WO2006059549A1

WO2006059549A1 - Illumination optical device, manufacturing method thereof, exposure device, and exposure method

Info

Publication number: WO2006059549A1
Application number: PCT/JP2005/021693
Authority: WO
Inventors: Koji Shigematsu
Original assignee: Nikon Corporation
Priority date: 2004-12-03
Filing date: 2005-11-25
Publication date: 2006-06-08
Also published as: TWI437371B; TW200625024A

Abstract

There is provided an illumination optical device capable of illuminating a surface to be irradiated, with light of a desired polarization state while preferably suppressing a change of the polarization state of the light in the illumination optical path. The illumination optical device illuminates the surface to be irradiated (M, W) according to the light supplied from a light source (1). The illumination optical device includes polarization setting units (3, 7) arranged in the optical path between the light source and the surface to be irradiated, for setting the polarization state of the light reaching the surface to be irradiated, to a predetermined polarization state. Each of light transmitting members arranged in the optical path between the deflection setting unit and the surface to be irradiated is formed by an optical material having double refraction amount generated by internal distortion suppressed to 5 nm/cm or below.

Description

Specification

Illumination optical apparatus, manufacturing method thereof, exposure apparatus, and exposure method

Technical field

TECHNICAL FIELD [0001] The present invention relates to an illumination optical apparatus, a manufacturing method thereof, an exposure apparatus, and an exposure method, and in particular, a microdevice such as a semiconductor element, an imaging element, a liquid crystal display element, and a thin film magnetic head is manufactured by a lithography process. The present invention relates to an exposure apparatus.

Background art

In a typical exposure apparatus of this type, a secondary light source as a substantial surface light source consisting of a large number of light sources through a fly-eye lens as a light source force, an emitted light beam force, and an optical integrator. Form. The light flux from the secondary light source (generally, the illumination pupil distribution formed in or near the illumination pupil of the illumination optical device) is restricted through an aperture stop arranged in the vicinity of the rear focal plane of the fly-eye lens. Is incident on the condenser lens

[0003] The light beam collected by the condenser lens illuminates a mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask pattern forms an image on the wafer through the projection optical system. Thus, the mask pattern is projected and exposed (transferred) onto the wafer. Note that the pattern formed on the mask is highly integrated, and in order to accurately transfer this fine pattern onto the wafer, it is essential to obtain a uniform illuminance distribution on the wafer.

[0004] For example, Japanese Patent No. 3246615, which is an application filed by the present applicant, describes a rear focal plane of a fly-eye lens in order to realize an illumination condition suitable for faithfully transferring a fine pattern in any direction. An annular secondary light source is formed in the linearly polarized state where the light flux passing through the annular secondary light source has a polarization direction in the circumferential direction (hereinafter referred to as “circumferential polarization state” for short) ) Disclosed is a technology for setting to be!

[0005] Patent Document 1: Japanese Patent No. 3246615

Disclosure of the invention

Problems to be solved by the invention [0006] Performing projection exposure of a specific pattern using light in a specific linear polarization state without being limited to the above-described circumferential polarization state is effective in improving the resolution of the projection optical system. More generally, performing projection exposure using light in a specific polarization state (hereinafter, a broad concept including a non-polarization state) according to the mask pattern is effective in improving the resolution of the projection optical system.

However, even if an attempt is made to illuminate the mask (and thus the wafer) with light of a desired polarization state, if an optical element that changes the polarization state of the light is interposed in the illumination optical path, the light is bonded in the desired polarization state. There is a possibility that the image is lost, and the imaging performance is deteriorated. In particular, in a light transmissive member such as a lens or a plane-parallel plate disposed in the illumination optical path, the polarization state of light passing therethrough changes due to birefringence caused by internal distortion.

[0008] It is an object of the present invention to provide an illumination optical device that can illuminate an irradiated surface with light in a desired polarization state while suppressing a change in the polarization state of light in an illumination optical path. To do. In addition, using an illumination optical device that illuminates the irradiated surface with light of a desired polarization state, a fine pattern is imaged on the photosensitive substrate in a desired polarization state to perform faithful and good exposure. An object of the present invention is to provide an exposure apparatus and an exposure method that can be used.

Means for solving the problem

In order to achieve the above object, according to a first aspect of the present invention, in an illumination optical apparatus that illuminates an irradiated surface based on light supplied from a light source,

A polarization setting unit for setting a polarization state of light, which is arranged in an optical path between the light source and the irradiated surface, and reaches the irradiated surface to a predetermined polarization state;

Each of the plurality of light transmitting members disposed in the optical path between the polarization setting unit and the irradiated surface is formed of an optical material in which the amount of birefringence generated due to internal distortion is suppressed to 5 nmZcm or less. An illumination optical device is provided.

[0010] In the second embodiment of the present invention, in the illumination optical device that illuminates the irradiated surface based on the light supplied with the light source power,

A plurality of light transmitting members disposed in an optical path between the polarization setting unit and the irradiated surface Are positioned at the required rotational angle positions around the optical axis in order to reduce the effects of birefringence caused by internal distortion in each light transmitting member by canceling each other. An illumination optical device is provided.

[0011] In the third aspect of the present invention, in the illumination optical device that illuminates the irradiated surface based on the light supplied with the light source power,

A polarization setting unit for setting a polarization state of light that is arranged in an optical path between the light source and the irradiated surface and reaches the irradiated surface to a predetermined polarization state;

A folding mirror disposed in the optical path between the polarization setting unit and the irradiated surface for folding the optical path;

The reflection film of the folding mirror has a phase difference generated by reflection between light incident on the reflection film with P-polarized light and light incident on the reflection film with S-polarized light. Provided is an illumination optical device characterized in that it is formed so as to be within 15 degrees of all light rays to be transmitted!

[0012] In the fourth embodiment of the present invention, in the illumination optical apparatus that illuminates the illuminated surface based on the light supplied with the light source power,

A polarization setting unit that is arranged in an optical path between the light source and the irradiated surface and sets a polarization state of light on the irradiated surface to a predetermined polarization state;

There is provided an illumination optical apparatus comprising: an optical system arranged in an optical path between the polarization setting unit and the irradiated surface and having a controlled birefringence amount.

[0013] In the fifth aspect of the present invention, in the illumination optical apparatus that illuminates the illuminated surface based on the light supplied with the light source power,

The polarization of the light reaching the irradiated surface is arranged in an optical path between the polarization setting unit and the irradiated surface so that the polarization state of the light on the irradiated surface becomes the predetermined polarization state. An illumination optical device comprising: an optical system that maintains a light state.

[0014] In a sixth aspect of the present invention, in a method for manufacturing an illumination optical device having a plurality of light transmission members, A bulk material preparing step of preparing a bulk material for forming each of the plurality of light transmitting members;

A measuring step of measuring the birefringence amount of each prepared Balta material;

At least the illumination optical device capable of allowing the influence of birefringence by collecting measurement information of each bulk material of the measurement process force relating to a plurality of light transmitting members constituting at least a part of the illumination optical device. A calculation step of selecting an appropriate combination of a plurality of light transmitting members constituting a part and obtaining a set position of each light transmitting member by an appropriate combination of the plurality of light transmitting members;

A processing step of processing each of the plurality of bulk materials to form each light transmission member, and a set in which each of the plurality of light transmission members processed in the processing step is incorporated at a predetermined set position based on the result of the calculation step. A method for manufacturing an illumination optical apparatus, comprising:

In the seventh embodiment of the present invention, there is provided an illumination optical device manufactured by the illumination optical device of the first to fifth embodiments or the manufacturing method of the sixth embodiment, and a mask illuminated by the illumination optical device. An exposure apparatus is characterized in that a pattern is exposed on a photosensitive substrate.

In the eighth embodiment of the present invention, a mask pattern is exposed on a photosensitive substrate using the illumination optical device of the first to fifth embodiments or the illumination optical device manufactured by the manufacturing method of the sixth embodiment. An exposure method is provided.

In the ninth embodiment of the present invention, a mask pattern is exposed to a photosensitive substrate using the illumination optical apparatus of the first to fifth embodiments or the illumination optical apparatus manufactured by the manufacturing method of the sixth embodiment. And a developing step of developing the photosensitive substrate exposed by the exposing step. A method of manufacturing a microdevice is provided.

[0018] In the tenth aspect of the present invention, in the adjustment method of the illumination optical apparatus having the polarization setting unit that sets the polarization state of the light on the irradiated surface to a predetermined polarization state,

Obtaining information on at least a part of an optical system to be arranged in an optical path between the polarization setting unit and the irradiated surface;

Birefringence amount of an optical system disposed in an optical path between the polarization setting unit and the irradiated surface And a method for adjusting the illumination optical device, comprising:

[0019] In an eleventh aspect of the present invention, in the adjustment method of the illumination optical device having the polarization setting unit that sets the polarization state of the light on the irradiated surface to a predetermined polarization state,

Maintaining the polarization setting force in the optical path to the irradiated surface so that the polarization state of the light reaching the irradiated surface via the optical system becomes the predetermined polarization state; A method for adjusting an illumination optical device is provided.

[0020] In a twelfth aspect of the present invention, the illumination optical apparatus adjusted by the adjustment method according to the tenth or eleventh aspect is provided, and a mask pattern illuminated by the illumination optical apparatus is exposed to a photosensitive substrate. An exposure apparatus characterized by the above is provided.

In a thirteenth aspect of the present invention, an exposure method is characterized in that a pattern of a mask is exposed on a photosensitive substrate using the illumination optical device adjusted by the adjustment method of the tenth or eleventh aspect. I will provide a.

[0022] In a fourteenth aspect of the present invention, an exposure step of exposing a pattern of a mask onto a photosensitive substrate using the illumination optical device adjusted by the adjustment method of the tenth or eleventh embodiment, and the exposure step And a developing step of developing the exposed photosensitive substrate. A method of manufacturing a microdevice is provided.

The invention's effect

[0023] In the illumination optical device according to a typical embodiment of the present invention, the polarization setting unit for setting the polarization state of the light reaching the irradiated surface to a predetermined polarization state includes a light source, an irradiated surface, and the like. It is placed in the optical path between. In addition, each light transmitting member (lens, parallel flat plate, etc.) arranged in the optical path between the polarization setting unit and the irradiated surface can suppress the amount of birefringence generated due to internal distortion to 5 nmZcm or less. It is made of an optical material. As a result, in these light transmitting members, birefringence due to internal distortion is suppressed, and as a result, the polarization state of light passing through the birefringence is not adversely affected.

Thus, in the illumination optical device of the present invention, the change in the polarization state of light in the illumination optical path The surface to be irradiated can be illuminated with light having a desired polarization state. Therefore, in the exposure apparatus and exposure method of the present invention, a fine pattern is formed on the photosensitive substrate in the desired polarization state using an illumination optical device that illuminates the irradiated surface with light in the desired polarization state. The image can be imaged with high fidelity and good exposure can be performed, and thus a good microdevice can be manufactured.

Brief Description of Drawings

FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus that works on an embodiment of the present invention.

2 is a diagram schematically showing the configuration of the polarization conversion element in FIG. 1. FIG.

FIG. 3 is a diagram for explaining the optical rotation of quartz.

[4] It is a diagram schematically showing an annular secondary light source set in a circumferential polarization state by the action of the polarization conversion element.

FIG. 5 is a diagram schematically showing an internal configuration of a polarization measuring unit in FIG. 1.

FIG. 6 is a diagram for explaining a first verification example for verifying the effect of birefringence according to a rotationally symmetric secondary distribution with respect to the optical axis.

FIG. 7 is a diagram for explaining a second verification example for verifying the influence of birefringence according to a tilted linear distribution that linearly changes in the direction.

FIG. 8 is a diagram schematically showing a force acting on the light transmitting member from the outside and a stress distribution generated in the light transmitting member in the prior art.

FIG. 9 is a diagram schematically showing a force acting from the outside on the light transmission member and a stress distribution generated in the light transmission member in the present embodiment.

FIG. 10 is a diagram schematically showing a configuration of a holding member that supports a light transmitting member at three points on both sides with force in this embodiment.

FIG. 11 is a cross-sectional view showing a state in which a notch (processed portion) having a surface 62a orthogonal to the optical axis is formed on the entire peripheral portion outside the effective region of the light transmitting member.

