Inter Partes Review
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`United States Patent No. 6,538,324
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`
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`UNITED STATES PATENT AND TRADEMARK OFFICE
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`
`
`Taiwan Semiconductor Manufacturing Company Limited
`
`Petitioner
`
`v.
`
`Godo Kaisha IP Bridge 1
`
`Patent Owner
`
`
`
`IPR2016-01249
`
`
`
`PETITION FOR INTER PARTES REVIEW
`OF UNITED STATES PATENT NO. 6,538,324
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`
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`
`
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`
`

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`Inter Partes Review
`United States Patent No. 6,538,324
`TABLE OF CONTENTS
`
`I.
`
`PRELIMINARY STATEMENT ................................................................... 1
`
`II. THE ’324 PATENT ........................................................................................ 5
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`A. Overview of the ’324 Patent .................................................................. 5
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`B.
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`Prosecution History ............................................................................... 7
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`III. Level of Ordinary Skill ................................................................................10
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`IV. Claim Construction .....................................................................................11
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`V. CLAIMS 1-3, 5-7, AND 9 OF THE ’324 PATENT ARE
`UNPATENTABLE OVER THE PRIOR ART .........................................11
`
`A. Overview of the Prior Art ....................................................................11
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`1.
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`2.
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`Ding ...........................................................................................16
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`Zhang.........................................................................................16
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`B.
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`The combined teachings of Ding in view of Zhang render
`claims 1-3, 5-7, and 9 obvious ............................................................17
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`1.
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`2.
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`3.
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`4.
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`5.
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`6.
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`7.
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`Claim 1 ......................................................................................17
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`Claim 2 ......................................................................................38
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`Claim 3 ......................................................................................41
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`Claim 5 ......................................................................................42
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`Claim 6 ......................................................................................44
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`Claim 7 ......................................................................................44
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`Claim 9 ......................................................................................44
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`VI. MANDATORY NOTICES .........................................................................45
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`A.
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`Real Party-in-Interest ..........................................................................45
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`Inter Partes Review
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`United States Patent No. 6,538,324
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`B.
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`C.
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`D.
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`Related Matters ....................................................................................45
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`Lead and Back-Up Counsel .................................................................48
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`Service Information .............................................................................48
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`VII. CERTIFICATION UNDER 37 C.F.R. § 42.24(d) ....................................48
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`VIII. GROUNDS FOR STANDING ....................................................................49
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`IX. STATEMENT OF PRECISE RELIEF REQUESTED FOR
`EACH CLAIM CHALLENGED ...............................................................49
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`X. CONCLUSION ............................................................................................49
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`Inter Partes Review
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`United States Patent No. 6,538,324
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`TABLE OF AUTHORITIES
`
` Page(s)
`
`Case
`ClearValue, Inc. v. Pearl River Polymers, Inc.,
`668 F.3d 1340 (Fed. Cir. 2012) .......................................................................... 38
`
`In re Cronyn,
`890 F.2d 1158 (Fed. Cir. 1989) ...................................................................passim
`
`Cuozzo Speed Techs., LLC v. Lee,
`No. 15-446, slip op. (U.S. June 20, 2016) .......................................................... 11
`
`In re Hall,
`781 F.2d 897 (Fed. Cir. 1986) .....................................................................passim
`
`KSR Int’l Co. v. Teleflex Inc.,
`550 U.S. 398, 415-421(2007) ............................................................................. 23
`
`Titanium Metals Corp.v. Banner,
`778 F.2d 775 (Fed. Cir. 1985) ............................................................................ 41
`
`Statutes
`35 U.S.C. § 102 .................................................................................................passim
`
`35 U.S.C. § 103. ................................................................................................... 5, 49
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`Other Authorities
`
`37 C.F.R. § 42.100(b) .............................................................................................. 11
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`37 C.F.R. § 42.24 ..................................................................................................... 48
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`M.P.E.P. (Rev. 07.2015) § 2143 .............................................................................. 23
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`M.P.E.P. (Rev. 07.2015) § 2131.03 ......................................................................... 42
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`P.T.A.B. Case No. CBM2012-00003, Paper No. 7 (Oct. 25, 2012) ........................ 46
`
`
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`iii
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`
`
`Exhibit 1001:
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`Exhibit 1002:
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`Exhibit 1003:
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`Exhibit 1004:
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`Exhibit 1005:
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`Exhibit 1006:
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`Exhibit 1007:
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`Exhibit 1008:
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`Exhibit 1009:
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`Exhibit 1010:
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`Exhibit 1011:
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`Exhibit 1012:
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`Exhibit 1013:
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`Exhibit 1014:
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`Inter Partes Review
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`United States Patent No. 6,538,324
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`LIST OF EXHIBITS
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`U.S. Patent No. 6,538,324 to Tagami et al.
