JP2012059848A - Polarization conversion unit, illumination optical system, and method of manufacturing device - Google Patents

Abstract

A polarization conversion unit that has a structure that is relatively easy to manufacture and is arranged in an optical path of an illumination optical system and can realize a pupil intensity distribution in a circumferential polarization state with high continuity.
In a polarization conversion unit including a polarization conversion member 51 that converts incident light into light having a predetermined polarization state and emits the light, the polarization conversion member 51 is formed of an optically rotatory optical material and crosses the optical axis. A plurality of polarization converters 511 to 514 arranged in parallel along the plane, and the plurality of polarization converters 511 to 514 are a planar entrance surface and a planar exit surface that is not parallel to the entrance surface. Respectively.
[Selection] Figure 4

Description

  The present invention relates to a polarization conversion unit, an illumination optical system, an exposure apparatus, and a device manufacturing method. More specifically, the present invention relates to an illumination optical system suitable for an exposure apparatus for manufacturing devices such as a semiconductor element, an image sensor, a liquid crystal display element, and a thin film magnetic head in a lithography process.

  In a typical exposure apparatus of this type, a secondary light source (generally an illumination pupil), which is a substantial surface light source composed of a number of light sources, passes through a fly-eye lens as an optical integrator. A predetermined light intensity distribution). Hereinafter, the light intensity distribution in the illumination pupil is referred to as “pupil intensity distribution”. The illumination pupil is a position where the illumination surface becomes the Fourier transform plane of the illumination pupil by the action of the optical system between the illumination pupil and the illumination surface (a mask or a wafer in the case of an exposure apparatus). Defined.

  The light from the secondary light source is collected by the condenser optical system and then illuminates the mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask forms an image on the wafer via the projection optical system, and the mask pattern is projected and exposed (transferred) onto the wafer. The pattern formed on the mask is miniaturized, and it is indispensable to obtain a uniform illuminance distribution on the wafer in order to accurately transfer the fine pattern onto the wafer.

  In order to realize an illumination condition suitable for faithfully transferring a fine pattern in any direction, an annular secondary light source is formed on the rear focal plane of the fly-eye lens or in the vicinity of the illumination pupil. Has been proposed (see, for example, Patent Documents), in which a light beam passing through the secondary light source is set in a linear polarization state whose polarization direction is the circumferential direction (hereinafter referred to as “circumferential polarization state” for short). 1). In the illumination optical system described in Patent Document 1, the polarization state of light passing through each divided region is changed in the circumferential direction by using an optical rotatory polarization conversion element having fan-shaped divided regions divided into four to eight. By setting, a so-called circumferential polarization state with relatively low continuity is realized.

US Patent Application Publication No. 2006/0170901

  In order to achieve the effect of circumferential polarization more satisfactorily, for example, it is desired to realize a circumferential polarization state with high continuity based on a division finer than eight divisions. However, in the polarization conversion element proposed in Patent Document 1, as many members as the number of divisions having a predetermined thickness corresponding to each divided region are prepared, and these members are accurately aligned along the in-plane direction. Since they need to be held side by side, the difficulty of manufacturing (a broad concept that includes holding a plurality of members correctly aligned) tends to increase as the number of divisions increases, and the manufacturing cost tends to increase.

  The present invention has been made in view of the above-described problems, has a structure that is relatively easy to manufacture, and is arranged in the optical path of an illumination optical system to provide a highly continuous pupil intensity distribution in a circumferentially polarized state. An object is to provide a polarization conversion unit that can be realized. The present invention also provides an illumination optical system capable of illuminating an irradiated surface with light in a desired circumferential polarization state using a polarization conversion unit that realizes a highly continuous pupil intensity distribution in the circumferential polarization state. The purpose is to provide. In addition, the present invention can accurately transfer a fine pattern onto a photosensitive substrate under an appropriate illumination condition using an illumination optical system that illuminates a predetermined pattern with light having a desired circumferential polarization state. An object of the present invention is to provide an exposure apparatus and a device manufacturing method.

In order to solve the above problems, in the first embodiment of the present invention, in a polarization conversion unit including a polarization conversion member that converts incident light into light having a predetermined polarization state and emits the light,
The polarization conversion member has a plurality of polarization conversion units formed of an optical rotatory optical material and arranged in parallel along a plane crossing the optical axis,
The plurality of polarization conversion units each have a planar incident surface and a planar exit surface that is not parallel to the incident surface.

In the second embodiment of the present invention, in the illumination optical system that illuminates the illuminated surface with the light from the light source,
Provided is an illumination optical system comprising a first type of polarization conversion unit disposed in an optical path between the light source and the irradiated surface.

In the third embodiment of the present invention, in the illumination optical system that illuminates the illuminated surface with light from the light source,
An illumination optical system comprising: a plurality of polarization conversion units of a first form, wherein the plurality of polarization conversion units are selectively disposed in an illumination optical path between the light source and the irradiated surface. provide.

  According to a fourth aspect of the present invention, there is provided an exposure apparatus comprising the illumination optical system according to the second or third aspect for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. To do.

In the fifth embodiment of the present invention, using the exposure apparatus of the fourth embodiment, exposing 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;
And processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method is provided.

  The polarization conversion unit of the present invention has a configuration that is relatively easy to manufacture, and is arranged in the optical path of the illumination optical system to realize a highly continuous pupil intensity distribution in the circumferential polarization state. In the illumination optical system of the present invention, the irradiated surface can be illuminated with light in a desired circumferential polarization state using a polarization conversion unit that realizes a highly continuous pupil intensity distribution in the circumferential polarization state. In the exposure apparatus of the present invention, a fine pattern is accurately applied to a photosensitive substrate under appropriate illumination conditions using an illumination optical system that illuminates a pattern surface as an irradiated surface with light in a desired circumferentially polarized state. It can be transferred and thus a good device can be produced.

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure which shows a mode that an annular | circular shaped light intensity distribution is formed in the pupil surface of an afocal lens. It is the figure which looked at the polarization conversion member concerning this embodiment from the entrance side along the optical axis. It is a perspective view which shows schematically the structure of the polarization conversion unit of this embodiment. It is a figure explaining the optical rotatory power of quartz. It is a figure which shows a mode that an annular | circular shaped light intensity distribution is formed in the illumination direction pupil immediately after a micro fly's eye lens in the circumferential polarization state. It is a figure which shows thickness distribution of the polarization conversion part in this embodiment. It is a figure which shows thickness distribution requested | required of a polarization conversion part in order to implement | achieve an ideal circumferential polarization state. It is a figure which shows a mode that an annular | circular shaped light intensity distribution is formed in the radial polarization state in the illumination pupil immediately after a micro fly's eye lens. It is a perspective view which shows roughly the structure of the polarization conversion member concerning a modification. It is a flowchart which shows the manufacturing process of a semiconductor device. It is a flowchart which shows the manufacturing process of liquid crystal devices, such as a liquid crystal display element.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, the Z axis along the normal direction of the exposure surface (transfer surface) of the wafer W, which is a photosensitive substrate, and the Y axis in the direction parallel to the paper surface of FIG. In the W exposure plane, the X axis is set in a direction perpendicular to the paper surface of FIG.

