Drive method, light source unit, illumination unit, exposure device, and exposure method

Abstract

This drive method for a light source element which emits light in a first light emission amount when supplied with a current of a first current value includes: initiating current supply to the light source element at a second current value lower than the first current value; and increasing the current value of the current being supplied to the light source element to the first current value. The current value of a current to be supplied to the light source element at a first time point is a corrected current value obtained by: acquiring the current value of a current to be supplied to the light source element at the first time point from first information in which the current value of a current to be supplied to the light source element at each time point, in a period during which the current supply to the light source element is initiated at a predetermined third current value and the current value of a current being supplied to the light source element is increased to the first current value, is predetermined; and correcting the acquired current value on the basis of the temperature of the light source element.

Description

Driving method, light source unit, lighting unit, exposure apparatus, and exposure method

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

[0002] In recent years, liquid crystal display panels have come into widespread use as display elements for personal computers, televisions, and the like. Liquid crystal display panels are manufactured by forming a circuit pattern of thin-film transistors on a plate (glass substrate) using a photolithography technique. An exposure apparatus is used for this photolithography process, which projects and exposes an original pattern formed on a mask onto a photoresist layer on the plate via a projection optical system (see, for example, Patent Document 1).

[0003] In light sources used in various optical devices including the above-mentioned exposure device, it is required to stabilize the amount of light emitted from the light source.

[0004] JP 2013-207251 A

[0005] According to a first aspect of the disclosure, a method for driving a light source element is a method for driving a light source element that emits light at a first light emission amount when a current of a first current value is supplied, the method including starting current supply to the light source element at a second current value lower than the first current value, and increasing the current value of the current supplied to the light source element to the first current value, wherein the current value of the current supplied to the light source element at a first time point is obtained from predetermined first information at each time point during a period in which current supply to the light source element is started at a predetermined third current value and the current value of the current supplied to the light source element is increased to the first current value, and the current value of the current supplied to the light source element at the first time point is a corrected current value obtained by correcting the obtained current value based on the temperature of the light source element.

[0006] According to a second aspect of the disclosure, a method for driving a light source element is a method for driving a light source element that, when supplied with a current of a first current value, emits light at a first light emission amount, and, when supplied with a current of a fifth current value lower than the first current value, emits light at a second light emission amount lower than the first light emission amount, the method includes starting to supply current to the light source element at a sixth current value higher than the fifth current value, and reducing the current value of the current supplied to the light source element from the sixth current value to the fifth current value, wherein the current value of the current supplied to the light source element at a first time point is obtained from predetermined third information, and the current value of the current supplied to the light source element at each time point during a period in which current supply to the light source element is started at a predetermined seventh current value and the current value of the current supplied to the light source element is changed up to the fifth current value, and the current value of the current supplied to the light source element at the first time point is a corrected current value obtained by correcting the obtained current value based on the temperature of the light source element.

[0007] According to a third aspect of the disclosure, the light source unit includes a plurality of light source elements that are two-dimensionally arranged on the surface of a fixed object, each emitting light at a first light emission amount when supplied with current of a first current value, a detection unit that detects the temperature of the plurality of light source elements, and a control unit that controls the value of the current supplied to the plurality of light source elements, wherein the control unit starts supplying current to the plurality of light source elements at a second current value lower than the first current value, and increases the current value of the current supplied to the plurality of light source elements from the second current value to the first current value, and the current value of the current supplied to the plurality of light source elements at a first time point is a corrected current value obtained by acquiring from predetermined first information the current value of the current supplied to the plurality of light source elements at the first time point during a period in which current supply to the plurality of light source elements is started at a predetermined third current value and the current value of the current supplied to the plurality of light source elements is increased to the first current value, and the acquired current value is a corrected current value obtained by correcting the acquired current value based on the temperature of the plurality of light source elements.

[0008] According to a fourth aspect of the disclosure, the light source unit includes a plurality of light source elements that are two-dimensionally arranged on a surface of a fixed object, each emitting light at a first light emission amount when supplied with a current of a first current value, and each emitting light at a second light emission amount lower than the first light emission amount when supplied with a current of a fifth current value lower than the first current value; a detection unit that detects the temperature of the plurality of light source elements; and a control unit that controls the value of the current supplied to the plurality of light source elements. and when the control unit puts the plurality of light source elements into a state in which they emit light at the second light emission amount, the control unit starts supplying current to the plurality of light source elements at a sixth current value higher than the fifth current value, and reduces the current value of the current supplied to the plurality of light source elements from the sixth current value to the fifth current value, and the current value of the current supplied to the plurality of light source elements at a first time point is a corrected current value obtained by acquiring from third information predetermined current values ​​to be supplied to the plurality of light source elements at each time point during a period in which current supply to the plurality of light source elements is started at a predetermined seventh current value and the current value of the current supplied to the plurality of light source elements is changed to the fifth current value, and the acquired current values ​​are corrected current values ​​obtained by correcting the acquired current values ​​based on the temperatures of the plurality of light source elements.

[0009] According to a fifth aspect of the disclosure, an illumination unit includes the light source unit and an illumination optical system that guides light emitted from the light source unit to an object to be illuminated.

[0010] According to a sixth aspect of the disclosure, the lighting unit comprises a plurality of the above-mentioned light source units, and an illumination optical system including a combining optical element that combines light emitted from the plurality of light source units and directs the combined light emitted from the combining optical element to an illuminated object.

[0011] According to a seventh 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.

[0012] According to an eighth aspect of the disclosure, an exposure method is an exposure method using the above-mentioned exposure apparatus, and includes illuminating a mask with the illumination unit and projecting a pattern image of the mask onto a photosensitive substrate using the projection optical system.

[0013] 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.

[0014] FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus according to a first embodiment. FIG. 2 is a schematic diagram showing the configuration of an illumination unit according to the first embodiment. FIG. 3A is a plan view showing the configuration of a light source array, and FIG. 3B is a view showing the internal configuration of a light source unit. FIG. 4 is a diagram illustrating the relationship between the temperature of an LED package and the amount of light emitted. FIG. 5 is a graph showing the measurement results of the amount of light emitted by the light-emitting unit of an LED package when a current is supplied to the LED package at a first current value from the start of current supply, when the temperature of the LED package is lower than a first temperature threshold and no current is being supplied, so that the light-emitting unit of the LED package emits light at a first amount of light. FIG. 6 is a diagram showing output versus elapsed time. FIG. 7 is an example of a one-stage map. Fig. 8A is a graph showing the measurement results of the light emission amount of the light-emitting unit of the LED package when the value of the current supplied to the LED package is controlled according to a first one-step map when the light-emitting unit of the LED package is set to emit light at a first light emission amount when the temperature is lower than a first temperature threshold and no current is being supplied thereto. Fig. 8B is a graph showing the range of the light emission amount deviation rate on the vertical axis in Fig. 8A enlarged from 0% to 2%. Fig. 9 is a graph showing the measurement results of the light emission amount of the light-emitting unit of the LED package when the value of the current supplied to the LED package is controlled according to a first two-step map when the light-emitting unit of the LED package is set to emit light at a first light emission amount when the temperature is lower than a first temperature threshold and no current is being supplied thereto. Fig. 10 is a graph showing the measurement results of the light emission amount of the light-emitting unit of the LED package when the value of the current supplied to the LED package is controlled according to a second two-step map when the light-emitting unit of the LED package of the light source array is set to emit light at a second light emission amount when the temperature is lower than a second temperature threshold and no current is being supplied thereto. Figures 11(A) and 11(B) are graphs showing the measurement results of the light emission amount of the light-emitting portion of the LED package when the current value of the current supplied to the LED package is controlled according to the first two-stage map in the fourth and fifth cases, respectively.FIG. 12(A) is a graph showing the measurement results of the amount of light emitted by the light-emitting portion of the LED package when the current value of the current supplied to the LED package is controlled according to the second two-stage map in the sixth case. FIG. 12(B) is a graph showing the measurement results of the amount of light emitted by the light-emitting portion of the LED package when the current value of the current supplied to the LED package is controlled according to the second two-stage map in the seventh case. FIG. 13 is a plan view showing a light source array provided in a light source unit according to the second embodiment. FIG. 14(A) is an example of a temperature map, and FIG. 14(B) is an example of the first two-stage map. FIG. 15(A) is a graph showing the actual temperature of the LED package versus the elapsed time since the supply of current was resumed (started), and FIG. 15(B) is a graph showing the current value of the current actually supplied to the LED package obtained by correcting the first two-stage map according to the actual temperature of the LED package. 16(A) and 16(B) are graphs showing the measurement results of the amount of light emitted by the LED package when the first two-stage map is corrected in accordance with the actual temperature of the LED package to control the value of the current supplied to the LED package in Cases 4 and 5. Fig. 17(A) is a graph showing the measurement results of the amount of light emitted by the LED package when the second two-stage map is corrected in accordance with the actual temperature of the LED package to control the value of the current supplied to the LED package in Case 6, and Fig. 17(B) is a graph showing the measurement results of the amount of light emitted by the LED package when the second two-stage map is corrected in accordance with the actual temperature of the LED package to control the value of the current supplied to the LED package in Case 7.18A is a graph showing the measurement results of the light emission amount of the light-emitting unit of the LED package when the first two-stage map is corrected in accordance with the actual temperature of the LED package to control the value of the current supplied to the LED package 23 in order to set the light-emitting unit of the LED package in a state where the temperature is lower than the first temperature threshold and no current is being supplied to emit light at a first light emission amount. FIG. 18B is a graph showing the measurement results of the light emission amount of the light-emitting unit of the LED package when the second two-stage map is corrected in accordance with the actual temperature of the LED package to control the value of the current supplied to the LED package in order to set the light-emitting unit of the LED package in a state where the temperature is lower than the second temperature threshold and no current is being supplied to emit light at a second light emission amount. FIG. 19 is a schematic diagram showing the configuration of an illumination unit according to a third embodiment. FIG. 20 is a schematic diagram showing the configuration of an exposure apparatus according to a fourth embodiment.

[0015] An exposure apparatus 10 according to one embodiment will be described with reference to FIGS.

[0016] (Configuration of Exposure Apparatus) First, the configuration of an exposure apparatus 10 according to this embodiment will be described. Fig. 1 is a diagram that shows a schematic configuration of an exposure apparatus 10 according to this embodiment.

[0017] The exposure apparatus 10 is a scanning stepper (scanner) that drives a mask MSK and a glass substrate (hereinafter referred to as "plate") P in the same direction and at the same speed relative to a projection optical system PL, thereby transferring a pattern formed on the mask MSK onto the plate P. The plate P is a rectangular glass substrate used in, for example, a liquid crystal display device (flat panel display), and has at least one side or diagonal length of 500 mm or more.

[0018] In the following, the direction in which the mask MSK and plate P are driven during scanning exposure (scanning direction) is referred to as the X-axis direction, the direction in the horizontal plane perpendicular to this is referred to as the Y-axis direction, the direction perpendicular to the X-axis and Y-axis is referred to as the Z-axis direction, and the rotation (tilt) directions around the X-axis, Y-axis, and Z-axis are referred to as the θx, θy, and θz directions, respectively.

[0019] The exposure apparatus 10 includes an illumination system IOP, a mask stage MST that holds a mask MSK, a projection optical system PL, a body 70 that supports these, a substrate stage PST that holds a plate P, and a controller (not shown) for these components. The controller controls all of the components of the exposure apparatus 10.

[0020] 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.

[0021] 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.

[0022] 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).

