JP2011134763A - Illumination optical system, aligner, and device manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an illumination optical system which can stably form a desired lens strength distribution even if a defective optical element is generated, in a spacial light modulator. <P>SOLUTION: The illumination optical system (IL) that illuminates a light-exposure surface (M) with light from a light source (1) includes a plurality of optical elements arranged on a given plane and controlled separately. The illumination optical system (IL) also includes a spacial light modulator (30) which forms a lens strength distribution on an illumination lens of the illumination optical system (IL), a detecting unit (9) which detects each beam of light that passes through each of the optical elements to fall to a conjugate location optically conjugate with the illumination lens, and a control unit (CR) which classifies the detection result of the detecting unit concerning the beams of light from the optical elements and controls the optical elements separately using the classified detection result information. <P>COPYRIGHT: (C)2011,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 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 plurality of mirror elements (generally optical elements) whose postures are individually controlled is used, the shape and size of the pupil intensity distribution There is a high degree of freedom regarding changes. However, for various reasons as will be described later, some of the plurality of mirror elements may not perform a required function. Conventionally, there has been no specific proposal for dealing with a defective mirror element (defective optical element) that cannot perform a required function.

  The present invention has been made in view of the above-described problems, and stably forms a desired pupil intensity distribution even when a defective optical element occurs in a spatial light modulator, and thus stably achieves a desired illumination condition. An object of the present invention is to provide an illumination optical system that can be formed. Another object of the present invention is to provide an exposure apparatus that can stably perform good exposure under appropriate illumination conditions using an illumination optical system that stably forms desired illumination conditions. And

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 in a predetermined plane and individually controlled, and forming a pupil intensity distribution in an illumination pupil of the illumination optical system;
A detection unit for detecting each light beam incident on a conjugate position optically conjugate with the illumination pupil via each of the plurality of optical elements;
A control unit that classifies each detection result by the detection unit for each of the plurality of optical elements, and controls the plurality of optical elements individually using the classified information. An illumination optical system is provided.

  According to a second aspect of the present invention, the illumination optical system according to any one of claims 1 to 8 for illuminating a predetermined pattern is provided, and the predetermined pattern is exposed on a photosensitive substrate. An exposure apparatus is provided.

In the third aspect of the present invention, using the exposure apparatus according to claim 9 or 10, an exposure step of exposing the photosensitive pattern to the photosensitive substrate;
Developing the photosensitive substrate to which the predetermined pattern is transferred, and forming a mask layer having a shape corresponding to the predetermined pattern on the surface of the photosensitive substrate;
And a processing step of processing the surface of the photosensitive substrate through the mask layer.

In the fourth aspect of the present invention, the illumination optical system is used together with an illumination optical system that illuminates a surface to be irradiated based on light from a light source. The illumination optical system includes a plurality of optical elements arranged in a predetermined plane and individually controlled. In a method for controlling a spatial light modulator that forms a pupil intensity distribution in an illumination pupil of an optical system,
Detecting each light beam incident on a conjugate position optically conjugate with the illumination pupil via each of the plurality of optical elements;
A classification step for classifying the detection results of the light beams;
And a control step of individually controlling the plurality of optical elements using information classified by the classification step.

  In the illumination optical system according to one aspect of the present invention, the position, the outer shape, and the intensity distribution of each light beam incident on a conjugate position optically conjugate with the illumination pupil via each optical element of the spatial light modulator are detected, A plurality of optical elements are individually controlled using information categorizing each detection result for each optical element. In the illumination optical system of the present invention, since the attitudes of a plurality of optical elements are individually controlled in consideration of the control error, shape error, and intensity error of each optical element, defective optical elements are generated in the spatial light modulator. In addition, a desired pupil intensity distribution can be stably formed, and thus a desired illumination condition can be stably formed. Further, in the exposure apparatus of the present invention, it is possible to stably perform good exposure under appropriate illumination conditions using an illumination optical system that stably forms desired illumination conditions. 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 roughly the structure and effect | action of a spatial light modulation unit. It is a fragmentary perspective view of the spatial light modulator in a spatial light modulation unit. It is a flowchart which shows each process of the control method of this embodiment. It is a flowchart which shows each process in the detection process of FIG. It is a flowchart which shows each process in the classification process of FIG. It is a figure explaining an example of the control method of the mirror element which has a comparatively big shape error. It is a flowchart which shows the manufacturing process of a semiconductor device. It is a flowchart which shows the manufacturing process of liquid crystal devices, such as a liquid crystal display element.

