Catadioptric projection objective Number:7,385,756 from the United States Patent and Trademark Office (PTO) owispatent 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.<H Catadioptric, projection, Catadioptric, pr, 7385756.html, Patent, pto, 7385756

Title: Catadioptric projection objective

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.

Patent Number: 7,385,756 Issued on 06/10/2008 to Shafer, et al.

Inventors: Shafer; David (Fairfield, CT), Ulrich; Wilhelm (Aalen, DE), Dodoc; Aurelian (Heidenheim, DE), Von Buenau; Rudolf (Jena, DE), Mann; Hans-Juergen (Oberkochen, DE), Epple; Alexander (Aalen, DE)
Assignee: Carl Zeiss SMT AG (Oberkochen, DE)

Appl. No.: 11/035,103

Filed: January 14, 2005

Related U.S. Patent Documents


Application Number	Filing Date	Patent Number	Issue Date
60617674	Oct., 2004
60612823	Sep., 2004
60587504	Jul., 2004
60536248	Jan., 2004

Current U.S. Class: 359/365 ; 359/730

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Primary Examiner: Allen; Stephone B.
Assistant Examiner: Fineman; Lee
Attorney, Agent or Firm: Fish & Richardson P.C.

Parent Case Text

The present application claims priority benefit to U.S. Provisional 60/536,248 filed Jan. 14, 2004; U.S. Provisional 60/587,504 filed Jul. 14, 2004; U.S. Provisional 60/617,674 filed Oct. 13, 2004; and U.S. Provisional 60/612,823 filed Sep. 24, 2004. The disclosures of all of these Provisional applications are incorporated into this application by reference.

Claims

What is claimed is:

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, wherein the projection objective includes exactly two concave mirrors and exactly two intermediate images.

2. Projection objective according to claim 1, wherein all concave mirrors are arranged optically remote from a pupil surface at a position where a chief ray height exceeds a marginal ray height of the imaging process.

3. 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.

4. Projection objective according to claim 3, 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.

5. 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.

6. Projection objective according to claim 1, wherein curvature surfaces of the first concave mirror and the second concave mirror have a common axis of rotational symmetry defining a catadioptric or catoptric part of the optical axis which is inclined at an angle to an object side part and an image side part of the optical axis.

7. Projection objective according to claim 1, wherein at least one mirror surface of a concave mirror is aspheric.

8. Projection objective according to claim 1, wherein the first objective part is a catadioptric objective part including a first of the concave mirrors and the second objective part is a catadioptric objective part including a second of the two concave mirrors.

9. Projection objective according to claim 1, wherein a mirror group defined by the first and the second concave mirror facing each other has a mirror group entry and a mirror group exit, the mirror group entry being positioned geometrically next to an edge of the second concave mirror facing the optical axis and the mirror group exit being positioned geometrically next to an edge of the first concave mirror facing the optical axis and wherein pupil surfaces of the projection objective are arranged in a vicinity of the mirror group entry and in a vicinity of the mirror group exit.

10. Projection objective according to claim 1, wherein the projection objective is designed such that radiation reflected from the first concave mirror crosses the optical axis prior to impinging on the second concave mirror.

11. Projection objective according to claim 1, wherein the first objective part is purely refractive, the second objective part is catoptric or catadioptric, and the third objective part is purely refractive.

12. Projection objective according to claim 1, wherein the projection objective includes no convex mirror.

13. Projection objective according to claim 1, wherein the first objective part is designed as an enlarging imaging system.

14. Projection objective according to claim 1, wherein the first objective part is designed as an enlarging imaging system having a magnification .beta..sub.1 in the range 1<|.beta..sub.1|<2.5.

15. Projection objective according to claim 1, wherein the second objective part is designed as near unit magnification optical system.

16. Projection objective according to claim 15, wherein the second objective part is designed as an system having a magnification .beta..sub.2 in the range 0.4<|.beta..sub.2|<1.5.

17. Projection objective according to claim 15, wherein the second objective part is designed as an system having a magnification .beta..sub.2 in the range 0.9<|.beta..sub.2|<1.1.

18. Projection objective according to claim 1, wherein the third objective part has a reducing magnification .beta..sub.3 wherein |.beta..sub.3|<1.

19. Projection objective according to claim 1, wherein the second intermediate image has a size larger than the image size.

20. Projection objective according to claim 1, wherein at least one of the first concave mirror and the second concave mirror is designed as a Mangin Mirror.

21. 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.

22. Projection objective according to claim 1, wherein at least one of the concave mirrors has an aspheric reflecting surface having an absolute value of curvature which decreases from an optical axis of the projection objective to the edge of the mirror in a radial direction.

