JP4581526B2 - Depolarizing element, illumination optical apparatus, exposure apparatus, and microdevice manufacturing method - Google Patents

Description

The present invention relates to a depolarizing element that converts incident light into non-polarized light, an illumination optical apparatus including the depolarization element, an exposure apparatus including the illumination optical apparatus , and a method of manufacturing a micro device using the exposure apparatus. It is.

  In a conventional exposure apparatus, a light beam emitted from a light source is incident on a fly-eye lens (or a microlens array or the like) as an optical integrator, and a substantial surface light source including a large number of light sources on a rear focal plane. A secondary light source is formed. The light beam from the secondary light source is limited through an aperture stop disposed in the vicinity of the rear focal plane of the fly-eye lens, and then enters the condenser lens.

  The light beam condensed by the condenser lens illuminates the 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 via the projection optical system. Thus, the mask pattern is projected and exposed (transferred) onto the wafer. The pattern formed on the mask is highly integrated, and it is essential to obtain a uniform illuminance distribution on the wafer in order to accurately transfer this fine pattern onto the wafer.

Currently, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, an ArF excimer laser light source that supplies light with a wavelength of 193 nm, and the like are used as the exposure light source. In addition, use of an F ₂ laser light source that supplies light having a wavelength of 157 nm has been proposed. In a conventional exposure apparatus, linearly polarized light supplied from this type of light source is converted into non-polarized light by a depolarizing element, and the mask is illuminated with light in a non-polarized state (see, for example, Patent Document 1) ).

JP 2001-264696 A

  However, in the conventional depolarizing element, the crystal optical axis (the fast axis or the slow axis) of the depolarizing element forms an angle of exactly 45 degrees with respect to the polarization direction of the incident light (the major axis direction of the elliptically polarized light). It is necessary to set as follows. That is, when the polarization direction of incident light is different from the direction assumed for some reason, or when the direction of the crystal optical axis of the depolarization element deviates from the intended direction for some reason, a sufficient depolarization effect is obtained. I can't.

  In addition, even if the polarization state of light supplied from the light source is accurately known, elements that change the polarization state in the optical path from the light source to the depolarization element (for example, birefringence of the transmission member and PS phase difference of the reflection member). Etc.), the polarization direction of the light incident on the depolarizing element may not be accurately known. In this case, it is difficult to set the crystal optical axis of the depolarization element so as to form an angle of 45 degrees with respect to the polarization direction of the incident light, and a sufficient depolarization effect cannot be obtained.

  Here, the disadvantages of the conventional depolarizing element will be described in detail. FIG. 20 is a diagram schematically showing a configuration of a conventional depolarizing element. As shown in FIG. 20A, the conventional depolarizing element includes a first declination prism (wedge plate) 101 and a second declination prism 102 in order from the light incident side. The first declination prism 101 is made of a birefringent material such as quartz and has a thickness that varies depending on the passage position of the light beam. The second declination prism 102 is made of a non-birefringent material such as quartz glass, and functions as a correction plate for returning the light beam bent by the declination action of the first declination prism 101.

  In a strict discussion, the light passing through a declination prism made of a birefringent material has a slightly different refraction angle between ordinary light and extraordinary light, and due to the optical path difference between ordinary and extraordinary light. When the phase difference occurs, the polarization state of the incident polarized light changes. However, here, the description will be made by approximating that the first declination prism 101 is a phase shifter having a phase shift amount different depending on the passing position as described above. Further, an explanation based on such approximation is sufficient for explaining the object and effect of the present invention.

  FIG. 20B shows the direction of the crystal optical axis and the polarization direction of incident light when the first deflection prism 101 is viewed from the optical axis direction. In FIG. 20B, the vertical direction is defined as the S1 axis of the Stokes parameter, and the −45 degrees and +45 degrees directions are defined as the S2 axis of the Stokes parameter. Here, the polarization direction of incident light is the direction of the elliptical long axis in elliptically polarized light, and means the vibration direction of light in linearly polarized light. In FIG. 20B, the angle of the first deflection prism 101 with respect to the vertical axis in the crystal optical axis direction 103 is represented by φ, and the angle with respect to the vertical axis of the polarization direction 104 of incident light is represented by θ.

  Since the polarized light incident on the first declination prism 101 undergoes different polarization state changes depending on the passing position, the polarization state of the emitted light can be regarded as an average of the light that has undergone different polarization state changes depending on the passing position. Therefore, the Stokes parameter of the emitted light is an average of the Stokes parameters of the light that has undergone a change in polarization state depending on the passing position.

  Here, out of the refractive indexes of the first deflection prism 101 when viewed from the optical axis direction, the high refractive index is n1, the low refractive index is n2, and the wedge angle (vertical angle) of the first deflection prism 101. Where α is α and the cross-sectional size of the incident light beam is L, Lα (n1-n2) is an integral multiple (1 ×, 2 ×, 3 ×...) Of the wavelength λ of the incident light, or Even if it is not an integral multiple, if Lα (n1-n2) is sufficiently large with respect to λ, it can be considered that the amount of phase shift of the first declination prism 101 is distributed almost uniformly between 0 and 2π. . That is, the Stokes parameter of the emitted light is an average when the phase shift angle change of 0 to 2π is received with respect to the Stokes parameter of the incident light. In order to obtain such an effect, it is necessary to satisfy the condition of Lα (n1-n2) ≧ λ.

  FIG. 21 shows how the Stokes parameter of the emitted light changes depending on the angle θ of the polarization direction of the incident light when the angle φ in the crystal optical axis direction of the first deflection prism is set to 45 degrees. FIG. In FIG. 21, the horizontal axis represents the angle θ of the polarization direction of linearly polarized light incident on the first deflection prism 101, and the vertical axis represents the value of the Stokes parameter of the emitted light. As shown in FIG. 21, when the polarization direction of incident light is changed, S1 (horizontal linear polarization intensity minus vertical linear polarization intensity) and S3 (clockwise circular polarization intensity minus counterclockwise circular polarization intensity) are always kept at zero. However, it can be seen that S2 (45-degree linear polarization intensity minus 135-degree linear polarization intensity) varies greatly between -1 and +1. Therefore, only when the angle θ (0 ≦ θ <360) of the polarization direction of the incident light is 0 degree, 90 degrees, 180 degrees, and 270 degrees, S1, S2, and S3 are simultaneously 0, and as a result, complete polarization. A cancellation effect is obtained.

  FIG. 22 shows how the Stokes parameter of the emitted light changes depending on the angle θ of the polarization direction of the incident light when the angle φ in the crystal optical axis direction of the first declination prism is set to −22.5 degrees. FIG. In this case, as shown in FIG. 22, both S1 and S2 change as the polarization direction of the incident light changes, and the angle θ of the polarization direction of the incident light is 22.5 degrees, 112.5 degrees, 202. It can be seen that the incident polarization is completely depolarized at 5 degrees and 292.5 degrees. As described above, in order to obtain a complete depolarization effect in a conventional depolarization element using a single quartz declination prism, the angle of the crystal optical axis direction with respect to the polarization direction of incident light is precisely 45 degrees + 90 degrees × I ( I must be set to an integer:... -1, 1,0, +1, +2.

  FIG. 23 is a diagram for explaining the operation of the conventional depolarizing element shown in FIG. 20 using Stokes parameters and Poincare spheres. FIG. 24 is a diagram for explaining the disadvantages of the conventional depolarizing element shown in FIG. 20 using Stokes parameters and Poincare spheres. The Stokes parameters and the Poincare sphere are described in detail in Tatsuta Tatsuo, “Applied Optics II”, Baifukan. In FIG. 23, when the incident polarized light is lateral linear polarized light, this linear polarized light is represented by a point 106a on the Poincare sphere. In the conventional depolarizing element shown in FIG. 20, the direction of the crystal optical axis of the first declination prism 101 is set to make an angle of 45 degrees with respect to the polarization direction of incident light.

  For this reason, the phase shift action of the first declination prism 101 is expressed by the rotation around the S2 axis in the Poincare sphere. The Poincare sphere is easy to understand when it is considered that the equator circle corresponds to 180 degrees. Thus, since the incident polarized light receives a different amount of phase shift depending on the passing position of the first declination prism 101, the polarization state of the emitted light is distributed on the line indicated by reference numeral 106b. At this time, since the average of the polarization states distributed on the line 106b is the center of the Poincare sphere, the Stokes parameter of the emitted light is S1 = S2 = S3 = 0, and a complete depolarization effect can be obtained.

  On the other hand, in FIG. 24, incident polarized light is represented by a point 107a on the Poincare sphere. In this case, since the polarization direction of the incident light represented by the point 107a is deviated from an angle of 45 degrees with respect to the S2 axis, the depolarization effect should be insufficient. Considering the Poincare sphere in FIG. 24, the incident polarized light represented by the point 107a is subjected to the phase shifting action (that is, rotation around the S2 axis) of the first declination prism 101, and the polarization state of the emitted light is denoted by reference numeral 107b. It will be distributed on the line shown. In this case, the average of the Stokes parameters of the emitted light is S1 = S3 = 0, but does not become S2 = 0. Therefore, the non-polarized state is not achieved, and the depolarization effect becomes insufficient.

  As described above, in the conventional depolarizing element, the crystal optical axis (the fast axis or the slow axis) of the depolarizing element is precisely 45 degrees with respect to the polarization direction of the incident light (the major axis direction of the elliptically polarized light). It is necessary to set the angle. As a result, when the polarization direction of the incident light is different from the direction assumed for some reason, or when the direction of the crystal optical axis of the depolarization element is deviated from the intended direction for some reason, or the light incident on the depolarization element In the case where the polarization direction is not accurately known, a sufficient depolarization effect cannot be obtained.

