Illumination unit, exposure apparatus, and exposure method

Abstract

This lighting unit comprises: a first light source array (20A) in which a plurality of first light source elements each having a first light emitting section that emits light having a first wavelength characteristic is arranged; a first enlarging optical system (30A) that forms an enlarged image of the first light emitting section of each of the first light source elements; a first optical system (81A) into which light from the first enlarging optical system enters; a second light source array (20B) in which a plurality of second light source elements each having a second light emitting section that emits light having a second wavelength characteristic, which is different from the first wavelength characteristic, is arranged; a second enlarging optical system (30B) that forms an enlarged image of the second light emitting section of each of the second light source elements; a second optical system (81B) into which light from the second enlarging optical system enters; and a combining optical element (DM2) that combines the light from the first optical system with the light from the second optical system, wherein the combining optical element is located at the back focal position of the first optical system or a position close thereto and at the back focal position of the second optical system or a position close thereto.

Description

[Technical Field]

[0001] The present invention relates to an illumination unit, an exposure apparatus, and an exposure method. [Background technology]

[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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-21712 Summary of the Invention

[0005] According to a first aspect of the disclosure, an illumination unit includes a first light source array including a plurality of first light source elements each having a first light-emitting portion that emits light having a first wavelength characteristic; a first magnifying optical system that forms a magnified image of the first light-emitting portion of each of the first light source elements; a first optical system into which light from the first magnifying optical system is incident; a second light source array including a plurality of second light source elements each having a second light-emitting portion that emits light having a second wavelength characteristic different from the first wavelength characteristic; a second magnifying optical system that forms a magnified image of the second light source elements; a second optical system into which light from the second magnifying optical system is incident; and a combining optical element that combines the light from the first optical system and the light from the second optical system, wherein the combining optical element is positioned at or near the back focal position of the first optical system and at or near the back focal position of the second optical system.

[0006] According to a second 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.

[0007] According to a third aspect of the disclosure, an exposure method is an exposure method using the above-mentioned exposure apparatus, and includes illuminating the mask using the illumination unit and projecting a pattern image of the mask onto the photosensitive substrate using the projection optical system.

[0008] 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. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic view showing the configuration of an exposure apparatus according to the first embodiment. [Figure 2] FIG. 2 is a schematic diagram showing the configuration of the lighting unit according to the first embodiment. [Figure 3]FIG. 3(A) is a plan view schematically showing the configuration of the first and second light source arrays, and FIG. 3(B) is a view schematically showing the internal configuration of the first and second light source units. [Figure 4] FIG. 4 is a graph showing an example of the relationship between the angle of incidence on the dichroic mirror and the illuminance. [Figure 5] FIG. 5 is a graph showing an example of the light distribution characteristics of the light-emitting portion of the LED chip. [Figure 6] 6(A) and 6(B) are diagrams illustrating an enlarged image formed on a predetermined plane in the second embodiment. [Figure 7] 7A and 7B are diagrams showing the simulation results. DETAILED DESCRIPTION OF THE INVENTION

[0010] First Embodiment An exposure apparatus 10 according to the first embodiment will be described with reference to FIGS.

[0011] (Configuration of exposure device) First, the configuration of an exposure apparatus 10 according to the first embodiment will be described using Figure 1. Figure 1 is a diagram that shows roughly the configuration of an exposure apparatus 10 according to the first embodiment.

[0012] 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, for example, in a liquid crystal display device (flat panel display), with at least one side or diagonal length of 500 mm or more.

[0013] 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.

[0014] 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 exposure apparatus 10.

[0015] 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.

[0016] 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.

[0017] 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).

[0018] 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 reflected light 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.

