Light source device

Abstract

To provide a light source device capable of improving stability of light to be taken out.SOLUTION: A light source device 1 according to the present disclosure includes a target holding unit 10 having a holding surface 17 that transports a target material 12 for generating plasma 11 to a plasma formation position 130, and a driving unit 20 that drives the target holding unit 10 to move the holding surface 17. The holding surface 17 moves relative to a processing surface 117 in a space along the holding surface 17. The processing surface 117 has at least one plasma formation position 130, at least one supply position 140 at which the target material 12 is supplied to the holding surface 17, and at least one observation position 150 at which state information of the target material 12 held on the holding surface 17 is acquired. The plasma formation position 130, the supply position 140, and the observation position 150 are disposed along the processing surface 117, and the processing surface 117 includes the supply position 140 disposed after the plasma formation position 130.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a light source device.

Background Art

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

[0003] Patent Document 2 describes a light source device that holds a target material of molten metal on the inner wall of a crucible that rotates around a rotation axis by centrifugal force and extracts illumination light by irradiating the held target material with excitation light.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In a light source device, due to vibrations generated during rotation of a target holding part such as a cylindrical member and a crucible, deformation of the structure itself, rotational stress and thermal deformation of the target holding part itself, and input of the target material into the target holding part, etc., the relative position between the light emitting point located near the surface of the target material and the optical member may vary. As a result, it is conceivable that light cannot be stably extracted from the light source device.

[0006] An object of the present disclosure is to solve such problems and provide a light source device capable of improving the stability of the light to be extracted.

Means for Solving the Problems

[0007] The light source device according to this disclosure comprises a target holding unit having a holding surface for transporting a target material that generates plasma to a plasma formation position, and a drive unit for driving the target holding unit to move the holding surface, wherein the holding surface moves relative to a processing surface in a space along the holding surface, and the processing surface includes at least one plasma formation 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, wherein the plasma formation position, the supply position and the observation position are arranged along the processing surface, and when viewed in the direction of movement of the holding surface by the drive unit, the processing surface includes the supply position located after the plasma formation position and the observation position located after the supply position.

[0008] The light source device according to this disclosure comprises a target holding unit having a holding surface for transporting a target material that generates plasma to a plasma formation position, and a drive unit for driving the target holding unit to move the holding surface, wherein the holding surface moves relative to a processing surface in a space along the holding surface, the processing surface includes at least one plasma formation position and at least one supply position to which the target material is supplied to the holding surface, the plasma formation position and the supply position are arranged along the processing surface, and when viewed in the direction of movement of the holding surface by the drive unit, the length along the processing surface from the plasma formation position to the supply position is shorter than the length along the processing surface from the supply position to the plasma formation position.

[0009] The above-described light source device may further include a forming unit that excites the target material by focusing laser light onto the target material at the plasma formation position.

[0010] In the above-described light source device, the target holding unit may have a rotation axis, and the drive unit may cause the target material to be transported to the target holding unit by rotating the target holding unit around the rotation axis.

[0011] In the above-described light source device, the rotation axis may be substantially perpendicular to the ground surface.

[0012] In the above-described light source device, the processing surface further has at least one observation position from which state information of the holding surface is acquired, and the plasma formation position, the supply position and the observation position may be arranged along the processing surface.

[0013] In the above-described light source device, when viewed in the direction of movement of the holding surface by the drive unit, the length along the processing surface from the supply position to the observation position may be shorter than the length along the processing surface from the observation position to the plasma formation position.

[0014] The above light source device may further include a first debris shield positioned opposite the region between the plasma formation position and the supply position.

[0015] The above light source device may further include a second debris shield positioned opposite the region between the supply position and the observation position.

[0016] The above light source device may further include a third debris shield positioned opposite the region between the plasma formation position and the observation position.

[0017] The above light source device may further include a first debris shield, a second debris shield, and a third debris shield, which are arranged opposite to each other in a first region between the plasma formation position and the supply position, a second region between the supply position and the observation position, and a third region between the plasma formation position and the observation position, respectively.

[0018] In the above-described light source device, a plurality of first debris shields, a plurality of second debris shields, and a plurality of third debris shields respectively arranged to face each other may be further provided in a first region between the plasma formation position and the supply position, a second region between the supply position and the observation position, and a third region between the plasma formation position and the observation position.

[0019] In the above-described light source device, the first debris shield may include an elongated portion whose distance from the processing surface becomes smaller as it moves in the moving direction.

[0020] In the above-described light source device, the angle formed between a portion including at least one of the end portions on the moving direction side of the first debris shield, the second debris shield, and the third debris shield and the tangent line of the processing surface on the extension line of the end portion may be less than 90°.

