Trials@uspto.gov
`571-272-7822
`
` Paper No. 10
`Entered: December 15, 2017
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`MICRON TECHNOLOGY, INC.,
`Petitioner,
`
`v.
`
`LONE STAR SILICON INNOVATIONS LLC,
`Patent Owner.
`____________
`
`Case IPR2017-01560
`Patent 5,912,188
`____________
`
`Before GRACE KARAFFA OBERMANN,
`JENNIFER MEYER CHAGNON, and ELIZABETH M. ROESEL,
`Administrative Patent Judges.
`
`ROESEL, Administrative Patent Judge.
`
`DECISION
`Institution of Inter Partes Review
`37 C.F.R. § 42.108
`
`
`571-272-7822
`
` Paper No. 10
`Entered: December 15, 2017
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`MICRON TECHNOLOGY, INC.,
`Petitioner,
`
`v.
`
`LONE STAR SILICON INNOVATIONS LLC,
`Patent Owner.
`____________
`
`Case IPR2017-01560
`Patent 5,912,188
`____________
`
`Before GRACE KARAFFA OBERMANN,
`JENNIFER MEYER CHAGNON, and ELIZABETH M. ROESEL,
`Administrative Patent Judges.
`
`ROESEL, Administrative Patent Judge.
`
`DECISION
`Institution of Inter Partes Review
`37 C.F.R. § 42.108
`
`
`
`IPR2017-01560
`Patent 5,912,188
`
`
`This case concerns U.S. Patent No. 5,912,188. Ex. 1001 (“the ’188
`patent”). Petitioner, Micron Technology, Inc., filed a Petition seeking inter
`partes review of claims 1–5, 7–13, 15–23, and 25–29 of the ’188 patent.
`Paper 1 (“Pet.”). Patent Owner, Lone Star Silicon Innovations LLC, filed a
`Preliminary Response. Paper 6 (“Prelim. Resp.”).
`We have authority to determine whether to institute an inter partes
`review. 35 U.S.C. § 314; 37 C.F.R. § 42.4(a). An inter partes review may
`not be instituted “unless the Director determines . . . there is a reasonable
`likelihood that the petitioner would prevail with respect to at least 1 of the
`claims challenged in the petition.” 35 U.S.C. § 314(a). Applying that
`standard, we institute an inter partes review of claims 1–5, 8–13, 15, and
`18–20 of the ’188 patent for the reasons and on the ground set forth below.
`The following findings of fact and conclusions of law are not final,
`but are made for the sole purpose of determining whether Petitioner meets
`the threshold for initiating review. Any final decision shall be based on the
`full trial record, including any response timely filed by Patent Owner.
`
`I. BACKGROUND
`A. Related Matters
`Pursuant to 37 C.F.R § 42.8(b)(2), the parties identify the following
`patent infringement lawsuits involving the ’188 patent:
`Lone Star Silicon Innovations, LLC v. Micron Technology, Inc.,
`No. 2:16-cv-01116 (E.D. Tex. filed Oct. 7, 2016); and
`Lone Star Silicon Innovations, LLC v. Toshiba Corp., No. 2:16-
`cv-01170 (E.D. Tex. filed Oct. 14, 2016).
`Pet. 2–3; Paper 4, 2 (Patent Owner Mandatory Notices).
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`In addition, Patent Owner identifies IPR2017-01561 involving the
`’188 patent. Paper 4, 1. Patent Owner identifies additional inter partes
`review proceedings involving Micron Technology as Petitioner and Lone
`Star Silicon Innovations LLC and states that the patents involved in the
`additional proceedings are not related to the ’188 patent. Id.
`
`B. Asserted Grounds of Unpatentability
`Petitioner asserts the following grounds of unpatentability under
`35 U.S.C. § 103(a):
`
`Reference(s)
`
`Claim(s)
`
`Hashimoto1
`
`Hashimoto and Sung2
`
`Hashimoto and Kawai3
`
`1–5, 8–13, 15, 18, and 19
`
`20
`
`7, 16, 17, 21–23, and 25–27
`
`Hashimoto, Sung, and Kawai
`
`28 and 29
`
`
`Pet. 4. Petitioner supports its challenge with a Declaration of Richard Fair,
`Ph.D. Ex. 1003. Patent Owner supports its Preliminary Response with a
`Declaration of W. R. Bottoms, Ph.D. Ex. 2001.
