Light source device, exposure device, and method for manufacturing articles

Abstract

To suppress fluctuations in peak wavelength caused by changes in the amount of light emitted. [Solution] A light source device having an LED module in which a plurality of LEDs are arranged and a cooler for cooling the LED module, wherein the amount of light emitted from the LED module is variable, the LED module comprises a plurality of chip rows in which a plurality of LEDs are arranged, and a current control unit that controls the current for each of the plurality of chip rows, wherein the current control unit determines the number of chip rows that emit light by flowing a current of a predetermined value or more when the amount of light emitted is a first amount of light emitted, to be less than the number of chip rows that emit light by flowing a current of a predetermined value or more when the amount of light emitted is a second amount of light emitted which is greater than the first amount of light emitted, and controls the chip rows other than those that emit light by flowing a current of a predetermined value or more to flow a current smaller than the predetermined value (excluding no current).

Description

Technical Field

[0001] The present invention relates to a light source device, an exposure device, and a method for manufacturing an article.

Background Art

[0002] An exposure device is a device that transfers the pattern of a master plate (reticle or mask) to a photosensitive substrate (such as a wafer or a glass plate having a resist layer formed on its surface) through a projection optical system in a lithography process, which is a manufacturing process for semiconductor devices, liquid crystal display devices, and the like. As a light source for this pattern transfer (exposure light source), for example, a mercury lamp is used. In recent years, however, it is expected to be replaced with a light-emitting diode (LED: Light Emitting Diode). The LED has a short time from when a current is passed through a circuit that controls light emission until the light output becomes stable, and does not need to emit light constantly like a mercury lamp, so it also has a long lifespan. However, since the luminance per LED is small, in order to use an LED as a light source instead of a mercury lamp, it is necessary to integrate a plurality of LEDs to improve the light emission amount of the light emitted as an exposure light source.

[0003] In order to improve the productivity of the exposure device, it is necessary to increase the light emission amount of the exposure light source. However, if the current value flowing through each integrated LED is increased to increase the light emission amount, the heat generation amount of the LED will also increase. In addition, depending on the exposure target, the exposure device may not require a large light amount for pattern transfer, and the current value flowing through the LED may be decreased to decrease the light emission amount.

[0004] As described above, changing the current flowing through the LED according to the object to be exposed changes the amount of heat generated by the LED, thus changing the LED's temperature. LEDs have a temperature-dependent characteristic in which the peak wavelength of the light emitted from the LED fluctuates depending on the LED's temperature. Furthermore, exposure equipment may experience a decrease in exposure performance due to fluctuations in the wavelength of light from the exposure light source (wavelength of exposure light). Therefore, even when using an LED as the exposure light source, fluctuations in the peak wavelength of the exposure light are undesirable. For example, an LED can experience a wavelength fluctuation of about 2 nm with a temperature change of about 15°C, which may adversely affect the exposure process.

[0005] Patent Document 1 describes a method for suppressing fluctuations in the peak wavelength of light emitted from an LED module. Specifically, it involves selecting an LED group from LED modules with different wavelength characteristics for each LED group, and correcting the current value supplied to the LEDs based on the temperature of the LEDs in the selected LED group, thereby suppressing fluctuations in the peak wavelength of light. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-59706 [Overview of the project] [Problems that the invention aims to solve]

[0007] However, Patent Document 1 does not describe how to make the light output of an LED module variable, nor does it show a method for suppressing the fluctuation in the peak wavelength of light from the LED module caused by changing the light output.

[0008] Therefore, the present invention aims to provide a light source device that is advantageous in suppressing fluctuations in the peak wavelength of light from an LED module caused by changes in the amount of light emitted. [Means for solving the problem]

[0009] To achieve the above objective, a light source device as one aspect of the present invention comprises an LED module having a plurality of LEDs arranged in a row, and a cooler for cooling the LED module, wherein the amount of light emitted from the LED module is variable, and the LED module comprises a plurality of chip rows having a plurality of LEDs arranged in a row, and has a current control unit that controls the current for each of the plurality of chip rows, and the current control unit determines the number of chip rows that emit light by flowing a current of a predetermined value or more when the amount of light emitted is a first amount of light emitted, to be less than the number of chip rows that emit light by flowing a current of a predetermined value or more when the amount of light emitted is a second amount of light emitted which is greater than the first amount of light emitted, and controls the chip rows other than those that emit light by flowing a current of a predetermined value or more to flow a current smaller than the predetermined value (excluding no current). [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a light source device that is advantageous in suppressing fluctuations in peak wavelength caused by changes in the amount of light emitted. [Brief explanation of the drawing]

[0011] [Figure 1] This is a schematic diagram showing the configuration of the light source device of the first embodiment. [Figure 2] This is a diagram showing the configuration of the cooler in the first embodiment. [Figure 3] This diagram shows the temperature distribution of the LED when the current value is changed. [Figure 4] This figure shows the method for lighting up an LED in the first embodiment. [Figure 5] This figure shows the temperature distribution of the LED in the first embodiment. [Figure 6] This figure shows the configuration of the cooler in the second embodiment. [Figure 7] This figure shows the configuration of the LED module in the third embodiment. [Figure 8] This figure shows the chip array implemented in the LED module of the third embodiment. [Figure 9] This figure shows the temperature distribution of the LED in the fourth embodiment. [Figure 10] This is a schematic diagram showing the configuration of the exposure apparatus. [Modes for carrying out the invention]

[0012] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings. In each drawing, the same reference numeral is used for identical components, and redundant descriptions are omitted.