[0021] In the above-described light source device, the portion including the end portion includes an elongated portion whose distance from the processing surface becomes smaller as it moves in the moving direction, and has a convex shape on the processing surface side, so that the angle with respect to the tangent line of the processing surface on the extension line of the end portion may become smaller as it approaches the end portion.

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

[0023] In the above-described light source device, at least one of the first debris shield, the second debris shield, and the third debris shield may be attached to a debris cover that covers the target holding portion.

[0024] In the above-described light source device, at least one of the first debris shield, the second debris shield, and the third debris shield may be adjusted to a temperature equal to or higher than the melting point of the target material.

[0025] In the above-described light source device, the plasma formation position may be arranged at a position facing the observation position with respect to the rotation axis of the target holding portion.

Advantages of the Invention

[0026] According to the present disclosure, a light source device capable of improving the stability of the light to be extracted can be provided.

Brief Description of the Drawings

[0027] [Figure 1] It is a cross-sectional view illustrating the light source device according to Embodiment 1, showing the cross-section taken along line I-I in FIG. 2. [Figure 2] It is a cross-sectional view illustrating the light source device according to Embodiment 1, showing the cross-section taken along line II-II in FIG. 1. [Figure 3] In the light source device 1 according to Embodiment 1, it is a schematic view illustrating the internal space of the target holding portion. [Figure 4] It is a cross-sectional view illustrating the light source device according to Embodiment 2, showing the cross-section taken along line IV-IV in FIG. 5. [Figure 5] It is a cross-sectional view illustrating the light source device according to Embodiment 2, showing the cross-section taken along line V-V in FIG. 4. [Figure 6] It is a cross-sectional view illustrating the light source device according to a modified example of Embodiment 2.

Modes for Carrying Out the Invention

[0028] Hereinafter, the specific configuration of the present embodiment will be described with reference to the drawings. The following description shows a preferred embodiment of the present disclosure, and the scope of the present disclosure is not limited to the following embodiments. In the following description, those denoted by the same reference numerals indicate substantially the same content.

[0029] <Embodiment 1> A light source device according to Embodiment 1 will now be described. The light source device of this embodiment generates light such as illumination light and exposure light used in optical devices such as inspection devices and exposure devices. The light source device may be provided integrally with the optical device, or it may be placed in the vicinity of the optical device as a separate unit. When the optical device is an inspection device, the light source device generates illumination light to illuminate the object to be inspected in the inspection device. When the optical device is an exposure device, the light source device generates exposure light to expose the object to be exposed in the exposure device.

[0030] The light source device generates light such as illumination light and exposure light by irradiating a target material held in a target holding section with excitation light. In Embodiment 1 below, an example of a light source device is described in which molten metal held in a target holding section including a container such as a crucible is used as the target material. In Embodiment 2, a light source device is described in which a solid held in a target holding section such as a cylindrical drum is used as the target material. Note that the light source device is not limited to one that uses molten metal held in a container such as a crucible as the target material, or a solid held in a target holding section such as a cylindrical drum as the target material, but may also use a solid metal held in a tape-shaped target holding section as the target material, or a droplet-shaped liquid metal as the target material.

[0031] Figure 1 is a cross-sectional view illustrating a light source device 1 according to Embodiment 1, showing the cross-section along line II in Figure 2. Figure 2 is a cross-sectional view illustrating a light source device 1 according to Embodiment 1, showing the cross-section along line II-II in Figure 1. Figure 3 is a schematic diagram illustrating the internal space 10a of the target holding section 10 in the light source device 1 according to Embodiment 1. In Figures 1 to 3, some components may be omitted to avoid making the diagrams cluttered. For example, in Figure 1, the debris shields 61 to 63 in the cover section 60 are omitted.

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

[0033] Here, for the sake of convenience in explaining the light source device 1, we introduce an XYZ Cartesian coordinate system. For example, the rotation axis R of the target holding unit 10 is defined as the Z-axis direction. Note that the introduced XYZ Cartesian coordinate system is for the sake of convenience in explanation and does not limit the orientation of each component.

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

[0035] As will be described later, the target holding section 10 is not limited to including a container such as a crucible. For example, the target holding section 10 may be a cylindrical drum. In that case, the target holding section 10 holds the target material 12 by fixing, for example, a solid substance such as xenon (Xe) frozen on the surface of the drum.

[0036] The target material 12 is not limited to molten metal held in the target holding part 10, but may also be a solid substance, solid metal, or liquid droplet, as long as it generates plasma 11 upon irradiation with excitation light LR. The molten metal is, for example, molten tin (Sn) or lithium (Li), but is not limited to tin and lithium, as long as it generates plasma 11 upon irradiation with excitation light LR.

