Raytheon Company v. Sony Corporation ( 2018 )


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  •        NOTE: This disposition is nonprecedential.
    United States Court of Appeals
    for the Federal Circuit
    ______________________
    RAYTHEON COMPANY,
    Appellant
    v.
    SONY CORPORATION, SAMSUNG ELECTRONICS
    CO., LTD., SAMSUNG ELECTRONICS AMERICA,
    INC., SAMSUNG SEMICONDUCTOR, INC.,
    Appellees
    ______________________
    2017-1554, 2017-1556, 2017-1557
    ______________________
    Appeals from the United States Patent and Trade-
    mark Office, Patent Trial and Appeal Board in Nos.
    IPR2015-01201, IPR2016-00209, IPR2016-00962.
    ______________________
    Decided: April 2, 2018
    ______________________
    JOHN J. MOLENDA, Steptoe & Johnson, LLP, New
    York, NY, argued for appellant. Also represented by
    JOHN LLOYD ABRAMIC, THOMAS J. FILARSKI, Chicago, IL;
    FANG BU, Washington, DC.
    MATTHEW A. SMITH, Smith Baluch LLP, Washington,
    DC, argued for all appellees. Appellee Sony Corporation
    also represented by ANDREW BALUCH; ROBERT LOUIS
    2                  RAYTHEON COMPANY   v. SONY CORPORATION
    HAILS, JR., T. CY WALKER, Baker & Hostetler LLP, Wash-
    ington, DC; ZHUANJIA GU, JENNIFER SERAPHINE, JACOB
    ZWEIG, Turner Boyd LLP, Redwood City, CA.
    RONALD J. PABIS, Greenberg Traurig LLP, Washing-
    ton, DC, for appellees Samsung Electronics Co., Ltd.,
    Samsung Electronics America, Inc., Samsung Semicon-
    ductor, Inc. Also represented by MARK G. DAVIS, PATRICK
    J. MCCARTHY, STEPHEN K. SHAHIDA; RICHARD A. EDLIN,
    New York, NY; HEATH BRIGGS, Denver, CO.
    ______________________
    Before LOURIE, O’MALLEY, and WALLACH, Circuit Judges.
    O’MALLEY, Circuit Judge.
    Raytheon Company (“Raytheon”) appeals from final
    written decisions in two inter partes review (“IPR”) pro-
    ceedings, in which the Patent Trial and Appeal Board
    (“Board”) held all claims of U.S. Patent No. 5,591,678
    (“’678 patent”) unpatentable. See Sony Corp. v. Raytheon
    Co., IPR2015-01201, 2016 Pat. App. LEXIS 13452
    (P.T.A.B. Nov. 30, 2016) (“1201 Decision”); Sony Corp. v.
    Raytheon Co., IPR2016-00209, -00962, 2016 Pat. App.
    LEXIS 13045 (P.T.A.B. Nov. 30, 2016) (“209 Decision”).
    For the following reasons, we affirm.
    I. BACKGROUND
    A. The ’678 Patent
    Entitled “Process of Manufacturing a Microelectric
    Device Using a Removable Support Substrate and Etch-
    Stop,” the ’678 patent is directed to purported advances in
    the manufacture of stacked semiconductors found in
    everyday electronic devices. The patent expired before
    the IPR proceedings at issue were initiated, and claims
    priority to an application filed on January 19, 1993.
    Rather than employ a conventional “front-side” fabri-
    cation process, whereby microelectronic circuits are
    RAYTHEON COMPANY       v. SONY CORPORATION                           3
    formed and substrates are stacked on top of a wafer, the
    ’678 patent employs a “back-side” process, whereby many
    of the fabrication steps are performed on the bottom of the
    wafer. ’678 patent, col. 2, ll. 29–37. As shown in box 24 of
    Figure 1 below, a first, multi-layer substrate 40 contain-
    ing circuitry 50 is attached to the bottom of a second
    substrate 58, which provides mechanical support for the
    wafer and circuitry. 
    Id. col. 4,
    ll. 22–52; 
    id. col. 5,
    ll. 15–
    44.
    
    Id. fig.1. (boxes
    24, 28). Once the wafer and circuitry are
    supported, the back side of the first substrate is removed.
    
    Id. col. 5,
    ll. 45–51. Finally, as shown in box 28 of Figure
    1, various back-side electrical connections are formed
    through the remaining portion of the first substrate. 
    Id. col. 6,
    ll. 10–15, 44–49.
    This fabrication method allows electrical connections
    to be made through the device rather than around the
    sides thereof—making the device more compact—while
    using the second substrate to protect the fragile wafer and
    circuitry from damage during fabrication. 
