United States Patent [19]
`Takahashi
`
`US005691802A
`[11] Patent Number:
`[45] Date of Patent:
`
`5,691,802
`Nov. 25, 1997
`
`[54] CATADIOPTRIC OPTICAL SYSTEM AND
`EXPOSURE APPARATUS HAVING THE
`SAME
`
`4/1994 Ieong a a1. ............................ .. 355/53
`5,303,001
`3/1995 Markle et a1.
`355/53
`5,402,205
`5,467,166 11/1995 Shiraishi ................................. .. 355/71
`
`[75] Inventor: Tomowaki Takahashi, Yokohama,
`Japan
`
`[73] Assignee: Nikon Corporation, Japan
`
`[21] Appl. No.: 552,453
`[22] Filed:
`Nov. 3, 1995
`[30]
`Foreign Application Priority Data
`
`Japan ..
`[JP]
`Nov. 7, 1994
`"
`Japan --
`[JP]
`Mm’- 7’ 1995
`Japan .................................. .. 7-177858
`[JP]
`1111.14, 1995
`[51] Int. (:1.6 ................................................... .. G03B 27/42 .
`[52] us. (:1. ............................... .. 355/53; 355/77; 355/60;
`355/43; 359/727; 359/730; 359/366
`[58] Field Of Search ................................ .. 355/53. 71, 43,
`355/77, 57, 60; 359/366, 727, 730, 731
`Refemnces Cited
`
`[56]
`
`U.S. PATENT DOCUMENTS
`3,917,399 11/1975 Buzawa et a1. ......................... .. 355/43
`4,669,866
`6/1987 Phillips ____ __
`355/53 X
`4,704,027 11/1987 Phillips ..
`355/53 X
`4,742,376
`5/1988 Phillips ..
`..... .. 355/77
`4,779,966 10/1983 Friedman
`. 350/442
`5,052,763 10/1991 Singh et a1.
`359/355
`5,274,420 12/1993. Chastang ............................. .. 355/53 X
`
`Primary Examiner-R. L. Moses
`Attorney, Agent, or Firm-Pennie & Edmonds LLP
`
`[57]
`
`ABSTRACT
`
`It is an object of the invention to provide a catadioplric
`optical system with an arrangement for realizing a large
`numerical aperture and reducing the diameter of a concave
`mirror while ensuring a suf?cient working distance on the
`image side, and also an exposure apparatus using this
`catadioptric optical system.
`
`A catadioptn'c optical system according to the invention
`includes a ?rst imaging optical System for forming an
`immediate image of a pattern on a ?rst plane, a second
`imaging Optical System for fonning a reduccd im?gc of the
`intermediate image on a second plane, and an optical path
`de?ecting membct f°r guiding a light beam fwm the ?rst
`imaging optical system to the second imaging optical sys
`tem. The ?rst imaging optical system has at least a ?rst
`optical element group having a positive refracting power,
`and a second optical element group having a concave mirror
`and a meniscus lens component with a concave surface
`faclflg the ?rst ‘magmg °P'§‘ca1 systef‘?‘ lnpamcf?ari the ?r,“
`optlcal element group having a posltlve refractlng power 1s
`arranged to guiltc a light beam from the ?rst plane to ttw
`second optical element group.
`
`35 Claims, 20 Drawing Sheets
`
`ILLUMINATION
`OPTICAL SYSTEM
`
`"\l
`
`ALIGNMENT
`OPTICAL SYSTEM
`
`>4 .4 lo
`
`R SCANNING
`
`SCANNING
`DIRECTION
`
`DIRECTION
`OF GRAVITY
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 1
`
`

`

`U.S. Patent
`
`Nov. 25, 1997
`
`Sheet 1 of 20
`
`5,691,802
`
`F lg. /
`
`[I
`
`ILLUMINATION
`OPTICAL SYSTEM
`
`/ I IO
`
`IOO
`/
`
`‘
`ALIGNMENT
`LIGHT SOURCE ‘21> OPTICAL SYSTEM
`
`/
`
`200
`f
`RETICLE
`EXCHANGE
`SYSTEM
`
`—
`
`R
`
`r300
`
`STAGE
`CONTROL
`SYSTEM
`
`MAIN
`
`CONTROL
`SECTION
`
`/ 40o
`
`_
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 2
`
`

