JP2012028543A - Illumination optical system, exposure device, and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an illumination optical system capable of forming a pupil intensity distribution having a form close to a surface light source with a high filling rate.SOLUTION: The illumination optical system for illuminating a surface to be irradiated with light from a light source includes: a spatial light modulator which has a plurality of optical elements arrayed along a prescribed surface and controlled individually, and forms a prescribed light intensity distribution, corresponding to the pupil intensity distribution to be formed in an illumination pupil of the illumination optical system, on a first surface; an imaging optical system which is disposed in an optical path between the spatial light modulator and the surface to be irradiated, and forms a second surface optically conjugate to the first surface; and an angular distribution imparting element which is disposed in an optical path between the spatial light modulator and the imaging optical system, and imparts the angular distribution of a range larger than the range of the angular distribution of an incident luminous flux to an emission luminous flux.

Description

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

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

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

  Conventionally, there has been proposed an illumination optical system capable of continuously changing the pupil intensity distribution (and thus the illumination condition) without using a zoom optical system (see Patent Document 1). In the illumination optical system disclosed in Patent Document 1, an incident light beam is generated using a movable multi-mirror configured by a large number of minute mirror elements that are arranged in an array and whose tilt angle and tilt direction are individually driven and controlled. By dividing and deflecting into minute units for each reflecting surface, the cross section of the light beam is converted into a desired shape or a desired size, and thus a desired pupil intensity distribution is realized.

US Patent Application Publication No. 2009/0116093

  In the illumination optical system described in Patent Document 1, since a spatial light modulator having a large number of mirror elements whose postures are individually controlled is used, the degree of freedom in changing the shape and size of the pupil intensity distribution is high. . However, the pupil intensity distribution formed on the illumination pupil immediately after the fly-eye lens is composed of a set of point-like small light sources, and the filling rate of the small light sources occupying the entire area of the pupil intensity distribution (hereinafter simply referred to as “pupil intensity distribution "Filling rate" or "filling rate") is low. In order to perform good exposure under desired illumination conditions, it is required to increase the filling rate of the pupil intensity distribution to form a pupil intensity distribution having a form close to a surface light source.

  The present invention has been made in view of the above-described problems, and an object thereof is to provide an illumination optical system that can form a pupil intensity distribution having a high filling rate and a form close to a surface light source. The present invention also provides an exposure apparatus capable of performing good exposure under desired illumination conditions using an illumination optical system that forms a pupil intensity distribution having a form that is close to a surface light source with a high filling factor. The purpose is to provide.

In order to solve the above problems, in the first embodiment of the present invention, in the illumination optical system that illuminates the illuminated surface with light from the light source,
A plurality of optical elements arranged along a predetermined surface and individually controlled, and a predetermined light intensity distribution corresponding to a pupil intensity distribution to be formed on the illumination pupil of the illumination optical system is formed on the first surface A spatial light modulator;
An imaging optical system disposed in an optical path between the spatial light modulator and the irradiated surface to form a second surface optically conjugate with the first surface;
An angle distribution providing element that is disposed in an optical path between the spatial light modulator and the imaging optical system and applies an angular distribution in a range larger than the angular distribution range of the incident light beam to the emitted light beam. An illumination optical system is provided.

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 plurality of optical elements arranged along a predetermined surface and individually controlled, and a predetermined light intensity distribution corresponding to a pupil intensity distribution to be formed on the illumination pupil of the illumination optical system is formed on the first surface A spatial light modulator;
An imaging optical system disposed in an optical path between the spatial light modulator and the irradiated surface and forming a second surface optically conjugate with the first surface;
An illumination optical system is provided in which an optical member having power is not disposed in an optical path between the spatial light modulator and the first surface.

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

In the fourth embodiment of the present invention, using the exposure apparatus of the third embodiment, exposing the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate having the predetermined pattern transferred thereon, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
And processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method is provided.

  With the illumination optical system of the present invention, it is possible to form a pupil intensity distribution having a high filling rate and a form close to a surface light source. 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 forms a pupil intensity distribution having a high filling rate and a shape close to that of a surface light source. 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 figure which shows schematically the internal structure of the spatial light modulation unit of FIG. It is a figure which shows roughly the structure and effect | action of a spatial light modulator. It is a fragmentary perspective view of a spatial light modulator. It is a 1st figure explaining that the filling rate of pupil intensity distribution will become low if a diffractive optical element is not interposed. It is a 2nd figure explaining that the filling rate of a pupil intensity distribution will become low if a diffractive optical element is not interposed. It is a 1st figure explaining that the filling rate of pupil intensity distribution becomes high by the effect | action of a diffractive optical element in this embodiment. It is a 2nd figure explaining that the filling rate of pupil intensity distribution becomes high by the effect | action of a diffractive optical element in this embodiment. It is a figure which shows the modification which forms a pair of rectangular small light source in each unit area | region of an illumination pupil. It is a figure which shows the modification which forms the single rectangular small light source in each unit area | region of an illumination pupil. 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. FIG. 2 is a diagram schematically showing the internal configuration of the spatial light modulation unit of FIG. 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 enters the micro fly's eye lens (or fly eye lens) 4 through the beam transmission unit 2 and the spatial light modulation unit 3. The beam transmitter 2 guides the incident light beam from the light source 1 to the spatial light modulation unit 3 while converting the incident light beam into a light beam having an appropriate size and shape, and changes the position of the light beam incident on the spatial light modulation unit 3. And a function of actively correcting the angular variation.