[0023] Position information of the mask stage MST in the XY plane (including rotation information in the θz direction) is measured by an interferometer system. The interferometer system measures the position of the mask stage MST by irradiating a measurement beam onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the mask stage MST and receiving the light reflected from the movable mirror. The measurement results are supplied to a control device (not shown), which drives the mask stage MST via a drive system in accordance with the measurement results of the interferometer system.

[0024] The projection optical system PL is supported on an optical surface plate 73 below (on the -Z side of) the mask stage MST. The projection optical system PL is configured similarly to the projection optical system disclosed in, for example, U.S. Pat. No. 5,729,331. The projection optical system PL includes multiple (e.g., seven) projection optical units 100 (multi-lens projection optical units) arranged, for example, in a staggered pattern, to project the pattern image of the mask MSK. This forms a rectangular image field with the Y-axis direction as its longitudinal direction. Here, four projection optical units 100 are arranged at predetermined intervals in the Y-axis direction, and the remaining three projection optical units 100 are arranged at predetermined intervals in the Y-axis direction, spaced apart from the four projection optical units 100 on the +X side. Each of the multiple projection optical units 100 is, for example, a bilaterally telecentric, 1x1 system that forms an erect, normal image. The multiple projection areas of the staggered projection optical units 100 are collectively referred to as the exposure area. In this embodiment, four projection optical units 100 and three projection optical units 100 are arranged at regular intervals in the Y-axis direction, but the number of modules of the projection optical units 100 arranged at regular intervals in the Y-axis direction may be less than three or more than four. Furthermore, although two rows of the projection optical units 100 are arranged in the X-axis direction, the number of rows of the projection optical units 100 arranged in the X-axis direction may be one row or less, or three or more rows.

[0025] When an illumination area on the mask MSK is illuminated by illumination light IL from the illumination system IOP, the illumination light IL that has passed through the mask MSK forms a projected image (partial erect image) of the circuit pattern of the mask MSK within that illumination area, via the projection optical system PL, in an irradiation area (exposure area (conjugate to the illumination area)) on a plate P arranged on the image plane side of the projection optical system PL. Here, a resist (sensitizer) is applied to the surface of the plate P. By synchronously driving the mask stage MST and the substrate stage PST, i.e., by driving the mask MSK in the scanning direction (X-axis direction) relative to the illumination area (illumination light IL) and driving the plate P in the same scanning direction relative to the exposure area (illumination light IL), the plate P is exposed and the pattern of the mask MSK is transferred onto the plate P.

[0026] The substrate stage PST is placed on a base (vibration isolation table) 71 below (on the -Z side of) the projection optical system PL. A plate P is held on the substrate stage PST via a substrate holder (not shown).

[0027] 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 θy in the θy direction), and rolling amount (rotation amount θx in the θx direction)))) is measured by an interferometer system. The interferometer system measures the position of the substrate stage PST by irradiating a measurement beam from the optical surface plate 73 onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the substrate stage PST, and receiving the reflected light from the movable mirror. The measurement results are supplied to a control device (not shown), and the control device drives the substrate stage PST in accordance with the measurement results of the interferometer system.

[0028] In exposure apparatus 10, alignment measurement (e.g., EGA, etc.) is performed prior to exposure, and the plate P is exposed using the results in the following procedure. First, in accordance with instructions from the control device, the mask stage MST and substrate stage PST are synchronously driven in the X-axis direction. This performs scanning exposure on the first shot area on plate P. When scanning exposure on the first shot area is completed, the control device moves (steps) the substrate stage PST to a position corresponding to the second shot area. Then, scanning exposure is performed on the second shot area. In the same manner, the control device repeats stepping between shot areas of plate P and scanning exposure on the shot areas to transfer the pattern of the mask MSK to all shot areas on plate P.

[0029] (Configuration of illumination system IOP) Next, the configuration of illumination system IOP in this embodiment will be described. Illumination system IOP includes a plurality of illumination units 90 corresponding to the plurality of projection optical units 100 included in projection optical system PL.

[0030] 2 is a diagram schematically illustrating the configuration of the illumination unit 90. As shown in FIG. 2, the illumination unit 90 includes a light source unit OPU and an illumination optical system 80.

[0031] (Configuration of Light Source Unit) The light source unit OPU includes a light source array 20, a magnifying optical system 30, and a control unit CTR.

[0032] FIG. 3A is a plan view schematically illustrating the configuration of the light source array 20. The light source array 20 includes a plurality of LED (Light Emitting Diode) packages 23 (5×5 in FIG. 3A ) arranged in an array on a substrate 21, for example. That is, the light source unit OPU is an LED light source. The number of LED packages 23 may be changed as needed. Here, the two directions in which the LED packages 23 are arranged are defined as the X1 direction and the Y1 direction. The X1 direction and the Y1 direction are orthogonal to each other. The direction orthogonal to the X1 direction and the Y1 direction is defined as the Z1 direction. The Z1 direction is approximately parallel to the optical axis OA of light emitted by a light-emitting unit 231, which will be described later.

[0033] Each of the multiple LED packages 23 has a light-emitting portion 231, and the peak wavelength of light emitted from the light-emitting portion 231 is, for example, in the range of 360 to 370 nm, 380 to 390 nm, or 400 to 410 nm. That is, the light-emitting portion 231 is an ultraviolet LED (UV LED). The light-emitting surface of the light-emitting portion 231 is square, and the length of one side is L. The LED packages 23 are arranged at a pitch P1. The pitch P1 is the distance between the centers of adjacent LED packages 23. The LED packages 23 may be arranged not on a substrate but on, for example, a heat sink.

[0034] FIG. 3B is a diagram schematically illustrating the internal configuration of the light source unit OPU.

[0035] 3B , the magnifying optical system 30 is an optical system for forming a magnified image of the light-emitting portion 231 of each LED package 23 on a predetermined plane PP. The magnifying optical system 30 includes a plurality of lens units 31 arranged to correspond to the arrangement of the LED packages 23. Each of the lens units 31 is a double-telecentric optical system that magnifies and projects the light-emitting portion 231 at a magnification M equal to or greater than (the arrangement pitch P1 of the LED packages 23) / (the length L of one side of the light-emitting surface of the light-emitting portion 231).

[0036] In this embodiment, the lens unit 31 includes four plano-convex lenses, but is not limited to this, and may include, for example, two biconvex lenses, three biconvex lenses, or a plano-convex lens and a biconvex lens.

[0037] The control unit CTR controls the current value of the current supplied to the LED packages 23 included in the light source array 20 .

[0038] 4 is a diagram illustrating the relationship between the temperature of the LED package 23 and the amount of light emitted by the light-emitting unit 231. As shown in FIG. 4, when the temperature of the LED package 23 is within a range (first temperature range) of temperature T1 to temperature T2 (>T1), the light-emitting unit 231 of the LED package 23 emits light at a first amount of light LA1 when a current of a first current value CV1 is supplied. The first temperature range is, for example, 20°C to 90°C, or may be 20°C to 50°C.

[0039] Furthermore, when the temperature of the LED package 23 is within a range (second temperature range) of temperatures T3 to T4 (>T3), the light-emitting portion 231 of the LED package 23 emits light at a second light emission amount LA2 when a current of a third current value CV3 lower than the first current value CV1 is supplied. Note that temperature T3 is lower than temperature T1, and temperature T4 is lower than temperature T2.

[0040] In the present embodiment, when the temperature is lower than a first temperature threshold Tth1 (e.g., 15° C.) and no current is being supplied to the light-emitting unit 231 of the LED package 23, the control unit CTR starts supplying current to the LED package 23 at a second current value CV2 that is lower than the first current value CV1, and increases the current value of the current supplied to the LED package 23 to the first current value CV1. This reduces the time required for the light-emitting unit 231 of the LED package 23 to stably emit light at the first light-emitting amount LA1, compared to when current supply to the LED package 23 is started at the first current value CV1. The first temperature threshold Tth1 is lower than the temperature T1, and is a temperature at which it can be determined that the temperature of the LED package 23 is stable at a temperature lower than the temperature T1 (the temperature change over a predetermined period (e.g., 10 seconds) is within a predetermined range (e.g., ±0.1°C)), for example, because no current is supplied to the LED package 23 for a predetermined period (e.g., 1 hour).

[0041] Furthermore, when the temperature of the light-emitting unit 231 of the LED package 23 is lower than the second temperature threshold Tth2 (e.g., 15°C) and no current is being supplied, the control unit CTR starts supplying current to the LED package 23 at a fourth current value CV4 lower than the third current value CV3 and increases the current value of the current supplied to the LED package 23 to the third current value CV3. This reduces the time required for the light-emitting unit 231 of the LED package 23 to stably emit light at the second light-emitting amount LA2, compared to when current supply to the LED package 23 is started at the third current value CV3. The second temperature threshold Tth2 is lower than the temperature T3 and is a temperature at which it can be determined that the temperature of the LED package 23 has stabilized at a temperature lower than the temperature T3 (that is, the temperature change over a predetermined period (e.g., 10 seconds) is within a predetermined range (e.g., ±0.1°C)) after a predetermined period (e.g., one hour) has passed since no current was supplied to the LED package 23. The second temperature threshold Tth2 may be the same as or different from the first temperature threshold Tth1, provided that the second temperature threshold Tth2 is lower than the temperature T3.

[0042] Furthermore, when the light-emitting unit 231 of the LED package 23, which is supplied with a current of the first current value CV1 and emits light at a first light-emitting amount LA1, is changed to a state in which the light-emitting unit 231 emits light at a second light-emitting amount LA2 that is lower than the first light-emitting amount LA1, the control unit CTR reduces the value of the current supplied to the LED package 23 over time from the first current value CV1 to a third current value CV3 (< the first current value CV1). This reduces the time required for the light-emitting unit 231 of the LED package 23 to stably emit light at the second light-emitting amount LA2, compared to when the value of the current supplied to the LED package 23 is immediately changed from the first current value CV1 to the third current value CV3.

[0043] In this embodiment, the phrase "the light-emitting portion 231 of the LED package 23 stably emits light at the first light-emitting amount LA1" means that the ratio (referred to as the light-emitting amount deviation rate) of the difference ΔLAt (=LAt-LA1) between the light-emitting amount LAt at a certain time t after the start of current supply to the LED package 23 and the first light-emitting amount LA1, i.e., ΔLAt / LA1×100[%], is within a range of ±1%. In addition, in this embodiment, the phrase "the light-emitting portion 231 of the LED package 23 stably emits light at the second light-emitting amount LA2" means that the ratio (referred to as the light-emitting amount deviation rate) of the difference ΔLAt (=LAt-LA2) between the light-emitting amount LAt at a certain time t after the start of current supply to the LED package 23 and the second light-emitting amount LA2, i.e., ΔLAt / LA2×100[%], is within a range of ±1%. This is because, when the deviation rate of the light emission amount is within the range of ±1%, the difference in the light emission amount of the light emitting portion 231 of the LED package 23 does not affect the exposure.

[0044] Next, a detailed description will be given of the control of the current value of the current supplied to the LED package 23, which is executed by the control unit CTR. The control unit CTR controls the current value of the current supplied to the LED package 23 based on a two-stage map created in advance, which indicates the relationship between the time elapsed since the start of supplying current to the LED package 23 and the current value of the current supplied to the LED package 23. The two-stage map is created as follows.

[0045] Here, as an example, we will explain how to create a two-stage map used when the light-emitting section 231 of the LED package 23, whose temperature is lower than the first temperature threshold Tth1 and no current is being supplied, is put into a state where it emits light at the first light emission amount LA1.

