Inter Partes Review
`United States Patent No. 6,538,324
`UNITED STATES PATENT AND TRADEMARK OFFICE
`_______________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`
`_______________
`
`GlobalFoundries U.S. Inc.
`
`Petitioner
`
`v.
`
`Godo Kaisha IP Bridge 1
`
`Patent Owner
`
`CASE IPR: IPR2017-00920
`
`PETITION FOR INTER PARTES REVIEW
`OF UNITED STATES PATENT NO. 6,538,324
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`Table of Contents
`
`Inter Partes Review
`United States Patent No. 6,538,324
`
`I.
`
`II.
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`
`
`B.
`
`PRELIMINARY STATEMENT ......................................................................................1
`THE ‘324 PATENT............................................................................................................4
`A.
`Overview of the ‘324 Patent ....................................................................................4
`B.
`Prosecution History ..................................................................................................6
` Level of Ordinary Skill ......................................................................................................8 III.
`
` Claim Construction ............................................................................................................9
`IV.
`CLAIMS 1-3, 5-7, AND 9 OF THE ‘324 PATENT ARE UNPATENTABLE
`V.
`
`OVER THE PRIOR ART .................................................................................................9
`A.
`Overview of the Prior Art ........................................................................................9
`1.
`Zhang ........................................................................................................ 13
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`Ding........................................................................................................... 13
`2.
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`Sun ............................................................................................................ 14
`3.
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`The combined teachings of Zhang in view of Ding render claims 1-3, 5-7,
`and 9 obvious .........................................................................................................14
`1.
`Claim 1 ...................................................................................................... 14
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`Claim 2 ...................................................................................................... 30
`2.
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`Claim 3 ...................................................................................................... 32
`3.
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`Claim 5 ...................................................................................................... 34
`4.
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`Claim 6 ...................................................................................................... 35
`5.
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`Claim 7 ...................................................................................................... 35
`6.
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`Claim 9 ...................................................................................................... 36
`7.
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`The combined teachings of Zhang and Ding further in view of Sun render
`claims 1-3, 5-7, and 9 obvious ...............................................................................37
` MANDATORY NOTICES ..............................................................................................40
`A.
`Real Party-in-Interest .............................................................................................40
`B.
`Related Matters ......................................................................................................40
`C.
`Lead and Back-Up Counsel ...................................................................................42
`D.
`Service Information ...............................................................................................42
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`C.
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`VI.
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`Inter Partes Review
`United States Patent No. 6,538,324
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`
` CERTIFICATION UNDER 37 C.F.R. § 42.24(d).........................................................42 VII.
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` GROUNDS FOR STANDING ........................................................................................43
`VIII.
`STATEMENT OF PRECISE RELIEF REQUESTED FOR EACH CLAIM
`IX.
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`CHALLENGED ...............................................................................................................43
`CONCLUSION ................................................................................................................43
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`X.
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`ii
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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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`Exhibit 1015:
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`Exhibit 1016:
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`Inter Partes Review
`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.
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`Expert Declaration of Dr. Sanjay Kumar Banerjee.
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`U.S. Patent No. 5,893,752 to Zhang et al.
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`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.
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`U.S. Patent No. 5,668,411 to Hong et al.
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`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).
`
`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
`
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`iii
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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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`Exhibit 1023:
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`Exhibit 1024:
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`Inter Partes Review
`United States Patent No. 6,538,324
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`(1997) 79-88.
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`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).
`
`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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`PRELIMINARY STATEMENT
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`
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`I.
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`
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`U.S. Patent No. 6,538,324 (Ex. 1001) “relates to a semiconductor integrated circuit
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`including a copper wiring layer.” Ex. 1001, 1:8-9. Semiconductor devices, such as transistors,
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`are typically formed using layers of material deposited on a semiconductor substrate, such as
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`silicon. Once formed, the semiconductor devices comprise electrical terminals that are
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`interconnected by one or more metal wiring layers to form specific integrated circuitry, for
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`example, in a processor. A metal wiring layer is often deposited over an interlayer insulating
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`layer, such as silicon dioxide, which separates the metal wiring layer from underlying layers of
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`the 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 understood that
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`copper was a desirable metal for the wiring layer as devices became smaller because copper
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`provides lower electrical resistivity than aluminum. Ex. 1001, 1:13-19; see also Ex. 1003, ¶ 40.
