JP2011009317A - Optical integrator, illumination optical system, exposure device, and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To correct illuminance unevenness of an illumination region formed on a surface to be irradiated while saving space and suppressing light quantity loss and generation of a flare small.SOLUTION: The optical integrator (7) having a plurality of wavefront division elements arranged in two dimensions and in parallel includes: a first optical member (7a) having a plurality of first incident refractive surfaces (7aa) in a cylinder surface shape which are formed alongside in one direction (X direction) and a plurality of first projection refractive surfaces (7ab) in a cylinder surface shape which are formed alongside in one direction (Z direction); and a second optical member (7b) disposed behind the first optical member and having a plurality of second incident refractive surfaces (7ba) in a cylinder surface shape which are formed alongside in the one direction (X direction) and a plurality of second projection refractive surfaces (7bb) in a cylinder surface shape which are formed alongside in one direction (Z direction). A dimming region which has a predetermined transmissivity distribution is provided on at least one of the plurality of refractive surfaces.

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 illumination optical system suitable for an exposure apparatus for 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.

  In a typical exposure apparatus of this type, light emitted from a light source forms a secondary light source as a substantial surface light source including a large number of light sources via a fly-eye lens as an optical integrator. The light from the secondary light source is condensed by the condenser lens 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 a wafer (photosensitive substrate) via a projection optical system, and a mask pattern is projected and exposed (transferred) onto the wafer.

  The pattern formed on the mask is highly integrated, and in order to accurately transfer this fine pattern onto the wafer, it is indispensable to obtain a uniform illuminance distribution on the wafer. Conventionally, a technique has been proposed in which a correction filter having a predetermined transmittance distribution is provided immediately before an optical integrator, and illuminance unevenness on the wafer is corrected by the action of the correction filter (see, for example, Patent Document 1).

US Pat. No. 5,615,047

  In the conventional technique proposed in Patent Document 1, it is necessary to secure a mechanical space related to the correction filter in addition to the arrangement space of the correction filter itself. In addition, light loss occurs during transmission through the correction filter, and flare due to reflection on the optical surface of the correction filter tends to occur. Furthermore, it is necessary to position the correction filter with high accuracy with respect to the optical integrator.

  The present invention has been made in view of the above-described problems, and is intended to correct illuminance unevenness in an illumination area formed on an irradiated surface while saving space and suppressing light loss and flare generation to a small extent. An object of the present invention is to provide an illumination optical system that can be used. Also provided are an exposure apparatus and a device manufacturing method capable of accurately transferring a pattern based on a desired illuminance distribution using an illumination optical system that corrects illuminance unevenness in an illumination area formed on an illuminated surface. For the purpose.

In order to solve the above-mentioned problem, in the first embodiment of the present invention, in an optical integrator having a plurality of wavefront division elements arranged two-dimensionally in parallel,
A first optical member having a plurality of cylindrical first incident refractive surfaces formed side by side in one direction and a plurality of cylindrical first emission refractive surfaces formed side by side in one direction;
A plurality of cylindrical incident second refracting surfaces arranged in one direction and arranged in the rear side of the first optical member, and a plurality of cylindrical second surfaces formed in one direction. A second optical member having an exit refractive surface,
An optical integrator is provided, wherein at least one refracting surface among the plurality of refracting surfaces is provided with a dimming region having a predetermined transmittance distribution.

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,
A first form of optical integrator;
There is provided an illumination optical system comprising: a distribution forming optical system that forms a pupil intensity distribution in an illumination pupil on the rear side of the optical integrator.

  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 predetermined pattern is transferred, and forming a mask layer having a shape corresponding to the predetermined 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 an optical integrator according to an aspect of the present invention, a predetermined transmission is applied to at least one refracting surface among a plurality of refracting surfaces, for example, one or a plurality of unit regions corresponding to a unit wavefront dividing surface in a first exit refracting surface. A dimming region having a rate distribution is provided. Therefore, as will be described later, it is possible to correct (adjust) the illuminance unevenness of the illumination area formed on the irradiated surface by the action of the dimming area provided in one or more unit areas.