[0019] The projection optical system PL is supported by 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. It includes multiple (e.g., seven) projection optical units 100 (multi-lens projection optical units) arranged in a staggered pattern, each projecting an image of a pattern on the mask MSK. The projection optical system PL forms a rectangular image field with its longitudinal direction along the Y axis. Here, four projection optical units 100 are arranged at predetermined intervals along the Y axis, and the remaining three projection optical units 100 are arranged at predetermined intervals along the Y axis, spaced apart from the first 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.

[0020] 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 in an irradiation area (exposure area (conjugate to the illumination area)) on the substrate P, which is placed 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.

[0021] The substrate stage PST is placed 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).

[0022] 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), which drives the substrate stage PST in accordance with the measurement results of the interferometer system.

[0023] In exposure apparatus 10, alignment measurement (for example, EGA) is performed prior to exposure, and the results are used to expose substrate P in the following procedure. First, mask stage MST and substrate stage PST are synchronously driven in the X-axis direction according to instructions from the control device. 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.

[0024] (Configuration of the illumination system IOP) Next, the configuration of the illumination system IOP in this embodiment will be described. The illumination system IOP comprises a plurality of illumination units 90 corresponding to the plurality of projection optical units 100 that the projection optical system PL comprises.

[0025] 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.

[0026] (Light source unit configuration) 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.

[0027] 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 (5×5 in FIG. 3A) arranged on a substrate 21A, for example. The number of LED chips 23A may be appropriately 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. That is, the light-emitting portion 231A is an ultraviolet LED (UV LED). It is more preferable that 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. The pitch P1 is the distance between the centers of adjacent LED chips 23A.

[0028] The second light source array 20B includes a plurality of LED chips 23B (5×5 in FIG. 3(A)) arranged on a substrate 21B, for example. 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 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 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.

[0029] 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.

[0030] FIG. 3(B) 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 the same, 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 perpendicular to each other. The direction perpendicular 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. 3(B) shows only four LED chips 23A aligned in a row along the Y1 direction.

[0031] As shown in Fig. 3(B), 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.

[0032] In this embodiment, each lens unit 31A includes four plano-convex lenses, but is not limited to this, and each lens unit 31A may include, for example, two biconvex lenses, three biconvex lenses, or a plano-convex lens and a biconvex lens.

[0033] 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.

[0034] (Configuration of illumination optical system 80) 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 81B (second optical system), 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.

[0035] 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 in 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 that 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. The first focusing optical system 81A may be configured with a single lens or a lens group including multiple lenses.

[0036] 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 position of the pupil. The second focusing optical system 81B may be composed of a single lens or a lens group including multiple lenses.

[0037] 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.

[0038] 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 performs Koehler illumination on the light emitted from the first light source unit OPU1 and the light emitted from the second light source unit OPU2. By performing Koehler illumination, it is possible to reduce changes in 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 back focal position of the first focusing optical system 81A or the back focal position of the second focusing optical system 81B, but may be positioned near the respective back focal positions. Here, "nearby" refers to within ±100 mm along the optical axis from the back 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.

[0039] Figure 4 is a graph showing an example of the relationship between the angle of incidence on the dichroic mirror and illuminance. In Figure 4, the horizontal axis represents the angle of incidence on the dichroic mirror, and the vertical axis represents the illuminance of the reflected light. The illuminance on the vertical axis is set to 1 when the light is incident on the dichroic mirror at the designed angle of incidence α.

[0040] 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 the 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 the 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 minimal illuminance unevenness.

[0041] 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.

[0042] Returning to FIG. 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.

[0043] Specifically, detector DT10 detects the illuminance of light with a peak wavelength of 385 nm reflected by the first dichroic mirror DM1. Detector DT20 detects the illuminance of light with a peak wavelength of 365 nm reflected by the second dichroic mirror DM2. Detector DT30 detects the illuminance of 385 nm light unintentionally reflected by the second dichroic mirror DM2 and the illuminance of 365 nm light unintentionally transmitted by the second dichroic mirror DM2.

[0044] 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.

[0045] 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.

[0046] 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 thus the shape of the exposure area to be formed on the substrate P).

