JP2014135357A - Illumination optical system and illumination method, polarization unit, and light exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical system having a high degree of freedom for changing a polarization state.SOLUTION: An illumination optical system ILS illuminating a reticle surface Ra with illumination light IL from a light source 10, comprises: a spatial optical modulator 22 having a plurality of mirror elements 24 arranged on an arrangement surface P1, and forming light intensity distribution to an illumination pupil of the illumination optical system ILS; an optical rotation member 29B arranged between the arrangement surface P1 and the reticle surface Ra, and changing a polarization state of at least a part of light toward the reticle surface Ra via the spatial optical modulator 22; and a birefringent member 31B arranged between the arrangement surface P1 and the reticle surface Ra, and that is a uniaxial birefringent crystal with no optical rotation, and that is arranged so that its optical axis is parallel to an optical axis AXI of the illumination optical system ILS.

Description

  The present invention relates to an illumination technique for illuminating a surface to be irradiated, a polarization unit used for controlling the polarization state of light, an exposure technique using the illumination technique, and a device manufacturing technique using the exposure technique.

  In a typical exposure apparatus of this type, light emitted from a light source is a secondary light source (illumination pupil) as a substantial surface light source composed of a large number of small light sources via, for example, a fly-eye lens as an optical integrator. A light intensity distribution). The surface on which the illumination pupil is formed (illumination pupil surface) is illuminated by the action of the optical system between the illumination pupil surface and the illuminated surface (reticle (mask) pattern surface in the case of an exposure apparatus). It can also be defined as a position where the plane is the Fourier transform plane of the illumination pupil plane. The light from the illumination pupil forms an image of a reticle pattern on the surface of a photosensitive substrate such as a wafer via the optical system, reticle, and projection optical system. Hereinafter, the light intensity distribution on the illumination pupil plane or a plane conjugate thereto is also referred to as a pupil intensity distribution.

  Conventionally, in order to control the distribution of the polarization state in the illumination pupil, which is one of the illumination conditions, according to the pattern of the reticle, an annular or multipolar illumination pupil is formed, and an aperture stop with a wavelength plate is formed. And a technique for setting the polarization state of a light beam passing through the illumination pupil to a linear polarization state (hereinafter, also referred to as a circumferential polarization state) having a polarization direction substantially in the circumferential direction with respect to the optical axis has been proposed. (For example, see Patent Document 1).

Japanese Patent No. 3246615

  Recently, in order to realize illumination conditions suitable for faithfully transferring various patterns of fine patterns, the degree of freedom in changing the shape (wide concept including size) and polarization state of the pupil intensity distribution has been improved. It is desired. However, in the prior art described in Patent Document 1, the shape of the pupil intensity distribution and the polarization state cannot be changed unless the aperture stop with the wave plate is replaced.

  The present invention has been made in view of the above-described problems, and an object thereof is to obtain a high degree of freedom regarding a change in polarization state.

  According to the first aspect of the present invention, in an illumination optical system that illuminates a surface to be irradiated with light from a light source, the light that is disposed within a predetermined plane and forms a light intensity distribution on the illumination pupil of the illumination optical system An optical power that changes the polarization state of at least part of the light that is disposed between the intensity distribution forming member and the predetermined surface and the irradiated surface and that is directed to the irradiated surface through the light intensity distribution forming member. A first rotatory member formed of an optical material having a uniaxial birefringent crystal without optical rotation disposed between a predetermined surface and an irradiated surface, the optical axis of which is the illumination optical An illumination optical system is provided that includes an adjustment member that is arranged to be parallel to the optical axis of the system.

According to the second aspect, the illumination optical system according to the aspect of the present invention for illuminating a predetermined pattern is provided, and the predetermined pattern is exposed on the photosensitive substrate using light from the illumination optical system. An exposure apparatus is provided.
Further, according to the third aspect, the polarization that controls the polarization state of the light beam that is arranged in the predetermined plane and that is emitted through the light intensity distribution forming member that forms the light intensity distribution on the illumination pupil of the illumination optical system. An optical material which is a unit and is arranged in the optical path of light emitted from the light intensity distribution forming member and has an optical rotation property that changes the polarization state of at least part of the light emitted from the light intensity distribution forming member A uniaxial birefringent crystal having no optical rotation, the optical axis of the illumination optical system being arranged in the optical path of light emitted from the first optical rotation member formed from the light intensity distribution forming member And an adjusting member arranged to be parallel to the optical axis of the polarizing unit.

  According to the fourth aspect, in the illumination method for illuminating the illuminated surface with the light from the light source, the light intensity distribution is formed in the predetermined plane and forms the light intensity distribution on the illumination pupil of the illumination optical system. Supplying light from the light source to the member and using the first optical rotation member formed of an optical material having optical activity, at least a part of the light intensity distribution forming member toward the irradiated surface A uniaxial birefringent crystal having no optical rotation, which is disposed between the predetermined surface and the irradiated surface, and whose optical axis is the light of the illumination optical system. Adjusting the polarization state of at least a part of the light toward the irradiated surface using an adjusting member arranged to be parallel to the axis.

Moreover, according to the 5th aspect, the exposure method which illuminates a predetermined pattern using the illumination method of the aspect of this invention and exposes the predetermined pattern to a photosensitive substrate is provided.
According to the sixth aspect, the exposure apparatus or the exposure method of the aspect of the present invention is used to expose the predetermined pattern on the photosensitive substrate, and the photosensitive property to which the predetermined pattern is transferred. Developing a substrate, forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate, and processing the surface of the photosensitive substrate through the mask layer A manufacturing method is provided.

  According to the aspect of the present invention, the cooperative action of the light intensity distribution forming member and the first optical rotation member makes it possible to obtain a high degree of freedom for changing the polarization state without replacing the optical member. Furthermore, when the polarization state at the time of emission of light (obliquely incident light) incident on the first optical rotation member with a relatively large incident angle changes with respect to the polarization state at the time of emission of normal incident light, the first By adjusting the polarization state of the incident incident light with the adjusting member on the incident side or the exit side of the optical rotation member, it is possible to match the polarization state when the oblique incident light is emitted with the polarization state when the perpendicular incident light is emitted. It becomes.

(A) is a view showing a schematic configuration of an exposure apparatus according to an example of the embodiment, (B) is an enlarged view showing a main part of the polarization control system in FIG. 1 (A), and (C) is a polarization control of a modification. It is an enlarged view which shows the principal part of a system | strain. (A) is an enlarged perspective view showing a part of mirror elements of an SLM (spatial light modulator), (B) is a diagram showing a polarization state of a light beam incident on the SLM, and (C) is a distribution of polarization states of an illumination pupil. (D) is a figure which shows another example of distribution of the polarization state of an illumination pupil. (A) is a diagram showing an array of mirror elements of the SLM in FIG. 1, (B) is a diagram showing another example of a partial array region of the SLM, (C) is a diagram showing a polarization control system, (D) is It is a figure which shows the state which driven the polarization control system. It is a perspective view which shows the principal part of an illumination optical system. (A) is a perspective view showing a change in the polarization state of a plurality of lights that have passed through the optical rotation member of the second polarization unit, (B) is a diagram showing the polarization state of a plurality of lights incident on the optical rotation member, (C) FIG. 5 is a diagram showing a polarization state of a plurality of lights emitted from an optical rotation member. (A) is a perspective view which shows the change of the polarization state of the some light which passed the optical rotation member and birefringent member of the 2nd polarization unit, (B) shows the polarization state of the some light which injects into a birefringent member. FIG. 4C is a diagram showing the polarization state of a plurality of lights emitted from the birefringent member. (A) is a perspective view showing a change in the polarization state of a plurality of lights that have passed through the optical rotation member of the third polarization unit, (B) is a diagram showing the polarization state of a plurality of lights incident on the optical rotation member, (C) FIG. 5 is a diagram showing a polarization state of a plurality of lights emitted from an optical rotation member. (A) is a perspective view which shows the change of the polarization state of the several light which passed the optical rotation member and birefringent member of the 3rd polarizing unit, (B) shows the polarization state of the several light which injects into a birefringent member. FIG. 4C is a diagram showing the polarization state of a plurality of lights emitted from the birefringent member. It is a flowchart which shows an example of the illumination method and the exposure method. (A) is a perspective view showing an essential part of a polarization control system of a modification, (B) is a diagram showing a polarization state of light emitted from a correction optical rotation member in FIG. 10 (A), and (C) is polarized light. The side view which shows the modification of a unit, (D) is a side view which shows another modification of a polarizing unit. It is a flowchart which shows the manufacturing process of a semiconductor device.

Hereinafter, an exemplary embodiment will be described with reference to FIGS. FIG. 1A shows a schematic configuration of an exposure apparatus EX according to the present embodiment. The exposure apparatus EX includes a projection optical system PL. Hereinafter, the exposure apparatus EX has a Z-axis parallel to the optical axis AX of the projection optical system PL, and in a direction perpendicular to the plane of FIG. 1A on a plane perpendicular to the Z-axis. The X axis will be described by taking the Y axis in a direction parallel to the paper surface.
In FIG. 1A, an exposure apparatus EX uses a light source 10 that generates illumination light (exposure light) IL for exposure, and a pattern surface (here, the lower surface) Ra of the reticle R using the illumination light IL from the light source 10. Is provided with an illumination optical system ILS and a reticle stage RST that holds and moves the reticle R. Further, the exposure apparatus EX includes a projection optical system PL that forms an image of the pattern of the reticle R on the surface of a semiconductor wafer (hereinafter simply referred to as a wafer) W as a photosensitive substrate, and a wafer that holds and moves the wafer W. A stage WST, a main control unit 38 comprising a computer that controls the overall operation of the apparatus, and an illumination control unit 36 that controls the illumination conditions of the illumination optical system ILS under the control of the main control unit 38 are provided. ing. The illumination optical system ILS of the present embodiment cooperates with a spatial light modulator (SLM) 22 for controlling the pupil intensity distribution of illumination light, and the spatial light modulator 22, and the illumination pupil of illumination light Is provided with a polarization control system 28 for controlling the distribution of the polarization state.

  As the light source 10, an ArF excimer laser light source that supplies pulsed light having a wavelength of 193 nm is used. However, as the light source 10, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, a solid-state laser light source (such as a YAG laser or a semiconductor laser), or a harmonic generator for laser light can also be used. The illumination light IL emitted from the light source 10 has a polarization state in which linearly polarized light along a certain direction according to the configuration of the light source 10 is a main component. Here, a polarization state mainly composed of linearly polarized light along a certain direction is a state in which the ratio of the intensity of linearly polarized light in that direction to the total light intensity (degree of polarization) is 80% or more. Can do. In this specification, linearly polarized light in a certain direction includes light in a polarization state whose main component is linearly polarized light along that direction.

  The linearly polarized illumination light IL emitted in the + Z direction from the light source 10 is reflected in the + Y direction by the mirror MR1 after the cross-sectional shape is controlled by the beam transmission system 12, and as an example, a rectangle having the X direction as the longitudinal direction. Is incident on the illumination optical system ILS as a parallel light beam having a cross section 50 (see FIG. 2B). The illumination light incident on the illumination optical system ILS is first incident on the polarization setting system 14 and the entire polarization state is set to a desired state. The polarization setting system 14 includes, as an example, a half-wave plate 15A, a quarter-wave plate 15B, and a pair of optical optical elements arranged in a non-parallel state and having optical rotation, respectively. A non-polarizing element 15C that emits non-polarized light (random polarized light) and a drive unit DR1 are included. As an example, the wave plates 15A and 15B are always installed in the optical path (illumination optical path) of the illumination light IL, and their rotation angles are controlled by the drive unit DR1. On the other hand, the non-polarizing element 15C is installed in the illumination optical path by the drive unit DR1 only when the illumination light IL is unpolarized. In the present embodiment, when the polarization state of the illumination light IL is controlled using the polarization control system 28, the non-polarization element 15C is retracted outside the illumination optical path, and the rotation angles of the wave plates 15A and 15B are The light after passing through the wave plates 15A and 15B is set to be linearly polarized light in the X direction or the Z direction (two directions orthogonal to each other in the cross section of the light beam).

Hereinafter, a state where light traveling in the + Y direction is linearly polarized in the Z direction is referred to as longitudinally polarized light DV, and a state where light linearly polarized in the X direction is referred to as laterally polarized light DH. As an example, the illumination light IL that has passed through the polarization setting system 14 is linearly polarized light (longitudinal polarization DV) in the Z direction (the direction corresponding to the Y direction in the pattern surface Ra of the reticle R) as shown in FIG. Suppose that
As the polarization setting system 14, a polarization state switching unit disclosed in US Pat. No. 7,423,731 that can control the polarization direction and / or polarization degree of a light beam can be used. .
In FIG. 1A, the illumination light IL made up of parallel light beams that has passed through the polarization setting system 14 is reflected obliquely upward (in the −Y direction and the + Z direction) by the mirror MR2, and is referred to as a spatial light modulator (hereinafter referred to as SLM). ) Is incident on a plurality of mirror elements 24. The illumination light IL reflected by the plurality of mirror elements 24 in the direction centered on the + Y direction is incident on the polarization control system 28 via the relay optical system 26 including the front lens group 26a and the rear lens group 26b. . In the present embodiment, the direction of the optical axis AXI of the illumination optical system ILS is parallel to the Y axis (Y direction) between the mirrors MR1 and MR2 and between the SLM 22 and the polarization control system 28.

  The SLM 22 has a main body portion 23 having a support surface parallel to the array surface P1, which is a plane rotated by a predetermined small angle clockwise about an axis parallel to the X axis with respect to a surface perpendicular to the Y axis, A plurality of mirror elements 24 that are supported on the supporting surface of the main body 23 and arranged on the array surface P1 in the X direction and in a direction orthogonal to the X direction (substantially in the Z direction) at predetermined intervals and individually controlled. Further, the SLM 22 is tilted around two axes orthogonal to each other (may be crossed obliquely) in the array plane P <b> 1 as the postures of the plurality of mirror elements 24 based on the control signal from the illumination control unit 36. A drive unit 25 that individually controls the angles θx and θz (see FIG. 2A) is provided. The number of arrangements of the mirror elements 24 in the X direction and the direction orthogonal to the X direction is, for example, several tens to several hundreds, for example, and the mirror elements 24 are, for example, square (or rectangular) and are dense so that the gap is as small as possible. It is arranged. The mirror element 24 does not necessarily have to be square (or rectangular). Since the angle of each mirror element 24 changes, the arrangement plane P1 is assumed to be a plane on which the centers of the plurality of mirror elements 24 are arranged as an example. The normal direction of the array plane P1 intersects the optical axis of the light incident on the SLM 22 and the optical axis AXI of the light reflected and emitted from the SLM 22 (parallel to the Y axis in this portion) at the same angle.

  In the present embodiment, the illumination light IL of longitudinally polarized light DV consisting of parallel light beams reflected by the mirror MR1 is a rectangular irradiation region 50A that is long in the X direction on the arrangement plane P1 of the SLM 22 (see FIG. 3A). Are incident on the array plane P1 in the state of P-polarized PP. Note that the irradiation region 50A is actually set on the array of mirror elements 24. In this case, the P-polarized light is defined as an incident surface including a light beam incident obliquely on the array surface P1 and a normal line of the array surface P1 passing through the incident point of the light beam. That is, it is linearly polarized light having a polarization direction in a parallel direction (polarized light having an electric vector oscillating in a direction parallel to the incident surface). The light reflected by each mirror element 24 in the irradiation region 50A enters the relay optical system 26 in the state of longitudinally polarized light DV (P-polarized light with respect to the array plane P1) polarized in the Z direction.

  Note that the illumination light IL may be incident on the arrangement plane P1 of the SLM 22 in the state of S-polarized light SP (which is also laterally polarized light DH in this embodiment). The S-polarized light in this case means that the light beam incident obliquely on the array plane P1 is linearly polarized light having a polarization direction in a direction perpendicular to the incident surface. The light incident on the array plane P1 in the S-polarized state enters the relay optical system 26 in the state of laterally polarized light DH (S-polarized with respect to the array plane P1) that is reflected in the X direction after being reflected by each mirror element 24.

In addition, the angle of each mirror element 24 changes with respect to the direction parallel to the array plane P1, but the amount of change is substantially smaller than the incident angle of the illumination light IL with respect to the array plane P1, so Alternatively, light incident as S-polarized light can be considered to be incident as approximately P-polarized light or S-polarized light on each mirror element 24.
In general, in a reflecting member such as the mirror element 24, the reflectance and phase are slightly different between the P-polarized light and the S-polarized light with respect to the obliquely incident light beam, and the difference in the reflectance and the like varies depending on the incident angle. . For this reason, when linearly polarized light other than P-polarized light and S-polarized light is incident on the reflecting member obliquely, the polarization direction of the reflected light may change or the polarization state may change to elliptically polarized light. On the other hand, in this embodiment, the light incident on the arrangement plane P1 of the SLM 22 is P-polarized light or S-polarized light, and the polarization state of the reflected light is almost the same as that at the time of incidence. Can be controlled with high accuracy to the target distribution.

The angle of each mirror element 24 of the SLM 22 may be continuously changed, but discretely, for example, a plurality of angles (for example, an angle that changes in units of 0.5 degrees in each of two orthogonal axes, etc.) ) May be switched.
As the SLM 22 (spatial light modulator) of the present embodiment, for example, European Patent Publication No. 779530, US Pat. No. 5,867,302, US Pat. No. 6,600,591, US Pat. No. 900,915, U.S. Pat. No. 7,295,726, U.S. Pat. No. 7,567,375, Pamphlet of International Patent Publication No. 2010/037476, or JP-A-2006-113437. A spatial light modulator can be used. Such a spatial light modulator can also be manufactured using, for example, a so-called MEMS (Microelectromechanical Systems) technique.

  The light reflected by the plurality of mirror elements 24 of the SLM 22 forms a light intensity distribution on the pupil plane P2 of the relay optical system 26 via the front lens group 26a of the relay optical system 26, and then passes through the rear lens group 26b. Then, the light enters the polarization control system 28 at a rectangular cross section 50B (see FIG. 3C) whose longitudinal direction is the X direction. The inclination angles around the two axes of the plurality of mirror elements 24 of the SLM 22 define the positions of the light reflected by the mirror element 24 in the X direction and the Z direction on the pupil plane P2. For this reason, the light intensity distribution on the pupil plane P2 can be set to an almost arbitrary distribution two-dimensionally by individually controlling the inclination angles around the two axes of the plurality of mirror elements 24 of the SLM 22.

  As an example, the polarization control system 28 is a rectangle that is larger than the cross section 50B and emits the incident light with its polarization direction rotated by a first angle, a second angle, a third angle, and a fourth angle. The first, second, third, and fourth polarization units 30A, 30B, 30C, and 30D, and the polarization units 30A to 30D each having a plane parallel plate shape are individually moved so as to cross the illumination optical path. Have For example, the polarization units 30A to 30D are arranged in the + Y direction in the order of the polarization units 30D, 30C, 30B, and 30A, but the arrangement order is arbitrary.

  Moreover, the 1st-4th angle which is a rotation angle of the polarization direction in the polarization units 30A-30D is 22.5 degrees, 90 degrees, 45 degrees, and 90 degrees counterclockwise as an example. Even when the polarization direction of the incident light is rotated counterclockwise by θa or when the polarization direction is rotated clockwise by (180 degrees −θa), the polarization direction of the emitted light is the same. The first to fourth angles may be 157.5 degrees, 90 degrees, 135 degrees, and 90 degrees clockwise. Furthermore, as will be described later, the combination of the first to fourth angles is arbitrary, and the first to fourth angles are, for example, counterclockwise (or clockwise) 90 degrees, 22.5 degrees, 22 .5 degrees, 22.5 degrees, etc. are also possible.

  In this embodiment, as shown in FIG. 1B, the polarization units 30A, 30B, 30C, and 30D that constitute the polarization control system 28 have optical characteristics that rotate the polarization direction of the incident linearly polarized light, respectively. Plate-shaped optical rotatory members 29A, 29B, 29C, and 29D formed of an optical material having a certain optical rotation, and tabular birefringent members 31A, 31B, formed of uniaxial birefringent crystals having no optical rotation 31C and 31D are bonded together through a light-transmitting adhesive. For this reason, the polarization unit 30A (the optical rotation member 29A and the birefringent member 31A) is integrally driven by the drive unit DR2, and similarly, the other polarization units 30B to 30D are also integrally driven by the drive unit DR2 independently of each other. .

In the example of FIG. 1B, the birefringent members 31A to 31D are arranged on the illumination light exit side (downstream) with respect to the optical rotation members 29A to 29D. The refractive members 31A to 31D may be arranged on the incident light incident side (upstream). Further, the birefringent members 31A to 31D may be arranged at a slight interval in the Y direction with respect to the optical rotation members 29A to 29D. In this case, the optical rotation members 29A to 29D and the birefringent members 31A to 31D may be driven synchronously in a state where they are independently supported by the drive unit DR2.

  As the optical material of the optical rotation members 29A to 29D, a crystal material having optical activity, for example, a crystal that is a uniaxial crystal can be used. As the quartz crystal, either a left-rotating left crystal or a right-handing dextrorotatory right crystal can be used. The front surfaces (and consequently the rear surfaces from which the light beams are incident) of the optical rotation members 29A to 29D are orthogonal to the optical axis AXI, and their crystal optical axes (hereinafter simply referred to as optical axes) are parallel to the optical axis AXI ( That is, it is parallel to the Y direction, which is the traveling direction of incident light parallel to the optical axis AXI. Typically, the optical axis OAA of the optical rotation member 29B of the polarization unit 30B is parallel to the Y direction. The front surfaces (rear surfaces) of the optical rotation members 29A to 29D may be substantially orthogonal to the optical axis AXI, and the optical axes of the optical rotation members 29A to 29D may be substantially parallel to the Y direction.

In uniaxial crystals, the refractive index for the ordinary ray (hereinafter, ordinary referred refractive index) n _o is the principal refractive index with respect to extraordinary ray (hereinafter, extraordinary refractive index of) n _e smaller crystal (e.g. quartz) is positive crystal, ordinary refractive index n _o is the extraordinary refractive index n _e larger crystals are called negative crystals. When the optical rotators 29A to 29D are positive crystals, the optical axis is also a slow axis (in this case, the axis along the direction in which the phase velocity is slowest), and the fast axis (in the plane perpendicular to the optical axis) The axis along the direction in which the phase velocity is fastest in the plane). When the optical rotators 29A to 29D are negative crystals, the optical axis is also a fast axis (in this case, the axis along the direction in which the phase velocity is fastest), and the slow axis (in the plane perpendicular to the optical axis) The axis along the direction in which the phase velocity is the slowest in the plane).

  In a member (optical rotator or optical rotator) formed of an optical material having optical activity, incident linearly polarized light is emitted in a state where the polarization direction is rotated by an angle corresponding to the thickness of the optical rotator. Therefore, the thickness of the optical rotation members 29A to 29D is determined according to the rotation angle (first to fourth angles) of the polarization direction of the incident light in the polarization units 30A to 30D. Hereinafter, the rotation angle of the polarization direction by the optical polarization member of linearly polarized light is referred to as an angle of rotation. When the optical rotation angle is expressed only by a numerical value, the optical rotation angle with the sign + (positive) indicates the counterclockwise (counterclockwise) angle with respect to the light traveling direction, and the optical rotation angle with the sign-(negative) is It is assumed to represent a clockwise (clockwise) angle with respect to the light traveling direction. Further, an optical rotation angle without a sign in which the rotation direction is not particularly defined means that it may be either a counterclockwise or clockwise direction.

On the other hand, as the optical material of the birefringent members 31A to 31D, magnesium fluoride (MgF ₂ ), sapphire (a crystal of Al ₂ O ₃ which is aluminum oxide), or calcite, which is a uniaxial birefringent crystal without optical rotation, (CaCO ₃ crystal which is calcium carbonate) or the like can be used. The front surfaces of the birefringent members 31A to 31D on which light beams enter (and hence the rear surfaces from which the light beams exit) are orthogonal to the optical axis AXI, and their optical axes (crystal optical axes) are parallel to the optical axis AXI (that is, the optical axis AXI). Parallel to the Y direction, which is the traveling direction of the incident light parallel to. Typically, the optical axis OAB of the birefringent member 31B of the polarization unit 30B is parallel to the Y direction. The front surfaces (rear surfaces) of the birefringent members 31A to 31D may be substantially orthogonal to the optical axis AXI, and the optical axes of the birefringent members 31A to 31D may be substantially parallel to the Y direction. When the birefringent members 31A to 31D are positive crystals, the optical axis is also a slow axis, and there is a fast axis in a plane perpendicular to the optical axis. When the birefringent members 31A to 31D are negative crystals, the optical axis is also a fast axis, and there is a slow axis in a plane perpendicular to the optical axis.

Table 1 below relates to light having a wavelength of 193 nm (ArF light) with respect to quartz that can be used as an optical material for optical rotators 29A to 29D and magnesium fluoride and sapphire that can be used as optical materials for birefringent members 31A to 31D. ordinary refractive index n _o, indicating the data of the extraordinary refractive index n _e, and optical rotatory power [rho (optical rotation angle per unit length to parallel incident light on the optical axis [deg / mm]). Since magnesium fluoride and sapphire have no optical rotation, the optical rotation power ρ in Table 1 is 0, respectively. Moreover, quartz and magnesium fluoride <a (n _e, sapphire and calcite (Table 1 not published) negative crystals (n _o positive crystal n _o)> is a n _e).

  In the present embodiment, since the optical axes of the birefringent members 31A to 31D are parallel to the Y direction, they enter perpendicularly (in parallel to the optical axis AXI) to the front surfaces of the polarization units 30A to 30D (optical rotation members 29A to 29D). The birefringent members 31A to 31D do not have a birefringence action with respect to illumination light (hereinafter referred to as perpendicular incident light), and the birefringent members 31A to 31D act as a simple light-transmitting substrate. Further, the optical rotation members 29A to 29D rotate the polarization direction of the linearly polarized vertical incident light by a specified optical rotation angle and emit the linearly polarized light. For this reason, when linearly polarized vertically incident light passes through the polarization units 30A to 30D, it is emitted as linearly polarized light whose polarization direction is rotated by the optical rotation angle of the optical rotation members 29A to 29D.

  On the other hand, illumination light (hereinafter referred to as oblique incident light) incident on the front surfaces of the polarization units 30A to 30D (optical rotation members 29A to 29D) as linearly polarized light and inclined at an angle with respect to the optical axis AXI. When the light passes through the optical rotation members 29A to 29D, the polarization direction is rotated by the optical rotation angle, and the light is emitted in a polarization state slightly elliptically polarized according to the inclination angle with respect to the optical axis AXI. For obliquely incident light, the birefringent members 31A to 31D have different refractive indexes in two orthogonal polarization directions (P-polarized light and S-polarized light), so that the birefringent action of the birefringent members 31A to 31D occurs. become. The birefringence action increases as the inclination angle of the oblique incident light with respect to the optical axis AXI increases. Therefore, for obliquely incident light, the birefringent action of the birefringent members 31A to 31D is used to correct the light that has been elliptically polarized by the optical rotation members 29A to 29D to linearly polarized light. For this reason, the thicknesses of the birefringent members 31A to 31D are set according to the optical rotation angles (or thicknesses) of the corresponding optical rotation members 29A to 29D (details will be described later).

  In FIG. 1A, as an example, a surface between the central polarizing units 30C and 30B (or a surface between the front surface of the polarizing unit 30D and the rear surface of the polarizing unit 30A, or a surface in the vicinity of these surfaces may be used. ) Is the installation surface P3 of the polarization units 30A to 30D, the installation surface P3 is substantially perpendicular to the optical axis AXI. As shown in FIG. 4, since the thickness of the polarization units 30A to 30D is actually considerably smaller than the focal length of the rear lens group 26b, the polarization units 30A to 30D are almost entirely on the installation surface P3. Can be considered in position.

  Further, the center of the arrangement surface P1 of the SLM 22 is in the vicinity of the front focal position of the front lens group 26a of the relay optical system 26, and the rear focal position of the front lens group 26a and the front focal position of the rear lens group 26b are almost the same. The rear focal position of the rear lens group 26b is substantially at the center of the installation surface P3 of the polarization units 30A to 30D. Accordingly, the installation surface P3 and the arrangement surface P1 of the SLM 22 are optically conjugate with respect to the relay optical system 26, and the rectangular cross section 50B of the illumination light IL in FIG. 3C is the SLM 22 in FIG. Are substantially conjugate with the irradiation region 50A of the illumination light IL in the arrangement plane P1.

