LIGHT SOURCE CONTROL DEVICE, LITHOGRAPHIC APPARATUS, AND METHOD FOR MANUFACTURING ARTICLE

Abstract

To provide a configuration advantageous in terms of cost for determination of a contact state between a light source and a drive part for driving the light source.SOLUTION: There is provided a light source control device for controlling a light source. The light source control device includes a drive part for driving the light source, a detection part for detecting electric characteristics of output of the drive part, and a control part for controlling the drive part on the basis of the electric characteristics detected by the detection part. The control part creates trend data indicating time transition of the electric characteristics, and predicts a timing at which the electric characteristics exceed a predetermined stable range on the basis of the trend data.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a light source control device, a lithography apparatus, and a method for manufacturing an article. [Background technology]

[0002] One of the devices used in the manufacturing process (lithography process) of semiconductor devices and the like is an exposure apparatus that exposes a substrate to light. The exposure apparatus transfers the mask pattern onto the photosensitive material (resist) on the substrate by projecting an image of the pattern formed on a mask onto the photosensitive material (resist) on the substrate via a projection optical system. When exposing the substrate (photosensitive material) to light (i-line) with a wavelength of, for example, 365 nm, the exposure apparatus uses a mercury lamp as the light source.

[0003] To control the lighting of the mercury lamp, the exposure apparatus is equipped with a lighting device (light source control device). The lighting device sets the electrical characteristic values ​​(power, voltage, current) of the mercury lamp to arbitrary values ​​and controls the lighting state of the mercury lamp. The lighting device measures the electrical characteristic values ​​in real time. The lighting device is equipped with a light source driving circuit (driving unit) that drives the mercury lamp, and the light source driving circuit and the mercury lamp are connected by elements such as cables, connectors, and screws.

[0004] When mercury lamps are turned on, the current value often exceeds 100 [A]. It is a basic fact that the loss [W] in a circuit is expressed as resistance [Ω] x current [A] x current [A], and this is mainly consumed as heat. In other words, assuming a high current value such as the one mentioned above, even a small fluctuation in resistance present in the light source drive circuit can lead to abnormal loss, i.e., abnormal heat generation, and cause fatal damage to the lighting device.

[0005] The aforementioned elements such as the cable, connector, and screw can become minute resistance components in the light source drive circuit, so the resistance value caused by these elements must be strictly controlled when the light source drive circuit has a high current value. For example, Patent Document 1 describes the construction of a dedicated electric circuit for monitoring the connection state between the light source control device and the light source, separate from the light source drive circuit. This electric circuit detects changes in electrical characteristics caused by loosening of the connection of the connector. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2008-186635 A Summary of the Invention [Problem to be solved by the invention]

[0007] The configuration disclosed in Patent Document 1 requires a dedicated electric circuit for monitoring the connection state between the light source drive circuit and the light source, which leads to increased costs. In addition, in a configuration in which ultra-high voltage (30 kV or more) is applied at the time of ignition, such as a mercury lamp, other issues may arise, such as ensuring an insulation distance. For this reason, it is desirable to determine the contact state from the electrical characteristic values ​​measured by the lighting device.

[0008] The present invention provides a configuration that is advantageous in terms of cost for determining the contact state between a light source and a drive unit that drives the light source. [Means for solving the problem]

[0009] According to one aspect of the present invention, there is provided a light source control device for controlling a light source, the light source control device including: a drive unit for driving the light source; a detection unit for detecting an electrical characteristic of an output of the drive unit; and a control unit for controlling the drive unit based on the electrical characteristic detected by the detection unit, the control unit creating trend data indicating a time transition of the electrical characteristic, and based on the trend data: An abnormality occurs in the connection state between the light source and the drive unit.A light source control device is provided that predicts the amount of light emitted from the light source. Effect of the Invention