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

  Referring to FIG. 1, exposure light (illumination light) is supplied from a light source 1 to the exposure apparatus of the present embodiment. 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 exposure apparatus of this embodiment supports an illumination optical system IL including a spatial light modulation unit 3, a mask stage MS that supports a mask M, a projection optical system PL, and a wafer W along the optical axis AX of the apparatus. Wafer stage WS.

  The light from the light source 1 illuminates the mask M through the illumination optical system IL. The light transmitted through the mask M forms an image of the pattern of the mask M on the wafer W via the projection optical system PL. The illumination optical system IL that illuminates the pattern surface (illuminated surface) of the mask M based on the light from the light source 1 is a multipolar illumination (bipolar illumination, quadrupole illumination, etc.) Deformation illumination such as annular illumination or normal circular illumination is performed.

  The illumination optical system IL includes, in order from the light source 1 side along the optical axis AX, a beam transmission unit 2, a spatial light modulation unit 3, a relay optical system 4, a detection unit 9, and a micro fly's eye lens (or fly fly lens). Eye lens) 5, condenser optical system 6, illumination field stop (mask blind) 7, and imaging optical system 8. The detection unit 9 includes a beam splitter 9a disposed in the optical path between the relay optical system 4 and the micro fly's eye lens 5, and a photodetector 9b that detects light extracted from the illumination optical path by the beam splitter 9a. Have. The operation of the detection unit 9 will be described later.

  The spatial light modulation unit 3 forms a desired light intensity distribution (pupil intensity distribution) in the far field region (Fraunhofer diffraction region) based on the light from the light source 1 via the beam transmitter 2. The internal configuration and operation of the spatial light modulation unit 3 will be described later. 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. The relay optical system 4 condenses the light from the spatial light modulation unit 3 and guides it to the micro fly's eye lens 5.

  The micro fly's eye lens 5 is, for example, an optical element composed of a large number of micro lenses having positive refractive power arranged vertically and horizontally and densely. The micro fly's eye lens 5 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'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 5 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. The micro fly's eye lens 5 divides the incident light beam into a wavefront and forms a secondary light source (substantial surface light source; pupil intensity distribution) composed of a large number of small light sources at the illumination pupil at or near the rear focal position. . The incident surface of the micro fly's eye lens 5 is disposed at or near the rear focal position of the relay optical system 4. For example, a cylindrical micro fly's eye lens can be used as the micro fly's eye lens 5. The configuration and operation of the cylindrical micro fly's eye lens are disclosed in, for example, US Pat. No. 6,913,373.

  In this embodiment, the secondary light source formed by the micro fly's eye lens 5 is used as a light source, and the mask M arranged on the irradiated surface of the illumination optical system IL 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 IL. . 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 IL or a plane optically conjugate with the illumination pupil plane. When the number of wavefront divisions by the micro fly's eye lens 5 is relatively large, the overall light intensity distribution formed on the incident surface of the micro fly's eye lens 5 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 5 and the surface optically conjugate with the incident surface can also be referred to as a pupil intensity distribution.

  The condenser optical system 6 condenses the light emitted from the micro fly's eye lens 5 and illuminates the illumination field stop 7 in a superimposed manner. The light that has passed through the illumination field stop 7 forms an illumination region that is an image of the opening of the illumination field stop 7 in at least a part of the pattern formation region of the mask M via the imaging optical system 8. In FIG. 1, the installation of the optical path bending mirror for bending the optical axis (and thus the optical path) is omitted, but the optical path bending mirror can be appropriately arranged in the illumination optical path as necessary. .

  A mask M is placed on the mask stage MS along the XY plane (for example, a horizontal plane), and a wafer W is placed on the wafer stage WS along the XY plane. The projection optical system PL forms an image of the pattern of the mask M on the transfer surface (exposure surface) of the wafer W based on the light from the illumination area formed on the pattern surface of the mask M by the illumination optical system IL. . 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.

  Next, the internal configuration and operation of the spatial light modulation unit 3 will be described with reference to FIGS. As shown in FIG. 2, the spatial light modulation unit 3 includes a prism 21 made of an optical material such as fluorite, and a spatial light modulation unit disposed close to a side surface 21a parallel to the YZ plane of the prism 21. Device 30. The optical material forming the prism 21 is not limited to fluorite, and may be quartz or other optical material according to the wavelength of light supplied from the light source 1 or the like.