[0047] 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.

[0048] 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 condensed by the condenser optical system 84, and then illuminates a mask MSK on which a predetermined pattern is formed in a superimposed manner.

[0049] 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 emitting 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 condensing 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 emitting 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 condensing 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.

[0050] The light beams of the pupil image formed by the first focusing optical system 81A and the light beams of the pupil image formed by the second focusing optical system 81B Koehler illuminate the second dichroic mirror DM2, and as described in FIG. 4, it is possible to achieve illumination light IL that has higher brightness and less illuminance unevenness compared to when the second dichroic mirror DM2 is critically illuminated.

[0051] 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 unit 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 unit 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.

[0052] 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 entrance end of the fly-eye lens FEL. This allows the mask MSK to be uniformly illuminated.

[0053] In the first embodiment, the incident angle 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.

[0054] 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. However, 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 directly incident on the second dichroic mirror DM2.

[0055] 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.

[0056] 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. 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. When the combination of the wavelengths of the light emitted by the first light source unit OPU1 and the second light source unit OPU2 is a combination other than that described in the first embodiment, it is preferable to appropriately change the material of the dichroic mirror depending on the wavelengths used.

[0057] 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.

[0058] (About LED chips) Fig. 5 is a graph showing an example of the light distribution characteristics of the light-emitting section 231A of the LED chip 23A. In Fig. 5, the solid line shows the theoretical light distribution characteristics (Lambert radiation) of the light-emitting section 231A, and the dotted line is a curve obtained by actually measuring the radiation intensity of the light emitted from the light-emitting section 231A and approximating the measurement results with a sixth-order polynomial.

[0059] 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, there is a range of emission angles in the light emitted from the light-emitting unit 231A where the radiation intensity is higher than the radiation intensity of Lambertian radiation. Therefore, it is believed that the luminance 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 emission angles within this range (a range of ±50° in the example of FIG. 5).

[0060] 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≦sinα1 / sinθ1···(1)

[0061] 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, α1 is the maximum emission angle of light emitted from the light-emitting portion 231A at which the radiation intensity is higher than Lambertian radiation, and θ1 is the maximum emission angle of light emitted from the first magnifying optical system 30A. Note that sin θ1 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 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 may be set so as to satisfy formula (1) in both the X1 direction and the Y1 direction.

[0062] Furthermore, the magnification M2 when the second magnifying optical system 30B enlarges and projects the light emitting part 231B is set to satisfy the following formula (2). P2 / a2 <M2≦sinα2 / sinθ2···(2)

[0063] 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 unit 231B, α2 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 θ2 is the maximum emission angle of light emitted from the second magnifying optical system 30B. Note that sin θ2 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 unit 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 unit 231B in the Y1 direction, they may be set to satisfy formula (2) in both the X1 direction and the Y1 direction.

[0064] By magnifying light emitting portions 231A and 231B with a magnification M1 that satisfies formula (1) and a magnification M2 that satisfies formula (2), the magnified images of the light emitting surfaces of light emitting portions 231A and 231B, excluding their peripheral edges, come into contact with each other on the predetermined plane PP. This point will now be explained.

[0065] 6(A) and 6(B) are diagrams illustrating an enlarged image formed on a predetermined surface PP in the second embodiment. More specifically, FIG. 6(A) is a plan view showing arranged LED chips 23A, and FIG. 6(B) is a plan view showing an enlarged image formed on the predetermined surface PP. For simplicity of illustration, a 2×2 array of LED chips 23A will be used for explanation.

[0066] As shown in Fig. 6(A), of the light-emitting surface of the light-emitting portion 231A of the LED chip 23A, the peripheral portion is defined as the peripheral region 231b, and the region excluding the peripheral region 231b is defined as the 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. 6(B).

[0067] 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.

