Control method, exposure apparatus, and method for manufacturing article

Abstract

The invention relates to a control method, an exposure apparatus, and a method of manufacturing an article. A control method for controlling the lighting of a first LED and a second LED includes an acquisition step for acquiring the illuminance of each of the first LED and the second LED, and a determination step for determining the value of current flowing to the first LED and the second LED on the basis of the measurement results of the acquisition step. In the determination step, the value of the current flowing to the first LED or the second LED having a small illuminance is determined to be smaller than the value of the current flowing to the other LED.

Description

Technical Field

[0001] This disclosure relates to a control method, an exposure apparatus, and a method for manufacturing an article. Background Technology

[0002] An exposure apparatus is used in the photolithography process, a manufacturing step in semiconductor devices, liquid crystal displays, etc., to transfer the pattern of a master template (mask template or mask) onto a photosensitive substrate (a wafer, glass plate, etc., with a resist layer formed on its surface) via a projection optical system. For example, in projection exposure apparatuses for transferring patterns to liquid crystal displays, there has been a recent demand to expose larger areas of the pattern from the mask onto the substrate. To address this demand, a scanning projection exposure apparatus using a step-scan method has been proposed, capable of achieving high resolution and exposing large images. This scanning exposure apparatus transfers a pattern illuminated by a slit beam onto the substrate via a projection optical system through a scanning motion.

[0003] While mercury lamps are commonly used as light sources in exposure devices, there is a growing expectation in recent years to replace them with light-emitting diodes (LEDs), which are solid-state light-emitting elements. LEDs have a shorter time frame from the flow of current to the substrate circuitry controlling light emission until the light output stabilizes, unlike mercury lamps which require continuous illumination. Therefore, they offer advantages such as energy efficiency and long lifespan. International Publication No. 2019 / 229971 discloses a method for reducing overall brightness uniformity by adjusting the brightness of each LED according to its degree of degradation. Summary of the Invention

[0004] The problem that the invention aims to solve

[0005] However, when adjusting the brightness to reduce overall brightness unevenness, a large amount of current needs to flow through LEDs with high degradation levels, which may increase the divergence in degradation levels among multiple LEDs.

[0006] Therefore, the purpose of this disclosure is to provide an advantageous control method for controlling the lighting of LEDs.

[0007] Technical solutions for solving the problem

[0008] To achieve the above objectives, one aspect of the control method disclosed herein is a control method for controlling the illumination of a first LED and a second LED. The control method is characterized by including a step of obtaining the illuminance of each of the first LED and the second LED, and a step of determining the current values ​​flowing to the first LED and the second LED based on the measurement results of the obtaining step. The determining step determines that the current value flowing to the LED with the lower illuminance among the first LED and the second LED is less than the current value flowing to the other LED.

[0009] Further features of this disclosure will become apparent from the following description of exemplary embodiments (with reference to the accompanying drawings). Attached Figure Description

[0010] Figure 1 This is a schematic diagram showing the structure of the exposure apparatus.

[0011] Figure 2 This is a schematic diagram showing the structure of an LED array.

[0012] Figure 3 This is a schematic diagram showing the structure of the variable slit.

[0013] Figure 4 This is a flowchart of the control method in the first embodiment.

[0014] Figure 5 This is a graph showing information about illuminance degradation.

[0015] Figure 6 This is a graph showing information about illuminance degradation.

[0016] Figure 7 This is a flowchart of the control method in the second embodiment.

[0017] Figure 8 This is a diagram showing the brightness distribution in the second embodiment.

[0018] Figure 9 It is a flowchart of the manufacturing process of the item. Detailed Implementation

[0019] Preferred embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. Furthermore, in the drawings, the same reference numerals are used for the same components, and repeated descriptions are omitted.

[0020] <First Embodiment>

[0021] Reference Figure 1 This describes the exposure apparatus 100 of this embodiment. Figure 1This diagram illustrates the exposure apparatus 100 of this embodiment. The exposure apparatus 100 of this embodiment is a scanning type exposure apparatus using a step-scan method to scan and expose a substrate with slit light. It includes an illumination optical system 1, an alignment observation instrument 2, a projection optical system 4, a substrate stage 11, and a control unit 20. Furthermore, the original plate 3 is held by the original plate stage 30 and positioned between the alignment observation instrument 2 and the projection optical system 4, while the substrate 10 is held by the substrate stage 11.