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`File History of U.S. Patent No. 6,538,324.
`
`Expert Declaration of Dr. Sanjay Kumar Banerjee.
`
`U.S. Patent No. 5,893,752 to Zhang et al.
`
`U.S. Patent No. 6,887,353 to Ding et al.
`
`Holloway et al., “Tantalum as a diffusion barrier between
`copper and silicon: Failure mechanism and effect of
`nitrogen additions,” Journal of Applied Physics, 71(11),
`5433-5444 (1992).
`
`Sun et al., “Properties of reactively sputter-deposited Ta-
`N thin films,” Thin Solid Films, 236 (1993) 347-351.
`
`U.S. Patent No. 5,858,873 to Vitkavage et al.
`
`U.S. Patent No. 5,668,411 to Hong et al.
`
`Excerpt of El-Kareh, “Fundamentals of Semiconductor
`Processing Technologies,” Kluwer Academic Publishers
`(1995).
`
`Declaration of Dr. Li Jiang.
`
`Library of Congress Catalog Record of Holloway et al.,
`“Tantalum as a diffusion barrier between copper and
`silicon: Failure mechanism and effect of nitrogen
`additions,” Journal of Applied Physics, 71(11), 5433-
`5444 (1992).
`
`Library of Congress Catalog Record of Sun et al.,
`“Properties of reactively sputter-deposited Ta-N thin
`films,” Thin Solid Films, 236 (1993) 347-351.
`
`Library of Congress Catalog Record of El-Kareh,
`“Fundamentals of Semiconductor Processing
`Technologies,” Kluwer Academic Publishers (1995).
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`iv
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`Exhibit 1015:
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`Exhibit 1016:
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`Exhibit 1017:
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`Exhibit 1018:
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`Exhibit 1019:
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`Exhibit 1020:
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`Exhibit 1021:
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`Exhibit 1022:
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`Inter Partes Review
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`United States Patent No. 6,538,324
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`Stavrev et al., “Crystallographic and morphological
`characterization of reactively sputtered Ta, Ta-N and Ta-
`N-O thin films,” Thin Solid Films, 307 (1997) 79-88.
`
`Library of Congress Catalog Record of Stavrev et al.,
`“Crystallographic and morphological characterization of
`reactively sputtered Ta, Ta-N and Ta-N-O thin films,”
`Thin Solid Films, 307 (1997) 79-88.
`
`Duan et al., “Magnetic Property and Microstructure
`Dependence of CoCrTa/Cr Media on Substrate
`Temperature and Bias,” IEEE Transactions on Magnetics,
`Vol. 28, No. 5, September 1992.
`
`Library of Congress Catalog Record of Duan et al.,
`“Magnetic Property and Microstructure Dependence of
`CoCrTa/Cr Media on Substrate Temperature and Bias,”
`IEEE Transactions on Magnetics, Vol. 28, No. 5,
`September 1992.
`
`Moussavi et al., “Comparison of Barrier Materials and
`Deposition Processes for Copper Integration,”
`Proceedings of the IEEE 1998 International Interconnect
`Technology Conference, pp. 295-97 (1998).
`
`Library of Congress Catalog Record of Moussavi et al.,
`“Comparison of Barrier Materials and Deposition
`Processes for Copper Integration,” Proceedings of the
`IEEE 1998 International Interconnect Technology
`Conference, pp. 295-97 (1998).