  Currently, quartz, which is a birefringent crystal material that has durability against long-term laser irradiation, is used as a depolarizing element member. However, with higher output of lasers, higher laser irradiation It is desired to use an optical member having durability as a member of a depolarizing element. That is, it is desired that an optical member that has conventionally been highly resistant to laser irradiation but cannot be used as a depolarizing element because of its small birefringence value can also be used as a member of the depolarizing element. Yes.

An object of the present invention is to provide a depolarization element using stress birefringence generated in an optical member, an illumination optical apparatus including the depolarization element, an exposure apparatus including the illumination optical apparatus , and a microdevice using the exposure apparatus. It is to provide a manufacturing method.

The depolarizing element of the present invention is a depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light, and includes at least two optical members arranged along an optical axis, Stress is applied to at least one of the at least two optical members from the first direction, and stress is applied to the at least one other of the at least two optical members from a second direction different from the first direction. Stress applying means for applying , at least one of the at least two optical members includes a first deflection prism, and at least one of the at least two optical members includes a second deflection prism. And the apex angle directions of the first declination prism and the second declination prism are set so as to be different from each other and not opposite to each other when viewed from the direction of the optical axis .

The depolarizing element of the present invention is a depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light, and includes at least two optical members arranged along the optical axis; Applying stress to at least one of the at least two optical members from a first direction, and applying at least one other of the at least two optical members from a second direction different from the first direction. Stress applying means for applying stress, wherein at least one of the at least two optical members includes a first deflection prism, and at least one of the at least two optical members is a second deflection angle. has a prism apex angle direction of the first deviation prism and the second deviation prism, the are set to be not different and opposite directions to each other when viewed from the direction of the optical axis, when the small The two declination prisms are made of either amorphous material quartz, birefringent crystal material quartz, calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride or calcite. It is characterized by being.

The depolarizing element of the present invention is a depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light, and includes at least two optical members arranged along the optical axis; Applying stress to at least one of the at least two optical members from a first direction, and applying at least one other of the at least two optical members from a second direction different from the first direction. Stress applying means for applying stress, wherein at least one of the at least two optical members includes a first deflection prism, and at least one of the at least two optical members is a second deflection angle. has a prism apex angle direction of the first deviation prism and the second deviation prism, the are set to be not different and opposite directions to each other when viewed from the direction of the optical axis, the stress applying Stage is characterized by having at least one of the pressing mechanism and tensioning mechanism to impart said predetermined direction to stress of the first deviation prism and the second deviation prism.

The depolarizing element of the present invention is a depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light, and includes at least two optical members arranged along the optical axis; Applying stress to at least one of the at least two optical members from a first direction, and applying at least one other of the at least two optical members from a second direction different from the first direction. Stress applying means for applying stress, wherein at least one of the at least two optical members includes a first cylindrical lens, and at least one other of the at least two optical members includes a second cylindrical lens. The generating lines of the first cylindrical lens and the second cylindrical lens are set to face different directions as viewed from the direction of the optical axis, Stress applying means is characterized by imparting stress in the vertical direction respectively generatrix of the first cylindrical lens and the second cylindrical lens.

The illumination optical device according to the present invention is an illumination optical device including a light source that supplies light having a degree of polarization, and a light guide optical system that irradiates a surface to be irradiated with light from the light source. The system is characterized by having a depolarizing element as described in the present invention .

The exposure apparatus of the present invention, the wherein an illumination optical apparatus of the present invention for illuminating a mask disposed on the irradiated surface, exposing a pattern formed on the mask onto the photosensitive substrate To do.

A method of manufacturing a micro device of the present invention develops an exposure step of exposing a pattern of a mask on a photosensitive substrate using the exposure apparatus of the present invention, the photosensitive substrate exposed by the exposing step development And a process.

  According to the depolarizing element of the present invention, by combining two optical members that generate stress birefringence by applying stress from a predetermined direction, incident light can be transmitted without depending on the polarization direction of incident light. It can be reliably converted into non-polarized light.

  In addition, according to the depolarizing element of the present invention, by using an optical member that generates stress birefringence by applying stress from two different directions, incident light can be transmitted without depending on the polarization direction of incident light. It can be converted into non-polarized light.

  Further, according to the illumination optical device of the present invention, it is possible to reliably illuminate the non-irradiated surface with light in a non-polarized state without depending on the polarization direction of light from the light source. Further, since the stress applying means changes the magnitude of the stress based on the measurement result by the polarization state measuring device, the magnitude of the stress birefringence generated in the optical member can be made constant, and the incident light is made unpolarized. It can be reliably converted into light.

  Further, according to the method for adjusting an illumination optical apparatus of the present invention, the applied stress is changed in the applied stress change step, and the magnitude of the stress applied to the depolarization element is changed based on the measurement result in the polarization state measurement step. The magnitude of the stress birefringence can be made constant, and incident light can be reliably converted into non-polarized light.

  Further, according to the exposure apparatus of the present invention, the mask can be reliably illuminated with light in a non-polarized state, and good exposure can be performed under appropriate illumination conditions. Further, according to the method for manufacturing a microdevice of the present invention, the mask can be reliably illuminated with light in a non-polarized state, and good exposure can be performed under appropriate illumination conditions, and thus good exposure is favorable. Microdevices can be manufactured.

Hereinafter, a first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to the first embodiment of the present invention. As shown in FIG. 1, the exposure apparatus according to this embodiment includes a light source 1 for supplying exposure light (illumination light). As the light source 1, for example, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, an ArF excimer laser light source that supplies light with a wavelength of 193 nm, an F ₂ laser light source that supplies light with a wavelength of 157 nm, or the like is used. it can. A substantially parallel light beam having a predetermined degree of polarization emitted from the light source 1 is shaped into a light beam having a predetermined rectangular cross section via the beam transmission system 2 and then enters the depolarization element 3.

  Here, the degree of polarization V is expressed by the following equation (a). In equation (a), S0 is the total intensity, S1 is the horizontal linear polarization intensity minus the vertical linear polarization intensity, S2 is the 45 degree linear polarization intensity minus the 135 degree linear polarization intensity, and S3 is the clockwise circular polarization intensity minus counterclockwise. Each represents the intensity of circularly polarized light.

V = (S1 ² + S2 ² + S3 ² ) ^1/2 / S0 (a)
The beam transmission system 2 guides the incident light beam to the depolarization element 3 while converting the incident light beam into a light beam having a cross section of an appropriate size and shape, and actively activates position fluctuation and angle fluctuation of the light beam incident on the depolarization element 3. It has a function to correct. On the other hand, the depolarizing element 3 has a function of converting incident light having a degree of polarization (for example, linearly polarized light in this embodiment) into substantially non-polarized light.

  FIG. 2 is a diagram schematically showing the configuration of the depolarizer 3. As shown in FIG. 2, the depolarizing element 3 includes a first declination prism 31 formed of fluorite (calcium fluoride), which is a birefringent crystal material, in order from the light source side along the optical axis AX; A first correction declination prism 32 formed of fluorite, a second declination prism 33 formed of fluorite, and a second correction declination prism 34 formed of fluorite are provided. In addition, a stress applying mechanism 35 that applies stress from a predetermined direction to the first declination prism 31 and the second declination prism 33 constituting the depolarizing element 3 is provided. The stress applying mechanism 35 includes a pressing mechanism or a pulling mechanism that applies stress in a predetermined crystal axis direction to the first deflection prism 31 and the second deflection prism 33. When stress is applied by the stress applying mechanism 35, the first deflection prism 31 and the second deflection prism 33 are distorted and have birefringence in a distribution substantially perpendicular to the stress application direction. . As will be described later, since the first deflection prism 31 and the second deflection prism 33 are wedge-shaped optical members, the thicknesses of the members differ from place to place. Since the thickness of the birefringent optical member is different for each portion, the effect as a wave plate is different for each place where light is transmitted. When light having a polarization component having a direction different by 45 degrees from the direction perpendicular to the stress applying direction is incident, the first deflection prism 31 and the second deflection prism 33 are λ // according to the thickness of the portion through which the light is transmitted. It functions as an R wave plate (R is an arbitrary real number).

FIG. 3 is a diagram for explaining the crystal axis of fluorite. As shown in FIG. 3, the crystal axis of fluorite is defined based on the cubic crystal axis a ₁ a ₂ a ₃ (indicated by the thin line arrows in the figure). That is, the crystal axes along the crystal axis + _{a 1} [100], the crystal axes along the crystal axis + _{a 2} [010], the crystal axes along the crystal axis + _{a 3} [001] are defined respectively (in FIG thick arrow ). Further, the crystal axis [101] that forms 45 degrees with the crystal axis [100] and the crystal axis [001] in the a ₁ a ₃ plane, and 45 degrees with the crystal axis [100] and the crystal axis [010] in the a ₁ a ₂ plane. The crystal axis [110] is defined in the direction that forms the crystal axis [011], and the crystal axis [011] is defined in the direction that forms 45 degrees with the crystal axis [010] and the crystal axis [001] in the a ₂ a ₃ plane. Show). Further, the crystal axis [111] is defined in the + direction of the crystal axes a ₁ a ₂ a _{3 and in} the direction that forms the same angle as the crystal axis [100], the crystal axis [010], and the crystal axis [001] ( (Indicated by bold arrows in the figure). In FIG. 3, only the crystal axes in the space defined by the crystal axis + a ₁ , the crystal axis + a ₂ , and the crystal axis + a ₃ are illustrated, but the crystal axes are similarly defined in other spaces.