`

`US. Patent
`
`Nov. 25, 1997
`Sheet 2 0f 20
`Fig. 2
`
`5,691,802
`
`ILLUMINATION
`OPTICAL SYSTEM
`
`I00
`/
`
`LIGHT
`SOURCE
`
`CONTROL
`SYSTEM
`
`400
`MAIN
`O
`CONTROL
`SECTION
`
`WAFER
`STAGE
`CONTROL
`SYSTEM
`
`300
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 3
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`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 3 of 20
`
`5,691,802
`
`F 19 . 3
`
`A
`
`r
`
`‘
`
`w‘
`
`FIRST IMAGING
`OPTICAL SYSTEM 6|
`G|2
`:----*----~
`:
`MI I
`i
`I
`'
`I
`
`(RETICLE R) Pl
`
`SCANNING
`DIRECTION
`
`SECOND IMAGING
`OPTICAL SYSTEM (32
`
`613
`‘
`‘
`GII
`GlgF 912ml ,
`r‘? :'"':
`'
`
`
`I " ' .
`:
`:5
`5
`|
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`e-2,-E
`
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`
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`
`
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`.
`l
`|
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`:
`l
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`
`I
`
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`r
`22~.j
`
`L-~--- #
`
`"c
`
`-
`
`6
`
`P2(WAFER w)
`_H
`’ SCANNING
`Axz
`DIRECTION
`
`Fig.4
`
`ILLUMINATION AREA
`
`SCANNING
`DIRECTION
`
`3
`
`=1
`
`R
`
`Fig.5
`
`EXPOSURE AREA Wf
`
`W
`
`SCANNING
`DIRECTION
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 4
`
`

`

`US. Patent
`Nov. 25, 1997
`Fig.6
`
`Sheet 4 of 20
`
`5,691,802
`
`(RETICLE R)
`I
`l
`613""
`
`Mo
`
`I
`SCANNING
`DIRECTIONP-H-J-HU
`
`.11 ..|| I ||||| rl/f.
`
`WA A
`
`SECOND IMAGING
`OPTICAL SYSTEM G2
`
`Fig.7
`
`Axg/?, (WAFER w)
`SCANNING DIRECTION
`
`SCANNING
`DIRECTION
`
`Fig.8
`
`Wf
`
`SCANNING
`DIRECTION
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 5
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 5 of 20
`
`5,691,802
`
`Fig .
`
`FIRST IMAGING OPTICAL SYSTEM G|
`'
`v
`M,
`j
`
`r
`
`(RETICLE R) Pl
`
`SCANNING
`DIRECTION
`
`' ,Axl
`
`________ __ AXZb
`Z
`
`“"3
`
`I
`
`APERTURE STOP
`
`‘a
`
`G22
`
`222
`I25 zm
`‘m
`will
`UH
`P2
`(WAFER w)
`
`l
`SECOND IMAGING OPTICAL SYSTEM 62
`
`Fig. /0
`
`Rf
`
`SCANNING
`DIRECTION :
`
`‘N
`
`F lg. I l
`
`W
`
`Wf
`
`SCANNING
`DIRECTION
`
`I
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 6
`
`

`

`U.S. Patent
`
`Nov. 25, 1997
`
`Sheet 6 0f 20
`
`5,691,802
`
`no.0
`
`S .8...‘
`
`1E" _ ______
`
`, E0
`
`0:
`E
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 7
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 7 0f 20
`
`5,691,802
`
`FIG. 14A
`
`FIG . 145
`
`FIG . 14C
`
`=-o.
`6
`NA
`L
`
`13 r
`
`Y= 26.00
`L
`K
`
`T
`
`' Y=26.00
`
`‘I
`
`I
`l
`I
`I
`I
`
`0. 010
`SPHERICAL
`ABERRA'I'ION
`
`0.0I0
`ASTIGMATISM
`
`0.0|O
`DI STORTI ON
`
`FIG . 15
`
`,L
`
`-
`
`-
`
`CHROMATIC ABERRATI ON OF
`MAGNIFI CATI ON
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 8
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 8 of 20
`
`5,691,802
`KJ
`L
`
`|04.o0
`
`.
`
`FIG.16A THANSVEHSE
`
`ABERHAT ION
`
`H0165
`THANSVERSE
`ABERRAT ION
`
`FIG . 16C
`TRANSVERSE
`ABERHAT I DN
`
`.
`
`7 92% L
`:
`
`JKL
`
`RAND
`
`F IG . 1 6D
`TRANSVERSE
`ABERRAT ION
`
`l==§;=~{——6=w?
`0.001
`
`ALL COMA
`
`F IG . 16E
`
`'L
`I
`THANSVERSE f/l
`
`ABEHHATIGN
`
`m}:- 0.6
`|
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 9
`
`