[0022] The control unit 20 includes a CPU and a memory, and controls the entire exposure apparatus 100 (each part of the exposure apparatus 100). In addition, the exposure apparatus 100 may not be in a step-scan mode, but in a step-repeat mode.

[0023] The illumination optical system 1 may include an LED array 13, a first compound eye lens 14a, a first condenser lens 15a, a second compound eye lens 14b, a plane mirror 16, a second condenser lens 15b, an illuminance sensor 17 (acquisition unit), a variable slit 18, and an imaging optical system 19. Light emitted from the LED array 13 passes through the first compound eye lens 14a, the first condenser lens 15a, and the second compound eye lens 14b, and its optical path is bent by the plane mirror 16. Then, it illuminates the variable slit 18 with uniform light intensity via the second condenser lens 15b, and after passing through the variable slit, it enters the imaging optical system 19.

[0024] exist Figure 2 The structure of the LED array 13 is shown in detail. The LED array 13 is formed by arranging multiple LED chips 31 in series in a direction orthogonal to the X-axis, forming a chip column. The chip column is as follows... Figure 3 As shown in 13A to 13G, multiple LEDs are arranged in the X direction. LED driver units 13a to 13g are connected to each chip array, and the LED driver units are connected via... Figure 1 The current flowing to the LED chip 31 is controlled by a signal from the lamp control unit 21. Chip rows 13A to 13G are mounted on separate electrical boards, allowing for replacement of each chip row if replacement is needed due to LED chip 31 failure or deterioration. Cooling of the LED chip 31 is achieved by a cooler (not shown).

[0025] Illuminance sensor 17 measures a portion of the light illuminating the variable slit 18. Illuminance sensor 17 is calibrated by a sensor (not shown) configured at the substrate stage 11, which in this embodiment serves as an illuminance monitor for the light illuminating the substrate 10. The variable slit 18 defines the illumination range of the original 3. Imaging optics system 19 is configured to illuminate the object plane (original 3) of projection optics system 4 with the slit light defined by the variable slit 18. Furthermore, alignment observer 2 simultaneously detects the alignment marks of the original 3 and the alignment marks of the substrate 10 via projection optics system 4.

[0026] The projection optical system 4 is configured to include a first parallel plate 5a, a second parallel plate 5b, a first plane mirror 6, a second plane mirror 7, a convex mirror 8, and a concave mirror 9, and projects an image of the pattern of the original plate 3, illuminated by the illumination optical system 1, onto the substrate 10. The original plate 3 is disposed on the object plane of the projection optical system 4, and the substrate 10 is disposed on the image plane of the projection optical system 4. The projection optical system 4 can be configured as any of a constant magnification imaging optical system, a magnifying imaging optical system, and a reducing imaging optical system, but in the exposure apparatus 100 of the first embodiment, it is configured as a constant magnification optical system. Slit light passing through the original plate 3 illuminates the substrate 10 through the first parallel plate 5a, the first plane mirror 6, the first surface 9a of the concave mirror 9, the convex mirror 8, the second surface 9b of the concave mirror 9, the second plane mirror 7, and the second parallel plate 5b. Then, by scanning the original 3 and the substrate 10 in a direction parallel to the substrate surface (scanning direction (Y direction in this embodiment)) at a speed ratio corresponding to the projection magnification of the projection optical system 4, the pattern of the original 3 can be transferred to the substrate 10.

[0027] The control unit 20 includes a lamp control unit 21 and a variable slit control unit 22. The lamp control unit 21 acquires the measurement value from the illuminance sensor 17 and instructs the LED driving units 13a-13g of the LED array 13 to achieve the desired illuminance. The variable slit control unit 22 controls the LEDs configured at the variable slit 18. Figure 3 The drive mechanism 18c operates to control the shape of the irradiation area so that the irradiation area defined by the variable slit 18 becomes the desired shape. Before scanning exposure, the control unit 20 generates an illuminance distribution and a variable slit drive distribution corresponding to the position of the substrate 10. When scanning exposure begins, the lamp control unit 21 controls the illuminance according to the illuminance distribution in sync with the drive of the substrate stage 11, and the variable slit control unit 22 controls the irradiation area according to the drive distribution.