  In the illumination optical system of the present invention, it is not necessary to attach a correction filter having a predetermined transmittance distribution immediately before the optical integrator, so that the surface to be irradiated is saved while saving space and reducing the occurrence of light loss and flare. Irradiance unevenness in the illumination area formed on the substrate can be corrected. As a result, in the exposure apparatus of the present invention, the pattern is accurately transferred to the wafer W based on the desired illuminance distribution using the illumination optical system that corrects the illuminance unevenness of the illumination area formed on the irradiated surface. And thus good devices can be manufactured.

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 perspective view which shows roughly the four wavefront division elements which comprise the cylindrical micro fly's eye lens of this embodiment. FIG. 4 is a view of the four wavefront splitting elements in FIG. 3 as viewed from the incident side along the optical axis. It is a figure which shows a mode that the light reduction area | region which has a predetermined transmittance | permeability distribution is provided in the unit area | region corresponding to a unit wavefront division surface. It is a figure which shows an example of the transmittance | permeability distribution provided to the light reduction area | region. It is a figure which shows the light intensity distribution of the illumination area | region which the light beam which passed through the light reduction area | region which has the transmittance | permeability distribution of FIG. 6 forms on a wafer. It is a figure which shows typically the annular-shaped pupil intensity distribution formed in annular illumination, and the small circular pupil intensity distribution formed in circular illumination with a small (sigma) value. It is a perspective view which shows roughly the structure of the cylindrical micro fly's eye lens which has another form from FIG. 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 is along the normal direction of the transfer surface (exposure surface) of the wafer W, which is a photosensitive substrate, and the Y-axis is in the direction parallel to the paper surface of FIG. In the W transfer surface, 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 1. 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. The 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 then enters the afocal lens 4 via, for example, a diffractive optical element 3 for annular illumination.

  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 surface 5 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.

  Specifically, 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. Have. Therefore, the substantially parallel light beam incident on the diffractive optical element 3 is emitted from the afocal lens 4 with a ring-shaped angular distribution after forming a ring-shaped light intensity distribution on the pupil plane of the afocal lens 4.

  The light emitted from the afocal lens 4 passes through a zoom lens 6 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 cylindrical as an optical integrator. The light enters the micro fly's eye lens 7. As shown in FIG. 2, the cylindrical micro fly's eye lens 7 includes a first fly eye member (first optical member) 7a disposed on the light source side and a second fly eye member (second optical member) disposed on the mask side. Member) 7b.

  On the light source side (incident side) surface of the first fly's eye member 7a and the light source side surface of the second fly's eye member 7b, a plurality of cylindrical refractive surfaces (cylindrical lens groups) arranged side by side in the X direction. ) 7aa and 7ba are formed with a pitch px. A plurality of cylindrical refractive surfaces (cylindrical lens groups) arranged side by side in the Z direction are provided on the mask side (exit side) surface of the first fly eye member 7a and the mask side surface of the second fly eye member 7b. 7ab and 7bb are formed with a pitch pz (pz> px).

  Focusing on the refraction action in the X direction of the cylindrical micro fly's eye lens 7 (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 7a. Corresponding in a group of refracting surfaces 7ba formed on the light source side of the second fly's eye member 7b after being wave-divided by the refracting surface 7aa along the X direction at a pitch px and receiving a 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 7.

  Focusing on the refractive action in the Z direction of the cylindrical micro fly's eye lens 7 (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 7a. Corresponding in the group of refracting surfaces 7bb formed on the mask side of the second fly's eye member 7b after the wavefront is divided at the pitch pz along the Z direction by the refracting surfaces 7ab The light is focused on the refracting surface to be focused on the rear focal plane of the cylindrical micro fly's eye lens 7.

  As described above, the cylindrical micro fly's eye lens 7 is composed of the first fly eye member 7a and the second fly eye member 7b in which the cylindrical lens group is formed on both side surfaces, and the size of px is set in the X direction. It has an optical function similar to that of a micro fly's eye lens in which a large number of rectangular minute refracting surfaces having a size of pz in the Z direction are integrally formed vertically and horizontally. That is, the cylindrical micro fly's eye lens 7 is configured by two-dimensionally arranging a number of wavefront division elements having a rectangular cross section having an X direction dimension of px and a Z direction dimension of pz along the XZ plane. It is an optical integrator.

  Each wavefront dividing element constituting the cylindrical micro fly's eye lens 7 has a rectangular wavefront dividing surface having a short side along the X direction and a long side along the Z direction. In the cylindrical micro fly's eye lens 7, a change in distortion due to variations in the surface shape of the microrefractive surface is suppressed to be small. For example, manufacturing errors of a large number of microrefractive surfaces integrally formed by etching process give the illuminance distribution. The influence can be kept small.