[0010] According to the present invention, it is possible to provide a configuration that is advantageous in terms of cost for determining the contact state between a light source and a drive unit that drives the light source. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is a diagram showing the configuration of a light source device. [Diagram 2] FIG. 4 is a diagram showing a portion where a light source and a driving unit are fastened with screws. [Diagram 3] FIG. 4 is a diagram showing a specific example of a connection configuration between a light source and a drive unit. [Figure 4] FIG. 11 is a diagram showing an example of a stable transition of a measurement value. [Diagram 5] 11A and 11B are diagrams showing an example of a shift phenomenon of a measurement value. [Figure 6] FIG. 13 is a diagram showing an example of a drift phenomenon of a measurement value. [Figure 7] FIG. 1 is a diagram for explaining the creation of trend data using machine learning. [Figure 8] FIG. 1 is a diagram showing the configuration of an exposure apparatus. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments will be described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe a number of features, not all of these features are essential to the invention, and the features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0013] First Embodiment A light source device 1 according to the first embodiment will be described with reference to FIG. 1. The light source device 1 is a device that supplies light to a device that requires light. The light source device 1 may include, for example, a light source control device 2 and a light source 3. The light source 3 may be composed of a mercury lamp, an LED, or the like, but is not limited thereto. The light source control device 2 controls the lighting of the light source 3. Therefore, the light source control device 2 may be called a lighting device. A connection portion 10 between the light source control device 2 and the light source 3 may include a transmission line connecting the two. The light source control device 2 may include a control unit 4, a driving unit 5, measurement points 6a and 6b, and a detection unit 15. The control unit 4 has three operation modes, a constant power mode, a constant voltage mode, and a constant power mode, and controls the driving unit 5 according to a specified set value and operation mode. The detection unit 15 detects electrical characteristics of the output of the driving unit 5 at the measurement points 6a and 6b. The electrical characteristics may be at least one of an output voltage 8, an output current 9, or an output resistance calculated from these of the driving unit 5. The electrical characteristic measured at the measurement points 6a, 6b is referred to as a "measurement value." The measurement value may be a value obtained by directly measuring the voltage and / or current, or may be a value obtained by measuring at a point where the voltage or current is divided. The electrical characteristic detected by the detection unit 15, i.e., the voltage 8 and / or current 9 measured at the measurement points 6a, 6b, is fed back to the control unit 4. The control unit 4 may include an A / D converter or the like that converts the input measurement value into a digital value.

[0014] In the constant power mode, the control unit 4 performs constant power control to control the drive unit 5 so that the power applied to the light source 3 becomes a constant target value based on the fed back voltage 8 and current 9. In the constant voltage mode, the control unit 4 controls the drive unit 5 so that the voltage applied to the light source 3 becomes a constant target value based on the fed back voltage 8. In the constant current mode, the control unit 4 controls the drive unit 5 so that the current applied to the light source 3 becomes a constant target value based on the fed back current 9. In this way, the control unit 4 controls the drive unit 5 according to the difference between the measured value and the target value according to the operation mode.

[0015] The driving unit 5 that drives the light source 3 is composed of elements such as MOS-FET, and may include a circuit configuration such as a half bridge or full bridge as an electric circuit. Therefore, the driving unit 5 may be called a light source driving circuit. In addition, when driving a discharge tube lamp such as a mercury lamp, the driving unit 5 may also include an igniter circuit necessary for generating an ultra-high voltage required at start-up.

[0016] The output of the driving unit 5 is connected to the light source 3 via a connection part 10. The connection part 10 may include a transmission path such as a cable or a conductive member (such as brass). When driving a discharge tube lamp such as a mercury lamp, an igniter circuit may be included in the middle of the transmission path.

[0017] At the connection part 10, connection points 7a and 7b, which are output terminals of the light source control device 2, are connected to connection points 7c and 7d, which are input terminals of the light source 3. In the example shown in FIG. 1, there are four connection points, but this number is not limited. The connection of the transmission lines at the connection points 7a to 7d can be performed by fastening with connectors or screws, soldering, or the like. As described above, the output (voltage 8 and / or current 9) of the drive unit 5 is fed back to the control unit 4 via the transmission line 10 and the light source 3.

[0018] Furthermore, the light source control device 2 may further include a notification unit 16 that notifies a user of the timing when a connection failure occurs between the light source 3 and the drive unit 5. The notification unit 16 may include a display and / or a speaker.

