JP2009071011A - Optical integrator, illumination optical system, exposure apparatus and device-manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical integrator, capable of uniforming an illumination distribution on an irradiated surface by suppressing the influence due to the difference in surface shape of each refractive surface, when it is applied to, for example, an illumination optical system that illuminates the surface to be illuminated. <P>SOLUTION: The wavefront separating type optical integrator (9) is provided with a plurality of refractive surfaces (9ab, 9bb) disposed one- or two-dimensionally, and at least one diffractive optical surface (9d), formed on a region (9c) between the plurality of refractive surfaces (9bb) adjacent to each other in the plurality of refractive surfaces. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical integrator, an illumination optical system, an exposure apparatus, and a device manufacturing method. More specifically, the present invention relates to an optical integrator suitable for an illumination optical system of an exposure apparatus used when manufacturing a device such as a semiconductor element, an imaging element, a liquid crystal display element, and a thin film magnetic head in a lithography process. is there.

  In a typical exposure apparatus of this type, a light beam emitted from a light source is incident on a fly-eye lens as a wavefront division type optical integrator, and a secondary light source composed of a number of light sources at or near its rear focal plane. Form. The light flux from the secondary light source illuminates the mask on which a predetermined pattern is formed via the condenser lens 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 mask pattern is highly integrated, and it is indispensable to obtain a uniform illuminance distribution on the wafer in order to accurately transfer the fine pattern onto the wafer. Conventionally, in order to improve the illuminance uniformity on a wafer, a configuration using a cylindrical micro fly's eye lens composed of a pair of fly's eye members formed with a cylindrical lens group as an optical integrator in an illumination optical system for illuminating a mask. It has been proposed (see Patent Document 1).

JP 2004-56103 A

  In the cylindrical micro fly's eye lens disclosed in Patent Document 1, a plurality of minute refractive surfaces arranged along one direction are formed on a parallel flat optical member by a polishing or etching technique. It is difficult to accurately manufacture each refracting surface in a desired surface shape, and the illuminance uniformity on the wafer may be reduced due to surface shape errors of each refracting surface. In addition, it is difficult to accurately produce a boundary region between two refracting surfaces adjacent to each other to have a desired surface shape, which is caused by a surface shape error of the boundary region (that is, due to light passing through the boundary region). ) Irradiance uniformity on the wafer may be reduced.

  The present invention has been made in view of the above-described problems. For example, when applied to an illumination optical system that illuminates a surface to be irradiated, the influence of the surface shape error of each refracting surface is suppressed to a small level. An object of the present invention is to provide an optical integrator capable of uniforming the illuminance distribution of the light.

  Another object of the present invention is to provide an illumination optical system that can illuminate an illuminated surface under a desired illumination condition using an optical integrator that can uniformize the illuminance distribution on the illuminated surface. To do.

  The present invention also provides an exposure apparatus and a device manufacturing method capable of performing good exposure under a desired illumination condition using an illumination optical system capable of illuminating the irradiated surface under the desired illumination condition. The purpose is to do.

In order to solve the above problems, in the first embodiment of the present invention, in the wavefront division type optical integrator,
A plurality of refractive surfaces arranged one-dimensionally or two-dimensionally;
An optical integrator comprising: at least one diffractive optical surface formed in a region between a plurality of refracting surfaces adjacent to each other among the plurality of refracting surfaces.

In the second embodiment of the present invention, in the illumination optical system that illuminates the illuminated surface based on the light from the light source,
Provided is an illumination optical system comprising a first form of optical integrator disposed in an optical path of the illumination optical system.

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

In the fourth embodiment of the present invention, using the exposure apparatus of the third embodiment, an exposure step of exposing the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate to which the pattern has been transferred, and forming a mask layer having a shape corresponding to the pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

  In the optical integrator of the present invention, at least one diffractive optical surface is formed in a region between a plurality of adjacent refracting surfaces among a plurality of refracting surfaces arranged one-dimensionally or two-dimensionally. For example, when the optical integrator of the present invention is incorporated in an illumination optical system that illuminates the illuminated surface, the illuminance unevenness that occurs on the illuminated surface due to surface shape errors of each refractive surface is corrected (adjusted). By designing the diffractive optical surface, the illuminance distribution on the irradiated surface can be made uniform.

  In other words, in the optical integrator of the present invention, for example, when applied to an illumination optical system that illuminates the illuminated surface, the illuminance distribution on the illuminated surface is made uniform while minimizing the influence of surface shape errors of each refractive surface. can do. Therefore, the illumination optical system of the present invention can illuminate the illuminated surface under desired illumination conditions using an optical integrator that can make the illuminance distribution uniform on the illuminated surface. In the exposure apparatus of the present invention, it is possible to perform good exposure under desired illumination conditions using an illumination optical system that can illuminate the irradiated surface under the desired illumination conditions, and thus a good device. Can be manufactured.

  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 wafer W, which is a photosensitive substrate, the Y axis in the direction parallel to the plane of FIG. 1 in the surface of the wafer W, and the surface of the wafer W in FIG. The X axis is set in the direction perpendicular to the paper surface. Referring to FIG. 1, the exposure apparatus of this embodiment includes a light source 1 for supplying exposure light (illumination light). As the light source 1, for example, an ArF excimer laser light source that supplies light with a wavelength of 193 nm, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, or the like can be used.

