Light source apparatus and control method of light source apparatus

Abstract

[Problem] Provides a light source device and a method for controlling the light source device that can easily change the relative position between a light-emitting point and an optical member in the light source device. [Solution] A light source device (1) according to the present disclosure is a rotating body (100) comprising a target holding part (110) that holds a target material (TG) which is a plasma source that generates plasma (PZ), and a shaft part (120) connected to the target holding part (110); the rotating body (100) that rotates around a rotation axis (R) passing through the shaft part (120), a magnetic force generating part (210) that applies magnetic force to the shaft part (120), a shaft support part (200) that supports the shaft part (120), and a control part (300) that controls the magnetic force generating part (210); the shaft support part (200) supports the shaft part (120) so as to be rotatable while the shaft part (120) is levitized by magnetic force through the magnetic force generating part (210); and the control part (300) controls the magnetic force generating part (210) by Displace the shaft (120).

Description

Technology Field

[0001] The present disclosure relates to a light source device and a method for controlling the light source device. Background Technology

[0002] Patent document 1 describes a light source that emits illumination light by forming a target material on the surface of a cylindrical member that rotates around a rotation axis and irradiating the formed target material with excitation light.

[0003] Patent document 2 describes a light source that emits illumination light by holding a target material of molten metal on the inner wall of a crucible rotating around a rotation axis by centrifugal force and irradiating the held target material with excitation light. Prior art literature

[0004] [Patent Document 1] Japanese Patent Publication No. 2020-077007 [Patent Document 2] Japanese Patent Publication No. 2022-168463 The problem to be solved

[0005] In a light source device, the relative position between the light-emitting point located near the surface of the target material and the optical member may change due to vibrations generated during the rotation of the target holding part, such as a cylindrical member and a crucible, deformation of the structure itself, deformation caused by rotational stress and heat of the target holding part itself, and the insertion of the target material into the target holding part. In addition, the target holding part may interfere with surrounding members. Consequently, it is possible to conceive of a situation where light cannot be stably emitted from the light source device. Therefore, appropriate control of the position of the target holding part is desired to easily change the relative position between the light-emitting point and the optical member and to prevent interference between the target holding part and surrounding members.

[0006] The purpose of the present disclosure is to provide a light source device and a method for controlling the light source device that can appropriately control the position of a target holding part, in order to solve these problems. means of solving the problem

[0007] A light source device according to the present disclosure comprises a target holding member that holds a target material serving as a plasma source for generating plasma, and a rotating body including a shaft member connected to the target holding member, wherein the rotating body rotates around a rotational axis passing through the shaft member, and a magnetic force generating member that applies magnetic force to the shaft member, and wherein the device comprises a shaft support member that supports the shaft member and a control member that controls the magnetic force generating member, wherein the shaft support member supports the shaft member rotatably while the shaft member is levitized by the magnetic force through the magnetic force generating member, and the control member displaces the shaft member by controlling the magnetic force generating member.

[0008] In the light source device, the magnetic field generating unit includes a first magnetic field generating unit that applies the magnetic field to the shaft portion, and the control unit may displace the shaft portion in a first displacement direction including a component perpendicular to the rotation axis by controlling the first magnetic field generating unit.

[0009] In the above light source device, the rotating body further includes a disc portion connected to the shaft portion having a diameter different from the diameter of the shaft portion, the magnetic field generating unit includes a second magnetic field generating unit that applies the magnetic field to the disc portion, and the control unit may displace the shaft portion in a second displacement direction including a component parallel to the rotation axis by controlling the second magnetic field generating unit.

[0010] In the light source device above, when the target material generates plasma, the control unit may rotate the rotating body at a target rotational speed and control the first magnetic force generating unit, thereby displace the shaft in the first displacement direction while the shaft is rotating at the target rotational speed.

[0011] The light source device further comprises an acquisition unit for acquiring the state of a holding surface that holds the target material in the target holding unit, and the control unit may displace the shaft in the first displacement direction based on the result of acquiring the state of the holding surface in the acquisition unit.

[0012] In the light source device, the state of the holding surface may include at least one of the amount of the target material held on the holding surface, the surface position of the target material, the surface roughness of the target material, and the surface roughness of the holding surface.

[0013] The light source device further comprises an input optical system that irradiates the excitation light onto the target material, having a first focusing point on the target material side of a first optical member that focuses the excitation light onto the target material, and an output optical system that extracts the light generated from the plasma source, having a second focusing point on the target material side of a second optical member that focuses the light generated from the plasma source, and the acquisition unit acquires the displacement of the surface position of the target material, and the control unit may displace the axis portion such that, when the surface position is displaced, the relative position between the surface position at the irradiation position of the excitation light of the target material and at least one of the first focusing point and the second focusing point is approximately constant before and after the displacement of the surface position.

[0014] In the light source device, the target holding member includes a cylindrical part and a bottom part that blocks an opening on one side of the cylindrical part, and further includes a shield that covers an opening on the other side of the cylindrical part, and the control member may displace the shaft part in the second displacement direction by controlling the second magnetic force generating member so that the distance between the shield and the cylindrical part becomes a predetermined target amount.

[0015] In the light source device, the control unit, when detecting the establishment of a predetermined condition, displaces the shaft portion in the second displacement direction so that the distance becomes greater, and the predetermined condition may include at least one of detecting a vibration greater than a predetermined value of the rotating body and detecting a rotational speed less than a predetermined value of the rotating body.

[0016] In the light source device, the control unit may acquire the surface position of the target material at the irradiation position based on the state of the holding surface at a position different from the irradiation position acquired by the acquisition unit.

[0017] In the light source device above, the control unit may displace the shaft in the first displacement direction when the surface position is displaced by a predetermined amount in the direction of increase of the target material.

[0018] A control method for a light source device according to the present disclosure comprises: a target holding member that holds a target material which is a plasma source for generating plasma; a rotating body including a shaft member connected to the target holding member, wherein the rotating body rotates around a rotation axis passing through the shaft member; a magnetic force generating member that applies magnetic force to the shaft member; a shaft supporting member that supports the shaft member; and a control member that controls the magnetic force generating member. The method further comprises a step in which the shaft supporting member supports the shaft member rotatably while the shaft member is levitating by the magnetic force through the magnetic force generating member, and a step in which the control member displaces the shaft member by controlling the magnetic force generating member.

[0019] In the control method of the light source device above, the magnetic force generating unit includes a first magnetic force generating unit that applies the magnetic force to the shaft portion, and in the step of displacing the shaft portion, the control unit may displace the shaft portion in a first displacement direction including a component perpendicular to the rotation axis by controlling the first magnetic force generating unit.

[0020] In the control method of the light source device described above, the rotating body further includes a disc portion connected to the shaft portion having a diameter different from the diameter of the shaft portion, and the magnetic force generating unit includes a second magnetic force generating unit that applies the magnetic force to the disc portion, and in the step of displacing the shaft portion, the control unit may displace the shaft portion in a second displacement direction including a component parallel to the rotation axis by controlling the second magnetic force generating unit.

[0021] The control method of the light source device described above is, in a step of rotatably supporting the shaft portion,

[0022] When the above target material generates plasma, the control unit may, in the step of rotating the rotating body at a target rotational speed and displacing the shaft, control the first magnetic force generating unit so that the shaft may displacing the shaft in the first displacement direction while the shaft is rotating at the target rotational speed.

[0023] In the control method of the light source device described above, the method further comprises a step of acquiring the state of a holding surface that holds the target material in the target holding part to an acquiring part, and in the step of displacing the shaft part, the control part may displacing the shaft part in the first displacement direction based on the result of acquiring the state of the holding surface in the acquiring part.

[0024] In the control method of the light source device above, the state of the holding surface may include at least one of the amount of the target material held on the holding surface, the surface position of the target material, the surface roughness of the target material, and the surface roughness of the holding surface.

[0025] In the control method of the light source device described above, the light source device further comprises an input optical system that irradiates the excitation light onto the target material, having a first focusing point on the target material side of a first optical member that focuses the excitation light onto the target material, and an output optical system that extracts the light generated from the plasma source, having a second focusing point on the target material side of a second optical member that focuses the light generated from the plasma source, wherein in the step of acquiring the state of the maintenance surface by the acquiring unit, the acquiring unit acquires the displacement of the surface position of the target material, and in the step of displacing the axis portion, the control unit may displacing the axis portion such that, when the surface position is displacing, the relative position between the surface position at the irradiation position of the excitation light of the target material and at least one of the first focusing point and the second focusing point is approximately constant before and after the displacement of the surface position.

[0026] In the control method of the light source device, the target holding member comprises a cylindrical part and a bottom part that blocks an opening on one side of the cylindrical part, and the light source device further comprises a shield that covers an opening on the other side of the cylindrical part, and in at least one of a step that rotatably supports the shaft part and a step that displaces the shaft part, the control member may displace the shaft part in the second displacement direction by controlling the second magnetic force generating member so that the distance between the shield and the cylindrical part becomes a predetermined target amount.