[0037] The target holding unit 10 has a rotation axis R and rotates around the rotation axis R. The rotation axis R may be approximately perpendicular to the ground surface. As a result, centrifugal force acts evenly on the target material 12 held by the target holding unit 10, so that the thickness of the target material 12 can be made uniform and the light L0 extracted from the light source device 1 can be stabilized.

[0038] The target holding part 10 is, for example, cylindrical in shape with one opening closed. The closed portion of the target holding part 10 is called the bottom portion 13. The cylindrical portion of the target holding part 10 is called the cylindrical portion 14. The inner surface of the bottom portion 13 is called the bottom surface 15. The inner surface of the cylindrical portion 14 is called the inner wall surface 16. The target holding part 10 has a holding surface 17 for holding the target material 12. For example, the target holding part 10 has an inner wall surface 16 as the holding surface 17. In that case, the target holding part 10 holds the target material 12 on the inner wall surface 16 by centrifugal force. Note that the target holding part 10 may also have a surface other than the inner wall surface 16, such as the bottom surface 15, as the holding surface 17, as long as it can hold the target material 12 containing molten metal or the like. Furthermore, the target holding part 10 may include shapes other than those described above, as long as it can hold the target material 12.

[0039] The inner wall surface 16, formed to surround the rotation axis R, may have a groove 18 formed along its inner circumference. The groove 18 is formed, for example, along the intersection line of the inner wall surface 16 and a plane perpendicular to the rotation axis R. The groove 18 is recessed in the inner wall surface 16 in the direction away from the rotation axis R. If the inner wall surface 16 has a groove 18, the target material 12 may 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 turbulence of the liquid surface of the target material 12. In addition, the amount of target material 12 can be limited to within the groove 18, so the required amount of target material 12 can be reduced. Note that a portion of the target material 12 may be located outside the groove 18.

[0040] The inner wall surface 16, formed to surround the rotation axis R, may include a cylindrical portion at a constant distance from the rotation axis R. Furthermore, the inner wall surface 16 may include an inclined surface at which the distance from the rotation axis R changes. For example, the inner wall surface 16 may have a rounded corner at the connection point with the bottom surface 15. The shape of the inner wall surface 16 is not limited to having grooves 18, cylindrical surfaces, inclined surfaces, and rounded corners, as long as it can hold the target material 12.

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

[0042] The drive unit 20 is connected to the target holding unit 10 via a power transmission mechanism such as a shaft. The drive unit 20 drives the target holding unit 10 by transmitting power to it. The drive unit 20 drives the target holding unit 10 to move the holding surface 17. For example, the drive unit 20 may cause the target holding unit 10 to transport the target material 12 by rotating the target holding unit 10 around the rotation axis R. When the target holding unit 10 is viewed from the +Z axis side to the -Z axis side, the drive unit 20 rotates the target holding unit 10 around the rotation axis R in the direction of the hands of a clock. The drive unit 20 may also rotate the target holding unit 10 in the opposite direction to the direction of the hands of a clock around the rotation axis R.

[0043] Here, the predetermined direction in which the drive unit 20 rotates the target holding unit 10 around the rotation axis R is called the direction of movement. For example, the direction in which the hands of a clock rotate around the rotation axis R is called the direction of movement. As the target holding unit 10 rotates in the direction of movement, the holding surface 17 of the target holding unit 10 also rotates around the rotation axis R in the direction of movement. As a result, the target material 12 also rotates around the rotation axis R in the direction of movement. Therefore, the target holding unit 10 has a holding surface 17 that transports the target material 12 that generates plasma 11 to the plasma formation position 130.

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

[0045] The space in which the target holding unit 10 is located is called the movement space 110. The movement space 110 includes the space in which the target holding unit 10 moves. The movement space 110 has a processing surface 117 along the holding surface 17. The processing surface 117 may overlap with the holding surface 17. The holding surface 17 moves relative to the processing surface 117.

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

[0047] The processing surface 117 may include a plurality of plasma formation 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 formation position 130, at least one supply position 140, and at least one observation position 150.

[0048] The plasma formation position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. For example, the plasma formation position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117 in a rotational direction around the rotation axis R. When viewed in the direction of movement of the holding surface 17 by the drive unit 20, the processing surface 117 includes the supply position 140, which is located after the plasma formation position 130. Furthermore, the processing surface 117 includes the observation position 150, which is located after the supply position 140. Therefore, when viewed in the direction of movement of the holding surface 17 by the drive unit 20, the holding surface 17 includes the supply position 140, which is located between the plasma formation position 130 and the observation position 150.

[0049] For example, in the XY plane viewed from the +Z axis side to the -Z axis side, the position of the processing surface 117 is defined by the angle it makes with the +Y axis, with the rotation axis R as the origin. Then, the plasma formation position 130 is located in the region including 0°, for example. The supply position 140 is located in the region including 90°, for example. The observation position 150 is located in the region including 180°. Therefore, the processing surface 117 includes the supply position 140, which is positioned +90° in the direction of movement from the plasma formation position 130. The processing surface 117 also includes the observation position 150, which is positioned +90° in the direction of movement from the supply position 140.

