Trials@uspto.gov
`571-272-7822
`
`
`
`
`
`Paper 41
`Entered: November 4, 2014
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`CARL ZEISS SMT GMBH,
`Petitioner,
`
`v.
`
`NIKON CORPORATION,
`Patent Owner.
`
`
`Case IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`Before HOWARD B. BLANKENSHIP, SALLY C. MEDLEY, and
`MATTHEW R. CLEMENTS, Administrative Patent Judges.
`
`
`CLEMENTS, Administrative Patent Judge.
`
`
`
`
`
`FINAL WRITTEN DECISION
`35 U.S.C. § 318(a) and 37 C.F.R. § 42.73
`
`
`
`571-272-7822
`
`
`
`
`
`Paper 41
`Entered: November 4, 2014
`
`
`
`UNITED STATES PATENT AND TRADEMARK OFFICE
`____________
`
`BEFORE THE PATENT TRIAL AND APPEAL BOARD
`____________
`
`CARL ZEISS SMT GMBH,
`Petitioner,
`
`v.
`
`NIKON CORPORATION,
`Patent Owner.
`
`
`Case IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`Before HOWARD B. BLANKENSHIP, SALLY C. MEDLEY, and
`MATTHEW R. CLEMENTS, Administrative Patent Judges.
`
`
`CLEMENTS, Administrative Patent Judge.
`
`
`
`
`
`FINAL WRITTEN DECISION
`35 U.S.C. § 318(a) and 37 C.F.R. § 42.73
`
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`I.
`
`INTRODUCTION
`
`Carl Zeiss SMT GmbH (“Carl Zeiss”) filed a Petition requesting inter
`
`partes review of claims 1–3, 8–12, 16–20, 23–26, and 29–33 of U.S. Patent
`
`No. 7,348,575 B2 (Ex. 1001, “the ’575 patent”). Paper 3 (“Pet.”). The
`
`Patent Owner, Nikon Corporation (“Nikon”), did not file a Preliminary
`
`Response. On December 16, 2013, we granted an inter partes review for all
`
`challenged claims on certain grounds of unpatentability. Paper 10 (“Dec. to
`
`Inst.”).
`
`After institution of trial, Nikon filed a Patent Owner Response (Paper
`
`19, “PO Resp.”) to which Carl Zeiss filed a Reply (Paper 22, “Reply”).
`
`Additionally, Nikon filed a Motion to Exclude Evidence (Paper 32), to
`
`which Carl Zeiss responded (Paper 36). Nikon then filed a Reply in Support
`
`of its Motion to Exclude. Paper 39.
`
`Carl Zeiss also filed a Motion to Exclude Evidence (Paper 33), to
`
`which Nikon responded (Paper 37). Carl Zeiss then filed a Reply in Support
`
`of its Motion to Exclude. Paper 38.
`
`Oral hearing was held on July 17, 2014.1
`
`The Board has jurisdiction under 35 U.S.C. § 6(c). This Final Written
`
`Decision is issued pursuant to 35 U.S.C. § 318(a) and 37 C.F.R. § 42.73.
`
`Carl Zeiss has shown by a preponderance of the evidence that claims
`
`1–3, 8–12, 16–20, 23–26, and 29–33 of the ’575 patent are unpatentable.
`
`
`
`1 A transcript of the oral hearing is included in the record as Paper 40
`(“Tr.”).
`
`2
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`A. The ’575 Patent
`
`The subject matter of the ’575 patent relates to a catadioptric
`
`projection optical system, exposure apparatus, and exposure method and,
`
`more particularly, to a high-resolution catadioptric projection optical system
`
`suitable for use in production of semiconductor devices and liquid-crystal
`
`display devices by photolithography. Ex. 1001, 1:18–23. In the production
`
`of semiconductor devices, photolithography uses a projection exposure
`
`apparatus to project an “image of a mask (or a reticle) through a projection
`
`optical system onto a wafer (or a glass plate or the like) coated with a
`
`photoresist or the like.” Id. at 1:27–32. As the dimensions of semiconductor
`
`devices shrink, the projection optical system of the projection exposure
`
`apparatus requires greater resolving power (resolution). Id. at 1:32–36. In
`
`order to satisfy the requirements for the resolving power of the projection
`
`optical system, it is necessary to shorten the wavelength of illumination light
`
`(exposure light) and to increase the image-side numerical aperture of the
`
`projection optical system. Id. at 1:37–41. It was known to increase the
`
`numerical aperture by putting a medium with a high refractive index, like a
`
`liquid, in the optical path between the projection optical system and the
`
`image plane. Id. at 1:55–58. However, there were known disadvantages to
`
`this approach. Id. at 1:59–67.
