Light source apparatus

Abstract

A light source device is provided that can improve the stability of extracted light. The light source device 1 of the present invention includes: a target holding part 10 having a holding surface 17 for transporting a target material 12 generated by a plasma 11 to a plasma forming position 130; and a driving part 20 for driving the target holding part 10 to move the holding surface 17; the holding surface 17 is moved relative to a processing surface 117 in the space along the holding surface 17; the processing surface 117 has: at least one plasma forming position 130; at least one supply position 140 for supplying the target material 12 to the holding surface 17; and at least one observation position 150 for acquiring state information of the target material 12 held on the holding surface 17; the plasma forming position 130, the supply position 140 and the observation position 150 are arranged along the processing surface 117; the processing surface 117 includes: the supply position 140, which is arranged further rearward than the plasma forming position 130.

Description

[Technical Field]

[0001] This invention relates to a light source device. [Previous Technology]

[0002] Patent document 1 describes a light source device in which a target material is formed on the surface of a cylindrical component rotating about a rotation axis, and illumination light is extracted by irradiating the formed target material with excitation light.

[0003] Patent Document 2 discloses a light source device that uses centrifugal force to hold a target material containing molten metal on the inner wall of a crucible rotating around a rotation axis, and extracts illumination light by irradiating the held target material with excitation light. [Prior Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-077007. [Patent Document 2] Japanese Patent Application Publication No. 2022-168463. [Summary of the Invention]

[0005] [Problem to be Solved by the Invention] In a light source device, the relative position between the light-emitting point near the surface of the target material and the optical component can change due to factors such as: vibrations generated when the cylindrical component and the target holding part such as the crucible rotate; deformation of the structure itself; deformation caused by rotational stress and heat of the target holding part itself; and the input of the target material into the target holding part. Therefore, it is believed that there may be situations where light cannot be stably extracted from the light source device.

[0006] The purpose of this invention is to solve such a problem and to provide a light source device that can improve the stability of the extracted light.

[0007] [Means for Solving the Problem] The light source apparatus of the present invention comprises: a target holding portion having a holding surface, the holding surface being used to transport a target material generated by plasma to a plasma forming position; and a driving portion driving the target holding portion to move the holding surface; the holding surface moving relative to a processing surface in space along the holding surface; the processing surface including: at least one plasma forming position; at least one supply position for supplying the target material to the holding surface; and at least one observation position for acquiring state information of the holding surface; the plasma forming position, the supply position, and the observation position being disposed along the processing surface; in the direction of movement of the holding surface driven by the driving portion, the processing surface including: the supply position disposed further rearward than the plasma forming position; and the observation position disposed further rearward than the supply position.

[0008] The light source device of the present invention comprises: a target holding portion having a holding surface, the holding surface being used to transport a target material generated by plasma to a plasma forming position; and a driving portion driving the target holding portion to move the holding surface; the holding surface being moved relative to a processing surface in space along the holding surface; the processing surface including: at least one plasma forming position; and at least one supply position for supplying the target material to the holding surface; the plasma forming position and the supply position being disposed along the processing surface; in the moving direction of the holding surface driven by the driving portion, the length of the processing surface from the plasma forming position to the supply position is shorter than the length of the processing surface from the supply position to the plasma forming position.

[0009] In the aforementioned light source device, it may also include: a forming part, which focuses laser light onto the target material at the aforementioned plasma forming position, thereby exciting the target material at the aforementioned plasma forming position.

[0010] In the aforementioned light source device, the aforementioned target holding part may also have a rotating shaft; the aforementioned drive part moves the aforementioned target material by rotating the aforementioned target holding part around the aforementioned rotating shaft.

[0011] In the aforementioned light source device, the aforementioned rotating axis system may also be approximately orthogonal to the ground plane.

[0012] In the aforementioned light source device, the aforementioned processing surface may also have: at least one observation position for obtaining state information of the aforementioned holding surface; the aforementioned plasma forming position, the aforementioned supply position and the aforementioned observation position are arranged along the aforementioned processing surface.

[0013] In the aforementioned light source device, it is also possible that, in the moving direction of the aforementioned holding surface driven by the aforementioned driving unit, the length of the aforementioned processing surface from the aforementioned supply position to the aforementioned observation position is shorter than the length of the aforementioned processing surface from the aforementioned observation position to the aforementioned plasma forming position.

[0014] In the aforementioned light source device, it may also include: a first debris shield, which is disposed in the region between the aforementioned plasma forming position and the aforementioned supply position.

[0015] In the aforementioned light source device, it may also include: a second debris shielding member, which is disposed in the area between the aforementioned supply position and the aforementioned observation position.

[0016] In the aforementioned light source device, it may also include: a third debris shielding member, which is disposed in the region between the aforementioned plasma formation position and the aforementioned observation position.

[0017] In the aforementioned light source device, it may also include: a first debris shielding member disposed in a first region between the aforementioned plasma forming position and the aforementioned supply position; a second debris shielding member disposed in a second region between the aforementioned supply position and the aforementioned observation position; and a third debris shielding member disposed in a third region between the aforementioned plasma forming position and the aforementioned observation position.

[0018] In the aforementioned light source device, it may also include: a plurality of first debris shielding members disposed in a first region between the aforementioned plasma forming position and the aforementioned supply position; a plurality of second debris shielding members disposed in a second region between the aforementioned supply position and the aforementioned observation position; and a plurality of third debris shielding members disposed in a third region between the aforementioned plasma forming position and the aforementioned observation position.

[0019] In the aforementioned light source device, the aforementioned first debris shielding member may also include: an elongated portion, the distance between the elongated portion and the moving trajectory of the aforementioned retaining surface becomes smaller as the elongation moves toward the aforementioned moving direction.

[0020] In the aforementioned light source device, the angle between the portion of the moving direction side of at least any one of the aforementioned first debris shield, the aforementioned second debris shield, and the aforementioned third debris shield, including the end, and the tangent to the moving trajectory of the aforementioned holding surface on the extension line of the aforementioned end is less than 90°.