  Light emitted from the light source 1 is converted into a light beam having a required cross-sectional shape by the shaping optical system 2 and enters the afocal lens 5 via the polarization state switching unit 3 and the diffractive optical element 4 for annular illumination. . The polarization state switching unit 3 includes, in order from the light source side, a quarter-wave plate 3 a 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 3b that changes the polarization direction of linearly polarized light that is incident on the optical axis AX so that the crystal optical axis is rotatable, and a depolarizer that can be inserted into and removed from the illumination optical path (depolarizing element). 3c.

  The polarization state switching unit 3 has a function of converting light from the light source 1 into linearly polarized light having a desired polarization direction and making it incident on the diffractive optical element 4 with the depolarizer 3c retracted from the illumination optical path. In the state where the depolarizer 3c is set in the illumination optical path, the light from the light source 1 is converted into substantially non-polarized light and incident on the diffractive optical element 4. The afocal lens 5 is set so that the front focal position thereof and the position of the diffractive optical element 4 substantially coincide with each other, and the rear focal position thereof substantially coincides with the position of the predetermined surface 6 indicated by a broken line in the drawing. System (non-focal optical system).

  The diffractive optical element 4 is formed by forming a step having a pitch of about the wavelength of exposure light (illumination light) on the substrate, and has an action of diffracting an incident beam to a desired angle. Specifically, the diffractive optical element 4 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 flux having a rectangular cross section is incident. Have Therefore, the substantially parallel light beam incident on the diffractive optical element 4 is formed from the afocal lens 5 with a ring-shaped angular distribution after forming a ring-shaped light intensity distribution on the pupil plane of the afocal lens 5.

  A conical axicon system 7 is disposed at or near the pupil position in the optical path between the front lens group 5a and the rear lens group 5b of the afocal lens 5. The configuration and operation of the conical axicon system 7 will be described later. The light beam that has passed through the afocal lens 5 passes through a zoom lens 8 for varying a σ value (σ value = mask-side numerical aperture of the illumination optical apparatus / mask-side numerical aperture of the projection optical system), and a cylindrical micro as an optical integrator. The light enters the fly eye lens 9.

  As shown in FIG. 2, the cylindrical micro fly's eye lens 9 includes a first fly eye member 9a disposed on the light source side and a second fly eye member 9b disposed on the mask side. On the light source side surface of the first fly eye member 9a and the light source side surface of the second fly eye member 9b, a plurality of cylindrical surface refracting surfaces (cylindrical lens groups) 9aa and 9ba arranged side by side in the X direction. Are formed at a pitch px. On the mask side surface of the first fly eye member 9a and the mask side surface of the second fly eye member 9b, a plurality of cylindrical refractive surfaces (cylindrical lens groups) 9ab and 9bb arranged side by side in the Z direction. Are formed at a pitch pz (pz> px).

  Focusing on the refraction action in the X direction of the cylindrical micro fly's eye lens 9 (that is, the refraction action in the XY plane), a group of parallel light beams incident along the optical axis AX are formed on the light source side of the first fly eye member 9a. Corresponding in the group of refracting surfaces 9ba formed on the light source side of the second fly's eye member 9b after being wavefront divided along the X direction by the refracting surface 9aa with a pitch px and receiving the condensing action on the refracting surface. The light is focused on the refracting surface to be focused on the rear focal plane of the cylindrical micro fly's eye lens 9.

  Focusing on the refractive action in the Z direction of the cylindrical micro fly's eye lens 9 (ie, the refractive action in the YZ plane), a group of parallel light beams incident along the optical axis AX are formed on the mask side of the first fly's eye member 9a. Corresponding in the group of refracting surfaces 9bb formed on the mask side of the second fly's eye member 9b after the wavefront is divided by the refracting surface 9ab with the pitch pz along the Z direction The light is focused on the refracting surface to be focused on the rear focal plane of the cylindrical micro fly's eye lens 9.

  As described above, the cylindrical micro fly's eye lens 9 is composed of the first fly eye member 9a and the second fly eye member 9b in which the cylindrical lens groups are arranged on both side surfaces, and the size of px is set in the X direction. It has the same optical function as a micro fly's eye lens in which a large number of rectangular micro-refractive surfaces (wavefront splitting elements) having a size of pz in the Z direction are integrally formed vertically and horizontally. In the cylindrical micro fly's eye lens 9, a change in distortion due to variations in the surface shape of the micro-refractive surface is suppressed, and for example, manufacturing errors of a large number of micro-refractive surfaces formed integrally by etching process give the illuminance distribution. The influence can be kept small.

  The position of the predetermined surface 6 is disposed at or near the front focal position of the zoom lens 8, and the incident surface of the cylindrical micro fly's eye lens 9 is disposed at or near the rear focal position of the zoom lens 8. In other words, the zoom lens 8 arranges the predetermined surface 6 and the incident surface of the cylindrical micro fly's eye lens 9 substantially in a Fourier transform relationship, and consequently the pupil surface of the afocal lens 5 and the cylindrical micro fly's eye lens 9. The incident surface is optically substantially conjugate.