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

[0051] By ensuring that the processing surface 117 includes a supply position 140 located after the plasma formation position 130, the state of the target material 12 supplied at the supply position 140 can be stabilized before plasma is formed at the plasma formation position 130. Furthermore, by ensuring that the processing surface 117 includes an observation position 150 located after the supply position 140, state information of the holding surface 17, including the target material 12 supplied at the supply position 140, can be obtained.

[0052] From the perspective of the internal space 10a, the plasma formation space 130a, the supply space 140a, and the observation space 150a are arranged along the processing surface 117. When viewed in the direction of movement of the holding surface 17 by the drive unit 20, the internal space 10a includes the supply space 140a, which is located after the plasma formation space 130a. Furthermore, the internal space 10a includes the observation space 150a, which is located after the supply space 140a.

[0053] Furthermore, when viewed in the direction of movement of the holding surface 17 by the drive unit 20, the length along the processing surface 117 from the plasma formation 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 formation position 130. In other words, the length measured along the processing surface 117 from the plasma formation position 130 in the direction of clockwise rotation to the supply position 140 is shorter than the length measured along the processing surface 117 from the supply position 140 in the direction of clockwise rotation to the plasma formation position. With this configuration, the state of the target material 12 supplied at the supply position 140 can be stabilized more before plasma is formed at the plasma formation position 130.

[0054] Furthermore, when considering the direction of movement of the holding surface 17 by the drive unit 20, the length along the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length along the processing surface 117 from the observation position 150 to the plasma formation position 130. With this configuration, the state of the holding surface 17 after the supply of the target material 12 can be observed while keeping the observation position 150 away from the plasma formation position 130. Therefore, it is possible to accurately acquire information on the state of the holding surface 17, such as the thickness of the target material 12 heading towards the plasma formation position 130, while reducing the influence of debris generated at the plasma formation position 130 on the observation unit 50.

[0055] Furthermore, it is preferable that the plasma formation position 130 is positioned opposite the observation position 150 with respect to the rotation axis R of the target holding unit 10. This further reduces the influence of debris generated at the plasma formation position 130 on the observation unit 50.

[0056] From the perspective of the internal space 10a, when viewed in the direction of movement of the holding surface 17 by the drive unit 20, the length along the processing surface 117 from the plasma formation space 130a to the supply space 140a is shorter than the length along the processing surface 117 from the supply space 140a to the plasma formation space 130a. Also, when viewed in the direction of movement of the holding surface 17 by the drive unit 20, the length along the processing surface 117 from the supply space 140a to the observation space 150a is shorter than the length along the processing surface 117 from the observation space 150a to the plasma formation space 130a. Furthermore, it is preferable that the plasma formation space 130a is positioned opposite the observation space 150a with respect to the rotation axis R of the target holding unit 10.

[0057] The forming unit 30 includes excitation light LR, etc., arranged in the plasma formation space 130a. At the plasma formation position 130, the forming unit 30 excites the target material 12 by focusing the laser light LR onto the target material 12. As a result, the forming unit 30 generates plasma 11 from the target material 12. When plasma 11 is generated, EUV light LE is generated from the plasma 11. For example, EUV light LE is used as light L0, such as illumination light, in optical devices such as inspection equipment or exposure equipment.

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

[0059] The light source device 1 may include a laser device that generates excitation light LR. Alternatively, the light source device 1 may receive excitation light LR from a laser device installed separately from the light source device 1. The laser device emits excitation light LR including IR light, for example. The excitation light LR may irradiate the target material 12 by controlling the oscillation and stopping of the control unit 80. For example, the excitation light LR is focused by the optical member 31. As a result, the excitation light LR irradiates the target material 12.

[0060] The optical component 31 irradiates the target material 12 with excitation light LR from an axis perpendicular to the surface of the target material 12, at an angle tilted towards the front with respect to the direction of movement of the target holding unit 10. As a result, the angular velocity in the rotational direction of the target holding unit 10 is added in the direction in which the debris is scattered, and the debris is scattered more towards the reflection direction of the excitation light LR, thereby suppressing the amount of debris scattered toward the laser device.

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

[0062] The supply unit 40 may also supply the molten target material 12 to the holding surface 17. For example, the supply unit 40 may supply the molten target material 12 to the holding surface 17 using a debris shield 62. The debris shield 62 is located near the supply position 140. The debris shield 62 is located, for example, opposite the supply position 140. The debris shield 62 is exposed to a temperature above the melting point of the target material 12. In this way, the debris shield 62 may be heated to a temperature above the melting point of the target material 12 by the radiant heat of the target holding unit 10 and the target material 12 within the target holding unit 10. Alternatively, the debris shield 62 may be heated to a temperature above the melting point of the target material 12 by a heating element such as a heater.