[0021] In the aforementioned light source device, the aforementioned portion including the end may also include: an elongated portion, the distance between the elongated portion and the moving trajectory of the aforementioned holding surface becomes smaller as the elongation moves toward the aforementioned moving direction; since the aforementioned holding surface side has a convex shape, as the elongation approaches the aforementioned end, the angle of the aforementioned portion including the end becomes smaller relative to the tangent of the moving trajectory of the aforementioned holding surface on the extension line of the aforementioned end.

[0022] In the aforementioned light source device, the aforementioned second debris shield may also include a portion disposed on a line extending from the rotation axis of the aforementioned target holding portion to the aforementioned processing surface.

[0023] In the aforementioned light source device, at least one of the aforementioned first debris shield, the aforementioned second debris shield and the aforementioned third debris shield may be installed on the debris cover covering the aforementioned target holding part.

[0024] In the aforementioned light source device, at least one of the aforementioned first debris shield, the aforementioned second debris shield, and the aforementioned third debris shield may be adjusted to be above the melting point of the aforementioned target material.

[0025] In the aforementioned light source device, the aforementioned plasma forming position may also be configured relative to the rotation axis of the aforementioned target holding part at a position opposite to the aforementioned observation position.

[0026] [Effect of the Invention] According to the present invention, a light source device that can improve the stability of extracted light can be provided.

Implementation Method

[0028] The specific configuration of this embodiment will be described below with reference to the drawings. The following description shows a preferred embodiment of the invention, and the scope of the invention is not limited to the following embodiments. In the following description, components with the same element symbols show substantially the same content.

[0029] <Embodiment 1> Description of the light source device in Embodiment 1. The light source device of this embodiment generates illumination light and exposure light for use in optical devices such as inspection devices and exposure devices. The light source device can be integrally installed with the optical device, or it can be arranged near the optical device as an independent device separate from the optical device. When the optical device is an inspection device, the light source device generates illumination light for illuminating the object being inspected in the inspection device. Furthermore, when the optical device is an exposure device, the light source device generates exposure light for exposing the object being exposed in the exposure device.

[0030] The light source device irradiates an excitation light onto a target material held by a target holding section, thereby generating illumination light and exposure light, etc. In the following embodiment one, as an example of a light source device, an example of using molten metal held by a target holding section containing a container such as a crucible as the target material is described. In embodiment two, a light source device using a solid held by a target holding section such as a cylindrical drum as the target material is described. Furthermore, the light source device is not limited to a light source device using molten metal held by a container such as a crucible as the target material, nor is it limited to a light source device using a solid such as a cylindrical drum as the target material. It can also be a light source device using solid metal such as a strip-shaped target holding section as the target material, or a light source device using liquid metal in the form of droplets as the target material.

[0031] FIG1 is a cross-sectional view illustrating the light source device 1 of Embodiment 1, and shows the cross-section along line II in FIG2. FIG2 is a cross-sectional view illustrating the light source device 1 of Embodiment 1, and shows the cross-section along line II-II in FIG1. ​​FIG3 is a schematic diagram illustrating the internal space 10a of the target holding part 10 in the light source device 1 of Embodiment 1. In FIG1 to avoid complicating the diagrams, some components are omitted. For example, in FIG1, the debris shielding members 61 to 63 in the cover part 60 are omitted.

[0032] As shown in Figures 1 to 3, the light source device 1 includes a target holding part 10 and a driving part 20. In addition to the target holding part 10 and the driving part 20, the light source device 1 may also include a forming part 30, a supply part 40, an observation part 50, a cover part 60, an output optical system 70 and a control part 80.

[0033] Here, for the convenience of explaining the light source device 1, an XYZ orthogonal coordinate system is introduced. For example, the rotation axis R of the target holding part 10 is taken as the Z-axis direction. In addition, the XYZ orthogonal coordinate system introduced is used for the convenience of explanation and is not used to limit the orientation of each component.

[0034] The target holding part 10 holds the target material 12. The target holding part 10 may also include a container such as a crucible. The target holding part 10 can melt metal inside. The target holding part 10 holds the target material 12, which is molten metal generated by plasma 11 by irradiation with excitation light LR. The excitation light LR is, for example, laser light including IR (Infrared ray) light.

[0035] Furthermore, as described later, the target holding portion 10 is not limited to containers such as crucibles. For example, the target holding portion 10 may also be a cylindrical barrel. In this case, the target holding portion 10 holds the target material 12 by fixing the xenon (Xe) or other substances that have been frozen to the surface of the barrel into a solid state, for example.

[0036] The target material 12 is not limited to molten metal held by the target holding part 10. It can be any substance that generates plasma 11 by irradiation with excitation light LR, such as a solid substance, solid metal, or droplet. The molten metal is, for example, molten metal such as tin (Sn) or lithium (Li). However, it is not limited to tin and lithium as long as it is a metal that generates plasma 11 by irradiation with excitation light LR.

[0037] The target holding part 10 has a rotation axis R, and rotates around the rotation axis R. The rotation axis R can also be approximately orthogonal to the ground plane. In this way, since a uniform centrifugal force is applied to the target material 12 held by the target holding part 10, the thickness of the target material 12 can be made uniform, thereby stabilizing the light L0 extracted from the light source device 1.

[0038] The target holding portion 10 is, for example, a cylindrical shape with one side opening closed. The closed portion of the target holding portion 10 is referred to as the bottom 13. The cylindrical portion of the target holding portion 10 is referred to as the cylindrical portion 14. The inner surface of the bottom 13 is referred to as the bottom surface 15. The inner surface of the cylindrical portion 14 is referred to as the inner wall surface 16. The target holding portion 10 has a holding surface 17 for holding the target material 12. For example, the target holding portion 10 has the inner wall surface 16 as the holding surface 17. In this case, the target holding portion 10 holds the target material 12 on the inner wall surface 16 by centrifugal force. Furthermore, as long as the target holding portion 10 can hold the target material 12 containing molten metal, the surface other than the inner wall surface 16, such as the bottom surface 15, can also be used as the holding surface 17. Moreover, the target holding portion 10 can also have shapes other than those described above, as long as it can hold the target material 12.