    Id. col. 1,
    l. 50
    to col. 2, l. 2; 
    id. col. 2,
    ll. 32–37; 
    id. col. 2,
    l. 59 to col. 3, l.
    14. Additional substrates may be sequentially stacked on
    the back side of the resulting structure to achieve a three-
    dimensional device containing an arbitrarily large num-
    ber of layers. See 
    id. col. 3,
    ll. 38–40; 
    id. col. 7,
    ll. 14–17,
    60–65.
    Dependent claim 5 is representative and recites—
    through its dependence from claim 1—the method de-
    scribed above using silicon-based materials:
    4                   RAYTHEON COMPANY    v. SONY CORPORATION
    1. A method of fabricating a microelectronic de-
    vice, comprising the steps of:
    furnishing a first substrate having an
    etchable layer, an etch-stop layer overly-
    ing the etchable layer, and a wafer overly-
    ing the etch-stop layer;
    forming a microelectronic circuit element
    in the exposed side of the wafer of the first
    substrate opposite to the side overlying
    the etch-stop layer;
    attaching the wafer of the first substrate to
    a second substrate; and
    etching away the etchable layer of the first
    substrate down to the etch-stop layer.
    ....
    5. The method of claim 1, wherein the etchable
    layer is silicon, the etch-stop layer is silicon diox-
    ide, and the wafer is single-crystal silicon.
    
    Id. col. 8,
    ll. 5–16 (emphasis added), 30–32.
    B. The Prior Art
    Three prior art references are at issue on appeal:
    (1) U.S. Patent No. 4,422,091 to Liu (“Liu”), (2) U.S.
    Patent No. 5,202,754 to Bertin (“Bertin”), and
    (3) Japanese Unexamined Patent Application Publication
    No. 64-18248 to Morimoto (“Morimoto”).
    Liu issued in 1983 and therefore qualifies as prior art
    to the ’678 patent under pre-AIA § 102(b). Liu describes a
    gallium arsenide, multi-layer charge coupled device
    (“CCD”) for detecting electromagnetic radiation, as well as
    a method of fabrication. Liu at Abstract; 
    id. at col.
    2, 7–
    18.
    RAYTHEON COMPANY    v. SONY CORPORATION                     5
    Bertin issued several months after the priority date of
    the ’678 patent, but was filed sixteen months prior there-
    to, on September 13, 1991, and therefore nominally quali-
    fies as prior art under pre-AIA § 102(e). Bertin discloses
    “[a] fabrication method and resultant three-dimensional
    multichip package” containing several layers of silicon-
    based material. Bertin at Abstract; 
    id. col. 1,
    ll. 10–15; 
    id. col. 1,
    l. 55 to col. 2, l. 31; 
    id. col. 3,
    ll. 4–46.
    Finally, Morimoto published in 1989 and therefore
    qualifies as prior art under pre-AIA § 102(b). Morimoto
    discloses “a method for manufacturing semiconductor
    devices” containing multiple layers. J.A. 115–16. 1 One of
    those layers is a “supporting silicon substrate,” which
    Morimoto teaches is removed during the fabrication
    process. See J.A. 116 (explaining that a “two-layer active
    layer structure is formed” by, among other things, bond-
    ing a “supporting silicon substrate” to an insulating film,
    performing additional steps, and then “removing the
    supporting silicon substrate” (emphasis added)).
    C. Procedural History
    Appellees Sony Corporation, Samsung Electronics Co.,
    Ltd., Samsung Electronics America, Inc., and Samsung
    Semiconductor, Inc. (collectively, “Sony”) filed a series of
    IPR petitions against Raytheon’s ’678 patent, which were
    consolidated into the two proceedings at issue here.
    In its final written decisions, the Board held in rele-
    vant part all claims unpatentable under pre-AIA 35
    U.S.C. § 103 as obvious over the prior art of record. See
    209 Decision, 2016 Pat. App. LEXIS 13045, at *33–64;
    1201 Decision, 2016 Pat. App. LEXIS 13452, at *43–69.
    Sony appealed with respect to claims 5, 13–14, and 16–18
    1 We cite here to the certified English translation of
    Morimoto included in the joint appendix. See J.A. 115–19.
    6                  RAYTHEON COMPANY    v. SONY CORPORATION
    only.     We have       jurisdiction   under   28   U.S.C.
    § 1295(a)(4)(A).
    II. DISCUSSION
    Raytheon makes three principal arguments on appeal.
