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

Abstract

A light source element drive method in which if a current of a first current value is supplied when the temperature of a light source element is within a first temperature range, light of a first light emission amount is emitted, wherein when the light source element is brought into the state of emitting light of the first light emission amount, current supply to the light source element at a second current value lower than the first current value is started, and the current value of the current supplied to the light source element is increased from the second current value to the first current value.

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.

[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 when the temperature of the light source element is within a first temperature range, and includes, when putting the light source element into a state in which it emits light at the first light emission amount, starting to supply current 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 from the second current value to the first current value.

[0006] According to a second 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, and that each emit light at a first light emission amount when a current of a first current value is supplied to the light source elements when the temperature of each element is within a first temperature range, and a control unit that controls the value of the current supplied to the plurality of light source elements, and when the control unit is to put the plurality of light source elements into a state in which they emit light at the first light emission amount, 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.

[0007] According to a third 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 illuminated object.

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

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

[0010] According to a sixth 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 amount when supplied with a current of a first current value, and includes, when putting the light source element into a state in which it emits light at the first light amount, supplying a current 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 from the second current value to the first current value.

[0011] The configurations of the embodiments described below may be modified as appropriate, and at least a portion of the configuration may be replaced with other components. Furthermore, components that are not particularly limited in terms of their placement may be placed in any position that allows them to achieve their function, not limited to the placement disclosed in the embodiments.

[0012] FIG. 1 is a schematic diagram showing the configuration of an exposure apparatus according to an embodiment. FIG. 2 is a schematic diagram showing the configuration of an illumination unit according to the present embodiment. FIG. 3(A) is a plan view showing the configuration of first and second light source arrays, and FIG. 3(B) is a diagram showing the internal configuration of first and second light source units. FIG. 4 is a diagram illustrating the relationship between the temperature and light emission amount of an LED chip. FIG. 5(A) is a graph showing the measurement results of the light emission amount of the light-emitting portion of an LED chip in Comparative Example 1, and FIG. 5(B) is a graph in which the light emission amount deviation rate is enlarged from FIG. 5(A) over a range of 0% to 2%. FIG. 6 is a diagram showing the output versus elapsed time in Comparative Example 1. FIG. 7(A) is a graph showing the measurement results of the light emission amount of the light-emitting portion of an LED chip according to the present embodiment, and FIG. 7(B) is a graph in which the light emission amount deviation rate is enlarged from FIG. 7(A) over a range of 0% to 2%. FIG. 8(A) is a graph showing the output of the first control unit versus elapsed time in this embodiment, and FIG. 8(B) is a graph enlarging the range of output from 98% to 100% in FIG. 8(A). FIG. 9(A) is a graph showing the results of a simulation of the light emission amount of the light-emitting unit of the LED chip in Comparative Example 2, and FIG. 9(B) is a graph enlarging the range of light emission amount deviation rates from -2% to 0% and elapsed time from 0 to 50 seconds in FIG. 9(A). FIG. 10 is a graph showing the output versus elapsed time in Comparative Example 2. FIG. 11(A) is a graph showing the results of a simulation of the light emission amount of the light-emitting unit of the LED chip in this embodiment, and FIG. 11(B) is a graph enlarging the range of light emission amount deviation rates from -2% to 0% and elapsed time from 0 to 50 seconds. FIG. 12 is a graph showing the output of the first control unit versus elapsed time in this embodiment. FIG. 13 is a schematic diagram showing the configuration of a lighting unit according to Modification Example 1. FIG. 14A is a plan view showing an example of a heat sink according to Modification 2, and FIG. 14B is a plan view showing a state in which a first light source array is mounted on the heat sink.

[0013] An exposure apparatus 10 according to one embodiment will be described with reference to FIGS.

[0014] (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.

[0015] 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.

[0016] 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.

[0017] The exposure apparatus 10 includes an illumination system IOP, a mask stage MST that holds a mask MSK, a projection optical system PL, a body 70 that supports these, a substrate stage PST that holds a plate P, and a control system for these. The control system provides overall control of each component of the exposure apparatus 10.

[0018] 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.

[0019] 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.

[0020] 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).

[0021] 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.

[0022] 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.

[0023] 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.

[0024] 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).

[0025] Position information of the substrate stage PST in the XY plane (including rotation information (yawing amount (rotation amount θz in the θz direction), pitching amount (rotation amount θx in the θx direction), and rolling amount (rotation amount θy in the θy direction))) is measured by an interferometer system. The interferometer system measures the position of the substrate stage PST by irradiating a measurement beam from the optical surface plate 73 onto a movable mirror (or a mirror-finished reflective surface (not shown)) provided at the end of the substrate stage PST, and receiving the reflected light from the movable mirror. The measurement results are supplied to a control device (not shown), and the control device drives the substrate stage PST in accordance with the measurement results of the interferometer system.

[0026] 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.

[0027] (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.

[0028] 2 is a diagram schematically illustrating the configuration of the illumination unit 90. As shown in FIG. 2, the illumination unit 90 includes a first light source unit OPU1, a second light source unit OPU2, and an illumination optical system 80.

[0029] (Configuration of light source unit) The first light source unit OPU1 includes a first light source array 20A, a first magnifying optical system 30A, and a first control unit CTR1, and the second light source unit OPU2 includes a second light source array 20B, a second magnifying optical system 30B, and a second control unit CTR2.

[0030] FIG. 3A is a plan view schematically illustrating the configuration of the first light source array 20A and the second light source array 20B. The first light source array 20A includes a plurality of LED (Light Emitting Diode) chips 23A (5 x 5 in FIG. 3A) arranged on a substrate 21A, for example. The number of LED chips 23A may be changed as needed. Each of the plurality of LED chips 23A has a light-emitting portion 231A, and the peak wavelength of light emitted from the light-emitting portion 231A is in the range of 380 to 390 nm. In other words, the light-emitting portion 231A is an ultraviolet LED (UV LED). More preferably, the peak wavelength of light emitted from the light-emitting portion 231A is 385 nm. The light-emitting surface of the light-emitting portion 231A is square, and the length of one side is a1. The LED chips 23A are arranged at a pitch P1, which is the distance between the centers of adjacent LED chips 23A.

[0031] The second light source array 20B includes, for example, a plurality of LED chips 23B (5 x 5 in FIG. 3A) arranged on a substrate 21B. The number of LED chips 23B may be changed appropriately as needed. Each of the plurality of LED chips 23B has a light-emitting portion 231B, and the peak wavelength of the light emitted from the light-emitting portion 231B is in the range of 360 to 370 nm. In other words, the light-emitting portion 231B is a UV LED. It is more preferable that the peak wavelength of the light emitted from the light-emitting portion 231B is 365 nm. The light-emitting surface of the light-emitting portion 231B is square, and the length of one side is a2. The LED chips 23B are arranged at a pitch P2.

