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 Art

[0002] Patent Document 1 describes a light source device that removes debris adhering to the surface of an optical component installed in a chamber by irradiating the optical component with cleaning pulsed laser light.

[0003] Patent Document 2 describes a light generation device that changes the optical conditions of a laser with which a target member is irradiated, and irradiates debris adhering to an optical system with the laser. Prior Art Documents Patent Documents

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2010-186995 Patent Document 2 Japanese Unexamined Patent Publication No. 2005-235959 Summary of the Invention Problems to be Solved by the Invention

[0005] As described above, Patent Documents 1 and 2 disclose devices that attempt to remove debris using a laser. However, in Patent Documents 1 and 2, the locations where debris can be removed are limited.

[0006] In view of the above 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 Problems

[0007] The control device for an optical device according to this disclosure is a control device for an optical device equipped with a light source 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 illuminates an object with illumination light generated by irradiating a target material held by a holding part with a laser, and a second mode in which the light source device reduces deposits attached to the surface of the holding part by irradiating the deposits with a laser.

[0008] The control device for a light source device according to this disclosure is a control device for a light source device that determines a mode to be executed from among a plurality of modes. The plurality of modes include a first mode in which light is generated by irradiating a target material held by a holding part with a laser, and a second mode in which deposits attached to the surface of the holding part with a laser to reduce the deposits.

[0009] The control device for an optical device according to this disclosure is a control device for an optical device that includes a light source device for determining 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 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 attached to the surface of components in the chamber by irradiating the deposits with a laser, wherein in the second mode, the laser irradiated on the deposits is also irradiated on the target material.

[0010] The control device for a light source device according to this disclosure is a control device for a light source device that determines a mode to be executed from among 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 the surface of components in the chamber are reduced by irradiating the deposits attached to the surface of the components in the chamber with a laser, wherein in the second mode, the laser irradiated to the deposits is also irradiated to the target material.

[0011] The control device may perform the laser scan in the second mode but not in the first mode, or it may perform the laser scan in both the first and second modes, and in the second mode, the amount scanned by the laser may be larger compared to the first mode.

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

[0013] The control device may switch the execution mode from the second mode to the first mode when predetermined switching conditions are met. The predetermined switching conditions may include the position of the plasma generated by the irradiation of the laser when the execution mode is the second mode matching a predetermined position.

[0014] The above light source device may include an identification unit for identifying the form of the deposit. The plurality of modes include a plurality of second modes with 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 form of the deposit identified by the identification unit.

[0015] The above light source device may include a laser generator that outputs a laser in the first mode and a laser in the second mode. The above 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 being executed.

[0017] The above light source device may include a holding part that rotates around a rotation axis. When the mode to be executed is the first mode, the control device may cause the light source device to irradiate the target material held by the holding part with the laser.

[0018] The optical device may include adjustment means to suppress the propagation of light generated from the light source to the object. The control device may drive the adjustment means when the mode being executed is the second mode.

[0019] The light source device according to this disclosure is a light source device that generates light by irradiating a molten target material with a laser, and includes a control unit that reduces deposits attached to the surface of the holding portion of the target material by irradiating the deposits with a laser.

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

[0021] The light source device according to this disclosure is a light source device that generates light by irradiating a target material in a chamber with a laser. The light source device includes a control unit that reduces deposits attached to the surface of components in the chamber by irradiating the deposits with a laser, and the laser irradiated on the deposits is also irradiated on the target material.

[0022] The control method for the optical device according to this disclosure comprises: a first step of illuminating an object with illumination light generated by irradiating a target material held by a holding part with a laser; a second step of reducing deposits attached to the surface of the holding part by irradiating the deposits with a laser; and a third step of switching between the first step and the second step.

[0023] A control method for a light source device according to the present disclosure comprises: a first step of generating light by irradiating a target material held by a holding unit with a laser; a second step of reducing deposits by irradiating the deposits adhering to a surface of the holding unit with a laser; and a third step of switching between the first step and the second step.

[0024] A control method for an optical device according to the present disclosure comprises: 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 by irradiating the 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 that irradiates the deposits also irradiates the target material.

[0025] A control method for a light source device according to the present disclosure comprises: a first step of generating light by irradiating a target material in a chamber with a laser; a second step of reducing deposits by irradiating the 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 that irradiates the deposits also irradiates the target material.

[0026] A control method for a light source device according to the present disclosure comprises: a first step of generating light by irradiating a molten target material with a laser; a second step of reducing deposits by irradiating the deposits adhering to a surface of a holding unit for the target material with a laser; and a third step of switching between the first step and the second step.

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

[0028] The program relating to this disclosure causes a light source device to perform the following steps: a first step of generating light by irradiating a target material held by a holding part with a laser; a second step of reducing deposits attached to the surface of the holding part by irradiating the deposits with a laser; and a third step of switching between the first step and the second step.

[0029] The program relating to this disclosure causes an optical device to perform 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 attached to the surface of components in the chamber by irradiating the deposits with a laser; and a third step of switching between the first and second steps. In the second step, the laser irradiated on the deposits is also irradiated on the target material.

[0030] The program relating to this disclosure causes a light source device to perform the following steps: a first step of generating light by irradiating a target material in a chamber with a laser; a second step of reducing deposits attached to the surface of components in the chamber by irradiating the deposits with a laser; and a third step of switching between the first and second steps. In the second step, the laser irradiated to the deposits is also irradiated to the target material.