  The spatial light modulator 30 includes, for example, a plurality of mirror elements 30a that are two-dimensionally arranged along the YZ plane, a base 30b that holds the plurality of mirror elements 30a, and a cable (not shown) connected to the base 30b. And a drive unit 30c for individually controlling and driving the postures of the plurality of mirror elements 30a. In the spatial light modulator 30, the attitude of the plurality of mirror elements 30a is changed by the action of the drive unit 30c that operates based on the control signal from the control unit CR, and each mirror element 30a is set in a predetermined direction. The

  The prism 21 is obtained by replacing one side surface of the rectangular parallelepiped (a side surface facing the side surface 21a where the plurality of mirror elements 30a of the spatial light modulator 30 are arranged close to each other) with side surfaces 21b and 21c recessed in a V shape. It has an obtained form and is also called a K prism because of its cross-sectional shape along the XZ plane. Sides 21b and 21c of the prism 21 that are recessed in a V shape are defined by two planes P1 and P2 that intersect to form an obtuse angle. The two planes P1 and P2 are both orthogonal to the XZ plane and have a V shape along the XZ plane.

  The inner surfaces of the two side surfaces 21b and 21c that are in contact with a tangent line (a straight line extending in the Y direction) P3 between the two planes P1 and P2 function as the reflection surfaces R1 and R2. That is, the reflective surface R1 is located on the plane P1, the reflective surface R2 is located on the plane P2, and the angle formed by the reflective surfaces R1 and R2 is an obtuse angle. As an example, the angle between the reflecting surfaces R1 and R2 is 120 degrees, the angle between the incident surface IP of the prism 21 perpendicular to the optical axis AX and the reflecting surface R1 is 60 degrees, and the prism 21 perpendicular to the optical axis AX. The angle formed by the exit surface OP and the reflective surface R2 can be 60 degrees.

  In the prism 21, the side surface 21a on which the plurality of mirror elements 30a of the spatial light modulator 30 are arranged close to each other and the optical axis AX are parallel, and the reflection surface R1 is on the light source 1 side (upstream side of the exposure apparatus: FIG. 2 on the left side), the reflecting surface R2 is located on the micro fly's eye lens 5 side (downstream side of the exposure apparatus: right side in FIG. 2). More specifically, the reflecting surface R1 is obliquely arranged with respect to the optical axis AX, and the reflecting surface R2 is obliquely inclined with respect to the optical axis AX symmetrically with respect to the reflecting surface R1 with respect to a plane passing through the tangent line P3 and parallel to the XY plane. It is installed.

  The reflection surface R <b> 1 of the prism 21 reflects light incident through the incident surface IP toward the spatial light modulator 30. The plurality of mirror elements 30a of the spatial light modulator 30 are arranged in the optical path between the reflecting surface R1 and the reflecting surface R2, and reflect the light incident through the reflecting surface R1. The reflecting surface R2 of the prism 21 reflects the light incident through the spatial light modulator 30 and guides it to the relay optical system 4 through the exit surface OP. Although FIG. 2 shows an example in which the prism 21 is integrally formed by one optical block, the prism 21 may be configured by using a plurality of optical blocks as will be described later.

  The spatial light modulator 30 applies the spatial modulation according to the incident position to the light incident through the reflecting surface R1 and emits the light. As shown in FIG. 3, the spatial light modulator 30 includes a plurality of minute mirror elements (optical elements) 30a arranged two-dimensionally within a predetermined plane. For ease of explanation and illustration, FIGS. 2 and 3 show a configuration example in which the spatial light modulator 30 includes 4 × 4 = 16 mirror elements 30a. Are provided with a number of mirror elements 30a.

