US20080068705A1 - Projection optical system and method - Google Patents

Abstract

A refractive projection optical system for imaging a first object into a region of a second object comprises a plurality of lenses disposed along an imaging beam path of the projection optical system; wherein the projection optical system is configured to have a numerical aperture on a side of the second object of greater than 1 wherein the projection optical system is configured to generate an intermediate image of the first object and to image the intermediate image into the region of the second object, wherein the intermediate image is formed in between the first and second objects.

Description

BACKGROUND OF THE INVENTION
• 1. Field of the Invention
• The present invention relates to a projection optical system, in particular an micro-lithographic projection optical system.
• 2. Brief Description of Related Art
• Lithographic processes are commonly used in the manufacture of semiconductor elements, such as integrated circuits (ICs), LSIs, liquid crystal elements, micropatterned members and micromechanical components.
• A projection exposure apparatus used for photolithography generally comprises an illumination optical system having a light source and a projection optical system. Light from the illumination optical system illuminates a reticle (a first object) having a given pattern, and the projection optical system transfers an image of the reticle pattern, onto a region of a photo-sensitive substrate (a second object). The image of the reticle pattern may also be reduced in size by the projection optical system so as to produce a smaller image of the reticle pattern on the substrate.
• The trend to ever smaller and more sophisticated miniaturized devices places increasingly high demands on the projection exposure systems and thus projection optical systems used for the manufacture of these devices. In order to achieve higher resolutions in the exposure of substrates, the imaging of the reticle onto the substrate has to be performed with a sufficiently high numerical aperture (NA) on the side of the substrate. Therefore, an increase of the numerical aperture is a decisive factor in the development of improved projection exposure systems.
• Projection exposure systems having a high numerical aperture are known from US 2003/0007253 A1 and WO 2003/075049 A2 and WO 2005/054956 A2 which documents are incorporated herein by reference.
• Some conventional projection exposure systems are able to achieve a numerical aperture of greater than 1. One example of such projection exposure systems is referred to as a projection exposure system of the immersion type, known for example from WO 2003/077037 A1, which document is incorporated herein by reference. Another example of such projection exposure system is referred to as a projection exposure system of the near field exposure type or solid immersion type, known for example from WO 2003/077036 A1, which document is incorporated herein by reference.
• High numerical apertures also bring about a whole range of challenges in terms of a design of the projection optical system. In purely refractive optical systems for projection exposure the requirements for correction of imaging errors, such as aberrations and the like, are increasing with increasing numerical aperture on an image side of the optical system. In addition to the demand for a well corrected wavefront, parameters such as a telecentricity on a reticle side need to be taken into account. These requirements are typically met by using aspherical lenses close to an image side of the projection optical system.
• Projection optical systems tend to increase in weight and size as the numerical aperture of such systems increases. In particular, diameters of lenses increase to such an extent that they become very expensive and difficult to manufacture, and the manufacture of aspherical lenses of a high diameter and a sufficient accuracy presents particular problems.
SUMMARY OF THE INVENTION
• The present invention has been accomplished taking the above problems into consideration.
• Embodiments of the present invention provide a projection optical system having a high numerical aperture and having a good imaging performance.
• Further embodiments of the present invention provide a projection optical system having a high numerical aperture, wherein diameters of lenses used in the projection optical system can be maintained within an acceptable range.
• Further embodiments of the present invention provide a projection optical system having a numerical aperture higher than 1 and having a good imaging performance.
• Further embodiments of the present invention provide a projection optical system having a numerical aperture higher than 1, wherein diameters of lenses used in the projection optical system can be maintained within an acceptable range.
• Further embodiments of the present invention provide an improved method of manufacturing a microstructured device and provide a microstructured device manufactured by such a method.
• According to an exemplary embodiment of the present invention a refractive projection optical system for imaging a first object into a region of a second object comprises: a plurality of lenses disposed along an imaging beam path of the projection optical system; wherein the projection optical system is configured to have a numerical aperture on a side of the second object of greater than 1; wherein the projection optical system is configured to generate an intermediate image of the first object and to image the intermediate image into the region of the second object, wherein the intermediate image is formed in between the first and second objects.
• In the context of the present invention, the term refractive optical system refers to systems where substantially all optical powers are provided by refractive lens elements. This is in contrast to a catadioptric optical system having at least one mirror providing a substantial amount of optical power. It is not excluded, however, that the refractive optical system according to the present invention comprises one or more mirrors for folding the beam path through the system to reduce its size, provided that such mirror is sufficiently flat to provide substantially no optical power.
• According to an exemplary embodiment of the invention the radius of curvature of the mirror of the refractive optical system is greater than 10³m.
• The present inventors have found that the concept of generating an intermediate image within the refractive optical system allows for an improved imaging quality at a high numerical aperture while maintaining free diameters of the lenses within an acceptable range.
• The term intermediate image as used herein stands for a real intermediate image, as opposed to a virtual intermediate image.
• The refractive optical system comprises a plurality of lenses. The plurality of lenses is dividable into a plurality of non-overlapping groups of lenses, such that a total refractive power of each group of lenses is one of a negative refractive power and a positive refractive power, and that a sum of the absolute values of the total refractive powers of the groups is a maximum value.
• A lens, as used herein, relates to a single lens element and not to an optical system comprised of a plurality of lens elements.
• A group of lenses, as used herein, may consist of a single lens only or more than one lens.
• According to an exemplary embodiment, the intermediate image is formed in a region between two adjacent lens groups having positive refractive power, wherein one lens group of negative refractive power may be disposed between these two lens groups of positive refractive power.
• According to an exemplary embodiment herein, a lens group of negative optical power and a further lens group of positive optical power is disposed between these two lens groups of positive refractive power and the second object.
• According to a further exemplary embodiment herein, three lens groups of negative, positive and negative optical powers, respectively, are disposed between these two lens groups of positive refractive power and the first object. According to a further alternative exemplary embodiment herein, four lens groups of positive, negative, positive and negative optical powers, respectively, are disposed between these two lens groups of positive refractive power and the first object.
• According to an exemplary embodiment, the refractive optical system is of an immersion type, having a liquid having a refractive index of greater than one provided in between of the second object and a front lens of the plurality of lenses disposed closest to the second object. Such immersion liquid allows to achieve particular high values of the numerical aperture. As an example of an immersion liquid having a refractive index of greater than one distilled deionized water may be mentioned which has a refractive index of 1.44 at a wavelength of 193 nm.
• According to an exemplary embodiment, the projection optical system has a numerical aperture that is greater than 1.1.
• According to other exemplary embodiments, the projection optical system has a numerical aperture that is greater than 1.2 and in particular greater than 1.3.
• According to exemplary embodiments, an imaging magnification of the optical system is less than 1.0, such that the image formed in the region of the second object is reduced in size as compared to the original provided by the first object.
• In exemplary embodiments of the projection optical system, an absolute value of a magnification of the imaging of the intermediate image into the region of the second object is less than 0.5.
• In further exemplary embodiments, an absolute value of a magnification of the imaging of the first object into the intermediate image is greater than 0.5.
• In further exemplary embodiments, a ratio of a magnification of the imaging of the first object into the intermediate image over a magnification of the imaging of the intermediate image into the region of the second object is in a range of about 2 to 10. For example, the ratio may be in a range of about 2.5 to 4.5, or 3 to 10.
• The choice of magnification of the imaging of the first object and the imaging of the intermediate image and their ratio may be used as a degree of freedom for achieving an improved design of the immersion type projection optical system.
• In an exemplary embodiment of the present invention, the projection optical system is divided into two sub-systems: a first subsystem of lenses which is configured to generate a real intermediate image of the first object, and a second sub-system of lenses which generates a reduced size image of the intermediate image in a region of the second object. In particular in those embodiments, there are substantial deviations from telecentricity in a location of the intermediate image in the projection optical system. Such an embodiment is advantageous in that the second sub-system may be designed such that is generates a good wavefront and comprises only lenses having relatively small effective diameters since the parameters telecentricity and aberration are corrected for or determined, respectively, by the first sub-system, which generates an intermediate image at a magnification of about 1. Therefore, one group of imaging errors is corrected in the first sub-system whereas a different group of imaging errors is corrected for in the second sub-system, wherein a combination of the correction of both sub-system not only results in good imaging properties, but also allows a projection optical system having only lenses of a relatively small effective diameter.
• The imaging of the first object into the intermediate image, in an exemplary embodiment, is such that at least one of the following conditions is fulfilled: an angle of at least one chief ray (as a measure for telecentricity) of the intermediate image is greater than 4°, a longitudinal spherical aberration of the intermediate image is greater than 0.8 mm, an astigmatism value of the intermediate image is greater than 11.0 mm, an aberration of the intermediate image is greater than 1.5%, a RMS (root mean square) of a spot diameter on an optical axis of the projection optical system is greater than 0.5 mm, a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is greater than 5 mm. In other words, in exemplary embodiments, an intermediate image is not telecentric, or is distorted, or is subject to spherical aberrations, or has coma, or has a chromatic error, or a combination thereof.
• For example, in some exemplary embodiments, the imaging of the first object into the intermediate image is such that at least one of the following conditions is fulfilled: an angle of at least one chief ray of the intermediate image may be greater than 8°, in particular greater 15°, and in particular greater 25°; a longitudinal spherical aberration of the intermediate image may be greater than 0.9 mm, in particular 12 mm; an astigmatism value of the intermediate image may be greater than or equal to 20 mm, in particular 30 mm; an absolute value of an aberration of the intermediate image may be greater than 2%, in particular 8%; a RMS of a spot diameter on an optical axis of the projection optical system may be greater than 0.6 mm, in particular 1 mm; a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system may be greater than or equal to 10 mm, in particular 16 mm.
• According to an exemplary embodiment, a RMS (root mean square) deviation of a wavefront at the intermediate image is greater than 10 times a diffraction limit. The diffraction limit may be defined as λ/NA, wherein λ is the wavelength of the light used for imaging and NA is the numerical aperture of the imaging at the intermediate image. For example, if it is assumed that the imaging is performed with spherical wavefronts emerging from the first object, the imaging wavefronts at the intermediate image will be distorted wavefronts deviating from the spherical shape, wherein an RMS value of such deviation may be greater than 10λ/NA.
• However, such aberration of wavefronts at the intermediate image is compensated for in the imaging of the intermediate image onto the second object. In exemplary embodiments of the invention, the RMS deviation at the second object may be less than λ/(10 NA), wherein NA is the numerical aperture of the imaging at the second object. According to further preferred exemplary embodiments of the invention, the RMS deviation of wavefronts at the second object may be less than λ/(50 NA).
• According to further exemplary embodiments, the imaging from the first object into the second object is configured such that at least one, or all, of the following conditions is fulfilled: an angle of at least one chief ray of the image is less than 1°; a longitudinal spherical aberration of the image is less than 0.001 mm; an astigmatism value of the image is less than 100 nm; an aberration of the image is less than 0.001%; a RMS of a spot diameter on an optical axis of the projection optical system is less than 0.001 mm; a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is less than 0.002 mm; and a RMS deviation of a wave front is less than 0.1 times a diffraction limit.
• In an exemplary embodiment, the projection optical system is rotationally symmetrical, i.e. the plurality of lenses are disposed along an optical axis of the projection optical system such that their centers are located on the optical axis.
