Illumination optical system, exposure apparatus and device manufacturing method

• US 10,168,620 B2
• Filed: 12/23/2016
• Issued: 01/01/2019
• 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:
  US15/390,127
• Publication Number:
  US 20170108782A1
• Time in Patent Office: 739 Days
• 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 which illuminates an illumination target surface with illumination light, comprising:

a polarization member arranged on an optical path of the illumination light, the polarization member configured to set a polarization state of first partial light serving as first part of the illumination light into first linear polarization having a polarization direction along a first direction and set a polarization state of second partial light serving as second part of the illumination light into second linear polarization having a polarization direction along a second direction, the second part being different from the first part, the second direction being different from the first direction;

a reflecting surface arranged on the optical path of the illumination light, the reflecting surface configured to reflect the first partial light and the second partial light, the polarization direction of the first linear polarization serving as s-polarization or p-polarization with respect to the reflecting surface; and

a phase member provided downstream on the optical path from the polarization member and configured to emit the second partial light while providing a phase difference between polarization components in the second partial light and emit the first partial light while maintaining the polarization state of the first partial light in the first linear polarization, polarization directions of the polarization components in the second partial light being orthogonal to each other.

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

the phase difference, caused between the polarization components in the second partial light by the phase member, includes a reversely-oriented phase difference with respect to a phase difference, the reversely-oriented phase difference being caused between the polarization components in the second partial light by the reflecting surface.

3. The illumination optical system according to claim 2, wherein

the polarization direction, serving as the s-polarization or the p-polarization with respect to the reflecting surface, is excluded from the polarization direction of the second linear polarization.

4. The illumination optical system according to claim 2, wherein

the first direction and the second direction are set in a positional relationship that excludes a relationship in which the first direction and the second direction are orthogonal to each other.

5. The illumination optical system according to claim 2, wherein

the phase member includes a wave plate having an optical axis directed in a direction intersecting the optical path of the illumination light.

6. The illumination optical system according to claim 5, wherein

the optical axis of the wave plate is directed in the first direction or a direction orthogonal to the first direction.

7. The illumination optical system according to claim 6, wherein

a thickness of the wave plate, in a direction along the optical path of the illumination light, is uniform on a surface intersecting the optical path of the illumination light.

8. The illumination optical system according to claim 2, wherein

the phase member is arranged on the illumination target surface side with respect to the polarization member.

9. The illumination optical system according to claim 1, wherein

the polarization member is comprised of an optical material having an optical rotatory power, and the optical rotatory power causes a difference between the polarization directions of the first partial light and the second partial light.

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

the polarization member is arranged so that an optical axis of the optical material with the optical rotatory power trends in a direction along an optical axis of the illumination optical system.

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

the polarization member is arranged so that the first partial light and the second partial light, out of the illumination light entering the polarization member in a linear polarization state having a polarization direction corresponding to a predetermined direction, pass through the optical material in mutually different lengths along a direction of the optical axis of the optical material.

12. An exposure apparatus comprising the illumination optical system as set forth in claim 1 which illuminates a predetermined pattern, the exposure apparatus performing exposure of a photosensitive substrate with light from the predetermined pattern.

13. The exposure apparatus according to claim 12, further comprising:

a projection optical system which projects light via the predetermined pattern onto the photosensitive substrate.

14. A device manufacturing method, comprising:

performing exposure of the substrate, using the exposure apparatus as set forth in claim 12;

developing the photosensitive substrate on which the predetermined pattern is transferred and forming a mask layer with a shape corresponding to the predetermined pattern; and

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