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

Abstract

This light source unit comprises: a light source array in which a plurality of light source elements each having a light emitting unit that emits light are arrayed on a two-dimensional plane; and a magnification optical system that forms a magnified image of the light emitting units of each of the light source elements, wherein: the magnification optical system is a double telecentric optical system that magnifies and projects at magnification M; and when the array pitch of the light source elements is defined as p, the length of one side of a light emitting surface of the light source unit as a, the maximum emission angle of light having a radiation intensity greater than Lambertian radiation among the light emitted from the light emitting unit as α, and the maximum emission angle of light emitted from the magnification optical system as θ, the magnification M satisfies the condition of p / a<M≤sinα / sinθ.

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 the like. Liquid crystal display panels are manufactured by forming a circuit pattern of thin-film transistors on a plate (glass substrate) using a photolithography technique. 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 (see, for example, Patent Document 1).

[0003] In general, there is a demand for a high-brightness surface light source that can be applied to various optical devices, including the above-mentioned exposure device.

[0004] Japanese Patent Application Laid-Open No. 2000-21712

[0005] According to the first aspect of the disclosure, the light source unit includes a light source array in which a plurality of light source elements, each having a light-emitting portion that emits light, are arranged on a two-dimensional plane, and a magnifying optical system that forms a magnified image of the light-emitting portion of each of the light source elements, wherein the magnifying optical system is a bilaterally telecentric optical system that performs enlarged projection at a magnification M, and where p is the arrangement pitch of the light source elements, a is the length of one side of the light-emitting surface of the light-emitting portion, α is the maximum emission angle of light that has a radiation intensity higher than Lambertian radiation among the light emitted from the light-emitting portion, and θ is the maximum emission angle of light emitted from the magnifying optical system, the magnification M satisfies the condition p / a<M≦sin α / sin θ.

[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-described illumination unit and a projection optical system that projects a pattern image of the object 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 the object to be irradiated with the illumination unit and projecting a pattern image of the object to the 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 allows them to 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 the first embodiment. FIG. 2 is a schematic diagram showing the configuration of an illumination unit according to the first embodiment. FIG. 3(A) is a plan view showing the configuration of first and second light source arrays, and FIG. 3(B) is a diagram showing the internal configuration of the first and second light source units. FIG. 4 is a graph showing an example of the relationship between the angle of incidence on a dichroic mirror and illuminance. FIG. 5 is a graph showing an example of the light distribution characteristics of the light-emitting portion of an LED chip. FIGS. 6(A) and 6(B) are diagrams explaining an enlarged image formed on a predetermined surface in the second embodiment. FIGS. 7(A) and 7(B) are diagrams showing simulation results.

[0012] First Embodiment An exposure apparatus 10 according to a first embodiment will be described with reference to FIGS. 1 to 4. FIG.

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

[0014] The exposure apparatus 10 is a scanning stepper (scanner) that drives a mask MSK and a glass substrate (hereinafter referred to as "substrate") 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 substrate P. The substrate P is a rectangular glass substrate used in, for example, a liquid crystal display device (flat panel display), with at least one side or diagonal length of 500 mm or more.

[0015] In the following, the direction in which the mask MSK and substrate 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 substrate 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 the 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 the substrate P, which is arranged on the image plane side of the projection optical system PL. Here, a resist (sensitizer) is applied to the surface of the substrate 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 substrate P in the same scanning direction relative to the exposure area (illumination light IL), the substrate P is exposed and the pattern of the mask MSK is transferred onto the substrate P.

[0023] The substrate stage PST is disposed on a base (vibration isolation table) 71 below (on the −Z side of) the projection optical system PL. The substrate 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 (for example, EGA, etc.) is performed prior to exposure, and the results are used to expose substrate P in the following procedure. First, in accordance with instructions from the control device, 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 substrate P. When scanning exposure on the first shot area is completed, the control device moves (steps) 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 on substrate P and scanning exposure on the shot areas to transfer the pattern of mask MSK to all shot areas on substrate 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.

[0027] 2 is a diagram schematically illustrating the configuration of the illumination unit 90. As shown in FIG. 2, 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 first light source array 20A and a first magnifying optical system 30A, and the second light source unit OPU2 includes a second light source array 20B and a second magnifying optical system 30B.