`
`
`1 Hashimoto et al., Japanese Patent Publication No. JP H9-64297, published
`March 7, 1997, with certified English translation, Ex. 1005 (“Hashimoto”).
`Hashimoto is asserted as prior art under 35 U.S.C. § 102(b). Pet. 18 n.3.
`2 Sung, US 5,550,078, filed June 28, 1995 and issued August 27, 1996,
`Ex. 1006 (“Sung”). Sung is asserted as prior art under 35 U.S.C. § 102(a)
`and (e). Pet. 24 n.4.
`3 Kawai et al., Japanese Patent Publication No. JP H8-46173, published
`February 16, 1996, with certified English translation, Ex. 1007 (“Kawai”).
`Kawai is asserted as prior art under 35 U.S.C. § 102(b). Pet. 26 n.5.
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`C. The ’188 Patent (Ex. 1001)
`The ’188 patent was issued June 15, 1999 from Application No.
`08/905,686, filed August 4, 1997. Ex. 1001, [45], [21], [22].
`The ’188 patent relates to integrated circuit manufacturing, and more
`specifically, to a method of forming a contact hole in an interlevel dielectric
`layer using dual etch stops. Id. at [54], [57], 1:7–10.
`The ’188 patent addresses the problem of overetching and gouging of
`underlying materials when forming contact holes. Id. at 2:29–50, 2:65–67,
`3:2–4. According to the ’188 patent, one known solution is an interlevel
`dielectric layer with a thick silicon dioxide layer on a thin silicon nitride
`layer and a two-step etching process, whereby the first etch is highly
`selective of silicon dioxide with respect to silicon nitride. Id. at 2:51–56.
`The ’188 patent states that this approach has a drawback in that the second
`etch is highly selective of both silicon nitride and silicon and may cause
`substantial damage to an underlying silicon surface. Id. at 2:58–63.
`The solution proposed by the ’188 patent is an interlevel dielectric
`with first, second, and third dielectric layers and a three-step etching
`process, whereby the first dielectric layer is etched using the second
`dielectric layer as an etch stop, and the second dielectric layer is etched
`using the third dielectric layer as an etch stop. Id. at 3:4–10.
`Figures 1A–1J of the ’188 patent illustrate process steps for forming a
`contact hole in an interlevel dielectric. Id. at 4:17–20. Figures 1D through
`1G are reproduced below:
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`Figures 1D through 1G of the ’188 patent illustrate process steps for forming
`a contact hole in an interlevel dielectric. Ex. 1001, 4:17–20. Figure 1D
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`shows interlevel dielectric layer 146, including silicon oxide layer 140,
`silicon nitride layer 142, and silicon oxide layer 144. Id. at 5:31–54. The
`interlevel dielectric layer is formed on a silicon substrate having active
`regions separated by trench oxide 106. Id. at 4:29–38, 5:31–54. Each active
`region includes a gate oxide layer and a gate, which are formed on the
`substrate, and source and drain regions, which are formed in the substrate.
`Id. at 4:44–5:30. Patterned photoresist layer 148 is formed on silicon oxide
`layer 144 to define contact holes. Id. at 5:59–67.
`Figure 1E shows the result of a first etching step. According to the
`’188 patent, “a long anisotropic reactive ion etch is applied that is highly
`selective of silicon dioxide with respect to silicon nitride using photoresist
`layer 148 as an etch mask and using nitride layer 142 as an etch stop” to
`form holes in oxide layer 144 that extend to nitride layer 142. Id. at 6:1–5.
`Figure 1F shows the result of a second etching step. According to the
`’188 patent, “the etch chemistry is changed and a brief anisotropic reactive
`ion etch is applied that is highly selective of silicon nitride with respect to
`silicon dioxide using photoresist layer 148 as an etch mask and using oxide
`layer 140 as an etch stop” to form holes in nitride layer 142 that extend to
`oxide layer 140. Id. at 6:14–19.
`Figure 1G shows the result of a third etching step. According to the
`’188 patent, “the etch chemistry is changed again and a brief anisotropic
`reactive ion etch is applied that is highly selective of silicon dioxide with
`respect to silicon nitride using photoresist layer 148 as an etch mask.” Id. at
`6:25–28.
