Control device, light source device, control method, and program

Abstract

To provide a control device capable of reducing deposits, a light source device, a control method, and a program.SOLUTION: The control unit 160 of the light source device 100 according to the present disclosure is a control device that determines a mode to be executed from among a plurality of modes. The plurality of modes include a first mode in which the light-source device 100 illuminates the sample 500 with the illumination light L1 generated by irradiating the target material 112 held by the target holding unit 110 with the laser beam, and a second mode in which the light-source device 100 reduces the attached matter by irradiating the attached matter attached to the target holding unit 110 with the laser beam.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] The present disclosure relates to a control device, a light source device, a control method, and a program. [Background technology]

[0002] Patent Document 1 describes a light source device that irradiates an optical component placed in a chamber with a cleaning pulse laser beam to remove debris adhering to the surface of the optical component.

[0003] Patent Document 2 describes a light generating device that changes the optical conditions of a laser that is irradiated onto a target member, and irradiates debris that has adhered to the optical system. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-186995 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-235959 Summary of the Invention [Problem to be solved by the invention]

[0005] As mentioned above, Patent Documents 1 and 2 disclose devices that use lasers to remove debris. However, in Patent Documents 1 and 2, the locations where debris adheres and from which it can be removed are limited.

[0006] In view of the above-mentioned problems, an object of the present disclosure is to provide a control device, a light source device, a control method, and a program that can improve the efficiency of operation and maintenance of the device. [Means for solving the problem]

[0007] The optical device control device according to the present disclosure is a control device for an optical device including a light source device, which determines an execution mode from among a plurality of modes, including a first mode in which the light source device illuminates an object with illumination light generated by irradiating a target material held by a holder with a laser, and a second mode in which the light source device reduces deposits adhering to the surface of the holder by irradiating the deposits with a laser.

[0008] A control device for a light source device according to the present disclosure is a control device for a light source device that determines an execution mode from among a plurality of modes, including a first mode in which light is generated by irradiating a laser onto a target material held by a holder, and a second mode in which deposits adhering to a surface of the holder are reduced by irradiating the laser onto the deposits.

[0009] The optical device control device according to the present disclosure is a control device for an optical device including a light source device, which determines an execution mode from among a plurality of modes, including a first mode in which the light source device illuminates an object with illumination light generated by irradiating a target material in a chamber with a laser, and a second mode in which the light source device irradiates a deposit adhering to a surface of a component in the chamber with a laser to reduce the deposit, and in the second mode, the laser irradiated on the deposit also irradiates the target material.

[0010] A control device for a light source device according to the present disclosure is a control device for a light source device that determines an execution mode from among a plurality of modes, including a first mode in which light is generated by irradiating a target material in a chamber with a laser, and a second mode in which deposits adhering to a surface of a component in the chamber are reduced by irradiating the laser onto the deposits, and in the second mode, the laser irradiated onto the deposits also irradiates the target material.

[0011] The control device may not perform scanning with the laser in the first mode but may perform scanning with the laser in the second mode, or may perform scanning with the laser in the first mode and the second mode, and the amount of scanning with the laser in the second mode may be larger than that in the first mode.

[0012] In the control device, the laser irradiation state in the second mode may be in a defocused state compared to the laser irradiation state in the first mode.

[0013] The control device may switch the execution mode from the second mode to the first mode when a predetermined switching condition is met, and the predetermined switching condition may include a condition where, when the execution mode is the second mode, a position of plasma generated by irradiation with the laser coincides with a predetermined position.

[0014] The light source device may include an identification unit that identifies a type of the attached matter. The plurality of modes may include a plurality of second modes having different control conditions, and the control device may determine one of the plurality of second modes as the mode to be executed based on the type of the attached matter identified by the identification unit.

[0015] The light source device may include a laser generator that outputs a laser in the first mode and a laser in the second mode, and the control device may control the laser generator according to the mode to be executed.

[0016] The light source device may include a first laser generator that outputs a laser in the first mode, a second laser generator that outputs a laser in the second mode, and an optical element through which the laser generated by the first laser generator and the laser generated by the second laser generator pass. The control device may control the first laser generator and the second laser generator according to the mode to be executed.

[0017] The light source device may include a holder that rotates around a rotation axis. When the execution mode is the first mode, the control device may cause the light source device to irradiate the laser beam onto the target material held by the holder.

[0018] The optical device may include an adjusting unit that suppresses propagation of light generated from the light source device to the object. The control unit may drive the adjusting unit when the execution mode is the second mode.

[0019] The light source device of the present disclosure is a light source device that generates light by irradiating a laser onto a molten target material, and is equipped with a control unit that reduces adhesions adhering to the surface of a holding portion of the target material by irradiating the laser onto the adhesions.

[0020] In the light source device, the holding portion may rotate around a rotation axis.

[0021] A light source device according to the present disclosure generates light by irradiating a target material in a chamber with a laser. The light source device includes a control unit that irradiates a laser beam onto a deposit adhering to a surface of a component in the chamber to reduce the deposit, and the laser beam irradiated onto the deposit is also irradiated onto the target material.

[0022] The control method for an optical device according to the present disclosure includes a first step of illuminating an object with illumination light generated by irradiating a laser onto a target material held by a holding portion, a second step of reducing adhesions adhering to the surface of the holding portion by irradiating the laser onto the adhesions, and a third step of switching between the first step and the second step.

[0023] The control method for a light source device according to the present disclosure includes a first step of generating light by irradiating a laser onto a target material held by a holding portion, a second step of reducing deposits adhering to the surface of the holding portion by irradiating the laser onto the deposits, and a third step of switching between the first step and the second step.

[0024] The method for controlling an optical device according to the present disclosure includes a first step of illuminating an object with illumination light generated by irradiating a target material in a chamber with a laser, a second step of reducing deposits adhering to a surface of a component in the chamber by irradiating the laser to the deposits, and a third step of switching between the first step and the second step. In the second step, the laser irradiated to the deposits is also irradiated to the target material.

[0025] A method for controlling a light source device according to the present disclosure includes a first step of generating light by irradiating a target material in a chamber with a laser, a second step of reducing deposits adhering to a surface of a component in the chamber by irradiating the laser to the deposits, and a third step of switching between the first step and the second step. In the second step, the laser irradiated to the deposits is also irradiated to the target material.

[0026] The control method for a light source device according to the present disclosure includes a first step of generating light by irradiating a laser onto a molten target material, a second step of reducing deposits adhering to the surface of a holding portion of the target material by irradiating the laser onto the deposits, and a third step of switching between the first step and the second step.

[0027] The program of the present disclosure causes an optical device to perform the following steps: a first step of illuminating an object with illumination light generated by irradiating a laser onto a target material held by a holding unit; a second step of reducing adhesions adhering to the surface of the holding unit by irradiating the laser onto the adhesions; and a third step of switching between the first step and the second step.

[0028] The program of the present disclosure causes a light source device to perform a first step of generating light by irradiating a laser onto a target material held by a holding unit, a second step of reducing adhesions adhering to the surface of the holding unit by irradiating the laser onto the adhesions, and a third step of switching between the first step and the second step.

[0029] The program according to the present disclosure causes an optical device to execute the following steps: a first step of illuminating an object with illumination light generated by irradiating a target material in a chamber with a laser, a second step of reducing deposits adhering to a surface of a component in the chamber by irradiating the laser to the deposits, and a third step of switching between the first step and the second step. In the second step, the laser irradiated to the deposits is also irradiated to the target material.