    First, Raytheon asserts that the Board failed to address
    its argument that using silicon in Liu’s devices would
    render them inoperable. Second, Raytheon argues that
    the Board erred in finding that it failed to antedate Ber-
    tin. Third, Raytheon argues that the Board erroneously
    construed the claim term “second substrate” to encompass
    Morimoto’s temporary supporting substrate. As explained
    below, we disagree with Raytheon’s Liu- and Bertin-based
    arguments and therefore affirm the Board’s obviousness
    determinations. And, as also explained below, while we
    agree with Raytheon that the Board’s construction of
    “second substrate” is erroneous, that issue is rendered
    moot in view of our holding.
    A. The Board’s Liu-Based Findings
    The Board found appealed claims 5, 13–14, and 16–18
    obvious over Liu in view of other prior art of record. See
    209 Decision, 2016 Pat. App. LEXIS 13045, at *33–63.
    Obviousness is a question of law based on underlying
    factual findings relating to “the scope and content of the
    prior art, differences between the prior art and the claims
    at issue, the level of ordinary skill in the pertinent art,
    and any objective indicia of non-obviousness.” Randall
    Mfg. v. Rea, 
    733 F.3d 1355
    , 1362 (Fed. Cir. 2013) (citing
    KSR Int’l Co. v. Teleflex Inc., 
    550 U.S. 398
    , 406 (2007)).
    We review the Board’s ultimate legal determination of
    obviousness de novo and its underlying factual findings
    for substantial evidence. PPC Broadband, Inc. v. Corning
    Optical Commc’ns RF, LLC, 
    815 F.3d 747
    , 751 (Fed. Cir.
    2016). Substantial evidence is “such relevant evidence as
    a reasonable mind might accept as adequate to support a
    conclusion.” In re Gartside, 
    203 F.3d 1305
    , 1312 (Fed.
    RAYTHEON COMPANY    v. SONY CORPORATION                      7
    Cir. 2000) (quoting Consol. Edison Co. of N.Y. v. N.L.R.B.,
    
    305 U.S. 197
    , 229 (1938)).
    As described above, Liu describes a multi-layer CCD
    for detecting electromagnetic radiation.            While Liu
    acknowledges that silicon devices are “adequate for many
    applications,” it states that silicon-based devices are
    unsuitable for “some specific applications,” including “star
    sensors which require extremely low dark currents and
    high optical responsivity.” Liu, col. 1, ll. 15–26. Liu
    teaches that these objectives—which comprise just two of
    Liu’s six objects of the invention—are “not likely to be
    realized simultaneously” in silicon-based CCDs. 
    Id. col. 1,
    ll. 25–26; 
    id. col. 1,
    l. 59 to col. 2, l. 6. Liu therefore em-
    ploys gallium arsenide, rather than silicon, for its devices.
    Pointing to these passages, Raytheon argues that us-
    ing silicon in Liu’s CCDs would defeat Liu’s primary
    objectives of achieving low dark current and high optical
    responsivity, which, in turn, would render Liu’s devices
    inoperable for their intended purpose. Appellant Br. 52–
    54 (citing In re Gordon, 
    733 F.2d 900
    (Fed. Cir. 1984)).
    For this reason, Raytheon argues, a skilled artisan would
    not be motivated to combine Liu with secondary refer-
    ences that teach using silicon in semiconductor devices.
    Raytheon contends that the Board failed to address this
    argument in its final written decision. We disagree.
    Raytheon’s inoperability argument is a slight varia-
    tion of the argument that the Board squarely addressed.
    The Board found that Liu’s statement that silicon can
    hamper performance in CCDs for “some specific applica-
    tions”—i.e., for star sensors—does not teach away from
    using silicon in CCDs for other applications, including
    microelectronics applications. See 209 Decision, 2016 Pat.
    App. LEXIS 13045, at *43–45. Indeed, as the Board
    noted, Liu expressly teaches that silicon in semiconductor
    systems was generally known. 
    Id. at *44
    (citing Liu, col.
    1, ll. 16–17; 
    id. col. 5,
    ll. 9–10). And, relying in part on
    8                  RAYTHEON COMPANY    v. SONY CORPORATION
    Sony’s petition and expert’s declaration, the Board found
    that, because “the vast majority of devices [at the time]
    were made with silicon, Liu’s reference to silicon would
    not have convinced anyone to avoid it except for certain
    specific applications.”  
    Id. (internal quotation
    marks
    omitted).
