Illumination optical apparatus, exposure apparatus, and device manufacturing method

• US 8,094,290 B2
• Filed: 11/06/2008
• Issued: 01/10/2012
• Est. Priority Date: 11/06/2007
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Owa, Soichi, Tanitsu, Osamu, Tanaka, Hirohisa
• Primary Examiner(s): Glick, Edward
• Assistant Examiner(s): Iacoletti, Michelle
• Application Number:
  US12/266,321
• Publication Number:
  US 20090115990A1
• Time in Patent Office: 1,160 Days
• Field of Search: 355/71, 355/67
• US Class Current: 355/67
• 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: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• 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 7/70116 Off-axis setting using a programmable means, e.g. liquid crystal display [LCD], digital micromirror device [DMD] or pupil facets
• CPC Class Codes: G03F 7/70583 Speckle reduction, e.g. coherence control or amplitude/wavefront splitting
• CPC Class Codes: Y10T 29/49826 Assembling or joining

Abstract

An illumination optical system with a simple structure reduces the effects of illumination variations caused by a spatial coherency of illumination light, while maintaining a high usage efficiency of illumination light that is emitted in pulses. The illumination optical system illuminates an irradiated plane with pulse-emitted illumination light and includes a spatial light modulator including a plurality of mirror elements each of which spatially modulates the illumination light in accordance with an incident position of the illumination light. A modulation control unit controls the mirror elements, whenever at least one pulse of illumination light is emitted, in a manner such that the optical elements spatially modulate the pulses of illumination light differently from one another and form substantially the same intensity distribution for the pulses of illumination light on a predetermined plane.

Claims

1. An illumination optical apparatus for illuminating a pattern arranged on an irradiated plane with a plurality of pulses of light, the illumination optical apparatus comprising:

an optical device arranged upstream from the irradiated plane and including a plurality of optical elements, each of which spatially modulates the pulses of light in accordance with incident positions of the pulses of light; and

an illumination control system which controls the plurality of optical elements, whenever at least one pulse of light is emitted, in a manner such that the optical elements spatially modulate the plurality of pulses of light differently from one another; and

a relay optical system arranged downstream from the optical device and changing distribution of angles of incident light to distribution of positions of exit light, wherein the relay optical system guides the plurality of pulses of light spatially modulated by the optical elements to a predetermined plane, which is an illumination pupil plane of the illumination optical system or a plane optically conjugated with the illumination pupil plane.

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

each of the optical elements is a reflective element; and

the reflective element includes a reflection surface which reflects the pulse of light and has a variable inclination angle.

3. The illumination optical apparatus according to claim 2, wherein the inclination angle of the reflection surface about at least one axis is adjustably set within a variable range.

4. The illumination optical apparatus according to claim 1, wherein each of the optical elements is a transmissive element.

5. The illumination optical apparatus according to claim 1, wherein each of the optical elements is a phase element.

6. The illumination optical apparatus according to claim 1, further comprising:

an optical member arranged near the optical device and including a first surface, which deflects each pulse of light in a direction for entering the plurality of optical elements, and a second surface, which deflects each pulse of light traveling through the plurality of optical elements in a direction for entering the irradiated plane.

7. The illumination optical apparatus according to claim 6, wherein the optical member includes a prism.

8. The illumination optical apparatus according to claim 1, further comprising:

a photoelectric sensor which measures an intensity distribution of the pulses of light entering the plurality of optical elements;

wherein the illumination control system controls the plurality of optical elements based on the intensity distribution measured by the photoelectric sensor so that the intensity distribution of the pulses of light on the predetermined plane satisfies a predetermined uniformity condition.

9. The illumination optical apparatus according to claim 1, further comprising:

a polarization control optical system arranged at an incident side of the plurality of optical elements which controls a polarization state of the pulses of light whenever a predetermined number of pulses of light are emitted.

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

each of the pulses of light emitted to the polarization control optical system is substantially linearly polarized; and

the polarization control optical system includes a half-wavelength plate having a rotation angle adjustably set about an optical axis or an axis substantially parallel to the optical axis.

11. The illumination optical apparatus according to claim 1, further comprising:

an optical integrator arranged on the predetermined plane.

12. The illumination optical apparatus according to claim 11, further comprising an optical system arranged downstream from the predetermined plane and guiding the pulses of light that have traveled via the predetermined plane, to the irradiated plane.

13. The illumination optical apparatus according to claim 1, wherein:

the irradiated plane is irradiated by N pulses of light, where N is an integer greater than or equal to 2; and

the illumination optical system controls the plurality of optical elements whenever m pulses of light are emitted, where m is an integer greater than or equal to 1; and

the illumination control system includes at least N or N/m illumination control patterns.

14. The illumination optical apparatus according to claim 1, further comprising:

a light source for emitting the pulses of light.

15. An exposure apparatus for projecting an image of a first plane onto a second plane, the exposure apparatus comprising:

the illumination optical apparatus according to claim 1 which illuminates the first plane with a pulse of light; and

a projection optical system which forms an image of the first plane on the second plane based on light from an illumination region formed on the first plane by the illumination optical apparatus.

16. The illumination optical apparatus according to claim 15, wherein the projection optical system includes an aperture stop, and the predetermined plane is at a location conjugated with the aperture stop.

17. A method for manufacturing a device, the method comprising:

exposing an object using the exposure apparatus according to claim 15; and

processing the exposed object.

18. The illumination optical apparatus according to claim 1, wherein the illumination control system controls the plurality of optical elements in a manner such that the plurality of pulses of light have substantially a same intensity distribution on the predetermined plane.

19. A method for exposing an image of a pattern arranged on a first plane onto an object arranged on a second plane with a plurality of pulses of light, the method comprising:

spatially modulating pulses of light in accordance with incident positions of the pulses of light, wherein the spatially modulating includes spatially modulating the plurality of pulses of light differently from one another by a plurality of optical elements whenever at least one pulse of light is emitted;

guiding the pulses of light that have been spatially modulated through an optical system, which converts distribution of angles of incident light to distribution of positions of exit light, to a predetermined plane to form a given intensity distribution of light on the predetermined plane;

guiding the pulses of light that have traveled via the predetermined plane, to the first plane; and

using a projection optical system to form an image of the pattern arranged on the first plane onto the second plane, wherein the predetermined plane is a plane conjugated with an aperture stop of the projection optical system.

20. A method for manufacturing a device, the method comprising:

exposing an object in accordance with the method according to claim 19; and

processing the exposed object.