[0013] <First Embodiment> The light source device in this embodiment will now be described. Figure 1 is a schematic diagram showing the configuration of the light source device 10. The light source device 10 includes an LED module 3, which is provided with multiple chip rows 2 on a circuit board 11, each containing multiple LEDs 1 (LED chips), a power supply 4, a temperature controller 5, a cooler, and a control unit 7. In the following description, the term "LED chip" will be used to refer to a single LED element. The cooler is not shown in Figure 1, but it is provided in contact with the back surface of the substrate 11 opposite to the surface surface on which the LED chips 1 of the LED module 3 are arranged. The amount of light emitted by the LED module 3 in this embodiment is variable.

[0014] On the circuit board 11, a wiring 14 is connected to and mounted on the LED chip 1, and a circuit for causing the LED chip 1 to emit light is formed. The chip row 2 has a plurality of LED chips 1 connected in series. By flowing a current through the circuit, light of a predetermined wavelength is output from the LED chip 1, and the LED chip 1 generates heat. The package type of the LED module 3 having such a configuration is generally also referred to as Chip On Board (hereinafter referred to as COB). Since COB can integrate many LED chips, it is advantageous in that a large amount of light can be obtained. In the example shown in FIG. 1, the LED module 3 includes six chip rows, and each chip row 2 has ten LED chips 1. The LED chip 1 emits light when a current is supplied from the power source 4 through the wiring 14 for each chip row.

[0015] The control unit 7 has an acquisition unit 8 that acquires the light emission amount of the LED module 3 and a current control unit 9 (light amount change unit) that controls the current flowing through each chip row 2 of the LED module 3. The acquisition unit 8 transmits the acquired light emission amount to the current control unit 9. The acquisition unit 8, for example, receives information regarding the light emission amount required for the LED module from an external device. The acquisition unit 8 is not limited to this, and may also acquire information regarding the light emission amount when the light emission amount required by the user is input. The current control unit 9 determines the current value to be passed through each chip row 2 based on the light emission amount acquired by the acquisition unit 8 and drives the power source 4. The power source 4 cannot drive each LED chip on the circuit board 11 to light individually, but can drive them to light in units of chip rows.

[0016] The temperature regulator 5 supplies a refrigerant controlled to a constant temperature to the cooler through the pipe 6. By flowing the refrigerant inside the cooler at a constant speed, the heat generated when the LED chip 1 lights up is cooled. The refrigerant after taking away the heat circulates to the temperature regulator 5 and can cool the heat of the LED chip 1 again by being cooled by the temperature regulator 5.

[0017] When a large current flows through the LED chip 1, the amount of heat generated from the LED chip 1 also increases, and the temperature rises. Since the LED chip 1 uses semiconductors, there is a risk of damage when the temperature exceeds a predetermined level. When compared with an incandescent bulb, the incandescent bulb reaches a temperature of 100°C or higher during light emission, but the LED chip 1 does not operate at temperatures exceeding 100°C. Therefore, it is necessary to equip the light source device 10 with a cooler to suppress the temperature rise. Also, since LEDs have the property that their luminous efficiency increases as the temperature decreases, it is desirable to equip the light source device 10 with a cooler.

[0018] In order to improve the cooling efficiency of the cooler, it is preferable to use a material with high thermal conductivity for the circuit board 11. As the material of the circuit board 11, for example, a material containing copper or aluminum with high thermal conductivity may be used. As the refrigerant, for example, a liquid mainly composed of water with excellent cooling power or a liquid mainly composed of oil with excellent electrical insulation properties can be used. In this embodiment, an example of using a liquid as the refrigerant will be described, but it is not limited thereto. For example, the LED chip 1 may be cooled by air cooling by blowing a gas having a lower temperature than the LED chip 1 during temperature rise. When air cooling, a cooler equipped with a nozzle or the like for blowing out the gas is provided.

[0019] Figure 2 is a schematic diagram showing the configuration of the cooler 12. The cooler 12 is provided in contact with the LED module 3, but a conduction grease or the like for enhancing the thermal conductivity may be applied between the cooler 12 and the LED module 3. Inside the cooler 12, a flow path 13 through which the refrigerant flows is formed, and the refrigerant flows in a direction parallel to the direction in which the LED chips 1 are arranged in each chip row 2 of the LED module 3. Incidentally, the first direction in which the LED chips 1 are arranged in each chip row 2 of the LED module 3 may be a direction including a parallel component with respect to the second direction in which the refrigerant flows, but it is preferable that the first direction is within an angle of 45 degrees with respect to the second direction. Also, since the effect described later can be obtained as the first direction is closer to being parallel to the second direction, it is preferable that the first direction is within an angle of 15 degrees with respect to the second direction.

[0020] LED chips have a temperature-dependent characteristic in which the peak wavelength of light emitted from the LED chip changes depending on the LED chip's temperature. Furthermore, if the required illuminance or exposure changes depending on the object being illuminated, the target light output of the LED module is changed. When the current flowing through each LED chip is changed to alter the light output, the temperature of most or all of the LED chips changes, causing the peak wavelength of the light emitted from each LED chip (light from the LED module) to fluctuate.