[0039] The inner wall surface 16 formed in a manner surrounding the rotation axis R may also have a groove 18 formed along its inner periphery. The groove 18 is formed, for example, along the intersection of the inner wall surface 16 and a plane orthogonal to the rotation axis R. The groove 18 is recessed in the inner wall surface 16 in a direction away from the rotation axis R. In the case where the inner wall surface 16 has a groove 18, the target material 12 can also be held in the groove 18. By holding the target material 12 in the groove 18, the movement of the target material 12 in the Z-axis direction can be restricted, thereby suppressing disturbances on the liquid surface of the target material 12. Furthermore, since the amount of the target material 12 can be confined within the groove 18, the necessary amount of the target material 12 can be reduced. In addition, a portion of the target material 12 may also be located outside the groove 18.

[0040] Furthermore, the inner wall surface 16 formed in a manner surrounding the rotation axis R may include a cylindrical portion at a fixed distance from the rotation axis R. Moreover, the inner wall surface 16 may also include an inclined surface at a varying distance from the rotation axis R. For example, the inner wall surface 16 may also have a rounded corner at its connection with the bottom surface 15. As long as the target material 12 can be maintained, the shape of the inner wall surface 16 is not limited to a shape having a groove 18, a cylindrical surface, an inclined surface, or a rounded corner.

[0041] A heater 19 is provided in the target holding part 10. By heating with the heater 19, a target material 12 such as molten metal can be formed in the target holding part 10.

[0042] The drive unit 20 is connected to the target holder 10 via a power transmission mechanism such as a shaft. The drive unit 20 drives the target holder 10 by transmitting power to it. The drive unit 20 drives the target holder 10, thereby moving the holding surface 17. For example, the drive unit 20 can also rotate the target holder 10 about the rotation axis R to move the target material 12. When viewed from the +Z axis direction to the -Z axis direction, the drive unit 20 rotates the target holder 10 about the rotation axis R in the direction in which the clock hands rotate. In addition, the drive unit 20 can also rotate the target holder 10 about the rotation axis R in the opposite direction to the direction in which the clock hands rotate.

[0043] Here, the predetermined direction in which the drive unit 20 rotates the target holding unit 10 about the rotation axis R is called the moving direction. For example, the direction in which the hands of a clock rotate about the rotation axis R is called the moving direction. Along with the rotation of the moving direction of the target holding unit 10, the holding surface 17 of the target holding unit 10 also rotates about the rotation axis R in the moving direction. Thereby, the target material 12 also rotates about the rotation axis R in the moving direction. Thus, the target holding unit 10 has a holding surface 17 that carries the target material 12 generated by the plasma 11 to the plasma forming position 130.

[0044] As shown in FIG. 3, the target holding portion 10 has an internal space 10a surrounded by an inner wall surface 16. The internal space 10a includes a plasma forming space 130a, a supply space 140a, and an observation space 150a. A forming portion 30 containing an excitation light LR is disposed in the plasma forming space 130a. A supply portion 40 is disposed in the supply space 140a, which supplies the target material 12 to the holding surface 17. An observation portion 50 is disposed in the observation space 150a, which acquires state information of the holding surface 17.

[0045] The space in which the target holding part 10 is disposed is referred to as the moving space 110. The moving space 110 is a space in which the target holding part 10 moves. The moving space 110 has a processing surface 117 along the holding surface 17. The processing surface 117 may also overlap with the holding surface 17. The holding surface 17 moves relative to the processing surface 117.

[0046] The processing surface 117 may also include a plasma forming position 130, a supply position 140, and an observation position 150. The plasma forming position 130 faces the forming section 30. The plasma forming position 130 includes the area where the plasma 11 is formed by the forming section 30. The supply position 140 faces the supply section 40. The supply position 140 includes the area where the target material 12 is supplied to the holding surface 17 by the supply section 40. The observation position 150 faces the observation section 50. The observation position 150 includes the area where the state information of the holding surface 17 is obtained by the observation section 50.

[0047] The processing surface 117 may also include a plurality of plasma forming positions 130, a plurality of supply positions 140 and a plurality of observation positions 150. Therefore, the processing surface 117 includes at least one plasma forming position 130, at least one supply position 140 and at least one observation position 150.

[0048] The plasma forming position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. For example, the plasma forming position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117 in a rotational direction about the rotation axis R. When viewed from the perspective of the movement of the holding surface 17 caused by the drive unit 20, the processing surface 117 includes the supply position 140, which is arranged further rearward than the plasma forming position 130. Furthermore, the processing surface 117 includes the observation position 150, which is arranged further rearward than the supply position 140. Therefore, when viewed from the perspective of the movement of the holding surface 17 caused by the drive unit 20, the holding surface 17 includes the supply position 140, which is arranged between the plasma forming position 130 and the observation position 150. In the direction of movement of the holding surface 17 driven by the drive unit 20, the processing surface 117 includes: a supply position 140, which is located further rearward than the plasma forming position 130; and an observation position 150, which is located further rearward than the supply position 140.

[0049] For example, in the XY plane viewed from the +Z-axis direction towards the -Z-axis direction, with the rotation axis R as the origin, the position of the processing surface 117 at this time is defined by the angle it forms with the +Y-axis. Accordingly, the plasma forming position 130 is located in, for example, a region containing 0°. The supply position 140 is located in, for example, a region containing 90°. The observation position 150 is located in a region containing 180°. Therefore, the processing surface 117 includes the supply position 140, which is positioned at a position +90° upward in the movement direction from the plasma forming position 130. The processing surface 117 also includes the observation position 150, which is positioned at a position +90° upward in the movement direction from the supply position 140.

[0050] Thus, if the direction of movement of the holding surface 17 caused by the drive unit 20 is defined as the direction (0° to 360°) of the angle increasing with respect to a predetermined radius (e.g., +Y axis) with the rotation axis R as the origin, the processing surface 117 includes a supply position 140, which is located at a position that increases in angle from the plasma forming position 130 (in the direction of movement). The processing surface 117 also includes an observation position 150, which is located at a position that increases in angle from the supply position 140 (in the direction of movement).

