Light source apparatus

Abstract

The light source device according to the present invention includes: a target holding unit having a holding surface for holding a target material for generating light; and a capturing unit configured to acquire state information of the holding surface. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The capturing unit acquires the amount of target material based on the area of ​​the holding surface occupied by the target material in the acquired state information.

Description

[Technical Field]

[0001] This invention relates to a light source device and a method for controlling the 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 member rotating about a pivot axis, and the formed target material is irradiated with excitation light to extract illumination light.

[0003] Patent document 2 describes a light source device that uses centrifugal force to hold a liquid target material on the inner wall of a crucible rotating around a rotation axis, and irradiates the held target material with excitation light to extract illumination light.

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

[0005] When the target material used to generate light is held by a target holding unit such as a cylinder or crucible in the light source device, the amount of target material changes according to the consumption of light generation and the supply from the supply unit. In order to stably extract illumination light, it is desirable to be able to easily obtain the amount of target material held in the target holding unit.

[0006] The present invention was proposed to solve this problem. The purpose of the present invention is to provide a light source device and a control method for the light source device, which can easily obtain the amount of target material.

[0007] The light source device according to the present invention includes: a target holding unit having a holding surface for holding a target material for generating light; an acquisition unit configured to acquire state information of the holding surface; and a processing unit configured to acquire an amount of target material based on the state information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The processing unit acquires the amount of target material based on the area of ​​the holding surface occupied by the target material in the acquired state information.

[0008] In the above-mentioned light source device, the holding surface may further include a third region, the depth of the second region from the predetermined surface is greater than the depth of the third region from the predetermined surface, and when the amount of the target material is a third amount greater than the second amount, the target material is held in the first region, the second region and the third region.

[0009] In the above-described light source device, the processing unit can obtain the amount of target material based on at least one of the width and area of ​​the region of the target material covering the holding surface.

[0010] In the above-described light source device, the capturing unit may include a camera, the capturing unit acquires image information of the holding surface captured by the camera as state information of the holding surface, and the processing unit may acquire the amount of the target material based on the area of ​​the holding surface occupied by the target material identified in the image information.

[0011] The above-mentioned light source device may further include a forming unit, which includes a condenser lens that focuses the excitation light that forms plasma through the excitation target onto the target, and a camera that takes pictures of the holding surface through the condenser lens.

[0012] In the above-mentioned light source device, the acquisition unit may further include a displacement meter, the displacement meter outputs the displacement amount of the surface position of the target material covering the holding surface, and the processing unit may acquire the amount of the target material based on image information and displacement amount.

[0013] In the above-described light source device, the holding surface may include a discontinuity between the first region and the second region. When the amount of the target material is a first amount, the discontinuity may not be covered by the target material, and when the amount of the target material is a second amount, the discontinuity may be covered by the target material.

[0014] In the above-described light source device, the discontinuity may be formed at the corner where the plane including the holding surface of the first region and the plane including the holding surface of the second region are connected together.

[0015] In the above-described light source device, the target holding unit may include a crucible that rotates about a rotation axis, and a first region and a second region may be formed on the inner circumferential surface of the crucible.

[0016] In the above-described light source device, the first region and the second region may each include a portion extending about the rotation axis along the rotation direction.

[0017] In the above-described light source device, the first region and the second region may each include a portion extending along the direction of the rotation axis.

[0018] In the above-described light source device, the target holding unit may include a cylinder that rotates about a rotation axis, and a first region and a second region may be formed on the outer peripheral surface of the cylinder.

[0019] In the above-described light source device, the first region and the second region may each include a portion extending about the rotation axis along the rotation direction.

[0020] In the above-described light source device, the first region and the second region may each include a portion extending along the direction of the rotation axis.

[0021] The control method of the light source device according to the present invention includes: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of target material based on the state information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The processing step includes acquiring the amount of target material based on the area of ​​the holding surface occupied by the target material in the state information.

[0022] The light source device according to the present invention includes: a target holding unit having a holding surface for holding a target material for generating light; an acquisition unit including a camera and acquiring image information of the holding surface captured by the camera; and a processing unit configured to acquire an amount of target material based on the image information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The processing unit acquires the amount of target material based on the region of the holding surface occupied by the target material identified in the image information.

[0023] The light source device according to the present invention includes: a target holding unit having a holding surface for holding a target material for generating light; an acquisition unit including a camera and acquiring image information of the holding surface captured by the camera; and a processing unit configured to acquire an amount of target material based on the image information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The holding surface includes a discontinuity between the first and second regions. When the amount of target material is the first amount, the discontinuity is not covered by the target material. When the amount of target material is the second amount, the discontinuity is covered by the target material. The processing unit acquires the amount of target material based on the presence or absence of specific light in the discontinuity identified in the image information.

[0024] The light source device according to the present invention includes: a target holding unit having a holding surface for holding a target material for generating light; an acquisition unit including a camera and acquiring image information of the holding surface captured by the camera; and a processing unit configured to acquire an amount of target material based on the image information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The second region has a protruding tip. The processing unit acquires the amount of target material based on the presence or absence of specific light in the second region identified in the image information.

[0025] The control method of the light source device according to the present invention includes: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of target material based on the state information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The acquisition step includes acquiring image information of the holding surface captured by a camera as state information. The processing step includes acquiring the amount of target material based on the area of ​​the holding surface occupied by the target material identified in the image information.

[0026] The control method of the light source device according to the present invention includes: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of target material based on the state information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from a predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The holding surface includes a discontinuity between the first and second regions. When the amount of target material is a first amount, the discontinuity is not covered by the target material. When the amount of target material is a second amount, the discontinuity is covered by the target material. The acquisition step includes acquiring image information of the holding surface captured by a camera as state information. The processing step includes acquiring the amount of target material based on the presence or absence of specific light in the discontinuity identified in the image information.

