Light source unit, illumination unit, exposure device, and exposure method

Abstract

The purpose of the present invention is to, by inhibiting warpage or bending of a substrate on which light source elements are arranged, improve adhesion between the substrate and a heat sink and increase cooling efficiency.　This light source unit comprises: a substrate (21A) that has a first surface and a second surface that are opposite each other; a plurality of light source elements (20A) that are two-dimensionally arranged on the first surface of the substrate (21A); and a heat sink (40). The substrate (21A) has at least one recess formed in a portion of the second surface opposing a range in which the plurality of light source elements (20A) are arranged in a plan view. The heat sink (40) has a through hole (401). The substrate (21A) and the heat sink (40) are fixed together by a fixing member (61) that is inserted through the through hole (401) and is fitted into the recess.

Description

Light source unit, illumination unit, exposure apparatus, and exposure method

[0001] The present invention relates to a light source unit, an illumination unit, an exposure apparatus, and an exposure method.

[0002] In recent years, liquid crystal display panels have come into widespread use as display elements for personal computers, televisions, and other devices. Liquid crystal display panels are manufactured by forming a thin-film transistor circuit pattern on a plate (glass substrate) using photolithography. An exposure apparatus is used for this photolithography process, which projects and exposes an original pattern formed on a mask onto a photoresist layer on the plate via a projection optical system.

[0003] It has been proposed to use a light source using a light emitting diode in various optical devices including the above-mentioned exposure device (for example, Patent Document 1).

[0004] Japanese Patent Application Laid-Open No. 2006-201476

[0005] According to a first aspect of the disclosure, the light source unit comprises a substrate having a first surface and a second surface facing each other, a plurality of light source elements arranged two-dimensionally on the first surface of the substrate, and a heat sink, wherein the substrate has at least one recess formed in a portion of the second surface that faces the range in which the plurality of light source elements are arranged in a planar view, the heat sink has a through hole, and the substrate and the heat sink are fixed by a fixing member that passes through the through hole and fits into the recess.

[0006] According to a second aspect of the disclosure, an illumination unit includes the light source unit and an illumination optical system that guides light emitted from the light source unit to an object to be illuminated.

[0007] According to a third aspect of the disclosure, the lighting unit comprises a plurality of the above-mentioned light source units, and an illumination optical system including a combining optical element that combines light emitted from the plurality of light source units and directs the combined light emitted from the combining optical element to an illuminated object.

[0008] According to a fourth aspect of the disclosure, an exposure apparatus includes the above-mentioned illumination unit and a projection optical system that projects a pattern image of a mask illuminated by the illumination unit onto a photosensitive substrate.

[0009] According to a fifth aspect of the disclosure, an exposure method is an exposure method using the above-mentioned exposure apparatus, and includes illuminating a mask with the illumination unit and projecting a pattern image of the mask onto a photosensitive substrate using the projection optical system.

[0010] The configurations of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not particularly limited in terms of their placement may be placed in any position that can achieve their function, not limited to the placement disclosed in the embodiments.

[0011] FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of an illumination unit. FIG. 3A is a front view of first and second light source arrays, and FIG. 3B is a cross-sectional view taken along line A-A in FIG. 3A. FIG. 4 is a rear view of a substrate. FIG. 5 is a perspective view showing a heat sink and a first light source array. FIG. 6 is a perspective view showing the -Z1 side of the heat sink. FIG. 7A is a front view showing a heat sink and a first light source array, and FIG. 7B is a cross-sectional view taken along line A-A in FIG. 7A. FIG. 8 is a diagram for explaining first and second magnifying optical systems. FIG. 9A is a front view showing a heat sink and a light source array according to a comparative example, and FIG. 9B is a cross-sectional view taken along line A-A in FIG. 9A. FIG. 10 is a diagram showing measurement results of the surface temperature of a substrate. FIG. 11 is a cross-sectional view for explaining a modified example.

[0012] An exposure apparatus 10 according to one embodiment will be described with reference to FIGS.

[0013] (Configuration of Exposure Apparatus) First, the configuration of an exposure apparatus 10 according to one embodiment will be described using Fig. 1. Fig. 1 is a diagram that shows schematically the configuration of an exposure apparatus 10 according to one embodiment.

[0014] The exposure apparatus 10 is a scanning stepper (scanner) that drives a mask MSK and a glass substrate (hereinafter referred to as "plate") P in the same direction and at the same speed relative to a projection optical system PL, thereby transferring a pattern formed on the mask MSK onto the plate P. The plate P is a rectangular glass substrate used in, for example, a liquid crystal display device (flat panel display), and has at least one side or diagonal length of 500 mm or more.

[0015] In the following, the direction in which the mask MSK and plate P are driven during scanning exposure (scanning direction) is referred to as the X-axis direction, the direction in the horizontal plane perpendicular to this is referred to as the Y-axis direction, the direction perpendicular to the X-axis and Y-axis is referred to as the Z-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are referred to as the θx, θy, and θz directions, respectively.