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`After completion of the etching steps, the photoresist layer is stripped,
`conductive plugs are formed in the contact holes, and a metal-1 pattern is
`formed in contact with the conductive plugs. Id. at 6:48–7:19, Figs. 1H–1J.
`
`D. Illustrative Claim
`The ’188 patent includes 30 claims. Claims 1, 11, and 21 are
`independent. Ex. 1001, 8:57–12:35. Claims 1–5, 7–13, 15–23, and 25–29
`are challenged in the Petition. Pet. 1. Claim 1 is illustrative of the
`challenged claims and is reproduced below:
`1. A method of forming a contact hole in an interlevel
`dielectric layer using dual etch stops, comprising:
`providing a semiconductor substrate;
`forming a gate over the substrate,
`forming a source/drain region in the substrate;
`providing a source/drain contact electrically coupled to the
`source/drain region;
`forming an interlevel dielectric layer that includes first,
`second and third dielectric layers over the source/drain contact;
`forming an etch mask over the interlevel dielectric layer;
`applying a first etch which is highly selective of the first
`dielectric layer with respect to the second dielectric layer through
`an opening in the etch mask using the second dielectric layer as
`an etch stop, thereby forming a first hole in the first dielectric
`layer that extends to the second dielectric layer without
`extending to the third dielectric layer;
`applying a second etch which is highly selective of the
`second dielectric layer with respect to the third dielectric layer
`through the opening in the etch mask using the third dielectric
`layer as an etch stop, thereby forming a second hole in the second
`dielectric layer that extends to the third dielectric layer without
`extending to the source/drain contact; and
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`applying a third etch which is highly selective of the third
`dielectric layer with respect to the source/drain contact through
`the opening in the etch mask, thereby forming a third hole in the
`third dielectric layer that extends to the source/drain contact,
`wherein the first, second and third holes in combination provide
`a contact hole in the interlevel dielectric layer.
`Ex. 1001, 8:57–9:22.
`
`II. DISCUSSION
`
`A. Claim Construction
`Petitioner asserts that the ʼ188 patent will expire during this
`proceeding and the claim construction principles of Phillips should be
`applied, rather than the broadest reasonable interpretation applicable to
`non-expired patents. Pet. 14 (referring to Phillips v. AWH Corp., 415 F.3d
`1303 (Fed. Cir. 2005) (en banc)). Patent Owner does not dispute Petitioner’s
`assertion. See Prelim. Resp. 14 (addressing claim interpretation).
`By our calculation, the ’188 patent expired on August 4, 2017. For
`expired patents, we apply the claim construction standard set forth in
`Phillips. See In re Rambus, Inc., 694 F.3d 42, 46 (Fed. Cir. 2012) (“the
`Board’s review of the claims of an expired patent is similar to that of a
`district court’s review”); see also Black & Decker, Inc. v. Positec USA, Inc.,
`646 Fed. App’x 1019, 1024 (Fed. Cir. 2016) (holding that in an inter partes
`review, “[c]laims of an expired patent are given their ordinary and
`customary meaning in accordance with our opinion in [Phillips]”).
`Under the Phillips standard, claim terms are given their ordinary and
`customary meaning, as would have been understood by a person of ordinary
`skill in the art at the time of the invention, in light of the language of the
`claims, the specification, and the prosecution history of record. Phillips,
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`415 F.3d at 1312–19; Thorner v. Sony Comput. Entm’t Am. LLC, 669 F.3d
`1362, 1365–66 (Fed. Cir. 2012).
`Below we address the term “anisotropic etch.” No other claim term
`requires express construction for purposes of this Decision. Vivid Techs.,
`Inc. v. Am. Sci. & Eng’g, Inc., 200 F.3d 795, 803 (Fed. Cir. 1999).
`
`“anisotropic etch”
`The term “anisotropic etch” appears in each of claims 3, 11, and 21.
`Although neither party proposes an express construction for “anisotropic
`etch,” the parties’ arguments implicitly address the meaning of the term.
`In applying the cited art to the challenged claims, Petitioner contends
`that the use of an “anisotropic etch” is indicated by production of straight
`sidewalls without undercutting of the etch mask. Pet. 48 (citing Ex. 1003
`¶ 145).4
`Patent Owner does not dispute Petitioner’s implicit interpretation.
