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

Abstract

The light source unit of the present invention comprises: 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 above-mentioned light source elements; the above-mentioned magnifying optical system is a double-sided telecentric optical system that performs magnifying projection at a magnification M, when the arrangement pitch of the above-mentioned light source elements is defined as p, the length of one side of the light-emitting surface of the above-mentioned light-emitting portion is defined as a, the maximum exit angle of light whose radiation intensity is higher than Lambertian radiation among the above-mentioned light emitted from the above-mentioned light-emitting portion is defined as α, and the maximum exit angle of light emitted from the above-mentioned magnifying optical system is defined as θ, the above-mentioned magnification M satisfies the condition of p / a < M ≦ sinα / sinθ.

Description

Technical Field

[0001] Regarding a light source unit, a lighting unit, an exposure device, and an exposure method. Prior Art

[0002] In recent years, liquid crystal display panels have often been used as display elements for personal computers or televisions, etc. The liquid crystal display panel is manufactured by forming a circuit pattern of thin film transistors on a flat plate (glass substrate) by a photolithography method. An exposure device that projects and exposes the original drawing pattern formed on a photomask onto a photoresist layer on a flat plate via a projection optical system is used as the device for this photolithography process (for example, Patent Document 1).

[0003] Generally speaking, a high-brightness surface light source that can be applied to various optical devices including the above exposure device is required. [Prior Art Documents] [Patent Documents]

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

[0005] According to the first aspect of the invention, the light source unit includes: a light source array that arranges a plurality of light source elements having light-emitting portions that emit light on a two-dimensional plane; and a magnifying optical system that forms magnified images of the light-emitting portions of the respective light source elements; the magnifying optical system is a two-sided telecentric optical system that magnifies and projects at a magnification M. When the arrangement pitch of the light source elements is set to p, the length of one side of the light-emitting surface of the light-emitting portion is set to a, the maximum emission angle of the light emitted from the light-emitting portion and having a radiation intensity higher than Lambert radiation is set to α, and the maximum emission angle of the light emitted from the magnifying optical system is set to θ, the magnification M satisfies the condition of p / a < M ≦ sin α / sin θ.

[0006] According to the second aspect of the invention, the lighting unit includes: the above light source unit; and a lighting optical system that guides the light emitted from the light source unit to an object to be irradiated.

[0007] According to the third aspect of the invention, the lighting unit includes: a plurality of the above light source units; and a lighting optical system that includes a combining optical element that combines the light emitted from the plurality of light source units, and guides the combined light emitted from the combining optical element to an object to be irradiated.

[0008] According to the fourth aspect of the invention, the exposure device comprises: the above-mentioned lighting unit; and a projection optical system, which projects the pattern image of the above-mentioned irradiated object illuminated by the above-mentioned lighting unit onto the photosensitive substrate.

[0009] According to the fifth aspect of the invention, the exposure method is an exposure method using the above-mentioned exposure device, and includes: using the above-mentioned lighting unit to illuminate the above-mentioned irradiated object; and using the above-mentioned projection optical system to project the pattern image of the above-mentioned irradiated object onto the above-mentioned photosensitive substrate.

[0010] Furthermore, the configuration of the following embodiments may be appropriately improved, and at least a portion thereof may be replaced with other components. Furthermore, the components whose configuration is not particularly limited are not limited to the configuration disclosed in the embodiments, and may be configured at a position where their functions can be achieved. Simple diagram description

[0011] [Fig. 1] is a schematic diagram showing the structure of the exposure device of the first embodiment. [Fig. 2] is a schematic diagram showing the structure of the lighting unit of the first embodiment. [FIG. 3(A)] is a top view schematically showing the structure of the first and second light source arrays, and [FIG. 3(B)] is a diagram schematically showing the internal structure of the first and second light source units. FIG. 4 is a diagram showing an example of the relationship between the incident angle and the illumination on a dichroic mirror. [Fig. 5] is a diagram showing an example of the light distribution characteristics of the light-emitting portion of an LED chip. [FIG. 6(A)] and [FIG. 6(B)] are diagrams for explaining an enlarged image formed on a predetermined surface in the second embodiment. [FIG. 7(A)] and [FIG. 7(B)] are diagrams showing simulation results. Implementation

[0012] 《First Implementation Form》 An exposure apparatus 10 according to a first embodiment will be described based on FIGS. 1 to 4 .