[0032] The arrangement pitch P1 of the LED chips 23A and the arrangement pitch P2 of the LED chips 23B may be the same or different. Furthermore, the length a1 of one side of the light-emitting surface of the light-emitting portion 231A and the length a2 of one side of the light-emitting surface of the light-emitting portion 231B may be the same or different. The LED chips 23A and 23B may be arranged on, for example, a heat sink, rather than on a substrate.

[0033] FIG. 3B is a diagram schematically illustrating the internal configuration of the first light source unit OPU1 and the second light source unit OPU2. Since the internal configurations of the first light source unit OPU1 and the second light source unit OPU2 are identical, the configuration of the first light source unit OPU1 will be mainly described here. Here, the two directions in which the LED chips 23A are arranged are defined as the X1 direction and the Y1 direction. The X1 direction and the Y1 direction are orthogonal to each other. The direction orthogonal to the X1 direction and the Y1 direction is defined as the Z1 direction. The Z1 direction is approximately parallel to the optical axis OA of the light emitted by the light-emitting portion 231A. For clarity of illustration, FIG. 3B shows only four LED chips 23A arranged in a row along the Y1 direction.

[0034] 3B, the first magnifying optical system 30A is an optical system for forming a magnified image of the light-emitting portion 231A of each LED chip 23A on a predetermined plane PP. The first magnifying optical system 30A includes a plurality of lens units 31A arranged to correspond to the arrangement of the LED chips 23A. Each of the lens units 31A is a double-telecentric optical system that magnifies and projects the light-emitting portion 231A at a magnification M1 that is equal to or greater than (the arrangement pitch P1 of the LED chips 23B) / (the length a1 of one side of the light-emitting surface of the light-emitting portion 231A).

[0035] The second magnifying optical system 30B is an optical system for forming a magnified image of the light-emitting portion 231B of each LED chip 23B on a predetermined plane PP. The second magnifying optical system 30B includes a plurality of lens units 31B arranged to correspond to the arrangement of the LED chips 23B. Each of the lens units 31B is a double-telecentric optical system that magnifies and projects the light-emitting portion 231B at a magnification M2 that is equal to or greater than (the arrangement pitch P2 of the LED chips 23A) / (the length a2 of one side of the light-emitting surface of the light-emitting portion 231B).

[0036] In this embodiment, each of the lens units 31A and 31B includes four plano-convex lenses, but this is not limiting, and the lens units 31A and 31B may include, for example, two biconvex lenses, three biconvex lenses, or a plano-convex lens and a biconvex lens.

[0037] The first controller CTR1 controls the current value of the current supplied to the LED chips 23A included in the first light source array 20A. The second controller CTR2 controls the current value of the current supplied to the LED chips 23B included in the second light source array 20B.

[0038] FIG. 4 illustrates the relationship between the temperature of the LED chips 23A and 23B and the light-emitting amount of the light-emitting portions 231A and 231B. As shown in FIG. 4, when the temperature of the LED chips 23A and 23B is within a range (first temperature range) of temperature T1 to temperature T2 (>T1), the light-emitting portions 231A and 231B of the LED chips 23A and 23B emit light at a first light-emitting amount LA1 when a current of a first current value CV1 is supplied to the light-emitting portions 231A and 231B. The first temperature range may be, for example, 20°C to 90°C, or 20°C to 50°C. Furthermore, when the temperature of the LED chips 23A and 23B is within a range (second temperature range) of temperature T3 to temperature T4 (>T3), the light-emitting portions 231A and 231B of the LED chips 23A and 23B emit light at a second light-emitting amount LA2 when a current of a third current value CV3 lower than the first current value CV1 is supplied to the light-emitting portions 231A and 231B. The temperature T3 is lower than the temperature T1, and the temperature T4 is lower than the temperature T2.

[0039] In this embodiment, when the temperature is lower than temperature T1 and no current is being supplied to the light-emitting portion 231A of the LED chip 23A, the first controller CTR1 starts supplying current to the LED chip 23A at a second current value CV2 lower than the first current value CV1 when the temperature is lower than temperature T1 and no current is being supplied to the light-emitting portion 231A of the LED chip 23A, causing the light-emitting portion 231A to emit light at the first light-emitting amount LA1. Furthermore, when the temperature is lower than temperature T1 and no current is being supplied to the light-emitting portion 231B of the LED chip 23B, causing the temperature to be lower than temperature T1 and no current is being supplied to the light-emitting portion 231B of the LED chip 23B, causing the light-emitting portion 231A of the LED chip 23A, the second controller CTR2 starts supplying current to the LED chip 23B at a second current value CV2 lower than the first current value CV1. This reduces the time it takes for the light-emitting portions 231A and 231B of the LED chips 23A and 23B to stably emit light at the first light-emitting amount LA1. This point will be described in detail. In this embodiment, the phrase "the light-emitting portion 231A of the LED chip 23A 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 point t after the start of current supply to the LED chip 23A and the first light-emitting amount LA1, i.e., ΔLAt / LA1×100[%], is within a range of ±1%. This is because, when the light-emitting amount deviation rate is within a range of ±1%, the difference in the light-emitting amount of the light-emitting portion 231A of the LED chip 23A does not affect the exposure.

[0040] As comparative example 1, we will explain the case where current is supplied to the LED chip 23A at a first current value CV1 from the start of current supply when the light-emitting portion 231A of the LED chip 23A of the first light source array 20A, which is in a state where the temperature is lower than temperature T1 and no current is being supplied, is set to a state where it emits light at a first light emission amount LA1.

[0041] Fig. 5(A) is a graph showing the measurement results of the light emission amount of the light-emitting portion 231A of the LED chip 23A in Comparative Example 1. In Fig. 5(A), the vertical axis represents the deviation rate of the light emission amount, and the horizontal axis represents the elapsed time from the start of current supply. Fig. 5(B) is a graph in Fig. 5(A) where the deviation rate of the light emission amount on the vertical axis is enlarged over the range of 0% to 2%.

[0042] FIG. 6 is a diagram showing the output versus elapsed time in Comparative Example 1. The output [%] is the ratio of the current value CVt of the current supplied to the LED chip 23A at a certain time t to the first current value CV1 (output [%] = CVt / CV1 × 100). As shown in FIG. 6 , in Comparative Example 1, the output is constant at 100% from the start of current supply. That is, in Comparative Example 1, current is supplied to the LED chip 23A at the first current value CV1 from the start of current supply.

