JP2011222841A - Spatial light modulation unit, illumination optical system, exposure device, and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a spatial light modulation unit capable of avoiding, in a reliable manner, optical members from being damaged by light excessively condensed through multiple mirror elements.SOLUTION: A spatial light modulation unit (3), used in an illumination optical system which illuminates a surface to be illuminated with light from a light source, comprises: multiple mirror elements (30a; SEa-SEd) arranged in a predetermined plane and controlled individually; a spatial light modulator (30) in which reflection surfaces of the multiple mirror elements are formed in concave (convex) shape; and light flux conversion element (31) which converts incident light flux into divergent luminous flux (or converging luminous flux ) and guides it to the spatial light modulator.

Description

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

  In a typical exposure apparatus of this type, a secondary light source (generally an illumination pupil), which is a substantial surface light source composed of a number of light sources, passes through a fly-eye lens as an optical integrator. A predetermined light intensity distribution). Hereinafter, the light intensity distribution in the illumination pupil is referred to as “pupil intensity distribution”. The illumination pupil is defined as 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). The

  The light from the secondary light source is condensed by the condenser lens and then illuminates the mask on which a predetermined pattern is formed in a superimposed manner. The light transmitted through the mask forms an image on 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 miniaturized, and it is indispensable to obtain a uniform illuminance distribution on the wafer in order to accurately transfer the fine pattern onto the wafer.

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

JP 2002-353105 A

  In the illumination optical system described in Patent Document 1, since a spatial light modulator having a large number of mirror elements whose postures are individually controlled is used, the degree of freedom in changing the shape and size of the pupil intensity distribution is high. . However, in the spatial light modulator, for example, when the power is turned off, the reflection surfaces of all the mirror elements are aligned, and the light that has passed through the many mirror elements of the spatial light modulator is reflected on the incident surface of the fly-eye lens. The light may be excessively focused on one point of the lens, and the fly-eye lens may be damaged by the excessive light concentration.

  The present invention has been made in view of the above-described problems, and provides a spatial light modulation unit capable of reliably avoiding damage to an optical member due to excessive collection of light that has passed through a plurality of mirror elements. The purpose is to do. In addition, the present invention provides an illumination optical system capable of stably illuminating an irradiated surface under a desired illumination condition using a spatial light modulation unit that reliably avoids damage to an optical member due to excessive light energy irradiation. The purpose is to provide. 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 realizes desired illumination conditions. And

In order to solve the above-mentioned problem, according to the first aspect of the present invention, there is provided a spatial light modulation unit used in an illumination optical system that illuminates an irradiated surface with light from a light source,
A spatial light modulator having a plurality of mirror elements arranged in a predetermined plane and individually controlled, and a reflecting surface of the plurality of mirror elements formed into a curved surface;
There is provided a spatial light modulation unit comprising a light beam conversion element that converts an incident light beam into a divergent light beam or a convergent light beam and guides it to the spatial light modulator.

In the second embodiment of the present invention, in the illumination optical system that illuminates the illuminated surface based on the light from the light source,
A spatial light modulation unit of the first form;
There is provided an illumination optical system comprising: a distribution forming optical system that forms a predetermined light intensity distribution on an illumination pupil of the illumination optical system based on light that has passed through the spatial light modulation unit.

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

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

  In the spatial light modulation unit according to one aspect of the present invention, it is possible to avoid damage to the optical member due to excessive condensing of the light that has passed through the plurality of mirror elements. In the illumination optical system of the present invention, it is possible to stably illuminate the irradiated surface under a desired illumination condition by using a spatial light modulation unit that reliably avoids damage to the optical member due to excessive light energy irradiation. The exposure apparatus of the present invention can stably perform good exposure under appropriate illumination conditions using an illumination optical system that stably realizes desired illumination conditions, and thus manufactures a good device. can do.

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 figure which shows a mode that it condenses to one point on the entrance plane of a fly eye lens, if the direction of a mirror element aligns in a prior art. It is a figure which shows a mode that a divergent light beam injects into the concave reflective surface of each mirror element, and is converted into a parallel light beam in this embodiment. It is a figure which shows a mode that the illumination field which has a certain amount of breadth in the entrance plane of a fly eye lens is formed even if the direction of a mirror element is equal in this embodiment. 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.) due to the action of the spatial light modulation unit 3. 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, and a micro fly's eye lens (or fly eye lens) 5. A condenser optical system 6, an illumination field stop (mask blind) 7, and an imaging optical system 8. 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.

