Catadioptric reduction projection optical system

• US 5,668,673 A
• Filed: 06/01/1995
• Issued: 09/16/1997
• Est. Priority Date: 08/05/1991
• Status: Expired due to Fees

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Suenaga, Yutaka, Hayashi, Kiyoshi, Shimizu, Yoshiyuki, Ishiyama, Toshiro
• Primary Examiner(s): NGUYEN, THONG Q
• Application Number:
  US08/456,624
• Time in Patent Office: 838 Days
• Field of Search: 359/364-366, 359/726-732, 359/857-863
• US Class Current: 359/731
• CPC Class Codes: G02B 17/0828 off-axis or unobscured systems in which all of the mirrors share a common axis of rotational symmetry
• CPC Class Codes: G02B 17/0892 specially adapted for the UV
• CPC Class Codes: G03F 7/70225 Optical aspects of catadioptric systems, i.e. comprising reflective and refractive elements

Abstract

A first partial optical system including a first group of lenses having a positive refractive power, a first concave reflection mirror and a second group of lenses having a positive refractive power, for forming a primary reduced image of an object, a second partial optical system including a second concave reelection mirror and a third group of lenses having a positive refractive power, for further reducing the primary reduced image and refocusing it, and a reflection mirror arranged between the first partial optical system and the second partial optical system, for deflecting a light path are arranged in a sequence as viewed from the object. A good image-forming ability as a projection optical system for fabricating a semiconductor device is attained with a simple construction.

Claims

1. A catadioptric reduction projection optical system for forming a reduced image of an object, comprising in a light path sequence from the object;

a first partial optical system including a first group of lenses having a positive refractive power, a first concave reflection mirror and a second group of lenses having a positive refractive power, for forming a primary reduced image of the object;

a second partial optical system including a second concave reflection mirror and a third group of lenses having a positive refractive power, for further reducing the primary reduced image to refocus the image; and

a reflection mirror arranged in a light path between said first partial optical system and said second partial optical system for deflecting the optical path.

2. A catadioptric reduction projection optical system according to claim 1, wherein said first concave reflection mirror has a reduction magnification and said second concave reflection mirror has an enlargement magnification.

3. A catadioptric reduction projection optical system according to claim 1, wherein a magnification β

of said second concave reflection mirror M₂ meets a condition of;

space="preserve" listing-type="equation">-2.5<

β

.sub.M2 <

-0.7.

4. A catadioptric reduction projection optical system according to claim 1, wherein a magnification β

said first concave reflection mirror meets a condition of;

space="preserve" listing-type="equation">-2.0<

β

.sub.M1 <

-0.3.

5. A catadioptric reduction projection optical system according to claim 1, wherein said first group of lenses is arranged in the vicinity of the object functions as a field lens and corrects distortion aberration, and said second group of lenses and said third group of lenses contribute to the formation of the reduced image and function to correct a Petzval sum.

6. A catadioptric reduction projection optical system according to claim 1, wherein said first concave reflection mirror and said second concave reflection mirror are spherical mirrors, and said second partial optical system has a fourth group of lenses between said second concave reflection mirror and said third group of lenses.

7. A catadioptric reduction projection optical system according to claim 6, wherein said first group of lenses of said first partial optical system includes a biconvex positive lens and a negative meniscus lens having a convex surface thereof facing the object, said second group of lenses includes a negative meniscus lens having a convex surface thereof faced to said first concave reflection mirror and a positive lens having a stronger radius of curvature on a surface facing said first concave reflection mirror, and said third group of lenses of said second partial optical system includes a positive lens having a stronger radius of curvature on a surface facing said second concave reflection mirror, a meniscus lens having a convex surface thereof facing said second concave reflection mirror and a positive lens having a stronger radius of curvature on a surface facing said second concave reflection mirror.

8. A catadioptric reduction projection optical system according to claim 6, wherein said first partial optical system has a fifth group of lenses including a meniscus lens having a convex surface thereof facing said first concave reflection mirror.

9. A catadioptric reduction projection optical system according to claim 8, wherein said first group of lenses includes a biconvex positive lens, a meniscus lens having a concave surface thereof facing the object and a meniscus lens having a convex surface thereof facing the object.

10. A catadioptric reduction projection optical system for forming a reduced image of an object, including:

a first partial optical system having first reflecting means and first refracting means to condense a light beam from the object and form a reduced primary image; and

a second partial optical system having second reflecting means and second refracting means to form a further reduced secondary image from said primary image;

said first reflecting means having only one concave reflecting mirror, said first refracting means having a lens group of positive refractive power disposed between said object and said concave reflecting mirror;

said second reflecting means having only one concave reflecting mirror, said second refracting means having a lens group of positive refractive power disposed between said concave reflecting mirror of said second partial optical system and said second secondary image.