• In an exemplary embodiment, the projection optical system is free of a physical beam splitter, such as a semitransparent mirror.
• In further exemplary embodiments, the intermediate image has a significant field curvature with a radius of curvature which is less than four times of its free diameter, in particular less than twice its free diameter or less than its free diameter.
• The term design distance or design length as used herein stands for a distance between the first object and the second object in an operating or exposure mode, i.e. as foreseen by the design of the projection optical system when both the first and the second objects are in focus. If for example, a folded arrangement is used, the distance between the first object and the second object would be represented by a distance between a plane where the first object is disposed in and a plane where the second object is disposed in.
• In an exemplary embodiment of the present invention, the design length L is greater than about 1100 mm or, preferably greater than about 1300 mm, wherein the embodiment is purely refractive.
• Embodiments of immersion type projection optical systems generally allow to use lenses having a relatively small effective diameter. In exemplary embodiments of the immersion type projection optical system, an effective diameter of any lens of the plurality of lenses is smaller than 250 mm.
• The refractive projection optical system having one intermediate image may be divided into lenses that generate the intermediate image, i.e. lenses in between the first object and a location of the intermediate image, and lenses that image the intermediate image, i.e. lenses that are disposed in between the location of the intermediate image and the second object. In exemplary embodiments of the present invention, effective diameters of the lenses that generate the intermediate image are preferably smaller than 220 mm, or effective diameters of the lenses that image the intermediate image are preferably smaller than 245 mm, or both.
• In an exemplary embodiment of the present invention, the plurality of lenses of the projection optical system is dividable into nine non-overlapping groups of lenses, such that a total refractive power of a first group disposed closest to the first object is a positive refractive power; a total refractive power of a second group disposed directly adjacent to the first group is a negative refractive power; a total refractive power of a third group disposed directly adjacent to the second group is a positive refractive power; a total refractive power of a fourth group disposed directly adjacent to the third group is a negative refractive power; a total refractive power of a fifth group disposed directly adjacent to the fourth group is a positive refractive power; a total refractive power of a sixth group disposed directly adjacent to the fifth group is a negative refractive power; a total refractive power of a seventh group disposed directly adjacent to the sixth group is a positive refractive power; a total refractive power of an eighth group disposed directly adjacent to the seventh group is a negative refractive power; and a total refractive power of a ninth group disposed directly adjacent to the eighth group is a positive refractive power. The grouping of lenses is defined such that a sum of the absolute values of the total refractive powers of the first to ninth groups is a maximum value.
• Such arrangement of lens groups in the projection optical system results in what would generally be referred to as having three waists. The waist indicates constrictions within the projection optical system. In an exemplary embodiment of the above arrangement of groups of lenses, a first waist is formed in a region of the fourth group of lenses, a second waist is formed in a region of the sixth group of lenses and a third waist is formed in a region of the eighth group of lenses.
• It is preferred that the projection optical system comprises an aperture stop. In exemplary embodiments, the projection optical system comprises an aperture stop disposed between two lenses of the ninth group of lenses. In those embodiments, the ninth group of lenses consists of a first sub-group of lenses that is disposed in between the first object, or more precisely the eighth group of lenses, and the aperture stop and a second sub-group of lenses in between the aperture stop and the second object.
• In alternative exemplary embodiments, the aperture stop may be disposed in any other group of lenses. Generally, the aperture stop may be disposed in a part of the projection optical system that is closer to the second object or a part of the projection optical system that is closer to the first object, with the former being preferred.
• The aperture stop used in embodiments of the present invention may be adjustable. An example of such an aperture is described in U.S. Pat. No. 6,445,510.
• Preferably, an effective diameter of any lens in a group of lenses having a total negative refractive power is equal to or smaller than an effective diameter of any lens in a group of lenses which in total has a positive refractive power and is disposed directly adjacent to the respective group of lenses having a total negative refractive power.
• Further embodiments of the present invention provide an immersion type projection exposure system comprising an illumination optical system for generating a light beam of light, a mount for mounting a patterning structure as a first object, a substrate mount for mounting a radiation sensitive substrate as a second object, and the refractive projection optical system according to the first aspect of the present invention for imaging the patterning structure (first object) into a region of the radiation sensitive substrate (second object).
• The term patterning structure as used herein refers broadly to any means suited for endowing an illuminating light beam with a patterned cross-section, an image of which pattern (of the illuminated patterning structure) is projected onto the substrate. The patterning structure may be a mask or a reticle, for example. Mask or reticle types include binary, attenuating and alternating phase shift types, and various hybrid types. The mask/reticle may transmit or reflect the illumination light beam whilst imparting a patterned cross-section upon it. Programmable mirror arrays are further examples of patterning structures suitable for use with the present invention. One example of such an array is described, for example, in U.S. Pat. No. 5,296,891. An additional example of a programmable mirror array is disclosed in U.S. Pat. No. 5,523,193. Programmable LCD arrays are further examples of patterning structures suitable for use with the present invention. Such an array is disclosed in U.S. Pat. No. 5,229,872, for example. Generally, light valves or illumination templates are additional terms used in connection with patterning structures.
• In exemplary embodiments of the projection optical system the imaging beam has a wavelength of shorter than 250 nm, preferably shorter than 200 nm.
• Further embodiments of the present invention provide a method of manufacturing a microstructured device, the method comprising: a first imaging of a patterning structure into an intermediate image of; and a second imaging of the intermediate image of the patterning structure into a region of a radiation sensitive substrate for exposing the radiation sensitive substrate; wherein the second imaging has a numerical aperture on a side of the radiation sensitive substrate of greater than one, and wherein the first imaging and the second imaging is performed by using a refractive projection optical system.
• According to an exemplary embodiment, the imaging is performed using the refractive projection optical system as illustrated above.
• According to an exemplary embodiment herein, the first imaging comprises: a first expanding of a cross section of an imaging beam downstream of the patterning structure; a first reducing of the cross section of the imaging beam downstream of the first expanding of the cross section; a second expanding of the cross section of the imaging beam downstream of the first reducing of the cross section; and a second reducing of the cross section of the imaging beam downstream of the second expanding of the cross section.
• According to an exemplary embodiment herein, the first imaging further comprises: a third expanding of the cross section of the imaging beam downstream of the second reducing of the cross section; and a third reducing of the cross section of the imaging beam downstream of the third expanding of the cross section.
• According to an exemplary embodiment herein, the second imaging comprises: a fourth expanding of the cross section of the imaging beam downstream of the intermediate image; a fourth reducing of the cross section of the imaging beam downstream of the fourth expanding of the cross section; a fifth expanding of the cross section of the imaging beam downstream of the fourth reducing of the cross section; and a fifth reducing of the cross section of the imaging beam downstream of the fifth expanding of the cross section; wherein the imaging beam is incident onto the radiation sensitive substrate downstream of the second reducing of the cross section.
• According to further exemplary embodiments, the imaging of the projection optical system is colour corrected for only a comparatively narrow range of wavelengths adapted to the light source used for generating the radiation for producing the image. An example of such light source is an excimer laser.
• According to an exemplary embodiment, the projection optical system is monochromatic. According to an exemplary embodiment herein, substantially all lenses of the projection optical system are made of a same lens material. An example of such lens material is quartz adapted for ultraviolet light applications (SILUV).
• In a further aspect, the present invention also provides a microstructured device manufactured by the above method.
BRIEF DESCRIPTION OF THE DRAWINGS
• The foregoing as well as other advantageous features of the invention will be more apparent from the following detailed description of exemplary embodiments of the invention with reference to the accompanying drawings. It is noted that not all possible embodiments of the present invention necessarily exhibit each and every, or any, of the advantages identified herein.
• FIG. 1 is a schematic illustration of a first exemplary embodiment of a projection optical system according to the present invention;
• FIG. 2 is a schematic illustration of a second exemplary embodiment of a projection optical system according to the present invention;
• FIG. 3 is a schematic illustration of a third exemplary embodiment of a projection optical system according to the present invention;
• FIG. 4 is a schematic illustration of a fourth exemplary embodiment of a projection optical system according to the present invention; and
• FIG. 5 shows a detail ofFIG. 4.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
• In the exemplary embodiments described below, components that are alike in function and structure are designated as far as possible by alike reference numerals. Therefore, to understand the features of the individual components of a specific embodiment, the descriptions of other embodiments and of the summary of the invention should be referred to.
• InFIG. 1, an optical path diagram of a first exemplary embodiment of a projection optical system according to the present invention is depicted. As indicated by the brackets, a first group of lenses LG1 includes fourlenses1,2,3 and has positive refractive power; a second group of lenses LG2 is formed of (single)lens4 and has negative optical power; the third group of lenses LG3 includes fivelenses5,6,7,8,9 and has positive refractive power; the fourth group of lenses LG4 includes twolenses10,11 and has negative refractive power; the fifth group of lenses LG5 includes fourlenses12,13,14,15 and has positive refractive power; the sixth group of lenses LG6 includes twolenses16,17 and has negative refractive power; the seventh group of lenses LG7 includes fourlenses18,19,20,21 and has positive refractive power; the eighth group of lenses LG8 includes threelenses22,23,24 and has negative refractive power; and afirst subgroup SG₉1 of the ninth group of lenses LG9 includes threelenses25,26,27 and has positive refractive power, asecond subgroup SG₉2 of the ninth group of lenses LG9 includes fourlenses28,29,30,31 and has also positive refractive power.
• In particular, in a direction from the first object to the second object, the first group of lenses LG1 includes a plane parallel plate1, a biconvex lens2, a convex meniscus lens3; lens4 of LG2 is a biconcave lens; the third group of lenses LG3 includes a meniscus lens5, a nearly planar convex lens6, a biconvex lens7 and two meniscus lenses8,9; the fourth group of lenses LG4 includes two biconcave lenses10,11, wherein both of those biconcave lenses have one surface which has a greater curvature than a respective second surface and wherein those surfaces of the biconcave lenses which have the greater curvature face each other; the fifth group of lenses LG5 is a fairly symmetrical arrangement of two convex meniscus lenses12,15 and two biconvex lenses13,14 in between the two meniscus lenses12,15; the sixth group of lenses LG6 includes two biconcave lenses16,17; the seventh group of lenses LG7 includes two meniscus lenses18,21 and two biconvex lenses19,20 in between the two meniscus lenses18,21; the eighth group of lenses LG8 includes a meniscus lens22, a biconcave lens23 and a concave meniscus lens24; and the ninth group of lenses LG9 comprises two convex meniscus25,26 lenses, two biconvex lenses27,28 and two convex meniscus lenses29,30 as well as a lens31 with a convex surface facing in the direction of the first object and a planar surface in a direction of the second object.
• Overall, the projection optical system includes 31 lenses. The ninth group of lenses LG9 also includes an aperture stop in between the first and the second subgroups.
• A center of an intermediate image is formed within the sixth group of lenses LG6, and is located in particular in between thefirst lens16 and thesecond lens17 of lens group LG6. Rays emanating from a point on the optical axis under different angles cross there in one point. It can also be seen inFIG. 1 that rays emanating from points located at a distance from the optical axis do not cross in a single point, due to coma. Therefore, the intermediate image formed is not a perfect “sharp” image.
• In this exemplary embodiment of the present invention, an angle of at least one chief ray of the intermediate image is about 8.6°, a longitudinal spherical aberration of the intermediate image is about 13 mm, an astigmatism value of the intermediate image is about 30 mm, an aberration of the intermediate image is about 9%, a RMS of a spot diameter on the optical axis of the projection optical system is about 1 mm, a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is about 16 mm.
• Detailed information on parameters of the lenses, such as thickness of the lens, lens material, radius of curvature of the optical surface and one half of the effective diameter of the lens are listed in Table 1 (radius, thickness and diameter are given in units of mm; the refractive index is given for a wavelength of 193 nm). In addition, an indication of a position of aspherical surfaces in the projection optical system and their parameters are given in Table 1.