[0027] The control method of the light source device according to the present invention includes: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of target material based on the state information. The holding surface includes a first region and a second region. The depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface. When the amount of target material is a first amount, the target material is held in the first region. When the amount of target material is a second amount greater than the first amount, the target material is held in both the first and second regions. The second region has a protruding tip. The acquisition step includes acquiring image information of the holding surface captured by a camera as state information. The processing step includes acquiring the amount of target material based on the presence or absence of specific light in the second region identified in the image information.

[0028] According to the present invention, a light source device and a control method for the light source device can be provided, which can acquire the amount of target material.

[0029] The above and other objects, features and advantages of the present invention will be more fully understood from the following detailed description and drawings.

Implementation Method

[0045] The specific configuration of this embodiment will now be described with reference to the drawings. The following description shows a preferred embodiment of the invention. The scope of the invention is not limited to the following embodiments. In the following description, symbols designated with the same reference numerals indicate similar content.

[0046] [First Embodiment]

[0047] A light source device is described according to a first embodiment. The light source device of this embodiment generates light, such as illumination light and exposure light, for use with optical devices, such as inspection devices and lithography devices. The light source device may be integrated with the optical device or disposed adjacent to the optical device as a separate device. When the optical device is an inspection device, the light source device generates illumination light to illuminate the target being inspected in the inspection device. When the optical device is a lithography device, the light source device generates exposure light to expose the target being exposed in the lithography device.

[0048] The light source device irradiates a target material held in a target holding unit with excitation light, thereby generating light such as illumination light and exposure light. In the first embodiment below, as an example of a light source device, an example of holding a liquid target material in a target holding unit including a container such as a crucible is described. In the second embodiment, an example of holding a solid target material in a target holding unit including a cylinder is described. It should be noted that the light source device is not limited to a device using a liquid target material held in a container such as a crucible, nor is it limited to a device using a solid target material held in a cylinder, etc.; it may also be a device using a strip target material or a target material that is dripped or ejected in droplet form.

[0049] FIG1 is a cross-sectional view of an example of the light source device 1 according to the first embodiment, showing a section along line II of FIG2. FIG2 is a cross-sectional view of an example of the light source device 1 according to the first embodiment, showing a section along line II-II of FIG1. ​​In FIG1 and FIG2, some components are sometimes omitted to avoid complexity of the diagrams. In addition, some symbols may be omitted. The same applies to the following diagrams.

[0050] As shown in Figures 1 and 2, the light source device 1 includes a target holding unit 10, a capturing unit 20, and a processing unit 22. It should be noted that, in addition to the target holding unit 10, the capturing unit 20, and the processing unit 22, the light source device 1 may further include a driving unit DU, a forming unit 30, a supply unit 40, a cover 60, an output optical system 70, and a control unit 80.

[0051] Here, for ease of description of the light source device 1, an XYZ orthogonal coordinate system is introduced. For example, assume that the rotation axis R of the target holding unit 10 is in the Z-axis direction. It should be noted that the XYZ orthogonal coordinate system is introduced for ease of description and does not restrict the orientation of each element.

[0052] The target holding unit 10 holds the target material 12 for generating light. The target holding unit 10 may include a container such as a crucible. The target holding unit 10 allows metal to melt inside. The target holding unit 10 holds the liquid target material 12 for forming plasma 11 under irradiation by excitation light LR. The excitation light LR is, for example, a laser light including infrared (IR) light.

[0053] It should be noted that, as described below, the target holding unit 10 is not limited to a configuration including a container such as a crucible. For example, the target holding unit 10 may be a cylindrical tube. In this case, the target holding unit 10 holds the target material 12, for example, by fixing the material (e.g., frozen xenon (Xe)) as the target material 12 in a solid state to the surface of the tube.

[0054] The target material 12 is not limited to the liquid material held in the target holding unit 10, but may include solid materials such as strip materials and solid metals, as long as the material forms plasma 11 by irradiation of excitation light LR. The liquid material is, for example, molten metal such as molten tin (Sn) or lithium (Li), but is not limited to tin or lithium, as long as the material generates plasma 11 by irradiation of excitation light LR.

[0055] The target holding unit 10 has a rotation axis R and rotates about the rotation axis R centered on the rotation axis R. For example, the target holding unit 10 includes a crucible or the like that rotates about the rotation axis R. The rotation axis R can be substantially orthogonal to the contact surface. This will apply centrifugal force uniformly to the target material 12 held in the target holding unit 10. Therefore, the thickness of the target material 12 can become uniform, which can stabilize the light L0 extracted from the light source device 1.

[0056] The target holding unit 10 is, for example, a cylindrical shape with a closed opening. It should be noted that the target holding unit 10 may have a shape other than a mortar-shaped or barrel-shaped cylinder, as long as it can hold the target material 12. The closed portion of the target holding unit 10 is called the bottom 13. The cylindrical portion of the target holding unit 10 is called the cylindrical portion 14. The inner surface of the bottom 13 is called the bottom surface 15. The inner surface of the cylindrical portion 14 is called the inner circumferential surface 16.

[0057] The target holding unit 10 has a holding surface 17 for holding the target material 12. For example, the target holding unit 10 has an inner peripheral surface 16 as the holding surface 17. In this case, the target holding unit 10 holds the target material 12 on the inner peripheral surface 16 by centrifugal force. It should be noted that the target holding unit 10 may use a surface other than the inner peripheral surface 16 of the bottom surface 15 as the holding surface 17, as long as it can hold the target material 12. That is, in addition to the inner peripheral surface 16, the holding surface 17 may have a surface other than the inner peripheral surface 16, or it may not have an inner peripheral surface 16 but have a surface other than the inner peripheral surface 16.

