JP2010087389A - Illumination optical system, aligner, and method for manufacturing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve lighting conditions rich in diversity as to a shape of pupil intensity distribution and a polarization state. <P>SOLUTION: An illumination optical system which illuminates faces M, W to be illuminated based on light from a light source LS includes: a spatial light modulator 3 having a plurality of optical elements which are two-dimensionally arranged and individually controlled; distribution forming optical systems 4, 5a, 5b, 6a, 5c, and 7 forming the pupil intensity distribution in an illumination pupil based on light passing through the spatial light modulator. The distribution forming optical systems have elements for altering the polarization state which are configurably arranged in at least one conjugated area of a first conjugate area which is optically substantially conjugated with a first area of arrangement faces of the plurality of optical elements and a second conjugate area which is optically substantially conjugated with a second area of the arrangement faces, and alter the polarization state of light incident in the one conjugated area for emission. <P>COPYRIGHT: (C)2010,JPO&INPIT

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 light beam emitted from a light source is passed through a fly-eye lens as an optical integrator, and a secondary light source (generally an illumination pupil) as a substantial surface light source composed of a number of light sources. 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 beam 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 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 integrated, and it is indispensable to obtain a uniform illumination 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 performing modified illumination such as annular illumination and multipolar illumination (bipolar illumination, quadrupole illumination, etc.) using a plurality of replaceable diffractive optical elements (patent) Reference 1). In the illumination optical system disclosed in Patent Document 1, for example, a diffractive optical element for annular illumination that forms an annular pupil intensity distribution in a fixed manner, pupil intensity of a plurality of poles (bipolar, quadrupole, etc.) By setting one diffractive optical element selected from diffractive optical elements for multipole illumination that forms a fixed distribution in the illumination optical path, the pupil intensity distribution (and thus the illumination condition) can be discretely changed. Yes.

US Pat. No. 6,913,373

  In the illumination optical system described in Patent Document 1, a relatively large number of diffractive optical elements having different characteristics are prepared, and these diffractive optical elements are connected to the illumination optical path in order to increase the degree of freedom regarding the change in the shape of the pupil intensity distribution. It is necessary to switch to In an actual illumination optical system, the number of exchangeable diffractive optical elements is limited, and it is difficult to realize illumination conditions rich in diversity with respect to the shape of the pupil intensity distribution. In order to increase the contrast of the pattern image formed on the wafer, it is required to increase the degree of freedom not only in the shape of the pupil intensity distribution but also in the polarization state.

  The present invention has been made in view of the above-described problems, and an object of the present invention is to provide an illumination optical system capable of realizing a wide variety of illumination conditions regarding the shape and polarization state of the pupil intensity distribution. In addition, the present invention provides an appropriate illumination realized according to the characteristics of the pattern to be transferred, using an illumination optical system capable of realizing a variety of illumination conditions for the shape and polarization state of the pupil intensity distribution. An object of the present invention is to provide an exposure apparatus capable of performing good exposure under conditions.

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 based on the light from the light source,
A spatial light modulator having a plurality of optical elements arranged two-dimensionally and individually controlled;
A distribution forming optical system that forms a pupil intensity distribution in the illumination pupil based on the light that has passed through the spatial light modulator;
The distribution forming optical system includes: a first conjugate region that is optically substantially conjugate with a first region of the arrangement surface of the plurality of optical elements; and a second conjugate region that is optically substantially conjugate with the second region of the arrangement surface. Provided is an illumination optical system comprising a polarization state changing element that is disposed so as to be arranged in at least one of the conjugate regions, and that changes the polarization state of light incident on the one conjugate region and emits the light. .

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

In the third embodiment of the present invention, using the exposure apparatus of the second 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.

  An illumination optical system according to the present invention includes a spatial light modulator having a plurality of optical elements that are two-dimensionally arranged and individually controlled as means for variably forming a light intensity distribution on an illumination pupil. . As a result, the shape of the pupil intensity distribution can be freely and quickly changed by the action of the spatial light modulator.