  TABLE 1
  				Lens	Refractive	½
  Lens#	Surface	Radius	Thickness	material	Index	Diameter
  	0	∞	40.000000000		1.00000000	53.000
  1	1	∞	10.000000000	SILUV	1.56049116	64.526
  	2	∞	1.000000000		1.00000000	66.329
  2	3	1188.659667350 AS	21.468222523	SILUV	1.56049116	67.830
  	4	−325.055504302	1.000000000		1.00000000	68.736
  3	5	155.617006797	22.934934551	SILUV	1.56049116	69.283
  	6	727.536884813	18.174889229		1.00000000	67.710
  4	7	−192.646034091	14.999828607	SILUV	1.56049116	67.126
  	8	273.881364877 AS	50.665512844		1.00000000	67.600
  5	9	−77.020751690	45.516341012	SILUV	1.56049116	67.888
  	10	−114.604649117	1.000000000		1.00000000	92.155
  6	11	−109987.496020000	40.293744935	SILUV	1.56049116	107.213
  	12	−208.761364284	1.000000000		1.00000000	109.107
  7	13	312.047113737	37.896771546	SILUV	1.56049116	107.966
  	14	−391.379716197 AS	1.000000000		1.00000000	106.562
  8	15	140.792401571	38.279905762	SILUV	1.56049116	94.431
  	16	595.044328920	1.000000000		1.00000000	90.332
  9	17	89.636711846	32.204876945	SILUV	1.56049116	70.645
  	18	111.608346837	19.054222657		1.00000000	58.330
  10	19	−429.397084300 AS	18.209656873	SILUV	1.56049116	57.080
  	20	98.226077778	50.232325179		1.00000000	41.561
  11	21	−61.703307112	11.999904429	SILUV	1.56049116	37.972
  	22	1661.483397630	49.691525854		1.00000000	47.513
  12	23	−344.829665657	42.085244023	SILUV	1.56049116	75.077
  	24	−107.671909899	1.000000000		1.000000000	81.492
  13	25	227.651221386	37.735333942	SILUV	1.56049116	96.198
  	26	−971.294005629	1.000000000		1.00000000	96.695
  14	27	2411.309898770	35.231061101	SILUV	1.56049116	96.779
  	28	−172.470493948 AS	1.000000000		1.00000000	96.697
  15	29	127.199282894	35.979585035	SILUV	1.56049116	83.764
  	30	590.640003478	22.420160606		1.00000000	79.423
  16	31	−1136.135888880	11.999850457	SILUV	1.56049116	69.651
  	32	97.965840133	33.048150980		1.00000000	58.175
  17	33	−150.955637569	11.999737315	SILUV	1.56049116	57.812
  	34	119.446001017 AS	28.704766869		1.00000000	59.976
  18	35	−169.101684614	30.810844072	SILUV	1.56049116	60.862
  	36	−143.556940908	1.000000000		1.00000000	71.166
  19	37	6059.614308150	27.240629998	SILUV	1.56049116	78.835
  	38	−198.152203067	1.000000000		1.00000000	80.968
  20	39	237.266870348 AS	35.744593296	SILUV	1.56049116	84.978
  	40	−432.817798201	1.000000000		1.00000000	83.945
  21	41	118.462571930	35.488600864	SILUV	1.56049116	78.566
  	42	685.595455023	33.017147840		1.00000000	74.975
  22	43	428.917580057	12.000000000	SILUV	1.56049116	57.406
  	44	227.044290939	20.509997540		1.00000000	52.054
  23	45	−102.067563936 AS	10.000000000	SILUV	1.56049116	51.298
  	46	101.557348748	41.525133257		1.00000000	49.401
  24	47	−59.061918360	22.768528549	SILUV	1.56049116	49.766
  	48	−1043.526546090 AS	16.290454399		1.00000000	78.032
  25	49	−178.935907735	32.555772497	SILUV	1.56049116	79.473
  	50	−106.364609023	1.000000000		1.00000000	85.792
  26	51	−632.435188067	39.079252875	SILUV	1.56049116	107.073
  	52	−174.987008053	1.000000000		1.00000000	110.790
  27	53	2805.478184950	38.636643743	SILUV	1.56049116	121.294
  	54	−294.402220845	14.000000000		1.00000000	122.565
  	55	∞	−13.000000000		1.00000000	120.985
  28	56	341.515594164 AS	41.973867680	SILUV	1.56049116	121.957
  	57	−613.012676946	1.000000000		1.00000000	121.709
  29	58	186.221573607	40.343551809	SILUV	1.56049116	113.484
  	59	854.107417415	0.999662417		1.00000000	110.285
  30	60	118.210352635	35.190252216	SILUV	1.56049116	91.465
  	61	221.690971967	1.000000000		1.00000000	85.108
  31	62	93.839361326	85.998752419	SILUV	1.56049116	70.310
  	63	∞	1.999818350	Water	1.43680000	15.666
  	64	∞	0.000181480		1.00000000	13.250