[0031] The program relating to this disclosure causes a light source device to perform the following steps: a first step of generating light by irradiating a molten target material with a laser; a second step of reducing deposits attached to the surface of the holding portion of the target material by irradiating the deposits with a laser; and a third step of switching between the first step and the second step. [Effects of the Invention]

[0032] According to this disclosure, the operation and maintenance of the equipment can be made more efficient. [Brief explanation of the drawing]

[0033] [Figure 1] This is a cross-sectional view illustrating a light source device according to Embodiment 1. [Figure 2] This is a perspective view illustrating a container serving as a target holder in the light source device according to Embodiment 1. [Figure 3] This is a plan view illustrating a light source device according to Embodiment 1. [Figure 4] This figure illustrates a focus adjustment mechanism according to Embodiment 1. [Figure 5] This figure illustrates the acquisition unit, drive unit, and control unit in a light source device according to Embodiment 1. [Figure 6] This flowchart illustrates a control method for the operating mode according to Embodiment 1. [Figure 7] This is a diagram illustrating an inspection apparatus equipped with a light source device according to Embodiment 1. [Modes for carrying out the invention]

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

[0035] (Embodiment 1) A light source device according to Embodiment 1 will now 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 it may be placed in the vicinity of the optical device as a separate unit. When the optical device is an inspection device, the light source device generates illumination light to illuminate the object to be inspected in the inspection device. When the optical device is an exposure device, the light source device generates exposure light to expose the object to be exposed in the exposure device.

[0036] The light source device generates light such as illumination light and exposure light by irradiating a target material held in a target holding section with excitation light. In the following Embodiment 1, as an example of a light source device, an example in which a liquid target material is held in a target holding section including a container such as a crucible is described. However, the target holding section may include a cylindrical drum, a tape-shaped structure, etc., instead of a container such as a crucible. For example, a solid target material is held in the drum. Here, the target holding section 110 may be housed in a chamber in which the inside is a vacuum state. In yet another example, the light source device may use a tape-shaped target material, or a target material that is dropped or ejected in droplet form. In other words, the target holding section is not necessarily required in the configuration of the light source device. Plasma is generated in the target material when it is irradiated with EUV light, as described later. At least the location in the target material where plasma is generated may be provided in a chamber in which the inside is a vacuum state. In this case, the optical elements of the light source device 100 described later may be provided in the chamber.

[0037] Figure 1 is a cross-sectional view illustrating a light source device 100 according to Embodiment 1. Figure 2 is a perspective view illustrating a container 111 as a target holding unit 110 in the light source device 100 according to Embodiment 1. Figure 3 is a plan view illustrating a light source device 100 according to Embodiment 1. In Figure 3, some components are omitted. As shown in Figures 1 to 3, the light source device 100 includes a target holding unit 110, an input optical system 120, an output optical system 130, an acquisition unit 140, a sensor 141, a drive unit 150, and a control unit 160. In Figure 1, the drive unit 150A is connected to the mirror 121, and the drive unit 150B is connected to the collector mirror 131. However, the drive unit does not necessarily need to be connected to all of these optical components. Also, to avoid making the diagram complicated, the control unit 160 is connected to only some components, but it may be connected to other components as well. The control unit 160 is a control device including one or more processors (processing devices). The processor is connected to memory (not shown) and controls the operation performed by the light source device 100 by reading and executing computer programs from memory. Details of this control will be described later.

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

[0039] Memory consists of volatile memory, non-volatile memory, or a combination thereof. There is no limit to one memory module; multiple modules may be provided. Volatile memory may include, for example, RAM (Random Access Memory) such as DRAM (Dynamic Random Access Memory) and SRAM (Static Random Access Memory). Non-volatile memory may include, for example, ROM (Read Only Memory) such as PROM (Programmable Random Only Memory) and EPROM (Erasable Programmable Read Only Memory), flash memory, or SSD (Solid State Drive).

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

[0041] Furthermore, memory may include not only memory located outside the processor, but also memory built into the processor. Memory may also include storage located separately from the processors that make up 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 in the light source device 100 execute one or more programs that include a set of instructions for causing a computer to perform the algorithm described with reference to the drawings. The execution of these programs enables the following information processing.

[0043] The target holding section 110 holds the target material 112. The target holding section 110 includes a container 111, such as a crucible. The container 111 can hold a metal that has been heated from a solid state to a liquid state (i.e., molten). Hereinafter, the metal in a liquid state will also be referred to as molten metal. The container 111 holds the target material 112, such as molten metal, which 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 section 110 is not limited to the container 111, but may also be a cylindrical drum. In that case, the target holding section 110 holds the target material 112 by fixing the solid target material 112, such as xenon (Xe), which is frozen on the surface of the drum.

[0045] The target material 112 may contain molten metal. The target material 112 is not limited to molten metal held in the container 111; it may also be a solid metal, a liquid droplet, or any other substance that generates plasma 127 upon irradiation with excitation light LR. The molten metal may be, for example, molten tin (Sn) or lithium (Li), but is not limited to tin or lithium as long as it generates plasma 127 upon irradiation with excitation light LR.

[0046] The container 111 has a rotation axis R and rotates about the rotation axis R. The container 111 is, for example, cylindrical with one opening closed. The closed portion of the container 111 is called the bottom 113. The cylindrical portion of the container 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. Note that the container 111 may include shapes other than those described above, as long as it can hold molten metal.