`

`U.S. Patent
`
`Nov. 25, 1997
`
`Sheet 9 0f 20
`
`5,691,802
`
`NNN J
`NNJ m
`
`NNO
`
`N0
`
`23 :3 E3
`
`E 5E
`
`m: st
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 10
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 10 0f 20
`
`5,691,802
`
`FIG.19A
`
`H0198
`
`FIG.19C
`
`Y=l9.00
`
`Y=l9.00
`
`0.0IO
`SPHERICAL
`ABERRATION
`
`_o.oro
`ASTIGMATISM
`
`0.0lO°/o
`DISTORTION
`
`F1620
`
`}
`
`—0.00I
`
`V KL
`
`CHROMATIC ABERRATION OF
`MAGNIFICATION
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 11
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 11 of 20
`
`5,691,802
`
`Ti?svéi?
`F
`.
`ABEHFIATION
`
`/ ‘
`
`76.00
`
`T
`
`1
`
`-
`-
`i-m
`
`GOTOO
`FIG .2
`TRANSVERg-EB r J.
`ABEFIHATIUN
`
`1K
`‘P’ L
`
`FIG . 21c
`TRANSVEHSE
`ABERRATIUN
`
`40.0
`
`rr=~
`
`I am
`
`'
`
`FIG . 210
`TRANSVERSE
`ABERRATIUN
`
`RAND
`w I
`Q00,
`
`.13“
`
`ALL COMA
`
`FIG 21E P T THANSi/EHSE l
`
`ABERRAT ION
`
`
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 12
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 12 of 20
`
`5,691,802
`
`Fig.23
`
`CARL ZEISS V. NIKON
`|PR2013-00362
`
`EX. 2011, p. 13
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`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 13
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`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 13 of 20
`
`5,691,802
`
`FIG 24A‘
`
`P162413
`
`FIG.24C
`
`Y=l8.00
`
`0.010
`SPHERICAL
`ABERRATION
`
`0.010
`ASTIGMATISM
`
`0.0IO
`DISTORTION
`
`F1625
`
`KL
`
`-0.00I
`
`CHROMATIC ABERRATION OF‘
`MAGNIFICATION
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 14
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 14 of 20
`
`5,691,802
`
`F IG . 26A
`TRANSVERSE
`ABERHATION
`
`72.00
`
`F 1*“
`
`F IG . 26B
`THANSVERSE
`ABERHATION
`
`F IG . 26C
`THANSVERSE
`ABERHATION
`
`FIG . 26D
`THANSVERSE
`ABEHHATION
`
`F IG . 26E
`THANSVEHSE
`ABERRATIDN
`
`ABE
`
`I
`
`‘PM.
`
`F=~
`
`Y
`
`RAND
`
`T
`
`-l-0.00I
`
`I
`
`<44“
`
`ALL COMA
`'l'
`
`NA:-O.6
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 15
`
`

`

`‘ U.S. Patent
`
`Nov. 25, 1997
`
`Sheet 15 0f 20
`
`5,691,802
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 16
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`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 16 0f 20
`
`5,691,802
`
`FIGEQA
`
`FIGBQB
`
`FIGEQC
`
`SPHERICAL
`ABERRATION
`
`0.500
`AS'I'IGMATISM
`
`[0 .000
`DIS'I'ORTION
`
`FIG .30
`
`KL
`
`—0.00I
`
`CHROMATI C ABERRAT I ON 0F
`MAGN IFI CATION
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 17
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 17 of 20
`
`5,691,802
`
`72.00
`
`é7——+—‘==?? -
`
`KL
`
`48.00
`
`i-p'—}———??
`
`25.0
`
`K
`
`
`
`Ag» 1% >
`
`RAND
`
`o.oo|
`
`K
`
`%
`
`ALLCOMA
`I
`l
`
`NA=-O.6
`?gi‘
`
`FIG.31A
`THANSVERSE
`ABERHATIDN
`
`H6818
`
`TRANSVEHSE
`ABERRATION
`
`FIG.31C THANSVEHSE
`
`ABERHATION
`
`FIG.31D THANSVERSE
`
`ABEHHATION
`
`FIG.31E
`TRANSVEHSE
`ABERHATIUN
`
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`