  With reference to FIG. 2 and FIG. 3, the internal configuration and operation of the spatial light modulation unit 3 will be described. As shown in FIG. 2, the spatial light modulation unit 3 includes, in order from the light incident side, a lens group 31 that includes one or a plurality of lenses and has an overall negative refractive power, a prism 32, and a prism 32. And a spatial light modulator 30 disposed close to the side surface 32a parallel to the YZ plane. The lens group 31 and the prism 32 are made of an optical material such as fluorite or quartz.

  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 32 replaces one side surface of the rectangular parallelepiped (a surface opposite to the side surface 32a on which the plurality of mirror elements 30a of the spatial light modulator 30 are arranged close to each other) with side surfaces 32b and 32c that are recessed in a V shape. It is also called a K prism because of the cross-sectional shape along the XZ plane. Side surfaces 32b and 32c of the prism 32 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 32b and 32c that are in contact with a tangent line (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 reflection surfaces R1 and R2 is 120 degrees, the angle between the incident surface IP of the prism 32 perpendicular to the optical axis AX and the reflection surface R1 is 60 degrees, and the prism 32 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 32, the side surface 32a 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 reflecting surface R1 of the prism 32 reflects the 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 32 reflects the light incident through the spatial light modulator 30 and guides it to the relay optical system 4 through the exit surface OP.

  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.

  Hereinafter, in order to facilitate understanding, the basic operation of the spatial light modulation unit 3 will be described with the cooperation of the lens group 31 and the spatial light modulator 30 ignored. Referring to FIG. 2, among the light beams that have entered the spatial light modulation unit 3 and passed through the lens group 31, the light beam L1 is different from the mirror element SEa of the plurality of mirror elements 30a, and the light beam L2 is different from the mirror element SEa. Each is incident on the mirror element SEb. Similarly, the light beam L3 is incident on a mirror element SEc different from the mirror elements SEa and SEb, and the light beam L4 is incident on a mirror element SEd different from the mirror elements SEa to SEc. The mirror elements SEa to SEd give spatial modulations set according to their positions to the lights L1 to L4.

  The 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 30 a regularly and two-dimensionally arranged along one plane with the reflecting surface as an upper surface, for example. It is a 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) is 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 rotate continuously or discretely by a desired rotation angle with two directions (Y direction and Z direction) parallel to the arrangement plane 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 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. Another illumination pupil position optically conjugate with the rear focal position of the micro fly's eye lens 5 or 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 (of the aperture stop AS) At the position), 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.

  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, the pupil intensity distribution formed by the action of the spatial light modulator 30 is obtained using 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. It can be freely and quickly changed, and thus various illumination conditions can be realized.

  In the illumination optical system described in Patent Document 1, as shown in FIG. 4, the plurality of mirror elements 40a of the spatial light modulator 40 have a planar reflecting surface and correspond to the lens group 31 of the present embodiment. The optical member to be operated is not disposed on the incident side of the spatial light modulator 40. Therefore, when the direction of each mirror element 40a of the spatial light modulator 40 is aligned for some reason (that is, when the plurality of mirror elements 40a are in parallel with each other), the parallel light beams incident on each mirror element 40a are relay optical system 41. Then, the light is condensed at one point on the incident surface 42a of the fly-eye lens 42, and the fly-eye lens 42 may be damaged by excessive light energy irradiation.

  Specifically, when electricity is not passed to the spatial light modulator 40, or when the mirror element 40a of the spatial light modulator 40 becomes uncontrollable, each mirror element of the spatial light modulator 40 is used. It is conceivable that the directions of 40a are aligned. In FIG. 4, in order to clarify the drawing and facilitate understanding of the explanation, the optical path between the spatial light modulator 40 and the micro fly's eye lens 42 is developed linearly, and the spatial light modulator 40 is used. The illustration of the incident light on is omitted.