  The position of the predetermined surface 5 is disposed at or near the front focal position of the zoom lens 6, and the incident surface of the cylindrical micro fly's eye lens 7 (that is, the incident surface of the first fly's eye member 7 a) is the rear focal position of the zoom lens 6. Or it is arrange | positioned in the vicinity. In other words, in the zoom lens 6, the predetermined surface 5 and the incident surface of the cylindrical micro fly's eye lens 7 are arranged substantially in a Fourier transform relationship, and as a result, the pupil surface of the afocal lens 4 and the cylindrical micro fly's eye lens 7. The incident surface is optically substantially conjugate.

  Accordingly, on the incident surface of the cylindrical micro fly's eye lens 7, 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 4. The overall shape of the annular illumination field changes in a similar manner depending on the focal length of the zoom lens 6. As described above, each wavefront dividing element of the cylindrical micro fly's eye lens 7 has a rectangular unit wavefront dividing surface having a long side along the Z direction and a short side along the X direction. The unit wavefront dividing surface of the shape is a rectangular shape similar to the shape of the illumination region to be formed on the mask M (and thus the shape of the exposure region to be formed on the wafer W).

  The light beam incident on the cylindrical micro fly's eye lens 7 is two-dimensionally divided, and the illumination light formed on the incident surface of the cylindrical micro fly's eye lens 7 is substantially the same light on the rear focal plane or in the vicinity of the illumination pupil. A secondary light source (pupil intensity distribution) composed of a secondary light source having an intensity distribution, that is, a substantial surface light source having an annular shape centering on the optical axis AX is formed.

  An illumination aperture stop (not shown) having an annular opening (light transmitting portion) corresponding to an annular secondary light source on the rear focal plane of the cylindrical micro fly's eye lens 7 or in the vicinity thereof, if necessary. Is arranged. The illumination aperture stop is configured to be detachable with respect to the illumination optical path, and is configured to be switchable with a plurality of aperture stops having apertures 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 is disposed at a position optically 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 light that has passed through the cylindrical micro fly's eye lens 7 illuminates the mask blind 9 in a superimposed manner via a condenser optical system 8. Thus, a rectangular illumination field corresponding to the shape and focal length of the unit wavefront dividing surface of the cylindrical micro fly's eye lens 7 is formed on the mask blind 9 as an illumination field stop. The light that has passed through the rectangular opening (light transmission portion) of the mask blind 9 passes through the imaging optical system 10 including the front lens group 10a and the rear lens group 10b, and the mask M on which a predetermined pattern is formed. Are illuminated in a superimposed manner.

  That is, the imaging optical system 10 forms an image of the rectangular opening of the mask blind 9 on the mask M. The pupil plane of the imaging optical system 10 is in an optically conjugate position with the rear focal plane of the cylindrical micro fly's eye lens 7 or the illumination pupil in the vicinity thereof, and the illumination plane in or near the pupil plane of the imaging optical system 10. In addition, an annular pupil intensity distribution is formed.

  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 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 the present embodiment, as described above, the secondary light source formed by the cylindrical micro fly's eye lens 7 is used as a light source, and the mask M disposed on the irradiated surface of the illumination optical system (2 to 10) 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 (2 to 10). 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 (2 to 10) or a plane optically conjugate with the illumination pupil plane. When the number of wavefront divisions by the cylindrical micro fly's eye lens 7 is relatively large, the overall light intensity distribution formed on the incident surface of the cylindrical micro fly's eye lens 7 and the overall light intensity distribution of the entire secondary light source (pupil) Intensity distribution). For this reason, the light intensity distribution on the incident surface of the cylindrical micro fly's eye lens 7 and a surface optically conjugate with the incident surface can also be referred to as a pupil intensity distribution. In the configuration of FIG. 1, the diffractive optical element 3, the afocal lens 4, the zoom lens 6, and the micro fly's eye lens 7 form a pupil intensity distribution on the rear focal plane of the micro fly's eye lens 7 or in the vicinity of the illumination pupil. The distribution forming optical system is configured.