  The stress applying mechanism 35 described above has the crystal axis [100], the crystal axis [010], the crystal axis [010] among the crystal axes defined in FIG. 3 with respect to the first deflection prism 31 and the second deflection prism 33. Stress is applied in any one of the crystal axis [001], the crystal axis [110], the crystal axis [101], and the crystal axis [011]. By applying stress in the crystal axis direction, stress birefringence can be effectively generated in the first deflection prism 31 and the second deflection prism 33.

  Here, the first deflection angle prism 31 and the second deflection angle prism 33 have a function of converting incident light having a polarization degree into substantially non-polarized light. Further, the first correction declination prism 32 has a function of correcting the declination action by the first declination prism 31, and the second correction declination prism 34 corrects the declination action by the second declination prism 33. It has the function to do.

  The first deflection prism 31 is a wedge-shaped optical member having a rectangular shape when viewed from the optical axis AX direction (see FIG. 4A). The first deflection prism 31 has an apex direction set upward in the drawing, and as shown in FIG. 4, stress (indicated by arrows in the drawing) is applied from the left and right directions in the drawing by the stress applying mechanism 35. . The stress application directions are the crystal axis [100], the crystal axis [010], the crystal axis [001], the crystal axis [110], the crystal axis [101], among the crystal axes of fluorite shown in FIG. The direction is any one of the crystal axes [011].

  Similarly to the first deflection angle prism 31, the first correction deflection prism 32 has a rectangular shape when viewed from the optical axis AX direction, and has a wedge shape having a shape complementary to the first deflection angle prism 31. This is an optical member. The first correction declination prism 32 has an apex angle direction set downward in the drawing. That is, a parallel plate is configured by combining the first deflection angle prism 31 and the first correction deflection angle prism 32. Accordingly, the bending of the light beam due to the declination effect of the first declination prism 31 is restored by the declination effect of the first correction declination prism 32.

  The second declination prism 33 is a wedge-shaped optical member having a rectangular shape when viewed from the optical axis direction (see FIG. 4B). The second declination prism 33 is set so that the apex direction rotates 45 degrees clockwise from the upward direction in the figure around the optical axis AX, and as shown in FIG. Stress (indicated by an arrow in the figure) is applied from a direction orthogonal to the apex direction. The stress application directions are the crystal axis [100], the crystal axis [010], the crystal axis [001], the crystal axis [110], the crystal axis [101], among the crystal axes of fluorite shown in FIG. The direction is any one of the crystal axes [011].

  Similarly to the second deflection prism 33, the second correction deflection prism 34 has a rectangular shape when viewed from the direction of the optical axis AX, and has a wedge shape having a shape complementary to the second deflection prism 33. This is an optical member. The second correction declination prism 34 is set so that the apex angle direction is rotated 45 degrees clockwise from the downward direction in the figure. That is, a parallel plate is formed by combining the second declination prism 33 and the second correction declination prism 34. Therefore, the bending of the light beam due to the declination action of the second declination prism 33 is restored by the declination action of the second correction declination prism 34.

  In the depolarizing element 3 of this embodiment, the stress application directions (first direction) and the second deflection prisms made of fluorite, which is a birefringent crystal material, that is, the first deflection prism 31 and the second deflection prism 3 are used. The stress applying direction (second direction) of the declination prism 33 is set to form an angle of 45 degrees with each other when viewed from the optical axis AX direction. Further, the apex angle direction of the first declination prism 31 and the apex direction of the second declination prism 33 are different from each other when viewed from the optical axis AX direction and are not opposite to each other, that is, from the optical axis AX direction. They are set to cross each other at an angle of 45 degrees. Therefore, the light incident on the depolarizing element 3 is reliably converted into non-polarized light without depending on the polarization direction of the incident light.

  The substantially parallel light flux converted into the non-polarized state via the depolarization element 3 enters the microlens array (or fly-eye lens) 4. The microlens array 4 is an optical element composed of a large number of microlenses having positive refractive power arranged vertically and horizontally and densely. For example, the microlens array 4 is formed by etching a parallel plane plate to form a microlens group. The Here, each microlens constituting the microlens array 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, the microlens array is formed integrally with a large number of microlenses (microrefractive surfaces) without being isolated from each other. However, the microlens array is an optical integrator of the same wavefront division type as that of the fly-eye lens in that lens elements having positive refractive power are arranged vertically and horizontally. In place of the microlens array 4, an optical integrator such as a diffractive optical element or a prismatic rod integrator can be used.

  The light beam incident on the microlens array 4 is two-dimensionally divided by a large number of minute lenses, and a light source is formed on the rear focal plane of each minute lens on which the light beam is incident. Thus, a substantial surface light source (hereinafter referred to as “secondary light source”) composed of a large number of light sources is formed on the rear focal plane of the microlens array 4. The light beam from the secondary light source formed on the rear focal plane of the microlens array 4 is limited by an aperture stop (not shown) arranged as necessary, and receives the light condensing action of the condenser optical system 5. The mask M on which the predetermined pattern is formed is illuminated in a superimposed manner.

  The light beam that has passed through the pattern of the mask M forms an image of the mask pattern on the wafer W, which is a photosensitive substrate, via the projection optical system PL. Thus, by performing batch exposure or scan exposure while driving and controlling the wafer W placed on the wafer stage WS in a two-dimensional manner within a plane orthogonal to the optical axis AX of the projection optical system PL, each wafer W The pattern of the mask M is sequentially exposed in the exposure area.

  In the depolarizing element 3 according to the present embodiment, as shown in FIG. 4, the stress application direction (direction of a predetermined crystal axis) with respect to the first declination prism 31 is set in the left-right direction in the drawing. Therefore, when linearly polarized light having a polarization plane in a direction that forms an angle of 45 degrees with respect to the direction of the crystal axis is incident on the first declination prism 31, a phase shift amount different depending on the light passing position is given. As a result, depolarization is possible. However, when linearly polarized light having a polarization plane in a direction that forms an angle of 90 degrees or 0 degrees with respect to the crystal axis direction is incident on the first declination prism 31, the polarization state does not change at all. It passes through and remains depolarized.

  Similarly, as shown in FIG. 4, the stress application direction (predetermined crystal axis direction) with respect to the second declination prism 33 is set in the direction of an angle of 45 degrees clockwise from the upper direction of the figure. Therefore, when linearly polarized light having a polarization plane in a direction that forms an angle of 45 degrees with respect to the direction of the crystal axis is incident on the second declination prism 33, a different amount of phase shift is given depending on the light passing position, As a result, depolarization is possible. However, when linearly polarized light having a polarization plane in a direction forming an angle of 90 degrees or 0 degrees with respect to the crystal axis direction is incident on the second declination prism 33, the polarization state does not change at all. It passes through and remains depolarized.

  As described above, the first deflection prism 31 and the second deflection prism 33 each have linearly polarized light that cannot be depolarized. The crystal axis of the first deflection prism 31 and the second deflection prism 33 Since the crystal optical axes are set to form an angle of 45 degrees with each other, linearly polarized light that cannot be depolarized by the first declination prism 31 can be depolarized by the second declination prism 33. The linearly polarized light that cannot be depolarized by the second declination prism 33 is depolarized by the first declination prism 31. In other words, the first deflection prism 31 converts linearly polarized light having a polarization plane in a direction that cannot be converted into non-polarized light by the second deflection prism 33 into non-polarized light. Reference numeral 33 denotes a first polarization prism 31 configured to convert linearly polarized light having a polarization plane in a direction that cannot be converted into non-polarized light into non-polarized light.

  The operational effect of the depolarizer 3 when linearly polarized light is incident has been described above, but the first declination prism is not limited to linearly polarized light, regardless of whether the incident light is elliptical or circularly polarized. The second deflection prism 33 converts the incident light in a polarization state that cannot be converted into non-polarized light by the second deflection prism 33 into non-polarization light. The second deflection prism 33 is the first deflection prism 31. Incident light in a polarization state that cannot be converted into non-polarized light is converted into non-polarized light.

  The wafer stage WS is detachably attached with a polarization state measuring device 6 for measuring the polarization state of illumination light (exposure light) with respect to the wafer W. FIG. 5 is a diagram schematically showing the internal configuration of the polarization state measuring device 6. The polarization state measuring device 6 includes a pinhole member 60 that can be positioned at or near the position of the wafer W. Here, when the polarization state measuring device 6 is used, the wafer W is retracted from the optical path. The light that has passed through the pinhole 60a of the pinhole member 60 becomes a substantially parallel light beam through the collimator lens 61, and after being reflected by the reflecting mirror 62, as a λ / 4 plate 63 and a polarizer as a phase shifter. And then reaches the detection surface 65a of the two-dimensional CCD 65.

  Here, the λ / 4 plate 63 and the polarization beam splitter 64 are configured to be rotatable about the optical axis. Thus, when the polarization degree of the illumination light with respect to the wafer W is not 0, the light intensity distribution on the detection surface 65a of the two-dimensional CCD 65 is changed by rotating the λ / 4 plate 63 around the optical axis. Therefore, the polarization state measuring device 6 detects a change in the light intensity distribution on the detection surface 65a while rotating the λ / 4 plate 63 around the optical axis, and the illumination on the wafer W is detected from the detection result by the rotational phase shifter method. The polarization state of light (and consequently illumination light for the mask M) can be measured.