[0027] In the control method of the light source device described above, in at least one of the step of rotatably supporting the shaft portion and the step of displacing the shaft portion, the control unit displaces the shaft portion in the second displacement direction such that the distance becomes greater when it detects the establishment of a predetermined condition, and the predetermined condition may include at least one of detecting a vibration greater than a predetermined value of the rotating body and detecting a rotational speed less than a predetermined value of the rotating body.

[0028] In the control method of the light source device described above, in the step of acquiring the state of the holding surface by the acquiring unit, the control unit may acquire the surface position of the target material at the irradiation position based on the state of the holding surface at a position different from the irradiation position acquired by the acquiring unit.

[0029] In the control method of the light source device above, in the step of displacing the shaft portion, the control unit may displacing the shaft portion in the first displacement direction when the surface position is displacing by a predetermined amount in the direction of increase of the target material. Effects of the invention

[0030] According to the present disclosure, the position of the target holding member can be appropriately controlled, and this can improve the operational stability of the light source device. Brief explanation of the drawing

[0031] [Fig. 1] This is a cross-sectional view illustrating a light source device according to Embodiment 1. [Fig. 2] A perspective view illustrating an axis support member in a light source device according to embodiment 1. [Fig. 3] This is a flowchart illustrating a control method for an optical device according to Embodiment 1. [Fig. 4] This is a cross-sectional view illustrating an optical device according to Embodiment 2. [Fig. 5] This is a plan view illustrating a target holding part in a light source device according to embodiment 2. [Fig. 6] This is a flowchart illustrating a control method for a light source device according to Embodiment 2. [Fig. 7] This is a cross-sectional view illustrating a light source device according to Embodiment 3. [Fig. 8] A graph illustrating the whirling amount from the axis of rotation when the rotating body rotates around the axis of rotation in a light source device according to embodiment 4, wherein the horizontal axis represents the frequency of rotation of the rotating body and the vertical axis represents the whirling amount. [Fig. 9] This is a configuration diagram illustrating an inspection device equipped with a light source device according to embodiment 5. Specific details for implementing the invention

[0032] Hereinafter, specific configurations of the present embodiment will be described with reference to the drawings. The following description represents highly suitable 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 denote substantially the same content. Some symbols and hatchings have been omitted to avoid cluttering the drawings.

[0033] <Embodiment 1>

[0034] A light source device according to Embodiment 1 is described. The light source device of this embodiment generates light such as illumination light used in optical devices, such as inspection devices and review devices, and exposure light used in optical devices, such as exposure devices. The light source device may be installed integrally with the optical device, or it may be placed near the optical device as a separate body separated from the optical device. When the optical device is an inspection device and a review device, the light source device generates illumination light that illuminates an object. Also, when the optical device is an exposure device, the light source device generates exposure light that exposes an object.

[0035] The light source device generates light, such as illumination light and exposure light, by irradiating an excitation light onto a target material maintained in a target holding part. Below, as an example of a light source device, an example is described in which a molten material maintained in a container is used as the target material. Furthermore, the light source device is not limited to using a molten material maintained in a container as the target material; it may also use a molten material in the shape of a liquid droplet or a solid material fixed in a cylinder-shaped drum as the target material.

[0036] FIG. 1 is a cross-sectional view illustrating a light source device (1) according to embodiment 1. FIG. 2 is a perspective view illustrating an axis support member (200) in the light source device (1) according to embodiment 1. FIG. 2 shows a cross-section of a part of the axis support member (200). As shown in FIG. 1 and FIG. 2, the light source device (1) comprises a rotating body (100), an axis support member (200), and a control member (300). Below, each component of the <rotating body>, <axis support member>, and <control member> will be described.

[0037] Rotating body

[0038] The rotating body (100) rotates around the rotation axis (R). Here, for convenience of explaining the light source device (1), an XYZ orthogonal coordinate system is introduced with the rotation axis (R) as the Z-axis direction. For example, the +Z-axis direction may be called the upward direction and the -Z-axis direction may be called the downward direction. Also, the upward and downward directions are for convenience of explanation and do not limit the direction of each component.

[0039] The rotating body (100) includes a target holding part (110) and a shaft part (120). The target holding part (110) holds a target material (TG) that serves as a plasma source for generating plasma (PZ). In the present embodiment, as an example, the target holding part (110) includes a container such as a crucible. The target material (TG) includes, as an example, a molten material such as tin (Sn) or lithium (Li). In addition, the target holding part (110) is not limited to a container and may be a cylindrical drum. In that case, the target holding part (110) may hold the target material (TG) by fixing a solid material such as frozen xenon (Xe) to the surface of the drum.

[0040] The target holding portion (110) includes a cylindrical portion (111) and a bottom portion (112). The cylindrical portion (111) may be, for example, a cylindrical shape having a central axis extending in the Z-axis direction. The central axis of the cylindrical portion (111) may coincide with the rotation axis (R). The cylindrical portion (111) has openings on the +Z-axis direction side and the -Z-axis direction side. The cylindrical portion (111) may hold a target material (TG) on its inner surface. In this case, the holding surface (113) holding the target material (TG) includes the inner surface of the cylindrical portion (111). The target material (TG) may be held on the holding surface (113) by centrifugal force caused by the rotation of the rotating body (100) around the rotation axis (R).

[0041] The retaining surface (113) formed to surround the rotation axis (R) may include a cylindrical portion with a constant distance from the rotation axis (R) from the top to the bottom, or a tubular portion with an expanded middle section between the top and bottom. Additionally, the retaining surface (113) may include a cone-shaped portion that spreads outward toward the top. The retaining surface (113) may be formed in an annular groove along the inner circumference of the cylindrical portion (111).

[0042] The bottom part (112) may, for example, be in the shape of a disc having a central axis extended in the Z-axis direction. The central axis of the bottom part (112) may coincide with the rotation axis (R). The bottom part (112) blocks the opening on the -Z-axis side of the cylindrical part (111). By this, the target holding part (110) is in the shape of a container with an opening on the +Z-axis side of the cylindrical part (111). Additionally, the holding surface (113) may include the inner surface on the +Z-axis side of the bottom part (112).

[0043] The target holding part (110) may include a heater not shown that melts the target material (TG).

[0044] The shaft portion (120) is connected to the target holding portion (110). The shaft portion (120) is in the shape of a rod extending in the Z-axis direction. The rotation axis (R) passes through the shaft portion (120). For example, the rotation axis (R) may coincide with the center axis of the shaft portion (120). Accordingly, the rotating body (100) rotates around the rotation axis (R) passing through the shaft portion (120).

[0045] The shaft portion (120) includes a material that adheres to a magnet or electromagnet. The shaft portion (120) may include, for example, at least one ferromagnetic material among iron, cobalt, and nickel. The shaft portion (120) is not limited to metals such as iron, cobalt, and nickel, provided that it includes a material that adheres to a magnet or electromagnet, i.e., a magnetic material. The shaft portion (120) may include a magnet or an electromagnet.

[0046] The shaft portion (120) has an end (121) on the +Z axis direction side and an end (122) on the -Z axis direction side. The end on the +Z axis direction side of the shaft portion (120) is connected to the target holding portion (110). Specifically, the end on the +Z axis direction side of the shaft portion (120) is connected to the surface on the -Z axis direction side of the bottom portion (112). The shaft portion (120) may penetrate the bottom portion (112), that is, the end on the +Z axis direction side of the shaft portion (120) may be on the Z axis direction plus side compared to the bottom portion (112). The shaft portion (120) has a side surface that is in contact with the direction perpendicular to the rotation axis (R).

[0047] The rotating body (100) may additionally include a disc portion (130). The disc portion (130) may, for example, be a ring shape having a central axis extended in the Z-axis direction. The disc portion (130) may, for example, be a polygonal shape having a central axis extended in the Z-axis direction. The central axis of the disc portion (130) may coincide with the rotation axis (R). The disc portion (130) has a diameter different from the diameter of the shaft portion (120). Specifically, the diameter of the disc portion (130) centered on the rotation axis (R) is larger than the diameter of the shaft portion (120) centered on the rotation axis (R). The disc portion (130) is connected to the shaft portion (120). For example, the disc portion (130) is connected to the shaft portion (120) by the shaft portion (120) being inserted into the center hole of the ring-shaped disc portion (130). The disc portion (130) has a ring-shaped upper surface and a lower surface within a plane perpendicular to the rotation axis (R).

[0048] <Chukjijibu>

[0049] The shaft support member (200) supports the shaft member (120). The shaft support member (200) includes a magnetic force generating member (210). The magnetic force generating member (210) applies magnetic force to the shaft member (120). The shaft support member (200) can make the shaft member (120) levitate by magnetic force through the magnetic force generating member (210). The shaft support member (200) supports the shaft member (120) so that it can rotate while levitating by magnetic force. The shaft support member (200) may include a case (230). The magnetic force generating member (210) and the shaft member (120) may be placed inside the case (230).

[0050] The magnetic generating unit (210) may include a first magnetic generating unit (211) and a second magnetic generating unit (212). Additionally, the magnetic generating unit (210) may include the first magnetic generating unit (211) and not include the second magnetic generating unit (212). Additionally, the magnetic generating unit (210) may include the second magnetic generating unit (212) and not include the first magnetic generating unit (211).