  Referring to FIG. 2, among the light beams incident on the spatial light modulation unit 3 along the direction parallel to the optical axis AX, the light beam L1 is the mirror element SEa of the plurality of mirror elements 30a, and the light beam L2 is the mirror element. The light is incident on a mirror element SEb different from 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 modulation unit 3, in the reference state where the reflection surfaces of all the mirror elements 30a of the spatial light modulator 30 are set parallel to the YZ plane, the light enters the reflection surface R1 along the direction parallel to the optical axis AX. After passing through the spatial light modulator 30, the light beam is configured to be reflected in the direction parallel to the optical axis AX by the reflecting surface R2. In addition, the spatial light modulation unit 3 has an air conversion length from the incident surface IP of the prism 21 through the mirror element 30a to the exit surface OP, and a position corresponding to the incident surface IP when the prism 21 is not disposed in the optical path. The air-converted length from the position to the position corresponding to the exit surface OP is equal. Here, the air conversion length is the optical path length in the optical system converted into the optical path length in the air with a refractive index of 1, and the air conversion length in the medium with the refractive index n is 1 / the optical path length. multiplied by n.

  The array surface of the plurality of mirror elements 30 a of the spatial light modulator 30 is disposed at or near the front focal position of the relay optical system 4. The light reflected by the plurality of mirror elements 30a of the spatial light modulator 30 and given a predetermined angular distribution forms predetermined light intensity distributions SP1 to SP4 on the rear focal plane 4a of the relay optical system 4. That is, the relay optical system 4 determines the angle that the plurality of mirror elements 30a of the spatial light modulator 30 gives to the emitted light on the surface 4a that is the far field region (Fraunhofer diffraction region) of the spatial light modulator 30. Has been converted.

  Referring again to FIG. 1, the incident surface of the micro fly's eye lens 5 is positioned at the rear focal plane 4 a of the relay optical system 4. Therefore, the pupil intensity distribution formed in the illumination pupil immediately after the micro fly's eye lens 5 is the light intensity distributions SP1 to SP4 formed on the incident surface of the micro fly's eye lens 5 by the spatial light modulator 30 and the relay optical system 4. Corresponding distribution. As shown in FIG. 3, the spatial light modulator 30 includes a large number of minute mirror elements 30a regularly and two-dimensionally arranged along one plane, for example, with a planar reflecting surface as an upper surface. Is a movable multi-mirror.

  Each mirror element 30a is movable, and the tilt of the reflecting surface, that is, the tilt angle and tilt direction of the reflecting surface are independently controlled by the action of the drive unit 30c that operates according to a command from the control unit CR. Each mirror element 30a can be rotated continuously or discretely by a desired rotation angle with two directions (Y direction and Z direction) parallel to the reflecting surface and orthogonal to each other as rotation axes. . That is, it is possible to two-dimensionally control the inclination of the reflecting surface of each mirror element 30a.

  When the reflection surface of each mirror element 30a is discretely rotated, the rotation angle is set in a plurality of states (for example,..., -2.5 degrees, -2.0 degrees, ... 0 degrees, +0.5 degrees). ... +2.5 degrees,. Although FIG. 3 shows a mirror element 30a having a square outer shape, the outer shape of the mirror element 30a is not limited to a square. However, from the viewpoint of light utilization efficiency, a shape that can be arranged so as to reduce the gap between the mirror elements 30a (a shape that can be closely packed) is preferable. From the viewpoint of light utilization efficiency, it is preferable to minimize the interval between two adjacent mirror elements 30a.

  In the present embodiment, as the spatial light modulator 30, for example, a spatial light modulator that continuously changes the directions of a plurality of mirror elements 30a 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 orientations of the plurality of mirror elements 30a arranged two-dimensionally may be controlled so as to have a plurality of discrete stages.

  In the spatial light modulator 30, the posture of the plurality of mirror elements 30a is changed by the action of the drive unit 30c that operates according to the control signal from the control unit CR, and each mirror element 30a is set in a predetermined direction. The The light reflected by the plurality of mirror elements 30a of the spatial light modulator 30 at a predetermined angle is applied to the illumination pupil immediately after the micro fly's eye lens 5 via the relay optical system 4 in a plurality of poles (bipolar). Light intensity distribution (pupil intensity distribution) having a ring shape, a circular shape, or the like.

  That is, the relay optical system 4 and the micro fly's eye lens 5 form a predetermined light intensity distribution in the illumination pupil of the illumination optical system IL based on the light that has passed through the spatial light modulator 30 in the spatial light modulation unit 3. A distribution forming optical system is configured. Further, another illumination pupil position optically conjugate with the rear focal position of the micro fly's eye lens 5 or the illumination pupil in the vicinity thereof, that is, the pupil position of the imaging optical system 8 and the pupil position of the projection optical system PL (aperture stop). A pupil intensity distribution corresponding to the light intensity distribution in the illumination pupil immediately after the micro fly's eye lens 5 is also formed at the AS position).