  For convenience of explanation, in FIG. 1A and FIG. 4 and the like, the region (array region) in which the mirror elements 24 of the SLM 22 are arranged is expressed larger than the actual shape. Actually, the width of the region where the mirror elements 24 are arranged is considerably smaller than the maximum diameter of the optical system such as the front lens group 26a. For this reason, it may be considered that the region where the mirror elements 24 are arranged is substantially in the vicinity of the optical axis AXI. Similarly, in the polarization units 30 </ b> A to 30 </ b> D, regions (partial regions C <b> 1 to C <b> 8 described later) irradiated with the illumination light IL can be regarded as being substantially in the vicinity of the optical axis AXI.

  As shown in FIG. 3C, the drive unit DR2 of the polarization control system 28 translates the polarization unit 30A in the Z direction (short-side direction) as an example with respect to the cross section 50B of the illumination light IL. The three polarization units 30B to 30D are translated independently in the X direction (long side direction). Further, the edge portion in the Z direction (movement direction) in the cross section 50B of the polarization unit 30A is substantially parallel to the edge portion in the Z direction (a linear portion substantially parallel to the X axis) of the outline of the cross section 50B. The edge portion in the X direction (movement direction) in the cross section 50B of the units 30B to 30D is substantially parallel to the X direction edge portion (a linear portion substantially parallel to the Z axis) of the outline of the cross section 50B. The drive unit DR2 includes four actuators for individually moving the polarization units 30A to 30D and four encoders for individually detecting the movement amounts of the polarization units 30A to 30D. The polarization units 30 </ b> A to 30 </ b> D are moved based on the control signal from. In the present embodiment, since the polarization units 30A to 30D are each configured to move in a one-dimensional direction, the support and drive mechanism of the polarization units 30A to 30D can be simplified.

  In this embodiment, since the arrangement plane P1 of the SLM 22 is slightly inclined with respect to the plane perpendicular to the optical axis, the plane conjugate to the arrangement plane P1 is also slightly different from the plane perpendicular to the optical axis. It may be inclined. In such a case, the installation surface P3 of the polarization control system 28 is set to be inclined along a plane conjugate with the arrangement plane P1, and the polarization units 30A to 30D are moved along the inclined surface. You may do it. Further, for example, another installation surface optically conjugate with the installation surface P3 is set by a relay optical system (not shown), the polarization units 30A and 30B are installed on the installation surface P3, and the polarization unit is installed on the other installation surface. The polarization units 30 </ b> A to 30 </ b> D may be divided into a plurality of conjugate surfaces so as to install 30 </ b> C and 30 </ b> D.

  Further, as an example, in the cross section 50B, a portion where the polarization units 30A to 30D do not overlap (a transparent portion) is the first partial region C1, a portion having only the polarization unit 30A is the second partial region C2, and the polarization units 30B to 30D. Only the overlapping part is the third partial region C3, the optically rotating members 30A to 30D are all overlapping the fourth partial region C4, the part having only the polarizing unit 30B is the fifth partial area C5, and only the polarizing units 30A and 30B are overlapping. The portion is referred to as a sixth partial region C6, a portion where only the polarization units 30B and 30C overlap is referred to as a seventh partial region C7, and a portion where all of the polarization units 30A to 30C overlap is referred to as an eighth partial region C8.

  At this time, the light incident on the partial areas C1 to C8 is continuously subjected to an optical rotation action by the optical rotation members 29A to 29D in the polarization units 30A to 30D arranged in the partial areas. It changes at the time of injection. For example, the second partial region C2 is a region where, for example, the incident light of the longitudinally polarized light DV is subjected to the optical rotation action only once by the polarization unit 30A, and the third partial region C3 is the three times of the incident light by the polarization units 30B to 30C. This is a region that continuously receives the optical rotation.

  Further, the cross section 50B of the illumination light IL in the polarization control system 28 and the irradiation region 50A of the illumination light IL for the SLM 22 in FIG. 3A are conjugate. Therefore, the regions in the irradiation region 50A conjugate with the eight partial regions C1, C2, C3, C4, C5, C6, C7, and C8 in the cross section 50B are respectively represented as partial array regions D1, D2, D3, and D3. Called D4, D5, D6, D7, and D8. By driving the polarization units 30A to 30D of the polarization control system 28, for example, as shown in FIG. 3D, the area ratio of the eight partial regions C1 to C8 (and thus the sectional area of the light passing through the partial regions C1 to C8). Ratio) can be changed over a wide range. As the area ratio of the partial regions C1 to C8 is changed, as shown in FIG. 3B, the area ratio of the partial array regions D1 to D8 in the SLM 22 (and thus the mirror elements 24 in these array regions). The number ratio is also changed at the same rate.

  Further, as an example, the illumination optical system ILS of the present embodiment has a polarization state distribution at the illumination pupil that is 180 degrees (π (rad) with respect to the polarization direction of light, for example, with reference to longitudinally polarized light DV (or laterally polarized light DH). )) Of 1 / N (N is an integer of 2 or more), and the angle φ1 can be set as a unit. In this case, there are N polarization directions that can be set simultaneously in an arbitrary light intensity distribution of the illumination pupil, and the polarization direction is any one of the following N angles with respect to a certain reference direction. It is only shifted.

Polarization direction = i · φ1, (i = 0, 1, 2,..., N−1) (1)
φ1 = 180 degrees / N (2)
As an example, when N = 4, the angle φ1 of the setting unit of the polarization direction is 45 degrees (= 180 degrees / 4). If N = 8, the angle φ1 is 22.5 degrees (= 180 degrees / 8).
Hereinafter, a case where N = 8 will be described. At this time, in the illumination pupil plane IPP (detailed later) on which the illumination pupil is formed, the polarization direction is i · 22.5 degrees (i = 0 to 7) counterclockwise with respect to the longitudinal polarization DV, that is, 0. The directions rotated by degrees, 22.5 degrees, 45 degrees, 67.5 degrees, 90 degrees, 112.5 degrees, 135 degrees, and 157.5 degrees are directions A1, A2, A3, and A4 in FIG. , A5, A6, A7, A8. At this time, directions in which the polarization direction is rotated by i · 22.5 degrees (i = 0 to 7) clockwise with respect to the longitudinal polarization DV are directions A8 to A1. A polarization state with a very high degree of freedom can be set by setting the polarization directions of a plurality of regions local in the illumination pupil to any combination of directions A1 to A8.

  In the case of N = 8 (angle φ1 = 22.5 degrees), as shown in FIG. 3C, as an example, the rotation angle of the polarization direction with respect to the incident light in the polarization units 30A, 30B, 30C, 30D (the above-mentioned first 1, 2nd, 3rd, 4th angle) (rotational angle of the optical rotation members 29 </ b> A to 29 </ b> D in FIG. 1B) is, for example, 22.5 degrees, 90 degrees, 45 degrees, and 90 degrees counterclockwise. is there. At this time, the thicknesses of the corresponding optical rotation members 29A, 29B, 29C, and 29D are “22.5 degrees + n1 · 180 degrees” with the optical rotation angle (rotation angle in the polarization direction) with respect to the light incident in the + Y direction counterclockwise. ”,“ 90 degrees + n2 · 180 degrees ”,“ 45 degrees + n3 · 180 degrees ”, and“ 90 degrees + n4 · 180 degrees ”. Note that n1, n2, n3, and n4 are each an integer of 0 or more, and n1 to n4 may be different from each other. If n1 = n2 = n3 = n4 = 0, the optical rotation angles in the optical rotation members 29A, 29B, 29C, 29D are 22.5 degrees, 90 degrees, 45 degrees, 90 degrees counterclockwise, and n1 = n2 = When n3 = n4 = 1, the optical rotation angles in the optical rotation members 29A, 29B, 29C, and 29D are 202.5 degrees, 270 degrees, 225 degrees, and 270 degrees counterclockwise.

  Further, even if the polarization direction is rotated counterclockwise by an angle φa or the polarization direction is rotated clockwise (180 degrees−φa), the polarization direction of the emitted light is the same. The thicknesses of 29A, 29B, 29C, and 29D are set to “157.5 degrees (= 180 degrees−22.5 degrees) + n1 · 180 degrees” and “90 degrees + n2 · 180 degrees” with the optical rotation angle with respect to the incident light clockwise. ”,“ 135 degrees (= 180 degrees−45 degrees) + n3 · 180 degrees ”, and“ 90 degrees + n4 · 180 degrees ”(hereinafter the same). Further, for example, the optical rotation angle is set so that the optical rotation angle is set counterclockwise in the optical rotation members 29A and 29C (polarization units 30A and 30C), and the optical rotation angle is set clockwise in the optical rotation members 29B and 29D (polarization units 30B and 30D). The sign of the optical rotation angle (counterclockwise or clockwise) may be varied between the members 29A to 29D (polarization units 30A to 30D). When the integers n1 to n4 that define the optical rotation angle are increased, the optical rotation members 29A to 29D can be thickened, and thus the optical rotation members 29A to 29D, and thus the polarizing units 30A to 30D may be easily manufactured and supported.

In the following, for convenience of explanation, when the optical rotation angle of the optical rotation member is φa counterclockwise or clockwise, the angle includes “φa + n · 180 degrees” (n is an integer of 0 or more).
In the present embodiment, the polarization direction of the light incident on the partial regions C1 to C8 is the sum of the optical rotation angles of the optical rotation members 29A to 29D in the polarization units 30A to 30D in the partial region, ignoring elliptical polarization. It changes by angle. Further, the polarization direction after rotating at an angle φa is the same as the polarization direction after rotating at an angle “φa + na · 180 degrees” (na is an integer). For this reason, in FIG. 3D, the polarization direction of the illumination light IL after passing through the partial regions C1, C2, C3, C4, C5, C6, C7, and C8 in the cross section 50B is the longitudinal polarization as a reference. They are rotated counterclockwise by 0 degrees, 22.5 degrees, 45 degrees, 67.5 degrees, 90 degrees, 112.5 degrees, 135 degrees, and 157.5 degrees with respect to the DV. Therefore, the illumination light IL after passing through the polarization control system 28 has eight linearly polarized light components whose polarization directions are different from each other by 22.5 degrees (= 180 degrees / 8).

  Here, the polarization state having a polarization direction changed by ± 45 degrees with respect to the longitudinal polarization DV is changed to 45 degrees polarization DSA and DSB, and the polarization state having a polarization direction changed by ± 22.5 degrees with respect to the longitudinal polarization DV is referred to as 22. The polarization state having the polarization direction changed by ± 22.5 degrees with respect to the 5 degrees polarization DV1 and DV2 and the lateral polarization DH will be referred to as 22.5 degrees polarization DH1 and DH2. At this time, the polarization state of the illumination light after passing through the partial regions C1, C2, C3, C4, C5, C6, C7, and C8 in the cross section 50B is DV, DV1, DSA, DH2, DH, DH1, DSB, respectively. , And DV2. The polarization directions of these polarization states DV to DV2 correspond to the polarization directions A1 to A8 in FIG.

  Further, since the partial areas C1 to C8 in the cross section 50B are conjugate with the partial array areas D1 to D8 in the irradiation area 50A of the SLM 22, the polarization directions of the light after passing through the partial areas C1 to C8 are different from each other. This is equivalent to the fact that the light reflected by the eight partial array regions D1 to D8 having variable area ratios in the irradiation region 50A of the SLM 22 is linearly polarized light having different polarization directions. For this reason, by individually controlling the angle of one or a plurality of mirror elements 24 in the partial array regions D1 to D8, the light intensity distribution in the illumination pupil can be changed to a distribution having eight polarization directions in an arbitrary arrangement. Can be set.

  The point is that the polarization direction of the light after passing through the eight partial regions in the cross section 50B only needs to be eight different directions in units of 22.5 degrees. The rotation angle of the polarization direction at 30D (the rotation angle of the optical rotation members 29A to 29D) can be arbitrarily combined. For example, the rotation angles (the first to fourth angles) in the polarization direction in the polarization units 30A, 30B, 30C, and 30D are respectively 90 degrees, 22.5 degrees, 22.5 degrees, and 22.5 counterclockwise. Also, the polarization direction of the light after passing through these can be set to eight directions. Furthermore, the rotation angle of the polarization direction in the polarization units 30A, 30B, 30C, and 30D may be 90 degrees, 22.5 degrees, 22.5 degrees, and 22.5 degrees clockwise.

  In FIG. 1A, the illumination light IL that has passed through the second polarization control system 28 enters a microlens array (or a fly-eye lens) 34 via a condensing optical system 32. The rear lens group 26b and the condensing optical system 32 optically conjugate the pupil plane P2 and the incident plane P5 of the microlens array 34. Accordingly, the illumination light IL that has passed through the array of mirror elements 24 of the SLM 22 has a light intensity distribution similar to the light intensity distribution formed on the pupil plane P2 on the incident surface P5 of the microlens array 34, and a polarization control system. A light intensity distribution having a polarization state distribution controlled by 28 is formed.

  The microlens array 34 is an optical element composed of microlenses having a large number of positive refracting powers arranged vertically and horizontally and densely, for example, and having a rectangular cross section. It can be formed by forming. The microlens array is a wavefront division type optical integrator similar to the fly-eye lens in that the lens elements are arranged vertically and horizontally. A rear focal plane of the microlens array 34 or a plane in the vicinity thereof becomes an illumination pupil plane IPP, and an illumination pupil is formed on this plane. An illumination aperture stop having an opening (light transmission part) having a shape corresponding to a secondary light source to be described later may be disposed at or near the illumination pupil plane IPP.

  A rectangular minute refracting surface as a unit wavefront dividing surface in the microlens array 34 is similar to the shape of the illumination field (illumination region) to be formed on the reticle R (and the shape of the exposure region to be formed on the wafer W). A rectangular shape. For example, a cylindrical micro fly's eye lens can be used as the microlens array 34. The configuration and operation of the cylindrical micro fly's eye lens are disclosed in, for example, US Pat. No. 6,913,373.

  Since the number of wavefront divisions by the microlens array 34 is relatively large, the overall light intensity distribution formed on the incident surface P5 of the microlens array 34 and the overall light intensity distribution of the entire secondary light source on the illumination pupil plane IPP. (Pupil intensity distribution) shows a high correlation. For this reason, the light intensity distribution on the incident surface P5 of the microlens array 34 and the surface optically conjugate with the incident surface P5 can also be substantially referred to as a pupil intensity distribution. The relay optical system 26, the condensing optical system 32, and the microlens array 34 form an intensity distribution that forms a pupil intensity distribution on the illumination pupil plane IPP (illumination pupil) immediately after the microlens array 34 based on the light beam that has passed through the SLM 22. An optical system is configured.