[0051] The first magnetic force generating unit (211) provides magnetic force to the shaft (120). For example, the first magnetic force generating unit (211) includes an electromagnet. The first magnetic force generating unit (211) may be arranged to surround a portion of the side of the shaft (120). With this configuration, the first magnetic force generating unit (211) provides magnetic force to the shaft (120). The first magnetic force generating unit (211) may be arranged with a gap between it and a portion of the side of the shaft (120).

[0052] The first magnetic force generating unit (211) may provide a magnetic force to the shaft portion (120) that rotates the shaft portion (120) around the rotation axis (R). Additionally, the first magnetic force generating unit (211) may provide a magnetic force to the shaft portion (120) that displaces the shaft portion (120) in a first displacement direction that includes a component perpendicular to the rotation axis (R). The first displacement direction may include a direction parallel to the XY plane.

[0053] The second magnetic force generating unit (212) provides magnetic force to the disc unit (130). For example, the second magnetic force generating unit (212) includes an electromagnet. The second magnetic force generating unit (212) may be positioned to face the surface on the +Z-axis direction side and the surface on the -Z-axis direction side of the disc unit (130). For example, the disc unit (130) is positioned between the second magnetic force generating unit (212) positioned on the +Z-axis direction side of the disc unit (130) and the second magnetic force generating unit (212) positioned on the -Z-axis direction side of the disc unit (130). With this configuration, the second magnetic force generating unit (212) provides magnetic force to the disc unit (130). The second magnetic generating part (212) may be spaced apart from the surface on the +Z axis direction side and the surface on the -Z axis direction side of the disc part (130).

[0054] The second magnetic force generating unit (212) may provide a magnetic force to the shaft portion (120) that rotates the shaft portion (120) around the rotation axis (R). Additionally, the second magnetic force generating unit (212) may provide a magnetic force to the shaft portion (120) that displaces the shaft portion (120) in a second displacement direction that includes a component parallel to the rotation axis (R). The second displacement direction may include a direction parallel to the Z-axis.

[0055] The shaft support member (200) may include a plurality of sensors (220). The shaft support member (200) may include a sensor (220) that detects the position of the shaft member (120). Additionally, the shaft support member (200) may include a sensor (220) that detects the rotational speed of the shaft member (120). The shaft support member (200) may include various sensors (220) other than these, such as those that detect temperature.

[0056] The first magnetic generating unit (211) and the second magnetic generating unit (212) in the magnetic generating unit (210) are connected to the control unit (300) in a state capable of transmitting information. The first magnetic generating unit (211) and the second magnetic generating unit (212) generate magnetic force under the control of the control unit (300). The sensor (220) is connected to the control unit (300) in a state capable of transmitting information. The sensor (220) outputs detection results, such as the detected position of the shaft (120), the number of rotations of the shaft (120), and the temperature of the shaft (120), to the control unit (300).

[0057] Control Unit

[0058] The control unit (300) controls the magnetic force generating unit (210). For example, the control unit (300) controls the magnetic force generating unit (210) by controlling the current flowing through the electromagnet included in the magnetic force generating unit (210). By controlling the magnetic force generating unit (210), the control unit (300) rotates the shaft unit (120) around the rotation axis (R). By doing so, the control unit (300) rotates the rotating body (100) around the rotation axis (R). By controlling the magnetic force generating unit (210), the control unit (300) displaces the shaft unit (120). By doing so, the control unit (300) moves the position of the rotating body (100).

[0059] Specifically, the control unit (300) controls the first magnetic force generating unit (211) to displace the shaft unit (120) in a first displacement direction containing a component perpendicular to the rotation axis (R). By doing so, the control unit (300) moves the position of the rotating body (100) in a first displacement direction containing a component perpendicular to the rotation axis (R). Additionally, the control unit (300) controls the second magnetic force generating unit (212) to displace the shaft unit (120) in a second displacement direction containing a component parallel to the rotation axis (R). By doing so, the control unit (300) moves the position of the rotating body (100) in a second displacement direction containing a component parallel to the rotation axis (R).

[0060] When plasma (PZ) is generated in the target material (TG) by irradiating the target material (TG) with excitation light (LR), the control unit (300) rotates the rotating body (100) at a target rotational speed. In this case, the control unit (300) controls the first magnetic force generating unit (211) to displace the shaft (120) in a first displacement direction while the shaft (120) is rotating at the target rotational speed. By doing so, for example, when the surface position of the target material (TG) relative to the point of concentration of the excitation light (LR) is displaced due to the return current of the target material (TG), the surface position of the target material (TG) can be corrected. Thus, the light source device (1) can be operated continuously while stably extracting light.

[0061] The recirculation of the target material (TG) refers to the target material (TG) scattered from the target holding part (110) returning to the target holding part (110) again. Additionally, the control part (300) does not exclude displacing the shaft part (120) in the first displacement direction while the shaft part (120) is not rotating at the target rotational speed. The state where the shaft part (120) is not rotating at the target rotational speed includes the state where the rotation of the shaft part (120) is stopped.

[0062] Meanwhile, the control unit (300) may displace the shaft (120) in the second displacement direction by controlling the second magnetic force generating unit (212) while the shaft (120) is not rotating at the target rotational speed. By doing so, the position of the rotating body (100) can be lowered at the start and stop of rotation of the rotating body (100), and a margin can be taken for clearance with other members, such as the debris shield described later. Therefore, interference with other members can be suppressed. The control unit (300) may displace the shaft (120) in the second displacement direction while the shaft (120) is rotating at the target rotational speed by controlling the second magnetic force generating unit (212). Specifically, the control unit (300) may displace the shaft (120) to an extent that no interference occurs while the shaft (120) is rotating at a target rotational speed.

[0063] Method for controlling a light source device

[0064] FIG. 3 is a flowchart illustrating a control method of a light source device (1) according to embodiment 1. As shown in FIG. 3, the control method of the light source device (1) comprises a step S10 that rotatably supports an axis portion (120) and a step S20 that displaces the axis portion (120).

[0065] In step S10, the shaft support member (200) supports the shaft member (120) rotatably while the shaft member (120) is levitized by magnetic force through the magnetic force generating member (210).

[0066] In step S20, the control unit (300) displaces the shaft (120) by controlling the magnetic force generating unit (210). In step S20, the control unit (300) may displace the shaft (120) in a first displacement direction containing a component perpendicular to the rotation axis (R) by controlling the first magnetic force generating unit (211). Additionally, the control unit (300) may displace the shaft (120) in a second displacement direction containing a component parallel to the rotation axis (R) by controlling the second magnetic force generating unit (212).

[0067] In step S10, when the target material (TG) generates plasma (PZ), the control unit (300) may rotate the rotating body (100) at a target rotational speed. In that case, in step S20, the control unit (300) may, by controlling the first magnetic force generating unit (211), displace the shaft (120) in a first displacement direction while the shaft (120) is rotating at the target rotational speed.

[0068] Next, the effects of the present embodiment are explained. The light source device (1) of the present embodiment can control the position of the rotating body (100) during rotation by magnetic force by using a shaft support member (200) that supports a shaft member (120) that has been levitated by magnetic force. Specifically, the shaft member (120) of the rotating body (100) can be rotatably supported while being levitated by magnetic force through a magnetic force generating member (210). The control member (300) displaces the shaft member (120) by controlling the magnetic force generating member (210). Accordingly, the position of the light emission point of the plasma (PZ) in the light source device (1) and the light emission intensity can be appropriately adjusted. In addition, the clearance between the rotating body (100) and surrounding members can be adjusted as desired. In this way, by appropriately controlling the position of the rotating body (100), the stability of the light (LE) emitted from the light source device (1) can be improved, and stable operation can be realized by avoiding interference with surrounding members.

[0069] The magnetic force generating unit (210) includes a first magnetic force generating unit (211) that displaces the shaft portion (120) in a first displacement direction containing a component perpendicular to the rotation axis (R), and a second magnetic force generating unit (212) that displaces the shaft portion (120) in a second displacement direction containing a component parallel to the rotation axis (R). By this, the light source device (1) can move the position of the rotating body (100) during rotation to any position in the XYZ axis direction. Accordingly, the position for displacing the rotating body (100) can be determined with high precision.

[0070] The control unit (300) can displace the shaft (120) in a first displacement direction and a second displacement direction while the shaft (120) is rotating at a target rotational speed. Thus, the light source device (1) can be operated without stopping the rotation of the rotating body (100).

[0071] <Embodiment 2>

[0072] Next, Embodiment 2 is described. In this embodiment, the state of the holding surface (113) of the target holding part (110) is acquired by the acquiring part (400). This is also an example corresponding to the recirculation of the target material (TG) or the consumption of the target material (TG). FIG. 4 is a cross-sectional view illustrating a light source device (2) according to Embodiment 2. FIG. 5 is a plan view illustrating a target holding part (110) in the light source device (2) according to Embodiment 2. As shown in FIG. 4 and FIG. 5, the light source device (2) is equipped with a rotating body (100), an axis support part (200), and a control part (300), in addition, an acquiring part (400).