[0046] First, when the temperature is lower than the first temperature threshold Tth1 and no current is being supplied to the light-emitting unit 231 of the LED package 23, the light-emitting unit 231 is put into a state where the light-emitting unit 231 emits light at the first light-emitting amount LA1. The supply of current to the LED package 23 is started at the first current value CV1, and a change in the light-emitting amount deviation rate is obtained when the current at the first current value CV1 is continuously supplied to the LED package 23. The change in the light-emitting amount deviation rate may be obtained, for example, by actually measuring the light-emitting amount of the light-emitting unit 231 of the LED package 23, or by simulation.

[0047] Next, based on the change in the deviation rate of the light emission amount, a one-stage map is created that shows the relationship between the elapsed time from the start of supplying current to the LED package 23 and the current value of the current supplied to the LED package 23 .

[0048] Creation of the one-stage map will be described in more detail. Fig. 5 is a graph showing measurement results of the light emission amount of the light-emitting unit 231 of the LED package 23 when current is supplied to the LED package 23 at a first current value CV1 from the start of current supply as shown in Fig. 6, in order to set the light-emitting unit 231 of the LED package 23 to a state in which the temperature is lower than the first temperature threshold Tth1 and no current is being supplied, so that the light-emitting unit 231 emits light at a first light-emitting amount LA1. In Fig. 5, the vertical axis represents the light emission amount deviation rate, and the horizontal axis represents the elapsed time from the start of current supply.

[0049] 6 is a graph showing the output versus time. The output [%] is the ratio of the current value CVt of the current supplied to the LED package 23 at a certain time t to the first current value CV1 (output [%] = CVt / CV1 × 100). As shown in FIG. 6, the output is constant at 100% from the start of current supply.

[0050] 5 , when current supply to the LED package 23 starts at the first current value CV1, the light-emitting unit 231 of the LED package 23 emits light at an amount of light that is higher than the first light emission amount LA1, and the amount of light emission decreases over time. This is because the amount of light emission of the light-emitting unit 231 included in the LED package 23 decreases as the temperature of the LED package 23 increases. More specifically, when current supply to the LED package 23 starts, the temperature of the LED package 23 is low, so the amount of light emission of the light-emitting unit 231 of the LED package 23 is high. Thereafter, the amount of light emission decreases as the temperature of the LED package 23 increases.

[0051] After that, when about 80 seconds have passed since the start of the current supply, the deviation rate of the light emission amount falls within the range of ±1%, and the light emission amount of the light emitting portion 231 of the LED package 23 becomes stable.

[0052] The one-step map is determined based on the light emission deviation rate shown in FIG. 5 . For example, if the light emission deviation rate 100 ms after the start of current supply to the LED package 23 is approximately +11.2%, the output 100 ms after the start of current supply to the LED package 23 is set to 88.8% (100% × 0.888) in the one-step map. Furthermore, if the light emission deviation rate 50 seconds after the start of current supply is approximately +1.2%, the output 50 seconds after the start of current supply is set to 98.8% (100% × 0.988) in the one-step map. In this manner, the output at each time point after the start of current supply is determined from the light emission deviation rate, thereby obtaining the one-step map shown in FIG. 7 , for example. As shown in FIG. 7 , the one-step map predetermines the output at each time point after the start of current supply.

[0053] The output at the start of current supply (0 [s]) can be calculated using various interpolation methods. As shown in FIG. 7 , the output at the start of current supply (0 [s]) is less than 100%, so the current value at the start of current supply to the LED package 23 is lower than the first current value CV1. In the following description, when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the first temperature threshold Tth1 and no current is being supplied, is set to emit light at the first light-emitting amount LA1, a one-step map created based on the change in the light-emission amount deviation rate when current is supplied to the LED package 23 at the first current value CV1 from the start of current supply, as shown in FIG. 6 , is referred to as the “first one-step map.” The current value at the start of current supply (0 [s]) in the first one-step map is referred to as the “first start current value CVst1.”

[0054] 5 , when the light emission deviation rate changes, a one-step map may be created by calculating the slope of the light emission deviation rate between elapsed times t1 and t2 from the light emission deviation rate at elapsed time t1 and the light emission deviation rate at elapsed time t2, and determining the rate of increase (amount of increase) of output between elapsed times t1 and t2 based on the slope. Alternatively, a one-step map may be created that increases output at a constant rate based on a value obtained by dividing the amount of change in the light emission deviation rate by the time from the start of current supply until the light emission deviation rate falls within the ±1% range (the average slope of the light emission deviation rate). That is, the rate at which the current value supplied to the LED package 23 is increased from the first start current value CVst1 to the first current value CV1 may vary or be constant depending on the time from the start of current supply.

[0055] The first one-stage map created in this manner is used to create a two-stage map. Creation of the two-stage map will be described in detail with reference to a specific example. First, when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the first temperature threshold Tth1 and no current is being supplied, is set to a state in which it emits light at the first light-emitting amount LA1, the current value supplied to the LED package 23 is controlled based on the first one-stage map shown in FIG. 7 , for example, to obtain a change in the light-emitting amount deviation rate. The change in the light-emitting amount deviation rate may be obtained, for example, by actually measuring the light-emitting amount of the light-emitting unit 231 of the LED package 23, or by simulation.

[0056] Next, based on the change in the deviation rate of the light emission amount, a two-stage map is created that shows the relationship between the time elapsed since the supply of current to the LED package 23 started and the current value of the current supplied to the LED package 23 .

[0057] 8A is a graph showing measurement results of the light emission amount of the light-emitting unit 231 of the LED package 23 when the current value supplied to the LED package 23 is controlled according to the first one-step map shown in FIG. 7 when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the first temperature threshold Tth1 and no current is being supplied, is set to a state in which it emits light at a first light emission amount LA1. In FIG. 8A, the vertical axis represents the light emission amount deviation rate, and the horizontal axis represents the elapsed time from the start of current supply. FIG. 8B is a graph in which the range of the light emission amount deviation rate on the vertical axis in FIG. 8A is enlarged to cover the range from 0% to 2%.

[0058] 8A and 8B show that the time until the light-emitting unit 231 of the LED package 23 stably emits light at the first light emission amount LA1 is shortened by starting the supply of current to the LED package 23 at a first start current value CVst1 that is lower than the first current value CV1 and increasing the current value of the current supplied to the LED package 23 over time in accordance with the first single-stage map of FIG. 7 . However, there are cases where it is desired to further shorten the time from when the supply of current to the LED package 23 is started until the light emission amount deviation rate becomes sufficiently small. Therefore, a two-stage map is created based on the light emission amount deviation rates shown in FIGS. 8A and 8B.

[0059] For example, if the output 100 ms after the start of current supply to the LED package 23 in the first one-stage map is 88.8% and the light emission amount deviation rate 100 ms after the start of current supply to the LED package 23 in the graph of light emission amount deviation rate shown in Figure 8(B) is +1%, the output 100 ms after the start of current supply in the two-stage map is set to 87.9% (88.8[%] x 0.99). Also, if the output 200 ms after the start of current supply to the LED package 23 in the first one-stage map is 91% and the light emission amount deviation rate 200 ms after the start of current supply to the LED package 23 in the graph of light emission amount deviation rate shown in Figure 8(B) is +0.5%, the output 200 ms after the start of current supply in the two-stage map is set to 90.5% (91[%] x 0.995). In this way, the two-stage map is created based on the change in the light emission amount deviation rate when the current value supplied to the LED package 23 is controlled in accordance with the first one-stage map. In other words, the two-stage map determines in advance the output at each time point after the start of current supply.

[0060] The output at the start of current supply (0 [s]) can be calculated using various interpolation methods. As with the first one-step map, the output at the start of current supply (0 [s]) in the two-step map is also less than 100%. Therefore, the current value at the start of current supply to the LED package 23 is lower than the first current value CV1. In the following description, a two-step map created based on the change in the light emission amount deviation rate when the current value supplied to the LED package 23 is controlled according to the first one-step map when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the first temperature threshold Tth1 and no current is being supplied, is set to emit light at the first light emission amount LA1 is referred to as the first two-step map. The current value at the start of current supply (0 [s]) in the first two-step map is referred to as the second start current value CVst2.

[0061] 8A and 8B , when the light emission deviation rate changes, the slope of the light emission deviation rate between elapsed times t1 and t2 may be calculated from the light emission deviation rate at elapsed time t1 and the light emission deviation rate at elapsed time t2. The slope may be used to determine the rate of increase (amount of increase) of output power between elapsed times t1 and t2. Alternatively, the first two-stage map may be created by dividing the change in the light emission deviation rate by the time from the start of current supply until the light emission deviation rate falls within the ±1% range (the average slope of the light emission deviation rate). That is, the rate at which the current value supplied to the LED package 23 is increased from the second start current value CVst2 to the first current value CV1 may vary or be constant depending on the time from the start of current supply.

[0062] 9 is a graph showing the measurement results of the light emission amount of the light-emitting unit 231 of the LED package 23 when the value of the current supplied to the LED package 23 is controlled according to the first two-stage map in order to make the light-emitting unit 231 of the LED package 23 emit light at the first light emission amount LA1 when the temperature is lower than the first temperature threshold Tth1 and no current is being supplied. In FIG. 9, the vertical axis represents the light emission amount deviation rate, and the horizontal axis represents the elapsed time from the start of current supply.

[0063] 9, the deviation rate of the light emission amount when the current value of the current supplied to the LED package 23 is controlled according to the first two-step map is within a range of ±0.5% from the start of current supply. In other words, the deviation rate of the light emission amount is improved compared to when the current value of the current supplied to the LED package 23 is controlled according to the first one-step map (see FIG. 5), and it can be seen that by using the first two-step map, the time until the light emission amount of the light-emitting portion 231 of the LED package 23 becomes stable can be further shortened.

[0064] This is thought to be because the use of the first two-stage map made it possible to supply a current of an appropriate value to the LED package 23 in order to obtain the first light emission amount LA1 at each temperature. Note that even after the current value of the current supplied to the LED package 23 reaches the first current value CV1, the LED package 23 continues to emit light at the first light emission amount LA1.

[0065] Next, we will explain how to create a two-stage map that is used when the light-emitting section 231 of the LED package 23, whose temperature is lower than the second temperature threshold Tth2 and no current is being supplied, is made to emit light at the second light emission amount LA2.

[0066] First, a change in the light emission amount deviation rate is acquired when current supply to the LED package 23 is initiated at the third current value CV3 when the light-emitting unit 231 of the LED package 23 is set to emit light at the second light emission amount LA2 while the temperature is lower than the second temperature threshold Tth2 and no current is being supplied. Next, a one-step map is created based on the acquired change in the light emission amount deviation rate, showing the relationship between the elapsed time since current supply to the LED package 23 was initiated and the current value of the current supplied to the LED package 23. In the following description, the one-step map created based on the change in the light emission amount deviation rate when current supply to the LED package 23 is initiated at the third current value CV3 while the light-emitting unit 231 of the LED package 23 is set to emit light at the second light emission amount LA2 while the temperature is lower than the second temperature threshold Tth2 and no current is being supplied is referred to as the second one-step map. Furthermore, the current value at the start of current supply (0 [s]) in the second one-step map is referred to as the third start current value CVst3.