[0043] As shown in FIG. 5A , when current supply to the LED chip 23A starts at the first current value CV1, the light-emitting portion 231A of the LED chip 23A emits light at an amount of light emission higher than the first light-emitting amount LA1, and the amount of light emission decreases over time. This is because the amount of light emission of the light-emitting portion 231A included in the LED chip 23A decreases as the temperature of the LED chip 23A increases. More specifically, when current supply to the LED chip 23A starts, the temperature of the LED chip 23A is low, so the amount of light emission of the light-emitting portion 231A of the LED chip 23A is high. Thereafter, the amount of light emission decreases as the temperature of the LED chip 23A increases.

[0044] 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 231A of the LED chip 23A becomes stable.

[0045] Figure 7(A) is a graph showing the measurement results of the light emission amount of the light-emitting portion 231A of the LED chip 23A in this embodiment, and Figure 7(B) is a graph in which the range of the light emission amount deviation rate on the vertical axis in Figure 7(A) is enlarged from 0% to 2%.

[0046] Also, Figure 8(A) is a graph showing the output of the first control unit CTR1 versus elapsed time in this embodiment, and Figure 8(B) is a graph in which the range of output on the vertical axis in Figure 8(A) is enlarged from 98% to 100%.

[0047] 8A, in this embodiment, the first controller CTR1 starts current supply at an output lower than 100% and increases the output over time. That is, the first controller CTR1 starts current supply to the LED chip 23A at a second current value CV2 lower than the first current value CV1 (approximately 89% of the first current value CV1 in FIG. 8A), and increases the current value of the current supplied to the LED chip 23A over time.

[0048] As a result, as shown in Figures 7A and 7B, the deviation rate of the light emission amount is within a range of ±1% from the start of current supply. That is, before the current value of the current supplied to the LED chip 23A changes from the second current value CV2 to the first current value CV1, the LED chip 23A emits light at the first light emission amount LA1. This is because, when the temperature of the LED chip 23A is low, the first light emission amount LA1 can be obtained at a current value lower than the first current value CV1. By increasing the current value in response to the temperature rise of the LED chip 23A, it is possible to supply the LED chip 23A with a current of an appropriate value to obtain the first light emission amount LA1 at each temperature. Even after the current value of the current supplied to the LED chip 23A reaches the first current value CV1, the LED chip 23A continues to emit light at the first light emission amount LA1.

[0049] How to increase the output (the current value of the current supplied to the LED chip 23A) can be determined from the change in the light emission amount deviation rate (FIGS. 5A and 5B) obtained when current supply to the LED chip 23A is started at the first current value CV1.

[0050] For example, when the light emission amount deviation rate changes as shown in FIGS. 5A and 5B , the slope of the light emission amount deviation rate between elapsed times t1 and t2 can be calculated from the light emission amount deviation rate at elapsed time t1 and the light emission amount deviation rate at elapsed time t2, and the output increase rate (increase amount) between elapsed times t1 and t2 can be determined based on this slope. Alternatively, the output may be increased at a constant rate based on the value obtained by dividing the change in the light emission amount deviation rate over the time from the start of current supply until the light emission amount deviation rate falls within the ±1% range (the average slope of the light emission amount deviation rate). In this embodiment, the slope of the light emission amount deviation rate at adjacent measurement times is calculated, and the output increase rate is determined from the slope of the light emission amount deviation rate. Therefore, the shapes of the output graphs shown in FIGS. 8A and 8B are similar to the shapes of the light emission amount deviation rate graphs shown in FIGS. 5A and 5B, respectively, upside down.

[0051] In this way, by starting the supply of current to the LED chip 23A at the second current value CV2 that is lower than the first current value CV1 (for example, a current value that is approximately 89% of the first current value CV1) and increasing the current value of the current supplied to the LED chip 23A over time, it is possible to shorten the time until the light-emitting portion 231A of the LED chip 23A stably emits light at the first light emission amount LA1. Note that although the light-emitting portion 231A of the LED chip 23A has been described above, the same applies to the light-emitting portion 231B of the LED chip 23B.

[0052] The first controller CTR1 may further correct the output based on the light emission deviation rate (see FIG. 7A) achieved by changing the output, for example, as shown in FIG. 8A. In this case, the light emission deviation rate shown in FIG. 7A may be reflected in the output shown in FIG. 8A to create a new output graph, and the first controller CTR1 may change the output based on the new output graph. This further shortens the time until the light emission of the light-emitting unit 231A of the LED chip 23A stabilizes. The output correction based on the light emission deviation rate may be performed multiple times. Furthermore, the first controller CTR1 may perform machine learning using the light emission deviation rate data and the output data as training data, and determine the output using the resulting trained model.

[0053] Next, we will explain the case where the light-emitting portion 231A of the LED chip 23A, which is supplied with a current of the first current value CV1 and emits light at the first light amount LA1, is changed to a state in which it emits light at a second light amount LA2 which is lower than the first light amount LA1.

[0054] As described above, when the temperature of the LED chip 23A is within the range of temperature T3 to temperature T4 (second temperature range), the light-emitting portion 231A of the LED chip 23A emits light at the second light emission amount LA2 when a current of the third current value CV3 lower than the first current value CV1 is supplied (see Figure 4).

[0055] In this case, the first controller CTR1 decreases the current value supplied to the LED chip 23A from the first current value CV1 to the third current value CV3. More specifically, the current value supplied to the LED chip 23A is decreased over time from the first current value CV1 to the third current value CV3. This reduces the time required for the light-emitting portion 231A of the LED chip 23A to stably emit light at the second light-emitting amount LA2. This point will be described below. In this embodiment, "the light-emitting portion 231A of the LED chip 23A stably emits light at the second light-emitting amount LA2" means that the ratio of the difference ΔLAt (= LAt - LA2) between the light-emitting amount LAt at a certain time point t and the second light-emitting amount LA2 to the second light-emitting amount LA2 (referred to as the light-emitting amount deviation rate), i.e., ΔLAt / LA2 × 100 [%], is within the range of ±1%.

[0056] As comparative example 2, we will explain the case where, when a current of the first current value CV1 is supplied to the light-emitting portion 231A of the LED chip 23A, which is emitting light at the first light amount LA1, and the light-emitting portion 231A is changed to a state in which the light-emitting portion 231A emits light at the second light amount LA2, the current value of the current supplied to the LED chip 23A is immediately changed from the first current value CV1 to the third current value CV3.