[0030] The program according to the present disclosure causes a light source device to execute a first step of generating light by irradiating a target material in a chamber with a laser, a second step of reducing deposits adhering to a surface of a component in the chamber with a laser, and a third step of switching between the first step and the second step. In the second step, the laser irradiated onto the deposits is also irradiated onto the target material.

[0031] The program of the present disclosure causes a light source device to perform a first step of generating light by irradiating a laser onto molten target material, a second step of reducing deposits attached to the surface of a holding portion of the target material by irradiating the laser onto the deposits, and a third step of switching between the first step and the second step. [Effects of the Invention]

[0032] According to the present disclosure, the operation and maintenance of the device can be made more efficient. [Brief explanation of the drawings]

[0033] [Figure 1] 1 is a cross-sectional view illustrating a light source device according to a first embodiment. [Figure 2] 3 is a perspective view illustrating a container serving as a target holding unit in the light source device according to the first embodiment. FIG. [Figure 3] 1 is a plan view illustrating a light source device according to a first embodiment. [Figure 4] 2 is a diagram illustrating a focus adjustment mechanism according to the first embodiment. FIG. [Figure 5] 3 is a diagram illustrating an acquisition unit, a drive unit, and a control unit in the light source device according to the first embodiment. FIG. [Figure 6] FIG. 3 is a flowchart illustrating a method for controlling an operation mode according to the first embodiment. [Figure 7] 1 is a configuration diagram illustrating an inspection device equipped with a light source device according to a first embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0034] Hereinafter, a specific configuration of this embodiment will be described with reference to the drawings. The following description shows a preferred embodiment of the present disclosure, and the scope of the present disclosure is not limited to the following embodiment. In the following description, components with the same reference numerals indicate substantially the same content.

[0035] (Embodiment 1) A light source device according to a first embodiment will be described. The light source device of this embodiment generates light such as illumination light and exposure light used in optical devices such as inspection devices and exposure devices. The light source device may be provided integrally with the optical device, or may be disposed near the optical device as a separate entity. When the optical device is an inspection device, the light source device generates illumination light that illuminates an inspection object in the inspection device. When the optical device is an exposure device, the light source device generates exposure light that exposes an exposure object in the exposure device.

[0036] The light source device generates light such as illumination light and exposure light by irradiating excitation light onto a target material held in a target holder. In the following first embodiment, an example of a light source device will be described in which a liquid target material is held in a target holder including a container such as a crucible. However, the target holder may include a cylindrical drum, a tape-like structure, or the like, instead of a container such as a crucible. A solid target material is held in the drum. Here, the target holder 110 may be housed in a chamber whose interior is in a vacuum state. As another example, the light source device may use a tape-like target material or a target material that falls or is ejected in droplet form. In other words, the target holder is not necessarily required for the configuration of the light source device. As described below, plasma is generated by irradiating the target material with EUV light. At least the portion of the target material where plasma is generated may be located within a chamber whose interior is in a vacuum state. In this case, optical elements of the light source device 100, described below, may be provided within the chamber.

[0037] FIG. 1 is a cross-sectional view illustrating a light source device 100 according to the first embodiment. FIG. 2 is a perspective view illustrating a container 111 as a target holder 110 in the light source device 100 according to the first embodiment. FIG. 3 is a plan view illustrating the light source device 100 according to the first embodiment. Some components are omitted in FIG. 3. As shown in FIGS. 1 to 3, the light source device 100 includes a target holder 110, an input optical system 120, an output optical system 130, an acquisition unit 140, a sensor 141, a driver 150, and a controller 160. In FIG. 1, the driver 150A is connected to the mirror 121, and the driver 150B is connected to the collector mirror 131. However, the driver does not necessarily need to be connected to all of these optical components. To avoid cluttering the diagram, the controller 160 is connected to only some components, but it may be connected to other components. The controller 160 is a control device including one or more processors (processing devices). The processor is connected to a memory (not shown), and reads and executes a computer program from the memory to control the operations performed by the light source device 100. Details of this control will be described later.

[0038] As an example of a processor, one of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), and an ASIC (Application Specific Integrated Circuit) may be used, or multiple of these may be used in parallel.

[0039] The memory may be a volatile memory, a nonvolatile memory, or a combination thereof. The number of memories is not limited to one, and multiple memories may be provided. The volatile memory may be, for example, a random access memory (RAM) such as a dynamic random access memory (DRAM) or a static random access memory (SRAM). The nonvolatile memory may be, for example, a read only memory (ROM) such as a programmable random only memory (PROM) or an erasable programmable read only memory (EPROM), a flash memory, or a solid state drive (SSD).

[0040] The memory is used to store one or more instructions. Here, the one or more instructions are stored in the memory as a program. The processor can perform the processes described in the above embodiments by reading and executing the program from the memory.

[0041] The memory may be external to the processor or may be built into the processor. The memory may also include storage located away from the processor. In this case, the processor can access the memory via an I / O (Input / Output) interface.

[0042] As described above, one or more processors included in the light source device 100 execute one or more programs including instructions for causing a computer to execute the algorithms described with reference to the drawings. By executing the programs, the following information processing can be realized.

[0043] The target holder 110 holds a target material 112. The target holder 110 includes a container 111 such as a crucible. The container 111 can hold metal that has been heated from a solid state to a liquid state (i.e., melted). Hereinafter, the metal that has been melted will also be referred to as molten metal. The container 111 holds a target material 112 such as molten metal that generates plasma 127 when irradiated with excitation light LR. The excitation light LR is, for example, laser light including IR (Infrared) light.

[0044] The target holding unit 110 is not limited to the container 111, and may be a cylindrical drum. In this case, the target holding unit 110 holds the target material 112 by fixing a solid, which will become the target material 112, such as frozen xenon (Xe), on the surface of the drum.

[0045] The target material 112 may include molten metal. Note that the target material 112 is not limited to the molten metal held in the container 111, and may be a solid metal, liquid droplets, or the like, as long as it is a substance that generates plasma 127 when irradiated with excitation light LR. The molten metal is, for example, melted tin (Sn) or lithium (Li), but is not limited to tin or lithium, as long as it generates plasma 127 when irradiated with excitation light LR.

[0046] The vessel 111 has a rotation axis R and rotates around the rotation axis R. The vessel 111 has, for example, a cylindrical shape with one opening closed. The closed portion of the vessel 111 is called the bottom 113. The cylindrical portion of the vessel 111 is called the cylindrical portion 114. The inner surface of the bottom 113 is called the bottom surface 115. The inner surface of the cylindrical portion 114 is called the inner wall surface 116A, and the outer surface of the cylindrical portion 114 is called the outer wall surface 116B. A groove 117 may be formed at the joint between the bottom 113 and the cylindrical portion 114. The vessel 111 may have a shape other than the above as long as it can hold molten metal.

[0047] The target holder 110 supports the target material 112 on the inner wall surface 116A of the container 111 by centrifugal force generated by rotation. The inner wall surface 116A formed to surround the rotation axis R may include a cylindrical portion that is at a constant distance from the rotation axis R, or may include a cone-shaped portion that widens outward as it approaches the top. For example, the cone-shaped portion of the inner wall surface 116A may be connected to a groove 117.

[0048] In addition to the target holder 110, the light source device 100 may also include a heater 118 and a debris shield 119. By heating with the heater 118, a target material 112 such as molten metal can be formed in the container 111. The debris shield 119 is disposed at an opening 111a of the container 111 so as to cover the target material 112.

