Claims
- 1. A projection objective for forming an image of an object, comprising:a plurality of optical elements arranged in an optical path between the object and the image, the plurality of optical elements are formed of crystalline material; the crystalline material of at least one of the optical elements is arranged so as to reduce an adverse effect of exposure energy on the crystalline material of the at least one optical element.
- 2. The projection objective according to claim 1, wherein the crystalline material comprises fluoride crystalline material.
- 3. The projection objective according to claim 2, wherein the fluoride crystalline material comprises calcium fluoride.
- 4. The projection objective according to claim 3, wherein the at least one optical element is a cube-type beam splitter.
- 5. The projection objective according to claim 4, wherein the crystalline material of the cube-type beam splitter has a (111) face that is perpendicular to an energy beam that passes through the cube-type beam splitter.
- 6. The projection objective according to claim 1, wherein the crystalline material of the at least one optical element has a (111) face that is perpendicular to an energy beam that passes through the at least one optical element.
- 7. An exposure apparatus that transfers an image of a pattern on a mask onto a substrate, comprising:a light source; an illumination optical system arranged in an optical path between the light source and the mask; and the projection objective according to claim 1.
- 8. The exposure apparatus according to claim 7, wherein the light source supplies an exposure energy beam having a wavelength under 200 nm.
- 9. A method for transferring an image of a pattern on a mask onto a substrate, comprising the steps of:illuminating the mask; and projecting the image of the pattern on the mask onto the substrate by using the projection objective according to claim 1.
- 10. The method according to claim 9, wherein the mask is illuminated by supplying an exposure energy beam having a wavelength under 200 nm.
Priority Claims (1)
Number |
Date |
Country |
Kind |
10-231531 |
Aug 1998 |
JP |
|
Parent Case Info
This is a Division of application Ser. No. 10/208,748 filed Aug. 1, 2002 now U.S. Pat. No. 6,646,797, which in turn is a Divisional of application Ser. No. 09/721,957 filed Nov. 27, 2000 (now U.S. Pat. No. 6,452,723), which is a Divisional of application Ser. No. 09/377,010 filed Aug. 18, 1999 (now U.S. Pat. No. 6,451,507). The entire disclosure of the prior application(s) is hereby incorporated by reference herein in its entirety.
US Referenced Citations (20)
Foreign Referenced Citations (10)
Number |
Date |
Country |
A2-0 816 892 |
Jan 1998 |
EP |
A-1-198759 |
Aug 1989 |
JP |
A-5-173065 |
Jul 1993 |
JP |
A-8-64505 |
Mar 1996 |
JP |
A-8-330220 |
Dec 1996 |
JP |
A-9-246139 |
Sep 1997 |
JP |
A-9-246140 |
Sep 1997 |
JP |
A-10-104513 |
Apr 1998 |
JP |
A-10-284408 |
Oct 1998 |
JP |
WO9925008 |
May 1999 |
WO |
Non-Patent Literature Citations (1)
Entry |
US 6,538,822, 3/2003, Schuster (withdrawn) |