  In the illumination optical system of the present invention, the distribution forming optical system that forms a pupil intensity distribution in the illumination pupil based on the light that has passed through the spatial light modulator is optically coupled to the first region of the array surface of the plurality of optical elements. A polarization state that is arranged so as to be arranged in at least one of a first conjugate region that is substantially conjugate and a second conjugate region that is optically substantially conjugate with the second region of the arrangement surface, and changes the polarization state of the incident light to be emitted. It has a change element. As a result, for example, a pupil intensity distribution in the circumferential polarization state can be formed by the cooperative action of the polarization state changing element and the spatial light modulator.

  In this way, the illumination optical system of the present invention can realize illumination conditions rich in diversity with respect to the shape and polarization state of the pupil intensity distribution. In the exposure apparatus of the present invention, the illumination optical system capable of realizing a variety of illumination conditions for the shape and polarization state of the pupil intensity distribution is realized according to the characteristics of the pattern to be transferred. Good exposure can be performed under appropriate illumination conditions, and thus a good device can be manufactured.

  Embodiments of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a drawing schematically showing a configuration of an exposure apparatus according to an embodiment of the present invention. In FIG. 1, the Z-axis 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 LS. As the light source LS, for example, an ArF excimer laser light source that supplies light with a wavelength of 193 nm, a KrF excimer laser light source that supplies light with a wavelength of 248 nm, or the like can be used. Light emitted from the light source LS is incident on the spatial light modulation unit SU via the beam transmission unit 1 and the polarization state switching unit 2. The beam transmitter 1 guides the incident light beam from the light source LS to the polarization state switching unit 2 (and thus the spatial light modulation unit SU) while converting the incident light beam into a light beam having a cross section having an appropriate size and shape. 2 has a function of actively correcting the position variation and the angle variation of the light beam incident on the beam 2.

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

  The spatial light modulation unit SU passes through the spatial light modulator 3 having a plurality of mirror elements that are two-dimensionally arranged and individually controlled, and the spatial light modulation unit SU via the beam transmission unit 1 and the polarization state switching unit 2. And a light guide member 4 for guiding the light incident on the spatial light modulator 3 and guiding the light having passed through the spatial light modulator 3 to the subsequent relay optical system 5a. The specific configuration and operation of the spatial light modulation unit SU will be described later.

  The light emitted from the spatial light modulation unit SU enters the predetermined surface IP via the relay optical system 5a. The relay optical system 5a is set so that the front focal position thereof substantially coincides with the position of the array surface of the plurality of mirror elements of the spatial light modulator 3, and the rear focal position substantially coincides with the position of the predetermined plane IP. Has been. As will be described later, the light passing through the spatial light modulator 3 forms a light intensity distribution corresponding to the postures of the plurality of mirror elements on the predetermined plane IP. The light whose light intensity distribution is formed on the predetermined surface IP is, via the relay optical system 5b, a polarization state changing unit 6a disposed at a position optically conjugate with the array surface of the plurality of mirror elements of the spatial light modulator 3. Is incident on. The specific configuration and operation of the polarization state changing unit 6a will be described later.

  The light that has passed through the polarization state changing unit 6a enters the micro fly's eye lens (or fly eye lens) 7 via the relay optical system 5c. The relay optical system 5c is set so that the front focal position thereof and the position of the polarization state changing unit 6a substantially coincide, and the rear focal position and the position of the incident surface of the micro fly's eye lens 7 substantially coincide. . Accordingly, the light that has passed through the spatial light modulator 3 and the polarization state changing unit 6a is formed on the incident surface of the micro fly's eye lens 7 that is disposed at a position optically conjugate with the predetermined surface IP. A light intensity distribution having the same outer shape as the intensity distribution is formed.

  The micro fly's eye lens 7 is an optical element made up of a large number of micro lenses having positive refractive power, which are arranged vertically and horizontally and densely. The micro fly's eye lens 7 is configured by forming a micro lens group by etching a plane parallel plate. 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's eye lens in that the lens elements are arranged vertically and horizontally.