FIG. 12 is a perspective view showing a state in which a notch (processed part) having a surface 62a orthogonal to the optical axis is formed on the entire peripheral part outside the effective region of the light transmitting member.

FIG. 13 is a flowchart showing each step of the method of manufacturing the illumination optical apparatus according to the present embodiment. FIG. 14 is a first diagram for illustrating an evaluation process in the manufacturing method of the present embodiment.

FIG. 15 is a second diagram for illustrating an evaluation process in the manufacturing method of the present embodiment.

FIG. 16 is a flowchart showing each step of another manufacturing method (adjustment method) of the illumination optical apparatus according to the present embodiment.

FIG. 17 is a flowchart of a method for obtaining a semiconductor device as a micro device.

FIG. 18 is a flowchart of a method for obtaining a liquid crystal display element as a micro device.

BEST MODE FOR CARRYING OUT THE INVENTION

[0026] An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In Fig. 1, the Z-axis along the normal direction of wafer W, which is the photosensitive substrate, the Y-axis in the direction parallel to the plane of Fig. 1 in the plane of wafer W, and Fig. 1 in the plane of wafer W. The X axis is set in the direction perpendicular to the page.

Referring to FIG. 1, the exposure apparatus of the present embodiment includes a light source 1 for supplying exposure light (illumination light). As the light source 1, for example, an ArF excimer laser light source that supplies light with a wavelength of 193 nm or a KrF excimer laser light source that supplies light with a wavelength of 248 nm can be used. A substantially parallel light beam emitted from the light source 1 is incident on the before power lens 5 through the relay lens system 2, the polarization state switching unit 3 (3a, 3b), and the diffractive optical element 4 for annular illumination. The configuration and operation of the polarization state switching unit 3 will be described later.

The relay lens system 2 has a function of converting a substantially parallel light beam from the light source 1 into a substantially parallel light beam having a predetermined rectangular cross section and guiding it to the polarization state switching unit 3. The focal lens 5 is an afocal lens that is set so that the front focal position thereof substantially coincides with the position of the diffractive optical element 4 and the rear focal position substantially coincides with the position of the predetermined plane 6 indicated by a broken line in the figure. System (non-focal optical system).

On the other hand, the diffractive optical element 4 is formed by forming a step having a pitch of about the wavelength of exposure light (illumination light) on the substrate, and has an action of diffracting the incident beam to a desired angle. To do. Specifically, the diffractive optical element 4 for annular illumination forms an annular light intensity distribution in the far field (or Fraunhofer diffraction region) when a parallel light flux having a rectangular cross section is incident. It has the function to do.

Accordingly, the substantially parallel light beam incident on the diffractive optical element 4 as the light beam conversion element forms a ring-shaped light intensity distribution on the pupil plane of the focal lens 5, and then has a ring-shaped angular distribution with a focal lens. Ejected from 5. In the optical path between the front lens group 5a and the rear lens group 5b of the afocal lens 5, a polarization conversion element 7 and a conical axicon system 8 are disposed at or near the pupil position. The configuration and operation of the polarization conversion element 7 and the conical axicon system 8 will be described later.

The light beam that has passed through the afocal lens 5 enters a micro fly's eye lens (or fly eye lens) 10 as an optical integrator through a zoom lens 9 for variable σ value. The micro fly's eye lens 10 is an optical element composed of a large number of microlenses having positive refracting power that are arranged vertically and horizontally and densely. In general, a micro fly's eye lens is configured by, for example, performing etching on a plane parallel plate to form a micro lens group.

Here, each micro lens constituting the micro fly's eye lens is smaller than each lens element constituting the fly eye lens. Further, unlike a fly-eye lens composed of lens elements isolated from each other, a micro fly-eye lens is integrally formed without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly's eye lens in that lens elements having positive refractive power are arranged vertically and horizontally.

The position of the predetermined surface 6 is disposed in the vicinity of the front focal position of the zoom lens 9, and the incident surface of the microfly lens 10 is disposed in the vicinity of the rear focal position of the zoom lens 9. In other words, the zoom lens 9 arranges the predetermined surface 6 and the entrance surface of the micro fly's eye lens 10 substantially in a Fourier transform relationship, and as a result, the pupil surface of the focal lens 5 and the entrance of the micro fly's eye lens 10. The surface is optically substantially conjugate.

Therefore, on the entrance surface of the micro fly's eye lens 10, for example, an annular illumination field centered on the optical axis ΑΧ is formed in the same manner as the pupil plane of the focal lens 5. This ring The overall illumination field shape changes in a similar manner depending on the focal length of the zoom lens 9, as will be described later. Each microlens constituting the micro fly's eye lens 10 is similar to the shape of the illumination field to be formed on the mask M (the shape of the exposure area to be formed on the wafer W). It has a rectangular cross section.

[0035] The light beam incident on the micro fly's eye lens 10 is two-dimensionally divided by a large number of microlenses, and an illumination field formed by the incident light beam is formed on the rear focal plane or in the vicinity thereof (and the illumination pupil plane). A secondary light source having substantially the same light intensity distribution, that is, a secondary light source such as a ring-shaped substantial surface light source centering on the optical axis AX is formed. The light beam from the secondary light source formed on the rear focal plane of the micro fly's eye lens 10 or in the vicinity thereof illuminates the mask blind 12 in a superimposed manner after passing through the condenser optical system 11.

Thus, a rectangular illumination field corresponding to the shape and focal length of each microlens constituting the micro fly's eye lens 10 is formed on the mask blind 12 as an illumination field stop. The light beam that has passed through the rectangular opening (light transmitting portion) of the mask blind 12 receives the light condensing action of the imaging optical system 13 and then illuminates the mask M on which a predetermined pattern is formed in a superimposed manner. That is, the imaging optical system 13 forms an image of the rectangular opening of the mask blind 12 on the mask M. A pair of bending mirrors Ml and M2 are disposed in the optical path of the imaging optical system 13.

[0037] The light beam that has passed through the pattern of the mask M held on the mask stage MS passes through the projection optical system PL, and the mask pattern on the wafer (photosensitive substrate) W held on the wafer stage WS. Form an image of In this way, the wafer stage WS is two-dimensionally driven and controlled in the plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, and consequently the wafer W is two-dimensionally driven and controlled for batch exposure or By performing the scanning exposure, the pattern of the mask M is sequentially exposed in each exposure region of the wafer W.

The polarization state switching unit 3 includes, in order from the light source side, a 1Z4 wavelength plate 3a and a half-wave plate 3b. The 1Z4 wavelength plate 3a is configured so that the crystal optical axis is rotatable about the optical axis AX, and converts incident elliptically polarized light into linearly polarized light. Further, the 1Z2 wave plate 3b is configured such that the crystal optical axis is rotatable about the optical axis AX, and changes the polarization plane (polarization direction) of incident linearly polarized light. The rotation of 1Z4 wave plate 3a and 1Z2 wave plate 3b Is performed by the drive unit 21 that operates based on a command from the control unit 20.

[0039] When a KrF excimer laser light source or an ArF excimer laser light source is used as the light source 1, the light emitted from these light source powers typically has a degree of polarization of 95% or more, and the 1Z4 wavelength plate 3a Nearly linearly polarized light is incident. However, when a right-angle prism as a back reflector is interposed in the optical path between the light source 1 and the polarization state switching unit 3, the polarization plane of the incident linearly polarized light is P-polarized or S-polarized with respect to the reflective surface. If they do not coincide with the plane, linearly polarized light changes to elliptically polarized light due to total reflection at a right angle prism.

[0040] In the polarization state switching unit 3, for example, even if elliptically polarized light is incident due to total reflection from a right-angle prism, the linearly polarized light converted by the action of the 1Z4 wavelength plate 3a is converted to the 1Z2 wavelength plate 3b. Is incident on. In the following, for simplicity of explanation, it is assumed that linearly polarized light (hereinafter referred to as “Y-direction polarized light”) having a polarization direction (electric field direction) in the Y direction in FIG. 1 is incident on the 1Z2 wavelength plate 3b. To do.

[0041] In this case, if the crystal optic axis of the 1Z2 wave plate 3b is set to make an angle of 0 degree or 90 degrees with respect to the polarization plane of the Z direction polarized light that is incident, the Z direction polarized light that is incident on the 1Z2 wave plate 3b The light passes through the polarization plane without changing the polarization plane, and enters the diffractive optical element 4 in the Z-direction polarization state. On the other hand, when the crystal optical axis of the 1Z2 wave plate 3b is set to form an angle of 45 degrees with respect to the polarization plane of the Z direction polarization incident on the 1Z2 wave plate 3b, the polarization plane of the Z direction polarization light incident on the 1Z2 wave plate 3b It changes by 90 degrees and becomes linearly polarized light (hereinafter referred to as “X direction polarized light”) having a polarization direction (electric field direction) in the X direction in FIG. 1 and enters the diffractive optical element 4 in the X direction polarization state. To do.

[0042] Generally, the polarization of incident light to the diffractive optical element 4 is set by setting the crystal optic axis of the 1Z2 wave plate 3b so as to make a required angle with respect to the polarization plane of the Z-direction polarization. The state can be set to a linear polarization state having a polarization direction in an arbitrary direction. Furthermore, in the polarization state switching unit 3, the 1Z2 wave plate 3b is retracted from the illumination optical path, and the crystal optical axis of the 1Z4 wave plate 3a is set to make a required angle with respect to the incident elliptically polarized light, thereby making a circle. Light in a polarization state or a desired elliptical polarization state can also be incident on the diffractive optical element 4. That is, in the state where the polarization conversion element 7 described later is retracted from the optical path, the polarization state of the light that illuminates the mask M and the wafer W is changed by the action of the polarization state switching unit 3. A linear polarization state having a polarization direction in an arbitrary direction, a circular polarization state, or a desired elliptical polarization state can be set.

[0043] Next, the conical axicon system 8 includes, in order, the light source side force with the first prism member 8a having a flat surface facing the light source and a concave conical refracting surface facing the mask, and a plane facing the mask side. And a second prism member 8b having a convex conical refracting surface facing the light source. The concave conical refracting surface of the first prism member 8a and the convex conical refracting surface of the second prism member 8b are complementarily formed so as to be in contact with each other. Further, at least one of the first prism member 8a and the second prism member 8b is configured to be movable along the optical axis AX, and the concave conical refracting surface of the first prism member 8a and the second prism are configured. The distance between the convex conical refracting surface of the member 8b is variable.

Here, when the concave conical refracting surface of the first prism member 8a and the convex conical bending surface of the second prism member 8b are in contact with each other, the conical axicon system 8 functions as a parallel flat plate However, there is no influence on the annular secondary light source formed. However, if the concave conical refracting surface of the first prism member 8a is separated from the convex conical refracting surface of the second prism member 8b, the width of the annular secondary light source (the outer diameter of the annular secondary light source and The outer diameter (inner diameter) of the annular secondary light source changes while keeping the difference 1Z2) from the inner diameter constant. That is, the annular ratio (inner diameter Z outer diameter) and size (outer diameter) of the annular secondary light source change.

[0045] The zoom lens 9 has a function of enlarging or reducing the entire shape of the annular secondary light source in a similar manner. For example, by expanding the focal length of the zoom lens 9 to a predetermined value with the minimum value force, the entire shape of the annular secondary light source is similarly enlarged. In other words, due to the action of the zoom lens 9, both the width and size (outer diameter) of the annular zone of the annular secondary light source change without change. In this way, the annular ratio and size (outer diameter) of the annular secondary light source can be controlled by the action of the conical axicon system 8 and the zoom lens 9.

It should be noted that quadrupole illumination can be performed by setting a diffractive optical element for quadrupole illumination (not shown) in the illumination optical path instead of the diffractive optical element 4 for annular illumination. The diffractive optical element for quadrupole illumination has a function of forming a quadrupole light intensity distribution in the far field when a parallel light beam having a rectangular cross section is incident. Therefore, for 4-pole lighting The light beam that passes through the diffractive optical element forms a quadrupole illumination field on the incident surface of the micro fly's eye lens 10 that also has, for example, four circular illumination fields around the optical axis AX. As a result, the same quadrupole secondary light source as the illumination field formed on the incident surface is formed at or near the rear focal plane of the micro fly's eye lens 10.

