# US 2008/0186567 A1 · Catadioptric projection objective > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2008/0186567 A1 - Document ID: US20080186567A1 - Status: Published application - Kind: A1 - Application number: 12/099,882 - Filed: 2008-04-09 - Published: 2008-08-07 - Earliest claimed: 2004-01-14 - Assignees: Carl Zeiss SMT GmbH - Inventors: David Shafer; Wilhelm Ulrich; Aurelian Dodoc; Rudolf Von Buenau; Hans-Juergen Mann; Alexander Epple - Web page: https://patentgrep.com/patent/US20080186567A1 ## CPC - G02B 17/0804: {using two curved mirrors (G02B17/0864, G02B17/0896 takes precedence)} - G02B 17/08: Catadioptric systems {(used in non-imaging applications G02B19/00)} - G02B 17/0812: {off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry} - G02B 17/0844: {off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry} - G02B 17/0856: {comprising a refractive element with a reflective surface, the reflection taking place inside the element, e.g. Mangin mirrors} - G02B 17/0892: {specially adapted for the UV} - G03F 7/70225: {Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements} - G02B: OPTICAL ELEMENTS, SYSTEMS OR APPARATUS - G03F: PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR; (phototypographic composing devices B41B; photosensitive materials or processes for photographic purposes G03C; electrophotography, sensitive layers or processes therefor G03G) ## Abstract A catadioptric projection objective for imaging a pattern provided in an object plane of the projection objective onto an image plane of the projection objective comprises: a first objective part for imaging the pattern provided in the object plane into a first intermediate image; a second objective part for imaging the first intermediate imaging into a second intermediate image; a third objective part for imaging the second intermediate imaging directly onto the image plane; wherein a first concave mirror having a first continuous mirror surface and at least one second concave mirror having a second continuous mirror surface are arranged upstream of the second intermediate image; pupil surfaces are formed between the object plane and the first intermediate image, between the first and the second intermediate image and between the second intermediate image and the image plane; and all concave mirrors are arranged optically remote from a pupil surface. The system has potential for very high numerical apertures at moderate lens material mass consumption. ## Claims ### Claim 1 A catadioptric projection objective for imaging a pattern provided in an object plane of the projection objective onto an image plane of the projection objective comprising: a first objective part for imaging the pattern provided in the object plane into a first intermediate image; a second objective part for imaging the first intermediate image into a second intermediate image; a third objective part for imaging the second intermediate image onto the image plane; wherein a first concave mirror having a first continuous mirror surface and at least one second concave mirror having a second continuous mirror surface are arranged upstream of the second intermediate image; pupil surfaces are formed between the object plane and the first intermediate image, between the first and the second intermediate image and between the second intermediate image and the image plane; and all concave mirrors are arranged optically remote from a pupil surface. ### Claim 2 (canceled) ### Claim 3 (canceled) ### Claim 4 (depends on 1) Projection objective according to claim 1, wherein the first objective part is a dioptric imaging system; the second objective part includes the first and the second concave mirrors, the concave mirror surfaces of the concave mirrors facing each other and defining an intermirror space; wherein at least the first intermediate image is located geometrically within the intermirror space between the first concave mirror and the second concave mirror. ### Claim 5 (depends on 4) Projection objective according to claim 4, wherein both the first intermediate image and the second intermediate image are located geometrically within the intermirror space between the first concave mirror and the second concave mirror. ### Claim 6 (depends on 1) Projection objective according to claim 1, wherein the first objective part and the second objective part and the third objective part share a common straight optical axis. ### Claim 7 (canceled) ### Claim 8 (depends on 1) Projection objective according to claim 1, wherein at least one mirror surface of a concave mirror is aspheric. ### Claim 9 (depends on 