  A rectangular minute refracting surface as a unit wavefront dividing surface in the micro fly's eye lens 7 is a rectangular shape similar to the shape of the illumination field to be formed on the mask M (and the shape of the exposure region to be formed on the wafer W). It is. For example, a cylindrical micro fly's eye lens can be used as the micro fly's eye lens 7. 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 7 is two-dimensionally divided by a large number of microlenses, and a secondary beam having substantially the same light intensity distribution as the illumination field formed by the incident light beam on or near the rear focal plane. A light source is formed. A light beam from a secondary light source (that is, pupil intensity distribution) formed on the rear focal plane of the micro fly's eye lens 7 or in the vicinity of the illumination pupil enters an illumination aperture stop (not shown). The illumination aperture stop is disposed at the rear focal plane of the micro fly's eye lens 7 or in the vicinity thereof, and has an opening (light transmission portion) 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.

  The light from the secondary light source limited by the illumination aperture stop illuminates the mask blind 9 in a superimposed manner via the condenser optical system 8. Thus, a rectangular illumination field corresponding to the shape and focal length of the rectangular micro-refractive surface of the micro fly's eye lens 7 is formed on the mask blind 9 as an illumination field stop. The light beam that has passed through the rectangular opening (light transmitting portion) of the mask blind 9 receives the light condensing action of the imaging optical system 10 and then illuminates the mask M on which a predetermined pattern is formed 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 light beam transmitted through the mask M held on the mask stage MS forms an image of a mask pattern on the wafer (photosensitive substrate) W held on the wafer stage WS via the projection optical system PL. In this way, batch exposure or scan exposure is performed while the wafer stage WS is two-dimensionally driven and controlled in a plane (XY plane) orthogonal to the optical axis AX of the projection optical system PL, and thus the wafer W is two-dimensionally driven and controlled. As a result, the pattern of the mask M is sequentially exposed in each exposure region of the wafer W.

  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 controller CR that controls the spatial light modulator 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 7 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 7 is relatively large, the overall light intensity distribution formed on the incident surface of the micro fly's eye lens 7 and the overall light intensity distribution (pupil intensity distribution) of the entire secondary light source. ) And a high correlation. For this reason, the light intensity distribution on the incident surface of the 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 light guide member 4, the relay optical systems 5 a, 5 b, 5 c, the polarization state changing unit 6 a, and the micro fly's eye lens 7 are based on the light that has passed through the spatial light modulator 3. In addition, a distribution forming optical system that forms a pupil intensity distribution in the illumination pupil on the rear side is configured.

  Referring to FIG. 2, the light guide member 4 in the spatial light modulation unit SU has a form of a triangular prism prism mirror extending in the X direction, for example. The light that has entered the spatial light modulation unit SU through the beam transmitter 1 and the polarization state switching unit 2 is reflected by the first reflecting surface 4 a of the light guide member 4 and then enters the spatial light modulator 3. The light modulated by the spatial light modulator 3 is reflected by the second reflecting surface 4b of the light guide member 4 and guided to the relay optical system 5a.

  As shown in FIGS. 2 and 3, the spatial light modulator 3 includes a main body 3a having a plurality of mirror elements SE arranged two-dimensionally, and a drive unit that individually controls and drives the postures of the plurality of mirror elements SE. 3b. For ease of explanation and illustration, FIGS. 2 and 3 show a configuration example in which the main body 3a of the spatial light modulator 3 includes 4 × 4 = 16 mirror elements SE. Much more mirror elements SE.

  Referring to FIG. 2, among the light beams incident on the first reflecting surface 4 a of the light guide member 4 along the direction parallel to the optical axis AX, the light beam L1 is applied to the mirror element SEa among the plurality of mirror elements SE. The light beam L2 is incident on 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.

  In the spatial light modulator 3, a direction parallel to the optical axis AX in a reference state (hereinafter referred to as “reference state”) in which the reflection surfaces of all the mirror elements SE are set along one plane (XY plane). Are reflected by each mirror element SE of the spatial light modulator 3 and then reflected by the second reflecting surface 4b of the light guide member 4 in a direction substantially parallel to the optical axis AX. It is configured. Further, the surface on which the plurality of mirror elements SE of the spatial light modulator 3 are arranged is positioned at or near the front focal position of the relay optical system 5a.