[0047] Also, instead of the diffractive optical element 4 for annular illumination, a diffractive optical element for circular illumination (not shown) is set in the illumination optical path, whereby normal circular illumination can be performed. The diffractive optical element for circular illumination has a function of forming a circular light intensity distribution in the far field when a parallel light beam having a rectangular cross section is incident. Therefore, the light beam that has passed through the diffractive optical element for circular illumination forms, for example, a circular illumination field around the optical axis AX on the incident surface of the micro fly's eye lens 10. As a result, a secondary light source having the same circular shape as the illumination field formed on the incident surface is also formed at or near the rear focal plane of the micro fly's eye lens 10.

[0048] Furthermore, instead of the diffractive optical element 4 for annular illumination, other diffractive optical elements (not shown) for multi-pole illumination are set in the illumination optical path, so that various multi-pole illuminations (2 Polar lighting, 8-pole lighting, etc.). Similarly, various forms of modified illumination can be performed by setting a diffractive optical element (not shown) having appropriate characteristics in the illumination optical path instead of the diffractive optical element 4 for annular illumination. it can.

FIG. 2 is a diagram schematically showing a configuration of the polarization conversion element of FIG. FIG. 3 is a diagram for explaining the optical rotation of quartz. FIG. 4 is a diagram schematically showing an annular secondary light source that is set in a circumferential polarization state by the action of the polarization conversion element. The polarization conversion element 7 according to the present embodiment is arranged at or near the pupil position of the focal lens 5, that is, at or near the pupil plane of the illumination optical device (1 to 13). Therefore, in the case of annular illumination, a light beam having a substantially annular cross section around the optical axis AX is incident on the polarization conversion element 7.

Referring to FIG. 2, the polarization conversion element 7 as a whole has a ring-shaped effective region centered on the optical axis AX, and this ring-shaped effective region is a circumference centered on the optical axis AX. It consists of eight fan-shaped basic elements equally divided in the direction. Among these eight basic elements, a pair of basic elements facing each other across the optical axis AX have the same characteristics. sand In other words, the eight basic elements include two types of four basic elements 7A to 7D that differ in thickness (length in the optical axis direction) along the light transmission direction (Y direction)! /, The

[0051] Specifically, the thickness of the fourth basic element 7D, where the thickness of the first basic element 7A is the largest, and the thickness of the second basic element 7B, where the thickness of the first basic element 7A is the smallest, is greater than the thickness of the third basic element 7C. It is set large. As a result, one surface (for example, the entrance surface) of the polarization conversion element 7 is planar, but the other surface (for example, the exit surface) is uneven due to the difference in thickness of the basic elements 7A to 7D. . In addition, both surfaces (incident surface and exit surface) of the polarization conversion element 7 are both formed in an uneven shape.

[0052] In the present embodiment, each of the basic elements 7A to 7D is composed of a water crystal that is an optical material having optical activity, and the crystal optical axis of each of the basic elements 7A to 7D is substantially coincident with the optical axis AX. Is set to Hereinafter, with reference to FIG. 3, the optical rotation of the crystal will be briefly described. Referring to FIG. 3, a plane-parallel plate-like optical member 100 made of quartz having a thickness d is arranged such that its crystal optical axis coincides with the optical axis AX. In this case, due to the optical rotation of the optical member 100, the incident linearly polarized light is emitted with the polarization direction rotated by Θ around the optical axis AX.

[0053] At this time, the rotation angle (rotation angle) Θ in the polarization direction due to the optical rotation of the optical member 100 is expressed by the following equation (1) according to the thickness d of the optical member 100 and the optical rotation power p of the crystal. .

Θ = d- p (1)

[0054] In general, the optical rotatory power p of crystal has a wavelength dependency (a property in which the value of the optical rotatory power varies depending on the wavelength of the used light: optical rotatory dispersion), and specifically increases as the wavelength of the used light becomes shorter. There is a tendency to become. According to the description on page 167 of “Applied Optics II”, the optical rotation power / 0 of quartz for light having a wavelength of 250.3 nm is 153.9 ° Zmm.

In this embodiment, the first basic element 7A, when linearly polarized light having a polarization direction in the Y direction is incident, is polarized in the direction obtained by rotating the Y direction by +180 degrees around the Z axis, that is, in the Y direction. The thickness dA is set to emit linearly polarized light having a direction. Therefore, in this case, of the annular secondary light source 31 shown in FIG. 4, the light beam passing through the pair of arcuate regions 31A formed by the light beam subjected to the optical rotation of the pair of first basic elements 7A. The polarization direction is the Y direction. [0056] When linearly polarized light having a polarization direction in the Y direction is incident on the second basic element 7B, the Y direction is rotated by +135 degrees around the Z axis, that is, the Y direction is around the Z axis. The thickness dB is set so as to emit linearly polarized light having a polarization direction in a direction rotated in degrees. Therefore, in this case, in the annular secondary light source 31 shown in FIG. 4, the polarization direction of the light beam passing through the pair of arc-shaped regions 31B formed by the light beam subjected to the optical rotation of the pair of second basic elements 7B Is the Y direction rotated around the Z axis by 45 degrees.

[0057] When linearly polarized light having a polarization direction in the Y direction is incident, the third basic element 7C is a linearly polarized light having a polarization direction in the X direction, that is, the Y direction rotated by +90 degrees around the Z axis. The thickness dC is set so as to emit light. Therefore, in this case, in the annular secondary light source 31 shown in FIG. 4, the polarization direction of the light beam passing through the pair of arcuate regions 31C formed by the light beam subjected to the optical rotation of the pair of third basic elements 7C. Is in the X direction.

[0058] When linearly polarized light having a polarization direction in the Y direction is incident, the fourth basic element 7D emits linearly polarized light having a polarization direction in a direction obtained by rotating the Y direction by +45 degrees around the Z axis. Thickness dD is set to inject. Therefore, in this case, of the annular secondary light source 31 shown in FIG. 4, the polarization direction of the light beam passing through the pair of arcuate regions 31D formed by the light beam subjected to the optical rotation of the pair of fourth basic elements 7D The direction is the Y direction rotated +45 degrees around the Z axis.

It is to be noted that the polarization conversion element 7 can be obtained by combining eight separately formed basic elements, or polarization can be achieved by forming a required concavo-convex shape (step) on a plane-parallel crystal substrate. The conversion element 7 can also be obtained. Further, in order to perform normal circular illumination without retracting the polarization conversion element 7 from the optical path, the effective area of the polarization conversion element 7 has a size of 1Z3 or more in the radial direction and an optical rotation. A circular central area 7E that does not have the property is provided. Here, the central region 7E may be formed of an optical material that does not have optical activity, such as quartz, or may be a simple circular opening. However, the central region 7E is not an essential element for the polarization conversion element 7.

FIG. 5 is a diagram schematically showing an internal configuration of the polarization measuring unit in FIG. 1. In the present embodiment, as shown in FIG. 5, a polarization measuring unit (polarization state measurement) for measuring the polarization state of illumination light (exposure light) with respect to the wafer W is provided on the wafer stage WS for holding the wafer W. Part) 1 4 is provided. The polarization measuring unit 14 includes a pinhole member 40 that can be two-dimensionally positioned at the height position of the exposure surface of the wafer W. When the polarization measuring unit 14 is used, the wafer W also retracts the optical path force.

The light that has passed through the pinhole 40a of the pinhole member 40 becomes a substantially parallel light beam through the collimator lens 41, is reflected by the reflecting mirror 42, and then enters the relay lens system 43. The almost parallel light beam through the relay lens system 43 reaches the detection surface 46a of the two-dimensional CCD 46 after passing through the λΖ4 plate 44 as a phase shifter and the polarization beam splitter 45 as a polarizer. The output of the two-dimensional CCD 46 is supplied to the control unit 20. Here, the λ Ζ4 plate 44 is configured to be rotatable around the optical axis, and a setting unit 47 for setting a rotation angle around the optical axis is connected to the λ Ζ4 plate 44. ing.

[0062] Thus, when the polarization degree of the illumination light with respect to Ueno and W is not 0, the λ / 4 plate 44 is rotated around the optical axis via the setting unit 47 so as to be detected on the detection surface 46a of the two-dimensional CCD 46. The light intensity distribution changes. Therefore, the polarization measuring unit 14 detects a change in the light intensity distribution on the detection surface 46a while rotating the λΖ4 plate 44 around the optical axis by using the setting unit 47, and from this detection result, the rotation phase shifter method is used for illumination. The polarization state of light (degree of polarization; Stokes parameters S 1, S 2, S 3 for light) can be determined.

one two Three

[0063] Note that the rotational phase shifter method is described in detail in, for example, Tsuruta, "Applied Optics for Optical Pencil Ikko Engineers", New Technology Communications Co., Ltd., and the like. In practice, the polarization state of the illumination light at a plurality of positions in the wafer surface is measured while the pinhole member 40 (and thus the pinhole 40a) is moved two-dimensionally along the wafer surface. At this time, since the polarization measurement unit 14 detects a change in the light intensity distribution on the two-dimensional detection surface 46a, the polarization state distribution in the pupil of the illumination light is measured based on the detection distribution information. Can do.

By the way, in the polarization measuring unit 14, it is possible to use a λλ2 plate instead of the λΖ4 plate 44 as a phase shifter. Whatever phase shifter is used, the relative angle around the optical axis between the phase shifter and the polarizer (polarized beam splitter 45) can be used to measure the polarization state, ie, the four status parameters. Change the light intensity distribution on the detection surface 46a in at least four different states by changing the phase difference or retracting the optical path force of the phase shifter or polarizer. There is a need.

In this embodiment, the λ Ζ4 plate 44 as the phase shifter is rotated around the optical axis, but the phase shift that allows the polarization beam splitter 45 as the polarizer to be rotated around the optical axis is also acceptable. Both the polarizer and the polarizer may be rotated around the optical axis. Further, in place of or in place of this operation, one or both of the λ 4 plate 44 serving as a phase shifter and the polarization beam splitter 45 serving as a polarizer may be removed from the optical path. .

[0066] In the polarization measuring unit 14, the polarization state of the light may change depending on the polarization characteristics of the reflecting mirror 42. In this case, since the polarization characteristics of the reflecting mirror 42 are previously determined, the measurement result of the polarization measuring unit 14 is corrected based on the influence of the polarization characteristics of the reflecting mirror 42 on the polarization state by the required calculation, and the illumination light It is possible to accurately measure the polarization state. Further, even when the polarization state changes due to other optical components such as a lens as well as the reflecting mirror, the measurement result can be similarly corrected to accurately measure the polarization state of the illumination light.

[0067] In this way, the polarization state (polarization degree) of the illumination light with respect to the wafer W in the pupil is measured using the polarization measuring unit 14, and the illumination light is in an appropriate polarization state (for example, the above-described circumferential polarization state). Etc.) is determined. Then, the control unit 20 drives the polarization state switching unit 3 (1Z4 wavelength plate 3a and 1Z2 wavelength plate 3b) as necessary based on the measurement result of the polarization measuring unit 14, and mask M (and thus the wafer W). ) Is adjusted to a desired polarization state.

[0068] In the present embodiment, the 1Z2 wavelength plate 3b in the polarization state switching unit 3 in the circumferential polarization annular illumination (modified illumination in which the light beam passing through the annular secondary light source is set in the circumferential polarization state). By adjusting the angular position of the crystal optical axis around the optical axis and making Y direction polarized light incident on the diffractive optical element 4 for annular illumination, linearly polarized light having a polarization direction in the Y direction is converted into a polarization converting element 7 To enter. As a result, an annular secondary light source (annular illumination pupil distribution) 31 is formed at or near the rear focal plane of the micro fly's eye lens 10, as shown in FIG. The light beam passing through the next light source 31 is set to the circumferential polarization state.

[0069] In the circumferential polarization state, the luminous fluxes respectively passing through the arc-shaped regions 31A to 31D constituting the annular secondary light source 31 are centered along the circumferential direction of each of the arc-shaped regions 31A to 31D. A linear polarization state having a polarization direction almost coincident with the tangential direction of the circle centered on the optical axis AX in the installation is obtained. Thus, in the present embodiment, the annular secondary light source 31 in the circumferentially polarized state is formed by the optical rotation action of the polarization conversion element 7 without substantially generating a light amount loss. In addition, in circumferentially polarized annular illumination based on the annular illumination pupil distribution in the circumferentially polarized state, the light irradiated on the wafer W as the final irradiated surface changes to a polarized state mainly composed of S-polarized light. Become.