[0013] (Construction of Exposure Device) First, the structure of the exposure apparatus 10 of the first embodiment will be described using Fig. 1. Fig. 1 is a diagram schematically showing the structure of the exposure apparatus 10 of the first embodiment.

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

[0015] Below, the direction (scanning direction) of driving the mask MSK and the substrate P during scanning exposure is set as the X-axis direction, the direction in the horizontal plane orthogonal to it is set as the Y-axis direction, the direction orthogonal to the X-axis and the Y-axis is set as the Z-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis and Z-axis are set as θx, θy and θz directions respectively.

[0016] The exposure device 10 includes an illumination system IOP, a mask stage MST holding a mask MSK, a projection optical system PL, a main body 70 supporting them, a substrate stage PST holding a substrate P, and a control system thereof. The control system controls the components of the exposure device 10 in an integrated manner.

[0017] The main body 70 includes a base (anti-vibration table) 71, columns 72A, 72B, an optical pressure plate 73, a support body 74, and a slider guide 75. The base (anti-vibration table) 71 is arranged on the floor F, and supports the columns 72A, 72B, etc. by eliminating the vibration from the floor F. The columns 72A and 72B each have a frame shape, and the column 72A is arranged inside the column 72B. The optical pressure plate 73 has a flat plate shape and is fixed to the top of the column 72A. The support body 74 is supported on the top of the column 72B via the slider guide 75. The slider guide 75 has an air ball lifter and a positioning mechanism to position the support body 74 (i.e., the mask stage MST described below) at an appropriate position in the X-axis direction relative to the optical pressure plate 73.

[0018] The illumination system IOP is disposed above the main body 70. The illumination system IOP irradiates the illumination light IL to the mask MSK. The detailed structure of the illumination system IOP will be described below.

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

[0020] The position information of the mask stage MST in the XY plane (including the rotation information in the θz direction) is measured by the interferometer system. The interferometer system measures the position of the mask stage MST by irradiating the moving mirror (or the reflective surface (not shown) processed by the mirror) at the end of the mask stage MST with a measuring beam and receiving the reflected light from the moving mirror. The measurement result is provided to the control device (not shown), and the control device drives the mask stage MST through the drive system according to the measurement result of the interferometer system.

[0021] The projection optical system PL is supported on the optical platen 73 below the mask stage MST (-Z side). The projection optical system PL is configured in the same manner as the projection optical system disclosed in the specification of U.S. Patent No. 5,729,331, for example, and includes a projection area of ​​the pattern image of the mask MSK, for example, a plurality of (for example, 7) projection optical units 100 (multi-lens projection optical units) arranged in a zigzag manner, forming a rectangular image field with the Y-axis direction as the length direction. Here, four projection optical units 100 are arranged at a predetermined interval along the Y-axis direction, and the remaining three projection optical units 100 are separated from the four projection optical units 100 on the +X side and arranged at a predetermined interval along the Y-axis direction. As each of the plurality of projection optical units 100, for example, an equal magnification system with telecentricity on both sides is used to form an erect image. Furthermore, the plurality of projection areas of the projection optical units 100 arranged in a zigzag manner are collectively referred to as an exposure area.

[0022] If the illumination area on the mask MSK is illuminated by the illumination light IL from the illumination system IOP, the projection image (partial erect image) of the circuit pattern of the mask MSK in the illumination area is formed in the irradiation area (exposure area (conjugate with the illumination area)) on the substrate P arranged on the image plane side of the projection optical system PL by the illumination light IL passing through the mask MSK. Here, a photoresist (sensing agent) is coated on the surface of the substrate P. The mask stage MST and the substrate stage PST are synchronously driven, that is, the mask MSK is driven along the scanning direction (X-axis direction) relative to the illumination area (illumination light IL), and the substrate P is driven along the same scanning direction relative to the exposure area (illumination light IL), whereby the substrate P is exposed and the pattern of the mask MSK is transferred to the substrate P.

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

[0024] The position information (rotation information (including yaw (rotation θz in the θz direction), pitch (rotation θx in the θx direction), and roll (rotation θy in the θy direction)) of the substrate stage PST in the XY plane is measured by the interferometer system. The interferometer system measures the position of the substrate stage PST by irradiating a length measuring beam from the optical pressure plate 73 to a movable mirror (or a reflective surface (not shown) processed by a mirror) disposed at the end of the substrate stage PST and receiving the reflected light from the movable mirror. The measurement result is provided to a control device (not shown), and the control device drives the substrate stage PST according to the measurement result of the interferometer system.