  Therefore, the light reflected by the mirror elements SEa to SEd of the spatial light modulator 3 and given a predetermined angular distribution forms the predetermined light intensity distributions SP1 to SP4 on the predetermined plane IP, and consequently the micro fly's eye lens 7. A light intensity distribution corresponding to the light intensity distributions SP1 to SP4 is formed on the incident surface. In other words, the relay optical system 5a determines the angle that the mirror elements SEa to SEd of the spatial light modulator 3 give to the emitted light with respect to a predetermined plane IP (and thus a microscopic field) that is a far field region (Fraunhofer diffraction region) of the spatial light modulator 3. The position is converted to a position on the incident surface of the fly-eye lens 7. The light intensity distribution (pupil intensity distribution) of the secondary light source formed by the micro fly's eye lens 7 is the light intensity distribution formed on the predetermined plane IP by the spatial light modulator 3 and the relay optical system 5a, and thus the spatial light modulator 3 and The relay optical systems 5a, 5b, and 5c have a distribution corresponding to the light intensity distribution formed on the incident surface of the micro fly's eye lens 7.

  As shown in FIG. 3, the spatial light modulator 3 includes a large number of minute mirror elements SE arranged regularly and two-dimensionally along one plane with a planar reflecting surface as an upper surface. It is a movable multi-mirror. Each mirror element SE is movable, and the inclination of the reflection surface, that is, the inclination angle and the inclination direction of the reflection surface are independently controlled by the drive unit 3b that operates according to a command from the control unit CR. Each mirror element SE can be rotated continuously or discretely by a desired rotation angle with two directions parallel to the reflecting surface and two directions orthogonal to each other (for example, the X direction and the Y direction) as rotation axes. it can. That is, it is possible to two-dimensionally control the inclination of the reflection surface of each mirror element SE.

  In addition, when rotating the reflective surface of each mirror element SE discretely, a rotation angle is a several state (For example, ..., -2.5 degree, -2.0 degree, ... 0 degree, +0. It is better to perform switching control at 5 degrees... +2.5 degrees,. Although FIG. 3 shows a mirror element SE having a square outer shape, the outer shape of the mirror element SE is not limited to a square. However, from the viewpoint of light utilization efficiency, it is possible to provide a shape that can be arranged so as to reduce the gap between the mirror elements SE (a shape that can be closely packed). Further, from the viewpoint of light utilization efficiency, the interval between two adjacent mirror elements SE can be minimized.

  In the present embodiment, as the spatial light modulator 3, for example, a spatial light modulator that continuously changes the directions of a plurality of mirror elements SE arranged two-dimensionally is 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 SE arranged two-dimensionally may be controlled so as to have a plurality of stages discretely.

  Thus, in the spatial light modulator 3, the posture of the plurality of mirror elements SE is changed by the action of the drive unit 3b that operates according to the control signal from the control unit CR, and each mirror element SE is in a predetermined direction. Is set. The light reflected at a predetermined angle by each of the plurality of mirror elements SE of the spatial light modulator 3 forms a desired light intensity distribution on the incident surface of the micro fly's eye lens 7, and consequently the rear side of the micro fly's eye lens 7. A pupil intensity distribution having a desired shape is formed on the illumination pupil (position where the illumination aperture stop is arranged) in the vicinity of the focal plane. Further, another illumination pupil position optically conjugate with the illumination aperture stop, that is, the pupil position of the imaging optical system 10 and the pupil position of the projection optical system PL (position where the aperture stop AS is disposed) are also desired. A pupil intensity distribution is formed.

  In the following description, in order to facilitate understanding of the main configuration and operational effects of the present embodiment, the predetermined surface IP has four arc-shaped substantial surface light sources (hereinafter simply referred to as “simply”). A quadrupole light intensity distribution 21 consisting of 21a, 21b, 21c, and 21d (referred to as “surface light source”) is formed. Further, it is assumed that the light in the linear polarization state polarized in the X direction, that is, the light in the X direction polarization state is incident on the spatial light modulation unit SU by the action of the polarization state switching unit 2. In the following description, the term “illumination pupil” simply refers to the rear focal plane of the micro fly's eye lens 7 or the illumination pupil in the vicinity thereof.