[0058] The inner circumferential surface 16 formed around the rotation axis R may have a recess formed along the inner circumferential surface 16. The recess includes, for example, a groove H1. In the following description, it is assumed that the recess is a groove H1. The holding surface 17 may have a groove H1. For example, the groove H1 is formed along the intersection line of the inner circumferential surface 16 and the surface orthogonal to the rotation axis R. The groove H1 is a recess formed on the inner circumferential surface 16 in a direction away from the rotation axis R. When the inner circumferential surface 16 has a groove H1, the target 12 can be held in the groove H1. By holding the target 12 in the groove H1, the movement of the target 12 in the Z-axis direction can be restricted, and the liquid surface of the target 12 can be prevented from being disturbed. In addition, the amount of target 12 can be limited within the groove H1. Therefore, the required amount of target 12 can be reduced. It should be noted that a portion of the target 12 may be located outside the groove H1.

[0059] FIG3 is a cross-sectional view showing an example of the groove H1 of the target holding unit 10 in the light source device 1 according to the first embodiment. As shown in FIG3, in addition to the groove H1, the inner peripheral surface 16 of the holding surface 17 may also include a cylindrical surface H0 having a constant distance from the rotation axis R. The inner peripheral surface 16 may further include an inclined surface H2 having a different distance from the rotation axis R. For example, the inner peripheral surface 16 may include an inclined surface H2 having a corner R at the connection portion with the bottom surface 15. Therefore, the holding surface 17 may include the cylindrical surface H0, the groove H1, and the inclined surface H2. For example, the groove H1 is formed between the cylindrical surface H0 and the inclined surface H2 in the Z-axis direction. It should be noted that the holding surface 17 is not limited to including the cylindrical surface H0, the groove H1, and the inclined surface H2, and may not include the cylindrical surface H0, the groove H1, and the inclined surface H2, as long as the holding surface 17 can hold the target material 12.

[0060] The groove H1 may include a first region H11, a second region H12, and a third region H13. Therefore, the retaining surface 17 may include the first region H11, the second region H12, and the third region H13. It should be noted that the retaining surface 17 may not necessarily include all of the first region H11, the second region H12, and the third region H13, as long as it includes at least one of the first region H11, the second region H12, and the third region H13.

[0061] A first region H11, a second region H12, and a third region H13 are formed on the inner circumferential surface 16 of the crucible. Specifically, the first region H11, the second region H12, and the third region H13 are formed along the intersection line between the inner circumferential surface 16 and the surface orthogonal to the rotation axis R. Therefore, the first region H11, the second region H12, and the third region H13 are formed in a ring shape on the inner circumferential surface 16. In other words, each of the first region H11, the second region H12, and the third region H13 has a portion extending about the rotation axis R in the direction of rotation.

[0062] The first region H11, the second region H12, and the third region H13 may be continuously formed into a ring shape in the rotational direction. Furthermore, each of the first region H11, the second region H12, and the third region H13 may include a plurality of portions aligned in the rotational direction. As described later, each region (e.g., the first region H11, the second region H12, etc.) may each have a portion extending in the direction of the rotation axis R.

[0063] The first region H11 is positioned relative to the third region H13 on the +Z axis side. The first region H11 is positioned relative to the second region H12 on the -Z axis side. The second region H12 is positioned relative to the first region H11 on the +Z axis side. The second region H12 is positioned relative to the cylindrical surface H0 on the -Z axis side. The third region H13 is positioned relative to the first region H11 on the -Z axis side. The third region H13 is positioned relative to the second region H12 on the +Z axis side.

[0064] The cross-section of the first region H11 is a rectangle with an opening on one side of the rotation axis R. The cross-section of the second region H12 is formed in the Z-axis direction as a stepped shape between the cylindrical surface H0 and the first region H11. The cross-section of the third region H13 is formed in the Z-axis direction as a stepped shape between the inclined surface H2 and the first region H11.

[0065] Each portion of the first region H11, the second region H12, and the third region H13 in the groove H1 may have different depths. That is, each portion of the first region H11, the second region H12, and the third region H13 may be positioned at different locations relative to the predetermined surface of the retaining surface 17 on which the groove H1 is formed, in a direction away from the rotation axis R. For example, when the predetermined surface of the retaining surface 17 on which the groove H1 is formed is a cylindrical surface H0, each portion of the first region H11, the second region H12, and the third region H13 may be positioned at different locations relative to the cylindrical surface H0 in a direction away from the rotation axis R.

[0066] As described above, when the distance from the predetermined surface of the holding surface 17 to the rotation axis R is defined as the reference distance, the absolute value of the difference between the reference distance and the distance from each portion of the first region H11, the second region H12, and the third region H13 to the rotation axis R is called the depth. Furthermore, the depth of each portion of the first region H11, the second region H12, and the third region H13 is also the distance from the predetermined surface to each portion in a direction orthogonal to the surface of the target material 12. The predetermined surface is located on the surface side of the target material 12. The distance from the rotation axis R to the predetermined surface of the holding surface 17 may be shorter than the distance from the rotation axis R to the first region H11, the second region H12, and the third region H13. In this embodiment, the depth is the length obtained by subtracting the reference distance from the distance between each portion of the first region H11, the second region H12, and the third region H13 and the rotation axis R.

[0067] Although the reference distance is defined, for example, as the distance from the cylindrical surface H0 to the rotation axis R, this is only one example. The reference distance can be the distance from the shallowest third region H13 to the rotation axis R. The surface used as a reference for introducing the reference distance is called the predetermined surface. Then, the depth of the first region H11 from the predetermined surface is greater than the depth of the second region H12 from the predetermined surface. The depth of the second region H12 from the predetermined surface is greater than the depth of the third region H13 from the predetermined surface. In this embodiment, the depth can be simply defined as the distance from the rotation axis R.