[0025] In the exposure device 10, alignment measurement (such as EGA, etc.) is performed before exposure, and the result is used to expose the substrate P in the following order. First, according to the instruction of the control device, the mask stage MST and the substrate stage PST are synchronously driven along the X-axis direction. Thereby, the first irradiation area on the substrate P is subjected to scanning exposure. When the scanning exposure for the first irradiation area is completed, the control device moves (steps) the substrate stage PST to a position corresponding to the second irradiation area. And, the second irradiation area is subjected to scanning exposure. Similarly, the control device repeats the stepping between the irradiation areas of the substrate P and the scanning exposure of the irradiation areas, and transfers the pattern of the mask MSK to all the irradiation areas on the substrate P.

[0026] (Composition of the lighting system IOP) Next, the configuration of the illumination system IOP in the present embodiment will be described. The illumination system IOP includes a plurality of illumination units 90 corresponding to the plurality of projection optical units 100 included in the projection optical system PL.

[0027] FIG2 is a diagram schematically showing the structure of the lighting unit 90. As shown in FIG2, the lighting unit 90 includes a first light source unit OPU1, a second light source unit OPU2, and an illumination optical system 80.

[0028] (Composition 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] FIG3(A) is a top view schematically showing the configuration of the first light source array 20A and the second light source array 20B. The first light source array 20A includes, for example, a plurality of (5×5 in FIG3(A)) LED (Light Emitting Diode) chips 23A arranged on a substrate 21A. The number of LED chips 23A can be appropriately changed as needed. Each of the plurality of LED chips 23A has a light emitting portion 231A, and the peak wavelength of the light emitted from the light emitting portion 231A is in the range of 380 to 390 nm. That is, the light emitting portion 231A is an ultraviolet LED (UV LED). The peak wavelength of the light emitted from the light emitting portion 231A is more preferably 385 nm. The light emitting surface of the light emitting portion 231A is a square, and the length of one side thereof 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.

[0030] The second light source array 20B includes, for example, a plurality of (5×5 in FIG. 3(A)) LED chips 23B arranged on a substrate 21B. The number of LED chips 23B can be appropriately changed 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 within the range of 360 to 370 nm. That is, the light emitting portion 231B is a UV LED. The peak wavelength of the light emitted from the light emitting portion 231B is more preferably 365 nm. The light emitting surface of the light emitting portion 231B is a square, and the length of one side thereof 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. Also, 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. Furthermore, the LED chips 23A and 23B may be arranged on a heat sink instead of a substrate, for example.

[0032] FIG. 3(B) is a diagram schematically showing the internal structure of the first light source unit OPU1 and the second light source unit OPU2. The internal structure of the first light source unit OPU1 and the second light source unit OPU2 is the same, so the structure of the first light source unit OPU1 is representatively described here. Here, the two directions in which the LED chips 23A are arranged are set as the X1 direction and the Y1 direction. The X1 direction is orthogonal to the Y1 direction. In addition, the direction orthogonal to the X1 direction and the Y1 direction is set as the Z1 direction. The Z1 direction is roughly parallel to the optical axis OA of the light emitted by the light emitting portion 231A. In FIG. 3(B), for the purpose of clarifying the diagram, only four LED chips 23A arranged in a row along the Y1 direction are shown.

[0033] As shown in FIG3(B), the first magnifying optical system 30A is a magnifying optical system for forming magnified images of the light emitting portion 231A of each LED chip 23A on a predetermined surface PP. The first magnifying optical system 30A includes a plurality of lens portions 31A arranged in a manner corresponding to the arrangement of the LED chips 23A. Each lens portion 31A is a bilateral 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 planoconvex lenses, but the present invention is not limited thereto, and each lens portion 31A may include, for example, two biconvex lenses or three biconvex lenses. In addition, each lens portion 31A may include, for example, a planoconvex lens and a biconvex lens.

[0035] In this embodiment, the lens portion 31A magnifies and projects the light emitting portion 231A at a magnification of M1 = (the arrangement pitch P1 of the LED chips 23A) / (the length a1 of one side of the light emitting surface of the light emitting portion 231A). On the other hand, the lens portion 31B included in the second magnifying optical system 30B magnifies and projects the light emitting portion 231B at a magnification of M2 = (the arrangement pitch P2 of the LED chips 23B) / (the length a2 of one side of the light emitting surface of the light emitting portion 231B). Thus, the magnified images of the plurality of light emitting portions 231A (231B) are almost in contact with each other on the predetermined plane PP.