  Accordingly, on the incident surface of the cylindrical micro fly's eye lens 9, for example, an annular illumination field centered on the optical axis AX is formed in the same manner as the pupil surface of the afocal lens 5. The entire shape of the annular illumination field changes in a similar manner depending on the focal length of the zoom lens 8. A rectangular micro-refractive surface as a wavefront division unit element in the cylindrical micro fly's eye lens 9 has a rectangular shape similar to the shape of the illumination field to be formed on the mask M (and thus the shape of the exposure region to be formed on the wafer W). Shape.

  The light beam incident on the cylindrical micro fly's eye lens 9 is two-dimensionally divided, and the light intensity substantially the same as the illumination field formed by the incident light beam is formed at the rear focal plane or in the vicinity thereof (and thus the position of the illumination pupil). A secondary light source having a distribution, that is, a secondary light source composed of a substantial surface light source having an annular shape centering on the optical axis AX is formed. A light beam from a secondary light source formed on the rear focal plane of the cylindrical micro fly's eye lens 9 or in the vicinity thereof enters an aperture stop 10 disposed in the vicinity thereof.

  The aperture stop 10 has an annular opening (light transmission part) corresponding to an annular secondary light source formed at or near the rear focal plane of the cylindrical micro fly's eye lens 9. The aperture stop 10 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 aperture stop 10 is disposed at a position optically substantially conjugate with an entrance pupil plane of the projection optical system PL described later, and defines a range that contributes to illumination of the secondary light source. The installation of the aperture stop 10 can be omitted.

  The light limited by the aperture stop 10 illuminates the mask blind 12 in a superimposed manner via the condenser optical system 11. Thus, the mask blind 12 as the illumination field stop is formed with a rectangular illumination field corresponding to the shape and focal length of the rectangular micro-refractive surface that is the wavefront dividing element of the cylindrical micro fly's eye lens 9. The light beam that has passed through the rectangular opening (light transmitting portion) of the mask blind 12 receives the light condensing action of the imaging optical system 13 and then illuminates the mask M on which a predetermined pattern is formed in a superimposed manner. That is, the imaging optical system 13 forms an image of the rectangular opening of the mask blind 12 on the mask M.

  A pattern to be transferred is formed on the mask M held on the mask stage MS, and a rectangular shape having a long side along the Y direction and a short side along the X direction in the entire pattern region ( The pattern area of the slit shape is illuminated. The light beam transmitted through the pattern area 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. That is, a rectangular stationary image having a long side along the Y direction and a short side along the X direction on the wafer W so as to optically correspond to the rectangular illumination area on the mask M. A pattern image is formed in the exposure area (effective exposure area).

  Thus, according to the so-called step-and-scan method, the mask stage MS and the wafer stage WS along the X direction (scanning direction) in the plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, As a result, by moving (scanning) the mask M and the wafer W synchronously, the wafer W has a width equal to the dimension in the Y direction of the static exposure region and corresponds to the scanning amount (movement amount) of the wafer W. A mask pattern is scanned and exposed to a shot area (exposure area) having a length.

  In place of the diffractive optical element 4 for annular illumination, a plurality of diffractive optical elements (not shown) for multipole illumination (dipole illumination, quadrupole 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. It has the function to do. Therefore, the light flux that has passed through the diffractive optical element for multipole illumination is incident on the incident surface of the cylindrical micro fly's eye lens 9, for example, a multipolar illumination field comprising a plurality of circular illumination fields centered on the optical axis AX. Form. As a result, the same multipolar secondary light source as the illumination field formed on the incident surface is formed on the rear focal plane of the cylindrical micro fly's eye lens 9 or in the vicinity thereof.

  Moreover, instead of the diffractive optical element 4 for annular illumination, 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 cylindrical micro fly's eye lens 9. 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 cylindrical micro fly's eye lens 9. Also, instead of the diffractive optical element 4 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 4, for example, a known turret method or slide method can be used.

  The conical axicon system 7 includes, in order from the light source side, a first prism member 7a 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 the second prism member 7b having the refractive surface thereof directed. The concave conical refracting surface of the first prism member 7a and the convex conical refracting surface of the second prism member 7b are complementarily formed so as to be in contact with each other. Further, at least one of the first prism member 7a and the second prism member 7b is configured to be movable along the optical axis AX, and the concave conical refracting surface of the first prism member 7a and the second prism member 7b. The distance from the convex conical refracting surface is variable. Hereinafter, the operation of the conical axicon system 7 and the operation of the zoom lens 8 will be described by focusing on the annular or quadrupolar secondary light source.

  In a state where the concave conical refracting surface of the first prism member 7a and the convex conical refracting surface of the second prism member 7b are in contact with each other, the conical axicon system 7 functions as a parallel flat plate, and is formed in an annular shape. Alternatively, there is no influence on the quadrupolar secondary light source. When the concave conical refracting surface of the first prism member 7a is separated from the convex conical refracting surface of the second prism member 7b, the width of the annular or quadrupolar secondary light source (outside of the annular secondary light source) 1/2 of the difference between the diameter and the inner diameter; 1/2 of the difference between the diameter of the circle circumscribed by the quadrupolar secondary light source (outer diameter) and the diameter of the inscribed circle (inner diameter)) The outer diameter (inner diameter) of the annular or quadrupolar secondary light source changes. That is, the annular ratio (inner diameter / outer diameter) and size (outer diameter) of the annular or quadrupolar secondary light source change.