`
`The ’575 patent discloses systems and methods to provide a relatively
`
`compact projection optical system that is “corrected for various aberrations,
`
`such as chromatic aberration and curvature of field, and being capable of
`
`securing a large effective image-side numerical aperture while well
`
`suppressing the reflection loss on optical surfaces.” Id. at 2:3–9. A medium
`
`3
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`having a refractive index larger than 1.1, such as deionized water, is
`
`interposed in the optical path between the boundary lens and the image
`
`plane, thereby increasing the image-side numerical aperture. Id. at 5:9–21.
`
`The projection optical system is catadioptric, comprising at least two
`
`reflecting mirrors, in which every transmitting member and every reflecting
`
`member with a refracting power are arranged along a single optical axis and
`
`in which the projection optical system has an effective imaging area that
`
`does not include the optical axis. Id. at 5:39–45. By arranging the
`
`transmitting members and the reflecting members along a single axis, the
`
`system is easier to produce than a system wherein the optical members are
`
`arranged along multiple optical axes. Id. at 5:52–59.
`
`B. Illustrative Claim
`
`Claim 1 is illustrative and is reproduced below:
`
`1. A catadiopt[ri]c projection optical system, which forms a
`reduced image of a first surface on a second surface,
`comprising:
`
`at least two reflecting mirrors; and
`
`a boundary lens whose surface on the first surface side
`has a positive refractive power,
`
`wherein where a refractive index of an atmosphere in an
`optical path of the projection optical system is 1, an optical path
`between the boundary lens and the second surface is filled with
`a medium having a refractive index la[r]ger than 1.1,
`
`wherein every transmitting member and every reflecting
`member with a refractive power constituting the projection
`optical system are arranged along a single optical axis; and
`
`the projection optical system having an effective imaging
`area of a predetermined shape not including said optical axis.
`
`4
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`C. Prior Art Supporting the Instituted Challenges
`
`Carl Zeiss relies on the following prior art references, as well as the
`
`Declaration of Richard C. Juergens (Ex. 1016):
`
`Terasawa
`
`US 2002/0024741 A1
`
`Feb. 28, 2002 Ex. 1008
`
`US 5,825,043
`
`Oct. 20, 1998 Ex. 1009
`
`Suwa
`
`Switkes
`
`Ulrich
`
`M. Switkes & M. Rothschild,
`Resolution Enhancement of
`157 nm Lithography by
`Liquid Immersion, 4691
`PROC. SPIE 459–465 (2002)
`
`Willi Ulrich et al., The
`Development of Dioptric
`Projection Lenses for DUV
`Lithography, 4832 PROC.
`SPIE 158–169 (2002)
`
`2002
`
`Ex. 1010
`
`2002
`
`Ex. 1011
`
`Sept. 30,
`1999
`
`Ex. 1012
`
`Dec. 1993
`
`Ex. 1013
`
`Fukami2
`
`WO 99/49504
`
`Asai
`
`Satoru Asai et al., Resolution
`Limit for Optical Lithography
`Using Polarized Light
`Illumination, 32 JAPAN J.
`APPL. PHYS. 5863–5866
`(1993)
`
`Carl Zeiss refers to Suwa, Switkes, Ulrich, and Fukami collectively as
`
`the “Immersion References.” Pet. 4.
`
`
`
`2 Fukami is a Japanese language document. Ex. 1012. Unless indicated
`otherwise, all subsequent references to Fukami in this decision will refer to
`its certified English language translation. Ex. 1015.
`
`5
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`D. The Instituted Challenges of Unpatentability
`
`We instituted trial based on the following grounds of unpatentability:
`
`References
`
`Basis Claim[s] challenged
`
`Terasawa and the
`Immersion References
`Terasawa, the Immersion
`References, and Asai
`
`§ 103 1–3, 8–12, 16–20, 23–26, 29, and
`31–33
`§ 103 30
`
`II. ANALYSIS
`
`A. Claim Construction
`
`In an inter partes review, claim terms in an unexpired patent are
`
`interpreted according to their broadest reasonable construction in light of the
`
`specification of the patent in which they appear. 37 C.F.R. § 42.100(b);
`
`Office Patent Trial Practice Guide, 77 Fed. Reg. 48,756, 48,766 (Aug. 14,
`
`2012). Also, claim terms are given their ordinary and customary meaning,
`
`as would be understood by one of ordinary skill in the art in the context of
`
`the entire disclosure. In re Translogic Tech., Inc., 504 F.3d 1249, 1257
`
`(Fed. Cir. 2007).