[0019] The light source device 1 is generally configured as described above and supplies desired light to an external device, etc. In addition to the configuration shown in Fig. 1, the light source device 1 may also include a PWM generating circuit, a power control circuit, a rectifier circuit for an AC input power supply, an interface with an external device, etc.

[0020] When the light source 3 is a high-power light source, the power output from the driving unit 5 may also be high. In the case of a high-power light source such as a mercury lamp, the total amount of power output from the driving unit 5 may reach several kW, and the current output from the driving unit 5 may often exceed 100 [A]. In such a case, if the connection state becomes unstable at the connection points 7a to 7d due to half-insertion or loosening, abnormal heat generation may occur due to the increase in contact resistance at that portion. For this reason, the connection state at the connection points 7a to 7d needs to be strictly managed.

[0021] 2 shows an example in which the driving unit 5 and the light source 3 are electrically connected by fastening with screws 11a and 11b at a connection portion 10. The light source 3 may be a type in which electrodes are led out by a pick tail cable, a type in which electrodes are led out by a conductive member, or the like, but is not limited thereto.

[0022] FIG. 3 is a detailed view of the periphery of the screws 11a and 11b. The conductive member 12 is a member on the connection part 10 side, and the conductive member 13 is a member on the light source 3 side. The conductive member 12 and the conductive member 13 can be conductive members such as cables and brass, but are not limited thereto. When the conductive member 12 and the conductive member 13 are connected by fastening with screws, etc., a connection method is adopted in which the fastening torque is strictly controlled and the contact resistance value is equal to or less than the contact resistance value calculated from the allowable heat generation amount. By managing the connection state in this way, a stable connection state can be guaranteed during operation of the light source device 1. That is, the measured values ​​of the power, voltage, and current in the light source control device 2 do not fluctuate over the long term, but transition stably as shown in FIG. 4. The resistance value [Ω] can also be calculated from the voltage value / current value at that time, and this resistance value can be considered as the combined resistance value of the transmission path of the connection part 10 and the light source 3.

[0023] Strictly speaking, each measured value may vary to some extent. One of the reasons is that the resistance value changes due to heat from the connection points 7a to 7b of the connection part 10 and the light source 3 immediately after the lamp is turned on, and a drift occurs immediately after the lamp is turned on. Therefore, it is possible to set a stabilization wait time without monitoring each value of the power, voltage, and current immediately after the light source 3 is turned on. However, the necessity of the stabilization wait should be determined from the S / N of the signal level to be measured, and in this embodiment, it is not essential to set a stabilization wait time. Another cause is the intrusion of ripple components of the drive unit 5 or AC power supply. Therefore, immediately after the light source 3 is turned on, each value of the power, voltage, and current may not be directly adopted as a measured value, but rather a measured value averaged by an averaging method such as a moving average may be adopted. However, like the above-mentioned stabilization wait, the necessity of such averaging should also be determined from the S / N of the signal level to be measured, and it is not essential to adopt averaging.

[0024] In this embodiment, the control unit 4 creates trend data indicating the time transition of the electrical characteristics. The trend data can be created by moving average processing of the electrical characteristics. Alternatively, the trend data may be created by filtering processing such as low-pass filtering of the electrical characteristics. The example of time transition of the measured values ​​shown in FIG. 4 is an example of time transition of the measured values ​​when the above-mentioned stabilization waiting and averaging are adopted, and it is assumed that the transition data of each value of the power, voltage, and current of the light source control device 2 is measured with a desired accuracy. Note that in this embodiment, an example of constant power control is described. Constant voltage control or constant current control may be adopted instead of constant power control.

[0025] During use of the light source device 1, if the connection between the drive unit 5 and the light source 3 becomes unstable due to loosening of the screws, the resistance value in the transmission path at the connection portion 10 may change, and the transition of the measurement value may change. Possible patterns of change include a shift in the measurement value as shown in FIG. 5 and a drift in the measurement value as shown in FIG. 6. The shift phenomenon may occur when the screw 11a of the screws 11a and 11b shown in FIG. 3 breaks and the screw 11b becomes cantilevered. In this case, the shift phenomenon is assumed to be caused by a sudden decrease in the contact surface between the conductive member 12 and the conductive member 13, causing the resistance value to increase.