  In this embodiment, a lens group 31 having a negative refractive power is attached to the incident side of the spatial light modulator 30, and the reflecting surface of each mirror element 30a of the spatial light modulator 30 is formed in a concave shape (for example, a concave spherical shape). is doing. In this case, the parallel light beam incident on the spatial light modulation unit 3 is converted into a divergent light beam by the action of the negative refractive power of the lens group 31 and is guided to the spatial light modulator 30. As a result, as shown in FIG. 5, the divergent light beam incident on each mirror element 30 a is converted into a substantially parallel light beam by the power of the concave reflecting surface and guided to the relay optical system 4.

  FIG. 5 shows a state in which the directions of the three mirror elements 30a having the same concave spherical reflecting surface are aligned, that is, a state in which the normal directions at the centers of the reflecting surfaces of the three mirror elements 30a are parallel to each other. Show. The condition for the divergent light beam from the virtual point 51 set on the lens group 31 side of negative refractive power to enter the mirror element 30a and be converted into a parallel light beam is the distance from the virtual point 51 to the array surface of the mirror element 30a. D is set equal to about ½ of the radius of curvature R of the concave spherical reflecting surface of the mirror element 30a.

  In the present embodiment, even if the directions of the three mirror elements 30a are aligned, the incident angles of divergent light beams that are obliquely incident on the mirror elements 30a (that is, the angle at which the center line of the divergent light beams becomes the normal of the array surface) are different from each other. Therefore, the traveling directions of the three light beams generated through the reflecting surfaces of the mirror elements 30a are not parallel to each other. As a result, as shown in FIG. 6 corresponding to FIG. 4, the parallel light beam generated through each mirror element 30 a spreads to some extent on the incident surface 5 a of the micro fly's eye lens 5 through the relay optical system 4. The illuminating field 61 is formed. In FIG. 6, the traveling directions of the light beams seem to be parallel to each other, but they are not actually parallel. The size of the illumination field 61 depends on the size of the maximum angle of the divergent light beam incident on the spatial light modulator 30, that is, all of the mirror elements 30a.

  On the other hand, in the prior art described in Patent Document 1, parallel light beams are obliquely incident on the planar reflection surface of each mirror element 40a. Therefore, when the directions of the mirror elements 40a are aligned, the light is generated through the reflection surface. The traveling directions of the parallel light beams are parallel to each other. As a result, the parallel light beam generated through each mirror element 40 a is condensed at one point on the incident surface 42 a of the fly-eye lens 42 through the relay optical system 41. 4 shows a state in which the reflecting surfaces of the mirror elements 40a are parallel to each other in a posture inclined with respect to the arrangement surface, the reflection surfaces of the mirror elements 40a are in a state parallel to the arrangement surface. When they are aligned, the light is condensed at the intersection of the incident surface 42a of the fly-eye lens 42 and the optical axis AX.

  As described above, in the spatial light modulation unit 3 of the present embodiment, the reflection surface of each mirror element 30a of the spatial light modulator 30 is formed in a concave shape, and the light beam incident on the lens group 31 as a light beam conversion element is received. The light is converted into a divergent light beam and guided to the spatial light modulator 30. As a result, even if the direction of each mirror element 30a of the spatial light modulator 30 is aligned for some reason, the light flux reaching the incident surface 5a of the micro fly's eye lens 5 via each mirror element 30a and the relay optical system 4 is It has a certain degree of spread, and it is possible to reliably avoid damage to the micro fly's eye lens 5 due to excessive light energy irradiation.

  That is, in the spatial light modulation unit 3 of the present embodiment, it is possible to reliably avoid damage to the micro fly's eye lens 5 due to excessive condensing of light that has passed through the plurality of mirror elements 30a. In the illumination optical system IL of the present embodiment, the pattern surface (irradiated surface) of the mask M is desired using the spatial light modulation unit 3 that reliably avoids damage to the micro fly's eye lens 5 due to excessive light energy irradiation. Illumination can be stably performed under illumination conditions. In the exposure apparatus (IL, MS, PL, WS) of this embodiment, appropriate illumination realized according to the characteristics of the pattern to be transferred using the illumination optical system IL that stably realizes desired illumination conditions. Good exposure can be stably performed under the conditions.