`
`Carl Zeiss contends that the words in the challenged claims generally
`
`should have their plain meaning. Pet. 13. However, Carl Zeiss provides its
`
`own interpretations of five terms—“boundary lens,” “a refractive index . . .
`
`is 1,” “effective imaging area,” “every effective imaging area,” and “the
`
`second imaging optical system.” Pet. 13–15. Nikon provides an
`
`interpretation only for “boundary lens.” PO Resp. 16–19. For this decision,
`
`we construe each of these claim terms in turn.
`
`6
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`1. “boundary lens” (claim 1)
`
`Claim 1 requires a “boundary lens.” Carl Zeiss contends that “when
`
`an immersion liquid is introduced between the last lens element of the
`
`projection optical system and the wafer (as in limitation [1d]), the last lens
`
`element becomes a ‘boundary lens.’” Pet. 14. This is consistent with the
`
`use of the term “boundary lens” in the ’575 patent. See, e.g., Ex. 1001,
`
`20:45–49 (“FIG. 3 is an illustration schematically showing a configuration
`
`between the boundary lens and the wafer in the first example of the present
`
`embodiment.”) (emphasis removed), Figs. 3, 4, 5, 7 (each depicting
`
`boundary lens Lb as the last lens element). Accordingly, in the Decision to
`
`Institute, we construed “boundary lens” as “the last lens element of the
`
`projection optical system.” Dec. to Inst. 8.
`
`Nikon contends that a “boundary lens” is not merely any lens that is
`
`placed in contact with an immersion liquid, but rather “a lens of the
`
`projection optical system that has a convex object-side surface and a flat
`
`image-side surface to increase effective NA in the presence of the immersion
`
`liquid by reducing reflection loss.” PO Resp. 16 (citing Ex. 1001, 5:22–31,
`
`Tables 1–11; Ex. 2024 ¶ 66). Nikon points to Figure 3 as depicting a
`
`boundary lens, and argues that a person of ordinary skill in the art would
`
`have understood that “a boundary lens needed to be designed to not only
`
`isolate an atmosphere of the projection optical system, but also stand a
`
`higher fluence from the light source and enable higher resolution by
`
`reducing reflection losses.” Id. at 17–18.
`
`Carl Zeiss counters that nothing in the portions of the ’575 patent
`
`cited by Nikon constitutes lexicography or disavowal of the plain and
`
`7
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`ordinary meaning of “boundary lens.” Reply 1–3. Claim 1 does not require
`
`that the image-side surface be “flat,” and the passage at column 5, lines 22 to
`
`31, merely describes what is “feasible” and “can be” secured. Id. Carl Zeiss
`
`also argues that Nikon’s proposed construction does not make technical
`
`sense because, as even Nikon’s expert conceded, it is the whole system, not
`
`just the boundary lens, that increases effective NA when an immersion
`
`liquid is used between the boundary lens and the image plane. Id.
`
`We are not persuaded that “boundary lens” should be construed to
`
`require “a convex object-side surface.” Claim 1 already requires that the
`
`“surface on the first surface side [of the boundary lens] has a positive
`
`refracting power.” To construe the term “boundary lens” to include this
`
`limitation would render this language of the claim limitation superfluous.
`
`We also are not persuaded that “boundary lens” should be construed
`
`to require “a flat image-side surface.” Although Figure 3 depicts boundary
`
`lens Lb with a flat image side, Figure 3 does not amount to a definition of
`
`“boundary lens.” With respect to Figure 3, the ’575 patent states that, “the
`
`boundary lens Lb in the first example has a convex surface kept toward the
`
`reticle (first surface). In other words, the reticle-side surface Sb of the
`
`boundary lens Lb has a positive refracting power.” Ex. 1001, 20:48–51.