`
`Wijekoon et al., “Development of a Production Worthy
`Copper CMP Process,” 1998 IEEE/SEMI Advanced
`Semiconductor Manufacturing Conference, pp. 354-63
`(1998).
`
`Library of Congress Catalog Record of Wijekoon et al.,
`“Development of a Production Worthy Copper CMP
`Process,” 1998 IEEE/SEMI Advanced Semiconductor
`Manufacturing Conference, pp. 354-63 (1998).
`
`v
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`Inter Partes Review
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`United States Patent No. 6,538,324
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`Wang et al., “Barrier Properties of Very Thin Ta and
`TaN layers Against Copper Diffusion,” J. Electrochem.
`Soc., Vol. 145, No. 7, pp. 2538-45.
`
`Library of Congress Catalog Record of Wang et al.,
`“Barrier Properties of Very Thin Ta and TaN layers
`Against Copper Diffusion,” J. Electrochem. Soc., Vol.
`145, No. 7, pp. 2538-45.
`
`
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`Exhibit 1023:
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`Exhibit 1024:
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`vi
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`I.
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`PRELIMINARY STATEMENT
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`Inter Partes Review
`United States Patent No. 6,538,324
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`U.S. Patent No. 6,538,324 (Ex. 1001) “relates to a semiconductor integrated
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`circuit including a copper wiring layer.” Ex. 1001, 1:8-9. Semiconductor devices,
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`such as transistors, are typically formed using layers of material deposited on a
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`semiconductor substrate, such as silicon. Once formed, the semiconductor devices
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`comprise electrical terminals that are interconnected by one or more metal wiring
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`layers to form specific integrated circuitry, for example, in a processor. A metal
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`wiring layer is often deposited over an interlayer insulating layer, such as silicon
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`dioxide, which separates the metal wiring layer from underlying layers of the
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`semiconductor devices (such as MOSFET transistors). See, e.g., Ex. 1003, ¶ 39.
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`At the time the application leading to the ’324 patent was filed, it was
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`understood that copper was a desirable metal for the wiring layer as devices
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`became smaller because copper provides lower electrical resistivity than aluminum.
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`Ex. 1001, 1:13-19; see also Ex. 1003, ¶ 40. But it was also known that “it is
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`absolutely necessary for a semiconductor device having a copper wiring layer to
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`have a diffusion-barrier film for preventing diffusion of copper into an interlayer
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`insulating film formed between copper wiring layers.” Ex. 1001, 1:26-30.
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`Diffusion occurs when atoms or molecules migrate from an area of higher
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`concentration into an area of lower concentration. Ex. 1003, ¶ 40. At the time of
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`the ’324 patent, there was a recognized need in the art for a diffusion barrier that
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`United States Patent No. 6,538,324
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`would block the movement of copper from a wiring layer with a high concentration
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`of copper into an underlying insulating layer and semiconductor devices. See, e.g.,
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`id.; Ex. 1001, 1:22-25 (explaining that copper has a high diffusion rate in silicon
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`and silicon dioxide, and if copper were to diffuse into a MOSFET formed on a
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`silicon substrate, it would induce a reduction in carrier lifetime in such a device).
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`The ’324 patent specification admits it was known that the diffusion barrier
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`not only must prevent copper from diffusing out of the wiring layer into underlying
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`layers and devices, but also must provide good adhesion to the copper wiring layer.
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`Id., 2:13-15 (“As will be obvious to those skilled in the art, the diffusion-barrier
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`film is required to have high coverage as well as capability of preventing copper
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`diffusion and adhesion to copper.”); see also id., 1:30-33.
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`The specification acknowledges the existence of several prior-art barrier
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`films for preventing diffusion of copper at the time of the alleged invention. Id.,
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`2:21-54, 7:52-57, FIGS. 1-3. In FIG. 1, the ’324 patent recognizes that two-layer
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`diffusion barrier structures were known in the art. Id., 7:51-52. With reference to
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`FIG. 2, the patent explains it was also known in the prior art that a diffusion barrier
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`containing a crystalline film could provide good adhesion to a copper wiring layer,
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`although it exhibited a “low barrier characteristic of preventing copper diffusion.”