[0049] As the container 111 rotates about the rotation axis R, the target material 112 also rotates about the rotation axis R. As shown in Fig. 3, for example, at time t1, the target material 112 is positioned at position P1 facing the sensor 141, and at time t2, as the container 111 rotates, the target material 112 moves to the irradiation position PS. In this way, as the target holder 110 moves (i.e., rotates), the target holder 110 moves the target material 112 to the irradiation position PS where it is irradiated with the excitation light LR.

[0050] The input optical system 120 includes a first optical member OP1. The first optical member OP1 irradiates the target material 112 with excitation light LR. The first optical member OP1 includes, for example, at least one of a mirror 121 and a focus adjustment mechanism 170. Note that the first optical member OP1 is not limited to the mirror 121 and the focus adjustment mechanism 170, as long as it is an optical member that irradiates the target material 112 with excitation light LR, and may also be a laser LS1 that generates the excitation light LR.

[0051] The first optical member OP1 irradiates the target material 112 with the excitation light LR at an angle tilted from an axis perpendicular to the surface of the target material 112. Specifically, for example, the first optical member OP1 irradiates the surface of the irradiation position PS where the excitation light LR is irradiated with the excitation light LR at an incident angle tilted. By irradiating the excitation light LR at an inclined angle in this way, it is possible to suppress the influence of debris on optical members including the collector mirror 131 and the like. The reason why the influence of debris on optical members such as the collector mirror 131 can be suppressed will be explained below.

[0052] When the excitation light LR is irradiated from a direction perpendicular to the surface of the target material 112, debris scatters in all directions centered on the direction perpendicular to the surface. This can result in the debris adhering to the collector mirror 131 facing the irradiation position PS. On the other hand, when the excitation light LR is irradiated at an incident angle tilted toward the front of the irradiation position PS with respect to the direction of movement of the target holder 110, that is, when the excitation light LR is irradiated from a direction having an incident angle component tilted toward the front in a plane perpendicular to the rotation axis R, an angular velocity in the rotation direction of the container 111 is applied in the direction in which the debris scatters. Therefore, the debris can be further scattered in the reflection direction of the excitation light LR. In this way, the impact of debris on optical components such as the collector mirror 131 can be suppressed.

[0053] The mirror 121, for example, reflects the excitation light LR generated by the laser LS1 toward the irradiation position PS of the target material 112. The mirror 121 may include, for example, a mirror such as a piezo steering mirror. Note that the mirror 121 is not limited to a piezo steering mirror and may include a galvanometer mirror, a polygon mirror, or the like, as long as it can reflect the excitation light LR toward the target material 112. A condenser lens 122 (described later) in the focus adjustment mechanism 170 condenses the excitation light LR at the irradiation position PS of the target material 112.

[0054] The light source device 100 may include a laser LS1, which is a laser generator that generates excitation light LR. Alternatively, the light source device 100 may introduce excitation light LR from a laser LS1 that is installed outside the light source device 100 and separate from the light source device 100 into the light source device 100. The excitation light LR is, for example, laser light that includes IR light. The excitation light LR may irradiate the target material 112 under the control of the control unit 160 to start and stop oscillation. For example, the excitation light LR is reflected by a mirror 121 and focused by a focusing lens in the focus adjustment mechanism 170. As a result, the excitation light LR irradiates the target material 112.

[0055] The output optical system 130 includes a second optical member OP2. The second optical member OP2 extracts the light L0 generated by irradiating the target material 112 with the excitation light LR from the light source device 100. The second optical member OP2 includes, for example, a collector mirror 131. Note that the second optical member OP2 is not limited to the collector mirror 131 as long as it is an optical member that extracts the light L0 generated by irradiating the target material 112 with the excitation light LR, and may also be a second collector mirror (not shown) that further reflects the light L0 reflected by the collector mirror 131.

[0056] The collector mirror 131 reflects the light L0 generated from the target material 112 by irradiation with the excitation light LR. The collector mirror 131 reflects, for example, the EUV (Extreme ultraviolet lithography) light LE generated by irradiation with the excitation light LR. That is, the light L0 may include the EUV light LE. The EUV light LE is generated from the plasma 127 generated by irradiating the target material 112 with the excitation light LR. The EUV light LE generated from the plasma 127 generated in the target material 112 is emitted as illumination light to an optical device such as an inspection device. Therefore, the illumination light includes the EUV light LE generated from the plasma 127.

[0057] The acquisition unit 140 acquires the surface position of the target material 112. The acquisition unit 140 is connected to a sensor 141 and acquires from the sensor 141 the surface position of the target material 112 that is actually measured by the sensor 141. The acquisition unit 140 acquires the surface position of the target material 112 at an irradiation position PS where the excitation light LR irradiates the target material 112. The acquisition unit 140 may acquire the surface position that is actually measured by the sensor 141 at the irradiation position PS, or may predict the surface position at the irradiation position PS from surface positions that are actually measured by the sensor 141 at peripheral positions, as will be described later. Furthermore, the acquisition unit 140 may predict the surface position of the target material 112 taking into account the tilt and vibration of the target holder 110 with respect to the rotation axis.

[0058] The acquisition unit 140 may be a separate entity from the sensor 141, or may be integrated with the sensor 141. Specifically, the sensor 141 may include, for example, a displacement meter, a high-speed camera, a low-speed camera, a four-segment PD (Photo Diode), or a TDI (Time Delay Integration) camera. The acquisition unit 140 may acquire the surface position of the target material 112 by combining the sensor 141, such as a displacement meter, with another sensor. This allows the other sensor to supplement phase information that is difficult for the sensor 141, such as a displacement meter, to acquire.

[0059] The acquisition unit 140 may acquire the surface position of the target material 112 as a relative position with respect to the second optical member OP2. Specifically, the acquisition unit 140 may acquire the surface position of the target material 112 at the irradiation position PS as a relative position with respect to the second optical member OP2, or may acquire the surface position at a peripheral position as a relative position with respect to the second optical member OP2. The acquisition unit 140 may acquire the surface position of the target material 112 based on the distance from the sensor 141 to the surface of the molten metal. The acquisition unit 140 may also acquire the surface position of the target material 112 based on the thickness of the molten metal from the inner wall surface 116A. Note that, in the case where the target material 112 is solid metal fixed to a cylindrical drum, the acquisition unit 140 may acquire the surface position of the target material 112 based on the thickness of the solid metal surface from the upper surface (surface) of the drum, as well as the tilt or vibration amount of the drum.

[0060] The acquisition unit 140 may acquire surface positions of peripheral positions other than the irradiation position PS. The peripheral positions include portions of the inner wall surface 116A of the container 111 other than the irradiation position PS. The acquisition unit 140 may predict the surface position of the irradiation position PS from the surface positions of the peripheral positions acquired from the sensor 141. Specifically, the acquisition unit 140 predicts the surface position of the irradiation position PS from the surface position of a position before the irradiation position PS in the direction of movement of the target holding unit 110. At this time, by taking into account the movement speed (rotation speed) of the target holding unit 110, it is possible to predict the surface position at the irradiation position PS at the time when the excitation light reaches the irradiation position PS (the time of irradiation). The acquisition unit 140 acquires the surface position of the irradiation position PS by predicting the surface position of the irradiation position PS in this manner.