  Referring to FIG. 1, in the exposure apparatus of the present embodiment, exposure light (illumination light) is supplied from a light source LS. As the light source LS, for example, an ArF excimer laser light source that supplies light with a wavelength of 193 nm, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, or the like can be used. The light beam emitted from the light source LS enters the afocal lens 4 through the shaping optical system 1, the polarization state switching unit 2, and the diffractive optical element 3. The shaping optical system 1 has a function of converting a substantially parallel light beam from the light source LS into a light beam having a predetermined rectangular cross section and guiding it to the polarization state switching unit 2.

  The polarization state switching unit 2 includes, in order from the light source side, a quarter-wave plate 2a that converts the incident elliptically polarized light into linearly polarized light with the crystal optical axis being rotatable about the optical axis AX, A half-wave plate 2b that changes the polarization direction of the linearly polarized light that is configured so that the crystal optical axis is rotatable about the optical axis AX, and a depolarizer that can be inserted into and removed from the illumination optical path (depolarizing element) 2c. The polarization state switching unit 2 has a function of converting light from the light source LS into linearly polarized light having a desired polarization direction and entering the diffractive optical element 3 with the depolarizer 2c retracted from the illumination optical path. In the state where the depolarizer 2c is set in the illumination optical path, the light from the light source LS is converted into substantially non-polarized light and incident on the diffractive optical element 3.

  The afocal lens 4 includes a front lens group 4a and a rear lens group 4b. The front focal position of the front lens group 4a substantially coincides with the position of the diffractive optical element 3, and the rear focal point of the rear lens group 4b. This is an afocal system (non-focal optical system) set so that the position and the position of the predetermined plane IP indicated by a broken line in the figure substantially coincide with each other. The diffractive optical element 3 is formed by forming a step having a pitch of about the wavelength of exposure light (illumination light) on the substrate, and has a function of diffracting an incident beam to a desired angle. Hereinafter, in order to simplify the explanation, it is assumed that the diffractive optical element 3 is a diffractive optical element for annular illumination.

  The diffractive optical element 3 for annular illumination has a function of forming an annular light intensity distribution in the far field (or Fraunhofer diffraction region) when a parallel light beam having a rectangular cross section is incident. Therefore, the substantially parallel light beam incident on the diffractive optical element 3 forms a ring-shaped light intensity distribution 21 at the pupil position of the afocal lens 4 as shown in FIG. 4 is injected. A polarization conversion unit 5 and a conical axicon system 6 are disposed at or near the pupil position of the afocal lens 4. The configuration and operation of the polarization conversion unit 5 will be described later. The configuration and operation of the conical axicon system 6 will also be described later.

  The light passing through the afocal lens 4 passes through a zoom lens 7 for varying a σ value (σ value = mask-side numerical aperture of the illumination optical system / mask-side numerical aperture of the projection optical system), and is a micro fly as an optical integrator. The light enters the eye lens (or fly eye lens) 8. The micro fly's eye lens 8 is, for example, an optical element composed of a large number of micro lenses having positive refracting power arranged vertically and horizontally and densely, and by performing etching treatment on a parallel plane plate, a micro lens group is formed. It is configured.

  Each micro lens constituting the micro fly's eye lens is smaller than each lens element constituting the fly eye lens. Further, unlike a fly-eye lens composed of lens elements isolated from each other, a micro fly-eye lens is formed integrally with a large number of micro lenses (micro refractive surfaces) without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly eye lens in that lens elements having positive refractive power are arranged vertically and horizontally. As the micro fly's eye lens 8, for example, a cylindrical micro fly's eye lens can be used. The configuration and action of the cylindrical micro fly's eye lens are disclosed in, for example, US Pat. No. 6,913,373.

  The position of the predetermined plane IP is disposed at or near the front focal position of the zoom lens 7, and the incident surface of the micro fly's eye lens 8 is disposed at or near the rear focal position of the zoom lens 7. In other words, the zoom lens 7 arranges the predetermined plane IP and the incident surface of the micro fly's eye lens 8 substantially in a Fourier transform relationship, and consequently the pupil surface of the afocal lens 4 and the incident surface of the micro fly's eye lens 8. Are arranged almost conjugate optically.

  Accordingly, on the incident surface of the micro fly's eye lens 8, for example, a ring-shaped illumination field centered on the optical axis AX is formed in the same manner as the pupil surface of the afocal lens 4. The overall shape of the annular illumination field changes in a similar manner depending on the focal length of the zoom lens 7. The light beam incident on the micro fly's eye lens 8 is two-dimensionally divided, and an illumination field formed on the entrance surface of the micro fly's eye lens 8 is positioned at the rear focal plane or in the vicinity thereof (the position of the illumination pupil). A secondary light source having substantially the same light intensity distribution, that is, a secondary light source (pupil intensity distribution) composed of a ring-shaped substantial surface light source centered on the optical axis AX is formed.

  On the rear focal plane of the micro fly's eye lens 8 or in the vicinity thereof, an illumination aperture stop 9 having an annular opening (light transmission part) corresponding to the annular secondary light source is disposed as necessary. Yes. The illumination aperture stop 9 is configured to be detachable with respect to the illumination optical path, and is configured to be switchable between a plurality of aperture stops having openings having different sizes and shapes. As an aperture stop switching method, for example, a well-known turret method or slide method can be used. The illumination aperture stop 9 is disposed at a position substantially optically conjugate with the entrance pupil plane of the projection optical system PL, and defines a range that contributes to illumination of the secondary light source.

  The light that has passed through the micro fly's eye lens 8 and the illumination aperture stop 9 illuminates the mask blind 11 in a superimposed manner via the condenser optical system 10. Thus, a rectangular illumination field corresponding to the shape and focal length of the microlens of the micro fly's eye lens 8 is formed on the mask blind 11 as an illumination field stop. The light that has passed through the rectangular opening (light transmission portion) of the mask blind 11 passes through the imaging optical system 12 including the front lens group 12a and the rear lens group 12b, and the mask M on which a predetermined pattern is formed. Are illuminated in a superimposed manner. That is, the imaging optical system 12 forms an image of the rectangular opening of the mask blind 11 on the mask M.