[0028] Next, we will describe the degradation rate (illuminance degradation rate) of the LED array. The degradation rate represents the rate of decrease in illuminance from the initial stage of use when the LED array is lit with a specific drive current. The relationship between the degradation rate and cumulative lighting time is not constant due to fluctuations in LED chip manufacturing processes, etc. Figure 5 The image shows an example of how the degradation rate changes relative to the cumulative lighting time. Figure 5 In the diagram, 13A represents the degradation rate of a chip array with slow illuminance degradation relative to cumulative operating time, while 13C represents the degradation rate of a chip array with fast illuminance degradation relative to cumulative operating time. For example, at a degradation rate of 30%, the cumulative operating time of 13A is over 11,000 hours, while that of 13C is approximately 7,500 hours. Figure 5As shown, illuminance degradation fluctuates, therefore the replacement period for the chip array caused by illuminance degradation varies. However, if the exposure apparatus 100 is shut down every time a chip array needs to be replaced, there are adverse effects such as decreased operating efficiency and increased maintenance costs. Therefore, regarding replacements caused by illuminance degradation over time, it is considered best to replace all usable chip arrays at once, including those still usable, when the initial replacement of a particular chip array is required. Therefore, suppressing the degradation rate of the fastest-degrading chip arrays and extending the time from the start of operation to the replacement period of the LED array 13 becomes a challenge.

[0029] Therefore, in this embodiment, by measuring the degradation rate of chip rows 13A to 13G and adjusting the drive current of each chip row based on the results, the degradation rate increase of chip rows with high degradation rates is reduced. According to... Figure 4 The flowchart shown illustrates an example of a control method for lighting a specific LED. Here, it is explained... Figure 5 The adjustment order of the three chip columns 13A, 13B, and 13C with different degradation characteristics is shown, but the adjustment can be performed in the same way even if the number of chip columns to be adjusted increases. In addition, in this embodiment, chip column 13A is also referred to as the first LED, and chip column 13C is also referred to as the second LED. The first LED and the second LED can be a single LED or multiple LEDs (LED group).

[0030] Figure 4 S11 is the first separate illuminance measurement process (reference acquisition process), which measures the initial illuminance of chip columns 13A to 13C at the start time of operation of LED array 13. The timing of S11 is also called the first timing. Lamp control unit 21 instructs LED driver units 13a to 13c to make the driving current ratio of chip columns 13A, 13B, and 13C at the time of initial illuminance measurement 1:1:1. The current value at this time is stored because it will be used in S13. Regarding the measurement, firstly, only chip column 13A is lit, and the illuminance is measured by illuminance sensor 17, and the lamp control unit 21 stores the measurement. Next, the illuminance of chip columns 13B and 13C is measured in the same way.

[0031] S12 performs the normal exposure operation, using the exposure device (lighting process). All chip rows 13A to 13C are lit. Regarding the drive current, the lamp control unit 21 calculates and instructs the LED driver units 13a to 13c based on the target illuminance required for the exposure operation and the measurement value from the illuminance sensor 17. The drive current ratio at this time is set to 1:1:1 immediately after S11, and to the current ratio determined in S15 if it occurs after S15. For example, immediately after S11, to obtain the target illuminance, each chip row is driven with a current value of 1000mA. In this case, when the current ratio is determined to be 1:1:0.98 after S15, chip rows 13A and 13B are driven at approximately 1007mA, and 13C is driven at approximately 987mA.

[0032] Furthermore, in this embodiment, the illumination process is performed by overlapping light from multiple chip columns on the irradiated surface. Therefore, even if there are fluctuations in illuminance between multiple chip columns, these fluctuations will not be a significant issue due to the overlapping of light on the irradiated surface.