  The zoom lens 8 has a function of similarly enlarging or reducing the entire shape of the annular or quadrupolar secondary light source. For example, by enlarging the focal length of the zoom lens 8 from a minimum value to a predetermined value, the entire shape of the annular or quadrupolar secondary light source is similarly enlarged. In other words, due to the action of the zoom lens 8, both the width and size (outer diameter) change without changing the annular ratio of the annular or quadrupolar secondary light source. In this way, the annular ratio and size (outer diameter) of the annular or quadrupolar secondary light source can be controlled by the action of the conical axicon system 7 and the zoom lens 8.

  Generally, in the cylindrical micro fly's eye lens, as shown in the left diagram of FIG. 3, a plurality of (only two are shown in FIG. 3) minute cylindrical surface-shaped refractive surfaces to be adjacently arranged along one direction. 31 is formed in a parallel plane optical member by, for example, a polishing or etching technique. In this case, it is difficult to accurately manufacture each refractive surface 31 in a desired surface shape. In addition, it is difficult to accurately manufacture a boundary region (shown by a dashed small circle) 32 between two adjacent refracting surfaces 31 into a desired surface shape.

  In particular, as schematically shown in the right diagram in FIG. 3, the boundary region 32a between the two refracting surfaces 31a that are actually formed tends to have a surface shape that is significantly different from the desired surface shape in design. As a result, the illuminance uniformity on the wafer W may be reduced due to the surface shape error of each refractive surface 31a. Further, the illuminance uniformity on the wafer W may be reduced due to light that has passed through the boundary region 32a between two adjacent refractive surfaces 31a, that is, due to a surface shape error of the boundary region 32a.

  Strictly speaking, the surface shape errors of the refracting surface 31a and the boundary region 32a are different for each manufactured cylindrical micro fly's eye lens, that is, for each individual. However, in the influence of the surface shape error of the refracting surface 31a and the boundary region 32a, the influence of the surface shape error that is commonly generated in many cylindrical micro fly's eye lenses depending on the manufacturing method or the like occurs for each individual. It is more dominant than the effect of surface shape error. In other words, due to surface shape errors of the refractive surface 31a and the boundary region 32a, illuminance unevenness common to a large number of cylindrical micro fly's eye lenses manufactured by the same manufacturing method tends to occur on the wafer W.

  In the exposure apparatus, in order to accurately transfer the fine pattern of the mask onto the wafer, it is required to obtain a top hat type uniform illumination distribution 34 on the wafer as shown in FIG. However, unless special measures are taken, illuminance unevenness occurs due to surface shape errors of the refractive surface and the boundary region that occur during the manufacture of the cylindrical micro fly's eye lens, and the rectangular stationary formed on the wafer W It is difficult to obtain a desired uniform illuminance distribution in the exposure region. In particular, due to the surface shape error of the boundary region, relatively large illuminance unevenness tends to occur at the corners of the illuminance distribution (indicated by the dashed small circle 34a in FIG. 4).

  That is, in the rectangular still exposure region, uneven illuminance occurs in both directions of the Y direction, which is the long side direction, and the X direction, which is the short side direction. In the case of the scanning exposure apparatus as in the present embodiment, even if illuminance unevenness remains to some extent in the X direction, which is the scanning direction, it does not pose a significant problem due to the scanning exposure averaging effect. However, if illuminance unevenness in the Y direction, which is the direction perpendicular to scanning, remains, it is difficult to obtain a desired illuminance distribution after scanning exposure, and it is difficult to achieve desired imaging performance.

  In the present embodiment, in the static exposure region formed on the wafer W, it is required to suppress the occurrence of illuminance unevenness particularly in the Y direction (corresponding to the Z direction at the position of the cylindrical micro fly's eye lens 9). . A group of refractive surfaces 9ab formed on the exit side (mask side) of the first fly's eye member 9a of the cylindrical micro fly's eye lens 9 contributes to the design of the illuminance distribution in the Y direction in the still exposure region. And a group of refracting surfaces 9bb formed on the exit side of the second fly's eye member 9b. When the conventional technique is applied to the cylindrical micro fly's eye lens 9, the surface shape errors of the group of refracting surfaces 9ab and 9bb and the surface shape errors of the boundary region of the refracting surface 9ab and the boundary region of the refracting surface 9bb are Y direction. Cause illuminance unevenness in the illuminance distribution.

  In the present embodiment, as shown in FIG. 5, a group of refracting surfaces 9ab formed on the exit side of the first fly's eye member 9a of the cylindrical micro fly's eye lens 9 between two adjacent refracting surfaces 9ab, and In the group of refracting surfaces 9bb formed on the exit side of the second fly's eye member 9b, for example, a planar region 9c is positively provided between two adjacent refracting surfaces 9bb, and the second fly's eye member 9b A diffractive optical surface 9d is formed on the whole or a part of the provided planar region 9c.