  The rotational phase shifter method is described in detail in, for example, Tsuruta, “Pencil of Light-Applied Optics for Optical Engineers”, New Technology Communications Inc. Actually, the polarization state of the illumination light at a plurality of positions in the wafer surface is measured while the pinhole member 60 (and thus the pinhole 60a) is moved two-dimensionally along the wafer surface. At this time, since the polarization state measuring device 6 detects a change in the light intensity distribution on the two-dimensional detection surface 65a, the distribution of the polarization state in the pupil of the illumination light can be measured based on this detection distribution information. it can.

  In the polarization state measuring device 6, the polarization state of the light may change due to the polarization characteristics of the reflecting mirror 62. In this case, since the polarization characteristic of the reflecting mirror 62 is known in advance, the measurement result of the polarization state measuring device 6 is corrected based on the influence of the polarization characteristic of the reflecting mirror 62 on the polarization state by a required calculation, and the illumination light The polarization state can be accurately measured.

  In the present embodiment, the polarization state of the illumination light on the wafer W (and consequently the illumination light on the mask M) is measured at any time using the polarization state measuring device 6 described above, and the almost complete depolarization effect is obtained by the action of the depolarization element 3. Can be confirmed. If the desired depolarization effect is not obtained, optical adjustment of the depolarization element 3 is performed so as to reliably convert the incident polarized light into non-polarized light without depending on the polarization direction of the incident polarized light. Can do. That is, the stress is applied to the first deflection prism 31 and the second deflection prism 33 by adjusting the magnitude of stress applied to the first deflection prism 31 and the second deflection prism 33 by the stress application mechanism 35. Adjust the magnitude of stress birefringence. Thus, the incident polarized light can be reliably converted into non-polarized light without depending on the polarization direction of the incident polarized light.

  In the above embodiment, an example is shown in which the correction declination prism (32, 34) that performs the axis correction of the declination prism (31, 33) is arranged downstream of the declination prism (31, 33). However, for example, the arrangement order of the declination prisms (31, 33) and the correction declination prisms (32, 34) may be reversed. That is, in the present invention, there is no limitation on the order of arrangement of the deflection prisms (31, 33) and the correction deflection prisms (32, 34), and it goes without saying that they may be arranged in any order.

  In the above-described embodiment, the bending of the light beam due to the deflection action of the first deflection prism 31 is corrected by the deflection action of the first correction deflection prism 32, and the deflection action of the second deflection prism 33 is used. Although the bending of the light beam is corrected by the declination action of the second correction declination prism 34, the combined declination of the first declination prism 31 and the second declination prism 33 using one correction declination prism. You may make it compensate an effect | action. In this case, the bending of the light beam due to the declination action of the first declination prism 31 and the second declination prism 33 is restored to the original by the declination action of the correction declination prism. Since the first declination prism 31 and the second declination prism 33 have birefringence, they have two different refractive indexes n1 and n2 (n1> n2). Therefore, the deviation angle of the light beam by the first deflection angle prism 31 and the second deflection angle prism 33 is calculated assuming that the refractive index is (n1 + n2) / 2, and correction is made so as to cancel the deviation angle of the light beam obtained by the calculation. The declination angle of the declination prism may be determined.

  In the above-described embodiment, the stress applying directions of the first deflection prism 31 and the second deflection prism 33 are configured to form an angle of 45 degrees with respect to the optical axis AX direction. When a depolarizing element is configured using three or more declination prisms, the angle is not limited to 45 degrees. That is, for example, when a depolarizing element is configured using three declination prisms, as a result of the phase shifting action by the three declination prisms, the center of gravity of the curved surface on the Poincare sphere representing the polarization state of the emitted light is If the crystal optical axis direction is set so as to be in the center, it is possible to obtain almost complete depolarization effect.

  In the above-described embodiment, the two declination prisms (31, 33) having birefringence are formed of fluorite. However, the present invention is not limited to this, and two declination prisms can be formed using a birefringent crystal material such as magnesium fluoride, barium fluoride, strontium fluoride, and calcite. Also in this case, birefringence can be effectively generated in the deflection prism by applying stress to the deflection prism from a predetermined crystal axis direction. Alternatively, the declination prism may be formed using an amorphous material such as quartz. By applying stress to the declination prism using an amorphous material from a predetermined direction, birefringence having a predetermined value can be generated inside the declination prism. In this case, if the predetermined direction is, for example, a direction crossing the optical axis, particularly a direction orthogonal to the optical axis, birefringence can be effectively generated.

  In the above-described embodiment, the first deflection prism 31 and the second deflection prism 33 are formed using fluorite. However, the first deflection prism 31 and the second deflection prism 33 are provided. These may be formed using different materials. That is, the first declination prism 31 is made of a birefringent crystal material such as calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride and calcite, or an amorphous material such as quartz. And the second declination prism 33 is formed of a birefringent crystal material such as calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride and calcite, or quartz. Other ones of non-crystalline materials may be used.

  In the above-described embodiment, the first correction declination prism 32 and the second correction declination prism 34 are formed using fluorite, which is a birefringent crystal material. You may form using a crystalline material.

  In the above-described embodiment, the depolarizing element 3 shown in FIG. 2 is used, but the depolarizing element 320 shown in FIGS. 6 and 7 may be used. Here, FIG. 6 is a perspective view of the depolarizing element 320, and FIG. 7 is a side view of the depolarizing element 320.

  The depolarization element 320 is formed of a first correction cylindrical lens 321 having a convex shape and formed of fluorite (calcium fluoride), which is a birefringent crystal material, in order from the light source side along the optical axis AX. A first cylindrical lens 322 having a concave shape is formed, a second correction cylindrical lens 323 having a convex shape formed by fluorite, and a second cylindrical lens 324 having a concave shape formed by fluorite. In addition, the depolarizing element 320 is provided with a stress applying mechanism (not shown) that applies stress to the first cylindrical lens 322 and the second cylindrical lens 324 from a predetermined direction. The stress applying mechanism includes a pressing mechanism or a pulling mechanism that applies stress to the first cylindrical lens 322 and the second cylindrical lens 324 in a predetermined crystal axis direction. When a stress is applied in a direction perpendicular to the generatrix G of the cylindrical lens by the stress applying mechanism, the first cylindrical lens 322 and the second cylindrical lens 324 are distorted, and are almost the same as the generatrix G of the cylindrical lens. It becomes birefringent in the parallel distribution. FIG. 8 shows the stress application direction (indicated by an arrow in the figure) to the first cylindrical lens 322 and the second cylindrical lens 324 and the distortion generated by the application of the stress (indicated by a solid line parallel to the generatrix G in the figure). . Since the first cylindrical lens 322 and the second cylindrical lens 324 are concave cylindrical optical members, the thicknesses of the members differ from place to place. Since the thickness of the birefringent optical member is different for each portion, the effect as a wave plate is different for each place where light is transmitted. When light having a polarization component that is 45 degrees different from the direction of the generatrix G is incident, the first cylindrical lens 322 and the second cylindrical lens 324 function as a λ / R wavelength plate according to the thickness of the portion through which the light is transmitted ( R is an arbitrary real number).

  The stress applying mechanism described above is based on the crystal axis [100], the crystal axis [010], the crystal axis [of the crystal axes defined in FIG. 3 with respect to the first cylindrical lens 322 and the second cylindrical lens 324 [ 001], the crystal axis [110], the crystal axis [101], and the crystal axis [011] are applied with stress in any one direction.

  Here, the first cylindrical lens 322 and the second cylindrical lens 324 have a function of converting incident light having a degree of polarization into substantially non-polarized light. Further, the first correction cylindrical lens 321 has a function of correcting the declination action by the first cylindrical lens 322, and the second correction cylindrical lens 323 has a function of correcting the declination action by the second cylindrical lens 324. .

  The first correction cylindrical lens 321 is an optical member having a convex cylinder shape. The first cylindrical lens 322 is an optical member having a concave cylinder shape that is complementary to the first correction cylindrical lens 321. As shown in FIG. 6, stress (indicated by an arrow in the figure) is applied to the first cylindrical lens 322 from a direction perpendicular to the generatrix G by a stress applying mechanism. The stress application directions are the crystal axis [100], the crystal axis [010], the crystal axis [001], the crystal axis [110], the crystal axis [101], among the crystal axes of fluorite shown in FIG. The direction is any one of the crystal axes [011].

  The second correction cylindrical lens 323 is an optical member having a convex cylinder shape. The second cylindrical lens 324 is an optical member having a concave cylinder shape that is complementary to the second correction cylindrical lens 323. As shown in FIG. 6, stress (indicated by an arrow in the figure) is applied to the second cylindrical lens 324 from a direction perpendicular to the generatrix G by a stress applying mechanism. The stress application directions are the crystal axis [100], the crystal axis [010], the crystal axis [001], the crystal axis [110], the crystal axis [101], among the crystal axes of fluorite shown in FIG. The direction is any one of the crystal axes [011].

  In the depolarizing element 320 of this embodiment, the direction of the bus G of the first cylindrical lens 322 and the direction of the bus G of the second cylindrical lens 324 formed of fluorite, which is a birefringent crystal material, They are set to form an angle of 45 degrees with each other when viewed from the axis AX direction. Therefore, this depolarizing element 320 also has a function of converting incident light having a degree of polarization into substantially non-polarized light without depending on the polarization direction of the incident light. The depolarizing element 320 has a function of converting incident light having a degree of polarization into substantially non-polarized light by applying stress to the two concave cylindrical lenses. Type cylindrical lens has a function of correcting the declination effect of the two concave cylindrical lenses, but by applying stress to the two convex cylindrical lenses, incident light having a polarization degree is substantially reduced. A function of converting the light into non-polarized light may be provided, and the two concave cylindrical lenses may be provided with a function of correcting the declination effect of the two convex cylindrical lenses.

