Paper 12
`Trials@uspto.gov
`571-272-7822 Entered: November 5, 2015
`
`
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`
`
`
`MICRON TECHNOLOGY, INC. and
`MICRON MEMORY JAPAN, INC.,
`Petitioners,
`
`v.
`
`MASSACHUSETTS INSTITUTE OF TECHNOLOGY,
`Patent Owner.
`____________
`
`IPR2015-01087
`Patent 6,057,221 C1
`____________
`
`
`
`Before KALYAN K. DESHPANDE, BRIAN J. McNAMARA, and
`DANIEL J. GALLIGAN, Administrative Patent Judges.
`
`
`GALLIGAN, Administrative Patent Judge.
`
`
`
`DECISION
`Institution of Inter Partes Review
`37 C.F.R. § 42.108
`
`
`
`
`
`
`Trials@uspto.gov
`571-272-7822 Entered: November 5, 2015
`
`
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`
`
`
`MICRON TECHNOLOGY, INC. and
`MICRON MEMORY JAPAN, INC.,
`Petitioners,
`
`v.
`
`MASSACHUSETTS INSTITUTE OF TECHNOLOGY,
`Patent Owner.
`____________
`
`IPR2015-01087
`Patent 6,057,221 C1
`____________
`
`
`
`Before KALYAN K. DESHPANDE, BRIAN J. McNAMARA, and
`DANIEL J. GALLIGAN, Administrative Patent Judges.
`
`
`GALLIGAN, Administrative Patent Judge.
`
`
`
`DECISION
`Institution of Inter Partes Review
`37 C.F.R. § 42.108
`
`
`
`
`
`
`
`IPR2015-01087
`Patent 6,057,221 C1
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`
`I. INTRODUCTION
`
`Micron Technology, Inc. (“Micron”) and Micron Memory Japan, Inc.
`
`(“Micron Memory Japan” or “MMJ”) (collectively “Petitioners”) filed a
`
`Petition (“Pet.”) requesting inter partes review of claims 3, 4, 6–8, 13–15,
`
`17, 18, and 21–30 of U.S. Patent No. 6,057,221 C1 (“the ’221 patent,” Ex.
`
`1003), which are all of the claims that emerged from reexamination pursuant
`
`to Reexamination Request No. 90/011,607. Paper 2. Massachusetts
`
`Institute of Technology (“MIT” or “Patent Owner”) timely filed a
`
`Preliminary Response. Paper 10 (“Prelim. Resp.”). We have jurisdiction
`
`under 35 U.S.C. § 314 and 37 C.F.R. § 42.4(a).
`
`The standard for instituting an inter partes review is set forth in
`
`35 U.S.C. § 314(a), which provides:
`
`THRESHOLD—The Director may not authorize an inter partes
`review to be instituted unless the Director determines that the
`information presented in the petition filed under section 311
`and any response filed under section 313 shows that there is a
`reasonable likelihood that the petitioner would prevail with
`respect to at least 1 of the claims challenged in the petition.
`
`After considering the Petition, the Preliminary Response, and
`
`associated evidence, we conclude that Petitioners have demonstrated a
`
`reasonable likelihood that they would prevail in showing unpatentability of
`
`all the challenged claims. Thus, we institute an inter partes review as to
`
`claims 3, 4, 6–8, 13–15, 17, 18, and 21–30 of the ’221 patent.
`
`A. Related Matters
`
`Petitioners and Patent Owner indicate that the ’221 patent is asserted
`
`against Petitioners in MIT v. Micron Tech., Inc. et al., 1:15-cv-10374
`
`(D. Mass.). Pet. 1; Paper 5, 1. In addition, Patent Owner identifies
`
`
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`2
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`corporate reorganization proceedings involving Micron Memory Japan as a
`
`related matter under 37 C.F.R. § 42.8(b)(2). Paper 5, 1–2. We address the
`
`implications of these Japanese corporate reorganization proceedings,
`
`pending in the Tokyo District Court, in the Analysis section of this Decision.
`
`B. Real Parties in Interest
`
`Petitioners identify Elpida USA, Micron Semiconductor Products,
`
`Inc., and the trustees reorganizing Elpida Memory, Inc. in Tokyo district
`
`court, as real parties-in-interest. Pet. 1–2. Petitioners indicate Elpida
`
`Memory, Inc. is a bankrupt Japanese entity, succeeded by and known as
`
`Micron Memory Japan. Pet. 1 n.1.