[0047] The target holding section 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, which is formed to surround the rotation axis R, may include a cylindrical portion at a constant distance from the rotation axis R, or it may include a mortar-shaped portion that widens outward towards the top. For example, the mortar-shaped portion of the inner wall surface 116A may be connected to a groove 117.

[0048] The light source device 100 may include a heater 118 and a debris shield 119 in addition to the target holding unit 110. Heating by the heater 118 can form a target material 112 such as molten metal inside the container 111. The debris shield 119 is positioned at the opening 111a of the container 111 so as to cover the target material 112.

[0049] As the container 111 rotates around its axis of rotation R, the target material 112 also rotates around the axis of rotation R. As shown in Figure 3, for example, at time t1, the target material 112 is located at position P1 facing the sensor 141. As the container 111 rotates, at time t2, the target material 112 moves to the irradiation position PS, where the excitation light LR irradiates. In this way, the target holding unit 110 moves the target material 112 to the irradiation position PS, where the excitation light LR irradiates, as the target holding unit 110 moves (i.e., rotates).

[0050] The input optical system 120 includes a first optical element OP1. The first optical element OP1 irradiates the target material 112 with excitation light LR. The first optical element OP1 includes, for example, at least one of a mirror 121 and a focus adjustment mechanism 170. Note that the first optical element OP1 is not limited to the mirror 121 and the focus adjustment mechanism 170, as long as it is an optical element 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 component OP1 irradiates the target material 112 with 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 component OP1 irradiates the excitation light LR at an incident angle tilted to the surface of the irradiation position PS to which the excitation light LR is irradiated. By irradiating the excitation light LR at such an inclined angle, the effect of debris on optical components, including the collector mirror 131, can be suppressed. The reason why the effect of debris on optical components such as the collector mirror 131 can be suppressed will be explained below.

[0052] When excitation light LR is irradiated from a direction perpendicular to the surface of the target material 112, debris scatters in all directions, centering on the direction perpendicular to the surface. This may cause debris to adhere to the collector mirror 131 facing the irradiation position PS. On the other hand, when 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 holding unit 110, that is, when 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, the direction in which the debris scatters speed The angular velocity in the rotational direction of the container 111 is added. As a result, the debris can be further scattered in the reflection direction of the excitation light LR. In this way, the effect of the debris on optical components such as the collector mirror 131 can be suppressed.

[0053] The mirror 121 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 piezo steering mirror. Note that the mirror 121 is not limited to a piezo steering mirror, but may include a galvanometer mirror, a polygon mirror, etc., as long as it can reflect the excitation light LR toward the target material 112. The focusing lens 122 in the focus adjustment mechanism 170, described later, focuses the excitation light LR toward 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 receive excitation light LR from a laser LS1 installed separately from the light source device 100. The excitation light LR is, for example, laser light including IR light. The excitation light LR may irradiate the target material 112 by controlling the oscillation and stopping of the control unit 160. For example, the excitation light LR is reflected by the mirror 121 and focused by the 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 element OP2. The second optical element OP2 extracts light L0 generated by irradiating the target material 112 with excitation light LR from the light source device 100. The second optical element OP2 includes, for example, a collector mirror 131. However, the second optical element OP2 is not limited to a collector mirror 131, as long as it is an optical element that extracts light L0 generated by irradiating the target material 112 with 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 excitation light LR. The collector mirror 131 reflects, for example, EUV (Extreme ultraviolet lithography) light LE generated by irradiation with excitation light LR. That is, light L0 may include EUV light LE. EUV light LE is generated from the plasma 127 that is generated when excitation light LR is irradiated onto the target material 112. 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 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 the sensor 141 and acquires the surface position of the target material 112 measured by the sensor 141 from the sensor 141. The acquisition unit 140 acquires the surface position of the target material 112 at the irradiation position PS where the excitation light LR irradiates the target material 112. The acquisition unit 140 may acquire the surface position measured by the sensor 141 at the irradiation position PS, or, as described later, may predict the surface position at the irradiation position PS from the surface position measured by the sensor 141 at a peripheral position. In addition, the acquisition unit 140 may predict the surface position of the target material 112 considering the inclination and vibration of the target holding unit 110 with respect to its rotation axis.

[0058] The acquisition unit 140 may be a separate unit from the sensor 141, or it 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 4-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 other sensors with the sensor 141, such as a displacement meter. This allows the other sensors 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 it 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. Alternatively, the acquisition unit 140 may acquire the surface position of the target material 112 based on the thickness from the inner wall surface 116A of the molten metal. In the case where the target material 112 is a 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 top surface (surface layer) of the drum, as well as the tilt and vibration of the drum.

[0060] The acquisition unit 140 may acquire surface positions at peripheral positions other than the irradiation position PS. Peripheral positions include parts 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 PS of the irradiation position from the surface positions of peripheral positions acquired from the sensor 141. Specifically, the acquisition unit 140 predicts the surface position PS of the irradiation position PS from the surface position at a position in front of the irradiation position PS with respect to the direction of movement of the target holding unit 110. At this time, by considering the movement speed (rotation speed) of the target holding unit 110, the surface position at the irradiation position PS at the time the excitation light reaches the irradiation position PS (irradiation time) can be predicted. In this way, the acquisition unit 140 acquires the surface position PS of the irradiation position PS by predicting the surface position PS.

