Lighting apparatus, exposure apparatus and microdevice manufacturing method

• US 7,800,734 B2
• Filed: 09/21/2005
• Issued: 09/21/2010
• Est. Priority Date: 09/22/2004
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Komatsuda, Hideki
• Primary Examiner(s): Kim; Peter B
• Assistant Examiner(s): RIDDLE, CHRISTINA A
• Application Number:
  US11/660,927
• Publication Number:
  US 20090002662A1
• Time in Patent Office: 1,826 Days
• Field of Search: 355 67- 71, 355/53, 355/44, 355/45, 355/52, 355/55, 359/599, 359/615, 359/584
• US Class Current: 355/67
• CPC Class Codes: G02B 19/0023 at least one surface having optical power
• CPC Class Codes: G02B 19/0047 for use with a light source G02B19/009, G02B19/0095 take precedence; details of lighting devices in general F21V; non-semiconductor lasers having optical devices external to the laser cavity H01S3/005
• CPC Class Codes: G02B 19/0095 for use with ultraviolet radiation
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• CPC Class Codes: G02B 27/143 using macroscopically faceted or segmented reflective surfaces
• 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 7/702 Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems

Abstract

An illumination apparatus for illuminating a surface (M) to be irradiated with illumination light emitted from a light source (2) comprises a reflection type fly-eye optical systems (12, 14) disposed between the light source (2) and the surface (M) to be irradiated and constituted by a plurality of reflection partial optical systems for wavefront-dividing a light beam from the light source (2) and superposing divided portions of the light beam onto each other on the surface (M) to be irradiated and a reflection type optical system (10) disposed between the light source (2) and the reflection type fly-eye optical systems (12, 14) for guiding the illumination light to the reflection type fly-eye optical systems (12, 14). The reflection type optical system (10) has a reflecting surface at least partly constructed by a diffusing surface.

Claims

1. An illumination apparatus for illuminating a surface to be irradiated with illumination light emitted from a light source, the illumination apparatus comprising:

a reflection type fly-eye optical system, between the light source and the surface to be irradiated, the fly-eye optical system having a plurality of reflection partial optical systems for wavefront-dividing a light beam from the light source and superposing divided portions of the light beam onto each other on the surface to be irradiated; and

a reflection type optical system, between the light source and the reflection type fly-eye optical system, for guiding the illumination light to the reflection type fly-eye optical system,

wherein the reflection type optical system has a reflecting surface, at least partly constructed by a diffusing surface, the diffusing surface guiding an incident light beam to the reflection type fly-eye optical system, and

wherein a diffusion angle of the diffusing surface is such an angle that a full width at half maximum of a range in which a light beam diffused from a point on the diffusing surface by the diffusing surface reaches an entrance surface of the reflection type fly-eye optical system is D/2 to D/100, where D is the entrance diameter of the fly-eye optical system.

2. An illumination apparatus according to claim 1, wherein a half width of a light beam spread from a point of the diffusing surface, at an entrance surface of the reflection type fly-eye optical system is D/2 to D/100, wherein D is the entrance diameter of the fly-eye optical system.

3. An illumination apparatus according to claim 1, wherein an RMS value indicating a surface roughness of the diffusing surface corresponding to a high-frequency region of a PSD (Power Spectral Density) value of a profile of the diffusing surface is smaller than 1/14 of a wavelength of the illumination light.

4. An illumination apparatus according to claim 3, wherein a boundary value between the high-frequency region and a frequency region lower than the high-frequency region is smaller than D/2λ

L, where D is the diameter of an entrance surface of the reflection type fly-eye optical system, L is a distance from the reflection type optical system to the entrance surface of the reflection type fly-eye optical system, and λ

is a wavelength of the illumination light.

5. An illumination apparatus according to claim 3, wherein a boundary value between the high-frequency region and an intermediate frequency region is greater than D/100λ

L, where D is the diameter of an entrance surface of the reflection type fly-eye optical system, L is a distance from the reflection type optical system to the entrance surface of the reflection type fly-eye optical system, and λ

is a wavelength of the illumination light.

6. An illumination apparatus according to claim 1, wherein the difference between a PSD (Power Spectral Density) value of a profile of the diffusing surface and a PSD value of a fractal curve, which represents the PSD value of an ideally polished surface profile, is smaller in a high-frequency region than in a frequency region lower than the high-frequency region.

7. An illumination apparatus according to claim 6, wherein a boundary value between the high-frequency region and a frequency region lower than the high-frequency region is smaller than D/2λ

L, where D is the diameter of an entrance surface of the reflection type fly-eye optical system, L is a distance from the reflection type optical system to the entrance surface of the reflection type fly-eye optical system, and λ

is a wavelength of the illumination light.

8. An illumination apparatus according to claim 6, wherein a boundary value between the high-frequency region and an intermediate frequency region is greater than D/100λ

L, where D is the diameter of an entrance surface of the reflection type fly-eye optical system, L is a distance from the reflection type optical system to the entrance surface of the reflection type fly-eye optical system, and λ

is a wavelength of the illumination light.

9. An illumination apparatus according to claim 1, wherein a surface roughness of the diffusing surface in a pitch finer than 1 mm is 0.5 to 3 nm RMS.

10. An illumination apparatus according to claim 1, wherein the light beam illuminating the surface to be irradiated is EUV light having a wavelength of 5 to 40 nm.

11. An exposure apparatus for transferring a pattern of a mask onto a photosensitive substrate;

the exposure apparatus comprising the illumination apparatus according to claim 1 for illuminating the mask.

12. An illumination apparatus according to claim 1, wherein the half width of a light beam, from the diffusing surface, at an entrance of the reflection type fly-eye optical system is D/2 to D/100, wherein D is the entrance diameter of the fly-eye optical system.

13. An illumination method for illuminating a surface to be irradiated with illumination light emitted from a light source, the illumination method comprising:

wavefront-dividing a light beam from the light source and superposing divided portions of the light beam onto each other on the surface to be irradiated by a reflection type fly-eye optical system, between the light source and the surface to be irradiated, the fly-eye optical system having a plurality of reflection partial optical systems; and

guiding the illumination light to the reflection type fly-eye optical system by a reflection type optical system, between the light source and the reflection type fly-eye optical system;

wherein the reflection type optical system has a reflecting surface, at least partly constructed by a diffusing surface, the diffusing surface guiding an incident light beam to the reflection type fly-eye optical system, and

wherein a diffusion angle of the diffusing surface is such an angle that a full width at half maximum of a range in which a light beam diffused from a point on the diffusing surface by the diffusing surface reaches an entrance surface of the reflection type fly-eye optical system is D/2 to D/100, where D is the entrance diameter of the fly-eye optical system.

14. An exposure method for exposing a pattern of a mask onto a photosensitive substrate, the exposure method comprising:

illuminating a pattern of a mask to be irradiated with illumination light emitted from a light source using the illumination method of claim 13.

15. A method of manufacturing a microdevice, the method comprising:

exposing a pattern of a mask onto a photosensitive substrate using the exposure method of claim 14; and

developing the exposed photosensitive substrate.

16. An illumination method according to claim 13, wherein the half width of a light beam, from the diffusing surface, at an entrance of the reflection type fly-eye optical system is D/2 to D/100, wherein D is the entrance diameter of the fly-eye optical system.