`
`The description of Figure 3 is silent, however, with respect to whether the
`
`image-side surface must be flat. Id. at 20:45–54. Moreover, Nikon’s
`
`reliance on column 5, lines 22 to 31, is unavailing because it describes only
`
`a “first aspect of the embodiment.” And in describing that aspect, as in
`
`describing Figure 3, the ’575 is silent with respect to whether the image-side
`
`surface must be flat. It says only that, “the optical surface on the object side
`
`8
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`(first surface side) of the boundary lens is provided with the positive
`
`refracting power, whereby the reflection loss is reduced on this optical
`
`surface and, in turn, the large effective image-side numerical aperture can be
`
`secured.” Id. at 5:23–27. Thus, whereas Nikon’s proposed construction
`
`would require a convex object-side surface and a flat image-side surface,
`
`this passage of the ’575 patent suggests that a boundary lens needs only a
`
`positive refracting power—i.e., convex object-side surface—to reduce
`
`reflection loss and, in turn, increase effective NA in the presence of an
`
`immersion liquid.
`
`Finally we are not persuaded that “boundary lens” should be
`
`construed to include a purpose—i.e., “to increase effective NA in the
`
`presence of the immersion liquid by reducing reflection loss.” Although this
`
`purpose is referenced in column 5 of the ’575 patent, we decline to import a
`
`description of a “first aspect of the embodiment” into the construction of a
`
`claim term.
`
`Accordingly, we maintain our construction of “boundary lens” as “the
`
`last lens element of the projection optical system.”
`
`2. “a refractive index . . . is 1” (claim 1)
`
`Carl Zeiss contends that “a refractive index . . . is 1” should be
`
`interpreted as “equal to 1 to within at least the first decimal place.” Pet. 14.
`
`Carl Zeiss’s proposal is consistent with the ’575 patent’s use of the first
`
`decimal place later in claim 1 (“having a refractive index la[r]ger than 1.1”).
`
`Specifically, the use of the first decimal place—i.e., “1.1”—elsewhere in the
`
`claim implies that the recited “1” means “1.0;” otherwise the first decimal
`
`place—i.e., the first digit to the right of the decimal—would have been
`
`9
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`specified there as well. Carl Zeiss’s proposal is also consistent with the
`
`examples in the Specification of the atmosphere in the projection optical
`
`system being an inert gas, such as helium or nitrogen, which has a refractive
`
`index close to, but not exactly, equal to 1. Ex. 1001, 20:24–44; see also
`
`Ex. 1016 ¶¶ 86–92. Accordingly, we construe “a refractive index . . . is 1”
`
`as “a refractive index . . . equal to 1 within at least the first decimal place.”
`
`3. “effective imaging area” (claim 1)
`
`Carl Zeiss contends that “effective imaging area” should be
`
`interpreted to mean the same thing as “effective exposure area” and
`
`“effective exposure region ER.” Pet. 15. The ’575 patent states that “FIG. 2
`
`is an illustration showing a positional relation between the optical axis and
`
`an effective exposure area of arcuate shape,” and that “an effective exposure
`
`region (effective imaging area) ER is set in an arcuate shape.” Ex. 1001,
`
`19:65–20:9 (emphasis removed). Based on our review of the Specification,
`
`we agree that these terms are used interchangeably.
`
`4. “every effective imaging area” (claim 18)
`
`Carl Zeiss contends that “every effective imaging area” should be
`
`interpreted to mean “the effective imaging area formed on the second
`
`surface as the final image, as well as effective imaging areas corresponding
`
`to any intermediate images.” Pet. 15. The term “every effective imaging
`
`area” is not used in the ’575 patent outside of claim 18. As support for its
`
`position, Carl Zeiss cites only to the Declaration of Richard C. Juergens. Id.
`
`(citing Ex. 1016 ¶ 93). The ’575 patent describes an “effective imaging
`
`area” and describes “intermediate images,” but does not describe “effective
`
`imaging areas corresponding to any intermediate images.” Specifically, the
`
`10
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`“effective imaging area” is the arcuate shape formed on a wafer, as depicted
`
`in Figure 2, reproduced below.