[0057] Fig. 9(A) is a graph showing the results of a simulation of the amount of light emitted by the light-emitting portion 231A of the LED chip 23A in Comparative Example 2. Fig. 9(B) is an enlarged view of Fig. 9(A) for the range in which the deviation rate of the amount of light emitted is -2% to 0% and the elapsed time is 0 seconds to 50 seconds.

[0058] 9A, the vertical axis represents the light emission amount deviation rate, and the horizontal axis represents the elapsed time from the start of control to change the light emission amount of the light-emitting portion 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2. The light emission amount deviation rate in FIG. 9A is the ratio (= ΔLAt / LA2) of the difference ΔLAt (= LAt - LA2) between the light emission amount LAt at the elapsed time t and the second light emission amount LA2 to the second light emission amount LA2.

[0059] FIG. 10 is a graph showing the output versus time in Comparative Example 2. It is assumed that the third current value CV3 is 50% of the first current value CV1. Therefore, a 50% output means that the current value of the current supplied to the LED chip 23A is the third current value CV3. As shown in FIG. 9B , in Comparative Example 2, the output versus time is constant at 50%. In other words, in Comparative Example 2, a current is supplied to the LED chip 23A at the third current value CV3 immediately after control is initiated to change the light emission amount of the light-emitting portion 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2.

[0060] When the current value supplied to the LED chip 23A is immediately changed from the first current value CV1 to the third current value CV3, the light-emitting portion 231A of the LED chip 23A emits light at an amount of light emission lower than the second light emission amount LA2, and the amount of light emission increases over time, as shown in Figure 9(A) . This is because, when the supply of current at the third current value CV3 to the LED chip 23A begins, the temperature of the LED chip 23A is higher than temperature T4, and therefore the amount of light emission from the light-emitting portion 231A of the LED chip 23A decreases. Thereafter, the amount of light emission increases as the temperature of the LED chip 23A decreases.

[0061] After that, when approximately 6 seconds have passed since the current value supplied to the LED chip 23A was set to the third current value CV3, the deviation rate of the light emission amount falls within the range of ±1%, and the light emission amount of the light-emitting portion 231A of the LED chip 23A stabilizes.

[0062] FIG. 11(A) is a graph showing the simulation results of the light emission amount of the light-emitting portion 231A of the LED chip 23A in this embodiment, and FIG. 11(B) is an enlarged view of the range in which the light emission amount deviation rate is −2% to 0% and the elapsed time is 0 seconds to 50 seconds.

[0063] FIG. 12 is a diagram showing the output of the first control unit CTR1 with respect to elapsed time in this embodiment.

[0064] In this embodiment, when the first control unit CTR1 starts to control the light emission amount of the light-emitting unit 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2, the current value of the current supplied to the LED chip 23A is set to a current value lower than the first current value CV1 and higher than the third current value CV3, and the current value of the current supplied to the LED chip 23A is reduced over time to the third current value CV3.

[0065] For example, the first controller CTR1 sets the current value to about 56% of the first current value CV1 one-tenth of a second after starting control to change the light emission amount of the light-emitting portion 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2, and sets the current value to about 55% of the first current value CV1 two-tenths of a second after starting control to change the light emission amount of the light-emitting portion 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2. Thus, in this embodiment, when the first controller CTR1 starts control to change the light emission amount of the light-emitting portion 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2, the first controller CTR1 supplies current to the LED chip 23A at a current value lower than the first current value CV1 and higher than the third current value CV3, and decreases the current value over time.

[0066] 11A and 11B, the deviation rate of the light emission amount is within a range of ±1% from the start of control for changing the light emission amount of the light-emitting portion 231A of the LED chip 23A from the first light emission amount LA1 to the second light emission amount LA2. This is because, at the start of control, the temperature of the LED chip 23A is higher than temperature T4 and the light emission efficiency of the LED chip 23A is low, so that the second light emission amount LA2 is obtained with a current value higher than the third current value CV3. It is believed that this is because, by reducing the current value in accordance with the decrease in temperature of the LED chip 23A, a current of an appropriate value for obtaining the second light emission amount LA2 at each temperature can be supplied to the LED chip 23A.

[0067] How to reduce the output (the current value of the current supplied to the LED chip 23A) can be determined from the change in the light emission amount deviation rate (FIGS. 9(A) and 9(B)) obtained when current is supplied to the LED chip 23A at the third current value CV3 from the start of control to set the light emission amount of the light-emitting portion 231A of the LED chip 23A to the second light emission amount LA2.

[0068] For example, when the light emission amount deviation rate changes as shown in FIG. 9A , the slope of the light emission amount deviation rate between elapsed times t1 and t2 can be calculated from the light emission amount deviation rate at elapsed time t1 and the light emission amount deviation rate at elapsed time t2 from the start of control, and the output reduction rate (amount of reduction) between elapsed times t1 and t2 can be determined based on this slope. Alternatively, the output may be reduced at a constant rate based on the value obtained by dividing the amount of change in the light emission amount deviation rate over the time from the start of control until the light emission amount deviation rate falls within a ±1% range (the average slope of the light emission amount deviation rate). In this embodiment, the slope of the light emission amount deviation rate at adjacent measurement times is calculated, and the output reduction rate is determined from this slope of the light emission amount deviation rate. Therefore, the shape of the output graph shown in FIG. 12 is a shape that is the upside-down shape of the light emission amount deviation rate graph shown in FIG. 9A.

[0069] In this way, when the light-emitting portion 231A of the LED chip 23A is changed from emitting light at the first light-emitting amount LA1 to emitting light at the second light-emitting amount LA2 (<first light-emitting amount LA1), at the start of control, a current lower than the first current value CV1 and higher than the third current value CV3 is supplied to the LED chip 23A, and the current value of the current supplied to the LED chip 23A is reduced over time to the third current value CV3, thereby shortening the time until the light-emitting portion 231A of the LED chip 23A stably emits light at the second light-emitting amount LA2. Note that while the light-emitting portion 231A of the LED chip 23A has been described above, the same applies to the light-emitting portion 231B of the LED chip 23B.

[0070] The first controller CTR1 may further correct the output based on the light emission amount deviation rate (see FIG. 11A) achieved by changing the output, for example, as shown in FIG. 12. In this case, the light emission amount deviation rate shown in FIG. 11A may be reflected in the output shown in FIG. 12 to create a new output graph, and the first controller CTR1 may change the output based on the new output graph. This further reduces the time until the light emission amount of the light-emitting unit 231A of the LED chip 23A stabilizes. The output correction based on the light emission amount deviation rate may be performed multiple times. Furthermore, the first controller CTR1 may perform machine learning using the light emission amount deviation rate data and the output data as training data, and determine the output using the obtained trained model.