[0061] If the sensor 141 is placed at a position opposite the irradiation position PS so that the surface position at the irradiation position PS can be measured and acquired, there is a risk that it will be affected by debris. Furthermore, since plasma 127 is generated at the irradiation position PS, there is a risk that the surface position will not be acquired accurately. Therefore, the sensor 141 is placed so as to face a peripheral position away from the irradiation position PS. This makes it possible to suppress the influence of debris and improve the measurement accuracy of the surface position. For example, the sensor 141 may be placed so as to face a position P1 on the opposite side of the irradiation position PS with respect to the rotation axis R. Note that the sensor 141 may be placed so as to face a peripheral position other than position P1 as long as the influence of debris can be reduced.

[0062] Fig. 4 is a diagram illustrating the focus adjustment mechanism 170 in the light source device 100 according to embodiment 1. As shown in Fig. 4, the focus adjustment mechanism 170 includes a condenser lens 122 and a driver 150C. In Fig. 4, the driver 150C is connected to the condenser lens 122.

[0063] The condenser lens 122 condenses the excitation light LR reflected by the mirror 121 onto the irradiation position PS of the target material 112. The control unit 160 controls the driving unit 150C to move the condenser lens 122 either toward the front or rear of the laser optical path. This allows the laser output from the laser LS1 to be defocused, as described below.

[0064] 5 is a diagram illustrating the acquisition unit 140, the drive unit 150, and the control unit 160 in the light source device 100 according to the first embodiment. As described above, the position of the sensor 141 is not limited to a position facing the irradiation position PS, but may be a position facing a peripheral position such as position P1. As shown in FIG. 5, the drive units 150A to 150C vary the position of the light convergence point of at least one of the first optical member OP1 and the second optical member OP2. The drive units 150A to 150C are, for example, actuators.

[0065] The driving units 150A and 150C drive the first optical member OP1 so as to change the irradiation direction of the excitation light LR. For example, when the first optical member OP1 is a mirror 121, the driving unit 150A performs beam scanning by changing the angle of the mirror 121 with respect to the excitation light LR. Specifically, the driving unit 150A changes the reflecting surface of the mirror 121 so that the excitation light LR scans the surface of the target material 112 in a predetermined direction.

[0066] If mirror 121 is a piezo steering mirror, driver 150A may include a drive mechanism provided on the piezo steering mirror. Also, if mirror 121 is a galvanometer mirror, polygon mirror, or the like, driver 150A may be a drive mechanism provided on the galvanometer mirror, polygon mirror, or the like. Note that if another actuator with a short response time and good controllability is available, driver 150A may also be that.

[0067] Plasma 127 is generated at the irradiation position PS where the excitation light LR irradiates the target material 112. The generated plasma 127 is observed as a bright spot. The driver 150A drives the mirror 121 to change the optical axis of the excitation light LR, thereby changing the position of the focal point. As a result, the driver 150A moves the bright spot at high speed to perform beam shaping. Therefore, when the optical device is an inspection device, it is possible to improve the uniformity and availability on the detector of the inspection device. The driver 150A may change the position of the focal point in two axial directions on the surface of the target material 112 at the irradiation position PS.

[0068] The control of the control unit 160 in the present disclosure will be described below. The light source device 100, or an optical device including the light source device 100 (an example of which will be described later), executes an operation according to one of a plurality of operation modes under the control of the control unit 160. The control unit 160 can switch between, for example, a first mode operation and a second mode operation as the plurality of operation modes, and cause the light source device 100 or the optical device to execute the operation. However, the plurality of operation modes may include operation modes other than the first mode and the second mode. The first mode is a mode in which the light source device 100 irradiates the molten target material 112 with excitation light LR from the laser LS1 to generate plasma, thereby generating light. The generated light may be EUV light LE, and the generated light may be used as illumination light for illuminating an object (a sample 500 described later). The first mode is a mode in which the optical device illuminates an object (a sample 500 described later) by using, as illumination light, light generated by the light source device 100 irradiating the molten target material 112 with excitation light LR from the laser LS1. Details of this operation are as described above.

[0069] The second mode is a mode in which light source device 100 reduces contamination of target holding part 110 by irradiating deposits adhering to the surface of target holding part 110 with a laser from laser LS1 (hereinafter also referred to as cleaning laser). The area irradiated with the cleaning laser may be the inner wall surface 116A or another part of target holding part 110. The laser from laser LS1 may be irradiated only to deposits adhering to target holding part 110, or may be irradiated not only to deposits adhering to target holding part 110 but also to target material 112.

[0070] The deposits are generated when the target material 112 is irradiated with the excitation light LR and plasma is generated, resulting in a high temperature and high pressure environment. The deposits are, for example, compounds derived from the material of the target material 112 and the material of the container 111 (or the target holder 110, such as a cylindrical drum or tape-like structure). The deposits adhere to components around the area where the target material 112 is held, and are thought to adhere particularly in large quantities to the metal surface of the target holder 110 (such as the container 111, drum, or tape). For example, when the sensor 141 acquires the surface position of the target material 112, the presence of deposits around the target material 112 may prevent the sensor 141 from accurately detecting the surface position of the target material 112. This may result in plasma not being generated at the desired position, which may prevent the sample 500 from being accurately illuminated. However, reducing or even removing the deposits can prevent such a situation from occurring. Furthermore, by irradiating the laser not only on the deposits but also on the target material 112, the deposits are more easily reduced due to mutual reactions between the deposits and the target material 112 and the laser.

[0071] Here, in the second mode, the control unit 160 may increase the amount of laser scanning in a direction perpendicular to the rotation direction of the inner wall surface 116A where the target holder 110 holds the target material 112, compared to the first mode. The direction perpendicular to the rotation direction is the β-axis direction in FIG. 2. For example, the control unit 160 may not cause the excitation light LR to scan in the β-axis direction in the first mode, but may cause the cleaning laser to scan a predetermined amount in the β-axis direction in the second mode. The control unit 160 can control the amount of scanning in the β-axis direction by controlling the drive unit 150A to change the manner in which the angle of the mirror 121 with respect to the excitation light LR is changed between the first mode and the second mode. This is explained above.

[0072] Further, the control unit 160 may set the irradiation state of the cleaning laser on the deposits on the target holding unit 110 in the second mode to a defocused state by comparing it with the irradiation state of the excitation light LR on the target material 112 in the first mode. The defocused state means a state where the laser is not in focus on the object to be irradiated. That is, the spot diameter of the cleaning laser irradiated on the deposits in the second mode is larger than the spot diameter of the excitation light LR irradiated on the target material 112 in the first mode. Furthermore, the distance between the focus of the cleaning laser and the deposits in the second mode is larger than the distance between the focus of the excitation light LR and the target material 112 in the first mode.

[0073] The control unit 160 may set either one of the peak power densities of the laser in the second mode and the peak power density of the laser in the first mode to be greater than the other, or may set both to be the same. The control unit 160 may realize the control of the peak power density by controlling the defocused state of the irradiation state as described above, or may realize it by controlling the pulse energy or peak power of the laser.

[0074] For example, the control unit 160 can set the peak power of the laser in the second mode to be smaller than the peak power of the laser in the first mode by setting the relationship between the pulse width W1 of the laser in the first mode and the pulse width W2 of the laser in the second mode to W1 < W2, even when the pulse energy is substantially the same in both modes.

[0075] Note that, where D is the peak power density, PP is the peak power, and M is the laser irradiation spot area, the relationship D=PP / M may hold. Therefore, the control unit 160 can make the peak power density in the first mode and the peak power density in the second mode different by controlling the peak power or the laser irradiation spot area using the above-mentioned method. When the laser irradiation spot area is small, the light is in focus (focused), and when the laser irradiation spot area is large, the light is out of focus (defocused). Therefore, making the laser more defocused by control by the control unit 160 may be synonymous with making the laser irradiation spot area larger.