[0021] Figure 3 is a conceptual diagram showing the temperature of LED chip 1 when the current value flowing through LED chip 1 is changed according to the amount of light emitted. The graph in Figure 3 shows the relationship between the position and temperature of LED chip 1 when LED chip 1 is lit at three different light emission levels 1 to 3. The diagram at the top of the graph in Figure 3 is a cross-sectional view of the light source device 10, showing that the position of LED chip 1 corresponds to the horizontal axis of the graph. To light up LED chip 1 to light emission level 1 (second light emission level), a current of 1A should be flowed through all LED chips 1. To light up LED chip 1 to light emission level 2 (first light emission level), which is 50% of light emission level 1, a current of 0.5A should be flowed through all LED chips 1. To light up LED chip 1 to light emission level 3, which is 33% of light emission level 1, a current of 0.33A should be flowed through all LED chips 1.

[0022] Upstream of the refrigerant, the refrigerant temperature is relatively low and the cooling power is high. However, downstream of the refrigerant, heat transfer to the refrigerant has already occurred, causing the refrigerant temperature to rise and thus reducing the cooling power, which in turn increases the temperature of the LED chips. In the case of light output 1, the temperature of LED chip 1 is about 20°C upstream of the refrigerant, but about 80°C downstream of the refrigerant. Therefore, the average temperature of all LED chips 1 is about 50°C. In the case of light output 2, the temperature of LED chip 1 is about 20°C upstream of the refrigerant, but about 50°C downstream of the refrigerant. Therefore, the average temperature of all LED chips 1 is about 35°C. In the case of light output 3, the temperature of LED chip 1 is about 20°C upstream of the refrigerant, but about 32°C downstream of the refrigerant. Therefore, the average temperature of all LED chips 1 is about 26°C.

[0023] As shown in Figure 3, when the light emission levels 1 to 3 are changed, the temperature of the LED chip 1 changes significantly, especially downstream. When the light source device 10 is applied to, for example, an exposure apparatus, it is necessary to keep the fluctuation in the peak wavelength of the exposure light within approximately 2 nm. In order to keep the fluctuation in the peak wavelength of the exposure light within approximately 2 nm, the difference in the average temperature of all LED chips 1 between different light emission levels (hereinafter sometimes referred to as the "allowable temperature difference") must be within approximately 15°C. In Figure 3, the difference in average temperature between light emission level 1 (50°C) and light emission level 3 (26°C) is 24°C, which exceeds the allowable temperature difference of 15°C, resulting in a fluctuation in the peak wavelength of the exposure light of 2 nm or more.

[0024] This embodiment describes a method for controlling the current flowing through a light source device 10 that can reduce fluctuations in the peak wavelength of light emitted from an LED module when the light output of the LED module is changed. In the light source device 10 of this embodiment, a chip row 2 through which current flows is selected based on the light output. That is, based on the light output, the ratio of the number of chip rows through which current flows and the number of chip rows through which current does not flow, relative to the total number of chip rows of the LED module 3, is determined.

[0025] Furthermore, the LED module 3 may take the form of, for example, a configuration in which a large number of individually current-controllable LED chips are arranged in a matrix. In that case, the ratio of the number of LED chips that conduct current to the number of LED chips that do not conduct current, relative to the total number of LED chips, may be determined.

[0026] Figure 4 shows the method of lighting the LED chip 1 in this embodiment. Figure 4(a) shows the lighting method for light emission amount 1 (second light emission amount). In Figure 4(a), the current control unit 9 controls the power supply 4 so that the same magnitude (current value) of current flows through all six chip rows 2 enclosed by the dotted line (i.e., through all LED chips).

[0027] Figure 4(b) shows the lighting method for light output level 2 (50% of light output level 1, the first light output level). The current control unit 9 controls the power supply 4 so that the same amount of current flows to only three of the six chip rows 2 (i.e., only half of the LED chips in total). At this time, the same current value that flowed to the six chip rows in Figure 4(a) is flowed to the three chip rows enclosed by the dotted line. In other words, in the case of the first light output level, the current control unit 9 controls the LED chips other than those that are to be made to emit light by flowing a current greater than a predetermined current value so that no current flows to them.

[0028] Figure 4(c) shows the lighting method for light output level 3 (33% of light output level 1). The current control unit 9 controls the power supply 4 so that current flows only to the two chip rows enclosed by the dotted line out of the six chip rows 2. At this time, the same current value that flowed through the six chip rows in Figure 4(a) is flowed through the two chip rows.

[0029] Figure 5 is a conceptual diagram showing the temperature of LED chip 1 when the number of chip rows through which current flows is changed according to the light emission level. The graph in Figure 5, similar to Figure 3, shows the relationship between the position and temperature of LED chip 1 when LED chip 1 is lit at three different light emission levels 1 to 3. The diagram at the top of the graph in Figure 5 is a cross-sectional view of the light source device 10, showing that the position of the LED chip 1 corresponds to the horizontal axis of the graph. To light up the LED chip 1 to a light output of 1, a current of 1A should be passed through all LED chips 1. To light up the LED chip 1 to a light output of 2, which is 50% of light output of 1, a current of 1A should be passed through three of the six chip rows 2, as shown in Figure 4(b), and no current should be passed through the remaining chip rows. To light up the LED chip 1 to a light output of 3, which is 33% of light output of 1, a current of 1A should be passed through two of the chip rows 2, and no current should be passed through the remaining chip rows.

[0030] In Figure 4(a), the temperature of LED chip 1 is approximately 20°C upstream of the refrigerant, but approximately 80°C downstream of the refrigerant. The average temperature of all lit LED chips 1 is approximately 50°C. In Figure 4(b), the temperature of LED chip 1 is approximately 20°C upstream of the refrigerant, but approximately 76°C downstream of the refrigerant. The average temperature of all lit LED chips 1 is approximately 48°C. In the case of light output 2, the temperature of LED chip 1 is approximately 20°C upstream of the refrigerant, but approximately 68°C downstream of the refrigerant. The average temperature of all lit LED chips 1 is approximately 44°C.