  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. It has the function to do. Therefore, the light flux that has passed through the diffractive optical element for multipole illumination is irradiated on the incident surface of the cylindrical micro fly's eye lens 7 with, for example, a plurality of predetermined shapes (arc shape, circular shape, etc.) centered on the optical axis AX. A multipolar illumination field consisting of 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 7 or on the illumination pupil near the rear focal plane.

  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 cylindrical micro fly's eye lens 7. 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 the rear focal plane of the cylindrical micro fly's eye lens 7 or on the illumination pupil in the vicinity thereof. 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.

  In the exposure apparatus of the present embodiment, as described above, scanning exposure is performed while relatively moving the mask M and the wafer W along the X direction with respect to the projection optical system PL. In this case, due to the averaging effect of the scanning exposure, even if some illuminance unevenness remains in the X direction, which is the scanning direction, in the exposure region on the wafer W, it does not cause a big problem. The illuminance unevenness that should be corrected well in the exposure area (illumination area) on the wafer W is the illuminance unevenness in the Y direction (scanning orthogonal direction) orthogonal to the scanning direction.

  FIG. 3 is a perspective view schematically showing four wavefront splitting elements that constitute a cylindrical micro fly's eye lens in the present embodiment. FIG. 4 is a view of the four wavefront splitting elements in FIG. 3 as viewed from the incident side along the optical axis. Referring to FIG. 3, among the many wavefront splitting elements constituting the cylindrical micro fly's eye lens 7, two first incident refracting surfaces 7 aa arranged in the X direction and two first exit refracting surfaces 7 ab arranged in the Z direction. The four wavefront splitting elements defined by are shown.

  In FIG. 4, three straight lines 41 extending along the Z direction are boundaries between two first incident refracting surfaces 7aa adjacent in the X direction, and three straight lines 42 extending along the X direction are adjacent in the Z direction. This is a boundary line between two first exit refracting surfaces 7ab. A rectangular region sandwiched between a pair of boundary lines 41 adjacent in the X direction and a pair of boundary lines 42 adjacent in the Z direction on the first incident refracting surface 7aa has short side dimensions px and Z along the X direction. An incident surface 7ea of the wavefront splitting element having a rectangular cross section defined by the long side dimension pz along the direction, that is, a unit wavefront splitting plane is configured.

  In the present embodiment, as shown in FIG. 5, one or more sandwiched between a pair of boundary lines 41 adjacent in the X direction and a pair of boundary lines 42 adjacent in the Z direction on the first exit refracting surface 7ab. A dimming region 7f having a predetermined transmittance distribution is provided in one or a plurality of unit regions 7eb corresponding to the incident surface 7ea of each wavefront dividing element in the rectangular region, that is, the first exit refracting surface 7ab. . Hereinafter, in order to simplify the description, as shown in FIG. 6, the dimming region 7f having a transmittance distribution that changes one-dimensionally along the Z direction is represented by one unit region 7eb on the first exit refracting surface 7ab. It is assumed that it is formed.

  The dimming region 7f is configured by distributing and forming a large number of light-shielding dots made of, for example, chromium or chromium oxide in the unit region 7eb. A large number of light-shielding dots are formed in accordance with a predetermined arrangement density distribution that varies along the Z direction in order to give a required transmittance distribution to the dimming region 7f. Here, the arrangement density is an area occupied by light-shielding dots per unit area in the light reduction region.

  The first exit refracting surface 7ab provided with the dimming region 7f is in the vicinity of a position optically conjugate with the transfer surface of the wafer W (and thus the pattern surface of the mask M). Therefore, in the rectangular illumination region (corresponding to the static exposure region) formed on the wafer W by the light beam that has passed through the unit region 7eb provided with the light reduction region 7f on the first exit refracting surface 7ab, the Y direction (cylindrical micro fly The light intensity distribution along the Z direction in the eye lens 7 is affected by the transmittance distribution along the Z direction of the dimming region 7f. Specifically, as shown in FIG. 7, the light intensity distribution along the Y direction of the illumination area exhibits the same properties as the transmittance distribution along the Z direction of the dimming area 7f.

  This means that the light intensity distribution along the Y direction of the final illumination area formed on the wafer W by the light beam that has passed through the cylindrical micro fly's eye lens 7 is also provided in one unit area 7eb on the first exit refracting surface 7ab. It means that it changes under the action of the light attenuation region 7f. Accordingly, for example, by providing the required number of unit regions 7eb on the first exit refracting surface 7ab with the dimming regions 7f each having the required one-dimensional transmittance distribution, the wafers are caused by the cooperative action of the respective dimming regions 7f. Obviously, the illuminance unevenness of the final illumination area on W can be corrected (adjusted) as appropriate.