[0026] The drift phenomenon can occur when the light source 3 is turned on and when the screws 11a, 11b loosen due to the difference in linear expansion between the screws 11a, 11b and the conductive members 12, 13, causing the contact surface between the conductive members 12, 13 to gradually decrease, resulting in an increase in resistance. The increase in resistance increases the amount of heat generated, and the difference in linear expansion between the fastening members causes one side to stretch, increasing the loosening of the fastening, ultimately resulting in a resistance value that is significantly different from the initial value. The increase in resistance due to these phenomena can lead to abnormal heat generation and may cause the light source device 1 to fail, so it is necessary to detect connection abnormalities early.

[0027] A method for detecting a connection abnormality will be described below. In constant power control, the measurement value used to detect a connection abnormality may be any of a voltage value, a current value, and a resistance value, but here, as an example, the resistance value is used.

[0028] With the simple method of comparing the measured value with a predetermined threshold and judging an abnormality if the measured value exceeds the threshold, it is difficult to improve the judgment accuracy due to the influence of individual differences between the light source 3 and the connection part 10. In addition, since the driving unit 5 (light source driving circuit) is generally configured with low impedance, it is expected that the resistance value will also vary widely.

[0029] Therefore, in this embodiment, if the measured value (electrical characteristic) exceeds a predetermined stable range defined by a lower limit value and an upper limit value, it is determined to be abnormal. The upper limit value and the lower limit value are determined after the light source device 1 is completed, so that it is possible to deal with the above-mentioned variations. The stable range should be thoroughly considered from the characteristics of the light source 3 and the connection part 10.

[0030] In the following, the screw fastening configuration shown in FIG. 3 and an example using a mercury lamp as the light source 3 will be discussed. Therefore, the specific values ​​below are merely exemplary values ​​under that premise. In the configuration of FIG. 3, the combined resistance value of the transmission line and the light source 3 at the connection portion 10 can be, for example, several hundred [mΩ]. When sufficient averaging processing is performed on the measured values ​​(resistance values), it is considered that the trend of the measured values ​​is stable within a stable range. In other words, in a normal state, no trend of change is formed. Although short-term fluctuations may occur, the range is about several [mΩ] and can remain stable within a stable range. When either of the screws 11a, 11b breaks and the fastening loosens, a resistance value shift occurs as shown in FIG. 5. It is expected that the magnitude of the resistance value shift will vary depending on the scale of the breakage, but for example, a resistance value fluctuation of about 10 [mΩ] will cause the resistance value to exceed the stable range and be determined to be abnormal. It is expected that the resistance value shift will occur in a relatively short period of time.

[0031] When the fastening of the screws 11a, 11b gradually loosens due to linear expansion difference or the like, a measurement value drift is formed as shown in Fig. 6. As with the shift, a drift of, for example, about 10 mΩ can cause the resistance value to exceed the stable range and be determined to be abnormal. It is expected that the measurement value will change over a relatively long period of time due to the resistance value drift.

[0032] In this manner, in this embodiment, the control unit 4 determines that an abnormality (poor connection) has occurred when trend data of the measured values ​​exceeds the stable range, but it is also possible to predict the timing at which the electrical characteristics will exceed the stable range based on the created trend data. For example, the control unit 4 performs a function approximation of the trend data by fitting it with a linear function or a quadratic function. The control unit 4 predicts the timing at which the predetermined range will be exceeded based on the approximation function of the trend data.

[0033] As described above, according to this embodiment, trend data showing the time transition of the electrical characteristics of the output of the driving unit 5 is created, and the timing when the electrical characteristics will exceed the stable range is predicted based on the trend data. This makes it possible to quickly inform the user of the timing when a poor connection occurs between the light source 3 and the driving unit 5. As a result, it becomes possible to prevent the occurrence of abnormal heat generation and the like, and to prevent serious damage to the light source control device.