[0067] Next, when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the second temperature threshold Tth2 and no current is being supplied, is put into a state where it emits light at the second light emission amount LA2, a change in the light emission amount deviation rate is obtained when the value of the current supplied to the LED package 23 is controlled according to the second one-step map. Next, based on the obtained change in the light emission amount deviation rate, a two-step map is created that shows the relationship between the elapsed time since the start of current supply to the LED package 23 and the current value of the current supplied to the LED package 23. In this case, too, in the two-step map, the output at the start of current supply (0 [s]) is lower than 100%, so the current value at the start of current supply to the LED package 23 is lower than the third current value CV3. In the following description, the two-stage map created based on the change in the light emission amount deviation rate when the current value of the current supplied to the LED package 23 is controlled according to the second one-stage map when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the second temperature threshold Tth2 and no current is being supplied, is put into a state where it emits light at the second light emission amount LA2, will be referred to as the second two-stage map. Also, the current value at the start of current supply (0 [s]) in the second two-stage map will be referred to as the fourth start current value CVst4.

[0068] 10 is a graph showing the measurement results of the light emission amount of the light-emitting unit 231 of the LED package 23 when the value of the current supplied to the LED package 23 is controlled according to the second two-stage map created as described above, when the light-emitting unit 231 of the LED package 23 of the light source array 20 is set to a state in which the temperature is lower than the second temperature threshold Tth2 and no current is being supplied, emitting light at the second light emission amount LA2. In FIG. 10, the vertical axis represents the light emission amount deviation rate, and the horizontal axis represents the elapsed time from the start of current supply.

[0069] As shown in Figure 10, even when the light-emitting unit 231 of the LED package 23 of the light source array 20 is in a state where the temperature is lower than the second temperature threshold Tth2 and no current is being supplied, and is set to a state where it emits light at the second light emission amount LA2, the current value of the current supplied to the LED package 23 can be controlled according to the second two-stage map, thereby reducing the light emission amount deviation rate and shortening the time until the light emission amount of the light-emitting unit 231 of the LED package 23 stabilizes.

[0070] Next, we will explain how to create a two-stage map that is used to change the light-emitting section 231 of the LED package 23, which is supplied with a current of a first current value CV1 and emits light at a first light emission amount LA1, to a state in which it emits light at a second light emission amount LA2 that is lower than the first light emission amount LA1.

[0071] First, when the light-emitting unit 231 of the LED package 23 is being supplied with a current of the first current value CV1 and emitting light at the first light-emitting amount LA1, and is being changed to a state where the light-emitting unit 231 is being supplied with a current of the first current value CV1 and emitting light at the second light-emitting amount LA2, a change in the light-emission amount deviation rate is obtained when the current value of the current supplied to the LED package 23 is immediately changed from the first current value CV1 to a third current value CV3. Next, based on the obtained change in the light-emission amount deviation rate, a one-step map is created that shows the relationship between the elapsed time since the supply of current to the LED package 23 began and the current value of the current supplied to the LED package 23. In the following description, the one-step map created based on the change in the light-emission amount deviation rate when the current value of the current supplied to the LED package 23 is immediately changed from the first current value CV1 to the third current value CV3 when the light-emitting unit 231 of the LED package 23 is being supplied with a current of the first current value CV1 and emitting light at the first light-emission amount LA1, and is being changed to a state where the light-emission unit 231 is being supplied with a current of the first current value CV1 and emitting light at the second light-emission amount LA2, is referred to as a third one-step map. Furthermore, the current value at the start of current supply (0 [s]) in the third one-step map is referred to as the fifth start current value CVst5. The start of current supply (0 [s]) in the third one-step map is the timing at which the current value of the current supplied to the LED package 23 is changed from the first current value CV1 to another current value. The temperature of the LED package 23, which is supplied with the first current value CV1 and emitting light at the first light emission amount LA1, is higher than temperature T4. Therefore, unless a current higher than the third current value CV3 is supplied, the light-emitting unit 231 of the LED package 23 cannot emit light at the second light emission amount LA2. Therefore, in the third one-step map, the output at the start of current supply (0 [s]), i.e., the current value (fifth start current value CVst5) when the current value of the current supplied to the LED package 23 is changed from the first current value CV1, is higher than the third current value CV3 and lower than the first current value CV1.

[0072] Next, a change in the light emission amount deviation rate is acquired when the value of the current supplied to the LED package 23 is controlled according to the third one-step map when the light-emitting unit 231 of the LED package 23, which is supplied with a current of the first current value CV1 and emitting light at the first light emission amount LA1, is changed to a state where it emits light at the second light emission amount LA2. Next, a two-step map is created based on the acquired change in the light emission amount deviation rate, which indicates the relationship between the elapsed time since the supply of current to the LED package 23 began and the value of the current supplied to the LED package 23. In the following description, the two-step map created based on the change in the light emission amount deviation rate when the value of the current supplied to the LED package 23 is controlled according to the third one-step map when the light-emitting unit 231 of the LED package 23, which is supplied with a current of the first current value CV1 and emitting light at the first light emission amount LA1, is changed to a state where it emits light at the second light emission amount LA2. Furthermore, the current value at the start of current supply (0 [s]) in the third two-step map is referred to as the sixth start current value CVst6. The start of current supply (0 [s]) in the third two-step map is the timing at which the value of the current supplied to the LED packages 23 is changed from the first current value CV1 to another current value. In the third two-step map, the output at the start of current supply (0 [s]), i.e., the current value (sixth start current value CVst6) when the value of the current supplied to the LED packages 23 is changed from the first current value CV1, is higher than the third current value CV3 and lower than the first current value CV1.

[0073] By controlling the current value of the current supplied to LED package 23 in accordance with the third two-stage map, when the light-emitting unit 231 of LED package 23, which is supplied with a current of the first current value CV1 and is emitting light at the first light amount LA1, is changed to a state in which it emits light at the second light amount LA2, the time until the light-emitting unit 231 stably emits light at the second light amount LA2 can be shortened compared to when the current value of the current supplied to LED package 23 is immediately changed from the first current value CV1 to the third current value CV3 or when control is performed in accordance with the third one-stage map.

[0074] 2, the configuration of the illumination optical system 80 will be described. The illumination optical system 80 includes an imaging optical system 81, a fly-eye lens FEL, an aperture stop 85, a condenser optical system 86, and an illumination compensation filter 87.

[0075] The imaging optical system 81 is a double-telecentric optical system that projects an image of the light source unit OPU (light source array 20) onto the incident end of the fly-eye lens FEL at an equal magnification.

[0076] The fly-eye lens FEL is formed by closely arranging a large number of lens elements, each having a positive refractive power, in a row and column so that their optical axes are parallel to the reference optical axis AX. Each lens element constituting the fly-eye lens FEL has a rectangular cross section similar to the shape of the illumination field to be formed on the mask MSK (and consequently the shape of the exposure area to be formed on the plate P).

[0077] 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 and the light source array 20 are optically conjugate.

[0078] The aperture stop 85 is positioned at a position nearly optically conjugate with the entrance pupil plane of the projection optical system PL and has a variable opening for defining the range contributing to illumination from the secondary light source. The aperture stop 85 changes the aperture diameter of the variable opening to set the σ value (the ratio of the aperture diameter of the secondary light source image on the pupil plane of the projection optical system to the aperture diameter of the pupil plane) that determines the illumination conditions to a desired value. The light from the secondary light source that passes through the aperture stop 85 is condensed by a condenser optical system 86, and then its illuminance is corrected by an illuminance correction filter 87, and the light illuminates a mask MSK on which a predetermined pattern is formed in a superimposed manner.

[0079] The wavelength of the light emitted by the light source unit OPU is not limited to that described above, and the light source unit OPU may be configured by appropriately combining LED packages that emit light having a peak wavelength in the range of 360 to 440 nm.

[0080] (Variations) In the first embodiment described above, cases have been described in which the current value of the current supplied to the LED package 23 is controlled in accordance with the first two-stage map, the second two-stage map, and the third two-stage map, respectively, in the following cases: when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the first temperature threshold value Tth1 and no current is being supplied, is made to emit light at the first light-emitting amount LA1 (first case); when the light-emitting unit 231 of the LED package 23, whose temperature is lower than the second temperature threshold value Tth2 and no current is being supplied, is made to emit light at the second light-emitting amount LA2 (second case); and when the light-emitting unit 231 of the LED package 23, which is supplied with a current of the first current value CV1 and emits light at the first light-emitting amount LA1, is made to emit light at the second light-emitting amount LA2 (third case). However, the present invention is not limited to these cases. For example, in the following four cases (cases 4 to 7), the current value of the current supplied to the LED package 23 may be controlled according to the first two-stage map, the second two-stage map, or the third two-stage map.

[0081] (Fourth Case) In the fourth case, the light-emitting unit 231 of the LED package 23 emits light at the first light emission amount LA1, and then the supply of current to the LED package 23 is stopped for a predetermined time (e.g., 80 seconds), after which the light-emitting unit 231 of the LED package 23 emits light at the first light emission amount LA1. In the fourth case, the control unit CTR can control the current value of the current supplied to the LED package 23 in accordance with the first two-stage map.

[0082] (Fifth Case) In the fifth case, the light-emitting unit 231 of the LED package 23 emits light at the second light emission amount LA2, and then the supply of current to the LED package 23 is stopped for a predetermined time (e.g., 80 seconds), after which the light-emitting unit 231 of the LED package 23 emits light at the first light emission amount LA1. In the fifth case, the control unit CTR can control the current value of the current supplied to the LED package 23 in accordance with the first two-stage map.

[0083] (Sixth Case) In the sixth case, the supply of current to the LED package 23 is stopped for a predetermined time (e.g., 80 seconds) from a state in which the light-emitting unit 231 of the LED package 23 is emitting light at the second light-emitting amount LA2, and then the light-emitting unit 231 of the LED package 23 is brought into a state in which it is emitting light at the second light-emitting amount LA2. In the sixth case, the control unit CTR can control the current value of the current supplied to the LED package 23 in accordance with the second two-stage map.

[0084] (Seventh Case) In the seventh case, the light-emitting unit 231 of the LED package 23 emits light at a first light emission amount LA1, and then the supply of current to the LED package 23 is stopped for a predetermined time (e.g., 80 seconds), after which the light-emitting unit 231 of the LED package 23 emits light at a second light emission amount LA2. In the seventh case, the control unit CTR can control the current value of the current supplied to the LED package 23 in accordance with the second two-stage map.

[0085] The first to seventh cases are summarized in Table 1.

[0086] For the fourth to seventh cases, the amount of light emitted by the light-emitting portion 231 of the LED package 23 was measured when the current value of the current supplied to the LED package 23 was controlled according to the two-stage map. In the fourth and fifth cases, the first two-stage map was used, in the sixth case the second two-stage map was used, and in the seventh case the second two-stage map was used to control the current value of the current supplied to the LED package 23.

[0087] 11(A) and 11(B) are graphs showing the measurement results of the light emission amount of the light-emitting portion 231 of the LED package 23 in the fourth and fifth cases, respectively. Fig. 12(A) and 12(B) are graphs showing the measurement results of the light-emitting portion 231 of the LED package 23 in the sixth and seventh cases, respectively.

[0088] As shown in Figures 11(A) to 12(B), even when the supply of current to the LED package 23 is stopped for a predetermined period of time after the light-emitting portion 231 of the LED package 23 is made to emit light, and then the light-emitting portion 231 of the LED package 23 is made to emit light again, it can be seen that by using the two-stage map, the amount of light emitted by the light-emitting portion 231 of the LED package 23 can be stabilized in a relatively short period of time.