[0031] In Figures 4(b) and 4(c), the reason the temperature of the highest-temperature LED chip is lower compared to Figure 4(a) is that the heat from the refrigerant spreads in a direction perpendicular to the direction of refrigerant flow (perpendicular to the plane of the paper in the cross-sectional view of Figure 3). In some chip rows, LED chip 1 is not lit, so although there is some temperature variation downstream of the refrigerant depending on the amount of light emitted, it does not result in a large temperature variation as shown in Figure 3.

[0032] As described above, when the light source device 10 is applied to the exposure apparatus, the allowable range of change in the average temperature of all lit LED chips 1 is about 15°C. In this embodiment, the difference between the average temperature of light emission amount 1 (50°C) and the average temperature of light emission amount 3 (44°C) is 6°C, so the average temperature difference is smaller than the allowable temperature difference. Therefore, fluctuations in the peak wavelength of light from the LED module 3 can be suppressed to 2 nm or less.

[0033] Next, in the light source device 10 of this embodiment, two methods will be described for determining which chip rows to supply current to, after determining the ratio of the number of chip rows that supply current to current to the number of chip rows that do not supply current to the total number of chip rows.

[0034] The first method involves determining which LED chip row to supply current to by comparing the cumulative lighting times. By lighting all LED chip rows so that the cumulative lighting time is approximately the same, the lifespan of the light source device 10 can be extended. Therefore, it is desirable for the current control unit 9 to control the current to flow to the first chip row of the LED module 3, and to control the current not to flow to the second chip row in the LED module 3, which has a longer cumulative lighting time than the first chip row. In other words, the current control unit 9 determines which chip row 2 to supply a current greater than a predetermined current value, prioritizing the chip row with the shortest cumulative lighting time among the multiple chip rows 2. Furthermore, in the case of a configuration in which many LED chips, each capable of individual current control, are arranged in a matrix, the current control unit 9 determines which LED chip 1 to supply a current greater than a predetermined current value, prioritizing the LED chip with the shortest cumulative lighting time among the multiple LED chips 1.

[0035] The second method involves determining which chip array 2 to supply current to by considering the centroid position of all the LED chips 1 to be lit. This centroid position of the LED chips 1 is obtained by weighting it with the light emission amount of each LED chip 1 to be lit, and is calculated based on the product of the light emission amount of the LED chip and the position coordinate of the LED chip. By ensuring that the centroid position of all the LED chips 1 to be lit is always near the center of the LED module 3, regardless of changes in the light emission amount of the LED module 3, fluctuations in lighting conditions such as the illuminance distribution for the illuminated object, such as a mask, can be reduced. For example, when a light source device 10 is applied to an exposure apparatus, the light intensity distribution is not uniform within the light-emitting surface (the surface in which the LED chips are arranged in two dimensions). Therefore, in an exposure apparatus, an integrator optical system is provided in the illumination optical system that illuminates the surface on which the circuit pattern of the mask is formed by light from the light source (hereinafter referred to as the mask pattern surface) or the virtual surface on which the mask pattern surface should be placed, in order to uniformize the illuminance distribution. Ideally, the light that passes through the integrator optical system becomes light with a uniform illuminance distribution. However, if there is a large bias in the illuminance distribution of the light incident on the integrator optical system, even if light from the light source device 10 is irradiated onto the mask via the integrator optical system, the illuminance distribution on the mask may not be very uniform. In particular, if the center of gravity of the multiple LED chips that are lit is biased towards a position close to the edge of the LED module, the illuminance distribution may not be very uniform.

[0036] Therefore, it is desirable for the current control unit 9 to control the center of gravity of the illuminated LED chips (one or more chips) among all the LED chips 1 of the LED module 3 so that it matches the center of gravity when all the LED chips are illuminated at the same brightness. In this embodiment, this center of gravity is aligned with the optical axis of the illumination optical system.

[0037] Furthermore, in this embodiment, an example was described in which the current flowing through some chip rows is reduced to zero when the light emission level is 2 (first light emission level), but the method of current control is not limited to this. For example, the number of LED chips that emit light by flowing a current of a predetermined value or more when the light emission level is 2 (first number) may be less than the number of LED chips that emit light by flowing a current of a predetermined value or more when the light emission level is 1 (second light emission level) (second number). In other words, when the light emission level is 2 (first light emission level), it is not necessary to completely reduce the current flowing through some chip rows (the chip rows indicated as OFF in Figure 4(b)), and a current lower than a predetermined current value may flow.

[0038] The predetermined current value mentioned above is, for example, half the average value of the current flowing through all LED chips lit at a light output of 1 (second light output). Furthermore, it is more preferable that the predetermined current value is 1 / 10 of the average value of the current flowing through all LED chips lit at a light output of 1 (second light output). This is because it is preferable that the current values ​​flowing through LED chips other than the first number of LED chips are close to zero, so that the amount of light emitted from the LED module 3 with a peak wavelength within the allowable range does not deviate significantly from the target light output.

[0039] Furthermore, in this embodiment, when the LED module 3 is lit with the first and second light emission levels, it is preferable to supply approximately the same current to multiple LED chips (LED chips that supply a current higher than a predetermined current value) that are used to light them. By supplying approximately the same current, it is possible to reduce the temperature change (temperature difference) caused by the difference in light emission levels between different LED chips, so it is preferable that the light emission levels between different chips are within a predetermined value (for example, within 20%). That is, the difference between the maximum and minimum current values ​​among the first number of LED chips is within 20% of the maximum current value, or the first current values ​​among the first number of LED chips are the same. Also, the difference between the maximum and minimum current values ​​among the second number of LED chips is within 20% of the maximum current value, or the second current values ​​among the second number of LED chips are the same.