`

`US. Patent
`Nov. 25, 1997
`Fig. 32
`
`Sheet 18 of 20
`
`5,691,802
`
`FA
`
`(F5
`
`Fig. 33
`
`Fig.34
`
`FB
`
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`IPR2013-00362
`Ex. 2011, p. 19
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`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 19 of 20
`
`5,691,802
`
`Fig.35
`
`M2
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 20
`
`

`

`US. Patent
`
`Nov. 25, 1997
`
`Sheet 20 of 20
`
`5,691,802
`
`Fig . 36
`
`ILLUMINATION
`OPTICAL SYSTEM
`
`OPTICAL SYSTEM
`
`ALIGNMENT
`
`R SCANNING
`DIRECTION
`
`
`
`
`
`I
`'
`,4
`633*?” L _______ ..I
`F——_— IIIW
`
`’
`
`
`
`
`
`SCANNING
`
`DIRECTION
`
`DIRECTION
`OF GRAVITY
`
`
`CARL ZEISS V. NIKON
`|PR2013-00362
`
`EX. 2011, p. 21
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`CARL ZEISS V. NIKON
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`

`

`, 5,691,802
`
`1
`CATADIOPTRIC OPTICAL SYSTEM AND
`EXPOSURE APPARATUS HAVING THE
`SAME
`
`BACKGROUND OF THE INVENTION
`
`1. Field of the Invention
`
`invention relates to a projection optical
`The present
`system in a projection exposure apparatus such as a stepper
`used to manufacture semiconductor elements or liquid crys—
`tal display elements by photolithography and, more
`particularly, to a catadioptric projection optical system using
`a reflection system as an element of an optical system.
`2. Related Background Art
`In photolithography for manufacturing semiconductor
`elements, liquid crystal display elements, or the like, a
`projection exposure apparatus which reduces the pattern
`image of a reticle (or a photomask) to about 1/: to 1/5 through
`a projection optical system and exposures the pattern image
`onto a wafer or a glass plate (to be referred to as a
`photosensitive substrate hereinafter) coated with a photore-
`sist or the like is used As a projection exposure apparatus,
`a one—shot exposure apparatus such as a stepper is conven—
`tionally used.
`Recently, as the degree of integration of a semiconductor
`element or the like is improved, a resolving power required
`for a projection optical system used in a projection exposure
`apparatus is also increasing. To cope with this requirement,
`the wavelength of illumination light for exposure (exposure
`wavelength) must be shortened, or the numerical aperture
`NA of the projection optical system must be increased.
`However, when the exposure wavelength is shortened, only
`limited types of optical glass materials can be practically
`used because of the absorption of illumination light. For this
`reason, it is difiicult to form a projection optical system
`using only a refraction system
`On the other hand, a projection optical system constituted
`by only a reflection system has also been examined. In this
`case, however, the projection optical system becomes bulky.
`Additionally, the reflecting surface must be made aspherical,
`though it is very diflicult
`to precisely manufacture an
`aspherical surface in a large size.
`Therefore, various techniques of forming a reduction
`projection optical system by a so-called catadioptric optical
`system consisting of a reflection system and a refraction
`system formed of an optical glass material having a resis-
`tance against the to-be-used exposure wavelength are pro-
`posed. For example, a catadioptric optical system for pro-
`jecting an image of a reticle at a predetermined reduction
`magnification by combining an optical system including a
`concave mirror and a refraction optical system is disclosed
`in, e.g., U.S. Pat. No. 4,779,966, and Japanese Patent
`Laid—Open No. 4—234722.
`A catadioptric optical system disclosed in U.S. Pat. No.
`4,779,966 comprises, in the following order from the object
`side, a refraction optical system, and a catadioptric optical
`system for refocusing an intermediate image formed by this
`refraction optical system.
`An optical system disclosed in Japanese Patent Laid—Open
`No. 4—234722 comprises, in the following order from the
`object side, a perfectly symmetrical type catadioptric optical
`system, and a refraction optical system for refocusing an