`
`
`
`Ex. 1001, Fig. 2, 19:65–20:23. Figure 2 depicts the “effective imaging area”
`
`as an arcuate shape formed on a wafer. In contrast, “intermediate images”
`
`are images of the reticle formed on various components of the first imaging
`
`optical system and second imaging optical system. See, e.g., Ex. 1001,
`
`21:56–67. Because the ’575 patent refers only to an area on a wafer as the
`
`“effective imaging area,” and never once refers to an intermediate image as
`
`having a corresponding effective imaging area, Carl Zeiss has not presented
`
`sufficient and credible evidence that patentee intended “every effective
`
`imaging area” to encompass “effective imaging areas corresponding to any
`
`intermediate images.” Based on our review of the Specification, “every
`
`effective imaging area” refers to all of the effective imaging areas of the
`
`claimed projection optical system, of which there is only one: the “effective
`
`imaging area” recited in claim 1. Accordingly, we construe “every effective
`
`11
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`imaging area” as commensurate in scope with the “effective imaging area”
`
`recited in claim 1.
`
`5. “the second imaging optical system” (claim 25)
`
`Carl Zeiss contends that “the second imaging optical system” should
`
`be interpreted to mean the “second lens unit” recited in claim 10. Pet. 15–
`
`16. We disagree. Claim 25 recites “wherein the second imaging optical
`
`system is a dioptric system consisting of only a plurality of transmitting
`
`members.” Claim 25 depends from claims 1 and 10. However, neither
`
`claim 1 nor claim 10 recites a “second imaging optical system.” The
`
`Specification is ambiguous. The ’575 patent does not describe only a
`
`“second imaging optical system” or only a “second lens unit” as “consisting
`
`of only a plurality of transmitting members.” All described embodiments of
`
`the “second lens unit” described in the ’575 patent “consist[] only of a
`
`plurality of transmitting members.” Ex. 1001, Figs. 5, 7, 9, 14, 15, 16.
`
`Some, but not all, embodiments of the “second imaging optical unit” are
`
`“dioptric systems consisting of only of a plurality of transmitting members.”
`
`See, e.g., Ex. 1001, Fig. 5 (second imaging optical system G2 consisting
`
`only of lenses), Fig. 7 (second imaging optical system G2 consisting only of
`
`lenses), Fig. 14 (second imaging optical system G2 consisting only of
`
`lenses), Fig. 15 (second imaging optical system G4 consisting only of
`
`lenses), Fig. 16 (second imaging optical system G6 consisting only of
`
`lenses). At least one embodiment of the “second imaging optical system” is
`
`not. Ex. 1001, Fig. 9 (second imaging optical system G2 including two
`
`reflecting mirrors M3 and M4).
`
`12
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`Claims 20, 21, 22, 23, 24, and 26 all depend, directly or indirectly,
`
`from claim 19. Claim 19 recites a “first imaging optical system” and a
`
`“second imaging optical system.” Claim 20 depends from claim 19 and
`
`defines further limitations on the “first imaging optical system” recited in
`
`claim 19. In this context, claim 25’s recitation of “[t]he projection optical
`
`system according to claim 10” (emphasis removed) appears to be a
`
`typographical error in which “10” should be “19” or “20.” Accordingly, we
`
`construe “the second imaging optical system” to mean the “second imaging
`
`optical system” recited in claim 19.
`
`B. Whether Mr. Juergens is an Expert
`
`Nikon contends that, “[b]ecause of the highly specialized nature of
`
`projection optical systems,” the level of ordinary skill in the art would have
`
`required at least two years of experience in the lithography optics industry
`
`and experience in the specification of projection optical systems. PO Resp.
`
`15–16. Nikon further contends that Mr. Juergens is not an expert in the
`
`relevant field because he does not have the experience required to be a
`
`person of even ordinary skill in the art.3 Id. at 35–38.
`
`Carl Zeiss counters that Nikon’s expert, Dr. Jose Sasian, invites Mr.
`
`Juergens to guest lecture Dr. Sasian’s class on lens design, and that Dr.
`
`Sasian conceded that Mr. Juergens is an expert on many aspects of optical
`
`design. Reply 13, n.2.
`
`
`
`3 Nikon also asserts that exclusion of Mr. Juergens’ testimony would be
`justified. PO Resp. 38. Nikon does not, however, move to exclude either
`the Declaration of Mr. Juergens submitted with the Petition (Ex. 1016) or the
`Declaration of Mr. Juergens submitted with the Reply (Ex. 1036). Paper 32.