[0029] FIG. 3A is a plan view schematically illustrating the configuration of the first light source array 20A and the second light source array 20B. The first light source array 20A includes a plurality of LED (Light Emitting Diode) chips 23A (5 x 5 in FIG. 3A) arranged on a substrate 21A, for example. The number of LED chips 23A may be changed as needed. Each of the plurality of LED chips 23A has a light-emitting portion 231A, and the peak wavelength of 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). More preferably, the peak wavelength of 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. The LED chips 23A are arranged at a pitch P1, which is the distance between the centers of adjacent LED chips 23A.

[0030] The second light source array 20B includes, for example, a plurality of LED chips 23B (5 x 5 in FIG. 3A) arranged on a substrate 21B. The number of LED chips 23B may be changed appropriately as needed. Each of the plurality of 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 LED chips 23B are arranged at a pitch P2.

[0031] 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. Furthermore, the length a1 of one side of the light-emitting surface of the light-emitting portion 231A and the length a2 of one side of the light-emitting surface of the light-emitting portion 231B may be the same or different. The LED chips 23A and 23B may be arranged on, for example, a heat sink, rather than on a substrate.

[0032] FIG. 3B is a diagram schematically illustrating the internal configuration of the first light source unit OPU1 and the second light source unit OPU2. Since the internal configurations of the first light source unit OPU1 and the second light source unit OPU2 are identical, the configuration of the first light source unit OPU1 will be described here. The two directions in which the LED chips 23A are arranged are defined 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 defined as the Z1 direction. The Z1 direction is approximately parallel to the optical axis OA of the light emitted by the light-emitting portion 231A. For clarity of illustration, FIG. 3B shows only four LED chips 23A aligned in a row along the Y1 direction.

[0033] 3B, the first magnifying optical system 30A is an 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 of the lens units 31A is a double-telecentric optical system that magnifies and projects the light-emitting portion 231A at a magnification M1.

[0034] In this embodiment, each lens portion 31A includes four plano-convex lenses, but is not limited to this, and each lens portion 31A may include, for example, two biconvex lenses, three biconvex lenses, or a plano-convex lens and a biconvex lens.

[0035] In this embodiment, the lens unit 31A enlarges and projects the light-emitting units 231A at a magnification M1 = (arrangement pitch P1 of the LED chips 23A) / (length a1 of one side of the light-emitting surface of the light-emitting units 231A). On the other hand, the lens unit 31B included in the second magnifying optical system 30B enlarges and projects the light-emitting units 231B at a magnification M2 = (arrangement pitch P2 of the LED chips 23B) / (length a2 of one side of the light-emitting surface of the light-emitting units 231B). As a result, the enlarged images of the multiple light-emitting units 231A (231B) are substantially in contact with each other on the predetermined plane PP.

[0036] 2 again, the configuration of the illumination optical system 80 will be described. 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, an aperture stop 85, and a condenser optical system 84.

[0037] 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.

[0038] The second focusing optical system 81B forms a pupil of the enlarged 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.

[0039] 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.

[0040] 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. The second dichroic mirror DM2 does not necessarily have to be positioned at the rear focal position of the first focusing optical system 81A or the rear focal position of the second focusing optical system 81B, but may be positioned near the respective rear focal positions. Here, "nearby" refers to within ±100 mm along the optical axis from the rear focal position, preferably within ±50 mm, and more preferably ±20 mm. Note that the signs here indicate that the direction in which light from the light source travels along the optical axis is positive, and the opposite direction is negative.

[0041] 4 is a graph showing an example of the relationship between the angle of incidence on the dichroic mirror and illuminance. In FIG. 4, the horizontal axis represents the angle of incidence on the dichroic mirror, and the vertical axis represents the illuminance of reflected light. The illuminance on the vertical axis is set to 1 when light is incident on the dichroic mirror at a designed angle of incidence α.

[0042] As shown in Figure 4, when the dichroic mirror is critically illuminated (i.e., when the image of the light source is formed at the position of the dichroic mirror), the angle of incidence of the light beam on the dichroic mirror is within a range of approximately the design angle of incidence α ± 8°, resulting in an illuminance variation of 3% or more. On the other hand, when the dichroic mirror is Koehler-illuminated, the angle of incidence of the light beam on the dichroic mirror is within a range of approximately the design angle of incidence α ± 4°, resulting in an illuminance variation of 1% or less. In this way, by Koehler-illuminating the second dichroic mirror DM2, the difference in illuminance between the light incident on the second dichroic mirror DM2 and the light reflected by the second dichroic mirror DM2 can be reduced, thereby achieving illumination light IL with high brightness and little illuminance unevenness.