`intermediate image formed by this catadioptric optical sys—
`tem at a reduction magnification.
`The catadioptric optical system disclosed in U.S. Pat. No.
`4,779,966 or Japanese Patent Laid—Open No. 4-234722 uses
`
`2
`
`only a lens component having a negative power as a refrac-
`tion optical member in the catadioptric optical system
`including a concave mirror. Therefore, the diameter of a
`light beam from an object (intermediate image) to the
`concave mirror only increases, so the diameter of the con-
`cave mirror itself cannot be reduced.
`
`Additionally, in the catadioptric optical system disclosed
`in U.S. Pat. No. 4,779,966, when the numerical aperture on
`the image side (substrate side) is to be increased,
`the
`numerical aperture of an optical system close to the image
`side must be increased. At this time, the diameter of a light
`beam incident on the concave mirror in the catadioptric
`optical system arranged on the image side must be increased
`As a result, the diameter of the concave mirror increases.
`Furthermore, since the catadioptric optical system disclosed
`in U.S. Pat No. 4,779,966 is an optical system having a
`reduction magnification, the optical path from the concave
`reflecting Inirror to the image plane on a photosensitive
`substrate cannot be made long. The number of refraction
`lenses arranged in this optical path cannot be increased, so
`suflicient
`imaging performance is hardly obtained.
`Furthermore, the distance between the end face of an optical
`element closest to the substrate side and the substrate surface
`(image plane), i.e., a sufficient working distance on the
`substrate side cannot be ensured.
`
`SUMMARY OF THE INVENTION
`
`is an object of the present invention to obtain a
`It
`catadioptric optical system with an arrangement for realizing
`a large numerical aperture and reducing the diameter of a
`concave mirror while ensuring a sufficient working distance
`on the image side, and also an exposure apparatus using this
`catadioptric optical system. The catadioptric optical system
`according to the present invention can be applied to both a
`one—shot exposure apparatus and a scanning exposure appa-
`ratus.
`
`In order to achieve the above object, according to the
`present invention, there is provided a reflection exposure
`apparatus comprising at least a first stage 3 (wafer stage)
`capable of holding a photosensitive substrate W on a major
`surface thereof, a second stage 2 (reticle stage) for holding
`a mask (reticle R) having a predetermined pattern, an
`illumination optical system 1 for emitting an exposure light
`beam having a predetermined wavelength to the mask and
`transferring an image of the predetermined pattern on the
`mask onto the substrate, and a catadioptric optical system
`according to the present
`invention, which is arranged
`between the first stage 3 and the second stage 2 to project the
`pattern formed on a first plane P1 (object plane) on the mask
`onto a second plane P2 (image plane) on the substrate, as
`shown in FIGS. 1 and 2. Note that the photosensitive
`substrate W consists of an exposure target 8 such as a glass
`plate, sflicon wafer, or the like, and a photosensitive material
`'7 such as aphotoresist coated on the surface of the exposure
`target 8.
`The catadioptric optical system comprises a first imaging
`optical system G1 for forming an intermediate image
`(primary image) of the pattern on the mask, a second
`imaging optical system G2 having a reduction magnification
`and adapted to form a reduced image (secondary image) of
`the intermediate image formed by the first imaging optical
`system G1 on the substrate (the composite magnification of
`the second imaging optical system G2 and the first imaging
`optical system G1 is a reduction magnification), and a first
`optical path deflecting member M2 arranged in the optical
`path from the first imaging optical system G1 to the second
`
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`CARL ZEISS V. NIKON
`|PR2013-00362
`
`EX. 2011, p. 22
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 22
`
`