  As shown in FIG. 2, the spatial light modulation unit 3 includes a pair of spatial light modulators 31 and 32 arranged in parallel in the illumination optical path. The spatial light modulators 31 and 32 have a plurality of mirror elements that are two-dimensionally arranged and individually controlled. A beam splitting member 33 is disposed in the optical path between the beam transmitter 2 and the spatial light modulators 31 and 32, and diffraction is performed in the optical path between the spatial light modulators 31 and 32 and the micro fly's eye lens 4. An optical element 34 and an imaging optical system 35 are disposed.

  The light beam dividing member 33 divides the incident light beam from the light source 1 into two light beams having different directions, guides the first light beam to the first spatial light modulator 31, and directs the second light beam to the second space. Guide to the light modulator 32. The light that has passed through the spatial light modulators 31 and 32 is guided to the micro fly's eye lens 4 via the diffractive optical element 34 and the imaging optical system 35. A required light intensity distribution is variably formed on the incident surface 4 a of the micro fly's eye lens 4 in accordance with the modulation action of the spatial light modulators 31 and 32. The specific configuration and operation of the spatial light modulation unit 3 will be described later.

  The micro fly's eye lens 4 is, for example, an optical element made up of a large number of micro lenses having positive refractive power arranged vertically and horizontally and densely. The micro fly's eye lens 4 is formed by etching a parallel plane plate to form a micro lens group. Has been. In a micro fly's eye lens, unlike a fly eye lens composed of lens elements isolated from each other, a large number of micro lenses (micro refractive surfaces) are integrally formed without being isolated from each other. However, the micro fly's eye lens is the same wavefront division type optical integrator as the fly eye lens in that the minute refractive surfaces are arranged vertically and horizontally.

  The rectangular micro-refractive surface as the unit wavefront dividing surface in the micro fly's eye lens 4 is a rectangular shape elongated in the Z direction, that is, the shape of the illumination field to be formed on the mask M (and thus the exposure region to be formed on the wafer W). It is a rectangular shape similar to As the micro fly's eye lens 4, for example, a cylindrical micro fly's eye lens can be used. The configuration and action of the cylindrical micro fly's eye lens are disclosed in, for example, US Pat. No. 6,913,373.

  The light beam incident on the micro fly's eye lens 4 is two-dimensionally divided by a large number of microlenses, and light having the same property as the light intensity distribution formed on the incident surface 4a is formed on the rear focal plane or in the vicinity of the illumination pupil. A secondary light source (pupil intensity distribution) having an intensity distribution is formed. The light beam from the secondary light source formed on the illumination pupil immediately after the micro fly's eye lens 4 enters an illumination aperture stop (not shown). The illumination aperture stop is disposed on the rear focal plane of the micro fly's eye lens 4 or in the vicinity thereof, and has an opening (light transmission part) having a shape corresponding to the secondary light source.

  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 a method for switching the illumination aperture stop, for example, a 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 installation of the illumination aperture stop can also be omitted.

  Light from the secondary light source limited by the illumination aperture stop illuminates the mask blind 6 having a rectangular opening (light transmission portion) elongated in the Z direction via the condenser optical system 5 in a superimposed manner. Thus, a rectangular illumination field corresponding to the shape and focal length of the rectangular minute refractive surface (unit wavefront dividing surface) of the micro fly's eye lens 4 is formed on the mask blind 6 as an illumination field stop. The light flux that has passed through the opening of the mask blind 6 receives the light condensing action of the illumination imaging optical system 7 and then illuminates the mask M on which a predetermined pattern is formed in a superimposed manner. That is, the illumination imaging optical system 7 forms an image of the rectangular opening of the mask blind 6 on the mask M.

  A pattern to be transferred is formed on the mask M held on the mask stage MS, and is in the Y direction (corresponding to the Z direction on the incident surface 4a of the micro fly's eye lens 4 and the mask blind 6) in the entire pattern area. A rectangular (slit-shaped) pattern region having a long side along the X direction and a short side along the X direction 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 step-and-scan method, the mask stage MS and the wafer stage WS are extended along the X direction (scanning direction) in the plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL. 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 a length corresponding to the scanning amount (movement amount) of the wafer W. A mask pattern is scanned and exposed to the upper one shot area (exposure area). The pattern of the mask M is sequentially transferred to each shot area of the wafer W by repeating scanning exposure while moving the wafer stage WS two-dimensionally along the XY plane.

