Ex Parte Tapily et al

Patent Trials and Appeals BoardJun 5, 2019

14635806 - (D) (P.T.A.B. Jun. 5, 2019)

UNITED STA TES p A TENT AND TRADEMARK OFFICE APPLICATION NO. FILING DATE FIRST NAMED INVENTOR 14/635,806 03/02/2015 Kandabara N. Tapily 37694 7590 06/07/2019 WOOD, HERRON & EV ANS, LLP (TOKYO ELECTRON) 2700 CAREW TOWER 441 VINE STREET CINCINNATI, OH 45202 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. TTCA-457US3 5188 EXAMINER TRAN,DZUNG ART UNIT PAPER NUMBER 2829 NOTIFICATION DATE DELIVERY MODE 06/07/2019 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): usptodock@whe-law.com abilton@whe-law.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE BEFORE THE PATENT TRIAL AND APPEAL BOARD Ex parte KANDABARA N. TAPIL Y and ROBERT D. CLARK Appeal2018-006223 Application 14/635,806 Technology Center 2800 Before LINDA M. GAUDETTE, CHRISTOPHER C. KENNEDY, and LILAN REN, Administrative Patent Judges. GAUDETTE, Administrative Patent Judge. DECISION ON APPEAL 1 1 This Decision includes citations to the following documents: Specification filed Mar. 2, 2015, as amended ("Spec."); Final Office Action dated July 14, 2017 ("Final"); Appeal Brief filed Jan. 11, 2018 ("Appeal Br."); Examiner's Answer dated Mar. 26, 2018 ("Ans."); and Reply Brief filed May 29, 2018 ("Reply Br."). Appeal2018-006223 Application 14/635,806 The Appellant2 appeals under 35 U.S.C. Â§ I34(a) from the Examiner's decision finally rejecting claims 1-20 under 35 U.S.C. Â§ 103 as follows: (1) claims 1-8 and 11-20 over Vandroux3 in view of Chang4, and (2) claims 9 and 10 over V androux in view of Higuchi 5 and Chang. 6 We REVERSE. The "invention generally relates to a method of enhancing high-dielectric constant (high-k) film nucleation rate and electrical mobility in a semiconductor device by microwave plasma treatment of an interface layer on a substrate prior to deposition of a high-k film on the interface layer." Spec. ,r 2. According to the Specification, exposing the interface layer to plasma excited species forms a modified interface layer with increased electrical mobility, whereby a high-k film that is subsequently deposited on the modified interface layer by atomic layer deposition (ALD) nucleates at a higher rate than on a non-modified interface layer. Id. ,r 6. The high-k film is said to possess superior material and electronic properties needed for advanced semiconductor devices, including scaled CMOS devices. Id. f 21. Of the appealed claims, claims 1, 15, and 17 are independent, and each recites a method for forming a semiconductor device. See generally Appeal Br. 15-18 (Claims Appendix). Claim 1 is representative, and is reproduced below. 2 The Appellant is the Applicant, Tokyo Electron Limited, also identified as the real party in interest. Appeal Br. 3. 3 US 2005/0215034 Al, pub. Sep. 29, 2005. 4 US 20I0/0075507Al, pub. Mar. 25, 2010. 5 US 2013/0228735 Al, pub. Sep. 5, 2013. 6 We have jurisdiction under 35 U.S.C. Â§ 6(b ). 2 Appeal2018-006223 Application 14/635,806 1. A method for forming a semiconductor device, the method compnsmg: providing a substrate in a process chamber; flowing a process gas consisting of hydrogen (H2) and optionally a noble gas into the process chamber; forming plasma excited species from the process gas by a microwave plasma source; exposing an interface layer on the substrate to the plasma excited species to form a modified interface layer; and depositing a high dielectric constant (high-k) film by atomic layer deposition (ALD) on the modified interface layer. Id. at 15. The Examiner determined the invention, as recited in claim 1, would have been obvious in view of the combined teachings of Vandroux and Chang. See Final 3. The Vandroux and Chang methods are summarized below. V androux discloses "methods and systems for reducing oxide contamination of germanium substrates and for forming dielectric layers over germanium substrates." Vandroux ,r 4. Vandroux describes a method that includes steps of (1) positioning a germanium substrate in a process chamber (id. ,r 16), (2) generating a plasma from a hydrogen-containing treatment gas such as H2 (id.) using a microwave plasma system (id. ,r 24), (3) providing the treatment gas plasma to the process chamber (id. ,r 17), ( 4) effecting a reduction reaction whereby the native oxide becomes less dense toward the top surface of the germanium substrate, the reduction being sufficient to provide an improved interface for deposition of a dielectric (id.), and (5) depositing a dielectric layer (id. ,r 22). Vandroux discloses that if the dielectric contains an oxide ( e.g., Si02), the method should include an additional step, prior to the step of depositing the dielectric layer, of exposing the improved interface to a silicon-containing gas to form an amorphous silicon 3 Appeal2018-006223 Application 14/635,806 protective layer (id. ,r 19) that acts as a barrier to prevent interaction of substances used in depositing the dielectric layer with the oxide-reduced germanium substrate Chang discloses a method