`
`13
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`Having considered the parties’ arguments and evidence, we are not
`
`persuaded that the level of ordinary skill in the art required at least two years
`
`of experience in the lithography optics industry and experience in the
`
`specification of projection optical systems. The claims are not limited to the
`
`field of lithography. Rather, based on the art of record, we find that the
`
`relevant field is projection optical systems. Mr. Juergens holds an M.A. in
`
`Physics and has more than 40 years of experience in the field of optical
`
`system design, including catoptric, dioptric, and catadioptric systems. Ex.
`
`1016 ¶¶ 3–9. Accordingly, we are persuaded that Mr. Juergens is a person
`
`of at least ordinary skill in the art in the art of projection optical systems.
`
`C. Claims 1–3, 8–12, 16–20, 23–26, 29, and 31–33 –
`Obvious over Terasawa and the Immersion References
`
`Carl Zeiss alleges that claims 1–3, 8–12, 16–20, 23–26, 29, and 31–33
`
`are unpatentable under 35 U.S.C. § 103(a) over Terasawa and the Immersion
`
`References. Pet. 31–50, 55–56. Carl Zeiss cites Terasawa as teaching every
`
`limitation, but acknowledges that Terasawa does not disclose expressly “an
`
`optical path between the boundary lens and the second surface is filled with
`
`a medium having a refractive index larger than 1.1,” as recited in claim 1.
`
`Id. at 34, 55. For that limitation, Carl Zeiss cites to the Immersion
`
`References (Suwa, Switkes, Ulrich, and Fukami). Id. at 36, 44–50, 55–56.
`
`Nikon counters that (1) Terasawa and the Immersion References do
`
`not teach, suggest, or otherwise render obvious a “boundary lens,” as
`
`properly construed; (2) a person of ordinary skill in the art would not have
`
`had a reasonable expectation of success in combining the references; and
`
`(3) secondary considerations demonstrate nonobviousness. PO Resp. 38–47.
`
`14
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`Upon consideration of the parties’ contentions and supporting
`
`evidence, we determine that Carl Zeiss has demonstrated by a preponderance
`
`of the evidence that claims 1–3, 8–12, 16–20, 23–26, 29, and 31–33 are
`
`unpatentable as obvious over Terasawa and the Immersion References. Pet.
`
`31–50, 55–56. In our discussion below, we address Nikon’s arguments
`
`presented in the Patent Owner Response.
`
`Terasawa (Ex. 1008)
`
`Terasawa describes a projection optical system and a projection
`
`exposure apparatus for projecting a pattern of a mask onto a substrate
`
`through the projection optical system. Ex. 1008 ¶ 1. Figure 1 of Terasawa,
`
`reproduced below, depicts a catadioptric projection optical system including
`
`a first imaging system G1 and a second imaging system G2 for projecting an
`
`image of reticle 101 illuminated with illumination system (not shown) onto
`
`wafer 102:
`
`
`
`Figure 1 of Terasawa depicts a catadioptric projection optical system. Id.
`
`¶¶ 55, 102, 103. “The first imaging optical system G1 comprises, in order
`
`from the object side, at least a first mirror M1, having a refracting element
`
`L1, [and] a second mirror M2.” Id. ¶ 103. Light from reticle 101 is imaged
`
`by first imaging optical system G1, whereby intermediate image Io is
`
`formed. Id. Intermediate image Io, as imaged by first imaging optical
`
`15
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`system G1, is then imaged on wafer 102 by second imaging optical system
`
`G2, comprising a refracting element, at a predetermined magnification. Id.
`
`In the structure described above, the optical system of the first embodiment
`
`has one optical axis 103, and produces a multiple-number imaging optical
`
`system wherein abaxial light, without light interception of a pupil, is imaged.
`
`Id. With the structure described above, light can be directed to the second
`
`imaging optical system without a void in a pupil and without bend of the
`
`optical axis. Id. ¶ 105. The region of the object plane from which the light
`
`reaches the image plane, and which is attributable to the imaging, is a semi-
`
`arcuate zone. Id. at Fig. 3, ¶ 117.
`
`Suwa (Ex. 1009)
`
`Suwa describes “a means for improving the resolution without largely
`
`increasing the numerical aperture of the projection optical system,” in which
`
`“an immersion projection method may be used in which the space between
`
`the wafer and the projection optical system is filled with a liquid.” Ex. 1009,
`
`3:18–23. Specifically:
`
`In this immersion projection method, the air space
`between the wafer and the optical element constituting the
`projection optical system on the projection end side (image
`plane side) is filled with a liquid having a refractive index close
`to the refractive index of the photoresist layer, to increase the
`effective numerical aperture of the projection optical system
`seen from the wafer side, i.e. improving the resolution. This
`immersion projection method is expected to attain good
`imaging performance by selecting the liquid used.