[0040] Alternatively, the difference between the average current value of a first number of LED chips and the average current value of a second number of LED chips should be within 20% of the larger of the two average current values. It is more preferable that it be within 10%. The difference between the average current values ​​of the first and second sets of currents may be the same for both sets of currents.

[0041] Based on the above, in this embodiment, fluctuations in the peak wavelength of light from the LED module 3 due to temperature changes of the LED chip caused by changes in the amount of light emitted can be kept within an acceptable range. The acceptable range of fluctuations in the peak wavelength of light will be explained in the embodiment of the exposure apparatus described later.

[0042] <Second Embodiment> In the first embodiment, an example was described in which the cooler 12 has one flow path 13. In this embodiment, an example is described in which the cooler 12 has multiple flow paths 13. The configuration of the LED module 3 is the same as in the first embodiment, so its description is omitted. Furthermore, matters not mentioned in this embodiment follow those of the first embodiment.

[0043] Figure 6 is a schematic diagram showing the configuration of the cooler 12 in this embodiment. The cooler 12 is equipped with a partition 14. The partition 14 forms a plurality of channels, including a first channel 13a and a second channel 13b through which the refrigerant flows. The plurality of channels are provided corresponding to the positions of each chip row of the LED module 3.

[0044] Refrigerant is supplied to these multiple channels from the temperature controller 5 through piping 6 and a pipe splitter (not shown) which is branched into multiple channels. The refrigerant that has passed through the multiple channels is combined into a single pipe by a manifold (not shown) located downstream, and returns to the temperature controller 5 through piping 6, where it is cooled again.

[0045] In Figure 6, the first channel 13a is formed corresponding to the position of the first chip row, and the second channel 13b is formed corresponding to the position of the second chip row. However, it is not necessarily the case that one chip row corresponds to one channel. For example, the first channel 13a and the second channel 13b may be formed across multiple chip rows.

[0046] In this embodiment, the spread of heat perpendicular to the direction of refrigerant flow can be suppressed. Therefore, it is advantageous in that the change in the temperature distribution of the LED shown in Figure 5 can be further reduced. This embodiment, as described above, can also suppress fluctuations in the peak wavelength of light from the LED module 3 of the device 10 caused by changes in the amount of light emitted.

[0047] <Third Embodiment> In the first embodiment, an example was described in which the LED module 3 has one circuit board 11. In this embodiment, an example is described in which the LED module 3 has multiple circuit boards 11. Matters not mentioned in this embodiment will follow those of the first embodiment.

[0048] Figure 7 shows the configuration of the LED module 3 in this embodiment. In this embodiment, ten circuit boards, from COB1 to COB10, are mounted on the housing of the light source device or on a support board inside the housing. Each COB has eight chip arrays mounted on it, and each chip array has 15 LED chips arranged in a single row. Each power supply corresponding to each COB supplies current to each COB, and the configuration allows for control of light emission on a COB-by-COB basis (circuit board-by-circuit board basis). In addition, each COB is equipped with a corresponding cooler, and a coolant flows through the cooler's channel at a constant flow rate.

[0049] When changing the target illuminance or target light output, the number of COBs to be lit and the current value are controlled. For example, when the light output is 100% (second light output), a current of 1A is set to flow through all chip rows of all COBs. When the light output is 50% (first light output), a current of 1A is set to flow through all chip rows of 5 of the 10 COBs. In other words, only 5 COBs are lit. For example, COB1, COB7, COB3, COB9, and COB5 are lit, and the other COBs are turned off. The lit COBs do not experience temperature changes (or the changes are sufficiently small) compared to when the light output is 100%. Therefore, it is possible to suppress (keep within an acceptable range) fluctuations in the peak wavelength of light from the LED module 3 of the device 10 caused by the change in light output.

[0050] Furthermore, simply deciding whether or not to selectively light up the COBs may not be sufficient to achieve the desired light output. For example, if the light output of LED module 3, which has 10 COBs, is 75%, lighting up 7 COBs with a current of 1A through all chip rows will result in a light output below the required level, while lighting up 8 COBs with a current of 1A through all chip rows will result in a light output above the required level. In such cases, the current value flowing through all chip rows of these 8 COBs can be adjusted to achieve the desired light output.

[0051] If the required light output is 75%, for example, this can be achieved by lighting up eight COBs and reducing the current flowing through each chip row to 75 / 80A (approximately 0.94A). In this case, the temperature of the LED chips being lit must be adjusted to within an acceptable range. That is, the temperature of the LED chips being lit will decrease in accordance with the decrease in the current flowing through each chip row, but there is no problem as long as the temperature decrease is within an acceptable range.

[0052] In this embodiment, the groups to be lit are defined as each COB, but even in a light source device having multiple COBs, the current may be controlled on a chip array basis or on a unit of multiple chip arrays grouped together.

[0053] Figure 8 illustrates an example of controlling the illumination of each chip row in a light source device 10 having multiple COBs. The light source device 10 in Figure 8 is similar to the light source device 10 described in Figure 7, with the LED module 3 having 10 COBs, and each COB having chip rows S1 to S80 mounted on it. The LED chips 1 that light up according to the amount of light emitted, the temperature change of each LED chip before and after changing the amount of light emitted, and the amount of variation in the peak wavelength of light from the LED module 3 are the same as in the light source device 10 described in Figure 7.