[0076] <Light source control method> Next, a method for controlling the operation mode will be described with reference to FIG. 6. FIG. 6 is a flowchart illustrating a method for controlling the operation mode according to the first embodiment. First, as shown in step S11, the control unit 160 sets the operation mode to the first mode. Next, as shown in step S12, the control unit 160 determines whether or not the optical device satisfies a predetermined condition set in advance. If the condition is not satisfied, the control unit 160 keeps the operation mode set to the first mode and executes the determination of step S12 again. If the condition is satisfied, the control unit 160 sets the operation mode to the second mode as shown in step S13.

[0077] Examples of the predetermined conditions in step S12 are described below. For example, in the first mode, the control unit 160 may determine whether or not the amount of attached matter adhering to the inner wall surface 116A is equal to or greater than a predetermined threshold by analyzing an image captured by the sensor 141, which is a camera. Here, because the target holder 110 is rotating, the attached matter appears in the captured image as a line having a different brightness from that of the target material 112. The control unit 160 determines whether or not the amount of attached matter on the target holder 110 is equal to or greater than a predetermined threshold by detecting the thickness of the line. If the control unit 160 determines in the first mode that the amount of attached matter on the target holder 110 is equal to or greater than the predetermined threshold, the control unit 160 may switch the operation mode from the first mode to the second mode as shown in step S13. The control unit 160 can make a similar determination not only on the brightness but also on the hue and saturation of the captured image.

[0078] The control unit 160 may also have a timer function. When the timer function detects that a predetermined time has elapsed since the time when the operation mode was switched to the first mode or the time when plasma was generated from the target material 112 in the first mode, the control unit 160 may switch the operation mode from the first mode to the second mode as shown in step S13.

[0079] When the operation mode is switched from the first mode to the second mode, the control unit 160 may execute the control relating to the scan amount in the β-axis direction or the defocus as described above.

[0080] The control unit 160 may identify the type or amount of the attachment by analyzing the image captured by the sensor 141, which is a camera. The type of the attachment may include, for example, the type (properties) of the attachment as well as the amount of the attachment, as described below. The control unit 160 may identify, as the type of attachment, at least one of the physical properties or chemical composition of the attachment, or the melting point of the attachment based on these. The control unit 160 may identify the type or amount of the attachment based on, for example, the brightness, hue, saturation, etc. of the captured image. The control unit 160 may also identify the type or amount of the attachment based on, for example, variations in surface roughness or reflectance indicated in the output value from the sensor 141. The control unit 160 is an example of an identification unit.

[0081] The plurality of modes may include a plurality of second modes with different control conditions, and the control unit 160 may determine one of the different second modes as the mode to be executed based on the state of the identified adhesion matter. The control unit 160 executes this control in step S13.

[0082] As an example, the plurality of modes may include, as second modes, a first second mode (hereinafter, second mode A) in which the laser peak power density is a certain value, and a second second mode (hereinafter, second mode B) in which the laser peak power density is lower than that of second mode A. In this case, when the control unit 160 identifies that the type of adhesion is an adhesion having a melting point equal to or higher than a predetermined value, it determines that the mode to be executed is second mode A, and reduces the adhesion. On the other hand, when the control unit 160 identifies that the type of adhesion is an adhesion having a melting point lower than the predetermined value, it determines that the mode to be executed is second mode B, and reduces the adhesion.

[0083] As another example, the plurality of modes may include, as second modes, second mode A in which the laser is pulsed and second mode B in which the laser is continuously oscillated. In this case, when the control unit 160 identifies the type of adhesion as an adhesion having a melting point equal to or higher than a predetermined value, it determines the mode to be executed as second mode A and reduces the adhesion. On the other hand, when the control unit 160 identifies the type of adhesion as an adhesion having a melting point lower than a predetermined value, it determines the mode to be executed as second mode B and reduces the adhesion.

[0084] Furthermore, when the control unit 160 determines in step S13 that the amount of adhering matter on the inner wall surface 116A is equal to or greater than a predetermined threshold Th1, the control unit 160 may analyze the image captured by the sensor 141 or the output value of the sensor 141. Based on the analysis result, the control unit 160 further determines whether the amount of adhering matter on the inner wall surface 116A is equal to or greater than a threshold Th2 (Th2>Th1). If the amount of adhering matter is equal to or greater than the threshold Th2, the control unit 160 sets the second mode to the above-described second mode A. If the amount is equal to or greater than the threshold Th1 but less than Th2, the control unit 160 sets the second mode to the above-described second mode B. In second mode A, the peak power density of the cleaning laser irradiated onto the adhering matter is set higher than in second mode B.

[0085] In this way, the control unit 160 determines a different second mode from the plurality of second modes as the mode to be executed based on the identified state of the attached matter. Note that when there are multiple second modes with different control conditions, the number does not need to be limited to two, and there may be three or more second modes. Also, although the modes that are the plurality of second modes with different control conditions are referred to as second mode A and second mode B in the above example, they may also be referred to as third mode, fourth mode, etc. In this case, the third mode, fourth mode, etc. are modes that belong to the second mode.

[0086] <Optical equipment> Next, an optical device will be described, using an inspection device as an example of the optical device.

[0087] FIG. 7 is a configuration diagram illustrating an inspection apparatus 1 including a light source device 100 according to the first embodiment. As shown in FIG. 7, the inspection apparatus 1 includes an illumination optical system 200, an inspection optical system 300, a detector 410, and an image processing unit 420. The inspection apparatus 1 may further include the light source device 100. The inspection apparatus 1 is an apparatus that inspects a sample 500 for defects and the like using light L0 generated by the light source device 100 as illumination light L1. The sample 500 is, for example, an EUV mask. The sample 500 is not limited to an EUV mask, and may be a semiconductor substrate or the like.

[0088] The illumination optical system 200 includes an ellipsoidal mirror 210, an ellipsoidal mirror 220, and a drop mirror 230. The inspection optical system 300 includes a concave mirror with a hole 310, a convex mirror 320, a plane mirror 330, and a concave mirror 340. The concave mirror with a hole 310 and the convex mirror 320 form a Schwarzschild magnification optical system.

[0089] The light source device 100 generates illumination light L1. The illumination light L1 includes, for example, EUV light LE with a wavelength of 13.5 nm, which is the same as the exposure wavelength of the EUV mask that serves as the sample 500. Note that the illumination light L1 may include light other than EUV light.

[0090] In the light source device 100, a shutter 180 is provided near the location where the generated illumination light L1 is emitted. The shutter 180 is connected to a drive unit 150E, and its opening and closing are controlled in accordance with the operation of the drive unit 150E. The shutter 180 is provided in the optical path between the target material 112 and the sample 500, which is the object. Therefore, when the shutter 180 is in a closed state, light is not emitted from the light source device 100. On the other hand, when the shutter 180 is in an open state, light can be emitted from the light source device 100.

[0091] The control unit 160 controls the driving of the drive unit 150E, thereby controlling the opening and closing of the shutter 180. In the first mode, the control unit 160 opens the shutter 180, thereby allowing the illumination light L1 to illuminate the sample 500. On the other hand, in the second mode, the control unit 160 drives the shutter 180 to close it, thereby preventing the light from the light source device 100 from illuminating the sample 500. Therefore, even if light originating from the target material 112 is generated in the second mode, the control unit 160 can prevent the light from reaching the sample 500.