  The illumination light IL incident on the microlens array 34 is two-dimensionally divided by a large number of microlenses and incident on the illumination pupil plane IPP. The illumination pupil plane IPP has substantially the same light intensity distribution as that formed on the incident plane P5. A secondary light source (pupil intensity distribution as a substantial surface light source made up of a large number of small light sources) having a light intensity distribution and substantially the same polarization state distribution is formed. The light beam from the secondary light source formed on the illumination pupil plane IPP illuminates the reticle blind 44 as an illumination field stop via the condenser optical system 42 in a superimposed manner.

  The light beam that has passed through the rectangular opening (light transmission portion) of the reticle blind 44 is reflected in the approximately -Z direction by the mirror MR3 via the first lens group 46a, and then condensed by the second lens group 46b. The illumination area IA on the pattern surface Ra (here, the lower surface) of the reticle R on which the transfer pattern is formed is illuminated in a superimposed manner. At this time, the imaging optical system 46 including the lens groups 46 a and 46 b forms an image of the rectangular opening of the reticle blind 44 on the pattern surface Ra of the reticle R. As described above, the polarization setting system 14, the mirrors MR2, MR3, the SLM 22, the relay optical system 26, the polarization control system 28 (polarization units 30A to 30D), the condensing optical system 32, the microlens array 34, the condenser optical system 42, An illumination optical system ILS is configured including the reticle blind 44 and the imaging optical system 46. The pattern surface Ra (irradiated surface) of the reticle R is an optical Fourier transform surface with respect to the illumination pupil plane IPP by the condenser optical system 42 and the imaging optical system 46 of the illumination optical system ILS. The pupil intensity distribution is a light intensity distribution (luminance distribution) on the illumination pupil plane IPP or a plane optically conjugate with the illumination pupil plane IPP.

  The illumination light IL transmitted through the illumination area of the reticle R held on the reticle stage RST is exposed to the surface of the wafer W held on the wafer stage WST via the projection optical system PL (an area conjugate with the illumination area). Then, an image of the reticle pattern is formed. The pupil plane of the projection optical system PL (a plane conjugate with the entrance pupil) is conjugate with the illumination pupil plane IPP, and an aperture stop AS is installed at a position near or in the pupil plane of the projection optical system PL. The wafer W includes a substrate in which a photoresist (photosensitive agent) is applied to a surface of a disk-shaped base material of a semiconductor such as silicon with a thickness of about several tens to 200 nm.

When the exposure apparatus EX of the present embodiment is a liquid immersion type, an apparatus (not shown) that supplies and recovers liquid as disclosed in, for example, US Patent Application Publication No. 2007/242247, etc. During exposure, a liquid that transmits the illumination light IL is supplied to a local region between the lens at the tip of the projection optical system PL and the wafer W.
In addition, reticle stage RST is placed on an upper surface of a reticle base (not shown) so as to be movable at least in the XY plane. At least a two-dimensional position of the reticle stage RST is measured by a laser interferometer (not shown). Based on this measurement information, the main controller 38 detects the position of the reticle stage RST via a drive system DRR including a linear motor and the like. Control the speed. Wafer stage WST is placed on the upper surface of a base member (not shown) so as to be movable at least within the XY plane. At least a two-dimensional position of wafer stage WST is measured by a laser interferometer or an encoder (not shown). Based on this measurement information, main controller 38 of wafer stage WST passes through drive system DRW including a linear motor and the like. Control position and speed.

  Further, the exposure apparatus EX of the present embodiment, based on the illumination light IL via the illumination optical system ILS and the projection optical system PL, determines the pupil intensity distribution and the polarization state on the illumination pupil plane IPP or the pupil plane of the projection optical system PL. A measuring device 40 for measuring the distribution is provided. The measurement device 40 includes a first measurement unit that measures the pupil intensity distribution and a second measurement unit that measures the distribution of the polarization state (for example, a polarization state represented by a Stokes parameter or a Jones matrix). The measurement result of the measuring device 40 is supplied to the main control device 38. Note that a measurement device similar to the measurement device 40 may be provided on the reticle stage RST so that the pupil intensity distribution and the polarization state distribution of only the illumination optical system ILS can be measured. A measurement apparatus that can be used as a pupil intensity distribution measurement unit is disclosed in, for example, US 2010/0020302.

  At the time of exposure of the wafer W, under the control of the main controller 38, the wafer W is collectively exposed or scanned through the projection optical system PL while the reticle R is illuminated with the illumination light IL from the illumination optical system ILS. By repeating this operation and the operation of moving the wafer W in the X direction and the Y direction via the wafer stage WST, the image of the pattern of the reticle R is exposed on all shot areas of the wafer W. When performing scanning exposure, the Y direction in FIG. 1A can be set as the scanning direction of the reticle R and the wafer W.

  Next, in the polarization units 30A to 30D of the polarization control system 28 of the present embodiment, when illumination light (oblique incident light) inclined with respect to the optical axis AXI is incident on the optical rotation members 29A to 29D, the birefringent member 31A. A description will be given of the fact that the polarization state of the light emitted after being slightly elliptically polarized from ˜31D is corrected to be close to linearly polarized light by the corresponding birefringent members 31A to 31D.

  FIG. 4 shows a main part of the illumination optical system ILS in FIG. 4 representatively shows one mirror element 24C, 24D, 24E, and 24F in each of the four partial array regions D5, D6, D7, and D8 of the SLM 22 shown in FIG. Note that the array (irradiation region 50A) of the mirror elements 24 of the SLM 22 and the region (cross section 50B) where the illumination light IL of the polarization control system 28 is incident are actually near the optical axis AXI of the illumination optical system ILS. Further, the lights IL5, IL6, IL7, and IL8 reflected by the mirror elements 24C, 24D, 24E, and 24F correspond to the inclination angles of the mirror elements 24C to 24F through the front lens group 26a in the state of longitudinally polarized light DV, respectively. Pass through a region on the pupil plane P2 that is arbitrarily determined. Here, it is assumed that the lights IL5 to IL8 reflected from the mirror elements 24C to 24F have a large inclination angle with respect to the optical axis AXI and pass through a region away from the optical axis AXI on the pupil plane P2. Then, the light beams IL5, IL6, IL7, and IL8 that have passed through the pupil plane P2 enter the partial regions C5, C6, C7, and C8 of the polarization control system 28 in the state of the longitudinal polarization DV through the rear lens group 26b. .

  In this case, the rotation angles of the polarization direction with respect to the incident light in the polarization units 30A, 30B, 30C, and 30D of the polarization control system 28 are 22.5 degrees, 90 degrees, 45 degrees, and 90 degrees, respectively, counterclockwise as an example. And At this time, the rotation angles of the polarization direction of the light passing through the partial regions C5, C6, C7, and C8 are 90 degrees, 112.5 degrees (= 90 degrees + 22.5 degrees), and 135 degrees (= 90), respectively. Degree + 45 degrees) and 157.5 degrees (= 135 degrees + 22.5 degrees). Accordingly, the lights IL5, IL6, IL7, and IL8 that have passed through the partial regions C5, C6, C7, and C8 are respectively the horizontally polarized light DH, the horizontally polarized light DH1 that is shifted by 22.5 degrees, the clockwise 45 degrees polarized light DSB, and 22. The longitudinally polarized light DV2 is shifted by 5 degrees, and a partial area (hereinafter referred to as a pupil area) separated from the optical axis AXI of the illumination pupil plane IPP (or the entrance plane P5 in FIG. 1A) via the condensing optical system 32. 53a. Incident on 53b, 53c, 53d. The pupil regions 53a to 53d are part of a region having a high light intensity in the pupil intensity distribution 53 formed on the illumination pupil plane IPP. And the polarization direction of the light which injects into the pupil area | regions 53a-53d turns into direction A5-A8 shown by FIG.2 (C).

  In this embodiment, since the arrangement plane P1 of the mirror element 24 of the SLM 22 and the installation plane P3 of the polarization units 30A to 30D are substantially conjugate, the incident angle of light incident on a point on the front surface of the polarization units 30A to 30D ( (The same angle as the tilt angle with respect to the optical axis AXI) corresponds to the tilt angle with respect to the optical axis AXI of the reflected light at the mirror element 24 of the SLM 22 at a position conjugate to that point. When the angle of inclination of the reflected light from the mirror element 24 with respect to the optical axis AXI is large, as shown by the lights IL5 to IL8, the light that has passed through the polarization units 30A to 30D has the optical axis AXI on the illumination pupil plane IPP. Incident into the pupil region away from the. The light passing through the optical rotation members 29A to 29D in the polarization units 30A to 30D is elliptically polarized when obliquely incident light is incident. The degree of elliptical polarization is the optical axis of the obliquely incident light. The larger the inclination angle with respect to AXI, that is, the larger the distance from the optical axis AXI on the illumination pupil plane IPP of the emitted light, the larger the angle.

  Therefore, in the effective area of the illumination pupil plane IPP (area surrounded by a circle having a coherence factor of 1), the average value of the distance from the optical axis AXI of the peripheral area is RIL, and the slope corresponding to this distance RIL For obliquely incident light with an angle, the elliptically polarized light is incident on almost all of its effective area by adjusting the elliptically polarized light so that it is closest to linearly polarized light. Can be corrected. In the following, regarding the light incident on the illumination pupil plane IPP at a position where the distance from the optical axis AXI is RIL, the inclination angle θ with respect to the optical axis AXI when entering the polarization units 30A to 30D (that is, the polarization units 30A to 30D). Assuming that the incident angle [theta] with respect to the front surface is several degrees (e.g., about 5 degrees), the case of correcting the elliptical polarization for the light incident on the polarization units 30A to 30D at this incident angle [theta] will be described.

First, the polarization characteristics of the optical rotation member 29B and the birefringence member 31B constituting the polarization unit 30B will be described with respect to the polarization unit 30B whose polarization direction rotation angle with respect to incident light is 90 degrees.
FIG. 5A shows a state in which only the optical rotation member 29B in the polarization unit 30B is installed on the installation surface P3 in the polarization control system 28 of the present embodiment. In FIG. 5A, FIG. 6A described below, and the like, coordinates that pass through the optical axis AXI of the illumination pupil plane IPP and are parallel to the X axis and the Z axis are defined as an X1 axis and a Z1 axis, respectively. The optical rotation angle of the optical rotation member 29B is 90 degrees counterclockwise (or clockwise) or (90 degrees + n2 · 180 degrees) (n2 is an integer of 0 or more). In FIG. 5A, the optical rotation member 29B is assumed to be a positive crystal such as quartz. At this time, the optical axis of the optical rotation member 29B is a slow axis. The optical rotator 29B has an optical axis OAA (also a slow axis PSA here) parallel to the optical axis AXI, and the two orthogonal fast axes PF1A and PF2A of the optical rotator 29B are the front surfaces of the optical rotator 29B. (Plane perpendicular to the optical axis AXI). Further, in the region near the optical axis AXI on the front surface of the optical rotation member 29B, the light ILA that is perpendicularly incident on the point 29Ba in the state of the longitudinal polarization DV is rotated by 90 degrees counterclockwise in the polarization direction by the optical rotation member 29B and is laterally polarized. DH enters the pupil region 54a centered on the optical axis AXI within the pupil intensity distribution 54 of the illumination pupil plane IPP.

  On the other hand, the incident angle θ (inclination angle with respect to the optical axis AXI) in the + Z direction, the direction rotated 45 degrees counterclockwise with respect to the Z axis, and the −X direction at the front points 29Bb, 29Bc, 29Bd of the optical rotation member 29B, respectively. Light ILB, ILC, and ILD of longitudinally polarized light DV incident at θ) is tilted 45 degrees counterclockwise with respect to the optical axis AXI of the illumination pupil plane IPP with respect to the optical axis AXI of the illumination pupil plane IPP via the condensing optical system 32. And the pupil regions 54b, 54c, and 54d that are separated in the −X1 direction. At this time, on the illumination pupil plane IPP, the light incident on the pupil regions 54b and 54d shifted from the optical axis AXI in the same direction and the direction rotated by 90 degrees with respect to the polarization direction (Z direction) of the longitudinally polarized light DV at the time of incidence. ILB and ILD have an elliptical polarization effect in the optical rotation member 29B, and are in a polarization state DHE in which the lateral polarization is slightly elliptically polarized. Also, on the illumination pupil plane IPP, the light ILC incident on the pupil region 54c shifted from the optical axis AXI in a direction rotated by 45 degrees with respect to the polarization direction (Z direction) of the longitudinally polarized light DV at the time of incidence is incident on the optical rotation member 29B. Since the action of elliptical polarization is small, the target laterally polarized light DH is obtained. The reason why the effect of elliptical polarization on the lights ILB and ILD is increased will be described with reference to FIGS. 5B and 5C.

  FIGS. 5B and 5C show polarization states at the time of incidence and emergence of light ILA perpendicularly incident on the optical rotation member 29B of FIG. 5A and light ILB to ILD incident at an incident angle θ, respectively. 5B and 5C, a point 55 represents the traveling direction of vertically incident light with respect to the optical rotation member 29B, and a dotted circumference 56 represents the traveling direction of light incident at an incident angle θ. The point 55 and the circumference 56 correspond to the positions where the vertically incident light and the light having the incident angle θ are incident on the illumination pupil plane IPP, respectively.

  In general, the polarization state of light incident on the optical rotatory member (or optical rotator) can be decomposed into two mutually orthogonal intrinsic polarization components. The intrinsic polarization is described, for example, in a reference document “Tatsuo Tsuruta: Applied Optics II (Applied Physics Selection), pp. 174-181 (Baifukan, 1990)”. Further, since the optical axis OAA of the optical rotation member 29B of this embodiment is parallel to the optical axis AXI, the optical rotation member 29B is incident on the optical rotation member 29B in parallel to the optical axis AXI (perpendicular to the front surface of the optical rotation member 29B) like the optical ILA. The polarization state of the light can be decomposed into first and second intrinsic polarizations consisting of clockwise and counterclockwise circularly polarized light 57A, 57B. In FIGS. 5B and 5C, the polarization state of light is represented by a trajectory of an oscillating electric vector viewed in the traveling direction. On the other hand, as in the light ILB to ILD, the polarization state of the light incident on the optical rotation member 29B at the incident angle θ is, for example, clockwise elliptically polarized light 57C, 57E, 57G with the radial direction of the circumference 56 as the major axis direction, for example. 1 and the second intrinsic polarization consisting of counterclockwise elliptically polarized light 57D, 57F, 57H whose major axis is the circumferential direction of the circumference 56.