  A pattern to be transferred is formed on the mask M held on the mask stage MS. The light transmitted through the pattern of the mask M forms an image of the mask pattern on the wafer (photosensitive substrate) W held on the wafer stage WS via the projection optical system PL. Thus, by performing batch exposure or scan exposure while driving and controlling the wafer W two-dimensionally in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, each exposure region of the wafer W is masked. M patterns are sequentially exposed.

  The conical axicon system 6 includes, in order from the light source side, a first prism member 6a having a flat surface facing the light source side and a concave conical refractive surface facing the mask side, and a convex conical shape facing the plane toward the mask side and the light source side. And a second prism member 6b facing the refractive surface. The concave conical refracting surface of the first prism member 6a and the convex conical refracting surface of the second prism member 6b are complementarily formed so as to be in contact with each other. Further, at least one of the first prism member 6a and the second prism member 6b is configured to be movable along the optical axis AX, and the interval between the first prism member 6a and the second prism member 6b is configured to be variable. Has been.

  Here, in a state where the first prism member 6a and the second prism member 6b are in contact with each other, the conical axicon system 6 functions as a plane parallel plate and has no effect on the annular secondary light source formed. . However, if the first prism member 6a and the second prism member 6b are separated from each other, the width of the annular secondary light source (1/2 of the difference between the outer diameter and the inner diameter of the annular secondary light source) becomes constant. While maintaining, the outer diameter (inner diameter) of the annular secondary light source changes. That is, the annular ratio (inner diameter / outer diameter) and size (outer diameter) of the annular secondary light source change.

  The zoom lens 7 has a function of enlarging or reducing the entire shape of the annular secondary light source in a similar manner. For example, by enlarging the focal length of the zoom lens 7 from a minimum value to a predetermined value, the entire shape of the annular secondary light source is similarly enlarged. In other words, due to the action of the zoom lens 7, both the width and size (outer diameter) change without changing the annular ratio of the annular secondary light source. As described above, the annular ratio and size (outer diameter) of the annular secondary light source can be controlled by the action of the conical axicon system 6 and the zoom lens 7.

  In the present embodiment, as described above, the secondary light source formed by the micro fly's eye lens 8 is used as the light source, and the mask M arranged on the irradiated surface of the illumination optical system (1-12) is Koehler illuminated. For this reason, the position where the secondary light source is formed is optically conjugate with the position of the aperture stop AS of the projection optical system PL, and the formation surface of the secondary light source is the illumination pupil plane of the illumination optical system (1-12). Can be called. Typically, the irradiated surface (the surface on which the mask M is disposed or the surface on which the wafer W is disposed when the illumination optical system including the projection optical system PL is considered) is optical with respect to the illumination pupil plane. A Fourier transform plane.

  The pupil intensity distribution is a light intensity distribution (luminance distribution) on the illumination pupil plane of the illumination optical system (1-12) or a plane optically conjugate with the illumination pupil plane. When the number of wavefront divisions by the micro fly's eye lens 8 is relatively large, the overall light intensity distribution formed on the incident surface of the micro fly's eye lens 8 and the overall light intensity distribution of the entire secondary light source (pupil intensity distribution). ) And a high correlation. For this reason, the light intensity distribution on the incident surface of the micro fly's eye lens 8 and the surface optically conjugate with the incident surface can also be referred to as a pupil intensity distribution. That is, the pupil plane of the afocal lens 4 that is optically conjugate with the incident plane of the micro fly's eye lens 8 can also be called an illumination pupil plane.

  In place of the diffractive optical element 3 for annular illumination, a plurality of diffractive optical elements (not shown) for multipole illumination (two-pole illumination, four-pole illumination, octupole illumination, etc.) are set in the illumination optical path. Polar lighting can be performed. A diffractive optical element for multipole illumination forms a light intensity distribution of multiple poles (bipolar, quadrupole, octupole, etc.) in the far field when a parallel light beam having a rectangular cross section is incident. Has the function of Accordingly, the light beam that has passed through the diffractive optical element for multipole illumination is incident on the incident surface of the micro fly's eye lens 8 from, for example, an illumination field having a plurality of predetermined shapes (arc shape, circular shape, etc.) centered on the optical axis AX. To form a multipolar illuminator. As a result, the same multipolar secondary light source as the illumination field formed on the incident surface is also formed on or near the rear focal plane of the micro fly's eye lens 8.

  Moreover, instead of the diffractive optical element 3 for annular illumination, a normal circular illumination can be performed by setting a diffractive optical element (not shown) for circular illumination in the illumination optical path. The diffractive optical element for circular illumination has a function of forming a circular light intensity distribution in the far field when a parallel light beam having a rectangular cross section is incident. Therefore, the light beam that has passed through the diffractive optical element for circular illumination forms, for example, a circular illumination field around the optical axis AX on the incident surface of the micro fly's eye lens 8. As a result, a secondary light source having the same circular shape as the illumination field formed on the incident surface is also formed on or near the rear focal plane of the micro fly's eye lens 8. Also, instead of the diffractive optical element 3 for annular illumination, various forms of modified illumination can be performed by setting a diffractive optical element (not shown) having appropriate characteristics in the illumination optical path. As a switching method of the diffractive optical element 3, for example, a known turret method or slide method can be used.

  As described above, the polarization conversion unit 5 is disposed at or near the pupil position of the afocal lens 4, that is, the position of the illumination pupil of the illumination optical system (1 to 12) or the vicinity thereof. Hereinafter, in order to facilitate understanding of the description, the polarization conversion unit 5 is disposed at a position immediately before the illumination pupil in the optical path of the afocal lens 4 so as to be fixed or detachable with respect to the optical path. Shall. When the diffractive optical element 3 for annular illumination is disposed in the illumination optical path, a light beam having an annular cross section enters the polarization conversion unit 5.

  In the present embodiment, linearly polarized light polarized in the Y direction is incident on the polarization conversion unit 5 by the action of the polarization state switching unit 2 during annular illumination. Referring to FIG. 1, the polarization conversion unit 5 sequentially converts the incident light into light having a predetermined polarization state and emits the light by the polarization conversion member 51 in order from the light incident side. And a correction member 52 for compensation. As shown in FIG. 3, the polarization conversion member 51 includes four polarization conversion units 511, 512, and 513 arranged in parallel along an XY plane (generally, a plane that crosses the optical axis AX) orthogonal to the optical axis AX. 514.

  The polarization converters 511 to 514 have the same square outer shape, and are arranged so as to correspond to a quadrangular region obtained by equally dividing a circle centered on the optical axis AX into four. . The polarization conversion units 511 to 514 are arranged such that square diagonal lines 511a, 512a, 513a, and 514a extend from the optical axis AX in the X direction or the Y direction. As a result, the outer shape of the polarization conversion member 51 is a square, and a pair of diagonal lines of the square extend in the X direction and the Y direction. In FIG. 3, two circles 21 a and 21 b indicated by broken lines indicate the inner and outer contours of the annular light intensity distribution 21, and the circle indicated by an alternate long and short dash line indicates the center line (outside of the annular light intensity distribution 21. (Corresponding to a circle having an intermediate diameter between the diameter and the inner diameter) 21c.