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`Id., 3:1-4, 3:14-19. FIG. 3 of the ’324 patent shows it was known in the prior art
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`United States Patent No. 6,538,324
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`that amorphous (non-crystalline) films provide a good barrier to copper diffusion,
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`but they do not adhere well to copper. Id., 3:21-33; FIG. 3.
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`Because of this knowledge in the art, many in the field had already made
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`two-layer diffusion barriers that combined the advantages of a crystalline layer for
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`its known characteristics of providing good adhesion to copper and an amorphous
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`layer for its known property of preventing copper diffusion into underlying layers
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`and semiconductor devices, e.g., incorporating the prior-art films in FIGS. 2 and 3
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`into the barrier structure in FIG. 1. And more particularly, others had already made
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`two-layer diffusion barriers using a crystalline layer for providing good adhesion to
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`copper and an amorphous layer for preventing copper diffusion. Exactly like the
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`claims of the ’324 patent, the prior art included such two-layer diffusion barriers
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`with tantalum nitride (TaNx) as the amorphous layer and a tantalum (Ta) metal
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`containing nitrogen as the crystalline layer.
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`• U.S. Patent No. 6,887,353 (“Ding,” Ex. 1005) teaches a two-layer
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`diffusion barrier having an amorphous TaNx layer on the bottom for
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`providing a barrier to copper diffusion and a crystalline tantalum layer
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`overlying the TaNx layer to provide good adherence to a copper
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`wiring layer. Ex. 1005, Abstract, 3:33-38, 7:66-8:4.
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`• U.S. Patent No. 5,893,752 (“Zhang,” Ex. 1004), directed to the same
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`problems as the ’324 patent and Ding, teaches a diffusion barrier with
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`a bottom TaNx layer for preventing copper diffusion and a top
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`“tantalum-rich nitride film” that provides good adherence to copper.
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`Ex. 1004, Abstract, 2:29-40, 3:22-67, 5:49-59, FIG. 8 (multi-layer
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`diffusion barrier 22 and 32, copper wiring layer 54 and 64)1, FIG. 4.
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`The purported invention in the ’324 patent is a two-layer diffusion barrier to
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`prevent copper diffusion and provide good adhesion to a copper wiring layer.2 The
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`bottom layer in the barrier is an amorphous metal nitride to prevent copper
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`diffusion. See, e.g., id., Abstract, 9:50-52, 18:22-24. The top layer is a crystalline
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`metal that contains nitrogen to provide good adhesion to a copper wiring layer.
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`See, e.g., id., Abstract, 9:49-50, 18:24-26. The claims require the crystalline layer
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`of the diffusion barrier to contain less nitrogen than the amorphous layer. Id., 19:2-
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`3. The claimed two-layer diffusion barrier, combining known crystalline and
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`amorphous barrier layers, was not new and non-obvious at the time of the alleged
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`1 Zhang teaches the copper seed film 54 and copper wiring film 64 may be
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`replaced with a single copper film. Ex. 1004, 5:35-38.
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`2 The ’324 patent’s specification and claims refer to a barrier “film” (i.e., thin film)
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`having a multi-layered structure of first and second films. In this context, the words
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`“layer” and “film” are used interchangeably. Ex. 1003, ¶ 42.
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`invention. Several prior art references, such as Ding and Zhang, taught the same
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`two-layer barrier structure.
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`Because the combination of Ding and Zhang renders obvious each of claims
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`1-3, 5-7, and 9 in the ’324 patent under 35 U.S.C. § 103, Petitioner respectfully
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`requests cancellation of these claims.