Here, the S-polarized light is linearly polarized light having a polarization direction in a direction perpendicular to the incident surface (polarized light whose electric vector is oscillating in a direction perpendicular to the incident surface). However, the incident surface is defined as a surface that includes the normal of the boundary surface at that point and the incident direction of light when the light reaches the boundary surface of the medium (irradiated surface: the surface of the wafer W). The As a result, optical performance (depth of focus, etc.) of the projection optical system is improved with circumferentially polarized annular illumination, and a high-contrast mask pattern image can be obtained on the wafer (photosensitive substrate).

[0071] Generally, even in illumination based on, for example, a multipolar illumination pupil distribution in a circumferentially polarized state, which is not limited to annular illumination, the light incident on the wafer W has a polarization state mainly composed of S-polarized light. Thus, a good mask pattern image with high contrast can be obtained on Ueno and W. At this time, instead of the diffractive optical element 4 for annular illumination, a diffractive optical element for multipole illumination (two-pole illumination, four-pole illumination, eight-pole illumination, etc.) is set as the illumination optical path, and the polarization state switching unit 3 By adjusting the angular position of the 1Z2 wave plate 3b around the optical axis of the 1Z2 wave plate 3b and making the Y-direction polarized light incident on the diffractive optical element for multipole illumination, linearly polarized light having the polarization direction in the Y-direction can be obtained. Light is incident on the polarization conversion element 7.

As described above, based on the light supplied from the light source 1! /, The illumination optical device (1 to 13) of the present embodiment that illuminates the mask M as the irradiated surface includes the light source 1 and Polarization state switching unit 3 (3a, 3b) and polarization conversion element as a polarization setting unit for setting the polarization state of the light that reaches the mask M and is arranged in the optical path between the mask M and the predetermined polarization state 7 is provided. However, even if the mask M (and thus the wafer W) is to be illuminated with light of a desired polarization state by the action of the polarization state switching unit 3 and the polarization conversion element 7, for example, the polarization of the light in the illumination light path If an optical element that changes the state is interposed, an image is not formed in a desired polarization state, and there is a possibility that the imaging performance is deteriorated. In particular, light transmission placed in the illumination light path In a member (such as a lens or a plane-parallel plate), the polarization state of light passing through it changes due to birefringence caused by internal distortion.

Hereinafter, based on a typical design example, for example, the influence of birefringence caused by internal distortion will be verified. First, in the first verification example, any one of all the light transmitting members (lenses, parallel plane plates, etc.) arranged in the optical path between the polarization state switching unit 3 and the mask M is selected. Light-transmitting member force The case of birefringence following a rotationally symmetric secondary distribution with respect to the optical axis AX is assumed. More specifically, as shown in Fig. 6 (a), the birefringence distribution has a birefringence amount OnmZcm at the center of the effective region (optical axis AX), and a birefringence amount around the effective region is lOnmZcm. The distribution is assumed to increase monotonically according to a quadratic function from the center to the periphery of the effective region. Here, the amount of birefringence is a phase difference generated between P-polarized light and S-polarized light when only lcm is transmitted through the light transmitting member. Also, here, the fast axis and slow axis are radial or concentric tangential to the center of the light transmissive member, and the birefringence increases monotonically as a quadratic function as it moves from the center to the periphery. The distribution to be added is assumed.

[0074] In this case, the center CR of the exposure region ER on the wafer W (that is, the optical axis AX: Fig. 6 (c)), regardless of which light transmissive member has birefringence according to the rotationally symmetric secondary distribution described above. The light reaching (see below) is not affected by birefringence at all. However, the light reaching the peripheral position P1 farthest in the X direction from the center CR of the exposure area ER, for example, a position other than the center CR of the exposure area ER, has the above-mentioned rotationally symmetric secondary distribution. Therefore, the degree of birefringence influence is different depending on which light transmitting member has birefringence.

[0075] Specifically, of the light reaching the peripheral position P1 of the exposure region ER, the light having a polarization direction in the X direction at the position where the polarization conversion element 7 is disposed or in the vicinity of the pupil position (see FIG. 6B). And circles A and B), that is, the stochastic parameter S-force ^ at the pupil position.

1 Focusing on the light, the stochastic parameter S when reaching the peripheral position P1 of the exposure area ER

The value of 1 was found to vary between approximately 0.991 and 1.0 depending on which light transmissive member has birefringence according to the rotationally symmetric quadratic distribution described above.

[0076] On the other hand, of the light reaching the peripheral position P1 of the exposure region ER, it is polarized in a direction rotated by -45 degrees around the Z axis in the X direction at the position where the polarization conversion element 7 is disposed or in the vicinity of the pupil position. Focusing on light having a direction (indicated by circles C and D in FIG. 6 (b)), that is, light having a stochastic parameter S of 1 at the pupil position, it reaches the peripheral position P1 of the exposure region ER.

2

The value of the stochastic parameter S when

2

It has been found that depending on which light transmissive member the refraction is present, it varies between about 0.92 and L0.

[0077] Next, in the second verification example, one arbitrary light transmission member among all the light transmission members arranged in the optical path between the polarization state switching unit 3 and the mask M is: It is assumed that there is a birefringence following a gradient distribution that varies linearly along one direction. More specifically, as shown in FIG. 7 (a), the birefringence distribution has a birefringence force SOnmZcm at one periphery of the effective region and a birefringence amount lOnmZcm at the other periphery of the effective region. A distribution is assumed that increases monotonically along the X direction from one periphery to the other. Here, it is assumed that the fast axis and the slow axis are parallel or perpendicular to the inclination direction of the birefringence.

In this case, light having a polarization direction in the X direction (indicated by circles A and B in FIG. 7B) and polarized in the Y direction over the position where the polarization conversion element 7 is disposed or in the vicinity of the pupil position. Light having a direction (indicated by circles E and F in FIG. 7 (b)), that is, light having a stochastic parameter S of 1 at the pupil position, has a birefringence according to the above-described inclined first-order distribution.

1

Even if it exists in the material, it is not affected by birefringence at all as long as it reaches the area on the X axis and the area on the Y axis of the exposure area ER on the wafer W.

[0079] However, for example, at the position where the polarization conversion element 7 is arranged or in the vicinity of the pupil position, the light having the polarization direction in the direction rotated about 45 degrees around the Z axis by 45 degrees (see Fig. 7 (b)). (Indicated by circles C and D), that is, the light with the stochastic parameter S force ^ at the pupil position

2

Is the above-mentioned gradient primary distribution when it reaches the center CR of the exposure area ER on the wafer W (that is, the optical axis AX: see Fig. 7 (c)) or the peripheral position P1 farthest from the center CR in the X direction The degree of influence of birefringence varies depending on which light transmitting member has birefringence.

[0080] Specifically, the light C having the stochastic parameter S-force ^ at the pupil position is in the exposure area ER.

2

When the center CR is reached, the value of the stochastic parameter S follows the sloped linear distribution described above. It was found that depending on which light-transmitting member birefringence is present, it varies between about 0.77 and L0. In addition, light D with a stochastic parameter S of 1 at the pupil position is exposed.

2

When reaching the center CR of the region ER, the value of the stochastic parameter S is inclined as described above.

2 It was found that the birefringence according to the first-order distribution varies between about 0.65 and L 0 depending on which light transmitting member exists.

[0081] On the other hand, light C with the stochastic parameter S-force ^ at the pupil position is around the exposure area ER.

2

When the position P1 is reached, the value of the stochastic parameter S follows the sloped linear distribution described above.

2

It was found that the birefringence varies between about 0.83 and L0 depending on which light transmitting member exists. In addition, light D, which is the stochastic parameter S force ^ at the pupil position, is

2

When the peripheral position P1 of the area ER is reached, the value of the status parameter S is

2

Depending on which light transmissive member has birefringence according to the distribution, it was found that it varied between about 0.88 and L0.

[0082] From the results of the two verification examples described above, the birefringence of the light transmission member in the optical path between the polarization state switching unit 3 and the mask M follows, for example, a rotationally symmetric secondary distribution due to internal distortion. It can be seen that the effect of this rotationally symmetric second-order birefringence on the polarization state of the light reaching the mask M (and hence the wafer W) is considerable. In addition, when birefringence occurs in the light transmission member in the optical path between the polarization state switching unit 3 and the mask M, for example, due to internal distortion, according to the tilted linear distribution, the birefringence of the tilted primary distribution is reduced. It can be seen that the effect on the polarization state of the light reaching the mask M (H !, wafer W) is very large.

Therefore, in the present embodiment, as a first method, each light transmitting member arranged in the optical path between the polarization state switching unit 3 and the mask M in the polarization setting unit (3, 7) is used. The birefringence generated due to internal strain is made of an optical material that is suppressed to 5 nmZcm or less. With this configuration, the change in the polarization state of light in the illumination optical path can be suppressed satisfactorily, and the mask M can be illuminated with light having a desired polarization state. It is possible to form an image in a polarized state and perform a faithful and good exposure.

Similarly, in the exposure apparatus, the light source 1 to the projection optical system PL are considered as an illumination optical apparatus, and are arranged in the optical path between the polarization state switching unit 3 in the polarization setting unit (3, 7) and the wafer W. Each The light transmitting member is made of an optical material in which the amount of birefringence generated due to internal strain is suppressed to 5 nmZcm or less. With this configuration, the change in the polarization state of the light in the illumination optical path can be suppressed satisfactorily, and the wafer W can be illuminated with light in the desired polarization state. As a result, a fine pattern can be illuminated on the wafer W in the desired polarization state. The image can be imaged and faithful and good exposure can be performed.

By the way, in the above description, attention is paid to the influence of birefringence caused by internal strain. A relatively large stress is applied from the outside when holding the light transmitting member, and a complex stress generated according to the external stress is applied. The polarization state of the light passing through the light transmitting member changes due to refraction. Therefore, in the present embodiment, as a second method, each light transmitting member disposed in the optical path between the polarization state switching unit 3 in the polarization setting unit (3, 7) and the mask M (or wafer W). Is maintained so that the amount of birefringence generated due to external stress is suppressed to 5 nmZcm or less. With this configuration, it is possible to illuminate the mask M (or wafer W) with light of a desired polarization state while suppressing a change in the polarization state of the light in the illumination optical path, and thus a fine pattern on the wafer W. It is possible to form an image in a desired polarization state and perform a faithful and good exposure.

Specifically, in the prior art, the light transmitting member disposed in the illumination light path is generally held in a form that is sandwiched from both sides by a cylindrical spacing ring in the lens barrel. In this case, in principle, the light transmission member is continuously supported along an annular region centered on the optical axis. However, in reality, the light transmitting member is not continuously supported along the annular region due to the manufacturing error of the end face of the spacing ring (surface that contacts the light transmitting member). In addition, it is supported by a plurality of point regions (especially intended regions).

That is, in the prior art, as shown in FIG. 8 (a), the position of the main force F1 acting on one optical surface side of the light transmitting member 50 and the other optical of the light transmitting member 50 The position of the main force F2 acting on the surface side from the outside does not match. As a result, as indicated by contour lines in FIG. 8 (b), a relatively large stress distribution is generated over almost the entire effective region 50a of the light transmitting member 50 in response to external forces F1 and F2. The polarization state of the light passing through the light transmitting member 50 changes due to the birefringence generated according to this stress distribution. On the other hand, in the present embodiment, as shown in FIG. 9 (a), the one optical surface side of the light transmitting member 50 is supported at three points by the three regions 51a to 51c, and the light transmitting member 50 is used. The other optical surface side is supported at three points by three regions 52a to 52c substantially opposite to the three regions 51a to 51c. In this case, the position of the three forces F3 acting on the one optical surface side of the light transmitting member 50 from the outside and the position of the three forces F4 acting on the other optical surface side of the light transmitting member 50 from the outside are provided. Almost matches.

Accordingly, as shown by contour lines in FIG. 9 (b), the light transmitting member 50 is concentrated on the support regions 51 & ˜51 ₍ 52 & ˜52 ₍ :)) in response to the external forces F3 and F4. As a result of the stress distribution, there is no substantial stress distribution in the effective region 50a, and as a result, the light transmission member supported at three points in the substantially opposite regions according to the present embodiment is affected by the stress distribution. Almost no birefringence occurs, and hence the polarization state of light passing through the birefringence hardly changes.