  The exposure apparatus according to the present embodiment includes a pupil intensity distribution measurement unit DT that measures the pupil intensity distribution on the pupil plane of the projection optical system PL based on light via the projection optical system PL, and a measurement result of the pupil intensity distribution measurement unit DT. And a control unit CR for controlling the spatial light modulation unit 3 based on the above. The pupil intensity distribution measurement unit DT includes, for example, a CCD image pickup unit having an image pickup surface disposed at a position optically conjugate with the pupil position of the projection optical system PL, and the pupil intensity relating to each point on the image plane of the projection optical system PL. The distribution (pupil intensity distribution formed at the pupil position of the projection optical system PL by the light incident on each point) is monitored. For the detailed configuration and operation of the pupil intensity distribution measuring unit DT, reference can be made to, for example, US Patent Publication No. 2008/0030707.

  In this embodiment, the secondary light source formed by the micro fly's eye lens 4 is used as a light source, and the mask M (and thus the wafer W) disposed on the irradiated surface of the illumination optical system 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 can be called the illumination pupil plane of the illumination optical system. 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 or a plane optically conjugate with the illumination pupil plane. When the number of wavefront divisions by the micro fly's eye lens 4 is relatively large, the overall light intensity distribution formed on the incident surface 4a of the micro fly's eye lens 4 and the overall light intensity distribution (pupil intensity) of the entire secondary light source. Distribution) shows a high correlation. For this reason, the light intensity distribution on the incident surface 4a of the micro fly's eye lens 4 and a surface optically conjugate with the incident surface 4a can also be referred to as a pupil intensity distribution.

  Next, the internal configuration and operation of the spatial light modulation unit 3 will be specifically described. The light beam splitting member 33 is formed of an optical material such as fluorite or quartz, and has the form of a triangular prism prism mirror extending in the X direction. The light beam splitting member 33 has a pair of reflecting surfaces 33a and 33b facing the light source side (left side in FIG. 2), and the ridge line between the reflecting surfaces 33a and 33b extends in the X direction through the optical axis AX. The light beam splitting member 33 can also be formed by providing a reflective film made of aluminum, silver, or the like on the side surface of a triangular prism-shaped member made of a non-optical material such as metal. Alternatively, the light beam splitting member 33 can be formed as a mirror.

  The light beam incident on the spatial light modulation unit 3 along the optical axis AX is divided into two by the two reflecting surfaces 33 a and 33 b of the light beam dividing member 33. The light beam reflected by the reflecting surface 33 a enters the spatial light modulator 31, and the light beam reflected by the reflecting surface 33 b enters the spatial light modulator 32. The light modulated by the spatial light modulator 31 and the light modulated by the spatial light modulator 32 form a required light intensity distribution on the first surface IP1 orthogonal to the optical axis AX, for example. In the optical path between the spatial light modulators 31 and 32 and the first surface IP1, there is no optical member (lens, curved reflector, etc.) having power.

  The diffractive optical element 34 is arranged so that its diffractive optical surface substantially coincides with the first surface IP1, and imparts an angle distribution in a range larger than the angle distribution range of the incident light beam to the emitted light beam. The imaging optical system 35 has a magnification, for example, and forms a second surface IP2 optically conjugate with the first surface IP1. The micro fly's eye lens 4 is disposed so that its incident surface 4a substantially coincides with the second surface IP2.

  Hereinafter, in order to simplify the description, it is assumed that the spatial light modulation unit 3 has a symmetric configuration with respect to a plane including the optical axis AX and parallel to the XY plane. That is, the spatial light modulators 31 and 32 have the same configuration and are arranged symmetrically with respect to a plane including the optical axis AX and parallel to the XY plane. In other words, the spatial light modulators 31 and 32 are arranged at an interval in the Z direction (corresponding to the long side direction of the rectangular unit wavefront dividing surface of the micro fly's eye lens 4) across the optical axis AX. It shall be. Similarly, it is assumed that the reflection surface 33a and the reflection surface 33b of the light beam splitting member 33 are arranged symmetrically with respect to a plane including the optical axis AX and parallel to the XY plane.

  As shown in FIG. 3, the spatial light modulator 31 (32) includes a plurality of mirror elements 31a (32a) and a plurality of mirror elements 31a (32a) arranged two-dimensionally along a predetermined surface (array surface). ) Holding the base 31b (32b) and a drive unit 31c (32c) for individually controlling and driving the posture of the plurality of mirror elements 31a (32a) via a cable (not shown) connected to the base 31b (32b). And. In the spatial light modulator 31 (32), the posture of the plurality of mirror elements 31a (32a) is changed by the action of the drive unit 31c (32c) that operates based on the control signal from the control unit CR, and each mirror element 31a (32a) is set in a predetermined direction.