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`II. THE ’324 PATENT
`A. Overview of the ’324 Patent
`The face of the ’324 patent indicates it was filed on June 19, 2000, issued on
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`March 25, 2003, and claims foreign priority to Japanese application 11-214110
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`filed on June 24, 1999. The patent contains claims 1-10, of which claims 1 and 5
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`are independent. Claim 1 and its dependent claims 2-4 recite a barrier film
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`preventing diffusion of copper from a copper wiring layer formed on a
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`semiconductor substrate. Claim 5 and its dependent claims 6-10 recite a multi-
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`layered wiring structure comprising the barrier film in claim 1. Although the
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`specification describes specific steps for manufacturing the claimed multi-layered
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`wiring structure and barrier film, the claims are directed only to the structure and
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`barrier film, not to any manufacturing method.
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`Claim 1 reads as follows:
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`[1.0] A barrier film preventing diffusion of copper from a copper wiring
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`layer formed on a semiconductor substrate, comprising a multi-layered structure of
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`first and second films:
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`[1.1] said first film being composed of crystalline metal containing nitrogen
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`therein,
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`[1.2] said second film being composed of amorphous metal nitride,
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`[1.3] said barrier film being constituted of common metal atomic species,
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`[1.4] said first film being formed on said second film,
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`[1.5] said first film in direct contact with said second film,
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`[1.6] said first film containing nitrogen in a smaller content than that of said
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`second film.
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`Claim 5 is substantially similar to claim 1. It reads:
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`[5.0] A multi-layered wiring structure comprising a barrier film which
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`prevents diffusion of copper from a copper wiring layer formed on a
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`semiconductor substrate,
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`[5.1] said barrier film having a multi-layered structure of first and second
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`films,
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`[5.2] said first film being composed of crystalline metal containing nitrogen
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`therein,
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`[5.3] said second film being composed of amorphous metal nitride,
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`United States Patent No. 6,538,324
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`[5.4] said barrier film being constituted of common metal atomic species,
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`[5.5] said first film being formed on said second film,
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`[5.6] said first film in direct contact with said second film,
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`[5.7] said first film containing nitrogen in a smaller content than that of said
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`second film.
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`Claim elements [5.2]-[5.7] of claim 5 are identical to the claim elements
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`[1.1]-[1.6] of claim 1.
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`During prosecution, the PTO correctly explained that a device covered by
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`claim 1 “could be made by processes materially different from those” of the
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`specific method described in the specification. Ex. 1002 (’324 patent file history)
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`at 202; Ex. 1003, ¶ 56 (Dr. Banerjee agreeing with PTO). The Applicant did not
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`disagree.
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`Prosecution History
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`B.
`The original application for the ’324 patent included claims 1-36. Claims
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`1-10 were directed to either a diffusion barrier film or a structure comprising the
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`diffusion barrier film, and claims 11-36 were directed to methods of forming either
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`the diffusion barrier film or a structure comprising the diffusion barrier film.
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`In an initial Office Action, the PTO restricted the claims into two distinct
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`groups and required election of one of the groups for examination. Group I
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`contained claims 1-10 “drawn to a semiconductor device,” and Group II contained
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`United States Patent No. 6,538,324
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`claims 11-36 “drawn to a method of making a semiconductor device.” Ex. 1002 at
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`202. The Applicant chose to prosecute Group I, claims 1-10, and withdrew all of
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`the method claims (claims 11-36) from consideration. Id. at 207.
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`The PTO issued a non-final rejection of claims 1-10 as anticipated or
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`rendered obvious by U.S. Patent No. 5,858,873 (“Vitkavage,” Ex. 1008). Id. at
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`210-12. In response, the Applicant amended the independent claims to recite “said
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`first film being formed on said second film” ([1.4] and [5.5]) and “said first film
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`containing nitrogen in a smaller content than that of said second film” ([1.6] and
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`[5.7]), seeking to distinguish the claims over Vitkavage because of these added
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`limitations. Id. at 219-23. The Applicant also added two new claims, corresponding
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`to claims 4 and 10 in the ’324 patent.
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`The PTO issued a final rejection finding the amended claims anticipated by
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`U.S. Patent No. 5,668,411 (“Hong,” Ex. 1009). The Applicant tried (Ex. 1002 at
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`231-36), but failed (id. at 237-39), to distinguish the claims over Hong, and
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`eventually filed a Request for Continued Examination. Id. at 240-41.