FIG. 10 is a diagram schematically showing a configuration of a holding member that supports the light transmitting member from three sides in this embodiment. The holding member according to the present embodiment is for supporting three points on one optical surface side (the upper side in FIG. 10) of the light transmitting member 60 to be held in three regions (corresponding to 51a to 51c in FIG. 9). The first spacing ring 71 having two support portions 71a to 71c and the other optical surface side (the lower side in FIG. 10) of the light transmitting member 60 are divided into three areas (corresponding to 52a to 52c in FIG. 9). And a second spacing ring 72 having three support portions 72a to 72c for supporting.

Here, the three support portions 71a to 71c of the first interval ring 71 are provided at substantially equal angular intervals, and the three support portions 72a to 72c of the second interval ring 72 are also provided at approximately equal angular intervals. Yes. Further, the first spacing ring 71 and the second spacing ring 72 are such that the support portion 71a and the support portion 72a are substantially opposed to each other, and consequently the support portions 71b and 71c and the support portions 72b and 72c are substantially opposite to each other. So that it is positioned. In this way, the light transmitting member 60 is supported by the holding force (71, 72) at three points on both sides in almost three regions facing each other.

As described above, in the illumination optical device (1-13) of the present embodiment, a required light transmitting member (generally at least one light transmitting member) among the light transmitting members arranged in the optical path. ) Is supported at three points from both sides in almost opposite areas. In this case, only a stress distribution concentrated on the support area of the light transmission member is generated, and the effective area of the light transmission member is substantially not increased. Stress distribution does not occur. As a result, almost no birefringence due to the stress distribution occurs, and as a result, the polarization state of the light passing therethrough hardly changes due to the birefringence.

Thus, in the illumination optical device (1 to 13) of this embodiment, the change of the polarization state of the light in the optical path is satisfactorily suppressed, and the surface to be irradiated is irradiated with light in a desired polarization state or non-polarization state. All masks M (and thus wafer W) can be illuminated. Therefore, in the exposure apparatus according to the present embodiment, the illumination optical apparatus (1 to 13) that illuminates the mask M as the irradiated surface with light in a desired polarization state or non-polarization state, and a desired pattern according to the mask pattern. A fine pattern can be faithfully transferred onto a wafer (photosensitive substrate) W based on illumination conditions.

By the way, in the above-described embodiment, the light transmitting member arranged in the optical path between the micro fly's eye lens 10 as the optical integrator and the mask M as the irradiated surface is easily increased in size in the radial direction. When the force is applied, the polarization state of the light passing therethrough is likely to change due to the birefringence. Therefore, in order to satisfactorily suppress the change in the polarization state of the light in the optical path, among the light transmitting members disposed in the optical path between the micro fly's eye lens 10 as the optical integrator and the mask M as the irradiated surface, It is preferable that a relatively large light transmitting member in the radial direction is supported at three points by the holding member.

Further, in the above-described embodiment, as shown in FIG. 10, the light transmitting member 61 adjacent to the light transmitting member 60 is arranged at three points from both sides in three regions that are substantially opposed by the holding members (72, 73). When supporting, the three-point support position of the light transmitting member 60 by the holding member (71, 72) and the three-point support position of the light transmitting member 61 by the holding member (72, 73) may be displaced around the optical axis. It is preferable. With this configuration, it is possible to disperse the influence of the three-point support of a plurality of light transmitting members in the angular direction around the optical axis, and thus it is possible to satisfactorily suppress changes in the polarization state of light in the optical path. . This point is generally the same for a plurality of light transmitting members without being limited between adjacent light transmitting members.

As described above, in the above-described embodiment, in order to satisfactorily suppress the change in the polarization state of light in the optical path, in the state where the light is supported by the holding member at the three points, the light transmission member in the effective region is duplicated. The amount of refraction should be 5nmZcm or less. Furthermore, Fig. 11 and Fig. 1 As shown in FIG. 2, instead of the light transmissive member (60, 61), a light transmissive member in which a notch (processed portion) having a surface 62a orthogonal to the optical axis AX is formed on the entire periphery outside the effective region. It is preferable to use 62. Thus, as shown in FIG. 10, instead of the light transmissive members (60, 61), two light transmissive members having notches (processed portions) formed like the light transmissive member 62 are supported at three points. Thereby, the external stress resulting from holding | maintenance can be suppressed further.

[0097] In order to reduce stress due to holding, the support portion of the optical member such as a light transmitting member that comes into contact with the metal member such as the support member adds a flat portion perpendicular to the optical axis AX to the peripheral portion of the optical member. The optical member is not limited to that described above, and at least one surface of the optical member may be a flat surface. In addition, when the optical member is subjected to stress by the support member at the processed flat part, the example of the three-point support has been shown above as a support form that does not shift in the radial direction or the rotation direction. Any support configuration can be used as long as it can be used without any deviation in the radial direction and the rotational direction.

[0098] Further, when the support is performed, the strain of the optical member in the vicinity of the support portion is measured with a strain measuring instrument or the like, and based on the measured strain, the amount of birefringence generated by the stress is 5 nmZcm or less (more preferably It is more desirable to carry out the process of adjusting the torque and spring constant of the pressed metal so that the pressure is 2 nmZcm or less. Furthermore, as shown in FIGS. 11 and 12, if a notch having a surface 62a orthogonal to the optical axis AX is formed at a location (peripheral edge) 3 mm or more away from the effective area of the light transmitting member 62, In addition, the external stress caused by holding the light transmitting member 62 can be further reliably reduced.

[0099] In the first method, it is preferable to form each light transmitting member using an optical material in which the amount of birefringence generated due to internal strain is suppressed to 2 nmZcm or less. In the second method, it is preferable to hold each light transmitting member so that the amount of birefringence generated due to external stress is suppressed to 2 nmZcm or less. In this case, the change in the polarization state of the light in the illumination optical path can be further suppressed, and as a result, the fine pattern can be imaged on the wafer W in the desired polarization state, so that more faithful and better exposure can be performed. Furthermore, a synergistic effect can be expected by combining the first and second methods.

[0100] In the above description, while focusing on the influence of birefringence generated by internal strain and external stress, the pair of folding mirrors M1 disposed in the optical path of the imaging optical system 13 and In M2, a light beam is incident over a relatively wide incident angle range, so that a phase difference (P—S phase difference) caused by reflection occurs between P-polarized light and S-polarized light. The polarization state of the passing light changes. Therefore, in the present embodiment, as a third method, a phase difference generated by reflection between the light incident on the reflective film with P-polarized light and the light incident with S-polarized light is all the rays incident on the reflective film. Folding mirrors Ml and M2 are formed to be within 15 degrees.

[0101] With this configuration, the change in the polarization state of the light in the illumination optical path including these bending mirrors Ml and M2 is satisfactorily suppressed, and the mask M (or woofer W) is illuminated with light in the desired polarization state. As a result, a fine pattern can be imaged on the wafer W in a desired polarization state, and faithful and satisfactory exposure can be performed. In the third method, it is preferable to suppress the phase difference generated by reflection between P-polarized light and S-polarized light within 10 degrees. In this case, the change in the polarization state of the light in the bending mirrors Ml and M2 is further suppressed, and as a result, a fine pattern is imaged on the wafer W in the desired polarization state, thereby performing more loyal and better exposure. be able to.

[0102] By the way, when birefringence occurs in a plurality of light transmission members due to, for example, a rotationally asymmetric distribution (typically a gradient distribution) due to internal strain, the combination of the birefringence distributions in these light transmission members The polarization state in the field (the polarization state in the pupil plane for each position in the exposure area ER on the wafer W) becomes substantially non-uniform, or the polarization state in the pupil plane is a desired polarization state (for example, Or change from a circumferentially polarized state) to a substantially different state. The polarization state in the field becomes substantially non-uniform (for example, the polarization state in the pupil plane for light reaching the center of the exposure area ER and the polarization state in the pupil plane for light reaching the periphery of the exposure area ER are substantially different. The line width of the pattern formed on the wafer W varies from position to position in the exposure region ER, so that a so-called field width difference is generated.

[0103] Further, when the polarization state in the pupil plane changes from a desired polarization state to a substantially different state, for example, a pattern extending elongated along the vertical direction on the wafer W and a pattern extending elongated along the horizontal direction. The line width varies between the so-called VH line width differences. Therefore, in this embodiment, as a fourth method, the polarization in the polarization setting unit (3, 7) is set. In order to reduce the effect of birefringence caused by internal distortion in each light transmitting member arranged in the optical path between the optical state switching unit 3 and the mask M (or wafer W) by canceling, Each light transmitting member is positioned at a required rotational angle position about the axis AX.

[0104] With this configuration, it is possible to illuminate the mask M (or wafer W) with light in a desired polarization state while suppressing a change in the polarization state of light in the illumination optical path, and in turn, to apply a fine pattern to the wafer. It is possible to form an image with a desired polarization state on W and to perform a faithful and good exposure. More specifically, the above-mentioned clocking method is used to adjust the polarization state in the field to be almost uniform, thereby suppressing the occurrence of the line width difference in the field, and the polarization state in the pupil plane to the desired polarization state. It is possible to suppress the occurrence of the VH line width difference by adjusting the distance closer to.

[0105] The first to fourth methods described above may be applied independently, or two or more methods may be applied in an appropriate combination. Hereinafter, a method for manufacturing the illumination optical apparatus according to the present embodiment will be described. FIG. 13 is a flowchart showing each step of the method for manufacturing the illumination optical apparatus according to the present embodiment. Referring to FIG. 13, in the manufacturing method of the present embodiment, an ingot having an optical material force such as quartz is manufactured (Sl). Specifically, for the ingot of quartz force, for example, the force obtained by using the soot method or the direct method, the details can be referred to International Publication WO00Z41226.

[0106] Next, the ingot obtained in the manufacturing step S1 is cut (cut out) to prepare a bulk material for forming each light transmitting member in the illumination optical device (S2). Here, the “balta material” is a concept including a material cut out from an ingot and a material processed to some extent according to the size and shape of the corresponding light transmitting member. Specifically, when the light transmitting member to be formed is a lens, it is preferable that the bulk material has a thin cylindrical shape. The diameter and thickness of the cylindrical material (ie, disk material) of the cylindrical shape is preferable. It is desirable that it is determined according to the effective diameter (outer diameter) of the lens and the thickness in the optical axis direction. In preparation step S 2, annealing is performed on the bulk material cut out from the ingot as necessary.

Next, the birefringence amount of each Baltha material obtained in the preparation step S2 is measured (S3). concrete In addition, in measurement step S3, the fast axis direction and birefringence amount of each bulk material (the amount of phase difference generated between P-polarized light and S-polarized light due to internal distortion when transmitted through a unit distance) are measured. Measure the distribution. For the measurement of the fast axis direction and birefringence amount of the bulk material, for example, International Publications WO00Z41226 and WO03Z007045 can be referred to.

Next, a combination of a light transmissive member and a bulk material for constituting one illumination optical device is assumed (S4). Specifically, in the combination assumption process S4, a set (combination) of bulk materials to be used to configure the illumination optical device is initially selected, and the rotation angle position of each bulk material around the optical axis in this set is determined. Determine early. In the assumed combination process S4, the force that would result in multiple sets of bulk materials. In the following explanation, we focus on one set of bulk materials.

Thus, in the manufacturing method of the present embodiment, the change in the polarization state of light in the illumination optical path is suppressed within a desired range when the set of bulk materials initially assumed in the combination assumption step S4 is used. It is evaluated by simulation whether or not it is possible (S5). Specifically, in the evaluation step S5, for example, data (curvature radius, center thickness, air gap, refractive index, etc.) of each lens (generally a light transmitting member), incident angle of the reflecting film of the bending mirror (Ml, M2) Referring to the design value (or measurement value) of P—S phase difference and the measurement results of each bulk material obtained in measurement step S3 (phase axis orientation, birefringence distribution), The change in the polarization state of light is calculated.