`
`C. The ’221 Patent (Ex. 1003)
`
`The ’221 patent, titled “Laser-Induced Cutting of Metal Interconnect,”
`
`issued May 2, 2000, from U.S. Patent Application No. 08/825,808, filed on
`
`April 3, 1997. Ex. 1003. The claims of the ’221 patent were submitted to ex
`
`parte reexamination via Reexamination Request No. 90/011,607, filed
`
`March 30, 2011. A reexamination certificate issued on September 11, 2012.
`
`Id. at 15–16.
`
`As the title suggests, the ’221 patent generally relates to using a laser
`
`in cutting parts of a circuit. Id. at Abst., 1:12–15. The ’221 patent explains
`
`that using lasers to cut integrated circuits was well-known at the time the
`
`application for the ’221 patent was filed. Id. at 1:12–15. The segment of the
`
`circuit that is cut is called a “cut-link,” and a laser is directed onto a cut-link
`
`and supplies enough heat energy to vaporize and sever the cut-link. Id.
`
`In describing the prior art, the ’221 patent explains that typical cut-
`
`links have taken one of two forms. The first configuration is where the cut-
`
`link is “an undistinguished segment of a line in the circuit, where the width
`
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`of the cut-link is equal to the width of the lines to which it is conductively
`
`coupled,” as illustrated in Figure 1 (reproduced below). Id. at 1:49–56, Fig.
`
`1.
`
`
`
`Figure 1 depicts “a cross-sectional illustration of a cut-link pad of the prior
`
`art, from a perspective normal to the plane of the substrate, where the width
`
`of the pad is equal to the width of the lines.” Id. at 3:48–51.
`
`The second alleged prior art configuration is a “dog-bone”
`
`configuration in which the cut-link is narrower than the lines to which it is
`
`connected, as illustrated in Figure 2 (reproduced below). Id. at 1:56–61,
`
`Fig. 2.
`
`
`
`4
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`Figure 2 depicts “a cross-sectional illustration of a cut-link pad of the prior
`
`art, from a perspective normal to the plane of the substrate, where the
`
`interconnect has the shape of a dog bone.” Id. at 3:52–55.
`
`According to the ’221 patent, “[a]lthough intuition might further
`
`suggest that a fuse-shaped cut-link of thin width could be severed with
`
`greater precision and efficiency than an otherwise comparable cut-link of
`
`greater width, the present inventors have recognized that this notion is
`
`generally false.” Id. at 2:8–12. Thus, the ’221 patent purports to recognize
`
`the benefit of having cut-link segments or pads that are wider and of lower
`
`thermal resistance per unit length than the lines to which they connect. Id. at
`
`2:13–21.
`
`One configuration for a cut-link pad taught in the ’221 patent is
`
`illustrated in Figures 3 and 4. Figure 3 is reproduced below:
`
`
`
`Figure 3 illustrates a cross-sectional view, from a perspective normal to the
`
`plane of the substrate, of cut-link pad 20, which is wider than lines 21 and
`
`22, to which is bonded. Id. at 3:57–60, 4:36–39. Circle 24 represents the
`
`laser beam spot, and the ’221 patent explains that “[t]he amount of laser
`
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`5
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`energy absorbed by the cut-link is maximized by providing a cut-link shaped
`
`in a form approximating that of the laser beam spot 24.” Id. at 4:61–63.
`
`Figure 4 is reproduced below:
`
`
`
`Figure 4 depicts a perspective view of the cut-link pad and connecting lines
`
`of Figure 3. Id. at 3:61–62. As can be seen from the perspective view of
`
`Figure 4, the cut-link pad in this configuration lies in the same plane as the
`
`lines to which it connects.
`
`The ’221 patent describes another embodiment in which the cut-link
`
`pad is not coplanar with the lines to which it connects:
`
`In contrast to the embodiments thus described, wherein the pad
`and the lines all lie within the same plane of a chip or circuit
`board, the invention may also be embodied in multi-layered
`chips. Such an embodiment is illustrated in FIGS. 10 and 11.
`As before, the orientation of the pad 20 is parallel to the plane
`of the chip. However, in place of the laterally-extending lines,
`the lines take the form of vias 21a and 22a extending downward
`from the surface 52 of the pad 20 away from the laser and into
`the substrate. These vias 21a and 22a provide a conductive link
`between levels of the integrated circuit.