  As clearly shown in FIG. 4, the polarization converters 511 to 514 each have a planar incident surface and a planar exit surface that is not parallel to the incident surface. The incident surfaces of the polarization conversion units 511 to 514 are orthogonal to the optical axis AX, and the exit surfaces thereof are inclined with respect to a plane orthogonal to the optical axis AX. The four polarization conversion units 511 to 514 are arranged such that their incident surfaces coincide with one plane orthogonal to the optical axis AX. As a result, the incident surface of the polarization conversion member 51 is planar, and its exit surface is uneven. Alternatively, the exit surfaces of the polarization conversion units 511 to 514 may be orthogonal to the optical axis AX, and the incident surfaces may be inclined with respect to a plane orthogonal to the optical axis AX. In that case, the exit surface of the polarization conversion member 51 is planar, and the incident surface is uneven.

  Of the four polarization conversion units 511 to 514, a pair of polarization conversion units facing each other across the optical axis AX have the same configuration. That is, the polarization conversion units 511 and 513 have the same configuration, and the polarization conversion units 512 and 514 have the same configuration. The polarization conversion units 511 to 514 are arranged so as to have the same thickness along the diagonal lines 511a to 514a (that is, straight lines extending in the radial direction of a circle centered on the optical axis AX). In other words, the exit surfaces of the polarization converters 511 to 514 are inclined in a direction orthogonal to the diagonal lines 511a to 514a.

  The polarization conversion units 511 to 514 are formed of quartz which is an optically rotatory optical material, and the crystal optical axis thereof extends in the Z direction (so as to extend parallel to the optical axis AX), that is, the traveling direction of incident light. It is set to almost match. The correction member 52 is disposed adjacent to the exit side of the polarization conversion member 51 and is made of fluorite or quartz, which is an optical material having no optical rotation. The correction member 52 has a required shape for functioning as a compensator that compensates for the light deflection action (change in the traveling direction of light) by the polarization conversion member 51.

  In other words, the correction member 52 has a correction unit 521 having a shape complementary to the polarization conversion unit 511, a correction unit 522 having a shape substantially complementary to the polarization conversion unit 512, and a shape substantially complementary to the polarization conversion unit 513. A correction unit 523 and a correction unit 524 having a shape substantially complementary to the polarization conversion unit 514 are provided. The correction units 521 to 524 are arranged so as to face the polarization conversion units 511 to 514. The outer shape of the correction member 52 is a square, its incident surface is an uneven surface, and its emission surface is a flat surface.

  The polarization conversion member 51 is manufactured by combining polarization conversion portions 511 to 514 obtained by processing one surface of a plane parallel plate made of quartz into a required planar shape. Alternatively, the polarization conversion member 51 as a single optical member can be manufactured by processing one surface of a plane-parallel plate made of quartz into a required uneven surface shape. Similarly, the correction member 52 is manufactured by combining correction parts 521 to 524 obtained by processing one surface of a parallel flat plate made of fluorite or quartz into a required plane shape. Alternatively, the correction member 52 as a single optical member can be manufactured by processing one surface of a plane parallel plate made of fluorite or quartz into a required uneven surface shape.

Hereinafter, with reference to FIG. 5, the optical rotation of the crystal will be briefly described. Referring to FIG. 5, a parallel flat plate-like optical member 100 made of quartz having a thickness d is arranged so that the crystal optical axis thereof coincides with the optical axis AX. In this case, due to the optical rotation of the optical member 100, the incident linearly polarized light is emitted in a state where the polarization direction is rotated by θ around the optical axis AX. At this time, the rotation angle (optical rotation angle) θ in the polarization direction due to the optical rotation of the optical member 100 is expressed by the following formula (a) by the thickness d of the optical member 100 and the optical rotation ρ of the crystal.
θ = d · ρ (a)

  In general, the optical rotation ρ of quartz has a wavelength dependency (a property in which the value of optical rotation varies depending on the wavelength of the light used: optical rotation dispersion), and specifically, it tends to increase as the wavelength of the light used decreases. is there. According to the description on page 167 of “Applied Optics II”, the optical rotation power ρ of quartz with respect to light having a wavelength of 250.3 nm is 153.9 degrees / mm.

  In the present embodiment, in the polarization conversion unit 511, when linearly polarized light having a polarization direction in the Y direction is incident on the intersection region r1c between the diagonal line 511a and the center line 21c, the Y direction is +180 degrees around the Z axis (see FIG. 3 along a diagonal line 511a which is a straight line extending in the X direction through the intersecting region r1c so as to emit light in the Y direction linearly polarized light having a polarization direction in the Y direction, that is, a direction F1c rotated clockwise by 180 degrees. The thickness t1c is set. Further, in the polarization conversion unit 511, when light of Y-direction linearly polarized light is incident on the intersection region r1a between the boundary line on the polarization conversion unit 512 side and the center line 21c, the Y direction is rotated by +45 degrees around the Z axis. A thickness t1a along a straight line extending in the X direction through the intersecting region r1a is set so that linearly polarized light having a polarization direction is emitted to F1a.

  In addition, in the polarization conversion unit 511, when Y-direction linearly polarized light is incident on the intersection region r1b between the boundary line on the polarization conversion unit 514 side and the center line 21c, the Y direction is rotated by +315 degrees around the Z axis. A thickness t1b along a straight line extending in the X direction through the intersecting region r1b is set so that linearly polarized light having a polarization direction is emitted to F1b. In other words, in the polarization conversion unit 511, there are innumerable linear contour lines extending along the X direction (lines connecting point regions having the same thickness t as the dimension along the optical axis AX direction). The thickness along the diagonal line 511a which is a contour line passing through the region r1c is set to t1c, and the thickness along the contour line passing through the intersecting regions r1a and r1b is set to t1a and t1b.

  In the polarization conversion unit 512, when Y-direction linearly polarized light is incident on the intersection region r2c between the diagonal line 512a and the center line 21c, the polarization direction is changed in the direction F2c obtained by rotating the Y direction by +90 degrees around the Z axis, that is, in the X direction. The thickness t2c along the diagonal 512a that is a straight line extending in the Y direction through the intersecting region r2c is set so as to emit the X-direction linearly polarized light. Further, in the polarization conversion unit 512, when Y-direction linearly polarized light is incident on an intersection region r2a between the boundary line on the polarization conversion unit 513 side and the center line 21c, the Y direction is −45 degrees around the Z axis (FIG. 3). A thickness t2a is set along a straight line extending in the Y direction through the intersecting region r2a so that linearly polarized light having a polarization direction in the direction F2a rotated 45 degrees counterclockwise) is emitted. .