  That is, the diffractive optical surface 9d may be formed in all the planar regions 9c provided between the group of refractive surfaces 9bb, or may be formed in at least one planar region 9c. . Further, the diffractive optical surface 9d may be formed over the entire one planar area 9c, or may be formed in a part of the one planar area 9c. The surface shape of the region 9c provided between the group of refracting surfaces 9ab and between the group of refracting surfaces 9bb is not limited to a planar shape, and is between the two cylindrical surface-shaped refracting surfaces 9ab and 9bb. Any surface shape can be used as long as it can be formed with high accuracy and the diffractive optical surface 9d can be formed with high accuracy.

  In this case, the light incident on the group of refracting surfaces 9ab and passing through the corresponding refracting surfaces 9bb passes through the light guide optical system including the condenser optical system 11 and the imaging optical system 13 to the illumination area on the mask M. The illumination is performed in a superimposed manner, and the still exposure region is illuminated in a superimposed manner via the projection optical system PL. Also, light that has entered a planar region 9c provided between the group of refractive surfaces 9ab and passed through the corresponding diffractive optical surface 9d (or the planar region 9c in which the diffractive optical surface 9d is not formed) is also transmitted. The illumination area on the mask M is reached via the light guide optical system (11, 13), and the still exposure area is reached via the projection optical system PL.

  In the present embodiment, the diffractive optical surface 9d includes the illuminance unevenness caused by the surface shape error of the group of refracting surfaces 9ab and 9bb, and the region 9c and the group of refracting surfaces provided between the group of refracting surfaces 9ab. Designed to correct (adjust) illuminance unevenness caused by light that has passed through a region 9c provided between 9bb and not formed with the diffractive optical surface 9d. In this way, the action of the diffractive optical surface 9d suppresses the influence of surface shape errors of the refracting surfaces 9ab and 9bb, and further suppresses the occurrence of illuminance unevenness in the Y direction, which is the direction perpendicular to the scanning direction. The illuminance distribution along the Y direction in the exposure region can be made uniform. As a result, a desired illuminance distribution can be obtained after scanning exposure, and good exposure can be performed based on desired imaging performance.

  In the above description, the diffractive optical surface 9d is formed on the whole or a part of the planar region 9c provided on the second fly's eye member 9b. However, the present invention is not limited to this, and the diffractive optical surface 9d may be formed on the whole or a part of the planar region 9c provided on the first fly-eye member 9a, or the first fly-eye member 9a and The diffractive optical surfaces 9d may be formed on both the second fly's eye members 9b. However, in this case, since the light diffracted by the diffractive optical surface 9d provided on the first fly's eye member 9a passes through the second fly's eye member 9b, the design of the diffractive optical surface 9d is complicated. There is a possibility.

  In the above description, the occurrence of illuminance unevenness in the Y direction, which is the direction perpendicular to the scan, is suppressed to a small level. It is also possible to make the illuminance distribution uniform throughout. A group of refractive surfaces 9aa formed on the incident side (light source side) of the first fly's eye member 9a of the cylindrical micro fly's eye lens 9 contributes to the design of the illuminance distribution in the X direction in the still exposure region. And a group of refracting surfaces 9ba formed on the incident side of the second fly's eye member 9b.

  Therefore, in order to make the illuminance distribution uniform over the entire still exposure region, a configuration as shown in FIG. 6 may be adopted in addition to the configuration of FIG. In FIG. 6, in the group of refracting surfaces 9aa formed on the incident side of the first fly's eye member 9a, the group of refracting surfaces 9aa formed between the two adjacent refracting surfaces 9aa and on the incident side of the second fly's eye member 9b. For example, a planar region 9e is provided between two refracting surfaces 9ba adjacent to each other on the refracting surface 9ba, and the diffractive optical surface 9f is formed on the whole or a part of the planar region 9e provided on the second fly's eye member 9b. Is forming.

  The diffractive optical surface 9f is provided between the illuminance unevenness caused by the surface shape error of the group of refracting surfaces 9aa and 9ba, and the region 9e provided between the group of refracting surfaces 9aa and the group of refracting surfaces 9ba. It is designed to correct (adjust) the illuminance unevenness caused by the light that has passed through the region 9e where the diffractive optical surface 9f is not formed. As a result, due to the action of the diffractive optical surfaces 9d and 9f provided on the second fly's eye member 9b, the influence of the surface shape error of each of the refractive surfaces 9aa, 9ab, 9ba, 9bb is suppressed to be small on the wafer W. The illuminance distribution can be made uniform over the entire static exposure region.

  In FIG. 6, the diffractive optical surface 9f is formed on the whole or a part of the planar region 9e provided on the second fly's eye member 9b, but the first fly's eye member is not limited to this. The diffractive optical surface 9f may be formed on the whole or a part of the planar region 9e provided on 9a, or the diffractive optical surface 9f is formed on both the first fly eye member 9a and the second fly eye member 9b. You may do it. However, in this case, since the light diffracted by the diffractive optical surface 9f provided on the first fly's eye member 9a passes through the second fly's eye member 9b, the design of the diffractive optical surface 9f is complicated. There is a possibility.

  In the above description, the cylindrical micro fly's eye lens 9 having the form shown in FIG. 2 is used as the wavefront division type optical integrator. However, the present invention is not limited to this, for example, as shown in FIG. It is also possible to use a cylindrical micro fly's eye lens 19 having another form. As shown in FIG. 7, the cylindrical micro fly's eye lens 19 includes a first fly eye member 19a disposed on the light source side and a second fly eye member 19b disposed on the mask side.