[0016] The exposure apparatus 10 includes an illumination system IOP, a mask stage MST that holds a mask MSK, a projection optical system PL, a body 70 that supports these, a substrate stage PST that holds a plate P, and a control system for these. The control system provides overall control of each component of the exposure apparatus 10.

[0017] The body 70 includes a base (vibration isolation table) 71, columns 72A and 72B, an optical surface plate 73, a support 74, and a slide guide 75. The base (vibration isolation table) 71 is placed on a floor F and supports the columns 72A, 72B, etc., while isolating vibrations from the floor F. The columns 72A and 72B each have a frame shape, with the column 72A being placed inside the column 72B. The optical surface plate 73 has a flat plate shape and is fixed to the ceiling of the column 72A. The support 74 is supported by the ceiling of the column 72B via a slide guide 75. The slide guide 75 includes an air ball lifter and a positioning mechanism, and positions the support 74 (i.e., the mask stage MST, described later) at an appropriate position in the X-axis direction relative to the optical surface plate 73.

[0018] The illumination system IOP is disposed above the body 70. The illumination system IOP irradiates the mask MSK with illumination light IL. The detailed configuration of the illumination system IOP will be described later.

[0019] The mask stage MST is supported by a support 74. A mask MSK having a pattern surface (the lower surface in FIG. 1 ) on which a circuit pattern is formed is fixed to the mask stage MST by, for example, vacuum suction (or electrostatic suction). The mask stage MST is driven by a drive system including, for example, a linear motor at a predetermined stroke in the scanning direction (X-axis direction), and is also driven slightly in the non-scanning directions (Y-axis direction and θz direction).

[0020] Position information of the mask stage MST in the XY plane (including rotation information in the θz direction) is measured by an interferometer system. The interferometer system measures the position of the mask stage MST by irradiating a measurement beam onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the mask stage MST and receiving the light reflected from the movable mirror. The measurement results are supplied to a control device (not shown), which drives the mask stage MST via a drive system in accordance with the measurement results of the interferometer system.

[0021] The projection optical system PL is supported on an optical surface plate 73 below (on the -Z side of) the mask stage MST. The projection optical system PL is configured similarly to the projection optical system disclosed in, for example, U.S. Pat. No. 5,729,331. The projection optical system PL includes multiple (e.g., seven) projection optical units 100 (multi-lens projection optical units) arranged, for example, in a staggered pattern, to project the pattern image of the mask MSK. This forms a rectangular image field with the Y-axis direction as its longitudinal direction. Here, four projection optical units 100 are arranged at predetermined intervals in the Y-axis direction, and the remaining three projection optical units 100 are arranged at predetermined intervals in the Y-axis direction, spaced apart from the four projection optical units 100 on the +X side. Each of the multiple projection optical units 100 is, for example, a bilaterally telecentric, 1x1 system that forms an erect, normal image. The multiple projection areas of the staggered projection optical units 100 are collectively referred to as the exposure area.

[0022] When an illumination area on the mask MSK is illuminated by illumination light IL from the illumination system IOP, the illumination light IL that has passed through the mask MSK forms a projected image (partial erect image) of the circuit pattern of the mask MSK within that illumination area, via the projection optical system PL, in an irradiation area (exposure area (conjugate to the illumination area)) on a plate P arranged on the image plane side of the projection optical system PL. Here, a resist (sensitizer) is applied to the surface of the plate P. By synchronously driving the mask stage MST and the substrate stage PST, i.e., by driving the mask MSK in the scanning direction (X-axis direction) relative to the illumination area (illumination light IL) and driving the plate P in the same scanning direction relative to the exposure area (illumination light IL), the plate P is exposed and the pattern of the mask MSK is transferred onto the plate P.

[0023] The substrate stage PST is placed on a base (vibration isolation table) 71 below (on the -Z side of) the projection optical system PL. A plate P is held on the substrate stage PST via a substrate holder (not shown).

[0024] Position information of the substrate stage PST in the XY plane (including rotation information (yawing amount (rotation amount θz in the θz direction), pitching amount (rotation amount θx in the θx direction), and rolling amount (rotation amount θy in the θy direction))) is measured by an interferometer system. The interferometer system measures the position of the substrate stage PST by irradiating a measurement beam from the optical surface plate 73 onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the substrate stage PST, and receiving the reflected light from the movable mirror. The measurement results are supplied to a control device (not shown), and the control device drives the substrate stage PST in accordance with the measurement results of the interferometer system.