  In the above embodiment, an example is shown in which the corrected cylindrical lenses (321, 323) that perform axial correction of the cylindrical lenses (322, 324) are arranged upstream of the cylindrical lenses (322, 324). The arrangement order of the cylindrical lenses (322, 324) and the correction cylindrical lenses (321, 323) may be reversed. That is, in the present invention, there is no limitation on the order of arrangement of the cylindrical lenses (321, 323) and the correction cylindrical lenses (321, 323), and it goes without saying that these may be arranged in any order.

  In the above-described embodiment, the depolarizing element shown in FIG. 9 may be used. Here, FIG. 9 shows a first declination prism 310, a first correction declination prism 320, a second declination prism 330, and a second correction declination prism 340 that constitute a depolarizing element. This depolarizing element is arranged in order from the light source side along the optical axis AX, a first declination prism 310 made of fluorite (calcium fluoride), which is a birefringent crystal material, and a first declination prism 310 made of fluorite. The first correction declination prism 320, the second declination prism 330 formed of fluorite, and the second correction declination prism 340 formed of fluorite are arranged. The first declination prism 310, the first correction declination prism 320, the second declination prism 330, and the second correction declination prism 340 that constitute this depolarization element are the first depolarization element 3 shown in FIG. The shape of the first declination prism 31, the first correction declination prism 32, the second declination prism 33, and the second correction declination prism 34 as viewed from the optical axis AX direction is changed to a circular shape. The arrangement position of the declination prism, the stress application direction, and the like are the same as those of the depolarizing element 3 shown in FIG.

  Also in this depolarizing element, the first deflection prism 310 and the second deflection prism 330 convert incident light having a degree of polarization into substantially non-polarized light without depending on the polarization direction of the incident light. It has a function. Further, the first correction declination prism 320 has a function of correcting the declination action by the first declination prism 310, and the second correction declination prism 340 corrects the declination action by the second declination prism 330. It has the function to do.

  In the above-described embodiment, the depolarizing element shown in FIG. 10 may be used. Here, FIG. 10 shows the first declination prism 311, the first correction declination prism 321, the second declination prism 331, and the second correction declination prism 341 that constitute the depolarization element. This depolarizing element has a first declination prism 311 made of fluorite (calcium fluoride), which is a birefringent crystal material, in order from the light source side along the optical axis AX, and a first declination prism 311 made of fluorite. The first correction declination prism 321, the second declination prism 331 formed of fluorite, and the second correction declination prism 341 formed of fluorite are arranged. The first declination prism 311, the first correction declination prism 321, the second declination prism 331, and the second correction declination prism 341 constituting this depolarization element are the first depolarization element 3 shown in FIG. For the first deflection prism 31 and the second deflection prism 33, stress was applied to two opposing sides, that is, from two directions, while stress was applied to each side, that is, from four directions. The arrangement positions of the other declination prisms are the same as those of the depolarizing element 3 shown in FIG.

  Also in this depolarizing element, the first deflection prism 311 and the second deflection prism 331 convert incident light having a degree of polarization into substantially non-polarized light without depending on the polarization direction of the incident light. It has a function. The first correction declination prism 321 has a function of correcting the declination action by the first declination prism 311, and the second correction declination prism 341 corrects the declination action by the second declination prism 331. It has the function to do.

  In the above-described embodiment, the depolarizing element shown in FIG. 11 may be used. Here, FIG. 11 shows the first declination prism 312, the first correction declination prism 322, the second declination prism 332, and the second correction declination prism 342 that constitute the depolarization element. This depolarizing element has a first declination prism 312 made of fluorite (calcium fluoride), which is a birefringent crystal material, in order from the light source side along the optical axis AX, and a first declination prism 312 made of fluorite. The first correction declination prism 322, the second declination prism 332 formed of fluorite, and the second correction declination prism 342 formed of fluorite are arranged. The first declination prism 312, the first correction declination prism 322, the second declination prism 332, and the second correction declination prism 342 constituting the depolarization element are the first depolarization element 3 shown in FIG. The first deflection angle prism 31, the first correction deflection angle prism 32, the second deflection angle prism 33, and the second correction deflection angle prism 34 are changed to a circular shape when viewed from the optical axis AX direction. The angular prism 312 and the second deflection prism 332 are modified so as to apply stress from four directions. The arrangement positions of the other declination prisms are the same as those of the depolarizing element 3 shown in FIG.

  Also in this depolarizing element, the first deflection prism 312 and the second deflection prism 332 convert incident light having a degree of polarization into substantially non-polarized light without depending on the polarization direction of the incident light. It has a function. Further, the first correction declination prism 322 has a function of correcting the declination action by the first declination prism 312, and the second correction declination prism 342 corrects the declination action by the second declination prism 332. It has the function to do.

  Arrangement order of the declination prisms (310, 330, 311, 331, 312, 332) and the correction declination prisms (320, 340, 321, 341, 322, 342) in the embodiment shown in FIGS. Needless to say, there is no limitation, and they may be arranged in any order.

  In the above-described embodiment, the depolarizing element shown in FIG. 12 may be used. Here, FIG. 12 shows the first optical member 313 and the second optical member 333 constituting the depolarizing element. The depolarizing element includes a first optical member 313 composed of parallel plates formed of fluorite (calcium fluoride), which is a birefringent crystal material, in order from the light source side along the optical axis AX; A second optical member 333 composed of parallel flat plates formed of stone is arranged and configured. The first optical member 313 and the second optical member 333 constituting the depolarizing element have a rectangular shape when viewed from the optical axis direction, and non-uniform stress is applied to each side. Yes. The stress is applied in the crystal axis [100], crystal axis [010], crystal axis [001], crystal axis [110], crystal axis [101], crystal in the crystal axes of fluorite shown in FIG. The direction is any one of the axes [011]. Therefore, non-uniform distortion occurs in the first optical member 313 and the second optical member 333, and birefringence having a predetermined distribution therein occurs. Further, the first optical member 313 and the second optical member 333 are arranged in a state where the second optical member 333 is rotated by 45 degrees with respect to the first optical member 313. Therefore, in this depolarizing element, the first optical member 313 and the second optical member 333 function to convert incident light having a polarization degree into substantially non-polarized light without depending on the polarization direction of the incident light. Have

  In the above-described embodiment, the depolarizing element shown in FIG. 13 may be used. Here, FIG. 13 shows the first optical member 314 and the second optical member 334 constituting the depolarizing element. The depolarizer includes a first optical member 314 composed of parallel plates formed of fluorite (calcium fluoride), which is a birefringent crystal material, in order from the light source side along the optical axis AX, A second optical member 334 composed of parallel flat plates formed of stone is arranged and configured. The first optical member 314 and the second optical member 334 constituting this depolarizing element have a circular shape when viewed from the optical axis direction, and give a nonuniform stress to the periphery of the optical member. Has been. Therefore, non-uniform distortion occurs in the first optical member 314 and the second optical member 334, and birefringence having a predetermined distribution therein occurs. The stress is applied in the crystal axis [100], crystal axis [010], crystal axis [001], crystal axis [110], crystal axis [101], crystal in the crystal axes of fluorite shown in FIG. The direction is any one of the axes [011]. Further, the first optical member 314 and the second optical member 334 are arranged in a state where the second optical member 334 is rotated by 45 degrees with respect to the first optical member 314. Therefore, in this depolarizing element, the first optical member 314 and the second optical member 334 convert incident light having a degree of polarization into substantially non-polarized light without depending on the polarization direction of the incident light. It has a function.

  In the embodiment described above, a depolarizing element using the optical member shown in FIG. 14 may be used. Here, FIG. 14 shows an optical member constituting the depolarizing element. In the above-described embodiment, birefringence is generated in the optical member by applying stress to the side surface portion of the optical member constituting the depolarizing element from the predetermined optical axis direction. By applying stress to the two points on the back surface located on the point and the straight line (shown by the solid line in the figure) connecting the two points on the surface and the straight line (shown by the broken line in the figure), the optical member is non-uniform Distortion may be generated, and birefringence having a predetermined distribution inside may be generated. In this case as well, the stress is applied in the crystal axis [100], crystal axis [010], crystal axis [001], crystal axis [110], and crystal axis [101] among the crystal axes of fluorite shown in FIG. ] Or any one of the crystal axes [011]. By arranging two such optical members in a state rotated relatively by 45 degrees, incident light having a polarization degree is converted into substantially non-polarized light without depending on the polarization direction of the incident light. It has the function to do.

  Further, in the above-described embodiment, by combining at least two optical members that generate birefringence by applying stress, incident light having a polarization degree can be obtained without depending on the polarization direction of incident light. When the light is converted into substantially non-polarized light, but non-uniform birefringence can be generated inside as in the optical member shown in FIGS. 12 to 14, the distribution of birefringence to be generated. By controlling this, incident light having a degree of polarization can be converted into substantially non-polarized light by one optical member without depending on the polarization direction of the incident light.