  Aspherical Surfaces

  	Surface 3	Surface 8	Surface 14
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 5.70001135e−008	C1: −2.34985768e−008	C1: 4.54530065e−008
  	C2: 9.7673749ge−012	C2: 5.68067165e−012	C2: −2.99107441e−013
  	C3: 8.19029831e−017	C3: −1.05424515e−015	C3: 2.61057788e−017
  	C4: 8.84893220e−020	C4: 2.80117106e−019	C4: −2.36906603e−023
  	C5: −1.76156850e−023	C5: −4.74649134e−023	C5: 2.40679240e−026
  	C6: 1.45768927e−0274	C6: 3.78500346e−027	C6: −9.4351673ge−031
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 19	Surface 28	Surface 34
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 2.63529568e−007	C1: 8.72339285e−008	C1: −3.077I5536e−008
  	C2: −1.38048336e−011	C2: −5.87555973e−013	C2: 2.82667732e−012
  	C3: 9.47230160e−016	C3: 3.69484334e−017	C3: −3.58560604e−015
  	C4: −1.39516446e−019	C4: −8.29838683e−022	C4: 4.34984764e−019
  	C5: 3.34855694e−023	C5: 2.8II5454ge−026	C5: −7.279I4300e−024
  	C6: −2.5433053ge−027	C6: 1.10167667e−031	C6: −1.84976566e−027
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 39	Surface 45	Surface 48
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 5.07I96594e−008	C1: 2.I7356870e−007	C1: 4.82747886e−009
  	C2: 1.34564781−012	C2: −3.86297236e−011	C2: −7.95248576e−012
  	C3: −7.71337598e−017	C3: 4.28396866e−015	C3: 9.I45I327Ie−016
  	C4: −4.89233493e−021	C4: 3.30679772e−019	C4: −4.70224273e−020
  	C5: 2.48728554e−025	C5: −1.4595826ge−022	C5: −3.I9828820e−025
  	C6: −1.07698735e−030	C6: −4.8394607ge−027	C6: 6.66424710e−029
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  		Surface 56
  		K: 0:0000
  		C1: −8.46890011e−009
  		C2: −8.6627038ge−014
  		C3: −2.06359620e−018
  		C4: 7.65545904e−023
  		C5: −3.32533536e−028
  		C6: −2.692I0340e−032
  		C7: 0.00000000e+000
  		C8: 0.00000000e+000
  		C9: 0.00000000e+000