[0063] Furthermore, the debris shield 61 positioned opposite the plasma formation position 130, and the debris shield 63 positioned opposite the observation position 150, may also be adjusted to a temperature above the melting point of the target material 12. In other words, at least one of the debris shields 61 to 63 may be adjusted to a temperature above the melting point of the target material 12. This allows the target material 12, which has become debris, to be reused for plasma generation.

[0064] The supply unit 40 may melt the solid target material 12b by bringing it into contact with the debris shield 62 or the like, and supply it into the target holding unit 10. For example, the target material 12 melted by the debris shield 62 falls to the bottom surface 15 and then reaches the inner wall surface 16 by centrifugal force. This eliminates the need to bring the solid target material 12b into contact with the target material 12 on the holding surface 17, thereby suppressing a temperature drop of the target material 12 on the holding surface 17. It also suppresses disturbances to the surface state of the target material 12 due to vibrations, etc.

[0065] The observation unit 50 is located 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 include the surface irregularities, surface roughness, height, reflectance, etc., of the target material 12 held on the holding surface 17. Alternatively, the state information of the holding surface 17 may include the presence or absence of scratches or deposits on the holding surface 17 and their size. 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. The observation unit 50 measures and acquires the surface position of the target material 12 using the position sensor. The position sensor may include, for example, a displacement sensor, a high-speed camera, a low-speed camera, a 4-segment PD (Photo Diode), or a TDI (Time Delay Integration) camera. Furthermore, the position sensor may be a one-dimensional, two-dimensional, or three-dimensional surface position sensor, or a combination of these.

[0066] The observation unit 50, including a position sensor, acquires the displacement of the surface position of the target material 12 based on the acquired surface position of the target material 12. The observation unit 50 may also acquire the surface position of the target material 12 based on its thickness from the holding surface 17.

[0067] It is desirable that the observation unit 50 be positioned away from the plasma formation position 130. For example, the observation unit 50 is positioned opposite the plasma formation position 130 with respect to the rotation axis R. This suppresses the influence of debris and improves the accuracy of surface position measurement.

[0068] The cover portion 60 includes debris shields 61-63 and debris cover 65. However, the cover portion 60 does not necessarily have to include all of the debris shields 61-63 and debris cover 65. The cover portion 60 may include at least one of the debris shields 61-63 and debris cover 65.

[0069] The debris cover 65 is positioned to cover the target holding section 10. For example, the debris cover 65 covers the opening on the +Z axis side of the target holding section 10. The debris cover 65 has openings formed for extracting excitation light LR and EUV light LE. The debris cover 65 suppresses the adhesion of debris scattered with the generation of plasma 11 to the collector mirror, etc. As mentioned above, the debris cover 65 may be adjusted to a temperature above the melting point of the target material 12.

[0070] The debris shield 61 is positioned in the plasma formation space 130a. The debris shield 61 is positioned to cover the plasma formation position 130. The debris shield 61 may include a portion positioned opposite to the region 135 between the plasma formation position 130 and the supply position 140 on the processing surface 117, or a portion positioned opposite to the region 155 between the plasma formation position 130 and the observation position 150 on the processing surface 117. Specifically, the debris shield 61 includes a portion positioned between the formation unit 30 and the supply unit 40, and a portion positioned between the formation unit 30 and the observation unit 50. Thus, the cover unit 60 further comprises a first debris shield (part of the debris shield 61) positioned opposite to the region 135 between the plasma formation position 130 and the supply position 140.

[0071] The debris shield 61 includes an elongated portion 61a, which, when viewed from the +Z-axis side towards the -Z-axis direction, decreases in distance from the processing surface 117 as the direction of movement increases. For example, the portion of the debris shield 61 on the +X-axis side includes an elongated portion 61a, which decreases in distance from the processing surface 117. The angle between the elongated portion 61a, which includes the end 61b on the direction of movement of the debris shield 61, and the tangent to the processing surface 117 on the extension of the end 61b is less than 90°. The elongated portion 61a, which includes the end 61b, has a convex shape toward the processing surface 117 when viewed from the +Z-axis side towards the -Z-axis direction, so that the angle with respect to the tangent to the processing surface 117 on the extension of the end 61b decreases as it approaches the end 61b.