[0054] Furthermore, this embodiment is an example in which the current flowing through some COBs (or some chip arrays) is reduced to zero in the case of the first light emission level, but it is not limited to this. For example, the number of LED chips that emit light by flowing a current of a predetermined value or more in the case of light emission level 2 (first light emission level) is less than the number of LED chips that emit light by flowing a current of a predetermined value or more in the case of light emission level 1 (second light emission level). In other words, in the case of light emission level 2 (first light emission level), it is not necessary to completely reduce the current flowing through some COBs (or some chip arrays), and a current smaller than the predetermined current value may flow.

[0055] Based on the above, this embodiment makes it possible to suppress fluctuations in the peak wavelength of light from the LED module caused by changes in the amount of light emitted.

[0056] <Fourth Embodiment> In the first embodiment, an example was described in which the current value supplied to the chip rows being lit was not changed when the ratio of the number of chip rows to which current is supplied according to the amount of light emitted was changed relative to the total number of chip rows. In this embodiment, an example is described in which the current value supplied to the chip rows is appropriately changed when the ratio of the number of chip rows to which current is supplied according to the amount of light emitted is changed relative to the total number of chip rows. The configuration of the light source device 10 is the same as in the first embodiment, so its description is omitted. Furthermore, matters not mentioned in this embodiment follow those of the first embodiment.

[0057] In this embodiment, when reducing the light emission level from level 1 to level 2, the current control unit 9 prevents current from flowing to some LED chip rows in response to the change in light emission level, and also increases the current value of the current flowing to the LED chip rows that are lit. This further reduces the temperature change of the LED chips that occurred in response to the change in light emission level.

[0058] Figure 9 is a conceptual diagram showing the temperature of LED chip 1 when the number of LED chip rows lit according to the light emission amount and the current value of the current flowing through the lit LED chip rows are changed in this embodiment. The graph in Figure 9, similar to the graph in Figure 5, shows the relationship between the position and temperature of LED chip 1 when the LED chip row 2 is lit at three different light emission amounts 1 to 3. The diagram shown at the top of the graph in Figure 9 is a cross-sectional view of the light source device 10, showing that the position of LED chip 1 corresponds to the horizontal axis of the graph. In order to light up the LED chip row 2 to a light emission amount of 1, a current of 1A should be flowed through all of the LED chip row 2.

[0059] In order to light up the LED chip array 2 to a light output 2 which is 50% of the light output 1, in the first embodiment, current was flowed through three LED chip arrays 2. However, in this embodiment, the current control unit 9 controls the current to flow through two LED chip arrays 2. If the number of chip arrays to which current flows is reduced to two, the light output will be less than the required light output 2 for the LED module 3 if the current value flowing through the chip array 2 remains at 1A. Therefore, the current value flowing through the chip array to be lit is increased from 1A to 1.5A.

[0060] Similarly, in order to light up the LED chip array 2 to a light output of 3, which is 33% of the light output of 1, in the first embodiment, current was flowed through two chip arrays. However, in this embodiment, the current control unit 9 controls the current to flow through only one chip array. Since using only one chip array would result in a light output below the required level, if there is sufficient current available for the chip array to be lit, the current value should be increased from 1A to 2A.

[0061] In the first embodiment, when the light emission level was changed from level 1 to levels 2 or 3, the temperature of the lit LED chips decreased as the number of lit LED chips was reduced. Therefore, in this embodiment, by reducing the number of chip rows through which current flows and increasing the current value, the amount of heat generated by the lit LED chips is increased, and as a result, the temperature change of the LED chips becomes smaller than in the first embodiment. The number of chip rows through which current flows and the current value are not limited to the above example, and appropriate values ​​will vary depending on factors such as the rate at which the coolant flows, so they may be set as appropriate.

[0062] Based on the above, this embodiment makes it possible to suppress fluctuations in the peak wavelength from the LED module caused by changes in the amount of light emitted.

[0063] <Embodiment of an exposure apparatus> In this embodiment, an example of an exposure apparatus equipped with a light source device 10 according to any of the first to fourth embodiments described above will be explained. The configuration of the light source device 10 is the same as that of any of the first to fourth embodiments, so a detailed explanation will be omitted.

[0064] Figure 10 is a schematic diagram showing the configuration of the exposure apparatus 100 of this embodiment. The exposure apparatus 100 is used in the lithography process when manufacturing semiconductor devices and devices such as flat panel displays (FPDs), and transfers the pattern of a mask (master plate) to a substrate coated with resist (photosensitive material). In this way, the exposure apparatus 100 forms a latent image pattern on the resist on the substrate. In this embodiment, a step-and-scan type exposure apparatus is described, but the light source apparatus of the first to fourth embodiments can also be applied to exposure apparatuses of other exposure methods such as the step-and-repeat method.

[0065] The exposure apparatus 100 includes an illumination optical system 101 for illuminating the mask M, a mask stage 102, a projection optical system 103 for projecting the pattern of the mask M onto the substrate W, a substrate stage 104, and a main control unit 105. The projection optical system 103 is a reflective projection optical system combining a concave mirror, a convex mirror, and a trapezoidal mirror, but other types of optical systems can also be used as described later.