  As described above, the cylindrical micro fly's eye lens 7 of the present embodiment includes the first fly eye member (first optical member) 7a and the second fly eye member (second optical member) disposed adjacent to the rear side thereof. ) 7b. The first fly-eye member 7a includes a plurality of cylindrical first incident refracting surfaces 7aa formed side by side in the X direction, and a plurality of cylindrical first emission refracting surfaces 7ab formed side by side in the Z direction. Have The second fly-eye member 7b includes a plurality of cylindrical second incident refracting surfaces 7ba formed side by side in the X direction, and a plurality of cylindrical second emission refracting surfaces 7bb formed side by side in the Z direction. Have

  In the present embodiment, in the plurality of first exit refracting surfaces 7ab formed on the exit side of the first fly's eye member 7a, one or more unit regions 7eb corresponding to the entrance surfaces 7ea of the wavefront dividing elements are arranged in the Z direction. A dimming region 7f having a transmittance distribution that changes one-dimensionally is provided. In other words, a dimming region 7f having a predetermined transmittance distribution is provided on at least one of the plurality of first exit refracting surfaces 7ab. As a result, as described above, the Y of the illumination region on the wafer W (and thus the mask M) is caused by the action of the dimming region 7f provided in the one or more unit regions 7eb on the plurality of first exit refracting surfaces 7ab. Irradiance unevenness along the direction can be corrected (adjusted).

  In the illumination optical system (2 to 10) of the present embodiment, it is not necessary to attach a correction filter having a predetermined transmittance distribution immediately before the cylindrical micro fly's eye lens 7, which causes inconvenience in installing the correction filter. In addition, the illuminance unevenness along the Y direction of the illumination area on the mask M (and thus the wafer W) can be corrected. In other words, the illumination optical system (2 to 10) of the present embodiment is formed on the mask M (and thus the wafer W), which is the irradiated surface, while saving space and minimizing light loss and flare generation. Illuminance unevenness in the illumination area can be corrected. As a result, the exposure apparatus (2 to WS) of the present embodiment uses the illumination optical system (2 to 10) that corrects the illuminance unevenness of the illumination area formed on the mask M (and thus the wafer W) to obtain a desired illuminance. Based on the distribution, the pattern of the mask M can be accurately transferred to the wafer W.

  In the above-described embodiment, the dimming region 7f having a transmittance distribution that changes one-dimensionally along the Z direction is formed on the first exit refractive surface 7ab formed on the exit side of the first fly-eye member 7a. Provided. However, the present invention is not limited to this, and various forms are possible with respect to the cylindrical refracting surface provided with the dimming region, the property of the transmittance distribution provided to the dimming region, and the like. In general, a dimming region having a predetermined transmittance distribution can be provided on at least one of the plurality of cylindrical refracting surfaces constituting a cylindrical micro fly's eye lens as an optical integrator.

  However, in the above-described embodiment, the first exit refracting surface 7ab and the second optical surface that form the plurality of light-shielding dots according to the array density distribution that changes only along the Z direction without changing in the X direction. As the exit refracting surface 7bb, a cylindrical refracting surface having a curvature only in the Z direction without having a curvature in the X direction is suitable. Further, since the first exit refracting surface 7ab is closer to a surface optically conjugate with the transfer surface of the wafer W (and thus the pattern surface of the mask M) than the second exit refracting surface 7bb, the dimming region 7f is formed. Suitable as a refractive surface to be provided.

  Further, in the case where the first exit refracting surface 7ab is provided with the dimming region 7f as in the above-described embodiment, the light beam divided by the plurality of first incident refracting surfaces 7aa is focused on the Z direction. Since the light is incident on the dimming region 7f without being affected, the influence of the transmittance distribution that varies along the Z direction can be applied to the incident light beam to the dimming region 7f as desired. In the unit region 7eb on the first exit refracting surface 7ab, the optical surface of the central region along the Z direction is substantially parallel to the XZ plane orthogonal to the optical axis AX, but the optical surface of the peripheral region along the Z direction. Is relatively inclined with respect to the XZ plane.