[0068] [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 plane. The simulation conditions were as follows: LED chip 23A: Nichia Corporation NVSU233B Length of one side of the light-emitting surface of the light-emitting unit 231A: 1.4 mm Array pitch P1: 4 mm α1: 50° θ1: 8°

[0069] In this case, the condition for the magnification M1 is 4 mm / 1.4 mm = 2.9 < M1 ≤ sin50° / sin8° = 5.5. Therefore, the illuminance was simulated for the cases of magnification M1 = 2.79 and magnification M1 = 3.6 times.

[0070] Figure 7(A) is a diagram showing the simulation results. In Figure 7(A), the horizontal axis represents the magnification, and the vertical axis represents the illuminance ratio when the illuminance at the time of magnification M1 = 2.79 is taken as 1. As shown in Figure 7(A), it was confirmed that by making the magnification M1 larger than P1 / a1, the illuminance is improved compared to the case where the magnification M1 is P1 / a1.

[0071] [Simulation 2] Using an LED chip 23A different from the LED chip 23A used in Simulation 1, the illuminance was simulated by changing the magnification M1 in the same manner as in Simulation 1. The simulation conditions are as follows. LED chip 23A: NWSU333B manufactured by Nichia Chemical Industries, Ltd. Length of one side of the light-emitting surface of the light-emitting unit 231A: 1.9 mm Array pitch P1: 7 mm α1: 50° θ1: 8°

[0072] In this case, the condition for the magnification M1 is 7 mm / 1.9 mm = 3.68 < M1 ≤ sin50° / sin8° = 5.5. Therefore, the illuminance was simulated for the cases of magnification M1 = 3.68, magnification M1 = 4.38, and magnification M1 = 4.65.

[0073] FIG. 7(B) is a diagram showing the simulation results. In FIG. 7(B), the horizontal axis represents the magnification, and the vertical axis represents the illuminance ratio when the illuminance at a magnification M1 = 4.38 is set to 1. As shown in FIG. 7(B), it was confirmed that by making the magnification M1 larger than P1 / a1, the illuminance is improved compared to the case where the magnification M1 is P1 / a1.

[0074] As described in detail above, according to the second embodiment, the magnification M1 when the first magnifying optical system 30A enlarges and projects the light emitting portion 231A satisfies P1 / a1 < M1 ≦ sinα1 / sinθ1, and the magnification M2 when the second magnifying optical system 30B enlarges and projects the light emitting portion 231B satisfies P2 / a2 < M2 ≦ sinα2 / sinθ2.

[0075] By defining the magnifications M1 and M2 in this way, a secondary light source can be formed by light whose radiant intensity is higher than Lambertian radiation, so that the intensity of the light emitted from the first light source unit OPU1 and the second light source unit OPU2 can be increased.

[0076] Also, in the manufacturing process of the first light source array 20A and the second light source array 20B, when the LED chips 23A and 23B are arranged on the substrate, misalignment of the LED chips 23A and 23B may occur. Due to the misalignment, the illuminance of the first light source array 20A and the second light source array 20B may decrease. In this embodiment, by making the magnifications M1 and M2 larger than P1 / a1 and P2 / a2, respectively, only the region inside the light emitting surfaces of the light emitting portions 231A and 231B (the region excluding the peripheral portion) can be used. 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.

[0077] Also, in the second embodiment, sinθ1 and sinθ2 are values that make the ratio (σ) of the numerical aperture of the illumination optical system 80 to the numerical aperture of the projection optical unit 100 equal to 1. Thereby, illumination light IL with luminance corresponding to the numerical aperture required in the exposure apparatus 10 can be realized.