[0092] When the shutter 180 is in an open state, the illumination light L1 generated from the light source device 100 is reflected by the ellipsoidal mirror 210. The illumination light L1 reflected by the ellipsoidal mirror 210 travels while being narrowed, and is collected at a convergence point IF1. Therefore, the ellipsoidal mirror 210 reflects the illumination light L1 generated from the light source device 100 as convergent light. The convergence point IF1 is located at a position conjugate with an upper surface 510 of a sample 500 such as an EUV mask and a detection surface 411 of the detector 410.

[0093] After passing through the convergence point IF1, the illumination light L1 travels while diverging and is incident on a reflecting mirror such as the ellipsoidal mirror 220. Therefore, the illumination light L1 reflected by the ellipsoidal mirror 210 is incident on the ellipsoidal mirror 220 as divergent light via the convergence point IF1. The illumination light L1 incident on the ellipsoidal mirror 220 is reflected by the ellipsoidal mirror 220, travels while being narrowed, and is incident on the drop-in mirror 230. In other words, the ellipsoidal mirror 220 reflects the incident illumination light L1 as converging light. The ellipsoidal mirror 220 then causes the illumination light L1 to be incident on the drop-in mirror 230. The drop-in mirror 230 is disposed directly above the EUV mask. The illumination light L1 incident on and reflected by the drop-in mirror 230 is incident on the sample 500. Therefore, the drop-in mirror 230 reflects the illumination light L1 reflected by the ellipsoidal mirror 220 toward the sample 500, causing the illumination light L1 to be incident on the sample 500.

[0094] The ellipsoidal mirror 220 focuses the illumination light L1 onto the sample 500. The illumination optical system 200 is installed so that when the illumination light L1 illuminates the sample 500, an image of the light source device 100 is formed on the upper surface 510 of the sample 500. Therefore, the illumination optical system 200 provides critical illumination. In this manner, the illumination optical system 200 illuminates the sample 500, such as an EUV mask, using critical illumination by the illumination light L1 generated by the light source device 100.

[0095] The sample 500 is placed on a stage 520. Here, a plane parallel to the upper surface 510 of the sample 500 is defined as the δε plane, and a direction perpendicular to the δε plane is defined as the ζ axis direction. The illumination light L1 is incident on the sample 500 from a direction tilted from the ζ axis direction. That is, the illumination light L1 is incident obliquely and illuminates the sample 500.

[0096] The stage 520 is a three-dimensional drive stage having a drive unit 530. The drive unit 530 can illuminate a desired area of ​​the sample 500 by moving the stage 520 in the δε plane. Furthermore, the drive unit 530 can perform focus adjustment by moving the stage 520 in the ζ-axis direction.

[0097] Illumination light L1 from light source device 100 illuminates an inspection area of ​​sample 500. The inspection area illuminated by illumination light L1 is, for example, 0.5 mm square. Note that the inspection area is not limited to 0.5 mm square. Illumination light L1 is incident on sample 500 from a direction tilted with respect to the ζ-axis direction. Light from sample 500 illuminated by illumination light L1 is incident on perforated concave mirror 310. In the following, light from sample 500 illuminated by illumination light L1 will be described as reflected light L2. Note that light incident on perforated concave mirror 310 from sample 500 is not limited to reflected light L2 and may include diffracted light, etc. The reflected light L2 reflected by sample 500 is incident on perforated concave mirror 310. A hole 311 is provided at the center of perforated concave mirror 310. The perforated concave mirror 310 collects the reflected light L2 from the sample 500 and reflects the collected reflected light L2 as convergent light.

[0098] The reflected light L2 reflected by the perforated concave mirror 310 is incident on the convex mirror 320. The convex mirror 320 reflects the reflected light L2 reflected by the perforated concave mirror 310 toward the hole 311 in the perforated concave mirror 310. The reflected light L2 that passes through the hole 311 is incident on the plane mirror 330. The plane mirror 330 causes the reflected light L2 reflected by the convex mirror 320 to be incident as convergent light through the hole 311 in the perforated concave mirror 310. The reflected light L2 that is incident on the plane mirror 330 is reflected by the plane mirror 330. The reflected light L2 reflected by the plane mirror 330 travels while being narrowed and is collected at a convergence point IF2. Therefore, the plane mirror 330 reflects the incident reflected light L2 as convergent light. The convergence point IF2 is sometimes called an aperture stop. The convergence point IF2 is located at a position conjugate with the upper surface 510 of the sample 500 and the detection surface 411 of the detector 410.

[0099] After passing through the convergence point IF2, the reflected light L2 diverges as it travels and enters the concave mirror 340. Therefore, the reflected light L2 reflected by the plane mirror 330 as convergent light enters the concave mirror 340 as divergent light via the convergence point IF2. The concave mirror 340 reflects the incident reflected light L2 as convergent light toward the detector 410. The reflected light L2 reflected by the concave mirror 340 is detected by the detector 410. In this way, the inspection optical system 300 inspects the sample 500, which is the inspection target, using the light L1 extracted from the output optical system 130 of the light source device 100. In other words, the inspection optical system 300 collects the reflected light L2 from the sample 500 illuminated by the illumination light L1 and guides the collected reflected light L2 to the detector 410.

[0100] The detector 410 may include a TDI (Time Delay Integration) sensor. The detector 410 receives light from the sample 500 illuminated by the illumination light L1. The area on the sample 500 detected by the detector 410 is called a field of view 511. The detector 410 receives reflected light L2 from the field of view 511 illuminated by the illumination light L1. The field of view 511 may be included in the inspection area illuminated by the illumination light L1. The detector 410 acquires image data of the sample 500, such as an EUV mask. When the detector 410 includes a TDI sensor, the detector 410 includes a plurality of image sensors arranged in a line in one direction. The image sensors are, for example, CCDs (Charge Coupled Devices). Note that the image sensors are not limited to CCDs.

[0101] The image data of the sample 500 acquired by the detector 410 is output to the image processing unit 420 and processed in the image processing unit 420. The image processing unit 420 may be, for example, an information processing device such as a server device or a personal computer.

[0102] The reflected light L2 contains information about defects in the sample 500. The specularly reflected light of the illumination light L1 that is incident on the sample 500 from a direction tilted with respect to the Z-axis direction is detected by the inspection optical system 300. If a defect exists in the sample 500, the defect is observed as a dark image. This observation method is called bright-field observation. Note that the inspection device 1 may also cause the illumination light L1 to be incident on the sample 500 from the Z-axis direction and detected by the inspection optical system 300. If a defect exists in the sample 500, the defect is observed as a bright image. This observation method is called dark-field observation.

[0103] As described above, the inspection apparatus 1 of this embodiment includes the light source device 100 described above and an inspection optical system 300 that inspects an object to be inspected with the light L0 extracted from the output optical system 130. Note that while the inspection apparatus 1 has been described as an optical apparatus, the optical apparatus may also be an exposure apparatus. For example, an exposure apparatus includes the light source device 100 described above and an exposure optical system that exposes an object to light L0 extracted from the output optical system 130. The control unit 160 may drive the drive unit 150 so that the light L0 scans an exposure area on the object to be exposed.

