Polarization-modulating element, illumination optical apparatus, exposure apparatus, and exposure method

• US 9,423,694 B2
• Filed: 10/08/2013
• Issued: 08/23/2016
• Est. Priority Date: 02/06/2004
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu, Shigematsu, Koji, Hirota, Hiroyuki, Matsuyama, Tomoyuki
• Primary Examiner(s): Chowdhury, Tarifur
• Assistant Examiner(s): NIXON, OMAR H
• Application Number:
  US14/048,563
• Publication Number:
  US 20140028990A1
• Time in Patent Office: 1,050 Days
• Field of Search: 356/364
• US Class Current: 1/1
• CPC Class Codes: F21V 13/02 Combinations of only two kinds of elements
• CPC Class Codes: F21V 9/14 for producing polarised light
• CPC Class Codes: G02B 27/0977 Reflective elements
• CPC Class Codes: G02B 27/286 for controlling or changing the state of polarisation, e.g. transforming one polarisation state into another G02B5/3083 takes precedence; light guide coupling means utilising polarising elements G02B6/34
• CPC Class Codes: G02B 5/3025 Polarisers, i.e. arrangements capable of producing a definite output polarisation state from an unpolarised input state G02B5/3008, G02B5/3016 take precedence
• CPC Class Codes: G03F 7/701 Off-axis setting using an aperture
• 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 7/70308 Optical correction elements, filters or phase plates for manipulating imaging light, e.g. intensity, wavelength, polarisation, phase or image shift
• CPC Class Codes: G03F 7/70566 Polarisation control

Abstract

There is disclosed a polarization-modulating element for modulating a polarization state of incident light into a predetermined polarization state, the polarization-modulating element being made of an optical material with optical activity and having a circumferentially varying thickness profile.

Claims

1. An illumination optical apparatus which illuminates an object having a pattern with illumination light, the illumination optical apparatus comprising:

an optical integrator arranged in an optical path of the illumination light; and

a polarization modulating member made of an optical material with optical activity, the polarization modulating member having a thickness that varies with respect to azimuthal positions about an optical axis of the illumination optical apparatus, the polarization modulating member being arranged in the optical path on an incidence side of the optical integrator and being arranged around the optical axis so as to surround the optical axis, a direction of an optic axis of the optical material being substantially coincident with a direction of the optical axis of the illumination optical apparatus,

wherein the polarization modulating member rotates a polarization direction of the illumination light so that the illumination light, being incident on the polarization modulating member in a linearly polarized state having the polarization direction along a single direction, is changed to a linearly polarized state having polarization directions being substantially coincident with an azimuthal direction about the optical axis at a pupil plane of the illumination optical apparatus, wherein the polarization modulating member has a region without optical activity in an area perpendicular to the optical axis, the region being on the optical axis, and

wherein the polarization modulating member has substantially constant thicknesses in at least two radial directions that are not parallel to each other.

2. The illumination optical apparatus according to claim 1, wherein the illumination light is irradiated onto the object in a polarization state in which a principal component is S-polarized light.

3. The illumination optical apparatus according to claim 1, wherein a first thickness of the polarization modulating member in an optical path of a first part of the illumination light is different from a second thickness of the polarization modulating member in an optical path of a second part of the illumination light, and

the first part of the illumination light passes through a first portion of the pupil plane away from the optical axis, and the second part of the illumination light passes through a second portion of the pupil plane away from the optical axis, the first and second portions being different from each other.

4. The illumination optical apparatus according to claim 3, further comprising a polarization converter arranged in the optical path on an incidence side of the polarization modulating member, wherein

the polarization converter converts a polarization state of the illumination light from a first polarization state including a substantially single polarization into a second polarization state different from the first polarization state.

5. The illumination optical apparatus according to claim 4, wherein a principal component of the second polarization state is linearly polarized light polarized substantially in the single direction.

6. The illumination optical apparatus according to claim 4, wherein a principal component of the first polarization state is linearly polarized light, circularly polarized light or elliptically polarized light.

7. The illumination optical apparatus according to claim 4, wherein the polarization converter comprises at least one of a half wavelength plate and a quarter wavelength plate.

8. The illumination optical apparatus according to claim 4, wherein the first and second portions are included in an annular region about the optical axis.

9. The illumination optical apparatus according to claim 8, wherein the first and second portions are substantially discrete from each other.