`
`Id. at 8:20–30.
`
`Figure 10 is reproduced below:
`
`6
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`IPR2015-01087
`Patent 6,057,221 C1
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`
`Figure 10 is a side view of cut-link pad 20 connected to conductive lines
`
`(vias) 21a and 22a in a multi-level structure. Id. at 4:16–18, 8:20–30.
`
`Figure 11 is reproduced below:
`
`
`
`Figure 11 is a view of the configuration of Figure 10 from underneath the
`
`
`
`via structure. Id. at 4:19–20.
`
`D. Claims
`
`As noted above, Petitioners challenge claims 3, 4, 6–8, 13–15, 17, 18,
`
`and 21–30 of the ’221 patent. Claims 3, 14, 17, and 26 are independent
`
`claims. Claims 4, 6–8, 13, 21–25, and 30 depend directly or indirectly from
`
`independent claim 3. Claims 15 and 29 depend from independent claim 14.
`
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`Claim 18 depends from independent claim 17, and claims 27 and 28 depend
`
`from claim 26.
`
`Each of the challenged claims is directed to a “method for cutting a
`
`link between interconnected circuits” comprising steps of (1) “directing a
`
`laser upon an electrically-conductive cutlink pad conductively bonded
`
`between a first electrically-conductive line and a second electrically-
`
`conductive line on a substrate” and (2) “maintaining the laser upon the cut-
`
`link pad until the laser infuses sufficient energy into the cut-link pad to break
`
`the conductive link across the cut-link pad between the pair of electrically-
`
`conductive lines.” Each of the challenged claims also recites “the cut-link
`
`pad having substantially less thermal resistance per unit length than each of
`
`the first and second lines.”
`
`The challenged claims differ, however, on the particular structures
`
`and configurations required of the cut-link pad and the electrically-
`
`conductive lines, which are discussed further below. One feature of
`
`independent claims 3, 17, and 26 that is not recited in independent claim 14
`
`is a particular configuration for the cutlink pad and the lines to which it
`
`connects defined by the limitation reciting that “the electrically-conductive
`
`cut-link pad has an inner surface facing the substrate and an opposing outer
`
`surface facing away from the substrate, the first and second electrically-
`
`conductive lines extending from the inner surface into the substrate.”
`
`
`
`Independent claims 3 and 14 are reproduced below:
`
`link between
`a
`cutting
`for
`A method
`3.
`
`interconnected circuits, comprising the following steps:
`directing a laser upon an electrically-conductive cutlink
`pad conductively bonded between a first electrically-conductive
`line and a second electrically-conductive line on a substrate,
`
`
`
`8
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`IPR2015-01087
`Patent 6,057,221 C1
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`
`thermal
`less
`the cut-link pad having substantially
`resistance per unit length than each of the first and second lines,
`wherein the width of the cut-link pad is at least ten
`percent greater than the width of each of the first and second
`electrically-conductive lines; and
`maintaining the laser upon the cut-link pad until the laser
`infuses sufficient energy into the cut-link pad to break the
`conductive link across the cut-link pad between the pair of
`electrically-conductive lines,
`wherein the electrically-conductive cut-link pad has an
`inner surface facing the substrate and an opposing outer surface
`facing away from the substrate, the first and second electrically-
`conductive lines extending from the inner surface into the
`substrate.
`
`link between
`a
`cutting
`for
`14. A method
`
`interconnected circuits comprising the following steps:
`directing a laser upon an electrically-conductive cut-link
`pad conductively bonded between a first electrically-conductive
`line and a second electrically-conductive line on a substrate,
`the cut-link pad having substantially
`less
`thermal
`resistance per unit length than each of the first and second lines,
`wherein the cut-link pad is covered with a passivative
`layer that is harder than the substrate; and
`maintaining the laser upon the cut-link pad until the laser
`infuses sufficient energy into the cut-link pad to break the
`conductive link across the cut-link pad between the pair of
`electrically-conductive lines.
`
`Ex. 1003, 10:49–62, Reexam Cert., 1:29–48.
