‘C,
`28
`$3
`
`U.S. PTO
`1 2/37941 5
`
`02/20/2009
`
`PATENT APPLICATION
`
`IN THE UNITED STATES PATENT AND TRADEMARK OFFICE
`%
`Ellie & BERRIDGE, PLC
`Attorney Docket No.:
`125842.05
`¢Hephone: (703) 836-6400
`Facsimile: (703) 836-2787
`
`Date:
`
`February 20, 2009
`
`
`
`Customer Number: 25944
`
`Commissioner for Patents
`P.O. Box 1450
`Alexandria, VA 22313-1450
`
`Sir:
`
`CONTINUING APPLICATION TRANSMITTAL
`
`RULE 1.53(b)
`
`Transmitted herewith for filing under 37 C.F.R. §1.53(b) is a
`
`|‘_‘] Divisional
`
`application of prior pending Application No. 11/882 208 filed July 31, 2007,
`
`E Continuation
`
`El Continuation—in-Part
`
`For (Title):
`
`PROJECTION OPTICAL SYSTEM, EXPOSURE APPARATUS, AND EXPOSURE
`METHOD
`
`By (Inventors):
`
`Yasuhim OMURA
`
`1.
`
`X A Declaration of the inventor is attached. The attached Declaration is:
`
`E a. A copy of the Declaration from the parent application. (Used with the same or fewer inventors
`and (a) a copy of the prior application or (b) a revised, reformatted or edited version of the prior
`application that does not contain new matter.)
`
`E]
`
`b. A new Declaration. (Used with the same, fewer or additional inventors and (a) a copy of the
`prior application, (b) a revised, reformatted or edited version of the prior application that does
`not contain new matter, or (c) a new specification.)
`
`2.
`
`K4
`
`A Power of Attorney is attached. The attached Power of Attorney is:
`
`IZ a. A copy of the Power of Attorney from the parent application.
`
`E]
`
`b. A new Power of Attorney.
`
`[Z
`
`The Power of Attorney is a General Power of Attorney.
`
`A Transmittal of Power of Attorney and Statement Under 37 C.F.R. §3.73(b) is attached, and
`
`A copy of the Assignment I3 is attached to the Transmittal or IE was recorded at Reel 017241
`Frames 0343-344.
`
`D The Power of Attorney is a Specific Power of Attorney for this application.
`
`A Transmittal of Power of Attorney and Statement Under 37 C.F.R. §3.73(b) is attached, and
`
`A copy of the Assignment E] is attached to the Transmittal or D was recorded at Reel
`Frame
`
`E The Power of Attorney is in a combined Declaration/Power of Attorney.
`
`XI
`
`a. The Power of Attorney identifies no more than ten attorneys.
`
`D b. The Power of Attorney identifies more than ten attorneys, and a separate Designation of
`Attorneys for Power of Attorney is filed herewith.
`
`[3 c. The Power of Attorney is to the attorneys associated with a Customer Number.
`
`1
`
`-
`
`ZEISS 1 137
`Zeiss v. Nikon
`
`|PR2013—OO363
`
`1
`
`ZEISS 1137
`Zeiss v. Nikon
`IPR2013-00363
`
`

`
`3.
`
`E The fees due upon filing are calculated below:
`
`CLAIMS IN THE APPLICATION AFTER ENTRY OF
`ANY PRELIMINARY AMENDMENT NOTED BELOW
`
`Rule 53(b) Continuing Application
`ofU.S. Application No. 11/882,208
`Filed July 31, 2007
`
`SMALL ENTITY
`
`OTHER THAN A
`SMALL ENTITY
`
`x 220= |O|O|O|O77757070
`
`$ 540
`
`x
`
`x
`
`270 =
`
`$270
`
`52=
`
`IE3|é3IE3IE3
`
`SEARCH FEE
`
`:
`
`‘
`
`APPLICATION SIZE FEB
`46 _ 50
`Total pages 146 - 100 =
`.