`Instead, Patent Owner argues that an “anisotropic etch” is one that “removes
`material almost exclusively in a downward direction and not in the sideways
`or radial direction.” Prelim. Resp. 9 (citing Ex. 2001 ¶ 39). Patent Owner
`further argues that “[a]nisotropic etching, by definition, is directional—and
`typically etches only the horizontal surfaces of the subject layers.” Id. at 22
`(citing Ex. 2001 ¶ 61.)
`
`
`4 Exhibit 1003 has a paragraph numbering defect starting with what should
`be paragraph 84 on page 35. As a result of this defect, the paragraph
`numbers of Exhibit 1003 do not always match the paragraph numbers as
`cited in the Petition. In citing to Exhibit 1003, we refer to the paragraph
`numbers as cited in the Petition. Petitioner is directed to file a replacement
`for Exhibit 1003 using the same exhibit number to correct the paragraph
`numbering on pages 35–97 of the exhibit, as set forth in the Order.
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`Turning first to the intrinsic evidence, the term “anisotropic etch” is
`used in claims 3, 11, and 21 to describe first, second, and third etches.
`Ex. 1001, 9:26–28 (dependent claim 3); id. at 10:2–22 (claim 11); id. at
`11:9–33 (claim 21). These etches form first, second, and third holes,
`respectively, which in combination provide a contact hole in the interlevel
`dielectric layer. Id.; see also id. at 9:2–22 (claim 1).
`We find that the following passages from the ’188 patent are helpful
`in determining the meaning of “anisotropic”:
`When contact holes are larger than about 2.0 microns, wet
`etching is often used. However, the isotropic nature of wet
`chemical etching makes it generally unsuitable for patterning
`submicron contact holes. Since the first interlevel dielectric is
`typically silicon dioxide, dry etching for silicon dioxide is often
`used to form submicron contact holes.
`Dry etching silicon dioxide typically involves a plasma
`etching procedure in which a plasma generates reactive gas
`species that chemically etch the material in direct proximity to
`the plasma. The ability to achieve anisotropic etching requires
`bombardment of the silicon dioxide with energetic ions. Other
`parameters such as the chemical nature of the plasma also
`influence the degree of anisotropy. In general, the etch is highly
`anisotropic and forms contact holes with straight vertical
`sidewalls that taper slightly.
`Ex. 1001, 1:54–2:2.
`third etches are preferably
`The first, second and
`anisotropic etches so that the contact holes have straight
`sidewalls that do not undercut the etch mask. However, when
`the second and third dielectric layers are thin, the second and
`third etches can be brief wet chemical etches that cause little or
`no undercutting.
`Id. at 8:22–27.
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`The foregoing passages indicate that dry etching under certain
`conditions produces an “anisotropic etch.” Id. at 1:54–2:2, 8:22–27. The
`foregoing passages further indicate that an “anisotropic etch” forms contact
`holes with straight, nearly vertical sidewalls, with no undercutting of the
`etch mask. Id. The passage from column one indicates that, whether an etch
`is isotropic or anisotropic is not a binary determination. Instead, the ’188
`patent teaches that anisotropy is a matter of degree, which is influenced by
`factors such as the energy level of ions and the chemical nature of the
`plasma. Id. at 1:61–2:2.
`The prosecution history of the ’188 patent also sheds light on the
`meaning of “anisotropic etch.” During prosecution, Applicants
`distinguished claims 3, 11, and 21 from the cited art5 based on the
`“anisotropic etch” limitation of the claims. Ex. 1002, 61. Applicants argued
`that only Figures 8B and 8E of Ogawa show an “anisotropic etch” and that
`at least one step in each embodiment of Ogawa requires an isotropic etch to
`undercut an overlying layer. Id.
`Ogawa Figures 8B through 8E are reproduced below:
`
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`5 Ogawa et al., US 5,275,972, issued January 4, 1994, Ex. 3001 (“Ogawa”).
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`Figures 8B through 8E of Ogawa show process steps in a method of forming
`contact holes. Ex. 3001, 1:12–16, 7:58–61. According to Ogawa, Figures
`8B, 8D, and 8E show “anisotropic dry etching” or “anisotropic etching.” Id.