11. A catadioptric reduction projection optical system according to claim 10, wherein negative Petzval sum created in the concave reflecting mirror of said first partial optical system and the concave reflecting mirror of said second partial optical system is corrected by positive Petzval sum created by the first refracting means of said first partial optical system and the second refracting means of said second partial optical system.

12. A catadioptric reduction projection optical system according to claim 11, wherein a magnification β

_M2 of the concave reflecting mirror of said second partial optical system meets a condition of;

space="preserve" listing-type="equation">-2.5<

β

.sub.M2 <

-0.7.

13. A catadioptric reduction projection optical system according to claim 11, wherein a magnification β

_M1 of the concave reflecting mirror of said first partial optical system meets a condition of;

space="preserve" listing-type="equation">-2.0<

β

.sub.M1 <

-0.3.

14.

14. A catadioptric reduction projection optical system according to claim 11, further including a plane reflecting member disposed between the concave reflecting mirror of said first partial optical system and the concave reflecting mirror of said second partial optical system for bending the optical path.

15. A catadioptric reduction projection optical system according to claim 10, wherein the concave reflecting mirror of said first partial optical system has a reduction magnification, and the concave reflecting mirror of said second partial optical system has an enlargement magnification.

16. A catadioptric reduction projection optical system for forming a reduced image of an object comprising, in succession from an object side:

a first partial optical system including, in succession from the object side, a first lens group of positive refractive power, and a first concave reflection mirror, for forming a primary image of the object; and

a second partial optical system including, in succession from the object side, a second lens group, a second concave reflection mirror, and a third lens group of positive refractive power, for re-imaging the primary image.

17. A system according to claim 16, wherein said third lens group is constituted to satisfy:

space="preserve" listing-type="equation">0.05<

β

.sub.G3 <

0.6

where β

_G3 is the magnification of said third lens group.

18. A system according to claim 16, wherein said first concave reflection mirror is constituted to satisfy:

space="preserve" listing-type="equation">-2.0<

β

.sub.M1 <

-0.7

where β

_M1 is a magnification of said first concave reflection mirror.

19. A system according to claim 16, wherein said second concave reflection mirror is constituted to satisfy:

space="preserve" listing-type="equation">-2.5<

β

.sub.M2 <

-0.7

where β

_M2 is a magnification of said second concave reflection mirror.

20. A system according to claim 16, wherein at least one of said first to third lens groups is constituted by at least two different optical materials, thereby correcting chromatic aberration.

21. A system according to claim 20, wherein the optical materials include quartz glass and fluorite.

22. A system according to claim 16, further including at least two reflection mirrors arranged in light paths of said first and second partial optical systems, thereby making an object surface parallel to an image surface.

23. A system according to claim 22, wherein one of said at least two reflection mirrors is arranged in the light path of said first partial optical system, and

the other of said at least two reflection mirrors is arranged in the light path of said second partial optical system.

24. A system according to claim 16, wherein at least one of said first and second concave reflection mirrors has a non-spherical reflection surface.

25. A catadioptric reduction projection optical system for forming a reduced image of an object, comprising:

a first partial optical system for forming a primary image of the object; and

a second partial optical system for forming a secondary image of the object based on light from the primary image,

said first partial optical system having a first lens group of positive refractive power, a second lens group of negative refractive power, and a first concave reflection mirror in succession from a light incident side, and

said second partial optical system having a second concave reflection mirror, and a fourth lens group of positive refractive power,

wherein a third lens group is disposed in a light path between said first concave reflection mirror and said second concave reflection mirror,

said first to fourth lens groups consist of at least one material selected from a group consisting of quartz glass and fluorite, and

a magnification β

_M1 of said first concave reflection mirror and a magnification β

_M2 of said second concave reflection mirror meet conditions of;

space="preserve" listing-type="equation">-1.0<

β

.sub.M1 <

-0.7

space="preserve" listing-type="equation">-2.5<

β

.sub.M2 <

-1.2.

26. A system according to claim 25, wherein a magnification β

_G4 of said fourth lens group meets a condition of;

space="preserve" listing-type="equation">0.05<

β

.sub.G4 <

0.3.

27.

27. A system according to claim 26, wherein

said third lens group has at least one positive lens consisting of quartz glass and at least one negative lens consisting of fluorite, and

said fourth lens group has at least two positive lenses consisting of fluorite and at least one negative lens consisting of quartz glass.

28. A system according to claim 26, wherein

said second lens group is constituted by a single lens of negative refractive power, and a glass material of said single lens is fluorite.