  Referring to FIG. 4, a quadrupole light intensity distribution 21 formed on a predetermined surface IP includes a pair of surface light sources 21a and 21b spaced in the X direction across the optical axis AX, and the optical axis AX. And a pair of surface light sources 21c and 21d spaced apart in the Z direction. Here, as shown in FIG. 5, the pair of surface light sources 21a and 21b is a straight line extending in the X direction in an effective area (indicated by a broken line) 3c on the array surface of the plurality of mirror elements SE of the spatial light modulator 3. Of the two regions 3ca and 3cb obtained by dividing the image into two, the light passes through a plurality of mirror elements SE arranged in the first region 3ca on the −Y direction side. In addition, the pair of surface light sources 21c and 21d are formed by light that has passed through a plurality of mirror elements SE arranged in the second region 3cb on the + Y direction side.

  In this case, the light that forms the pair of surface light sources 21a and 21b through the plurality of mirror elements SE arranged in the first region 3ca of the effective region 3c of the arrangement surface is 1 / of the polarization state changing unit 6a shown in FIG. The light enters the two-wave plate 6aa. On the other hand, the light that forms the pair of surface light sources 21c and 21d through the plurality of mirror elements SE arranged in the second region 3cb of the effective region 3c of the arrangement surface enters the parallel plane plate 6ab of the polarization state changing unit 6a. . In addition, it is possible to omit the installation of the plane parallel plate 6ab and to allow light to pass through the area indicated by the reference numeral 6ab as an opening.

  That is, in the polarization state changing unit 6a, the half-wave plate 6aa is disposed in the first conjugate region optically conjugate with the first region 3ca, and the parallel plane plate 6ab is optically conjugate with the second region 3cb. In the second conjugate region. Here, the first conjugate region where the half-wave plate 6aa can be arranged and the second conjugate region where the parallel plane plate 6ab can be arranged are in one plane (XZ plane) orthogonal to the optical axis AX. Needless to say.

  The light incident on the half-wave plate 6aa of the polarization state changing unit 6a in the X direction polarization state from the pair of surface light sources 21a and 21b is converted into light in the linear polarization state polarized in the Z direction, that is, in the Z direction polarization state. Thereafter, as shown in FIG. 7, a pair of surface light sources 22a and 22b corresponding to the pair of surface light sources 21a and 21b are formed on the rear focal plane of the micro fly's eye lens 7 or in the vicinity of the illumination pupil. In addition, the light incident on the parallel flat plate 6ab of the polarization state changing unit 6a in the X-direction polarization state from the pair of surface light sources 21c and 21d is in the X-direction polarization state without changing the polarization state. A pair of surface light sources 22c and 22d corresponding to 21d are formed in the illumination pupil.

  Thus, on the rear focal plane of the micro fly's eye lens 7 or in the vicinity of the illumination pupil, a pair of surface light sources 22a and 22b formed by light in the Z direction polarization state and light in the X direction polarization state are formed. A light intensity distribution composed of a pair of surface light sources 22c and 22d, that is, a so-called quadrupole and circumferentially polarized pupil intensity distribution 22 is obtained. Similarly, a pupil intensity distribution in a quadrupolar and circumferentially polarized state is also formed at the pupil position of the imaging optical system 10 and the pupil position of the projection optical system PL.

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

  In the exposure apparatus, in order to transfer the pattern of the mask M to the wafer W with high accuracy and faithfully, it is important to perform exposure under appropriate illumination conditions corresponding to the pattern characteristics. In the present embodiment, as a means for variably forming a light intensity distribution in the illumination pupil, a spatial light modulator 3 in which the postures of the plurality of mirror elements SE are individually changed is provided. Therefore, for example, based on the measurement result of the pupil intensity distribution measurement unit DT, the control unit CR controls the postures of the plurality of optical elements SE of the spatial light modulator 3, so that the shape of the pupil intensity distribution formed in the illumination pupil is formed. (A wide concept including size) can be changed freely and quickly.

  In the present embodiment, the distribution forming optical system (4 to 7) that forms a pupil intensity distribution on the illumination pupil based on the light that has passed through the spatial light modulator 3 includes the first array surface 3c of the plurality of mirror elements SE. A half-wave plate 6aa that is arranged in a first conjugate region that is optically conjugate with the region 3ca and emits light after changing the polarization state of incident light. As a result, due to the cooperative action of the half-wave plate 6aa as the polarization state changing element and the spatial light modulator 3, the circumferential polarization state is applied to the rear focal plane of the micro fly's eye lens 7 or the illumination pupil in the vicinity thereof. Can be formed.