[0066] The illumination optical system 101 illuminates the mask M with light from the light source device 10. The mask M has a pattern formed on it that corresponds to the pattern to be formed on the substrate W. The mask M is held on the mask stage 102, and the substrate W is held on the substrate stage 104. The illumination optical system 101 consists of a first condenser lens group 106, an optical integrator 107 equipped with a fly-eye lens group and a lenticular lens group, a second condenser lens group 108, etc. With this configuration, even if the light intensity distribution from the light source device 10 is non-uniform, a uniform illuminance distribution can be obtained on the patterned surface (the surface on which the pattern is formed) of the mask M held on the stage 102.

[0067] The main control unit 105 controls various parts of the exposure apparatus 100. For example, the main control unit 105 controls the amount of light emitted from the light source device 10 and the driving of the mask stage 102 and the substrate stage 104.

[0068] The pattern surface of the mask M and the resist on the substrate W are positioned at approximately conjugate optical locations via the projection optical system 103. The projection optical system 103 can be a reflective projection optical system (which may include lenses for aberration correction), a refractive projection optical system with multiple lenses, or a reflective-refracting projection optical system with multiple lenses and a concave mirror. In this embodiment, the projection optical system 103 has a predetermined projection magnification and projects a portion of the circuit pattern formed on the mask M onto the substrate W. The mask stage 102 and the substrate stage 104 are scanned in a direction parallel to the object plane of the projection optical system 103 at a speed ratio corresponding to the projection magnification of the projection optical system 103. This allows the entire circuit pattern formed on the mask M to be transferred to the substrate W.

[0069] The resist applied to the substrate W has different sensitivities depending on the wavelength of the exposure light. Therefore, if the wavelength suitable for the photosensitive resist differs from the peak wavelength of the light from the light source device 10 (i.e., there is variation in the peak wavelength of the exposure light from the light source device 10), it will affect the results obtained in the subsequent development process. When there is variation in the peak wavelength of the exposure light, the line width of the resist pattern obtained by development changes, resulting in a line width error. For example, if the variation in the peak wavelength is within 2 nm (±1 nm), the line width error will remain within the standard range, but if the variation in the peak wavelength is greater than 2 nm, it may not remain within the standard range. Therefore, it is necessary to suppress the variation in the peak wavelength of the light from the light source device 10.

[0070] The light source device 10 of the first to fourth embodiments can provide an exposure apparatus 100 that can keep fluctuations in the peak wavelength of light from the LED module caused by changes in the amount of light emitted within an acceptable range.

[0071] Furthermore, although this embodiment has been described assuming that an LED chip emitting light at a specific peak wavelength (for example, one of 365 nm, 405 nm, or 436 nm) is used as the light source, it is not limited to this. For example, the substrate may be exposed using a two-wavelength composite exposure light obtained by combining light from two types of LED chips with different peak wavelengths. By using a two-wavelength composite exposure light, the amount of light from the exposure light, i.e., the illuminance on the substrate to be exposed, can be improved.

[0072] One example of a combination of two types of LED chips is a combination of a first LED emitting light with a peak wavelength of 365 nm and a second LED emitting light with a peak wavelength of 405 nm. When using this combination, the LED module can be configured to have either a first group of LEDs and a second group of LEDs, or a first LED module with a first group of LEDs and a second LED with a second group of LEDs. Even in such a two-wavelength synthesis case, by controlling the current of the light source device 10 so that the peak wavelength of the light from each LED chip does not fluctuate, the error in the line width of the resist pattern obtained after development can be reduced. Alternatively, a configuration using three-wavelength composite exposure light, which is a composite of light from three or more types of LED chips with different peak wavelengths, is also possible. As an example of combining two wavelengths of light, a dichroic mirror that reflects light with a peak wavelength of 365 nm and transmits light with a peak wavelength of 405 nm can be used to combine light of different wavelengths.

[0073] Furthermore, in the first to fourth embodiments, a light source device 10 capable of reducing wavelength fluctuations when the light emission amount is changed in three stages: 100%, 50%, and 33%, was described. When this light source device 10 is applied to an exposure apparatus 100, the light emission amount can be changed according to the exposure target. For example, the manufacturing of transparent electrode films (Indium Tin Oxide: ITO) is a process that requires high-intensity exposure. When the light emission amount of the light source required for ITO manufacturing is 100%, the light emission amount of the light source required for other processes is about 70%. The light source device 10 in this embodiment can suppress wavelength fluctuations that may occur when the light emission amount is changed from 100% to 70%.

[0074] Furthermore, when applying the light source device 10 described in the first to fourth embodiments to the exposure apparatus 100, it is required to achieve a high light emission amount from the light of a large number of LED chips. For example, it is required to achieve a light emission amount comparable to that when a mercury lamp is used as the light source for the exposure apparatus. However, the light emission amount of each individual LED chip is very small compared to the light emission amount of a mercury lamp. Therefore, in the light source device 10 of this embodiment, it is preferable that, for example, 150 or more LED chips are mounted on a single circuit board. More preferably, as the light source device 10 of this embodiment, it is preferable that multiple circuit boards (for example, 6 or more) with 150 or more LEDs mounted on them are configured, as shown in Figure 7.

[0075] <Embodiment for manufacturing an article> A method for manufacturing an article according to an embodiment of the present invention is suitable, for example, for manufacturing a flat panel display (FPD). The method for manufacturing an article according to this embodiment includes the steps of: forming a latent image pattern on a photosensitive agent coated on a substrate by exposure using the above-mentioned exposure apparatus 100 to obtain an exposure substrate (exposure step); and developing the exposure substrate on which the latent image pattern was formed in the above step to obtain a developed substrate (development step). Furthermore, this manufacturing method includes other well-known steps (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The method for manufacturing an article according to this embodiment is advantageous over conventional methods in at least one of the performance, quality, productivity, and production cost of the article.

