ILLUMINATION APPARATUS, ILLUMINATION METHOD, EXPOSURE APPARATUS, AND DEVICE MANUFACTURING METHOD

• US 20090116093A1
• Filed: 10/22/2008
• Published: 05/07/2009
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: TANITSU, Osamu
• Granted Patent: US 9,116,346 B2
• Time in Patent Office: Days
• US Class Current: 359/239
• CPC Class Codes: G02B 26/02 for controlling the intensity of light G02B26/004 takes precedence
• CPC Class Codes: G02B 26/0833 the reflecting element being a micromechanical device, e.g. a MEMS mirror, DMD G02B26/0825 takes precedence; micromechanical devices in general B81B
• CPC Class Codes: G02B 27/0905 Dividing and/or superposing multiple light beams
• CPC Class Codes: G03F 7/70058 Mask illumination systems
• 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

Abstract

To optionally forming a multilevel light intensity distribution on an illumination pupil plane, the illumination apparatus implements Köhler illumination on an illumination target surface, using as a light source the light intensity distribution formed on the illumination pupil plane on the basis of light from a light source. The illumination apparatus has a spatial light modulator, a condensing optical system, and a control unit. The spatial light modulator has a plurality of reflecting surfaces which are two-dimensionally arranged and postures of which can be controlled independently of each other. The condensing optical system condenses light from the reflecting surfaces to form a predetermined light intensity distribution on the illumination pupil plane. The control unit controls the number of reflecting surfaces contributing to arriving light, for each of points on the illumination pupil plane forming the light intensity distribution, according to a light intensity distribution to be formed on the illumination pupil plane.

Claims

1. An illumination apparatus which forms a predetermined light intensity distribution on an illumination pupil plane on the basis of light from a light source and implements Kö

hler illumination on an illumination target surface using the predetermined light intensity distribution as a light source, the illumination apparatus comprising;

a spatial light modulator with a plurality of reflecting surfaces arranged two-dimensionally, postures of the respective reflecting surfaces being controlled independently of each other;

a condensing optical system, arranged in a light path of light from the plurality of reflecting surfaces of the spatial light modulator, to condense the light from the plurality of reflecting surfaces of the spatial light modulator form a predetermined light intensity distribution on the illumination pupil plane and convert light provided with a predetermined angle distribution by the plurality of reflecting surfaces of the spatial light modulator, into a position distribution on the illumination pupil plane; and

a control unit to feed a control signal to the spatial light modulator according to a light intensity distribution to be formed on the illumination pupil plane and control a number of the reflecting surfaces contributing to arriving light, for each of points on the illumination pupil plane forming the light intensity distribution.

2. An illumination apparatus according to claim 1, wherein, in the case that there is a remainder when a number of the reflecting surfaces in the spatial light modulator is divided by a total number of reflecting surfaces necessary for formation of the light intensity distribution on the illumination pupil plane, the control unit controls the postures of the respective reflecting surfaces so that light reflected by remaining reflecting surfaces is guided to a region other than the illumination pupil plane.

3. An illumination apparatus according to claim 2, further comprising a light intensity distribution measuring device for performing measurement of the light intensity distribution formed on the illumination pupil plane,

wherein the control unit controls the postures of the reflecting surfaces in the spatial light modulator, based on a result of the measurement from the light intensity distribution measuring device.

4. An illumination apparatus according to claim 1, further comprising a light intensity distribution measuring device for performing measurement of the light intensity distribution formed on the illumination pupil plane,

wherein the control unit controls the postures of the reflecting surfaces in the spatial light modulator, based on a result of the measurement from the light intensity distribution measuring device.

5. An illumination apparatus according to claim 1, wherein the spatial light modulator comprises a drive unit for individually changing the postures of the reflecting surfaces on the basis of a control signal from the control unit.

6. An illumination apparatus according to claim 5, wherein the drive unit continuously or discretely changes orientations of the reflecting surfaces.

7. An illumination apparatus according to claim 6, wherein the reflecting surfaces contributing to light arriving at a predetermined point on the illumination pupil plane are subjected to such posture control that normals to the respective reflecting surfaces become parallel to each other.

8. An exposure apparatus comprising an illumination apparatus as set forth in claim 1 for illuminating a predetermined pattern, the exposure apparatus performing exposure of the predetermined pattern on a photosensitive substrate.

9. A device manufacturing method comprising:

effecting the exposure of the predetermined pattern on the photosensitive substrate, using the exposure apparatus of claim 8;

developing the photosensitive substrate onto which the predetermined pattern has been transferred, and then forming a mask layer in a shape corresponding to the predetermined pattern on a surface of the photosensitive substrate; and

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

10. An illumination method of forming a predetermined light intensity distribution on an illumination pupil plane on the basis of light from a light source and implementing Kö

hler illumination on an illumination target surface using the predetermined light intensity distribution as a light source, the illumination method comprising;

two-dimensionally arranging a plurality of reflecting surfaces postures of which are controlled independently of each other, on an optical path of light traveling from the light source to the illumination pupil plane;

arranging a condensing optical system which converts light provided with a predetermined angle distribution by the plurality of reflecting surfaces, into a position distribution on the illumination pupil plane, on an optical path of light traveling from the reflecting surfaces to the illumination pupil plane; and

controlling a number of the reflecting surfaces contributing to arriving light, for each of points on the illumination pupil plane forming the light intensity distribution, when the predetermined light intensity distribution is formed on the illumination pupil plane by condensing the light from the reflecting surfaces by the condensing optical system.

11. An illumination method according to claim 10, wherein, in the case that there is a remainder when a number of the reflecting surfaces is divided by a total number of reflecting surfaces necessary for formation of the light intensity distribution on the illumination pupil plane, the postures of the respective reflecting surfaces are controlled so that light reflected by remaining reflecting surfaces is guided to a region other than the illumination pupil plane.

12. An illumination method according to claim 10, wherein the postures of the reflecting surfaces are controlled based on a result of measurement of the light intensity distribution formed on the illumination pupil plane.

13. An illumination method according to claim 10, wherein orientations of the reflecting surfaces are continuously or discretely changed.

14. An illumination method according to claim 10, wherein the reflecting surfaces contributing to light arriving at a predetermined point on the illumination pupil plane are subjected to such posture control that normals to the respective reflecting surfaces are parallel to each other.