  As described above, in the illumination optical system (1 to 10) of the present embodiment, it is possible to realize a wide variety of illumination conditions with respect to the shape and polarization state of the pupil intensity distribution. Therefore, in the exposure apparatus (1 to WS) of the present embodiment, transfer is performed using the illumination optical system (1 to 10) capable of realizing a variety of illumination conditions for the shape and polarization state of the pupil intensity distribution. Good exposure can be performed under appropriate illumination conditions realized according to the characteristics of the fine pattern of the mask M to be performed.

  In the above description, the polarization state changing unit 6a is arranged in the first conjugate region optically substantially conjugate with the first region 3ca of the effective region 3c of the array surface of the plurality of mirror elements SE of the spatial light modulator 3. And a parallel plane plate 6ab disposed in a second conjugate region optically substantially conjugate with the second region 3cb. However, the present invention is not limited to this configuration example, and various configurations are possible for the specific configuration of the polarization state changing unit.

  For example, instead of the polarization state changing unit 6a having the half-wave plate 6aa, a polarization state changing unit 6b having a pair of optical rotators 6ba and 6bb can be used as shown in FIG. In general, an optical rotator (optical rotator) has a function of emitting a linearly polarized incident light with a required optical rotation angle. The optical rotator is made of quartz which is an optical material having optical activity, and the crystal optical axis thereof is set so as to substantially coincide with the optical axis AX. The optical rotatory power of quartz has a wavelength dependency (a property in which the value of the optical rotatory power varies depending on the wavelength of the used light: optical rotatory dispersion). Specifically, it tends to increase as the wavelength of the used light becomes shorter. According to the description on page 167 of "Applied optics II", the optical rotation power of quartz for light having a wavelength of 250.3 nm is 153.9 degrees / mm.

  That is, in the polarization state changing unit 6b, the thicknesses (dimensions in the optical axis direction) of the pair of optical rotators 6ba and 6bb are respectively set according to the required optical rotation angle to be given to the linearly polarized incident light. Specifically, in order to obtain a quadrupole and circumferentially polarized state pupil intensity distribution 22 as shown in FIG. 7 using the polarization state changing unit 6b, for example, by the action of the polarization state switching unit 2, for example, in the + X direction and + Z direction Light in a linearly polarized state that is polarized in an oblique direction having an angle of 45 degrees with respect to the direction, that is, in an obliquely polarized state, is incident on the spatial light modulation unit SU.

  Then, the thickness of the first optical rotator 6ba disposed in the first conjugate region optically substantially conjugate with the first region 3ca is rotated by +135 degrees around the Y axis with respect to the polarization direction of the incident light in the obliquely polarized state. It is set so that light polarized in a different direction, that is, light in the Z-direction linearly polarized state is emitted. Further, the thickness of the second optical rotator 6bb disposed in the second conjugate region optically almost conjugate with the second region 3cb is rotated by +45 degrees around the Y axis with respect to the polarization direction of the incident light in the obliquely polarized state. The light is set so as to emit light polarized in a different direction, that is, light in the X-direction linearly polarized state.

  Further, instead of the polarization state changing unit 6a having the half-wave plate 6aa, a polarization state changing unit 6c having a pair of polarizers 6ca and 6cb can be used as shown in FIG. As the polarizers 6ca and 6cb, for example, wire grid type polarizers can be used. Such a wire grid type polarizer is disclosed in, for example, Japanese Patent Application Laid-Open No. 2005-202104. Further, a polarizer including a polarization splitting surface array disclosed in US Pat. No. 7,408,622 may be used.

  Specifically, in order to obtain a quadrupole and circumferentially polarized state pupil intensity distribution 22 as shown in FIG. 7 using the polarization state changing unit 6c, the polarization state switching unit 2 can be used, for example, substantially non- Polarized light is incident on the spatial light modulation unit SU. The first polarizer 6ca disposed in the first conjugate region optically substantially conjugate with the first region 3ca emits only the light component in the Z-direction linearly polarized state from the unpolarized incident light, and the second region The second polarizer 6cb disposed in the second conjugate region optically substantially conjugate with 3cb emits only the light component in the X-direction linearly polarized state from the unpolarized incident light.

