Huang Liu et al.Download PDFPatent Trials and Appeals BoardJul 21, 20202018001645 (P.T.A.B. Jul. 21, 2020) Copy Citation 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. 14/219,039 03/19/2014 Huang Liu EU552/4014.252100 1764 123187 7590 07/21/2020 Williams Morgan, P.C. 6464 Savoy Suite 600 Houston, TX 77036 EXAMINER MAI, ANH D ART UNIT PAPER NUMBER 2829 NOTIFICATION DATE DELIVERY MODE 07/21/2020 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): Docketing@wmalaw.com nnolan@wmalaw.com PTOL-90A (Rev. 04/07) UNITED STATES PATENT AND TRADEMARK OFFICE ____________ BEFORE THE PATENT TRIAL AND APPEAL BOARD ____________ Ex parte HUANG LIU, WEN-PIN PENG, and JEAN-BAPTISTE LALOE 1 ____________ Appeal 2018-001645 Application 14/219,039 Technology Center 2800 ____________ Before ROMULO H. DELMENDO, JAMES T. MOORE, and MONTÉ T. SQUIRE, Administrative Patent Judges. DELMENDO, Administrative Patent Judge. DECISION ON APPEAL The Appellant files this appeal under 35 U.S.C. § 134(a) from a final rejection of claims 1–3 and 5–7.2 We have jurisdiction under 35 U.S.C. § 6(b). We REVERSE. 1 We use the word “Appellant” to refer to “applicant” as defined in 37 C.F.R. § 1.42—“GLOBALFOUNDRIES Inc.,” Application Data Sheet filed March 19, 2014 at 4, which is also listed as the real party in interest. Appeal Brief dated June 5, 2017 (“Appeal Br.”) 2. 2 Claims 4 and 10–20 are withdrawn. Appeal Br. 15–18 (Claims App.). Claims 8 and 9 were cancelled after final rejection. Id.; Advisory Action entered February 9, 2017; Amendment filed February 9, 2017. Appeal 2018-001645 Application 14/219,039 2 BACKGROUND The Appellant’s claims are directed to a method for forming a metal gate on a semiconductor device including de-oxidizing the metal gate using a reducing agent. Specification filed February 18, 2016 (“Spec.”) ¶ 14. The Specification discloses that the process of fabricating semiconductor devices in an open-air environment may oxidize exposed portions of metal gates previously formed on the devices. Id. ¶ 2. According to the Specification, This oxidation can alter the characteristics of the gate metal, and, by extension, the gate itself, causing the gate to perform less optimally. In addition, the presence of an oxide layer can lead to unintended consequences in later fabrication steps, further degrading the performance of the gate. Id. To solve this problem, the Specification discloses that “[a] reducing agent can be used to de-oxidize the metal that forms the metal gate, leaving a substantially non-oxidized surface.” Id. ¶ 14. Claim 1, the sole independent claim on appeal, is representative of the subject matter on appeal and is reproduced below: 1. A method for forming a metal gate in a semiconductor device, comprising: forming the metal gate on a substrate in the semiconductor device; de-oxidizing, using a reducing agent, an oxidation layer formed on the metal gate; and[] forming raised source-drains in proximity to the metal gate. Appeal Br. 15 (Claims App.). Appeal 2018-001645 Application 14/219,039 3 REJECTIONS ON APPEAL3 1. The Examiner rejected claims 1, 2, and 5–7 under 35 U.S.C. § 103 as unpatentable over the combination of Chiang4 and Wood.5 Final Office Action entered November 7, 2016 (“Final Act.”) 5–7; Examiner’s Answer entered October 3, 2017 (“Ans.”) at 5–13. 2. The Examiner rejected claim 3 under 35 U.S.C. § 103 as unpatentable over the combination of Chiang, Wood, and Ngo.6 Final Act. 7; Ans. 13. 3. The Examiner rejected claims 1–3, 5, and 7 under 35 U.S.C. § 103 as unpatentable over the combination of Chiang and Ngo. Final Act. 8–9; Ans. 13–14. 4. The Examiner rejected claim 6 under 35 U.S.C. § 103 as unpatentable over the combination Chiang, Ngo, and Chang.7 Final Act. 9–10; Ans. 14–15. 3 The rejections of claim 8 under 35 U.S.C. § 112(b) as being indefinite and claims 8 and 9 under 35 U.S.C. § 112(d) as being improper dependent claims, as set forth in the Final Action, are moot because claims 8 and 9 have been cancelled. 4 Chiang et al., US 2013/0113027 A1, published May 9, 2013. 5 Wood et al., US 7,604,708 B2, issued October 20, 2009. 6 Ngo et al., US 6,335,283 B1, issued January 1, 2002. 7 Chang et al., US 8,202,776 B2, issued June 19, 2012. Appeal 2018-001645 Application 14/219,039 4 DISCUSSION I. Obviousness of Claims 1–3 and 5–7 over the Combination of Chiang, Wood, and Ngo (for Claim 3) The Examiner finds that Chiang teaches “a method forming a metal gate in a semiconductor device” including the steps of “forming the metal gate (330) on . . . substrate (300) in the semiconductor device; forming . . . oxidation layer (335) on . . . metal gate (330); and forming raised source- drains [sic] [electrodes] (322) in proximity to . . . metal gate (330).” Final Act. 5 (citing Chiang, Figs. 5–6); see also id. ¶¶ 21–22. The Examiner acknowledges that Chiang does not explicitly disclose de-oxidizing the oxidation layer formed on the metal gate. Id. Nevertheless, the Examiner finds that the “metal oxide layer 335, above . . . metal gate 330, must be removed so that electrical contact can be made to the gate.” Ans. 4. The Examiner finds that “Wood teaches a method for forming a contact to a metal in a semiconductor device including: de-oxidizing, using a reducing agent, . . . oxidation layer (12) formed on . . . metal (16).” Id. The Examiner finds that Wood teaches “the de-oxidizing agent