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`Along with the RCE, the Applicant further amended the independent claims
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`to recite “said first film in direct contact with said second film” ([1.5] and [5.6]).
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`Id. at 247-49. With the amendment, the Applicant distinguished Hong because it
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`lacked a top layer (“first film”) in direct contact with a bottom layer (“second
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`film”), whereas Hong disclosed “a seed layer 46 of the diffusion barrier film
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`positioned between the top layer 48 and the bottom layer 44.” Id. at 245. The PTO
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`allowed the claims in the next Office Action. Id. at 252-61.
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`During prosecution, the Examiner did not consider prior art that disclosed
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`the same claim elements he believed were missing from the art of record. For
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`example, the Applicant distinguished Vitkavage by arguing that Vitkavage does not
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`disclose “said first film being formed on said second film” ([1 -4] and [5_5]) and
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`“said first film containing nitrogen in a smaller content than that of said second
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`1” ([1 .6] and [5.7]). These elements are disclosed in Ding, as shown in the
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`armotated FIG. 2 of Ding below, which teaches a two-layer diffusion barrier
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`structure with a top tantalum layer (in blue) overlying a bottom tantalum nitride
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`layer (in red). See, e.g., Ex. 1005, 3:33-34 (“a layer of Ta overlying a layer of
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`TaNx”), 7:1-29, Abstract, 4:66-5:1 (“The TaNx/Ta barrier layer structure”), FIG. 2.
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`/ A
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`nnotated FIG. 2 ofDing (Ex. 1005)
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`ma at Cu mu on nu,/Ia Substrate
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`United States Patent No. 6,538,324
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`In Ding, “[t]o form the TaNx/Ta barrier layer structure, a tantalum target
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`cathode 110 was used,” where “[d]uring the formation of the TaNx first layer, . . .
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`[n]itrogen gas was also fed into vacuum chamber 117” and “[s]ubsequent to
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`application of the TaN layer, the nitrogen gas was shut off” to form “a . . . layer of
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`tantalum . . . over the TaN layer.” Ex. 1005, 6:64-7:28.
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`Further, the claims were allowed after Applicant argued that Hong does not
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`disclose “said first film in direct contact with said second film” ([1.5] and [5.6]),
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`but the prior art discloses this claim element as well, such as in Ding, which was
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`not before the Examiner during prosecution. See, e.g., id., 3:33-34 (“We have
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`developed a barrier layer structure comprising a layer of Ta overlying a layer of
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`TaNx”), 7:21-29 (describing the formation of the second layer directly on the first
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`layer, whereby “[s]ubsequent to application of the TaN layer, the nitrogen gas was
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`shut off” to form the Ta layer), 4:66-5:1 (“TaNx/Ta barrier layer structure”), FIG. 2
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`(annotated above).
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`III. Level of Ordinary Skill
`A person of ordinary skill in the art (“POSITA”) at the time the application
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`leading to the ’324 patent was filed would have an equivalent of a Master of
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`Science degree from an accredited institution in electrical engineering, materials
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`science, or physics, or the equivalent, a working knowledge of semiconductor
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`processing technologies for integrated circuits, and at least two years of experience
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`in semiconductor processing analysis, design, and development. Ex. 1003, ¶ 64.
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`Additional graduate education could substitute for professional experience, and
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`significant work experience could substitute for formal education. Id.
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`IV. Claim Construction
`A claim in an unexpired patent subject to inter partes review receives the
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`“broadest reasonable construction in light of the specification of the patent in
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`which it appears.” 37 C.F.R. § 42.100(b); see also Cuozzo Speed Techs., LLC v.
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`Lee, No. 15-446, slip op. (U.S. June 20, 2016). The broadest reasonable
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`construction should be applied to all claim terms in the ’324 patent.