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`But it was also known that “it is absolutely necessary for a semiconductor device having a
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`copper wiring layer to have a diffusion-barrier film for preventing diffusion of copper into an
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`interlayer insulating film formed between copper wiring layers.” Ex. 1001, 1:26-30. Diffusion
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`occurs when atoms or molecules migrate from an area of higher concentration into an area of
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`lower concentration. Ex. 1003, ¶ 40. At the time of the ‘324 patent, there was a recognized need
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`in the art for a diffusion barrier that would block the movement of copper from a wiring layer
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`with a high concentration of copper into an underlying insulating layer and semiconductor
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`devices. See, e.g., id.; Ex. 1001, 1:22-25 (explaining that copper has a high diffusion rate in
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`silicon and silicon dioxide, and if copper were to diffuse into a MOSFET formed on a silicon
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`substrate, it would induce a reduction in carrier lifetime in such a device).
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`Inter Partes Review
`United States Patent No. 6,538,324
`The ‘324 patent specification admits it was known that the diffusion barrier not only must
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`prevent copper from diffusing out of the wiring layer into underlying layers and devices, but also
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`must provide good adhesion to the copper wiring layer. Id., 2:13-15 (“As will be obvious to
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`those skilled in the art, the diffusion-barrier film is required to have high coverage as well as
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`capability of preventing copper 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 films for
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`preventing diffusion of copper at the time of the alleged invention. Id., 2:21-54, 7:52-57, FIGS.
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`1-3. In FIG. 1, the ‘324 patent recognizes that two-layer diffusion barrier structures were known
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`in the art. Id., 7:51-52. With reference to FIG. 2, the patent explains it was also known in the
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`prior art that a diffusion barrier containing a crystalline film could provide good adhesion to a
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`copper wiring layer, although it exhibited a “low barrier characteristic of preventing copper
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`diffusion.” Id., 3:1-4, 3:14-19. FIG. 3 of the ‘324 patent shows it was known in the prior art that
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`amorphous (non-crystalline) films provide a good barrier to copper diffusion, but they do not
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`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 two-layer
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`diffusion barriers that combined the advantages of a crystalline layer for its known
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`characteristics of providing good adhesion to copper and an amorphous layer for its known
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`property of preventing copper diffusion into underlying layers and semiconductor devices, e.g.,
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`incorporating the prior-art films in FIGS. 2 and 3 into the barrier structure in FIG. 1. And more
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`particularly, others had already made two-layer diffusion barriers using a crystalline layer for
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`providing good adhesion to copper and an amorphous layer for preventing copper diffusion.
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`Exactly like the claims of the ‘324 patent, the prior art included such two-layer diffusion barriers
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`Inter Partes Review
`United States Patent No. 6,538,324
`with tantalum nitride (TaNx) as the amorphous layer and a tantalum (Ta) metal containing
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`nitrogen as the crystalline layer.
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`•
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`U.S. Patent No. 5,893,752 (“Zhang,” Ex. 1004) discloses a two-layer
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`diffusion barrier having a bottom TaNx layer for preventing copper
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`diffusion and a top “tantalum-rich nitride film [that] is substantially pure
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`tantalum” for providing good adherence to a copper wiring layer. Ex.
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`1004, Abstract, 2:29-40, 3:22-67, 5:49-59, FIG. 8 (multi-layer diffusion
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`barrier 22 and 32, copper wiring layer 54 and 64)1, FIG. 4.
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`•
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`•
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`U.S. Patent No. 6,887,353 (“Ding,” Ex. 1005), directed to the same
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`problem as the ‘324 patent and Zhang, teaches that the TaNx layer in
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`Zhang would be an amorphous layer and the adjacent layer of the
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`tantalum-rich tantalum nitride film would be crystalline. Ex. 1005,
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`Abstract, 3:33-38, 7:66-8:4.
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`Other prior art also discusses properties of Ta-based diffusion barriers at
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`different nitrogen contents for preventing copper diffusion. Sun et al.,
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`“Properties of reactively sputter-deposited Ta-N thin films,” Thin Solid
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`Films, vol. 236, nos. 1-2, pages 347-351 (1993) (“Sun,” Ex. 1007)
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`discloses that “In substantial atomic concentrations, nitrogen can also
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`promote the formation of amorphous metallic alloys with most early
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`transition metals,” such as Ta, and the resulting amorphous films exhibit
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`1 Zhang teaches the copper seed film 54 and copper wiring film 64 may be replaced with a single
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`copper film. Ex. 1004, 5:35-38.