[0025] In exposure apparatus 10, alignment measurement (e.g., EGA, etc.) is performed prior to exposure, and the plate P is exposed using the results in the following procedure. First, in accordance with instructions from the control device, the mask stage MST and substrate stage PST are synchronously driven in the X-axis direction. This performs scanning exposure on the first shot area on plate P. When scanning exposure on the first shot area is completed, the control device moves (steps) the substrate stage PST to a position corresponding to the second shot area. Then, scanning exposure is performed on the second shot area. In the same manner, the control device repeats stepping between shot areas of plate P and scanning exposure on the shot areas to transfer the pattern of the mask MSK to all shot areas on plate P.

[0026] (Configuration of illumination system IOP) Next, the configuration of illumination system IOP in this embodiment will be described. Illumination system IOP includes a plurality of illumination units 90 corresponding to the plurality of projection optical units 100 included in projection optical system PL. Figure 2 is a diagram schematically showing the configuration of illumination unit 90.

[0027] The illumination unit 90 includes a first light source unit OPU1, a second light source unit OPU2, and an illumination optical system 80.

[0028] (Configuration of light source unit) The first light source unit OPU1 includes a heat sink 40, a first light source array 20A, and a first magnifying optical system 30A, and the second light source unit OPU2 includes a heat sink 40, a second light source array 20B, and a second magnifying optical system 30B.

[0029] Fig. 3(A) is a front view schematically showing the configuration of the first light source array 20A and the second light source array 20B, and Fig. 3(B) is a cross-sectional view taken along line A-A in Fig. 3(A). Note that hatching of LED chips 23A and 23B, which will be described later, is omitted in Fig. 3(B).

[0030] 3A, the first light source array 20A includes a substrate 21A and a plurality of LED (Light Emitting Diode) chips 23A (5×5 in FIG. 3A) arranged two-dimensionally on the substrate 21A. The number of LED chips 23A may be changed as needed.

[0031] The substrate 21A has a first surface 21a and a second surface 21b facing each other, and the LED chips 23A are arranged on the first surface 21a. The LED chips 23A are arranged at a pitch P1, which is the distance between the centers of adjacent LED chips 23A.

[0032] Each of the multiple LED chips 23A has a light-emitting portion 231A, and the peak wavelength of the light emitted from the light-emitting portion 231A is in the range of 380 to 390 nm. In other words, the light-emitting portion 231A is an ultraviolet LED (UV LED). It is more preferable that the peak wavelength of the light emitted from the light-emitting portion 231A is 385 nm. The light-emitting surface of the light-emitting portion 231A is square, and the length of one side is a1. In the following description, the two directions in which the LED chips 23A are arranged are referred to as the X1 direction and the Y1 direction. The X1 direction and the Y1 direction are orthogonal to each other. The direction orthogonal to the X1 direction and the Y1 direction is referred to as the Z1 direction. The Z1 direction is approximately parallel to the optical axis of the light emitted by the light-emitting portion 231A.

[0033] The second light source array 20B includes a substrate 21B and a plurality of LED chips 23B (5 x 5 in FIG. 3A) arranged two-dimensionally on the substrate 21B. The number of LED chips 23B may be changed as needed. The substrate 21B also has a first surface 21a and a second surface 21b facing each other, and the LED chips 23B are arranged on the first surface 21a. The LED chips 23B are arranged at a pitch P2, which is the distance between the centers of adjacent LED chips 23B. The arrangement pitch P1 of the LED chips 23A and the arrangement pitch P2 of the LED chips 23B may be the same or different.

[0034] Each of the multiple LED chips 23B has a light-emitting portion 231B, and the peak wavelength of the light emitted from the light-emitting portion 231B is in the range of 360 to 370 nm. In other words, the light-emitting portion 231B is a UV LED. It is more preferable that the peak wavelength of the light emitted from the light-emitting portion 231B is 365 nm. The light-emitting surface of the light-emitting portion 231B is square, and the length of one side is a2. The length a2 of one side of the light-emitting surface of the light-emitting portion 231B may be the same as or different from the length a1 of one side of the light-emitting surface of the light-emitting portion 231A.

[0035] FIG. 4 is a rear view of the substrates 21A and 21B. The substrates 21A and 21B are metal substrates with a thickness of 5 mm or less. The substrates 21A and 21B are preferably made of a material with high thermal conductivity, such as a copper substrate. As shown in FIGS. 3B and 4 , a plurality of recesses 211 (3×3 in FIG. 4 ) are formed in a portion AR1 of the second surface 21b of the substrates 21A and 21B, which is opposite the first surface 21a of the substrates 21A and 21B and faces the area in which the plurality of LED chips 23A and 23B are arranged in a plan view. In this embodiment, the recesses 211 are arranged at equal intervals in both the X1 and Y1 directions.

[0036] 3B, the recesses 211 do not penetrate the substrates 21A and 21B. In this embodiment, the recesses 211 are screw holes, and as will be described in detail later, the substrates 21A and 21B can be fixed to the heat sink 40 by engaging bolts 61 with the recesses 211.