`TOTALCLAIMS @-
`INDEPCLAIMS H-
`E] MULTIPLE DEPENDENT CLAIMS PRESENTED
`*Ifthe difference is less than zero, enter "0".
`Tround up to next integer
`
`4.
`
`K4
`
`Check No. 215428 in the amount of $1360 to cover the fees due upon filing is attached. The
`Commissioner is hereby authorized to charge any other fees that may be required to complete this filing,
`or to credit any overpayment, to Deposit Account No. 15-0461.
`
`IZIEIEE
`
`IXIEIEIEIEIIXI
`
`Application Data Sheet is attached.
`
`Formal drawings (Figs. 1-21) are attached.
`
`Use Figure
`
`for front page of Publication.
`
`
`Priority of foreign applications No. 2003—128154 filed May 6, 2003, No. 2003-350647 filed October 9
`
`2003 and No. 2003-364596 filed October 24 2003 all in JAPAN is claimed under 35 U.S.C. §1l9 and/or
`§365(b).
`
`
`The certified copy was filed in prior Application No. 11/266 288 on November 4 2005.
`
`An electronic copy of the above foreign application(s) was received by the PTO in prior Application
`No.
`
`A certified copy of the above foreign application(s) is filed herewith.
`
`A copy of the priority document was transmitted by the International Bureau in prior Application
`No.
`
`An electronic copy of the above foreign application should be automatically retrieved by the PTO in
`accordance with the electronic priority document exchange service.
`
`
`Priority of U.S. Provisional Application No. 60/721 582 filed September 29, 2005 is claimed under
`35 U.S.C. §119.
`
`(A Preliminary Amendment is attached to reflect the claim of benefit in the specification if not already
`present.)
`
`9.
`
`E]
`
`The prior application is assigned of record to Nikon Comoration, Tolgyo, Japan and recorded at Reel
`017241 Frames 0343-344.
`
`2
`
`

`
`10.
`
`[:1
`
`This application is filed by fewer than all the inventors named in the prior application
`(37 C.F.R §1.53(b)(1)). Delete the following inventor(s) named in the prior application:
`
`Rule 53(b) Continuing Application
`ofU.S. Application No. 11/882,208
`Filed July 31, 2007
`
`A Preliminary Amendment is attached. The Preliminary Amendment amends the specification to reflect
`the continuation data. Claims added by this Amendment are properly numbered consecutively beginning
`with the number next following the highest numbered claim in the application and claims canceled are
`identified in the listing of claims.
`
`An Information Disclosure Statement is attached.
`
`Small entity status:
`
`[I
`
`a. Entitlement to small entity status is asserted.
`
`E]
`
`b. Small entity status is no longer claimed.
`
`Other:
`
`As also indicated in the attached Request, this application is NOT to be published under 35 U.S.C.
`122(b). The undersigned attorney or agent hereby certifies that the invention disclosed in this application
`has not and will not be the subject of an application filed in another country, or under a multilateral
`international agreement, that requires publication of applications 18 months afier filing.
`
`The claims in this continuing application differ from the claims in the parent application(s). As to each
`claim or claim term in this continuing application that is broader than any claim or claim term in any
`parent application, any previous disclaimer of claim scope made during prosecution of any parent
`application is rescinded. The Examiner is requested to consider such broader claims and/or claim terms
`in view of all of the prior art without any previous disclaimers.
`
`*
`
`tfillly submitted,
`
`
`
`gistration 0. 61,276
`
`
`
`11.
`
`E]
`
`12.
`
`13.
`
`[Z]
`
`I3
`
`14.
`
`15.
`
`E]
`
`El
`
`16.