[0072] The debris shield 62 is located in the supply space 140a. The debris shield 62 is positioned to cover the supply position 140. The debris shield 62 is also positioned to cover the supply unit 40 from both sides. The debris shield 62 may include a portion positioned opposite the region 145 between the supply position 140 and the observation position 150 on the processing surface 117, or a portion positioned opposite the region 135 between the supply position 140 and the plasma formation position 130 on the processing surface 117. Specifically, the debris shield 62 includes a portion positioned between the supply unit 40 and the observation unit 50, and a portion positioned between the supply unit 40 and the formation unit 30. Thus, the cover unit 60 further comprises a second debris shield (part of the debris shield 62) positioned opposite the region 145 between the supply position 140 and the observation position 150.

[0073] The debris shield 62 may include a portion positioned on a line extending from the rotation axis R of the target holding section 10 to the processing surface 117. In other words, the debris shield 62 may include a radial portion. This allows the debris shield 62 to smoothly supply the molten target material 12, which is made of debris, to the holding surface 17 by centrifugal force.

[0074] The portion of the debris shield 62 including the end 62b on the moving side may be curved. The angle between the curved portion of the debris shield 62 including the end 62b on the moving side and the tangent to the processing surface 117 on the extension of the end 62b may be less than 90°.

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

[0076] The portion of the debris shield 63 including the end 63b on the moving side may be curved. The angle between the curved portion of the debris shield 63 including the end 63b on the moving side and the tangent to the processing surface 117 on the extension of the end 63b may be less than 90°.

[0077] The cover portion 60 includes a first debris shield, a second debris shield, and a third debris shield, which are positioned opposite each other in the region 135 between the plasma formation position 130 and the supply position 140 on the processing surface 117, the region 145 between the supply position 140 and the observation position 150 on the processing surface 117, and the region 155 between the plasma formation position 130 and the observation position 150 on the processing surface 117. Here, the first debris shield includes a part of the debris shield 61 or a part of the debris shield 62. The second debris shield includes a part of the debris shield 62 or a part of the debris shield 63. The third debris shield includes a part of the debris shield 63 or a part of the debris shield 61.

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

[0079] The cover portion 60 may include a plurality of first debris shields, a plurality of second debris shields, and a plurality of third debris shields, which are arranged opposite each other in the region 135 between the plasma formation position 130 and the supply position 140 on the processing surface 117, the region 145 between the supply position 140 and the observation position 150 on the processing surface 117, and the region 155 between the plasma formation position 130 and the observation position 150 on the processing surface 117. Here, the plurality of first debris shields include a portion of debris shield 61 and a portion of debris shield 62. The plurality of second debris shields include a portion of debris shield 62 and a portion of debris shield 63. The plurality of third debris shields include a portion of debris shield 63 and a portion of debris shield 61.

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

[0081] The optical element 71 reflects the light L0 generated from the target material 12 by irradiation with excitation light LR. The optical element 71 reflects, for example, EUV light LE generated by irradiation with excitation light LR. That is, light L0 may include EUV light LE. EUV light LE is generated from the plasma 11 that is created when excitation light LR is irradiated onto the target material 12. The EUV light LE generated from the plasma 11 generated in the target material 12 is emitted as illumination light to an optical device such as an inspection device. Therefore, the illumination light includes EUV light LE generated from the plasma 11.

[0082] The control unit 80 may control each component in the light source device 1. The control unit 80 is connected to each component in the light source device 1 in a manner that enables information transmission via a communication line, including wireless or wired connections. For example, the control unit 80 analyzes the state information of the target material 12 acquired by the observation unit 50. The control unit 80 also analyzes output information, including the intensity and irradiation position of the light L0, such as illumination light, output by the output optical system 70.

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

[0084] Next, the effects of this embodiment will be described. In the light source device 1 of this embodiment, the plasma formation position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. When viewed in the direction of movement, the processing surface 117 includes the supply position 140, which is located after the plasma formation position 130, and also includes the observation position 150, which is located after the supply position 140. Therefore, the state of the target material 12 supplied at the supply position 140 can be stabilized more before forming the plasma at the plasma formation position 130. In addition, state information of the holding surface 17, including the target material 12 supplied at the supply position 140, can be acquired. Furthermore, the influence of the surface state due to the supply of the target material 12 when generating the plasma 11 at the plasma formation position 130 can be reduced. In addition, state information such as the thickness of the target material 12 at the plasma formation position 130 can be accurately acquired.

[0085] Furthermore, in the light source device 1, the length along the processing surface 117 from the plasma formation 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 formation position 130. Therefore, the state of the target material 12 supplied at the supply position 140 is stabilized before the plasma is formed at the plasma formation position 130. Moreover, even with this configuration, the influence of the surface state due to the supply of the target material 12 can be reduced.