[0061] If the sensor 141 is placed opposite the irradiation position PS in order to measure and obtain the surface position of the irradiation position PS, there is a risk of being affected by debris. Also, since plasma 127 is generated at the irradiation position PS, there is a risk that the surface position cannot be accurately obtained. Therefore, the sensor 141 is placed opposite the irradiation position PS at a peripheral position away from it. This suppresses the influence of debris and improves the accuracy of surface position measurement. For example, the sensor 141 may be placed opposite the irradiation position PS at position P1 on the opposite side of the rotation axis R. In addition, the sensor 141 may be placed opposite a peripheral position other than position P1 if the influence of debris can be reduced.

[0062] Figure 4 is an example of a focus adjustment mechanism 170 in a light source device 100 according to Embodiment 1. As shown in Figure 4, the focus adjustment mechanism 170 includes a condensing lens 122 and a drive unit 150C. In Figure 4, the drive unit 150C is connected to the condensing lens 122.

[0063] The focusing lens 122 focuses 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 drive unit 150C so that the focusing lens 122 moves either in the forward or backward direction of the laser beam path. This allows the laser output by the laser LS1 to be defocused, as described later.

[0064] Figure 5 is a diagram illustrating the acquisition unit 140, drive unit 150, and control unit 160 in the light source device 100 according to Embodiment 1. As mentioned above, the position of the sensor 141 is not limited to a position opposite the irradiation position PS, but may also be a position opposite a peripheral position such as position P1. As shown in Figure 5, the drive units 150A to C change the position of the focusing point of at least one of the first optical member OP1 and the second optical member OP2. The drive units 150A to C are, for example, actuators.

[0065] The drive units 150A and C drive the first optical element OP1 to change the irradiation direction of the excitation light LR. For example, if the first optical element OP1 is a mirror 121, the drive unit 150A performs a beam scan by changing the angle of the mirror 121 with respect to the excitation light LR. Specifically, the drive unit 150A changes the reflective 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 the mirror 121 is a piezo steering mirror, the drive unit 150A may include a drive mechanism provided in the piezo steering mirror. Also, if the mirror 121 is a galvanometer mirror, polygon mirror, etc., the drive unit 150A may be a drive mechanism provided in the galvanometer mirror, polygon mirror, etc. Furthermore, if there is another actuator with a short response time and good controllability, the drive unit 150A may be used instead.

[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 drive unit 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 drive unit 150A moves the bright spot at high speed to perform beam shaving. Therefore, if the optical device is an inspection device, the uniformity and availability on the detector of the inspection device can be improved. The drive unit 150A may also change the position of the focal point in two axes on the surface of the target material 112 at the irradiation position PS.

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

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

[0070] The deposits are generated when the target material 112 is irradiated with excitation light LR and plasma is produced, causing the environment to become high temperature and high pressure. The deposits are compounds derived from the material of the target material 112 and the material of the container 111 (or the cylindrical drum or tape-like structure that constitutes the target holding part 110). The deposits adhere to the 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 holding part 110 (container 111, drum, or tape, etc.). 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 prevent the generation of plasma at the desired position, potentially making it impossible to accurately illuminate the sample 500. However, by reducing, and ultimately removing, the deposits, such situations can be suppressed. Furthermore, by irradiating not only the deposits but also the target material 112 with the laser, the deposits become even easier to reduce due to the interaction between the deposits, the target material 112, and the laser.

[0071] Here, in the second mode, the control unit 160 may increase the amount by which the laser is scanned in a direction perpendicular to the rotation direction of the inner wall surface 116A on which the target material 112 is held by the target holding unit 110, compared to the first mode. The direction perpendicular to the rotation direction is the β-axis direction in Figure 2. For example, in the first mode, the control unit 160 may not scan the excitation light LR in the β-axis direction, and in the second mode, it may scan the cleaning laser by a predetermined amount in the β-axis direction. The control unit 160 can control the amount of scanning in the β-axis direction by controlling the drive unit 150A and changing the manner in which the angle of the mirror 121 with respect to the excitation light LR is swung between the first mode and the second mode. This explanation is as described above.

[0072] Furthermore, 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 in comparison with the irradiation state of the excitation light LR on the target material 112 in the first mode. The defocused state refers to a state where the laser is not focused on the irradiation target. That is, the spot diameter of the cleaning laser irradiated onto the deposit in the second mode is larger than the spot diameter of the excitation light LR irradiated onto the target material 112 in the first mode. Furthermore, the distance between the focal point of the cleaning laser in the second mode and the deposit is larger than the distance between the focal point of the excitation light LR in the first mode and the target material 112.

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

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

[0075] Furthermore, if D is the peak power density, PP is the peak power, and M is the laser irradiation spot area, then the relationship D = PP / M may be assumed to hold. Therefore, the control unit 160 can make the peak power density in the first mode different from the peak power density in the second mode by controlling the peak power and the laser irradiation spot area in the manner described above. When the laser irradiation spot area is small, the light is in focus, and when the laser irradiation spot area is large, the light is out of focus. Therefore, making the laser more defocused by the control unit 160 can be considered equivalent to making the laser irradiation spot area larger.

[0076] <Light source control method> Next, the method for controlling the operating mode will be explained with reference to Figure 6. Figure 6 is a flowchart illustrating the method for controlling the operating mode according to Embodiment 1. First, as shown in step S11, the control unit 160 sets the operating mode to the first mode. Next, as shown in step S12, the control unit 160 determines whether the optical device satisfies predetermined conditions. If the conditions are not met, the control unit 160 keeps the operating mode in the first mode and performs the determination in step S12 again. If the conditions are met, the control unit 160 sets the operating mode to the second mode, as shown in step S13.