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`V. CLAIMS 1-3, 5-7, AND 9 OF THE ’324 PATENT ARE
`UNPATENTABLE OVER THE PRIOR ART
`A. Overview of the Prior Art
`The ’324 patent admits the inventors were not the first to recognize
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`problems associated with single-layer barriers for preventing diffusion of copper
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`and suggest a multi-layer solution. The specification recognized a desire for a
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`diffusion barrier “having a high barrier characteristic of preventing copper
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`diffusion and high adhesion to copper.” Ex. 1001, 3:47-49; see also 2:12-15. The
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`specification also acknowledges that a barrier layer formed only of a crystalline
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`metal film, such as a crystalline β-Ta (002) film, was known to provide “good
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`adhesion” and “rich crystal orientation” (e.g., allowing a copper film to grow with
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`good adhesion), but would serve as a poor barrier to copper diffusion. Id., 3:14-20;
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`United States Patent No. 6,538,324
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`see also, Ex. 1003, ¶ 67. On the other hand, a diffusion barrier formed only of an
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`amorphous metal nitride would provide a better barrier to copper diffusion since it
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`“does not have the [grain-boundary] paths through which copper is diffused,” but
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`would suffer from poor adhesion because “copper crystallinity and adhesion to
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`copper are degraded” using an amorphous layer. Ex. 1001, 3:21-33; see also, Ex.
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`1003, ¶ 67.
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`The ’324 patent claims a two-layer diffusion barrier comprising overlying
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`crystalline and amorphous films having different nitrogen contents. See, e.g., Ex.
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`1001, claims 1 and 5. In this multi-layer structure, the bottom film of the barrier
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`(substrate side) may be a prior-art amorphous metal nitride film, such as tantalum
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`nitride, and the top film (copper side) may be a prior-art crystalline metal film
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`containing less nitrogen than the bottom film. As discussed below, both the
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`problems with known diffusion barriers and the solution described in the ’324
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`patent were already known in the art, including in Ding and Zhang.
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`Like the ’324 patent, Ding discloses a two-layer “TaNx/Ta barrier structure”
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`that “provides both a barrier to the diffusion of a copper layer deposited thereover,
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`and enables the formation of a copper layer having a high <111> crystallographic
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`content so that the electromigration resistance of the copper is increased.” Ex.
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`1005, Abstract.3 The diffusion barrier in Ding may consist of an amorphous
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`tantalum nitride bottom film for preventing copper diffusion (Ex. 1005, Abstract),
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`and a crystalline tantalum top film for “easy wetting of the tantalum surface by the
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`copper” (thus providing good adhesion to the copper layer) and “depositing of a
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`copper layer having a high <111> crystal orientation” (Ex. 1005, 8:1-4). See also
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`Ex. 1003, ¶ 72.
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`Ding meets every claim element of the ’324 patent, except it does not
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`expressly mention whether its crystalline tantalum film for the top film of the
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`barrier contains “nitrogen therein” as required by the first film in claim 1.
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`3 <111> are indices representing a set of equivalent directions in a crystalline
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`material. Ex. 1003, ¶ 51; see also Ex. 1010 at 11-12, which is a technical
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`publication that was catalogued and available to the public in the Library of
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`Congress in 1994. Ex. 1010 at 2 (showing Library of Congress stamp dated
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`December 21, 1994); Ex. 1014 (catalogue entry); Ex. 1011 at ¶ 5 (linking Ex. 1010
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`to Ex. 1014). Papers catalogued and available to the public in libraries, including
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`the Library of Congress, are sufficiently “publicly accessible” to serve as prior art.
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`See, e.g., In re Hall, 781 F.2d 897 (Fed. Cir. 1986); In re Cronyn, 890 F.2d 1158,
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`1161 (Fed. Cir. 1989). Accordingly, Exhibit 1010 qualified as prior art at least one
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`year before the earliest priority date of the ’324 patent.
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`United States Patent No. 6,538,324
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`Zhang discloses a two-layer diffusion barrier film for copper having top and
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`bottom films 32 and 22, with the bottom film 22 lying closer to the substrate than
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`the top film 32. Ex. 1004, Abstract. According to Zhang, a “combination of
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`portions (22 and 32) within the first conductive film provides a good diffusion
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`barrier (first portion) and has good adhesion (second portion) with the second
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`conductive film (54 and 64).” Id.4 Zhang further teaches the top (32) and bottom
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`(22) films are tantalum-based films with different nitrogen contents. Id., 3:22-23.
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`The “nitrogen percentage for the second portion (32) is lower than the nitrogen
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`atomic percentage for the first portion (22).” Id., Abstract.
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`Zhang discloses an embodiment in which the top film of the two-layer
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`diffusion barrier (the copper side) is a “tantalum-rich tantalum nitride film” that
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`has an upper surface which is “substantially pure tantalum.” Id., 3:54-57.5 The top
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`film of the barrier in Ding (the copper side) is also a tantalum layer, which Ding
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`teaches is a crystalline film with a <002> crystalline orientation. Ex. 1005, 8:1-4.
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`4 Zhang refers to the same thin films 22 and 32 as either “portions” or “films.” See,
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`e.g., Ex. 1004, Abstract (“portions (22 and 32)”), 3:37 (“films 22 and 32”).
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`5 FIG. 4 in Zhang illustrates the atomic percentage of nitrogen in the top film 32 as
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`a function of distance from its exposed surface. Ex. 1004, 3:50-53, FIG. 4.
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`United States Patent No. 6,538,324
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`A POSITA reading Ding at the time of the ’324 patent’s effective filing date
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`would have understood that the top tantalum film in Ding could contain a small
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`percentage of nitrogen therein and still provide a “substantially pure tantalum”
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`surface to deposit copper as taught in Zhang. Ex. 1003, ¶ 74. Indeed, the sputtering
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`process described in Ding suggests the top tantalum film would contain at least a
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`small amount of nitrogen, e.g., from residual nitrogen in the vacuum chamber after
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`the nitrogen feed gas was turned off following the deposition of the bottom
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`tantalum nitride (TaNx) film. Id.
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`The POSITA also would have found it obvious to modify the top tantalum
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`film in Ding to purposely add a small content of nitrogen therein, as taught in
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`Zhang, because adding nitrogen to the tantalum film would provide well known
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`benefits to the diffusion barrier, including better polishing characteristics, lower
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`resistivity, and more effective blocking of copper diffusion for Ding’s diffusion-
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`barrier structure. Id., ¶¶ 74, 139; see Section V.B.1.b infra. Claims 1-3, 5-7, and 9
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`would have been obvious to the POSITA because modifying the top tantalum film
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`in Ding to include nitrogen in view of Zhang would result in a two-layer barrier
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`structure satisfying each of these claims.
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`United States Patent No. 6,538,324
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`Ding
`1.
`U.S. Patent No. 6,887,353 to Ding et al. was filed on December 19, 1997,
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`issued on May 3, 2005, and qualifies as prior art to the ’324 patent under pre-AIA
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`35 U.S.C. § 102(e). Ding was not considered or relied on by the Patent Office.
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`Ding discloses a TaNx/Ta barrier layer structure that prevents the diffusion
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`of copper in semiconductor devices. Ex. 1005, Abstract. The inventors in Ding
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`explained,
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`“We have discovered that tantalum nitride (TaNx) is a better barrier
`layer for copper than tantalum . . . We have developed a barrier layer
`structure comprising a layer of Ta overlying a layer of TaNx which
`provides both a barrier to the diffusion of a copper layer deposited
`thereover, and enables the formation of a copper layer having a high
`<111> crystallographic content, so that copper electromigration
`resistance is increased.”
`
`Ex. 1005, 3:28-38.
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`Ding teaches that the top film of the diffusion barrier is crystalline Ta (id at
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`8:2 “crystalline orientation”), while the bottom film is amorphous TaNx (id at 3:39
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`“amorphous”).
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`Zhang
`2.
`U.S. Patent No. 5,893,752 to Zhang et al. was filed on December 22, 1997,
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`issued on April 13, 1999, and qualifies as prior art to the ’324 patent under pre-AIA
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`United States Patent No. 6,538,324
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`35 U.S.C. §§ 102(a), (b), and (e). Zhang was not considered or relied on by the
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`Patent Office.
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`Zhang teaches