(19)
`
`(12)
`
`Europäisches Patentamt
`
`European Patent Office
`
`Office européen des brevets
`
`*EP001069448B1*
`
`(11)
`
`EP 1 069 448 B1
`
`EUROPEAN PATENT SPECIFICATION
`
`(45) Date of publication and mention
`of the grant of the patent:
`19.03.2003 Bulletin 2003/12
`
`(21) Application number: 00305938.3
`
`(22) Date of filing: 13.07.2000
`
`(51) Int Cl.7: G02B 17/08, G03F 7/20
`
`(54) Catadioptric optical system and projection exposure apparatus equipped with the same
`
`Katadioptrisches optisches System und Projektionsbelichtungsvorrichtung mit einem solchen System
`
`Système optique catadioptrique et dispositif d’exposition par projection muni d’un tel système
`
`(84) Designated Contracting States:
`DE NL
`
`(30) Priority: 13.07.1999 JP 19946799
`
`(43) Date of publication of application:
`17.01.2001 Bulletin 2001/03
`
`(60) Divisional application:
`03000101.0
`
`(73) Proprietor: NIKON CORPORATION
`Tokyo (JP)
`
`(72) Inventors:
`• Suenaga, Yutaka, Nikon Corp.
`Tokyo (JP)
`• Miyashita, Tomohiro, Nikon Corp.
`Tokyo (JP)
`• Yamaguchi, Kotaro, Nikon Corp.
`Tokyo (JP)
`
`(74) Representative: Burke, Steven David et al
`R.G.C. Jenkins & Co.
`26 Caxton Street
`London SW1H 0RJ (GB)
`
`(56) References cited:
`EP-A- 0 779 528
`US-A- 4 293 186
`US-A- 4 812 028
`US-A- 5 734 496
`
`WO-A-95/32446
`US-A- 4 685 777
`US-A- 5 717 518
`US-A- 5 737 137
`
`• OWEN G ET AL: "A CATADIOPTRIC REDUCTION
`CAMERA FOR DEEP UV MICROLITHOGRAPHY"
`MICROELECTRONIC
`ENGINEERING,NL,ELSEVIER PUBLISHERS BV.,
`AMSTERDAM, vol. 11, no. 1 / 04, 1 April 1990
`(1990-04-01), pages 219-222, XP000134590 ISSN:
`0167-9317
`• HAGA T ET AL: "Large-field ( ? 20 ? 25 mm)
`replication by EUV lithography"
`MICROELECTRONIC
`ENGINEERING,NL,ELSEVIER PUBLISHERS BV.,
`AMSTERDAM, vol. 30, no. 1, 1996, pages
`179-182, XP004003058 ISSN: 0167-9317
`
`Note: Within nine months from the publication of the mention of the grant of the European patent, any person may give
`notice to the European Patent Office of opposition to the European patent granted. Notice of opposition shall be filed in
`a written reasoned statement. It shall not be deemed to have been filed until the opposition fee has been paid. (Art.
`99(1) European Patent Convention).
`
`Printed by Jouve, 75001 PARIS (FR)
`
`EP1 069 448B1
`
`1
`
`ZEISS 1027
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`EP 1 069 448 B1
`
`Description
`
`BACKGROUND OF THE INVENTION
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`[0001] The present invention relates to a catadioptric optical system and a projection exposure apparatus equipped
`with the catadioptric optical system suitable when manufacturing in a photolithography process, for example, a semi-
`conductor device or a liquid crystal display device. In particular, the invention relates to a catadioptric optical system
`suitable for a scanning type projection exposure apparatus.
`
`Related Background Art
`
`[0002]
`In a photolithography process for manufacturing semiconductor devices and the like, there is used a projection
`exposure apparatus by which a pattern image formed on a photomask or reticle (collectively referred to as "reticle"
`hereinafter) is projected and exposed onto a wafer, a glass plate, etc. coated with a photoresist or the like via a projection
`optical system. As the integration of the semiconductor devices and the like is improved, there has been a demand for
`a higher resolution of the projection optical system used in the projection exposure apparatus. In order to satisfy such
`a demand, there have been occurred necessities for shortening the wavelength of illumination light and increasing the
`numerical aperture (hereinafter referred to as "NA") of the projection optical system. In particular, regarding the expo-
`sure wavelength, replacing g-line (λ=436 nm), i-line (λ=356 nm) and, further, KrF excimer laser light (λ = 248 nm) are
`currently used. In the future, ArF excimer laser light (λ = 193 nm) and F2 laser light (λ=157 nm) will probably be used.