[0036] (Configuration of Illumination Optical System 80) 2 again, the structure of the illumination optical system 80 will be described. The illumination optical system 80 includes a first light-converging optical system (first optical system) 81A including a first dichroic mirror DM1, a second light-converging optical system (second optical system) 81B, a second dichroic mirror DM2, an imaging optical system 83, a fly-eye lens FEL, an aperture stop 85, and a light-converging (condenser) optical system 84.

[0037] The first light-converging optical system 81A forms the pupil of the magnified image of the light-emitting portion 231A formed by the first magnifying optical system 30A. That is, the rear focal position of the first light-converging optical system 81A is the position of the pupil. The first light-converging optical system 81A has a first dichroic mirror DM1 in the middle of the optical path, and reflects at least a part of the light with a peak wavelength of 385 nm. Thereby, the light beam is incident on the second dichroic mirror DM2. Furthermore, the first light-converging optical system 81A may also be a structure without the first dichroic mirror DM1. In this case, the configuration of the first light source unit OPU1 and the configuration of each lens of the first light-converging optical system 81A may be appropriately adjusted so that the light beam is incident on the second dichroic mirror DM2. Furthermore, the first light-converging optical system 81A may be composed of a single lens or a lens group including a plurality of lenses.

[0038] The second condensing optical system 81B forms the pupil of the magnified image of the light emitting portion 231B formed by the second magnifying optical system 30B. That is, the rear focus position of the second condensing optical system 81B is the position of the pupil. The second condensing optical system 81B may be composed of a single lens or a lens group including a plurality of 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. Thus, a composite image is formed by overlapping the pupil image formed by the first condensing optical system 81A and the pupil image formed by the second condensing optical system 81B.

[0040] In this embodiment, the second dichroic mirror DM2 overlaps the pupil image formed by the first light-converging optical system 81A and the pupil image formed by the second light-converging optical system 81B to form a composite image. That is, the second dichroic mirror DM2 is arranged at a position that is the rear focal position of the first light-converging optical system 81A and the rear focal position of the second light-converging optical system 81B. Thereby, the second dichroic mirror DM2 is Kohler illuminated by the light emitted from the first light source unit OPU1 and the light emitted from the second light source unit OPU2. By Kohler illumination, the illumination change of the light beam of the pupil image formed by the first light-converging optical system 81A and the illumination change of the light beam of the pupil image formed by the second light-converging optical system 81B can be reduced. Furthermore, the second dichroic mirror DM2 may not necessarily be arranged at the position serving as the rear focal position of the first condensing optical system 81A and the rear focal position of the second condensing optical system 81B, but may be arranged in the vicinity of the respective rear focal positions. Here, vicinity means within ±100 mm, preferably within ±50 mm, and more preferably ±20 mm from the rear focal position along the optical axis. Furthermore, the sign here sets the direction in which the light from the light source travels along the optical axis as positive, and the opposite direction as negative.

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

[0042] As shown in FIG4 , when the dichroic mirror is subjected to critical illumination (i.e., when the image of the light source is formed at the position of the dichroic mirror), the incident angle of the light beam on the dichroic mirror is within the range of the designed incident angle α±8°, resulting in an illumination change of more than 3%. On the other hand, when the dichroic mirror is subjected to Koehler illumination, the incident angle of the light beam on the dichroic mirror is within the range of the designed incident angle α±4°, and the illumination change can be reduced to less than 1%. In this way, by performing Koehler illumination on the second dichroic mirror DM2, the difference between the illumination of the light incident on the second dichroic mirror DM2 and the illumination of the light reflected by the second dichroic mirror DM2 can be reduced, thereby realizing illumination light IL with high brightness and less illumination unevenness.

[0043] In this embodiment, the incident angle θ of the light from the second light-converging optical system 81B to the second dichroic mirror DM2 is set to 35°. The incident angle θ of 35° means that the incident angle θ is within the range of 35°±5°. Furthermore, the incident angle θ is preferably 25° or more and less than 45°, more preferably 25° or more and 42° or less, and further preferably 35°±5°. Thus, the second dichroic mirror DM2 can reflect the light beam of the pupil image formed by the second light-converging optical system 81B with higher efficiency.