  Therefore, due to the influence of the inclination of the optical surface with respect to the XZ plane, the light-shielding dots having the required size and shape are arranged in the required arrangement density distribution in the peripheral region along the Z direction of the unit region 7eb on the first exit refracting surface 7ab. Therefore, it may be difficult to form. In this case, instead of forming a light-shielding dot in the peripheral region along the Z direction of the unit region 7eb on the first exit refracting surface 7ab, a cylindrical surface having a curvature only in the X direction without a curvature in the Z direction. In the second incident refracting surface 7ba, a complementary light shielding dot may be formed in a region corresponding to the peripheral region described above. If necessary, a dimming region can be provided in parallel not only on the first exit refracting surface 7ab but also on the second exit refracting surface 7bb.

  In the above-described embodiment, the dimming region 7f is configured by distributing and forming a plurality of light-shielding dots made of, for example, chromium or chromium oxide in the unit region 7eb. However, without being limited to the light-shielding dots that block the incident light, for example, the light-reducing area can also be configured using a plurality of light-scattering dots whose arrangement density distribution changes according to a predetermined transmittance distribution. In general, the light-scattering dots are formed by subjecting a required area of the optical surface to a roughening process. In addition, the dimming region can be configured by using a thin film (for example, a thin film made of chromium or chromium oxide) whose thickness changes according to a predetermined transmittance distribution.

  In the above-described embodiment, the first fly eye member (first optical member) 7a and the second fly eye member (second optical member) 7b constituting the cylindrical micro fly's eye lens 7 are adjacent to each other. However, the present invention is not limited to this, and some optical member (for example, a filter) may be interposed between the first optical member and the second optical member constituting the optical integrator.

  Further, in the above-described embodiment, light incident on the central position along the Y direction in the rectangular illumination area formed on the wafer W passes through the central position along the Z direction in the dimming area 7f, and the illumination area The light incident on the peripheral position along the Y direction passes through the peripheral position along the Z direction in the dimming region 7f. Therefore, the intensity of the pupil intensity distribution regarding each point along the Y direction in the illumination area can be adjusted by the action of the transmittance distribution in the Z direction given to the dimming area 7f.

  Further, in the above-described embodiment, as shown in FIG. 8, for example, in the annular illumination, a region where the light that forms the annular pupil intensity distribution 81 passes through the first exit refracting surface 7ab, and the circular illumination with a small σ value. In this case, the light forming the small circular pupil intensity distribution 82 is different from the region where the light passes through the first exit refracting surface 7ab (not coincident with each other). Accordingly, by appropriately selecting the pattern of the dimming area 7f provided on the first exit refracting surface 7ab (and the number, position, etc. of the dimming area 7f) as appropriate, the illumination intensity is increased according to the size or shape of the pupil intensity distribution. The intensity of the pupil intensity distribution can also be adjusted according to changes in conditions.

  In the cylindrical micro fly's eye lens 7 according to the above-described embodiment, the plurality of cylindrical incident refracting surfaces 7aa of the first fly eye member 7a and the plurality of cylindrical incident refracting surfaces 7ba of the second fly eye member 7b are used. Are arranged along the X direction and have a refractive power in the X direction and no refractive power in the Z direction. The plurality of cylindrical exit refracting surfaces 7ab of the first fly's eye member 7a and the plurality of cylindrical exit refracting surfaces 7bb of the second fly's eye member 7b are arranged along the Z direction and are arranged in the Z direction. And has no refractive power in the X direction.

  However, the present invention is not limited to the configuration shown in FIG. 2, and various configurations are possible for the configuration of the optical integrator having a plurality of wavefront division elements arranged two-dimensionally in parallel. For example, a cylindrical micro fly's eye lens 17 having another form as shown in FIG. 9 can be used. As shown in FIG. 9, the cylindrical micro fly's eye lens 17 is composed of a first fly eye member 17a disposed on the light source side and a second fly eye member 17b disposed on the mask side.

  A plurality of cylindrical refractive surfaces (cylindrical lens groups) 17aa and 17ab 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 17a. ing. A plurality of cylindrical refracting surfaces (cylindrical lens groups) 17ba and 17bb 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 17b at a pitch p2 (p2>). p1).