`
`
`E. Prior Art Relied Upon
`
`Petitioners rely upon the following prior art references:
`
`Billig
`
`Lou
`
`Wada
`
`
`
`US 5,025,300
`
`June 18, 1991
`
`Ex. 1010
`
`US 5,729,042
`
`Mar. 17, 1998
`
`Ex. 1008
`
`JP 6-244285
`
`Sept. 2, 1994
`
`Ex. 1007
`
`9
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`Koyou
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`JP 8-213465
`
`
`
`Aug. 20, 1996
`
`Ex. 1006
`
`F. Asserted Grounds of Unpatentability
`
`Petitioners challenge claims 3, 4, 6–8, 13–15, 17, 18, and 21–30 of the
`
`’221 patent based on the asserted grounds of unpatentability set forth in the
`
`table below.
`
` Reference(s)
`
`Basis
`
`Claims Challenged
`
`§ 102(a)
`1 Koyou
`2 Wada and Lou1
`§ 103(a)
`§ 103(a)
`3 Wada and Billig
`§ 103(a)
`4 Koyou and Wada
`§ 103(a)
`5 Koyou and Lou
`§ 103(a)
`6 Koyou and Billig
`§ 103(a)
`7 Koyou, Wada, and Lou
`8 Koyou, Wada, and Billig § 103(a)
`
`
`3, 4, 6–8, 23, 25, 26, and 28
`14, 15, and 29
`14, 15, and 29
`3, 4, 6–8, 23, 25, 26, and 28
`13, 17, 18, 21, 22, 24, 27, and 30
`13, 17, 18, 21, 22, 24, 27, and 30
`13, 17, 18, 21, 22, 24, 27, and 30
`13, 17, 18, 21, 22, 24, 27, and 30
`
`II. ANALYSIS
`
`A. Time Bar under 35 U.S.C. § 315(b) Based on Japanese Corporate
`Reorganization Proceedings
`
`Under 35 U.S.C. § 315(b), “[a]n inter partes review may not be
`
`instituted if the petition requesting the proceedings is filed more than 1 year
`
`after the date on which the petitioner, real party in interest, or privy of the
`
`petitioner is served with a complaint alleging infringement of the patent.”
`
`Patent Owner argues that inter partes review is barred under 35 U.S.C.
`
`§ 315(b) because MMJ, a Petitioner, and its bankruptcy trustees in Japan, a
`
`
`1 Although Petitioners add the general knowledge in the art to the express
`statement of certain grounds of unpatentability under 35 U.S.C. § 103(a)
`(Pet. 5), that is not necessary. Obviousness is determined from the
`perspective of one with ordinary skill in the art. We leave out the express
`inclusion of the general knowledge in the art.
`
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`real party in interest, were served with a complaint more than one year
`
`before the Petition was filed. Prelim. Resp. 1–2, 18–22. In particular, Patent
`
`Owner contends that a “Petition for Corporate Reorganization Claim
`
`Assessment” filed in Tokyo District Court on December 22, 2012, and
`
`served on MMJ and its trustees on December 26, 2012, is a “complaint”
`
`within the meaning of section 315(b). Prelim. Resp. 19; Ex. 2004 (“Petition
`
`for Corporate Reorganization Claim Assessment”); Ex. 2005
`
`(Acknowledgement of Receipt of Petition Brief, Dec. 26, 2012); Ex. 2006
`
`(Certificate of Service); Ex. 2007 (Translation of Certificate of Service).
`
`We are not persuaded that a petition for claim assessment in a
`
`corporate reorganization proceeding in a foreign country is “a complaint
`
`alleging infringement of the patent” within the meaning of section 315(b).
`
`None of the Board decisions cited by Patent Owner determined that a
`
`proceeding in a foreign country triggered a bar under section 315(b). See,
`
`e.g., St. Jude Med., Cardiology Division, Inc. v. Volcano Corp., IPR2013-
`
`00258, Paper 29, at 7 (PTAB Oct. 16, 2013) (determining that a
`
`counterclaim for infringement in U.S. District Court is “a complaint alleging
`
`infringement of the patent” within the meaning of 35 U.S.C. § 315(b));
`
`Amkor Tech., Inc. v. Tessera, Inc., IPR2013-00242, Paper 98, at 18–19
`
`(PTAB Jan. 31, 2014) (determining “that the one-year statutory deadline in
`
`section 315(b) applies only to civil actions brought under 35 U.S.C. §§ 271
`
`and 281, and not to arbitration proceedings”). Although these Board
`
`decisions are not precedential, we find them instructive in determining what
`
`constitutes a complaint within the meaning of section 315(b).