[0071] 2 again, the configuration of the illumination optical system 80 will be described. The illumination optical system 80 includes a first focusing optical system 81A including a first dichroic mirror DM1, a second focusing optical system 81B, a second dichroic mirror DM2, an imaging optical system 83, a fly's eye lens FEL, an aperture stop 85, and a condenser optical system 84.

[0072] The first focusing optical system 81A forms a pupil of the magnified image of the light-emitting unit 231A formed by the first magnifying optical system 30A. That is, the rear focal position of the first focusing optical system 81A is the pupil position. The first focusing optical system 81A has a first dichroic mirror DM1 along the optical path, which reflects at least a portion of the light with a peak wavelength of 385 nm. This causes the light beam to be incident on the second dichroic mirror DM2. Note that the first focusing optical system 81A may be configured without the first dichroic mirror DM1. In this case, the arrangement of the first light source unit OPU1 and the arrangement of each lens in the first focusing optical system 81A may be appropriately adjusted so that the light beam is incident on the second dichroic mirror DM2. Furthermore, the first focusing optical system 81A may be configured with a single lens or a lens group including multiple lenses.

[0073] The second focusing optical system 81B forms a pupil of the enlarged image of the light-emitting unit 231B formed by the second magnifying optical system 30B. That is, the rear focal position of the second focusing optical system 81B is the pupil position. The second focusing optical system 81B may be composed of a single lens or a lens group including multiple lenses.

[0074] The second dichroic mirror DM2 transmits at least a portion of the light with a peak wavelength of 385 nm and reflects at least a portion of the light with a peak wavelength of 365 nm, thereby forming a composite image by superimposing the pupil image formed by the first focusing optical system 81A and the pupil image formed by the second focusing optical system 81B.

[0075] In this embodiment, the second dichroic mirror DM2 forms a composite image by superimposing the pupil image formed by the first focusing optical system 81A and the pupil image formed by the second focusing optical system 81B. That is, the second dichroic mirror DM2 is disposed at a position that is the back focal position of the first focusing optical system 81A and the back focal position of the second focusing optical system 81B. As a result, the second dichroic mirror DM2 Koehler-illuminates the light emitted from the first light source unit OPU1 and the light emitted from the second light source unit OPU2. By Koehler-illuminating the light, it is possible to reduce changes in the illuminance of the light beam of the pupil image formed by the first focusing optical system 81A and the second focusing optical system 81B. In addition, without being limited to the configuration of this embodiment, the first focusing optical system 81A and the second focusing optical system 81B may be configured to perform critical illumination that forms an image of the first light source unit OPU1 and an image of the second light source unit OPU2 on the second dichroic mirror DM2, respectively.

[0076] The illumination unit 90 is provided with a detector DT10 for monitoring light with a peak wavelength of 385 nm, a detector DT20 for monitoring light with a peak wavelength of 365 nm, and a detector DT30 for monitoring light with a peak wavelength of 385 nm and light with a peak wavelength of 365 nm.

[0077] Specifically, detector DT10 detects the illuminance of light with a peak wavelength of 385 nm reflected by first dichroic mirror DM1. Detector DT20 detects the illuminance of light with a peak wavelength of 365 nm reflected by second dichroic mirror DM2. Detector DT30 detects the illuminance of 385 nm light unintentionally reflected by second dichroic mirror DM2 and the illuminance of 365 nm light unintentionally transmitted by second dichroic mirror DM2.

[0078] The detection results of detectors DT10 to DT30 are output to the first control unit CTR1 and the second control unit CTR2, and the first control unit CTR1 and the second control unit CTR2 control the value of the current supplied to the LED chips 23A and 23B provided in the first light source unit OPU1 and the second light source unit OPU2, respectively, based on the detection results of detectors DT10 to DT30.

[0079] The imaging optical system 83 is a double-telecentric optical system that projects the composite image formed by the second dichroic mirror DM2 onto the incident end of the fly-eye lens FEL at an equal magnification. Note that the imaging optical system 83 may also reduce and project the composite image formed by the second dichroic mirror DM2 onto the incident end of the fly-eye lens FEL.

[0080] 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).

[0081] Therefore, the light beam incident on the fly-eye lens FEL is wavefront split by the multiple lens elements, and one light source image is formed on or near the rear focal plane (exit surface) of each lens element. That is, a substantial surface light source, i.e., a secondary light source, consisting of multiple light source images is formed on or near the rear focal plane (exit surface) of the fly-eye lens FEL. The light beam from the secondary light source formed on or near the rear focal plane (exit surface) of the fly-eye lens FEL is incident on an aperture stop 85 arranged nearby. In this embodiment, the rear focal plane (exit surface) of the fly-eye lens FEL is optically conjugate with the first light source array 20A and the second light source array 20B.

[0082] The aperture stop 85 is disposed at a position that is nearly optically conjugate with the entrance pupil plane of the projection optical system PL, and has a variable opening for defining the range that contributes to illumination from the secondary light source. The aperture stop 85 changes the aperture diameter of the variable opening to set the σ value (the ratio of the aperture diameter of the secondary light source image on the pupil plane of the projection optical system to the aperture diameter of the pupil plane) that determines the illumination conditions to a desired value. The light from the secondary light source that passes through the aperture stop 85 is subjected to the focusing action of the condenser optical system 84, and then illuminates a mask MSK on which a predetermined pattern is formed in a superimposed manner.

[0083] 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 chips that emit light having a peak wavelength in the range of 360 to 440 nm.

[0084] For example, the peak wavelength of the light emitted from the light-emitting portion 231A of the LED chip 23A may be in the range of 400 to 410 nm. For example, the first light source unit OPU1 may be configured to emit light with a peak wavelength of 405 nm, and the second light source unit OPU2 may be configured to emit light with a peak wavelength of 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 of the present embodiment, it is preferable to change the material of the dichroic mirror appropriately depending on the wavelengths used.