interacts more specifically with . . . deposits 12 and [does] not undesirably damage the structure of . . . surrounding low k dielectric layer 18.” Id. at 13 (citing Wood 5:9–26). The Examiner therefore concludes that it would have been obvious to one having ordinary skill in the art at the time of invention was made to form [the] metal gate of Chiang[,] including de-oxidizing the oxidation layer formed on the metal gate as taught by Wood[,] to remove the oxidation layer without damaging the surrounding layers. Id. at 6. Appeal 2018-001645 Application 14/219,039 5 The Appellant argues that the Examiner “fails to identify the reason why the person of ordinary skill in the art would have combined the prior art references in the manner set forth in the claims.” Appeal Br. 5. Specifically, the Appellant contends that “no evidence of record supports the contention that the person of ordinary skill in the art would wish to remove Chiang’s protective layer 335 by any technique.” Id. Rather, the Appellant contends that Chiang teaches forming protective oxidation layer 335 by performing an oxygen treatment as a preferred embodiment. Id. (citing Chiang ¶ 22). What is more, the Appellant points out that Chiang discloses forming dielectric layer 329 and barrier layer 336 over oxidation layer 335. Id. at 6. (citing Chiang ¶¶ 25–26; Figs. 8, 10). Based on these disclosures, Appellant contends that Chiang suggests retaining, rather than removing, oxidation layer 335. See id. at 5–6. Additionally, the Appellant argues that a person of ordinary skill in the art would not have been motivated by Wood to modify Chiang. See id. at 8–9. The Appellant argues that Wood teaches “that oxides are undesirable on metal-containing conductors deposited on a substrate.” Id. at 8 (citing Wood 1:13–2:38). The Appellant contends that, therefore, Wood’s teaching is not relevant to Chiang’s gates or transistors. Id. (citing Chiang ¶¶ 25–26). We agree with the Appellant and find that a preponderance of the evidence does not support the Examiner’s rejection. In a preferred embodiment, Chiang teaches intentionally performing an oxygen treatment on the low resistance layer of the metal gate to form an oxidized protective layer 335. Chiang ¶ 22. Chiang teaches that this oxidized protective layer 335 prevents transistor 340 from being damaged due to etching selectivity. Id. ¶ 26. Thus, although described in the context of a preferred embodiment Appeal 2018-001645 Application 14/219,039 6 of Chiang’s gate structure, Wood’s teachings regarding a de-oxidation process to remove an undesired oxide film 12 from a surface 14 of a conductor 16, Wood 1:14–47; 4:45–50, are inapt for Chiang’s gate in which an oxide film is disclosed as a protective film, not an undesired deposited film. “The mere fact that the prior art may be modified in the manner suggested by the Examiner does not make the modification obvious unless the prior art suggested the desirability of the modification.” In re Fritch, 972 F.2d 1260, 1266 (Fed. Cir. 1992). Accordingly, we reverse the rejection of claim 1 under 35 U.S.C. § 103 over the combination of Chiang and Wood. The rejections of dependent claims 2, 3, and 5–7 over Chiang, Wood, and Ngo (for claim 3) fall with claim 1. II. Obviousness of Claims 1–3 and 5–7 over the Combination of Chiang, Ngo and Chang (for Claim 6) The Examiner finds that “Ngo teaches a method for forming a contact to a metal in a semiconductor device including: de-oxidizing, using a reducing agent, . . . oxidation layer (24) formed on . . . metal (23).” Final Act. 8 (citing Ngo, Figs. 2–4); see also Ngo 6:20–56. The Examiner concludes that “it would have been obvious to one having ordinary skill in the art at the time of invention was made to form [the] metal gate of Chiang including de-oxidizing the oxidation layer formed on the metal gate as taught by Ngo to clean the exposed surface of the metal.” Id. The Appellant contends that “[l]ike Wood, Ngo is directed to cleaning oxides from conductive lines[,] such as copper oxide film 24 from copper lines 23. Ngo is silent regarding metal gates.” Appeal Br. 11 (emphasis omitted). Hence, Appellant argues that a person of ordinary skill in the art Appeal 2018-001645 Application 14/219,039 7 would not have been motivated by Ngo “to remove Chiang’s protective layer 335 from metal gate 330.” Id. at 12 (emphasis omitted). We agree with the Appellant and find that the preponderance of the evidence does not support the Examiner’s rejection. As in the rejection based on Wood, Ngo has not been shown to provide a reason for removing Chiang’s protective layer by de-oxidizing using a reducing agent because such a removal is inconsistent with Chiang’s stated goal and, additionally, Ngo is directed to conductive lines and not gates. Accordingly, we reverse the rejection of claim 1 under 35 U.S.C. § 103 over the combination of Chiang and Ngo. The rejections of dependent claims 2, 3, and 5–7 over Chiang, Ngo, and Chang (for claim 6) fall with claim 1. CONCLUSION In summary, we reverse the Examiner’s rejections under 35 U.S.C. § 103 as follows: Claims Rejected 35 U.S.C. § Reference(s)/Basis Affirmed Reversed 1, 2, 5–7 103 Chiang, Wood 1, 2, 5–7 3 103 Chiang, Wood, Ngo 3 1–3, 5, 7 103 Chiang, Ngo 1–3, 5, 7 6 103 Chiang, Ngo, Chang 6 Overall Outcome 1–3, 5–7 REVERSED Copy with citationCopy as parenthetical citation