[0043] In this embodiment, the incident angle θ of the light from the second focusing optical system 81B onto the second dichroic mirror DM2 is set to 35°. An incident angle θ of 35° means that the incident angle θ is within the range of 35°±5°. The incident angle θ is preferably equal to or greater than 25° and less than 45°, more preferably equal to or greater than 25° and less than 42°, and even more preferably 35°±5°. This allows the second dichroic mirror DM2 to reflect the light beam of the pupil image formed by the second focusing optical system 81B with high efficiency.

[0044] Returning to Figure 2, 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.

[0045] 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.

[0046] 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.

[0047] 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.

[0048] The fly-eye lens FEL is constructed by closely arranging a large number of lens elements, each having a positive refractive power, in a vertical and horizontal direction 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 substrate P).

[0049] 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. 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.

[0050] The aperture stop 85 is disposed at a position that is nearly optically conjugate with the entrance pupil plane of the projection optical unit 100, 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 unit 100 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.

[0051] As described above in detail, the illumination unit 90 according to the first embodiment includes a first light source array 20A including an array of LED chips 23A each having a light-emitting portion 231A that emits light with a peak wavelength of 385 nm, a first magnifying optical system 30A that forms a magnified image of each light-emitting portion 231A of the LED chips 23A, and a first focusing optical system 81A that forms a pupil of the magnified image formed by the first magnifying optical system 30A. The illumination unit 90 also includes a second light source array 20B including an array of LED chips 23B each having a light-emitting portion 231B that emits light with a peak wavelength of 365 nm, a second magnifying optical system 30B that forms a magnified image of each light-emitting portion 231B of the LED chips 23B, and a second focusing optical system 81B that forms a pupil of the magnified image formed by the second magnifying optical system 30B. Furthermore, the illumination unit 90 includes a second dichroic mirror DM2 that 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.

[0052] The light beam of the pupil image formed by the first focusing optical system 81A and the light beam of the pupil image formed by the second focusing optical system 81B Koehler illuminate the second dichroic mirror DM2, and therefore, as described in FIG. 4, it is possible to realize illumination light IL that has higher brightness and less illuminance unevenness compared to when the second dichroic mirror DM2 is critically illuminated.

[0053] In the first embodiment, the first magnifying optical system 30A is a lens array having a plurality of lens units 31A arranged to correspond to the light-emitting units 231A, and the second magnifying optical system 30B is a lens array having a plurality of lens units 31B arranged to correspond to the light-emitting units 231B. Each of the lens units 31A of the first magnifying optical system 30A is a double-telecentric optical system that enlarges and projects the light-emitting units 231A at a magnification of (arrangement pitch P1 of the LED chips 23A) / (length a1 of one side of the light-emitting surface of the light-emitting units 231A). Each of the lens units 31B of the second magnifying optical system 30B is a double-telecentric optical system that enlarges and projects the light-emitting units 231B at a magnification of (arrangement pitch P2 of the LED chips 23B) / (length a2 of one side of the light-emitting surface of the light-emitting units 231B). This allows for the formation of a surface light source in which enlarged images of the plurality of light-emitting units 231A (231B) are substantially tangent to each other on a predetermined plane PP.

[0054] In the first embodiment, the illumination unit 90 includes a fly-eye lens FEL that converts the light beam of the composite image combined by the second dichroic mirror DM2 into a light beam with a uniform illuminance distribution and outputs the converted light beam, and a double-telecentric imaging optical system 83 that projects the composite image combined by the second dichroic mirror DM2 at an equal magnification onto the incident end of the fly-eye lens FEL. This allows the mask MSK to be uniformly illuminated.

[0055] In the first embodiment, the angle of incidence of the light beam of the pupil image formed by the second focusing optical system 81B on the second dichroic mirror DM2 is 35°, which allows the light beam of the pupil image formed by the second focusing optical system 81B to be reflected with high efficiency.

[0056] In the first embodiment described above, the light with a peak wavelength of 385 nm emitted from the first light source unit OPU1 is reflected by the first dichroic mirror DM1 and incident on the second dichroic mirror DM2, but the first dichroic mirror DM1 may be omitted and the light with a peak wavelength of 385 nm emitted from the first light source unit OPU1 may be incident directly on the second dichroic mirror DM2.