[0073] The acquisition unit (400) acquires the state of the holding surface (113) that holds the target material (TG) in the target holding unit (110). The state of the holding surface (113) includes at least one of the amount of target material (TG) held on the holding surface (113), the surface position of the target material (TG), and the displacement of the surface position of the target material (TG). The state of the holding surface (113) may include at least one of the surface roughness of the target material (TG) and the surface roughness of the holding surface (113).

[0074] The acquisition unit (400) may include at least one of a displacement meter, a high-speed camera, a low-speed camera, a 4-segment PD (Photo Diode), and a TDI (Time Delay Integration) camera. Additionally, the acquisition unit (400) may be one that measures the state of the maintenance surface (113) in one dimension, one that measures in two dimensions, and one that measures in three dimensions, and may be a combination of several of these.

[0075] The acquisition unit (400) is connected to the control unit (300) in a state capable of transmitting information. The acquisition unit (400) outputs information regarding the state of the acquired maintenance surface (113) to the control unit (300).

[0076] The control unit (300) displaces the shaft (120) based on the result of acquiring the state of the holding surface (113) in the acquiring unit (400). For example, the control unit (300) displaces the shaft (120) in the first displacement direction based on the result of acquiring the state of the holding surface (113) in the acquiring unit (400). For example, when the surface position of the target material (TG) on the inner circumference of the cylindrical part (111) in the holding surface (113) is displaced due to the recirculation or consumption of the target material (TG), the control unit (300) displaces the shaft (120) in the first displacement direction. Additionally, the control unit (300) may displace the shaft (120) in the second displacement direction based on the result of acquiring the state of the holding surface (113) in the acquiring unit (400). When the target material (TG) is circulated, the surface position of the target material (TG) is displaced so as to be closer to the rotation axis (R). Also, when the target material (TG) is consumed, the surface position of the target material (TG) is displaced so as to be further away from the rotation axis (R). The control unit (300) may displace the shaft unit (120) in the first displacement direction when a displacement greater than a predetermined amount is acquired for the surface position of the target material (TG) by the acquisition unit (400).

[0077] The light source device (1) further comprises an input optical system (500) and an output optical system (600). The input optical system (500) irradiates excitation light (LR) onto a target material (TG). The input optical system (500) includes an optical member (OP1) that concentrates the excitation light (LR) onto the target material (TG). The optical member (OP1) includes, for example, a concentrating lens. Additionally, the optical member (OP1) may be a mirror or the like as long as it can concentrate the excitation light (LR) onto the target material (TG). The input optical system (500) has a concentrating point (F1) on the target material (TG) side of the optical member (OP1).

[0078] The optical member (OP1) may irradiate the target material (TG) with excitation light (LR) at an angle inclined from an axis perpendicular to the surface of the target material (TG). Specifically, for example, the optical member (OP1) irradiates the excitation light (LR) at an angle of incidence inclined to the surface of the irradiation position (PS) where the excitation light (LR) is irradiated.

[0079] The input optical system (500) may include a laser device that generates excitation light (LR). Additionally, the input optical system (500) may guide excitation light (LR) generated by a laser device separate from the light source device (2) to the light source device (2).

[0080] The output optical system (600) extracts light (LE) generated from the plasma (PZ) from the light source device (1). The output optical system (600) includes an optical member (OP2) that collects light (LE) generated from the plasma source. The optical member (OP2) includes, for example, a collector mirror such as an ellipsoidal mirror. Additionally, the optical member (OP2) may be a collecting lens as long as it can collect light (LE) generated from the plasma (PZ). Additionally, the optical member (OP2) may be a second collector mirror that further reflects light (LE) reflected by the collector mirror. The output optical system (600) has a collecting point (F2) on the target material (TG) side of the optical member (OP2).

[0081] Among the planes including the rotation axis (R), the plane including the light-gathering point (F1) when the light-gathering point (F1) is at a reference position, and the inner circumferential surface of the cylindrical part (111) intersect at the position where the plane including the light-gathering point (F1) intersects, is called the irradiation position (PS) (irradiation position of the excitation light (LR) to the target material (TG). FIG. 4 is a cross-sectional view of a light source device (2) based on the irradiation position (PS) and the plane including the rotation axis (R). In FIG. 4, the surface position (thick line in FIG. 4) at the irradiation position (PS) of the target material (TG) coincides with the positions of the light-gathering point (F1) and the light-gathering point (F2).

[0082] Here, the surface position at the irradiation position (PS) of the target material (TG) changes as the amount of target material (TG) within the rotating body (100) changes due to the recirculation or consumption of the target material (TG). Specifically, as the amount of target material (TG) within the rotating body (100) increases, the surface position at the irradiation position (PS) of the target material (TG) changes to move closer to the rotation axis (R). Also, as the amount of target material (TG) within the rotating body (100) decreases, the surface position at the irradiation position (PS) of the target material (TG) changes to move further away from the rotation axis (R).

[0083] Due to a change in the surface position of the target material (TG), the relative position between the surface position at the irradiation position (PS) of the target material (TG) and the concentration point (F1) or the concentration point (F2) may change. A change in the relative position causes defocus of the optical member (OP1) or the optical member (OP2) on the target material (TG), and causes a change in the size or position of the plasma (PZ), and a change in the intensity of the emitted light (LE). As such, a change in the relative position impairs the stability of the light (LE) emitted from the light source device (1). Therefore, the control unit (300) changes the position of the rotating body (100) as described below.

[0084] The control unit (300) displaces the shaft (120) so that when the surface position of the target material (TG) is displaced, the relative position between the surface position at the irradiation position (PS) of the target material (TG) and at least one of the concentrating point (F1) and the concentrating point (F2) becomes approximately constant before and after the displacement of the surface position. For example, the control unit (300) displaces the shaft (120) in the first displacement direction when the surface position of the target material (TG) is displaced by a predetermined amount in the direction of increase of the target material (TG) due to the recirculation of the target material (TG). In addition, the control unit (300) may displace the shaft (120) in the first displacement direction when the surface position of the target material (TG) is displaced by a predetermined amount in the direction of decrease of the target material (TG) due to the consumption of the target material (TG). Additionally, the control unit (300) may displace the shaft (120) in a second displacement direction when the surface position of the target material (TG) is displaced by a predetermined amount in the direction of increase (decrease) of the target material (TG) due to the recirculation (consumption) of the target material (TG).

[0085] The control unit (300) may displace the shaft (120) to at least one of the first displacement direction and the second displacement direction when it is predicted that the surface position of the target material (TG) will be displaced by a predetermined amount in the direction of increase of the target material (TG).

[0086] The acquisition unit (400) may acquire the surface position at the irradiation location of the target material (TG) by measuring it. In this case, the control unit (300) acquires the displacement of the surface position of the target material (TG) at the irradiation location (PS). However, if the acquisition unit (400) is placed near the irradiation location (PS) so that the surface position at the irradiation location (PS) of the target material (TG) can be acquired by measuring it, there is a risk that the acquisition unit (400) may be affected by debris or heat.

[0087] Therefore, it is preferable to position the acquisition unit (400) so as to face a surrounding position away from the irradiation position (PS). The surrounding position includes a part other than the irradiation position (PS) on the holding surface (113) of the target holding unit (110). For example, it is acceptable to position the acquisition unit (400) so as to face a position (P1) on the opposite side of the irradiation position (PS) with respect to the rotation axis (R). By doing so, the influence of debris or heat can be suppressed. Additionally, as long as the influence of debris or heat can be reduced, the acquisition unit (400) is not limited to the position (P1) and may be positioned to face a surrounding position other than the position (P1).

[0088] In this way, the acquisition unit (400) may acquire the surface position at a surrounding location other than the irradiation location (PS) by actually measuring it. In this case, the control unit (300) acquires the surface position of the target material (TG) at the irradiation location (PS) from the result of the acquisition unit (400) acquiring the surface position of the target material (TG) at a location different from the irradiation location (PS). The control unit (300) may acquire the displacement of the surface position of the target material (TG) at the surrounding location from the surface position of the target material (TG) at the surrounding location acquired by the acquisition unit (400), and furthermore, may predict the displacement of the surface position of the target material (TG) at the irradiation location (PS). In addition, the control unit (300) may predict the displacement of the surface position of the target material (TG) by considering the tilt or vibration with respect to the rotation axis (R) of the target holding unit (110).

[0089] For example, the acquisition unit (400) acquires the surface position of the target material (TG) at a position ahead of the irradiation position (PS) with respect to the direction of rotation of the target holding unit (110). The control unit (300) acquires the displacement of the surface position of the target material (TG) at a peripheral position that can be placed ahead of the irradiation position (PS), and predicts the displacement of the surface position of the target material (TG) at the irradiation position (PS) from the acquired displacement. In this case, the control unit (300) can predict the displacement of the surface position of the target material (TG) at the irradiation position (PS) at the time when the excitation light (LR) reaches the irradiation position (PS) (irradiation time) by considering the rotation speed of the target holding unit (110). In this way, the control unit (300) acquires the displacement of the surface position of the target material (TG) at the irradiation position (PS) by predicting the displacement of the surface position of the target material (TG) at the irradiation position (PS).

