ILLUMINATION OPTICAL SYSTEM, EXPOSURE APPARATUS, AND DEVICE MANUFACTURING METHOD

• US 20090097094A1
• Filed: 10/15/2008
• Published: 04/16/2009
• Est. Priority Date: 10/16/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Tanaka, Hirohisa
• Granted Patent: US 8,520,291 B2
• Time in Patent Office: Days
• US Class Current: 359/239
• CPC Class Codes: G03F 7/70075 Homogenization of illumination intensity in the mask plane by using an integrator, e.g. fly's eye lens, facet mirror or glass rod, by using a diffusing optical element or by beam deflection
• CPC Class Codes: G03F 7/70108 Off-axis setting using a light-guiding element, e.g. diffractive optical elements [DOEs] or light guides
• CPC Class Codes: G03F 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/7085 Detection arrangement, e.g. detectors of apparatus alignment possibly mounted on wafers, exposure dose, photo-cleaning flux, stray light, thermal load

Abstract

An illumination optical system which illuminates an irradiated plane with illumination light provided from a light source includes a spatial light modulator which is arranged in an optical path of the illumination optical system and cooperates with part of the illumination optical system to form a desired light intensity distribution at a pupil position of the illumination optical system or a position optically conjugated with the pupil position. A detection unit detects the light intensity distribution of the illumination light at a position in an optical path extending from the light source to the spatial light modulator. The detection unit includes a light receiving surface which receives some of the illumination light. A control unit controls the spatial light modulator based on the light intensity distribution detected by the detection unit.

Claims

1. An illumination optical system which illuminates an irradiated plane with illumination light provided from a light source, the illumination optical system comprising:

a spatial light modulator which is arranged in an optical path of the illumination optical system and cooperates with part of the illumination optical system to form a desired light intensity distribution at a pupil position of the illumination optical system or a position optically conjugated with the pupil position;

a detection unit which detects the light intensity distribution of the illumination light at a position in an optical path extending from the light source to the spatial light modulator, with the detection unit including a light receiving surface which receives some of the illumination light; and

a control unit which controls the spatial light modulator based on the light intensity distribution detected by the detection unit.

2. The illumination optical system according to claim 1, wherein:

the illumination light includes a plurality of light pulses;

the light receiving surface of the detection unit receives the light intensity distribution of the illumination light formed based on the light pulses, every one or more light pulses; and

the control unit controls the spatial light modulator based on a plurality of the light intensity distributions of the illumination light detected for every one or more light pulses.

3. The illumination optical system according to claim 1, further comprising:

an information acquisition unit which acquires information on the light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position; and

wherein the control unit corrects the controlling executed by the control unit based on the light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position that is acquired by the information acquisition unit.

4. The illumination optical system according to claim 3, further comprising:

an optical path branching member which is arranged in an optical path between the spatial light modulator and the irradiated plane, with the optical path branching member branching off some of the illumination light from the optical path and guiding the branched off light to the information acquisition unit.

5. The illumination optical system according to claim 3, wherein the information acquisition unit acquires information on the light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position based on the illumination light that has passed through the irradiated plane.

6. The illumination optical system according to claim 3, wherein the spatial light modulator includes:

a first spatial light modulator which cooperates with the part of the illumination optical system to form a first light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position; and

a second spatial light modulator which cooperates with the part of the illumination optical system to form a second light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position.

7. The illumination optical system according to claim 6, further comprising:

a divisional light guide member which is arranged in an optical path between the light source and the spatial light modulator, with the divisional light guide member dividing the illumination light from the light source and guiding the divided light to the first and second spatial light modulators.

8. The illumination optical system according to claim 7, wherein the detection unit detects the light intensity distribution of the illumination light at a position in an optical path extending from the light source to the divisional light guide member.

9. The illumination optical system according to claim 3, wherein:

the detection unit detects a position on the light receiving surface at which the illumination light falls; and

the control unit controls the spatial light modulator based on the position on the light receiving surface at which the illumination light falls.

10. The illumination optical system according to claim 9, wherein:

the detection unit includes an incidence angle detection unit which detects incidence angle of the illumination light entering the spatial light modulator; and

the control unit controls the spatial light modulator based on the incidence angle detected by the incidence angle detection unit.

11. The illumination optical system according to claim 10, wherein:

the spatial light modulator includes a plurality of two-dimensionally arranged elements; and

the plurality of two-dimensionally arranged elements are controllable independently from each other to perform spatial optical modulation on incident light before emitting the light.

12. The illumination optical system according to claim 1, wherein the spatial light modulator includes:

a first spatial light modulator which cooperates with the part of the illumination optical system to form a first light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position; and

a second spatial light modulator which cooperates with the part of the illumination optical system to form a second light intensity distribution at the pupil position of the illumination optical system or the position optically conjugated with the pupil position.

13. The illumination optical system according to claim 12, further comprising:

a divisional light guide member which is arranged in an optical path between the light source and the spatial light modulator, with the divisional light guide member dividing the illumination light from the light source and guiding the divided light to the first and second spatial light modulators.

14. The illumination optical system according to claim 13, wherein the detection unit detects the light intensity distribution of the illumination light at a position in an optical path extending from the light source to the divisional light guide member.

15. The illumination optical system according to claim 1, wherein:

the detection unit detects a position on the light receiving surface at which the illumination light falls; and

the control unit controls the spatial light modulator based on the position on the light receiving surface at which the illumination light falls.

16. The illumination optical system according to claim 15, wherein:

the detection unit includes an incidence angle detection unit which detects incidence angle of the illumination light entering the spatial light modulator; and

the control unit controls the spatial light modulator based on the incidence angle detected by the incidence angle detection unit.

17. The illumination optical system according to claim 1, wherein:

the detection unit includes an incidence angle detection unit which detects incidence angle of the illumination light entering the spatial light modulator; and

the control unit controls the spatial light modulator based on the incidence angle detected by the incidence angle detection unit.

18. The illumination optical system according to claim 1, wherein:

the spatial light modulator includes a plurality of two-dimensionally arranged elements; and

the plurality of two-dimensionally arranged elements are controllable independently from each other to perform spatial optical modulation on incident light before emitting the light.

19. The illumination optical system according to claim 18, wherein:

the plurality of elements each include a reflection surface; and

the reflection surfaces of the plurality of elements are controllable independently from each other to perform spatial optical modulation on incident light before emitting the light.

20. The illumination optical system according to claim 19, wherein orientations of the reflection surfaces are controllable independently from each other.

21. An exposure apparatus which transfers a predetermined pattern onto a photosensitive substrate, the exposure apparatus comprising:

the illumination optical system according to claim 1 which illuminates the pattern that is arranged on an irradiated plane.

22. A method for manufacturing a device comprising:

exposing a predetermined pattern onto a photosensitive substrate using the exposure apparatus according to claim 21;

developing the photosensitive substrate onto which the pattern has been transferred to form a mask layer shaped in correspondence with the pattern on a surface of the photosensitive substrate; and

processing the surface of the photosensitive substrate through the mask layer.