`[0003] However, as the wavelength of the illumination light becomes shorter, a fewer kinds of glass materials can
`be practically used due to light absorption. As a result, when the projection optical system is constructed by a refraction
`system alone, that is, only by optical elements not including a reflecting mirror with refractive power (a concave or
`convex mirror), chromatic aberration cannot be corrected. Additionally, because the optical performance required of
`the projection optical system is extremely high, various kinds of aberrations should preferably be corrected to a level
`of almost no aberration. Eighteen or more lens elements are required for correcting various aberrations to a desired
`optical performance by a refraction type projection optical system constituted of lens elements (see, for example,
`Japanese Unexamined Patent Publication Hei No. 5-173065), and it is difficult to suppress light absorption and avoid
`manufacturing costs' increase. Moreover, when extreme ultraviolet light with a wavelength of 200 nm or less is used,
`the optical performance may be affected by, for example, light absorption in glass material and on an anti-reflection
`film on the lens surface.
`[0004] Further, although the oscillation bandwidth of laser light sources with an oscillation wavelength of 200 nm or
`less has been considerably narrowed, the bandwidth has still a certain wavelength width. Thus, to project and expose
`a pattern maintaining good contrast, correction of chromatic aberration of the order of pm (pico meter) is required. The
`optical system disclosed in the above-mentioned Japanese Unexamined Patent Publication Hei No. 5-173065 is a
`refraction type lens system made from a single kind of glass material, and its chromatic aberration is too large to be
`used with a light source having a wavelength width.
`[0005] On the other hand, a reflection type optical system utilizing power (refractive power) of a concave mirror and
`the like does not effect chromatic aberration and, with respect to Petzval sum, creates a contribution with an opposite
`sign to a lens element. As a result, a so-called catadioptric optical system (hereinafter referred to as "catadioptric optical
`system"), which combines a catoptric optical system and a dioptric optical system together, can correct chromatic
`aberration as well as other various aberrations to a level of almost no aberration without increasing the number of
`lenses. Thus, a catadioptric optical system is an optical system having at least one lens element and at least one
`reflecting mirror with refractive power.
`[0006] However, when a concave mirror is incorporated on the optical axis of a projection optical system of a pro-
`jection exposure apparatus, light from the reticle side incident on the concave mirror is reflected toward the reticle.
`Addressing this problem, techniques to separate the optical path of light incident on a concave mirror from the optical
`path of light reflected by the concave mirror and also to direct the reflected light from the concave mirror to the wafer
`direction, i.e., various techniques to implement a projection optical system by a catadioptric optical system, have been
`extensively proposed.
`[0007] However, when using a beam splitter as is used in the optical system disclosed in Japanese Unexamined
`Patent Publication Hei No. 5-281469, it is difficult to secure large-sized glass material for manufacturing the optical
`system. In addition, in the case of the optical system disclosed in Japanese Unexamined Patent Application Hei No.
`5-51718, an optical path folding mirror (folding mirror) or a beam splitter is required, a plurality of lens barrels are
`required for manufacturing the optical system, resulting in such problems as difficulties in manufacture or in adjusting
`optical elements. A light beam impinges obliquely onto a plane reflecting mirror (folding mirror) for changing the optical
`
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`EP 1 069 448 B1
`
`path direction incorporated in a catadioptric optical system as necessary. Accordingly, extremely high surface accuracy
`of the mirror is required, resulting thus in the difficulty of the manufacture of the mirror. Further, the mirror is easily
`affected by vibration.
`[0008] Meanwhile, when an optical path separating method disclosed in U.S. Patent No. 5,717,518 is used, optical
`elements constituting a optical system can all be disposed along a single optical axis. As a result, the optical system
`can be manufactured with high accuracy following an optical element adjustment method conventionally used in the
`projection optical system manufacture. However, the system requires a central light-shielding portion to shield light
`beam propagating along the optical axis, resulting in the contrast deterioration of a pattern of a certain frequency.