• An aspherical surface can be characterised by the following equation:$p\left(h\right)=\frac{\frac{h^2}{\mathrm{<figure-callout\; label="r"\; filenames="US20080068705A1-20080320-D00001.png,US20080068705A1-20080320-D00002.png"\; state="\{\{state\}\}">r</figure-callout>}}}{1+\sqrt{1-\left(1+K\right)\frac{h^2}{{\mathrm{<figure-callout\; label="r"\; filenames="US20080068705A1-20080320-D00002.png,US20080068705A1-20080320-D00003.png"\; state="\{\{state\}\}">r</figure-callout>}}^2}}}+{\mathrm{<figure-callout\; label="C"\; filenames="US20080068705A1-20080320-D00001.png,US20080068705A1-20080320-D00002.png"\; state="\{\{state\}\}">C</figure-callout>}}_1·{\mathrm{<figure-callout\; label="h"\; filenames="US20080068705A1-20080320-D00003.png,US20080068705A1-20080320-D00004.png"\; state="\{\{state\}\}">h</figure-callout>}}^4+{\mathrm{<figure-callout\; label="C"\; filenames="US20080068705A1-20080320-D00002.png,US20080068705A1-20080320-D00003.png"\; state="\{\{state\}\}">C</figure-callout>}}_2·{\mathrm{<figure-callout\; label="h"\; filenames="US20080068705A1-20080320-D00000.png,US20080068705A1-20080320-D00001.png"\; state="\{\{state\}\}">h</figure-callout>}}^6+\dots$
  wherein
• r is radius of curvature in the apex of the aspherical surface (paraxial curvature),
• h is a distance of a point on the aspherical surface from the optical axis (or height of the aspherical surface from the optical axis),
• p(h) is the sag of the surface in axial direction, i.e. a distance along the direction of the optical axis from a tangent plane to a vertex of the aspheric surface,
• K is a conical coefficient and
• C₁. . . C₆are aspherical coefficients.
• The lens material SILUV indicated in the Tables designates a quartz glass adapted for applications using ultraviolet light. The lens material CAFUV indicated in the Tables designates a calcium fluoride material adapted for applications using ultraviolet light.
• As evident from Table 1, the exemplary embodiment of an immersion type projection optical system contains 10 aspherical surfaces.
• The numerical aperture (NA) at the first object is 0.275, the numerical aperture (NA) at the intermediate image is 0.267, and the numerical aperture (NA) at the second object is 1.1. An imaging magnification β₁from the first object to the intermediate image is −1.032, an imaging magnification β₂from the intermediate image to the second object is −0.242, such that a total magnification β₁·β₂from the first object to the second object is 0.25.
• FIG. 2 schematically illustrates a second exemplary embodiment of the projection optical system according to the present invention. This embodiment has a numerical aperture of about 1.3. The brackets indicate which lens or which lenses are attributed to which group of lenses. The first group of lenses LG1 includes twolenses1,2 and has positive refractive power, the second group of lenses LG2 includes only onelens3 and has negative refractive power, the third group of lenses LG3 includes fourlenses4,5,6,7 and has positive refractive power, the fourth group of lenses LG4 includes twolenses8,9 and has negative refractive power, the fifth group of lenses LG5 includes threelenses10,11,12 and has positive refractive power, the sixth group of lenses LG6 includes only onelens13 and has negative refractive power, the seventh group of lenses LG7 includes fourlenses4,15,16,17 and has positive refractive power, the eighth group of lenses LG8 includes twolenses18,19 and has negative refractive power and the ninth group of lenses LG9 includes sevenlenses20,21,22,23,24,25,25 and has positive refractive power. The ninth group of lenses LG9 may be subdivided into two subgroups, thefirst subgroup SG₉1 comprising the lenses of the ninth group that are disposed in between the first object and the aperture stop (lenses20 to23) and thesecond subgroup SG₉2 comprising the lenses of the ninth group LG9 that are disposed in between the aperture stop and the second object (lenses24 to26).
• In particular, in a direction from the first object to the second object, the first group of lenses LG1 includes a planeparallel plate1 and a substantially plano-convex lens2; the second group of lenses LG2 includes abiconcave lens3, the second group of lenses LG2 being separated from the first group of lenses LG1 by a relatively large air gap; the third group of lenses LG3 includes ameniscus lens4, aconvex lens5 and twomeniscus lenses6,7, the fourth group of lenses LG4 includes twobiconcave lenses8,9; the fifth group of lenses LG5 includes ameniscus lens10, abiconvex lens11, and ameniscus lens12; the sixth group of lenses LG5 includes onebiconcave lens13,; the seventh group of lenses includes a plano-convex lens14, twobiconvex lenses15,16 and ameniscus lens17; the eight group of lenses LG8 includes twobiconcave lenses18,19, and the ninth group of lenses LG5 includes twomeniscus lenses20,21, twobiconvex lenses22,23, twomeniscus lenses24,25 and a plano-convex lens26. This projection optical system is further characterized in that the lenses in the first, third, fifth and seventh groups of lenses each have relatively small diameters.
• In the second exemplary embodiment, the intermediate image is formed in the sixth group of lenses LG6. In this exemplary embodiment of the present invention, an angle of at least one chief ray of the intermediate image is about 28.5°, a longitudinal spherical aberration of the intermediate image is about 0.94 mm, an astigmatism value of the intermediate image is about 11.8 mm, an aberration of the intermediate image is about −2.1%, a RMS of a spot diameter on an optical axis of the projection optical system is about 0.6 mm, a RMS of a spot diameter at a field point farthest away from the optical axis of the projection optical system is about 5.1 mm.
• Detailed information on lens parameters such as thickness of the lens, lens material, radius of the optical surface and the value of one half of the effective diameter of the lens for the second exemplary embodiment are listed in Table 2 (radius, thickness and diameter are given in units of mm; the refractive index is given for a wavelength of 193 nm). In addition, an indication of a position of aspherical surfaces in the projection optical system and their parameters are given in Table 2.

  TABLE 2
  				Lens	Refractive	½
  Lens #	Surface	Radius	Thickness	material	Index	Diameter
  0	0	∞	32.000000000		1.00000000	56.000
  1	1	∞	10.000000000	SILUV	1.56049116	61.280
  	2	∞	1.000000000		1.00000000	63.329
  2	3	100.733544514	62.667723686	SILUV	1.56049116	66.653
  	4	32022.952347600 AS	70134547178		1.00000000	58.743
  3	5	−84.779999894	9.000000000	SILUV	1.56049116	41.640
  	6	124.100395299 AS	27.042753966		1.00000000	42.594
  4	7	−58.387067887	32.224091935	SILUV	1.56049116	42.973
  	8	−89.495828338	1.000000000		1.00000000	57.226
  5	9	637.424312309 AS	31.249717824	SILUV	1.56049116	63.302
  	10	−125.457411370	1.000000000		1.00000000	66.789
  6	11	87.142282901	43.194516336	SILUV	1.56049116	71.140
  	12	277.245672397	1.000000000		1.00000000	65.566
  7	13	65.650106643	37.378396547	SILUV	1.56049116	54.716
  	14	70.641087666	17.179300000		1.00000000	39.429
  8	15	−222.806366019	10.000000000	SILUV	1.56049116	37.867
  	16	148.946283435	10.386040060		1.00000000	32.053
  9	17	−110.856025103	10.000000000	SILUV	1.56049116	31.056
  	18	−441.185155014 AS	60.806885163		1.00000000	33.310
  10	19	−115.871220561	29.971002452	SILUV	1.56049116	54.778
  	20	−67.675896231	1.000000000		1.00000000	59.166
  11	21	122.823548172	27.522471538	SILUV	1.56049116	57.550
  	22	−309.184286918 AS	0.600000000		1.00000000	55.548
  12	23	90.971070084	53.606853082	SILUV	1.56049116	48.656
  	24	53.484081747	14.538911633		1.00000000	26.876
  13	25	−79.033769110	10.000000000	SILUV	1.56049116	26.339
  	26	72.653436508 AS	38.345474204		1.00000000	28.975
  14	27	−2900.861854210	34.681904182	SILUV	1.56049116	46.375
  	28	−89.912398367	1.000000000		1.00000000	52.359
  15	29	185.647971655	43.084526832	SILUV	1.56049116	55.946
  	30	−575.357419176	1.000000000		1.00000000	55.177
  16	31	564.297938029 AS	37.364414663	SILUV	1.56049116	55.662
  	32	−353.745030574	1.000000000		1.00000000	54.497
  17	33	72.220793243	33.554938963	SILUV	1.56049116	50.519
  	34	135.919156304	22.801797274		1.00000000	42.367
  18	35	−559.501580107 AS	10.000000000	SILUV	1.56049116	36.79619
  	36	55.246497668	24.571144054		1.00000000	33.677
  19	37	−57.654090614	12.000001146	SILUV	1.56049116	34.184
  	38	81.435897123 AS	23.389527676		1.00000000	47.984
  20	39	−138.774239558	24.397599913	SILUV	1.56049116	52.581
  	40	−101.724186955	1.000000000		1.00000000	63.478
  21	41	−219.325940773	33.639467701	SILUV	1.56049116	73.220
  	42	−115.213916303	0.999998360		1.00000000	81.562
  22	43	1392.045998250	58.673748551	SILUV	1.56049116	101.704
  	44	−203.620511778	1.000000000		1.00000000	108.306
  23	45	231.429869259 AS	58.933085574	SILUV	1.56049116	113.649
  	46	−272.100613336	33.533113389		1.00000000	113.307
  	47	∞	−32.533113389		1.00000000	93.345
  24	48	134.670223347	34.693999198	SILUV	1.56049116	92.605
  	49	336.731245700 AS	1.000000000		1.00000000	88.261
  25	50	87.745787808	31.038932143	SILUV	1.56049116	71.327
  	51	157.022439156 AS	1.000000000		1.00000000	64.932
  26	52	41.017420667	47.655583536	CAFUV	1.50110592	40.098
  	53	∞	3.000000000	H2O	1.43680000	13.439
  	54	∞	0.000000000		1.00000000	7.000