`at 13:33–37, 14:18–20, 14:41–48. Figure 8C, on the other hand, is described
`as showing “isotropic dry etching.” Id. at 13:56–61. Whereas Ogawa
`Figure 8C shows undercutting of etch mask 3, Figures 8B, 8D, and 8E show
`etching steps that result in straight sidewalls with no undercutting of the etch
`mask. Id. at Figs. 8B–8E. The prosecution history thus supports that an
`“anisotropic etch” results in straight sidewalls with no undercutting of the
`etch mask.
`Next we turn to extrinsic evidence. Webster’s New World College
`Dictionary defines “anisotropic” in the field of physics as “having
`properties, such as conductivity or speed of transmission of light, etc., that
`vary according to the direction in which they are measured.”
`http://www.yourdictionary.com/anisotropic (accessed October 20, 2017),
`Ex. 3002. In the context of etching, etch rate is a property that may vary
`according to the direction in which it is measured. When horizontal surfaces
`are etched at a higher rate than vertical surfaces, then the etch may be
`characterized as anisotropic, consistent with the foregoing dictionary
`definition.
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`Patent Owner’s declarant, Dr. Bottoms, testifies that the ’188 patent
`contrasts “highly anisotropic” dry etching with “isotropic” wet etching.
`Ex. 2001 ¶ 39 (citing Ex. 1001, 1:54–60). In addition, Dr. Bottoms testifies
`as follows regarding the meaning of “anisotropic etch” in the ’188 patent:
`Although the ’188 patent discloses anisotropic etching
`using a plasma etching procedure, a person having ordinary skill
`in the art would recognize that every plasma etch would have
`some
`isotropic
`characteristics
`and
`some
`anisotropic
`characteristics. The etch characteristics (i.e., isotropic versus
`anisotropic) depend upon multiple parameters
`including
`pressure, flow rate, plasma power, etchant gas, all of which can
`be controlled to form contact holes with certain desired
`characteristics. In view of the ’188 patent’s disclosure that the
`etch “forms contact holes with straight vertical sidewalls that
`taper slightly,” the person having ordinary skill in the art would
`recognize that the disclosed anisotropic etch removes material
`almost exclusively in a downward direction, and not in the
`sideways or radial direction.
`Id. Dr. Bottoms’ testimony is consistent with our finding that anisotropy is
`not a binary determination, but a matter of degree.
`Taking into account both the intrinsic and extrinsic evidence, we
`construe the term, “anisotropic etch,” to mean “an etch that is directional
`such that horizontal surfaces are etched at a higher rate than vertical surfaces
`and straight, nearly vertical, sidewalls without undercutting of the etch mask
`are produced.”
`Our claim construction is not final. We direct the parties to indicate
`whether or not they agree that the ’188 patent has expired and whether or not
`they agree with our claim construction. The parties may present arguments
`and evidence in support of or in opposition to our claim construction and/or
`propose modifications of that construction.
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`B. Level of Ordinary Skill in the Art
`Petitioner’s declarant, Dr. Fair, testifies that a person of ordinary skill
`in the art (“POSA”) would have had at least a Bachelor of Science degree in
`electrical engineering, chemical engineering, chemistry, physics, materials
`science, or a closely related field, along with at least five years of experience
`in semiconductor fabrication. Ex. 1003 ¶ 18. Dr. Fair further testifies that
`an individual with an advanced degree in one of these fields would require
`less experience in semiconductor fabrication. Id. Patent Owner’s declarant,
`Dr. Bottoms, testifies that a POSA would have held a master’s degree in
`physics, electrical engineering or a related field and at least three years of
`experience working with the technologies implemented in semiconductor
`devices and the fabrication of semiconductor devices. Ex. 2001 ¶ 30.
`Neither declarant indicates that any proffered opinion would change
`depending on the level of ordinary skill in the art.
`In our view, based on record presented at this stage of the proceeding,
`there is little difference between the declarants’ definitions of a POSA, and
`the outcome of our determination whether to institute review would be the
`same, regardless of which definition we accept. Nevertheless, for the sake
`of clarity and for purposes of this Decision, we accept Dr. Bottoms’
`definition of a POSA. We also rely on the cited prior art references as
`reflecting the level of ordinary skill in the art at the time of the invention.