`[0009] Additionally, because it is difficult to provide an anti-reflection film with sufficient optical performance in the
`extreme ultraviolet wavelength region, it is also required that the number of optical elements constituting an optical
`system be reduced as much as possible.
`[0010] As can be seen from the above, it is preferable that, to expose a pattern having a linewidth of 0.18 µm or less,
`an optical system in which a good chromatic aberration correction capability is realized even when using a light source
`with a wavelength of 200 nm or less such as ArF or F2 laser, no central light-shielding is used, a high numerical aperture
`of NA 0.6 or more can be secured, and the number of refractive and reflecting components is reduced as much as
`possible be provided.
`[0011] EP 0 779 528A relates to an optical projection reduction system comprising a first mirror pair, a field mirror
`pair receiving light from the first mirror pair, and a third mirror pair receiving light from the field mirror pair, whereby an
`intermediate image is re-imaged to a final image at an image plane.
`
`SUMMARY OF THE INVENTION
`
`[0012] The present invention has been made in view of the above problems, and the object of the invention is to
`provide a catadioptric optical system in which chromatic aberration is well corrected in the extreme ultraviolet wave-
`length region, in particular, even in the wavelength region of 200 nm or less, and a NA (0.6 or more) necessary for
`high resolution is secured, and the number of refractive and reflecting components is reduced as much as possible; a
`projection exposure apparatus equipped with the optical system.
`[0013] The present invention provides a catadioptric optical system as set out in claim 1.
`[0014] The invention also provides a projection exposure apparatus as set out in claim 9.
`[0015] Preferred features are set out in the dependent claims.
`
`BRIEF DESCRIPTION OF THE DRAWINGS
`
`[0016] FIG. 1 is a view schematically illustrating the configuration of a projection exposure apparatus equipped with
`a catadioptric projection optical system to which. the present Invention is applied.
`[0017] FIG. 2 is a view illustrating a lens configuration of a catadioptric optical system in accordance with a first
`embodiment of the present invention.
`[0018] FIG. 3 is a view showing transverse aberrations of the catadioptric optical system in accordance with the first
`embodiment,
`[0019] FIG. 4 is a view illustrating a lens configuration of a catadioptric optical system in accordance with a second
`embodiment of the present invention.
`[0020] FIG. 5 is a view showing transverse aberrations of the oatadioptric optical system in accordance with the
`second embodiment.
`[0021] FIG. 6 is a view illustrating a lens configuration of a catadioptric optical system in accordance with a third
`embodiment of the present invention.
`[0022] FIG. 7 is a view showing transverse aberrations of the catadioptric optical system in accordance with the third
`embodiment.
`
`DESCRIPTION OF THE PREFERRED EMBODIMENTS
`
`[0023]
`In the following, the catadioptric optical system in accordance with an embodiment of the present invention
`will be described with reference to the accompanying drawings. The system is a catadioptric optical system provided
`with a first catadioptric type imaging optical system G1 for forming an intermediate image I1 of a first surface 3 and
`with a second refraction type imaging optical system G2 for telecentrically forming the final image of the first surface
`3 onto a second surface 9 (wafer surface, i.e., the final image plane) based on light from the intermediate image. The
`first optical system G1 has a lens group including at least one positive lens element, a first reflecting surface M1 which
`reflects light passed through the lens group and is substantially collimated, and a second reflecting surface M2 for
`directing light reflected by the first reflecting surface M1 to the second imaging optical system G2; and at least one of
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`EP 1 069 448 B1
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`the first and second reflecting surfaces is a concave reflecting surface. Further, the second imaging optical system G2
`has aperture diaphragm AS, all of the optical elements of the catadioptric optical system are disposed on a single linear
`optical axis AX, the first surface 3 and the second surface 9 are plane surfaces which are substantially mutually parallel;
`and an exit pupil of the catadioptric optical system is substantially circular.
`[0024] A structurally reasonable catadioptric optical system is achieved by making the effective projected area an
`annular shape and by preventing mutual interference of optical elements through appropriately positioning the first and
`second reflecting surfaces M1 and M2.
`[0025] Further, in the present invention, the following condition is preferably satisfied:
`
`(1)
`
`0.04<|fM1|/L<0.4
`
`wherein fM1 is a focal length of the concave reflecting surface of the first or second reflecting surface, and L is a
`distance along the optical axis AX from the first surface 3 to the second surface 9. The condition (1) defines an appro-
`priate power range of the concave reflecting surface.