[0110] By the way, as a method of describing the polarization state, the stochastic parameters (S, S, S, S) are

0 1 2 3 Can be used. Where S is the total light intensity (I +1) and S is the horizontal and vertical polarization

0 0 ° 90 ° 1

Intensity difference (I I), S is the intensity difference (I I) between 45 ° polarized light and 135 ° polarized light, S is clockwise

0 ° 90 ° 2 45 ° 135 ° 3 Defined as the intensity difference (I I) between polarized and left-handed polarized light. In addition, S is normalized to 1 right turn left turn 0

You can use the normalized Stokes parameter (S

1,, S

2, S,). Where s

3 1, 2 s

1 Z s

0 s 2, = s 2 Zs,

0 s 3 = s 3 Zs.

0

[0111] In the evaluation step S5, as shown in FIG. 14 (a), a light beam is incident on a rectangular lattice point of the entrance pupil of the optical system. At this time, as shown in Fig. 14 (b), when all incident rays are laterally polarized, the normalized stochastic parameters (S ', S', S ') = (1, 0, 0) . Evaluation process S5 Then, by trying to track the polarized light, the incident light to the entrance pupil is affected by the birefringence due to the internal distortion of the light transmitting member and the P—S phase difference of the reflecting film of the bending mirror (Ml, M2). The force that changes the polarization state is calculated.

Thus, a polarization map of the exit pupil is obtained corresponding to the rectangular lattice point of the entrance pupil, as shown in FIG. 14 (c). Specifically, for each ray at the rectangular grid point of the entrance pupil, the incident polarization state (S, S, S,) = (1, 0, 0) to the exit polarization state (S ", S", S " ) Is obtained.

1 2 3 1 2 3

In step S5, the incident lateral polarization component S ′ = S (in), the exit lateral polarization component S ″ = S (out), and S (ou

1 1

t) / S (in) = S VS '≥0.8, the change in the polarization state of the light in the illumination path

1 1

Evaluated as being within the desired range.

[0113] As shown in Fig. 14 (d), S (out) / S (in) = S VS is also applied when vertically polarized light is incident on the rectangular lattice point of the entrance pupil of the optical system. If ≥0.8, in the illumination light path

1 1

It is evaluated that the change in the polarization state of light is suppressed within a desired range. As described above, in order to improve the imaging performance of the projection optical system having a high numerical aperture, it is effective to use the circumferentially polarized state. Therefore, in the evaluation step S5, as shown in FIG. 15 (a), even if the entrance pupil is divided into four parts and light beams having different polarization directions are incident on each pupil division region so as to be in the circumferential polarization state as a whole. Good. However, in Fig. 15 (a), some of the rectangular grid points are omitted for simplicity of explanation.

[0114] In this case, laterally polarized light is incident on pupil division regions A and B, and longitudinally polarized light is incident on pupil division regions C and D. Therefore, the standardized stochastic parameters (S,, S,, S,) of the incident light are (1, 0, 0) in regions A and B, and in regions C and D (

one two Three

1, 0, 0). Then, in the ideal state where the polarization state of the incident light is completely maintained, the standardized status parameters (S ", S", S ") of the outgoing light corresponding to the regions A and B

one two Three

= (1, 0, 0), and the normalized stochastic parameters (S ", S", S ") = (-1, 0, 0) of the outgoing rays corresponding to regions C and D. In this case, S (out) ZS (in

one two Three

) = S VS '≥0.8, the desired change in the polarization state of the light in the illumination path

1 1

Evaluated as being within the range.

[0115] Similarly, as shown in FIG. 15 (b), the entrance pupil may be divided into eight, and light beams having different polarization directions may be incident on each pupil division region so as to be in a circumferential polarization state as a whole. . However, Figure 1 In FIG. 5 (b), part of the rectangular lattice points is omitted for the sake of simplicity. In this case, the incident light normalization status parameters (S, S, S, S)

one two Three

Is (1, 0, 0), pupil division regions C and D are (one 1, 0, 0), pupil division regions E and F are (0, 1, 0), and pupil division region G And for H and (0,-1, 0).

[0116] Then, in an ideal state where the polarization state of the incident light beam is completely maintained, the normalized light emission status parameters (S ", S", S ") = (1, 0, 0)

one two Three

, The normalized ray-stamp parameters (S ", S", S "

one two Three

) = (−1, 0, 0), and the standardized stochastic parameters (S “, S“, S “) = (0, 1, 0) of the exit rays corresponding to regions E and F Emission ray criteria for G and H

one two Three

匕 Stokes parameters (S ", S", S ") = (0,-1, 0).

one two Three

Corresponding to S (out) ZS (in) 2 S "ZS, ≥0.8, corresponding to region E ~ H, S (out) ZS (in

1 1

) = S Change in the polarization state of light in the illumination light path is desired.

2 If VS '≥0.8, then

2

Evaluated as being within the range.

In the above description, a polarization index (evaluation index) is determined for each ray map of the entrance pupil, and an optimization criterion is shown. In an actual illumination optical device, the secondary light source has a circular shape, an annular shape, a quadrupole shape, etc., and has an area in the entrance pupil plane. Therefore, in the evaluation step S5, the optimization criterion is that the average value of the polarization index S (out) ZSGn) of the light rays contained in the aperture of each secondary light source is 0.8 or more. In the above description, the polarization state of the intra-pupil ray map for one point in the illumination area is described, but the average value of the polarization index S (out) ZSGn) is 0.8 or more over the entire illumination area. Is the standard for optimization.

[0118] Further, in the evaluation step S5, the optimization criterion is that the variation width of the average value of the polarization index S ( _0Ut ) ZS (in) for each point in the illumination region is 0.05 or less. Note that the evaluation step S5 described above is for the partial optical system between the mask blind 12 and the mask M for simplicity. This is also the force that this partial optical system has a bending mirror (Ml, M2) and a lens with a large diameter that cannot ignore the influence of internal distortion.

[0119] As described above, in the evaluation step S5, the bulk material set initially selected in the combination assumption step S4 is cast on each light transmitting member and is initially set to the rotation angle position. When each of the light transmitting members is installed, whether or not the above-mentioned optimization criteria can be satisfied is suppressed, so that the change in the polarization state of the light in the illumination optical path is suppressed within a desired range. Evaluate whether or not If the evaluation result is affirmative (YES in FIG. 13), the process proceeds to processing step S6 in which each bulk material is processed to form each light transmitting member.

On the other hand, if the evaluation result is negative (NG in FIG. 13), the rotational angle position of an arbitrary bulk material (light transmitting member) is changed (S 7). That is, in the changing step S7, the above-described clocking method is applied in order to adjust the polarization state in the field to be substantially uniform and adjust the polarization state in the pupil plane to approach the desired polarization state. . Then, it is evaluated whether or not it is possible to suppress the change in the polarization state of the light in the illumination optical path within a desired range when the arbitrary light transmitting member is repositioned at the rotation angle position after the change. For example, here, by optimizing the rotational angle position around the reference axis (optical axis) of each bulk material (light transmissive member) by the clocking method, the light of the optical system that should appropriately suppress the amount of birefringence due to internal distortion It is evaluated whether or not a birefringence distribution that is asymmetric about the axis can be optimized.

[0121] Force to proceed to machining step S6 when the evaluation result is affirmative If the evaluation result is negative, change step S7 and evaluation step S5 are repeated until a positive evaluation result is obtained. return. When a positive evaluation result is obtained in the evaluation step S5, as described above, each light transmitting member is formed by covering each bulk material in the calorie step S6, and after passing through the processing step S6. Each formed light transmitting member is set and incorporated at the rotation angle position optimized in the evaluation step S5 (S8).

[0122] In the manufacturing method of the present embodiment described above, when it is difficult to obtain a positive evaluation result in the evaluation step S5, as shown in FIG. The bulk material may be changed (S9), and the combination of the bulk materials may be changed. In the second modification step S9, an arbitrary bulk material can be changed to a bulk material provided with a desired birefringence distribution for satisfying the optimization criteria. The technique for giving the desired birefringence distribution is briefly described below.

[0123] In the case of an amorphous transparent member made of an amorphous material such as quartz or fluorine-doped quartz (hereinafter referred to as "modified quartz"), birefringence is ideal in its ideal state. Does not occur. However, in quartz or modified quartz, when impurities are mixed, When temperature distribution occurs when cooling quartz formed at high temperature, birefringence due to internal stress appears.

Therefore, by adjusting the amount and type of impurities mixed in the ingot or the thermal history, a desired birefringence distribution can be generated in quartz or modified quartz. In other words, a desired birefringence distribution that is rotationally symmetric (or non-rotational symmetric) with respect to the optical axis is imparted to the amorphous transmission member by adjusting at least one of the density distribution due to impurities and thermal history during manufacturing. can do.

[0125] Examples of impurities include OH, Cl, metal impurities, and dissolved gases. In the case of the direct method, OH is contained in several hundred ppm or more, and then contained in several tens of ppm. However, it is considered that the mixing power is also dominant. When the impurities are mixed into the ingot, the coefficient of thermal expansion of the material changes. For example, when cooling after annealing, the shrinkage of the portion where impurities are mixed increases, and the internal difference due to the difference in shrinkage Stress is generated and stress birefringence occurs. In addition, the thermal history exists regardless of the production method such as the direct method, the VAD (vapor axial deposition) method, the sol-gel method, or the plasma burner method.

[0126] Further, in the manufacturing method of the present embodiment described above, after the evaluation step S5, the processing step S6 in which each bulk material is formed by caloeing each bulk material is performed. However, without being limited thereto, for example, the measuring step S3 may be followed by the machining step S6 prior to the evaluation step S5 or in parallel with the evaluation step S5.

[0127] Further, in the manufacturing method of the present embodiment described above, a nore material sorting step for sorting a bulk material whose birefringence amount is suppressed to 5 nm Zcm or less can be added after the measurement step S3. In this case, it becomes easy to obtain a positive evaluation result in the evaluation step S5. In order to obtain a positive evaluation result more easily in the evaluation step S5, it is preferable to select a bulk material whose birefringence is suppressed to 2 nmZcm or less in the selection step.

[0128] As described above, Fig. 16 shows an embodiment according to the fifth technique in which the first to fourth techniques are summarized. In step S10 for selecting an optical member having an appropriate internal stress as shown in FIG. 16, a bulk member whose birefringence is suppressed to 5 nmZcm or less by measuring the optical member or the like is used. Or, select a lens, etc., and manage the amount of birefringence generated due to internal distortion of the optical member. Here, in correspondence with the process of the fourth technique in FIG. 13, the process S10 in FIG. 16 includes a process S1, a process S2, and a process S3.

[0129] In this step S10, the optical system mainly disposed in the optical path between the force polarization setting section (3, 7) and the irradiated surface (mask, etc.) described for the optically transparent optical member. In the case that includes a reflecting member, the phase difference generated by reflection between the light incident as P-polarized light and the light incident as S-polarized light on the reflecting film of the reflecting member Needless to say, it is desirable to select the reflecting member to be within 15 degrees. In order to improve the performance of the device, it is more desirable to select an optical member whose birefringence due to internal strain is suppressed to 2 nmZcm or less, needless to say.

Next, step S11 for setting the position of the rotation angle includes step S4, step S5, step S7, and step S9, corresponding to the step of the fourth method in FIG. For example, in step S11, the amount of birefringence due to internal distortion is appropriately adjusted by optimizing the rotation angle position around the reference axis (optical axis) of each optical member (bulk material, light transmitting member) by the clocking method. Evaluate whether or not an asymmetric birefringence distribution can be optimized in the optical axis of the optical system to be suppressed. In step S11, if the optical system placed in the optical path between the polarization setting section (3, 7) and the irradiated surface (mask, etc.) includes a reflective member, it is selected in step S10. Including the reflection characteristics of the reflected members.

[0131] If optimization is not possible in step S11 (indicated by NG in Fig. 16), the process returns to step S10, and an optical member having an appropriate internal strain distribution is selected again. If the process is optimized (indicated by YES in Fig. 16), the process proceeds to the next step S12.

[0132] The manufacturing process S12 of the optical system (optical unit) includes a process S6 for forming each optical member and an assembling process S8 for each optical member, corresponding to the process of the fourth method in FIG. is there. Here, in step S12, the amount of birefringence generated due to externally applied strain (stress, etc.) as shown in FIGS. 9 to 12 when assembling the optical member that has undergone the process of forming each optical member. Includes a step of holding or supporting the optical member so that the thickness is suppressed to 5 nmZcm or less. That is, step S12 includes a step of managing the birefringence amount or birefringence distribution due to strain to which an external force is also applied. including.