また、旋光部材２９Ｂにおける第１の固有偏光の光に対する屈折率をｎ₊、第２の固有偏光の光に対する屈折率をｎ_-とすると、上記の参考文献に記載されているように、これらの屈折率ｎ_±は、その屈折率ｎ_I及びｎ_IIを用いて次式（４）のように表すことができる。なお、式（４）における係数Ｒは式（５）で表され、係数Ｃは旋光部材２９Ｂの旋回ベクトルの係数Ｇを用いて式（６）で表される。 The optical rotator or the optical rotatory member is also a birefringent member having optical activity. Therefore, the ordinary refractive index n _o of the optical rotation member 29B, the use of extraordinary refractive index n _e and the incident angle theta, as described in the above references, the refractive index n _I for ordinary ray of the optical rotation member 29B And the refractive index n _II for the extraordinary ray at the incident angle θ is as follows.

Further, when the refractive index for the light of the first intrinsic polarization in the optical rotation member 29B is n ₊ and the refractive index for the light of the second intrinsic polarization is n ₋ , as described in the above-mentioned reference, refractive index n _± can be expressed by the following equation (4) using the refractive index n _I and n _II. The coefficient R in Expression (4) is expressed by Expression (5), and the coefficient C is expressed by Expression (6) using the coefficient G of the turning vector of the optical rotation member 29B.

なお、旋回ベクトルの係数Ｇは、上記の表１の旋光能ρ、旋光部材２９Ｂの平均屈折率ｎ、入射光の波長λを用いて、次のようになる。
Ｇ＝ρｎλ／π …（６Ａ）
また、第１及び第２の固有偏光が楕円偏光である場合、上記の参考文献に記載されているように、その楕円率ｋ（＝短軸半径／長軸半径）の絶対値は次式で表される。

The swirl vector coefficient G is as follows using the optical rotation power ρ of Table 1 above, the average refractive index n of the optical rotation member 29B, and the wavelength λ of the incident light.
G = ρnλ / π (6A)
When the first and second intrinsic polarizations are elliptical polarizations, the absolute value of the ellipticity k (= short axis radius / major axis radius) is expressed by the following equation, as described in the above-mentioned reference. expressed.

式（４）から分かるように、第１及び第２の固有偏光の光に対する屈折率が互いに異なっているため、旋光部材２９Ｂの厚さｄ１に応じて第１及び第２の固有偏光間の位相差が変化する。
本実施形態では、光ＩＬＡ〜ＩＬＤは縦偏光ＤＶで旋光部材２９Ｂに入射するため、垂直入射する光ＩＬＡは、入射時には、円偏光５７Ａ，５７Ｂの位相がＺ方向の端部で一致する。同様に、入射角θで入射する光ＩＬＢ〜ＩＬＤは、一方の楕円偏光５７Ｃ〜５７Ｇと他方の楕円偏光５７Ｄ〜５７Ｈとの位相がＺ方向の端部で一致する。また、旋光部材２９Ｂの旋光角は（９０度＋ｎ２・１８０度）であるため、垂直入射する光ＩＬＡが射出されるときには、図５（Ｃ）に示すように、円偏光５７Ａ，５７Ｂ間に１８０度の位相差が付与される。そして、光ＩＬＡの射出時の偏光状態は、１８０度の位相差がある円偏光５７Ａ，５７Ｂを合成することで正確に横偏光ＤＨとなる。

As can be seen from the equation (4), since the refractive indexes of the first and second intrinsic polarizations with respect to the light are different from each other, the position between the first and second intrinsic polarizations depends on the thickness d1 of the optical rotation member 29B. The phase difference changes.
In the present embodiment, the lights ILA to ILD are incident on the optical rotation member 29B with longitudinally polarized light DV, and therefore the vertically incident light ILA has the phases of the circularly polarized lights 57A and 57B coincide with each other at the end in the Z direction. Similarly, in the lights ILB to ILD that are incident at the incident angle θ, the phases of the one elliptically polarized light 57C to 57G and the other elliptically polarized light 57D to 57H coincide at the end in the Z direction. Since the optical rotation angle of the optical rotation member 29B is (90 degrees + n2 · 180 degrees), when vertically incident light ILA is emitted, as shown in FIG. A phase difference of degrees is given. The polarization state at the time of emission of the light ILA is accurately the laterally polarized light DH by combining the circularly polarized light 57A and 57B having a phase difference of 180 degrees.

When the integer n2 is 3, for example, the optical rotation angle of the optical rotation member 29B is 630 degrees (= 90 degrees + 3 · 180 degrees). At this time, the thickness d1 of the optical rotation member 29B is approximately 1.9 mm using the optical rotation power ρ of Table 1 as follows.
d1 = 630 / ρ = 630/325 = 1.94 (mm) (8)
At this time, even in the lights ILB and ILD inclined in the Z direction and the X direction at the incident angle θ, a phase difference of 180 degrees is given between the elliptically polarized light 57C and 57G and the elliptically polarized light 57D and 57H at the time of emission. When the elliptically polarized light 57C and 57G and the elliptically polarized light 57D and 57H are combined, the obtained polarization state becomes the elliptically polarized light DHE close to the laterally polarized light DH. However, in the light ILC inclined in the direction inclined by 45 degrees in the Z direction at the incident angle θ, a phase difference of 180 degrees is given between the elliptically polarized light 57E and the elliptically polarized light 57F at the time of emission. When 57E and 57F are synthesized, the polarization state obtained is substantially laterally polarized light DH. As a result, on the illumination pupil plane IPP in FIG. 5A, the lights ILB and ILD incident on the pupil regions 54b and 54d shifted in the Z1 direction and the X1 direction from the optical axis AXI are slightly elliptically polarized according to the incident angle θ. Turn into. The degree of elliptically polarized light is expressed by the ellipticity k of the first and second intrinsic polarized light in the above equation (7).

When the light emitted from the optical rotation member 29B is elliptically polarized in this way, if this light is used as it is, the deviation of the polarization state of the light irradiated to the reticle R from the desired polarization state increases, and the wafer W There is a possibility that the resolution and uniformity of the pattern image projected on the top may be lowered.
Therefore, in this embodiment, as shown in FIG. 6A, the birefringent member 31B is installed adjacent to the optical rotation member 29B so that the optical axis OAB is parallel to the optical axis AXI. If the birefringent member 31B is a positive crystal such as magnesium fluoride, the optical axis OAB of the birefringent member 31B is also the slow axis PSB, and the two orthogonal fast axes PF1B and PF2B of the birefringent member 31B. Is parallel to the front surface (surface perpendicular to the optical axis AXI) of the birefringent member 31B. The light ILA emitted perpendicularly to the optical rotatory member 29B is also perpendicularly incident on the birefringent member 31B, and the light ILB to ILD incident on the optical rotatory member 29B at the incident angle θ and emitted are birefringent members. It also enters 31B at an incident angle θ. The lights ILA to ILD that have passed through the birefringent member 31B are incident on the pupil regions 54a to 54d of the illumination pupil plane IPP.

  FIGS. 6B and 6C show polarization states at the time of incidence and emission of light ILA perpendicularly incident on the birefringent member 31B of FIG. 6A and light ILB to ILD incident at an incident angle θ, respectively. . As shown in FIG. 6B, at the time of incidence on the birefringent member 31B, the vertically incident light ILA is laterally polarized light DH, and the light ILC tilted counterclockwise at 45 degrees to the Z axis is substantially laterally polarized light DH. Lights ILB and ILD inclined in the direction and the X direction are slightly elliptically polarized light DHE close to the laterally polarized light DH. Further, as described in the above-mentioned reference, the polarization state of the light incident on the birefringent member having no optical rotation is the first and second intrinsic polarization components composed of two mutually orthogonal linearly polarized lights. Can be disassembled.

  Since the birefringent member 31B of the present embodiment has the optical axis OAB parallel to the optical axis AXI, the polarization state of the light perpendicularly incident on the front surface of the birefringent member 31B, like the optical ILA, is orthogonal to each other. Can be decomposed into two linearly polarized lights having the same value. For this reason, the polarization state at the time of incidence is the same as that at the time of emission, and the light ILA is emitted from the birefringent member 31B as the laterally polarized light DH (see FIG. 6C).

On the other hand, the polarization state of the light incident on the birefringent member 31B at the incident angle θ, such as the light ILB to ILD, is linearly polarized along the circumferential direction of the circumference 56 in FIG. Polarization) and linearly polarized light (second intrinsic polarization) along the radial direction of the circumference 56. In the birefringent member 31B, the first intrinsic polarization is an ordinary ray polarization state, and the second intrinsic polarization is also an extraordinary ray polarization state. The birefringent member 31B has an ordinary light refractive index n _o , an extraordinary light refractive index _ne , and an incident angle θ, and the refractive index n _I for ordinary light and extraordinary light (first and second intrinsic polarized light). And n _II are represented by the above formulas (3A) and (3B), respectively. As can be seen from equation (3B), when the incident angle θ is greater than 0, the refractive indexes n _II and n _I are different from each other. The phase difference between extraordinary rays changes.

In the present embodiment, when entering the birefringent member 31B, the light ILB that is inclined in the Z direction and incident on the elliptically polarized light DHE is decomposed into linearly polarized light 58C having a large circumferential direction and linearly polarized light 58C having a small radial direction. (There is a phase difference of 90 degrees between them.) Light ILC that is incident as substantially laterally polarized light DH is decomposed into linearly polarized light 58E in the circumferential direction and linearly polarized light 58F of approximately the same size in the radial direction. The light ILD inclined in the direction and incident as elliptically polarized light DHE is decomposed into linearly polarized light 58G having a small circumferential direction and linearly polarized light 58H having a large radial direction (there is a phase difference of 90 degrees between them). If linearly polarized light 58C, 58E, the refractive index for light (ordinary ray) of 58G is assumed to be n _I, linearly polarized light 58D, 58F, the refractive index for light of 58H (extraordinary ray) according to the incident angle θ changes N _II .

At this time, the thickness d2 of the birefringent member 31B is, for example, 90 degrees (or 90 degrees + n5 · 180 degrees) between the lights of the linearly polarized light 58C and 58D while the light ILB passes through the birefringent member 31B. The phase difference δ is set such that n5 is an integer equal to or greater than 0. At this time, there is the following relationship using the wavelength λ of light.
δ = 360 ° (n _II −n _I ) d2 / λ (9)
In other words, when the polarization state of the light that passes through the optical rotation member 29B and is inclined at a predetermined angle (incident angle θ) with respect to the optical axis AXI of the illumination optical system ILS is adjusted to elliptically polarized light (or the incident light is elliptically polarized light). The minimum thickness in the optical axis direction of the birefringent member 31B (adjusting member) when adjusting to linearly polarized light is da, and the polarization state of the light incident on the birefringent member 31B at the predetermined angle is The minimum thickness in the optical axis direction of the birefringent member 31B when returning to the state (here, the thickness to which a phase difference of 180 degrees is given between the light beams of the linearly polarized light 58C and 58D) is db, and the birefringent member The thickness d2 of 31B in the optical axis direction is set to da + i · db (i is an integer of 0 or more).

As the birefringent member 31B is magnesium fluoride, the refractive index n _o of Table 1 above, using a n _e, 5 degrees incident angle θ of the formula (3B) as an example, when the wavelength λ and 193 nm, wherein (N _II −n _I ) / λ in (9) is approximately 0.528 (1 / mm). Therefore, when the phase difference δ is 450 degrees (= 90 degrees + 360 degrees) (n5 = 2), the thickness d2 of the birefringent member 31B is approximately 2.4 mm (here, the thickness) from the equation (9) as follows. d1 approximately 1.2 times).
d2 = (δ / 360) · λ / (n _II −n _I ) = 2.4 mm (10)
At this time, as shown in FIG. 6C, when the light ILB and ILD inclined at the incident angle θ in the Z direction and the X direction are emitted, between the linearly polarized light 58C and 58D and between the linearly polarized light 58G and 58H. Since a phase difference of 90 degrees is added to each, the obtained polarization state is linearly polarized light DHL and DHR that can be regarded as substantially horizontally polarized light DH. Note that, depending on the ellipticity of the elliptically polarized light DHE of the light ILB and ILD when entering the birefringent member 31B, the linearly polarized light DHL and DHR at the time of emission slightly rotate, for example, counterclockwise and clockwise, respectively. The amount of rotation is considerably smaller than the unit for setting the polarization direction (here, 22.5 degrees), and is negligible during normal use.

  In addition, in the light ILC inclined in the direction inclined by 45 degrees in the Z direction at the incident angle θ, the polarization state at the time of emission is substantially horizontal polarization DH. As a result, in the illumination pupil plane IPP of FIG. 6A, the light beams ILB and ILD that are incident on the pupil regions 54b and 54d that are shifted from the optical axis AXI in the Z1 direction and the X1 direction are the lateral polarization DH that is the target polarization state. DHL and DHR that are close to each other, and the target polarization state distribution is obtained in the pupil intensity distribution 54 as a whole. Therefore, the pattern image of the reticle R can be exposed on the wafer with high resolution and contrast.

Note that the polarization unit 30D in FIG. 3C has the same rotation angle as the polarization unit 30B, and therefore the polarization unit 30D may have the same configuration as the polarization unit 30B.
Next, the polarization characteristics of the optical rotation member 29C and the birefringence member 31C constituting the polarization unit 30C will be described for the polarization unit 30C whose polarization direction rotation angle with respect to incident light is 45 degrees.

  FIG. 7A shows a state where only the optical rotation member 29C in the polarization unit 30C is installed on the installation surface P3 in the polarization control system 28 of the present embodiment. The optical rotation angle of the optical rotation member 29C is 45 degrees counterclockwise or (45 degrees + n3 · 180 degrees) (n3 is an integer of 0 or more). In FIG. 7A, the optical rotator 29C has an optical axis OAC (here, also a slow axis PSC) parallel to the optical axis AXI, and two orthogonal fast axes PF1C and PF2C of the optical rotator 29C. Is parallel to the front surface (surface perpendicular to the optical axis AXI) of the optical rotation member 29C. Further, in the region near the optical axis AXI on the front surface of the optical rotatory member 29C, the light ILE perpendicularly incident on the point 29Ca in the state of longitudinally polarized light DV is rotated 45 degrees counterclockwise by the optical rotatory member 29C and the polarization direction is rotated 45 degrees counterclockwise. The polarized light DSA is incident on the pupil region 54a centered on the optical axis AXI of the illumination pupil plane IPP.