  Further, in the polarization conversion unit 512, when Y-direction linearly polarized light is incident on the intersection region r2b between the boundary line on the polarization conversion unit 511 side and the center line 21c, the Y direction is rotated by +225 degrees around the Z axis. A thickness t2b along a straight line extending in the Y direction through the intersecting region r2b is set so that linearly polarized light having a polarization direction is emitted to F2b. That is, in the polarization conversion unit 512, there are an infinite number of straight contour lines extending along the Y direction, the thickness along the diagonal 512a that is a contour line passing through the intersection region r2c is t2c, and the intersection region The thicknesses along the contour lines passing through r2a and r2b are set to be t2a and t2b.

  The polarization conversion unit 513 has the same configuration (the same shape and size) as the polarization conversion unit 511 facing each other across the optical axis AX, and is obtained by rotating the polarization conversion unit 511 by +180 degrees around the optical axis AX. Is arranged in. The polarization conversion unit 514 has the same configuration as the polarization conversion unit 512 facing each other across the optical axis AX, and is arranged in a posture obtained by rotating the polarization conversion unit 512 by +180 degrees around the optical axis AX. Therefore, in the polarization conversion unit 513, the thickness t3c along the diagonal line 513a is equal to the thickness t1c along the diagonal line 511a of the polarization conversion unit 511, and the Y direction linearly polarized light is crossed in the intersecting region r3c between the diagonal line 513a and the center line 21c. When light is incident, Y direction linearly polarized light having a polarization direction in the same direction F3c as the direction F1c, that is, the Y direction is emitted.

  In the polarization conversion unit 514, the thickness t4c along the diagonal line 514a is equal to the thickness t2c along the diagonal line 512a of the polarization conversion unit 512, and the Y-direction linearly polarized light is incident on the intersection region r4c between the diagonal line 514a and the center line 21c. When the light enters, X-direction linearly polarized light having a polarization direction in the same direction F4c as the direction F2c, that is, the X direction is emitted. Therefore, the polarization conversion units 511 to 514 convert at least the Y-direction linearly polarized light incident on each of the above-described intersection regions into circumferentially-polarized light having a polarization direction in a tangential direction of a circle centered on the optical axis AX. And inject.

  Thus, in this embodiment, the light subjected to the actions of the diffractive optical element 3 and the polarization conversion unit 5 is circumferentially polarized as shown in FIG. 6 on the rear focal plane of the micro fly's eye lens 8 or the illumination pupil in the vicinity thereof. An annular pupil intensity distribution 22 set in a state is formed. Hereinafter, of the four polarization conversion units 511 to 514 constituting the polarization conversion member 51, focusing on the optical rotation of the polarization conversion unit 511 having a diagonal line 511a extending in the X direction, the circumferential direction in the annular pupil intensity distribution 22 Verify the continuity of the polarization state.

  In the above description, of the incident region of light to the polarization conversion unit 511 (a quadrangular annular region defined by a pair of circles 21a and 21b indicated by broken lines in FIG. 3), the diagonal line 511a and the center line 21c Reference is made only to the optical rotation effect on the light incident on the intersection region r1c, the intersection region r1a between the boundary line on the polarization conversion unit 512 side and the center line 21c, and the intersection region r1b between the boundary line on the polarization conversion unit 514 side and the center line 21c. is doing. In order to verify the continuity of the circumferential polarization state in the annular pupil intensity distribution 22, it is necessary to understand the optical rotation effect on the incident light over the entire incident region of the light to the polarization converter 511.

  In the polarization conversion unit 511, as shown in FIG. 7, there is a diagonal line 511a that is a straight contour line extending in the X direction through the intersection region r1c, and is thick along the direction orthogonal to the diagonal line 511a, that is, along the Y direction. The length t changes linearly. More specifically, the thickness t of the polarization converter 511 decreases linearly in the + Y direction. Therefore, in the polarization conversion unit 511, there are an infinite number of equal-thickness lines extending linearly along the X direction, and a plurality of equal-thickness lines defined for each constant thickness change are equally spaced along the Y direction. Exists.

In FIG. 7, orthogonal coordinates (x, y) and polar coordinates (r, φ) with the optical axis AX as the origin are displayed. The x coordinate of the orthogonal coordinates (x, y) is set in parallel with the X coordinate of the orthogonal coordinates (X, Y, Z). In this case, the thickness distribution t (x, y) of the polarization converter 511 using orthogonal coordinates (x, y) and the thickness distribution t (r, φ) of the polarization converter 511 using polar coordinates (r, φ). ) Is represented by the following equations (1A) and (1B), respectively.
t (x, y) = C1 · y + C2 (1A)
t (r, φ) = C1 · rsinφ + C2 (1B)

  The coefficients C1 and C2 in the equations (1A) and (1B) indicate that the Y direction linearly polarized light is incident on the polarization conversion unit 511, and the light passing through the intersection region r1c has a polarization direction in the direction F1c, that is, the Y direction. It is set such that light that is linearly polarized light and that has passed through the intersecting regions r1a and r1b becomes linearly polarized light having a polarization direction in the directions F1a and F1b.

On the other hand, in order for the polarization converter 511 to realize an ideal circumferential polarization state, as shown in FIG. 8, it extends linearly along the radial direction (r direction) of a circle centered on the optical axis AX. There must be an infinite number of equal thickness lines, and there must be a plurality of equal thickness lines defined for each constant thickness change at equal intervals along the circumferential direction (φ direction) of the circle centered on the optical axis AX. There is. That is, the thickness distribution t (r, φ) of the polarization converter 511 necessary for realizing an ideal circumferential polarization state is expressed by the following equation (2).
t (r, φ) = C3 · φ + C4 (2)

  The coefficients C3 and C4 in Equation (2) indicate that when the Y-direction linearly polarized light is incident on the polarization conversion unit 511, the light that has passed through the intersection region r1c has the polarization direction in the direction F1c, that is, the Y-direction. The light is set so that the light passing through the intersecting regions r1a and r1b becomes linearly polarized light having a polarization direction in the directions F1a and F1b.

  Referring to the distribution of the isosceles line in FIG. 8, the thickness t varies linearly along the circumferential direction of the circle centered on the optical axis AX over the entire incident surface of the polarization converter 511, and The thickness t is constant along the radial direction of the circle. On the other hand, referring to the distribution of the iso-thick lines in FIG. 7, the thickness t linearly changes along the circumferential direction of the circle centered on the optical axis AX on the entire incident surface of the polarization converter 511. In addition, the thickness t is not constant along the radial direction of the circle except for the diagonal line 511a. However, in the light incident area to the polarization converter 511, the change in the thickness t along the circumferential direction is almost linear, and the thickness t is almost constant along the radial direction. In other words, in the region relatively close to the optical axis AX in the polarization conversion unit 511, the linearity of the change in the thickness t along the circumferential direction is relatively largely lost, and the thickness t along the radial direction is reduced. Change is relatively large.