`[0026] Positive Petzval sum created by refractive lenses is corrected by negative Petzval sum created by the concave
`mirror. When the power is over the upper limit value of the condition (1), the positive Petzval sum created by refractive
`lenses cannot be sufficiently corrected, and the flatness of the image deteriorates. In contrast, when the power is below
`the lower limit value of the condition (1), the Petzval sum is overcorrected, and the flatness of the image deteriorates
`similarly
`[0027] Further, in the present invention, the following condition is preferably satisfied:
`
`(2)
`
`0.6<|βM1|<20
`
`wherein βM1 represents a magnification of the concave reflecting surface of the first or second reflecting surface. The
`condition (2) defines an appropriate magnification range of the concave reflecting mirror. When the magnification is
`over the upper limit value of the condition (2) or is below the lower limit value of the condition (2), symmetricity of the
`first imaging system G1 is seriously affected, large coma aberration being produced, and causes the image deteriora-
`tion.
`[0028] Further, in the present invention, the following condition is preferably satisfied:
`
`(3)
`
`0.3<|β1|<1.8
`
`wherein β1 is a magnification of the first imaging optical system G1. The condition (3) defines an appropriate magni-
`fication range of the first imaging optical system G1. When the magnification is over the upper limit value of the condition
`(3) or is below the lower limit value of the condition (3), power balance collapses, causing distortion aberration (distor-
`tion) and coma aberration. and the imaging performance deteriorates.
`[0029] Further, in the present invention, it is preferable that, the first imaging optical system G1 has a light beam
`which intersects at least three times a plane P1 perpendicular to the optical axis AX. Light from the first surface 3, after
`being refracted by the lens group L1, passes through the plane P1 (the first time) to the reflecting surface M1, and,
`after being reflected by the surface, passes through again the plane P1 (the second time) to the reflecting surface M2.
`Further, the light, after being reflected by the reflecting surface M2, passes through again the plane P1 (the third time)
`and forms the intermediate image I1. In addition, by having made the effective projected area an annular shape, the
`light and the optical elements such as the reflecting surfaces M1 and M2 can be positioned so as not to physically
`interfere with each other.
`[0030] Further, as mentioned above, the catadioptric optical system is telecentric on the second surface 9 side (wafer
`surface side), but it is preferable that the optical system be additionally telecentric on the first surface 3 side (reticle
`surface side).
`[0031]
`In the following, embodiments of the present invention will be described with reference to the attached draw-
`ings. FIG. 1 is a drawing schematically illustrating the overall configuration of a projection exposure apparatus equipped
`with a projection optical system in accordance with any embodiment of the present invention optical systems. Note
`that, in FIG. 1, a Z-axis is set parallel to the optical axis AX of the projection optical system 8 constituting the projection
`exposure optical system, an X-axis is set parallel to the plane of the drawing of FIG.1. and a Y-axis is set perpendicular
`to the plane of the drawing, both of X- and Y- axes being in a plane perpendicular to the optical axis AX. Further, a
`reticle 3, as a projection original plate, on which a predetermined circuit pattern is formed is disposed on the object
`plane of the projection optical system 8, and a wafer 9, as a substrate, coated with a photoresist is disposed on the
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`EP 1 069 448 B1
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`image plane of the projection optical system 8.
`[0032]
`Light emitted from light source 1, via the illumination optical system 2, uniformly illuminates the reticle on
`which the predetermined pattern is formed. One or more folding mirrors for changing the optical path direction are
`disposed, as required, on the optical path from the light source 1 to the illumination optical system 2.
`[0033] Note further that the illumination optical system 2 comprises optical systems such as an optical integrator
`constituted of, for example, a flyeye lens or an internal reflection type integrator for forming a plane light source having
`a predetermined size and shape; a variable field stop (reticle blind) for defining the size and shape of an illumination
`area on the reticle 3; and a field stop imaging optical system for projecting the image of this field stop on the reticle.
`Also note that. as an optical system from the light source 1 to the field stop, the illumination optical system disclosed
`in U.S. Patent No. 5,345,292 may be applied.
`[0034] The reticle 3 is, via reticle holder 4, held on reticle stage 5 parallel to the XY plane. On the reticle 3 is formed
`a pattern to be transferred, and the overall pattern area is illuminated with light from the illumination optical system 2.