[0037] FIG. 5 is a perspective view showing the heat sink 40 and the first light source array 20A, and FIG. 6 is a perspective view showing the -Z1 side of the heat sink 40. FIG. 7A is a front view showing the heat sink 40 and the first light source array 20A, and FIG. 7B is a cross-sectional view taken along line A-A in FIG. 7A. The relationship between the second light source array 20B and the heat sink 40 is the same as the relationship between the first light source array 20A and the heat sink 40, so the following description will focus on the heat sink 40 and the first light source array 20A. Note that FIG. 5 illustrates, as an example, a case where the first light source array 20A includes 10 × 14 LED chips 23A. Furthermore, hatching of the LED chips 23A is omitted in FIG. 7B.

[0038] 5 and 7A, in this embodiment, three first light source arrays 20A are arranged on the heat sink 40. Note that the number of first light source arrays 20A arranged on the heat sink 40 is not limited to three, and may be two or less, or four or more. In other words, it is sufficient that at least one first light source array 20A is arranged on the heat sink 40.

[0039] As shown in FIG. 6 , the heat sink 40 has a flow path 402 through which a coolant flows, a supply port 41 for supplying the coolant to the flow path 402, and an outlet port 42 for discharging the coolant that has passed through the flow path 402, and cools the LED chips 23A included in the first light source array 20A. The coolant may be liquid or gas, but is preferably water. The brightness of the light emitted from the light-emitting unit 231A included in the LED chip 23A decreases as the temperature of the LED chip 23A increases. In other words, the light-emitting efficiency of the LED chip 23A decreases as the temperature increases. By cooling the LED chip 23A with the heat sink 40, it is possible to suppress a decrease in the brightness of the light emitted from the first light source array 20A.

[0040] 6 and 7B, the heat sink 40 has a through hole 401 penetrating the heat sink 40. The through hole 401 is a stepped through hole whose diameter changes in two stages. A flow path 402 inside the heat sink 40 is formed in a portion where the through hole 401 is not formed. The through hole 401 is provided at a position corresponding to a recess 211 provided in the second surface 21b of the substrate 21A included in the first light source array 20A.

[0041] As shown in FIG. 7B , a thermally conductive member 50 such as a Thermal Interface Material (TIM) is provided between the substrate 21A and the heat sink 40. In this embodiment, a thermally conductive sheet is used as the thermally conductive member 50. The thermally conductive member 50 may be thermally conductive grease or the like. The thermally conductive member 50 is provided so as to contact at least a portion AR1 of the second surface 21b of the substrate 21A that corresponds to the range in which the LED chips 23A are arranged. This fills small gaps and irregularities between the substrate 21A and the heat sink 40, allowing the heat sink 40 to efficiently cool the LED chips 23A.

[0042] The heat sink 40 and the substrate 21A are fixed by bolts 61 that pass through the through holes 401 and engage (fit) into the recesses 211. The bolts 61 pass through the thermally conductive member 50. The length of the bolts 61 is set so that they penetrate the thermally conductive member 50 and bring the heat sink 40 and the substrate 21A and the thermally conductive member 50 into close contact with each other. This allows the heat sink 40 to cool the LED chips 23A more efficiently. In this embodiment, a thermally conductive member 50 is provided corresponding to each first light source array 20A. However, for example, one sheet-like thermally conductive member 50 may be provided for three first light source arrays 20A.

[0043] Next, the first magnifying optical system 30A and the second magnifying optical system 30B will be described. Fig. 8 is a diagram for explaining the first magnifying optical system 30A and the second magnifying optical system 30B provided in the first light source unit OPU1 and the second light source unit OPU2, respectively.

[0044] As shown in FIG. 8 , the first magnifying optical system 30A is a magnifying optical system for forming a magnified image of the light-emitting portion 231A of each LED chip 23A on a predetermined plane PP. The first magnifying optical system 30A includes a plurality of lens units 31A arranged to correspond to the arrangement of the LED chips 23A. Each lens unit 31A is a double-telecentric optical system that magnifies and projects the light-emitting portion 231A at a magnification M1 equal to or greater than (the arrangement pitch P1 of the LED chips 23B) / (the length a1 of one side of the light-emitting surface of the light-emitting portion 231A). For clarity of illustration, FIG. 8 shows only four LED chips 23A (23B) arranged in a row along the Y1 direction.

[0045] The second magnifying optical system 30B is an optical system for forming a magnified image of the light-emitting portion 231B of each LED chip 23B on a predetermined plane PP. The second magnifying optical system 30B includes a plurality of lens units 31B arranged to correspond to the arrangement of the LED chips 23B. Each of the lens units 31B is a double-telecentric optical system that magnifies and projects the light-emitting portion 231B at a magnification M2 that is equal to or greater than (the arrangement pitch P2 of the LED chips 23A) / (the length a2 of one side of the light-emitting surface of the light-emitting portion 231B).

[0046] In this embodiment, each of the lens units 31A and 31B includes four plano-convex lenses, but this is not limiting, and the lens units 31A and 31B may include, for example, two biconvex lenses, three biconvex lenses, or a plano-convex lens and a biconvex lens.

[0047] (Configuration of illumination optical system 80) Returning to Figure 2, the illumination optical system 80 includes a first focusing optical system (first optical system) 81A including a first dichroic mirror DM1, a second focusing optical system (second optical system) 81B, a second dichroic mirror DM2, an imaging optical system 83, a fly's eye lens FEL, and a condenser optical system 84.

[0048] The first focusing optical system 81A forms a pupil of the magnified image of the light-emitting unit 231A formed by the first magnifying optical system 30A. That is, the rear focal position of the first focusing optical system 81A is the pupil position. The first focusing optical system 81A has a first dichroic mirror DM1 along the optical path, which reflects at least a portion of the light with a peak wavelength of 385 nm. This causes the light beam to be incident on the second dichroic mirror DM2. Note that the first focusing optical system 81A may be configured without the first dichroic mirror DM1. In this case, the arrangement of the first light source unit OPU1 and the arrangement of each lens in the first focusing optical system 81A may be appropriately adjusted so that the light beam is incident on the second dichroic mirror DM2. Furthermore, the first focusing optical system 81A may be configured with a single lens or a lens group including multiple lenses.

[0049] The second focusing optical system 81B forms a pupil of the magnified image of the light-emitting unit 231B formed by the second magnifying optical system 30B. That is, the rear focal position of the second focusing optical system 81B is the pupil position. The second focusing optical system 81B may be composed of a single lens or a lens group including multiple lenses.

[0050] The second dichroic mirror DM2 transmits at least a portion of the light with a peak wavelength of 385 nm and reflects at least a portion of the light with a peak wavelength of 365 nm, thereby forming a composite image by superimposing the pupil image formed by the first focusing optical system 81A and the pupil image formed by the second focusing optical system 81B.

[0051] In this embodiment, the second dichroic mirror DM2 forms a composite image by superimposing the pupil image formed by the first focusing optical system 81A and the pupil image formed by the second focusing optical system 81B. That is, the second dichroic mirror DM2 is disposed at a position that is the back focal position of the first focusing optical system 81A and the back focal position of the second focusing optical system 81B. As a result, the second dichroic mirror DM2 Koehler-illuminates the light emitted from the first light source unit OPU1 and the light emitted from the second light source unit OPU2. By Koehler-illuminating the light, it is possible to reduce changes in the illuminance of the light beam of the pupil image formed by the first focusing optical system 81A and the second focusing optical system 81B. In addition, without being limited to the configuration of this embodiment, the first focusing optical system 81A and the second focusing optical system 81B may be configured to perform critical illumination that forms an image of the first light source unit OPU1 and an image of the second light source unit OPU2 on the second dichroic mirror DM2, respectively.

[0052] The illumination unit 90 is provided with a detector DT10 for monitoring light with a peak wavelength of 385 nm, a detector DT20 for monitoring light with a peak wavelength of 365 nm, and a detector DT30 for monitoring light with a peak wavelength of 385 nm and light with a peak wavelength of 365 nm.

[0053] Specifically, detector DT10 detects the illuminance of light with a peak wavelength of 385 nm reflected by first dichroic mirror DM1. Detector DT20 detects the illuminance of light with a peak wavelength of 365 nm reflected by second dichroic mirror DM2. Detector DT30 detects the illuminance of 385 nm light unintentionally reflected by second dichroic mirror DM2 and the illuminance of 365 nm light unintentionally transmitted by second dichroic mirror DM2.

[0054] The detection results of detectors DT10 to DT30 are output to a control device not shown, and the control device controls the value of the current supplied to the LED chips 23A and 23B provided in the first light source unit OPU1 and the second light source unit OPU2, respectively, based on the detection results of detectors DT10 to DT30.

[0055] The imaging optical system 83 is a double-telecentric optical system that projects the composite image formed by the second dichroic mirror DM2 onto the incident end of the fly-eye lens FEL at an equal magnification. Note that the imaging optical system 83 may also reduce and project the composite image formed by the second dichroic mirror DM2 onto the incident end of the fly-eye lens FEL.

[0056] The fly-eye lens FEL is formed by closely arranging a large number of lens elements, each having a positive refractive power, in a row and column so that their optical axes are parallel to the reference optical axis AX. Each lens element constituting the fly-eye lens FEL has a rectangular cross section similar to the shape of the illumination field to be formed on the mask MSK (and consequently the shape of the exposure area to be formed on the plate P).