`

`5,691,802
`
`3
`imaging optical system G2 to guide a light beam from the
`first imaging optical system G1 to the second imaging
`optical system G2, as shown in FIG. 3.
`The first imaging optical system G1 comprises a first
`optical element group G11 having a positive refracting
`power, and a second optical element group G12 consisting of
`a negative lens component and a concave mirror M1 and
`having a positive refracting power. Each element constitut-
`ing the first imaging optical system G1 is arranged such that
`a fight beam from the mask passes through the first optical
`element group G11 and reaches the concave mirror M1 in the
`second optical element group G12, and the light beam
`reflected by the concave mirror M1 passes through the first
`optical element group G11 again and reaches the first optical
`path deflecting member M2. The second imaging optical
`system G2 comprises a front optical element group G21
`having a positive refracting power, and a rear optical ele-
`ment group G22 having a positive refracting power. In
`particular, a light beam from the first imaging optical system
`G1 sequentially passes through the front optical element
`group G21 and the rear optical element group G22 and
`reaches the second plane P2 (image plane) on the substrate.
`The first imaging optical system G1 in the catadioptric
`optical system may further comprise a third optical element
`group G13 arranged in the optical path between the first
`plane P1 and the first optical element group G11. In this case,
`the third optical element group G13 comprises a forward lens
`group G131; having a positive refracting power and a rear
`lens group G13R having a negative refracting power, in this
`order from the first plane P1 to the first optical element
`sump G11-
`To minimize the number of optical elements susceptible
`to asymmetric deformation due to gravity, the catadiopnic
`optical system is preferably arranged in the exposure appa-
`ratus such that at least the propagation direction of an
`exposure light beam irradiated from the illumination optical
`system 1 and passing through the mask and the propagation
`direction of an exposure light beam emerging from the
`second imaging optical system toward the substrate W
`coincides with the direction of gravity while arranging the
`first plane P1 (object plane) on the mask and the second
`plane (image plane) on the substrate in parallel to each other.
`As an aspect for obtaining this arrangement, a second optical
`path deflecting member M0 for changing the propagation
`direction of a light beam from the first plane P1 (object
`plane) can be arranged between the first plane P1 and the
`first optical path deflecting member M2, thereby arranging
`the first plane P1 and the second plane P2 (image plane) in
`parallel to each other, as shown in FIG. 6. As shown in FIG.
`9, even when a third optical path deflecting member M3 for
`changing the propagation direction of a light beam from the
`front optical element group G21 in the second imaging
`optical system G2 is arranged between the front optical
`element group G21 and the rear optical element group G22,
`the first plane P1 and the second plane P2 become to be
`arranged in parallel to each other. In FIG. 6, the lower side
`of the drawing corresponds to the lower side of the exposure
`apparatus, and the upper side of the drawing corresponds to
`the upper side of the exposure apparatus.
`According to the present
`invention with the above
`arrangement, a light beam from the first plane P1 reaches the
`second optical element group G12 including the concave
`mirror M1 via the first optical element group G11 having a
`positive refracting power in the first imaging optical system
`G1. For this reason, the diameter of the light beam reaching
`the second optical element group G12 can be reduced by the
`first optical element group G“. Therefore, the diameter of
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`
`the concave mirror M1 in the second optical element group
`G12 can be reduced. Reduction of the diameter of the
`concave mirror M1 facilitates to precisely manufacture the
`concave mirror M1 and also reduces the manufacturing cost.
`In addition, according to the present invention, an inter—
`mediate image (primary image) is forrned, and the first
`imaging optical system G1 has the concave mirror M1 and
`the negative lens component. With this arrangement, chro-
`matic aberration can be minimized. Particularly, when the
`present invention is applied using a krypton fluoride (KrF)
`excimer laser or an argon fluoride (ArF) excimer laser with
`a large oscillation wavelength width as a light source,
`chromatic aberration can be advantageously minimized.
`Furthermore according to the present invention, in the
`optical path from the first imaging optical system G1 to the
`second imaging optical system G2, the diameter of the light
`beam is reduced by the first imaging optical system G1. For
`this reason, size reduction of the first optical path deflecting
`member M2 itself arranged in this optical path can be
`achieved.
`
`Furthermore, according to the present invention, the first
`optical path deflecting member M2 is preferably constituted
`by a member having only a function of deflecting the optical
`path. Such a member need not have a function of splitting a
`light beam, unlike a beam splitter. Therefore, the loss in light
`amount can be suppressed to almost 0%, and flare light can
`also be advantageously minimized. In the present invention,
`an aberration caused by nonuniformity in characteristics of
`the beam Split surface in a beam splitter or variations in
`characteristics of the beam split surface due to heat absorp—
`tion does not occur.
`
`The first optical path deflecting member M2 is more
`preferably arranged near the intermediate image formed by
`the first imaging optical system G1. With this arrangement,
`an influence of a decentering error caused upon deflecting
`the optical path can be minimized. For example, if an
`angular error is generated in the optical path deflecting
`member M2,
`the second imaging optical system G2 is
`decentered with respect to the first imaging optical system
`G1. As a result, an image formed on the second plane P2 is
`only shifted with respect to the first plane P1, so the imaging
`performance is hardly influenced.
`In the present invention, a field stop is preferably arranged
`in the optical path from the first imaging optical system G1
`to the second imaging optical system G2. At this time, the
`field stop is preferably integrally formed with the above
`optical path deflecting member.
`In the present invention,
`the second imaging optical
`system 62 does not
`include the concave mirror M1.
`However, even with a large numerical aperture, a sufficient
`working distance on the image side can be ensured.
`In the present invention,
`the second imaging optical
`system G2 preferably has the front optical element group
`G21 having a positive retracting power and the rear optical
`element group G22 having a positive retracting power. In the
`present invention, an aperture stop can be arranged in the
`optical path between the front optical element group G21 and
`the rear optical element group G22. Therefore, when the
`aperture stop is constituted by a variable aperture stop, the
`coherence factor (0 value) can be adjusted.
`To increase the depth of focus, a special filter can be
`inserted in the Fourier transform plane in the second imag-
`ing optical system G2.
`As a method of increasing the depth of focus to increase
`the resolving power, a phase shift method is proposed in
`Japanese Patent Laid-Open No. 62—508 11 in which the phase
`
`CARL ZEISS V. NIKON
`|PR2013-00362
`
`EX. 2011, p. 23
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 23
`
`