[0057] In the first embodiment, the light-emitting portion 231A of the LED chip 23A emits light with a peak wavelength of 385 nm, and the light-emitting portion 231B of the LED chip 23B emits light with a peak wavelength of 365 nm. However, the light-emitting portion 231A of the LED chip 23A may emit light with a peak wavelength of 365 nm, and the light-emitting portion 231B of the LED chip 23B may emit light with a peak wavelength of 385 nm. In this case, the first dichroic mirror DM1 may be configured to reflect at least a portion of the light with a peak wavelength of 365 nm, and the second dichroic mirror DM2 may be configured to transmit at least a portion of the light with a peak wavelength of 365 nm and reflect at least a portion of the light with a peak wavelength of 385 nm.

[0058] 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.

[0059] Second Embodiment Next, a second embodiment will be described. The second embodiment differs from the first embodiment in the magnifications M1 and M2 of the light-emitting units 231A and 231B by the first magnifying optical system 30A and the second magnifying optical system 30B.

[0060] (Regarding the LED chip) Fig. 5 is a graph showing an example of the light distribution characteristics of the light-emitting portion 231A of the LED chip 23A. In Fig. 5, the solid line shows the theoretical light distribution characteristics (Lambertian radiation) of the light-emitting portion 231A, and the dotted line is a curve obtained by actually measuring the radiation intensity of light emitted from the light-emitting portion 231A and approximating the measurement results using a sixth-order polynomial.

[0061] 5, of the light emitted from the light-emitting unit 231A, the radiation intensity of light in the range of emission angles greater than -50° and less than 50° is higher than the radiation intensity of Lambertian radiation, and the radiation intensity of light in the range of emission angles equal to or less than -50° and equal to or greater than 50° is lower than the radiation intensity of Lambertian radiation. Thus, the light emitted from the light-emitting unit 231A has a range of emission angles within which the radiation intensity is higher than the radiation intensity of Lambertian radiation. Therefore, it is believed that the brightness of the light emitted from the first light source unit OPU1 can be improved by using light emitted from the light-emitting unit 231A with an emission angle within this range (a range of ±50° in the example of FIG. 5).

[0062] Therefore, in the second embodiment, the magnification M1 when the first magnifying optical system 30A enlarges and projects the light emitting unit 231A is set to satisfy the following formula (1): P1 / a1<M1≦sin α １ / sinθ １ ...(1)

[0063] Here, P1 is the arrangement pitch of the LED chips 23A, a1 is the length of one side of the light-emitting surface of the light-emitting portion 231A, and α １ is the maximum emission angle of light emitted from the light emitting unit 231A at which the radiation intensity is higher than Lambertian radiation, and θ １ is the maximum emission angle of the light emitted from the first magnifying optical system 30A. １is a value that sets the ratio (σ) of the numerical aperture of the illumination optical system 80 to the numerical aperture of the projection optical unit 100 to 1. Note that, if the arrangement pitch P1 of the LED chips 23A and the length a1 of one side of the light-emitting surface of the light-emitting portion 231A in the X1 direction in Fig. 3 are different from the arrangement pitch P1 of the LED chips 23A and the length a1 of one side of the light-emitting surface of the light-emitting portion 231A in the Y1 direction, they should be set so as to satisfy formula (1) in both the X1 direction and the Y1 direction.

[0064] Furthermore, the magnification M2 when the second magnifying optical system 30B enlarges and projects the light emitting unit 231B is set to satisfy the following formula (2): P2 / a2<M2≦sin α ２ / sinθ ２ ... (2)

[0065] Here, P2 is the arrangement pitch of the LED chips 23B, a2 is the length of one side of the light-emitting surface of the light-emitting portion 231B, and α ２ is the maximum emission angle of light emitted from the light emitting unit 231B at which the radiation intensity is higher than Lambertian radiation, and θ ２ is the maximum emission angle of the light emitted from the second magnifying optical system 30B. ２ is a value that sets the ratio (σ) of the numerical aperture of the illumination optical system 80 to the numerical aperture of the projection optical unit 100 to 1. Note that, if the arrangement pitch P2 of the LED chips 23B and the length a2 of one side of the light-emitting surface of the light-emitting portion 231B in the X1 direction in FIG. 3 are different from the arrangement pitch P2 of the LED chips 23B and the length a2 of one side of the light-emitting surface of the light-emitting portion 231B in the Y1 direction, they should be set so as to satisfy formula (2) in both the X1 direction and the Y1 direction.

[0066] By magnifying the light-emitting portions 231A and 231B at a magnification M1 that satisfies the formula (1) and a magnification M2 that satisfies the formula (2), the magnified images of the light-emitting surfaces of the light-emitting portions 231A and 231B, excluding their peripheral edges, come into contact with each other on the predetermined plane PP. This point will be explained below.