`
`>14
`
`MAC:JTL/jls
`
`DEPOSIT ACCOUNT USE
`AUTHORIZATION
`
`De 0 osit Account No. 15-0461
`
`Please grant any extension
`necessary for entry;
`Charge any fee due to our
`
`3
`
`

`
`o‘;\ .. LT-d
`
`CLIFF & BERRIDGE, PLC
`ATTORN EYS AT LAW
`
`Application Data Sheet
`
`Applicant Information
`
`Applicant Authority type::
`
`Primary Citizenship Country::
`
`Status:
`
`Given Name::
`
`Family Name::
`
`City of Residence::
`
`Inventor
`
`Japan
`
`Full Capacity
`
`Yasuhiro
`
`OMURA
`
`Kumagaya-shi
`
`T JAN
`out f Residence::
`
`
`Correspondence Information
`
`Correspondence Customer Number::
`
`25944
`
`Application Information
`
`Application Type::
`
`Subject Matter::
`
`CD:ROM or CD-R2:
`
`Title::
`
`' Continuation
`
`Utility
`
`None
`
`PROJECTION OPTICAL SYSTEM,
`EXPOSURE APPARATUS, AND
`EXPOSURE METHOD
`
`Attorney Docket Number::
`
`125842.05
`
`Total Drawing Sheets::
`
`Small Entity::
`
`21
`
`No
`
`Representative Information
`
`Attorneys associated with Customer No. 25944.
`
`4
`
`

`
`Domestic Priority Information
`
`Application:
`
`Continuity Type::
`
`
`
`Parent Application:
`
`
`
`Parent Filing
`Date:
`—_——
`This A Iication is a
`11/882,208
`07/31/2007
`—
`Continuation of
`11/266,288
`11/04/2005
`——__
`Continuation-in-art of PCT/JP04/006417
`05/06/2004
`——_—
`Which claims benefit of Provisional
`60/721,582
`09/29/2005
`A Iication No.
`
`Foreign Priority Information
`
`Priorit C|aimed::
`Alication Number:
`————
`JAPAN
`2003-128154
`05/06/2003
`Yes
`————
`A Iication Number:
`Priorit Claimed:
`————
`JAPAN
`2003-350647
`10/09/2003
`————
`A Iication Number::
`Filin Date:
`Priorit Claimed:
`————
`JAPAN
`2003-364596
`10/24/2003
`————
`
`Street of mailin address:
`Cit of mailin address:
`Count
`of mailin address:
`
`Postal or Zi Code of mailin address:
`
`NIKON CORPORATION
`2-3, Marunouchi 3-chome, Chi oda-ku
`
`JAPAN
`
`100-8331
`
`
`
`Page 2
`
`2/20/09
`
`
`
`
`
`————
`
`
`
`5
`
`

`
`Title of the Invention
`
`PROJECTION OPTICAL SYSTEM, EXPOSURE APPARATUS, AND
`
`EXPOSURE METHOD
`
`CROSS-REFERENCE TO RELATED APPLICATIONS
`
`This is a continuation of U.S. Patent Application No. 11/882,208
`
`filed July 31, 2007, which is a continuation of U.S. Patent Application
`
`No. 11/266,288 filed November 4, 2005, which in turn is a continuation-
`
`in—part of International Application No. PCT/JP2004/006417 filed May
`
`6, 2004. Application No. 11/266,288 also claims the benefit of U.S.
`
`10
`
`Provisional Application No. 60/721,582 filed September 29, 2005.
`
`The disclosures of these prior applications are incorporated herein by
`
`reference in their entireties.
`
`Field of the Invention
`
`The present invention relates to a catadioptric projection optical
`
`15
`
`system, exposure apparatus, and exposure method and, more
`
`particularly, to a high—resolution catadioptric projection optical system
`
`suitable for exposure apparatus used in production of semiconductor
`
`devices, liquid-crystal display devices, etc. by photolithography.
`
`Related Background Art
`
`20
`
`The photolithography for production of the semiconductor
`devices and others is implemented using a projection exposure
`
`apparatus for projecting a pattern 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. The resolving power (resolution)
`
`25
`
`required for the projection optical system of the projection exposure
`
`apparatus is becoming increasingly higher and higher with increase in
`
`6
`
`

`
`integration degree of the semiconductor devices and others.