  In the exposure apparatus, in order to transfer the pattern of the mask M onto the wafer W with high accuracy and faithfulness, it is important to perform exposure under appropriate illumination conditions according to the pattern characteristics of the mask M, for example. In the present embodiment, since the spatial light modulation unit 3 including the spatial light modulator 30 in which the postures of the plurality of mirror elements 30a individually change is used, the pupil intensity formed by the action of the spatial light modulator 30 is used. The distribution can be freely and quickly changed, and various illumination conditions can be realized.

  However, in the present embodiment, there is a possibility that some of the plurality of mirror elements 30a of the spatial light modulator 30 do not perform a required function. Specifically, for example, the reflectance of the mirror element 30a having a reflecting surface made of a metal film such as aluminum decreases with time due to light irradiation, and after the relay optical system 4 passes through the mirror element 30a due to the decrease in reflectance. There is a possibility that the light amount of the light beam incident on the side focal plane 4a is decreased (the intensity distribution of the light beam is changed from a required intensity distribution in the design). In addition, the reflecting surface of the mirror element 30a is deformed over time by light irradiation, and the outer shape of the light beam incident on the surface 4a through the mirror element 30a can be changed from the required design outer shape by the deformation of the reflecting surface. There is sex.

  In addition, the tilt angle or the tilt direction of the reflecting surface of the mirror element 30a may not be correctly controlled for some reason, and the position of the light beam incident on the surface 4a through the mirror element 30a may be displaced from the required position in the design. There is. When a part of the plurality of mirror elements 30a does not perform the required function, a desired light intensity distribution is formed on the surface 4a due to the defective mirror element 30a, and the illumination pupil immediately after the micro fly's eye lens 5 is formed. Therefore, a desired pupil intensity distribution cannot be formed.

  In the present embodiment, there is provided a detection unit 9 that detects each light beam incident on a detection surface 9ba optically conjugate with the surface 4a via each mirror element 30a of the spatial light modulator 30. That is, the photodetector 9b of the detection unit 9 is disposed at a position optically conjugate with the rear focal plane 4a of the relay optical system 4, and thus at a position optically conjugate with the incident surface of the micro fly's eye lens 5. It has a detection surface 9ba. As described above, the light intensity distribution formed on the incident surface of the micro fly's eye lens 5 and the light intensity distribution (pupil intensity distribution) formed on the illumination pupil immediately after the micro fly's eye lens 5 show a high correlation. Therefore, the position of the incident surface of the micro fly's eye lens 5 can be called a position optically conjugate with the illumination pupil.

  Therefore, the detection unit 9 detects each light beam incident on the detection surface 9ba disposed at a position optically conjugate with the illumination pupil via each mirror element 30a. Specifically, the detection unit 9 detects the position, outer shape, and intensity distribution of each light beam incident on the detection surface 9ba through each mirror element 30a. The detection result of the detection unit 9 is supplied to the control unit CR. As will be described later, the control unit CR classifies each detection result by the detection unit 9 for each mirror element 30a, and individually controls the plurality of mirror elements 30a using the classified information.

  Hereinafter, a method for controlling the spatial light modulator 30 according to the present embodiment will be described with reference to FIGS. 4, 5, and 6. In the control method of the present embodiment, each light beam incident on the detection surface 9ba of the detection unit 9 via each mirror element 30a of the spatial light modulator 30 is detected (S10). In the detection step S10, the plurality of mirror elements 30a of the spatial light modulator 30 are grouped, and detection is performed for each group. Each group includes, for example, a plurality of mirror elements 30a distributed discretely. In other words, the light beams incident on the detection surface 9ba through the mirror elements 30a are simultaneously detected for each group of mirror elements among the plurality of mirror elements 30a. However, as necessary, the light flux is individually detected for all or some of the mirror elements 30a in the group.