  A plurality of cylindrical refracting surfaces (cylindrical lens groups) 19aa and 19ab arranged side by side in the X direction are formed at a pitch p1 on the light source side surface and the mask side surface of the first fly-eye member 19a. ing. A plurality of cylindrical refracting surfaces (cylindrical lens groups) 19ba and 19bb arranged side by side in the Z direction are respectively formed on the light source side surface and the mask side surface of the second fly-eye member 19b at a pitch p2 (p2>). p1).

  Focusing on the refractive action in the X direction of the cylindrical micro fly's eye lens 19 (that is, the refractive action in the XY plane), a group of parallel light beams incident along the optical axis AX are formed on the light source side of the first fly's eye member 19a. Corresponding in the group of refracting surfaces 19ab formed on the mask side of the first fly's eye member 19a after the wavefront is divided at the pitch p1 along the X direction by the refracting surfaces 19aa The light is focused on the refracting surface to be focused on the rear focal plane of the cylindrical micro fly's eye lens 19.

  Focusing on the refractive action in the Z direction of the cylindrical micro fly's eye lens 19 (that is, the refractive action in the YZ plane), a group of parallel beams incident along the optical axis AX are formed on the light source side of the second fly's eye member 19b. Corresponding in the group of refracting surfaces 19bb formed on the mask side of the second fly's eye member 19b after the wave front is divided at the pitch p2 along the Z direction by the refracting surfaces 19ba of the second fly-eye member 19b. The light is focused on the refracting surface to be focused on the rear focal plane of the cylindrical micro fly's eye lens 19.

  When the cylindrical micro fly's eye lens 19 is used, it is formed on the incident side (light source side) of the second fly's eye member 19b that contributes to the design of the illuminance distribution in the Y direction (scanning orthogonal direction) in the still exposure region. And a group of refracting surfaces 19bb formed on the exit side (mask side) of the second fly's eye member 19b. Therefore, in order to make the illuminance distribution in the Y direction in the still exposure region uniform, a configuration as shown in FIG. 8 may be employed.

  In FIG. 8, in the group of refracting surfaces 19ba formed on the incident side of the second fly's eye member 19b of the cylindrical micro fly's eye lens 19, between two adjacent refracting surfaces 19ba and the exit of the second fly's eye member 19b. For example, a planar region 19c is provided between two adjacent refracting surfaces 19bb in the group of refracting surfaces 19bb formed on the side, and the planar region 19c provided on the exit side of the second fly's eye member 19b. A diffractive optical surface 19d is formed entirely or partially.

  The diffractive optical surface 19d is provided between the region 19c provided between the group of refracting surfaces 19ba and the group of refracting surfaces 19bb and the uneven illuminance caused by the surface shape errors of the group of refracting surfaces 19ba and 19bb. It is designed to correct (adjust) the illuminance unevenness caused by the light passing through the region 19c where the diffractive optical surface 19d is not formed. As a result, due to the action of the diffractive optical surface 19d provided on the second fly's eye member 19b, the influence of the surface shape error of each refractive surface 19ba, 19bb is suppressed to be small, and the Y direction in the still exposure region on the wafer W is reduced. The illuminance distribution can be made uniform.

  In FIG. 8, the diffractive optical surface 19d is formed on the whole or a part of the planar region 19c provided on the exit side of the second fly's eye member 19b. However, the present invention is not limited to this. The diffractive optical surface 19d may be formed on the whole or a part of the planar region 19c provided on the incident side of the fly eye member 19b, or diffracted on both the incident side and the exit side of the second fly eye member 19b. The optical surface 19d may be formed. However, in this case, since the light diffracted by the diffractive optical surface 19d provided on the incident side of the second fly's eye member 19b passes through the inside of the second fly's eye member 19b, the diffractive optical surface 19d. The design can be complicated.

  On the other hand, when the cylindrical micro fly's eye lens 19 is used, it is on the incident side (light source side) of the first fly's eye member 19a that contributes to the design of the illuminance distribution in the X direction (scanning direction) in the still exposure region. The group of refracting surfaces 19aa formed and the group of refracting surfaces 19ab formed on the exit side (mask side) of the first fly's eye member 19a. Therefore, in order to make the illuminance distribution uniform over the entire still exposure region, a configuration as shown in FIG. 9 may be adopted in addition to the configuration in FIG.

  In FIG. 9, in a group of refracting surfaces 19aa formed on the incident side of the first fly's eye member 19a of the cylindrical micro fly's eye lens 19, between two adjacent refracting surfaces 19aa and the exit of the first fly's eye member 19a. For example, a planar region 19e is provided between two adjacent refracting surfaces 19ab in the group of refracting surfaces 19ab formed on the side, and the planar region 19e provided on the exit side of the first fly's eye member 19a. A diffractive optical surface 19f is formed in whole or in part.

  The diffractive optical surface 19f is provided between the region 19e provided between the group of refracting surfaces 19aa and the group of refracting surfaces 19ab, and uneven illuminance caused by surface shape errors of the group of refracting surfaces 19aa and 19ab. It is designed to correct (adjust) the illuminance unevenness caused by the light passing through the region 19e where the diffractive optical surface 19f is not formed. As a result, due to the action of the diffractive optical surface 19d provided on the second fly's eye member 19b and the diffractive optical surface 19f provided on the first fly's eye member 19a, the surface shapes of the refractive surfaces 19aa, 19ab, 19ba, 19bb It is possible to make the illuminance distribution uniform over the entire static exposure region on the wafer W while minimizing the influence of errors and the like.