    That Liu’s claimed invention is directed primarily to
    star sensor applications does not preclude a skilled arti-
    san from combining Liu with silicon-based references for
    different applications. “A reference must be considered
    for everything that it teaches, not simply the described
    invention or a preferred embodiment.” In re Applied
    Materials, Inc., 
    692 F.3d 1289
    , 1298 (Fed. Cir. 2012)
    (citing EWP Corp. v. Reliance Universal Inc., 
    755 F.2d 898
    , 907 (Fed. Cir. 1985)). Indeed, “[o]n the issue of
    obviousness, the combined teachings of the prior art as a
    whole must be considered.” 
    EWP, 755 F.2d at 907
    . As
    described above, Liu teaches that silicon-based devices
    were known. Thus, a skilled artisan cannot be assumed
    to ignore Liu merely because it is primarily directed to a
    specific application that is different from the application
    claimed in the patent at issue. 
    KSR, 550 U.S. at 420
    –21
    (“The idea that a designer hoping to make an adjustable
    electronic pedal would ignore Asano because Asano was
    designed to solve the constant ratio problem makes little
    sense.”). In view of Liu’s teachings and the record evi-
    dence, therefore, we conclude that the Board’s findings
    are supported by substantial evidence.
    Even if Raytheon were correct that Liu’s high optical
    responsivity and low dark current objectives would be
    thwarted by using silicon in Liu’s devices for microelec-
    tronics applications, those objectives comprise just two of
    Liu’s six stated goals. Raytheon does not explain why the
    resulting device, with just those two objectives frustrated,
    would be rendered inoperable rather than merely less
    efficient or less desirable. See Allied Erecting & Disman-
    tling Co. v. Genesis Attachments, LLC, 
    825 F.3d 1373
    ,
    RAYTHEON COMPANY    v. SONY CORPORATION                     9
    1381 (Fed. Cir. 2016) (“Although modification of the
    movable blades may impede the quick change functionali-
    ty disclosed by Caterpillar, ‘[a] given course of action often
    has simultaneous advantages and disadvantages, and this
    does not necessarily obviate motivation to combine.’”
    (quoting Medichem, S.A. v. Rolabo, S.L., 
    437 F.3d 1157
    ,
    1165 (Fed. Cir. 2006)). Raytheon’s inoperability argu-
    ment therefore fails on its own terms.
    Substantial evidence supports the Board’s finding
    that a skilled artisan would have been motivated to use
    silicon material with Liu’s CCD semiconductors in non-
    star sensor applications. We therefore affirm the Board’s
    determination that Liu renders appealed claims 5, 13–14,
    and 16–18 of the ’678 patent obvious.
    B. The Board’s Bertin-Based Findings
    The Board also found appealed claims 5 and 13 obvi-
    ous over Bertin in view of Morimoto. See 1201 Decision,
    2016 Pat. App. LEXIS 13452, at *43–48. Raytheon does
    not challenge the Board’s finding that Bertin and
    Morimoto collectively disclose every limitation recited in
    those claims, or that a skilled artisan would have been
    motivated to combine the references. Instead, Raytheon
    argues only that Bertin is not prior art because the inven-
    tors reduced to practice the claimed subject matter before
    Bertin’s filing date. Again, we disagree.
    To antedate a prior art reference, a patentee must es-
    tablish that it invented the subject matter recited in the
    patent claims before the reference’s priority date. That,
    in turn, can be established by showing “either an earlier
    reduction to practice, or an earlier conception followed by
    a diligent reduction to practice.” Purdue Pharma L.P. v.
    Boehringer Ingelheim GmbH, 
    237 F.3d 1359
    , 1365 (Fed.
    Cir. 2001). A party seeking to establish an actual reduc-
    tion to practice, as here, must satisfy a two-prong test:
    (1) the party must construct an embodiment or perform a
    process that satisfies every element of the claim at issue,
    10                 RAYTHEON COMPANY     v. SONY CORPORATION
    and (2) the embodiment or process must operate for its
    intended purpose. In re Steed, 
    802 F.3d 1311
    , 1318 (Fed.
    Cir. 2015); Cooper v. Goldfarb, 
    154 F.3d 1321
    , 1327 (Fed.
    Cir. 1998). “The inventor must also have ‘contemporane-
    ous recognition and appreciation of the invention’ repre-
    sented by the claims.” 
    Purdue, 237 F.3d at 1365
    –66.
    Significantly, an inventor’s testimony alone is insuffi-
    cient to establish an earlier reduction to practice. Medi-
    
    chem, 437 F.3d at 1169
    –71. Instead, a party seeking to
    prove an actual reduction to practice must proffer evi-
    dence corroborating that testimony. 
    Id. at 1170.