[0090] The acquisition unit (400) may acquire the surface position of the target material (TG) as a relative position with respect to the optical member (OP2). Additionally, the control unit (300) may acquire the displacement of the surface position of the target material (TG) as a relative position with respect to the optical member (OP2). Specifically, the acquisition unit (400) may acquire the surface position of the target material (TG) at the irradiation position (PS) as a relative position with respect to the optical member (OP2) by actual measurement, and may acquire the surface position at a surrounding position as a relative position with respect to the optical member (OP2) by actual measurement. Accordingly, the control unit (300) may acquire the displacement of the surface position of the target material (TG) at the irradiation position (PS) as a relative position with respect to the optical member (OP2).

[0091] The acquisition unit (400) may acquire the surface position of the target material (TG) based on the thickness from the holding surface (113) of the molten target material (TG). Accordingly, the control unit (300) may acquire the displacement of the surface position of the target material (TG) based on the thickness from the holding surface (113) of the molten target material (TG). In addition, in the case where the target material (TG) is a solid material fixed to a cylindrical drum, the acquisition unit (400) may acquire the surface position of the target material (TG) based on the inclination or vibration amount of the drum, in addition to the thickness from the upper surface (surface layer) of the drum of the surface of the solid material fixed to the drum. The control unit (300) may acquire the displacement of the surface position of the target material (TG) based on the inclination or vibration amount of the drum, in addition to the thickness from the upper surface (surface layer) of the drum of the surface of the solid material fixed to the drum. Additionally, the acquisition unit (400) may acquire the surface position of the target material (TG) by measuring the distance from the acquisition unit (400) to the surface position of the target material (TG).

[0092] The control unit (300) may combine other sensors with the acquisition unit (400) to acquire the displacement of the surface position at the irradiation position (PS) of the target material (TG). By doing so, the displacement of the surface position due to temperature changes of each member of the light source device (2) and the displacement of the surface position due to stress changes can be supplemented by other sensors. Specifically, the control unit (300) may correct the displacement of the surface position of the target material (TG) based on the temperature change acquired by the temperature sensor installed in the target holding unit (110). In addition, the control unit (300) may correct the displacement of the surface position of the target material (TG) based on the stress change acquired by the stress sensor installed in the target holding unit (110).

[0093] Additionally, the acquisition of the displacement of the surface position by the control unit (300) may include detecting that a displacement of the surface position is occurring at that time (i.e., acquiring the fact of displacement) or calculating the amount of displacement. For example, the control unit (300) may detect that the surface position of the target material (TG) at that time has been displaced from the surface position of the target material (TG) at the time when the excitation light (LR) irradiated the target material (TG) in the previous time, or calculate the amount of displacement.

[0094] Additionally, the control unit (300) may detect that the surface position of the target material (TG) is displaced from a reference surface position (i.e., a reference position of the surface position. For example, it may be a position overlapping with the light-gathering point (F1)), or may calculate the amount of displacement. Additionally, the acquisition of the surface position displacement by the control unit (300) may include predicting the occurrence of or amount of displacement of the surface position at a future point in time (for example, when the excitation light (LR) is irradiated). For example, the control unit (300) may predict that the surface position of the target material (TG) at the time when the target material (TG) is irradiated with the excitation light (LR) from now on is displaced from the surface position of the target material (TG) at the time when the target material (TG) was irradiated with the excitation light (LR) in the previous instance, or may predict the amount of displacement. Additionally, the control unit (300) may predict that the surface position of the target material (TG) at the time when the target material (TG) is irradiated with the excitation light (LR) is displaced from the reference position, or predict the amount of such displacement.

[0095] FIG. 6 is a flowchart illustrating a control method of a light source device (2) according to embodiment 2. As shown in FIG. 6, the control method of the light source device (2) of the present embodiment further comprises step S15 of acquiring the state of a holding surface (113) that holds a target material (TG). Step S15 may be performed between step S10 and step S20.

[0096] In step S15, the control unit (300) acquires the state of the holding surface (113) that holds the target material (TG) in the target holding unit (110) to the acquisition unit (400). In this case, in step S20, the control unit (300) may displace the shaft unit (120) based on the result of acquiring the state of the holding surface (113) in the acquisition unit (400).

[0097] Additionally, in step S15, the acquisition unit (400) may acquire the displacement of the surface position of the target material (TG). In this case, in step S20, the control unit (300) displaces the shaft unit (120) so that when the surface position is displaced, the relative position between the surface position and at least one of the light-gathering point (F1) and the light-gathering point (F2) becomes approximately constant before and after the displacement of the surface position. Additionally, the control unit (300) may displace the shaft unit (120) in the first displacement direction when the surface position of the target material (TG) is displaced by a predetermined amount in the direction of increase of the target material (TG).

[0098] Additionally, in step S15, the control unit (300) may acquire the surface position of the target material (TG) at the irradiation position (PS) based on the state of the holding surface (113) at a position different from the irradiation position (PS) acquired by the acquisition unit (400). The control unit (300) may also acquire the surface position from the result of acquiring a position different from the light-gathering point (F1) by the acquisition unit (400). For example, the control unit (300) may acquire the surface position from the result of acquiring the state of the position (P1) by the acquisition unit (400).

[0099] Next, the effects of the present embodiment are explained. The light source device (2) of the present embodiment is equipped with an acquisition unit (400) that acquires the state of a holding surface (113) that holds the target material (TG). Accordingly, the light source device (2) can displace the shaft (120) to an optimal position according to the state of the holding surface (113). For example, when a recirculation of the target material (TG) occurs, the acquisition unit (400) acquires the displacement of the surface position of the target material (TG). Then, the control unit (300) displaces the shaft (120) to cancel the displacement of the surface position of the target material (TG) caused by the recirculation. Specifically, the control unit (300) acquires the displacement of the surface position at the irradiation position (PS) of the target material (TG) based on the detection result from the acquisition unit (400). And, the control unit (300) displaces the axis unit (120) so that the relative position between the surface position at the irradiation position (PS) of the target material (TG) and at least one of the concentrating point (F1) and the concentrating point (F2) is approximately constant before and after the displacement of the surface position of the target material (TG). By doing so, the focus of the optical member (OP1) or the optical member (OP2) on the target material (TG) can be maintained very appropriately, and the stability of the light (LE) emitted from the light source device (2) can be improved.

[0100] <Embodiment 3>

[0101] FIG. 7 is a cross-sectional view illustrating a light source device (3) according to embodiment 3. As shown in FIG. 7, the light source device (3) may further be provided with a shield (700). The shield (700) covers an opening on the +Z axis side of the cylindrical part (111) in the target holding part (110). The shield (700) is, for example, in the shape of a plate. Furthermore, the shield (700) is not limited to a plate shape and may be in the shape of a film as long as it can cover an opening on the +Z axis side of the cylindrical part (111) in the target holding part (110). Also, the shield (700) may have a hole through which excitation light (LR) and light (LE) pass. In that case, the shield (700) may have a cover that covers the area around the hole to suppress the scattering of debris from the hole. The shield (700) may include a debris shield (710) and a debris catcher (720).

[0102] The debris shield (710) covers the opening on the +Z-axis side of the cylindrical part (111) in the target holding part (110). By doing so, the scattering of debris to the outside of the light source device (3) can be suppressed. Additionally, the debris shield (710) may capture the debris and return it to the target holding part (110) as target material (TG), that is, recirculate it.

[0103] The debris catcher (720) covers the area around the point of concentration (F1) of the excitation light (LR). Since the debris catcher (720) covers the area around the point of concentration (F1) where debris is most likely to occur in the target holding part (110), it can effectively suppress the scattering of debris.

[0104] The control unit (300) displaces the shaft portion (120) in the second displacement direction by controlling the second magnetic force generating unit (212) so that the distance between the shield (700) and the target holding unit (110) becomes a predetermined target amount. Specifically, the control unit (300) displaces the shaft portion (120) in the second displacement direction by controlling the second magnetic force generating unit (212) so that the distance (D1) between the debris shield (710) (shield (700)) and the cylindrical portion (111) becomes a predetermined target amount. In addition, the control unit (300) displaces the shaft portion (120) in the second displacement direction by controlling the second magnetic force generating unit (212) so that the distance (D2) between the debris catcher (720) and the bottom portion (112) becomes a predetermined target amount. Additionally, the control unit (300) controls the second magnetic force generating unit (212) so that the distance (D3) between the debris shield (710) and the bottom unit (112) becomes a predetermined target amount, thereby displacing the shaft unit (120) in the second displacement direction.

