Illumination optical system, exposure apparatus and device manufacturing method

• US 9,563,130 B2
• Filed: 12/08/2014
• Issued: 02/07/2017
• Est. Priority Date: 06/19/2010
• Status: Active Grant

• Current Assignee: Nikon Corporation
• Original Assignee: Nikon Corporation
• Inventors: Shigematsu, Koji
• Primary Examiner(s): Whitesell Gordon, Steven H
• Application Number:
  US14/563,275
• Publication Number:
  US 20150092173A1
• Time in Patent Office: 792 Days
• US Class Current: 1/1
• CPC Class Codes: G02B 27/0927 Systems for changing the beam intensity distribution, e.g. Gaussian to top-hat
• 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 5/3083 Birefringent or phase retarding elements G02B5/3008, G02B5/3016 take precedence; systems for polarisation control G02B27/286; manufacturing phase modulating patterns by lithographic processes G03F7/001
• 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 7/701 Off-axis setting using an aperture
• 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 7/70191 Optical correction elements, filters or phase plates for controlling intensity, wavelength, polarisation, phase or the like
• CPC Class Codes: G03F 7/702 Reflective illumination, i.e. reflective optical elements other than folding mirrors, e.g. extreme ultraviolet [EUV] illumination systems
• CPC Class Codes: G03F 7/70558 Dose control, i.e. achievement of a desired dose
• CPC Class Codes: G03F 7/70566 Polarisation control

Abstract

The illumination optical system for illuminating an illumination target surface with light from a light source is provided with a polarization converting member which converts a polarization state of incident light to form a pupil intensity distribution in a predetermined polarization state on an illumination pupil of the illumination optical system; and a phase modulating member which is arranged in the optical path on the illumination target surface side with respect to the polarization converting member and which transmits light from the pupil intensity distribution so as to convert linearly polarized light thereof polarized in a first direction, into required elliptically polarized light and maintain a polarization state of linearly polarized light polarized in a second direction (X-direction or Y-direction) obliquely intersecting with the first direction, in order to reduce influence of retardation caused by a subsequent optical system between the polarization converting member and the illumination target surface.

Claims

1. An illumination optical system for illuminating an illumination target surface with light from a light source, comprising:

a polarization converting member which is arranged in an optical path of the illumination optical system and which converts a polarization state of incident light so as to form a pupil intensity distribution in a predetermined polarization state on an illumination pupil of the illumination optical system;

a first path bending mirror having a planar reflecting surface; and

a wave plate which is arranged in the optical path between the polarization converting member and the first path bending mirror and an optic axis of which is set in a direction along a first plane including an optical axis of an optical system arranged on the light source side of the first path bending mirror and an optical axis of an optical system arranged on the illumination target surface side of the first path bending mirror, or in a direction perpendicular to said direction along the first plane.

2. The illumination optical system according to claim 1, further comprising a second path bending mirror having a planar reflecting surface,

wherein a second plane including an optical axis of an optical system arranged on the light source side of the second path bending mirror and an optical axis of an optical system arranged on the illumination target surface side of the second path bending mirror is coincident with said first plane or parallel to said first plane.

3. The illumination optical system according to claim 1, wherein the wave plate is arranged in the optical path on the illumination target surface side of the polarization converting member.

4. An exposure apparatus comprising the illumination optical system as set forth in claim 1 for illuminating a predetermined pattern, the exposure apparatus performing exposure of a photosensitive substrate with the predetermined pattern.

5. The exposure apparatus according to claim 4, further comprising a projection optical system which forms an image of the predetermined pattern on the photosensitive substrate,

wherein the illumination pupil is located at a position optically conjugate with an aperture stop of the projection optical system.

6. The exposure apparatus according to claim 5, wherein the wave plate reduces influence of retardation caused by the projection optical system.

7. A device manufacturing method comprising:

performing the exposure of the photosensitive substrate with the predetermined pattern, using the exposure apparatus as set forth in claim 4;

developing the photosensitive substrate on which the predetermined pattern is transferred, and 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.

8. An illumination method for illuminating an illumination target surface with light from a light source, comprising:

converting a polarization state of incident light from the light source so as to form a pupil intensity distribution in a predetermined polarization state on an illumination pupil by using a polarization converting member;

passing light from the polarization converting member through a wave plate; and

bending light from the wave plate by using a first path bending mirror having a planar reflecting surface,

wherein an optic axis of the wave plate is set in a direction along a first plane including an optical axis of an optical system arranged on the light source side of the first path bending mirror and an optical axis of an optical system arranged on the illumination target surface side of the first path bending mirror, or in a direction perpendicular to said direction along the first plane.

9. The illumination method according to claim 8, further comprising

bending light from the first path bending mirror by using a second path bending mirror having a planar reflecting surface,

wherein a second plane including an optical axis of an optical system arranged on the light source side of the second path bending mirror and an optical axis of an optical system arranged on the illumination target surface side of the second path bending mirror is coincident with said first plane or parallel to said first plane.

10. The illumination method according to claim 8, wherein the wave plate is arranged in the optical path on the illumination target surface side of the polarization converting member.

11. An exposure method comprising:

illuminating a predetermined pattern by using the illumination method according to claim 8, and

exposing a photosensitive substrate with the predetermined pattern.

12. The exposure method according to claim 11, further comprising projecting an image of the predetermined pattern on the photosensitive substrate.

13. A device manufacturing method comprising:

performing the exposure of the photosensitive substrate with the predetermined pattern, using the exposure method as set forth in claim 11;

developing the photosensitive substrate on which the predetermined pattern is transferred, and 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.