[0078] 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. [Explanation of symbols]

[0079] 10 Exposure equipment 20A First Light Source Array 20B Second light source array 23A, 23B LED chip 30A First magnifying optical system 30B Second magnifying optical system 31A, 31B Lens section 81A First focusing optical system 81B Second focusing optical system 90 Lighting Unit 100 Projection Optical Unit PL projection optical system FEL Fly Eye Lens DM2 Second Dichroic Mirror

Claims

1. a first light source array in which a plurality of first light source elements having first light emitting portions that emit light having a first wavelength characteristic are arranged; a first magnifying optical system that forms a magnified image of the first light-emitting portion of each of the first light source elements; a first optical system onto which light from the first magnifying optical system is incident; a second light source array in which a plurality of second light source elements each having a second light emitting portion that emits light having a second wavelength characteristic different from the first wavelength characteristic are arranged; a second magnifying optical system that forms a magnified image of the second light-emitting portion of each of the second light source elements; a second optical system onto which light from the second magnifying optical system is incident; a combining optical element that combines the light from the first optical system and the light from the second optical system; Equipped with An illumination unit, wherein the combining optical element is disposed at a position that is at or near the back focal position of the first optical system and at or near the back focal position of the second optical system.

2. the first magnifying optical system is a first lens array having a plurality of first lens units arranged to correspond to the first light-emitting units, the second magnifying optical system is a second lens array having a plurality of second lens units arranged to correspond to the second light-emitting units, The lighting unit according to claim 1 .

3. each of the first lens units of the first lens array is a bilaterally telecentric optical system that enlarges and projects the first light-emitting units at a magnification of at least (arrangement pitch of the first light source elements) / (length of one side of a light-emitting surface of the first light-emitting units), Each of the second lens units of the second lens array is a bilaterally telecentric optical system that enlarges and projects the second light-emitting units at a magnification of at least (arrangement pitch of the second light source elements) / (length of one side of the light-emitting surface of the second light-emitting units). The lighting unit according to claim 2 .

4. a light uniformizing element that converts the light combined by the combining optical element into a light beam with a uniform illuminance distribution and outputs the light; a double-telecentric imaging optical system that projects the light combined by the combining optical element onto an incident end of the light uniformizing element at a magnification of 100 or a reduced magnification; The lighting unit of claim 1 , comprising:

5. The lighting unit according to claim 4 , wherein the light homogenizing element is a fly's eye lens.

6. the first light-emitting unit and the second light-emitting unit are each an ultraviolet light-emitting diode; The lighting unit according to claim 1 .

7. The peak wavelength of the light emitted from the first light-emitting unit is in the range of 380 to 390 nm.

7. The lighting unit according to claim 6.

8. The peak wavelength of the light emitted from the second light-emitting unit is in the range of 360 to 370 nm.

8. The lighting unit according to claim 7.

9. the combining optical element is a dichroic mirror that transmits at least a portion of the light having the first wavelength characteristic and reflects at least a portion of the light having the second wavelength characteristic; 9. The lighting unit according to claim 8.

10. the combining optical element is a dichroic mirror that reflects at least a portion of the light having the first wavelength characteristic and transmits at least a portion of the light having the second wavelength characteristic.

9. The lighting unit according to claim 8.

11. an incident angle of the light from the second optical system to the combining optical element is equal to or greater than 25° and less than 45°; 11. The lighting unit according to any one of claims 1 to 10.

12. an incident angle of the light from the second optical system to the combining optical element is equal to or greater than 25° and equal to or less than 42°; 11. The lighting unit according to claim 1.

13. The incident angle of the light from the second optical system to the combining optical element is 35°.

11. The lighting unit according to any one of claims 1 to 10.

14. The lighting unit according to any one of claims 1 to 10; a projection optical system that projects a pattern image of a mask illuminated by the illumination unit onto a photosensitive substrate; An exposure apparatus comprising:

15. The photosensitive substrate has at least one side length or diagonal length of 500 mm or more. The exposure apparatus according to claim 14.

16. An exposure method using the exposure apparatus according to claim 14, illuminating the mask with the illumination unit; projecting a pattern image of the mask onto the photosensitive substrate using the projection optical system; An exposure method comprising:

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