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`Inter Partes Review
`United States Patent No. 6,538,324
`an “absence of fast diffusion paths” as compared with polycrystalline
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`films. Ex. 1007 at 9.
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`The purported invention in the ‘324 patent is a two-layer diffusion barrier to prevent
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`copper diffusion and provide good adhesion to a copper wiring layer.2 The bottom layer in the
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`barrier is an amorphous metal nitride to prevent copper diffusion. See, e.g., id., Abstract, 9:50-
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`52, 18:22-24. The top layer is a crystalline metal that contains nitrogen to provide good adhesion
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`to a copper wiring layer. See, e.g., id., Abstract, 9:49-50, 18:24-26. The claims require the
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`crystalline layer of the diffusion barrier to contain less nitrogen than the amorphous layer. Id.,
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`19:2-3. The claimed two-layer diffusion barrier, combining known crystalline and amorphous
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`barrier layers, was not new and non-obvious at the time of the alleged invention. Several prior
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`art references, such as Zhang and Ding, taught the same two-layer barrier structure.
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`Because the combination of Zhang and Ding, or in the alternative the combination of
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`Zhang, Ding, and Sun, renders obvious each of claims 1-3, 5-7, and 9 in the ‘324 patent under 35
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`U.S.C. § 103, Petitioner respectfully requests cancellation of these claims.
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`II.
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`THE ‘324 PATENT
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`A.
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`Overview of the ‘324 Patent
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`The face of the ‘324 patent indicates it was filed on June 19, 2000, issued on March 25,
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`2003, and claims foreign priority to Japanese application 11-214110 filed on June 24, 1999. The
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`patent contains claims 1-10, of which claims 1 and 5 are independent. Claim 1 and its dependent
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`claims 2-4 recite a barrier film preventing diffusion of copper from a copper wiring layer formed
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`2 The ‘324 patent’s specification and claims refer to a barrier “film” (i.e., thin film) having a
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`multi-layered structure of first and second films. In this context, the words “layer” and “film” are
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`used interchangeably. Ex. 1003, ¶ 42.
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`Inter Partes Review
`United States Patent No. 6,538,324
`on a semiconductor substrate. Claim 5 and its dependent claims 6-10 recite a multi-layered
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`wiring structure comprising the barrier film in claim 1. Although the specification describes
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`specific steps for manufacturing the claimed multi-layered wiring structure and barrier film, the
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`claims are directed only to the structure and 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 layer formed on
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`a semiconductor substrate, comprising a multi-layered structure of first and second films:
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`[1.1] said first film being composed of crystalline metal containing nitrogen 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 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 prevents diffusion
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`of copper from a copper wiring layer formed on a semiconductor substrate,
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`[5.1] said barrier film having a multi-layered structure of first and second films,
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`[5.2] said first film being composed of crystalline metal containing nitrogen therein,
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`[5.3] said second film being composed of amorphous metal nitride,
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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 second film.
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`5
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`Inter Partes Review
`United States Patent No. 6,538,324
`Claim elements [5.2]-[5.7] of claim 5 are identical to the claim elements [1.1]-[1.6] of
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`claim 1.
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`During prosecution, the PTO correctly explained that a device covered by claim 1 “could
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`be made by processes materially different from those” of the specific method described in the
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`specification. Ex. 1002 (‘324 patent file history) at 202; Ex. 1003, ¶ 56 (Dr. Banerjee agreeing
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`with PTO). The Applicant did not disagree.
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`B.
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`Prosecution History
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`The original application for the ‘324 patent included claims 1-36. Claims 1-10 were
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`directed to either a diffusion barrier film or a structure comprising the diffusion barrier film, and
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`claims 11-36 were directed to methods of forming either the diffusion barrier film or a structure
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`comprising the diffusion barrier film.