[0057] Therefore, the light beam incident on the fly-eye lens FEL is wavefront split by the multiple lens elements, and one light source image is formed on or near the rear focal plane (exit surface) of each lens element. That is, a substantial surface light source, i.e., a secondary light source, consisting of multiple light source images is formed on or near the rear focal plane (exit surface) of the fly-eye lens FEL. The light beam from the secondary light source formed on or near the rear focal plane (exit surface) of the fly-eye lens FEL is incident on an aperture stop 85 arranged nearby. Note that in this embodiment, the rear focal plane (exit surface) of the fly-eye lens FEL is optically conjugate with the first light source array 20A and the second light source array 20B.

[0058] The aperture stop 85 is disposed at a position that is nearly optically conjugate with the entrance pupil plane of the projection optical system PL, and has a variable opening for defining the range that contributes to illumination from the secondary light source. The aperture stop 85 changes the aperture diameter of the variable opening to set the σ value (the ratio of the aperture diameter of the secondary light source image on the pupil plane of the projection optical system to the aperture diameter of the pupil plane) that determines the illumination conditions to a desired value. The light from the secondary light source that passes through the aperture stop 85 is subjected to the focusing action of the condenser optical system 84, and then illuminates a mask MSK on which a predetermined pattern is formed in a superimposed manner.

[0059] The wavelengths of the light emitted by the first light source unit OPU1 and the second light source unit OPU2 are not limited to those described above, and the first light source unit OPU1 and the second light source unit OPU2 may be configured by appropriately combining LED chips that emit light having a peak wavelength in the range of 360 to 440 nm. For example, the first light source unit OPU1 may be configured to emit light with a peak wavelength of 405 nm, and the second light source unit OPU2 may be configured to emit light with a peak wavelength of 385 nm. Alternatively, the first light source unit OPU1 may be configured to emit light with a peak wavelength of 395 nm, and the second light source unit OPU2 may be configured to emit light with a peak wavelength of 385 nm. The combination of the wavelengths of the light emitted by the first light source unit OPU1 and the second light source unit OPU2 is not limited to these examples. In addition, if the combination of the wavelength of the light emitted by the first light source unit OPU1 and the wavelength of the light emitted by the second light source unit OPU2 is a combination other than that in the first embodiment, it is preferable to change the material of the dichroic mirror appropriately depending on the wavelength to be used.

[0060] (Experiment) The temperature of the substrate was measured when the heat sink and the substrate were fixed by the method according to the embodiment and when the heat sink and the substrate were fixed by the method according to the comparative example. Here, the number of LED chips arranged in the light source array was 5 × 5.

[0061] Comparative Example First, a description will be given of a comparative example of a method for fixing the heat sink 1040 and the substrate 1021. Fig. 9A is a front view showing the heat sink 1040 and the light source array 1020 according to the comparative example, and Fig. 9B is a cross-sectional view taken along line A-A in Fig. 9A.

[0062] 9A , in the comparative example, three light source arrays 1020 are also arranged on a heat sink 1040. Each light source array 1020 includes a substrate 1021 and a plurality of LED chips 23A. The number of LED chips 23A provided on the substrate 1021 and the arrangement pitch are the same as those of the first light source array 20A.

[0063] 9B, the heat sink 1040 according to the comparative example includes a through hole 1401 and a fixing block 45. The fixing block 45 is fixed to the heat sink 1040 by a bolt 46. A screw hole is formed in the end of the fixing block 45 on the +Z1 side.

[0064] The substrate 1021 has through holes at four locations outside the range in which the LED chips 23A are arranged. The substrate 1021 is fixed to the heat sink 1040 by inserting bolts 60 into the through holes from the +Z1 side and engaging them with screw holes formed in the end of the fixing block 45 on the +Z1 side. The other configurations are the same as those of the embodiment, so detailed description will be omitted.

[0065] As shown in Fig. 9A, a thermistor 25 was placed on the surface of the substrate 1021, and the surface temperature of the substrate 1021 was measured. Similarly, a thermistor 25 was placed on the surface of the substrate 21A, and the surface temperature was measured. The thermistor 25 was placed in the same position on the substrate 21A and the substrate 1021. Fig. 10 shows the measurement results.

[0066] The horizontal axis of Fig. 10 indicates each substrate, with "left" indicating the substrate arranged on the -Y1 side, "center" indicating the substrate arranged in the center, and "right" indicating the substrate arranged on the +Y1 side, and "average" indicating the average value of all substrates. The vertical axis of Fig. 10 indicates the temperature obtained from the measurement value of thermistor 25.