`

`5,691,802
`
`5
`
`of a predetermined portion in the pattern of the reticle R is
`shifted from the remaining portion. In the present invention,
`since the coherence factor (0' value) can be adjusted, the
`elfect of the phase shift method can be further increased.
`In the present invention, the first imaging optical system
`G1 preferably has the third optical element group G13
`arranged in the optical path between the first plane P1 and
`the first optical element group G11. The third optical element
`group G13 has a function of magnifying the first imaging
`optical system G1. The third optical element group G13 is
`located near the first plane P1 and also has a function of
`satisfactorily correcting asymmetrical aberrations, and
`particularly, distortion and chromatic aberration of
`magnification, which cannot be completely corrected by the
`first optical element group G11, the second optical element
`group G12, and the second imaging optical system G2. The
`third optical element group G13 preferably has the forward
`lens group G13F having a positive refracting power and the
`rear lens group G13R having a negative refracting power, in
`this order from the first plane P1 to the first optical element
`group G11. With this arrangement, satisfactory telecentricity
`can be maintained while achieving diameter reduction in the
`overall third optical element group G13.
`In the present invention, the first and second imaging
`optical systems G1 and G2 preferably satisfy the following
`conditions:
`
`o.4<|a,|<1.2
`
`0.2<IB2|<0.7
`
`1/10<lB1.B2|<V2
`
`(l)
`
`(2)
`
`(3)
`
`Where [31 is the imaging magnification of the first imaging
`optical system, and [52 is the imaging magnification of the
`second imaging optical system.
`The above inequalities (1) to (3) define the appropriate
`magnification ranges of the imaging optical systems G1 and
`G2 in the present invention to obtain satisfactory imaging
`performance.
`When the imaging magnification of the first imaging
`optical system G1 is below the lower limit of inequality (1),
`an intermediate image of a pattern having a predetermined
`object height on the first plane (object plane) is formed near
`the optical axis of the first imaging optical system G1. This
`matter undesirably limits the arrangement of the first optical
`path deflecting member M2. In addition, a light beam from
`the first plane P1 to the first imaging optical system G1 may
`undesirably interfere with the first optical path deflecting
`member M2.
`When the imaging magnification of the first imaging
`optical system G1 exceeds the upper limit of inequality (1),
`the diameter of the first imaging optical system GI, and
`particularly, the lens diameter of the first optical element
`group G11 is undesirably increased to impose a heavy load
`on the aberration correction by the second imaging optical
`system G2. Note that the upper limit of inequality (1) is more
`preferably 1.0.
`When the imaging magnification of the second imaging
`optical system G2 is below the lower limit of inequality (2),
`aberrations occurring in the second imaging optical system
`G2 itself undesirably increase. In addition, the diameter of a
`lens present near a position where an intermediate image is
`formed is undesirably increased.
`When the imaging magnification of the second imaging
`optical system G2 exceeds the upper limit of inequality (2),
`the first imaging optical system G1 must have a very large
`reduction magnification to obtain a desired reduction mag—
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`nification. At this time, aberrations originating from the first
`imaging optical system G1 undesirably increase, and the
`arrangement of the first optical path deflecting member M2
`is undesirably limited. Note that the upper limit of inequality
`(2) is more preferably 0.5.
`When the imaging magnification product of the first and
`second imaging optical systems G1 and G2 is below the
`lower limit of inequality (3), exposure in a wide range
`cannot undesirably be achieved with satisfactory optical
`performance. When the product exceeds the upper limit of
`inequality (3), it undesirably becomes difficult to increase
`the numerical aperture on the image side (substrate side).
`In the present invention, to further improve the optical
`performance,
`the Petzval sum of the overall system is
`preferably close to zero. From this viewpoint, the catadiop—
`tric optical system according to the present invention is
`preferably arranged to satisfy the following conditions:
`
`1P61+Pml<o1
`
`PGll+PGZI+P022>O
`
`P612<0
`
`where
`
`(4)
`
`(5)
`
`(6)
`
`Pm: Petzval value of the first imaging optical system G1,
`PG21 Petzval value of the second imaging optical system
`G2,
`P611: Petzval value of the first optical element group G11,
`PG”: Petzval value of the second optical element group
`G123
`P021: Petzval value of the front optical element group G21
`in the second imaging optical system G2,
`P022: Petzval value of the rear optical element group G22
`in the second imaging—optical system G2.
`Similarly, when the third optical element group G13 is
`arranged in the optical path between the first plane P1 and
`the first optical element group G11, the catadioptric optical
`system according to the present invention is preferably
`arranged to satisfy inequality (7) in place of inequality (5):
`
`P611+P621+P622+P613>0
`
`(7)
`
`where
`
`45
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`P011: Petzval value of the first optical element group G11,
`P012: Petzval value of the second optical element group
`G12,
`P621: Petzval value of the front optical element group G21
`in the second imaging optical system G2,
`P622: Petzval value of the rear optical element group G22
`in the second imaging optical system G2,
`PG13: Petzval value of the third optical element group G13
`in the first imaging optical system G1.
`In this case, the Petzval value of the first imaging optical
`system G1 includes the sum of the Petzval values of the first
`optical element group G11, the second optical element group
`G”, and the third optical element group G13.
`.
`The above conditions mean that an increase in Petzval
`sum, which is caused by a group of elements each having a
`positive refracting power, is decreased by the second optical
`element group Gl2 including the concave mirror M1, and
`correction of Petzval sum is performed by both the first
`imaging optical system G1 and the second imaging optical
`system G2. When the above conditions are not satisfied,
`flatness of the image plane on the second plane P2 is
`undesirably degraded.
`However, when a zone using a portion near a predeter-
`mined image height as an exposure area is used, the flatness
`
`CARL ZEISS V. NIKON
`|PR2013-00362
`
`EX. 2011, p. 24
`
`CARL ZEISS V. NIKON
`IPR2013-00362
`Ex. 2011, p. 24
`
`