[0068] The depths of the first region H11, the second region H12, and the third region H13 may each have a predetermined range. For example, the depth of the third region H13 may be greater than the fourth depth (the depth of the cylindrical surface H0) and equal to or less than the third depth. The depth of the second region H12 may be greater than the third depth and equal to or less than the second depth. The depth of the first region H11 may be greater than the second depth and equal to or less than the first depth. Here, the following condition is satisfied: first depth ˃ second depth ˃ third depth ˃ fourth depth.

[0069] The retaining surface 17 may include a discontinuity H3 between the first region H11 and the second region H12, which will be defined later. The retaining surface 17 may include a discontinuity H3 between the first region H11 and the third region H13.

[0070] As shown in Figure 3, the cross-section of the second region H12 is formed in a stepped shape in the Z-axis direction between the cylindrical surface H0 and the first region H11. In this way, the boundary between the first region H11 and the second region H12, the depth of the first region H11, and the depth of the second region H12 can vary discontinuously, and a portion shallower than the first region H11 can be formed. In such an example, the boundary portion with discontinuously varying depth can be called the discontinuity H3.

[0071] The surface of the target 12 includes a flat portion. Therefore, the surface of the target 12 reflects the emitted light of the plasma 11 or light such as predetermined illumination light in a fixed direction. On the other hand, the discontinuity H3 reflects or scatters the emitted light of the plasma 11 or light such as predetermined illumination light in a manner different from that of the surface of the target 12. Therefore, by providing the discontinuity H3 between the first region H11 and another region, it is possible to easily determine whether the target 12 is held only in the first region H11 or simultaneously in the second region H12 and the first region H11 by the presence or absence of a specific light (e.g., reflected light, scattered light, etc.). This is because when the target 12 is held in both the second region H12 and the first region H11, the discontinuity H3 between the second region H12 and the first region H11 is covered by the target 12, thereby suppressing the occurrence of reflected or scattered light from the discontinuity H3.

[0072] The location of the discontinuity H3 is not limited to the part between the first region H11 and another region, and the discontinuity H3 can be formed between the second region H12 and another region or between the third region H13 and another region.

[0073] When the amount of target 12 is a first amount 12a, target 12 is held in the first region H11. More specifically, when the amount of target 12 is the first amount 12a, target 12 is held in the first region H11, and not in the second region H12. When the amount of target 12 is the first amount 12a, target 12 is held in the first region H11, and not in the second region H12 and the third region H13. The first amount 12a may be a fixed value or may have a predetermined range. The amount held in the first region H11 may be the first amount 12a. When the amount of target 12 is a second amount 12b greater than the first amount 12a, target 12 is held in both the first region H11 and the second region H12. More specifically, when the amount of target 12 is the second amount 12b, target 12 is held in the first region H11 and the second region H12, rather than in the third region H13. The second amount 12b can be a fixed value or have a predetermined range. The amount held in the second region H12 can be the second amount 12b. When the amount of target 12 is a third amount 12c greater than the second amount 12b, target 12 is held in the first region H11, the second region H12, and the third region H13. The third amount 12c can be a fixed value or have a predetermined range. The amount held in the third region H13 can be the third amount 12c. For clarity, in the description of this embodiment, the phrase "target 12 is held in the Nth region" can be understood as the target holding unit 10 rotating at a sufficient speed, causing target 12 to contact the Nth region, so that target 12 is held against the holding surface 17 by centrifugal force. Similarly, the phrase "target 12 covers or occupies a certain part or area" can also be understood in the same way. When the light source device 1 is operated to irradiate the target 12 with excitation light and extract the generated light, it can be regarded as the target holding unit 10 rotating at a sufficient speed.

[0074] When the holding surface 17 has a discontinuity H3 between the first region H11 and the second region H12, when the amount of the target material 12 is the first amount 12a, the discontinuity H3 is not covered by the target material 12, while when the amount of the target material 12 is the second amount 12b, the discontinuity H3 is covered by the target material 12. Similarly, for example, when the holding surface 17 has a discontinuity H3 between the second region H12 and the third region H13, when the amount of the target material 12 is the second amount 12b, the discontinuity H3 is not covered by the target material 12, while when the amount of the target material 12 is the third amount 12c, the discontinuity H3 is covered by the target material 12.

[0075] Figures 4 to 6 are cross-sectional views showing an example of another groove H1 in the target holding unit 1 of the light source device 1 according to the first embodiment. As shown in Figure 4, the cross-section of the groove H1 may have an arcuate portion and a straight portion connected together. The first region H11 is provided at the deepest part of the groove H1, that is, the part of the groove H1 farthest from the rotation axis R. The second region H12 and the third region H13 are arranged sequentially from the first region H11 in the +Z axis direction. The second region H12 and the third region H13 are also arranged sequentially from the first region H11 in the -Z axis direction. The first region H11 is arranged such that it is held between the two second regions H12. The first region H11 and the second region H12 are arranged such that they are held between the two third regions H13.

[0076] Under the above configuration, when the amount of target 12 is a first amount 12a, target 12 is held in the first region H11. When the amount of target 12 is a second amount 12b greater than the first amount 12a, target 12 is held in both the first region H11 and the second region H12. When the amount of target 12 is a third amount 12c greater than the second amount 12b, target 12 is held in the first region H11, the second region H12, and the third region H13.

[0077] As shown in Figure 5, the cross-section of the groove H1 can be a transverse V-shape. The V-shaped opening faces the rotation axis R. The first region H11 is located at the deepest part of the groove H1, that is, the part of the groove H1 farthest from the rotation axis R. The second region H12 and the third region H13 are sequentially arranged from the first region H11 in the +Z axis direction. The second region H12 and the third region H13 are also sequentially arranged from the first region H11 in the -Z axis direction. The arrangement of the first region H11 is such that it is held between the two second regions H12. The arrangement of the first region H11 and the second region H12 is such that they are held between the two third regions H13. The correspondence between the amount of target 12 and the region where the target 12 is held is similar to that shown in Figure 4.