  In the above-described embodiment, the depolarizing element 3 is disposed in the optical path between the beam transmission system 2 and the microlens array 4. However, the present invention is not limited to this. For example, the condenser optical system 5 It is also possible to arrange the depolarizing element 3 in the optical path between the mask and the mask M or in another suitable optical path. However, by adopting a configuration in which an optical integrator is disposed in the optical path between the depolarizing element 3 and the mask M, the effective diameter (outer diameter) of the depolarizing element 3 can be kept small.

  In the above-described embodiment, it is preferable that the depolarizing element 3 is configured to be detachable with respect to the illumination optical path. In this case, if necessary, the depolarizing element 3 is set in the illumination optical path to illuminate the mask M with unpolarized light, and the depolarizing element 3 is retracted from the illumination optical path to linearly polarized light. Thus, the mask M can be illuminated, and various illuminations can be applied to the mask M.

  Next, an exposure apparatus including an illumination optical system according to the second embodiment of the present invention will be described with reference to the drawings. FIG. 15 is a drawing schematically showing a configuration of an exposure apparatus provided with an illumination optical apparatus according to the second embodiment of the present invention. In FIG. 15, the Z axis along the normal direction of the wafer W, which is a photosensitive substrate, the Y axis in the direction parallel to the paper surface of FIG. 15 in the wafer surface, and perpendicular to the paper surface of FIG. 15 in the wafer surface. The X axis is set for each direction. In FIG. 15, the illumination optical device is set to perform annular illumination.

  The exposure apparatus includes a laser light source 10 for supplying exposure light (illumination light). For example, an ArF excimer laser light source that supplies light having a wavelength of 193 nm can be used as the laser light source 10. A substantially parallel light beam emitted from the laser light source 10 along the Z direction has a rectangular cross section extending along the X direction and is incident on a beam expander 11 including a pair of lenses 11a and 11b. Each lens 11a and 11b has a negative refracting power and a positive refracting power in the plane of FIG. 15 (in the YZ plane), respectively. Therefore, the light beam incident on the beam expander 11 is enlarged in the plane of FIG. 15 and shaped into a light beam having a predetermined rectangular cross section.

  The substantially parallel light beam via the beam expander 11 as the shaping optical system is deflected in the Y direction by the bending mirror 12 and then passed through the phase member 13, the depolarizer (depolarization element) 14, and the diffractive optical element 15. The light enters the afocal zoom lens 16. The configuration and operation of the phase member 13 will be described later. The configuration and operation of the depolarizer (depolarization element) 14 are the same as the configuration and operation of the depolarization element 3 according to the first embodiment. In this embodiment, FIG. 2, FIG. 7 to FIG. The depolarizing element described using 14 can be used.

  In general, a diffractive optical element is formed by forming a step having a pitch of the wavelength of exposure light (illumination light) on a substrate, and has a function of diffracting an incident beam to a desired angle. Specifically, the diffractive optical element 15 has a function of forming a circular light intensity distribution in the far field (or Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section is incident.

  Therefore, the light beam passing through the diffractive optical element 15 forms a circular light intensity distribution, that is, a light beam having a circular cross section at the pupil position of the afocal zoom lens 16. The diffractive optical element 15 is configured to be retractable from the illumination optical path. The afocal zoom lens 16 is configured so that the magnification can be continuously changed within a predetermined range while maintaining an afocal system (non-focus optical system). The light beam that has passed through the afocal zoom lens 16 enters a diffractive optical element 17 for annular illumination. The afocal zoom lens 16 optically couples the divergence origin of the diffractive optical element 15 and the diffractive surface of the diffractive optical element 17 optically in a conjugate manner. The numerical aperture of the light beam condensed on one point of the diffractive surface of the diffractive optical element 17 or a surface in the vicinity thereof changes depending on the magnification of the afocal zoom lens 16.

  The diffractive optical element 17 for annular illumination has a function of forming a ring-shaped light intensity distribution in the far field when a parallel light beam is incident. The diffractive optical element 17 is configured to be detachable with respect to the illumination optical path, and includes a diffractive optical element 60 for quadrupole illumination, a diffractive optical element 61 for circular illumination, a diffractive optical element 62 for X-direction dipole illumination, It is configured to be switchable with a diffractive optical element 63 for Y-direction dipole illumination. By using a diffractive optical element 60 for quadrupole illumination, a diffractive optical element 61 for circular illumination, a diffractive optical element 62 for X direction dipole illumination, and a diffractive optical element 63 for Y direction dipole illumination, a quadrupole is obtained. Illumination, circular illumination, X direction dipole illumination, and Y direction dipole illumination can be performed.

  The light beam that has passed through the diffractive optical element 17 enters the zoom lens 18. In the vicinity of the rear focal plane of the zoom lens 18, the incident surface of the micro fly's eye lens (or fly eye lens) 19 is positioned. The micro fly's eye lens 19 is an optical element composed of a large number of microlenses having positive refractive powers arranged vertically and horizontally and densely. In general, a micro fly's eye lens is configured by, for example, performing etching treatment 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 formed integrally with a large number of micro lenses (micro refractive surfaces) without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly eye lens in that lens elements having positive refractive power are arranged vertically and horizontally.

  As described above, the light beam from the circular light intensity distribution formed at the pupil position of the afocal zoom lens 16 via the diffractive optical element 15 is emitted from the afocal zoom lens 16 and then has various angles. A light beam having a component enters the diffractive optical element 17. That is, the diffractive optical element 15 constitutes an optical integrator having an angular light beam forming function. On the other hand, the diffractive optical element 17 has a function as a light beam conversion element that forms a ring-shaped light intensity distribution in the far field when a parallel light beam is incident. Therefore, the light beam that has passed through the diffractive optical element 17 forms a ring-shaped illumination field around the optical axis AX, for example, on the rear focal plane of the zoom lens 18 (and thus on the incident surface of the micro fly's eye lens 19). .

  The outer diameter of the annular illumination field formed on the incident surface of the micro fly's eye lens 19 varies depending on the focal length of the zoom lens 18. Thus, the zoom lens 18 substantially connects the diffractive optical element 17 and the incident surface of the micro fly's eye lens 19 in a Fourier transform relationship. The light beam incident on the micro fly's eye lens 19 is two-dimensionally divided, and the rear focal plane of the micro fly's eye lens 19 has a ring-shaped multiple light source (hereinafter referred to as “two-lens”) as the illumination field formed by the incident light beam. Next light source ") is formed.

  The light beam from the annular secondary light source formed on the rear focal plane of the micro fly's eye lens 19 illuminates the mask blind 23 in a superimposed manner after passing through the beam splitter 21 and the condenser optical system 22. Thus, a rectangular illumination field corresponding to the shape and focal length of each microlens constituting the micro fly's eye lens 19 is formed on the mask blind 23 as an illumination field stop. The internal configuration and operation of the polarization monitor 20 incorporating the beam splitter 21 will be described later.

  The light beam that has passed through the rectangular opening (light transmission portion) of the mask blind 23 is subjected to the light condensing action of the imaging optical system 24, and then superimposed on the mask (reticle) M1 on which a predetermined pattern is formed. Illuminate. Thus, the imaging optical system 24 forms an image of the rectangular opening of the mask blind 23 on the mask M1. The light beam that has passed through the pattern of the mask M1 forms an image of the mask pattern on the wafer W1, which is a photosensitive substrate, via the projection optical system PL1. Thus, the pattern of the mask M1 is formed in each exposure region of the wafer W1 by performing batch exposure or scan exposure while controlling the wafer W2 in a two-dimensional manner in a plane orthogonal to the optical axis AX of the projection optical system PL1. Sequential exposure is performed.

  FIG. 16 is a diagram schematically showing the configuration of the phase member 13 and the depolarizer 14. The phase member 13 is composed of a half-wave plate whose crystal axis is rotatable around the optical axis AX. On the other hand, the depolarizing element 14 has the same configuration as the depolarizing element 3 (see FIG. 2 and the like) according to the first embodiment as described above. As shown in FIG. 15, the rotation of the phase member 13 around the optical axis AX and the insertion / removal of the depolarization element 14 with respect to the illumination optical path are performed by a drive system 26 that receives a command from the control system 25. In addition, the drive system 26 has a function as a stress applying mechanism that applies stress to the optical member that constitutes the depolarization element 14. The drive system 26 receives an instruction from the control system 25 and serves as an optical member that constitutes the depolarization element 14. Make adjustments such as changing the magnitude of the stress to be applied.

  When an ArF excimer laser light source is used as the laser light source 10, linearly polarized light is incident on the phase member 13 formed of a half-wave plate. Here, when the crystal axis of the phase member 13 is set to make an angle of 0 degrees or 90 degrees with respect to the plane of polarization of the linearly polarized light that is incident, the plane of polarization of the linearly polarized light incident on the phase member 13 is Pass through without change. In addition, when the crystal optical axis of the phase member 13 is set to form an angle of 45 degrees with respect to the polarization plane of the linearly polarized light incident thereon, the linearly polarized light incident on the phase member 13 has a polarization plane of only 90 degrees. It is converted into light with changed linear polarization. Further, the linearly polarized light incident on the depolarizing element 14 is converted into non-polarized light (depolarized).