[0034] Furthermore, according to the configuration of this embodiment, there is no need to configure a dedicated electric circuit for monitoring the connection state between the light source 3 and the driving unit 5. Therefore, according to this embodiment, a configuration that is advantageous in terms of cost for determining the contact state between the light source 3 and the driving unit 5 is provided.

[0035] <Second embodiment> In the second embodiment, detection of an abnormality in a connection state using machine learning will be described. For example, the control unit 4 acquires an image of a connection part for learning (for example, by imaging) each time a measurement is performed, and stores the image, a measurement value (here, a resistance value), and the time when the measurement was performed in association with each other in a memory, and this is used as learning data. The more learning data, the more desirable it is, and the learning data should sufficiently include data at the time of connection abnormality. After that, for example, each acquired image is judged for connection abnormality by image processing or visual inspection, and information on the measurement value and time for the image at the time of connection abnormality is created. Based on the created information, the control unit 4 generates a model for determining an estimated normal range of electrical characteristics by machine learning. The machine learning may be, for example, learning using a linear regression model. However, there is no limitation to the algorithm of the machine learning, and the machine learning may be learning using a principal component analysis model that takes into account the influence of components such as the light source ON time and the environmental temperature, or learning using Naive Bayes that takes into account real-time characteristics.

[0036] FIG. 7 shows the relationship between the transition of the measurement value and the estimated normal range obtained based on the model. The estimated normal range is obtained, for example, as a range narrower than the predetermined stable range described in the first embodiment. Since the measurement value stably transitions within the estimated normal range while the connection state is normal, the measurement value does not shift or drift, and the measurement value does not exceed the estimated normal range. However, as time passes, a shift or drift of the measurement value occurs, the measurement value exceeds the estimated normal range obtained by learning, and transitions to an abnormal state. The control unit 4 creates trend data of the measurement value detected after transitioning to the abnormal state. As described above, the trend data is created by moving average or filter processing. Furthermore, function approximation of the created trend data is performed using an approximation method such as function fitting by the least squares method, a generation method using a machine learning algorithm, or the like. The control unit 4 predicts the timing of exceeding the predetermined range based on the function obtained by the function approximation. The trend data at this time does not include the measurement value at the stable time, but only includes the trend at the time of the shift or drift, so that the timing of exceeding the stable range can be predicted more accurately and quickly. The control unit 4 may notify the user of the predicted time of exceeding the threshold width. This makes it possible to notify the user of a possible connection failure at an earlier stage.

[0037] In the above embodiment, the machine learning has been described as being executed in the control unit 4, but the machine learning may be executed by an external machine learning device.

[0038] According to the first and second embodiments described above, it is possible to prevent the occurrence of abnormal heat generation in the light source, and it is possible to prevent serious damage to the light source control device.

[0039] <Third embodiment> In the following embodiment, a lithography apparatus to which the above-mentioned light source device is applied will be described. The lithography apparatus is an apparatus for forming a pattern on a substrate, and examples of the lithography apparatus include an exposure apparatus and an imprint apparatus. The exposure apparatus projects the pattern of an original onto a substrate coated with a photosensitive agent via a projection optical system, thereby forming a latent image pattern corresponding to the pattern of the original in the photosensitive agent. The imprint apparatus, for example, illuminates and hardens the imprint material arranged on the substrate while the original (mold) is in contact with the imprint material, thereby forming the imprint material into a pattern corresponding to the pattern of the original.

[0040] 8 is a block diagram showing the configuration of an exposure apparatus, which is one type of lithography apparatus equipped with a light source device. This exposure apparatus includes a light source device 1, an illumination optical system 200, a reticle stage RS that holds a reticle R, a projection optical system 300, a wafer stage WS that holds a wafer W, which is a substrate, and a controller 400.

[0041] The illumination optical system 200 includes lenses, mirrors, optical integrators, diaphragms, etc. (not shown), which adjust the light from the light source device 1 and illuminate the reticle R, which is the illumination area. The reticle R is an original (mask) made of, for example, quartz glass, on which a pattern (for example, a circuit pattern) to be transferred onto the wafer W is formed. The reticle stage RS is capable of holding and moving the reticle R, and is driven by a driving mechanism such as a linear motor (not shown). The projection optical system 300 projects the light that has passed through the reticle R onto the wafer W at a predetermined magnification. The wafer W is a substrate made of, for example, single crystal silicon, with a photoresist (photosensitive material) applied on its surface. The wafer stage WS is capable of holding and moving the wafer W via a wafer chuck (not shown), and is driven by a driving mechanism such as a linear motor (not shown).