[0085] As described above in detail, according to this embodiment, the first light source unit OPU1 includes a plurality of LED chips 23A that are two-dimensionally arranged on the surface of the substrate 21A and each emit light at a first light-emitting amount LA1 when a current of a first current value CV1 is supplied to the LED chips 23A when the temperature is within the range of T1 to T2, and a first controller CTR1 that controls the value of the current supplied to the LED chips 23A. When the plurality of LED chips 23A are to emit light at the first light-emitting amount LA1, the first controller CTR1 starts supplying current to the plurality of LED chips 23A at a second current value CV2 that is lower than the first current value CV1, and then increases the current value supplied to the LED chips 23A from the second current value CV2 to the first current value CV1. This allows current to be supplied to the LED chips 23A at a current value corresponding to the temperature rise of the LED chips 23A, thereby shortening the time until the light-emitting portions 231A of the LED chips 23A stably emit light at the first light-emitting amount LA1.

[0086] Furthermore, in this embodiment, when the temperature of the LED chips 23A is within the range of temperatures T3 to T4, the LED chips 23A emit light at a second light-emitting amount LA2 lower than the first light-emitting amount LA1 when a current of a third current value CV3 lower than the first current value CV1 is supplied to the LED chips 23A. When the LED chips 23A, which are receiving the current of the first current value CV1 and emitting light at the first light-emitting amount LA1, are changed to emit light at the second light-emitting amount LA2, the first controller CTR1 reduces the current value supplied to the LED chips 23A from the first current value CV1 to the third current value CV3. Specifically, the first controller CTR1 reduces the current value supplied to the LED chips 23A over time from the first current value CV1 to the third current value CV3. More specifically, the first control unit CTR1 supplies the LED chip 23A with a current value that is lower than the first current value CV1 and higher than the third current value CV3, and reduces the current value of the current supplied to the LED chip 23A to the third current value CV3 over time. As a result, the LED chip 23A is supplied with a current value that corresponds to the decrease in temperature of the LED chip 23A, thereby shortening the time until the light-emitting unit 231A of the LED chip 23A stably emits light at the second light emission amount LA2.

[0087] (Modification 1) The illumination unit to which the first light source unit OPU1 and the second light source unit OPU2 are applied is not limited to the above-described embodiment. Fig. 13 is a schematic diagram showing the configuration of an illumination unit 90A according to Modification 1.

[0088] 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 and the second light source unit OPU2 are the same as those in the above embodiment, and therefore detailed description thereof will be omitted.

[0089] The illumination optical system 80A includes a first focusing optical system 81A1, a second focusing optical system 81B1, a third dichroic mirror DM3, an imaging optical system 83A, a fly-eye lens FEL, an aperture stop 85, and a condenser optical system 84A.

[0090] The first focusing optical system 81A1 is disposed on or near the predetermined plane PP, and forms a pupil of the enlarged image of the light-emitting unit 231A formed by the first magnifying optical system 30A. The first focusing optical system 81A1 may be composed of a single lens, or may be composed of a lens group including a plurality of lenses.

[0091] The second focusing optical system 81B1 is disposed on or near the predetermined plane PP, and forms a pupil of the magnified image of the light-emitting unit 231B formed by the second magnifying optical system 30B. The second focusing optical system 81B1 may be composed of a single lens or a lens group including multiple lenses.

[0092] 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 81A1 and the pupil image formed by the second focusing optical system 81B1.

[0093] The imaging optical system 83A 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 83A 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.

[0094] The light beam incident on the fly-eye lens FEL is wavefront split by the multiple lens elements 60, and one light source image is formed on or near the rear focal plane of each lens element 60. 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 arranged nearby.

[0095] Light from the secondary light source passes through the aperture stop 85 and is condensed by the condenser optical system 84A, and then illuminates a mask MSK on which a predetermined pattern is formed in a superimposed manner.

[0096] The projection optical system PL according to the first modification is an Offner-type optical system that is supported below (on the -Z side of) the mask stage MST by an optical surface plate 73. The projection optical system PL forms, for example, an arc-shaped image field with its longitudinal direction in the Y-axis direction.

[0097] 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.

[0098] As shown in Modification 2, the first light source unit OPU1 and the second light source unit OPU2 may be applied to the light source of an exposure apparatus equipped with an Offner type projection optical system PL.

[0099] As described above, the amount of light emitted by the light-emitting portion 231A of the LED chip 23A and the amount of light emitted by the light-emitting portion 231B of the LED chip 23B decrease as the temperatures of the LED chips 23A and 23B increase. In other words, the light-emitting efficiency of the LED chips 23A and 23B decreases as the temperatures increase.

[0100] Therefore, it is preferable to mount the first light source array 20A and the second light source array 20B on a heat sink, respectively, to cool the LED chips 23A and 23B.

[0101] Fig. 14(A) is a plan view showing an example of a heat sink 40 according to Modification 2, and Fig. 14(B) is a plan view showing a state in which a first light source array 20A is mounted on the heat sink 40. In Fig. 14(A) and Fig. 14(B), the longitudinal direction of the heat sink 40 is the X2 direction, the lateral direction is the Y2 direction, and the thickness direction is the Z2 direction. The X2 direction, Y2 direction, and Z2 direction are perpendicular to one another.

[0102] As shown in Figure 14 (A), the heat sink 40 extends in the Y2 direction and has multiple flow paths 403 through which a refrigerant flows from a refrigerant inlet 401 provided at one end of the heat sink 40 in the Y2 direction to a refrigerant outlet 402 provided at the other end of the heat sink 40 in the Y2 direction.

[0103] In the second modification, the LED chips 23A adjacent to each other in the X2 direction on the substrate 21A mounted on the heat sink 40 are connected in series. Here, the groups of the LED chips 23A connected in series are designated as a first group G1, a second group G2, a third group G3, a fourth group G4, and a fifth group G5 in this order from the refrigerant inlet 401 toward the refrigerant outlet 402 (see FIG. 14B ).

[0104] 14B, for example, current flows through the LED chip 23A in the direction indicated by the arrow AR1 (+X2 direction), while the coolant in the heat sink 40 flows in the direction indicated by the arrow AR2 (-Y2 direction).

[0105] The cooling effect of the refrigerant is stronger the closer to the refrigerant inlet 401, so when the same current value is supplied to all of the LED chips 23A included in the first light source array 20A, the temperature of the LED chips 23A increases from the refrigerant inlet 401 toward the refrigerant outlet 402. In other words, the closer the LED chips 23A are to the refrigerant inlet 401, the lower their temperature becomes.

[0106] In the LED chips 23A connected in series, the current value supplied to each LED chip 23A cannot be made different for each LED chip 23A. Therefore, the current value supplied to the LED chips 23A connected in series is controlled uniformly in the wiring direction (X2 direction).