[0104] As described above, the control unit 160 determines one of multiple operating modes to be executed. For example, the control unit 160 can switch between a first mode in which the sample 500 is illuminated by irradiating the target material 112 with a laser and a second mode in which the laser is irradiated to remove deposits on the surface of the target holder 110. Therefore, even if deposits are generated by irradiating the target material 112 with a laser, the light source device 100 can reduce and ultimately remove the deposits in the second mode. In this way, automatic removal of deposits can improve the efficiency of maintenance of the light source device 100. Furthermore, by executing the first mode under the control of the control unit 160 and then executing the second mode, the process from illuminating the target object to maintenance can be simplified. Therefore, the operation of the light source device 100 can be improved. Note that in the second mode, the laser may be irradiated not only to deposits on the surface of the target holder 110 but also to the target material 112.

[0105] Furthermore, in the second mode, the control unit 160 may increase the amount of laser scanning in the direction perpendicular to the rotation direction of the target holder 110 on the holding surface where the target holder 110 holds the target material 112, compared to the first mode. This makes it possible to reduce deposits over a wider area of ​​the holder.

[0106] Furthermore, the control unit 160 may set the laser irradiation state in the second mode to a more defocused state compared to the laser irradiation state in the first mode, thereby preventing excessive heat from being supplied to the target holder 110 in the second mode and damaging the container 111.

[0107] Furthermore, the control unit 160 may switch between opening and closing the shutter 180 in the first mode and the second mode. This makes it difficult for light originating from the target material 112 to reach the sample 500 even if light is generated in the second mode, thereby making it possible to suppress the occurrence of unexpected erroneous inspections.

[0108] The shutter 180 may be provided in the optical path up to the field of view 511 in the illumination optical system 200, instead of in the light source device 100. The control unit 160 of the light source device 100 or the control unit of the inspection device 1 controls the shutter 180, so that the opening and closing of the shutter 180 in the first mode and the second mode are controlled in the same manner as described above.

[0109] The shutter 180 is an example of an adjustment means for suppressing propagation of light generated from the light source device 100 to the sample 500, which is an object of interest. As an adjustment means other than the shutter 180, for example, an optical element such as a mirror or an actuator for changing the position and posture of a stage on which the sample 500 is placed may be provided in the inspection device 1. The control unit 160 drives the optical element or actuator in the second mode. As a result, even if light originating from the target material 112 is generated in the second mode, it is possible to suppress propagation of the light to the sample 500.

[0110] (Embodiment 2) A light source device according to embodiment 2 will be described. In this embodiment, a light source device having a different configuration from the light source device according to embodiment 1 will be described.

[0111] The control unit 160 of the light source device 100 may switch between an operating mode: a first mode in which the sample 500 is illuminated by irradiating the target material 112 in the chamber with a laser; and a second mode in which the laser is irradiated to both the target material 112 and the deposits adhering to the surfaces of the components in the chamber. In the second mode, the same laser is irradiated to the deposits and the target material 112. However, the multiple operating modes of the light source device 100 or the optical device may include operating modes other than the first and second modes.

[0112] The light source device 100 may include a target holder 110 that holds the target material 112, as in the first embodiment, or may not include the target holder 110. When the light source device 100 includes the target holder 110, for example, in the second mode, the control unit 160 may control the laser LS1 to irradiate both the target material 112 and deposits attached to the target holder 110 with a cleaning laser. However, in the second mode, the control unit 160 may also control the laser LS1 to irradiate deposits attached to other optical elements of the light source device 100 with the cleaning laser, rather than the target holder 110. When the light source device 100 does not include the target holder 110, for example, in the second mode, the control unit 160 may control the laser LS1 to irradiate both the target material 112 and deposits attached to optical elements in the chamber with the cleaning laser. The target holder 110 and the optical elements are examples of components in the chamber. The object whose surface is irradiated with the laser together with the target material 112 in the second mode may be a component other than the target holder 110 or the optical element.

[0113] In the first or second embodiment, the laser generator that outputs the cleaning laser in the second mode may be the laser LS1 that outputs the laser irradiated in the first mode, or may be a different laser generator (hereinafter also referred to as laser LS2). When the light source device has the laser LS2, the control unit 160 controls the laser LS1 to perform laser irradiation in the first mode, and controls the laser LS2 to perform laser irradiation in the second mode. The characteristics of the laser irradiated by the laser LS2 in the second mode are as described in the first embodiment.

[0114] The optical path from the laser LS1 to the target material 112 and the optical path from the laser LS2 to the adherent (or target material 112) may share a portion in common. For example, a common optical element such as a mirror 121 or a condenser lens 122 may be provided on both optical paths. However, the optical paths may not share a common optical element and may be non-overlapping.

[0115] In the first or second embodiment, when the operation mode is set to the second mode, if the control unit 160 determines that a predetermined condition different from the condition in step S12 of FIG. 6 is satisfied, the control unit 160 may transition the operation mode to the first mode. As a different predetermined condition, the control unit 160 may switch the operation mode from the second mode to the first mode when the position of plasma generated by irradiating the target material 112 with the cleaning laser coincides with a predetermined position in the second mode. The predetermined position refers to a position where the optical path of the light L0 generated by the plasma faces a direction suitable for the application of the light L0 (for example, a position where the optical path faces a direction suitable for illuminating the sample 500, which is the target object, with the light L0), and is a position pre-stored in memory. When the sensor 141 observes the generated plasma 127 as a bright spot, the control unit 160 determines whether the observed bright spot coincides with a predetermined position. This allows the control unit 160 to keep the operating mode in the second mode when the illumination light L1 is generated at an angle that is not suitable for inspection of the sample 500, thereby obtaining stable inspection results.

[0116] The control unit 160 may switch the operation mode from the second mode to the first mode when a predetermined switching condition is met. The predetermined switching condition may include, as described above, that the position of the plasma generated by irradiating the target material 112 with the cleaning laser coincides with a predetermined position. However, even if the position of the plasma generated by irradiating the target material 112 with the cleaning laser coincides with the predetermined position in the second mode, the control unit 160 may not switch the operation mode from the second mode to the first mode if other conditions are not met (for example, if the amount of attached matter has not been reduced). The case where the amount of attached matter has not been reduced includes a case where the control unit 160 determines that the amount of attached matter attached to the inner wall surface 116A, as indicated by the image captured by the sensor 141 or the output value, is less than a predetermined threshold. The amount of attached matter reduced indicates the difference between the amount of attached matter detected in the most recent measurement by the sensor 141 and the amount of attached matter detected in the previous measurement by the sensor 141 (or when the execution mode is set to the second mode and cleaning of the attached matter is started). In this way, the predetermined switching condition may include both the fact that the amount of adhesion has been reduced and the fact that the position of the plasma generated by irradiating the target material 112 with the cleaning laser matches the predetermined position.

[0117] The program defining the operations executed by the control unit 160 of the light source device 100 includes instructions or software code that, when loaded into a computer, causes the computer to perform one or more functions described in the embodiments. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, computer-readable media or tangible storage media include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, compact disc read-only memory (CD-ROM), digital versatile disk (DVD), Blu-ray (registered trademark) disc or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage, or other magnetic storage devices. The program may also be transmitted on a transient computer-readable medium or communication medium. By way of example and not limitation, transient computer-readable media or communication media include electrical, optical, acoustic, or other forms of propagated signals. The transient computer-readable medium or communication medium may provide the program to the computer via a wired communication path, such as an electric wire or optical fiber, or via a wireless communication path.