[0078] For example, the angle between a surface including the first region H11 and a predetermined surface (e.g., the surface of the target 12) may be different from the angle between a surface including the second region H12 and the predetermined surface. In this way, the angles of surfaces including two (adjacent and different) regions relative to the predetermined surface may be different at the boundary between the two regions. That is, at the boundary between the two regions, the angle of the surface including each region may change discontinuously. In this way, the portion where the angle changes discontinuously with respect to the predetermined surface may also be called a discontinuity H3. The discontinuity H3 may be formed at the corner where the plane of the holding surface 17 including the first region H11 and the plane of the holding surface 17 including the second region H12 are joined together. The discontinuity H3 may be formed at the corner where the plane of the holding surface 17 including the second region H12 and the plane of the holding surface 17 including the third region H13 are joined together.

[0079] Based on the above discussion, the discontinuity H3 may indicate at least one of a boundary portion with discontinuous depth (e.g., stepped) and a boundary portion with discontinuous angle.

[0080] As shown in Figure 6, two first regions H11 are disposed on the +Z axis side relative to the third region H13. The two first regions H11 are vertically aligned in the Z axis direction. The second region H12 is disposed such that it is held between the two first regions H11. The second region H12 is shaped such that its top protrudes. Therefore, when the protrusion H4 of the second region H12 protrudes to the surface of the target 12, it can be said that the target 12 is held in the first region H11, rather than in the second region H12. Therefore, in this case, the amount of the target 12 is a first amount 12a. Until the protrusion H4 is covered by the target 12 and the target 12 occupies the third region H13, the target 12 is held in the first region H11 and the second region H12, rather than in the third region H13. Therefore, in this case, the amount of the target 12 is a second amount 12b.

[0081] FIG7 is a diagram showing an example of another groove H1 in the target holding unit 10 of the light source device 1 according to the first embodiment. FIG8 is a cross-sectional view showing an example of another groove H1 in the target holding unit 10 of the light source device 1 according to the first embodiment, wherein (a) shows the α-α section of FIG7, (b) shows the β-β section of FIG7, and (c) shows (a) and (b) in an overlapping manner. As shown in FIG7 and FIG8, the first region H11 and the second region H12 may each have a portion extending in the direction of the rotation axis R. The holding surface 17 has a plurality of first regions H11. The plurality of first regions H11 are formed to be aligned along the holding surface 17 in the rotational direction about the rotation axis R. The plurality of first regions H11 extend in the direction of the rotation axis R. Specifically, each first region H11 includes a groove extending in the direction of the rotation axis R. Second regions H12 are formed between adjacent first regions H11. The plurality of second regions H12 extend in the direction of the rotation axis R. The position of the end of the first region H11 extending in the direction of the rotation axis R on the +Z direction side is relative to the position of the end of the second region H12 on the +Z axis side, and is attached to the +Z axis side. The position of the end of the first region H11 extending in the direction of the rotation axis R on the -Z direction side is relative to the position of the end of the second region H12 on the -Z axis side, and is attached to the -Z axis side.

[0082] When the amount of the target 12 is the first amount 12a, the target 12 is held in the groove of the first region H11. When the amount of the target 12 is the second amount 12b, the target 12 is held in both the first region H11 and the second region H12.

[0083] The holding surface 17 may further include a third region H13 and a fourth region H14. The third region H13, which is the region between adjacent first regions H11, includes the region other than the second region H12. Therefore, the third region H13 includes a plurality of regions on the +Z-axis side relative to the second region H12 and a plurality of regions on the -Z-axis side relative to the second region H12. The fourth region H14 includes an annular region on the +Z-axis side relative to the region including the first region H11, the second region H12, and the third region H13, and an annular region on the -Z-axis side relative to the region including the first region H11, the second region H12, and the third region H13. When the amount of the target 12 is the third amount 12c, the target 12 is held in the first region H11, the second region H12, and the third region H13. When the amount of target 12 is the fourth amount 12d, target 12 is held in the first region H11, the second region H12, the third region H13, and the fourth region H14. The amount of target 12 satisfies the following condition: first amount 12a ⊥ second amount 12b ⊥ third amount 12c ⊥ fourth amount 12d. Discontinuity H3b is formed between the first region H11, the third region H13, and the fourth region H14. Discontinuity H3a is formed between the second region H12 and the third region H13.

[0084] When the amount of the target material 12 changes from the fourth amount 12d to the third amount 12c, which is less than the fourth amount 12d, specific light appears from the discontinuity H3b in the surrounding area having the cross-section of FIG. 8(b). Therefore, the processing unit 22 can obtain the amount of the target material 12 based on whether specific light from the discontinuity H3b exists in the image captured by the capturing unit 20. As shown in this example, the discontinuity H3b may only be formed in a portion of the surrounding area of ​​the entire surrounding area.

[0085] Furthermore, when the amount of the target material 12 has changed from the fourth amount 12d to the third amount 12c, which is less than the fourth amount 12d, the width of the area occupied by the target material 12 in the surrounding area with the cross-section of FIG8(b) is wider than the width of the area occupied by the target material 12 in the surrounding area with the cross-section of FIG8(a) by an amount corresponding to the length D1 + length D2 shown in FIG8(c). Then, when the capture unit 20 acquires the supplementary capture image of the surrounding area with the cross-section of FIG8(b) and the surrounding area with the cross-section of FIG8(a), when the amount of the target material 12 is the third amount 12c, the parameters such as brightness and contrast of the captured image acquired from the capture unit 20 are different from the parameters of the captured image acquired from the capture unit 20 when the amount of the target material 12 is the fourth amount 12d. This is because when the amount of the target material 12 is the fourth amount 12d, the target material 12 with a width corresponding to the length D1 + length D2 (a portion of which depends on the viewing angle) is captured throughout the entire perimeter. However, when the amount of the target material 12 is the third amount 12c, the target material 12 is not imaged in the portion of the surrounding area, i.e., it is not imaged in the surrounding area with the cross-sectional structure shown in FIG8(a). Therefore, the processing unit 22 can obtain the amount of the target material 12 from the changes in brightness, contrast, etc. of the image captured by the capturing unit 20. In other words, in a portion of the surrounding area, the first region H11 and the second region H12 are formed as portions extending in the direction of the rotation axis R, and at this time, the position of the end on the +Z direction side (and / or -Z direction side) of the first region H11 is located on the +Z axis side (and / or -Z direction side) relative to the position of the end on the +Z direction side (and / or -Z direction side) of the second region H12. In this way, the processing unit 22 can obtain the amount of the target material 12 from the changes in brightness, contrast, etc. of the image captured by the capturing unit 20.