`Okajima v. Bourdeau, 261 F.3d 1350, 1355 (Fed. Cir. 2001).
`
`C. Petitioner’s Ground 1
`Petitioner contends that claims 1–5, 8–13, 15, 18, and 19 are
`unpatentable as obvious over Hashimoto. Pet. 28–60. Patent Owner
`opposes Petitioner’s Ground 1 with respect to claims 3, 11–13, 15, 18, and
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`19. Prelim. Resp. 38–51; see also id. at 14–25 (discussing Hashimoto). The
`parties’ arguments and evidence are addressed below.
`
`1. Hashimoto (Ex. 1005)
`Hashimoto discloses a method for manufacturing a semiconductor
`device and, more specifically, a method for opening a contact hole in a
`wiring pattern. Ex. 1005, p. 2 (claim 1), ¶ 1. Hashimoto discloses forming
`three layers on a silicon substrate: a first silicon oxide-based insulating film,
`a silicon nitride film, and a second silicon oxide-based interlayer insulating
`film. Id. at p. 2 (claim 1), ¶ 6. Hashimoto discloses a three-step process for
`opening a contact hole: (1) selectively dry etching the second interlayer
`insulating film with the silicon nitride film as an etching stopper;
`(2) selectively dry etching the silicon nitride film with the silicon oxide-
`based film as an etching stopper; and (3) selectively dry etching the first
`silicon oxide-based film while preventing penetration of the silicon
`substrate. Id. at p. 2 (claims 1 and 3), ¶ 6.
`Petitioner relies on Hashimoto’s Embodiment 1, which is described in
`paragraphs 7–10 and illustrated in Figures 1(a)–(c), 4(d)–(f), and 5(g), which
`are reproduced below:
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`Hashimoto Figures 1(a)–(c), 4(d)–(f), and 5(g) illustrate a semiconductor
`manufacturing method. Ex. 1005 ¶ 7. Figure 1(a) shows silicon substrate
`41, field oxide film 42, gate oxide film 43, phosphorus-doped polycrystalline
`silicon conductive layer 44, and Non-doped Silicate Glass (“NSG”)
`insulating layer 45. Id. Hashimoto discloses that conductive layer 44 and
`NSG layer 45 are patterned to form a word line (gate) wiring pattern. Id.
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`Figure 1(b) shows NSG film 46 and ion-implanted source/drain 47. Id. ¶ 8.
`Figure 1(c) shows silicon nitride film 48. Id. Figure 4(d) shows Boron
`Phospho Silicate Glass (“BPSG”) interlayer insulation film 49 and
`photoresist/contact hole pattern 50. Figures 4(e), 4(f), and 5(g) show the
`results of first, second, and third etching steps, respectively. Id. ¶¶ 8, 9.
`Hashimoto discloses that, in the first etching step, BPSG 49 is
`removed using resist pattern 5 as an etching mask and silicon nitride film 48
`as an etch stopper. Id. ¶ 8. In the second etching step, silicon nitride film 48
`is removed without NSG film 46 being etched. Id. ¶ 9. In the third etching
`step, NSG film 46 is etched and source/drain 47 is not etched. Id. After the
`third etching step, resist pattern 50 is removed, bit contacts are formed, and
`other components are formed to complete the manufacture of a dynamic
`random access memory (“DRAM”) cell. Id.
`
`2. Claims 1, 2, 4, 5, and 8–10
`Petitioner contends that Hashimoto discloses or suggests all elements
`of claims 1, 2, 4, 5 and 8–10. Pet. 29–43, 54–58. For example, Petitioner
`contends that Hashimoto claim 3, paragraphs 8 and 9, and Figures 4(e), 4(f),
`and 5(g) disclose a first etch, a second etch, and a third etch, as recited in
`claim 1. Pet. 38–43.
`Patent Owner presents no argument opposing Petitioner’s Ground 1
`with respect to claims 1, 2, 4, 5, and 8–10.
`After considering the arguments and evidence presented in the
`Petition and Preliminary Response, we are persuaded that Petitioner has
`demonstrated a reasonable likelihood of prevailing on its contention that
`claims 1, 2, 4, 5, and 8–10 are unpatentable as obvious in view of
`Hashimoto.