  The spatial light modulator 31 (32) emits the incident light after applying spatial modulation according to the incident position. As shown in FIG. 4, the spatial light modulator 31 (32) includes a plurality of minute mirror elements (optical elements) 31 a (32 a) arranged two-dimensionally within a predetermined plane. For ease of explanation and illustration, FIGS. 3 and 4 show a configuration example in which the spatial light modulator 31 (32) includes 4 × 4 = 16 mirror elements 31a (32a). Comprises much more than 16 mirror elements 31a (32a).

  Referring to FIG. 3, among the light beams that enter the spatial light modulator 31 (32) through the reflecting surface 33 a (33 b) of the light beam splitting member 33, the light beam L 1 is a mirror of the plurality of mirror elements 31 a (32 a). The light beam L2 is incident on the element SEa to a mirror element SEb different from the mirror element SEa. Similarly, the light beam L3 is incident on a mirror element SEc different from the mirror elements SEa and SEb, and the light beam L4 is incident on a mirror element SEd different from the mirror elements SEa to SEc. The mirror elements SEa to SEd give spatial modulations set according to their positions to the lights L1 to L4.

  The light reflected by the plurality of mirror elements SEa to SEd of the spatial light modulator 31 (32) and given a predetermined angular distribution forms a predetermined light intensity distribution on the first surface IP1. The light having a predetermined light intensity distribution formed on the first surface IP1 passes through the diffractive optical element 34 and the imaging optical system 35 to the second surface IP2, and further to the incident surface 4a of the micro fly's eye lens 4. A light intensity distribution having the same properties as the light intensity distribution on the surface IP1 is formed.

  Thus, the light intensity distribution (pupil intensity distribution) formed on the illumination pupil immediately after the micro fly's eye lens 4 is the same as the first light intensity distribution formed on the first surface IP1 by the spatial light modulator 31 and the spatial light modulation. The distribution corresponds to the combined distribution with the second light intensity distribution formed on the first surface IP1 by the device 32. In other words, the spatial light modulators 31 and 32 form a predetermined light intensity distribution corresponding to the pupil intensity distribution to be formed on the illumination pupil immediately after the micro fly's eye lens 4 on the first surface IP1.

  As shown in FIG. 4, the spatial light modulator 31 (32) has a large number of minute reflections regularly and two-dimensionally arranged along one plane with a planar reflection surface as an upper surface. This is a movable multi-mirror including a mirror element 31a (32a) as an element. Each mirror element 31a (32a) is movable, and the inclination of the reflection surface, that is, the inclination angle and the inclination direction of the reflection surface are independently determined by the action of the drive unit 31c (32c) that operates according to a command from the control unit CR. Be controlled. Each mirror element 31a (32a) is continuously or discretely by a desired rotation angle with two directions parallel to the reflecting surface and orthogonal to each other (for example, the X direction and its orthogonal direction) as the rotation axis. Can rotate. That is, it is possible to two-dimensionally control the inclination of the reflecting surface of each mirror element 31a (32a).

  In addition, when rotating the reflective surface of each mirror element 31a (32a) discretely, a rotation angle is made into several states (for example, ..., -2.5 degree, -2.0 degree, ... 0 degree). , +0.5 degrees,... +2.5 degrees,. Although FIG. 4 shows a mirror element 31a (32a) having a square outer shape, the outer shape of the mirror element 31a (32a) is not limited to a square. However, from the viewpoint of light utilization efficiency, it is possible to have a shape that can be arranged so that the gap between the mirror elements 31a (32a) is small (a shape that can be packed most closely). Further, from the viewpoint of light utilization efficiency, the interval between two adjacent mirror elements 31a (32a) can be minimized.

  In the present embodiment, as the spatial light modulators 31 and 32, for example, spatial light modulators that continuously change the directions of a plurality of mirror elements 31a and 32a arranged two-dimensionally are used. As such a spatial light modulator, for example, Japanese Patent Laid-Open No. 10-503300 and European Patent Publication No. 779530 corresponding thereto, Japanese Patent Application Laid-Open No. 2004-78136 and corresponding US Pat. No. 6,900, The spatial light modulator disclosed in Japanese Patent No. 915, Japanese National Publication No. 2006-524349 and US Pat. No. 7,095,546 corresponding thereto and Japanese Patent Application Laid-Open No. 2006-113437 can be used. Note that the directions of the plurality of mirror elements 31a and 32a arranged two-dimensionally may be controlled so as to have a plurality of discrete stages.

  In the spatial light modulators 31 and 32, the postures of the plurality of mirror elements 31a and 32a are changed by the action of the drive units 31c and 32c that operate according to the control signal from the control unit CR, and the respective mirror elements 31a and 32a are changed. Are set in a predetermined direction. The light reflected by the plurality of mirror elements 31a and 32a of the spatial light modulators 31 and 32 at a predetermined angle is reflected on the incident surface 4a of the micro fly's eye lens 4 in a desired shape (circular, ring-shaped, multiple poles). Shape) and size of light intensity distribution.