[0044] Returning to FIG. 2 , the lighting 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, the detector DT10 detects the illuminance of the light with a peak wavelength of 385 nm reflected by the first dichroic mirror DM1. The detector DT20 detects the illuminance of the light with a peak wavelength of 365 nm reflected by the second dichroic mirror DM2. The detector DT30 detects the illuminance of the light with a peak wavelength of 385 nm unintentionally reflected by the second dichroic mirror DM2 and the illuminance of the light with a peak wavelength of 365 nm unintentionally transmitted by the second dichroic mirror DM2.

[0046] The detection results of detectors DT10~DT30 are output to a control device not shown in the figure. Based on the detection results of detectors DT10~DT30, the control device controls the value of the current supplied to the LED chips 23A and 23B respectively possessed by the first light source unit OPU1 and the second light source unit OPU2.

[0047] The imaging optical system 83 is a telecentric optical system on both sides that projects the composite image synthesized by the second dichroic mirror DM2 to the incident end of the fly-eye lens FEL at the same magnification. Furthermore, the imaging optical system 83 can also reduce the composite image synthesized by the second dichroic mirror DM2 and project it to the incident end of the fly-eye lens FEL.

[0048] The fly-eye lens FEL is formed by arranging a plurality of lens elements having positive refractive power, for example, in a manner that their optical axes are parallel to the reference optical axis AX, vertically and horizontally and densely. Each lens element constituting the fly-eye lens FEL has a rectangular cross-section similar to the shape of the irradiation field to be formed on the mask MSK (and thus 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 divided by the wavefronts of the plurality of lens elements, and a light source image is formed on the rear focal plane (exit plane) of each lens element or in its vicinity. That is, a substantial surface light source, i.e., a secondary light source, composed of a plurality of light source images is formed on the rear focal plane (exit plane) of the fly-eye lens FEL or in its vicinity. The light beam from the secondary light source formed on the rear focal plane (exit plane) of the fly-eye lens FEL or in its vicinity is incident on the aperture stop 85 arranged in its vicinity. Furthermore, in the present embodiment, the rear focal plane (exit plane) 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 arranged at a position substantially optically conjugate with the incident pupil plane of the projection optical unit 100, and has a variable opening portion for determining the range of illumination that contributes to the secondary light source. Furthermore, the aperture stop 85 sets the σ value (the ratio of the aperture of the secondary light source image on the pupil plane to the aperture of the pupil plane of the projection optical unit 100) that determines the illumination condition to a desired value by changing the aperture of the variable opening portion. The light from the secondary light source passing through the aperture stop 85 is condensed by the condensing optical system 84, and then superimposedly illuminates the mask MSK having a predetermined pattern.

[0051] As described above, the lighting unit 90 of the first embodiment includes: a first light source array 20A in which a plurality of LED chips 23A having light emitting portions 231A emitting light having a peak wavelength of 385 nm are arranged; a first magnifying optical system 30A in which a magnified image of the light emitting portion 231A of each LED chip 23A is formed; and a first condensing optical system 81A in which a pupil of the magnified image formed by the first magnifying optical system 30A is formed. Furthermore, the lighting unit 90 includes: a second light source array 20B in which a plurality of LED chips 23B having light emitting portions 231B emitting light having a peak wavelength of 365 nm are arranged; a second magnifying optical system 30B in which a magnified image of the light emitting portion 231B of each LED chip 23B is formed; and a second condensing optical system 81B in which a pupil of the magnified image formed by the second magnifying optical system 30B is formed. Furthermore, the illumination unit 90 includes a second dichroic mirror DM2 for superimposing the pupil image formed by the first condensing optical system 81A and the pupil image formed by the second condensing optical system 81B to form a composite image.

[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 perform Köhler illumination on the second dichroic mirror DM2. Therefore, as shown in FIG. 4 , compared with the case where critical illumination is performed on the second dichroic mirror DM2, illumination light IL having high brightness and less illumination unevenness can be achieved.