23. Projection objective according to claim 1, wherein the projection objective includes no planar folding mirror.

24. Projection objective according to claim 1, wherein a maximum light beam height at the concave mirrors is less than 1.5 fold of the maximum light beam height within the third objective part.

25. 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.

26. Projection objective according to claim 1, wherein all light beams within the projection objective are located within a space defined as a cylinder around the optical axis of said third objective part, extending from the object plane to the image plane and having a maximum radius of 1.5 fold of a maximum beam height within said third objective part.

27. 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.

28. Projection objective according to claim 1, wherein between the radius R1 of the first concave mirror and the radius R2 of the second concave mirror the following relation: 0.7<|R1/R2|<1.3 is satisfied.

29. Projection objective according to claim 1, wherein between the radius R1 of the first concave mirror and the radius R2 of the second concave mirror and the distance d on the optical axis between the two concave mirrors the relation: 0.7<(|R1|+|R2|)/2/d<1.3 is satisfied.

30. Projection objective according to claim 1, wherein at least one lens having a free entry surface and a free exit surface is arranged within an intermirror space defined between the first and second concave mirror.

31. Projection objective according to claim 30, wherein the lens is a mirror-related lens arranged such that it is transited twice by the radiation passing to and from the concave mirror.

32. Projection objective according to claim 31, wherein the mirror-related lens is a negative lens.

33. Projection objective according to claim 31, wherein the mirror-related lens is a meniscus lens having negative refractive power and a sense of curvature similar to the sense of curvature of the concave mirror to which the mirror-related lens is assigned.

34. Projection objective according to claim 31, wherein the mirror-related lens is designed as a truncated lens being arranged mostly on the side of the optical axis where the associated concave mirror is situated.

35. Projection objective according to claim 1, wherein there is at least one lens arranged within an intermirror space defined between the first and second concave mirror, wherein the lens is transited three times by a light beam between the object plane and the image plane.

36. Projection objective according to claim 1, wherein the first concave mirror and the second concave mirror are designed to have essentially the same or exactly the same curvature surfaces.

37. Projection objective according to claim 1, wherein the first concave mirror and the second concave mirror are manufactured such that firstly a mirror blank for the first and second concave mirror is manufactured to obtain a desired concave shape of a mirror surface and that, afterwards, the mirror blank is separated into two truncated mirror used as the first and second concave mirror.

38. Projection objective according to claim 1, wherein the second objective part includes a first catadioptric sub-group consisting of the first concave mirror and a first mirror-related lens and a second catadioptric sub-group consisting of the second concave mirror and a second mirror-related lens, wherein the catadioptric sub-groups are designed essentially identically.

39. Projection objective according to claim 1, wherein concave surfaces of the two concave mirrors are aspheric.

40. Projection objective according to claim 1, wherein there is at least one lens arranged within an intermirror space defined between the concave mirrors, the at least one lens being positioned between an intermediate image and one of the two concave mirrors optically near the intermediate image; where at least one surface of the lens is aspheric.

41. Projection objective according to claim 40, wherein the aspheric surface of the lens is the surface facing the intermediate image.

42. Projection objective according to claim 1, wherein the first concave mirror has a curvature c.sub.1(in [mn.sup.-1]) and the second concave mirror has a curvature c.sub.2(in [mm.sup.31 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: 1<D/(|c.sub.1|+|c.sub.2|)10.sup.-4<6.

43. Projection objective according to claim 1, wherein at least one of the concave mirrors fulfills the condition: p>0.22R where p=R-(R2-D.sup.2/4.sup.)0.5, wherein R is the curvature radius and D is the diameter of the aspherical mirror surface.

44. Projection objective according to claim 43, wherein the condition D<1.3R is fulfilled.

45. Projection objective according to claim 1, wherein the projection objective is designed such that the first intermediate image is located geometrically within an intermirror space defined between the first and second concave mirror and the second intermediate image is arranged outside the intermirror space.

46. Projection objective according to claim 1, wherein the first and the second concave mirror are disposed on the same side of an optical axis of the projection objective.

47. Projection objective according to claim 1, wherein the first concave mirror and the second concave mirror are positioned at opposite sides of an optical axis of the projection objective.

48. Projection objective according to claim 1, wherein at least one lens is arranged outside an intermirror space defined between the first and second concave mirror between a mirror group defined by the first and second concave mirror and the second intermediate image.

49. Projection objective according to claim 1, wherein the projection objective includes at least one biaspherical lens having an aspheric entrance surface and an aspheric exit surface.