`
`Id. at 3:24–33. Figure 9 of Suwa is reproduced below:
`
`16
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`
`
`Figure 9 of Suwa depicts a projection optical system (PL) with an immersion
`
`fluid (LQ). Id. at 23:59-65. Suwa discloses that the last lens element, LE1,
`
`is a “positive lens element [] having a flat lower surface Pe and a convex
`
`upper surface,” and “is fixed on the end of the projection lens system PL
`
`inside the lens barrel.” Id. at 23:9–11. Suwa also discloses that the
`
`projection optical system can be catadioptric. Id. at 20:13–21. Carl Zeiss
`
`acknowledges that Suwa does not disclose expressly that the liquid has a
`
`refractive index greater than 1.1, but contends that:
`
`[A person of ordinary skill in the art] would know that “a
`refractive index close to the refractive index of the photoresist”
`would be a refractive index greater than 1.1. For example, U.S.
`Patent No. 4,346,164 (“Tabarelli”), to which the passage from
`Suwa cited above expressly refers, identifies the refractive
`index of the photoresist as 1.6, and goes on to list nine
`immersion liquids with refractive indices between 1.5 and 1.66.
`(ZEISS 1016; ¶¶ 199-201; ZEISS 1025, 3:57-60, 5:36-50.)
`
`Pet. 45. We are persuaded by Carl Zeiss’s reasoning.
`
`17
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`
`Switkes (Ex. 1010)
`
`Switkes teaches that immersion lithography can be used to enhance
`
`resolution by increasing numerical aperture and also can be used to increase
`
`depth of focus. Ex. 1010, 459 (“Immersion lithography is a technique which
`
`can enhance the resolution of projection lithography by permitting exposures
`
`with numerical aperture (NA) greater than one, the theoretical maximum for
`
`conventional ‘dry’ systems. . . . Liquid immersion also increases the wafer
`
`depth of focus, i.e. the tolerable error in the vertical position of the wafer, by
`
`the index of the immersion liquid compared to a dry system with the same
`
`numerical aperture.”) (footnotes omitted). Switkes describes several
`
`immersion liquids for use at 157 nm and 193 nm whose refractive indexes
`
`are greater than 1.2. Id. at 461. Switkes describes how immersion can be
`
`used with “much of conventional designs.” Id.
`
`Ulrich (Ex. 1011)
`
`Ulrich describes the application of immersion lithography to prior art
`
`“dry” designs to achieve increased numerical aperture. Ex. 1011, 166–167.
`
`Ulrich expressly teaches that “immersion designs can be applied to other
`
`design concepts such as catadioptric designs with similar results.” Id. at
`
`167.
`
`Fukami (Ex. 1015)
`
`Fukami describes the use of liquid immersion to improve the
`
`resolution of conventional projection exposure apparatuses. Ex. 1015, 3:13–
`
`28.4 Fukami expressly describes the applicability of immersion techniques
`
`
`
`4 Page numbers refer to the bottom number on the page.
`
`18
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`to a catadioptric optical projection system having two mirrors and a single
`
`optical axis. Id. at 21:13–16 (“Furthermore, the projection optical system
`
`PL can be a dioptric, catoptric, or catadioptric system, for example an optical
`
`system which has a plurality of dioptric elements and two catoptric elements
`
`(at least one of which is a concave mirror) disposed on an optical axis
`
`extending straight without being bent . . . .”).
`
`Boundary lens
`
`Nikon contends that Terasawa’s last lens immediately prior to wafer
`
`102 is not a “boundary lens” as construed by Nikon because it does not
`
`increase numerical aperture by reducing reflection loss. PO Resp. 38–39.
`
`We decline to adopt Nikon’s proposed construction of “boundary lens” for
`
`the reasons discussed above. Based on our construction of boundary lens,
`
`Terasawa’s last lens immediately prior to wafer 102 is a “boundary lens”
`
`because it is the last lens element of the projection optical system. Pet. 36.
`
`Reason to combine and reasonable expectation of success
`
`Carl Zeiss contends that “Ulrich demonstrates that the level of
`
`ordinary skill in this art is high and how, at the time of the alleged invention,
`
`there was not only express teaching to modify prior art ‘dry’ catadioptric
`
`projection optical system to include the immersion limitation to thereby
`
`increase NA, but also the skill necessary to do so.” Pet. 48 (citing Ex. 1016
`
`¶¶ 22–24, 77–81, 223–224).