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`In an initial Office Action, the PTO restricted the claims into two distinct groups and
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`required election of one of the groups for examination. Group I contained claims 1-10 “drawn to
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`a semiconductor device,” and Group II contained claims 11-36 “drawn to a method of making a
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`semiconductor device.” Ex. 1002 at 202. The Applicant chose to prosecute Group I, claims 1-10,
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`and withdrew all of 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 rendered obvious
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`by U.S. Patent No. 5,858,873 (“Vitkavage,” Ex. 1008). Id. At 210-12. In response, the Applicant
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`amended the independent claims to recite “said first film being formed on said second film”
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`([1.4] and [5.5]) and “said first film containing nitrogen in a smaller content than that of said
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`second film” ([1.6] and [5.7]), seeking to distinguish the claims over Vitkavage because of these
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`added limitations. Id. at 219-23. The Applicant also added two new claims, corresponding to
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`claims 4 and 10 in the ‘324 patent.
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`Inter Partes Review
`United States Patent No. 6,538,324
`The PTO issued a final rejection finding the amended claims anticipated by U.S. Patent
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`No. 5,668,411 (“Hong,” Ex. 1009). The Applicant tried (Ex. 1002 at 231-36), but failed (id. at
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`237-39), to distinguish the claims over Hong, and eventually filed a Request for Continued
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`Examination. Id. at 240-41.
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`Along with the RCE, the Applicant further amended the independent claims to recite
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`“said first film in direct contact with said second film” ([1.5] and [5.6]). Id. at 247-49. With the
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`amendment, the Applicant distinguished Hong because it lacked a top layer (“first film”) in
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`direct contact with a bottom layer (“second film”), whereas Hong disclosed “a seed layer 46 of
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`the diffusion barrier film positioned between the top layer 48 and the bottom layer 44.” Id. at
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`245. The PTO 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 the same claim
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`elements he believed were missing from the art of record. For example, the Applicant
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`distinguished Vitkavage by arguing that Vitkavage does not disclose “said first film being formed
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`on said second film” ([1.4] and [5.5]) and “said first film containing nitrogen in a smaller content
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`than that of said second film” ([1.6] and [5.7]). These elements are disclosed in Zhang, as shown
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`in the annotated FIG. 8 of Zhang below, which teaches a two-layer diffusion barrier including a
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`top, first film 32 (in blue) formed on a bottom, second film 22 (in red).
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`Inter Partes Review
`United States Patent No. 6,538,324
`Annotated FIG. 8 of Zhang (Ex. 1004)
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`In Zhang, the “deposition [i.e., depositing] of the two films 22 and 32 is typically
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`performed as one sequence during a single evacuation cycle,” where nitrogen is applied during
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`sputter deposition of the bottom, second film 22 and then the nitrogen gas is turned off during the
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`deposition of the top, first film 32 of the diffusion barrier. Ex. 1004, 3:37-38. As a result, the
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`first film 32 contains a smaller nitrogen content than the second film 22. Compare Ex. 1004,
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`3:39-41 (film 22 contains TaN close to its stoichiometric composition, i.e., one-to-one atomic Ta
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`to atomic nitrogen, which is 50 atomic percent nitrogen) with id., 3:53-54 (film 32 contains 0-30
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`atomic percent nitrogen); see also id., FIG. 4.
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`Further, the claims were allowed after Applicant argued that Hong does not disclose “said
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`first film in direct contact with said second film” ([1.5] and [5.6]), but the prior art discloses this
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`claim element as well, such as in Zhang, which was not before the Examiner during prosecution.
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`See, e.g., Ex. 1004, FIG. 8 (annotated above, showing first film 32 in direct contact with second
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`film 22).
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` Level of Ordinary Skill III.
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`A person of ordinary skill in the art (“POSITA”) at the time the application leading to the
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`‘324 patent was filed would have an equivalent of a Master of Science degree from an accredited
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`institution in electrical engineering, materials science, or physics, or the equivalent, a working
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`knowledge of semiconductor processing technologies for integrated circuits, and at least two
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`years of experience in semiconductor processing analysis, design, and development. Ex. 1003, ¶
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`64. Additional graduate education could substitute for professional experience, and significant
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`work experience could substitute for formal education. Id.
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`Inter Partes Review
`United States Patent No. 6,538,324
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`IV.
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` Claim Construction
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`A claim in an unexpired patent subject to inter partes review receives the “broadest
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`reasonable construction in light of the specification of the patent in which it appears.” 37 C.F.R.
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`§ 42.100(b); see also Cuozzo Speed Techs., LLC v. Lee, No. 15-446, slip op. (U.S. June 20,
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`2016). The broadest reasonable construction should be applied to all claim terms in the ‘324
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`patent.
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`V.
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`CLAIMS 1-3, 5-7, AND 9 OF THE ‘324 PATENT ARE UNPATENTABLE OVER
`THE PRIOR ART
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`A.
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`Overview of the Prior Art
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`The ‘324 patent admits the inventors were not the first to recognize problems associated
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`with single-layer diffusion barriers for preventing diffusion of copper and suggest a multi-layer
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`solution. The specification recognized a desire for a diffusion barrier “having a high barrier
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`characteristic of preventing copper diffusion and high adhesion to copper.” Ex. 1001, 3:47-49;
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`see also 2:12-15. The specification also acknowledges that a barrier layer formed only of a
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`crystalline metal film, such as a crystalline R-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 good
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`adhesion), but would serve as a poor barrier to copper diffusion. Id., 3:14-20; see also, Ex. 1003,
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`¶ 67. On the other hand, a diffusion barrier formed only of an amorphous metal nitride would
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`provide a better barrier to copper diffusion since it “does not have the [grain-boundary] paths
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`through which copper is diffused,” but would suffer from poor adhesion because “copper
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`crystallinity and adhesion to copper are degraded” using an amorphous layer. Ex. 1001, 3:21-33;
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`see also, Ex. 1003, ¶ 67.
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`The ‘324 patent claims a two-layer diffusion barrier comprising adjacent crystalline and
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`amorphous films having different nitrogen contents. See, e.g., Ex. 1001, claims 1 and 5. In this
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`Inter Partes Review
`United States Patent No. 6,538,324
`multi-layer structure, the bottom film of the barrier (substrate side) may be a prior-art amorphous
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`metal nitride film, such as tantalum nitride, and the top film (copper side) may be a prior-art
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`crystalline metal film containing less nitrogen than the bottom film. As discussed below, both
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`the problems with known diffusion barriers and the solution described in the ‘324 patent were
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`already known in the art.
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`Zhang discloses a “first conductive film” that serves as a multi-layer diffusion barrier
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`relative to a “second conductive film” that includes mostly copper. Ex. 1004, Abstract. The first
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`conductive film in Zhang is a two-layer diffusion barrier film having top and bottom portions 32
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`and 22, with the bottom film 22 lying closer to the substrate than the top film 32.3 Id. According
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`to Zhang, a “combination of portions (22 and 32) within the first conductive film provides a
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`good diffusion barrier (first portion) and has good adhesion (second portion) with the second
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`conductive film (54 and 64).” Id. In Zhang, the top (32) and bottom (22) films are tantalum-
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`based films with different nitrogen contents. Id., 3:22-23. The “nitrogen percentage for the
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`second portion (32) is lower than the nitrogen atomic percentage for the first portion (22).” Id.,
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`Abstract. Zhang thus recognized the same problems and the same two-layer solution as the ‘324
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`patent. Indeed, Zhang meets every claim element of the ‘324 patent, except it does not expressly
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`mention the crystalline or amorphous nature of the films 22 and 32 in the diffusion barrier.
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`Ding, however, does address the crystalline/amorphous nature of a two-film diffusion
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`barrier, and is directed to the same problems and solution as the ‘324 patent and Zhang.
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`Specifically, Ding discloses a two-layer “TaNx/Ta barrier structure” that “provides both a barrier
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`to the diffusion of a copper layer deposited thereover, and enables the formation of a copper
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`3 Zhang refers to the same thin films 22 and 32 as either “portions” or “films.” See, e.g.,
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`Ex. 1004, Abstract (“portions (22 and 32)”), 3:37 (“films 22 and 32”).
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`layer having a high <111> crystallographic content so that the electromigration resistance of the
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`copper is increased.” Ex. 1005, Abstract.4 The diffusion barrier in Ding may consist of an
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`amorphous 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 copper,” i.e.,
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`providing good adhesion to the copper layer, and “depositing of a copper layer having a high
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`<111> crystal orientation,” (Ex. 1005, 8:1-4). See also Ex. 1003, ¶ 72.
