Optical system, exposure system, and exposure method

• US 20100142051A1
• Filed: 02/05/2010
• Published: 06/10/2010
• Est. Priority Date: 01/27/2004
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Omura, Yasuhiro
• Granted Patent: US 8,351,021 B2
• Time in Patent Office: Days
• US Class Current: 359/494
• CPC Class Codes: G02B 13/143 for use with ultraviolet radiation
• CPC Class Codes: G02B 17/08 Catadioptric systems used in non-imaging applications G02B19/00
• CPC Class Codes: G02B 17/0892 specially adapted for the UV
• CPC Class Codes: G02B 27/28 for polarising used in stereoscopes G02B30/25
• CPC Class Codes: G03F 7/70091 Illumination settings, i.e. intensity distribution in the pupil plane or angular distribution in the field plane; On-axis or off-axis settings, e.g. annular, dipole or quadrupole settings; Partial coherence control, i.e. sigma or numerical aperture [NA]
• CPC Class Codes: G03F 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• CPC Class Codes: G03F 7/70566 Polarisation control
• CPC Class Codes: G03F 7/70966 Birefringence

Abstract

An optical system is able to achieve a substantially azimuthal polarization state in a lens aperture while suppressing loss of light quantity, based on a simple configuration. The optical system of the present invention is provided with a birefringent element for achieving a substantially circumferential distribution or a substantially radial distribution as a fast axis distribution in a lens aperture, and an optical rotator located behind the birefringent element and adapted to rotate a polarization state in the lens aperture. The birefringent element has an optically transparent member which is made of a uniaxial crystal material and a crystallographic axis of which is arranged substantially in parallel with an optical axis of the optical system. A light beam of substantially spherical waves in a substantially circular polarization state is incident to the optically transparent member.

Claims

1. An optical system comprising:

a birefringent optical rotator which is made of an optical material with linear birefringence and optical rotatory power and an optic axis of which is arranged substantially in parallel with an optical axis of the optical system,

wherein a beam bundle in a substantially circular polarization state is incident to the birefringent optical rotator.

2. The optical system according to claim 1,

wherein the birefringent optical rotator is located at a position where a beam bundle of substantially spherical waves is incident thereto, and

includes a required thickness for converting a beam bundle in a peripheral region of the incident beam bundle into a beam bundle in a substantially linear polarization state of substantially circumferential vibration in a lens aperture.

3. The optical system according to claim 2,

wherein the birefringent optical rotator includes

a first optically transparent member made of an optical material with clockwise optical rotatory power, and

a second optically transparent member made of an optical material with counterclockwise optical rotatory power.

4. The optical system according to claim 2,

said optical system including a projection optical system which forms an image of a first plane on a second plane.

5. The optical system according to claim 4,

wherein the projection optical system is arranged to be substantially telecentric on the first plane side, and

wherein the birefringent optical rotator is located in an optical path which is substantially telecentric on the first plane side.

6. The optical system according to claim 4,

wherein the projection optical system is arranged to be substantially telecentric on the second plane side, and

wherein the birefringent optical rotator is located in an optical path which is substantially telecentric on the second plane side.

7. The optical system according to claim 1,

said optical system including an illumination optical system which illuminates a surface to be illuminated, in a substantially telecentric manner.

8. The optical system according to claim 7,

wherein the birefringent optical rotator is located near the surface to be illuminated, or at or near a position optically conjugate with the surface to be illuminated, in an optical path of the illumination optical system.

9. The optical system according to claim 8,

wherein the illumination optical system forms a secondary light source including a predetermined optical intensity distribution, on an illumination pupil plane, and

wherein the predetermined optical intensity distribution of the secondary light source is so set that an optical intensity in a pupil center region being a region on the illumination pupil and including an optical axis is smaller than an optical intensity in a region around the pupil center region.

10. The optical system according to claim 9,

wherein the predetermined optical intensity distribution of the secondary light source includes an optical intensity distribution of an annular shape or multi-pole shape.

11. The optical system according to claim 1,

said optical system including a projection optical system which forms an image of a first plane on a second plane.

12. The optical system according to claim 11,

wherein the projection optical system is arranged to be substantially telecentric on the first plane side, and

wherein the birefringent optical rotator is located in an optical path which is substantially telecentric on the first plane side.

13. The optical system according to claim 11,

wherein the projection optical system is arranged to be substantially telecentric on the second plane side, and

wherein the birefringent optical rotator is located in an optical path which is substantially telecentric on the second plane side.

14. The optical system according to claim 12,

said optical system including an illumination optical system which illuminates a surface to be illuminated, in a substantially telecentric manner.

15. The optical system according to claim 14,

wherein the birefringent optical rotator is located near the surface to be illuminated, or at or near a position optically conjugate with the surface to be illuminated, in an optical path of the illumination optical system.

16. The optical system according to claim 15,

wherein the illumination optical system forms a secondary light source including a predetermined optical intensity distribution, on an illumination pupil plane, and

wherein the predetermined optical intensity distribution of the secondary light source is so set that an optical intensity in a pupil center region being a region on the illumination pupil and including an optical axis is smaller than an optical intensity in a region around the pupil center region.

17. The optical system according to claim 16,

wherein the predetermined optical intensity distribution of the secondary light source includes an optical intensity distribution of an annular shape or multi-pole shape.

18. The optical system according to claim 14,

wherein the illumination optical system forms a secondary light source including a predetermined optical intensity distribution, on an illumination pupil plane, and

wherein the predetermined optical intensity distribution of the secondary light source is so set that an optical intensity in a pupil center region being a region on the illumination pupil and including an optical axis is smaller than an optical intensity in a region around the pupil center region.

19. The optical system according to claim 18,

wherein the predetermined optical intensity distribution of the secondary light source includes an optical intensity distribution of an annular shape or multi-pole shape.

20. The optical system according to claim 1,

said optical system being an optical system for lithography.