[0133] In step S12, in order to improve the performance of the apparatus, it is more desirable to hold the optical member so that the amount of birefringence generated by external strain is suppressed to 2 nmZcm or less! / Needless to say! /.

As described above, the technique shown in FIG. 16 can be described from one viewpoint. An optical system disposed in the optical path between the polarization setting unit (3, 7) and the irradiated surface (mask, etc.). The amount of birefringence of the light is controlled, or an optical system in which the amount of birefringence is controlled is arranged in the optical path between the polarization setting unit and the surface to be irradiated, so that the surface to be irradiated and thus the pupil It is possible to obtain a well-polarized illumination distribution on the surface.

[0135] If the method shown in Fig. 16 is described from another viewpoint, the polarization state of light reaching the irradiated surface via an optical system disposed in the optical path between the polarization setting unit and the irradiated surface. However, the polarization setting unit force maintains the polarization characteristics in the optical path between the irradiated surface or the optical path between the polarization setting unit and the irradiated surface so that the predetermined polarization state is obtained. By arranging the optical system to maintain the polarization state of the light reaching the irradiated surface so that the polarization state of the light on the surface becomes a predetermined polarization state, And an illumination distribution with a good polarization state can be obtained.

[0136] From the above two viewpoints, information relating to a part or a part of the optical system (including the entire optical system) arranged in advance in the optical path between the polarization setting unit and the irradiated surface (for example, Information on acceptable optical performance of the optical system related to birefringence, etc. and at least one piece of information such as measurement related to birefringence of at least one optical member constituting the optical system as shown in step S3 of FIG. 13) It is preferable to obtain

[0137] Fig. 16 shows an example in which the optical member is managed based on the measurement value of the birefringence amount of the bulk material. Bulk material force Performs predetermined processing to form an optical member such as a lens. The step S10 may be executed based on the birefringence distribution of the optical member formed and processed. In this case, the processing step of the optical member in step S12 is not necessary, and the step of assembling each optical member is performed.

FIG. 16 mainly describes an example of manufacturing an illumination optical apparatus and an exposure apparatus equipped with the illumination optical apparatus, but in the case of periodic maintenance (repair, maintenance, inspection) of the illumination optical apparatus. Will be described with reference to FIG.

[0139] First, at the time of maintenance, in the step S20 of selecting an appropriate replacement optical member or an appropriate replacement optical unit, first, information on polarization optical performance and the like regarding the illumination optical system (polarization measuring unit 14). Optical information such as the actual measurement value of the optical system and the measurement value at the time of manufacture of the illumination optical system), and the optical information such as the birefringence and polarization characteristics of the optical system placed in the optical path between the polarization setting unit and the irradiated surface ( Polarized optics related to at least one optical member of the optical system arranged in the optical path between the polarization setting unit and the irradiated surface) At least one piece of performance information (information such as an actual measurement value of the polarization measuring unit 14 or a measurement value at the time of manufacturing the optical member) is obtained in advance. After that, as described above, based on the information about the obtained optical system, the optical member or optical unit to be replaced is specified, and the appropriate replacement optical unit whose birefringence due to internal distortion is suppressed to 5 nmZcm or less. Select a suitable replacement optical unit.

[0140] Next, in step S21, an appropriate rotation angle position of the selected optical member is set and evaluated as in each step (S4, S5, S7, S9) shown in FIG. If obtained, the process proceeds to the next optical system manufacturing process (optical system adjustment process). If in step S21, good evaluation results are not obtained! / In case, return to the previous selection step S20.

[0141] Next, after processing each optical member, each optical member is incorporated into the illumination optical system. This assembling step includes a step of holding or supporting the optical member so that the amount of birefringence generated by externally applied strain (stress etc.) is suppressed to 5 nm Zcm or less. That is, step S22 includes a step of managing the birefringence amount or birefringence distribution due to the strain to which an external force is also applied, and this management step includes the holding step.

[0142] Note that, in step S20 in Fig. 16, the force shown in the example in which the optical member is managed based on the measurement value of the birefringence amount from the bulk material. Bulk material force. The step S20 may be performed based on the birefringence distribution of the processed optical member after forming the optical member and the birefringence distribution. In this case, an optical member processing step in the optical system manufacturing step (adjustment step) S22 is not necessary, and an assembly step of each optical member is performed.

[0143] As described above, the maintenance method shown in Fig. 16 can be described from one point of view. An optical device arranged in the optical path between the polarization setting unit (3, 7) and the irradiated surface (mask, etc.). The birefringence of the system It can be improved on the irradiated surface, and hence on the pupil plane, by taking steps to manage, or by placing an optical system with controlled birefringence in the optical path between the polarization setting section and the irradiated surface. An illumination distribution in a polarization state can be obtained.

[0144] In addition, if the maintenance method shown in Fig. 16 is described from another viewpoint, the light reaching the irradiated surface via the optical system disposed in the optical path between the polarization setting unit and the irradiated surface will be described. In the step of maintaining the polarization characteristics in the optical path between the polarization setting unit force and the irradiated surface, or in the optical path between the polarization setting unit and the irradiated surface so that the polarization state becomes a predetermined polarization state, By adopting an optical system to maintain the polarization state of the light reaching the irradiated surface so that the polarization state of the light on the irradiated surface becomes a predetermined polarization state, the irradiated surface, and hence the pupil surface An illumination distribution with a good polarization state can be obtained.

[0145] From the above two viewpoints, information on a part or a part of the optical system (including the entire optical system) arranged in the optical path between the polarization setting unit and the irradiated surface in advance (for example, As shown in step S20 of FIG. 16, information such as measurement of optical performance related to the optical system related to birefringence, etc., and information such as measurement related to birefringence of at least one optical member constituting the optical system). It is preferable to obtain it.

In the maintenance method of FIG. 16, in order to improve the performance of the apparatus, an optical member is used in step S 20 so that the amount of birefringence generated by internal distortion is suppressed to 2 nmZcm or less. Desirably, it is more desirable to hold the optical member in step S22 so that the amount of birefringence generated by external strain is suppressed to 2 nmZcm or less! /.

[0147] In addition, in steps S10 to S12 in Fig. 16, the contents of the manufacturing method of the illumination optical system have been mainly described. From another viewpoint, steps S10 to S12 in Fig. 16 are performed in accordance with the manufacturing method of the exposure apparatus. It can also be referred to as an illumination optical system adjustment method or an exposure apparatus adjustment method. In addition, in steps S20 to S22 in FIG. 16, the contents of the adjustment method of the illumination optical system have been mainly described. From another point of view, steps S20 to S22 in FIG. It can also be referred to as a system manufacturing method or an exposure apparatus manufacturing method.

In the above-described embodiment, the polarization conversion element 7 is disposed immediately before the conical axicon system 8 (or the pupil of the focal lens 5 or the vicinity thereof). However, it is limited to this Of course, for example, the polarization conversion element 7 can be arranged at or near the pupil of the imaging optical system 13 or immediately before or after the micro fly's eye lens 10. However, if the polarization conversion element 7 is arranged in the optical path of the imaging optical system 13 or before and after the micro fly's eye lens 10, the required effective diameter of the polarization conversion element 7 tends to be large, so that a high quality and large quartz substrate can be obtained. Considering the current situation where this is difficult, it is not very desirable.

[0149] In the above-described embodiment, at least one surface (for example, the exit surface) of the polarization conversion element 7 is formed to be uneven, and as a result, the polarization conversion element 7 changes discretely (discontinuously) in the circumferential direction. Thickness distribution. However, without being limited thereto, at least one surface (for example, the exit surface) of the polarization conversion element 7 so that the polarization conversion element 7 has a thickness distribution that changes substantially discontinuously in the circumferential direction. Can be formed into a curved surface.

[0150] In the above-described embodiment, the polarization conversion element 7 is constituted by eight fan-shaped basic elements corresponding to eight divisions of the annular zone-shaped effective region. However, it is not limited to this, for example, there are 8 fan-shaped basic elements corresponding to 8 divisions of a circular effective area, and it corresponds to 4 divisions of a circular or annular effective area The polarization conversion element 7 can also be constituted by four fan-shaped basic elements or 16 fan-shaped basic elements corresponding to 16 divisions of a circular or ring-shaped effective area. In other words, the shape of the effective area of the polarization conversion element 7, the number of divisions of the effective area (number of basic elements), etc.! Various modifications are possible.

[0151] In the above-described embodiment, the basic elements 7A to 7D (and hence the polarization conversion element 7) are formed using quartz. However, it is also possible to form each basic element using other suitable optical materials having optical rotation without being limited thereto. In this case, it is preferable to use an optical material having an optical rotation ability of 100 degrees Zmm or more with respect to light of the wavelength used. That is, it is not preferable to use an optical material having a small optical rotation power because the thickness required to obtain the required rotation angle in the polarization direction becomes too large, resulting in a loss of light quantity.

In the exposure apparatus according to the above-described embodiment, the illumination optical device illuminates the mask (reticle) (illumination process), and the transfer pattern formed on the mask using the projection optical system is applied to the photosensitive substrate. Microdevices (semiconductor elements, imaging elements, liquid crystal display elements, thin film magnetic heads, etc.) can be produced by exposure (exposure process). The above-mentioned actual An example of a technique for obtaining a semiconductor device as a micro device by forming a predetermined circuit pattern on a wafer or the like as a photosensitive substrate using the exposure apparatus of the embodiment will be described with reference to the flowchart of FIG. To do.

First, in step 301 in FIG. 17, a metal film is deposited on one lot of wafers. In the next step 302, a photoresist is applied onto the metal film on the one lot of wafers. Thereafter, in step 303, using the exposure apparatus of the above-described embodiment, the pattern image on the mask is sequentially exposed and transferred to each shot area on the wafer of one lot via the projection optical system. After that, in step 304, the photoresist on the one lot of wafers is developed, and in step 305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit pattern force is formed in each shot area on each wafer. Then, devices such as semiconductor elements are manufactured by forming a circuit pattern of an upper layer. According to the semiconductor device manufacturing method described above, a semiconductor device having an extremely fine circuit pattern can be obtained with high throughput.

[0154] In the exposure apparatus of the above-described embodiment, a predetermined pattern is formed on a plate (glass substrate).

By forming (circuit pattern, electrode pattern, etc.), a liquid crystal display element as a microdevice can also be obtained. Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 18, in the pattern formation process 401, a so-called photolithography process is performed in which the exposure pattern of the above-described embodiment is used to transfer and expose the mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). . By this optical lithography process, a predetermined pattern including a large number of electrodes and the like is formed on the photosensitive substrate. Thereafter, the exposed substrate is subjected to a development process, an etching process, a resist stripping process, and the like, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming process 402.

[0155] Next, in the color filter forming step 402, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix, or R, G, A color filter is formed by arranging a set of filters of the three stripes B in the horizontal scanning line direction. After the color filter forming step 402, the cell assembly step 403 is executed. The In the cell assembly step 403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step 401, the color filter obtained in the color filter formation step 402, and the like.

[0156] In the cell assembly step 403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern formation step 401 and the color filter obtained in the color filter formation step 402. Manufactures panels (liquid crystal cells). Thereafter, in the module assembling step 404, components such as an electric circuit and a backlight for performing display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete the liquid crystal display element. According to the above liquid crystal display element manufacturing method, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

In the above-described embodiment, the force using KrF excimer laser light (wavelength: 248 nm) or ArF excimer laser light (wavelength: 193 nm) as the exposure light is not limited to this, and other suitable Laser light source, for example, F laser light that supplies laser light with a wavelength of 157 nm

The present invention can be applied to two sources. Furthermore, in the above-described embodiment, the present invention has been described by taking an exposure apparatus including an illumination optical apparatus as an example. However, the present invention is applied to a general illumination optical apparatus for illuminating a surface other than an irradiation target. It is clear that you can.

[0158] In the above-described embodiment, a method of filling the optical path between the projection optical system and the photosensitive substrate with a medium (typically liquid) having a refractive index larger than 1.1, so-called immersion. Laws may apply. In this case, as a method for filling the liquid in the optical path between the projection optical system and the photosensitive substrate, a method for locally filling the liquid as disclosed in International Publication No. WO99Z49504, A method of moving a stage holding a substrate to be exposed as disclosed in Japanese Patent No. 124873 in a liquid tank, or a predetermined stage on such a stage as disclosed in Japanese Patent Laid-Open No. 10-303114. For example, a method can be employed in which a liquid tank having a depth is formed and the substrate is held in the tank.