of fabricating a semiconductor device. Chang ,r 6. The substrate includes a silicon substrate that may include germanium. Id. ,r 28. Chang's method includes forming an Si02 interfacial layer over the substrate by treating the H-terminated silicon substrate in a process chamber with hydrous radicals generated by plasma containing O and H atoms. Id. ,r 29. Chang discloses that a radical surface treatment may be performed on the Si02 interfacial layer/Si substrate configuration to improve surface conditions of the interfacial layer for better formation of the high-k dielectric layer. Id. ,r 31. Chang discloses that the method may continue to form various microelectronic devices such as transistors, resistors, capacitors, etc. of an integrated circuit; for example, the interfacial and high-k dielectric layers may be used as the gate dielectric for various nMOSFET and pMOSFET devices formed in the substrate. Id. ,r 34. The Examiner found Vandroux discloses the first three steps of the claim 1 method, but does not disclose explicitly the remaining recited steps of exposing an interface layer to form a modified interface layer and depositing a high dielectric constant film. Final 3. The Examiner found Chang discloses a method that includes steps of exposing and depositing as recited in claim 1. Id. The Examiner found one of ordinary skill in the art would have modified Vandroux's method to include steps of "exposing an interface layer on the substrate to the plasma excited species to form a modified interface layer; and depositing a high dielectric constant (high- k) film by atomic layer deposition (ALD) on the modified interface layer in order to fabricate a high-k gate dielectric for various nMOSFET and pMOSFET devices in the substrate" as taught by Chang. Id. ( citing Chang ,r 34). 4 Appeal2018-006223 Application 14/635,806 The Appellant argues Chang's method "uses a plasma of hydrous radicals whereas Vandroux utilizes a plasma of hydrogen ions. These are different plasma excited species and produce different effects." Appeal Br. 8 ( emphasis omitted). The Appellant also argues "[t]he goal of Chang's [method] is to grow an oxide layer and to replace the H-terminations with hydroxyl functional groups. The goal of Vandroux is to remove or reduce an oxide from the substrate." Id. The Appellant contends the Examiner has not articulated with sufficient clarity how and why the ordinary artisan would have combined the Vandroux and Chang methods, which utilize different plasma excited species to achieve different goals See, e.g. Appeal Br. 6-7. We agree. In the Response to Argument section of the Answer, the Examiner asserts that Vandroux "discloses a hydrogen plasma is for oxide reduction treatment on the germanium substrate ... and providing an improved interface for deposition of a dielectric .... This advantage can be utilized to improve a method for forming a high-k dielectric layer on the interfacial layer on a substrate ... as taught by Chang[]." Ans. 5 (emphasis added). We agree with the Appellant that the Examiner relied on improper hindsight reasoning in determining how the references could be combined to achieve the claimed invention, rather than considering what the prior art teachings would have suggested to the ordinary artisan at the time of the invention. See, e.g., Reply Br. 2-3 ("Examiner has not established why one skilled in the art would be motivated to treat the amorphous silicon protective layer with hydrogen plasma, since Vandroux makes no such suggestion, and since Chang teaches that the interface layer is a Si02 dielectric layer and the necessary treatment involves an oxygen-containing gas in order to form hydroxyl terminations. Examiner simply has not explained why the teachings of Chang (that a Si02 interfacial layer would be formed with hydroxyl terminations 5 Appeal2018-006223 Application 14/635,806 to suppress oxide regrowth of the underlying substrate and to provide wetting for a high-k dielectric layer) would be ignored in favor of treating an interfacial layer with hydrogen plasma that has only been disclosed by Vandroux for oxide reduction on the germanium substrate before depositing a Si02 dielectric layer (non-high-k conventional dielectric)."). In sum, because the Appellant has argued persuasively that the Examiner's rejection of claim 1 is based on improper hindsight reasoning, we do not sustain the rejection of claim 1 or its dependent claims 2-8 and 11-14. The Examiner relies on the same improper hindsight reasoning in rejection claims 15 and 17, which recite process steps similar to those in claim 1. See Final 4---6. Accordingly, we likewise do not sustain the rejection as to claims 15 and 17, and their dependent claims 16 and 18-20. In rejecting claims 9 and 10, the Examiner also relies on Higuchi. See Final 9-10. We agree with the Appellant that Higuchi fails to cure the above-noted deficiencies in the Examiner's combination of Vandroux and Chang. Therefore, we do not sustain the rejection of claims 9 and 10. REVERSED 6