Ex Parte Hasunuma

Board of Patent Appeals and Interferences

Feb 25, 2008

10254669 (B.P.A.I. Feb. 25, 2008)

UNITED STATES PATENT AND TRADEMARK OFFICE ____________ BEFORE THE BOARD OF PATENT APPEALS AND INTERFERENCES ____________ Ex parte MASAHIKO HASUNUMA ____________ Appeal 2007-1426 Application 10/254,669 Technology Center 2800 ____________ Decided: February 25, 2008 ____________ Before KENNETH W. HAIRSTON, JOSEPH F. RUGGIERO, and ANITA PELLMAN GROSS, Administrative Patent Judges. GROSS, Administrative Patent Judge. DECISION ON APPEAL STATEMENT OF THE CASE Hasunuma (Appellant) appeals under 35 U.S.C. § 134 from the Examiner's Final Rejection of claims 1, 3 through 9, 11 through 15, and 22 through 28. Claim 10 is also pending, but has not been included in any of the rejections. We have jurisdiction under 35 U.S.C. § 6(b). Appellant's invention relates generally to a semiconductor device having a copper or silver interconnection portion with a tantalum alloy Appeal 2007-1426 Application 10/254,669 barrier film. See Spec. 3:8-4:18. Claim 1 is illustrative of the claimed invention, and it reads as follows: 1. A semiconductor device comprising: an insulating film disposed on or above a semiconductor substrate; and an interconnection portion disposed on the insulating film, the interconnection portion comprising: a low resistivity single-layer barrier film structure disposed on the insulating film, the barrier film structure being an alloy of a first material and Ta, the first material being at least one element selected from the group consisting of Nb, Mo, W, and Ti; and a conductive layer disposed on the barrier film structure, the conductive layer containing Cu or Ag as a major element. The prior art references of record relied upon by the Examiner in rejecting the appealed claims are: Dohjo US 5,170,244 Dec. 08, 1992 Cohen US 6,136,707 Oct. 24, 2000 Yamazaki US 6,144,082 Nov. 07, 2000 Gates US 6,603,204 B2 Aug. 05, 2003 Claims 1, 5, 6, 14, and 15 stand rejected under 35 U.S.C. § 102(e) as being anticipated by Gates. Claims 11 through 13 stand rejected under 35 U.S.C. § 102(e) as being anticipated by or, in the alternative, under 35 U.S.C. § 103 as being unpatentable over Gates. Claims 7 and 22 stand rejected under 35 U.S.C. § 103 as being unpatentable over Gates in view of Cohen. 2 Appeal 2007-1426 Application 10/254,669 Claims 3, 4, 23, 24, 27, and 28 stand rejected under 35 U.S.C. § 103 as being unpatentable over Gates in view of Dohjo. Claims 8, 9, 25, and 26 stand rejected under 35 U.S.C. § 103 as being unpatentable over Gates in view of Dohjo, Cohen, and Yamazaki. We refer to the Examiner's Answer (mailed April 12, 2006) and to Appellant's Brief (filed January 23, 2006) and Reply Brief (filed June 12, 2006) for the respective arguments. SUMMARY OF DECISION As a consequence of our review, we will affirm the anticipation rejection of claims 1, 5, 6, 14, and 15, the anticipation/obviousness rejection of claims 11 through 13, and the obviousness rejection of claims 7 and 22 and reverse the obviousness rejection of claims 3, 4, 8, 9, and 23 through 28. OPINION Independent claim 1 recites, in pertinent part, "the barrier film structure being an alloy of a first material and Ta, the first material being at least one element selected from the group consisting of Nb, Mo, W, and Ti" (emphasis added). The Examiner rejects claims 1, 5, 6, 14, and 15 as being anticipated by Gates. Gates discloses (col. 7, ll. 28-30 and 41-50) that a liner material (which everyone agrees corresponds to the claimed barrier film) is formed of "TiN, TaN, Ti, Ta, W, WN, Cr, Nb and other like materials including combinations thereof" (emphasis added). The Examiner asserts (Ans. 4 and 7) that Gates' disclosure of combinations of Ti, Ta, W, and Nb, among others, anticipates the claim limitation of an alloy of Ta and at least one of Nb, Mo, W, and Ti. Appellant, on the other hand, contends 3 Appeal 2007-1426 Application 10/254,669 (App. Br. 10-12 and Reply Br. 5-8) that an alloy is formed by combining metals in a particular manner and, therefore, is more than merely a combination of two or more metals, and that Gates distinguishes between a combination and an alloy by using different terms for different elements. The issue before us is whether Appellant has shown that the Examiner erred in considering Gates' disclosure of a combination of certain metals as satisfying the claim limitation of an alloy of the same metals. Appellant's distinction between Gates' use of the term "alloy" to describe the conductive layer and Gates' use of the term "combination" to describe the barrier film is not persuasive. The word "combination" is broader than the term "alloy" and clearly used to cover combinations of TaN and TiN, for example. Further, Appellant states (App. Br. 11-12) that "[o]ne of ordinary skill in the art would have recognized that a combination of 'liners' (col. 7, line 44) including a liner layer of the disclosed TiN and a liner layer of the disclosed W, for example, would not constitute an alloy." However, the referenced portion does not recite a combination of "liners" but, rather, recites "other like materials including combinations thereof" (emphasis added). Thus, Gates refers to a combination of materials, not of layers. In addition, Appellant's argument that "alloy" requires the metals be combined in a specific way is not convincing either. Appellant has presented no evidentiary support showing that the lack of a disclosure of a particular way of combining the metals means that the combination is not an alloy. Appellant has not even described what constitutes the "specific way" to form an alloy. The dictionary definition