`

`7
`
`8
`
`5,691,802
`
`of the image plane near the predetermined image height
`need only be considered, so the above conditions need not
`always be satisfied.
`the second imaging optical
`In the present invention,
`system G2 preferably consists of at least two optical mate-
`rials having diiferent dispersion values. With this
`arrangement, the effect of chromatic aberration correction
`can be increased.
`
`In the present invention, the front optical element group
`G21 in the second imaging optical system G2 preferably
`includes a negative lens component consisting of high-
`dispersion glass, and a positive lens component consisting of
`low-dispersion glass. The rear optical element group G22 in
`the second imaging optical element system G2 preferably
`includes a positive lens component consisting of low—
`dispersion glass.
`With this arrangement, the effect of chromatic aberration
`correction can be further increased.
`
`In the first imaging optical system G1 of the catadioptric
`optical system according to the present invention, the menis-
`cus lens component in the second optical element group G12
`preferably has a shape in which the lens surface on the first
`optical element group G11 side is a concave surface facing
`the first optical element group G11, and the lens surface on
`the concave mirror M1 side is a concave surface facing the
`first optical element group G11. The concave surface (first
`concave surface) of the meniscus lens component on the first
`optical element group G11 side and the concave surface
`(second surface) thereof on the concave mirror M1 side are
`preferably arranged to satisfy inequality (8):
`
`10
`
`15
`
`20
`
`25
`
`O.5<trAl/r,d
`
`where
`
`30
`
`(8)
`
`IA: radius of curvature of the concave surface of the
`meniscus lens component, on the first optical element
`group G11 side, in the second optical element group
`G12,
`r3: radius of curvature of the concave surface of the
`meniscus lens component, on the concave mirror M1
`side, in the second optical element group G12.
`Condition (8) is a condition for obtaining good symmetry
`of coma. When erler of the first imaging optical system G1
`exceeds the upper limit of condition (8), the upper coma
`undesirably increases. When erl/rB of the