`
`As a result, in order to satisfy the requirements for the resolving
`
`power of the projection optical system, it is necessary to shorten the
`
`wavelength X of illumination light (exposure light) and to increase the
`
`image-side numerical aperture NA of the projection optical system.
`
`Specifically, the resolution of the projection optical system is expressed
`
`by k-X/NA (where k is the process coefficient). The image-side
`
`numerical aperture NA is represented by n-sine, where n is a refractive
`
`10
`
`index of a medium (normally, gas such as air) between the projection
`
`optical system and the image plane and 0 a maximum angle of incidence
`
`to the image plane.
`
`In this case, if the maximum incidence angle 9 is increased in
`
`order to increase the numerical aperture NA, it will result in increasing
`
`15
`
`the input angle to the image plane and the output angle from the
`
`projection optical system, so as to increase reflection loss on optical
`
`surfaces and thus fail to secure a large effective image-side numerical
`
`aperture. For this reason, there is the known technology of increasing
`
`the numerical aperture NA by filling a medium like a liquid with a high
`
`20
`
`refractive index in the optical path between the projection optical
`
`system and the image plane.
`
`However, application of this technology to the ordinary dioptric
`
`projection optical systems caused such disadvantages that it was
`
`difficult to well correct for chromatic aberration and to satisfy the
`
`25
`
`Petzval's condition to well correct for curvature of field, and that an
`
`increase in the scale of the optical system was inevitable.
`
`In addition,
`
`7
`
`

`
`there was another disadvantage that it was difficult to secure a large
`
`effective image-side numerical aperture while well suppressing the
`
`reflection loss on optical surfaces.
`
`Summafl of the Invention
`
`A first object of the embodiment is to provide a relatively
`
`compact projection optical system having excellent imaging
`
`performance as well 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
`
`10
`
`reflection loss on optical surfaces.
`
`In the case where the projection optical system is composed of
`
`only reflecting optical members and in the case where the projection
`
`optical system is composed of a combination of refracting optical
`
`members with reflecting optical members, with increase in the
`
`15
`
`numerical aperture, it becomes more difficult to implement optical path
`
`separation between a beam entering a reflecting optical member and a
`
`beam reflected by the reflecting optical member and it is infeasible to
`
`avoid an increase in the scale of the reflecting optical member, i.e., an
`
`increase in the scale of the projection optical system.
`
`20
`
`In order to achieve simplification of production and
`
`simplification of mutual adjustment of optical members, it is desirable
`
`to construct a catadioptric projection optical system of a single optical
`
`axis; in this case, with increase in the numerical aperture, it also
`
`becomes more difficult to achieve the optical path separation between
`
`25
`
`the beam entering the reflecting optical member and the beam reflected
`
`by the reflecting optical member, and the projection optical system
`
`8
`
`

`
`increases its scale.
`
`A second object of the embodiment is to achieve a large
`
`numerical aperture, without increase in the scale of optical members
`
`forming a catadioptric projection optical system.
`
`A third object of the embodiment is to provide an exposure
`
`apparatus and exposure method capable of performing an exposure to
`
`transcribe a fine pattern with high accuracy through a projection optical
`
`system having excellent imaging performance and having a large
`
`effective image-side numerical aperture and therefore a high resolution.
`
`10
`
`In order to achieve the above—described first object, a projection optical
`
`system according to a first aspect of the embodiment is a catadioptric
`
`projection optical system for forming a reduced image of a first surface
`
`on a second surface,
`
`the projection optical system comprising at least two reflecting
`
`15
`
`mirrors, and a boundary lens whose surface on the first surface side has
`
`a positive refracting 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
`
`20
`
`refiactive index larger than 1.1,
`
`wherein every transmitting member and every reflecting
`
`member with a refracting power constituting the projection optical
`
`system are arranged along a single optical axis, and
`
`the projection optical system having an effective imaging area of
`
`25
`
`a predetermined shape not including the optical axis.