  In FIG. 9, the diffractive optical surface 19f is formed on the whole or a part of the planar region 19e provided on the exit side of the first fly's eye member 19a. However, the present invention is not limited to this. The diffractive optical surface 19f may be formed on the whole or a part of the planar region 19e provided on the incident side of the fly eye member 19a, or diffracted on both the incident side and the exit side of the first fly eye member 19a. The optical surface 19f may be formed. However, in this case, the light diffracted by the diffractive optical surface 19f provided on the incident side of the first fly's eye member 19a passes through the inside of the first fly's eye member 19a and the second fly's eye member 19b. Therefore, the design of the diffractive optical surface 19f may be complicated.

  In the above-described embodiment, the present invention is applied to the cylindrical micro fly's eye lenses 9 and 19 including a pair of fly's eye members (optical members). However, the present invention is not limited to this, and the present invention can be similarly applied to an optical integrator composed of a single optical member. For example, in a micro fly's eye lens or a fly's eye lens, a plurality of refractive surfaces are two-dimensionally arranged on at least one of an entrance surface and an exit surface of a single optical member. What is necessary is just to form at least 1 diffractive optical surface in the area | region between refractive surfaces. In this case, the diffractive optical surface can be easily designed by forming the diffractive optical surface on the exit surface of the single optical member. In general, in a wavefront division type optical integrator having a plurality of refractive surfaces arranged one-dimensionally or two-dimensionally, at least one diffractive optical surface is formed in a region between a plurality of adjacent refractive surfaces. Thus, the function and effect of the present invention can be achieved.

  In the above-described embodiment, the present invention is applied to an exposure apparatus that scans and exposes a pattern in each exposure area of a wafer according to a so-called step-and-scan method while moving the mask and the wafer relative to the projection optical system. The invention is applied. However, the present invention is not limited to this. For an exposure apparatus that sequentially exposes a pattern on a shot area of a wafer according to a so-called step-and-repeat method by performing batch exposure while controlling the wafer in two dimensions. However, the present invention can also be applied.

  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. By using such a variable pattern forming apparatus, the influence on the synchronization accuracy can be minimized even if the pattern surface is placed vertically. As the variable pattern forming apparatus, for example, a DMD (digital micromirror device) including a plurality of reflecting elements driven based on predetermined electronic data can be used. An exposure apparatus using DMD is disclosed in, for example, Japanese Patent Application Laid-Open Nos. 8-313842 and 2004-304135. In addition to a non-light-emitting reflective spatial light modulator such as DMD, a transmissive spatial light modulator may be used, or a self-luminous image display element may be used. Note that a variable pattern forming apparatus may be used even when the pattern surface is placed horizontally.

  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 is preferably 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. 10 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 10, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a substrate of the semiconductor device (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the projection 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 wafer W after the transfer is completed. Development, that is, development of the photoresist to which the pattern has been transferred (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 projection exposure apparatus of the above-described embodiment is generated, and the recess penetrates the photoresist layer. It is. 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 projection exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as the photosensitive substrate, that is, the plate P.

  FIG. 11 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 11, in the manufacturing process of the liquid crystal device, a pattern formation process (step S50), a color filter formation process (step S52), a cell assembly process (step S54), and a module assembly 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 projection exposure apparatus of the above-described embodiment. The pattern forming step includes an exposure step of transferring the pattern to the photoresist layer using the projection exposure apparatus of the above-described embodiment, and development of the plate P on which the pattern is transferred, that is, development of the photoresist layer on the glass substrate. 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 process in 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 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, 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, the present invention is applied to the optical integrator used in the illumination optical system of the exposure apparatus, but the wavefront used in a general optical apparatus is not limited to this. The present invention can also be applied to a split-type optical integrator. 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 the irradiated surface other than the mask or wafer is illuminated. The present invention can also be applied to a general illumination optical system.

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a perspective view which shows schematically the structure of the cylindrical micro fly's eye lens of FIG. It is a figure which shows typically the error which generate | occur | produces in the refractive surface of a cylindrical micro fly's eye lens, and the surface shape of a boundary region. It is a figure which shows the site | part which an illumination intensity nonuniformity tends to generate | occur | produce due to the uniform illumination intensity distribution which should be formed on a wafer, and the surface shape error of the boundary area | region of a refracting surface. FIG. 3 is a diagram schematically illustrating a configuration for uniformizing an illuminance distribution in a scanning orthogonal direction in the cylindrical micro fly's eye lens of FIG. 2. FIG. 3 is a diagram schematically illustrating a configuration for making an illuminance distribution uniform over the entire static exposure region in the cylindrical micro fly's eye lens of FIG. 2. It is a perspective view which shows roughly the structure of the cylindrical micro fly's eye lens which has another form from FIG. FIG. 8 is a diagram schematically illustrating a configuration for equalizing an illuminance distribution in a scanning orthogonal direction in the cylindrical micro fly's eye lens of FIG. 7. FIG. 8 is a diagram schematically illustrating a configuration for making the illuminance distribution uniform over the entire static exposure region in the cylindrical micro fly's eye lens of FIG. 7. 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.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Light source 3 Polarization state switching part 4 Diffractive optical element 5 Afocal lens 7 Conical axicon system 8 Zoom lens 9 Cylindrical micro fly's eye lens (optical integrator)
11 Condenser optical system 12 Mask blind 13 Imaging optical system M Mask PL Projection optical system W Wafer