[0053] In the first embodiment, the first magnifying optical system 30A is a lens array having a plurality of lens portions 31A arranged in a manner corresponding to each of the light emitting portions 231A, and the second magnifying optical system 30B is a lens array having a plurality of lens portions 31B arranged in a manner corresponding to each of the light emitting portions 231B. Moreover, each of the lens portions 31A of the first magnifying optical system 30A is a bilateral telecentric optical system that magnifies and projects the light emitting portion 231A at a magnification ratio of (the arrangement pitch P1 of the LED chips 23A) / (the length a1 of one side of the light emitting surface of the light emitting portion 231A). Moreover, each of the lens portions 31B of the second magnifying optical system 30B is a bilateral telecentric optical system that magnifies and projects the light emitting portion 231B at a magnification ratio of (the arrangement pitch P2 of the LED chips 23B) / (the length a2 of one side of the light emitting surface of the light emitting portion 231B). Thereby, a surface light source can be formed in which magnified images of a plurality of light-emitting portions 231A (231B) are almost in contact with each other on a given surface PP.

[0054] Furthermore, in the first embodiment, the illumination unit 90 includes a fly-eye lens FEL for emitting a light beam of a synthetic image synthesized by the second dichroic mirror DM2 as a light beam with uniform illumination distribution, and a telecentric imaging optical system 83 for equally projecting the synthetic image synthesized by the second dichroic mirror DM2 to the incident end of the fly-eye lens FEL. Thus, the mask MSK can be illuminated uniformly.

[0055] Furthermore, in the first embodiment, the incident angle of the light beam of the pupil image formed by the second condensing optical system 81B to the second dichroic mirror DM2 is 35°. Thus, the light beam of the pupil image formed by the second condensing optical system 81B can be reflected with high efficiency.

[0056] Furthermore, in the above-mentioned first embodiment, 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 is incident on the second dichroic mirror DM2, but the first dichroic mirror DM1 may be omitted so that the light with a peak wavelength of 385 nm emitted from the first light source unit OPU1 is directly incident on the second dichroic mirror DM2.

[0057] Furthermore, 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 reflect at least a portion of the light with a peak wavelength of 365 nm, and the second dichroic mirror DM2 may 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] Furthermore, the wavelengths of the light emitted by the first light source unit OPU1 and the second light source unit OPU2 are not limited to the above, and the first light source unit OPU1 and the second light source unit OPU2 may be formed by appropriately combining LED chips that emit light with a peak wavelength in the range of 360 to 440 nm. For example, the first light source unit OPU1 may emit light with a peak wavelength of 405 nm, and the second light source unit OPU2 may emit light with a peak wavelength of 385 nm. Furthermore, the first light source unit OPU1 may emit light with a peak wavelength of 395 nm, and the second light source unit OPU2 may emit light with a peak wavelength of 385 nm. The combination of the wavelength of the light emitted from the first light source unit OPU1 and the wavelength of the light emitted from the second light source unit OPU2 is not limited to the examples. Furthermore, when 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 made to be a combination other than the first embodiment, it is preferable to appropriately change the material of the dichroic mirror according to the wavelength used.

[0059] 《Second Implementation Form》 Next, the second embodiment will be described. The magnifications M1 and M2 of the light emitting units 231A and 231B of the first magnifying optical system 30A and the second magnifying optical system 30B of the second embodiment are different from those of the first embodiment.

[0060] (About LED chips) Fig. 5 is a diagram 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 represents the theoretical light distribution characteristics (Lambert radiation) of the light emitting portion 231A, and the dotted line is a curve obtained by approximating the measurement results of the radiation intensity of the light emitted from the light emitting portion 231A using a sixth-order polynomial.

[0061] In the example of FIG. 5 , among the light emitted from the light emitting portion 231A, the radiation intensity of the light in the range of the emission angle greater than -50° and less than 50° is higher than the radiation intensity of the Lambertian radiation, and the radiation intensity of the light in the range of the emission angle less than -50° and more than 50° is lower than the radiation intensity of the Lambertian radiation. In this way, among the light emitted from the light emitting portion 231A, there is a range of emission angles where the radiation intensity is higher than the radiation intensity of the Lambertian radiation. Therefore, it is considered that by using the light in the range (in the example of FIG. 5 , the range of ±50°) of the light emitted from the light emitting portion 231A, the brightness of the light emitted from the first light source unit OPU1 can be increased.