  Thus, the light that has passed through the pair of spatial light modulators 31 and 32 forms a pupil intensity distribution corresponding to the light intensity distribution at the entrance plane 4a on the rear focal plane of the micro fly's eye lens 4 or in the vicinity of the illumination pupil. To do. Furthermore, the position of another illumination pupil optically conjugate with the illumination pupil immediately after the micro fly's eye lens 4, that is, the pupil position of the illumination imaging optical system 7 and the pupil position of the projection optical system PL (aperture stop AS is disposed). The pupil intensity distribution corresponding to the light intensity distribution on the incident surface 4a is also formed at the position).

  In the present embodiment, the shape and size of the pupil intensity distribution is freely and quickly changed by the action of the spatial light modulation unit 3 including the spatial light modulators 31 and 32 arranged in parallel, and thus various. Various lighting conditions can be realized. However, if the installation of the diffractive optical element 34 is omitted from the configuration of FIG. 2, the pupil intensity distribution formed on the illumination pupil immediately after the micro fly's eye lens 4 is a set of point-like small light sources, as in the case of the prior art. Therefore, the filling rate of the pupil intensity distribution becomes low.

  The prior art employs a Fourier lens that optically makes a Fourier transform relationship between the spatial light modulator (corresponding to 31 and 32 in FIG. 2) and the incident surface of the micro fly's eye lens (corresponding to 4 in FIG. 2). ing. In this case, in order to increase the filling rate of the pupil intensity distribution formed on the illumination pupil immediately after the micro fly's eye lens (increase the size of each small light source constituting the pupil intensity distribution), the focal length of the Fourier lens is decreased. It is required to do.

  However, in order to configure the light passing through the spatial light modulator to illuminate the entire effective area of the incident surface of the micro fly's eye lens, it is necessary to secure a large focal length of the Fourier lens. For this reason, in the prior art, priority is given to securing the focal length of the Fourier lens to a certain extent, the size of each small light source constituting the pupil intensity distribution is reduced, and the filling rate of the pupil intensity distribution is reduced.

  Hereinafter, in order to facilitate understanding of the fact that the filling factor of the pupil intensity distribution is reduced when the diffractive optical element 34 is not interposed in the present embodiment, parallel light beams are incident on the spatial light modulators 31 and 32 and a plurality of light beams are incident on the spatial light modulators 31 and 32. It is assumed that the mirror elements 31a and 32a are aligned with the arrangement surface, that is, the reflection surfaces of the mirror elements 31a and 32a are aligned in parallel with the arrangement surface. In this case, as shown in FIG. 5, the parallel light beams that have passed through the spatial light modulators 31, 32 are points 41, spaced apart in the Z direction across the optical axis AX, on the pupil plane 35 a of the imaging optical system 35. 42 is condensed.

  The positions of the condensing points 41 and 42 depend on the angle at which the parallel light beams that have passed through the spatial light modulators 31 and 32 enter the imaging optical system 35. The light that has formed the condensing points 41 and 42 via the spatial light modulators 31 and 32 is incident on the micro fly's eye lens 4 and forms a pupil intensity distribution in the illumination pupil immediately thereafter. As shown in FIG. 6, this pupil intensity distribution is composed of a set of point-like small light sources 43, and the filling rate is low. In FIG. 6, a rectangular unit region 44 surrounded by a straight broken line corresponds to the rectangular unit wavefront dividing surface of the micro fly's eye lens 4.

  A pair of point-like small light sources 43 formed at intervals in the Z direction in each unit region 44 is a pair of condensing points 41, 42 spaced at intervals in the Z direction on the pupil plane 35 a of the imaging optical system 35. It corresponds to. This is because the pupil plane 35a of the imaging optical system 35 and the illumination pupil plane immediately after the micro fly's eye lens 4 are optically conjugate. Actually, the light modulated through the spatial light modulators 31 and 32 is not in a parallel light flux state, but the distribution of angular components of incident light to the imaging optical system 35 and the micro fly's eye lens 4 is biased. In addition, the size of the point-like small light source 43 is also reduced.

  In the present embodiment, the diffractive optical element 34 that imparts an angular distribution in a range larger than the angular distribution of the incident light beam to the outgoing light beam is disposed along the first surface IP1. Therefore, as shown in FIG. 7, the parallel light beams that have passed through the spatial light modulators 31 and 32 in the aligned state enter the diffractive optical element 34. Light to which a certain range of angular distribution is given through the diffractive optical element 34 forms light flux areas 51 and 52 spaced in the Z direction across the optical axis AX on the pupil plane 35a of the imaging optical system 35. To do.