`
`In order to achieve the above—described second object, a
`
`9
`
`

`
`projection optical system according to a second aspect of the
`
`embodiment is a catadioptric projection optical system for forming an
`
`image of a first surface on a second surface, the projection optical
`
`system comprising:
`
`a first imaging optical system comprising two mirrors, for
`
`forming an intermediate image of the first surface; and
`
`a second imaging optical system for forming the intermediate
`
`image_ on the second surface,
`
`wherein the second imaging optical system comprises the
`
`10
`
`following components in order of passage of a ray from the intermediate
`
`image side:
`
`a first field mirror of a concave shape;
`
`a second field mirror;
`
`a first lens unit comprising at least two negative lenses and
`
`15
`
`having a negative refracting power;
`
`a second lens unit having a positive refracting power;
`
`an aperture stop; and
`
`a third lens unit having a positive refracting power.
`
`In order to achieve the above-described second object, a
`
`20
`
`projection optical system according to a third aspect of the embodiment
`
`is a catadioptric projection optical system for forming an image of a first
`
`surface on a second surface, the projection optical system comprising:
`
`a first unit disposed in an optical path between the first surface
`
`and the second surface and having a positive refracting power;
`
`25
`
`a second unit disposed in an optical path between the first unit
`
`and the second surface and comprising at least four mirrors;
`
`10
`
`10
`
`

`
`a third unit disposed in an optical path between the second unit
`
`and the second surface, comprising at least two negative lenses, and
`
`having a negative refracting power; and
`
`a fourth unit disposed in an optical path between the third unit
`
`and the second surface, comprising at least three positive lenses, and
`
`having a positive refracting power,
`
`wherein an intermediate image is formed in the second unit and
`
`wherein an aperture stop is provided in the fourth unit.
`
`In order to achieve the above-described second object, a
`
`10
`
`projection optical system according to a fourth aspect of the
`
`embodiment is a catadioptric projection optical system for forming an
`
`image of a first surface on a second surface, the projection optical
`
`system comprising:
`
`a first imaging optical system comprising at least six mirrors, for
`
`15
`
`forming a first intermediate image and a second intermediate image of
`
`the first surface; and
`
`a second imaging optical system for relaying the second
`
`intermediate image onto the second surface.
`
`In order to achieve the above-described third object, an exposure
`
`20
`
`apparatus according to a fifth aspect of the embodiment is an exposure
`
`apparatus for effecting an exposure of a pattern formed on a mask, onto
`
`a photosensitive substrate, the exposure apparatus comprising:
`
`an illumination system for illuminating the mask set on the first
`
`surface; and
`
`25
`
`the projection optical system according to any one of the above-
`
`described aspects, for forming an image of the pattern formed on the
`
`11
`
`11
`
`

`
`mask, on the photosensitive substrate set on the second surface.
`
`In order to achieve the above-described third object, an exposure
`
`method according to a sixth aspect of the embodiment is an exposure
`
`method of effecting an exposure of a pattern formed on a mask, onto a
`
`photosensitive substrate, the exposure method comprising:
`
`an illumination step of illuminating the mask on which the
`
`predetermined pattern is formed; and
`
`an exposure step of performing an exposure of the pattern of the
`
`mask set on the first surface, onto the photosensitive substrate set on the
`
`10
`
`second surface, using the projection optical system as set forth in the
`
`above.
`
`The present invention will be more fiilly understood from the
`
`detailed description given hereinbelow and the accompanying drawings,
`
`which are given by way of illustration only and are not to be considered
`
`15
`
`as limiting the embodiment.
`
`Further scope of applicability of the embodiment will become
`
`apparent from the detailed description given hereinafter. However, it
`
`should be understood that the detailed description and specific examples,
`
`while indicating preferred embodiments of the invention, are given by
`
`20
`
`Way of illustration only, since various changes and modifications within
`
`the spirit and scope of the invention will be apparent to those skilled in
`
`the art from this detailed description.