[0086] Furthermore, when the amount of the target material 12 changes from the third amount 12c to a second amount 12b that is less than the third amount 12c, specific light appears from the discontinuity H3a in the surrounding area having the cross-section of FIG. 8(a). Therefore, the processing unit 22 can obtain the amount of the target material 12 based on whether specific light from the discontinuity H3a exists in the image captured by the capturing unit 20. As shown in this example, the discontinuity H3a may only be formed in a portion of the surrounding area of ​​the entire surrounding area.

[0087] It should be noted that the first region H11 and the second region H12 in FIG. 7 may have opposite configurations. That is, the portion of the groove extending along the direction of the rotation axis R may be shallower than the portion formed between adjacent grooves. Therefore, the second region H12 includes the portion extending along the direction of the rotation axis R, while the first region H11 includes the portion formed between adjacent grooves. It should be noted that the first region H11 may be integrated together to connect the plurality of portions formed between adjacent grooves and formed as a strip along the inner circumferential surface 16. In this way, the retaining surface 17 may include the first region H11 extending about the rotation axis R in the direction of rotation and the second region H12 extending in the direction of the rotation axis R.

[0088] As shown in Figure 1, the heater 19 is disposed in the target holding unit 10. Heating by the heater 19 can form a liquid target material 12 in the target holding unit 10.

[0089] The drive unit DU is connected to the target holding unit 10 via a power transmission mechanism such as a shaft. The drive unit DU drives the target holding unit 10 by transmitting power to it. The drive unit DU moves the holding surface 17 by driving the target holding unit 10. For example, the drive unit DU feeds the target material 12 to the target holding unit 10 by rotating the target holding unit 10 about the rotation axis R.

[0090] The capturing unit 20 acquires information on the holding surface 17 of the target holding unit 10. The information on the holding surface 17 is called status information. The capturing unit 20 may include a camera 21. The capturing unit 20 may include a camera 21 that captures images using visible light, or it may include a camera 21 that captures images using light other than visible light. The capturing unit 20 may include a camera 21 that captures still images, or it may include a camera 21 that captures moving images.

[0091] The capturing unit 20 acquires image information of the holding surface 17 captured by the camera 21, which serves as state information of the holding surface 17 of the target holding unit 10. Specifically, the camera 21 captures an image of the groove H1, thereby the capturing unit 20 acquires image information of the groove H1. For example, the camera 21 captures an image of the target material 12 held in the first region H11. Therefore, the capturing unit 20 can acquire first image information, in which it is identified that the target material 12 is held in the first region H11 and not held in the second region H12. Furthermore, the camera 21 captures images of the target material 12 held in both the first region H11 and the second region H12. Therefore, the capturing unit 20 can acquire second image information, in which it is identified that the target material 12 is held in both the first region H11 and the second region H12. Similarly, the camera 21 captures images of the target material 12 held in the first region H11, the second region H12, and the third region H13. Therefore, the capturing unit 20 can acquire third image information, in which the target 12 is identified as being held in the first region H11, the second region H12, and the third region H13. The capturing unit 20 outputs the acquired state information to the processing unit 22.

[0092] The processing unit 22 acquires the amount of the target 12 based on the area of ​​the target 12 occupying the holding surface 17 in the acquired state information (i.e., based on state information identification). The processing unit 22 may acquire the amount of the target 12 based on at least one of the width and area of ​​the area of ​​the target 12 occupying the holding surface 17 in the image information. The width and area of ​​the area of ​​the target 12 occupying the holding surface 17 may be identified based on the area in the captured image that is identified as the target 12. The processing unit 22 may acquire the amount of the target 12 as the total amount of the target 12 held by the target holding unit 10 (such as the amount of the target 12 included in the container having the holding surface 17), or as the amount of the target 12 in a partial area of ​​the holding surface 17 (e.g., the area where state information has been acquired).

[0093] The processing unit 22 can acquire the amount of the target 12 based on the presence or absence of specific light from the discontinuity H3 or from the second region H12 (e.g., the protrusion H4) in the acquired state information (i.e., based on state information identification). The processing based on the presence or absence of specific light from the discontinuity H3 and from the second region H12 (e.g., the protrusion H4) is an example of processing based on the area occupied by the target 12 on the holding surface 17. Acquiring the amount of the target 12 may include estimating and predicting the amount of the target 12, determining and estimating that the amount of the target 12 has decreased or increased from a predetermined level, etc. The processing unit 22 can acquire information related to the amount of the target 12 based on the area occupied by the target 12 on the holding surface 17 in the acquired state information (i.e., based on state information identification). The information related to the amount of the target 12 may include, for example, the amount of the target 12, whether the amount of the target 12 has increased or decreased from a predetermined level, and the acquisition processing may include estimation and prediction processing.