  The light beam regions 51 and 52 have outer shapes (circular shape, elliptical shape, rectangular shape, etc.) corresponding to the diffraction characteristics of the diffractive optical element 34. The light that has formed, for example, circular light beam regions 51 and 52 via the spatial light modulators 31 and 32 forms a pupil intensity distribution in the illumination pupil immediately after the micro fly's eye lens 4. As shown in FIG. 8, this pupil intensity distribution is composed of a set of circular small light sources 53, and the filling rate is higher than that of the comparative example shown in FIG. Also in FIG. 8, the rectangular unit region 54 surrounded by the straight broken line corresponds to the rectangular unit wavefront dividing surface of the micro fly's eye lens 4.

  A pair of circular small light sources 53 formed at intervals in the Z direction in each unit region 54 is a pair of circular light beam regions 51 spaced at intervals in the Z direction on the pupil plane 35a of the imaging optical system 35. , 52. Actually, the light passing through the spatial light modulators 31 and 32 is not in a parallel light flux state but has a relatively small angular distribution. The light having a relatively small angular distribution is converted into light having a relatively large angular distribution through the diffractive optical element 34 and enters the micro fly's eye lens 4.

  That is, even if the range of the angular distribution of the light modulated through the spatial light modulators 31 and 32 is relatively small, the angular distribution of the incident light to the imaging optical system 35 is affected by the angular distribution imparting action of the diffractive optical element 34. Since the range becomes relatively large, the distribution of the angular components of the incident light to the micro fly's eye lens 4 is dispersed, and the size of the small light source 53 is also increased. The diffractive optical element 34 does not substantially affect the optical conjugate relationship between the first surface IP1 and the second surface IP2 by the imaging optical system 35.

  Thus, in the present embodiment, the distribution of the angle component of the incident light to the micro fly's eye lens 4 is dispersed by the action of imparting the angle distribution of the diffractive optical element 34. As a result, the size of each small light source 53 constituting the pupil intensity distribution formed in the illumination pupil immediately after that is enlarged according to the dispersion of the distribution of the angular component of the incident light to the micro fly's eye lens 4, and as a result It is possible to increase the filling rate of the intensity distribution and form a pupil intensity distribution having a form close to a surface light source.

  As described above, in the illumination optical system (2 to 7) of the present embodiment, a pupil intensity distribution having a form with a high filling rate and close to a surface light source is formed on the illumination pupil immediately after the micro fly's eye lens 4. Can do. In the exposure apparatus (2 to WS) of the present embodiment, the mask M to be transferred using the illumination optical system (2 to 7) that forms a pupil intensity distribution having a high filling rate and a form close to a surface light source. Good exposure can be performed under desired illumination conditions realized according to the characteristics of the pattern.

  Further, in the present embodiment, the surface shape of the exit surface of the micro fly's eye lens 4 is manufactured by forming a small light source 53 having a relatively large size in each unit region 54 in the illumination pupil immediately after the micro fly's eye lens 4. Illuminance unevenness due to errors can be reduced. In the comparative example of FIG. 6, light reaching each point-like small light source 43 in the illumination pupil immediately after the micro fly's eye lens 4 passes only a relatively small area of each micro refraction surface on the exit side. For this reason, when there is a manufacturing error in the surface shape of each micro-refractive surface on the exit side, the illuminance unevenness is directly affected by the manufacturing error of the relatively small passing region and the mask M or wafer W that is the irradiated surface. Is likely to occur.

  On the other hand, in the present embodiment, the light reaching each circular small light source 53 in the illumination pupil immediately after the micro fly's eye lens 4 passes through a relatively large region of each minute refraction surface on the exit side. In this case, even if there is a manufacturing error in the surface shape of each micro-refractive surface on the exit side, due to the averaging effect of the manufacturing error for each micro area in the relatively large passing area, the mask M or wafer W Occurrence of illuminance unevenness can be kept small.

  Moreover, in this embodiment, the optical member which has power is not arrange | positioned in the optical path between the spatial light modulators 31 and 32 and 1st surface IP1. As a result, the movable angle range of the mirror elements 31a and 32a necessary for forming a desired light intensity distribution on the first surface IP1 can be reduced, and the drive controllability of the spatial light modulators 31 and 32 is improved. To do.

  Further, in the present embodiment, by using the imaging optical system 35 having an enlargement magnification, the external size of the illumination field formed on the incident surface 4a of the micro fly's eye lens 4 is enlarged and the light to the incident surface 4a is increased. Can be narrowed to an appropriate range. However, it is not essential that the imaging optical system has an enlargement magnification, and an imaging optical system having an equal magnification or a reduction magnification can also be used.

  In the above-described embodiment, the diffractive optical element 34 disposed along the first surface IP1 is used as an angle distribution providing element that provides the exit light flux with an angular distribution in a range larger than the angular distribution range of the incident light flux. Used. However, the present invention is not limited to this, and various forms are possible for the specific configuration and arrangement of the angle distribution providing element. For example, the diffractive optical element 34 as an angle distribution imparting element can be disposed at an appropriate position in the optical path between the spatial light modulators 31 and 32 and the imaging optical system 35. An angle distribution imparting element having a form other than the diffractive optical element can also be used.