    “Suffi-
    ciency of corroboration is determined by using a ‘rule of
    reason’ analysis, under which all pertinent evidence is
    examined when determining the credibility of an inven-
    tor’s testimony.” Id.; 
    Cooper, 154 F.3d at 1330
    . Whether
    a patentee reduced its invention to practice is a mixed
    question of law and fact. REG Synthetic Fuels, LLC v.
    Neste Oil Oyj, 
    841 F.3d 954
    , 958 (Fed. Cir. 2016); 
    Steed, 802 F.3d at 1318
    –20; 
    Cooper, 154 F.3d at 1327
    . We
    review the Board’s legal conclusions de novo and its
    underlying factual findings for substantial evidence.
    
    REG, 841 F.3d at 958
    ; 
    Steed, 802 F.3d at 1318
    –20;
    
    Cooper, 154 F.3d at 1327
    .
    Much of the parties’ briefing and supporting evidence
    related to Raytheon’s reduction to practice contention are
    designated confidential. Accordingly, we do not describe
    these documents in detail here. For purposes of our
    analysis, it is sufficient to address Raytheon’s arguments
    at a high level of generality. During the IPR proceedings,
    the inventors testified that they reduced to practice the
    subject matter recited in the claims by the end of 1990—
    more than nine months before Bertin’s September 1991
    filing date—while working on a project for their employer
    and original assignee, Hughes Aircraft Company.
    Raytheon relies on a March 1991 internal report to
    corroborate that testimony. As the Board found, however,
    RAYTHEON COMPANY    v. SONY CORPORATION                   11
    the report indicates that one of the claimed steps had not
    yet been completed by December 1990. The report states,
    for example, that the particular structure referenced in
    the report was an “intended structure,” and that a con-
    stituent structure was “awaiting” a process step and
    testing critical to one of the claim limitations. 2 J.A. 241–
    42 (emphases added). The Board concluded that these
    statements imply that Hughes expected to complete the
    claimed step in the future, contrary to the inventors’
    testimony. 1201 Decision, 2016 Pat. App. LEXIS 13452,
    at *36–38. Based on our careful review of the report, the
    inventor testimony, and the balance of the record on
    appeal, we conclude that substantial evidence supports
    the Board’s finding that the report contradicts the inven-
    tors’ testimony and therefore cannot corroborate such
    testimony.
    We reject, moreover, Raytheon’s legal arguments as to
    why the Board erred. First, Raytheon argues that the
    Board erred by requiring every point of the reduction to
    practice be disclosed in the corroborating evidence, which
    Raytheon contends is inconsistent with the rule of reason
    standard. Raytheon is correct that corroborating evidence
    need not disclose each and every aspect of the claimed
    invention. See 
    Cooper, 154 F.3d at 1331
    (“[T]he law does
    not impose an impossible standard of independence on
    corroborative evidence by requiring that every point of a
    2   The report also states that Hughes “will empha-
    size continuing” development related to the claimed goals
    in early 1991, J.A. 242 (emphasis added), but does not
    indicate that such goals were ever achieved. And, alt-
    hough the report states that Hughes “completed the
    design and layout of” a particular structure, it states that
    Hughes only “continued development” of a relevant step
    in the claimed process. J.A. 238; J.A. 241 (emphasis
    added).
    12                 RAYTHEON COMPANY    v. SONY CORPORATION
    reduction to practice be corroborated by evidence having a
    source totally independent of the inventor[.]” (internal
    quotation marks omitted)); see also Fleming v. Escort Inc.,
    
    774 F.3d 1371
    , 1377 (Fed. Cir. 2014). But the Board did
    not require such proof here. As described above, the
    Board determined that the corroborating evidence contra-
    dicted the inventor’s testimony and therefore could not be
    sufficiently corroborative. This conclusion is reasonable
    in view of the evidence. Cf. Woodland Tr. v. Flowertree
    Nursery, Inc., 
    148 F.3d 1368
    , 1371 (Fed. Cir. 1998) (ex-
    plaining that, in evaluating the rule of reason, courts take
    into account “contradiction or impeachment of the wit-
    ness’ testimony”).
    Second, Raytheon argues that the Board erroneously
    required that the corroborating evidence itself be corrobo-
    rated. To support that argument, Raytheon points to
    specific language in the Board’s final written decision in
    which it stated that “there is no corroborating evidence
    that” a particular structure described in the report was
    “constructed or tested in 1990.” 1201 Decision, 2016 Pat.