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`3. Claims 3 and 11
`Claim 3 depends from claim 1 and recites “wherein the first, second
`and third etches are anisotropic etches and the contact hole has straight
`sidewalls.” Ex. 1001, 9:26–28. Claim 11 similarly recites “a first
`anisotropic etch,” “a second anisotropic etch,” and “a third anisotropic etch.”
`Id. at 10:2, 10:9, 10:16.
`Petitioner contends that the etching conditions disclosed in Hashimoto
`produce an anisotropic etch. Pet. 48 (first etch), 51–52 (second etch), 53
`(third etch). Petitioner relies on Dr. Fair’s testimony, as well as additional
`exhibits discussing anisotropic etching. Id. (citing Ex. 1003 ¶¶ 144, 152,
`159; Ex. 1009,6 5:21–26; Ex. 1010,7 1; Ex. 1015,8 4:26–40; Ex. 1016,9 4:16–
`24; Ex. 1017,10 3:41–59). Petitioner contends that Hashimoto Figures 4(e),
`4(f), and 5(g) show an anisotropic etch. Id. at 48 (first etch), 51–52(second
`etch), 53 (third etch). Petitioner further contends that it would have been
`obvious to perform Hashimoto’s etches under conditions that are
`anisotropic. Id. at 49–50, 52, 54 (citing Ex. 1003 ¶¶ 148, 155; Ex. 1010, 1).
`Patent Owner argues that Petitioner fails to show that Hashimoto’s
`etch steps are anisotropic. Prelim. Resp. 38–49.
`After considering both the Petition and Preliminary Response, we
`determine that Petitioner’s evidence is sufficient to support its contention
`
`
`6 Groechel et al., EP 0 442 488 A2, published Aug. 21, 1991 (“Groechel”).
`7 Donnelly et al., Anisotropic Etching of SiO2 in Low-Frequency CF4/O2 and
`NF3/Ar Plasmas, 55 J. Appl. Phys. 242 (Jan. 1984) (“Donnelly”).
`8 Dunfield et al., US 4,793,897, issued Dec. 27, 1988 (“Dunfield”).
`9 Hong, US 5,525,535, issued June 11, 1996 (“Hong”).
`10 Rhoades et al., US 5,269,879, issued Dec. 14, 1993 (“Rhoades”).
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`that Hashimoto teaches or suggests that the first, second, and third etches are
`anisotropic, as recited in claims 3 and 11.
`Petitioner’s contention is supported by Hashimoto, which discloses
`that the first, second, and third etches are carried out using dry etching,
`which the ’188 patent discloses may be used to produce an anisotropic etch.
`Ex. 1005, claim 3, ¶¶ 8, 9; Ex. 1001, 1:64–2:2. Petitioner’s contention is
`further supported by Hashimoto Figures 4(e), 4(f), and 5(g), which show a
`contact hole having straight sidewalls with no undercutting of the etch mask.
`Ex. 1005, Figs. 4(e), 4(f), 5(g). The ’188 patent teaches that these features
`are characteristic of an anisotropic etch. Ex. 1001, 8:22–24.
`Petitioner’s contention is also supported by the Preliminary Response.
`Patent Owner argues that “[a]nisotropic etching, by definition, is
`directional . . . .” Prelim. Resp. 22. At the same time, Patent Owner
`concedes that Hashimoto’s etches are directional. Id. at 21 (arguing that, in
`Hashimoto, certain layers are “substantially thicker in the direction of the
`etch”) (emphasis added). Patent Owner’s concession supports Petitioner’s
`contention that Hashimoto teaches or suggests that the first, second, third
`etches are anisotropic.
`Patent Owner argues that Hashimoto’s first, second, and third etching
`steps are not “solely” or “necessarily” anisotropic, that anisotropic etching is
`not required for Hashimoto’s contact holes, and that the vertical geometry of
`Hashimoto’s dielectric layers would have motivated a POSA to use isotropic
`etching. Prelim. Resp. 21, 23–25, 40–47 (citing Ex. 2001 ¶¶ 57, 61, 62, 65,
`68). We are persuaded to institute review, notwithstanding Patent Owner’s
`arguments. Claims 3 and 11 do not specify a degree of anisotropy, nor
`require that the etches be “solely” anisotropic. Even if Hashimoto’s
`
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`disclosed etch conditions are not “necessarily” anisotropic, unpatentability
`may be shown, if the evidence demonstrates that it would have been obvious
`to use an anisotropic etch. See Southwire Co. v. Cerro Wire LLC, 870 F.3d
`1306, 1311–12 (Fed. Cir. 2017) (Board erred in relying on inherency
`without finding that functional claim limitation would necessarily result
`from prior art process; however, the error was harmless because the
`evidence showed that it would have been obvious to practice the prior art
`process in a manner that achieved the claimed result).