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`The bottom film of the two-layer diffusion barriers in both Zhang and Ding consists of a
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`tantalum nitride (TaNx) film, which Ding teaches may be an amorphous thin film. Ex. 1005,
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`Abstract. The TaNx film in Zhang is “close to the stoichiometric composition (TaN),” such that
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`x equals one using the TaNx nomenclature. Ex. 1004, 3:39-41; see also id., 3:10-12 (“The
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`tantalum nitride film 22 typically includes 33 to 50 atomic percent nitrogen with the balance
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`essentially being tantalum”). Ding discloses a “TaNx layer, where x ranges from about 0.1 to
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`about 1.5, is sufficiently amorphous to prevent the diffusion of copper into the underlying
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`substrate, which is typically silicon or a dielectric such as silicon dioxide.” Ex. 1005, Abstract.
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`Other prior-art references, such as Holloway et al., “Tantalum as a diffusion barrier between
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`copper and silicon: Failure mechanism and effect of nitrogen additions,” Journal of Applied
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`4 <111> are indices representing a set of equivalent directions in a crystalline material.
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`Ex. 1003, ¶ 51; see also Ex. 1010 at 11-12, which is a technical publication that was catalogued
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`and available to the public in the Library of Congress in 1994. Ex. 1010 at 2 (showing Library of
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`Congress stamp dated December 21, 1994); Ex. 1014 (catalogue entry); Ex. 1011 at ¶ 5 (linking
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`Ex. 1010 to Ex. 1014). Papers catalogued and available to the public in libraries, including the
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`Library of Congress, are sufficiently “publicly accessible” to serve as prior art. See, e.g., In re
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`Hall, 781 F.2d 897 (Fed. Cir. 1986); In re Cronyn, 890 F.2d 1158,
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`Physics, vol. 71, no. 11, pages 1161 (Fed. Cir. 1989). Accordingly, Exhibit 1010 qualified as
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`prior art at least one year before the earliest priority date of the ‘324 patent. 5433-5444 (1992)
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`(“Holloway,” Ex. 1006),5 and Sun, also describe properties of various Ta-based diffusion barrier
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`layers at different nitrogen contents. See, e.g., Ex. 1006, Abstract; Ex. 1007, Abstract.
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`Zhang discloses an embodiment in which the top film of the two-layer diffusion barrier is
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`a “tantalum-rich tantalum nitride film” that has an upper surface which is “substantially pure
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`tantalum.” Ex. 1004, 3:54-57, FIG. 4.6 The top film of the barrier in Ding is also a tantalum
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`layer, which Ding teaches is a crystalline film with a <002> crystalline orientation. Ex. 1005,
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`8:1-4.
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`It would have been obvious to a POSITA at the time of the application leading to the
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`‘324 patent that the two-layer diffusion barrier consisting of a crystalline Ta film and an
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`amorphous TaNx film in Ding would have been usable as the two-layer diffusion barrier in
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`Zhang, as both prior-art references teach the same diffusion-barrier structure for the same
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`purpose of preventing copper diffusion and providing good adhesion to a copper layer, and both
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`5 Exhibit 1006 was catalogued and available to the public in the Library of Congress in
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`1992. Ex. 1006 at 3-4 (showing Library of Congress stamp dated June 17, 1992); Ex. 1012
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`(catalogue entry); Ex. 1011, ¶ 3 (linking Ex. 1006 to Ex. 1012). Papers catalogued and available
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`to the public in libraries, including the Library of Congress, are sufficiently “publicly accessible”
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`to serve as prior art. See, e.g., In re Hall, 781 F.2d 897 (Fed. Cir. 1986); In re Cronyn, 890 F.2d
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`1158, 1161 (Fed. Cir. 1989). Accordingly, Exhibit 1006 qualified as prior art at least one year
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`before the earliest priority date of the ‘324 patent.
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`6 FIG. 4 in Zhang illustrates the atomic percentage of nitrogen in the top film 32 as a
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`function of distance from its exposed surface. Ex. 1004, 3:50-53, FIG. 4.
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`use Ta-based thin films fabricated using similar sputtering-deposition techniques. Ex. 1003, ¶
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`75. Specifically, the POSITA would have found it obvious to modify Zhang to ensure the top
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`film (32) of the two-layer diffusion barrier is crystalline and the bottom film (22) is amorphous
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`given the teachings of Ding. Id..
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`1.
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`Zhang
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`U.S. Patent No. 5,893,752 to Zhang et al. was filed on December 22, 1997, issued on
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`April 13, 1999, and qualifies as prior art to the ‘324 patent under pre-AIA 35 U.S.C. §§ 102(a),
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`(b), and (e). Zhang was not considered or relied on by