    App. LEXIS 13452, at *36. That statement, however,
    does not fault Raytheon for failing to proffer evidence that
    corroborates the corroborating evidence. Instead, it faults
    Raytheon for failing to proffer evidence that sufficiently
    corroborates the inventors’ testimony that they completed
    all claimed steps by the end of 1990. In other words, the
    Board’s statement merely declares that the report is not
    itself sufficiently corroborative, and that Raytheon prof-
    fered no other evidence to fill the gap. 3 Similarly, the
    3  Before the Board, Raytheon also relied on an
    August 1990 invention disclosure and a November 1990
    white paper. On appeal, however, Raytheon disclaims
    reliance on those documents. See Appellant Br. 15 n.8;
    Oral Argument at 12:28–13:35, Raytheon Co. v. Sony
    Corp. (No. 2017-1554), http://oralarguments.cafc.uscourts.
    RAYTHEON COMPANY   v. SONY CORPORATION                  13
    Board did not require that Raytheon’s expert’s testimony
    be corroborated. Rather, the Board determined that his
    testimony was not credible in view of the report’s contrary
    statements.
    Third, Raytheon asserts that the Board improperly re-
    lied on Sony’s attorney argument interpreting the report.
    This assertion has little force given the plain language of
    the report, which, on its face, contradicts the inventor
    testimony.
    Substantial evidence supports the Board’s findings,
    and we therefore affirm the Board’s determination that
    Raytheon failed to antedate Bertin, and that Bertin also
    renders appealed claims 5 and 13 of the ’678 patent
    obvious.
    C. The Board’s Construction of “second substrate”
    and Morimoto-Based Findings
    In view of our holding above affirming the Board’s
    Liu- and Bertin-based obviousness determinations as to
    claims 5, 13–14, and 16–18, we need not reach Raytheon’s
    final argument regarding the Board’s Morimoto-based
    obviousness determination as to those same claims. As
    explained below, however, we agree with Raytheon that
    the Board’s determination on that prior art reference is
    predicated on an erroneous claim construction.
    The Board found appealed claims 5, 13–14, and 16–18
    obvious over Morimoto, either standing alone or in view of
    other prior art of record. See 1201 Decision, 2016 Pat.
    App. LEXIS 13452, at *48–68. That determination was
    predicated on the Board’s construction of the claimed
    “second substrate” limitation. The Board noted that the
    term’s plain meaning “is merely another substrate (i.e., in
    gov/default.aspx?fl=2017-1554.mp3 (“[W]e limited        the
    scope of the evidence that we’re relying upon.”).
    14                  RAYTHEON COMPANY     v. SONY CORPORATION
    addition to the claimed ‘first substrate’).” J.A. 166 (insti-
    tution decision). In view of that broad meaning and the
    claims’ “comprising” transition, the Board determined
    that the second substrate need not remain part of the
    final device, and that the claim limitation therefore
    encompasses Morimoto’s temporary substrate, which is
    removed during fabrication. 1201 Decision, 2016 Pat.
    App. LEXIS 13452, at *10–12, 49–62.
    Raytheon argues that the Board’s construction is too
    broad, and that the correct construction requires that the
    second substrate remain attached to the device through-
    out the fabrication process and in the final product. We
    agree.
    Where, as here, an IPR involves an expired patent,
    the Board gives the claims their plain meaning in accord-
    ance with the standard set forth in Phillips v. AWH Corp.,
    
    415 F.3d 1303
    (Fed. Cir. 2005) (en banc). See Wasica Fin.
    GmbH v. Cont’l Auto. Sys., Inc., 
    853 F.3d 1272
    , 1279–80
    (Fed. Cir. 2017).
    The plain language of the ’678 patent claims states
    that the wafer of the first substrate is “attach[ed] . . . to a
    second substrate,” and that a portion of the first substrate
    is thereafter “etch[ed] away.” ’678 patent, col. 8, ll. 13–16.
    The claims say nothing about subsequently removing the
    second substrate, and, in the absence of such language,
    the reasonable inference is that the substrate is not
    removed once attached. Further, although the claims
    make clear that the first substrate is partially removed
    during fabrication via etching, they do not recite similar
    language with respect to the second substrate. This
    omission suggests that the second substrate is not, in fact,
    removed. Cf. Rodime PLC v. Seagate Tech., Inc., 
    174 F.3d 1294
    , 1305 (Fed. Cir. 1999) (“Had Rodime intended or
    desired to claim thermal compensation as a function of
    the positioning means in the asserted claims, it could
    have done it explicitly, as in claim 11. The absence of any
    RAYTHEON COMPANY     v. SONY CORPORATION                     15
    such explicit language, however, shows that claims 3, 5,
    and 8 do not include the function of thermal compensa-
    tion.”).