[0089] Second Embodiment As shown in FIGS. 11A to 12B , in the fourth to seventh cases, the light emission amount deviation rate is larger than in the first and second cases (see FIGS. 9 and 10 ), and the time until the light emission amount of the light-emitting unit 231 of the LED package 23 stabilizes is longer. This is thought to be because in the fourth and fifth cases, the temperature of the LED package 23 is equal to or higher than the first temperature threshold Tth1 and lower than the temperature T1 when the supply of current to the LED package 23 is resumed. The first two-stage map is created for the case where the temperature of the LED package 23 is lower than the first temperature threshold Tth1 when the current supply is started. Therefore, when the temperature of the LED package 23 is equal to or higher than the first temperature threshold Tth1, it is thought that unless a current value higher than the current value based on the first two-stage map is supplied, it is not possible to obtain the same light emission amount as that of the light-emitting unit 231 of the LED package 23 when the temperature of the LED package 23 is lower than the first temperature threshold Tth1 when the current supply is started.

[0090] Furthermore, in the sixth case, it is considered that the temperature of the LED package 23 when the supply of current to the LED package 23 is resumed is equal to or higher than the second temperature threshold value Tth2 and lower than the temperature T3. Therefore, unless a current value higher than the current value based on the second two-stage map created for the case where the temperature of the LED package 23 when the supply of current is started is lower than the second temperature threshold value Tth2 is supplied, it is considered that an amount of light emission equivalent to the amount of light emission of the light-emitting unit 231 of the LED package 23 when the temperature of the LED package 23 when the supply of current is started is lower than the second temperature threshold value Tth2 cannot be obtained.

[0091] Furthermore, in the seventh case, it is considered that the temperature of the LED package 23 when the supply of current to the LED package 23 is resumed is equal to or higher than the second temperature threshold value Tth2 and higher than the temperature T4. Therefore, unless a current value higher than the current value based on the second two-stage map created for the case where the temperature of the LED package 23 when the supply of current is started is lower than the second temperature threshold value Tth2 is supplied, it is considered that an amount of light emission equivalent to the amount of light emission of the light-emitting unit 231 of the LED package 23 when the temperature of the LED package 23 when the supply of current is started is lower than the second temperature threshold value Tth2 cannot be obtained.

[0092] Therefore, in the second embodiment, the first to third two-stage maps are corrected based on the temperature of the LED package 23 to control the current value of the current supplied to the LED package 23 .

[0093] 13 is a plan view showing a light source array 20X included in a light source unit OPU-A according to the second embodiment. The light source unit OPU-A includes the light source array 20X, a magnifying optical system 30 (not shown in FIG. 13), and a control unit CTR-A.

[0094] The light source array 20X includes a plurality of LED packages 23 arranged in an array on a substrate 21 and a thermistor 25. The thermistor 25 is disposed on the surface of the substrate 21, for example, near the LED packages 23, and detects the surface temperature of the substrate 21. That is, in this embodiment, the surface temperature of the substrate 21 near the LED packages 23 is used as the temperature of the LED packages 23. Note that, for example, a thermistor may be attached to the LED packages 23 to measure the temperature of the LED packages 23 themselves. In this case, the thermistor may be attached in a position that does not interfere with the propagation of light emitted from the LED packages 23. Furthermore, for example, a thermistor may be disposed in a portion of the substrate 21 surrounded by the plurality of LED packages 23, and the temperature of that portion may be used as the temperature of the LED packages 23. Since the other configurations are the same as those of the light source array 20 according to the first embodiment, detailed description thereof will be omitted.

[0095] The control unit CTR-A controls the current value (second current value CV2 or fourth current value CV4) at which current supply to the LED package 23 is started and the rate at which the current value of the current supplied to the LED package 23 is increased to the first current value CV1 or the third current value CV3, according to the temperature of the LED package 23. The control unit CTR-A also controls the current value at which current supply to the LED package 23 is started and the rate at which the current value of the current supplied to the LED package 23 is decreased to the third current value CV3, according to the temperature of the LED package 23. The control performed by the control unit CTR-A will be described in more detail.

[0096] As an example, a fourth case will be described in which, from a state in which the light-emitting unit 231 of the LED package 23 is emitting light at the first light-emitting amount LA1, the supply of current to the LED package 23 is stopped for a predetermined time (e.g., 80 seconds), and then the light-emitting unit 231 of the LED package 23 is returned to a state in which it emits light at the first light-emitting amount LA1. In this case, the temperature of the LED package 23 when the supply of current to the LED package 23 is resumed is equal to or higher than the first temperature threshold value Tth1 and lower than the temperature T1.

[0097] The control unit CTR-A calculates the current value CVact(t) of the current supplied to the LED package 23 at a certain time t after the start of the current supply to the LED package 23, based on the following formula (1): CVact(t)=CVmap(t)×{1.0+(Tact(t)−Tmap(t))×(temperature characteristic / 100)} (1)

[0098] Here, CVmap(t) represents the current value at a certain time t from the start of current supply in the first two-stage map, and Tact(t) represents the actual temperature of the LED package 23 measured by the thermistor 25 at a certain time t from the start of current supply.

[0099] Tmap(t) represents the temperature of the LED package 23 at a certain time t from the start of current supply in a temperature map created in advance. The temperature map is a map showing the relationship between the time elapsed from the start of current supply and the temperature of the LED package 23 when current is supplied to the LED package 23 in accordance with the first two-stage map, with the LED package 23 in a state where its temperature is lower than the first temperature threshold Tth1 and no current is being supplied, and the LED package 23 is brought into a state where it emits light at the first light emission amount LA1. The temperature map may be created by actually measuring the temperature of the LED package 23, or may be created by simulation.

[0100] The temperature characteristic is a characteristic that indicates the relationship between the temperature of the LED package 23 and the amount of light emitted by the light-emitting section 231 of the LED package 23, and indicates the rate of change (%) in the amount of light emitted when the temperature of the LED package 23 that is supplied with a predetermined current value changes by 1° C. The temperature characteristic may take a different value depending on the actual temperature of the LED package 23, or may be constant regardless of the temperature of the LED package 23.

[0101] As can be seen from equation (1), when the actual temperature Tact(t) of the LED package 23 and Tmap(t) of the temperature map are the same at time t, the control unit CTR-A supplies the current value of the two-stage map to the LED package 23. In other words, when the actual temperature Tact(t) of the LED package 23 and Tmap(t) of the temperature map are the same at time t, the current value supplied to the LED package 23 is not changed from the current value of the two-stage map.

[0102] Next, a method for determining the current value of the current supplied to the LED package 23 based on the temperature map and the two-stage map, which is executed by the control unit CTR-A, will be described. Fig. 14(A) is an example of the temperature map, and Fig. 14(B) is an example of the first two-stage map. Note that in Fig. 14(B), the vertical axis represents the current value for ease of understanding, but the vertical axis may also represent the output.

[0103] Here, a case will be described in which the current value of the current to be supplied to the LED package 23 is determined at a certain time t11 after the supply of current to the LED package 23 is resumed (started).

[0104] As shown in FIG. 14A, the temperature of the LED package 23 at time t11 obtained from the temperature map is Tt11. Also, as shown in FIG. 14B, the current value at time t11 obtained from the first two-stage map is CVt11. Assume also that the temperature characteristic is, for example, 2%. In this case, from equation (1), the current value CVact(t11) of the current supplied to the LED package 23 at time t11 is given by: CVact(t11)=CVt11×{1.0+(Tact(t11)-Tt11)×(2 / 100)}. Here, Tact(t11) is the actual temperature of the LED package 23 measured by the thermistor 25 at time t11.

[0105] Fig. 15(A) is a graph showing the actual temperature of the LED package 23 versus the elapsed time since the supply of current was resumed (started), and Fig. 15(B) is a graph showing the current value of the current actually supplied to the LED package 23, which is obtained by correcting the first two-stage map according to the actual temperature of the LED package 23. In Fig. 15(A), the actual temperature of the LED package 23 is shown by a solid line, and the temperature map is shown by a dashed line. In Fig. 15(B), the current value of the current actually supplied to the LED package 23 is shown by a solid line, and the first two-stage map is shown by a dashed line.

[0106] As shown in FIG. 15A , the actual temperature of the LED package 23 is higher than the temperature in the temperature map at the start of current supply to the LED package 23. Therefore, as shown in Equation (1), the control unit CTR-A corrects the current value obtained from the first two-step map based on the actual temperature of the LED package 23 using Equation (1). For example, the control unit CTR-A calculates the second current value CV2 when current supply to the LED package 23 is resumed by correcting the second start current value CVst2 based on the temperature of the LED package 23 when current supply to the LED package 23 is started. As a result, as shown in FIG. 15B , the second current value CV2 when current supply to the LED package 23 is resumed becomes a corrected second start current value CVst2′ that is higher than the second start current value CVst2 of the first two-step map.

[0107] Furthermore, the current supply to the LED package 23 is resumed at the corrected second start current value CVst2′, and the current value of the current supplied to the LED package 23 at each time point during the period until the current value reaches the first current value CV1 is a corrected current value obtained by correcting a current value predetermined for each time point in the first two-step map based on the temperature of the LED package 23 at each time point. As a result, for example, as shown in FIG. 15(B), the control unit CTR-A supplies current to the LED package 23 at a current value greater than the current value in the first two-step map until the current value reaches the first current value CV1.

[0108] As described above, in the second embodiment, the control unit CTR-A controls the current value at the start of current supply to the LED package 23 and the current value of the current supplied to the LED package 23 at each time point after the supply of current to the LED package 23 is resumed (started) in accordance with the temperature of the LED package 23. This allows current to be supplied to the LED package 23 at a more appropriate current value in accordance with the actual temperature of the LED package 23, thereby shortening the time until the light emission amount of the light-emitting unit 231 of the LED package 23 stabilizes.

[0109] In the fifth case, that is, when the supply of current to the LED package 23 is stopped for a predetermined time from a state in which the light-emitting unit 231 of the LED package 23 is emitting light at the second light emission amount LA2, and then the light-emitting unit 231 of the LED package 23 is changed to a state in which it is emitting light at the first light emission amount LA1, the control unit CTR-A supplies to the LED package 23 a current value obtained by correcting the first two-stage map in accordance with the actual temperature of the LED package 23.

[0110] In addition, in the sixth case, that is, when the supply of current to the LED package 23 is stopped for a predetermined time from a state in which the light-emitting unit 231 of the LED package 23 is emitting light at the second light emission amount LA2, and then the control unit CTR-A changes the state in which the light-emitting unit 231 of the LED package 23 is emitting light at the second light emission amount LA2, the control unit CTR-A supplies to the LED package 23 a current value obtained by correcting the second two-stage map in accordance with the actual temperature of the LED package 23.

[0111] The temperature map used in the sixth case is a map showing the relationship between the time elapsed from the start of current supply and the temperature of the LED package 23 when current is supplied to the LED package 23 in accordance with the second two-stage map, with the temperature of the LED package 23 being lower than the second temperature threshold Tth2 and no current being supplied, and the LED package 23 is brought into a state in which it emits light at the second light emission amount LA2.

[0112] In addition, in the seventh case, that is, when the supply of current to the LED package 23 is stopped for a predetermined time from a state in which the light-emitting unit 231 of the LED package 23 is emitting light at a first light emission amount LA1, and then the light-emitting unit 231 of the LED package 23 is changed to a state in which it is emitting light at a second light emission amount LA2, the control unit CTR-A supplies to the LED package 23 a current value obtained by correcting the second two-stage map in accordance with the actual temperature of the LED package 23.