  On the other hand, the incident angle θ (inclination angle with respect to the optical axis AXI) in the + Z direction, the direction rotated 45 degrees counterclockwise with respect to the Z axis, and the −X direction at the front points 29Cb, 29Cc, 29Cd of the optical rotation member 29C, respectively. The light ILF, ILG, ILH of the longitudinally polarized light DV incident at θ) is in the + Z1 direction with respect to the optical axis AXI of the illumination pupil plane IPP, in the direction inclined 45 degrees counterclockwise with respect to the Z1 axis, and in the −X1 direction. The light enters the separated pupil regions 54b, 54c, and 54d. At this time, in the illumination pupil plane IPP, the light ILF, ILG, ILH incident on the pupil regions 54b, 54c, 54d is a polarization state in which the polarization DSA is slightly elliptically polarized by the action of elliptical polarization in the optical rotation member 29C. It is DSAE. In the case of the optical rotation member 29C, the illumination pupil plane IPP is used for light incident on the regions 54e, 54f intermediate the pupil regions 54b, 54c, 54d (light in a direction shifted by 22.5 degrees from the Z1 axis or the X1 axis). The polarization state above is a nearly accurate 45 degree polarization DSA. The reason why the action of elliptical polarization becomes large with respect to the light ILF to ILH will be described with reference to FIGS. 7B and 7C.

  FIGS. 7B and 7C show the polarization states at the time of incidence and emergence of the light ILE perpendicularly incident on the optical rotation member 29C of FIG. 7A and the light ILF to ILH incident at the incident angle θ, respectively. As in the case of the optical rotation member 29B in FIG. 5A, the polarization state of the light ILA can be decomposed into first and second intrinsic polarizations composed of circularly polarized light 57A and 57B, and the light ILF to ILH having the incident angle θ. The polarization state is the first intrinsic polarization composed of elliptically polarized light 57C, 57E, 57G along the radial direction of the circumference 56 and the second intrinsic polarization 57D, 57F, 57H along the circumferential direction of the circumference 56. It can be decomposed into intrinsic polarization. In the present embodiment, the light ILE to ILH are incident on the optical rotatory member 29C as longitudinally polarized light DV, and therefore the decomposition of the first and second intrinsic polarizations in the polarization state at the time of incidence is the same as in FIG.

  Further, since the optical rotation angle of the optical rotation member 29C is counterclockwise (45 degrees + n3 · 180 degrees), when vertically incident light ILA is emitted, as shown in FIG. 7C, circularly polarized light 57A, 57B A phase difference of 90 degrees is given between them. The polarization state at the time of emission of the light ILA is accurately 45 degrees polarized DSA by combining the circularly polarized light 57A and 57B having a phase difference of 90 degrees. The thickness of the optical rotatory member 29C can be calculated in the same manner as the optical rotatory member 29B.

  At this time, even in the light ILF to ILH inclined at the incident angle θ, a phase difference of 90 degrees is given between the elliptically polarized light 57C and 57G and the elliptically polarized light 57D and 57H at the time of emission, but these elliptically polarized light 57C, When 57G and elliptically polarized light 57D and 57H are combined, the polarization state obtained becomes elliptically polarized DSAE close to 45 degree polarized light DSA. Similarly, in the light ILG inclined in the direction inclined by 45 degrees in the Z direction, a phase difference of 90 degrees is given between the elliptically polarized light 57E and the elliptically polarized light 57F at the time of emission, so that these elliptically polarized lights 57E and 57F Are combined, the polarization state obtained is approximately elliptically polarized DSAE. As a result, in the illumination pupil plane IPP of FIG. 7A, the light ILF to ILH incident on the pupil regions 54b to 54d is slightly elliptically polarized according to the incident angle θ. The degree of elliptically polarized light is expressed by the ellipticity k of the first and second intrinsic polarized light in the above equation (7).

  In this embodiment, in order to correct the elliptical polarization in the optical rotation member 29C, as shown in FIG. 8A, the birefringent member 31C is adjacent to the optical rotation member 29C and its optical axis OAD (here, the slow axis). (It is assumed that it is also a PSD) in parallel with the optical axis AXI. Two orthogonal fast axes PF1D and PF2D of the birefringent member 31C are parallel to the front surface (a surface perpendicular to the optical axis AXI) of the birefringent member 31C. In addition, the light ILE perpendicularly incident on the optical rotatory member 29C is incident on the birefringent member 31C, and the light ILF to ILH incident upon the optical rotatory member 29C at the incident angle θ and emitted are birefringent members. It also enters 31C at an incident angle θ. The lights ILE to ILH that have passed through the birefringent member 31C enter the pupil regions 54a to 54d of the illumination pupil plane IPP.

  FIGS. 8B and 8C show the polarization states at the time of incidence and emergence of light ILE perpendicularly incident on the birefringent member 31C of FIG. 8A and light ILF to ILH incident at an incident angle θ, respectively. . As shown in FIG. 8B, when entering the birefringent member 31C, vertically incident light ILE is 45-degree polarized DSA, and the other lights ILF to ILH are elliptically polarized DSAE close to 45-degree polarized DSA. .

  Since the optical axis OAD of the birefringent member 31C of this embodiment is parallel to the optical axis AXI, the polarization state of light that is perpendicularly incident on the front surface of the birefringent member 31C, as in the case of the light ILE, is the time of incidence and the time of emission. The light ILE is emitted from the birefringent member 31B as it is with 45-degree polarization DSA (see FIG. 8C). On the other hand, the polarization state of the light incident on the birefringent member 31C at the incident angle θ, such as the light ILF to ILH, is linearly polarized along the circumferential direction of the circumference 56 in FIG. It can be decomposed into ordinary polarized light that is polarized light) and linearly polarized light along the radial direction of the circumference 56 (second polarized light that is the second intrinsic polarized light). Similar to the case of the birefringent member 31B in FIG. 6A, the phase difference between the ordinary ray and the extraordinary ray changes with respect to the oblique incident light according to the thickness of the birefringent member 31C.

In the present embodiment, when entering the birefringent member 31C, the light ILF and ILH incident as elliptically polarized light DSAE are decomposed into linearly polarized light 58C and 58G having a large circumferential direction and linearly polarized light 58D and 58H having a large radial direction. (There is a phase difference of about 45 degrees between them), and the light ILG is decomposed into linearly polarized light 58E having a small circumferential direction and linearly polarized light 58F having a large radial direction (about 45 degrees between them). There is a phase difference.
At this time, the thickness of the birefringent member 31C is, for example, 45 degrees (or 45 degrees + n5 · 180 degrees) between the lights of the linearly polarized light 58C and 58D while the light ILF passes through the birefringent member 31C ( n6 is set to give a phase difference δ of 0 or more.

  At this time, as shown in FIG. 8C, when light ILF, ILG, and ILH incident at an incident angle θ is emitted, the linearly polarized light 58C, 58E, and 58G and the linearly polarized light 58D, 58F, and 58H are respectively provided. Since a 45 degree phase difference is added, the obtained polarization states are approximately 45 degree polarized light DSA, respectively. Depending on the ellipticity of the elliptically polarized light DSAE of the light ILF to ILH when entering the birefringent member 31C, the linearly polarized light at the time of emission slightly rotates, for example, counterclockwise and clockwise from the accurate 45 degree polarized light DSA, respectively. However, this rotation amount is considerably smaller than the setting unit (22.5 degrees in this case) of the polarization direction, and is negligible in normal use. As a result, on the illumination pupil plane IPP in FIG. 8A, the light ILF to ILH incident on the pupil regions 54b to 54d shifted in the Z1 direction and the X1 direction from the optical axis AXI are 45-degree polarized light that is a target polarization state. DSA is obtained, and the distribution of the target polarization state is obtained in the pupil intensity distribution 54 as a whole.

Similarly, for the polarization unit 30A having a polarization direction rotation angle of 22.5 degrees with respect to the incident light in FIG. 3A, an optical rotation member 29A having an optical rotation angle of 22.5 degrees and, for example, an ordinary ray and an extraordinary ray By combining with the birefringent member 31A whose thickness is set so that the phase difference is 22.5 degrees, elliptical polarization in the optical rotation member 29A can be corrected.
In addition, in the polarization units 30A to 30D, even when the polarization direction is rotated by one polarization unit, or when the polarization directions are sequentially rotated by arranging a plurality of polarization units 30A to 30D in series, the final The result will be the same if the polarization rotation angle is the same. Further, the result is the same even if the rotation angle (optical rotation angle) of the polarization direction is an angle obtained by adding an integral multiple of 180 degrees to the above angle.

As described above, there is a pupil intensity distribution in a polarization state that is a combination of eight polarization directions that are set so that illumination light IL of longitudinally polarized light DV is incident on the cross section 50B of the polarization control system 28 over the entire surface of the illumination pupil plane IPP. High precision is set.
Next, an example of an illumination method for illuminating the reticle R by controlling the light intensity distribution and the polarization state distribution on the illumination pupil plane IPP in the exposure apparatus EX of the present embodiment, and an example of an exposure method using this illumination method are shown in FIG. This will be described with reference to a flowchart. The operation of this method is controlled by the main controller 38. First, in step 102 in FIG. 9, reticle R is loaded onto reticle stage RST in FIG. The main controller 38 reads the illumination conditions (including pupil intensity distribution and polarization state distribution) of the reticle R from the exposure data file in the internal storage device, and outputs information on the illumination conditions to the illumination controller 36.

  Here, as an example, the target pupil intensity distribution on the illumination pupil plane IPP is assumed to have the linearly polarized light components of the eight polarization directions A1 to A8 in FIG. At this time, the illumination control unit 36 drives the polarization units 30A to 30D of the polarization control system 28 according to the target area ratio of the pupil regions (regions on the illumination pupil plane IPP) for the polarization directions A1 to A8 ( Step 104). As an example, as shown in FIG. 3C, the position of the polarization unit 30A in the Z direction so that the areas of the eight partial regions C1 to C8 in the cross section 50B of the illumination light IL are the same, and The positions of the polarization units 30B to 30D in the X direction are controlled. And the illumination control part 36 belongs to every 8 partial array area | regions D1-D8 (refer FIG. 3 (A)) of SLM22 corresponding to the partial area | regions C1-C8 via the drive part 25 of SLM22. The angles (inclination angles around two orthogonal axes) of the plurality of mirror elements 24 are individually set (step 106). In this case, for example, in the partial array region D5 of the SLM 22, a plurality of mirrors belonging to the region are arranged so that the reflected light is substantially uniformly incident in the pupil region having the illumination pupil plane IPP and the polarization direction A5 (laterally polarized light DH). The angles of the elements 24 are set individually.

  Thereafter, wafer W is loaded onto wafer stage WST (step 108), and irradiation of illumination light IL from light source 10 is started (step 110). The illumination light IL is incident on the SLM 22 with, for example, longitudinally polarized light DV (P-polarized light with respect to the arrangement plane P1), and is reflected by each mirror element 24 of the SLM 22 in a direction corresponding to the angle set in Step 106 (Step 112). . The illumination light IL reflected by the SLM 22 enters the polarization units 30 </ b> A to 30 </ b> D of the polarization control system 28 via the relay optical system 26. In addition, the light which goes to the pupil area | region of longitudinally polarized light DV in the illumination pupil plane IPP passes through the partial area C1 without the polarization units 30A to 30D and enters the illumination pupil plane IPP through the condensing optical system 32.

  The light incident on the polarization units 30A to 30D is individually rotated by an angle at which the polarization direction is set by the optical rotation members 29A to 29D (step 114). Then, the light that is incident on the optical rotation members 29A to 29D in an inclined state with respect to the optical axis AXI and is elliptically polarized after passing through the optical rotation members 29A to 29D passes through the corresponding birefringence members 31A to 31D. The elliptically polarized light is corrected (adjusted) into linearly polarized light (step 116). When there is light perpendicularly incident on the optical rotation members 29A to 29D, this light is linearly polarized light in a target direction without being elliptically polarized. Moreover, although the light incident perpendicularly to the optical rotation members 29A to 29D is also incident perpendicularly to the birefringent members 31A to 31D, the polarization state of the light does not change depending on the birefringent members 31A to 31D. The light that has passed through the polarization units 30A to 30D of the polarization control system 28 becomes light having eight linearly polarized light components set for the partial regions C1 to C8 (step 118).

  The illumination light IL that has passed through the polarization control system 28 passes through the condensing optical system 33 to the incident surface P5 of the microlens array 34, and thus to the at least eight pupil regions of the illumination pupil plane IPP, respectively, with straight lines having polarization directions A1 to A8. Incident with polarized light (step 120). Thus, a pupil intensity distribution (illumination pupil) having a desired light intensity distribution and polarization state distribution is formed on the illumination pupil plane IPP. The reticle surface Ra of the reticle R is illuminated by the illumination optical system ILS with the illumination light IL from the illumination pupil. Then, the wafer W is exposed with the illumination light IL (step 122). Thereafter, the irradiation of the illumination light IL is stopped, and the exposed wafer W is unloaded. Further, when the next wafer is exposed (step 124), the operation returns to step 108, and the formation and exposure of the illumination pupil are repeated.

As described above, according to the illumination method and the exposure method of the present embodiment, the illumination condition including the polarization state distribution optimized with high accuracy with respect to the pattern of the reticle R by the cooperative action of the SLM 22 and the polarization control system 28. Since the reticle R can be illuminated with the above, the pattern of the reticle R can be exposed to the wafer W with high accuracy.
For example, a pupil intensity distribution 52 having 16 pupil regions Bj (j = 1 to 16) in the circumferential direction so as to surround the optical axis AXI as shown in FIG. When the circumferential polarization state is set so that the polarization directions in the regions B1 to B8 are A1 to A8 and the polarization directions in the pupil regions B9 to B16 are A1 to A8, the portion of the SLM 22 in FIG. The reflected light from the array areas D1 to D8 may be distributed to the pupil areas B1 to B8 and B9 to B16, respectively.