`The reticle stage 5 is so configured that the stage is two-dimensionally movable along a reticle plane (i.e., the XY
`plane) by the effect of a drive system, not shown, and that the coordinate position of the stage is measured by inter-
`ferometer 7 using reticle moving mirror 6 and is position-controlled.
`[0035]
`Light from the pattern formed on the reticle 3 forms, via the projection optical system 8, a mask pattern image
`onto the wafer which is a photosensitive substrate. The projection optical system 8 has a variable aperture diaphragm
`AS (see FIG. 2) near its pupil and is substantially telecentric on both of the reticle 3 and wafer 9 sides.
`[0036] The wafer 9 is, via a wafer holder 10, held on a wafer stage 11 parallel to the XY plane. Onto a substantially
`similar exposure area to the illuminated area on the reticle 3 is thus formed the pattern image.
`[0037] The wafer stage 11 is so configured that the stage is two-dimensionally movable along a wafer plane (i.e.,
`the XY plane) by the effect of a drive system, not shown, and that the coordinate position of the stage is measured by
`interferometer 13 using wafer moving mirror 12 and thus the wafer stage is position-controlled.
`[0038] As described above. the field view area on the mask 3 (illumination area) and the projection area (exposure
`area) on the wafer 9 both defined by the projection optical system 8 are rectangle-shaped areas having a short-side
`along the X-axis. Aligning the mask 3 and the wafer 9 is thus performed by using the drive systems and the interfer-
`ometers (7, 13), and the wafer 9 is positioned onto the image plane of the projection optical system by the use of an
`autofocus/autoleveling system, not shown. Further, by synchronously moving (scanning) the mask stage 5 and the
`wafer stage 11, and accordingly, the mask 3 and the wafer 9, along the short-side direction of the rectangle-shaped
`exposure and illumination areas, i.e., along the X-direction. the mask pattern is scanningly exposed onto an area on
`the wafer 9 of which width is equal to the long-side length of the exposure area and of which length is equal to the
`scanning (moving) length of the wafer 9.
`[0039] Note that over the overall optical path between the light source 1 and the wafer 9 is formed an inert gas
`atmosphere such as nitrogen or helium gas into which the exposure light is little absorbed.
`
`(First Embodiment)
`
`[0040] FIG. 2 is a drawing illustrating a lens configuration of a catadioptric optical system in accordance with a first
`embodiment of the present invention. The system is a catadioptric optical system comprising a first catadioptric type
`imaging optical system G1 for forming an intermediate image Il of a reticle (first surface) 3 and a second refraction
`type imaging optical system G2 for telecentrically forming the final image of the reticle surface 3 onto a wafer (second
`surface) 9 based on light from the intermediate image I1.
`[0041] The first imaging optical system G1 has a lens group L1 including at least one positive lens element, a first
`reflecting surface M1 which reflects light passed through the lens group L1, and a second reflecting surface M2 for
`directing light reflected by the first reflecting surface M1 to the second imaging optical system G2, at least one of the
`first and second reflecting surfaces being a concave reflecting surface, and the second imaging optical system G2
`having an aperture diaphragm AS. Further, all of the optical elements of the catadioptric optical system are disposed
`on a single linear optical axis AX, the reticle surface 3 and the wafer surface 9 are plane surfaces which are substantially
`mutually parallel; and an exit pupil of the catadioptric optical system is substantially circular.
`[0042]
`In Table 1 are listed values of items of the projection optical system in accordance with the first embodiment.
`In Table 1, numerals in the leftmost column represent the order of lens surfaces from the reticle 3 (first object plane)
`side, r is the radius of curvature of the lens surface, d is the lens surface interval from the lens surface to the next lens
`surface, β is the overall magnification of the catadioptric optical system, NA is the numerical aperture on the wafer side
`(the second surface side), and λ is the standard wavelength. Note that the refractive indexes of the glass used in the
`first embodiment equal to those in the second embodiment.