`
`Patent Owner further argues that “[t]he Japanese proceedings are
`
`materially indistinguishable from ordinary infringement litigation in the
`
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`United States” and that they “follow[] comparable procedures and impose[]
`
`parallel consequences.” Prelim. Resp. 20. We disagree for at least the
`
`reason that we are not aware of any authority, and Patent Owner has not
`
`directed us to any authority, that a Japanese bankruptcy court has to render a
`
`decision that is legally binding in the United States concerning the validity
`
`of a United States patent.
`
`On the current record, we are not persuaded the Petition is barred
`
`under section 315(b).
`
`B. Petition Should Be Denied under 35 U.S.C. § 325(d)
`Based on Prior Reexamination
`
`Patent Owner argues institution should be denied under section 325(d)
`
`because the Petition presents the same or substantially the same prior art and
`
`arguments as those already considered in the ex parte reexamination of the
`
`’221 patent. Prelim. Resp. 22–24. As Patent Owner recognizes, denial
`
`under section 325(d) is at the discretion of the Board. See Prelim. Resp. 24
`
`(“Congress granted this Board discretion to refuse duplicative proceedings
`
`for a reason.”). For the reasons set forth below, we determine the Petition
`
`presents a reasonable likelihood that Petitioners will prevail with respect to
`
`at least one claim, and, therefore, we decline to deny institution under
`
`section 325(d).
`
`C. Claim Construction
`
`In an inter partes review, “[a] claim in an unexpired patent shall be
`
`given its broadest reasonable construction in light of the specification of the
`
`patent in which it appears.” 37 C.F.R. § 42.100(b); In re Cuozzo Speed
`
`Techs., LLC, 793 F.3d 1268, 1275–78 (Fed. Cir. 2015), reh’g en banc
`
`denied, 793 F.3d 1297 (Fed. Cir. 2015). In determining the broadest
`
`reasonable construction, we presume that claim terms carry their ordinary
`
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`and customary meaning. See In re Translogic Tech., Inc., 504 F.3d 1249,
`
`1257 (Fed. Cir. 2007). This presumption may be rebutted when a patentee,
`
`acting as a lexicographer, sets forth an alternate definition of a term in the
`
`specification with reasonable clarity, deliberateness, and precision. In re
`
`Paulsen, 30 F.3d 1475, 1480 (Fed. Cir. 1994).
`
`Petitioners propose a construction for each of the following claim
`
`terms or phrases: (1) “cut-link (cutlink) pad” (all challenged claims);
`
`(2) “substrate” (all challenged claims); and (3) “harder than the substrate”
`
`(claims 14, 15, 29, and 30). Pet. 6–8. In response, Patent Owner contends
`
`“[t]he ’221 Patent is valid under any reasonable construction, including . . .
`
`under petitioners’ three proposed constructions.” Prelim. Resp. 17. Patent
`
`Owner then separately addresses Petitioners’ construction of “substrate” and
`
`proposes an alternative construction for this claim term. Id.
`
`First, Petitioners propose to construe “cut-link (cutlink) pad” to mean
`
`“an electrically-conductive segment of a circuit capable of being ablated in
`
`whole or in part when exposed to a laser beam.” Pet. 6–7. Each of
`
`independent claims 3, 14, 17, and 26 specifies that the cut-link pad is
`
`“electrically-conductive,” and, therefore, this further recitation in the
`
`construction of the term is unnecessary. For purposes of this Decision, we
`
`construe the term “cut-link (cutlink) pad” to mean “a segment of a circuit
`
`capable of being ablated in whole or in part when exposed to a laser beam.”
`
`See, e.g., Ex. 1003, 1:12–15 (“The use of lasers to cut integrated circuits is
`
`well-known in the art. In existing methods, a laser is directed onto a cut-link
`
`segment of the circuit. The laser supplies sufficient heat to vaporize the cut-
`
`link, thereby severing the cut-link.”), 3:1–3 (“In the method of this invention
`
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`a laser is directed upon a cut-link pad, as described above, and the laser is
`
`maintained there until the conductive link between the lines is broken.”).
`
`Next, Petitioners propose to construe “substrate” to mean “base
`
`structure, including overlying insulating layers.” Pet. 6–8. Patent Owner
`
`contends that Petitioners’ proposed construction of “substrate” is incomplete
`
`because it does not specify that the substrate is “beneath the cut-link pad.”