  Furthermore, a polarization state changing unit 6a having a half-wave plate 6aa, a polarization state changing unit 6b having optical rotators 6ba and 6bb, and a polarization state changing unit 6c having polarizers 6ca and 6cb are provided with respect to the illumination optical path. It can also be configured to be replaceable. In other words, the polarization state changing element such as the half-wave plate 6aa may be configured to be exchangeable with another polarization state changing element having different characteristics (such as the optical rotators 6ba and 6bb and the polarizers 6ca and 6cb). it can.

  In the above description, the operational effects of the present invention are described by taking, as an example, modified illumination in which a quadrupole pupil intensity distribution 22 is formed on the illumination pupil, that is, quadrupole illumination. However, the present invention is not limited to quadrupole illumination. For example, annular illumination in which an annular pupil intensity distribution is formed, multipolar illumination in which a multipolar pupil intensity distribution other than quadrupole is formed, and the like. In contrast, it is apparent that the same effects can be obtained by applying the present invention. As an example, FIG. 10 shows a state in which the pupil intensity distribution 23 (23a to 23d) in the annular shape and in the circumferential polarization state is formed on the illumination pupil.

  In the above description, the first conjugate region where the half-wave plate 6aa can be placed and the second conjugate region where the parallel plane plate 6ab can be placed are within one plane (XZ plane) orthogonal to the optical axis AX. Is provided. However, the present invention is not limited to this, and the first conjugate region in which the first polarization state changing element is to be disposed and the second conjugate region in which the second polarization state changing element is to be disposed are one orthogonal to the optical axis AX. It does not have to be provided in the plane, and can be provided at two different positions which are optically conjugate.

  In the above description, the two regions 3ca and 3cb obtained by equally dividing the effective region 3c of the array surface of the plurality of mirror elements SE of the spatial light modulator 3 into two are arranged in the first region 3ca. The surface light sources 21a and 21b are formed by light passing through the plurality of mirror elements SE, and the surface light sources 21c and 21d are formed by light passing through the plurality of mirror elements SE arranged in the second region 3cb. However, the present invention is not limited to two halves, and various forms are possible for setting the first region and the second region in the effective region 3c of the arrangement surface. That is, various modification examples are conceivable with respect to the number and arrangement of the regions in the effective region 3c of the arrangement surface of the spatial light modulator 3, the shape of the light intensity distribution formed by the light passing through each region in the illumination pupil, the polarization state, and the like. It is done.

  In the above description, as the spatial light modulator having a plurality of optical elements that are two-dimensionally arranged and individually controlled, the direction (angle: inclination) of the plurality of two-dimensionally arranged reflecting surfaces is set. An individually controllable spatial light modulator is used. However, the present invention is not limited to this. For example, a spatial light modulator that can individually control the height (position) of a plurality of two-dimensionally arranged reflecting surfaces can be used. As such a spatial light modulator, for example, 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 description, a reflective spatial light modulator having a plurality of mirror elements is used. However, the present invention is not limited to this. For example, transmission disclosed in US Pat. No. 5,229,872 A type of spatial light modulator may be used.

  In the above-described embodiment, the micro fly's eye lens 7 is used as the optical integrator, but instead, an internal reflection type optical integrator (typically a rod type integrator) may be used. In this case, an imaging optical system that forms a position optically conjugate with the polarization state changing unit 6a is disposed instead of the relay optical system 5c. Then, instead of the micro fly's eye lens 7 and the condenser optical system 8, a rod type integrator is arranged so that the incident end is positioned at or near the conjugate position by the imaging optical system. At this time, the injection end of the rod-type integrator is positioned at the mask blind 9. When a rod type integrator is used, a position optically conjugate with the position of the aperture stop AS of the projection optical system PL in the imaging optical system 10 downstream of the rod type integrator can be called an illumination pupil plane. In addition, since a virtual image of the secondary light source of the illumination pupil plane is formed at the position of the entrance surface of the rod integrator, this position and a position optically conjugate with this position are also called the illumination pupil plane. Can do.