[0113] The temperature map used in the seventh case is a map showing the relationship between the time elapsed from the start of current supply and the temperature of the LED package 23 when current is supplied to the LED package 23 in accordance with the second two-stage map, with the temperature of the LED package 23 being lower than the second temperature threshold Tth2 and no current being supplied, and the LED package 23 is brought into a state where it emits light at the second light emission amount LA2.

[0114] In the seventh case, the control unit CTR-A may determine whether to use the second two-stage map or the third two-stage map to control the current value of the current supplied to the LED package 23, depending on the temperature of the LED package 23 when the supply of current to the LED package 23 is started after the supply of current to the LED package 23 has been stopped for a predetermined period of time.

[0115] 16(A) and 16(B) are graphs showing the measurement results of the amount of light emitted by the LED package 23 when the first two-stage map is corrected in accordance with the actual temperature of the LED package 23 to control the current value supplied to the LED package 23 in the fourth and fifth cases, respectively. FIG. 17(A) is a graph showing the measurement results of the amount of light emitted by the LED package 23 when the second two-stage map is corrected in accordance with the actual temperature of the LED package 23 to control the current value supplied to the LED package 23 in the sixth case. FIG. 17(B) is a graph showing the measurement results of the amount of light emitted by the LED package 23 when the second two-stage map is corrected in accordance with the actual temperature of the LED package 23 to control the current value supplied to the LED package 23 in the seventh case. In FIGS. 16(A) to 17(B), the vertical axis represents the light emission amount deviation rate, and the horizontal axis represents the elapsed time from the start of current supply.

[0116] 11(A) to 12(B), it can be seen that in the second embodiment, the light emission amount deviation rate is smaller and the time until the light emitting unit 231 of the LED package 23 emits light at the desired light emission amount is shorter than in the modified example of the first embodiment. In this way, by correcting the two-stage map in accordance with the actual temperature of the LED package 23 and controlling the current value of the current supplied to the LED package 23, it is possible to further shorten the time until the light emitting unit 231 of the LED package 23 stably emits light at the desired light emission amount.

[0117] As described above in detail, according to the second embodiment, when the control unit CTR-A supplies a current of the first current value CV1 when the temperature of the LED package 23 is within the range of temperature T1 to temperature T2 (>T1) (first temperature range), the control unit CTR-A starts supplying a current to the LED package 23, which emits light at the first light emission amount LA1, at a second current value CV2 lower than the first current value CV1, and increases the current value of the current supplied to the LED package 23 from the second current value CV2 to the first current value CV1. The control unit CTR-A controls the second current value CV2 and the rate at which the current value of the current supplied to the LED package 23 is increased from the second current value CV2 to the first current value CV1, depending on the temperature of the LED package 23. Specifically, the control unit CTR-A sets the second current value CV2 when starting to supply current to the LED package 23 to a current value obtained by correcting the second start current value CVst2 in the first two-step map based on the temperature of the LED package 23. Furthermore, the control unit CTR-A increases the rate at which the current value of the current supplied to the LED package 23 is increased to the first current value CV1 at a rate obtained by correcting the first two-step map based on the temperature of the LED package 23. In other words, at each time point during the period in which the current value of the current supplied to the LED package 23 is increased to the first current value CV1, the control unit CTR-A supplies to the LED package 23 a current of a corrected current value obtained by correcting a current value predetermined for each time point in the first two-step map based on the temperature of the LED package 23.

[0118] Furthermore, when the control unit CTR-A supplies a current of the third current value CV3 when the temperature of the LED package 23 is within a range from temperature T3 to temperature T4 (>T3) (second temperature range), the control unit CTR-A starts supplying current to the LED package 23, which emits light at the second light emission amount LA2, at a fourth current value CV4 that is lower than the third current value CV3, and increases the current value of the current supplied to the LED package 23 from the fourth current value CV4 to the third current value CV3. The control unit CTR-A controls the fourth current value CV4 and the rate at which the current value of the current supplied to the LED package 23 is increased from the fourth current value CV4 to the third current value CV3, depending on the temperature of the LED package 23. Specifically, the control unit CTR-A sets the fourth current value CV4 when starting to supply current to the LED package 23 to a current value obtained by correcting the fourth start current value CVst4 in the second two-step map based on the temperature of the LED package 23. Furthermore, the control unit CTR-A increases the rate at which the current value of the current supplied to the LED package 23 is increased to the third current value CV3 at a rate obtained by correcting the second two-step map based on the temperature of the LED package 23. That is, at each point in time during which the current value of the current supplied to the LED package 23 is increased to the third current value CV3, the control unit CTR-A supplies to the LED package 23 a current of a corrected current value obtained by correcting a current value predetermined for each point in time in the second two-step map based on the temperature of the LED package 23. This makes it possible to shorten the time until the light emission amount of the light-emitting unit 231 of the LED package 23 stabilizes.

[0119] Furthermore, in the second embodiment, when a current of a third current value CV3 lower than the first current value CV1 is supplied to the LED package 23 while the temperature of the LED package 23 is within the range from temperature T3 to temperature T4 (second temperature range), the LED package 23 emits light at a second light emission amount LA2 lower than the first light emission amount LA1. The control unit CTR-A starts supplying current at a current value higher than the third current value CV3 to the LED package 23 at a temperature higher than temperature T4, and reduces the current value supplied to the LED package 23 to the third current value CV3. The control unit CTR-A controls the current value at which the supply of current to the LED package 23 starts and the rate at which the current value supplied to the LED package 23 is reduced to the third current value CV3, depending on the temperature of the LED package 23. For example, the control unit CTR-A sets the fourth current value CV4 when starting to supply current to the LED package 23 to a current value obtained by correcting the fourth start current value CVst4 in the second two-step map based on the temperature of the LED package 23. Furthermore, at each time point during the period in which the current value of the current supplied to the LED package 23 is reduced to the third current value CV3, the control unit CTR-A supplies to the LED package 23 a current with a corrected current value obtained by correcting a current value predetermined for each time point in the second two-step map based on the temperature of the LED package 23. This makes it possible to shorten the time until the light emission amount of the light-emitting unit 231 of the LED package 23 stabilizes at the second light emission amount LA2, compared to a case in which the second one-step map or the second two-step map is not corrected in accordance with the temperature of the LED package 23.

[0120] In the second embodiment, the actual temperature of the LED package 23 is measured using the thermistor 25, but this is not limiting. The control unit CTR-A may, for example, predict the temperature at a certain point after the start of supplying current to the LED package 23 based on a temperature prediction map, and use the predicted temperature as the actual temperature of the LED package 23. The temperature prediction map can be created, for example, as follows. As an example, a case will be described in which, from a state in which the light-emitting unit 231 of the LED package 23 is emitting light at a first light-emitting amount LA1, the supply of current to the LED package 23 is stopped for a predetermined time (e.g., 80 seconds), and then the light-emitting unit 231 of the LED package 23 is caused to emit light again at the first light-emitting amount LA1. In this case, the temperature of the LED package 23 is measured when the current value of the current supplied to the LED package 23 is controlled based on the first two-stage map, and a temperature prediction map is created based on the measurement results. The temperature prediction map is a graph showing the relationship between the time since the supply of current to the LED package 23 begins and the actual temperature of the LED package 23 when the current value of the current supplied to the LED package 23 is controlled based on the first two-stage map.

[0121] The control unit CTR-A may correct the first two-stage map by using the temperature of the LED package 23 in the temperature prediction map for the time period from when the supply of current to the LED package 23 is started as the actual temperature of the LED package 23. In this case, the temperature of the LED package 23 when the supply of current to the LED package 23 is resumed varies depending on the length of time for which the supply of current to the LED package 23 is stopped. Therefore, a temperature prediction map may be created for each length of time for which the supply of current to the LED package 23 is stopped, or, for example, a function including the length of time for which the supply of current to the LED package 23 is stopped as a parameter may be used as the temperature prediction map for the LED package 23.

[0122] Furthermore, in the second embodiment, a current having a current value obtained by correcting the two-step map based on the actual temperature of the LED package 23 is supplied to the LED package 23. However, this is not limited to this. A current having a current value obtained by correcting the one-step map based on the actual temperature of the LED package 23 may be supplied to the LED package 23. In the fourth and fifth cases, the current value when supplying current to the LED package 23 starts (second current value CV2) is the temperature obtained by correcting the first start current value CVst1 of the first one-step map in accordance with the temperature of the LED package 23. In the sixth case, the current value when supplying current to the LED package 23 starts (fourth current value CV4) is the temperature obtained by correcting the third start current value CVst3 of the second one-step map in accordance with the temperature of the LED package 23. In the seventh case, the current value when supplying current to the LED package 23 starts is the temperature obtained by correcting the third start current value CVst3 of the second one-step map in accordance with the temperature of the LED package 23.

[0123] In addition, instead of correcting the predetermined current value for each time point obtained from the one-stage map or two-stage map according to the temperature of the LED package 23 to calculate the current value to be supplied to the LED package 23 at each time point, the current value at each time point calculated from an equation (approximate equation) indicating the current value to be supplied to the LED package 23 at each time point, which is predetermined in the one-stage map or two-stage map, may be corrected according to the temperature of the LED package 23.

[0124] In addition, the control unit CTR-A may perform machine learning using the actual temperature data of the LED package 23, the light emission amount deviation rate data, and the output data as training data, and determine the output using the obtained trained model.

[0125] Furthermore, in the second embodiment described above, when the supply of current to the LED package 23 is stopped for a predetermined time from a state in which the light-emitting portion 231 of the LED package 23 is emitting light, and then the supply of current to the LED package 23 is resumed, if the temperature of the LED package 23 is equal to or higher than the first temperature threshold Tth1 and lower than temperature T1, or if the temperature of the LED package 23 is equal to or higher than the second temperature threshold Tth2 and lower than temperature T3, the two-stage map is corrected in accordance with the actual temperature of the LED package 23. However, the two-stage map may also be corrected in accordance with the actual temperature of the LED package 23 when the temperature of the LED package 23 is lower than the first temperature threshold Tth1 or when the temperature of the LED package 23 is lower than the second temperature threshold Tth2.

[0126] 18A is a graph showing a measurement result of the amount of light emitted by the light-emitting unit 231 of the LED package 23 when a current having a value obtained by correcting the first two-stage map in accordance with the actual temperature of the LED package 23 is supplied to the LED package 23 in order to cause the light-emitting unit 231 of the LED package 23 to emit light at a first light-emitting amount LA1 when the temperature is lower than the first temperature threshold Tth1 and no current is being supplied to the LED package 23. FIG. 18B is a graph showing a measurement result of the amount of light emitted by the light-emitting unit 231 of the LED package 23 when a current having a value obtained by correcting the second two-stage map in accordance with the actual temperature of the LED package 23 is supplied to the LED package 23 in order to cause the light-emitting unit 231 of the LED package 23 to emit light at a second light-emitting amount LA2 when the temperature is lower than the second temperature threshold Tth2 and no current is being supplied to the LED package 23.

[0127] As shown in Figures 18(A) and 18(B), even when the temperature is lower than the first temperature threshold Tth1 or the second temperature threshold Tth2 and the light-emitting unit 231 of the LED package 23 is in a state where it emits light at a predetermined light intensity when no current is being supplied, the time until the light-emitting unit 231 of the LED package 23 stabilizes can be shortened by supplying to the LED package 23 a current whose value is obtained by correcting the two-stage map according to the actual temperature of the LED package 23.