`
`Prelim. Resp. 17. We are not persuaded that the term “substrate” requires an
`
`express construction as proposed by either party. Defining a “substrate” to
`
`be a “base structure” simply restates the plain and ordinary meaning of the
`
`term, and we are not persuaded that the broadest reasonable interpretation of
`
`“substrate” requires a recitation of what additional layers can be included.
`
`Furthermore, the claims themselves define the relative location of the
`
`substrate vis-à-vis other components, such as reciting various components
`
`are “on a substrate.” See claims 3, 14, 17, and 26. We are not persuaded it
`
`is necessary to include “beneath the cut-link pad” in the definition of
`
`“substrate.” Therefore, at this stage of the proceeding, we apply the plain
`
`and ordinary meaning of the term “substrate.”
`
`Finally, Petitioners propose to construe “harder than the substrate” to
`
`mean “harder than the layer of the substrate upon which the cut-link pad
`
`resides.” Pet. 6–8. We are not persuaded that the broadest reasonable
`
`interpretation of this phrase requires reference to any particular “layer.” The
`
`phrase “harder than the substrate” is clear and stands on its own. Therefore,
`
`at this stage of the proceeding, we apply the plain and ordinary meaning of
`
`“harder than the substrate.”
`
`All remaining claim terms or phrases recited in the challenged claims
`
`need not be construed explicitly at this time.
`
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`D. Overview of Challenges
`
`Petitioners present multiple grounds of unpatentability for each claim
`
`of the ’221 patent. Grounds 1 and 4 address claims 3, 4, 6–8, 23, 25, 26, and
`
`28. Grounds 2 and 3 address claims 14, 15, and 29. Grounds 5 through 8
`
`address claims 13, 17, 18, 21, 22, 24, 27, and 30. We begin our discussion
`
`with an analysis of Ground 2 and Wada and Lou.
`
`E. Claims 14, 15, and 29 – Obviousness over Wada and Lou
`
`Petitioners contend independent claim 14 and its dependent claims 15
`
`and 29 would have been unpatentable under 35 U.S.C. § 103(a) over the
`
`combination of Wada and Lou. Pet. 31–46. Petitioners provide detailed
`
`analysis and arguments to explain how the cited prior art references
`
`allegedly teach the claimed subject matter and rely upon the Declaration of
`
`Dr. Michael Thomas (Ex. 1001) to support their positions. Id.
`
`1. Wada2
`
`Wada relates to fuses that are melted or broken by lasers and teaches
`
`various fuse configurations. See Ex. 1007, Abst., ¶¶ 1–7, Figs. 1–4. Wada
`
`explains that a “redundancy fuse is generally melted by focusing irradiation
`
`of an energy beam such as a YAG laser.” Ex. 1007 ¶ 2; see also Ex. 1007,
`
`Abst. Figure 1 of Wada is reproduced below:
`
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`2 References to Wada and Koyou are to the English translations provided
`with the Petition.
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`Figure 1 is a top view of a semiconductor device having redundancy fuse 1
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`according to one embodiment. Ex. 1007 ¶ 10.
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`Wada explains that “redundancy fuse 1 comprises a melting portion
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`1a and non-melting portions 1b” and that “melting portion 1a is continuously
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`provided between the non-melting portions 1b . . . and the width thereof is
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`configured larger than a width of the non-melting portion 1b.”
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`Ex. 1007 ¶ 10. Wada provides exemplary widths of 1 µm and 2 µm,
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`respectively, for the melting and non-melting portions. Ex. 1007 ¶ 10.
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`Figure 2 of Wada is reproduced below:
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`Figure 2 is a top view of a semiconductor device having redundancy fuse 5
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`according to another embodiment. Ex. 1007 ¶ 13. In this configuration,
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`“redundancy fuse 5 . . . comprises a melting portion 5a positioned in the
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`center and non-melting portions 5b continuously provided at both ends of
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`the melting portion 5a and provided, in a portion thereof, with a region 6
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`with higher thermal resistance than that at the periphery.” Ex. 1007 ¶ 13.
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`Wada provides exemplary widths of 1 µm and 0.5 µm, respectively, for the
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`melting portion 5a and region 6. Ex. 1007 ¶ 13.