  Specifically, in the detection step S10, as shown in the flowchart of FIG. 5, the position of each light beam incident on the detection surface 9ba by the detection unit 9 via each mirror element 30a in the reference state of the spatial light modulator 30, for example ( For example, the center position) is detected (S11), the outer shape of each light beam is detected (S12), and the intensity distribution of each light beam is detected (S13). Further, in the detection step S10, the detection unit 9 has a position (for example, the position of each light beam that has passed through each mirror element 30a in a tilted state in which the reflecting surface of each mirror element 30a is tilted in a predetermined direction by a predetermined angle from the reference state, for example. (Center position) is detected (S14). That is, in the detection step S10, a change in position of each light beam according to the control of each mirror element 30a is detected. In the tilted state, the position and outer shape of each light beam incident on the detection surface 9ba via each mirror element 30a can be detected, and the detection result can be used.

  Next, in the control method of the present embodiment, the detection results of the detection unit 9 for the mirror elements 30a of the spatial light modulator 30, that is, the detection results of the light beams that have passed through the mirror elements 30a are classified (S20). Specifically, in the classification step S20, as shown in the flowchart of FIG. 6, the control unit CR adds a plurality of mirror elements 30a according to the detection result regarding the position change of each light beam according to the control of each mirror element 30a. Sort (S21). In step S21, the control unit CR uses the reference information (the required movement amount and the required movement direction based on the design) as the movement amount and the movement direction of each light beam accompanying the change in the posture of each mirror element 30a from the reference state to the inclined state. ), The plurality of mirror elements 30a are divided into groups having control characteristics similar to each other.

  In step S21, for example, the controller CR roughly divides into a mirror element that does not need to consider the control error, a mirror element that should consider the control error, and a mirror element that should not be used. Here, the mirror element that should not be used is a mirror element having a control error that is too large, that is, a mirror element in which a change in the position of the light beam accompanying a change in posture deviates from a predetermined allowable range. The mirror elements that should take control error into consideration are further classified as needed based on information such as the nature and magnitude of the control error.

  In the classification step S20, the control unit CR classifies the plurality of mirror elements 30a according to the detection result relating to the outer shape of each light beam that has passed through each mirror element 30a (S22). In step S22, for example, the outer shape of each light beam of each mirror element 30a in the reference state is compared with reference information (required outer shape based on design), and the plurality of mirror elements 30a are grouped into groups having similar shape characteristics. Divide the level. In step S22, for example, the control unit CR roughly divides into a mirror element that does not need to consider a shape error, a mirror element that should consider a shape error, and a mirror element that should not be used. Here, the mirror element that should not be used is a mirror element having an excessively large shape error, that is, a mirror element whose outer shape of the light beam deviates from a predetermined allowable range (for example, the outer shape of the light beam is too large). The mirror elements that should take into account the shape error are further classified as needed based on information such as the nature and size of the shape error.

  Further, in the classification step S20, the control unit CR classifies the plurality of mirror elements 30a according to the detection result regarding the intensity distribution of each light beam that has passed through each mirror element 30a (S23). In step S23, the control unit CR compares, for example, the intensity distribution of each light beam of each mirror element 30a in the reference state with reference information (required intensity distribution based on the design), and makes the plurality of mirror elements 30a have similar intensities. Divide into groups with characteristics. In step S23, as an example, the mirror element is roughly divided into a mirror element that does not need to consider the intensity error and a mirror element that should consider the intensity error. The mirror elements that should take into account the intensity error are further classified as required based on information such as the nature and magnitude of the intensity error.

  Finally, in the control method of the present embodiment, the postures of the plurality of mirror elements 30a of the spatial light modulator 30 are individually controlled using the classification information obtained in the classification step S20 (S30). Specifically, in the control step S30, the controller CR considers the control characteristics, shape characteristics, and intensity characteristics of each mirror element 30a, that is, considers the control error, shape error, and intensity error of each mirror element 30a. Meanwhile, the postures of the plurality of mirror elements 30a are individually controlled. In the control step S30, the light that has passed through the mirror element determined not to be used in steps S21 and S22 is guided out of the illumination optical path so as not to contribute to the illumination. In other words, in the control step S30, the control unit CR removes only the mirror element in which the change in the position of the light beam accompanying the change in posture is within the predetermined allowable range and the mirror element in which the outer shape of the light beam is in the predetermined allowable range. Control individually.