[0067] As shown in FIG. 10 , it was confirmed that for both substrates, fixing the heat sink 40 to the substrate 21A using the method according to the embodiment reduced the substrate surface temperature compared to the method according to the comparative example. That is, it was confirmed that the fixing method according to the embodiment provided a greater cooling effect for the LED chip 23A than the fixing method according to the comparative example. This is believed to be due to the following reason. With the fixing method according to the comparative example, the substrate 1021 is fixed to the heat sink 1040 at four locations outside the area where the multiple LED chips 23A are arranged. Therefore, warping or deflection of the substrate 1021 results in insufficient adhesion between the heat conductive member 50 and the substrate 1021 and the heat sink 1040 in the area where the LED chips 23A are arranged. On the other hand, with the fixing method according to the embodiment, the substrate 21A can be fixed to the heat sink 40 at nine locations within the area where the LED chips 23A are arranged. This suppresses warping or deflection of the substrate 21A in the area where the LED chips 23A are arranged, thereby improving adhesion between the heat conductive member 50 and the substrate 21A and the heat sink 40. As a result, it is considered that the fixing method according to the embodiment has a higher cooling effect on the LED chip 23A than the fixing method according to the comparative example.

[0068] In this way, by fixing the substrate 21A to the heat sink 40 using the recess 211 formed in the portion AR1 of the second surface 21b of the substrate 21A that corresponds to the range in which the LED chips 23A are arranged, it has been confirmed that the LEDs 23A can be cooled more efficiently than in the comparative example in which a mechanism for fixing the substrate 1021 to the heat sink 1040 is provided outside the range in which the LED chips 23A are arranged and the substrate 1021 and the heat sink 1040 are fixed together.

[0069] As described above in detail, according to this embodiment, the first light source unit OPU1 includes the substrate 21A having the first surface 21a and the second surface 21b facing each other, the LED chips 23A arranged two-dimensionally on the first surface 21a of the substrate 21A, the heat sink 40, and the thermal conduction member 50 provided between the substrate 21A and the heat sink 40. The substrate 21A has a plurality of recesses 211 in a portion AR1 of the second surface 21b that faces the range in which the LED chips 23A are arranged in a plan view, the heat sink 40 has through holes 401, and the substrate 21A and the heat sink 40 are fixed together with bolts 61 that pass through the through holes 401 and fit into the recesses 211. This makes it possible to suppress warping or deflection of the substrate 21A in the range where the LED chips 23A are arranged, compared to, for example, a case where the substrate 21A and the heat sink 40 are fixed outside the range where the LED chips 23A are arranged, thereby improving the adhesion between the heat conduction member 50 and the substrate 21A and the heat sink 40. This allows the LED chips 23A to be cooled efficiently. This makes it possible to suppress a decrease in the brightness of the light emitted from the light-emitting portion 231A due to a rise in temperature of the LED chips 23A.

[0070] In this embodiment, the recesses 211 are screw holes, which allow the substrate 21A and the heat sink 40 to be easily fixed together using the bolts 61.

[0071] Furthermore, in this embodiment, a plurality of recesses 211 are formed in portion AR1 facing the range in which LED chips 23A are arranged, and a plurality of through-holes 401 are formed corresponding to the plurality of recesses 211. This allows substrate 21A and heat sink 40 to be fixed at a plurality of locations, thereby allowing substrate 21A and heat conductive member 50, and heat conductive member 50 and heat sink 40, to be closely attached to each other, and LED chips 23A can be cooled more efficiently.

[0072] In this embodiment, the recesses 211 and the through holes 401 are formed at equal intervals, which makes it possible to equalize the force acting on the substrate 21A from the bolts 61, thereby suppressing distortion, bending, and the like of the substrate 21A.

[0073] In this embodiment, the recess 211 does not penetrate the substrate 21A, which prevents the bolt 61 from coming into contact with the LED chip 23A.

[0074] In this embodiment, the substrate 21A is a metal substrate, which makes it easy to form the recess 211.

[0075] In the above embodiment, the thermally conductive member 50 is provided between the heat sink 40 and the substrate 21A, but the thermally conductive member 50 may be omitted. That is, the heat sink 40 and the substrate 21A may be fixed with bolts 61 so that they are in direct contact with each other. This also makes it possible to cool the LED chip 23A and to prevent a decrease in the brightness of the light emitted by the light-emitting portion 231A of the LED chip 23A due to a rise in temperature of the LED chip 23A.

[0076] In the above embodiment, the recess 211 is a screw hole, but this is not limiting. The recess 211 may be a hole without a thread. In this case, instead of the bolt 61, a fixing member that fits into the recess 211 may be used, and the fixing member may be fixed to the substrate 21A by soldering or adhesive.

[0077] In the above embodiment, a plurality of recesses 211 are provided, but it is sufficient that at least one recess 211 is formed in a portion of the second surface 21b of the substrate 21A corresponding to the portion where the LED chips 23A are arranged. The number of recesses 211 is not limited to that in the above embodiment, and may be eight or less, or ten or more.

[0078] In the above embodiment, the recesses 211 are provided at equal intervals in both the X1 direction and the Y1 direction, but may be provided at irregular intervals. In this case, the through holes 401 of the heat sink 40 may be formed at positions corresponding to the positions of the recesses 211.

[0079] In the above embodiment, the heat sink 40 has the flow passage 402 therein through which the coolant flows, but this is not limitative. The heat sink 40 may be, for example, a fin-type heat sink.