[0051] By including a supply position 140 disposed further rearward than the plasma formation position 130 in the processing surface 117, the state of the target material 12 supplied in the supply position 140 can be more stable before plasma is formed in the plasma formation position 130. Furthermore, by including an observation position 150 disposed further rearward than the supply position 140 in the processing surface 117, state information of the holding surface 17 of the target material 12 supplied in the supply position 140 can be obtained.

[0052] From the viewpoint of the internal space 10a, the plasma forming space 130a, the supply space 140a, and the observation space 150a are arranged along the processing surface 117. When the holding surface 17 is moved by the drive unit 20 to the viewing position, the internal space 10a includes the supply space 140a, which is arranged further rearward than the plasma forming space 130a. Furthermore, the internal space 10a includes the observation space 150a, which is arranged further rearward than the supply space 140a.

[0053] Furthermore, when viewed in the direction of movement of the holding surface 17 caused by the drive unit 20, the length of the processing surface 117 from the plasma forming position 130 to the supply position 140 is shorter than the length of the processing surface 117 from the supply position 140 to the plasma forming position 130. In other words, the length measured from the plasma forming position 130 along the processing surface 117 in the direction of clock hand rotation to the supply position 140 is shorter than the length measured from the supply position 140 along the processing surface 117 in the direction of clock hand rotation to the plasma forming position. In the direction of movement of the holding surface 17 driven by the drive unit 20, the length along the processing surface 117 from the plasma forming position 130 to the supply position 140 is shorter than the length along the processing surface 117 from the supply position 140 to the plasma forming position 130. By designing it in this way, the state of the target 12 supplied at the supply position 140 can be more stable before plasma is formed at the plasma forming position 130.

[0054] Furthermore, when the holding surface 17 moves towards the viewing position due to the drive unit 20, the length of the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length of the processing surface 117 from the observation position 150 to the plasma forming position 130. In the direction of movement of the holding surface 17 driven by the drive unit 20, the length of the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length of the processing surface 117 from the observation position 150 to the plasma forming position 130. With this configuration, the observation position 150 can be moved away from the plasma forming position 130, and the state of the holding surface 17 after the target 12 is supplied can be observed. Therefore, the influence of debris generated at the plasma forming position 130 on the observation position 50 can be reduced, and information on the state of the holding surface 17, such as the thickness of the target 12 toward the plasma forming position 130, can be accurately obtained.

[0055] Furthermore, the plasma forming position 130 is preferably positioned opposite the observation position 150 relative to the rotation axis R of the target holding part 10. This can further reduce the impact of debris generated at the plasma forming position 130 on the observation part 50.

[0056] From the viewpoint of the internal space 10a, when viewed in the direction of the movement of the holding surface 17 caused by the drive unit 20, the length of the processing surface 117 from the plasma forming space 130a to the supply space 140a is shorter than the length of the processing surface 117 from the supply space 140a to the plasma forming space 130a. Furthermore, when viewed in the direction of the movement of the holding surface 17 caused by the drive unit 20, the length of the processing surface 117 from the supply space 140a to the observation space 150a is shorter than the length of the processing surface 117 from the observation space 150a to the plasma forming space 130a. Further, the plasma forming space 130a is preferably positioned opposite the observation space 150a relative to the rotation axis R of the target holding unit 10.

[0057] The forming section 30 includes an excitation light LR disposed in the plasma forming space 130a. The forming section 30 excites the target 12 by focusing the laser light LR onto the target 12 in the plasma forming position 130. Thereby, the forming section 30 generates plasma 11 from the target 12 in the plasma forming position 130. When the plasma 11 is generated, EUV (extreme ultraviolet) light LE is produced from the plasma 11. For example, EUV light LE is used as illumination light LO in optical devices such as inspection apparatus or exposure apparatus.

[0058] The forming part 30 may also include an optical component 31. The optical component 31 irradiates the target 12 with excitation light LR. The optical component 31 includes at least one of, for example, a mirror and a condenser lens. In addition, the optical component 31 is not limited to a mirror and a condenser lens, as long as it is a component that irradiates the target 12 with excitation light LR, it may also be a laser device that generates excitation light LR.

[0059] The light source device 1 may also include a laser device for generating excitation light LR. Alternatively, the light source device 1 may also receive excitation light LR from a laser device, which is separately disposed outside the light source device 1. The laser device, for example, emits excitation light LR containing IR light. The excitation light LR can also irradiate the target material 12 by controlling the oscillation and stopping of oscillation by the control unit 80. For example, the excitation light LR is focused by the optical component 31. Thus, the excitation light LR irradiates the target material 12.

[0060] The optical component 31 causes the excitation light LR to irradiate the target 12 at an inclined incident angle relative to the target holder 10 from an axis perpendicular to the surface of the target 12 toward the near front side. Hereby, since the angular velocity of the rotation direction of the target holder 10 is applied to the direction of debris scattering, the debris can be scattered more toward the reflection direction of the excitation light LR, thereby suppressing the amount of debris scattered toward the laser device side.

[0061] The supply unit 40 is disposed in the supply space 140a. The supply unit 40 supplies the target material 12 to the holding surface 17 in the supply position 140. The supply unit 40 may also supply a solid target material 12 to the holding surface 17. The solid target material 12 may also be in the form of a wire. The wire-shaped target material 12 may also be wound around a bobbin or the like and held. The supply unit 40 supplies the wire-shaped target material 12 from the bobbin into the target holding part 10.

[0062] Furthermore, the supply unit 40 can also supply the molten target material 12 to the holding surface 17. For example, the supply unit 40 can also use a debris shield 62 to supply the molten target material 12 to the holding surface 17. The debris shield 62 is disposed near the supply position 140. The debris shield 62 is disposed, for example, opposite to the supply position 140. The debris shield 62 is exposed to a temperature above the melting point of the target material 12. Accordingly, the debris shield 62 can also be heated to a temperature above the melting point of the target material 12 by the radiant heat of the target holding part 10 and the target material 12 within the target holding part 10. Furthermore, the debris shield 62 can also be adjusted to a temperature above the melting point of the target material 12 by a heating member such as a heater.