  Aspherical Surfaces

  	Surface 4	Surface 6	Surface 9
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 6.91762547e−008	C1: −4.27433833e−007	C1: −2.70725252e−007
  	C2: −1.00821998e−012	C2: 9.24619398e−011	C2: 7.89014814e−012
  	C3: 8.22439961e−016	C3: −6.99952985e−014	C3: −1.45142628e−015
  	C4: −1.26146197e−019	C4: 3.04240551e−017	C4: −2.26439260e−019
  	C5: −5.92492144e−024	C5: −8.56628971e−021	C5: 7.10185165e−023
  	C6: 1.68627707e−027	C6: 6.04286715e−025	C6: −1.37233277e−026
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 18	Surface 22	Surface 26
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 1.13326160e−006	C1: 1.86984594e−007	C1: −1.22627425e−007
  	C2: 4.69642710e−010	C2: −7.47098219e−012	C2: −1.73570760e−011
  	C3: 1.93983951e−013	C3: 7.81949424e−016	C3: 1.56978236e−014
  	C4: 3.77234480e−017	C4: −1.23355413e−019	C4: −1.27740748e−016
  	C5: 1.20657590e−020	C5: 1.39727008e−023	C5: 9.41034563e−020
  	C6: 1.10191897e−023	C6: 1.72439306e−028	C6: −2.50468463e−023
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 31	Surface 35	Surface 38
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 1.43703293e−007	C1: −1.42590228e−006	C1: −1.21758383e−006
  	C2: 1.13355487e−011	C2: −1.97387056e−010	C2: 2.25752422e−011
  	C3: −6.75460046e−016	C3: 4.78455973e−014	C3: 1.11782472e−014
  	C4: −7.03138870e−020	C4: 1.62503154e−017	C4: −5.16089164e−018
  	C5: −1.74001972e−023	C5: 2.50774387e−020	C5: 5.93762703e−022
  	C6: 1.93426816e−027	C6: −1.12531033e−027	C6: −5.20615255e−026
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 45	Surface 49	Surface 51
  	K: 0:0000	K: 0:0000	K: 0:0000
  	C1: −3.74737153e−008	C1: −5.35416508e−009	C1: −6.44904425e−008
  	C2: −7.62435274e−013	C2: 5.84206555e−013	C2: −7.20142509e−012
  	C3: −6.93980539e−018	C3: −1.02043747e−016	C3: 6.07409160e−016
  	C4: −4.33525846e−022	C4: −2.70496897e−020	C4: 9.20273534e−019
  	C5: 8.52520503e−026	C5: 1.68712776e−024	C5: −1.85277777e−022
  	C6: −2.83405796e−030	C6: −3.20799816e−030	C6: 1.48428230e−026
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000

• A numerical aperture (NA) at the first object is 0.1625, the numerical aperture (NA) at the intermediate image is 0.285, and the numerical aperture (NA) at the second object is 1.3. An imaging magnification β₁from the first object to the intermediate image is −0.57, an imaging magnification β₂from the intermediate image to the second object is −0.219, such that a total magnification β₁·β₂from the first object to the second object is 0.125.
• FIG. 3 schematically illustrates a third exemplary embodiment of the projection optical system according to the present invention. The projection optical system shown inFIG. 3 has a similar structure as that shown inFIG. 2.
• Optical data of the projection optical system ofFIG. 3 are given in Table 3 below.

  TABLE 3
  				Lens	Refractive	½
  Lens #	Surface	Radius	Thickness	material	Index	Diameter
  	0	∞	32.000000000		1.00000000	56.000
  1	1	∞	9.994926454	SILUV	1.56049116	61.487
  	2	∞	0.983970249		1.00000000	62.576
  2	3	104.335302767	50.000128595	SILUV	1.56049116	66.908
  	4	−3106.949722908 AS	76.175374387		1.00000000	62.019
  3	5	−108.162859030	8.996945596	SILUV	1.56049116	43.312
  	6	145.872762253 AS	26.612977949		1.00000000	43.188
  4	7	−63.692112581	41.121449191	SILUV	1.56049116	43.598
  	8	−148.694829892	0.999314823		1.00000000	60.533
  5	9	−1881.227188585 AS	28.600200276	SILUV	1.56049116	62.871
  	10	−100.640093152	0.998292928		1.00000000	66.648
  6	11	93.310678254	42.633131227	SILUV	1.56049116	74.614
  	12	330.638332368	0.996803092		1.00000000	70.108
  7	13	65.552800218	30.873146207	SILUV	1.56049116	57.917
  	14	105.866610652	13.963247135		1.00000000	50.783
  8	15	367.134055921	9.793129426	SILUV	1.56049116	46.925
  	16	107.242761257	16.571541756		1.00000000	38.861
  9	17	−125.867739347	8.997719804	SILUV	1.56049116	36.093
  	18	176.780711857 AS	61.484433369		1.00000000	33.520
  10	19	−102.551788067	37.043696332	SILUV	1.56049116	52.676
  	20	−67.900979720	0.997513775		1.00000000	60.304
  11	21	122.872438500	27.058733851	SILUV	1.56049116	58.037
  	22	−318.215075265 AS	0.998963808		1.00000000	56.115
  12	23	88.799497079	51.427075983	SILUV	1.56049116	48.524
  	24	53.527140946	17.646941838		1.00000000	26.980
  13	25	−80.288767257	8.996807285	SILUV	1.56049116	26.963
  	26	73.896625355 AS	37.739389033		1.00000000	29.546
  14	27	−2111.719991198	33.548344902	SILUV	1.56049116	46.806
  	28	−90.879698694	2.062998346		1.00000000	52.624
  15	29	207.677300574	36.682295744	SILUV	1.56049116	56.675
  	30	−950.438335639	4.239364713		1.00000000	56.460
  16	31	412.576525922 AS	35.094990292	SILUV	1.56049116	55.932
  	32	−288.898999836	2.054606078		1.00000000	54.344
  17	33	72.294412199	33.413205228	SILUV	1.56049116	50.689
  	34	126.924823744	23.263607131		1.00000000	42.670
  18	35	−610.144871693 AS	9.004431664	SILUV	1.56049116	37.723
  	36	56.861698660	29.493986876		1.00000000	35.203
  19	37	−56.969571039	8.997309770	SILUV	1.56049116	36.575
  	38	99.784593360 AS	27.465223390		1.00000000	51.821
  20	39	−117.765690318	48.249958252	SILUV	1.56049116	57.605
  	40	−90.269492866	0.773643744		1.00000000	77.087
  21	41	−875.910732301	42.249248610	SILUV	1.56049116	104.385
  	42	−172.604598891	0.974038994		1.00000000	108.929
  22	43	803.097825670	41.021577890	SILUV	1.56049116	123.629
  	44	−376.629540438	30.903940303		1.00000000	124.899
  23	45	287.536526769	55.352280753	SILUV	1.56049116	125.000
  	46	−397.989329067 AS	40.345224742		1.00000000	123.309
  	47	∞	−39.345382978		1.00000000	100.204
  24	48	237.819815616	30.589038976	SILUV	1.56049116	106.035
  	49	1105.595513606 AS	0.999299763		1.00000000	100.156
  25	50	86.934183491	45.380148828	SILUV	1.56049116	77.957
  	51	170.242472558 AS	0.997963011		1.00000000	69.126
  27	52	45.257566696	49.528196203	SILUV	1.56049116	43.217
  	53	∞	1.974724574	H2O	1.43680000	12.491
  	54	∞	0.000000000		1.00000000	7.003