1) Projection objective according to claim 1, wherein the first objective part is a catadioptric objective part including a single first concave mirror and the second objective part is a catadioptric objective part including a single second concave mirror. ### Claim 10 (canceled) ### Claim 11 (depends on 1) Projection objective according to claim 1, wherein it is designed such that radiation reflected from the first concave mirror crosses the optical axis prior to impinging on the second concave mirror. ### Claim 12 (canceled) ### Claim 13 (canceled) ### Claim 14 A catadioptric projection objective for imaging a pattern provided in an object plane of the projection objective onto an image plane of the projection objective comprising: a first objective part for imaging the pattern provided in the object plane into a first intermediate image; a second objective part for imaging the first intermediate image into a second intermediate image; a third objective part for imaging the second intermediate image onto the image plane; wherein the second objective part includes a first concave mirror having a first mirror surface and a second concave mirror having a second mirror surface, the concave mirror surfaces of the concave mirrors facing each other and defining an intermirror space; wherein at least the first intermediate image is located geometrically within the intermirror space between the first concave mirror and the second concave mirror. ### Claim 15 (canceled) ### Claim 16 (canceled) ### Claim 17 (canceled) ### Claim 18 (canceled) ### Claim 19 (canceled) ### Claim 20 (canceled) ### Claim 21 (depends on 14) Projection objective according to claim 14, wherein a chief ray of the most off axial field point intersects the optical axis in the optical paths between the two concave mirrors in the geometrical vicinity of the location of the first intermediate image. ### Claim 22 (depends on 1) Projection objective according to claim 1, wherein the first objective part is designed as an enlarging imaging system. ### Claim 23 (canceled) ### Claim 24 (canceled) ### Claim 25 (depends on 1) Projection objective according to claim 1, wherein the second objective part is designed as an system having a magnification β2 in the range 0.4<|β2|<1.5. ### Claim 26 (canceled) ### Claim 27 (depends on 1) Projection objective according to claim 1, wherein the third objective part has a reducing magnification β3 wherein |β3|<1. ### Claim 28 (depends on 1) Projection objective according to claim 1, wherein the second intermediate image has a size larger than the image size. ### Claim 29 (depends on 14) Projection objective according to claim 14, wherein the first objective part and the second objective part and the third objective part share a common straight optical axis. ### Claim 30 (depends on 14) Projection objective according to claim 14, wherein curvature surfaces of the first concave mirror and the second concave mirror have a common axis of rotational symmetry. ### Claim 31 (canceled) ### Claim 32 (canceled) ### Claim 33 (depends on 1) Projection objective according to claim 1, wherein at least one of the first concave mirror and the second concave mirror is designed as a front face mirror. ### Claim 34 (canceled) ### Claim 35 (canceled) ### Claim 36 (depends on 1) Projection objective according to claim 1, wherein the projection objective includes no planar folding mirror. ### Claim 37 (canceled) ### Claim 38 (depends on 1) Projection objective according to claim 1, wherein the diameter of the concave mirrors is less than 150% of the size of the first and the second intermediate image. ### Claim 39 (canceled) ### Claim 40 (depends on 1) Projection objective according to claim 1, wherein a maximum free diameter is 2.4 fold of a maximum beam height within said third objective part. ### Claim 41 (canceled) ### Claim 42 (canceled) ### Claim 43 (canceled) ### Claim 44 (canceled) ### Claim 45 (canceled) ### Claim 46 (canceled) ### Claim 47 (canceled) ### Claim 48 (canceled) ### Claim 49 (canceled) ### Claim 50 (canceled) ### Claim 51 (canceled) ### Claim 52 (canceled) ### Claim 53 (canceled) ### Claim 54 (canceled) ### Claim 55 (canceled) ### Claim 56 (depends on 1) Projection objective according to claim 1, wherein the first concave mirror has a curvature c1 (in [mm−1]) and the second concave mirror has a curvature c2 (in [mm−1]) and D (in [mm]) is a maximum diameter of a lens element of the third objective part and wherein the following condition is fulfilled: 10.9. ### Claim 75 (depends on 1) Projection objective according to claim 1, wherein the projection objective is