  Therefore, in the polarization conversion unit 511 according to the present embodiment, an ideal circumferential polarization state is realized with respect to the incident light to the diagonal line 511a extending in the X direction through the intersecting region r1c and the intersecting regions r1a and r1b. It is possible to exert the optical rotation required for In addition, among the light incident areas to the polarization converter 511, the incident light to areas other than the diagonal line 511a and the intersecting areas r1a and r1b can have an effect very close to the ideal optical rotation. . Incidentally, in the split region of the polarization conversion element described in Patent Document 1, the thickness is constant over the entire incident surface, which is completely different from the ideal isoline distribution as shown in FIG.

  Thus, an annular light intensity distribution is formed in the illumination pupil immediately after the polarization conversion unit 5 in the circumferential polarization state with high continuity. As a result, an annular light intensity distribution 22 is formed in the circumferential polarization state with high continuity also in the illumination pupil immediately after the micro fly's eye lens 8. In the circumferential polarization state, the light beam passing through the annular light intensity distribution 22 is in a linear polarization state having a polarization direction in a tangential direction of a circle with the optical axis AX as the center. Furthermore, the position of another illumination pupil optically conjugate with the illumination pupil immediately after the micro fly's eye lens 8, that is, the pupil position of the imaging optical system 12 and the pupil position of the projection optical system PL (the aperture stop AS is disposed). The annular light intensity distribution is also formed in a substantially continuous circumferential polarization state corresponding to the annular light intensity distribution 22.

  In general, in the circumferential polarization illumination based on the annular intensity distribution in the circumferential polarization state or a multipolar (bipolar, quadrupole, octupole, etc.) pupil intensity distribution, the wafer W as the final irradiated surface is formed. The irradiated light becomes a polarization state mainly composed of s-polarized light. Here, the s-polarized light is linearly polarized light having a polarization direction in a direction perpendicular to the incident surface (polarized light having an electric vector oscillating in a direction perpendicular to the incident surface). The incident surface is defined as a surface including the normal of the boundary surface at that point and the incident direction of light when the light reaches the boundary surface of the medium (irradiated surface: the surface of the wafer W). As a result, in the circumferential polarization illumination, the optical performance (such as depth of focus) of the projection optical system can be improved, and a mask pattern image with high contrast can be obtained on the wafer (photosensitive substrate).

  As described above, the four polarization conversion units 511 to 514 constituting the polarization conversion member 51 have a planar incident surface and a planar exit surface that is not parallel to the incident surface, and thus have a simple surface shape. Is an optical member. Moreover, the pair of polarization conversion units 511 and 513 and 512 and 514 facing each other with the optical axis AX interposed therebetween have the same configuration. The polarization conversion unit 5 corresponds to the number of polarization conversion units on the illumination pupil immediately after the micro fly's eye lens 8 by the cooperative optical rotation of the four polarization conversion units 511 to 514 arranged in parallel. The light intensity distribution 22 in the circumferentially polarized state is much more continuous than the quadrant type.

  That is, the polarization conversion unit 5 of the present embodiment has a configuration that is relatively easy to manufacture, and is arranged in the optical path of the illumination optical system (1-12) and has high continuity in the circumferential polarization state pupil intensity distribution. Can be realized. In the illumination optical system (1 to 12) of the present embodiment, the pattern of the mask M with light of a desired circumferential polarization state using the polarization conversion unit 5 that realizes a highly continuous pupil intensity distribution of the circumferential polarization state. The surface (irradiated surface) can be illuminated. In the exposure apparatus (1 to WS) of this embodiment, the illumination optical system (1 to 12) that illuminates the pattern surface of the mask M with light in a desired circumferentially polarized state is used to change the pattern of the mask M to be transferred. The fine pattern can be accurately transferred to the wafer W by exerting the effect of circumferentially polarized light satisfactorily under appropriate illumination conditions realized according to the characteristics.

  In the above-described embodiment, Y-direction linearly polarized light is incident on the polarization conversion unit 5. However, if X-direction linearly polarized light having a polarization direction in the X direction is incident on the polarization conversion unit 5, As shown in FIG. 9, an annular light intensity distribution 23 is formed on the illumination pupil immediately after the conversion unit 5 and thus the illumination pupil immediately after the micro fly's eye lens 8 in a radially continuous polarization state. . As a result, an annular light intensity distribution is formed in a substantially continuous radial polarization state corresponding to the annular light intensity distribution 23 at the pupil position of the imaging optical system 12 and the pupil position of the projection optical system PL. Is done. In this case, the polarization converters 511 to 514 convert the X-direction linearly polarized light into radial-polarized light having a polarization direction in the radial direction of a circle centered on the optical axis AX, and emit the light.

  In general, in radial polarization illumination based on an annular or multipolar pupil intensity distribution in the radial polarization state, the light irradiated on the wafer W as the final irradiated surface is a polarization state whose main component is p-polarization. become. Here, p-polarized light is linearly polarized light having a polarization direction in a direction parallel to the incident surface defined as described above (polarized light whose electric vector is oscillating in a direction parallel to the incident surface). is there. As a result, in the radial polarization illumination, a good mask pattern image can be obtained on the wafer (photosensitive substrate) while suppressing the reflectance of light in the resist applied to the wafer W to be small.

  Moreover, in the above-mentioned embodiment, this invention is demonstrated based on the polarization conversion unit 5 which has a specific structure shown to FIG. 3 and FIG. However, the present invention is not limited to this, and various configurations are possible for the configuration of the polarization conversion unit. Specifically, the arrangement position of the polarization conversion unit, the arrangement position of the polarization conversion member, the arrangement position of the correction member, the positional relationship between the polarization conversion member and the correction member, the presence or absence of the correction member, the number of polarization conversion units, the number of polarization conversion units Various forms are possible for the arrangement, the material of the polarization conversion unit, the configuration of the polarization conversion unit (difference in outer shape, surface shape (thickness distribution, etc.), and the like.

  For example, in the above-described embodiment, the polarization conversion unit 5 is disposed at or near the pupil position of the afocal lens 4. However, the present invention is not limited to this, and the polarization conversion unit 5 can be arranged at the position of another illumination pupil of the illumination optical system (1 to 12) or a position in the vicinity thereof. Specifically, the polarization conversion unit 5 can be arranged near the entrance surface of the micro fly's eye lens 8, near the exit surface of the micro fly's eye lens 8, the pupil position of the imaging optical system 12, or the vicinity thereof. .