Claims (12)

In the wavefront division type optical integrator,
A plurality of refractive surfaces arranged one-dimensionally or two-dimensionally;
An optical integrator comprising: at least one diffractive optical surface formed in a region between the plurality of refractive surfaces adjacent to each other on the plurality of refractive surfaces. The plurality of refractive surfaces are two-dimensionally arranged on at least one of an entrance surface and an exit surface of a single optical member, and the at least one diffractive optical surface is incident on the single optical member. The optical integrator according to claim 1, wherein the optical integrator is formed on at least one of a surface and an emission surface. The optical integrator according to claim 2, wherein the at least one diffractive optical surface is formed on an exit surface of the single optical member. In order from the light incident side, a first optical member and a second optical member are provided,
The first optical member has a plurality of refractive powers having a predetermined refractive power in a first direction in a plane perpendicular to the optical axis and substantially non-refractive in a second direction perpendicular to the first direction in the plane. A first refracting surface is arranged along the first direction;
The second optical member is formed to correspond to the plurality of first refracting surfaces, has a predetermined refractive power in the first direction, and has a plurality of second powers having almost no refractive power in the second direction. Refracting surfaces are arranged along the first direction;
The at least one diffractive optical surface includes a region between two refracting surfaces adjacent to each other in the plurality of first refracting surfaces and a region between two refracting surfaces adjacent to each other in the plurality of second refracting surfaces. The optical integrator according to claim 1, wherein the optical integrator is formed in at least one of the regions. The optical integrator according to claim 4, wherein the at least one diffractive optical surface is formed in a region between two refracting surfaces adjacent to each other in the plurality of second refracting surfaces. On the opposite side of the first optical member from the side on which the plurality of first refracting surfaces are provided, there are a plurality of refracting powers having a predetermined refractive power in the second direction and substantially no refractive power in the first direction. A third refracting surface is arranged along the second direction;
The second optical member is formed on the side opposite to the side where the plurality of second refracting surfaces are provided so as to correspond to the plurality of third refracting surfaces, and has a predetermined refractive power in the second direction. And a plurality of fourth refractive surfaces having substantially no refractive power in the first direction are arranged along the second direction,
The at least one diffractive optical surface includes a region between two refracting surfaces adjacent to each other in the plurality of third refracting surfaces and a region between two refracting surfaces adjacent to each other in the plurality of fourth refracting surfaces. The optical integrator according to claim 5, wherein the optical integrator is formed in at least one of the regions. In order from the light incident side, a first optical member and a second optical member are provided,
The first optical member has a plurality of refractive powers having a predetermined refractive power in a first direction in a plane perpendicular to the optical axis and substantially non-refractive in a second direction perpendicular to the first direction in the plane. A first refracting surface is arranged along the first direction;
In the second optical member, a plurality of second refractive surfaces having a predetermined refractive power in the second direction and having almost no refractive power in the first direction are arranged along the second direction,
The at least one diffractive optical surface includes a region between two refracting surfaces adjacent to each other in the plurality of first refracting surfaces and a region between two refracting surfaces adjacent to each other in the plurality of second refracting surfaces. The optical integrator according to claim 1, wherein the optical integrator is formed in at least one of the regions. A side of the first optical member opposite to the side on which the plurality of first refracting surfaces are provided is formed so as to correspond to the plurality of first refracting surfaces and has a predetermined refractive power in the first direction. And a plurality of third refractive surfaces having substantially no refractive power in the second direction are arranged along the first direction,
The second optical member is formed on the side opposite to the side where the plurality of second refracting surfaces are provided so as to correspond to the plurality of second refracting surfaces, and has a predetermined refractive power in the second direction. And a plurality of fourth refractive surfaces having substantially no refractive power in the first direction are arranged along the second direction,
The at least one diffractive optical surface includes a region between two refracting surfaces adjacent to each other in the plurality of third refracting surfaces and a region between two refracting surfaces adjacent to each other in the plurality of fourth refracting surfaces. The optical integrator according to claim 7, wherein the optical integrator is formed in at least one of the regions. In the illumination optical system that illuminates the illuminated surface based on the light from the light source,
9. An illumination optical system comprising the optical integrator according to claim 1 disposed in an optical path of the illumination optical system. A light guide optical system that guides light through each of the plurality of refractive surfaces of the optical integrator to the irradiated surface in a superimposed manner and guides light through the at least one diffractive optical surface to the irradiated surface; The illumination optical system according to claim 9, wherein the illumination optical system is provided. 11. An exposure apparatus comprising the illumination optical system according to claim 9 or 10 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. An exposure step of exposing the predetermined pattern to the photosensitive substrate using the exposure apparatus according to claim 11;
Developing the photosensitive substrate to which the pattern has been transferred, and forming a mask layer having a shape corresponding to the pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

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