[0086] Furthermore, in the light source device 1, the length along the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length along the processing surface 117 from the observation position 150 to the plasma formation position 130. Therefore, the influence of debris generated at the plasma formation position 130 on the observation unit 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 according to Embodiment 2, showing the cross-section along line IV-IV in Figure 5. Figure 5 is a cross-sectional view illustrating the light source device 2 according to Embodiment 2, showing 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 unit 210 and a drive unit 220. In addition to the target holding unit 210 and the drive unit 220, the light source device 2 may further include a forming unit 230, a supply unit 240, an observation unit 250, a cover unit 260, an output optical system 270, and a control unit 280.

[0088] The target holding section 210 holds the target material 212. The target holding section 210 includes a cylindrical drum 213. The inside of the drum 213 is filled with a coolant 214 such as liquid nitrogen. The target holding section 210 holds the target material 212 by fixing the solid, such as frozen xenon (Xe), which will become the target material 212, to the outer circumferential surface 215 of the drum 213. In this embodiment, the holding surface 217 of the target holding section 210 includes the outer circumferential surface 215 of the drum 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 side to the -Z axis side, the drive unit 220 rotates the target holding unit 210 around the rotation axis R in the direction of the hands of a clock.

[0090] The forming section 230 is located on the +Y axis side of the target holding section 210. The forming section 230 irradiates the target material 212 held on the holding surface 217 on the +Y axis side of the target holding section 210 with excitation light LR that travels in the -Y axis direction. Therefore, the plasma formation position 130 includes the portion of the holding surface 217 on the +Y axis side.

[0091] The supply unit 240 is located 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 of the holding surface 217 on the +X-axis side. The supply port 241 is connected to a gas source 243 for the target material 212. The gas source 243 supplies the gas 242 for the target material 212 to the supply position 140 via the supply port 241. The gas 242 for the target material 212 supplied from the supply port 241 solidifies on the surface of the drum 213, thereby forming the target material 212.

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

[0093] In this embodiment, a target holding unit 210 is arranged in the moving space 110. The target holding unit 210 moves within the moving space 110. The moving space 110 has a processing surface 117 that is aligned with the holding surface 217. The processing surface 117 may overlap with the holding surface 217. The holding surface 217 moves relative to the processing surface 117.

[0094] The plasma formation position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. When viewed in the direction of movement of the holding surface 217 by the drive unit 220, the processing surface 117 includes the supply position 140, which is located after the plasma formation position 130. Furthermore, the processing surface 117 includes the observation position 150, which is located after the supply position 140.

[0095] Furthermore, when viewed in the direction of movement of the holding surface 217 by the drive unit 220, the length along the processing surface 117 from the plasma formation position to the supply position 140 is shorter than the length along the processing surface 117 from the supply position 140 to the plasma formation position 130. Moreover, the length along the processing surface 117 from the supply position 140 to the observation position 150 is shorter than the length along the processing surface 117 from the observation position 150 to the plasma formation position 130.

[0096] The cover portion 260 includes debris shields 261 to 263. Debris shield 261 is positioned opposite the region 135 between the plasma formation position 130 and the supply position 140. Debris shield 262 is positioned opposite the region 145 between the supply position 140 and the observation position 150. Debris shield 263 is positioned opposite the region 155 between the plasma formation position 130 and the observation position 150.

[0097] As in this embodiment, even when the target material 212 is a solid held in a target holding part 210 such as a cylindrical drum, the same effects as in Embodiment 1 can be obtained. That is, the state of the target material 212 supplied at the supply position 140 can be stabilized before plasma is formed at the plasma formation position 130. In addition, state information of the holding surface 217, including the target material 212 supplied at the supply position 140, can be obtained.

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

[0099] Even with this configuration, the plasma formation position 130, the supply position 140, and the observation position 150 are arranged along the processing surface 117. When viewed in the direction of movement of the holding surface 217 by the drive unit 220, the processing surface 117 includes the supply position 140, which is located after the plasma formation position 130. Furthermore, the processing surface 117 includes the observation position 150, which is located after the supply position 140. Other configurations and effects are described in Embodiments 1 and 2.

[0100] While embodiments of the present disclosure have been described above, the disclosure includes appropriate modifications that do not impair its purpose and advantages, and is not limited by the above embodiments. Furthermore, the configurations of Embodiments 1 and 2 and their modifications may be combined as appropriate. [Explanation of Symbols]

[0101] 1, 2, 2a light source device 10 Target holding section 10a Internal space 11 Plasma 12, 12b Target material 13 Bottom 14. Cylindrical section 15. Base 16 Interior wall surface 17 Retention surface 18 Groove 19 Heater 20 Drive unit 30 Formation part 31 Optical components 40 Supply section 50 Observation Section 60 Cover section 61, 62, 63 Debris Shield 61a Elongated section 61b, 62b, 63b ends 65 Debris Cover 70 Output Optics 71 Optical components 80 Control Unit 110 Mobile space 117 Processing surface 130 Plasma formation location 130a Plasma formation space 135 areas 140 Supply position 140a supply space 145 areas 150 Observation Position 150a Observation Space 155 areas 210 Target holding section 212 Target material 213 Drums 214 Coolant 215 Outer surface 217 Retaining surface 220 Drive unit 230 Formation part 240 Supply section 241 Supply port 242 Gas 243 Supplier 250 Observation Section 260 Cover section 261, 262, 263 Debris Shield 270 Output Optics 280 Control Unit L0 light LE EUV light LR excitation light R rotation axis