[0080] In the above embodiment, as shown in FIG. 11 , a control unit CTR that controls the LED chips 23A may be disposed on the surface of the heat sink 40 opposite to the surface on which the substrates 21A are arranged. In this case, the control unit CTR can be cooled by the heat sink 40, eliminating the need for a separate mechanism for cooling the control unit CTR and simplifying the configuration of the first light source unit OPU1. Furthermore, the length of the cable CBL that transmits signals from the control unit CTR to the LED chips 23A can be reduced. A longer cable increases the likelihood of noise being introduced into the signal, but the cable can be shortened, reducing noise. The same applies to the second light source unit OPU2.

[0081] Furthermore, in the above-described embodiment and modified examples, the illumination unit 90 includes the first light source unit OPU1, the second light source unit OPU2, and the illumination optical system 80 including the second dichroic mirror DM2. However, this is not limiting. For example, the illumination unit 90 may include only one of the first light source unit OPU1 and the second light source unit OPU2. In this case, the illumination optical system 80 may have any configuration as long as it can guide light emitted from the first light source unit OPU1 or the second light source unit OPU2 to the mask MSK.

[0082] The above-described embodiment is a preferred example of the present invention, but the present invention is not limited to this and can be modified in various ways without departing from the spirit of the present invention.

[0083] REFERENCE SIGNS LIST 10 Exposure device 20A First light source array 20B Second light source array 21A, 21B Substrate 21a First surface 21b Second surface 23A, 23B LED chip 30A First magnifying optical system 30B Second magnifying optical system 31A, 31B Lens section 40 Heat sink 50 Heat conduction member 61 Bolt 211 Recess 231A, 231B Light emitting section 401 Through hole 80 Illumination optical system 90 Illumination unit 100 Projection optical unit CTR Control section DM2 Second dichroic mirror MSK Mask OPU1 First light source unit OPU2 Second light source unit P Glass substrate

Claims

1. A substrate having a first surface and a second surface facing each other, a plurality of light source elements two-dimensionally arranged on the first surface of the substrate, a heat sink, comprising: The substrate has at least one recess formed in a portion of the second surface that faces the range in which the plurality of light source elements are arranged in a plan view, The heat sink has a through hole, The substrate and the heat sink are fixed by a fixing member that passes through the through hole and fits into the recess, A light source unit.

2. The recess is a screw hole, The light source unit according to Claim 1.

3. The fixing member is a screw, The light source unit according to Claim 2.

4. The heat sink has a flow path through which a refrigerant passes inside the heat sink, The light source unit according to any one of Claims 1 to 3.

5. The flow path is formed in a portion where the through hole is not formed, The light source unit according to Claim 4.

6. A plurality of the recesses are formed in a portion facing the range, A plurality of the through holes are formed corresponding to the plurality of the recesses, The light source unit according to any one of Claims 1 to 3.

7. The plurality of the recesses and the plurality of the through holes are formed at equal intervals, The light source unit according to Claim 6.

8. The recess does not penetrate the substrate, The light source unit according to any one of Claims 1 to 3.

9. Comprising a heat conduction member provided between the heat sink and the substrate, The light source unit according to any one of Claims 1 to 3.

10. The fixing member penetrates the heat conduction member, The light source unit according to Claim 9.

11. The substrate is a metal substrate, The light source unit according to any one of Claims 1 to 3.

12. The substrate has a thickness of 5 mm or less, The light source unit according to any one of Claims 1 to 3.

13. Each of the plurality of light source elements includes a light emitting portion that emits light, Further comprising a lens array in which a plurality of lenses that form an enlarged image of the light emitting portion of each of the plurality of light source elements are arranged on a two-dimensional plane, The light source unit according to any one of Claims 1 to 3.

14. A control unit for controlling the plurality of light source elements is arranged on a surface of the heat sink opposite to the surface on which the substrate is arranged. The light source unit according to any one of claims 1 to 3.

15. The light source unit according to claim 1, and an illumination optical system that guides the light emitted from the light source unit to an object to be irradiated. An illumination unit comprising the same.

16. A plurality of light source units according to claim 1, including a combining optical element that combines the light emitted from the plurality of light source units, and an illumination optical system that guides the combined light emitted from the combining optical element to an object to be irradiated. An illumination unit comprising the same.

17. The illumination unit according to claim 15 or claim 16, and a projection optical system that projects the pattern image of the mask illuminated by the illumination unit onto a photosensitive substrate. An exposure apparatus comprising the same.

18. The photosensitive substrate has a length or diagonal length of at least one side of 500 mm or more. The exposure apparatus according to claim 17.

19. An exposure method using the exposure apparatus according to claim 17, comprising illuminating a mask with the illumination unit, and projecting the pattern image of the mask onto a photosensitive substrate using the projection optical system. An exposure method comprising the same.