Illumination optical system, exposure apparatus, and exposure method with polarized state detection result and adjustment
First Claim
1. A method for adjusting an illumination optical system that illuminates an illuminated surface with light including a predetermined polarized state supplied from a light source, comprising:
- a wavelength plate setting step of (i) setting a quarter-wave plate in an illumination light path of the illumination optical system such that a crystal optic axis of the quarter-wave plate is set at a predetermined angular position, and (ii) setting a half-wave plate in the illumination light path such that a crystal optic axis of the half-wave plate is set at a predetermined angular position, whereinbased on a result of detection of a polarized state of the light in the light path between a polarized state switching device and the illuminated surface when the crystal optic axes of the quarter-wave plate and the half-wave plate are respectively changed, the wavelength plate setting step sets (1) the crystal optic axis of the quarter-wave plate at a desired position for converting incident elliptically polarized light into linearly polarized light, and (2) the crystal optic axis of the half-wave plate at a standard position for converting incident linearly polarized light into linearly polarized light that includes a polarized plane in a predetermined direction, whereinthe crystal optic axis of the quarter-wave plate is set at a first angular position, at which a contrast for changes in an S1 component of a Stokes parameter becomes substantially maximum in the detection result, andthe crystal optic axis of the half-wave plate is set at a second angular position, at which the S1 component of the Stokes parameter becomes substantially maximum or substantially minimum in the detection result while the crystal optic axis of the quarter-wave plate is set at the first angular position.
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Abstract
An illumination optical system for, when installed in an exposure system, realizing a suitable illumination condition by varying the polarized state of the illumination light according to the pattern characteristics of the mask while suppressing the loss of the intensity of the light. The illumination optical system has a light source unit for supplying a linearly polarized light for illuminating surfaces to be illuminated therewith, and a polarized state changing device for changing the polarized state of the illuminating light from a predetermined polarized state to a nonpolarized state and vice versa. The polarized state changing device is arranged in the optical path between the light source unit and the surfaces to be illuminated. The polarized state changing device can be removed from the illumination optical path and has a depolarizer for selectively depolarizing the incident linearly polarized light.
39 Citations
28 Claims
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1. A method for adjusting an illumination optical system that illuminates an illuminated surface with light including a predetermined polarized state supplied from a light source, comprising:
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a wavelength plate setting step of (i) setting a quarter-wave plate in an illumination light path of the illumination optical system such that a crystal optic axis of the quarter-wave plate is set at a predetermined angular position, and (ii) setting a half-wave plate in the illumination light path such that a crystal optic axis of the half-wave plate is set at a predetermined angular position, wherein based on a result of detection of a polarized state of the light in the light path between a polarized state switching device and the illuminated surface when the crystal optic axes of the quarter-wave plate and the half-wave plate are respectively changed, the wavelength plate setting step sets (1) the crystal optic axis of the quarter-wave plate at a desired position for converting incident elliptically polarized light into linearly polarized light, and (2) the crystal optic axis of the half-wave plate at a standard position for converting incident linearly polarized light into linearly polarized light that includes a polarized plane in a predetermined direction, wherein the crystal optic axis of the quarter-wave plate is set at a first angular position, at which a contrast for changes in an S1 component of a Stokes parameter becomes substantially maximum in the detection result, and the crystal optic axis of the half-wave plate is set at a second angular position, at which the S1 component of the Stokes parameter becomes substantially maximum or substantially minimum in the detection result while the crystal optic axis of the quarter-wave plate is set at the first angular position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17)
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18. An exposure apparatus comprising:
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an illumination optical system that illuminates an illuminated surface with light including a predetermined polarized state supplied from a light source, the illumination optical system having been adjusted by (i) setting a quarter-wave plate in an illumination light path of the illumination optical system such that a crystal optic axis of the quarter-wave plate is set at a predetermined angular position, and (ii) setting a half-wave plate in the illumination light path such that a crystal optic axis of the half-wave plate is set at a predetermined angular position, wherein based on a result of detection of a polarized state of the light in the light path between a polarized state switching device and the illuminated surface when the crystal optic axes of the quarter-wave plate and the half-wave plate are respectively changed, (1) the crystal optic axis of the quarter-wave plate having been set at a desired position for converting incident elliptically polarized light into linearly polarized light, and (2) the crystal optic axis of the half-wave plate having been set at a standard position for converting incident linearly polarized light into linearly polarized light that includes a polarized plane in a predetermined direction; a projection optical system positioned in the light path between a first plane at which a mask is positioned, and a second plane at which a photosensitive substrate is positioned, the projection optical system forming an image of a pattern on the mask onto the second plane; a pupil intensity distribution forming device that forms a predetermined light intensity distribution at a position conjugate to a pupil of the projection optical system or a position adjacent thereto; a pupil intensity distribution changing device that changes at least one of a shape and a size of the predetermined light intensity distribution; and a polarized state changing device that is positioned in the light path between the light source and the illuminated surface and changes the polarized state of the light that illuminates the illuminated surface, wherein the pupil intensity distribution changing device changes at least one of the shape and the size of the predetermined light intensity distribution in accordance with pattern characteristics of the mask, and the polarized state changing device changes the polarized state of the light that illuminates the illuminated surface in accordance with at least one of the shape and the size of the predetermined light intensity distribution. - View Dependent Claims (19, 20, 21, 22, 23, 24)
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25. An exposure method comprising:
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illuminating a mask through an illumination optical system that illuminates an illuminated surface with light including a predetermined polarized state supplied from a light source, the illumination optical system being adjusted by a wavelength plate setting step of (i) setting a quarter-wave plate in an illumination light path of the illumination optical system such that a crystal optic axis of the quarter-wave plate is set at a predetermined angular position, and (ii) setting a half-wave plate in the illumination light path such that a crystal optic axis of the half-wave plate is set at a predetermined angular position, wherein based on a result of detection of a polarized state of the light in the light path between a polarized state switching device and the illuminated surface when the crystal optic axes of the quarter-wave plate and the half-wave plate are respectively changed, the wavelength plate setting step sets (1) the crystal optic axis of the quarter-wave plate at a desired position for converting incident elliptically polarized light into linearly polarized light, and (2) the crystal optic axis of the half-wave plate at a standard position for converting incident linearly polarized light into linearly polarized light that includes a polarized plane in a predetermined direction; exposing an image of a pattern on the mask onto a photosensitive substrate positioned on the illuminated surface by; forming the image of the pattern on the mask using a projection optical system; forming a predetermined light intensity distribution at a position conjugate to a pupil of the projection optical system or a position adjacent thereto; and changing at least one of a shape or a size of the predetermined light intensity distribution in accordance with pattern characteristics of the mask; the exposure method further comprising changing a polarized state of the light that illuminates the illuminated surface in accordance with a change in the at least one of the shape and the size of the predetermined light intensity distribution. - View Dependent Claims (26, 27, 28)
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Specification