[0105] Additionally, as an example, the control unit (300) can obtain distances (D1, D2 and D3) as follows. That is, the control unit (300) obtains distance (D1) based on the output value of a displacement meter (730) that irradiates a measurement light from the debris shield (710) toward the cylindrical part (111) and the known position of the debris shield (710). Also, the control unit (300) obtains distance (D3) based on the output value of a displacement meter (740) that irradiates a measurement light from the debris shield (710) toward the bottom part (112) and the known position of the debris shield (710). Additionally, if the height (d1) of the cylindrical part (111) is known, the control unit (300) can obtain the other distance (D1) by distance (D1) + height (d1) or distance (D3) - height (d1) based on the height (d1) and either the measurement value of distance (D1) or distance (D3). In this case, it is acceptable to install only one of the displacement meter (730) or the displacement meter (740) in the light source device (3). Furthermore, the control unit (300) can obtain the distance (D2) from the difference (distance (D3) - distance (D2)) between the distance (D3) and the distance (D2) from the known debris shield (710) to the tip of the debris catcher (720).

[0106] The control unit (300) may displace the shaft (120) in the second displacement direction so that the distance (D1 and D2) becomes larger when the establishment of a predetermined condition is detected. Additionally, the control unit (300) may displace the shaft (120) in the second displacement direction so that the distance between the shield (700) and the target holding unit (110) becomes larger when the establishment of a predetermined condition is detected. The distance between the shield (700) and the target holding unit (110) may be evaluated as at least one of the distances (D1, D2, and D3). The predetermined condition includes, for example, detecting a vibration greater than a predetermined value of the rotating body (100), and detecting a rotational speed less than a predetermined value of the rotating body (100). The predetermined condition may include a case where the temperature of the target material (TG) is not above a predetermined value. By doing so, interference between the target holding part (110) and surrounding members caused by factors such as when the target material (TG) is not sufficiently melted or other factors can be prevented, and the operation of the light source device (3) can be stabilized. Additionally, when the temperature of the target material (TG) is not above a predetermined level, the light source device (3) may be prepared for operation or preparation for stopping. The control unit (300) may displace the shaft part (120) in the second displacement direction so that the distance between the shield (700) and the target holding part (110) becomes greater than the distance during normal operation of the light source device (3). At this time, the control unit (300) may rotate the target holding part (110) even during the preparation for operation or preparation for stopping of the light source device (3).

[0107] The control unit (300) may displace the shaft (120) in the second displacement direction so that the distance between the shield (700) and the target holding unit (110) when the excitation light (LR) is continuously irradiated onto the target material (TG) becomes smaller than the distance between the shield (700) and the target holding unit (110) when the excitation light (LR) is not continuously irradiated onto the target material (TG). By doing so, scattering of the target material (TG) to the outside of the target holding unit (110) can be suppressed, and the influence of surface position fluctuations when debris is recirculated can be reduced, thereby stabilizing the operation of the light source device (3). Furthermore, when the excitation light (LR) is not continuously irradiated onto the target material (TG), the case in which the irradiation of the excitation light (LR) to the target material (TG) is stopped is included.

[0108] Next, a control method for the light source device (3) of the present embodiment is described based on FIG. 6. In the present embodiment, step S15 may be omitted. In the present embodiment, in step S20, the control unit (300) may displace the shaft (120) in the second displacement direction by controlling the second magnetic force generating unit (212) so that the distance between the shield (700) and the target holding unit (110) (at least one of distance (D1) and distance (D2)) becomes a predetermined target amount. Also, in step S20, when the control unit (300) detects the establishment of a predetermined condition, the shaft (120) may displace the shaft in the second displacement direction so that at least one of distances (D1 and D2) becomes larger. That is, in step S20, when the control unit (300) detects the establishment of a predetermined condition, it may change at least one of the distances (D1 and D2) to a larger target amount and displace the shaft (120) in the second displacement direction so that the distance between the shield (700) and the target holding unit (110) becomes the target amount after the change. Also, in step S20, the control unit (300) may displace the shaft (120) in the second displacement direction so that the distance between the shield (700) and the target holding unit (110) when the excitation light (LR) is continuously irradiated onto the target material (TG) becomes smaller than the distance between the shield (700) and the target holding unit (110) when the excitation light (LR) is not continuously irradiated onto the target material (TG).

[0109] Next, the effects of the present embodiment are explained. The light source device (3) of the present embodiment can displace the shaft (120) by controlling the magnetic force generating unit (210) so that the distance between the shield (700) and the target holding unit (110) becomes a predetermined target amount. In this way, since the position alignment of the shaft (120) in the vertical direction becomes easy in the present embodiment, the control of the clearance between the shield (700) and the target holding unit (110) can be easily controlled, and the light source device (3) can achieve stable operation.

[0110] <Embodiment 4>

[0111] Next, a light source device (3) is described as embodiment 4. FIG. 8 is a graph illustrating the amount of vibration rotation from the rotation axis (R) when the rotating body (100) rotates around the rotation axis (R) in the light source device (3) according to embodiment 4, wherein the horizontal axis represents the frequency of rotation of the rotating body (100) and the vertical axis represents the amount of vibration rotation. The horizontal axis and the vertical axis each increase in the direction of the arrow.

[0112] FIG. 8 shows the case where the mass M of the rotating body (100) is mass M1 and mass M2, respectively, with the target material (TG) present (M1+TG and M2+TG) and without the target material (TG) (M1 and M2). The relationship between the four masses M1, mass M1+TG, mass M2, and mass M2+TG is mass M2+TG > mass M2 > mass M1+TG > mass M1.

[0113] As shown in Fig. 8, each mass (mass M1, mass M1+TG, mass M2, mass M2+TG) has a frequency at which the amount of vibration rotation peaks when the frequency is changed. The velocity (angular velocity) derived from the frequency at which the amount of vibration rotation peaks is called the critical velocity (critical angular velocity) and is expressed as ωn=√(K / M). Here, k is the spring constant and can also be described as the axial stiffness coefficient in a physical system model that rotates an object around an elastic axis.

[0114] As the mass M increases, the critical speed (ωn) decreases. Also, when the frequency exceeds the critical speed (ωn), the amount of vibration rotation decreases as the mass M increases. When there is a target material (TG) such as molten metal, the critical speed (ωn) decreases, and the amount of vibration rotation when the frequency exceeds the critical speed (ωn) also decreases. This can be attributed to the balancing effect of the liquid.

[0115] In this embodiment, the rotating body (100) and the shaft portion (120) have a mass M and a spring constant k such that the critical angular velocity (ωn) when the rotating body (100) rotates is 85% or less of the target rotational angular velocity (ω0). Here, the target rotational angular velocity (ω0) is the angular velocity that rotates the rotating body (100) as a target and is an angular velocity corresponding to the aforementioned target rotational velocity. As an example, it may be ensured that the critical angular velocity (ωn) when the rotating body (100) rotates is 85% or less of the target rotational angular velocity (ω0) by at least one of (1) making the mass M sufficiently large, and (2) making the spring constant k sufficiently small by bending the shaft portion (120) on the bottom (112) side of the rotating body (100) to make the shaft diameter thin.

[0116] The mass M of the rotating body (100) may be the mass in a state where the target material (TG) is not being fed into the rotating body (100). The mass M of the rotating body (100) may be the sum of the mass of the target material (TG) in a state where the target material (TG) is fed in an amount less than a predetermined target amount, an amount equal to a predetermined target amount, or an amount greater than a predetermined target amount. Among these, if the mass M of the rotating body (100) is set as the mass of the rotating body (100) in a state where the target material (TG) is not being fed, the total mass of the rotating body (100) when the target material (TG) is fed increases by the mass of the target material (TG). Then, the critical speed at which the vibration rotation amount in this case is maximized is an angular velocity smaller than the critical angular velocity (ωn) = √(K / M) in the state where the target material (TG) is not being fed, that is, the critical angular velocity (ωn) is further separated from the target rotational angular velocity (ω0), which is desirable.

[0117] <Embodiment 5>

[0118] Next, as Embodiment 5, an optical device including a light source device will be described. Below, an inspection device will be used as an example of the optical device.

[0119] FIG. 9 is a configuration diagram illustrating an inspection device (10) equipped with a light source device (1) according to embodiment 5. As shown in FIG. 9, the inspection device (10) is equipped with an illumination optical system (20), an inspection optical system (30), a detector (41), and a processing unit (42). Additionally, the inspection device (10) may also be equipped with a light source device (1). The inspection device (10) is a device that inspects defects, etc., of an object (50) by using light (LE) generated from the light source device (1) as illumination light (L1). The object (50) is, for example, an EUV mask. Additionally, the object (50) is not limited to an EUV mask and may be a semiconductor substrate, etc.

[0120] The illumination optical system (20) has an elliptical mirror (21), an elliptical mirror (22), and a drop mirror (23). The inspection optical system (30) has an opening concave mirror (31), a convex mirror (32), a flat mirror (33), and a concave mirror (34). The opening concave mirror (31) and the convex mirror (32) constitute a Schwarzschild magnifying optical system.