[0067] 6A and 6B are diagrams illustrating an enlarged image formed on a predetermined plane PP in the second embodiment. More specifically, Fig. 6A is a plan view showing arranged LED chips 23A, and Fig. 6B is a plan view showing an enlarged image formed on the predetermined plane PP. For simplicity of illustration, a 2 x 2 array of LED chips 23A will be used for the description.

[0068] 6A, the peripheral portion of the light-emitting surface of the light-emitting portion 231A of the LED chip 23A is defined as a peripheral region 231b, and the region excluding the peripheral region 231b is defined as a central region 231a. In this case, when an enlarged image of the light-emitting portion 231A is formed at a magnification M1 that satisfies formula (1), the enlarged images are formed so that the enlarged images MI1 of the central region 231a contact each other on the predetermined plane PP, and the enlarged images MI2 of the light-emitting portion 231A including the central region 231a and the peripheral region 231b partially overlap each other, as shown in FIG.

[0069] By enlarging the light-emitting units 231A and 231B by magnifications M1 and M2 that satisfy equations (1) and (2), respectively, a surface light source can be formed on the predetermined plane PP by light whose radiation intensity is higher than Lambertian radiation, thereby making it possible to increase the intensity of the light emitted from the first light source unit OPU1 and the second light source unit OPU2. In other words, a surface light source is formed by light emitted from a region (central region 231a) of the light-emitting surfaces of the light-emitting units 231A and 231B that emits light whose radiation intensity is higher than Lambertian radiation, thereby making it possible to increase the intensity of the light emitted from the first light source unit OPU1 and the second light source unit OPU2.

[0070] [Simulation 1] The magnification M1 of the light-emitting unit 231A by the first magnifying optical system 30A was changed to simulate the illuminance of the magnified image formed by the first magnifying optical system 30A on a predetermined surface. The simulation conditions were as follows: LED chip 23A: NVSU233B manufactured by Nichia Corporation; length of one side of the light-emitting surface of the light-emitting unit 231A: 1.4 mm; array pitch P1: 4 mm α １ : 50° θ １ : 8°

[0071] In this case, the condition for the magnification M1 is 4 mm / 1.4 mm=2.9<M1≦sin 50° / sin 8°=5.5. Therefore, the illuminance was simulated for the cases where the magnification M1=2.79 and the magnification M1=3.6 times.

[0072] Fig. 7A is a diagram showing the results of the simulation. In Fig. 7A, the horizontal axis represents the magnification, and the vertical axis represents the illuminance ratio when the illuminance at magnification M1 = 2.79 is set to 1. As shown in Fig. 7A, it was confirmed that by making the magnification M1 larger than P1 / a1, the illuminance is improved compared to when the magnification M1 is set to P1 / a1.

[0073] [Simulation 2] Using an LED chip 23A different from the LED chip 23A used in Simulation 1, illuminance was simulated by changing the magnification M1 in the same manner as in Simulation 1. The simulation conditions were as follows: LED chip 23A: NWSU333B manufactured by Nichia Corporation; length of one side of the light-emitting surface of the light-emitting portion 231A: 1.9 mm; arrangement pitch P1: 7 mm α １ : 50° θ １ : 8°

[0074] In this case, the condition for the magnification M1 is 7 mm / 1.9 mm=3.68<M1≦sin 50° / sin 8°=5.5. Therefore, the illuminance was simulated for the cases of magnification M1=3.68, magnification M1=4.38, and magnification M1=4.65.

[0075] Fig. 7(B) is a diagram showing the simulation results. In Fig. 7(B), the horizontal axis represents magnification, and the vertical axis represents the illuminance ratio when the illuminance at magnification M1 = 4.38 is set to 1. As shown in Fig. 7(B), it was confirmed that by making magnification M1 larger than P1 / a1, the illuminance is improved compared to when magnification M1 is set to P1 / a1.

[0076] As described above in detail, according to the second embodiment, the magnification M1 when the first magnifying optical system 30A enlarges and projects the light emitting unit 231A satisfies the following relationship: P1 / a1<M1≦sin α １ / sinθ １The magnification M2 when the second magnifying optical system 30B enlarges and projects the light emitting unit 231B satisfies the following condition: P2 / a2<M2≦sinα ２ / sinθ ２ Meet the following.