  Aspherical Surfaces

  	Surface 4	Surface 6	Surface 9
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 5.79209182e−008	C1: −3.44646611e−007	C1: −3.73442666e−007
  	C2: −6.37791028e−013	C2: 8.59385562e−011	C2: 1.43445552e−011
  	C3: 3.44372255e−016	C3: −6.71616375e−014	C3: −3.17190498e−015
  	C4: −8.85599631e−020	C4: 3.03855181e−017	C4: −2.26702756e−020
  	C5: 1.08570138e−023	C5: −8.55350273e−021	C5: 4.11927181e−023
  	C6: −6.96227825e−028	C6: 6.00036028e−025	C6: −1.38156455e−026
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 18	Surface 22	Surface 26
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 1.18777440e−006	C1: 1.71075626e−007	C1: −1.10154860e−007
  	C2: 4.35580377e−010	C2: −7.64005086e−012	C2: 9.17734618e−012
  	C3: 1.88404875e−013	C3: 7.08908253e−016	C3: 1.76187633e−014
  	C4: 3.83721549e−017	C4: −1.37311020e−019	C4: −1.28147141e−016
  	C5: 1.20493249e−020	C5: 2.02367340e−023	C5: 9.40704126e−020
  	C6: 1.10378361e−023	C6: −1.15655593e−027	C6: −2.50493002e−023
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 31	Surface 35	Surface 38
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 1.55330372e−007	C1: −1.37333522e−006	C1: −9.81476763e−007
  	C2: 1.27330720e−011	C2: −2.24444706e−010	C2: 2.91363587e−011
  	C3: −6.68035467e−016	C3: 4.91877012e−014	C3: 1.01744933e−014
  	C4: −1.73835192e−019	C4: 1.64123170e−017	C4: −4.68579579e−018
  	C5: 4.68772334e−025	C5: 2.50741808e−020	C5: 6.42028822e−022
  	C6: 1.16194092e−027	C6: −1.12492432e−023	C6: −4.96400088e−026
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000
  	Surface 46	Surface 49	Surface 51
  	K: 0.0000	K: 0.0000	K: 0.0000
  	C1: 6.28883670e−009	C1: 5.08335169e−008	C1: −1.57589741e−007
  	C2: −5.65369265e−014	C2: −8.36178137e−013	C2: 2.00244046e−011
  	C3: 3.85725582e−017	C3: 1.52685373e−017	C3: −2.81721098e−015
  	C4: 2.41064866e−022	C4: −7.56691426e−021	C4: 1.09133188e−018
  	C5: −1.06036768e−025	C5: −1.10112578e−024	C5: −1.77818931e−022
  	C6: 3.55992142e−030	C6: 6.92008272e−029	C6: 1.21644794e−026
  	C7: 0.00000000e+000	C7: 0.00000000e+000	C7: 0.00000000e+000
  	C8: 0.00000000e+000	C8: 0.00000000e+000	C8: 0.00000000e+000
  	C9: 0.00000000e+000	C9: 0.00000000e+000	C9: 0.00000000e+000

• The numerical aperture of this projection optical system at the first object is 0.16875, the numerical aperture (NA) at the intermediate image is 0.343875, and the numerical aperture (NA) at the second object is 1.35. An imaging magnification β₁from the first object to the intermediate image is −0.49, and imaging magnification β₂from the intermediate image to the second object is −0.25, such that a total magnification β₁·β₂from the first object to the second object is 0.125.
• FIG. 4 schematically illustrates a fourth exemplary embodiment of the projection optical system according to the present invention. Optical data of this projection optical system are given in Table 4 below.

  TABLE 4
  				Lens	Refractive	½
  Lens #	Surface	Radius	Thickness	Material	Index	Diameter
  	0	∞	32.0177			28.04
  1	1	219.726108	16.9641	SILUV	1.56049116	40.832
  	2	−516.629235	25.5543			41.534
  2	3	−67.647606	9.9997	SILUV	1.56049116	42.327
  	4	−260.983067	29.1106			48.384
  3	5	−55.926810	22.2539	SILUV	1.56049116	49.734
  	6	−92.468456	0.9991			67.142
  4	7	−767.680932	37.5784	SILUV	1.56049116	82.094
  	8	−131.658929	0.9988			86.014
  5	9	286.557516	28.7046	SILUV	1.56049116	94.284
  	10	−524.762011	0.9983			94.07
  6	11	179.876647	39.2566	SILUV	1.56049116	94.422
  	12	−1720.456551	0.9987			92.365
  7	13	81.367631	46.6132	SILUV	1.56049116	73.745
  	14	214.457507	10.7815			65.879
  8	15	988.155084	9.9989	SILUV	1.56049116	61.001
  	16	44.128228	58.8087			39.687
  9	17	−54.499122	21.1959	SILUV	1.56049116	37.928
  	18	779.716415	7.4192			58.019
  10	19	−2380.510542	41.7009	SILUV	1.56049116	63.429
  	20	−116.856539	7.1183			73.297
  11	21	374.105752	27.3570	SILUV	1.56049116	95.272
  	22	−939.498386	0.9989			97.02
  12	23	1698.857072	35.5054	SILUV	1.56049116	98.937
  	24	−232.675275	0.9998			100.079
  13	25	−637.737295	29.4950	SILUV	1.56049116	98.687
  	26	−154.955797	1.6682			98.696
  14	27	143.644278	43.3863	SILUV	1.56049116	82.611
  	28	−4991.975215	33.6199			75.464
  15	29	−135.548808	10.0009	SILUV	1.56049116	58.898
  	30	−135.939439	15.7718			57.063
  16	31	−155.550081	9.9994	SILUV	1.56049116	39.631
  	32	59.823981	34.9249			32.76
  	33	40.944395	44.6217			30.661
  17	34	−78.015171	17.8868	SILUV	1.56049116	43.479
  	35	−103.229933	0.9990			53.465
  18	36	748.407674	34.9736	SILUV	1.56049116	64.921
  	37	−114.726548	0.9986			68.235
  19	38	155.876376	36.7930	SILUV	1.56049116	73.693
  	39	−322.561694	0.9993			72.589
  20	40	82.043143	24.2651	SILUV	1.56049116	60.783
  	41	123.218503	14.1941			55.017
  21	42	501.513595	9.9987	SILUV	1.56049116	52.632
  	43	108.394643	23.2241			45.918
  22	44	−108.072241	9.9973	SILUV	1.56049116	44.309
  	45	75.853522	43.3152			42.433
  23	46	−49.580063	10.4777	SILUV	1.56049116	43.795
  	47	−135.624067	16.3741			61.989
  24	48	−127.749898	50.3510	SILUV	1.56049116	69.632
  	49	−93.339527	1.9988			84.556
  25	50	−230.459673	31.7216	SILUV	1.56049116	100.287
  	51	−145.921184	0.9986			105.092
  26	52	438.084235	34.1859	SILUV	1.56049116	119.607
  	53	−958.216153	0.9985			119.996
  27	54	148.780263	56.2561	SILUV	1.56049116	119.317
  	55	1006.690104	17.5434			115.143
  	56	∞	−16.5440			113.484
  28	57	121.754105	46.1167	SILUV	1.56049116	101.339
  	58	364.980240	1.0000			94.888
  29	59	92.745174	44.9633	SILUV	1.56049116	76.661
  	60	162.095006	1.0000			61.07
  30	61	79.550539	21.2760	SILUV	1.56049116	50.022
  	62	52.213824	1.0000			33.7
  31	63	38.877117	23.2198	SILUV	1.56049116	28.052
  	64	∞	1.9981	H2O	1.43680000	11.206
  	65	∞	0.0000		0.00	7.01