  Furthermore, in order to set the polarization direction in the pupil regions B1 to B16 in the radial direction (radial polarization state) with respect to the optical axis AXI, as shown by the pupil intensity distribution 52A in FIG. The reflected light from the partial array regions D5, D6, D7, D8, D1, D2, D3, and D4 may be distributed to the pupil regions B1 to B8 and B9 to B16, respectively. In the distribution of FIG. 2 (D), the polarization direction is the direction A1 (vertical polarization) in the pupil region B17 on the optical axis, and the circumferential polarization of the four pupil regions B18 around the polarization direction is the direction A5. However, the reflected light from the mirror elements 24 in the corresponding partial array regions D1 and D5 of the SLM 22 may be distributed to the pupil regions B17 and B18, respectively.

Then, by changing the area ratio of the partial regions C1 to C8 (as a result, the partial array regions D1 to D8 of the SLM 22) in FIG. 3C, the polarization directions of the reflected light from the partial array regions D1 to D8 are A1 to A8, respectively. Thus, an illumination pupil having a combination of any eight polarization directions with any light intensity distribution can be easily formed on the illumination pupil plane IPP.
As described above, the illumination optical system ILS of this embodiment is an optical system that illuminates the reticle surface Ra (irradiated surface) with the illumination light IL from the light source 10. The illumination optical system ILS has a plurality of mirror elements 24 arranged on the array surface P1 (predetermined surface), and forms an SLM (light intensity distribution on the illumination pupil (illumination pupil plane IPP) of the illumination optical system ILS. (Spatial light modulator) 22 (light intensity distribution forming member), optical rotation arranged between the array surface P1 and the reticle surface Ra, and changing the polarization state of at least part of the light toward the reticle surface Ra via the SLM 22 Optically rotatory members 29A, 29B, 29C and 29D (first optically rotatory members) formed of an optical material having optical properties, and uniaxial birefringence having no optical activity disposed between the array surface P1 and the reticle surface Ra. A birefringent member 31A, 31B, 31C, 31D (adjusting member) which is a crystal and is disposed so that its optical axis OAB and the like are parallel to the optical axis AXI of the illumination optical system ILS.

  The illumination optical system ILS includes a polarization control system 28, and the polarization control system 28 includes a plurality of polarization units 30A to 30D having the same configuration. Each of the polarization units 30 </ b> A to 30 </ b> D is an optical unit that controls the polarization state of a light beam emitted through the SLM 22 that forms a light intensity distribution on the illumination pupil. The polarization units 30A to 30D are arranged on the optical path of the light emitted from the SLM 22, and are emitted from the SLM 22 and the optical rotation members 29A to 29D that change the polarization state of at least a part of the light emitted from the SLM 22. Birefringent members 31A to 31D, which are disposed in the optical path of the light and are uniaxial birefringent crystals having no optical rotation, the optical axes of which are parallel to the optical axis AXI. Yes.

  The illumination method using the illumination optical system ILS is an illumination method that illuminates the reticle surface Ra with light from the light source 10. The illumination method includes a plurality of mirror elements 24 arranged on the array plane P1, and the illumination light IL from the light source 10 on the plurality of mirror elements 24 of the SLM 22 that forms a light intensity distribution on the illumination pupil of the illumination optical system ILS. , Step 114 for changing the polarization state of at least part of the light toward the reticle surface Ra via the SLM 22 using the optical rotation members 29A to 29D, and the optical axis parallel to the optical axis AXI. Step 116 of adjusting the polarization state of at least a part of the light toward the reticle surface Ra using the birefringent members 31A to 31D arranged as described above.

  According to the illumination optical system ILS or the illumination method of this embodiment, the optical member is exchanged by the cooperative action of the SLM 22 (light intensity distribution forming member) and the optical rotation members 29A to 29D in the polarization units 30A to 30D. In addition, it is possible to obtain a high degree of freedom regarding the change of the polarization state. Furthermore, when the polarization state at the time of emission of light (oblique incident light) incident on the optical rotation members 29A to 29D with a relatively large incident angle changes with respect to the polarization state at the time of emission of normal incident light (for example, slightly elliptical) In the case of polarized light), the polarization state of the emitted light is adjusted by the birefringent members 31A to 31D on the exit side (downstream) of the optical rotation members 29A to 29D (for example, the elliptically polarized light is adjusted to linearly polarized light). Can do. For this reason, it becomes possible to match the polarization state at the time of emission of the oblique incident light with the polarization state at the time of emission of the normal incident light, and the distribution of the polarization direction can be set with high accuracy by the illumination pupil plane IPP, and the pattern of the reticle R Can be exposed with higher accuracy.

  The birefringent members 31A to 31D can be arranged on the incident side (upstream) of the optical rotation members 29A to 29D. In this case, the birefringent members 31A to 31D are arranged on the incident side of the optical rotation members 29A to 29D. By adjusting the polarization state of the emitted light (for example, the linearly polarized light at the time of incidence is slightly adjusted to elliptically polarized light so as to become linearly polarized light after passing through the optical rotation members 29A to 29D), It becomes possible to match the polarization state at the time of emission with the polarization state at the time of emission of normal incident light.

  Further, by controlling the angle of each mirror element 24 of the SLM 22, the shape of the pupil intensity distribution (a broad concept including the size) can be easily set to an almost arbitrary shape, and the shape of the pupil intensity distribution can be changed. High degree of freedom. Furthermore, in the present embodiment, the polarization state of the light reflected by the SLM 22 is variable by the polarization control system 28 so that the cross-sectional area ratio (the ratio of the number of mirror elements 24 in the corresponding partial array regions D1 to D8 of the SLM 22) is variable. The distribution of the polarization direction is set. Therefore, the cooperative action of the SLM 22 and the polarization control system 28 allows the light intensity distribution (pupil intensity distribution) of the illumination pupil to be set to an almost arbitrary distribution without exchanging optical members, The polarization state of the illumination light IL can be easily set to a distribution of almost any combination of the eight polarization directions. Therefore, an extremely high degree of freedom can be obtained with respect to changing the light intensity distribution and the polarization state distribution.

  In the present embodiment, the illumination light IL is substantially supplied to the plurality of mirror elements 24 of the SLM 22 in the state of P-polarized light or S-polarized light, and the polarization control system 28 disposed on the downstream side of the SLM 22 vertically Linearly polarized light having a polarization direction different from that of the polarized light DV or the laterally polarized light DH is set. For this reason, the polarization state of the illumination light IL does not change to elliptically polarized light when reflected by the mirror element 24, and the polarization state distribution at the illumination pupil can be set with high accuracy.

  In addition, since the illumination optical system ILS of this embodiment includes the polarization control system 28 having four polarization units 30A to 30D, it is possible to set eight polarization direction distributions on the illumination pupil. However, when it is only necessary to obtain, for example, four polarization directions (for example, vertical polarization DV, horizontal polarization DH, and 45-degree polarization DSA, DSB) at the illumination pupil, the rotation angle of the polarization unit 30A of the polarization control system 28 is set, for example. The optical rotation angle of the polarization unit 30B may be 45 degrees, and the other optical rotation member polarization units 30C and 30D may be omitted. Alternatively, the polarization unit 30A that moves in the Z direction of the polarization control system 28 may be omitted, and the optical rotation angles of the three polarization units 30B to 30D that move in the other X direction may be 45 degrees clockwise, for example.

  Further, according to the exposure apparatus EX of the present embodiment, the illumination optical system ILS having a high degree of freedom with respect to the change of the shape and polarization state of the pupil intensity distribution is provided, and the reticle R and projection are performed with the illumination light IL from the illumination optical system ILS. The wafer W is exposed through the optical system PL. For this reason, the fine pattern can be transferred to the wafer W with high accuracy under appropriate illumination conditions realized in accordance with the pattern characteristics of the reticle R to be transferred.

In the above embodiment, the following modifications are possible.
First, in the example of FIG. 6A described above, for example, the optical rotation member 29B of the polarization unit 30B is formed from a positive crystal (for example, quartz), and the birefringent member 31B is also formed from a positive crystal (for example, magnesium fluoride). . These positive crystals are readily available. On the other hand, when the optical rotation member 29B is formed from a positive crystal, the birefringent member 31B may be formed from a negative crystal (for example, sapphire). In the case of a negative crystal, the optical axis OAB (set parallel to the optical axis AXI) is the fast axis, and two slow axes orthogonal to the front surface of the birefringent member 31B are set, for example. The

  Thus, when the optical rotation member 29B is formed from a positive crystal and the birefringent member 31B is formed from a negative crystal, if the correction effect (adjustment effect) of elliptically polarized light is high, a combination of these positive and negative crystals is selected. It is preferable to use it. When there is a negative crystal optical rotatory member and the elliptical polarization correction effect is high, the optical rotatory member 29B may be formed from a negative crystal and the birefringent member 31B may be formed from a positive crystal. However, when the correction effect of elliptically polarized light is enhanced by the combination of negative crystals, the optical rotation member 29B may be formed from a negative crystal, and the birefringent member 31B may also be formed from a negative crystal.

  In the above-described embodiment, the optical rotation members 29A to 29D and the birefringent members 31A to 31D constituting the polarization units 30A to 30D of the polarization control system 28 are in contact with or in close proximity, that is, adjacent to each other. . For this reason, the optical rotation members 29A to 29D and the corresponding birefringent members 31A to 31D can be easily driven (moved) integrally by the drive unit DR2. For example, a surface P3A (not shown) optically conjugate with the installation surface P3 is set downstream of the installation surface P3 by a relay optical system (not shown), and the optical rotation members 29A to 29D are installed on the installation surface P3, for example. Even if the birefringent members 31A to 31D are installed on the surface P3A, the optical rotation members 29A to 29D are driven by the driving unit DR2, and the birefringent members 31A to 31D are driven in synchronization with the driving unit DR2 by another driving unit. Good. Furthermore, the birefringent members 31A to 31D may be installed on the installation surface P3, and the optical rotation members 29A to 29D may be installed on the downstream surface P3A.

  Further, as shown in the polarization control system 28A of the modification of FIG. 1C, for example, with respect to the polarization unit 30A1 whose rotation angle in the polarization direction is as small as 22.5 degrees, this polarization unit 30A1 has an optical rotation angle of 22.5. You may comprise only the optical rotation member 29A of a degree. In the polarization control system 28A, the polarization units 30B1, 30C1, and 30D1 whose rotation angles in the other polarization directions are 90 degrees, 45 degrees, and 90 degrees, for example, are formed on the incident surfaces of the optical rotation members 29B to 29D, respectively. 31D is fixed and formed.

When the optical rotation angle is small as in the polarization unit 30A1, since the degree of elliptical polarization with respect to obliquely incident light is small, the illumination pupil plane can be provided without providing the birefringent member 31D for correcting (adjusting) elliptically polarized light. It becomes possible to keep the polarization state error in the IPP within an allowable range. Therefore, elliptical polarization can be suppressed and the configuration of the polarization control system 28A can be simplified.
In the above embodiment, when the polarization unit 30B of FIG. 6A is used, when obliquely incident light enters the optical rotation member 29B, elliptically polarized light DHE generated at the time of emission is linearly polarized light DHL, DHR by the birefringent member 31B. Adjusted to The rotation angle of the linearly polarized light DHL and DHR from the accurate laterally polarized light DH is small. However, in order to bring the linearly polarized light DHL and DHR closer to the target linearly polarized light (in this case, the laterally polarized light DH), as shown in the polarization unit 30B2 of the main part of the polarization control system 28B of the modified example of FIG. A flat plate optical rotatory member (hereinafter referred to as a correction optical rotatory member) 29F formed of an optical material having optical rotatory power may be disposed on the exit surfaces of the optical rotatory member 29B and the birefringent member 31B. The polarization unit 30B2 including the optical rotatory member 29B, the birefringent member 31B, and the correcting optical rotatory member 29F can be moved in the X direction so as to integrally cross the cross section 50B of the illumination light by the drive unit DR2A.

  In FIG. 10A, the correction optical rotation member 29F is formed of, for example, an optical material (for example, quartz) having the same optical rotation as the optical rotation member 29B, and the optical axis of the correction optical rotation member 29F is also set parallel to the optical axis AXI. . Further, the thickness d3 of the correction optical rotation member 29F, and consequently the optical rotation angle (rotation angle of the polarization direction of the incident light) in the optical rotation member 29F, as shown in FIG. The linearly polarized lights DHL and DHR of the lights ILB and ILD that have passed through the refracting member 31B are set to rotate to the laterally polarized light DH, respectively. Other configurations are the same as those in FIGS. 6A and 1A.

  By using the polarization unit 30B2 of this modified example, light ILB and ILD (oblique incidence) that have passed through the optical rotation member 29B and the birefringent member 31B with an inclination with respect to the optical axis AXI and with an inclination in the Z direction and the X direction. Even if the light is linearly polarized light DHL, DLR slightly inclined with respect to the laterally polarized light DH, the direction of polarization is rotated so that the linearly polarized light DHL, DLR is accurately converted to the laterally polarized light DH by the correction optical rotation member 29F. Is done. Therefore, the distribution of the polarization state on the illumination pupil plane IPP can be brought closer to the target distribution with higher accuracy, and the pattern image of the reticle R can be exposed with higher accuracy.

  The deviation in angle between the linearly polarized light DHL, DHR and the laterally polarized light DH is smaller than, for example, a unit for setting the polarization direction (for example, 22.5 degrees) by the polarization control system 28B. The optical rotation angle is an angle considerably smaller than the set unit (or this angle + an integral multiple of 180 degrees). Therefore, the polarization state of the illumination light passing through the correction optical rotation member 29F is substantially not elliptically polarized.

  Further, for the polarization unit 30C whose polarization direction rotation angle in FIG. 8A is 45 degrees, for example, the linearly polarized 45 degree polarization DSA generated by the light ILG or the like in FIG. A correction optical rotation member (not shown) for correcting a slight deviation from the above may be provided. Thereby, the distribution of the polarization state can be set with higher accuracy. Similarly, for the polarization unit 30A having a polarization direction rotation angle of 22.5 degrees, for example, as shown in FIG. 1B, a slight angular deviation of linearly polarized light that may occur in obliquely incident light, for example, on the exit surface thereof. A correction optical rotatory member (not shown) for correcting the above may be provided.

In the example of FIG. 10A, the correction optical rotation member 29F is disposed adjacent to the exit surfaces (downstream) of the optical rotation member 29B and the birefringent member 31B. However, the arrangement order of the optical rotation member 29B, the birefringent member 31B, and the correction optical rotation member 29F along the optical axis AXI is arbitrary. For example, the correction optical rotation member 29F is adjacent to the incident surface (upstream) of the optical rotation member 29B. May be arranged.
Further, the correction optical rotation member 29F can be disposed at a position optically conjugate with the optical rotation member 29B.