[0077] An example of the predetermined conditions in step S12 is shown below. For example, in the first mode, the control unit 160 may determine whether or not a certain amount of deposits are adhering to the inner wall surface 116A by analyzing the image captured by the sensor 141, which is a camera. Here, since the target holding unit 110 is rotating, the deposits appear in the captured image as lines having a different brightness than the target material 112. The control unit 160 determines whether or not the amount of deposits on the target holding unit 110 is above a predetermined threshold by detecting the thickness of these lines, etc. If the control unit 160 determines in the first mode that the amount of deposits on the target holding unit 110 is above a predetermined threshold, it may switch the operation mode from the first mode to the second mode, as shown in step S13. The control unit 160 can make similar determinations regarding hue and saturation, not just brightness, in the captured image.

[0078] Furthermore, the control unit 160 may also have a timer function. When the control unit 160 detects that a predetermined time has elapsed, starting from the time it transitions to the first mode, or from the time plasma is generated from the target material 112 in the first mode, using the timer function, it may switch the operating mode from the first mode to the second mode, as shown in step S13.

[0079] Furthermore, when the control unit 160 switches the operating mode from the first mode to the second mode, it may perform control of the scan amount in the β-axis direction or defocus as described above.

[0080] The control unit 160 may identify the characteristics of the deposits by analyzing the images captured by the sensor 141, which is a camera. The characteristics of the deposits include, for example, the type (properties) of the deposits, as well as the amount of deposits, as will be described later. The control unit 160 may identify at least one of the following as the type of deposits: for example, the physical properties of the deposits, the chemical composition, or the melting point of the deposits based on these. The control unit 160 may identify characteristics such as the type or amount of deposits based on, for example, the brightness, hue, saturation, etc., in the captured image. Alternatively, the control unit 160 may identify characteristics such as the type or amount of deposits based on, for example, fluctuations in surface roughness or reflectance indicated by the output values ​​from the sensor 141. The control unit 160 is an example of an identification unit.

[0081] Multiple modes may include multiple second modes with different control conditions, and the control unit 160 may determine which of the different second modes to execute based on the characteristics of the identified deposit. The control unit 160 executes this control in step S13.

[0082] For example, the multiple modes may include a first second mode (hereinafter referred to as second mode A) in which the laser's peak power density is set to a certain value, and a second second mode (hereinafter referred to as second mode B) in which the laser's peak power density is smaller than that of second mode A. In this case, if the control unit 160 identifies that the type of deposit is one with a melting point above a predetermined value, it determines that the mode to be executed is second mode A and performs deposit reduction. On the other hand, if the control unit 160 identifies that the type of deposit is one with a melting point below a predetermined value, it determines that the mode to be executed is second mode B and performs deposit reduction.

[0083] As another example, the multiple modes may include a second mode A in which the laser is pulsed, and a second mode B in which the laser is continuously waved. In this case, if the control unit 160 identifies that the type of deposit is one with a melting point above a predetermined value, it determines that the mode to be executed is second mode A and performs deposit reduction. On the other hand, if the control unit 160 identifies that the type of deposit is one with a melting point below a predetermined value, it determines that the mode to be executed is second mode B and performs deposit reduction.

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

[0085] In this way, the control unit 160 determines a different second mode from among the multiple second modes to be executed based on the identified characteristics of the deposit. Note that when there are multiple second modes with different control conditions, the number is not limited to two; there may be three or more second modes. In the example above, each of the multiple second modes with different control conditions is referred to as second mode A, second mode B, etc., but they may also be referred to as third mode, fourth mode, etc. In this case, the third mode, fourth mode, etc., are modes belonging to the second mode.

[0086] <Optical equipment> Next, we will explain optical devices. In the following explanation, we will use an inspection device as an example of an optical device.

[0087] Figure 7 is a diagram illustrating an inspection apparatus 1 equipped with a light source device 100 according to Embodiment 1. As shown in Figure 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 a light source device 100. The inspection apparatus 1 is a device that uses light L0 generated by the light source device 100 as illumination light L1 to inspect defects, etc., in a sample 500. The sample 500 is, for example, an EUV mask. Note that the sample 500 is not limited to an EUV mask, but may also be a semiconductor substrate, etc.

[0088] The illumination optical system 200 includes an ellipsoidal mirror 210, an ellipsoidal mirror 220, and a recessed mirror 230. The inspection optical system 300 includes a perforated concave mirror 310, a convex mirror 320, a plane mirror 330, and a concave mirror 340. The perforated concave mirror 310 and the convex mirror 320 constitute a Schwarzschild magnifying optical system.

[0089] The light source device 100 generates illumination light L1. 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 will become the sample 500. However, illumination light L1 may also include light other than EUV light.

[0090] In the light source device 100, a shutter 180 is provided near the point from which 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 to be illuminated. Therefore, when the shutter 180 is closed, no light is emitted from the light source device 100. On the other hand, when the shutter 180 is open, light can be emitted from the light source device 100.