  In the present embodiment described above, a pair of circular small light sources 53 spaced in the Z direction is formed in each unit region 54 of the illumination pupil immediately after the micro fly's eye lens 4. However, the present invention is not limited to this, and various forms are possible for the outer shape, number, arrangement, and the like of the small light sources formed in each unit region of the illumination pupil. For example, as shown in FIG. 9, a pair of rectangular small light sources 55 spaced in the Z direction can be formed in each unit region 54 of the illumination pupil.

  In the above-described embodiment, the pair of spatial light modulators 31 and 32 are arranged in the Z direction (corresponding to the long side direction of the rectangular unit wavefront dividing surface of the micro fly's eye lens 4) with the optical axis AX interposed therebetween. They are arranged at intervals. However, the present invention is not limited to this, and various forms are possible for the number and arrangement of the spatial light modulators. When the spatial light modulator is arranged alone, a single light flux region is formed on the pupil plane 35 a of the imaging optical system 35. As a result, a single small light source 56 having a predetermined shape (exemplarily rectangular in FIG. 10) is formed in each unit region 54 of the illumination pupil immediately after the micro fly's eye lens 4 as shown in FIG. The

  In the above-described embodiment, a plurality of reflecting surfaces arranged two-dimensionally as the spatial light modulators 31 and 32 having a plurality of mirror elements 31 a and 32 a that are two-dimensionally arranged and individually controlled. The spatial light modulator that can individually control the direction (angle: inclination) is used. However, the present invention is not limited to this. For example, a spatial light modulator that can individually control the height (position) of a plurality of two-dimensionally arranged reflecting surfaces can be used. As such a spatial light modulator, for example, Japanese Patent Application Laid-Open No. 6-281869 and US Pat. No. 5,312,513 corresponding thereto, and Japanese Patent Laid-Open No. 2004-520618 and US Patent corresponding thereto are disclosed. The spatial light modulator disclosed in FIG. 1d of Japanese Patent No. 6,885,493 can be used. In these spatial light modulators, by forming a two-dimensional height distribution, an action similar to that of the diffractive surface can be given to incident light. Note that the spatial light modulator having a plurality of two-dimensionally arranged reflection surfaces described above is disclosed in, for example, Japanese Patent Laid-Open No. 2006-513442 and US Pat. No. 6,891,655 corresponding thereto, or a special table. You may deform | transform according to the indication of 2005-524112 gazette and the US Patent Publication 2005/0095749 corresponding to this.

  In the above-described embodiment, the spatial light modulators 31 and 32 having a plurality of mirror elements 31 a and 32 a arranged along a predetermined plane and individually controlled are used. However, the present invention is not limited to this, and for example, a transmissive spatial light modulator including a plurality of transmissive optical elements arranged along a predetermined plane and individually controlled can be used.

  Further, in the above-described embodiment, for the step-and-scan type exposure apparatus that scans and exposes the mask pattern in each exposure region of the wafer W while moving the mask M and the wafer W relative to the projection optical system PL. The present invention is applied. However, the present invention is not limited to this, and the mask pattern is collectively transferred to the photosensitive substrate while the mask and the photosensitive substrate are stationary, and the photosensitive substrate is sequentially moved stepwise to mask each exposure region. The present invention can also be applied to a step-and-repeat type exposure apparatus that sequentially exposes a pattern.

  In the above-described embodiment, a variable pattern forming apparatus that forms a predetermined pattern based on predetermined electronic data can be used instead of a mask. As the variable pattern forming apparatus, for example, a reflective spatial light modulator such as a DMD (digital micromirror device) including a plurality of reflective 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. 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. 11 is a flowchart showing a manufacturing process of a semiconductor device. As shown in FIG. 11, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a semiconductor device substrate (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the 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. 12 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 12, in the liquid crystal device manufacturing process, a pattern 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, etc.), micromachine, thin film magnetic head, and DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

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

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

  In the above-described embodiment, a so-called polarization illumination method disclosed in US Pat. No. 7,423,731 and US Publication Nos. 2006/0170901 and 2007/0146676 can be applied. . When the technique disclosed in US Pat. No. 7,423,731 is applied to the above-described embodiment, the polarization state switching device of the publication is arranged on the light source side of the spatial light modulation unit 3 in the above-described embodiment. What is necessary is just to arrange | position to the optical path between the light beam splitting member 33 and the spatial light modulators 31 and 32, respectively. In addition, when the technique disclosed in US Publication No. 2006/0170901 is applied to the above-described embodiment, the polarization state converter of the publication is connected to the light source side of the spatial light modulation unit 3 in the above-described embodiment. Arranged in the optical path or in the optical path between the light beam splitting member 33 and the spatial light modulators 31 and 32, the polarization modulator in the above-described embodiment is irradiated from the spatial light modulators 31 and 32. It may be arranged on the side optical path and on the first surface IP1 or the surface optically conjugate with the first surface (for example, the second surface IP2) or in the vicinity of those surfaces, or in the illumination pupil plane or in the vicinity thereof. Here, the teachings of U.S. Patent No. 7,423,731, U.S. Patent Publication No. 2006/0170901 and U.S. 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. The present invention can also be applied to a general illumination optical system that illuminates the irradiation surface.