[0118] Although the embodiments of the present disclosure have been described above, the present disclosure includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the above-described embodiments. Furthermore, the configurations of Embodiments 1 and 2 may be combined as appropriate. [Explanation of symbols]

[0119] 1. Inspection equipment 100 Light source device 110 Target holder 111 Container 111a opening 112 Target material 113 Bottom 114 Cylindrical part 115 bottom 116A Inner wall 116B Exterior wall surface 117 Groove 118 Heater 119 Debris Shield 120 Input optical system 121 Mirror 122 Condenser Lens 127 Plasma 130 Output Optical System 131 Collector Mirror 140 Acquisition Department 141 Sensors 150 Drive unit 160 control section 170 Focus adjustment mechanism 200 Illumination optical system 210 Ellipsoidal Mirror 220 Ellipsoidal Mirror 230 Drop-in mirror 300 Inspection Optical System 310 Perforated concave mirror 311 holes 320 Convex mirror 330 plane mirror 340 concave mirror 410 detector 411 Detection surface 420 Image Processing Unit 500 samples 510 Top surface 511 Field of view 520 Stage 530 Drive Unit BS beam spot FOV field of view L0 light L1 illumination light L2 reflected light LE EUV light LR excitation light LS1 Laser OP1 First optical member OP2 Second optical element P1 position PS irradiation position R rotation axis

Claims

1. A control device for an optical device including a light source device, which determines an execution mode from among a plurality of modes, The plurality of modes include a first mode in which the light source device illuminates an object with illumination light generated by irradiating a target material held by a holder with a laser, and a second mode in which the light source device reduces deposits adhering to the surface of the holder by irradiating the deposits with a laser. Control device.

2. A control device for a light source device that determines a mode to be executed from a plurality of modes, The plurality of modes include a first mode in which light is generated by irradiating a laser onto a target material held by a holder, and a second mode in which a laser is irradiated onto a deposit adhering to a surface of the holder, thereby reducing the deposit. Control device.

3. A control device for an optical device including a light source device, which determines an execution mode from among a plurality of modes, The plurality of modes include a first mode in which the light source device illuminates an object with illumination light generated by irradiating a target material in a chamber with a laser, and a second mode in which the light source device reduces deposits adhering to a surface of a component in the chamber by irradiating the laser onto the deposits, and in the second mode, the laser irradiated onto the deposits is also irradiated onto the target material. Control device.

4. A control device for a light source device that determines a mode to be executed from a plurality of modes, The plurality of modes include a first mode in which light is generated by irradiating a target material in a chamber with a laser, and a second mode in which deposits attached to a surface of a component in the chamber are reduced by irradiating the laser onto the deposits, and in the second mode, the laser irradiated onto the deposits is also irradiated onto the target material. Control device.

5. the laser scanning is not performed in the first mode and is performed in the second mode, or the laser scanning is performed in the first mode and the second mode, and the amount of scanning by the laser is larger in the second mode than in the first mode; The control device according to any one of claims 1 to 4.

6. The laser irradiation state in the second mode is in a defocused state compared to the laser irradiation state in the first mode. The control device according to any one of claims 1 to 4.

7. when a predetermined switching condition is met, the execution mode is switched from the second mode to the first mode; the predetermined switching condition includes that, when the execution mode is the second mode, the position of the plasma generated by irradiating the laser coincides with a predetermined position. The control device according to any one of claims 1 to 4.

8. the light source device includes an identification unit that identifies the type of the attachment, the plurality of modes include a plurality of second modes with different control conditions; determining one of the second modes as the mode to be executed based on the state of the attachment identified by the identification unit; The control device according to any one of claims 1 to 4.

9. the light source device includes a laser generator that outputs a laser in the first mode and a laser in the second mode, controlling the laser generator according to the mode to be executed; The control device according to any one of claims 1 to 4.

10. The light source device is a first laser generator that outputs a laser in the first mode; a second laser generator that outputs a laser in the second mode; an optical element through which the laser generated by the first laser generator and the laser generated by the second laser generator pass, controlling the first laser generator and the second laser generator according to the execution mode; The control device according to claim 1 or 2.

11. the light source device includes the holding portion that rotates around a rotation axis, When the execution mode is the first mode, the light source device is caused to irradiate the laser onto the target material held by the holding unit. The control device according to claim 1 or 2.

12. the optical device includes an adjustment means for suppressing propagation of light generated from the light source device to the object; driving the adjusting means when the execution mode is the second mode; The control device according to claim 1 or 3.

13. A light source device that generates light by irradiating a molten target material with a laser, a control unit that irradiates a laser beam onto deposits adhering to the surface of the holder of the target material, thereby reducing the deposits; Light source device.

14. The holding portion rotates around a rotation axis. The light source device according to claim 13.

15. A light source device that generates light by irradiating a target material in a chamber with a laser, a control unit that irradiates a laser beam onto deposits adhering to a surface of a component in the chamber to reduce the deposits, and the laser beam irradiated onto the deposits is also irradiated onto the target material; Light source device.

16. a first step of irradiating a target material held by a holder with a laser to generate illumination light, thereby illuminating an object; a second step of irradiating the deposits on the surface of the holding portion with a laser to reduce the deposits; a third step of switching between the first step and the second step. A method for controlling an optical device.

17. a first step of generating light by irradiating a laser onto a target material held by a holding unit; a second step of irradiating the deposits on the surface of the holding portion with a laser to reduce the deposits; a third step of switching between the first step and the second step. A method for controlling a light source device.

18. a first step of illuminating an object with illumination light generated by irradiating a target material in a chamber with a laser; a second step of irradiating a laser beam onto deposits adhering to surfaces of components within the chamber to reduce the deposits; a third step of switching between the first step and the second step; In the second step, the laser irradiated onto the deposit is also irradiated onto the target material. A method for controlling an optical device.

19. a first step of generating light by irradiating a target material in a chamber with a laser; a second step of irradiating a laser beam onto deposits adhering to surfaces of components within the chamber to reduce the deposits; a third step of switching between the first step and the second step; In the second step, the laser irradiated onto the deposit is also irradiated onto the target material. A method for controlling a light source device.

20. a first step of generating light by irradiating a molten target material with a laser; a second step of irradiating a laser beam onto the deposits adhering to the surface of the holder of the target material to reduce the deposits; a third step of switching between the first step and the second step. A method for controlling a light source device.

21. a first step of irradiating a target material held by a holder with a laser to generate illumination light, thereby illuminating an object; a second step of irradiating the deposits on the surface of the holding portion with a laser to reduce the deposits; a third step of switching between the first step and the second step; A program that causes an optical device to execute the above.

22. a first step of generating light by irradiating a laser onto a target material held by a holding unit; a second step of irradiating the deposits on the surface of the holding portion with a laser to reduce the deposits; a third step of switching between the first step and the second step; A program that causes a light source device to execute the above.

23. a first step of illuminating an object with illumination light generated by irradiating a target material in a chamber with a laser; a second step of irradiating a laser beam onto deposits adhering to surfaces of components within the chamber to reduce the deposits; a third step of switching between the first step and the second step, In the second step, the laser irradiated onto the deposit is also irradiated onto the target material. program.

24. a first step of generating light by irradiating a target material in a chamber with a laser; a second step of irradiating a laser beam onto deposits adhering to surfaces of components within the chamber to reduce the deposits; a third step of switching between the first step and the second step; In the second step, the laser irradiated onto the deposit is also irradiated onto the target material. program.

25. a first step of generating light by irradiating a molten target material with a laser; a second step of irradiating a laser beam onto the deposits adhering to the surface of the holder of the target material to reduce the deposits; a third step of switching between the first step and the second step; A program that causes a light source device to execute the above.

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