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

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

[0093] The illumination light L1, after passing through the convergence point IF1, spreads out as it travels and enters a reflecting mirror such as the ellipsoidal mirror 220. Therefore, the illumination light L1 reflected by the ellipsoidal mirror 210 enters the ellipsoidal mirror 220 as divergent light via the convergence point IF1. The illumination light L1 that enters the ellipsoidal mirror 220 is reflected by the ellipsoidal mirror 220, travels while being narrowed, and enters the recessed mirror 230. In other words, the ellipsoidal mirror 220 reflects the incident illumination light L1 as converged light. The ellipsoidal mirror 220 then causes the illumination light L1 to enter the recessed mirror 230. The recessed mirror 230 is positioned directly above the EUV mask. The illumination light L1 that enters the recessed mirror 230 and is reflected enters the sample 500. Therefore, the recessed mirror 230 causes the illumination light L1 that was reflected by the ellipsoidal mirror 220 to enter the sample 500 by reflecting it back at the sample 500.

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

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

[0097] Illumination light L1 from the light source device 100 illuminates the inspection area of ​​the sample 500. The inspection area illuminated by illumination light L1 is, for example, 0.5 mm square. However, the inspection area is not limited to 0.5 mm square. Illumination light L1 is incident on the sample 500 from a direction inclined with respect to the ζ axis. The light from the sample 500 illuminated by illumination light L1 is incident on the perforated concave mirror 310. In the following, the light from the sample 500 illuminated by illumination light L1 will be described as reflected light L2. Note that the light incident on the perforated concave mirror 310 from the sample 500 is not limited to reflected light L2, but may also include diffracted light, etc. The reflected light L2 reflected by the sample 500 is incident on the perforated concave mirror 310. A hole 311 is provided in the center of the perforated concave mirror 310. The perforated concave mirror 310 focuses the reflected light L2 from the sample 500 and reflects the focused 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 towards the hole 311 of the perforated concave mirror 310. The reflected light L2 that has passed 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 on the perforated concave mirror 310 as focused light through the hole 311. The reflected light L2 that has been 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 focused at the convergence point IF2. Therefore, the plane mirror 330 reflects the incident reflected light L2 as focused light. The convergence point IF2 is sometimes called the aperture diaphragm. The convergence point IF2 is located in a position conjugate to the upper surface 510 of the sample 500 and the detection surface 411 of the detector 410.

[0099] After passing the convergence point IF2, the reflected light L2 spreads out as it travels and enters the concave mirror 340. Therefore, the concave mirror 340 receives the reflected light L2 that was reflected by the plane mirror 330 as converged light. Convergence point It is incident as divergent light via IF2. The concave mirror 340 reflects the incident reflected light L2 as focused light to 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 is taken from the output optical system 130 of the light source device 100. Lighting The sample 500 to be inspected is inspected with L1. 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] Detector 410 is TDI (Time Delay) Integration) may include a sensor. The detector 410 receives light from the sample 500 illuminated by illumination light L1. The area on the sample 500 detected by the detector 410 is called the field of view 511. The detector 410 receives reflected light L2 from the field of view 511 illuminated by illumination light L1. The field of view 511 may be included in the inspection area illuminated by illumination light L1. The detector 410 acquires image data of the sample 500, such as an EUV mask. If 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 It is a CCD device. Note that the image sensor is not limited to a CCD.

[0101] 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 an information processing device such as a server 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 incident on the sample 500 from a direction tilted with respect to the Z-axis is detected by the inspection optical system 300. If a defect exists in the sample 500, the defect will be observed as a dark image. This observation method is called bright-field observation. Alternatively, the inspection device 1 may incident the illumination light L1 on the sample 500 from the Z-axis direction and have it detected by the inspection optical system 300. If a defect exists in the sample 500, the defect will be observed as a bright image. This observation method is called dark-field observation.

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

[0104] As described above, the control unit 160 determines one mode to execute from among multiple operating modes. For example, the control unit 160 can switch between a first mode, which illuminates the sample 500 by irradiating the target material 112 with a laser, and a second mode, which reduces deposits on the surface of the target holding unit 110 by irradiating the deposits with a laser. Therefore, even if deposits are generated when the light source device 100 irradiates the target material 112 with a laser, these deposits can be reduced and eventually removed in the second mode. In this way, the automatic reduction of deposits makes the maintenance of the light source device 100 more efficient. Furthermore, by executing the first mode under the control of the control unit 160, and then the second mode, the process from illuminating the target object to maintenance is simplified. Therefore, the operation of the light source device 100 can be made more efficient. Note that in the second mode, the laser may be irradiated not only on the deposits on the surface of the target holding unit 110 but also on the target material 112.

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

[0106] Furthermore, the control unit 160 may set the laser irradiation state in the second mode to a defocused state compared to the laser irradiation state in the first mode. This prevents excessive heat from being supplied to the target holding unit 110 in the second mode, which could damage the container 111.

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

[0108] The shutter 180 may be located in the optical path up to the field of view 511 in the illumination optical system 200, rather than 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, thereby controlling the opening and closing of the shutter 180 in the first mode and the second mode in the same manner as described above.

[0109] The shutter 180 is an example of an adjustment means that suppresses the propagation of light generated from the light source device 100 to the sample 500, which is the object being inspected. Other adjustment means besides the shutter 180 may include, for example, an optical element such as a mirror, or an actuator that changes the position and orientation of the stage on which the sample 500 is placed, which may be provided in the inspection device 1. In the second mode, the control unit 160 drives the optical element or actuator. This makes it possible to suppress the propagation of light to the sample 500 even if light originating from the target material 112 is generated in the second mode.