  Focusing on the refractive action in the X direction of the cylindrical micro fly's eye lens 17 (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 17a. Corresponding in a group of refracting surfaces 17ab formed on the mask side of the first fly's eye member 17a after being wavefront divided by the refracting surface 17aa along the X direction at a pitch p1 and receiving a light condensing action on the refracting surface. The light is focused on the refracting surface and focused on the rear focal plane of the cylindrical micro fly's eye lens 17.

  Focusing on the refractive action in the Z direction of the cylindrical micro fly's eye lens 17 (that is, the refractive action in the YZ plane), a group of parallel light beams incident along the optical axis AX are formed on the light source side of the second fly's eye member 17b. Corresponding in the group of refracting surfaces 17bb formed on the mask side of the second fly's eye member 17b after the wavefront is divided at the pitch p2 along the Z direction by the refracting surface 17ba of the second flyeye member 17b The light is focused on the refracting surface and focused on the rear focal plane of the cylindrical micro fly's eye lens 17.

  Thus, the cylindrical micro fly's eye lens 17 is composed of the first fly eye member 17a and the second fly eye member 17b in which the cylindrical lens groups are arranged on both sides, and has a size of p1 in the X direction. It has a large number of rectangular microscopic refracting surfaces (unit wavefront dividing surfaces) having a size of p2 in the direction. In other words, the cylindrical micro fly's eye lens 17 is configured by two-dimensionally arranging a number of wavefront division elements having a rectangular cross section having an X-direction dimension of p1 and a Z-direction dimension of p2 along the XZ plane. It is an optical integrator.

  Each wavefront dividing element constituting the cylindrical micro fly's eye lens 17 has a rectangular wavefront dividing surface having a short side along the X direction and a long side along the Z direction. In the cylindrical micro fly's eye lens 17 in FIG. 9, the plurality of cylindrical incident refracting surfaces 17aa and the plurality of cylindrical exit refracting surfaces 17ab of the first fly eye member 17a are arranged along the X direction, It has refractive power in the X direction and no refractive power in the Z direction. Further, the plurality of cylindrical incident refracting surfaces 17ba and the plurality of cylindrical exit refracting surfaces 17bb of the second fly's eye member 17b are arranged along the Z direction and have a refractive power in the Z direction. No refractive power in the X direction.

  That is, the cylindrical micro fly's eye lens 17 includes a first fly's eye member (first optical member) 17a and a second fly's eye member (second optical member) 17b disposed adjacent to the rear side. . The first fly's eye member 17a includes a plurality of cylindrical incident first refractive surfaces 17aa formed side by side in the X direction and a plurality of cylindrical first emission refractive surfaces 17ab formed side by side in the X direction. Have The second fly's eye member 17b includes a plurality of cylindrical second incident refracting surfaces 17ba formed side by side in the Z direction, and a plurality of cylindrical second emission refracting surfaces 17bb formed side by side in the Z direction. Have

  When the cylindrical micro fly's eye lens 17 of FIG. 9 is used, one or a plurality of second incident surfaces 17ba formed on the incident side of the second fly's eye member 17b correspond to the incident surfaces of the wavefront dividing elements. By providing the unit region with a dimming region having a transmittance distribution that changes one-dimensionally along the Z direction, it is possible to obtain the same effect as that of the above-described embodiment. If necessary, a complementary dimming region can be provided on the first exit refracting surface 17ab, or a dimming region can be provided in parallel on the second exit refracting surface 17bb.

  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. Thus, the present invention can be applied as necessary.

  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 No. 2004-304135, International Patent Publication No. 2006/080285 pamphlet and US Patent Publication No. 2007/0296936 corresponding thereto. 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. Here, the teachings of US Patent Publication No. 2007/0296936 are incorporated by reference.

  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. 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 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 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 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 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, 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.

  In the above-described embodiment, a so-called polarization illumination method disclosed in US Publication Nos. 2006/0170901 and 2007/0146676 can be applied. Here, the teachings of US Patent Publication No. 2006/0170901 and US Patent Publication No. 2007/0146676 are incorporated by reference.

  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.