merely says a homogeneous mixture of metals, but does not indicate whether or not metals can be mixed 4 Appeal 2007-1426 Application 10/254,669 and not form an alloy. Accordingly, we will sustain the anticipation rejection of claims 1, 5, 6, 14, and 15. Regarding the rejection of claims 11 through 13, Appellant repeats the contention (Br. 12-13) that Gates fails to teach or suggest a barrier film made of a metal alloy. As indicated supra, we find that Gates does teach a metal alloy barrier film. Further, Appellant contends (Br. 13-14) that the Examiner has failed to provide a motivation for modifying Gates. However, Appellant has not indicated what element or elements have been improperly modified. Claims 11 through 13 each recite a product-by-process. In the absence of evidence to the contrary, such claims are considered anticipated by or at least obvious over the same product, regardless of the process by which it is made. Since Appellant has advanced no evidence that the claimed product differs from that of Gates, we will sustain the rejection of claims 11 through 13. The Examiner rejects claims 7 and 22 over Gates in view of Cohen. Appellant's sole contention (other than that Cohen fails to cure the alleged deficiency of Gates discussed supra) is that Cohen's barrier layer has a relatively large resistivity, which differs from Appellant's low resistivity barrier structure. See Brief, page 15. However, the Examiner (Ans. 5) relies on Cohen for a teaching to limit the thickness of a barrier layer to between 3 and 30 nanometer, not to replace Gates' barrier layer with that of Cohen. In any event, since Cohen uses the same materials for the barrier layer as Gates and Appellant, "relatively large resistivity" would appear to mean that the resistivity is large relative to that of the conductive layer. Thus, Cohen's barrier layer does not differ substantially from Appellant's. Further, Cohen discloses (col. 2, ll. 5-7) that barrier layers are "typically deposited to a 5 Appeal 2007-1426 Application 10/254,669 thickness of about 50 Å to about 500 Å." In light of the typical thickness being 5-50 nm, a barrier layer thickness of 3-30 nm would have been obvious to the skilled artisan. Accordingly, we will sustain the obviousness rejection of claims 7 and 22 over Gates in view of Cohen. Appellant contends (App. Br. 16) that the combination of Gates and Dohjo, as applied against claims 3, 4, 23, 24, 27, and 28, fails to address the limitations of independent claim 23. Although Appellant does not specify which limitations are not addressed, it is clear that Dohjo teaches using a Mo-Ta alloy, with particular amounts of Mo and Ta, whereas claim 23 recites an alloy of Ta and at least one of Nb, W, and Ti. The Examiner has not addressed this difference. Consequently, we cannot sustain the rejection of claim 23 and dependent claim 24 over Gates and Dohjo. As to claims 3, 4, 27, and 28, Appellant contends (App. Br. 16) that since Dohjo does not disclose using a Mo-Ta alloy as a barrier layer, Dohjo does not teach making a barrier layer of Mo-Ta alloy having a body-centered cubic crystal structure, the claimed resistivity, and the claimed Mo content, nor does it cure the alleged deficiencies of Gates. We agree. Although Dohjo discloses a Mo-Ta alloy with a particular crystal structure, resistivity, and Mo content, Dohjo discloses the alloy for a gate electrode or a gate electrode interconnection material. Nothing in Dohjo (or Gates) suggests that the same material would be useful as a barrier layer under a Cu or Ag conductive layer in an interconnection portion. Accordingly, we will reverse the rejection of claims 3, 4, 27, and 28 over Gates and Dohjo. Lastly, the Examiner rejects claims 8, 9, 25, and 26 over Gates, Dohjo, Cohen, and Yamazaki. The Examiner asserts (Ans. 6) that Gates and Dohjo "show most aspects of the instant invention … except for the barrier 6 Appeal 2007-1426 Application 10/254,669 film thickness range between 3 to 30 nm and comprising Ta-Nb." The Examiner continues that Cohen teaches the barrier layer thickness and Yamazaki teaches that "Ta-Nb is an equivalent structure known in the art." Although we agree that Cohen suggests the barrier layer thickness, we disagree that Dohjo and Yamazaki provide for a particular content of Nb, as recited in claims 8 and 9, or a particular content of Nb, W, or Ti for claims 25 and 26. Dohjo discloses a Mo-Ta layer with a particular content for a gate electrode or gate electrode interconnection material. Dohjo does not teach or suggest using such a material as a barrier layer under a Cu or Ag conductive layer. Further, although Yamazaki (col. 6, ll. 55-56) suggests the equivalence of Mo-Ta, Nb-Ta, W-Ta, and Ta, Ti, Mo, Nb, and W, there is no indication of the Nb or W content in such alloys. Therefore, even if we could substitute Nb-Ta or W-Ta for the Ta, Ti, W, or Nb disclosed by Gates, the only teaching of amounts to be used relates to Mo-Ta used as a gate electrode. Therefore, the combination of Gates, Dohjo, Cohen, and Yamazaki fails to disclose or suggest each and every limitation of claims 8, 9, 25, and 26. Consequently, we cannot sustain the obviousness rejection of claims 8, 9, 25, and 26 over Gates, Dohjo, Cohen, and Yamazaki. ORDER The decision of the Examiner rejecting claims 1, 3 through 9, 11 through 15, and 22 through 28 is affirmed as to claims 1, 5 through 7, 11 through 15, and 22 and reversed as to claims 3, 4, 8, 9, and 23 through 28. 7 Appeal 2007-1426 Application 10/254,669 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-IN-PART Tdl/gw FINNEGAN, HENDERSON, FARABOW, GARRETT & DUNNER LLP 901 NEW YORK AVENUE, NW WASHINGTON, DC 20001-4413 8