  In the present embodiment, as described above, linearly polarized light from the laser light source 10 is incident on the phase member 13. However, in order to simplify the following description, P-polarized light is incident on the phase member 13. It shall be. In this case, when the drive system 25 inserts the depolarization element 14 into the illumination optical path and is set so that the crystal axis of the phase member 13 forms an angle of 0 degree or 90 degrees with respect to the polarization plane of the P-polarized light incident thereon. The P-polarized light incident on the phase member 13 passes through the P-polarized light without changing the polarization plane and enters the depolarization element 14. The P-polarized light incident on the depolarization element 14 is converted into light in a non-polarized state, and illuminates the mask M in the non-polarized state. On the other hand, when the drive system 25 inserts the depolarizing element 14 into the illumination optical path and the crystal optical axis of the phase member 13 is set to make an angle of 45 degrees with respect to the polarization plane of the P-polarized light, the phase member The polarization plane of the P-polarized light incident on 13 changes by 90 degrees, and becomes S-polarized light and enters the depolarization element 14. The S-polarized light incident on the depolarizing element 14 is converted into light in a non-polarized state, and illuminates the mask M in the non-polarized state.

  On the other hand, when the drive system 26 retracts the depolarizing element 14 from the illumination optical path and is set so that the crystal axis of the phase member 13 forms an angle of 0 degree or 90 degrees with respect to the polarization plane of the P-polarized light incident thereon. The P-polarized light incident on the phase member 13 passes through the P-polarized light without changing the polarization plane, and illuminates the mask M with the P-polarized light. On the other hand, when the drive system 26 retracts the depolarization element 14 from the illumination optical path and the angle of 45 degrees is formed with respect to the polarization plane of the P-polarized light on which the crystal axis of the phase member 13 is incident, The incident P-polarized light changes its polarization plane by 90 degrees to become S-polarized light, and illuminates the mask M with S-polarized light.

  FIG. 17 schematically shows an internal configuration of the polarization monitor 20 for detecting whether or not the polarization state of the light that illuminates the mask M (and thus the wafer W) as the irradiated surface is a desired polarization state. It is a perspective view. As shown in FIG. 15, the polarization monitor 20 includes a first beam splitter 21 disposed in the optical path between the micro fly's eye lens 19 and the condenser optical system 22. The first beam splitter 21 has a form of an uncoated parallel flat plate (that is, a bare glass) formed of, for example, quartz glass, and has a function of extracting reflected light having a polarization state different from the polarization state of incident light from the optical path. .

  The light extracted from the optical path by the first beam splitter 21 enters the second beam splitter 27. Similar to the first beam splitter 21, the second beam splitter 27 has a form of a non-coated parallel flat plate made of, for example, quartz glass, and generates reflected light having a polarization state different from the polarization state of incident light. It has a function. The P-polarized light for the first beam splitter 21 is set to be S-polarized light for the second beam splitter 27, and the S-polarized light for the first beam splitter 21 is set to be P-polarized light for the second beam splitter 27.

  The light transmitted through the second beam splitter 27 is detected by the first light intensity detector 28, and the light reflected by the second beam splitter 27 is detected by the second light intensity detector 29. The outputs of the first light intensity detector 28 and the second light intensity detector 29 are respectively supplied to the control system 25 (see FIG. 15). Further, as described above, the control system 25 drives the phase member 13 and the depolarization element 14 constituting the polarization state switching means via the drive system 26.

  As described above, in the first beam splitter 21 and the second beam splitter 27, the reflectance for P-polarized light and the reflectance for S-polarized light are substantially different. Therefore, in the polarization monitor 20, the reflected light from the first beam splitter 21 is, for example, about 10% of the S-polarized component of the incident light to the first beam splitter 21 (the S-polarized component with respect to the first beam splitter 21, P-polarized component for the two beam splitter 27) and, for example, a P-polarized component of about 1% of the incident light on the first beam splitter 21 (P-polarized component for the first beam splitter 21 and S-polarized light for the second beam splitter 27) Component).

  The reflected light from the second beam splitter 27 is, for example, a P-polarized component of about 10% × 1% = 0.1% of the incident light to the first beam splitter 21 (a P-polarized component with respect to the first beam splitter 21). The S-polarized component for the second beam splitter 27) and the S-polarized component of about 1% × 10% = 0.1% of the incident light to the first beam splitter 21 (the S-polarized component for the first beam splitter 21). And a P-polarized component for the second beam splitter 27).

  Thus, in the polarization monitor 20, the first beam splitter 21 has a function of extracting reflected light having a polarization state different from the polarization state of incident light from the optical path according to the reflection characteristics. As a result, the output of the first light intensity detector 28 (information on the intensity of the transmitted light of the second beam splitter 27, that is, the first beam splitter is slightly affected by the polarization fluctuation due to the polarization characteristic of the second beam splitter 27. The polarization state (polarization degree) of the incident light to the first beam splitter 21 and the polarization state of the illumination light to the mask M based on the information on the intensity of the light having the same polarization state as the reflected light from the light 21. Can be detected.

  The polarization monitor 20 is set so that the P-polarized light for the first beam splitter 21 becomes S-polarized light for the second beam splitter 27 and the S-polarized light for the first beam splitter 21 becomes P-polarized light for the second beam splitter 27. ing. As a result, the polarization of the incident light to the first beam splitter 21 based on the output of the second light intensity detector 29 (information on the intensity of the light sequentially reflected by the first beam splitter 21 and the second beam splitter 27). The light quantity (intensity) of the incident light on the first beam splitter 21 and the light quantity of the illumination light on the mask M can be detected without being substantially affected by the change in state. In this way, the polarization monitor 20 is used to detect the polarization state of the light incident on the first beam splitter 21, and as a result, it is determined whether or not the illumination light to the mask M is in a desired non-polarization state or linear polarization state. can do. When the control system 25 confirms that the illumination light to the mask M (and thus the wafer W) is not in the desired non-polarized state or linearly polarized state based on the detection result of the polarization monitor 20, the drive system 26 is turned on. Then, the phase member 13 and the depolarization element 14 constituting the polarization state switching means are driven and adjusted, and the state of the illumination light on the mask M is adjusted to a desired non-polarization state or linear polarization state. In addition, the illumination light applied to the mask M should be in a non-polarized state, and the reason why the light is not unpolarized is due to an insufficient amount of stress applied to the optical member constituting the depolarizer 14 In this case, under the control of the drive system 26, the magnitude of the stress applied to the optical member is changed, and the illumination light applied to the mask M is brought into a non-polarized state.

In the above-described embodiment, KrF excimer laser light, ArF excimer laser light, or F ₂ laser light is used as the exposure light. However, the present invention is not limited to this. The present invention can be applied to any suitable light source. In the above-described embodiment, the projection exposure apparatus provided with the illumination optical apparatus has been described as an example. However, the present invention is applied to a general illumination optical apparatus for illuminating an irradiated surface other than the mask. Is also possible.

  In the exposure apparatus according to the above-described embodiment, a mask (reticle) is illuminated by an illumination optical apparatus (illumination process), and a transfer pattern formed on the mask is exposed to a photosensitive substrate using a projection optical system ( By the exposure step, a micro device (semiconductor element, imaging element, liquid crystal display element, thin film magnetic head, etc.) can be manufactured. FIG. 18 is a flowchart of an example of a method 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 above-described embodiment. The description will be given with reference.

  First, in step S301 in FIG. 18, a metal film is deposited on one lot of wafers. In the next step S302, a photoresist is applied on the metal film on the wafer of the l lot. After that, in step S303, 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 using the exposure apparatus of the above-described embodiment. Thereafter, in step S304, the photoresist on the one lot of wafers is developed, and in step S305, the resist pattern is etched on the one lot of wafers to form a pattern on the mask. Corresponding circuit patterns are formed in each shot area on each wafer. Thereafter, a device pattern such as a semiconductor element is 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.

  In the exposure apparatus of the above-described embodiment, a liquid crystal display element as a micro device can be obtained by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on a plate (glass substrate). Hereinafter, an example of the technique at this time will be described with reference to the flowchart of FIG. In FIG. 19, in the pattern forming step S401, a so-called photolithography step is performed in which the exposure pattern of the above-described embodiment is used to transfer and expose a mask pattern onto a photosensitive substrate (such as a glass substrate coated with a resist). . By this photolithography 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 various processes such as a developing process, an etching process, and a resist stripping process, whereby a predetermined pattern is formed on the substrate, and the process proceeds to the next color filter forming process S402.

  Next, in the color filter forming step S402, a large number of groups of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix, or three of R, G, and B are arranged. A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning line direction. Then, after the color filter formation step S402, a cell assembly step S403 is executed. In the cell assembly step S403, a liquid crystal panel (liquid crystal cell) is assembled using the substrate having the predetermined pattern obtained in the pattern formation step S401, the color filter obtained in the color filter formation step S402, and the like.

  In the cell assembling step S403, for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in the pattern forming step S401 and the color filter obtained in the color filter forming step S402. ). Thereafter, in a module assembly step S404, components such as an electric circuit and a backlight for performing a display operation of the assembled liquid crystal panel (liquid crystal cell) are attached to complete a liquid crystal display element. According to the above-described method for manufacturing a liquid crystal display element, a liquid crystal display element having an extremely fine circuit pattern can be obtained with high throughput.