[0107] Here, if there is a temperature difference between adjacent LED chips 23A in the wiring direction (X2 direction), it is difficult to correct the amount of light emitted by the light-emitting portion 231A of the LED chip 23A. Therefore, in Modification 2, the substrate 21A is mounted on the heat sink 40 so that the wiring direction of the LED chips 23A (see arrow AR1) and the direction in which the coolant flows in the heat sink 40 (see arrow AR2) are perpendicular to each other.

[0108] With the configuration shown in FIG. 14B , the LED chips 23A (LED chips 23A included in the same group) along the wiring direction are located at approximately the same distance from the refrigerant inlet 401, and therefore their temperatures change in the same manner. Therefore, by controlling the current value supplied to each wiring (each group), the light-emitting units 231A of the LED chips 23A can be made uniform in terms of the amount of light emitted. Specifically, the current value supplied to the LED chips 23A in the first group G1, which are closest to the refrigerant inlet 401, is made lowest, and the current value supplied to the groups farthest from the refrigerant inlet 401 is made higher. That is, the current value supplied to the LED chips 23A in the fifth group G5 is made highest. This allows the light-emitting units 231A of the multiple LED chips 23A included in the first light source array 20A to be made approximately the same, thereby improving illuminance uniformity. The same applies to the second light source array 20B. The LED chips 23A and LED chips 23B may be directly mounted on the heat sink 40.

[0109] In the above embodiment and its modified examples, the illumination unit 90, 90A includes the first light source unit OPU1, the second light source unit OPU2, and the illumination optical system 80, 80A including the second dichroic mirror DM2. However, this is not limited to this. For example, the illumination unit 90, 90A may include only one of the first light source unit OPU1 and the second light source unit OPU2. In this case, the illumination optical system 80, 80A may have any configuration as long as it can guide light emitted from the first light source unit OPU1 or the second light source unit OPU2 to the mask MSK.

[0110] 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.

[0111] 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.

[0112] 10 Exposure apparatus 20A First light source array 20B Second light source array 21A, 21B Substrate 23A, 23B LED chip 40 Heat sink 80, 80A Illumination optical system 90, 90A Illumination unit 100 Projection optical unit CTR1 First control unit CTR2 Second control unit DM2 Second dichroic mirror FEL Fly's eye lens MSK Mask 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 at a first light emission amount when a current of a first current value is supplied when the temperature of the light source element is within a first temperature range, When the light source element is set to a state in which it emits light at the first light emission amount, a current supply to the light source element is started at a second current value lower than the first current value; increasing a current value of a current supplied to the light source element from the second current value to the first current value; A method for driving a light source element comprising:

2. In the increasing step, the current value of the current supplied to the light source element is increased over time from the second current value to the first current value. A method for driving a light source element according to claim 1 .

3. The second current value is a predetermined current value, In the increasing step, the current value of the current supplied to the light source element is increased from the second current value to the first current value at a predetermined first rate.

3. A method for driving a light source element according to claim 1.

4. the first rate is a constant rate; The method for driving the light source element according to claim 3 .

5. The second current value and the first ratio are determined based on a change in the amount of light emitted from the light source element when current supply to the light source element is started at the first current value. The method for driving the light source element according to claim 3 .

6. the light source element emits light at the first light emission amount before the current value of the current supplied to the light source element changes from the second current value to the first current value; 3. A method for driving a light source element according to claim 1.

7. After the current value of the current supplied to the light source element reaches the first current value, the light source element continues to emit light at the first light emission amount. The method for driving a light source element according to claim 6 .

8. The first temperature range is 20°C to 90°C.

3. A method for driving a light source element according to claim 1.

9. The second 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 current supply to the light source element is started at a fifth current value lower than the first current value and the current value of the current supplied to the light source element is increased at a third rate up to the first current value; the first rate is a rate at which the current value of the current to be supplied to the light source element is increased from the second current value to the first current value, the rate 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 fifth current value and the current value of the current to be supplied to the light source element is increased to the first current value at the third rate; the fifth current value and the third ratio 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. The method for driving the light source element according to claim 3 .

10. A method for driving a light source element, wherein when a current of a first current value is supplied to the light source element while the temperature of the light source element is within a first temperature range, the light source element emits light at a first light intensity, and when a current of a third current value lower than the first current value is supplied to the light source element while the temperature of the light source element is within a second temperature range, the light source element emits light at a second light intensity lower than the first light intensity, When the light source element, which is supplied with the current of the first current value and is emitting light at the first light emission amount, is brought into a state in which it emits light at the second light emission amount, starting to supply current to the light source element at a fourth current value higher than the third current value; reducing a current value of the current supplied to the light source element from the fourth current value to the third current value; A method for driving a light source element comprising:

11. The decreasing step decreases the current value of the current supplied to the light source element from the fourth current value to the third current value over time. The method for driving a light source element according to claim 10.

12. The fourth current value is a predetermined current value, The current value of the current supplied to the light source element is decreased from the fourth current value to the third current value at a predetermined second rate.

12. A method for driving a light source element according to claim 10.

13. the second ratio is a constant ratio; The method for driving a light source element according to claim 12.

14. The fourth current value and the second ratio are determined based on a change in the light emission amount of the light source element when the current value of the current supplied to the light source element, which is supplied with the first current value and is emitting light at the first light emission amount, is changed from the first current value to the third current value. The method for driving a light source element according to claim 12.

15. The light source element is an LED element.

12. A method for driving a light source element according to claim 1, claim 2, claim 10, or claim 11.

16. The peak wavelength of the light emitted from the light source element is in the range of 360 to 370 nm.

12. A method for driving a light source element according to claim 1, claim 2, claim 10, or claim 11.

17. The peak wavelength of the light emitted from the light source element is in the range of 380 to 390 nm.

12. A method for driving a light source element according to claim 1, claim 2, claim 10, or claim 11.

18. The peak wavelength of the light emitted from the light source element is in the range of 400 to 410 nm.

12. A method for driving a light source element according to claim 1, claim 2, claim 10, or claim 11.

19. The fourth 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 current supply to the light source element is started at a sixth current value higher than the third current value, and the current value of the current supplied to the light source element is reduced to the third current value at a fourth rate; the second rate is a rate at which the current value of the current to be supplied to the light source element is reduced from the fourth current value to the third current value, the rate 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 sixth current value and the current value of the current to be supplied to the light source element is reduced to the third current value at the fourth rate; the sixth current value and the fourth ratio are determined based on a change in the amount of light emitted by the light source element when the current value of the current supplied to the light source element is changed from the first current value to the third current value. The method for driving a light source element according to claim 12.