[0042] The control unit 400 is configured by a computer device including, for example, a CPU 401, a memory 402, and a display unit 403, and performs overall control of each unit of the exposure apparatus to execute an exposure process for transferring a pattern formed on a reticle R onto a wafer W. In this embodiment, the control unit 400 may function as the control unit 4 in the light source control device 2 described above. In an exposure apparatus configured in this manner, similar to the first embodiment, trend data showing the time transition of the electrical characteristics of the output of the drive unit 5 is created, and the timing at which the electrical characteristics will exceed the stable range is predicted based on the trend data. This makes it possible to quickly inform the user of the timing at which a connection failure will occur between the light source 3 and the drive unit 5.

[0043] <Embodiment of the article manufacturing method> The article manufacturing method according to the embodiment of the present invention is suitable for manufacturing articles such as microdevices such as semiconductor devices and elements having fine structures. The article manufacturing method according to the present embodiment may include a forming step of forming a pattern of an original on a substrate using the above-mentioned lithography apparatus (exposure apparatus, imprint apparatus, drawing apparatus, etc.) and a processing step of processing the substrate on which the pattern has been formed in the forming step. Furthermore, such an article manufacturing method may include other well-known steps (oxidation, film formation, deposition, doping, planarization, etching, resist stripping, dicing, bonding, packaging, etc.). The article manufacturing method according to the present embodiment is advantageous in at least one of the performance, quality, productivity, and production cost of the article compared to conventional methods.

[0044] The invention is not limited to the above-described embodiments, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, the following claims are appended to apprise the public of the scope of the invention. [Explanation of symbols]

[0045] 1: light source device, 2: light source control device, 3: light source, 4: control unit, 5: drive unit, 10: connection part, 15: detection unit

Claims

1. A light source control device that controls a light source, A driving unit that drives the light source; a detector for detecting an electrical characteristic of an output of the driver; a control unit that controls the drive unit based on the electrical characteristic detected by the detection unit, The control unit creates trend data indicating the time progression of the electrical characteristics, and predicts the occurrence of an abnormality in the connection state between the light source and the driving unit based on the trend data.

2. The light source control device as described in Claim 1, characterized in that the control unit predicts the timing when the electrical characteristics will exceed a predetermined stable range.

3. 3. The light source control device according to claim 2, further comprising a notification unit that notifies the predicted timing as a timing at which a connection failure will occur between the light source and the drive unit.

4. A light source control device as described in claim 1, further comprising an alarm unit that notifies the timing at which the abnormality occurs.

5. 5. The light source control device according to claim 1, wherein the trend data is generated by performing a moving average process on the electrical characteristics.

6. The light source control device according to claim 1 , wherein the trend data is generated by filtering the electrical characteristics.

7. The light-source control device according to claim 1 , wherein the control unit performs constant power control to control the power applied to the light source so as to be constant.

8. 8. The light source control device according to claim 1, wherein the electrical characteristic is any one of an output resistance, an output voltage, and an output current of the drive unit.

9. The light source control device according to claim 1 , wherein a model for determining the estimated normal range of the electrical characteristic is generated by machine learning.

10. The light source control device according to claim 9, characterized in that the control unit creates trend data of the electrical characteristics detected by the detection unit after the electrical characteristics exceed the estimated normal range determined based on the model, and predicts the timing at which the electrical characteristics will exceed a predetermined stable range based on the trend data.

11. 1. A lithographic apparatus for forming a pattern on a substrate, comprising: The light source control device according to any one of claims 1 to 10, a light source that is controlled by the light source control device and that exposes the substrate to light, thereby forming a pattern on the substrate;

12. forming a pattern on a substrate using a lithographic apparatus according to claim 11; processing the substrate on which the pattern is formed; and manufacturing an article from the processed substrate.

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