[0121] The light source device (1) generates illumination light (L1) from the extracted light (LE). The illumination light (L1) includes, for example, EUV light (LE) of 13.5 nm, which is the same as the exposure wavelength of the EUV mask that is the object (50). Additionally, the illumination light (L1) may include light other than EUV light. The illumination light (L1) extracted from the light source device (1) is reflected by the ellipsoidal mirror (21). The illumination light (L1) reflected by the ellipsoidal mirror (21) travels while narrowing and is concentrated at the convergence point (IF1). Thus, the ellipsoidal mirror (21) reflects the illumination light (L1) generated from the light source device (1) as converged light. The convergence point (IF1) is a location that is in a co-space with the upper surface (51) of the object (50), such as the EUV mask, and the detection surface (41a) of the detector (41).

[0122] The illumination light (L1) passes through the convergence point (IF1), spreads out, and travels to be incident on a reflector such as an elliptical mirror (22). Thus, the illumination light (L1) reflected from the elliptical mirror (21) is incident on the elliptical mirror (22) as divergent light through the convergence point (IF1). The illumination light (L1) incident on the elliptical mirror (22) is reflected by the elliptical mirror (22), travels while narrowing, and is incident on the drop mirror (23). That is, the elliptical mirror (22) reflects the incident illumination light (L1) as convergent light. Then, the elliptical mirror (22) directs the illumination light (L1) to the drop mirror (23). The drop mirror (23) is positioned directly above the EUV mask. The illumination light (L1) incident on and reflected by the drop mirror (23) is incident on the object (50). Accordingly, the drop mirror (23) causes the illumination light (L1) reflected from the elliptical mirror (22) to be incident on the object (50) by reflecting the illumination light (L1) reflected from the elliptical mirror (22) to the object (50).

[0123] The elliptical mirror (22) concentrates the illumination light (L1) onto the object (50). When the illumination light (L1) illuminates the object (50), the illumination optical system (20) is installed to form an image of the light source device (1) on the upper surface (51) of the object (50). Thus, the illumination optical system (20) becomes a critical illumination. In this way, the illumination optical system (20) illuminates the object (50), such as an EUV mask, using the critical illumination generated by the illumination light (L1) from the light source device.

[0124] The object (50) is placed on the stage (52). Here, a plane parallel to the upper surface (51) of the object (50) is designated as the αβ plane, and a direction perpendicular to the αβ plane is designated as the γ-axis direction. The illumination light (L1) is incident on the object (50) from a direction inclined from the γ-axis direction. That is, the illumination light (L1) is incident obliquely to illuminate the object (50).

[0125] The stage (52) is a three-dimensional driving stage having a driving unit (53). The driving unit (53) can illuminate a desired area of ​​an object (50) by moving the stage (52) within the αβ plane. In addition, the driving unit (53) can perform focus adjustment by moving the stage (52) in the γ-axis direction.

[0126] The illumination light (L1) from the light source device (1) illuminates the inspection area of ​​the object (50). The inspection area illuminated by the illumination light (L1) is, for example, 0.5 mm angle. Also, the inspection area is not limited to 0.5 mm angle. The illumination light (L1) is incident on the object (50) in a direction tilted with respect to the γ-axis direction. The light from the object (50) illuminated by the illumination light (L1) is incident on the hole-opening concave mirror (31). Hereinafter, the light from the object (50) illuminated by the illumination light (L1) is described as reflected light (L2). Also, the light incident on the hole-opening concave mirror (31) from the object (50) is not limited to reflected light (L2) and may include diffracted light, etc. The reflected light (L2) reflected from the object (50) is incident on the hole-opening concave mirror (31). A hole (31a) is installed in the center of the hole-opening concave mirror (31). The hole-opening concave mirror (31) collects reflected light (L2) from an object (50) and reflects the collected reflected light (L2) as convergent light.

[0127] The reflected light (L2) reflected from the open-hole concave mirror (31) is incident on the convex mirror (32). The convex mirror (32) reflects the reflected light (L2) reflected from the open-hole concave mirror (31) toward the hole (31a) of the open-hole concave mirror (31). The reflected light (L2) passing through the hole (31a) is incident on the flat mirror (33). The flat mirror (33) directs the reflected light (L2) reflected from the convex mirror (32) as convergent light through the hole (31a) of the open-hole concave mirror (31). The reflected light (L2) incident on the flat mirror (33) is reflected back to the flat mirror (33). The reflected light (L2) reflected from the flat mirror (33) travels while narrowing and is concentrated at the convergence point (IF2). Therefore, the planar mirror (33) reflects the incident reflected light (L2) as converged light. The convergence point (IF2) is sometimes referred to as an aperture. The convergence point (IF2) is located in a position that is conjugated with the upper surface (51) of the object (50) and the detection surface (41a) of the detector (41).

[0128] The reflected light (L2) passes through the convergence point (IF2), spreads out, and proceeds to be incident on the concave mirror (34). Thus, the reflected light (L2) reflected from the flat mirror (33) as convergent light is incident on the concave mirror (34) as divergent light through the convergence point (IF2). The concave mirror (34) reflects the incident reflected light (L2) as convergent light to the detector (41). The reflected light (L2) reflected from the concave mirror (34) is detected by the detector (41). In this way, the inspection optical system (30) inspects the object (50) to be inspected using the illumination light (L1) extracted from the output optical system (600) of the light source device (1). That is, the inspection optical system (30) collects reflected light (L2) from an object (50) illuminated by illumination light (L1) and directs the collected reflected light (L2) to a detector (41).

[0129] The detector (41) may include a TDI (Time Delay Integration) sensor. The detector (41) receives light from an object (50) illuminated by an illumination light (L1). The area on the object (50) detected by the detector (41) is called a viewing area (51a). The detector (41) receives reflected light (L2) from the viewing area (51a) illuminated by the illumination light (L1). The viewing area (51a) may be included in the inspection area illuminated by the illumination light (L1). The detector (41) acquires image data of an object (50), such as an EUV mask. If the detector (41) includes a TDI sensor, the detector (41) includes a plurality of imaging elements arranged in a line shape in one direction. The imaging elements are, for example, a CCD (Charge Coupled Device). Furthermore, the imaging elements are not limited to a CCD.

[0130] Image data of an object (50) acquired by the detector (41) is output to a processing unit (42) and processed in the processing unit (42). The processing unit (42) may be, for example, an information processing device such as a server device or a personal computer.

[0131] The reflected light (L2) contains information such as defects in the object (50). Specular reflection of the illumination light (L1) incident on the object (50) in a direction tilted with respect to the Z-axis direction is detected by the inspection optical system (30). If a defect exists in the object (50), the defect is observed as a dark image. This method of observation is called bright-field observation. Additionally, the inspection device (10) may incident the illumination light (L1) on the object (50) in the Z-axis direction and detect it by the inspection optical system (30). If a defect exists in the object (50), the defect is observed as a bright image. This method of observation is called dark-field observation.

[0132] Thus, the inspection device (10) of the present embodiment comprises the light source device (1) described above and an inspection optical system (30) that inspects an inspection target using light (LE) extracted from an output optical system (600). An inspection method using the inspection device (10) comprises a step of inspecting an inspection target using light (LE) extracted according to the control method of the light source device (1) described above. Furthermore, although the inspection device (10) has been described as an optical device, the optical device may be an exposure device. For example, the exposure device comprises the light source device (1) described above and an exposure optical system that exposes an exposure target using light (LE) extracted from an output optical system (600). An exposure method using the exposure device comprises a step of exposing an exposure target using light (LE) extracted according to the control method of the light source device (1) described above.

[0133] Next, the effects of the present embodiment are explained. The optical device including the inspection device (10) of the present embodiment is equipped with a light source device (1). Accordingly, the stability of the illumination light (L1) illuminating the object (50) can be improved. Other configurations and effects are included in the description of embodiments 1 to 4 above.

[0134] Although embodiments of the present disclosure have been described above, the present disclosure includes suitable modifications that do not impair its purpose and advantages, and furthermore, is not limited by the above embodiments. Additionally, each component of embodiments 1 to 5 may be combined in a suitable manner. Furthermore, light source devices (1 to 3) equipped with a control unit (300) having the following configuration are also within the scope of the technical concept of the embodiments.