[0062] In contrast, in the second embodiment, the magnification M1 when the first magnifying optical system 30A magnifies and projects the light emitting portion 231A is set so as to satisfy the following formula (1). P1 / a1 <M1≦sinα 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 α1 is the maximum emission angle of the light emitted from the light emitting portion 231A, which has a radiation intensity higher than that of Lambertian radiation. θ1 is the maximum emission angle of the light emitted from the first magnifying optical system 30A. Furthermore, sinθ1 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 equal to 1. Furthermore, when 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 can be set in the X1 direction and the Y1 direction respectively in a manner that satisfies the formula (1).

[0064] Furthermore, the magnification M2 when the second magnifying optical system 30B magnifies and projects the light emitting portion 231B is set so as to satisfy the following formula (2). P2 / a2 <M2≦sinα 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, α2 is the maximum emission angle of the light having a radiation intensity higher than the Lambertian radiation among the light emitted from the light emitting portion 231B, and θ2 is the maximum emission angle of the light emitted from the second magnifying optical system 30B. Furthermore, sinθ2 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 equal to 1. Furthermore, when 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 can be set in the X1 direction and the Y1 direction respectively in a manner that satisfies the formula (2).

[0066] By enlarging the light emitting parts 231A and 231B by the magnification M1 satisfying the formula (1) and the magnification M2 satisfying the formula (2), the enlarged images of the light emitting surfaces of the light emitting parts 231A and 231B except for the peripheral portions are connected to each other on the predetermined plane PP. This aspect is described below.

[0067] Fig. 6 (A) and Fig. 6 (B) are diagrams for explaining the enlarged image formed on the predetermined surface PP in the second embodiment. More specifically, Fig. 6 (A) is a top view showing the arranged LED chips 23A, and Fig. 6 (B) is a top view showing the enlarged image formed on the predetermined surface PP. In order to simplify the diagram, the description is made using 2×2 rows of LED chips 23A.

[0068] As shown in FIG6(A), in 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 other than the peripheral region 231b is defined as the central region 231a. In this case, if the magnified image of the light-emitting portion 231A is formed at a magnification M1 satisfying the formula (1), then as shown in FIG6(B), on a given plane PP, the magnified images MI1 of the central region 231a are connected to each other, and the magnified image MI2 of the light-emitting portion 231A including the central region 231a and the peripheral region 231b is formed in a partially overlapping manner.

[0069] By magnifying the light-emitting units 231A and 231B at magnification factors M1 and M2 that respectively satisfy equations (1) and (2), a surface light source is formed on a predetermined surface PP by light with a radiation intensity higher than Lambert radiation. Therefore, the intensity of the light emitted from the first light source unit OPU1 and the second light source unit OPU2 can be increased. In other words, a surface light source is formed by the light emitted from the region (central region 231a) on the light-emitting surfaces of the light-emitting units 231A and 231B where the radiation intensity is higher than Lambert radiation, thereby increasing 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 factor M1 of the light-emitting unit 231A of the first magnification optical system 30A is changed, and the illuminance on a predetermined surface of the magnified image formed by the first magnification optical system 30A is simulated. The simulation conditions are as follows. LED chip 23A: NVSU233B manufactured by Nichia Chemical Industries, Ltd. Length of one side of the light-emitting surface of the light-emitting unit 231A: 1.4 mm Arrangement pitch P1: 4 mm α1: 50° θ1: 8°

[0071] In this case, the condition for the magnification factor M1 is 4 mm / 1.4 mm = 2.9 < M1 ≤ sin50° / sin8° = 5.5. In contrast, the illuminance is simulated for the cases where the magnification factor M1 = 2.79 and the magnification factor M1 = 3.6 times.

[0072] Figure 7(A) is a diagram showing the simulation results. In Figure 7(A), the horizontal axis represents the magnification factor, and the vertical axis is the illuminance ratio with the illuminance when the magnification factor M1 = 2.79 set to 1. As shown in Figure 7(A), it is confirmed that by making the magnification factor M1 greater than P1 / a1, the illuminance is increased compared to the case where the magnification factor M1 is set to P1 / a1.

[0073] [Simulation 2] Using an LED chip 23A different from the one used in Simulation 1, the illuminance is simulated by changing the magnification factor 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 Arrangement pitch P1: 7 mm α1: 50° θ 1: 8°

[0074] In this case, the condition for the magnification M1 is 7 mm / 1.9 mm = 3.68 < M1 ≤ sin50° / sin8° = 5.5. For this, the simulated illuminance is performed in 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 the 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 is confirmed that by making the magnification M1 greater than P1 / a1, the illuminance can be increased compared to the case where the 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 magnifies and projects the light emitting portion 231A satisfies P1 / a1 < M1 ≤ sinα1 / sinθ1, and the magnification M2 when the second magnifying optical system 30B magnifies and projects the light emitting portion 231B satisfies P2 / a2 < M2 ≤ sinα2 / sinθ2.