  In the above-described embodiment, the correction member 52 is disposed adjacent to the exit side of the polarization conversion member 51. However, the present invention is not limited to this, and a correction member may be disposed adjacent to the incident side of the polarization conversion member. Further, the correction member may be disposed on the exit side or the incident side of the polarization conversion member via another optical member, or the disposition of the correction member may be omitted.

  In the above-described embodiment, the four polarization conversion units 511 to 514 have the same square outer shape, and are formed in a quadrant shape obtained by equally dividing a circle centered on the optical axis AX into four. Arranged to correspond to the area. However, the present invention is not limited to this, and as shown in the modified example of FIG. 10, a circular outer shape is obtained by using four polarization conversion units 531, 532, 533, and 534 having the same quadrant outer shape. The polarization conversion member 53 can also be configured.

  The polarization conversion units 531 to 534 are obtained by changing the outer shape of the polarization conversion units 511 to 514 from a square to a quarter circle. The polarization conversion units 531 to 534 are arranged so as to have the same thickness along straight lines 531a, 532a, 533a, and 534a extending in the radial direction of a circle centered on the optical axis AX. Referring to FIG. 10, for example, it can be seen that the polarization conversion member can be configured by a plurality of polarization conversion units arranged so as to correspond to a region obtained by dividing a circle centered on the optical axis AX into an arbitrary number.

  In the above-described embodiment, the polarization conversion units 511 to 514 are formed of quartz. However, the present invention is not limited to this, and the polarization conversion section can be formed using another suitable optical material having optical rotation.

  In the above description, the operational effects of the present invention are described by taking, as an example, modified illumination in which an annular pupil intensity distribution is formed on the illumination pupil, that is, annular illumination. However, the present invention is similarly applied to, for example, multipolar illumination in which a multipolar pupil intensity distribution is formed without being limited to annular illumination, and the same operational effects can be obtained. Is clear.

  Then, the polarization conversion unit 5 may be retracted from the illumination optical path in accordance with a change in the shape of the pupil intensity distribution (and thus a change in illumination conditions). Further, the polarization conversion unit 5 can be replaced with another polarization conversion unit having different characteristics in accordance with a change in the shape or size of the pupil intensity distribution. That is, a plurality of polarization conversion units are provided, and the coefficients C1 and C2 in the equations (1A) and (1B) are determined according to the annular ratio, outer diameter, inner diameter, etc. of the annular or multipolar pupil intensity distribution. A polarization conversion unit including a polarization conversion member may be selectively disposed in the illumination optical path.

  In the above-described embodiment, the micro fly's eye lens 8 is used as the optical integrator, but instead, an internal reflection type optical integrator (typically a rod type integrator) may be used. In this case, the condensing lens is arranged on the rear side of the zoom lens 7 so that the front focal position thereof coincides with the rear focal position of the zoom lens 7, and the incident end is located at or near the rear focal position of the condensing lens. Position the rod-type integrator so that is positioned. At this time, the exit end of the rod integrator is the position of the illumination field stop 11. When using a rod type integrator, a position optically conjugate with the position of the aperture stop of the projection optical system PL in the field stop imaging optical system 12 downstream of the rod type integrator can be called an illumination pupil plane. In addition, since a virtual image of the secondary light source of the illumination pupil plane is formed at the position of the entrance surface of the rod integrator, this position and a position optically conjugate with this position are also called the illumination pupil plane. Can do.

  In the above-described embodiment, a variable pattern forming apparatus that forms a predetermined pattern based on predetermined electronic data can be used instead of a mask. As the variable pattern forming apparatus, for example, a spatial light modulation element including a plurality of reflection elements driven based on predetermined electronic data can be used. An exposure apparatus using a spatial light modulator is disclosed in, for example, Japanese Patent Application Laid-Open No. 2004-304135, International Patent Publication No. 2006/080285, and US Patent Publication No. 2007/0296936 corresponding thereto. In addition to the non-light-emitting reflective spatial light modulator as described above, a transmissive spatial light modulator may be used, or a self-luminous image display element may be used.

  The exposure apparatus of the above-described embodiment is manufactured by assembling various subsystems including the respective constituent elements recited in the claims of the present application so as to maintain predetermined mechanical accuracy, electrical accuracy, and optical accuracy. Is done. In order to ensure these various accuracies, before and after assembly, various optical systems are adjusted to achieve optical accuracy, various mechanical systems are adjusted to achieve mechanical accuracy, and various electrical systems are Adjustments are made to achieve electrical accuracy. The assembly process from the various subsystems to the exposure apparatus includes mechanical connection, electrical circuit wiring connection, pneumatic circuit piping connection and the like between the various subsystems. Needless to say, there is an assembly process for each subsystem before the assembly process from the various subsystems to the exposure apparatus. When the assembly process of the various subsystems to the exposure apparatus is completed, comprehensive adjustment is performed to ensure various accuracies as the entire exposure apparatus. The exposure apparatus may be manufactured in a clean room where the temperature, cleanliness, etc. are controlled.

  Next, a device manufacturing method using the exposure apparatus according to the above-described embodiment will be described. FIG. 11 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 11, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a semiconductor device substrate (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the exposure apparatus of the above-described embodiment, the pattern formed on the mask (reticle) M is transferred to each shot area on the wafer W (step S44: exposure process), and the transfer of the wafer W after the transfer is completed. Development, that is, development of the photoresist to which the pattern has been transferred is performed (step S46: development process). Thereafter, using the resist pattern generated on the surface of the wafer W in step S46 as a mask, processing such as etching is performed on the surface of the wafer W (step S48: processing step).

  Here, the resist pattern is a photoresist layer in which unevenness having a shape corresponding to the pattern transferred by the exposure apparatus of the above-described embodiment is generated, and the recess penetrates the photoresist layer. is there. In step S48, the surface of the wafer W is processed through this resist pattern. The processing performed in step S48 includes, for example, at least one of etching of the surface of the wafer W or film formation of a metal film or the like. In step S44, the exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as a photosensitive substrate.

  FIG. 12 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 12, in the liquid crystal device manufacturing process, a pattern forming process (step S50), a color filter forming process (step S52), a cell assembling process (step S54), and a module assembling process (step S56) are sequentially performed. In the pattern forming process of step S50, a predetermined pattern such as a circuit pattern and an electrode pattern is formed on the glass substrate coated with a photoresist as the plate P using the exposure apparatus of the above-described embodiment. In this pattern formation process, an exposure process for transferring the pattern to the photoresist layer using the exposure apparatus of the above-described embodiment and development of the plate P to which the pattern is transferred, that is, development of the photoresist layer on the glass substrate are performed. And a developing step for generating a photoresist layer having a shape corresponding to the pattern, and a processing step for processing the surface of the glass substrate through the developed photoresist layer.