[0159] As the liquid, it is preferable to use a liquid that is stable with respect to a projection optical system having a transmittance to exposure light and having a refractive index as high as possible, and a photoresist applied to the substrate surface. For example, KrF excimer laser light or ArF excimer laser light is used as exposure light. In this case, pure water or deionized water can be used as the liquid. In addition, when F laser light is used as exposure light, the liquid is, for example, fluorine-based fluorine that can transmit F laser light.

2

Use a fluorine-based liquid such as perfluorinated polyether (PFPE)!

Explanation of symbols

1 Light source

3 Polarization state switching section

3a 1Z4 wave plate

3b 1Z2 wave plate

4 Diffractive optical element (light flux conversion element)

5 Before power lens

7 Polarization conversion element

8 Conical axicon system

9 Zoom lens

10 Micro fly's eye lens

11 Condenser optics

12 Mask blind

13 Imaging optics

14 Polarization measurement unit

20 Control unit

21 Drive unit

M mask

PL projection optics

W wafer

Ml, M2 folding mirror

Claims

The scope of the claims

[1] In an illumination optical apparatus that illuminates an illuminated surface based on light that is also supplied with light source power, a polarization state of light that is disposed in an optical path between the light source and the illuminated surface and reaches the illuminated surface Including a polarization setting unit for setting the to a predetermined polarization state,

Each of the plurality of light transmitting members disposed in the optical path between the polarization setting unit and the irradiated surface is formed of an optical material in which the amount of birefringence generated due to internal distortion is suppressed to 5 nmZcm or less. An illumination optical device.

[2] The plurality of light transmitting members are respectively positioned at required rotational angular positions around the optical axis in order to reduce the influence of birefringence caused by internal distortion in each light transmitting member by canceling. 2. The illumination optical apparatus according to claim 1, wherein the illumination optical apparatus is provided.

[3] The light transmitting member according to claim 1 or 2, wherein each of the plurality of light transmitting members is held such that an amount of birefringence generated due to an external stress is suppressed to 5 nm Zcm or less. Illumination optical device.

[4] In an illumination optical apparatus that illuminates an illuminated surface based on light that is also supplied with light source power, a polarization state of light that is disposed in an optical path between the light source and the illuminated surface and reaches the illuminated surface Including a polarization setting unit for setting the to a predetermined polarization state,

The plurality of light transmissive members arranged in the optical path between the polarization setting unit and the irradiated surface reduces the influence of birefringence caused by internal distortion in each light transmissive member by offsetting. Therefore, the illumination optical device is characterized in that it is placed at a required rotational angle position around the optical axis.

[5] Each of the plurality of light transmitting members has a birefringence amount of 5 nm generated due to an external stress.

5. The illumination optical apparatus according to claim 4, wherein the illumination optical apparatus is held so as to be suppressed to Zcm or less.

[6] It further includes a bending mirror disposed in the optical path between the polarization setting unit and the irradiated surface for bending the optical path,

The reflection film of the folding mirror has a phase difference generated by reflection between light incident on the reflection film with P-polarized light and light incident on the reflection film with S-polarized light. It is formed to be within 15 degrees of all rays of light! The illumination optical apparatus according to any one of claims 1 to 5.

[7] In an illumination optical apparatus that illuminates an illuminated surface based on light that is also supplied with light source power, a polarization state of light that is disposed in an optical path between the light source and the illuminated surface and reaches the illuminated surface A polarization setting unit for setting a predetermined polarization state;

The reflection film of the folding mirror has a phase difference generated by reflection between light incident on the reflection film with P-polarized light and light incident on the reflection film with S-polarized light. The illumination optical device is characterized in that it is formed to be within 15 degrees of all the rays of light!

[8] In an illumination optical apparatus that illuminates an illuminated surface based on light that is also supplied with light source power, polarization of light on the illuminated surface is arranged in an optical path between the light source and the illuminated surface. A polarization setting unit for setting the state to a predetermined polarization state;

An illumination optical apparatus, comprising: an optical system disposed in an optical path between the polarization setting unit and the irradiated surface and having a controlled birefringence amount.

[9] In an illumination optical apparatus that illuminates an illuminated surface based on light that is also supplied with light source power, polarization of light on the illuminated surface that is disposed in an optical path between the light source and the illuminated surface A polarization setting unit for setting the state to a predetermined polarization state;

The polarization of the light reaching the irradiated surface is arranged in an optical path between the polarization setting unit and the irradiated surface so that the polarization state of the light on the irradiated surface becomes the predetermined polarization state. And an optical system that maintains an optical state.

10. The illumination optical apparatus according to claim 8, wherein the optical system includes a plurality of optical members having controlled birefringence amounts.

[11] The illumination optical apparatus according to [10], wherein the plurality of optical members are respectively placed at required rotational angle positions around the optical axis.

[12] The illumination optical apparatus according to [10] or [11], wherein the plurality of optical members have a birefringence amount of 5 nmZcm or less due to internal strain.

[13] The plurality of optical members have an amount of birefringence generated due to external strain of 5 nmZcm or less. The illumination optical apparatus according to claim 10, wherein the illumination optical apparatus is held so as to be suppressed to a minimum.

[14] In the method of manufacturing an illumination optical device having a plurality of light transmission members,

A bulk material preparing step of preparing a bulk material for forming each of the plurality of light transmitting members;

A processing step of processing each of the plurality of bulk materials to form each light transmission member, and a set in which each of the plurality of light transmission members processed in the processing step is incorporated at a predetermined set position based on the result of the calculation step. A method for manufacturing an illumination optical device.

[15] In the calculation step, based on the collected information, with respect to a combination of a plurality of light transmissive members constituting at least a part of the illumination optical device, the influence of birefringence in each light transmissive member is within an allowable range. In order to reduce, the rotational angle position around the optical axis of each light transmitting member is optimized in calculation, and a combination of a plurality of light transmitting members constituting at least a part of the illumination optical device that can be optimized is obtained. Including an optimization step for obtaining a rotation angle position of each light transmission member under an optimal combination of the plurality of light transmission members,

The assembling step includes a step of incorporating a plurality of light transmitting members processed in the processing step at respective predetermined rotational angle positions based on the information on the optimized rotational angle position. 15. The method of manufacturing an illumination optical device according to claim 14,

[16] In the optimization step, when obtaining a combination capable of optimizing a plurality of light transmission members constituting at least a part of the illumination optical device, at least the illumination optical device 16. The method according to claim 15, further comprising the step of replacing measurement information of the bulk material relating to at least one light transmission member in a combination of a plurality of light transmission members constituting a part with measurement information of another bulk material. Manufacturing method of illumination optical device.

[17] The method further includes a bulk material selection step of selecting a bulk material whose birefringence is suppressed to 5 nmZcm or less after the measurement step,

The calculation step collects measurement information of each Balta material related to a plurality of light transmission members constituting at least a part of the illumination optical device based on the measurement information selected in the bulk material selection step, An appropriate combination of a plurality of light transmission members constituting at least a part of the illumination optical device capable of allowing the influence of birefringence is selected, and each light transmission member by an appropriate combination of the plurality of light transmission members The method for manufacturing an illumination optical device according to claim 14, further comprising: obtaining a set position of the illumination optical device.

[18] An illumination optical device according to any one of claims 1 to 13, or an illumination optical device manufactured by the manufacturing method according to any one of claims 14 to 17, comprising the illumination optical device. An exposure apparatus characterized by exposing a pattern of an illuminated mask onto a photosensitive substrate.

[19] A mask pattern is formed by using the illumination optical apparatus according to any one of claims 1 to 13 or the illumination optical apparatus manufactured by the manufacturing method according to any one of claims 14 to 17. An exposure method comprising exposing a photosensitive substrate.

[20] A mask pattern is formed using the illumination optical apparatus according to any one of claims 1 to 13 or the illumination optical apparatus manufactured by the manufacturing method according to any one of claims 14 to 17. A method for producing a microdevice, comprising: an exposure step of exposing a photosensitive substrate; and a development step of developing the photosensitive substrate exposed by the exposure step.

[21] In the adjustment method of the illumination optical device having the polarization setting unit that sets the polarization state of the light on the irradiated surface to a predetermined polarization state,

Obtaining information on at least a part of an optical system to be arranged in an optical path between the polarization setting unit and the irradiated surface; A management step of managing a birefringence amount of an optical system disposed in an optical path between the polarization setting unit and the irradiated surface.

22. The adjustment method for an illumination optical device according to claim 21, wherein the management step includes a step of managing a birefringence amount generated by internal distortion of a plurality of optical members included in the optical system.

[23] The step of managing the amount of birefringence due to the internal strain includes the step of using, as the plurality of optical members, an optical member having a birefringence amount of 5 nmZcm or less caused by the internal strain. The method of adjusting an illumination optical apparatus according to claim 22.

24. The force of any one of claims 21 to 23, wherein the management step includes a step of adjusting a birefringence distribution that is rotationally asymmetric with respect to an optical axis remaining in the optical system. Adjustment method of the illumination optical apparatus mounted.

[25] The step of adjusting the birefringence distribution includes a step of standing each of the plurality of optical members of the optical system at a required rotation angle position around the optical axis. 25. The method of adjusting an illumination optical apparatus according to claim 24.

[26] The force according to any one of items 21 to 25, wherein the management step includes a step of managing a birefringence amount generated due to an externally applied distortion to the optical system. The adjustment method of the illumination optical apparatus as described in any one of Claims 1-3.

[27] The step of managing the amount of birefringence generated due to the strain applied from the outside is performed so that the amount of birefringence generated due to the strain applied by the external force is suppressed to 5 nmZcm or less. 27. The method for adjusting an illumination optical apparatus according to claim 26, further comprising a step of holding the plurality of optical members included in the optical system.

[28] In the adjustment method of the illumination optical device having the polarization setting unit that sets the polarization state of the light on the irradiated surface to a predetermined polarization state,

Maintaining the polarization setting force in the optical path to the irradiated surface so that the polarization state of the light reaching the irradiated surface via the optical system becomes the predetermined polarization state; A method for adjusting an illumination optical apparatus, comprising:

29. The adjustment method for an illumination optical device according to claim 28, wherein the maintaining step includes a step of managing a birefringence amount generated by internal distortion of a plurality of optical members included in the optical system.

[30] The step of managing the amount of birefringence due to the internal strain includes the step of using, as the plurality of optical members, an optical member having a birefringence amount of 5 nmZcm or less caused by the internal strain. 30. The method of adjusting an illumination optical apparatus according to claim 29.

31. The force according to any one of claims 28 to 30, wherein the maintaining step includes a step of adjusting a birefringence distribution that is rotationally asymmetric with respect to an optical axis remaining in the optical system. Adjustment method of the illumination optical apparatus mounted.

[32] The step of adjusting the birefringence distribution includes the step of standing each of the plurality of optical members of the optical system at a required rotation angle position around the optical axis. 32. The method of adjusting an illumination optical apparatus according to claim 31.

[33] The force according to any one of claims 28 to 32, wherein the management step includes a step of managing a birefringence amount generated due to an externally applied distortion to the optical system. The adjustment method of the illumination optical apparatus as described in any one of Claims 1-3.

[34] The step of managing the amount of birefringence generated due to the strain applied from the outside is performed so that the amount of birefringence generated due to the strain applied by the external force is suppressed to 5 nmZcm or less. 34. The method for adjusting an illumination optical apparatus according to claim 33, further comprising a step of holding the plurality of optical members included in the optical system.

[35] An illumination optical device adjusted by the adjustment method according to any one of claims 21 to 34, wherein the pattern of the mask illuminated by the illumination optical device is exposed to a photosensitive substrate. An exposure apparatus characterized by:

[36] An exposure method comprising exposing a mask pattern to a photosensitive substrate using the illumination optical device adjusted by the adjustment method according to any one of claims 21 to 34.

[37] Using the illumination optical device adjusted by the adjustment method according to any one of claims 21 to 34, an exposure step of exposing a pattern of a mask onto a photosensitive substrate, and exposure by the exposure step. And a developing step for developing the photosensitive substrate. The manufacturing method of the mouthpiece device.