[0077] Since the secondary light sources can be formed from light having a higher emission intensity than Lambert emission by setting the magnifications M1 and M2 in this way, the intensity of the light emitted from the first light source unit OPU1 and the second light source unit OPU2 can be increased.

[0078] Also, in the manufacturing steps 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, positional deviations of the LED chips 23A and 23B may occur. Due to the positional deviations, the illuminance of the first light source array 20A and the second light source array 20B may be reduced. In this embodiment, since by making the magnifications M1 and M2 greater 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 other than the peripheral portion) can be used, even if the LED chips 23A and 23B are positionally deviated, the reduction in the illuminance of the first light source array 20A and the second light source array 20B can be suppressed.

[0079] Also, in the second embodiment, sinθ1 and sinθ2 are values obtained by setting 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. Thereby, the illumination light IL having a brightness corresponding to the numerical aperture required in the exposure apparatus 10 can be realized.

[0080] The above-mentioned embodiments are preferred embodiments of the present invention, but are not limited thereto, and various modifications can be implemented within the scope of the present invention.

[0081] 10: Exposure device 20A: 1st light source array 20B: Second light source array 21A, 21B: substrate 23A, 23B: LED chips 231a: Central area 231b: Peripheral area 30A: 1st magnification optical system 30B: Second magnification optical system 31A, 31B: Lens section 70: Main body 71: Base (anti-vibration table) 72A, 72B: Column 73: Optical pressure plate 74: Support 75: Slider guide seat 80:Illumination optical system 81A: 1st focusing optical system 81B: Second focusing optical system 83: Imaging optical system 84: Focusing optical system 85: Aperture diaphragm 90: Lighting unit 100: Projection optical unit AX: Reference optical axis a1, a2: length of one side DM1: 1st dichroic mirror 231A, 231B: Light emitting unit DM2: Second dichroic mirror DT10, DT20, DT30: Detectors F: Floor FEL: Fly Eye Lens IL: Illumination light IOP: Lighting System MI1, MI2: Enlarged image MSK: Photomask MST: Mask Platform OA: Optical Axis OPU1: Light source unit 1 OPU2: Second light source unit P: Substrate PP:Predetermined surface P1, P2: Arrangement spacing PL: Projection Optical System PST: Substrate Platform θ: incident angle

Claims

1. A light source unit comprising: a light source array having a plurality of light source elements having light-emitting portions having emitted light arranged on a two-dimensional plane; and a magnifying optical system for forming a magnified image of the light-emitting portion of each of the light source elements; wherein the magnifying optical system is a telecentric optical system that magnifies the projection at a magnification M, and wherein when the arrangement spacing of the light source elements is set to p and the length of one side of the light-emitting surface of the light-emitting portion is set to a, the magnification M satisfies the condition p / a < M.

2. The light source unit as described in claim 1, wherein, The light-emitting part mentioned above is an ultraviolet light-emitting diode.

3. The light source unit as described in claim 1 or 2, wherein, The peak wavelength of the light emitted from the aforementioned light-emitting part is in the range of 360–440 nm.

4. An illumination unit comprising: a light source unit as described in any one of claims 1 to 3; and an illumination optical system that guides light emitted from the light source unit to an irradiated object.

5. An illumination unit comprising: a plurality of light source units as described in any one of claims 1 to 3; and an illumination optical system comprising a combining optical element for combining light emitted from the plurality of light source units, and guiding the combined light emitted from the combining optical element to an irradiated object.

6. An exposure apparatus comprising: an illumination unit as described in claim 4 or 5, and a projection optical system for projecting a pattern image of the irradiated object illuminated by the illumination unit onto a photosensitive substrate.

7. The exposure apparatus as described in claim 6, wherein, The length of at least one side or the diagonal length of the aforementioned photosensitive substrate is 500 mm or more.

8. An exposure method using an exposure apparatus as described in claim 6 or 7, comprising the steps of: illuminating the object to be irradiated using the illumination unit; and projecting a pattern image of the object to the photosensitive substrate using the projection optics system.

Images