[0128] Furthermore, in the second embodiment described above, the current value at the start of supplying current to the LED package 23 and the rate at which the current value of the current supplied to the LED package 23 is increased or decreased are controlled in accordance with the temperature of the LED package 23. However, it is only necessary to control at least one of the current value at the start of supplying current to the LED package 23 and the rate at which the current value of the current supplied to the LED package 23 is increased or decreased in accordance with the temperature of the LED package 23.

[0129] Third Embodiment The lighting unit to which the driving methods of the LED package 23 according to the first and second embodiments and their modifications are applied is not limited to the lighting unit 90. Fig. 19 is a schematic diagram showing the configuration of a lighting unit 90A according to a third embodiment.

[0130] The illumination unit 90A includes a first light source unit OPU1, a second light source unit OPU2, and an illumination optical system 80A. The first light source unit OPU1 includes a first light source array 20-1, a first magnifying optical system 30-1, and a first controller CTR-1, while the second light source unit OPU2 includes a second light source array 20-2, a second magnifying optical system 30-2, and a second controller CTR-2.

[0131] The first light source unit OPU1 emits light with a peak wavelength of 385 nm, for example. The second light source unit OPU2 emits light with a peak wavelength of 365 nm, for example. Note that the configurations of the first light source unit OPU1 and the second light source unit OPU2 are the same as those of the light source unit OPU according to the first embodiment or the light source unit OPU-A according to the second embodiment, and therefore detailed description thereof will be omitted.

[0132] The illumination optical system 80A includes a first focusing optical system 83A including a first dichroic mirror DM1, a second focusing optical system 83B, a second dichroic mirror DM2, an imaging optical system 81A, a fly's eye lens FEL, an aperture stop 85, a condenser optical system 86, and an illuminance correction filter 87.

[0133] The first focusing optical system 83A forms a pupil of the magnified image of the light-emitting unit 231 formed by the first magnifying optical system 30-1. That is, the rear focal position of the first focusing optical system 83A is the pupil position. The first focusing optical system 83A 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 83A 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 83A may be appropriately adjusted so that the light beam is incident on the second dichroic mirror DM2. Furthermore, the first focusing optical system 83A may be configured with a single lens or a lens group including multiple lenses.

[0134] The second focusing optical system 83B forms a pupil of the magnified image of the light-emitting unit 231 formed by the second magnifying optical system 30-2. That is, the rear focal position of the second focusing optical system 83B becomes the pupil position. The second focusing optical system 83B may be composed of a single lens or a lens group including multiple lenses.

[0135] 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 83A and the pupil image formed by the second focusing optical system 83B.

[0136] The imaging optical system 81A is a double-telecentric optical system that projects a composite image formed by the second dichroic mirror DM2 onto the entrance end of the fly-eye lens FEL at an equal magnification.

[0137] The other configurations are the same as those of the above embodiment, and therefore detailed description will be omitted. In this way, the light source unit according to any one of the first and second embodiments and the modified examples can be applied to an exposure apparatus having multiple light source units.

[0138] Fourth Embodiment FIG. 20 is a schematic diagram showing the configuration of an exposure apparatus 10B according to a fourth embodiment.

[0139] In the exposure apparatus 10B, the illumination unit 90B includes a first light source unit OPU1, a second light source unit OPU2, and an illumination optical system 80B. The first light source unit OPU1 and the second light source unit OPU2 are the same as those in the third embodiment, and therefore detailed description thereof will be omitted.

[0140] The illumination optical system 80B includes a first focusing optical system 83A1, a second focusing optical system 83B1, a third dichroic mirror DM3, an imaging optical system 81B, a fly-eye lens FEL, an aperture stop 85, a condenser optical system 86B, and an illuminance correction filter 87.

[0141] The first focusing optical system 83A1 is disposed on or near the predetermined plane PP, and forms a pupil of the magnified image of the light-emitting unit 231 formed by the first magnifying optical system 30-1. The first focusing optical system 83A1 may be composed of a single lens, or may be composed of a lens group including a plurality of lenses.

[0142] The second focusing optical system 83B1 is disposed on or near the predetermined plane PP, and forms a pupil of the magnified image of the light-emitting unit 231 formed by the second magnifying optical system 30-2. The second focusing optical system 83B1 may be composed of a single lens, or may be composed of a lens group including a plurality of lenses.

[0143] The third dichroic mirror DM3 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 83A1 and the pupil image formed by the second focusing optical system 83B1.

[0144] The imaging optical system 81B is a double-telecentric optical system that projects the composite image formed by the third dichroic mirror DM3 onto the incident end of the fly-eye lens FEL at an equal magnification. Note that the imaging optical system 81B may also reduce and project the composite image formed by the third dichroic mirror DM3 onto the incident end of the fly-eye lens FEL.

[0145] The light beam incident on the fly-eye lens FEL is wavefront-split by a number of lens elements, and one light source image is formed on or near the rear focal plane of each lens element. The light beam from the secondary light source formed on or near the rear focal plane of the fly-eye lens FEL is incident on an aperture stop 85 located nearby.

[0146] The light from the secondary light source passing through the aperture stop 85 is subjected to the focusing action of the condenser optical system 86B, and then its illuminance is corrected by the illuminance correction filter 87, and the light is superimposed to illuminate a mask MSK on which a predetermined pattern is formed.

[0147] Furthermore, in exposure apparatus 10B, projection optical system PL is an Offner-type optical system that is supported below (on the -Z side of) mask stage MST by optical surface plate 73. Projection optical system PL forms, for example, an arc-shaped image field with its longitudinal direction in the Y-axis direction.

[0148] 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 the illumination area in an irradiation area (exposure area (conjugate to the illumination area)) on the plate P that is arranged on the image plane side of the projection optical system PL. This exposes the plate P, and the pattern of the mask MSK is transferred onto the plate P.

[0149] As shown in the fourth embodiment, the light source unit according to any one of the first and second embodiments and their modifications may be applied to an exposure apparatus equipped with an Offner type projection optical system PL.

[0150] The wavelengths of the light emitted by the first light source unit OPU1 and the second light source unit OPU2 are not limited to those described above, and the first light source unit OPU1 and the second light source unit OPU2 may be constructed by appropriately combining LED packages that emit light having a peak wavelength in the range of 360 to 440 nm.

[0151] 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 365 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 from the first light source unit OPU1 and the second light source unit OPU2 is not limited to these examples. Note that, when the combination of the wavelengths of the light emitted from the first light source unit OPU1 and the second light source unit OPU2 is a combination other than that described in this embodiment, it is preferable to change the material of the dichroic mirror appropriately depending on the wavelengths used.

[0152] In the above embodiment and its modifications, the exposure apparatus has been described as being used to manufacture liquid crystal display devices (flat panel displays), but the exposure apparatus may also be used to manufacture semiconductors by exposing silicon wafers.

[0153] 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.

[0154] 10, 10B Exposure apparatus 20, 20X Light source array 20-1 First light source array 20-2 Second light source array 21 Substrate 23 LED package 25 Thermistor 80, 80A, 80B Illumination optical system 90, 90A, 90B Illumination unit 100 Projection optical unit CTR, CTR-A Control unit CTR-1 First control unit CTR-2 Second control unit DM2 Second dichroic mirror FEL Fly's eye lens MSK Mask OPU Light source unit OPU-A Light source unit OPU1 First light source unit OPU2 Second light source unit PL Projection optical system P Glass substrate

Claims

1. A method for driving a light source element that emits light with a first amount of light when a current of a first current value is supplied thereto, comprising: starting current supply to the light source element at a second current value lower than the first current value, and increasing the current value of the current supplied to the light source element to the first current value, wherein the current value of the current supplied to the light source element at a first time point is a corrected current value obtained by obtaining from predetermined first information the current value of the current supplied to the light source element at the first time point at each time point during a period in which current supply to the light source element is started at a predetermined third current value and the current value of the current supplied to the light source element is increased to the first current value, and the obtained current value is corrected based on the temperature of the light source element.

2. A method for driving a light source element as described in claim 1, comprising: calculating the second current value by correcting the predetermined third current value based on the temperature of the light source element when starting to supply current to the light source element; and calculating a current value of a current to be supplied to the light source element at the first time point by correcting the current value obtained from the first information based on the temperature of the light source element at the first time point.

3. A method for driving a light source element as described in claim 2, wherein the current value of the current supplied to the light source element at the first time point is a corrected current value obtained by correcting the current value obtained from the first information based on a previously acquired relationship between the elapsed time since the start of current supply to the light source element and the temperature of the light source element, and the temperature of the light source element at the first time point.

4. A method for driving a light source element described in any one of claims 1 to 3, wherein the predetermined third current value is a current value at which current supply to the light source element is started, determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the first current value when the temperature of the light source element is lower than the first temperature threshold, and the first information is determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the first current value when the temperature of the light source element is lower than the first temperature threshold.

5. The predetermined third current value is a current value at which current supply to the light source element is started, the current value being determined based on a change in the amount of light emitted by the light source element when the current supply to the light source element is started at a fourth current value lower than the first current value when the temperature of the light source element is lower than a first temperature threshold, and the current value of the current supplied to the light source element is increased to the first current value according to predetermined second information at each time point during a period in which current supply to the light source element is started at the fourth current value and the current value of the current supplied to the light source element is increased to the first current value according to predetermined second information; the first information is determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the fourth current value when the temperature of the light source element is lower than the first temperature threshold, and the current value of the current supplied to the light source element is increased to the first current value according to the second information; and the fourth current value and the second information are determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the first current value when the temperature of the light source element is lower than the first temperature threshold. A method for driving the light source element according to claim 1 .

6. A method for driving a light source element which emits light at a first light emission amount when supplied with a current of a first current value, and emits light at a second light emission amount lower than the first light emission amount when supplied with a current of a fifth current value lower than the first current value, comprising: starting current supply to the light source element at a sixth current value higher than the fifth current value, and decreasing the current value of the current supplied to the light source element from the sixth current value to the fifth current value, wherein the current value of the current supplied to the light source element at a first time point is a corrected current value obtained by obtaining the current value of the current supplied to the light source element at the first time point from predetermined third information at each time point during a period in which current supply to the light source element is started at a predetermined seventh current value and the current value of the current supplied to the light source element is changed to the fifth current value, and the obtained current value is corrected based on the temperature of the light source element.

7. A method for driving a light source element as described in claim 6, comprising: calculating the sixth current value by correcting the predetermined seventh current value based on the temperature of the light source element when starting to supply current to the light source element; and calculating a current value of a current to be supplied to the light source element at the first time point by correcting the current value obtained from the third information based on the temperature of the light source element at the first time point.

8. A method for driving a light source element as described in claim 7, wherein the current value of the current supplied to the light source element at the first point in time is a corrected current value obtained by correcting the current value obtained from the third information based on a previously acquired relationship between the elapsed time since the start of current supply to the light source element and the temperature of the light source element, and the temperature of the light source element at the first point in time.

9. A method for driving a light source element according to any one of claims 6 to 8, wherein the predetermined seventh current value is a current value at which to start supplying current to the light source element, determined based on a change in the amount of light emitted by the light source element when a current value of a current supplied to the light source element is changed from the first current value to the fifth current value when the light source element, which is supplied with a current of the first current value and emitting the first amount of light, is put into a state in which it emits light at the second amount of light; and the third information is determined based on a change in the amount of light emitted by the light source element when a current value of a current supplied to the light source element is changed from the first current value to the fifth current value when the light source element, which is supplied with a current of the first current value and emitting the first amount of light, is put into a state in which it emits light at the second amount of light.