[0063] Furthermore, the debris shield 61, which is arranged opposite to the plasma formation position 130, and the debris shield 63, which is arranged opposite to the observation position 150, can also be adjusted to a temperature above the melting point of the target material 12. That is, at least one of the debris shields 61 to 63 can be adjusted to a temperature above the melting point of the target material 12. In this way, plasma can be generated again using the target material 12 which has become debris.

[0064] The supply section 40 can also melt the solid target material 12b by contacting it with the debris shield 62, and supply it into the target holding section 10. For example, after the molten target material 12b falls to the bottom surface 15 through the debris shield 62, it reaches the inner wall surface 16 by centrifugal force. In this way, since the target material 12 on the holding surface 17 can be prevented from contacting the solid target material 12b, the temperature drop of the target material 12 on the holding surface 17 can be suppressed. Furthermore, disturbances to the surface state of the target material 12 caused by vibration, etc., can also be suppressed.

[0065] The observation unit 50 is disposed in the observation space 150a. The observation unit 50 acquires state information of the holding surface 17 at the observation position 150. The state information of the holding surface 17 may also be the surface unevenness, surface roughness, height, reflectivity, etc. of the target material 12 held on the holding surface 17. Alternatively, the state information of the holding surface 17 may also be whether there are scratches, whether there are attachments, the size of the scratches, the size of the attachments, etc. For example, the observation unit 50 acquires the position of the target material 12 held on the holding surface 17 relative to the holding surface 17. In this case, the observation unit 50 includes a position sensor. In addition to the position sensor, the observation unit 50 may also include various sensors such as a temperature sensor and a stress sensor. By means of the position sensor, the observation unit 50 measures and acquires the surface position of the target material 12. For example, a position sensor may include a displacement meter, a high-speed camera, a low-speed camera, a quadrant photodiode, or a TDI (Time Delay Integration) camera. Furthermore, a position sensor may be any one of a one-dimensional, two-dimensional, or three-dimensional position sensor measuring surface position, or a combination of several of these position sensors.

[0066] The observation unit 50, which includes a position sensor, obtains the displacement of the surface position of the target 12 based on the obtained surface position of the target 12. The observation unit 50 may also obtain the surface position of the target 12 based on the thickness from the holding surface 17.

[0067] The observation unit 50 is preferably located away from the plasma formation position 130. For example, the observation unit 50 is located opposite the plasma formation position 130 relative to the rotation axis R. This can suppress the influence of debris and improve the accuracy of surface position measurement.

[0068] The cover 60 includes debris shielding members 61 to 63 and a debris cover 65. However, the cover 60 may not necessarily include all of the debris shielding members 61 to 63 and the debris cover 65. The cover 60 may also include at least any one of the debris shielding members 61 to 63 and the debris cover 65.

[0069] The debris cover 65 is configured to cover the target holding portion 10. For example, the debris cover 65 covers the opening on the +Z axis direction side of the target holding portion 10. Furthermore, the debris cover 65 forms an opening for extracting excitation light (LR) and EUV light (LE). The debris cover 65 suppresses debris that flies away with the generation of plasma 11 from adhering to the collector mirror, etc. Furthermore, as mentioned above, the debris cover 65 can also be adjusted to be above the melting point of the target material 12.

[0070] The debris shield 61 is disposed in the plasma forming space 130a. The debris shield 61 is configured to cover the plasma forming position 130. The debris shield 61 may also include a portion disposed opposite to the region 135 between the plasma forming position 130 and the supply position 140 in the processing surface 117, and the debris shield 61 may also include a portion disposed opposite to the region 155 between the plasma forming position 130 and the observation position 150 in the processing surface 117. Specifically, the debris shield 61 includes a portion disposed between the forming section 30 and the supply section 40 and a portion disposed between the forming section 30 and the observation section 50. Accordingly, the cover 60 further includes: a first debris shield (a part of the debris shield 61), which is disposed opposite to the region 135 between the plasma forming position 130 and the supply position 140. The cover 60 further includes a first debris shield (part of debris shield 61) disposed in region 135 between plasma forming position 130 and supply position 140.

[0071] The debris shield 61 includes an elongated portion 61a, the distance between which, when viewed from the +Z-axis direction towards the -Z-axis direction, decreases towards the moving direction. The debris shield 61 has an elongated portion 61a, the distance between which it and the moving trajectory of the holding surface 17 decreases along the moving direction. For example, the portion of the debris shield 61 on the +X-axis direction side includes an elongated portion 61a with a decreasing distance from the processing surface 117. The angle between the elongated portion 61a including the end 61b on the moving direction side of the debris shield 61 and the tangent to the processing surface 117 on the extension line of the end 61b is less than 90°. In the moving trajectory of the holding surface 17, the tangent on the extension line of the end 61b is less than 90°. Viewed from the +Z-axis direction towards the -Z-axis direction, due to the convex shape of the processing surface 117, the angle between the elongated portion 61a including the end 61b and the tangent of the processing surface 117 on the extension line of the end 61b decreases as it approaches the end 61b. The portion of the debris shield 61 including the end on the +X-axis direction has: an elongated portion 61a, the distance between it and the moving trajectory of the holding surface 17 decreases along the moving direction; and, it becomes convex near the holding surface 17, and the angle between the portion of the debris shield 61 including the end on the +X-axis direction and the tangent of the moving trajectory of the holding surface 17 on the extension line of the end decreases as it approaches the end.

[0072] The debris shield 62 is disposed in the supply space 140a. The debris shield 62 is configured to cover the supply position 140. Furthermore, the debris shield 62 is configured to cover the supply section 40 from both sides. The debris shield 62 may also include a portion disposed opposite to the region 145 between the supply position 140 and the observation position 150 in the processing surface 117, and may also include a portion disposed opposite to the region 135 between the supply position 140 and the plasma forming position 130 in the processing surface 117. Specifically, the debris shield 62 includes a portion disposed between the supply section 40 and the observation section 50 and a portion disposed between the supply section 40 and the forming section 30. Accordingly, the cover 60 further includes: a second debris shield (a part of the debris shield 62), which is disposed opposite to the region 145 between the supply position 140 and the observation position 150. The cover 60 further includes a second debris shield (part of the debris shield 62) disposed in the region 145 between the supply position 140 and the observation position 150.