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`Wada teaches a benefit of making the melting portion of the fuse
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`wider than the non-melting portion is that “the ratio of the area occupied by
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`the melting portion in the irradiation region of the energy beam will be
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`larger than was conventional. Thus, the energy of the energy beam can be
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`effectively utilized for melting the redundancy fuse.” Ex. 1007 ¶ 8. Wada
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`also teaches a benefit in making the non-melting portions have a higher
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`thermal resistance: “[B]ecause the region having high thermal resistance is
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`provided in a portion of . . . the non-melting portions, escape of heat
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`generated in the melting portion can be reduced. Thus, the energy of the
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`energy beam can be effectively utilized for melting the redundancy fuse.”
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`Ex. 1007 ¶ 9.
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`2. Lou
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`Lou teaches providing a “fusible link” that can be opened using a
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`laser. Ex. 1008, 2:49–52. Figure 2 of Lou is reproduced below:
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`Figure 2 of Lou illustrates a two layer fuse (13 and 14) resting on
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`silicon oxide (10) and covered with passivation layers 15 and 16. Ex. 1008,
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`3:14–51. Lou teaches that passivation layers 15 and 16 comprise boro-
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`phosphosilicate glass and silicon nitride, respectively. Ex. 1008, 3:52–59.
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`3. Independent Claim 14
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`a. Wada’s Teachings of Certain Common Claim Limitations
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`First, as explained above, each of the challenged claims is directed to
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`a “method for cutting a link between interconnected circuits” comprising
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`steps of (1) “directing a laser upon an electrically-conductive cutlink pad
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`conductively bonded between a first electrically-conductive line and a
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`second electrically-conductive line on a substrate” and (2) “maintaining the
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`laser upon the cut-link pad until the laser infuses sufficient energy into the
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`cut-link pad to break the conductive link across the cut-link pad between the
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`pair of electrically-conductive lines.”
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`Petitioners contend Figures 1 and 2 of Wada disclose fuse
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`configurations having a “melting portion” (1a in Figure 1 and 5a in Figure 2)
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`that is a “cutlink pad.” Pet. 37 (citing Ex. 1007 ¶¶ 10, 13). Wada explains
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`that the melting portion is irradiated by an energy beam, such as a YAG
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`laser, to melt the melting portion. Ex. 1007 ¶¶ 7, 10–14. Accordingly, the
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`“melting portion” is a cutlink pad within the meaning of the claims because
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`it is “a segment of a circuit capable of being ablated in whole or in part when
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`exposed to a laser beam.” Petitioners contend that lines 1b in Figure 1 and
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`lines 6 in Figure 2 are first and second conducting lines on a substrate,
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`between which the melting portions (cutlink pads) are conductively bonded.
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`Pet. 37 (citing Ex. 1007 ¶¶ 10, 13–14, Figs. 1–2; Ex. 1001 ¶ 182).
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`Petitioners also contend Wada teaches directing a laser on the cutlink
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`pad and maintaining it until the conductive link is broken. Pet. 40 (citing
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`Ex. 1007 ¶¶ 2, 7, Figs. 1, 2; Ex. 1001 ¶¶ 199–200). Wada explains that a
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`“redundancy fuse is generally melted by focusing irradiation of an energy
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`beam such as a YAG laser.” Ex. 1007 ¶ 2; see also Ex. 1007, Abst. (“The
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`energy of an energy beam is more effectively utilized, allowing a
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`redundancy fuse connected to a redundant circuit comprised by a
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`semiconductor-integrated circuit device to be reliably melted by an energy
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`beam having lower energy.”).
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`On the record before us, we are persuaded that Wada teaches these
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`limitations.
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`b. “Substantially Less Thermal Resistance per Unit Length”
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`Next, Petitioners contend Wada teaches “the cut-link pad having
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`substantially less thermal resistance per unit length than each of the first and
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`second lines,” which is recited in each independent claim. Pet. 37–39. In
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`particular, Petitioners argue that the fuses of Figures 1 and 2 are of uniform
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`thickness and are made of the same material, and the melting portions
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`(cutlink pads – 1a in Figure 1 and 5a in Figure 6) are wider than the lines to
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`which they connect (1b in Figure 1 and 6 in Figure 2). Id.