`
`Brief Description of the Drawings
`
`Fig. 1 is an illustration schematically showing a configuration of
`
`25
`
`an exposure apparatus according to an embodiment of the embodiment.
`
`Fig. 2 is an illustration showing a positional relation between the
`
`12
`
`12
`
`

`
`optical axis and an effective exposure area of arcuate shape formed. on a
`
`wafer in the embodiment.
`
`Fig. 3 is an illustration schematically showing a configuration
`
`between a boundary lens and a wafer in the first example of the
`
`embodiment.
`
`Fig. 4 is an illustration schematically showing a configuration
`
`between a boundary lens and a wafer in the second example of the
`
`embodiment.
`
`Fig. 5 is an illustration showing a lens configuration of a
`
`10
`
`projection optical system according to the first example of the
`
`embodiment.
`
`Fig. 6 is a diagram showing the transverse aberration in the first’
`
`example.
`
`Fig. 7 is an illustration showing a lens configuration of a
`
`15
`
`projection optical system according to the second example of the
`
`embodiment.
`
`Fig. 8 is a diagram showing the transverse aberration in the
`
`second example.
`
`Fig. 9 is an illustration showing a lens configuration of a
`
`20
`
`catadioptric projection optical system according to the third example.
`
`Fig. 10 is an illustration showing a lens configuration of a
`
`catadioptric projection optical system according to the fourth example.
`
`Fig. 11 is an illustration showing an exposure area on a wafer in
`
`the third and fourth examples.
`
`25
`
`Fig. 12 is a transverse aberration diagram showing the
`
`transverse aberration in the meridional direction and in the sagittal
`
`13
`
`13
`
`

`
`direction of the catadioptric projection optical system in the third
`
`example.
`
`Fig. 13 is a transverse aberration diagram showing the
`
`transverse aberration in the meridional direction and in the sagittal
`
`direction of the catadioptric projection optical system in the fourth
`
`example.
`
`Fig. 14 is an illustration showing a lens configuration of a
`
`catadioptric projection optical system according to the fifth example.
`
`Fig. 15 is an illustration showing a lens configuration of a
`
`10
`
`catadioptric projection optical system according to the sixth example.
`
`Fig. 16 is an illustration showing a lens configuration of a
`
`catadioptric projection optical system according to the seventh example.
`
`Fig. 17 is a transverse aberration diagram showing the
`
`transverse aberration in the meridional direction and in the sagittal
`
`15
`
`direction of the catadioptric projection optical system in the fifth
`
`example.
`
`Fig. 18 is a transverse aberration diagram showing the
`
`transverse aberration in the meridional direction and in the sagittal
`
`direction of the catadioptric projection optical system in the sixth
`
`20
`
`example.
`
`Fig. 19 is a transverse aberration diagram showing the
`
`transverse aberration in the meridional direction and in the sagittal
`
`direction of the catadioptric projection optical system in the seventh
`
`example.
`
`25
`
`Fig. 20 is a flowchart of a method of producing semiconductor
`
`devices as rnicrodevices.
`
`14
`
`14
`
`

`
`Fig. 21 is a flowchart of a method of producing a liquid crystal
`
`display device as a microdevice.
`
`Detailed Description of the Preferred Embodiments
`
`In the projection optical system according to the first aspect of
`
`the embodiment, the medium having the refractive index larger than 1.1
`
`is interposed in the optical path between the boundary lens and the
`
`image plane (second surface), thereby increasing the image—side
`
`numerical aperture NA.
`
`In passing, "Resolution Enhancement of 157-
`
`nm Lithography by Liquid Immersion" reported in "Massachusetts
`
`10
`
`Institute of Technology" in "SPIE2002 Microlithography" by Mr. M.
`
`Switkes and Mr. M. Rothschild describes Fluorinert
`
`,
`
`(Perfluoropolyethers: trade name of 3M, USA) and Deionized Water as
`
`candidates for media having the required transmittance for light of
`
`wavelength X of not more than 200 nm.