[0073] The debris shield 62 may also include a portion disposed on a line extending from the rotation axis R of the target holder 10 to the processing surface 117. In other words, the debris shield 62 also includes a radial portion. In this way, the debris shield 62 can supply the target material 12 after the debris has been melted to the holding surface 17 without interruption by centrifugal force.

[0074] The portion of the debris shield 62 that includes the end 62b in the moving-oriented side can also be bent. Furthermore, the angle between the bent portion of the debris shield 62 that includes the end 62b in the moving-oriented side and the tangent of the processing surface 117 on the extension line of the end 62b may not reach 90°.

[0075] The debris shield 63 is disposed in the observation space 150a. The debris shield 63 is configured to cover the observation position 150. The debris shield 63 is configured to cover the observation section 50 from both sides. The debris shield 63 may also include a portion disposed opposite to the region 155 between the observation position 150 and the plasma forming position 130 in the processing surface 117, and may also include a portion disposed opposite to the region 145 between the observation position 150 and the supply position 140 in the processing surface 117. Specifically, the debris shield 63 includes a portion disposed between the observation section 50 and the forming section 30 and a portion disposed between the observation section 50 and the supply section 40. Accordingly, the cover 60 further includes: a third debris shield (a part of the debris shield 63), which is disposed opposite to the region 155 between the plasma forming position 130 and the observation position 150. The cover 60 further includes a third debris shield (part of debris shield 63) disposed in region 155 between plasma formation position 130 and observation position 150.

[0076] The portion of the debris shield 63 that includes the end 63b on the moving side can also be bent. Furthermore, the angle between the bent portion of the debris shield 63 that includes the end 63b on the moving side and the tangent of the processing surface 117 on the extension line of the end 63b may not reach 90°.

[0077] The cover 60 includes: a first debris shielding member disposed opposite to a region 135 between the plasma forming position 130 and the supply position 140 in the processing surface 117; a second debris shielding member disposed opposite to a region 145 between the supply position 140 and the observation position 150 in the processing surface 117; and a third debris shielding member disposed opposite to a region 155 between the plasma forming position 130 and the observation position 150 in the processing surface 117. Here, the first debris shielding member includes a portion of debris shielding member 61 or a portion of debris shielding member 62. The second debris shielding member includes a portion of debris shielding member 62 or a portion of debris shielding member 63. The third debris shielding member includes a portion of debris shielding member 63 or a portion of debris shielding member 61.

[0078] At least one of the first debris shield, the second debris shield and the third debris shield may also be installed on the debris cover 65.

[0079] The cover 60 includes: a plurality of first debris shielding members disposed in a region 135 between the plasma forming position 130 and the supply position 140 in the processing surface 117; a plurality of second debris shielding members disposed in a region 145 between the supply position 140 and the observation position 150 in the processing surface 117; and a plurality of third debris shielding members disposed in a region 155 between the plasma forming position 130 and the observation position 150 in the processing surface 117. Here, the plurality of first debris shielding members includes a portion of debris shielding member 61 and a portion of debris shielding member 62. The plurality of second debris shielding members includes a portion of debris shielding member 62 and a portion of debris shielding member 63. The plurality of third debris shielding members includes a portion of debris shielding member 63 and a portion of debris shielding member 61.

[0080] The output optical system 70 extracts light L0 generated by irradiating the target 12 with excitation light LR from the light source device 1. The output optical system 70 includes, for example, an optical component 71. The optical component 71 includes, for example, a focusing lens. Furthermore, the optical component 71 is not limited to a focusing lens, as long as it is an optical component that extracts light L0 generated by irradiating the target 12 with excitation light LR, it may also be a second focusing lens (not shown) that further reflects the light L0 reflected by the focusing lens.

[0081] Optical component 71 reflects light L0 generated from the target 12 by irradiation with excitation light LR. Optical component 71, for example, reflects EUV light LE generated by irradiation with excitation light LR. That is, light L0 may also include EUV light LE. EUV light LE is generated from plasma 11 produced by irradiating the target 12 with excitation light LR. The EUV light LE generated by the plasma 11 generated by the target 12 is emitted as illumination light to optical devices such as inspection apparatus. Therefore, the illumination system includes EUV light LE generated from plasma 11.

[0082] The control unit 80 can also control the components in the light source device 1. The control unit 80 is connected to the components in the light source device 1 in a manner that allows information transmission via wireless or wired communication lines. For example, the control unit 80 analyzes the status information of the target material 12 obtained by the observation unit 50. Furthermore, the control unit 80 analyzes output information, which includes the intensity and irradiation position of the illumination light L0 output by the output optical system 70.

[0083] The control unit 80 controls the formation state of the plasma in the forming unit 30, including the intensity and irradiation position of the excitation light LR, based on the status information of the target material 12 and the output information of the illumination light L0. Furthermore, the control unit 80 controls the supply state of the supply unit 40, including the temperature and supply amount of the target material 12, based on the status information and output information. Furthermore, the control unit 80 controls the temperature of the cover unit 60, etc., based on the status information and output information.

[0084] Next, the effects of this embodiment will be explained. In the light source device 1 of this embodiment, the plasma forming position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. In the case of viewing along the moving direction, the processing surface 117 includes: the supply position 140, which is arranged further rearward than the plasma forming position 130; and the observation position 150, which is arranged further rearward than the supply position 140. Therefore, the state of the target material 12 supplied at the supply position 140 can be more stable before plasma is formed in the plasma forming position 130. Furthermore, the state information of the holding surface 17, which includes the target material 12 supplied at the supply position 140, can be obtained. Furthermore, the influence of the surface state caused by the supply of the target material 12 when plasma 11 is generated in the plasma forming position 130 can be reduced. Furthermore, the state information such as the thickness of the target material 12 in the plasma forming position 130 can be accurately obtained.