20. a plurality of light source elements that are two-dimensionally arranged on a surface of a fixing object, each emitting light at a first light emission amount when a current of a first current value is supplied to the light source elements when the temperature of each element is within a first temperature range; a control unit that controls the value of current supplied to the plurality of light source elements; Equipped with The control unit when the plurality of light source elements are to be brought into a state in which they emit light at the first light emission amount, a current supply to the plurality of light source elements is started at a second current value lower than the first current value; increasing a current value of the current supplied to the plurality of light source elements from the second current value to the first current value; Light source unit.

21. the control unit increases a current value of the current supplied to the plurality of light source elements from the second current value to the first current value over time. The light source unit according to claim 20.

22. The second current value is a predetermined current value, the control unit increases a current value of the current supplied to the plurality of light source elements from the second current value to the first current value at a predetermined first rate; 22. The light source unit according to claim 20 or 21.

23. the first rate is a constant rate; 23. The light source unit according to claim 22.

24. The second current value and the first ratio 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.

23. The light source unit according to claim 22.

25. the plurality of light source elements emit light at the first light emission amount before the current value of the current supplied to the plurality of light source elements changes from the second current value to the first current value; 22. The light source unit according to claim 20 or 21.

26. After the current value of the current supplied to the plurality of light source elements reaches the first current value, the plurality of light source elements continue to emit light at the first light emission amount.

26. The light source unit according to claim 25.

27. The first temperature range is 20°C to 90°C.

22. The light source unit according to claim 20 or 21.

28. The second 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 current supply to the light source element is started at a fifth current value lower than the first current value and the current value of the current supplied to the light source element is increased at a third rate up to the first current value; the first rate is a rate at which the current value of the current to be supplied to the light source element is increased from the second current value to the first current value, the rate 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 fifth current value and the current value of the current to be supplied to the light source element is increased to the first current value at the third rate; the fifth current value and the third ratio 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.

23. The light source unit according to claim 22.

29. A plurality of light source elements arranged two-dimensionally on the surface of a fixed object, each emitting light at a first light intensity when a current of a first current value is supplied when the temperature of each element is within a first temperature range, and each emitting light at a second light intensity lower than the first light intensity when a current of a third current value lower than the first current value is supplied when the temperature of each element is within a second temperature range; a control unit that controls the value of current supplied to the plurality of light source elements; Equipped with The control unit when the plurality of light source elements, which are supplied with the current of the first current value and are emitting light at the first light emission amount, are brought into a state in which they emit light at the second light emission amount, current supply to the plurality of light source elements is started at a fourth current value higher than the third current value, reducing the current value of the current supplied to the plurality of light source elements from the fourth current value to the third current value; Light source unit.

30. the control unit reduces the current value of the current supplied to the plurality of light source elements from the fourth current value to the third current value over time.

30. The light source unit of claim 29.

31. The fourth current value is a predetermined current value, the control unit reduces the current value of the current supplied to the plurality of light source elements from the fourth current value to the third current value at a predetermined second rate; 31. The light source unit according to claim 29 or 30.

32. the second ratio is a constant ratio; 32. The light source unit according to claim 31.

33. The fourth current value and the second ratio are determined based on a change in the light emission amount of the plurality of light source elements when the current value of the current supplied to the plurality of light source elements that are supplied with the first current value and are emitting light at the first light emission amount is changed from the first current value to the third current value.

32. The light source unit according to claim 31.

34. The plurality of light source elements are a plurality of first light source elements arranged in a first direction and connected in series; a plurality of second light source elements spaced apart from the plurality of first light source elements in a second direction perpendicular to the first direction, arranged in the first direction, and connected in series; Including, the object to be fixed is a substrate mounted on a heat sink, the heat sink has a plurality of flow paths extending in the second direction and through which a refrigerant flows from a refrigerant inlet provided at one end of the heat sink in the second direction to a refrigerant outlet provided at the other end of the heat sink in the second direction.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

35. The plurality of light source elements are a plurality of first light source elements arranged in a first direction and connected in series; a plurality of second light source elements spaced apart from the plurality of first light source elements in a second direction perpendicular to the first direction, arranged in the first direction, and connected in series; Including, the object to be fixed is a heat sink, the heat sink has a plurality of flow paths extending in the second direction and through which a refrigerant flows from a refrigerant inlet provided at one end of the heat sink in the second direction to a refrigerant outlet provided at the other end of the heat sink in the second direction.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

36. The plurality of light source elements are a plurality of LED elements.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

37. The peak wavelength of the light emitted from the plurality of light source elements is within a range of 360 to 370 nm.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

38. The peak wavelength of the light emitted from the plurality of light source elements is in the range of 380 to 390 nm.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

39. The peak wavelength of the light emitted from the plurality of light source elements is in the range of 400 to 410 nm.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

40. The light source unit is for use in an exposure device.

31. The light source unit according to claim 20, claim 21, claim 29, or claim 30.

41. The fourth 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 current supply to the light source element is started at a sixth current value higher than the third current value, and the current value of the current supplied to the light source element is reduced to the third current value at a fourth rate; the second rate is a rate at which the current value of the current to be supplied to the light source element is reduced from the fourth current value to the third current value, the rate 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 sixth current value and the current value of the current to be supplied to the light source element is reduced to the third current value at the fourth rate; the sixth current value and the fourth ratio are determined based on a change in the amount of light emitted by the light source element when the current value of the current supplied to the light source element is changed from the first current value to the third current value.

32. The light source unit according to claim 31.

42. A light source unit according to claim 20, claim 21, claim 29, or claim 30; an illumination optical system that guides the light emitted from the light source unit to an illuminated object; A lighting unit comprising:

43. a plurality of light source units according to claim 20, claim 21, claim 29, or claim 30; an illumination optical system including a combining optical element that combines light beams emitted from the plurality of light source units, and that guides the combined light beam emitted from the combining optical element to an illuminated object; A lighting unit comprising:

44. A lighting unit according to claim 42, a projection optical system that projects a pattern image of a mask illuminated by the illumination unit onto a photosensitive substrate; An exposure apparatus comprising:

45. The photosensitive substrate has at least one side length or diagonal length of 500 mm or more.

45. The exposure apparatus according to claim 44.

46. ​​An exposure method using the exposure apparatus according to claim 44, comprising: illuminating a mask with the illumination unit; projecting a pattern image of the mask onto a photosensitive substrate using the projection optical system; An exposure method comprising:

47. 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, supplying a current to the light source element at a second current value lower than the first current value when the light source element is set to a state in which the light source element emits light at the first light emission amount; increasing a current value of a current supplied to the light source element from the second current value to the first current value; A method for driving a light source element comprising: