Ex Parte Houston et al

Patent Trial and Appeal BoardOct 30, 2017

13043163 (P.T.A.B. Oct. 30, 2017)

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. 13/043,163 03/08/2011 Theodore W. Houston TI-66545.1 8363 23494 7590 11/01/2017 TEXAS INSTRUMENTS INCORPORATED P O BOX 655474, M/S 3999 DALLAS, TX 75265 EXAMINER CHEN, DAVID Z ART UNIT PAPER NUMBER 2815 NOTIFICATION DATE DELIVERY MODE 11/01/2017 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 THEODORE W. HOUSTON, THOMAS J. ATON, and SCOTT W. JESSEN Appeal 2015-003283 Application 13/043,163 Technology Center 2800 Before ROMULO H. DELMENDO, MARKNAGUMO, and JEFFREY R. SNAY, Administrative Patent Judges. SNAY, Administrative Patent Judge. DECISION ON APPEAL1 Appellants2 appeal under 35 U.S.C. § 134(a) from the Examiner’s decision rejecting claims 1—10. We have jurisdiction under 35 U.S.C. § 6(b). We affirm-in-part. 1 We cite to the Specification (“Spec.”) filed March 8, 2011; Final Office Action (“Final Act.”) dated June 5, 2014; Appellants’ Appeal Brief (“Br.”) dated August 8, 2014; and Examiner’s Answer (“Ans.”) dated November 12, 2014. 2 Appellants identify Texas Instruments Incorporated as the real party in interest. Br. 3. Appeal 2015-003283 Application 13/043,163 BACKGROUND The subject matter on appeal relates to a process for forming an integrated circuit containing static random access memory cells (SRAMs). Spec. 12; claim 1. Particularly, Appellants describe forming “T-shaped contacts, in which each T-shaped contact provides an electrical connection between a drain node of a driver transistor and a drain node of a corresponding load transistor in one inverter and a gate of an opposite inverter, where the two inverters form cross-coupled inverters in the SRAM cell.” Spec. 112. Claim 1 is illustrative and reproduced from the Claims Appendix of the Appeal Brief as follows: 1. A process of forming an integrated circuit containing an array of SRAM (Static Random Access Memory) cells, comprising the steps: providing an integrated circuit containing a first driver/passgate active strip having a first conductivity type, a second driver/passgate active strip having said first conductivity type, a first load active strip having a second conductivity type opposite from said first conductivity type, a second load active strip having said second conductivity type, a first inverter gate that crosses said first driver/passgate active strip over a channel region of a first driver transistor and crosses said first load active strip over a channel region of a first load transistor, and a second inverter gate that crosses said second driver/passgate active strip over a channel region of a second driver transistor and crosses said second load active strip over a channel region of a second load transistor; performing a first photolithographic exposure step to form a first drain connecting segment patterned area of a first T-shaped contact and to form a second drain connecting segment patterned area of a second T-shaped contact, such that said first drain connecting segment patterned area overlaps said first driver/passgate active strip over a drain node of said first driver transistor and also overlaps said first load active strip over a drain node of said first load transistor, and said second 2 Appeal 2015-003283 Application 13/043,163 drain connecting segment patterned area overlaps said second driver/passgate active strip over a drain node of said second driver transistor and overlaps said second load active strip over a drain node of said second load transistor; performing a second photolithographic exposure step to form a first gate connecting segment patterned area of said first T-shaped contact and to form a second gate connecting segment patterned area of said second T-shaped contact, such that said first gate connecting segment patterned area intersects said first drain connecting segment patterned area, and said second gate connecting segment patterned area intersects said second drain connecting segment patterned area; forming said first T-shaped contact in an area defined by said first drain connecting segment patterned area and said first gate connecting segment patterned area, such that said first T- shaped contact includes a first drain connecting segment in an area defined by said first drain connecting segment patterned area, said first T-shaped contact also includes a first gate connecting segment in an area defined by said first gate connecting segment patterned area, said first drain connecting segment is substantially laterally adjacent to said first gate connecting segment; and said first T-shaped contact provides an electrical connection between said drain node of said first driver transistor, said drain node of said first load transistor, and said second inverter gate; and forming said second T-shaped contact concurrently with said first T-shaped contact in an area defined by said second drain connecting segment patterned area and said second gate connecting segment patterned area, such that said second T- shaped contact includes a second drain connecting segment in an area defined by said second drain connecting segment patterned area, said second T-shaped contact also includes a second gate connecting segment in an area defined by said second gate connecting segment patterned area, said second drain connecting segment is substantially laterally adjacent to said second gate connecting segment; and said second T-shaped contact provides an electrical connection between said drain node of said second driver transistor, said drain node of said second load transistor, and said first inverter gate; 3 Appeal 2015-003283 Application 13/043,163 wherein an end of said first drain connecting segment over said drain node of said first load transistor extends beyond an inner comer of an intersection of said first drain connecting segment with said first gate connecting segment by a distance greater than 10 percent of an end separation distance between ends of said first drain connecting segment and said second drain connecting segment, and an end of said second drain connecting segment over said drain node of said second load transistor extends beyond an inner comer of an intersection of said second drain connecting segment with said second gate connecting segment by a distance greater than 10 percent of said end separation distance between ends of said first drain connecting segment and said second drain connecting segment. REJECTIONS The Examiner maintains the following grounds of rejection3: I. Claims 1—3 and 6—8 stand rejected under 35 U.S.C. § 103(a) as unpatentable over Satomi,4 Rathsack,5 and Yang.6 II. Claims 4, 5, 9, and 10 stand rejected under 35 U.S.C. § 103(a) as unpatentable over Satomi, Rathsack, Yang, and Tsuboi.7 3 Final Act. 4—9. The Examiner additionally finds that claims 1—10 are “patentably indistinct from claims of Application No. 13/530,368, 13/530,390, and 13/530,410.” Id. at 2. The Examiner presents this finding—in a conclusory fashion—under the heading, “Double Patenting,” but does not otherwise articulate a formal double-patenting rejection. Id. at 2—3; see also Ans. 12—13. Because each of the above-listed applications is abandoned, we consider any underlying double-patenting issue to be moot. 4 US 2003/0067819 Al, published April 10, 2003 (“Satomi”). 5 US 2007/0099424 Al, published May 3, 2007 (“Rathsack”). 6 US 2008/0048297 Al, published February 28, 2008 (“Yang”). 7 US 2007/0080423 Al, published April 12, 2007 (“Tsuboi”). 4 Appeal 2015-003283 Application 13/043,163 DISCUSSION Rejection I Appellants separately argue each of the rejected claims. See Br. 24— 50. Claim 1 The Examiner finds that Satomi discloses all of the features recited in claim 1, except that “Satomi does not specifically disclose performing photolithographic exposure steps to form the first T-shaped contact and the second T-shaped contact patterned areas, and forming the first T-shaped contact and the second T-shaped contact concurrently.” Final Act. 7. Particularly, with reference to Satomi’s Figure 8, the Examiner finds that Satomi discloses a “T-shaped contact [which] provides an electrical connection between said drain node (DN1 contact) of said first driver transistor (TNI), said drain node (DPI contact) of said first load transistor (TP1), and said second inverter gate (PF2).” Id. at 5—6. A corresponding second T-shaped contact is highlighted in the Examiner’s annotated copy of Satomi’s Figure 8. Id. at 8. Appellants argue that Rathsack does not teach a T-shaped contact having a first drain connecting segment that is “substantially laterally adjacent” to the first gate connecting segment, as required by claim 1. Br. 25. Appellants also argue that Rathsack does not teach the recited end separation distance between end of first and second drain connecting segments of the first and second T-shaped contacts. Id. These arguments are not persuasive of reversible error because the Examiner expressly relies on Satomi as disclosing these features, not Rathsack. See Final Act. 4—7. 5 Appeal 2015-003283 Application 13/043,163 Appellants’ argument that Yang also does not teach such a T-shaped contact (Br. 28—29) is not persuasive for the same reason. Appellants also contend that these features are not found in Satomi. Br. 26—27. To support that contention, Appellants point to Satomi’s disclosure in paragraph 54 as evidence that Satomi’s “drain connecting segment is in a different circuit level that overlaps the gate connecting segment.” Id. at 26. Satomi’s paragraph 54 relates to Figure 1 of the reference, and identifies various connections shown in that Figure, including polysilicon wire PL1 connecting gates of drive transistor TNI and load transistor TP1, and wiring layer AL1 connecting drains of the above- mentioned drive and load transistors. See Satomi | 54. Appellants do not explain how this disclosure in Satomi requires that drain and gate connecting segments of the T-shaped connector identified by the Examiner are in a different circuit level. Nor do Appellants explain why such a different circuit level would preclude Satomi’s T-shaped contact segments from being “substantially laterally adjacent” (claim 1) to one another. To the contrary, the T-shaped contact element highlighted in the Examiner’s annotated copy of Satomi’s Figure 8 (Final Act. 8) shows a horizontally-depicted drain connecting segment that is laterally adjacent to a vertically-depicted gate connecting segment. Appellants do not persuade us that Satomi’s description in paragraph 54 negates the Examiner’s findings regarding the T- shaped contacts depicted in Satomi’s Figure 8. Appellants further contend that Satomi fails to disclose the T-shaped contact extending a distance beyond an inner comer of the intersection of the gate and drain connecting segments that is greater than 10 percent of an end separation between the first and second T-shaped contacts. Br. 26—27. The 6 Appeal 2015-003283 Application 13/043,163 Examiner relies on the relative proportions and distances depicted in Satomi’s Figure 8 as evidence in support of the finding that Satomi discloses this arrangement. Because Appellants do not point us to evidence or credible technical reasoning to refute the Examiner’s finding, Appellants’ contention amounts to unsubstantiated attorney argument and is not persuasive of reversible error. Appellants also argue that Rathsack does not teach performing photolithographic exposure “to form a first drain connecting segment patterned area of a first T-shaped contact and to form a second drain connecting segment patterned area of a second T-shaped contact.” Br. 30. However, the Examiner’s reasoning in support of Rejection I relies on Satomi as disclosing the above-mentioned T-shaped contact, with Rathsack providing a reason to perform preliminary photolithographic exposure steps to form patterned areas to facilitate formation of Satomi’s T-shaped contact. Final Act. 7. Appellants’ argument directed solely toward Rathsack fails to address the combined teachings of the prior art relied upon by the Examiner, and fails to identify reversible error for that reason. Similarly, Appellants’ argument that Yang fails to teach separate photolithographic exposures steps does not address the basis of the rejection expressly relies on Rathsack for that teaching. See Ans. 6. For the foregoing reasons, we sustain Rejection I as applied to claim 1. Claim 2 Claim 2 further requires that intersecting edges of the drain and gate connecting segments of each T-shaped contact are substantially perpendicular. The Examiner shows such perpendicular arrangement in the 7 Appeal 2015-003283 Application 13/043,163 annotated copy of Satomi’s Figure 8. Final Act. 8. Appellants argue that Satomi’s drain connecting segment and gate connecting segment are substantially perpendicular “in the vertical direction,” not in the “lateral direction.” Br. 34. This argument is not persuasive. As found by the Examiner, Satomi’s Figure 8 depicts a T-shaped contact which includes a gate connecting segment which is shown to extend orthogonally and laterally relative to a drain connecting segment. See Final Act. 8. Appellants do not point to evidence or credible evidence sufficient to identify reversible error in that finding. We sustain Rejection I as applied to claim 2. Claim 3 Claim 3 recites “an outer edge of said channel region of said second passgate transistor extends beyond an outer edge of said channel region of said second driver transistor by a distance greater than half said distance by which said end of said second drain connecting segment extends beyond said second gate connecting segment.” Appellants exemplify this recitation in Figure 1C of the Specification, reproduced below, where the distance 1074 is greater than half the distance 1090. 8 Appeal 2015-003283 Application 13/043,163 Figure 1C is a top view of a pair of cross-coupled inverters in an SRAM cell. Spec. 13. Appellants argue that the Examiner incorrectly relies on a distance measured from an inner edge of the channel region of the first driver transistor, rather than an outer edge as claimed. Br. 36. We agree. See Final Act. 8 (identifying a distance X measured from an outer edge of a channel region of a passgate transistor to an opposite inner edge of a channel region of a driver transistor). On this appeal record, we are persuaded that the Examiner failed to identify evidence sufficient to support a finding that Satomi meets the recitation set forth in claim 3. Accordingly, we do not sustain Rejection I as applied to claim 3. Claim 6 Although Appellants separately present arguments directed toward claim 6, those arguments reiterate the same arguments presented in connection with claim 1. Br. 37—45. We find these arguments unpersuasive 9 Appeal 2015-003283 Application 13/043,163 for the same reasons set forth above in connection with claim 1. Accordingly, Rejection I as applied to claim 6 also is sustained. Claim 7 Appellants also separately present arguments directed toward claim 7 that reiterate the same arguments presented in connection with claim 2. Br. 46-47. We find these arguments unpersuasive for the same reasons set forth above in connection with claim 2. Accordingly, Rejection I as applied to claim 7 also is sustained. Claim 8 Like claim 3, claim 8 also recites, “an outer edge of said channel region of said second passgate transistor extends beyond an outer edge of said channel region of said second driver transistor by a distance greater than half said distance by which said end of said second drain connecting segment extends beyond said second gate connecting segment.” Appellants present the same argument for claim 8 as are presented for claim 3. Br. 47— 50. For the reasons set forth above in connection with claim 3, we find this argument persuasive, and we do not sustain Rejection I as applied to claim 8. Rejection II Each of claims 4 and 9 requires, inter alia, that each T-shaped contact includes a gate connecting segment that is inclined a distance which is greater than half the distance by which the end of the drain connecting segment “extends beyond” the gate connecting segment. Claims 5 and 10 depend from claims 4 and 9, respectively. Thus, at a minimum, each of these claims requires that the gate connecting segment extends some distance beyond the drain connecting segment in each of the T-shaped 10 Appeal 2015-003283 Application 13/043,163 contacts. Consistent with that recitation, independent claims 1 and 6 also require that an end of each drain connecting segment “extends beyond an inner comer of an intersection” of the corresponding drain and gate connecting segments. The recitation of the first and second contacts being “T-shaped” in each of the independent claims also implies that the drain connecting segment extends at least some distance beyond the gate connecting segment. Acknowledging that Satomi fails to disclose an inclined gate connecting segment, the Examiner finds that one of ordinary skill would have had a reason to substitute Tsuboi’s inclined connector, represented by reference numerals 3a (the purported drain connecting segment) and 3b (the purported gate connecting segment) in Tsuboi’s Figure 1A. Final Act. 14— 15. We reproduce Tsuboi’s Figure 1A below. FIG,1A Figure 1A is a plane view of a semiconductor device. Tsuboi 114. Appellants argue, and we agree, that Tsuboi’s element 3a, the purported 11 Appeal 2015-003283 Application 13/043,163 drain connecting segment, does not extend beyond the inner intersection of element 3a with element 3b, the purported gate connecting segment. Br. 54, 61. The Examiner fails to articulate a reason why one of ordinary skill in the art would modify Tsuboi’s contact such that the drain connecting segment 3a would extend some distance beyond the inclined distance of the gate connecting segment 3b. Thus, the Examiner has not set forth a factual basis which is sufficient to support a prima facie case of obviousness over the cited prior art. For that reason, we do not sustain Rejection II. DECISION The Examiner’s decision rejecting claims 1, 2, 6, and 7 is affirmed. The Examiner’s decision rejecting claims 3—5 and 8—10 is reversed. No time period for taking any subsequent action in connection with this appeal may be extended under 37 C.F.R § 1.136(a). AFFIRMED-IN-PART 12