  In the above-described embodiment, a variable pattern forming apparatus that forms a predetermined pattern based on predetermined electronic data can be used instead of a mask. 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.

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

  Next, a device manufacturing method using the exposure apparatus according to the above-described embodiment will be described. FIG. 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 or the like), a micromachine, a thin film magnetic head, and a DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

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

  In the above-described embodiment, 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 technique for filling the liquid in the optical path between the projection optical system and the photosensitive substrate, a technique for locally filling the liquid as disclosed in International Publication No. WO99 / 49504, a special technique, A method of moving a stage holding a substrate to be exposed as disclosed in Kaihei 6-124873 in a liquid bath, or a predetermined stage on a stage as disclosed in JP-A-10-303114. A method of forming a liquid tank having a depth and holding the substrate therein can be employed.

  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.

It is a figure which shows schematically the structure of the exposure apparatus concerning embodiment of this invention. It is a figure explaining the effect | action of the spatial light modulator in a spatial light modulation unit. It is a fragmentary perspective view of the principal part of a spatial light modulator. It is a figure which shows quadrupole light intensity distribution formed in the predetermined surface IP. It is a figure which shows a mode that the effective area | region of the arrangement surface of the several mirror element of a spatial light modulator was divided into 2 equally. It is a figure which shows the structural example of the polarization state change unit which has a wavelength plate. It is a figure which shows the pupil intensity distribution of 4 pole shape and the circumferential direction polarization state. It is a figure which shows the structural example of the polarization state change unit which has an optical rotator. It is a figure which shows the structural example of the polarization state change unit which has a polarizer. It is a figure which shows the pupil intensity distribution of the annular | circular shape and the circumferential direction polarization state. It is a flowchart which shows the manufacturing process of a semiconductor device. It is a flowchart which shows the manufacturing process of liquid crystal devices, such as a liquid crystal display element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Beam transmission part 2 Polarization state switching part 3 Spatial light modulator 4 Light guide member 5a, 5b, 5c Relay optical system 6a, 6b, 6c Polarization state change unit 7 Micro fly eye lens 8 Condenser optical system 9 Mask blind 10 Connection Image optical system DT Pupil intensity distribution measurement unit LS Light source SU Spatial light modulation unit CR Control unit M Mask PL Projection optical system W Wafer

Claims (14)

In the illumination optical system that illuminates the illuminated surface based on the light from the light source,
A spatial light modulator having a plurality of optical elements arranged two-dimensionally and individually controlled;
A distribution forming optical system that forms a pupil intensity distribution in the illumination pupil based on the light that has passed through the spatial light modulator;
The distribution forming optical system includes: a first conjugate region that is optically substantially conjugate with a first region of the arrangement surface of the plurality of optical elements; and a second conjugate region that is optically substantially conjugate with the second region of the arrangement surface. An illumination optical system, comprising: a polarization state changing element that is arranged so as to be arranged in at least one of the conjugate regions, and that changes the polarization state of light incident on the one conjugate region and emits the light. The distribution forming optical system includes a first polarization state changing element provided to be arranged in the first conjugate region and a second polarization state changing element provided to be arranged in the second conjugate region. The illumination optical system according to claim 1. 3. The illumination optical system according to claim 1, wherein the first conjugate region and the second conjugate region are in one plane orthogonal to the optical axis of the distribution forming optical system. 4. The illumination optical system according to claim 1, wherein the first region and the second region are regions obtained by dividing an effective region of the arrangement surface into two equal parts. 5. The illumination optical system according to claim 1, wherein the polarization state changing element has a wave plate. The illumination optical system according to claim 1, wherein the polarization state changing element includes a polarizer. The illumination optical system according to any one of claims 1 to 4, wherein the polarization state changing element includes an optical rotator. The illumination optical system according to any one of claims 1 to 7, wherein the polarization state changing element is configured to be exchangeable with another polarization state changing element having different characteristics. 9. 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 9, wherein the driving unit changes the directions of the plurality of mirror elements continuously or discretely. 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 10. 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 exposure apparatus according to claim 12, further comprising a projection optical system that forms an image of the predetermined pattern on the photosensitive substrate. An exposure step of exposing the predetermined pattern to the photosensitive substrate using the exposure apparatus according to claim 12 or 13,
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.

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