[0033] Even if the target illuminance changes during the operation of the exposure apparatus, and the driving current value of the chip array changes accordingly, the driving current ratio of each chip array will still be maintained. In this embodiment, the operation period of S12 is set to 1000 hours. The operation period can be set arbitrarily, or it can be changed each time according to process conditions such as target illuminance, the magnitude of degradation rate, the hourly increase rate of degradation rate, etc. In addition, if there are periods when the exposure apparatus 100 is in standby mode according to the production plan, the processes after S13 can also be performed.

[0034] S13 is the second and subsequent individual illuminance measurement process (acquisition process), where the illuminance of chip rows 13A to 13C is measured individually again using the same method as in S11. The drive current during measurement is set to be the same as that in S11. Because a certain period of time has been used in S12, the illuminance after the reduction from the initial illuminance measured in S11 is measured. The timing of S12 is also called the second timing. The measured value is stored by the lamp control unit 21 each time.

[0035] S14 is the degradation rate calculation step (calculation step). Based on the initial illuminance of chip rows 13A to 13C measured in S11 and the illuminance measured in S13 after a certain period of use, the percentage reduction in illuminance is calculated as the degradation rate of each of chip rows 13A to 13C. That is, based on the measurement results of the reference acquisition step and the acquisition step, the illuminance degradation information of the first LED and the aforementioned second LED is calculated. The illuminance degradation information may include information related to illuminance degradation, such as the illuminance degradation rate.

[0036] S15 is a degradation suppression process (determination process), which determines the drive current ratio for each chip row. Based on the result of S14, the chip row with the highest degradation rate at that time point is determined, so the drive current ratio of the chip row with the highest degradation rate is reduced from the current drive current ratio. That is, the current value flowing to the LED with lower illuminance among the first and second LEDs is determined to be less than the current value flowing to the LED of the other side. More preferably, the current value flowing to the LED with higher illuminance degradation rate among the first and second LEDs is determined to be less than the current value flowing to the LED of the other side.

[0037] For example, if the current drive current ratio is 1:1:1 and the chip row with the highest degradation rate is 13C, it can be changed to 1:1:0.99. The method for changing the drive current ratio can be determined, for example, based on the magnitude of the degradation rate since the last individual illuminance measurement, or, alternatively, by considering the deviation of the degradation rate of each chip row relative to the median; it is not limited to one method. Generally, LEDs degrade more slowly if the drive current is decreased and more quickly if the drive current is increased. Therefore, by changing the drive current ratio as described above, the degradation of the chip row with the highest degradation rate is slowed down, while the degradation of other chip rows is relatively accelerated.

[0038] Furthermore, in this embodiment, the chip array with the highest degradation rate is selected to reduce the drive current. However, two or more chip arrays (LED groups) can also be selected as a selection method. For example, a threshold for the degradation rate can be predetermined, and chip arrays with a degradation rate above the threshold can be selected. Further, regarding the method for selecting chip arrays to maintain or increase the drive current, this embodiment describes a method where the drive current ratio of the chip array with a high degradation rate is reduced, thereby relatively and passively increasing the drive current of the remaining chip arrays. However, this method is not limited to this. For example, one or more chip arrays with low degradation rates can be selected to increase the drive current ratio. If the target illuminance during use can be reduced, the effect of this embodiment can be achieved even if chip arrays with high degradation rates are reduced without selecting chip arrays that increase the drive current.

[0039] By repeatedly performing the sequence S12 to S15, thus Figure 5 The degradation of the chip column 13C shown is, for example, as Figure 6 The degradation process slows down. That is, the acquisition and decision processes are executed multiple times. On the other hand, regarding the chip 13A, which degrades slowly, although the drive current increases relatively after S15, the degradation rate is correspondingly slower. Figure 5 The speed increases, but the maintenance period of LED array 13 depends on the fastest deteriorating chip column, so it will not affect the working efficiency of the exposure device.

[0040] The above methods can provide an exposure device that makes the degradation rate of each chip column relative to the cumulative lighting time as uniform as possible and makes the maintenance interval of the LED array 13 longer than before.

[0041] <Second Implementation>

[0042] In this embodiment, an example using a variable slit 18 will be described regarding the lighting method of the LED array 13, taking into account the brightness distribution of the area (irradiation area) on the substrate 10 illuminated by the slit light. Furthermore, the basic structure of the exposure apparatus 100 is the same as in the first embodiment, so its description is omitted. Additionally, matters not mentioned in this embodiment will be handled according to the first embodiment.