[0094] Furthermore, the processing unit 22 can control the supply amount of the target 12 in the supply unit 40 based on the area occupied by the target 12 on the holding surface 17 in the acquired state information (i.e., based on state information recognition). For example, the processing unit 22 performs control to increase the supply amount from the supply unit 40 to compensate for a decrease in the amount of the target 12, or performs control to decrease the supply amount from the supply unit 40 to cope with an increase in the amount of the target 12. In addition, the processing unit 22 can control the forming unit 30; for example, the processing unit 22 can control the irradiation frequency of the excitation light LR, the orientation of the optical elements, etc., based on the area occupied by the target 12 on the holding surface 17 in the acquired state information (i.e., based on state information recognition). In this way, the processing unit 22 can perform various controls based on information related to the amount of the acquired target 12 and the state control of the light source device 1. In addition, the processing unit 22 can acquire control information based on the amount of the target 12 based on the area occupied by the target 12 on the holding surface 17 in the acquired state information (i.e., based on state information recognition). The processing unit 22 can control the state of the light source device 1, such as the supply unit 40 and the forming unit 30, based on the control information of the amount of the target material 12.

[0095] For example, when camera 21 acquires first image information, processing unit 22 determines the amount of target 12 as a first amount 12a. Therefore, processing unit 22 acquires the first amount 12a as the amount of target 12. When camera 21 acquires second image information, processing unit 22 determines the amount of target 12 as a second amount 12b. Therefore, processing unit 22 acquires the second amount 12b as the amount of target 12. When camera 21 acquires third image information, processing unit 22 determines the amount of target 12 as a third amount 12c. Therefore, processing unit 22 acquires the third amount 12c as the amount of target 12.

[0096] The processing unit 22 can predict the amount of the target 12 based on the area occupied by the target 12 on the holding surface 17 in the acquired state information (i.e., based on state information identification). That is, the processing unit 22 can obtain the predicted amount of the target 12. For example, the processing unit 22 obtains supply information about the supply of the target 12 through the supply unit 40 directly from the supply unit 40 or indirectly through the control unit 80, etc. The processing unit 22 can predict the amount of the target 12 based on the supply information and the state information.

[0097] The processing unit 22 can acquire state information of the holding surface 17 from a detection device other than a sensor, such as a camera 21. For example, the processing unit 22 can acquire state information of the holding surface 17 from the position of the target 12 detected by a position sensor. The position sensor detects the position of the end of the target 12. Therefore, the position sensor can detect at least one of the width and area of ​​the region occupied by the target 12 on the holding surface 17. The position sensor may include, for example, a displacement meter, a high-speed camera, a low-speed camera, a quadrant photodiode (PD), or a time delay integration (TDI) camera. The position sensor may be any one of one-dimensional measurement surface position, two-dimensional measurement surface position, three-dimensional measurement surface position, or a combination thereof. In this way, the acquisition unit 20 may include a displacement meter that outputs the displacement amount of the surface position of the target 12 covering the holding surface 17. The processing unit 22 can acquire the amount of the target 12 based on image information and displacement amount.

[0098] Furthermore, the processing unit 22 can simultaneously use the camera 21, a position sensor, etc. The processing unit 22 can use one of the camera 21 or the position sensor for auxiliary applications of the other. Specifically, the state information acquired by one of the camera 21 or the position sensor can be corrected by the other. For example, the processing unit 22 can acquire or predict the amount of the target 12 by combining the image information acquired by the position sensor and the camera 21.

[0099] In addition, the capturing unit 20 may include a photodetector that detects specific light from the discontinuity H3, and may acquire information about the presence or intensity of the specific light from the discontinuity H3 as status information.

[0100] FIG9 is a configuration diagram showing an example of the capturing unit 20 in the light source device 1 according to the first embodiment. As shown in FIG9, the capturing unit 20 may further include a plurality of cameras 21a and 21b, an illumination unit 23, lenses 24a to 24c, and mirrors 25a to 25c. It should be noted that the capturing unit 20 may further include optical elements other than those described above, or some of the optical elements may be omitted.

[0101] Illumination unit 23 generates and emits illumination light L1. Illumination light L1 emitted from illumination unit 23 illuminates, for example, target holding unit 10 via lens 24c, mirror 25c, mirror 32, and condenser lens 31. Camera 21a captures light L2 from a bright spot on plasma 11 via condenser lens 31, mirror 32, mirror 25a, and lens 24a. Camera 21b captures light L3 from holding surface 17 via condenser lens 31, mirror 32, mirror 25b, and lens 24b. Therefore, camera 21b acquires image information of holding surface 17.

[0102] The cameras 21, 21a, and 21b in the acquisition unit 20 can capture images of the holding surface 17 of the target holding unit 10 via the focusing lens 31 that focuses the excitation light LR. Therefore, the target material 12 at the position irradiated by the excitation light LR can be captured, thereby improving the accuracy of the target material 12. In addition, the holes formed in the debris cover 65 for the optical path of the excitation light LR and the holes for the camera 21 to acquire images can be shared, thereby reducing the number of holes formed in the debris cover 65. Therefore, the adverse effects of debris in the light source device 1 can be reduced.

[0103] The forming unit 30 may include optical elements. The optical elements include a condenser lens 31 that focuses the excitation light LR onto the target 12 and a mirror 32 that reflects the excitation light LR. The forming unit 30 excites the target 12 by focusing laser light onto the target 12 as the excitation light LR.

[0104] As shown in Figures 1 and 2, the forming unit 30 forms plasma 11 from the target material 12. When plasma 11 is formed, plasma 11 generates EUV light LE. For example, EUV light LE is used as light L0 for illumination, exposure, etc. in optical devices such as inspection devices, lithography devices, etc.

[0105] It should be noted that the optical elements in the forming unit 30 are not limited to the condenser lens 31 and the mirror 32, and may include a laser device that generates excitation light LR, as long as it irradiates the target material 12 with the excitation light LR. That is, the light source device 1 may include a laser device that generates excitation light LR. On the other hand, the light source device 1 may introduce excitation light LR from a laser device separately mounted outside the light source device 1 into the light source device 1. The excitation light LR can irradiate the target material 12 by means of the laser device under the control of the control unit 80.