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`First, with respect to the relative widths of the structures, Wada
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`provides widths of approximately 1 μm and 2 μm, respectively, for 1b (lines)
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`and 1a (melting portion) in Figure 1:
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`[T]he width of the non-melting portion 1b is approximately 1
`μm, while the size of the melting portion 1a is made a size that
`allows melting and is close to the area of the region irradiated
`by laser light 4; and for example, if the region irradiated by
`laser light 4 is made a circle with a diameter of 3 μm, the area
`of the melting portion 1a is made approximately 60% thereof,
`for example a square with a 2 μm side.
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`Ex. 1007 ¶ 10. With reference to Figure 2, Wada explains that “the widths
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`of the melting portion 5a and the non-melting portion 5b, excluding the
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`regions 6, are made approximately 1 μm, and the width of the regions 6 is
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`made approximately 0.5 μm.” Ex. 1007 ¶ 13.
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`Petitioners contend Wada teaches that the melting and non-melting
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`portions of the fuse are made of the same material, citing Wada’s disclosure
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`that “[t]his redundancy fuse 1 comprises a melting portion 1a and non-
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`melting portions 1b, and is formed from polycrystaline silicon, or polycide,
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`which is made of polycrystaline silicon and a metal silicide, or aluminum, or
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`the like.” Ex. 1007 ¶ 10 (cited at Pet. 38). Petitioners further cite the
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`declaration of one of the inventors of the ’221 patent, Joseph Bernstein,
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`submitted by Patent Owner during reexamination. Pet. 38 (citing Ex. 1016
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`(Declaration of Joseph B. Bernstein (“Bernstein Declaration”))). In this
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`declaration, Dr. Bernstein stated: “[T]he fuse structures disclosed in Wada
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`are horizontal structures, in which the fuse pad (i.e., the ‘fusing portion’) and
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`the first and second electrically-conductive lines (i.e., the ‘non-fusing
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`portions’) are formed at the same time from the same material in the same
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`layer of metallization.” Ex. 1016 ¶ 35.
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`Petitioners also cite the Bernstein Declaration in support of their
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`contention that the thickness of the fuse structure in Wada, including the
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`melting and non-melting portions, is uniform. Pet. 38 (citing Ex. 1016 ¶ 36).
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`Dr. Bernstein stated: “In horizontal fuse structures, one dimension is
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`constant (i.e., the thickness of the fuse pad and the conductive lines is the
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`same).” Ex. 1016 ¶ 36.
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`We agree with Petitioners that, given two structures made of the same
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`material and having the same thickness, the wider structure will have a lower
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`thermal resistance per unit length because the cross sectional area of the
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`wider structure will be larger. On the record before us, in which Wada
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`teaches melting portions having widths roughly twice those of the lines
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`connecting to them, we are persuaded Wada teaches “the cut-link pad having
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`substantially less thermal resistance per unit length than each of the first and
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`second lines.”
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`c. “Passivative Layer That Is Harder Than the Substrate”
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`With respect to the limitation of claim 14 reciting “wherein the cut-
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`link pad is covered with a passivative layer that is harder than the substrate,”
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`Petitioners contend Lou teaches a passivation layer of silicon nitride
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`covering a laser fuse on a silicon dioxide substrate. Pet. 39–40. As
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`explained above, Figure 2 of Lou illustrates a two layer fuse (13 and 14)
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`resting on silicon oxide (10) and covered with passivation layers 15 and 16.
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`Ex. 1008, 3:14–51. Lou teaches that passivation layers comprise boro-
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`phosphosilicate glass and silicon nitride, respectively. Ex. 1008, 3:52–59.
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`Petitioners argue that the term “silicon oxide,” used in the preferred
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`embodiments of Lou, was well-known to encompass silicon dioxide
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`materials and point out that the Background section of Lou teaches forming
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`fusible links on silicon dioxide. Pet. 39 n.10 (citing, inter alia, Ex. 1008,
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`2:14–18; Ex. 1001 ¶ 191). Petitioners also cite to Patent Owner’s statement
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`in reexamination that Lou teaches a fuse on top of silicon dioxide:
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`Lou discloses a vertical fuse structure having a pedestal
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`10 of silicon dioxide, resting on a layer 12 of the same material
`lying on the surface of a substrate 11, comprising the integrated
`circuit (see col. 3, 11. 14-18 and FIG. 2 of Lou). A two layer
`fuse lies on the pedestal 10, and two passivating layers 15, 16
`cover the fuse (see col. 3,
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