id. at 7. We disagree. Final Act. 4 (determining that “it would have been obvious to provide two dielectric filled trenches extending into the substrate to provide total Appeal 2020-004577 Application 15/597,769 6 isolation for the device.”); see also Ans. 4–5 (explaining how “optimization of [trench] depth relates directly to the optimization of [] isolation.”).6 CONCLUSION The Examiner’s rejection is affirmed. DECISION SUMMARY Claims Rejected 35 U.S.C. § Reference(s) / Basis Affirmed Reversed 1–21 103 Lidow, Tipirneni, Plumton 1–21 No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R. § 1.136(a). See 37 C.F.R. § 1.136(a)(1)(iv). AFFIRMED 6 Significantly, Appellant does not contest this statement in the Reply Brief.