`
`15
`
`In the projection optical system according to the first aspect of
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`the embodiment, the optical surface on the object side (first surface
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`side) of the boundary lens is provided with the positive refracting
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`power, whereby the reflection loss is reduced on this optical surface
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`and, in turn, the large effective image—side numerical aperture can be
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`secured.
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`In the optical system having the high-refractive-index
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`material like liquid as the medium on the image side, it is feasible to
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`increase the effective image—side numerical aperture to not less than 1.0
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`and, in turn, to enhance the resolution. However, where the projection
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`magnification is constant, the object-side numerical aperture also
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`increases with increase in the image—side numerical aperture; therefore,
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`if the projection optical system is constructed of only refracting
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`members, it will be difficult to satisfy the Petzval's condition and it will
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`result in failing to avoid the increase in the scale of the optical system.
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`Therefore, the projection optical system according to the first
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`aspect of the embodiment adopts the catadioptric system of the type
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`comprising at least two reflecting mirrors, in which every transmitting
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`member and every reflecting member with a refracting power (power)
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`are arranged along the single optical axis and which has the effective
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`imaging area of the predetermined shape not including the optical axis.
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`In the projection optical system of this type, for example, through action
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`of a concave reflecting mirror, it is feasible to well correct for the
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`chromatic aberration and to readily satisfy the Petzval's condition to
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`well correct for the curvature of field, and the scale of the optical system
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`can be reduced.
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`The projection optical system of this type has the configuration
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`wherein every transmitting member (lenses or the like) and every
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`reflecting member with a power (concave reflecting mirrors or the like)
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`are arranged along the single optical axis, which is preferable because
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`the degree of difficulty in production is considerably lower than in a
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`multi-axis configuration wherein the optical members are arranged
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`along multiple optical axes. However, in the case of the single-axis
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`configuration wherein the optical members are arranged along the single
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`optical axis, the chromatic aberration tends to be difficult to well correct
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`for, but this problem of correction for chromatic aberration can be
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`overcome, for example, by use of laser light with a narrowed spectral
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`width like ArF laser light.
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`In this manner, the first aspect of the embodiment can realize the
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`relatively compact projection optical system having the excellent
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`imaging performance as well corrected for the various aberrations such
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`as chromatic aberration and curvature of field and being capable of
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`securing the large effective image-side numerical aperture while well
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`suppressing the reflection loss on the optical surfaces. Therefore, an
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`exposure apparatus and exposure method using the projection optical
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`system according to the first aspect of the embodiment are able to
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`perform an exposure of a fine pattern to transcribe the pattern through
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`the projection optical system having the excellent imaging performance
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`and the large effective image-side numerical aperture and therefore the
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`high resolution.
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`In the first aspect of the embodiment, the projection optical
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`system is preferably arranged to have an even number of reflecting
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`mirrors, i.e., to form the image of the first surface on the second surface
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`through an even number of reflections. When the projection optical
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`system in this configuration is applied, for example, to the exposure
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`apparatus and exposure method, not a mirror image ( a flipped image)
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`but an unrnirrored (unflipped) image (erect image or inverted image) of
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`the mask pattern, is formed on the wafer, whereby the ordinary masks
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`(reticles) can be used as in the case of the exposure apparatus equipped
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`with the dioptric projection optical system.
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`In the first aspect of the embodiment, the projection optical
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`system preferably comprises: a first imaging optical system comprising
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`two mirrors, which forms an intermediate image of the first surface; and
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`a second imaging optical system, which forms the intermediate image
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`on the second surface; the second imaging optical system preferably
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`comprises the following components in order of passage of a ray from
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`the intermediate image side: a first field mirror of a concave shape; a
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`second field mirror; a first lens unit comprising at least two negative
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`lenses and having a negative refracting power; a second lens unit having
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`a positive refracting power; an aperture stop; and a third lens unit
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`having a positive refracting power.