    The specification amply supports this reading. First,
    every embodiment described in the specification includes
    the second substrate. Box 30 of Figure 1, for example,
    depicts a representative embodiment, and shows the
    second substrate 58 present in the “complete device”
    manufactured using the claimed method:
    ’678 patent, fig.1 (box 30). And, although the specification
    explains that additional layers may be added to the device
    after the second substrate is attached, see, e.g., 
    id. col. 6,
    ll. 50–58, it never suggests that the second substrate may
    be removed. This is particularly significant because the
    specification emphasizes the temporary nature of other
    layers within the device. See, e.g., 
    id. col. 3,
    ll. 12–14
    (“With the circuit element thus supported, the etchable
    portion of the first substrate is removed by etching, down
    to the etch-stop layer.” (emphasis added)); 
    id. col. 5,
    ll. 47–
    51 (describing a base layer as being “temporarily at-
    tached” to the device and eventually “removed” (emphasis
    added)). The specification describes, moreover, a method
    of fabricating a three-dimensional device containing
    multiple layers of stacked semiconductors. See 
    id. col. 1,
    ll. 45–49; 
    id. col. 2,
    ll. 37–42; 
    id. col. 7,
    ll. 61–65. Without
    the second substrate, the device would contain just a
    single wafer layer and circuitry, which the patent de-
    scribes as a “two-dimensional structure.” See 
    id. col. 1,
    ll.
    15–23 (explaining that a device having only “an electronic
    16                   RAYTHEON COMPANY      v. SONY CORPORATION
    circuit on or near the top surface of a thin substrate wafer
    . . . is considered a two-dimensional structure in the plane
    of the substrate wafer”). These passages suggest that the
    second substrate is not removed.
    Second, the specification makes clear that one of the
    purposes of the second substrate is to protect the fragile
    wafer during fabrication. See 
    id. col. 1,
    ll. 11–13; 
    id. col. 1,
    l. 58 to col. 2, l. 2; 
    id. col. 2,
    l. 59 to col. 3, l. 14. This
    purpose is facilitated by transferring the microelectronic
    circuit elements from the first substrate to the second
    substrate. See, e.g., 
    id. col. 3,
    ll. 6–8 (“In the present
    approach, after initial circuit element fabrication on a
    first substrate structure, the electrical circuit element is
    transferred to a second substrate structure.”); see also 
    id. col. 1,
    ll. 11–13; 
    id. col. 2,
    ll. 59–61. In other words, the
    second substrate protects the circuitry and wafer
    throughout fabrication, even as subsequent layers are
    added to the back side of the structure. That purpose
    implies that the second substrate is not temporary, but
    instead remains within the device. See 
    id. col. 3,
    ll. 2–5
    (explaining that, in the absence of a second substrate,
    “[t]he first substrate cannot simply be removed to permit
    access to the bottom side of the electrical circuit element,
    as the assembly could not be handled in that very thin
    form”). The claims must be read in view of the specifica-
    tion’s “consistent emphasis on this fundamental feature of
    the invention.” Praxair, Inc. v. ATMI, Inc., 
    543 F.3d 1306
    ,
    1324 (Fed. Cir. 2008).
    Third, the only passage in the specification that de-
    scribes how the second substrate is attached to the wafer
    states that epoxy glue is preferably used. See 
    id. col. 5,
    ll.
    33–38. As the patent explains, such glue, when degassed
    and cured, “is resistant to chemical attack” and therefore
    provides a “permanent attachment.” 
    Id. In other
    words,
    the epoxy glue used in the preferred embodiment ensures
    that the second substrate remains permanently affixed to
    the electrical device. Epoxy glue need not be used, of
    RAYTHEON COMPANY     v. SONY CORPORATION                      17
    course, but its reference in the specification suggests that
    whatever adhesive is used must ensure that the second
    substrate is permanently attached.
    Finally, the specification explains that the second
    substrate may itself possess circuitry that can be electri-
    cally connected to the first substrate’s circuitry. See, e.g.,
    
    id. at Abstract;
    id. col. 2, 
    ll. 24–28; 
    id. col. 5,
    ll. 38–44. It
    would be illogical and inefficient to add circuitry to the
    second substrate and establish electrical connections
    between the two substrates, only to remove the second
    substrate from the device. In sum, the ’678 patent speci-
    fication makes clear that the second substrate is not
    removed. 4
    The Board did not consider these, or any other, pas-
    sages of the specification. Instead, it focused solely on the
    “comprising” transition in the claims’ preambles, finding
    that the open-ended transition allows for subsequent
    removal of the second substrate. 1201 Decision, 2016 Pat.