  As an example, as shown in FIG. 7, a dipole pupil intensity distribution 40 composed of two substantial surface light sources 40a and 40b spaced apart in the Y direction is formed on the illumination pupil immediately after the micro fly's eye lens 5. In this case, a light beam 41 having a relatively small cross section passing through the mirror element 30a having a relatively small shape error is incident on the outer edge region of each of the surface light sources 40a and 40b, and is relatively large via the mirror element 30a having a relatively large shape error. The postures of the plurality of mirror elements 30a may be individually controlled so that the light beam 42 having a cross section enters the central region of each of the surface light sources 40a and 40b. Such control makes it easy to obtain a desired intensity distribution for each surface light source (40a and 40b in the example of FIG. 7) without depending on the external shape of the surface light source constituting the pupil intensity distribution.

  As described above, in the illumination optical system IL of the present embodiment, the position, the outer shape, and the position of each light beam incident on the detection surface 9ba that is optically conjugate with the illumination pupil via each mirror element 30a of the spatial light modulator 30. The intensity distribution is detected as needed, and the plurality of mirror elements 30a are individually controlled using information obtained by categorizing each detection result by the detection unit 9 for each mirror element 30a. In the illumination optical system IL, the attitudes of the plurality of mirror elements 30a are individually controlled in consideration of the control error, shape error, and intensity error of each mirror element 30a. Therefore, defective mirror elements are generated in the spatial light modulator 30. However, it is possible to stably form a desired pupil intensity distribution and thus stably form a desired illumination condition. Further, in the exposure apparatus (IL, MS, PL, WS) of the present embodiment, the illumination optical system IL that stably realizes desired illumination conditions is used and is appropriately realized according to the characteristics of the pattern to be transferred. Therefore, good exposure can be stably performed under various illumination conditions.

  In the above-described embodiment, in the detection step S10, the position, outer shape, and intensity distribution of each light beam incident on the detection surface 9ba through each mirror element 30a are detected. However, the present invention is not limited to this, and it is only necessary to detect at least one of the position, the outer shape, and the intensity distribution of each light beam incident on the detection surface via each mirror element. Similarly, in the classification step S20, the position of the luminous flux, the outer shape, and the intensity distribution are classified. However, the present invention is not limited to this, and at least one of the position, the outer shape, and the intensity distribution of the light beam may be classified.

  In the above-described embodiment, the K prism 21 integrally formed with one optical block is used as the prism member having an optical surface facing the surface on which the plurality of mirror elements 30a of the spatial light modulator 30 are arranged. Used. However, the present invention is not limited to this, and a prism member having a function similar to that of the K prism 21 can be configured by a pair of prisms. In addition, a prism member having the same function as the K prism 21 can be configured by one plane-parallel plate and a pair of triangular prisms. Further, an assembly optical member having the same function as that of the K prism 21 can be constituted by one parallel plane plate and a pair of plane mirrors.

  In the above-described embodiment, the orientation (angle: inclination) of a plurality of reflection surfaces arranged two-dimensionally as a spatial light modulator having a plurality of mirror elements arranged two-dimensionally and individually controlled. A spatial light modulator that can be controlled individually 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 modulator 30 includes a plurality of mirror elements 30a arranged two-dimensionally, but instead, a plurality of elements arranged in a predetermined plane and controlled individually. It is also possible to use a transmissive spatial light modulator having the transmissive optical element.

  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. 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. 8 is a flowchart showing a semiconductor device manufacturing process. As shown in FIG. 8, in the semiconductor device manufacturing process, a metal film is vapor-deposited on a wafer W to be a substrate of the semiconductor device (step S40), and a photoresist, which is a photosensitive material, is applied on the vapor-deposited metal film. (Step S42). Subsequently, using the projection exposure apparatus of the above-described embodiment, the pattern formed on the mask (reticle) M is transferred to each shot area on the wafer W (step S44: exposure process), and the wafer W after the transfer is completed. Development, that is, development of the photoresist to which the pattern has been transferred (step S46: development process).

  Thereafter, using the resist pattern generated on the surface of the wafer W in step S46 as a mask, processing such as etching is performed on the surface of the wafer W (step S48: processing step). Here, the resist pattern is a photoresist layer in which unevenness having a shape corresponding to the pattern transferred by the projection exposure apparatus of the above-described embodiment is generated, and the recess penetrates the photoresist layer. It is. In step S48, the surface of the wafer W is processed through this resist pattern. The processing performed in step S48 includes, for example, at least one of etching of the surface of the wafer W or film formation of a metal film or the like. In step S44, the projection exposure apparatus of the above-described embodiment performs pattern transfer using the wafer W coated with the photoresist as the photosensitive substrate, that is, the plate P.