10. The predetermined seventh current value is a current value at which current supply to the light source element is started at an eighth current value higher than the fifth current value, and the current value supplied to the light source element at each point in a period from when current supply to the light source element is started at the eighth current value to when the current value supplied to the light source element is reduced to the fifth current value in accordance with predetermined fourth information, the current value being determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the eighth current value and the current value supplied to the light source element is reduced to the fifth current value in accordance with the fourth information, the third information being determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the eighth current value and the current value supplied to the light source element is reduced to the fifth current value in accordance with the fourth information, 9. The method for driving a light source element according to claim 6, wherein the eighth current value and the fourth information are determined based on a change in the amount of light emitted by the light source element when a current value of the current supplied to the light source element is changed from the first current value to the fifth current value when the light source element, which is supplied with a current of the first current value and emitting the first amount of light, is put into a state in which it emits light at the second amount of light.

11. A method for driving a light source element described in any one of claims 6 to 8, wherein the predetermined seventh current value is a current value at which current supply to the light source element is started, determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the fifth current value when the temperature of the light source element is lower than the second temperature threshold, and the third information is determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the fifth current value when the temperature of the light source element is lower than the second temperature threshold.

12. The predetermined seventh current value is a current value at which current supply to the light source element is started at a ninth current value lower than the fifth current value when the temperature of the light source element is lower than the second temperature threshold, and the current value supplied to the light source element at each time point during which current supply to the light source element is started at the ninth current value and the current value of the current supplied to the light source element is increased to the fifth current value according to predetermined fifth information; the third information is determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the ninth current value when the temperature of the light source element is lower than the second temperature threshold, and the current value of the current supplied to the light source element is increased to the fifth current value according to the fifth information; and the ninth current value and the fifth information are determined based on a change in the amount of light emitted by the light source element when current supply to the light source element is started at the fifth current value when the temperature of the light source element is lower than the second temperature threshold. A method for driving the light source element according to claim 6 .

13. The method for driving a light source element according to any one of claims 1 to 12, wherein the light source element is an LED element.

14. A method for driving a light source element according to any one of claims 1 to 13, wherein the peak wavelength of light emitted from the light source element is within a range of 360 to 370 nm.

15. A method for driving a light source element according to any one of claims 1 to 13, wherein the peak wavelength of light emitted from the light source element is within a range of 380 to 390 nm.

16. A method for driving a light source element according to any one of claims 1 to 13, wherein the peak wavelength of light emitted from the light source element is within a range of 400 to 410 nm.

17. A light source unit comprising: a plurality of light source elements that are two-dimensionally arranged on a surface of a fixed object, each emitting light with a first amount of light when supplied with a current of a first current value; a detection unit that detects the temperature of the plurality of light source elements; and a control unit that controls the value of the current supplied to the plurality of light source elements, wherein the control unit starts supplying current to the plurality of light source elements at a second current value lower than the first current value, and increases the current value of the current supplied to the plurality of light source elements from the second current value to the first current value, and the current value of the current supplied to the plurality of light source elements at a first time point is a corrected current value obtained by acquiring from first information predetermined current values ​​of the current supplied to the plurality of light source elements at the first time point at each time point during a period in which current supply to the plurality of light source elements is started at a predetermined third current value and the current value of the current supplied to the plurality of light source elements is increased to the first current value, and the acquired current value is a corrected current value obtained by correcting the current value based on the temperature of the plurality of light source elements.

18. The light source unit described in claim 17, wherein the control unit calculates the second current value by correcting the predetermined third current value based on the temperatures of the multiple light source elements when current supply to the multiple light source elements is started, and calculates a current value of the current to be supplied to the multiple light source elements at the first time point by correcting the current value obtained from the first information based on the temperatures of the multiple light source elements detected by the detection unit at the first time point.

19. The light source unit described in claim 18, wherein the control unit corrects the current value acquired from the first information based on a previously acquired relationship between the elapsed time since the start of current supply to the multiple light source elements and the temperatures of the multiple light source elements, and the temperatures of the multiple light source elements at the first time point, and calculates a current value of a current to be supplied to the multiple light source elements at the first time point.

20. A light source unit as described in any one of claims 17 to 19, wherein the predetermined third current value is a current value at which current supply to the multiple light source elements is started, determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the first current value when the temperature of the multiple light source elements is lower than the first temperature threshold, and the first information is determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the first current value when the temperature of the multiple light source elements is lower than the first temperature threshold.

21. The predetermined third current value is a current value at which current supply to the multiple light source elements is started, the current value being determined based on a change in the amount of light emitted by the multiple light source elements when the current supply to the multiple light source elements is started at a fourth current value lower than the first current value when the temperature of the multiple light source elements is lower than a first temperature threshold, and the current value of the current supplied to the multiple light source elements is increased to the first current value in accordance with predetermined second information at each time point during which current supply to the multiple light source elements is started at the fourth current value and the current value of the current supplied to the multiple light source elements is increased to the first current value in accordance with the second information; and the first information is determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the fourth current value when the temperature of the multiple light source elements is lower than the first temperature threshold, and the current value of the current supplied to the multiple light source elements is increased to the first current value in accordance with the second information; The light source unit according to any one of claims 17 to 19, wherein the fourth current value and the second information are determined based on a change in the amount of light emitted by the plurality of light source elements when current supply to the plurality of light source elements is started at the first current value when the temperature of the plurality of light source elements is lower than the first temperature threshold value.

22. A device comprising: a plurality of light source elements that are two-dimensionally arranged on a surface of a fixed object, each emitting light with a first light emission amount when a current of a first current value is supplied thereto, and each emitting light with a second light emission amount lower than the first light emission amount when a current of a fifth current value lower than the first current value is supplied thereto; a detection unit that detects the temperature of the plurality of light source elements; and a control unit that controls the value of the current supplied to the plurality of light source elements, wherein the control unit, when putting the plurality of light source elements into a state in which they emit light with the second light emission amount, starts supplying current to the plurality of light source elements at a sixth current value higher than the fifth current value, and reduces the current value of the current supplied to the plurality of light source elements from the sixth current value to the fifth current value, a current value of the current supplied to the multiple light source elements at a first time point is a corrected current value obtained by obtaining the current value of the current supplied to the multiple light source elements at the first time point from third information which is predetermined at each time point during a period during which current supply to the multiple light source elements is started at a predetermined seventh current value and the current value of the current supplied to the multiple light source elements is changed to the fifth current value, and correcting the obtained current value based on the temperature of the multiple light source elements.

23. The light source unit described in claim 22, wherein the control unit calculates the sixth current value by correcting the predetermined seventh current value based on the temperatures of the plurality of light source elements when starting to supply current to the plurality of light source elements, and calculates a current value of the current to be supplied to the plurality of light source elements at the first time point by correcting the current value obtained from the third information based on the temperatures of the plurality of light source elements at the first time point.

24. The light source unit described in claim 23, wherein the control unit calculates a current value of a current to be supplied to the multiple light source elements at the first time point by correcting the current value acquired from the third information based on a previously acquired relationship between the elapsed time since the start of current supply to the multiple light source elements and the temperatures of the multiple light source elements, and the temperatures of the multiple light source elements at the first time point.

25. A light source unit as described in any one of claims 22 to 24, wherein the predetermined seventh current value is a current value at which current supply to the multiple light source elements is started, determined based on a change in the amount of light emitted by the multiple light source elements when a current value of a current supplied to the multiple light source elements is changed from the first current value to the fifth current value when the multiple light source elements, which are supplied with a current of the first current value and emitting the first amount of light, are put into a state in which they emit light at the second amount of light; and the third information is determined based on a change in the amount of light emitted by the multiple light source elements when a current value of a current supplied to the multiple light source elements is changed from the first current value to the fifth current value when the multiple light source elements, which are supplied with a current of the first current value and emitting the first amount of light, are put into a state in which they emit light at the second amount of light.

26. The predetermined seventh current value is a current value at which current supply to the multiple light source elements is started, the current value being determined based on a change in the amount of light emitted by the multiple light source elements when the current value supplied to the multiple light source elements is reduced to the fifth current value in accordance with predetermined fourth information at each time point during a period in which current supply to the multiple light source elements is started at an eighth current value higher than the fifth current value and the current value of the current supplied to the multiple light source elements is reduced to the fifth current value in accordance with the fourth information; and the third information is determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the eighth current value and the current value of the current supplied to the multiple light source elements is reduced to the fifth current value in accordance with the fourth information, 25. The light source unit according to claim 22, wherein the eighth current value and the fourth information are determined based on a change in the amount of light emitted by the plurality of light source elements when a current value of the current supplied to the plurality of light source elements is changed from the first current value to the fifth current value when the plurality of light source elements, which are supplied with a current of the first current value and emitting the first amount of light, are put into a state in which they emit light at the second amount of light.

27. A light source unit as described in any one of claims 22 to 24, wherein the predetermined seventh current value is a current value at which current supply to the multiple light source elements is started, determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the fifth current value when the temperature of the multiple light source elements is lower than the second temperature threshold, and the third information is determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the fifth current value when the temperature of the multiple light source elements is lower than the second temperature threshold.

28. The predetermined seventh current value is a current value at which current supply to the multiple light source elements is started at a ninth current value lower than the fifth current value when the temperature of the multiple light source elements is lower than the second temperature threshold, and the current value supplied to the multiple light source elements at each time point during which current supply to the multiple light source elements is started at the ninth current value and the current value of the current supplied to the multiple light source elements is increased to the fifth current value in accordance with predetermined fifth information; and the third information is determined based on a change in the amount of light emitted by the multiple light source elements when current supply to the multiple light source elements is started at the ninth current value when the temperature of the multiple light source elements is lower than the second temperature threshold, and the current value of the current supplied to the multiple light source elements is increased to the fifth current value in accordance with the fifth information; 25. The light source unit according to claim 22, wherein the ninth current value and the fifth information are determined based on a change in the amount of light emitted by the plurality of light source elements when current supply to the plurality of light source elements is started at the fifth current value when the temperature of the plurality of light source elements is lower than the second temperature threshold value.

29. A light source unit according to any one of claims 17 to 28, wherein the plurality of light source elements are a plurality of LED elements.

30. A light source unit according to any one of claims 17 to 28, wherein the peak wavelength of light emitted from the plurality of light source elements is within a range of 360 to 370 nm.

31. A light source unit according to any one of claims 17 to 28, wherein the peak wavelength of light emitted from the plurality of light source elements is within a range of 380 to 390 nm.

32. A light source unit according to any one of claims 17 to 28, wherein the peak wavelength of light emitted from the plurality of light source elements is within a range of 400 to 410 nm.

33. The light source unit according to any one of claims 17 to 32, wherein the light source unit is for an exposure apparatus.

34. An illumination unit comprising: a light source unit according to any one of claims 17 to 33; and an illumination optical system that guides the light emitted from the light source unit to an illuminated object.

35. An illumination unit comprising: a plurality of light source units as defined in any one of claims 17 to 33; and an illumination optical system including a combining optical element that combines light emitted from the plurality of light source units and directs the combined light emitted from the combining optical element to an illuminated body.

36. An exposure apparatus comprising: an illumination unit according to claim 34 or 35; and a projection optical system for projecting a pattern image of a mask illuminated by the illumination unit onto a photosensitive substrate.

37. The exposure apparatus according to claim 36, wherein the photosensitive substrate has at least one side length or diagonal length of 500 mm or more.

38. An exposure method using the exposure apparatus according to claim 36 or 37, comprising: illuminating a mask with the illumination unit; and projecting a pattern image of the mask onto a photosensitive substrate using the projection optical system.

Images