[0076] Although preferred embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to these embodiments, and various modifications and changes are possible within the scope of its essence. [Explanation of symbols]

[0077] 1 LED chip (LED) 2 chip rows 3 LED modules 7 Control Unit 8 Acquisition Department 9. Current control unit (light intensity changing unit) 10. Light source device 11 circuit board 12 Cooler

Claims

1. A light source device comprising an LED module having multiple LEDs arranged in a row, and a cooler for cooling the LED module, wherein the amount of light emitted by the LED module is variable, The aforementioned LED module comprises multiple chip rows, each containing multiple LEDs arranged in a specific configuration. The system includes a current control unit that controls the current for each chip row of the plurality of chip rows, The current control unit, The number of chip arrays that emit light by flowing a current of a predetermined value or more when the amount of light emitted is a first amount of light emitted is determined to be less than the number of chip arrays that emit light by flowing a current of a predetermined value or more when the amount of light emitted is a second amount of light emitted which is greater than the first amount of light emitted. For chip arrays other than those that emit light by flowing a current greater than or equal to the predetermined current value, the current flowing to them is controlled to be less than the predetermined current value (excluding no current flow). A light source device characterized by the following features.

2. The light source device according to claim 1, characterized in that the direction in which the multiple LEDs are arranged in each of the multiple chip rows includes a component parallel to the direction in which the coolant flows in the cooler.

3. The light source device according to claim 2, characterized in that the direction in which the plurality of LEDs are arranged in the chip row is at an angle of 45 degrees or less with respect to the direction in which the refrigerant flows.

4. The current control unit, When the amount of light emitted is the first amount of light emitted, a current of a first current value equal to or greater than the predetermined current value is passed through a first number of chip arrays, and when the amount of light emitted is the second amount of light emitted, a current of a second current value equal to or greater than the predetermined current value is passed through a second number of chip arrays greater than the first number, The average value of the first current in the first number of chip rows and the average value of the second current in the second number of chip rows are equal to each other, or the difference between the average value of the first current and the average value of the second current is within 20% of the larger of the two average values. A light source device characterized by controlling the current value for the plurality of chip rows.

5. The current control unit, When the amount of light emitted is the first amount of light emitted, a current of a first current value equal to or greater than the predetermined current value is passed through a first number of chip arrays, and when the amount of light emitted is the second amount of light emitted, a current of a second current value equal to or greater than the predetermined current value is passed through a second number of chip arrays greater than the first number, The average value of the first current in the first number of chip rows and the average value of the second current in the second number of chip rows are the same, or the difference between the average value of the first current and the average value of the second current is within 10% of the larger of the two average values. The light source device according to claim 4, characterized in that it controls the current value for the plurality of chip rows.

6. The current control unit, When the amount of light emitted is the first amount of light emitted, a current of a first current value equal to or greater than the predetermined current value is passed through a first number of chip arrays, and when the amount of light emitted is the second amount of light emitted, a current of a second current value equal to or greater than the predetermined current value is passed through a second number of chip arrays greater than the first number, The difference between the maximum and minimum current values ​​among the first number of chip arrays is within 20% of the maximum current value, or the first current values ​​for the first number of chip arrays are the same among the first number of chip arrays. The difference between the maximum and minimum current values ​​among the second number of chip arrays is within 20% of the maximum current value, or the second current values ​​among the second number of chip arrays are the same. The light source device according to claim 4 or 5, characterized in that it controls the current value for the plurality of chip rows.

7. The light source device according to any one of claims 1 to 3, characterized in that the predetermined current value is half the average value of the current flowing through the plurality of chip rows that emit light when the LED module emits light at the second amount of light.

8. The light source device according to any one of claims 1 to 7, characterized in that the current control unit controls the current flowing through the plurality of chip rows so as to reduce the change in the peak wavelength of light emitted from the LED module due to the change from the second light emission amount to the first light emission amount.

9. The light source device according to any one of claims 1 to 7, characterized in that when the current control unit changes from the second light emission amount to the first light emission amount, it controls the current flowing to the chip row that emits light by flowing a current greater than the predetermined current value when the first light emission amount is set, in order to reduce the change in average temperature associated with the change in the light emission amount of the chip row among the plurality of chip rows that emits light by flowing a current greater than the predetermined current value when the first light emission amount is set.

10. The light source device according to any one of claims 1 to 7, characterized in that the current control unit determines, preferentially, which of the plurality of chip rows will carry a current greater than the predetermined current value, starting with the chip row with the shortest cumulative lighting time.

11. The cooler includes partitions that form multiple passages through which the refrigerant flows, The light source device according to any one of claims 1 to 10, characterized in that the partition is provided such that the plurality of flow paths correspond to the respective positions of the plurality of chip rows.

12. The LED module comprises multiple circuit boards, each having a chip array in which multiple LEDs are arranged. The light source device according to any one of claims 1 to 11, characterized in that the current control unit performs current control on a circuit board basis for the plurality of chip rows of the plurality of circuit boards based on the magnitude of the amount of light emitted.

13. An exposure apparatus characterized by projecting a pattern formed on a master plate onto a substrate using light from a light source device according to any one of claims 1 to 12, and exposing the substrate.

14. An exposure step of exposing a substrate using the exposure apparatus described in claim 13 to obtain an exposed substrate, The process includes developing the aforementioned photopolymer substrate to obtain a developed substrate, A method for manufacturing an article, characterized by manufacturing an article from the aforementioned developing substrate.

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