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`In this configuration, the intermediate image of the first surface
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`is formed in the first imaging optical system, and it is thus feasible to
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`readily and securely achieve the optical path separation between the
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`beam toward the first surface and the beam toward the second surface,
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`even in the case where the numerical apertures are increased of the
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`catadioptric projection optical system.
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`Since the second imaging
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`optical system comprises the first lens unit having the negative
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`refracting power, the total length of the catadioptric projection optical
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`system can be reduced, and adjustment for satisfying the Petzval's
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`condition can be readily performed.
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`Furthermore, the first lens unit
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`relieves variation due to the difference of field angles of the beam
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`expanded by the first field mirror, so as to suppress occurrence of
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`aberration. Therefore, the good imaging performance can be achieved
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`throughout the entire region in the exposure area, even in the case where
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`the obj ect-side and image-side numerical apertures of the catadioptric
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`projection optical system are increased in order to enhance the
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`resolution.
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`In the above—described configuration, preferably, the first
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`imaging optical system comprises a fourth lens unit having a positive
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`refracting power, a negative lens, a concave mirror, and an optical path
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`separating mirror; and the first imaging optical system is arranged as
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`follows: light traveling in the first imaging optical system passes
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`through the fourth lens unit and the negative lens, is then reflected by
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`the concave mirror, and passes again through the negative lens to be
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`guided to the optical path separating mirror; the light reflected by the
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`optical path separating mirror is reflected by the first field mirror and
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`the second field mirror and thereafter directly enters the first lens unit in
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`the second imaging optical system.
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`In this configuration, the projection optical system can be
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`telecentric on the first surface side because the first imaging optical
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`system comprises the fourth lens unit having the positive refracting
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`power.
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`Since the firstimaging optical system comprises the negative
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`lens and the concave mirror, adjustment for satisfying the Petzva1's
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`condition can be readily performed by adjusting the negative lens and
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`the concave mirror.
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`In the first aspect of the embodiment, the projection optical
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`system preferably comprises a first imaging optical system comprising
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`at least six mirrors for forming a first intermediate image and a second
`intermediate image of the first surface; and a second imaging optical‘
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`system , which relays the second intermediate image onto the second
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`surface.
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`Since this configuration comprises at least six mirrors, the first
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`intermediate image and the second intermediate image can be formed
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`without increase in the total length of the catadioptric projection optical
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`system, and the good imaging performance can be achieved throughout
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`the entire region in the exposure area, even in the case where the object-
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`side and the image-side numerical apertures of the catadioptric
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`projection optical system are increased in order to enhance the
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`resolution.
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`In the aforementioned configuration, preferably, the first
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`intermediate image is formed between a mirror that light emerging from
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`the first surface enters second and a mirror that the light emerging from
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`the first surface enters fourth, out of the at least six mirrors in the first
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`imaging optical system.
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`In this configuration, the first intermediate image is formed
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`between the mirror that the light emerging from the first surface enters
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`second and the mirror that the light emerging from the first surface
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`enters fourth. Therefore, even in the case where the object-side and
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`image-side numerical apertures of the catadioptric projection optical
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`system are increased in order to enhance the resolution, it is feasible to
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`readily and securely achieve the optical path separation between the
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`beam toward the first surface and the beam toward the second surface
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`and to achieve the good imaging performance throughout the entire
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`region in the exposure area.
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`Incidentally, since it is necessary to form the intermediate image
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`20
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`near the pupil position in order to construct the catadioptric projection
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`optical system of the single optical axis according to the first aspect of
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`the embodiment, it is desirable to construct the projection optical system ‘
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`as a reimaging optical system.
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`In order to avoid mechanical
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`interference between optical members while achieving the optical path
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`separation with the intermediate image being formed near the pupil
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`position of the first imaging, the pupil diameter of the first imaging
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`needs to be set as small as possible even in the case where the object-
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`side numerical aperture is large; therefore, the first imaging optical
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`system with the small numerical aperture is desirably a catadioptric
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`system.
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`In the first aspect of the embodime