`
`Nikon contends that a person of ordinary skill in the art would not
`
`have had a reasonable expectation of success in combining the references
`
`because introducing an immersion liquid into a dry projection optical system
`
`such as Terasawa’s would create technical problems that would render it
`
`19
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`inoperative. Id. at 39 (citing Ex. 2024 ¶¶ 119, 120). Specifically, Nikon
`
`argues that neither increasing NA nor increasing DOF would have led a
`
`person of ordinary skill in the art to combine the references because
`
`(1) adding an immersion liquid to Terasawa would cause technical problems
`
`that would have required undue experimentation and design to solve; and
`
`(2) a person of ordinary skill in the art would not have increased DOF at the
`
`expense of NA. Id. at 40–43. Carl Zeiss counters that nothing in claim 1 or
`
`the ’575 patent addresses the problems identified by Nikon, and that Nikon’s
`
`expert, Dr. Sasian, conceded that a person of ordinary skill in the art could
`
`have addressed those challenges at the time of the invention. Reply 6–7
`
`(citing Ex. 1033).
`
`Having reviewed the parties’ contentions and evidence, we are
`
`persuaded that a person of ordinary skill in the art would have had a
`
`reasonable expectation of success in combining the references. Nikon’s
`
`argument assumes that a person of ordinary skill in the art would introduce
`
`an immersion liquid into the dry projection optical system of Terasawa
`
`without any further modification. In the Petition, however, Carl Zeiss
`
`argued that “Ulrich also demonstrates that a POSITA at the time of the
`
`alleged invention would have been able to modify the systems . . . to include
`
`the immersion liquid to increase NA.” Pet. 52 (emphasis added). Ulrich
`
`teaches, for example, that “the high-NA dry projection lenses were not taken
`
`as a straight forward starting point but well-known and proven know-how of
`
`design history was fallen back on,” and that routine optimizations (“scaling
`
`of the two partial focus widths,” “splitting thick lenses,” and “adding
`
`aspheres”) can be used to achieve the level of performance desired for
`
`20
`
`
`
`IPR2013-00362
`Patent 7,348,575 B2
`
`
`projection microlithography. Ex. 1011, 166; Reply 10 (citing Ex. 1016
`
`¶¶ 220, 221). Thus, Nikon’s assumption is improper. In any event, the
`
`technical problems identified by Dr. Sasian relate to the need to characterize
`
`the optical properties of an immersion fluid, and Dr. Sasian concedes that
`
`the experiments necessary to do so were “comparable” to the techniques
`
`known and used to characterize materials such as silica glass. See, e.g.,
`
`Ex. 1033, 80:13–87:13. Accordingly, we are persuaded that a person of
`
`ordinary skill in the art at the time would have had a reasonable
Accessing this document will incur an additional charge of $.
After purchase, you can access this document again without charge.
Accept $ Charge
Still Working On It
This document is taking longer than usual to download. This can happen if we need to contact the court directly to obtain the document and their servers are running slowly.
Give it another minute or two to complete, and then try the refresh button.
A few More Minutes ... Still Working
It can take up to 5 minutes for us to download a document if the court servers are running slowly.
Thank you for your continued patience.
This document could not be displayed.
We could not find this document within its docket. Please go back to the docket page and check the link. If that does not work, go back to the docket and refresh it to pull the newest information.
Your account does not support viewing this document.
You need a Paid Account to view this document. Click here to change your account type.
Your account does not support viewing this document.
Set your membership
status to view this document.
With a Docket Alarm membership, you'll
get a whole lot more, including:
- Up-to-date information for this case.
- Email alerts whenever there is an update.
- Full text search for other cases.
- Get email alerts whenever a new case matches your search.
One Moment Please
The filing “” is large (MB) and is being downloaded.
Please refresh this page in a few minutes to see if the filing has been downloaded. The filing will also be emailed to you when the download completes.
Your document is on its way!
If you do not receive the document in five minutes, contact support at support@docketalarm.com.
Sealed Document
We are unable to display this document, it may be under a court ordered seal.
If you have proper credentials to access the file, you may proceed directly to the court's system using your government issued username and password.
Access Government Site