[0077] By specifying the magnifications M1 and M2 in this manner, a secondary light source can be formed using light whose radiation intensity is higher than Lambertian radiation, thereby making it possible to increase the intensity of the light emitted from the first light source unit OPU1 and the second light source unit OPU2.

[0078] Furthermore, during the manufacturing process of the first light source array 20A and the second light source array 20B, misalignment of the LED chips 23A and 23B may occur when the LED chips 23A and 23B are arranged on a substrate. Such misalignment may result in a decrease in the illuminance of the first light source array 20A and the second light source array 20B. In this embodiment, by making the magnifications M1 and M2 larger than P1 / a1 and P2 / a2, respectively, it is possible to use only the inner regions (regions excluding the peripheral portions) of the light-emitting surfaces of the light-emitting units 231A and 231B. Therefore, even if the LED chips 23A and 23B are misaligned, a decrease in the illuminance of the first light source array 20A and the second light source array 20B can be suppressed.

[0079] In the second embodiment, sin θ １ and sinθ ２ is a value that makes the ratio (σ) of the numerical aperture of the illumination optical system 80 to the numerical aperture of the projection optical unit 100 1. This makes it possible to realize illumination light IL with a brightness according to the numerical aperture required in the exposure apparatus 10.

[0080] 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.

[0081] REFERENCE SIGNS LIST 10 exposure device 20A first light source array 20B second light source array 23A, 23B LED chips 231A, 231B light emitting section 30A first magnifying optical system 30B second magnifying optical system 31A, 31B lens section 81A first focusing optical system 81B second focusing optical system 80 illumination optical system 90 illumination unit 100 projection optical unit OPU1 first light source unit OPU2 second light source unit PL projection optical system FEL fly's eye lens DM2 second dichroic mirror

Claims

1. A light source array comprising multiple light source elements having light-emitting parts that emit light arranged on a two-dimensional plane, A magnifying optical system that forms an enlarged image of each of the light-emitting parts of the light source element, Equipped with, The aforementioned magnification optical system is a bilateral telecentric optical system that magnifies and projects at a magnification of M. When the array pitch of the light source elements is p and the length of one side of the light-emitting surface of the light-emitting unit is a, the magnification M satisfies the condition p / a < M. Light source unit.

2. When α is the maximum emission angle of light emitted from the light-emitting unit whose radiation intensity is higher than that of Lambertian radiation, and θ is the maximum emission angle of light emitted from the magnifying optical system, the magnification M satisfies the condition M ≤ sinα / sinθ. The light source unit according to claim 1.

3. The light-emitting part is an ultraviolet light-emitting diode. A light source unit according to claim 1 or claim 2.

4. The peak wavelength of the light emitted from the light-emitting part is in the range of 360 to 440 nm. A light source unit according to claim 1 or claim 2.

5. Used in an exposure apparatus having an illumination optical system that guides light emitted from a light source to an object to be illuminated, and a projection optical system that projects an image of the pattern of the object to be illuminated by the illumination optical system onto a photosensitive substrate, The sinθ is a value that makes the ratio of the numerical aperture of the illumination optical system to the numerical aperture of the projection optical system equal to 1. The light source unit according to claim 2.

6. A light source unit according to claim 1 or claim 2, An illumination optical system that guides light emitted from the light source unit to the object to be illuminated, A lighting unit equipped with [a specific feature / feature].

7. Multiple light source units according to claim 1 or claim 2, An illumination optical system including a composite optical element that combines light emitted from multiple light source units, and which guides the composite light emitted from the composite optical element to the object to be illuminated, A lighting unit equipped with [a specific feature / feature].

8. The lighting unit according to claim 6, A projection optical system that projects a pattern image of the illuminated object, illuminated by the illumination unit, onto a photosensitive substrate, An exposure apparatus equipped with the following features.

9. The photosensitive substrate has at least one side length or diagonal length of 500 mm or more. The exposure apparatus according to claim 8.

10. The light source unit according to Claim 2, An illumination optical system that guides light emitted from the light source unit to the object to be illuminated, A projection optical system that projects an image of the pattern of the illuminated object, illuminated by the illumination optical system, onto a photosensitive substrate, Equipped with, The sinθ is a value that makes the ratio of the numerical aperture of the illumination optical system to the numerical aperture of the projection optical system equal to 1. Exposure apparatus.

11. An exposure method using the exposure apparatus described in claim 8, The lighting unit illuminates the object to be illuminated, Projecting a pattern image of the irradiated object onto the photosensitive substrate using the projection optical system, An exposure method including [details omitted].