[0043] exist Figure 3 The variable slit 18 is shown in detail. Light that shines on the variable slit 18 passes through the slit opening 18a, thereby shaping the slit opening 18a and affecting... Figure 1 The original version 3 is used for lighting. The variable slit 18 has a drive mechanism 18c consisting of a pulse motor and a ball screw, etc., which is controlled by a source... Figure 1 The variable slit control unit 22 controls the drive mechanism 18c. Driven by the drive mechanism 18c, the opening end 18b formed by the metal plate or the like moves, changing the length (hereinafter referred to as the slit width) of the slit opening 18a in the scanning direction (Y direction in this embodiment). Figure 3 The slits are arranged in a plurality of configurations in the non-scanning direction (X direction in this embodiment), allowing the slit width to be varied for each configuration position. Furthermore, in the exposure apparatus 100 of this embodiment, the shape of the illumination range of the original plate 3 is described as rectangular, but it is not limited to this. The shape of the illumination area after passing through the original plate 3 and the projection optical system 4 becomes the same as the illumination range of the original plate 3. Therefore, the shape of the illumination area on the substrate 10 is equivalent to the variable slit 18 defining the shape of the illumination area. By driving... Figure 3 The variable slit drive mechanism 18c shown is used to change Figure 3 The slit width shown can change the exposure amount of the substrate during scanning exposure.

[0044] However, the brightness distribution in the irradiated area on the substrate 10 in the direction orthogonal to the scanning direction (x-direction in this embodiment) is expected to be uniform. Fluctuations in the brightness distribution affect exposure quality such as circuit linewidth, and depending on the process conditions, fluctuations exceeding a certain percentage can lead to poor exposure. In the exposure apparatus 100, an optical system is provided that uniformizes the intensity of light emitted from the LED array 13 using optical elements 14-16. However, due to the difference in illuminance between each chip row, the light intensity uniformity performance of the optical elements 14-16 is exceeded, affecting the brightness distribution of the irradiated surface on the substrate 10. In this case, as a method to achieve the effects of this disclosure while maintaining exposure quality, Figure 7 The flowchart shown illustrates the method using the variable slit 18.

[0045] Figure 7 S21 to S25 and Figure 4 (In the first embodiment) S11 to S15 are the same. In S26, the brightness distribution of the light-irradiated surface for exposure is measured by a brightness sensor configured on the substrate mounting stage (measurement process). The measurement is performed with all the chip columns 13A to 13G of the LED array 13 lit up according to the current value determined in S25. Figure 8 Examples of measurement results are shown below. Figure 8 The x-coordinate of the surface illuminated by the exposure light and the deviation of the brightness in the x-direction from the average value are shown. The measured width in the x-direction is the same as the width M of the variable slit 18 in the x-direction.

[0046] In step S27, it is determined whether the brightness distribution is within the allowable range. The allowable range is determined based on manufacturing process conditions, etc. For example, if a deviation of +3% or less and -3% or more relative to the average value is defined as the allowable range, Figure 8 A portion of the measurement results are outside the permissible range.

[0047] In S28, the variable slit is deformed (adjustment process). In the adjustment process, the shape of the beam illuminating the irradiated area is adjusted based on the brightness distribution measured in the measurement process. This is followed by... Figure 8 When the brightness is outside the allowable range, the variable slit control unit 22 controls the drive mechanism 18c to drive it in the +Y direction, so that the opening 18a of the part that increases the brightness becomes wider.

[0048] Then, S26 to S28 are repeated. When the brightness distribution is within the allowable range in S27, the process returns to S22. Through the lighting method described above, even when the difference in current values ​​between each chip column increases, the maintenance interval of the LED array 13 can be extended while maintaining exposure quality.