  FIG. 9 is a flowchart showing manufacturing steps of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 9, in the liquid crystal device manufacturing process, a pattern forming process (step S50), a color filter forming process (step S52), a cell assembling process (step S54), and a module assembling process (step S56) are sequentially performed. In the pattern forming process of step S50, a predetermined pattern such as a circuit pattern and an electrode pattern is formed on the glass substrate coated with a photoresist as the plate P using the 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. 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, the present invention is applied to the illumination optical system that illuminates the mask in the exposure apparatus. However, the present invention is not limited to this, and a general illumination surface other than the mask is illuminated. The present invention can also be applied to an illumination optical system.

DESCRIPTION OF SYMBOLS 1 Light source 2 Beam transmission part 3 Spatial light modulation unit 21 K prism 30 Spatial light modulator 30a Mirror element 30c Drive part 4 Relay optical system 5 Micro fly eye lens 6 Condenser optical system 7 Illumination field stop (mask blind)
8 Imaging optical system 9 Detector 9a Beam splitter 9b Photo detector IL Illumination optical system CR Control unit M Mask PL Projection optical system W Wafer

Claims (19)

In the illumination optical system that illuminates the illuminated surface based on light from the light source,
A spatial light modulator having a plurality of optical elements arranged in a predetermined plane and individually controlled, and forming a pupil intensity distribution in an illumination pupil of the illumination optical system;
A detection unit for detecting each light beam incident on a conjugate position optically conjugate with the illumination pupil via each of the plurality of optical elements;
A control unit that classifies each detection result by the detection unit for each of the plurality of optical elements, and controls the plurality of optical elements individually using the classified information. Illumination optical system. The illumination optical system according to claim 1, wherein the detection unit detects at least one of a position, an outer shape, and an intensity distribution of each light beam. The illumination optical system according to claim 2, wherein the control unit classifies at least one of a position, an outer shape, and an intensity distribution of each light beam. 4. The illumination optical system according to claim 1, wherein the control unit classifies each detection result of the detection unit by comparing with at least one reference information. 5. The detector includes a beam splitter disposed in an optical path between the spatial light modulator and the illumination pupil, and a photodetector that detects light extracted from the illumination optical path by the beam splitter. The illumination optical system according to any one of claims 1 to 4, wherein the illumination optical system is characterized in that: The spatial light modulator includes a plurality of mirror elements arranged two-dimensionally within the predetermined plane, and a drive unit that individually controls and drives the postures of the plurality of mirror elements based on a control signal from the control unit The illumination optical system according to any one of claims 1 to 5, wherein: The illumination optical system according to claim 6, wherein the driving unit continuously or discretely changes the directions of the plurality of mirror elements. 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 7. 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 9, 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 9 or 10,
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. Used with an illumination optical system that illuminates a surface to be irradiated based on light from a light source, has a plurality of optical elements that are arranged in a predetermined plane and are individually controlled, and pupil intensity at an illumination pupil of the illumination optical system In a method of controlling a spatial light modulator that forms a distribution,
Detecting each light beam incident on a conjugate position optically conjugate with the illumination pupil via each of the plurality of optical elements;
A classification step for classifying the detection results of the light beams;
And a control step of individually controlling the plurality of optical elements using information classified by the classification step. The control method according to claim 12, wherein in the detection step, at least one of a position, an outer shape, and an intensity distribution of each light beam is detected. 14. The control method according to claim 13, wherein in the classification step, at least one of a position, an outer shape, and an intensity distribution of each light beam is classified. The control method according to any one of claims 12 to 14, wherein, in the detection step, a change in position of each light beam corresponding to control of each optical element is detected. 16. The detection step according to any one of claims 12 to 15, wherein each light beam incident on the conjugate position via each optical element is simultaneously detected for each group of optical elements among the plurality of optical elements. The control method according to item. The control method according to any one of claims 12 to 16, wherein, in the classification step, the classification is performed by comparing a detection result of each light flux with at least one reference information. In the detection step, the outer shape of each light beam is detected,
The control method according to any one of claims 12 to 17, wherein in the control step, only the optical elements whose outer shape is within a predetermined allowable range are individually controlled. In the detection step, a change in position of each light beam according to the control of each optical element is detected,
The control method according to any one of claims 12 to 18, wherein, in the control step, only optical elements whose position change is within a predetermined allowable range are individually controlled.

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