DESCRIPTION OF SYMBOLS 1 Light source 2 Beam transmission part 3 Spatial light modulation units 31 and 32 Spatial light modulator 33 Light beam splitting member 34 Diffractive optical element 35 Imaging optical system 4 Micro fly eye lens 5 Condenser optical system 6 Mask blind 7 Illumination imaging optical system DT pupil intensity distribution measurement unit CR control unit M mask MS mask stage PL projection optical system W wafer WS wafer stage

Claims (18)

In the illumination optical system that illuminates the illuminated surface with light from the light source,
A plurality of optical elements arranged along a predetermined surface and individually controlled, and a predetermined light intensity distribution corresponding to a pupil intensity distribution to be formed on the illumination pupil of the illumination optical system is formed on the first surface A spatial light modulator;
An imaging optical system disposed in an optical path between the spatial light modulator and the irradiated surface to form a second surface optically conjugate with the first surface;
An angle distribution providing element that is disposed in an optical path between the spatial light modulator and the imaging optical system and applies an angular distribution in a range larger than the angular distribution range of the incident light beam to the emitted light beam. An illumination optical system. 2. The illumination optical system according to claim 1, wherein an optical member having power is not disposed in an optical path between the spatial light modulator and the first surface. The illumination optical system according to claim 1, further comprising a wavefront division type optical integrator having an incident surface along the second surface. The illumination optical system according to claim 3, wherein the illumination pupil is positioned immediately after the optical integrator. 5. The illumination optical system according to claim 3, wherein the optical integrator has a rectangular unit wavefront dividing surface that is elongated along the first direction. 6. The illumination optical system according to claim 1, wherein the angle distribution providing element includes a diffractive optical element. The illumination optical system according to claim 6, wherein the diffractive optical element is disposed along the first surface. 8. The spatial light modulator according to claim 1, further comprising: a plurality of mirror elements arranged two-dimensionally; and a drive unit that individually controls and drives the postures of the plurality of mirror elements. The illumination optical system according to claim 1. The illumination optical system according to claim 8, wherein the driving unit changes the directions of the plurality of mirror elements continuously or discretely. A plurality of the spatial light modulators;
The incident light beam is divided into a plurality of light beams having different directions, the first light beam among the plurality of light beams is guided to the first spatial light modulator, and the second light beam is guided to the second spatial light modulator. The illumination optical system according to claim 1, further comprising a light beam splitting member. The first spatial light modulator and the second spatial light modulator are arranged at an interval in the first direction across an optical axis of the imaging optical system. Item 11. The illumination optical system according to Item 10. 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. The illumination optical system according to any one of 1 to 11. In the illumination optical system that illuminates the illuminated surface with light from the light source,
A plurality of optical elements arranged along a predetermined surface and individually controlled, and a predetermined light intensity distribution corresponding to a pupil intensity distribution to be formed on the illumination pupil of the illumination optical system is formed on the first surface A spatial light modulator;
An imaging optical system disposed in an optical path between the spatial light modulator and the irradiated surface and forming a second surface optically conjugate with the first surface;
An illumination optical system, wherein an optical member having power is not disposed in an optical path between the spatial light modulator and the first surface. An angle distribution providing element that is disposed in an optical path between the spatial light modulator and the imaging optical system and applies an angle distribution in a range larger than the angle distribution range of the incident light beam to the emitted light beam is provided. The illumination optical system according to claim 13. 15. An exposure apparatus comprising the illumination optical system according to claim 1 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. The projection optical system for forming the image of the predetermined pattern on the photosensitive substrate, wherein the illumination pupil is at a position optically conjugate with an aperture stop of the projection optical system. The exposure apparatus described. An optical integrator having a plurality of rectangular unit wavefront dividing surfaces elongated in the first direction along the second surface;
The predetermined pattern and the photosensitive substrate are moved relative to the projection optical system along a scanning direction corresponding to a second direction orthogonal to the first direction, and the predetermined pattern is moved to the photosensitive substrate. The exposure apparatus according to claim 16, wherein projection exposure is performed. Using the exposure apparatus according to any one of claims 15 to 17, exposing the predetermined pattern to the photosensitive substrate;
Developing the photosensitive substrate having the predetermined pattern transferred thereon, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
Processing the surface of the photosensitive substrate through the mask layer. A device manufacturing method comprising:

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