`[0043] Further, ASP in the lens data represents an aspherical surface. In each embodiment, an aspherical surface
`can be expressed by the following mathematical formula:
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`2
`
`Z=(y
`
`/r) /[1+ {1- (1+κ)·y
`
`2
`
`2
`
`}
`
`/r
`
`1/2
`
`]+A · y
`
`4
`
`6
`
`+B · y
`
`+C · y
`
`8
`
`+D · y
`
`10
`
`+E · y
`
`12
`
`+F · y
`
`14
`
`wherein y is the height in the direction normal to the optical axis, Z is a displacement amount (sag amount) from the
`tangential plane at the apex of the aspherical surface to a position of the aspherical surface at the height y measured
`along the direction of the optical axis, r is the radius of curvature at the apex, κ is a conical coefficient, and A⬃F are
`aspherical coefficients of the n-th order.
`[0044] Note that, in all of the values of items of the following embodiments, similar reference codes to those of this
`embodiment are used. Here, as an example of the unit for the radius of curvature r and the lens surface interval d in
`the values of items of all embodiments, mm may be used.
`
`| β |=1/4
`NA=0. 7 5
`λ=193. 3 nm
`
`No.
`
`r
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`8
`
`9
`
`-211.97583
`
`-354.80161
`
`-8888.21083
`
`-227.79960
`
`303.84978
`
`ASP:
`κ=0.000000
`A=+0.743561⫻10-8
`C=-0.115168⫻10-17
`237634.15996
`∞ (Plane)
`-348.87932
`
`4267.07121
`
`10
`
`-362.24910
`
`11
`
`12
`
`13
`
`14
`
`15
`
`16
`
`ASP:
`κ=3.260270
`A=+0.859110⫻10-8
`C=-0.100064⫻10-15
`E=-0.489883⫻10-23
`4267.07087
`
`-348.87932
`
`642.80918
`
`ASP:
`κ=1.840470
`A=0.198825⫻10-8
`C=0.597091⫻10-18
`E=-0.103460⫻10-26
`208.71115
`
`-2529.72930
`
`-1810.41832
`
`ASP:
`κ =0.000000
`A=-0.885983⫻10-7
`C=-0.570861⫻10-16
`E=-0.493085⫻10-25
`
`[Table 1]
`
`d
`
`30.000000
`
`35.347349
`
`38.000000
`
`0.944905
`
`27.415767
`
`B=-0.230589⫻10-12
`D=-0.753145⫻10-22
`30.000000
`
`214.776416
`
`12.000000
`
`5.579827
`
`-5.579827
`
`B=+0.351935⫻10-12
`D=+0.318170⫻10-19
`
`Glass Material
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`(Reflecting surface)
`
`-12.000000
`
`-214.776416
`
`246.776416
`
`SiO2
`
`(Reflecting surface)
`
`B=0.556479⫻10-13
`D=0.492729⫻10-22
`
`33.000000
`
`257.546203
`
`14.500000
`
`SiO2
`
`SiO2
`
`B=-0.200044⫻10-11
`D=+0.456578⫻10-22
`
`6
`
`

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`[Table 1]
`
`(continued)
`
`d
`
`220.408225
`
`30.000000
`
`0.200000
`
`36.013163
`
`No.
`
`r
`
`17
`
`18
`
`19
`
`20
`
`851.98207
`
`15200.59096
`
`-268.76515
`
`434.96005
`
`ASP:
`κ=0.000000
`A=-0.161380⫻10-7
`C=+0.108604⫻10-17
`E=-0.101080⫻10-25
`-345.83883
`
`-215.91874
`
`-619.95152
`
`415.08345
`
`-1275.90912
`
`324.91386
`
`-740.00769
`
`ASP:
`κ=0.000000 κ=0.000000
`A=+0.138330⫻10-7
`C=-0.258860⫻10-18
`E=+0.363539⫻10-26
`140.91060
`
`1406.88948
`
`355.40083
`
`98.27403
`
`105.27944
`
`1597.37798
`
`21
`
`22
`
`23
`
`24
`
`25
`
`26
`
`27
`
`28
`
`29
`
`30
`
`31
`
`32
`
`33
`
`B=+0.153066⫻10-12
`D=+0.319975⫻10-21
`
`10.489902
`
`20.000000
`
`0.200000
`
`40.000000
`
`26.288090
`
`35.000000
`
`5.214992
`
`B=+0.194125⫻10-12
`D=-0.196062⫻10-22
`
`34.000000
`
`0.500000
`
`17.506069
`
`1.561573
`
`75.940555
`
`12.920542
`
`Glass Material
`
`SiO2
`
`CaF2
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`(Refractive index of glass material)
`
`λ=193.3nm+0.48pm λ=193.3nm λ=193.3nm-0.48pm
`
`SiO2
`
`CaF2
`
`1.56032536
`
`1.50145434
`
`1.5603261
`
`1.5014548
`
`1.56032685
`
`1.50145526
`
`(Condition correspondence value)
`
`[0045]
`
`(1)
`
`| f M 1 | = 181.1246/1350=0.13417
`
`(2)
`
`| β M 1 | =|-1.21007|=1.21007
`
`(3)
`
`| β 1 | =|-1.1454|=1.1454
`
`[0046] FIG. 3 shows transverse aberrations (coma aberrations) of the catadioptric optical system in accordance with
`the embodiment in the meridional (tangential) and sagittal directions. In each diagram, Y indicates the image height,
`continuous line indicates the standard wavelength (λ=193.3nm), dotted line indicates λ=193.3nm+0.48pm, and alter-
`nate long and short line indicates λ=193.3nm-0.48pm (the same is applied in the second embodiment). Note that, in
`
`7
`
`

`

`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`EP 1 069 448 B1
`
`all of the various aberration diagrams of the following embodiments, similar reference codes to those of this embodiment
`are used. As can be clearly seen from the aberration diagrams, aberrations are well-balancedly corrected in the overall
`exposure area in the catadioptric optical system of this embodiment in spite of the both-sides telecentricity along with
`the imaging performance deterioration due to the light absorption by the applied glass materials being prevented.
`
`(Second Embodiment)
`
`[0047] FIG. 4 is a drawing illustrating a lens configuration of a catadioptric optical system in accordance with a second
`embodiment. The system is a catadioptric optical system comprising a first catadioptric type imaging optical system
`G1 for forming an intermediate image I1 of a reticle (first surface) 3 and a second refraction type imaging optical system
`G2 for telecentrically forming the final image of the reticle surface 3 onto a wafer (second surface) 9 based on light
`from the intermediate image I1.
`[0048] The first imaging optical system G1 has a lens group L1 including at least one positive lens element, a first
`reflecting surface M1 which reflects light passed through the lens group L1, and a second reflecting surface M2 for
`directing light reflected by the first reflecting surface M1 to the second imaging optical system G2; at least one of the
`first and second reflecting surfaces is a concave reflecting surface; and the second imaging optical system G2 has an
`aperture diaphragm AS. Further, all of the optical elements of the catadioptric optical system are disposed on a single
`linear optical axis AX, the reticle surface 3 and the wafer surface 9 are plane surfaces which are substantially mutually
`parallel; and an exit pupil of the catadioptric optical system is substantially circular.
`[0049]
`In Table 2 are listed values of items of the projection optical system in accordance with the second embodi-
`ment. Note that reference codes in Table 2 are similarly defined as those in FIG. 1, aspherical surface ASP can be
`expressed by the above-described mathematical formula.
`
`| β |=1/6
`NA=0. 7 5
`λ=1 9 3. 3 nm
`
`No.
`
`r
`
`1
`
`2
`
`3
`
`4
`
`5
`
`6
`
`7
`
`8
`
`9
`
`521.54601
`
`-191794.5079
`
`194.28987
`
`ASP:
`κ=0.000000
`A=-0.155326⫻10-8
`C=+0.176234⫻10-17
`452.66236
`
`-589.38426
`
`1106.79674
`
`-482.64964
`
`ASP:
`κ = 7.430564
`A=+0.199000 ⫻ 10-8
`C=-0.122172 ⫻ 10-15
`E=-0.126279 ⫻ 10-22
`1106.79671
`
`-589.38426
`
`10
`
`455.39924
`
`[Table 2]
`
`d
`
`23.000000
`
`0.944905
`
`30.000000
`
`B=-0.140791⫻10-12
`D=-0.155625⫻10-21
`300.000000
`
`12.000000
`
`5.000000
`
`-5.000000
`
`B=-0.957889 ⫻ 10-12
`D=+0.305937 ⫻ 10-19
`
`Glass Material
`
`SiO2
`
`SiO2
`
`SiO2
`
`(Reflecting surface)
`
`-12.000000
`
`-273.707398
`
`477.535323
`
`SiO2
`
`(Reflecting surface)
`
`ASP:
`κ=0.000000
`A=+0.434199⫻10-9
`C=+0.360429⫻10-19
`300.69546
`
`B=+0.327908⫻10-14
`D=-0.622589⫻10-24
`29.000000
`
`-3836.44237
`
`-4996.75666
`
`191.527911
`
`15.000000
`
`> 11
`
`12
`
`13
`
`SiO2
`
`SiO2
`
`8
`
`

`

`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`EP 1 069 448 B1
`
`[Table 2]
`
`(continued)
`
`No.
`
`r
`
`d
`
`Glass Material
`
`ASP:
`κ=0.000000
`A=-0.601871E-07
`C=-0.177478⫻10-16
`E=-0.236872⫻10-23
`1631.22452
`
`761.43970
`
`-416.24467
`
`385.90210
`
`ASP:
`κ=0.000000
`A=-0.127289⫻10-7
`C=-0.237720⫻10-18
`E=-0.177785⫻10-25
`-325.55463
`
`-220.30976
`
`-755.61144
`
`359.10784
`
`-1575.91947
`
`235.63612
`
`-2200.62013
`
`ASP:
`κ=0.000000
`A=+0.198616⫻10-7
`C=0.106669⫻10-16
`E=+0.853932⫻10-28
`159.89570
`
`2158.79385
`
`406.09986
`
`68.76384
`
`70.58705
`
`2340.17874
`
`14
`
`15
`
`16
`
`17
`
`18
`
`19
`
`20
`
`21
`
`22
`
`23
`
`24
`
`25
`
`26
`
`27
`
`28
`
`29
`
`30
`
`B=-0.111865⫻10-11
`D=+0.104425⫻10-23
`
`164.229823
`
`32.000000
`
`7.787594
`
`43.198650
`
`B=+0.112712⫻10-12
`D=+0.283035⫻10-21
`
`16.575364
`
`20.000000
`
`9.063759
`
`37.871908
`
`1.464560
`
`32.000000
`
`1.000000
`
`B=-0.109623⫻10-12
`D=-0.466071⫻10-21
`
`33.600000
`
`0.000000
`
`9.500000
`
`4.196119
`
`75.473363
`
`9.379567
`
`SiO2
`
`CaF2
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`SiO2
`
`(Condition correspondence value)
`
`[0050]
`
`(1)
`
`| f M 1 | =241.3248/1339.26=0.18019
`
`(2)
`
`| βM1 | =|-12.51|=12.51
`
`(3)
`
`| β 1 | =|-0.6135|=0.6135
`
`[0051] FIG. 5 shows transverse aberration diagrams of the catadioptric optical system in accordance with the second
`embodiment. As can be clearly seen also from the aberration diagrams, aberrations are well-balancedly corrected in
`the overall exposure area.
`
`9
`
`

`

`5
`
`10
`
`15
`
`20
`
`25
`
`30
`
`35
`
`40
`
`45
`
`50
`
`55
`
`(Third Embodiment)
`
`EP 1 069 448 B1
`
`[0052] FIG. 6 is a drawing illustrating a lens configuration of a catadioptric optical system in accordance with a third
`embodiment. The system is a catadloptric optical system comprising a first catadioptric type imaging optical system
`G1 for forming an intermediate image I1 of a reticle (first surface) 3 and a second refraction type imaging optical system
`G2 for telecentrically forming the final image of the reticle surface 3 onto a wafer (second surface) 9 based on light
`from the intermediate image I1.
`[0053] The first imaging optical system G1 has a lens group L1 including at least one positive lens element, a first
`reflecting surface M1 which reflects light passed through the lens group L1, and a second reflecting surface M2 for
`directing light reflected by the first reflecting surface M1 to the second imaging optical system G2; at least one of the
`first and second reflecting surfaces is a concave reflecting surface; and the second imaging optical system G2 has an
`aperture diaphragm AS. Further, all of the optical elements of the catadioptric optical system are disposed on a single
`linear optical axis AX, the reticle surface 3 and the wafer surface 9 are plane surfaces which are substantially mutually
`parallel: and an exit pupil of the catadioptric optical system is substantially circular.
`[0054]
`In Table 3 are listed values of items of the projection optical system in acco