[0110] (Embodiment 2) A light source device according to Embodiment 2 will be described. In this embodiment, the configuration of 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 two operating modes: 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 deposits adhering to the surface of the components in the chamber and the target material 112. In the second mode, the same laser is irradiated to both the deposits and the target material 112. However, the 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 or may not include a target holding unit 110 for holding the target material 112, as in Embodiment 1. If the light source device 100 includes a target holding unit 110, for example in the second mode, the control unit 160 may control the cleaning laser from the laser LS1 to irradiate both the target material 112 and the deposits attached to the target holding unit 110. However, in the second mode, the control unit 160 may control the cleaning laser to irradiate deposits attached to other optical elements of the light source device 100 instead of the target holding unit 110. If the light source device 100 does not include a target holding unit 110, for example in the second mode, the control unit 160 may control the cleaning laser from the laser LS1 to irradiate both the target material 112 and the deposits attached to the optical elements in the chamber. The target holding unit 110 and the optical elements are examples of components in the chamber. In the second mode, components other than the target holding part 110 and optical elements may be irradiated on the surface of the target material 112 with a laser.

[0113] In Embodiment 1 or 2, the laser generator that outputs the cleaning laser in the second mode may be laser LS1 that outputs the laser irradiated in the first mode, or it may be a different laser generator (hereinafter also referred to as laser LS2). When the light source device has laser LS2, the control unit 160 controls laser LS1 to perform laser irradiation in the first mode, and controls laser LS2 to perform laser irradiation in the second mode. The characteristics of the laser irradiated by laser LS2 in the second mode are as described in Embodiment 1.

[0114] The optical path from laser LS1 to target material 112 and the optical path from laser LS2 to the deposit (or target material 112) may share a portion of their paths. For example, a common optical element such as a mirror 121 or a focusing lens 122 may be provided on both optical paths. However, the two optical paths may not share any common optical elements and may not overlap.

[0115] In Embodiment 1 or 2, when the operating 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 Figure 6 is met, the control unit 160 may switch the operating mode to the first mode. As a different predetermined condition, the control unit 160 may switch the operating mode from the second mode to the first mode when, in the second mode, the position of the plasma generated by the cleaning laser irradiating the target material 112 matches a predetermined position. The predetermined position is a position in which the optical path of the light L0 generated by the plasma is oriented in a direction suitable for the application of the light L0 (for example, a position in which the light L0 is oriented in a direction suitable for illuminating the sample 500, which is the object), 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 matches the predetermined position. As a result, the control unit 160 can maintain the second operating mode when illumination light L1 is generated at an angle unsuitable for inspection relative to the sample 500, thereby enabling stable inspection results.

[0116] The control unit 160 may switch the operating mode from the second mode to the first mode when predetermined switching conditions are met. The predetermined switching conditions may include, as described above, that the position of the plasma generated when the cleaning laser irradiates the target material 112 matches a predetermined position. However, even if the position of the plasma generated when the cleaning laser irradiates the target material 112 matches a predetermined position in the second mode, the control unit 160 does not need to switch the operating mode from the second mode to the first mode if other conditions are not met (for example, if the amount of deposits has not been reduced). The case where the amount of deposits has not been reduced includes the case where the control unit 160 determines that the amount of deposits 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 deposit reduction indicates the difference between the amount of deposits detected during the most recent measurement by the sensor 141 and the amount of deposits detected during the previous measurement by the sensor 141 (or when the mode to be executed is set to the second mode and the cleaning of deposits is started). Thus, the predetermined switching conditions may include both the reduction of deposits and the position of the plasma generated by the cleaning laser irradiating the target material 112 matching the predetermined position.

[0117] The program defining the operations performed by the control unit 160 of the light source device 100 includes, when loaded into a computer, a set of instructions or software code for causing the computer to perform one or more of the functions described in the embodiments. The program may be stored in a non-temporary computer-readable medium or a physical storage medium. Examples, but not limited to, 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® disc or other optical disc storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage devices. The program may be transmitted over a temporary computer-readable medium or a communication medium. Examples, but not limited to, include temporary computer-readable medium or a communication medium that includes electrical, optical, acoustic or other forms of propagating signals. The temporary computer-readable medium or a communication medium can supply the program to a computer via wired communication channels such as electric wires and optical fibers, or via wireless communication channels.

[0118] While embodiments of the present disclosure have been described above, the disclosure includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the embodiments described above. Furthermore, the configurations of Embodiments 1 to 2 may be combined as appropriate. [Explanation of Symbols]

[0119] 1. Inspection device 100 Light source device 110 Target holding section 111 Container 111a opening 112 Target material 113 Bottom 114 Cylindrical section 115 Base 116A Interior wall surface 116B Exterior wall surface 117 Groove 118 Heater 119 Debris Shield 120 Input Optics 121 Mirror 122 Focusing lens 127 Plasma 130 Output Optics 131 Collector's Mirror 140 Acquisition Department 141 Sensors 150 Drive unit 160 Control Unit 170 Focus adjustment mechanism 200 Illumination optical system 210 Ellipsoidal mirror 220 Ellipsoidal mirror 230 Recessed Mirror 300 Inspection Optical System 310 Perforated concave mirror 311 holes 320 Convex mirror 330 plane mirror 340 concave mirror 410 detectors 411 detection surface 420 Image Processing Unit 500 samples 510 Top surface 511 Field of view 520 stages 530 Drive unit L 0 light L1 illumination light L2 reflected light LE EUV light LR excitation light LS1 laser OP1 First optical component OP2 Second optical component P1 position PS irradiation position R rotation axis

Claims

1. A control device for an optical device equipped with a light source device, which determines the mode to be executed from among multiple modes, The aforementioned multiple 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 the holding part with a laser, and a second mode in which the light source device reduces deposits attached to the surface of the holding part by irradiating the deposits with a laser. Control device.