DESCRIPTION OF SYMBOLS 1 Light source 3 Diffractive optical element 4 Afocal lens 6 Zoom lens 7 Cylindrical micro fly's eye lens 8 Condenser optical system 9 Mask blind 10 Imaging optical system M Mask PL Projection optical system AS Aperture stop W Wafer

Claims (20)

In an optical integrator having a plurality of wavefront splitting elements arranged two-dimensionally in parallel,
A first optical member having a plurality of cylindrical first incident refractive surfaces formed side by side in one direction and a plurality of cylindrical first emission refractive surfaces formed side by side in one direction;
A plurality of cylindrical incident second refracting surfaces arranged in one direction and arranged in the rear side of the first optical member, and a plurality of cylindrical second surfaces formed in one direction. A second optical member having an exit refractive surface,
An optical integrator, wherein a dimming region having a predetermined transmittance distribution is provided on at least one of the plurality of refractive surfaces. The dimming area is provided on at least one of the plurality of first exit refracting surfaces, the plurality of second entrance refracting surfaces, and the plurality of second exit refracting surfaces. The optical integrator according to claim 1. 3. The wavefront dividing element has a rectangular wavefront dividing surface having a short side along a first direction and a long side along a second direction intersecting the first direction. Optical integrator described in 1. The optical integrator according to claim 3, wherein the dimming region has a transmittance distribution that varies along the second direction. The plurality of cylindrical first incident refractive surfaces and the plurality of cylindrical second incident refractive surfaces are arranged along the first direction, have a refractive power in the first direction, and No refractive power in the second direction,
The plurality of cylindrical surface-shaped first exit refracting surfaces and the plurality of cylindrical surface-shaped second exit refracting surfaces are arranged along the second direction, have a refractive power in the second direction, and 5. The optical integrator according to claim 3, wherein the optical integrator has no refractive power in the first direction. 6. The optical integrator according to claim 5, wherein the dimming region is provided on at least one refracting surface of the plurality of first exit refracting surfaces. The dimming region is provided on at least one refracting surface of the plurality of first exit refracting surfaces and at least one refracting surface of the plurality of second incident refracting surfaces. The optical integrator according to claim 5 or 6. The plurality of cylindrical surface-shaped first incident refracting surfaces and the plurality of cylindrical surface-shaped first exit refracting surfaces are arranged along the first direction and have refractive power in the first direction, and No refractive power in the second direction,
The plurality of cylindrical second incident refracting surfaces and the plurality of cylindrical second refracting surfaces are arranged along the second direction and have refractive power in the second direction, and 5. The optical integrator according to claim 3, wherein the optical integrator has no refractive power in the first direction. The optical integrator according to claim 8, wherein the dimming region is provided on at least one of the plurality of second incident refracting surfaces. The dimming region is provided on at least one refracting surface of the plurality of second incident refracting surfaces and at least one refracting surface of the plurality of first exit refracting surfaces. The optical integrator according to claim 8 or 9. The optical integrator according to any one of claims 1 to 10, wherein the first optical member and the second optical member are adjacent to each other. The optical integrator according to claim 1, wherein the dimming region has a plurality of light-shielding dots whose arrangement density distribution changes according to the predetermined transmittance distribution. The optical integrator according to any one of claims 1 to 11, wherein the dimming region includes a plurality of light scattering dots whose arrangement density distribution changes according to the predetermined transmittance distribution. The optical integrator according to any one of claims 1 to 11, wherein the dimming region includes a thin film whose thickness varies according to the predetermined transmittance distribution. In the illumination optical system that illuminates the illuminated surface with light from the light source,
The optical integrator according to any one of claims 1 to 14,
An illumination optical system comprising: a distribution forming optical system that forms a pupil intensity distribution in an illumination pupil behind the optical integrator. 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. 15. The illumination optical system according to 15. 17. An exposure apparatus comprising the illumination optical system according to claim 15 or 16 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. A projection optical system for forming an image of the predetermined pattern on the photosensitive substrate; and moving the predetermined pattern and the photosensitive substrate relative to the projection optical system along a scanning direction to The exposure apparatus according to claim 17, wherein the pattern is exposed by projection onto the photosensitive substrate. 19. The optical integrator according to claim 17, wherein the optical integrator has a rectangular unit wavefront dividing surface that is elongated along a predetermined direction, and the predetermined direction corresponds to a direction orthogonal to the scanning direction. Exposure device. An exposure step of exposing the predetermined pattern to the photosensitive substrate using the exposure apparatus according to any one of claims 17 to 19,
Developing the photosensitive substrate to which the predetermined pattern is transferred, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

Images