  In the above-described embodiment, the lens group 31 that functions as a light beam conversion element that converts an incident light beam into a divergent light beam and guides it to the spatial light modulator 30 is used, and the reflecting surface of each mirror element 30a is formed in a concave shape. is doing. However, the present invention is not limited to this, and by using a light beam conversion element that converts an incident light beam into a convergent light beam and guides it to a spatial light modulator, and forming the reflecting surface of each mirror element in a convex shape, The same effect as the embodiment can be obtained. In this case, as the light beam conversion element, for example, a lens group including one or a plurality of lenses and having a positive refractive power as a whole can be used.

  Further, in the above-described embodiment, the K prism 32 integrally formed with one optical block is used as the prism member having the optical surface facing the arrangement surface of the plurality of mirror elements 30a of the spatial light modulator 30. Yes. However, the prism member having the same function as that of the K prism 32 can be configured by a pair of prisms without being limited thereto. In addition, a prism member having the same function as the K prism 32 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 32 can be constituted by one parallel plane plate and a pair of plane mirrors.

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

  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, 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. 7 is a flowchart showing a semiconductor device manufacturing process. As shown in FIG. 7, 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. 8 is a flowchart showing a manufacturing process of a liquid crystal device such as a liquid crystal display element. As shown in FIG. 8, 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, etc.), micromachine, thin film magnetic head, and DNA chip. Furthermore, the present invention can also be applied to an exposure process (exposure apparatus) when manufacturing a mask (photomask, reticle, etc.) on which mask patterns of various devices are formed using a photolithography process.

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

  In the above-described embodiment, a so-called immersion method is applied in which the optical path between the projection optical system and the photosensitive substrate is filled with a medium (typically liquid) having a refractive index larger than 1.1. You may do it. In this case, as a 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 30 Spatial light modulator 30a Mirror element 30c Drive part 31 Lens group (light beam conversion element)
32 K prism 4 relay optical system 5 micro fly's eye lens 6 condenser optical system 7 illumination field stop (mask blind)
8 Imaging optical system IL Illumination optical system CR Control unit M Mask PL Projection optical system W Wafer

Claims (13)

A spatial light modulation unit used in an illumination optical system that illuminates a surface to be irradiated with light from a light source,
A spatial light modulator having a plurality of mirror elements arranged in a predetermined plane and individually controlled, and a reflecting surface of the plurality of mirror elements formed into a curved surface;
A spatial light modulation unit comprising: a light beam conversion element that converts an incident light beam into a divergent light beam or a convergent light beam and guides the light beam to the spatial light modulator. The spatial light modulation unit according to claim 1, wherein the light beam conversion element converts an incident light beam into a divergent light beam, and the plurality of mirror elements have concave reflection surfaces. The spatial light modulation unit according to claim 1, wherein the light beam conversion element converts an incident light beam into a convergent light beam, and the plurality of mirror elements have convex reflecting surfaces. The spatial light modulator includes: the 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. Item 4. The spatial light modulation unit according to any one of Items 1 to 3. The spatial light modulation unit according to claim 4, wherein the driving unit continuously or discretely changes directions of the plurality of mirror elements. The spatial light modulation unit according to claim 1, wherein the light beam conversion element has one or a plurality of lenses. 7. The optical system according to claim 1, wherein the optical system is used together with a distribution forming optical system that forms a predetermined light intensity distribution in an illumination pupil of the illumination optical system based on light that has passed through the spatial light modulation unit. The spatial light modulation unit described in 1. In the illumination optical system that illuminates the illuminated surface based on the light from the light source,
The spatial light modulation unit according to any one of claims 1 to 7,
An illumination optical system comprising: a distribution forming optical system that forms a predetermined light intensity distribution on an illumination pupil of the illumination optical system based on light that has passed through the spatial light modulation unit. 9. The illumination optical system according to claim 8, wherein the distribution forming optical system includes an optical integrator and a condensing optical system disposed in an optical path between the optical integrator and the spatial light modulation unit. system. 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 8 or 9. An exposure apparatus comprising the illumination optical system according to any one of claims 8 to 10 for illuminating a predetermined pattern, and exposing the predetermined pattern onto a photosensitive substrate. 12. The exposure apparatus according to claim 11, 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 11 or 12,
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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