  Further, when the optical material of the correction optical rotation member 29F (thickness d3) is the same as the optical material of the optical rotation member 29B (thickness d1), as shown in FIG. And the correction optical rotation member 29F may be integrated. In this case, an optical rotation member 29B1 having a thickness (d1 + d3) formed of an optical material for forming the optical rotation member 29B is installed as an integrated optical rotation member 29B and a correction optical rotation member 29F. Further, a birefringent member 31B (thickness d2) is fixed to the exit surface of the optical rotatory member 29B1 by adhesion or the like, and the optical rotatory member 29B1 and the birefringent member 31B have their optical axes parallel to the optical axis AXI. Has been placed. When the optical rotation member 29B1 integrated in this way is used, the manufacturing cost can be reduced as compared with the case where the optical rotation members 29B and 29F are manufactured individually, and the support of the optical rotation member 29B1 by the drive unit DR2A is easy. is there.

As shown in FIG. 10D, a birefringent member 31B may be disposed on the incident surface side of the illumination light IL of the optical rotation member 29B1.
In each of the above-described embodiments, the optical rotation members 29A to 29D and the like are made of, for example, quartz. However, the present invention is not limited to this, and the optical rotation members 29A to 29D and the like can be formed using other appropriate optical materials having optical activity.
Further, in each of the above-described embodiments, various forms are possible with respect to the outer shape, number, arrangement, optical characteristics, and the like of the optical elements (such as the optical rotation member) constituting the polarization control system 28.
Further, in each of the above-described embodiments, as the SLM 22 having the plurality of mirror elements 24 arranged two-dimensionally and individually controlled, the angles of the plurality of reflection surfaces arranged two-dimensionally can be individually controlled. A spatial light modulator is used. However, the present invention is not limited to this. For example, a spatial light modulator that can individually control the height (position) of a plurality of two-dimensionally arranged reflecting surfaces can be used. As such a spatial light modulator, for example, the spatial light modulator disclosed in FIG. 1d of US Pat. No. 5,312,513 and US Pat. No. 6,885,493 can be used.

Furthermore, in the above-described embodiment, the SLM 22 includes a plurality of mirror elements 24 arranged two-dimensionally within a predetermined plane. However, the present invention is not limited to this, and the SLM 22 is arranged within the predetermined plane and individually controlled. It is also possible to use a transmissive spatial light modulator including a plurality of transmissive optical elements.
In the above-described embodiment, the optical rotation members 30A to 30C and the like rotate the polarization direction of incident linearly polarized light in units of 22.5 degrees or 45 degrees, but the rotation angle of the polarization direction is 22.5 degrees or It may be set not in units of 45 degrees but in units of finer angles.

  In the illumination optical system of the above embodiment, the SLM 22 is used as a light intensity distribution forming member that forms a light intensity distribution on the illumination pupil of the illumination optical system. However, even when using, for example, a diffractive optical element (DOE) as a light intensity distribution forming member, in order to set the polarization direction distribution within the light intensity distribution set by this diffractive optical element, The polarization control system 28 (polarization units 30A to 30D) of the embodiment can be used.

  Further, when an electronic device (or a micro device) such as a semiconductor device is manufactured using the exposure apparatus EX or the exposure method of the above embodiment, the electronic device has a function / performance design of the electronic device as shown in FIG. Step 221 for performing a step, Step 222 for fabricating a reticle (mask) based on this design step, Step 223 for fabricating a substrate (wafer) as a base material of the device and applying a resist, and the exposure apparatus ( Substrate processing step 224 including a step of exposing a reticle pattern to a substrate (photosensitive substrate) by an exposure method), a step of developing the exposed substrate, a heating (curing) and etching step of the developed substrate, and a device assembly step (dicing) (Including processing processes such as processes, bonding processes, and packaging processes) 22 And an inspection step 226, and the like.

  In other words, the device manufacturing method transfers the reticle pattern image onto the substrate (wafer) using the exposure apparatus EX (exposure method) of the above-described embodiment, and the pattern image transferred to the substrate (wafer). Processing the substrate based on the image of the pattern (development, etching, etc. in step 224). In this case, according to the above-described embodiment, the illumination condition of the reticle including the polarization state can be optimized with high accuracy, and the reticle pattern can be exposed to the substrate with high accuracy, so that the electronic device can be manufactured with high accuracy.

  In addition, the present invention is not limited to application to an exposure apparatus for manufacturing a semiconductor device, for example, an exposure apparatus for a display device such as a liquid crystal display element formed on a square glass plate or a plasma display, It can also be widely applied to an exposure apparatus for manufacturing various devices such as an image sensor (CCD or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

In the above-described embodiment, the present invention is applied to the illumination optical system that illuminates the mask (wafer) in the exposure apparatus. However, the present invention is not limited to this, and the irradiated surface other than the mask (wafer) is used. The present invention can also be applied to a general illumination optical system that illuminates the light.
Thus, the present invention is not limited to the above-described embodiments, and various configurations can be taken without departing from the gist of the present invention.

EX ... exposure apparatus, ILS ... illumination optical system, PL ... projection optical system, R ... reticle, 10 ... light source, 22 ... spatial light modulator (SLM), 26 ... relay optical system, 28 ... polarization control system, 29A to 29D ... Optical rotator, 29F ... Optical rotator for correction, 30A to 30D ... Polarization unit, 31A to 31D ... Birefringent member, 34 ... Microlens array, 36 ... Illumination controller

Claims (40)

In the illumination optical system that illuminates the illuminated surface with light from the light source,
A light intensity distribution forming member that is disposed within a predetermined plane and forms a light intensity distribution on an illumination pupil of the illumination optical system;
The optical material is disposed between the predetermined surface and the irradiated surface, and is formed of an optical material having optical activity that changes the polarization state of at least a part of the light toward the irradiated surface via the light intensity distribution forming member. A first optical rotation member;
A uniaxial birefringent crystal having no optical rotation and disposed between the predetermined surface and the irradiated surface, the optical axis of which is disposed parallel to the optical axis of the illumination optical system. An adjustment member;
An illumination optical system comprising:   2. The illumination according to claim 1, wherein the adjustment member is capable of adjusting a polarization state of at least a part of the elliptically polarized light out of the light passing through the first optical rotation member to a linear polarization state. Optical system.   2. The illumination optical system according to claim 1, wherein the adjustment member is capable of adjusting at least a part of linearly polarized light out of the light passing through the first optical rotation member into an elliptically polarized state.   The illumination optical system according to any one of claims 1 to 3, wherein the first optical rotation member and the adjustment member are disposed at optically conjugate positions.   The illumination optical system according to claim 1, wherein the adjustment member is disposed adjacent to the first optical rotation member.   The illumination optical system according to claim 1, wherein the uniaxial birefringent crystal is a magnesium fluoride or sapphire crystal. When the polarization state of light that is inclined at a predetermined angle with respect to the optical axis of the illumination optical system and passes through the first optical rotation member is adjusted to linearly polarized light or elliptically polarized light, the minimum of the adjusting member in the optical axis direction is adjusted. The thickness is da, and the minimum thickness in the optical axis direction of the adjustment member when the polarization state of light incident on the adjustment member at the predetermined angle returns to the incident state is db.
The illumination optical system according to claim 1, wherein a thickness of the adjustment member in the optical axis direction is set to da + i · db (i is an integer of 0 or more). The light supplied from the light source to the light intensity distribution forming member is linearly polarized light,
The illumination optical system according to any one of claims 1 to 7, wherein the first optical rotation member emits light by rotating a polarization direction of incident light in a linearly polarized state by 80 degrees to 100 degrees. . The first optical rotation member moves in at least one of the first and second directions intersecting each other in a plane perpendicular to the optical axis of the illumination optical system on an arrangement surface optically conjugate with the predetermined surface. An optical rotatory member that is arranged so as to rotate the polarization direction of at least part of the light from the light intensity distribution forming member by a first angle;
The illumination optical system according to any one of claims 1 to 8, further comprising a drive unit that can move the first optical rotation member and the adjustment member integrally along the arrangement surface.   The third optical rotation member formed of an optical material having optical activity for adjusting the polarization direction of the light that has passed through the first optical rotation member and the adjustment member is provided. The illumination optical system according to one item.   The third optical rotation member formed of an optical material having optical activity for adjusting the polarization direction of light passing through the first optical rotation member and the adjustment member is provided. The illumination optical system according to one item.   12. The illumination optical system according to claim 10, further comprising a drive unit capable of integrally moving the first optical rotation member and the third optical rotation member.   The illumination optical system according to claim 10 or 11, wherein the first optical rotation member and the third optical rotation member are integrated.   The illumination optical system according to claim 1, further comprising a relay optical system disposed between the predetermined surface and an arrangement surface on which the first optical rotation member is arranged. With an optical integrator,
The illumination according to any one of claims 1 to 14, wherein the first optical rotation member and the adjustment member are disposed in an optical path between the light intensity distribution forming member and the optical integrator. Optical system.   The light intensity distribution forming member is a spatial light modulator having a plurality of mirror elements that are two-dimensionally arranged in the predetermined plane and a drive unit that individually drives and controls the postures of the plurality of mirror elements. The illumination optical system according to any one of claims 1 to 15, wherein   An exposure apparatus comprising the illumination optical system according to any one of claims 1 to 16 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. Using the exposure apparatus according to claim 17 to expose the predetermined pattern on the photosensitive substrate;
Developing the photosensitive substrate having the predetermined pattern transferred thereon, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
Processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method comprising: A polarization unit that is arranged in a predetermined plane and controls a polarization state of a light beam emitted through a light intensity distribution forming member that forms a light intensity distribution on an illumination pupil of an illumination optical system,
A first optical material arranged in the optical path of the light emitted from the light intensity distribution forming member and made of an optical material having optical rotation that changes the polarization state of at least part of the light emitted from the light intensity distribution forming member. 1 optical rotation member,
A uniaxial birefringent crystal without optical rotation arranged in the optical path of the light emitted from the light intensity distribution forming member, and arranged so that its optical axis is parallel to the optical axis of the illumination optical system An adjusting member to be
A polarization unit comprising:   The polarized light according to claim 19, wherein the adjustment member is capable of adjusting a polarization state of at least a part of the elliptically polarized light out of the light passing through the first optical rotation member to a linear polarization state. unit.   The polarization unit according to claim 19, wherein the adjustment member is capable of adjusting at least a part of linearly polarized light out of the light passing through the first optical rotation member into an elliptically polarized state.   The polarization unit according to any one of claims 19 to 21, wherein the first optical rotation member and the adjustment member are disposed at positions optically conjugate with each other.   The polarization unit according to any one of claims 19 to 21, wherein the adjustment member is disposed adjacent to the first optical rotation member.   The polarizing unit according to any one of claims 19 to 23, wherein the uniaxial birefringent crystal is a magnesium fluoride or sapphire crystal.   The polarization unit according to any one of claims 19 to 24, wherein the first optical rotation member emits light by rotating the polarization direction of incident light in a state of linearly polarized light by 80 degrees to 100 degrees. The first optical rotation member moves in at least one of the first and second directions intersecting each other in a plane perpendicular to the optical axis of the illumination optical system on an arrangement surface optically conjugate with the predetermined surface. An optical rotatory member that is arranged so as to rotate the polarization direction of at least part of the light from the light intensity distribution forming member by a first angle;
The polarizing unit according to any one of claims 19 to 25, further comprising a drive unit that can move the first optical rotation member and the adjustment member integrally along the arrangement surface.   27. A third optical rotation member formed of an optical material having optical activity for adjusting a polarization direction of light that has passed through the first optical rotation member and the adjustment member. The polarizing unit according to one item.   27. The third optical rotation member formed of an optical material having optical activity for adjusting a polarization direction of light passing through the first optical rotation member and the adjustment member, 27. The polarizing unit according to one item.   The polarizing unit according to claim 27 or 28, further comprising a drive unit that can move the first optical rotation member and the third optical rotation member integrally.   The polarization unit according to claim 27 or 28, wherein the first optical rotation member and the third optical rotation member are integrated. In the illumination method of illuminating the illuminated surface with light from the light source,
Supplying light from the light source to a light intensity distribution forming member disposed in a predetermined plane and forming a light intensity distribution on an illumination pupil of the illumination optical system;
Using a first optical rotation member formed of an optical material having optical activity, changing the polarization state of at least a part of the light toward the irradiated surface via the light intensity distribution forming member;
A uniaxial birefringent crystal having no optical rotation and disposed between the predetermined surface and the irradiated surface, the optical axis of which is disposed parallel to the optical axis of the illumination optical system. Using an adjustment member to adjust the polarization state of at least a portion of the light toward the irradiated surface;
The lighting method characterized by including.   Adjusting the polarization state of the at least part of the light includes adjusting the polarization state of at least a part of the elliptically polarized light out of the light passing through the first optical rotation member to a linear polarization state. The illumination method according to claim 31, wherein:   The adjusting the polarization state of the at least part of the light includes adjusting at least a part of the linearly polarized light out of the light passing through the first optical rotation member to an elliptical polarization state. Item 32. The illumination method according to Item 31.   Changing the polarization state of the at least part of the light using the first optical rotation member includes rotating the polarization direction of the incident light in the state of linear polarization and emitting it by rotating it by 80 degrees to 100 degrees. The illumination method according to any one of claims 31 to 33, which is characterized by the following.   The illumination method according to any one of claims 31 to 34, including moving the first optical rotation member and the adjustment member integrally along an arrangement surface of the first optical rotation member.   36. The method includes adjusting a polarization direction of light that has passed through the first optical rotation member and the adjustment member using a third optical rotation member formed of an optical material having optical activity. The illumination method according to any one of the above.   36. The method includes adjusting a polarization direction of light passing through the first optical rotation member and the adjustment member using a third optical rotation member formed of an optical material having optical activity. The illumination method according to any one of the above.   38. The illumination method according to claim 36 or 37, comprising moving the first optical rotation member and the third optical rotation member integrally. A predetermined pattern is illuminated using the illumination method according to any one of claims 31 to 38,
An exposure method comprising exposing the predetermined pattern onto a photosensitive substrate. Using the exposure method of claim 39 to expose the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate having the predetermined pattern transferred thereon, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
Processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method comprising:

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