Claims

1. A target holding section having a holding surface for transporting a target material that generates plasma to a plasma formation position, A drive unit that drives the target holding unit to move the holding surface, Equipped with, The holding surface moves relative to the processing surface in the space along the holding surface, The aforementioned processing surface is At least one of the plasma formation positions, At least one supply position from which the target material is supplied to the holding surface, At least one observation position from which state information of the holding surface is acquired, Includes, The plasma formation position, the supply position, and the observation position are arranged along the processing surface. When viewed in the direction of movement of the holding surface by the drive unit, the processing surface is The supply position is located after the plasma formation position, and includes the supply position located after the plasma formation position. Including the observation position located after the supply position, Light source device.

2. A target holding section having a holding surface for transporting a target material that generates plasma to a plasma formation position, A drive unit that drives the target holding unit to move the holding surface, Equipped with, The holding surface moves relative to the processing surface in the space along the holding surface, The aforementioned processing surface is At least one of the plasma formation positions, At least one supply position from which the target material is supplied to the holding surface, Includes, The plasma formation position and the supply position are arranged along the processing surface. When viewed in the direction of movement of the holding surface by the drive unit, the length along the processing surface from the plasma formation position to the supply position is shorter than the length along the processing surface from the supply position to the plasma formation position. Light source device.

3. The plasma formation position further includes a forming section that excites the target material by focusing laser light onto the target material, The light source device according to claim 1 or 2.

4. The target holding part has a rotation axis, The drive unit causes the target material to be transported to the target holding unit by rotating the target holding unit around the rotation axis. The light source device according to claim 1 or 2.

5. The aforementioned axis of rotation is approximately perpendicular to the ground surface. The light source device according to claim 4.

6. The processing surface further has at least one observation position from which state information of the holding surface is acquired. The plasma formation position, the supply position, and the observation position are arranged along the processing surface. The light source device according to claim 2.

7. When viewed in the direction of movement of the holding surface by the drive unit, the length along the processing surface from the supply position to the observation position is shorter than the length along the processing surface from the observation position to the plasma formation position. The light source device according to claim 1 or 6.

8. The system further comprises a first debris shield positioned opposite to the region between the plasma formation position and the supply position, The light source device according to claim 1 or 2.

9. The system further comprises a second debris shield positioned opposite to the region between the supply position and the observation position, The light source device according to claim 1 or 6.

10. The system further comprises a third debris shield positioned opposite the region between the plasma formation position and the observation position, The light source device according to claim 1 or 6.

11. The system further comprises a first debris shield, a second debris shield, and a third debris shield, each positioned opposite to the first region between the plasma formation position and the supply position, the second region between the supply position and the observation position, and the third region between the plasma formation position and the observation position, respectively. The light source device according to claim 1 or 6.

12. The system further comprises a plurality of first debris shields, a plurality of second debris shields, and a plurality of third debris shields, which are arranged opposite each other in a first region between the plasma formation position and the supply position, a second region between the supply position and the observation position, and a third region between the plasma formation position and the observation position, respectively. The light source device according to claim 1 or 6.

13. The first debris shield includes an elongated portion whose distance from the processing surface decreases with increasing movement direction. The light source device according to claim 8.

14. The angle between the portion of at least one of the first debris shield, the second debris shield, and the third debris shield that includes the end on the moving side and the tangent to the processing surface on the extension of the end is less than 90°. The light source device according to claim 11.

15. The portion including the aforementioned end is, The longer the movement direction, the smaller the distance from the processing surface becomes, By having a convex shape on the processing surface side, the angle with respect to the tangent to the processing surface on the extension of the end becomes smaller as it approaches the end. The light source device according to claim 14.

16. The second debris shield includes a portion positioned on a line extending from the rotation axis of the target holding unit to the processing surface. The light source device according to claim 9.

17. At least one of the first debris shield, the second debris shield, and the third debris shield is attached to the debris cover that covers the target holding portion. The light source device according to claim 11.

18. At least one of the first debris shield, the second debris shield, and the third debris shield is adjusted to a temperature above the melting point of the target material. The light source device according to claim 12.

19. The plasma formation position is positioned opposite the observation position with respect to the rotation axis of the target holding portion. The light source device according to claim 1 or 6.

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