  In the color filter forming step of step S52, a large number of sets of three dots corresponding to R (Red), G (Green), and B (Blue) are arranged in a matrix or three R, G, and B A color filter is formed by arranging a plurality of stripe filter sets in the horizontal scanning direction. In the cell assembly process in step S54, a liquid crystal panel (liquid crystal cell) is assembled using the glass substrate on which the predetermined pattern is formed in step S50 and the color filter formed in step S52. Specifically, for example, a liquid crystal panel is formed by injecting liquid crystal between a glass substrate and a color filter. In the module assembling process in step S56, various components such as an electric circuit and a backlight for performing the display operation of the liquid crystal panel are attached to the liquid crystal panel assembled in step S54.

  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, etc.), micromachine, thin film magnetic head, and 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, ArF excimer laser light (wavelength: 193 nm) or KrF excimer laser light (wavelength: 248 nm) is used as the exposure light. However, the present invention is not limited to this, and other appropriate laser light sources are used. For example, the present invention can also be applied to an F ₂ laser light source that supplies laser light having a wavelength of 157 nm.

  In the above-described embodiment, a so-called immersion method is applied in which the optical path between the projection optical system and the photosensitive substrate is filled with a medium (typically liquid) having a refractive index larger than 1.1. You may do it. In this case, as a method for filling the liquid in the optical path between the projection optical system and the photosensitive substrate, a method for locally filling the liquid as disclosed in International Publication No. WO 99/49504, A method of moving a stage holding a substrate to be exposed as disclosed in Japanese Patent Application Laid-Open No. 6-124873 in a liquid bath, or a predetermined depth on a stage as disclosed in Japanese Patent Application Laid-Open No. 10-303114. A technique of forming a liquid tank and holding the substrate in the liquid tank can be employed. Here, the teachings of International Publication No. WO99 / 49504, JP-A-6-124873 and JP-A-10-303114 are incorporated by reference.

  Further, in the above-described embodiment, in place of or in addition to the diffractive optical element 3, for example, a large number of minute element mirrors arranged in an array and whose tilt angle and tilt direction are individually driven and controlled. A spatial light modulator that converts the cross section of the light beam into a desired shape or a desired size by dividing the incident light beam into minute units for each reflecting surface and deflecting the incident light beam may be used. An illumination optical system using such a spatial light modulator is disclosed in, for example, Japanese Patent Application Laid-Open No. 2002-353105.

  In the above-described embodiment, the present invention is applied to the illumination optical system that illuminates the mask (or wafer) in the exposure apparatus. However, the present invention is not limited to this, and an object other than the mask (or wafer) is used. The present invention can also be applied to a general illumination optical system that illuminates the irradiation surface.

2 Polarization state switching unit 3 Diffractive optical element 4 Afocal lens 5 Polarization conversion unit 51 Polarization conversion member 52 Correction member 6 Conical axicon system 7 Zoom lens 8 Micro fly's eye lens (optical integrator)
10 Condenser optical system 11 Mask blind 12 Imaging optical system LS Light source M Mask MS Mask stage PL Projection optical system W Wafer WS Wafer stage

Claims (19)

In a polarization conversion unit including a polarization conversion member that converts incident light into light having a predetermined polarization state and emits the light,
The polarization conversion member has a plurality of polarization conversion units formed of an optical rotatory optical material and arranged in parallel along a plane crossing the optical axis,
The plurality of polarization conversion units each have a planar incident surface and a planar exit surface that is not parallel to the incident surface. 2. The polarization conversion according to claim 1, wherein the plurality of polarization conversion units are arranged so as to have the same thickness along a straight line extending in a radial direction of a circle centered on the optical axis. unit. The said polarization conversion member has the said even number of polarization conversion parts arrange | positioned so as to correspond to the area | region obtained by dividing | segmenting the said circle | round | yen into four or more even number. Polarization conversion unit. 4. The polarization conversion unit according to claim 3, wherein, of the even number of polarization conversion units, a pair of polarization conversion units facing each other across the optical axis have the same configuration. 5. The polarization conversion unit according to claim 3, wherein one of an incident surface and an exit surface of the even number of polarization conversion units is orthogonal to the optical axis. 6. The polarization conversion unit according to claim 5, wherein the even number of polarization conversion units are arranged so that the one surface coincides with one plane orthogonal to the optical axis. The polarization conversion unit according to any one of claims 1 to 6, wherein the polarization conversion member is made of quartz, and a crystal optical axis of the quartz is parallel to the optical axis. 8. The correction member according to claim 1, further comprising a correction member that is disposed on an incident side or an emission side of the polarization conversion member and compensates for a light deflection action of the polarization conversion member. Polarization conversion unit. The polarization conversion unit according to claim 8, wherein the polarization conversion member and the correction member are disposed adjacent to each other. 10. The optical path of an illumination optical system that illuminates a surface to be irradiated with light from a light source, wherein the illumination optical system is disposed at or near an illumination pupil of the illumination optical system. The polarization conversion unit described. The plurality of polarization conversion units are configured to polarize linearly polarized incident light having a polarization direction in a predetermined direction in a circumferential direction polarization having a polarization direction in a tangential direction of a circle around the optical axis or in a radial direction of the circle. 11. The polarization conversion unit according to claim 1, wherein the polarization conversion unit emits light after being converted into radially polarized light having a direction. In the illumination optical system that illuminates the illuminated surface with light from the light source,
An illumination optical system comprising the polarization conversion unit according to any one of claims 1 to 11 disposed in an optical path between the light source and the irradiated surface. The illumination optical system according to claim 12, wherein the polarization conversion unit is disposed at or near an illumination pupil of the illumination optical system. The projection pupil is used in combination with a projection optical system that forms a surface optically conjugate with the irradiated surface, and the illumination pupil is at a position optically conjugate with an aperture stop of the projection optical system. 14. The illumination optical system according to 13. 15. The illumination optical system according to any one of claims 12 to 14, wherein the polarization conversion unit is detachable with respect to the illumination optical path. In the illumination optical system that illuminates the illuminated surface with light from the light source,
A plurality of polarization conversion units according to any one of claims 1 to 11, wherein the plurality of polarization conversion units are selectively disposed in an illumination optical path between the light source and the irradiated surface. An illumination optical system characterized by that. An exposure apparatus comprising the illumination optical system according to any one of claims 12 to 16 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. The exposure apparatus according to claim 17, further comprising a projection optical system that forms an image of the predetermined pattern on the photosensitive substrate. Using the exposure apparatus according to claim 17 or 18, exposing 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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