designed as an immersion objective adapted with reference to aberrations such that an image side working distance between a last optical element and the image plane is filled up with an immersion medium with a refractive index substantially greater than 1. ### Claim 76 (depends on 1) Projection objective according to claim 1, wherein it has an image side numerical aperture NA>1.1 when used in connection with an immersion medium. ### Claim 77 (depends on 1) Projection objective according to claim 1, that is telecentric on both its object end and image end. ### Claim 78 (depends on 1) Projection objective according to claim 1, that has an essentially homocentric entrance pupil. ### Claim 79 (canceled) ### Claim 80 (canceled) ### Claim 81 (depends on 1) Projection objective according to claim 1, wherein an aperture stop is provided in the third objective part. ### Claim 82 (depends on 1) Projection objective according to claim 1, that is configured for use with ultraviolet light falling within a wavelength range extending from about 120 nm to about 260 nm. ### Claim at position 83 -107. (canceled) ### Claim 108 (depends on 1) Projection objective according to claim 1, wherein a first lens element of the first objective part immediately following the object plane has an aspheric surface facing the object plane, wherein the aspheric surface is essentially flat having a local radius R>300 mm at each point of the aspheric surface. ### Claim 109 (canceled) ### Claim 110 (canceled) ### Claim 111 (canceled) ### Claim 112 (depends on 1) Projection objective according to claim 1, wherein a plurality of optical elements having at least one aspherical surface is provided, and wherein all aspheric surfaces have surface shapes which are free of inflection points. ### Claim 113 (depends on 1) Projection objective according to claim 1, wherein the projection objective has at least one optical element having an aspherical surface with a surface shape free of extremal points in an optically used area of the aspheric surface outside the optical axis, wherein an extremal point is defined by:  p  h = 0   and    2  p  h 2 ≠ 0. where parameter p represents a distance, measured parallel to the optical axis of an optical element, of a point at height h from the vertex of the surface. ### Claim 114 (canceled) ### Claim 115 (depends on 1) Projection objective according to claim 1, wherein a plurality of optical elements having at least one aspherical surface is provided, and wherein all aspheric surfaces have surface shapes which are free of extremal points outside the optical axis. ### Claim 116 (depends on 113) Projection objective according to claim 113, wherein the aspheric surface is free of extremal point in an area including the optically utilized area defined by the optically used radius hopt and going beyond that area up to a maximum height hmax>hopt, where hmax=hopt+OR and where OR is at least 5 mm. ### Claim 117 (depends on 1) Projection objective according to claim 1, wherein aspheric surfaces having at least one extremal point are essentially flat across the entire optically utilized area. ### Claim at position 94 -128. (canceled) ### Claim 129 (depends on 1) Projection objective according to claim 1, wherein the first objective part includes a concave mirror and at least one additional mirror having a curved mirror surface, wherein the curved mirror surfaces of the concave mirror and the additional mirror are facing each other. ### Claim 130 (depends on 129) Projection objective according to claim 129, wherein the additional mirror has a convex mirror surface. ### Claim 131 (canceled) ### Claim 132 (depends on 129) Projection objective according to claim 129, wherein the first objective parts is catadioptric and includes at least one lens in addition to the concave mirror and the additional mirror. ### Claim 133 (depends on 129) Projection objective according to claim 129, wherein the second objective part includes a first concave mirror having a first mirror surface and a second concave mirror having a second mirror surface, the concave mirror faces of the concave mirrors facing each other and defining an intermirror space. ### Claim 134 (canceled) ### Claim 135 (canceled) ### Claim 136 (depends on 129) Projection objective according to claim 129, wherein the first objective part and the second objective part and the third objective part share a common straight optical axis. ### Claim 137 (depends on 129) Projection objective according to claim 129, wherein the first objective part is designed as an enlarging imaging system. ### Claim at position 104 -162. (canceled)