50. Projection objective according to claim 49, wherein at least one of the pupil surfaces is formed in the third objective part and wherein the biaspherical lens is arranged between the at least one pupil surface in the third objective part and the image plane.

51. Projection objective according to claim 1, wherein the first objective part includes at least one lens having a concave surface facing the image plane.

52. Projection objective according to claim 51, wherein the lens having a concave surface facing the image plane is a meniscus lens arranged between the object plane and a pupil surface of the first objective part.

53. Projection objective according to claim 1, wherein at least one of the pupil surfaces is formed in the first objective part and a first lens group is arranged between the object plane and the at least one pupil surface in the first objective part, wherein the first lens group includes in that sequence a positive lens, a negative lens and a positive lens, wherein the negative lens has a concave surface facing the image.

54. Projection objective according to claim 1, wherein a maximum diameter of optical elements of the second objective part is smaller or equal to a maximum diameter of lenses of the third objective part.

55. Projection objective according to claim 1, wherein at least one of the pupil surfaces is formed in the third objective part and at least one lens having negative refractive power arranged between the second intermediate image and the at least one pupil surface in the third objective part such that a shallow waist is defined in the beam path, wherein no negative lens is arranged between the waist and the image plane.

56. Projection objective according to claim 1, wherein the third objective part includes no more than two negative lenses.

57. Projection objective according to claim 1, wherein the projection objective has an image side numerical aperture NA<0.9.

58. 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.

59. Projection objective according to claim 1, wherein the projection objective has an image side numerical aperture NA<1.1 when used in connection with an immersion medium.

60. Projection objective according to claim 1, wherein the projection objective is telecentric on both its object end and image end.

61. Projection objective according to claim 1, wherein the projection objective has an essentially homocentric entrance pupil.

62. Projection objective according to claim 1, wherein an aperture stop is provided in the first objective part.

63. Projection objective according to claim 1, wherein an aperture stop is provided in the second objective part.

64. Projection objective according to claim 1, wherein an aperture stop is provided in the third objective part.

65. Projection objective according to claim 1, wherein the projection objective is configured for use with ultraviolet light falling within a wavelength range extending from about 120 nm to about 260 nm.

66. Projection objective according to claim 1, wherein the first concave mirror has a first aspheric mirror surface and the second concave mirror has a second aspheric mirror surface, and wherein the first and second mirror surfaces have essentially the same or identical aspheric shape.

67. Projection objective according to claim 1, wherein at least one of the first and second concave mirrors has a mirror surface having a parabolic shape.

68. Projection objective according to claim 1, wherein the first objective part is purely refractive and has positive lenses only.

69. Projection objective according to claim 68, wherein a plate having essentially parallel plate surfaces is provided in addition to the positive lenses in the first objective part.

70. 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.

71. Projection objective according to claim 1, wherein all negative lenses are arranged optically remote from the pupil surfaces.

72. 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.

73. 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: dd.times..times..times..times.d.times.d.noteq. ##EQU00005## 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.

74. Projection objective according to claim 73, wherein the aspheric surface is free of extremal point in an area including the optically utilized area defined by the optically used radius h.sub.opt and going beyond that area up to a maximum height h.sub.max>h.sub.opt, where h.sub.max=h .sub.opt +OR and where OR is at least 5 mm.

75. 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.

76. Projection objective according to claim 1, wherein aspheric surfaces having at least one extremal point are essentially flat across the entire optically utilized area.

77. Projection objective according to claim 1, having at least one aspheric surface having at least one extremal point, where the aspheric surface is essentially flat across the entire optically utilized area of the optical element such that the following condition holds for that aspheric surface: |p(h)|<p.sub.max where p.sub.max=0.5 mm.

78. 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, refractive objective part for imaging the pattern provided in the object plane into a first intermediate image; a second, catadioptric or catoptric objective part for imaging the first intermediate imaging into a second intermediate image; a third, refractive objective part for imaging the second intermediate imaging onto the image plane; wherein the second objective part includes exactly one first concave mirror having a first continuous mirror surface and exactly one second concave mirror having a second continuous mirror surface, the concave mirror faces of the concave mirrors facing each other and defining an intermirror space; wherein the first and the second intermediate image are located geometrically within the intermirror space between the first concave mirror and the second concave mirror.

79. 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 at a position where a chief ray height exceeds a marginal ray height of the imaging process.

80. 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; all concave mirrors are arranged optically remote from a pupil surface; and curvature surfaces of the first concave mirror and the at least one second concave mirror have a common axis of rotational symmetry defining a catadioptric or catoptric part of the optical axis which is inclined at an angle to an object side part and an image side part of the optical axis.

81. 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