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

• US 9,429,848 B2
• Filed: 10/29/2008
• Issued: 08/30/2016
• Est. Priority Date: 02/06/2004
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanitsu, Osamu, Shigematsu, Koji, Hirota, Hiroyuki
• Primary Examiner(s): Punnoose, Roy M
• Application Number:
  US12/289,518
• Publication Number:
  US 20090073414A1
• Time in Patent Office: 2,862 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:

a polarization-modulating element made of an optical material having optical activity, which is arranged in an optical path of the illumination light and which changes a polarization state of the illumination light incident on the polarization-modulating element into a predetermined polarization state based on the optical activity of the optical material, the polarization-modulating element having a circumferentially varying thickness profile;

an annular ratio changing optical system, arranged in the optical path of the illumination light, that changes an annular ratio of a light intensity distribution formed on an illumination pupil of the illumination optical apparatus; and

an optical integrator arranged in the optical path of the illumination light so that a rear focal plane of the optical integrator is substantially coincident with the illumination pupil,

wherein the polarization-modulating element is arranged between the annular ratio changing optical system and the optical integrator, and

wherein the circumferentially varying thickness profile is formed to change a linearly polarized state of the illumination light having a polarization direction substantially along a single direction into an azimuthal polarized state having a polarization direction substantially along a circumferential direction on the illumination pupil.

2. The illumination optical apparatus according to claim 1, wherein the polarization-modulating element has a central region having no optical activity, the central region having a radial size that is not less than ⅓

of a radial size of an effective region of the polarization-modulating element, the central region being enclosed by the optical material having optical activity.

3. The illumination optical apparatus according to claim 1, wherein the polarization-modulating element has a central region and a depolarizer arranged in the central region, the central region being enclosed by the optical material having optical activity.

4. The illumination optical apparatus according to claim 1, wherein the polarization modulating element has sector-shaped elements which are circumferentially arranged.

5. The illumination optical apparatus according to claim 1, wherein the illumination optical apparatus satisfies the following conditions:

(10in+Δ

A)/10out<

0.75;

0.4<

(10in+Δ

A)/10out,

where 10in;

an effective radius of a central region of the polarization-modulating element,

10out;

an outside effective radius of the polarization-modulating element, and

Δ

A;

an increase of an inside radius of a beam passing through the annular ratio changing optical system.

6. An exposure apparatus which exposes a photosensitive substrate with light from a pattern on an object, the exposure apparatus comprising:

a stage which holds the photosensitive substrate;

the illumination optical apparatus according to claim 1 which illuminates the pattern on the object; and

a projection optical system which projects an image of the pattern illuminated with the light onto the photosensitive substrate held by the stage.

7. A device manufacturing method comprising the steps of:

projecting an image of a predetermined pattern onto a photosensitive substrate, using the exposure apparatus according to claim 6, and

developing the photosensitive substrate.

8. The exposure apparatus according to claim 6, wherein the photosensitive substrate is exposed with the light from the pattern through liquid disposed below the projection optical system.

9. The exposure apparatus according to claim 6, wherein the circumferentially varying thickness profile of the polarization-modulating element is formed so that the object is illuminated with the illumination light from the polarization-modulating element via the illumination pupil in a polarization state in which a principal component is S-polarized light.

10. The exposure apparatus according to claim 1, wherein the polarization-modulating element is arranged so that a crystallographic axis of the optical material having optical activity is substantially coincident with an optical axis of the illumination optical apparatus.

11. The illumination optical apparatus according to claim 1, wherein circumferentially varying thickness profile is formed so that the object is illuminated with the illumination light from the polarization-modulating element via the illumination pupil in a polarization state in which a principle component is S-polarized light.

12. The illumination optical apparatus according to claim 1, wherein the polarization-modulating element is arranged so that a crystallographic axis of the optical material having optical activity is substantially coincident with an optical axis of the illumination optical apparatus.

13. An exposure method for exposing a photosensitive substrate with light from a pattern on an object, the exposure method comprising:

holding the photosensitive substrate by a 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 photosensitive substrate held by the stage.

14. The exposure method according to claim 13, wherein the photosensitive substrate is exposed with the light from the pattern through liquid.

15. The exposure method according to claim 13, wherein the circumferentially varying thickness profile of the polarization-modulating element is formed so that the object is illuminated with the illumination light from the polarization-modulating element via the illumination pupil in a polarization state in which a principal component is S-polarized light.

16. The exposure method according to claim 13, wherein the polarization-modulating element is arranged so that a crystallographic axis of the optical material having optical activity is substantially coincident with an optical axis of the illumination optical apparatus.

17. A device manufacturing method comprising the steps of:

projecting an image of a predetermined pattern onto a photosensitive substrate, using the exposure method according to claim 13, and

developing the photosensitive substrate.