[0135] The control unit (300) is equipped with a processor, memory, and a storage device as a configuration not shown. The storage device stores a program that executes each process of the control method of the light source device according to each embodiment on a computer. The corresponding processor reads the program from the storage device into memory and executes the program. By doing so, the processor realizes each function of the control unit (300). Furthermore, the components of the control unit (300) may each be realized as dedicated hardware. Also, some or all of each component may be realized by general-purpose or dedicated circuits, processors, etc., or a combination thereof. These may be configured by a single chip or by multiple chips connected via a bus. Some or all of each component may be realized by a combination of the aforementioned circuits, etc., and a program. Also, a CPU (Central Processing Unit), GPU (Graphics Processing Unit), etc., may be used as the processor. In the examples described above, the program comprises a set of instructions (or software code) for causing the computer to perform one or more of the functions described in the embodiments when read by the computer. The program may be stored in a non-transient computer-readable medium or a physical storage medium. Examples, but not limited to, of a computer-readable medium or a physical storage medium include random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technologies, CD-ROM, digital versatile disc (DVD), Blu-ray (trademark) 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 transient computer-readable medium or a communication medium.As an example, though not limited to, a temporary computer-readable medium or communication medium includes a general signal of an electrical, optical, acoustic, or other form. Explanation of the symbols

[0136] 1, 2, 3 light source devices 10 inspection devices 20 Illumination Optical System 21 Elliptical mirror 22 Elliptical mirror 23 Falling Mirror 30 inspection optical system 31 Hole-opening concave mirror 31a hole 32 Convex Mirror 33 Planar mirror 34 Concave Mirror 41 detector 41a Detection surface 42 Processing Unit 50 objects 51 Top surface 51a field of view Stage 52 53 Drive unit 100 revolutions 110 Target Maintenance Unit 111 cylindrical part 112 bottom 113 Yujimyeon 114 Shield 120 shafts 121, 122 end 130 disc section 200 Chukji Branch 210 Magnetic field generator 211 1st Magnetic Force Generator 212 Second Magnetic Force Generator 220 sensor 230 case 300 control unit 400 Acquisition Department 500 input optical system 600 output optical system 700 Shields 710 Debris Shield 720 Debris Catcher 730 displacement gauge 740 displacement gauge F1, F2 concentration points L1 Lighting L2 reflected light LE Optical LR Here Gwang OP1, OP2 optical components P1 location PS investigation location PZ plasma TG target material

Claims

Claim 1 A light source device comprising: a target holding member that holds a target material serving as a plasma source for generating plasma; a rotating body including a shaft member connected to the target holding member; the rotating body that rotates around a rotation axis passing through the shaft member; a magnetic force generating member that applies magnetic force to the shaft member; a shaft supporting member that supports the shaft member; and a control member that controls the magnetic force generating member. The shaft supporting member supports the shaft member rotatably while the shaft member is levitized by the magnetic force through the magnetic force generating member, and the control member displaces the shaft member by controlling the magnetic force generating member. Claim 2 A light source device according to claim 1, wherein the magnetic generating unit comprises a first magnetic generating unit that applies the magnetic force to the shaft portion, and the control unit controls the first magnetic generating unit to displace the shaft portion in a first displacement direction including a component perpendicular to the rotation axis. Claim 3 A light source device according to claim 1, wherein the rotating body further comprises, in a disc portion connected to the shaft portion, the disc portion having a diameter different from the diameter of the shaft portion, the magnetic force generating unit comprises a second magnetic force generating unit that applies the magnetic force to the disc portion, and the control unit displaces the shaft portion in a second displacement direction including a component parallel to the rotation axis by controlling the second magnetic force generating unit. Claim 4 A light source device according to paragraph 2, wherein when the target material generates plasma, the control unit rotates the rotating body at a target rotational speed and controls the first magnetic force generating unit to displace the shaft in the first displacement direction while the shaft is rotating at the target rotational speed. Claim 5 A light source device according to paragraph 2, further comprising an acquisition unit for acquiring the state of a holding surface that holds the target material in the target holding unit, and the control unit for displaces the shaft in the first displacement direction based on the result of acquiring the state of the holding surface in the acquisition unit. Claim 6 A light source device according to claim 5, wherein the state of the holding surface comprises at least one of the amount of the target material held on the holding surface, the surface position of the target material, the surface roughness of the target material, and the surface roughness of the holding surface. Claim 7 A light source device according to claim 5, further comprising: an input optical system that irradiates the excitation light onto the target material, having a first focusing point on the target material side of a first optical member that focuses the excitation light onto the target material; and an output optical system that extracts the light generated from the plasma source, having a second focusing point on the target material side of a second optical member that focuses the light generated from the plasma source; wherein the acquisition unit acquires the displacement of the surface position of the target material; and the control unit, when the surface position is displaced, displaces the axis portion such that the relative position between the surface position at the irradiation position of the excitation light of the target material and at least one of the first focusing point and the second focusing point is constant before and after the displacement of the surface position. Claim 8 A light source device according to paragraph 3, wherein the target holding part comprises a cylindrical part and a bottom part that blocks an opening on one side of the cylindrical part, and further comprises a shield that covers an opening on the other side of the cylindrical part, and the control part controls the second magnetic force generating part so that the distance between the shield and the cylindrical part becomes a predetermined target amount, thereby displacing the shaft part in the second displacement direction. Claim 9 A light source device according to claim 8, wherein the control unit, when detecting the establishment of a predetermined condition, displaces the shaft portion in the second displacement direction so that the distance becomes greater, and the predetermined condition includes at least one of detecting a vibration greater than a predetermined value of the rotating body and detecting a rotational speed less than a predetermined value of the rotating body. Claim 10 In claim 7, the light source device wherein the control unit acquires the surface position of the target material at the irradiation position based on the state of the maintenance surface at a position different from the irradiation position acquired by the acquisition unit. Claim 11 In claim 7, the control unit is a light source device that, when the surface position is displaced by a predetermined amount in the direction of increase of the target material, displaces the shaft in the first displacement direction. Claim 12 A method for controlling a light source device comprising: a target holding member that holds a target material serving as a plasma source for generating plasma; a rotating body including a shaft member connected to the target holding member, wherein the rotating body rotates around a rotational axis passing through the shaft member; a magnetic force generating member that applies magnetic force to the shaft member; a shaft supporting member that supports the shaft member; and a control member that controls the magnetic force generating member. The method further comprises a step in which the shaft supporting member supports the shaft member rotatably while the shaft member is levitized by the magnetic force through the magnetic force generating member, and a step in which the control member displaces the shaft member by controlling the magnetic force generating member. Claim 13 A method for controlling a light source device according to claim 12, wherein the magnetic generating unit comprises a first magnetic generating unit that applies the magnetic force to the shaft portion, and in a step of displacing the shaft portion, the control unit controls the first magnetic generating unit to displace the shaft portion in a first displacement direction including a component perpendicular to the rotation axis. Claim 14 A method for controlling a light source device according to claim 12, wherein the rotating body further comprises, in a disc portion connected to the shaft portion, the disc portion having a diameter different from the diameter of the shaft portion, and the magnetic force generating unit comprises a second magnetic force generating unit that applies the magnetic force to the disc portion, and in a step of displacing the shaft portion, the control unit displaces the shaft portion in a second displacement direction including a component parallel to the rotation axis by controlling the second magnetic force generating unit. Claim 15 A method for controlling a light source device according to claim 13, wherein in a step of rotatably supporting the shaft portion, when the target material generates plasma, the control unit rotates the rotating body at a target rotational speed, and in a step of displacing the shaft portion, the control unit controls the first magnetic force generating unit so that, while the shaft portion is rotating at the target rotational speed, the shaft portion is displaced in the first displacement direction. Claim 16 A method for controlling a light source device according to claim 13, further comprising a step of acquiring the state of a holding surface that holds the target material in the target holding part in the acquiring part, and in the step of displacing the shaft part, the control part displaces the shaft part in the first displacement direction based on the result of acquiring the state of the holding surface in the acquiring part. Claim 17 A method for controlling a light source device according to claim 16, wherein the state of the holding surface comprises at least one of the amount of the target material held on the holding surface, the surface position of the target material, the surface roughness of the target material, and the surface roughness of the holding surface. Claim 18 In claim 16, the light source device further comprises an input optical system that irradiates the excitation light onto the target material, having a first focusing point on the target material side of a first optical member that focuses the excitation light onto the target material, and an output optical system that extracts the light generated from the plasma source, having a second focusing point on the target material side of a second optical member that focuses the light generated from the plasma source, wherein in a step of acquiring the state of the holding surface by an acquiring unit, the acquiring unit acquires the displacement of the surface position of the target material, and in a step of displacing the axis, the control unit displaces the axis such that when the surface position is displacing, the relative position between the surface position at the irradiation position of the excitation light of the target material and at least one of the first focusing point and the second focusing point is constant before and after the displacement of the surface position. Claim 19 A method for controlling a light source device according to claim 14, wherein the target holding member comprises a cylindrical member and a bottom member that blocks an opening on one side of the cylindrical member, and the light source device further comprises a shield that covers an opening on the other side of the cylindrical member, and in at least one of a step that rotatably supports the shaft member and a step that displaces the shaft member, the control member displaces the shaft member in the second displacement direction by controlling the second magnetic force generating member so that the distance between the shield and the cylindrical member becomes a predetermined target amount. Claim 20 A method for controlling a light source device according to claim 19, wherein in at least one of a step for rotatably supporting the shaft portion and a step for displacing the shaft portion, the control unit displaces the shaft portion in the second displacement direction such that the distance becomes greater when the establishment of a predetermined condition is detected, and the predetermined condition includes at least one of detecting a vibration greater than a predetermined value of the rotating body and detecting a rotational speed less than a predetermined value of the rotating body. Claim 21 A method for controlling a light source device, wherein in the step of acquiring the state of the maintenance surface by the acquiring unit, the control unit acquires the surface position of the target material at the irradiation position based on the state of the maintenance surface at a position different from the irradiation position acquired by the acquiring unit. Claim 22 A method for controlling a light source device according to claim 18, wherein in the step of displacing the shaft portion, the control portion displaces the shaft portion in the first displacement direction when the surface position is displaced by a predetermined amount in the direction of increase of the target material.

Images