[0049] <Implementation Method of the Article Manufacturing Method>

[0050] The method for manufacturing articles according to the embodiments of this disclosure is suitable for manufacturing articles such as flat panel displays (FPDs), semiconductor devices, sensors, and optical components. Figure 9 This is a flowchart of the article manufacturing method according to this embodiment. The article manufacturing method of this embodiment includes a step of forming a latent image pattern on a photosensitive material coated on a substrate by exposure performed by the exposure apparatus 100 to obtain an exposed substrate (exposure step, step S31). It also includes a step of developing the substrate exposed in the above step to obtain a developed substrate (development step, step S32). Furthermore, the above manufacturing method includes other known processes (oxidation, film formation, vapor deposition, doping, planarization, etching, resist stripping, cutting, bonding, encapsulation, etc.) (processing step, step S33). Compared with conventional methods, the article manufacturing method of this embodiment is advantageous in at least one aspect of article performance, quality, productivity, and production cost.

[0051] The preferred embodiments of this disclosure have been described above, but this disclosure is not limited to these embodiments. It goes without saying that various modifications and alterations can be made within its scope. Regarding the application scope of this disclosure, it can also be applied, for example, to substrate processing apparatuses such as semiconductor manufacturing apparatuses (film deposition apparatuses, sputtering apparatuses, annealing apparatuses, inspection apparatuses, etc.), organic EL evaporation apparatuses, imprinting apparatuses, and planarization apparatuses.

[0052] According to this disclosure, an advantageous control method can be provided for controlling the lighting of LEDs.

[0053] ★★★

[0054] While this disclosure has been described with reference to exemplary embodiments, it should be understood that this disclosure is not limited to the disclosed exemplary embodiments. The scope of the following claims should be given the broadest interpretation to cover all such modifications and equivalent structures and functions.

[0055] This application claims the benefit of Japanese Patent Application No. 2024-192656, the entire contents of which are incorporated herein by reference.

Claims

1. A control method for controlling the illumination of a first LED and a second LED, characterized in that the control method includes: The process involves obtaining the illuminance of each of the first LED and the second LED. as well as The decision process involves determining the current values ​​flowing to the first LED and the second LED based on the results of the acquisition process. The decision process determines that the current value flowing to the LED with lower illuminance among the first LED and the second LED is less than the current value flowing to the other LED.

2. The control method according to claim 1, characterized in that, The acquisition process and the decision process are executed multiple times.

3. The control method according to claim 1, characterized in that, Prior to the acquisition step, a reference acquisition step is also included to obtain the illuminance of the first LED and the second LED respectively.

4. The control method according to claim 3, characterized in that, It also has: The calculation process, based on the measurement results of the benchmark acquisition process and the measurement results of the acquisition process, calculates the illuminance degradation information of the first LED and the second LED respectively. The decision-making process determines the current values ​​flowing to the first LED and the second LED based on the illuminance degradation information.

5. The control method according to claim 4, characterized in that, The decision process determines that the current value flowing to the LED with the higher illuminance degradation rate among the first LED and the second LED is less than the current value flowing to the other LED.

6. The control method according to claim 3, characterized in that, It also has: The lighting process, which is performed during the timing between the reference acquisition process and the acquisition process, involves lighting up the first LED and the second LED.

7. The control method according to claim 6, characterized in that, The lighting process is performed by overlapping the light from the first LED and the light from the second LED on the illuminated surface.

8. The control method according to claim 1, characterized in that, Also includes: The measurement process includes measuring the brightness distribution of the irradiated area illuminated by the first LED and the second LED; and The adjustment process involves adjusting the shape of the light beam irradiating the irradiated area according to the brightness distribution.

9. An exposure apparatus for transferring a pattern from an original image onto a substrate, the exposure apparatus characterized by having: The acquisition unit acquires the illuminance of each of the first and second LEDs; and The control unit controls the lighting of the first LED and the second LED. The control unit obtains the illuminance of the first LED and the second LED respectively, and based on the obtained illuminance of the first LED and the second LED respectively, determines that the current value flowing to the LED with the lower illuminance is less than the current value flowing to the other LED.

10. A method for manufacturing an article, characterized in that, include: The exposure process involves using the exposure apparatus described in claim 9 to expose the substrate, thereby obtaining an exposed substrate. as well as In the developing process, the exposed substrate is developed to obtain a developed substrate. Articles are manufactured from the developing substrate.

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