  SRF

  	1	4	10	15	26
  K	0	0	0	0	0
  C1	4.949385E−07	−3.024420E−08	6.269111E−08	1.261175E−07	8.504929E−08
  C2	−4.367642E−11	−5.916383E−11	1.324406E−12	8.971294E−12	−7.030475E−14
  C3	4.465807E−14	5.552973E−15	−4.683596E−17	−3.260724E−15	−2.810798E−17
  C4	−8.750418E−18	6.922767E−19	7.650166E−21	−8.196181E−20	9.597806E−21
  C5	2.122243E−21	−2.973575E−22	−5.793979E−25	1.052835E−22	−4.197615E−25
  C6	3.823785E−25	1.235469E−25	1.724683E−29	−1.037823E−26	1.026003E−29

  SRF

  	33	36	43	47	55
  K	−4.00584	0	0	0	0
  C1	0.000000E+00	−1.247396E−08	−3.505754E−08	3.209461E−07	4.027043E−08
  C2	0.000000E+00	1.139915E−12	−8.285113E−13	−1.311727E−11	−9.830902E−13
  C3	0.000000E+00	−1.179022E−15	−3.632752E−15	−6.000578E−15	3.287892E−17
  C4	0.000000E+00	1.461992E−19	−7.761827E−18	3.031884E−19	8.492315E−21
  C5	0.000000E+00	−2.604272E−24	2.347772E−21	1.642062E−22	−6.295963E−25
  C6	0.000000E+00	−6.658674E−28	−6.931183E−25	−2.108137E−26	1.638768E−29

  SRF

  		58	60	62
  	K	0	0	0
  	C1	6.832442E−08	−3.313614E−07	−1.637842E−06
  	C2	5.874159E−12	1.413471E−10	−1.031046E−09
  	C3	−7.216686E−16	−2.638118E−14	8.964353E−13
  	C4	−6.194479E−21	3.624962E−18	1.249258E−16
  	C5	1.981698E−24	−2.616814E−22	−4.210636E−19
  	C6	−3.629080E−29	1.122394E−27	1.742133E−22

• This projection optical system is designed to be operated with light of a wavelength of 193 nm and has a numerical aperture (NA) at the second object of 1.3. A distance between the first object and second object is 1300 mm. A diameter of the image field is 14.02 mm, and a RMS deviation of a wavefront at the second object is about 8.5 mλ.
• A caustic of the intermediate image generated in the embodiments illustrated with reference toFIGS. 1, 2 and3 above extends over plural lenses of the group LG7. Those lenses should be manufactured with a particularly high accuracy, in particular with respect to surface roughness and a homogeneity of the lens material.
• In the embodiment shown inFIG. 4, the intermediate image is completely formed in a space betweenlens16 and17 as illustrated in the enlarged partial view of the projection optical system shown inFIG. 5. Thus, in this embodiment, the intermediate image is sufficiently corrected to be completely formed outside of lenses of the projection optical system, even though the intermediate image has a significant field curvature as indicated by a broken line inFIG. 5.
• Summarized, a refractive projection optical system for imaging a first object into a region of a second object comprises a plurality of lenses disposed along an imaging beam path of the projection optical system; wherein the projection optical system is configured to have a numerical aperture on a side of the second object of greater than 1 wherein the projection optical system is configured to generate an intermediate image of the first object and to image the intermediate image into the region of the second object, wherein the intermediate image is formed in between the first and second objects.
• While the invention has been described with respect to certain exemplary embodiments thereof, it is evident that many alternatives, modifications and variations will be apparent to those skilled in the art. Accordingly, the exemplary embodiments of the invention set forth herein are intended to be illustrative and not limiting in any way. Various changes may be made without departing from the spirit and scope of the present invention as defined in the following claims.

Claims (20)

1-30. (canceled)

31. A projection optical system used for an exposure apparatus to projecting a reduced size of an image of an object onto an image plane, said projection optical system comprising plural refractive elements that dispense with a reflective element having a substantial optical power, wherein said projection optical system forms an intermediate image.

32. The projection optical system according toclaim 31, wherein only the plural refractive elements have optical powers in said projection optical system.

33. The projection optical system according toclaim 31, wherein said projection optical system has a numerical aperture of 1.1 or greater.

34. The projection optical system according toclaim 31, wherein a maximum effective diameter of said projection optical system divided by an overall length of said projection optical system is equal to or smaller than 0.20.

35. The projection optical system according toclaim 31, wherein a maximum effective diameter of said projection optical system divided by an overall length of said projection optical system is equal to or smaller than 0.25.

36. The projection optical system according toclaim 31, wherein −1.50≦β₁≦−0.50, where β₁is a magnification of a first imaging system for forming an intermediate image in said projection optical system.

37. The projection optical system according toclaim 31, wherein −1.50≦β₁≦−0.40, where β₁is a magnification of a first imaging system for forming an intermediate image in said projection optical system.

38. The projection optical system according toclaim 31, wherein said projection optical system is substantially telecentric both at object side and image side.

39. The projection optical system according toclaim 31, wherein a distance between the image plane and an optical surface of said projection optical system closest to the image plane is 20 mm or smaller.

40. The projection optical system according toclaim 31, wherein said projection optical system includes, in order from an object side to an image side, first, second, third and fourth units having optically positive powers, a first pupil being formed between the first and second units, the intermediate image being formed between the second and third units, and a second pupil being formed between the third and fourth units.

41. The projection optical system according toclaim 31, wherein said projection optical system includes, in order from an object side to an image side, first, second, third and fourth units, at least three units having optically positive powers, a first pupil being formed between the first and second units, the intermediate image being formed between the second and third units, and a second pupil being formed between the third and fourth units.

42. The projection optical system according toclaim 31, wherein said projection optical system includes, in order from an object side to an image side, first, second, third and fourth units, the first, second and fourth units having optically positive powers, a first pupil being formed between the first and second units, the intermediate image being formed between the second and third units, and a second pupil being formed between the third and fourth units.

43. The projection optical system according toclaim 42, wherein said projection optical system consists of the first, second, third and fourth units.

44. The projection optical system according toclaim 42, wherein at least three of the first, second, third and fourth units include a negative lens.

45. The projection optical system according toclaim 42, wherein each of the first, second, and third units includes a negative lens.

46. The projection optical system according toclaim 42, wherein f1≧f4, and f3≧f4 are met, where f1 denotes a focal length of the first unit, f2 denotes a focal length of the second unit, f3 denotes a focal length of the third unit, and f4 denotes a focal length of the fourth unit.

47. The projection optical system according toclaim 42, wherein 0.078≦f1≦0.15, 0.055≦f2/L≦1.917, 0.084≦f3/L≦0.276, 0.056≦f4/L≦0.066 are met, where f1 denotes an absolute value of a focal length of the first unit, f2 denotes an absolute value of a focal length of the second unit, f3 denotes an absolute value of a focal length of the third unit, and f4 denotes an absolute value of a focal length of the fourth unit.

48. An exposure apparatus comprising:

an illumination optical system for illuminating an original from light from a light source; and

a projection optical system according toclaim 31 for projecting a pattern of the original onto an object to be exposed.

49. A device manufacturing method comprising the steps of:

exposing an object using an exposure apparatus according toclaim 48; and

developing the object that has been exposed.

Images