[0085] Furthermore, in the light source device 1, the length of the processing surface 117 from the plasma forming position 130 to the supply position 140 is shorter than the length of the processing surface 117 from the supply position 140 to the plasma forming position 130. Therefore, after the state of the target material 12 supplied at the supply position 140 is more stable, plasma is formed in the plasma forming position 130. Furthermore, in this configuration, the influence of the surface state caused by the supply of the target material 12 can also be reduced.

[0086] Furthermore, in the light source device 1, the length of the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length of the processing surface 117 from the observation position 150 to the plasma formation position 130. Therefore, the impact of debris generated at the plasma formation position 130 on the observation section 50 can be reduced.

[0087] <Embodiment 2> Next, the light source device 2 of Embodiment 2 will be described. Figure 4 is a cross-sectional view illustrating the light source device 2 of Embodiment 2, and shows the cross-section along line IV-IV in Figure 5. Figure 5 is a cross-sectional view illustrating the light source device 2 of Embodiment 2, and shows the cross-section along line VV in Figure 4. As shown in Figures 4 and 5, the light source device 2 includes a target holding section 210 and a driving section 220. In addition to the target holding section 210 and the driving section 220, the light source device 2 may further include a forming section 230, a supply section 240, an observation section 250, a cover section 260, an output optical system 270, and a control section 280.

[0088] The target holding part 210 holds the target material 212. The target holding part 210 includes a cylindrical barrel 213. The interior of the barrel 213 is filled with a coolant 214 such as liquid nitrogen. The target holding part 210 fixes the solid material such as xenon (Xe) frozen to the outer peripheral surface 215 of the barrel 213, thereby holding the target material 212. In this embodiment, the holding surface 217 of the target holding part 210 includes the outer peripheral surface 215 of the barrel 213.

[0089] The drive unit 220 drives the target holding unit 210 to move the holding surface 217. The target holding unit 210 has a rotation axis R. When the target holding unit 210 is viewed from the +Z axis direction to the -Z axis direction, the drive unit 220 rotates the target holding unit 210 about the rotation axis R in the direction in which the hands of a clock rotate.

[0090] The forming portion 230 is disposed on the +Y axis direction side of the target holding portion 210. The forming portion 230 is formed by irradiating the target material 212 held on the holding surface 217 on the +Y axis direction side of the target holding portion 210 with an excitation light LR advancing along the -Y axis direction. Therefore, the plasma forming position 130 includes the portion on the +Y axis direction side of the holding surface 217.

[0091] The supply unit 240 is disposed on the +X-axis side of the target holding unit 210. The supply unit 240 has a supply port 241. The supply port 241 faces the +X-axis side of the target holding unit 210. Therefore, the supply position 140 includes the portion on the +X-axis side of the holding surface 217. The supply port 241 is connected to a supply source 243 for the gas 242 of the target material 212. The supply source 243 supplies the gas 242 of the target material 212 to the supply position 140 through the supply port 241. The gas 242 of the target material 212 supplied by the supply port 241 is solidified on the surface of the barrel 213, thereby forming the target material 212.

[0092] The observation section 250 is disposed on the Y-axis side of the target holding section 210. Therefore, the observation position 150 includes the Y-axis side of the holding surface 217.

[0093] In this embodiment, the target holding part 210 is disposed in the moving space 110. The target holding part 210 moves within the moving space 110. The moving space 110 has a processing surface 117 along the holding surface 217. The processing surface 117 may also overlap with the holding surface 217. The holding surface 217 moves relative to the processing surface 117.

[0094] The plasma forming position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. When the holding surface 217 is moved by the drive unit 220 to the viewing position, the processing surface 117 includes the supply position 140, which is located further rearward than the plasma forming position 130. Furthermore, the processing surface 117 includes the observation position 150, which is located further rearward than the supply position 140.

[0095] Furthermore, when the holding surface 217 moves towards the viewing position due to the drive unit 220, the length of the processing surface 117 from the plasma forming position to the supply position 140 is shorter than the length of the processing surface 117 from the supply position 140 to the plasma forming position 130. Further, the length of the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length of the processing surface 117 from the observation position 150 to the plasma forming position 130.

[0096] The cover 260 includes debris shielding members 261 to 263. Debris shielding member 261 is disposed opposite to each other in the region 135 between the plasma forming position 130 and the supply position 140. Debris shielding member 262 is disposed opposite to each other in the region 145 between the supply position 140 and the observation position 150. Debris shielding member 263 is disposed opposite to each other in the region 155 between the plasma forming position 130 and the observation position 150.

[0097] As in this embodiment, even when a solid or the like held in the target holding portion 210 of a cylindrical barrel or the like is used as the target material 212, the same effect as in Embodiment 1 can be obtained. That is, the state of the target material 212 supplied from the supply position 140 can be stabilized before plasma is formed in the plasma forming position 130. Furthermore, state information of the holding surface 217, which is included in the target material 212 supplied from the supply position 140, can be obtained.

[0098] <Modified Example> Figure 6 is a cross-sectional view illustrating the light source device 2a of Embodiment 2. As shown in Figure 6, in this modified example, the position of the forming portion 230 is different from that of the light source device 2 in Embodiment 2. That is, the forming portion 230 is disposed on the -X-axis direction side of the target holding portion 210. The forming portion 230 is formed by irradiating the target material 212 held on the holding surface 217 on the -X-axis direction side of the target holding portion 210 with an excitation light LR advancing in the +X-axis direction. Therefore, the plasma forming position 130 includes the portion on the -X-axis direction side of the processing surface 117.

[0099] Even with this configuration, the plasma forming position 130, the supply position 140, and the observation position 150 are still arranged along the processing surface 117. When the holding surface 217 is moved by the drive unit 220 towards the viewer, the processing surface 117 includes: the supply position 140, which is located further rearward than the plasma forming position 130. Furthermore, the processing surface 117 includes: the observation position 150, which is located further rearward than the supply position 140. Other configurations and functions are described in Embodiment 1 and Embodiment 2.