2. A control device for a light source device that determines the mode to be executed from among multiple modes, The aforementioned multiple modes include a first mode in which light is generated by irradiating a target material held by the holding part with a laser, and a second mode in which deposits attached to the surface of the holding part are reduced by irradiating the deposits with a laser. Control device.

3. A control device for an optical device equipped with a light source device, which determines the mode to be executed from among multiple modes, The aforementioned multiple 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 attached to the surface of components in the chamber by irradiating the deposits with a laser, wherein in the second mode, the laser irradiated to the deposits is also irradiated to the target material. Control device.

4. A control device for a light source device that determines the mode to be executed from among multiple modes, The aforementioned multiple 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 adhering to the surface of components in the chamber with a laser to reduce the deposits, wherein in the second mode, the laser irradiated to the deposits is also irradiated to the target material. Control device.

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

6. The irradiation state of the laser in the second mode is a defocused state compared to the irradiation state of the laser 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 conditions include, when the mode being executed is the second mode, the position of the plasma generated by the irradiation of 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 for identifying the form of the attached substance, The aforementioned plurality of modes include a plurality of second modes with different control conditions, Based on the characteristics of the deposit identified by the identification unit, one of the multiple second modes is determined to be the mode to be executed. 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, The laser generator is controlled according to the mode of execution described above. The control device according to any one of claims 1 to 4.

10. The aforementioned 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, The system comprises an optical element through which the laser generated by the first laser generator and the laser generated by the second laser generator pass, The first laser generator and the second laser generator are controlled according to the execution mode described above. The control device according to claim 1 or 2.

11. The light source device includes the holding part that rotates around the rotation axis, When the mode being executed is the first mode, the light source device is instructed to irradiate the target material held by the holding part with the laser. The control device according to claim 1 or 2.

12. The optical device includes adjustment means for suppressing the propagation of light generated from the light source device to the object, When the mode of execution is the second mode, the adjustment means is driven. 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, The system includes a control unit that reduces deposits by irradiating the deposits adhering to the surface of the target material holding portion with a laser. Light source device.

14. The holding part rotates around the rotation axis. The light source device according to claim 13.

15. A light source device that generates light by irradiating a target material inside a chamber with a laser, The chamber includes a control unit that reduces deposits by irradiating the deposits adhering to the surface of the components within the chamber with a laser, and the laser irradiated to the deposits also irradiates the target material. Light source device.

16. The first step involves illuminating the target object with illumination light generated by irradiating the target material held by the holding part with a laser, A second step involves reducing the deposits adhering to the surface of the holding part by irradiating them with a laser, The method comprises a third step of switching between the first step and the second step. A method for controlling optical devices.

17. The first step involves generating light by irradiating a target material held by a holding unit with a laser, A second step involves reducing the deposits adhering to the surface of the holding part by irradiating them with a laser, The method comprises a third step of switching between the first step and the second step. A method for controlling a light source device.

18. The first step involves illuminating the target object with illumination light generated by irradiating the target material inside the chamber with a laser, and A second step involves reducing the deposits adhering to the surface of the components within the chamber by irradiating them with a laser, The method comprises a third step of switching between the first step and the second step, In the second step described above, the laser irradiated onto the deposit is also irradiated onto the target material. A method for controlling optical devices.

19. The first step involves generating light by irradiating a target material inside a chamber with a laser, A second step involves reducing the deposits adhering to the surface of the components within the chamber by irradiating them with a laser, The method comprises a third step of switching between the first step and the second step, In the second step described above, the laser irradiated onto the deposit is also irradiated onto the target material. A method for controlling a light source device.

20. The first step involves generating light by irradiating the molten target material with a laser, A second step involves reducing the deposits adhering to the surface of the holding portion of the target material by irradiating the deposits with a laser, The method comprises a third step of switching between the first step and the second step. A method for controlling a light source device.

21. The first step involves illuminating the target object with illumination light generated by irradiating the target material held by the holding part with a laser, A second step involves reducing the deposits adhering to the surface of the holding part by irradiating them with a laser, A third step which switches between the first step and the second step, A program that causes an optical device to execute a command.

22. The first step involves generating light by irradiating a target material held by a holding unit with a laser, A second step involves reducing the deposits adhering to the surface of the holding part by irradiating them with a laser, A third step which switches between the first step and the second step, A program that causes the light source device to execute.

23. The first step involves illuminating the target object with illumination light generated by irradiating the target material inside the chamber with a laser, and A second step involves reducing the deposits adhering to the surface of the components within the chamber by irradiating them with a laser, The optical device is made to perform a third step which switches between the first step and the second step, In the second step described above, the laser irradiated onto the deposit is also irradiated onto the target material. program.

24. The first step involves generating light by irradiating a target material inside a chamber with a laser, A second step involves reducing the deposits adhering to the surface of the components within the chamber by irradiating them with a laser, The light source device is made to perform a third step which switches between the first step and the second step, In the second step described above, the laser irradiated onto the deposit is also irradiated onto the target material. program.

25. The first step involves generating light by irradiating the molten target material with a laser, A second step involves reducing the deposits adhering to the surface of the holding portion of the target material by irradiating the deposits with a laser, A third step which switches between the first step and the second step, A program that causes the light source device to execute.

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