`We are persuaded that Petitioner’s argument and evidence regarding
`motivation provide a sufficient basis on which to institute review. Pet. 49–
`50, 52, 54 (citing Ex. 1003 ¶¶ 148, 155; Ex. 1010, 1). Dr. Fair testifies that a
`POSA would have been motivated to use an anisotropic etch “to produce the
`straight sidewalls of the contact hole as illustrated in Hashimoto.” Ex. 1003
`¶¶ 148, 155, 162. Dr. Bottoms, on the other hand, testifies that “the vertical
`geometry of Hashimoto’s dielectric layers would motivate the person having
`ordinary skill in the art to use isotropic etching steps.” Ex. 2001 ¶ 69. We
`do not need to resolve this disputed issue of fact for purposes of this
`Decision. Instead, by rule, we view any genuine issue of material fact
`created by testimonial evidence submitted by Patent Owner (i.e.,
`Dr. Bottoms’ testimony) in a light most favorable to Petitioner. See
`37 C.F.R. § 42.108(c).
`Patent Owner argues that Hashimoto’s etching pressures do not fall
`within the typical range understood to provide anisotropic results. Prelim.
`Resp. 21–25, 41, 44–46 (citing Ex. 2001 ¶¶ 59–60, 64, 67; Ex. 1010, 1;
`Ex. 1015, 5:8–9, 5:60–62). We are persuaded to institute review,
`notwithstanding Patent Owner’s argument. Petitioner’s evidence supports
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`that a wide range of conditions, including gas composition, pressure, and
`applied frequency, have been employed to achieve anisotropic etching.
`Ex. 1010, 1. Furthermore, as discussed above, even if Hashimoto’s
`Embodiment 1 is not necessarily anisotropic, Petitioner has articulated a
`reason or motivation for a POSA to use an anisotropic etch. Pet. 49–50, 52,
`54.
`
`Patent Owner argues that Hashimoto Figure 4(e) shows an isotropic
`etch of silicon nitride film 48. Prelim. Resp. 22–23, 42 (citing Ex. 2001
`¶ 61). We are persuaded to institute review, notwithstanding Patent Owner’s
`argument. Hashimoto Figure 4(e) shows the result of etching BPSG layer
`49. Ex. 1005 ¶ 8. Whereas layer 49 is 400 nm thick, the silicon nitride film
`is only 100 nm thick. Id. Even if the entire silicon nitride film were etched
`in the horizontal direction, it would still be etched to a lesser extent (100 nm)
`than the BPSG layer is etched in the vertical direction (400 nm). For this
`reason and for purposes of this Decision, we are not persuaded that
`Hashimoto Figure 4(e) shows an isotropic etch.
`Patent Owner argues that the absence of undercutting in Hashimoto
`Figures 4(e), 4(f), and 5(g) is due to an inaccuracy in the drawings. Prelim.
`Resp. 23, 42, 45, 47 (citing Ex. 2001 ¶ 61). We are persuaded to institute
`review, notwithstanding Patent Owner’s argument. Dr. Fair testifies that
`Hashimoto Figures 4(e), 4(f), and 5(g) show straight sidewalls without
`undercutting of the etch mask. Ex. 1003 ¶¶ 145, 153, 160. Dr. Bottoms, on
`the other hand, attributes the lack of undercutting to an inaccuracy in
`Hashimoto Figure 4(e). Ex. 2001 ¶ 61. For purposes of this Decision, we
`do not need to resolve this dispute because, by rule, we view any genuine
`
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`issue of material fact created by Dr. Bottoms’ testimony in a light most
`favorable to Petitioner. 37 C.F.R. § 42.108(c).
`Patent Owner additionally argues that it would have been difficult for
`Hashimoto to achieve both selectivity and anisotropy. Prelim. Resp. 44, 47–
`48 (c
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