[0100] While embodiments of the present invention have been described above, the present invention includes appropriate modifications that do not impair its objectives and advantages, and is not limited to the above embodiments. Furthermore, the various configurations of Embodiment 1, Embodiment 2, and the variations can be appropriately combined. [Simplified Explanation of the Diagram]

[0027] [Fig. 1] is a cross-sectional view illustrating the light source device of Embodiment 1, and shows the cross-section along line II in Fig. 2. [Fig. 2] is a cross-sectional view illustrating the light source device of Embodiment 1, and shows the cross-section along line II-II in Fig. 1. [Fig. 3] is a schematic diagram illustrating the internal space of the target holding part in the light source device 1 of Embodiment 1. [Fig. 4] is a cross-sectional view illustrating the light source device of Embodiment 2, and shows the cross-section along line IV-IV in Fig. 5. [Fig. 5] is a cross-sectional view illustrating the light source device of Embodiment 2, and shows the cross-section along line VV in Fig. 4. [Fig. 6] is a cross-sectional view illustrating a modified example of the light source device of Embodiment 2.

Claims

1. A light source apparatus comprising: a target holding portion having a holding surface for conveying a plasma-generated target material to a plasma forming position; and a driving portion for driving the target holding portion to move the holding surface; the holding surface moving relative to a processing surface in space along the holding surface; the processing surface including: at least one plasma forming position; at least one supply position for supplying the target material to the holding surface; and at least one observation position for acquiring state information of the holding surface; the plasma forming position, the supply position, and the observation position being disposed along the processing surface; in the direction of movement of the holding surface driven by the driving portion, the processing surface including: the supply position disposed further rearward than the plasma forming position; and the observation position disposed further rearward than the supply position.

2. A light source apparatus comprising: a target holding portion having a holding surface for conveying a plasma-generated target material to a plasma forming position; and a driving portion for driving the target holding portion to move the holding surface; the holding surface moving relative to a processing surface in space along the holding surface; the processing surface including: at least one plasma forming position; and at least one supply position for supplying the target material to the holding surface; the plasma forming position and the supply position being disposed along the processing surface; in the direction of movement of the holding surface driven by the driving portion, the length of the processing surface from the plasma forming position to the supply position is shorter than the length of the processing surface from the supply position to the plasma forming position.

3. The light source apparatus as described in claim 1 or 2, further comprising: a forming section that focuses laser light onto the target material at the plasma forming position, thereby exciting the target material at the plasma forming position.

4. The light source device as described in claim 1 or 2, wherein the aforementioned target holding part has a rotation axis; the aforementioned drive part moves the aforementioned target material by rotating the aforementioned target holding part about the aforementioned rotation axis.

5. The light source device as described in claim 4, wherein the aforementioned rotation axis is substantially orthogonal to the ground plane.

6. The light source device as described in claim 2, wherein the aforementioned processing surface further comprises: at least one observation position for obtaining state information of the aforementioned holding surface; the aforementioned plasma forming position, the aforementioned supply position and the aforementioned observation position are arranged along the aforementioned processing surface.

7. The light source device as described in claim 1 or 6, wherein in the direction of movement of the aforementioned holding surface driven by the aforementioned driving unit, the length of the aforementioned processing surface from the aforementioned supply position to the aforementioned observation position is shorter than the length of the aforementioned processing surface from the aforementioned observation position to the aforementioned plasma formation position.

8. The light source device as described in claim 1 or 2, further comprising: a first debris shielding member disposed in the region between the aforementioned plasma forming position and the aforementioned supply position.

9. The light source device as described in claim 1 or 6, further comprising: a second debris shield disposed in the region between the aforementioned supply position and the aforementioned observation position.

10. The light source device as described in claim 1 or 6, further comprising: a third debris shield disposed in the region between the aforementioned plasma formation position and the aforementioned observation position.

11. The light source apparatus as described in claim 1 or 6, further comprising: a first debris shield disposed in a first region between the plasma forming position and the supply position; a second debris shield disposed in a second region between the supply position and the observation position; and a third debris shield disposed in a third region between the plasma forming position and the observation position.

12. The light source apparatus as described in claim 1 or 6, further comprising: a plurality of first debris shielding members disposed in a first region between the plasma forming position and the supply position; a plurality of second debris shielding members disposed in a second region between the supply position and the observation position; and a plurality of third debris shielding members disposed in a third region between the plasma forming position and the observation position.

13. The light source device as described in claim 8, wherein the aforementioned first debris shielding member includes: an elongated portion, the distance between the elongated portion and the moving trajectory of the aforementioned retaining surface becoming smaller as the moving direction moves.

14. The light source device as described in claim 11, wherein the angle between the portion of the moving direction side of at least any one of the aforementioned first debris shield, the aforementioned second debris shield, and the aforementioned third debris shield, including the end portion, and the tangent to the moving trajectory of the aforementioned holding surface on the extension line of the aforementioned end portion is less than 90°.

15. The light source device as described in claim 14, wherein the portion including the end portion includes: an elongated portion, the distance between the portion including the end portion and the movement trajectory of the holding surface becomes smaller as the movement direction approaches the end portion; and the portion including the end portion has a smaller angle as it approaches the end portion, relative to the tangent of the movement trajectory of the holding surface on the extension line of the end portion, due to the convex shape of the holding surface side.

16. The light source device as described in claim 9, wherein the aforementioned second debris shielding member comprises: a portion disposed on a line extending from the rotation axis of the aforementioned target holding portion to the aforementioned processing surface.

17. The light source device as described in claim 11, wherein at least one of the aforementioned first debris shield, the aforementioned second debris shield and the aforementioned third debris shield is mounted on a debris cover covering the aforementioned target holding portion.

18. The light source device as described in claim 12, wherein at least one of the aforementioned first debris shield, the aforementioned second debris shield and the aforementioned third debris shield is adjusted to be above the melting point of the aforementioned target material.

19. The light source device as described in claim 1 or 6, wherein the plasma forming position is arranged relative to the rotation axis of the target holding part at a position opposite to the observation position.

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