10. The illumination optical apparatus according to claim 4, wherein the first and second portions are substantially discrete from each other and are aligned along a circumference about the optical axis.

11. The illumination optical apparatus according to claim 3, wherein the first and second portions are included in an annular region about the optical axis.

12. The illumination optical apparatus according to claim 11, wherein the first and second portions are substantially discrete from each other.

13. The illumination optical apparatus according to claim 3, wherein the first and second portions are substantially discrete from each other and are aligned along a circumference about the optical axis.

14. The illumination optical apparatus according to claim 1, wherein the optical integrator comprises a fly'"'"'s eye lens, and a surface of an exit side of the fly'"'"'s eye lens is arranged at a position substantially equivalent to the pupil plane.

15. The illumination optical apparatus according to claim 1, further comprising a polarization converter arranged in the optical path on an incidence side of the polarization modulating member, wherein

the polarization converter converts a polarization state of the illumination light from a first polarization state including a substantially single polarization into a second polarization state different from the first polarization state.

16. The illumination optical apparatus according to claim 15, wherein a principal component of the second polarization state is linearly polarized light polarized substantially in the single direction.

17. The illumination optical apparatus according to claim 15, wherein a principal component of the first polarization state is linearly polarized light, circularly polarized light or elliptically polarized light.

18. The illumination optical apparatus according to claim 15, wherein the polarization converter comprises at least one of a half wavelength plate and a quarter wavelength plate.

19. An exposure method which exposes a substrate to light via an object having a pattern, the exposure method comprising:

holding the substrate by the stage;

illuminating the pattern with the light by using the illumination optical apparatus as defined in claim 1; and

projecting an image of the pattern illuminated with the light onto the substrate held by the stage.

20. The exposure method according to claim 19, wherein the substrate is exposed to the light through liquid.

21. A device manufacturing method, comprising:

transferring a pattern to a substrate by using the exposure method as defined in claim 19; and

developing the substrate to which the pattern is transferred.

22. An exposure apparatus which exposes a substrate to light via an object having a pattern, the exposure apparatus comprising:

a stage which holds the substrate,

the illumination optical apparatus as defined in claim 1 which illuminates the pattern with the light; and

a projection optical system which projects an image of the pattern illuminated with the light onto the substrate held by the stage, wherein the polarization modulating member has a region without optical activity in an area perpendicular to the optical axis, the region being on the optical axis, and

wherein the polarization modulating member has substantially constant thicknesses in at least two radial directions that are not parallel to each other.

23. The exposure apparatus according to claim 22, wherein the substrate is exposed to the light through liquid.

24. The exposure apparatus according to claim 22, wherein the light is irradiated onto the object in a polarization state in which a principal component is S-polarized light.

25. The exposure apparatus according to claim 22, wherein a first thickness of the polarization modulating member in an optical path of a first part of the light is different from a second thickness of the polarization modulating member in an optical path of a second part of the light, and

the first part of the light passes through a first portion of the pupil plane away from the optical axis, and the second part of the light passes through a second portion of the pupil plane away from the optical axis, the first and second portions being different from each other.

26. The exposure apparatus according to claim 25, further comprising a polarization converter arranged in the optical path on an incidence side of the polarization modulating member, wherein

the polarization converter converts a polarization state of the light from a first polarization state including a substantially single polarization into a second polarization state different from the first polarization state.

27. The exposure apparatus according to claim 26, wherein a principal component of the second polarization state is linearly polarized light polarized substantially in the single direction.

28. The exposure apparatus according to claim 26, wherein a principal component of the first polarization state is linearly polarized light, circularly polarized light or elliptically polarized light.

29. The exposure apparatus according to claim 26, wherein the polarization converter comprises at least one of a half wavelength plate and a quarter wavelength plate.

30. The exposure apparatus according to claim 25, wherein the first and second portions are included in an annular region about the optical axis.

31. The exposure apparatus according to claim 30, wherein the first and second portions are substantially discrete from each other.

32. The exposure apparatus according to claim 25, wherein the first and second portions are substantially discrete from each other and are aligned along a circumference about the optical axis.

33. The exposure apparatus according to claim 22, wherein the optical integrator comprises a fly'"'"'s eye lens, and a surface of an exit side of the fly'"'"'s eye lens is arranged at a position substantially equivalent to the pupil plane.

34. A device manufacturing method, comprising:

transferring a pattern to a substrate by using the exposure apparatus as defined in claim 22; and

developing the substrate to which the pattern is transferred.