    App. LEXIS 13452, at *10; J.A. 166–67 (institution deci-
    sion). It is true, of course, that “the use of ‘comprising’
    creates a presumption that the body of the claim is open.”
    Crystal Semiconductor Corp. v. TriTech Microelecs. Int’l,
    Inc., 
    246 F.3d 1336
    , 1348 (Fed. Cir. 2001); Genentech, Inc.
    v. Chiron Corp., 
    112 F.3d 495
    , 501 (Fed. Cir. 1997)
    (“‘Comprising’ is a term of art used in claim language
    which means that the named elements are essential, but
    other elements may be added and still form a construct
    4   We recognize that the claims at issue are method
    claims, and that it would be improper to read apparatus
    limitations pertaining to the final device into the claims.
    But we do not embark down that road. Rather, our con-
    struction addresses the manner in which the second
    substrate is attached during the fabrication process. In
    other words, we interpret the claimed “attaching . . . a
    second substrate” step to require permanent attachment.
    18                 RAYTHEON COMPANY    v. SONY CORPORATION
    within the scope of the claim.”). But, the term “compris-
    ing” does not displace, or otherwise allow one to disre-
    gard, the patent specification. As we repeatedly have
    emphasized, the claims must be read in view of the speci-
    fication, which “is always highly relevant to the claim
    construction analysis” and is “the single best guide to the
    meaning of a disputed term.” Indacon, Inc. v. Facebook,
    Inc., 
    824 F.3d 1352
    , 1355 (Fed. Cir. 2016) (quoting Phil-
    
    lips, 415 F.3d at 1315
    ). This fundamental precept is no
    less true for “comprising” claims than it is for other types
    of claims. See In re Suitco Surface, Inc., 
    603 F.3d 1255
    ,
    1260 (Fed. Cir. 2010) (stating that the Board’s construc-
    tion of a claim reciting a “comprising” limitation must be
    “consistent with the specification” (internal quotation
    marks omitted)).
    A “comprising” transition, moreover, is “not a weasel
    word with which to abrogate claim limitations” and “does
    not reach into each of the . . . steps to render every word
    and phrase therein open-ended.” Dippin’ Dots, Inc. v.
    Mosey, 
    476 F.3d 1337
    , 1343 (Fed. Cir. 2007). Indeed, the
    word “‘[c]omprising,’ while permitting additional elements
    not required by a claim, does not remove the limitations
    that are present.” Power Mosfet Techs., L.L.C. v. Siemens
    AG, 
    378 F.3d 1396
    , 1409 (Fed. Cir. 2004) (emphases
    added); cf. In re Skvorecz, 
    580 F.3d 1262
    , 1268 (Fed. Cir.
    2009) (“The signal ‘comprising’ does not render a claim
    anticipated by a device that contains less (rather th[a]n
    more) than what is claimed.”).
    Here, the ’678 patent claims and specification clearly
    impose a limitation on the claim term “second substrate,”
    requiring permanent attachment throughout the fabrica-
    tion process. Morimoto’s additional step of removing the
    second substrate vitiates that limitation because it, in
    fact, removes the substrate from the device. Accordingly,
    the claims cannot be construed so broadly as to encom-
    pass such removal. See In re Varma, 
    816 F.3d 1352
    , 1362
    (Fed. Cir. 2016) (explaining that “comprising” claims “do[]
    RAYTHEON COMPANY   v. SONY CORPORATION                  19
    not cover systems whose unclaimed features make the
    claim elements no longer satisfied”); Mitsubishi Chem.
    Corp. v. Barr Labs., Inc., 435 F. App’x 927, 935 (Fed. Cir.
    2011) (“While claim 3 is open-ended, the addition of new
    compounds to the composition that would defeat the
    ‘pharmaceutical’ character of the overall composition
    would move the composition outside the scope of the
    claimed invention.”); cf. Outside the Box Innovations, LLC
    v. Travel Caddy, Inc., 
    695 F.3d 1285
    , 1305 (Fed. Cir.
    2012) (per curiam) (“The usage [of] ‘comprising’ means
    that additional components may be present in the device,
    but does not change the elements that are stated in the
    claim.”).
    Thus, although our holding is not affected by the
    Board’s error, its interpretation of the word “comprising”
    as displacing the ’678 patent specification and vitiating
    the “second substrate” limitation is improper under the
    Phillips standard; indeed, it would be improper under any
    standard.
    III. CONCLUSION
    We have considered Raytheon’s remaining arguments
    and find them unpersuasive. For the reasons stated
    above, we affirm the Board’s ruling invalidating claims 5,
    13–14, and 16–18 of the ’678 patent as obvious.
    AFFIRMED