1 is a drawing schematically showing a configuration of an exposure apparatus according to a first embodiment of the present invention. It is a block diagram of the depolarizing element concerning the 1st Embodiment of this invention. It is a figure for demonstrating the crystal axis of a fluorite. It is a figure for demonstrating the optical member which comprises the depolarizing element concerning the 1st Embodiment of this invention. It is a figure which shows schematically the internal structure of the polarization state measuring device concerning the 1st Embodiment of this invention. It is a figure which shows roughly the structure of the modification of the depolarizing element concerning embodiment. It is a figure which shows roughly the structure of the modification of the depolarizing element concerning embodiment. It is a figure for demonstrating the distortion which generate | occur | produces in the optical member which comprises the depolarizing element concerning embodiment. It is a figure which shows the structure of the modification of the depolarizing element concerning embodiment. It is a figure which shows the structure of the modification of the depolarizing element concerning embodiment. It is a figure which shows the structure of the modification of the depolarizing element concerning embodiment. It is a figure which shows the structure of the modification of the depolarizing element concerning embodiment. It is a figure which shows the structure of the modification of the depolarizing element concerning embodiment. It is a figure which shows the modification of the optical member which comprises the depolarizing element concerning embodiment. It is a figure which shows schematically the structure of the exposure apparatus concerning the 2nd Embodiment of this invention. It is a block diagram of the phase member and depolarizing element concerning the 2nd Embodiment of this invention. It is a figure which shows the structure of the change monitor concerning the 2nd Embodiment of this invention. It is a flowchart explaining the manufacturing method of the semiconductor device as a microdevice concerning embodiment of this invention. It is a flowchart for demonstrating the manufacturing method of the liquid crystal display element as a micro device concerning embodiment of this invention. It is a figure which shows schematically the structure of the conventional depolarizing element. It is a figure which shows how the Stokes parameter of an emitted light changes with angle (theta) of the polarization direction of incident light, when angle (phi) of the crystal optical axis direction of a 1st deflection angle prism is set to 45 degree | times. It is a figure which shows how the Stokes parameter of an emitted light changes with angle (theta) of the polarization direction of incident light when the angle (phi) of the crystal optical axis direction of a 1st deflection prism is set to 22.5 degree | times. is there. It is a figure explaining the effect | action of the conventional depolarizing element using a Stokes parameter and a Poincare sphere. It is a figure explaining the disadvantage of the conventional depolarizing element using a Stokes parameter and a Poincare sphere.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Light source, 2 ... Beam transmission system, 3 ... Depolarization element, 4 ... Micro lens array (fly eye lens), 5 ... Condenser optical system, 6 ... Polarization state measuring device, 31 ... 1st deflection angle prism, 32 ... 1st correction declination prism, 33 ... 2nd declination prism, 34 ... 2nd correction declination prism, 320 ... Depolarization element, 321 ... 1st correction cylindrical lens, 322 ... 1st cylindrical lens, 323 ... 2nd Corrected cylindrical lens, 324 ... second cylindrical lens, M ... mask, PL ... projection optical system, W ... wafer

Claims (26)

A depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light,
At least two optical members disposed along the optical axis;
Stress is applied to at least one of the at least two optical members from a first direction, and stress is applied to at least one other of the at least two optical members from a second direction different from the first direction. A stress applying means for applying
At least one of the at least two optical members has a first declination prism, and at least one other of the at least two optical members has a second declination prism,
The depolarizing element, wherein apex angle directions of the first declination prism and the second declination prism are set so as to be different from each other and not opposite to each other when viewed from the direction of the optical axis.   2. The depolarizing element according to claim 1, wherein at least one of the at least two optical members is made of a crystal material, and a direction in which stress is applied by the stress applying unit is a predetermined crystal axis direction.   3. The depolarizing element according to claim 1, wherein crystal axes of the at least two optical members are set to form an angle of 45 degrees with each other when viewed from the optical axis direction.   The first deflection angle prism and the second deflection angle prism are set so that the apex direction intersects at an angle of approximately 45 degrees. The depolarizing element as described in 2.   5. The correction declination prism according to any one of claims 1 to 4, further comprising a correction declination prism for compensating for a combined declination action by the first declination prism and the second declination prism. The depolarizing element as described.   The depolarizing element according to claim 5, wherein the correction declination prism is made of a birefringent material.   A first correction declination prism for correcting the declination action by the first declination prism and a second correction declination prism for correcting the declination action by the second declination prism are further provided. The depolarizing element according to any one of claims 1 to 6, wherein the depolarizing element. The first correction declination prism and the second correction declination prism are formed of a birefringent material,
The depolarization element includes the first declination prism, the first correction declination prism, the second declination prism, and the second correction declination prism. The depolarizing element as described.   The at least two declination prisms are any of quartz, which is an amorphous material, quartz, which is a birefringent crystal material, calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride, and calcite. The depolarizing element according to claim 1, wherein the depolarizing element is formed by:   2. The stress applying unit includes at least one of a pressing mechanism and a tension mechanism that applies stress in the predetermined direction of the first deflection prism and the second deflection prism. The depolarizing element according to any one of 9. At least one of the at least two optical members has a first cylindrical lens, and at least one other of the at least two optical members has a second cylindrical lens;
The buses of the first cylindrical lens and the second cylindrical lens are set to face different directions as seen from the direction of the optical axis,
3. The depolarizing element according to claim 1, wherein the stress applying unit applies stress in a direction perpendicular to a generatrix of the first cylindrical lens and the second cylindrical lens. 4.   The material of at least one of the first cylindrical lens and the second cylindrical lens is a crystal material, and a predetermined crystal axis is set in a direction perpendicular to the generatrix. Depolarizing element.   13. The generatrix according to claim 11 or 12, wherein the generating lines of the first cylindrical lens and the second cylindrical lens are set to form an angle of 45 degrees with respect to the optical axis direction. Depolarizing element.   14. The depolarizing element according to claim 11, further comprising a correcting cylindrical lens for compensating for a combined declination effect by the at least two cylindrical lenses.   It further comprises a first correction cylindrical lens for correcting a declination effect by the first cylindrical lens, and a second correction cylindrical lens for correcting a declination effect by the second cylindrical lens. The depolarizing element according to any one of claims 11 to 13. The first correction cylindrical lens and the second correction cylindrical lens are formed of a birefringent material,
The depolarization element according to claim 15, wherein the depolarization element includes the first correction cylindrical lens, the first cylindrical lens, the second correction cylindrical lens, and the second cylindrical lens. element.   The stress applying means has at least one of a pressing mechanism and a tension mechanism for applying stress in a predetermined crystal axis direction set in a direction perpendicular to the generatrix of the first cylindrical lens and the second cylindrical lens, respectively. The depolarizing element according to claim 16.   The at least two cylindrical lenses are made of any one of quartz that is an amorphous material, quartz that is a birefringent crystal material, calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride, and calcite. The depolarizing element according to any one of claims 11 to 17, wherein the depolarizing element is formed. A depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light,
At least two optical members disposed along the optical axis;
Stress is applied to at least one of the at least two optical members from a first direction, and stress is applied to at least one other of the at least two optical members from a second direction different from the first direction. A stress applying means for applying
At least one of the at least two optical members has a first deflection prism, and at least one other of the at least two optical members has a second deflection prism, and the first deflection prism. And the apex directions of the second declination prisms are set so as to be different from each other and not opposite to each other when viewed from the direction of the optical axis,
The at least two declination prisms are any one of quartz that is an amorphous material, quartz that is a birefringent crystal material, calcium fluoride, magnesium fluoride, barium fluoride, strontium fluoride, and calcite. The depolarizing element characterized by being formed by these. A depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light,
At least two optical members disposed along the optical axis;
Stress is applied to at least one of the at least two optical members from a first direction, and stress is applied to at least one other of the at least two optical members from a second direction different from the first direction. A stress applying means for applying
At least one of the at least two optical members has a first deflection prism, and at least one other of the at least two optical members has a second deflection prism, and the first deflection prism. And the apex directions of the second declination prisms are set so as to be different from each other and not opposite to each other when viewed from the direction of the optical axis,
The depolarizing element, wherein the stress applying means includes at least one of a pressing mechanism and a tension mechanism that applies stress in the predetermined direction of the first deflection prism and the second deflection prism. A depolarizing element for converting incident light having a degree of polarization into substantially non-polarized light,
At least two optical members disposed along the optical axis;
Stress is applied to at least one of the at least two optical members from a first direction, and stress is applied to at least one other of the at least two optical members from a second direction different from the first direction. A stress applying means for applying
At least one of the at least two optical members has a first cylindrical lens, and at least one other of the at least two optical members has a second cylindrical lens;
The buses of the first cylindrical lens and the second cylindrical lens are set to face different directions as seen from the direction of the optical axis,
The depolarizing element according to claim 1, wherein the stress applying unit applies stress in a direction perpendicular to a generatrix of the first cylindrical lens and the second cylindrical lens.   The predetermined crystal axis is any one of a crystal axis [100], a crystal axis [010], a crystal axis [001], a crystal axis [110], a crystal axis [101], and a crystal axis [011]. The depolarizing element according to any one of claims 1 to 21, wherein the depolarizing element is provided. In an illumination optical apparatus including a light source that supplies light having a degree of polarization, and a light guide optical system that irradiates the irradiated surface with light from the light source,
23. An illumination optical apparatus, wherein the light guide optical system includes the depolarizing element according to any one of claims 1 to 22. A polarization state measuring device for measuring the polarization state of the light that has passed through the depolarizing element,
The illumination optical apparatus according to claim 23, wherein the stress applying unit changes the magnitude of the stress based on a measurement result by the polarization state measuring apparatus. The illumination optical device according to claim 23 or 24 for illuminating a mask arranged on the irradiated surface,
An exposure apparatus that exposes a pattern formed on the mask onto a photosensitive substrate. An exposure step of exposing a pattern of a mask onto a photosensitive substrate using the exposure apparatus according to claim 25;
A developing step of developing the photosensitive substrate exposed by the exposing step;
A method for manufacturing a microdevice, comprising:

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