[0106] The supply unit 40 supplies the target material 12 to the target holding unit 10. The supply unit 40 can supply the solid target material 12 to the target holding unit 10. The target material 12 may have a linear shape. The linear target material 12 may be held in a state of being wound on a spool or the like. The supply unit 40 supplies the linear target material 12 from the spool to the target holding unit 10.

[0107] The supply unit 40 can supply the molten target 12 to the holding surface 17. For example, the supply unit 40 can supply the molten target 12 to the holding surface 17 using a fragmentation shield 62. The fragmentation shield 62 is disposed near the supply unit 40 to cover the supply unit 40. The fragmentation shield 62 is exposed to a temperature higher than or equal to the melting point of the target 12. As described above, the fragmentation shield 62 can be set to a temperature higher than or equal to the melting point of the target 12 by means of the radiant heat of the target holding unit 10 and the target 12 in the target holding unit 10. The temperature of the fragmentation shield 62 can be adjusted to a temperature higher than or equal to the melting point of the target 12 by means of a heating element such as a heater.

[0108] The supply unit 40 can melt the solid target material 12q by contacting the fragmentation shield 62, etc., and then supply it to the target holding unit 10. For example, the target material 12 melted by the fragmentation shield 62 falls to the bottom surface 15 and reaches the inner peripheral surface 16 under the maximum effect of centrifugal force. Therefore, it is not necessary for the solid target material 12q to contact the target material 12 on the holding surface 17. Therefore, the temperature drop of the target material 12 on the holding surface 17 can be prevented. Interference with the surface state of the target material 12 due to vibration, etc. can be prevented.

[0109] The cover 60 includes debris covers 61, 62 and debris cover 65. It should be noted that the cover 60 does not necessarily include all of the debris covers 61, 62 and debris cover 65. The cover 60 may include at least one of the debris covers 61, 62 and debris cover 65.

[0110] The debris cover 65 is configured to cover the target holding unit 10. For example, the debris cover 65 covers the opening on the +Z axis side of the target holding unit 10. It should be noted that the debris cover 65 has an opening formed for extracting excitation light (LR) and EUV light (LE). The debris cover 65 prevents debris scattered during the formation of plasma 11 from adhering to the focusing lens, etc. The temperature of the debris cover 65 can be adjusted to a temperature higher than or equal to the melting point of the target material 12. Therefore, the debris can be remelted and reused as the target material 12.

[0111] The fragmentation cover 61 is configured to cover the location where the plasma 11 is formed. The fragmentation cover 62 is configured to cover the supply unit 40. The fragmentation cover 62 may include a portion disposed on a line extending from the rotation axis R of the target holding unit 10 to the holding surface 17. That is, the fragmentation cover 62 may include a moving radius portion. Therefore, the fragmentation cover 62 can supply the molten target material 12 to the holding surface 17 by centrifugal force. At least one of the fragmentation cover 61 and fragmentation cover 62 may be attached to the fragmentation cap 65.

[0112] The output optical system 70 extracts light L0 generated by the excitation light LR irradiating the target 12 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 condenser lens. It should be noted that the optical element 71 is not limited to a condenser lens, but may also be a second condenser lens (not shown) that further reflects the light L0 reflected by the condenser lens, as long as it is an optical element that extracts light L0 generated by the excitation light LR irradiating the target 12.

[0113] Optical element 71 reflects light L0 generated by the excitation light LR irradiation of the target 12. Optical element 71 may reflect, for example, EUV light LE generated by the excitation light LR irradiation. That is, light L0 may include EUV light LE. EUV light LE is generated by plasma 11 formed by irradiating the target 12 with excitation light LR. EUV light LE generated from plasma 11 and reflected by optical element 71 is emitted as illumination light and / or exposure light to optical devices such as inspection devices and / or lithography devices.

[0114] The control unit 80 can control each component of the light source device 1. The control unit 80 is connected to each component of the light source device 1 via communication lines including wireless and wired connections in a state capable of transmitting information. For example, the control unit 80 analyzes the state information of the target material 12 acquired by the acquisition unit 20. The control unit 80 analyzes the output information of the light L0, such as illumination light, output by the optical output system 70, including intensity, irradiation position, etc.

[0115] The control unit 80 controls the formation state of the plasma 11, including the intensity and illumination position of the excitation light LR at the forming unit 30, based on the status information of the target 12 and the output information of the light L0. The control unit 80 also controls the supply state of the target 12 at the supply unit 40, including the temperature and supply amount, based on the status information and output information. Finally, the control unit 80 controls the temperature of the cover 60, based on the status information and output information.

[0116] Next, the effectiveness of this embodiment will be described. In the light source device 1 according to this embodiment, the target holding unit 10 has a groove H1 with a cross-sectional shape, in which the width of the target 12 varies according to the amount of the target 12. The groove H1 includes a first region H11, a second region H12, and a third region H13 with different depths. Therefore, the capturing unit 20 can easily capture the amount of the target 12 based on the area occupied by the target 12 on the holding surface 17.

[0117] In addition, the processing unit obtains the amount of the target 12, thereby reducing the consumption of the target 12.

[0118] Furthermore, the amount of the target 12 is monitored and acquired by the acquisition unit 20, thereby allowing adjustment of the amount of the target 12. Therefore, for example, by increasing the amount of the target 12, the area occupied by the target 12 on the holding surface 17 can be expanded, and the liquid level change caused by the backflow of the target 12 can be reduced. Thus, the liquid level change caused by backflow can be reduced.

[0119] [Second Embodiment]

[0120] Next, the light source device 2 according to the second embodiment will be described. FIG10 is a cross-sectional view of an example of the light source device 2 according to the second embodiment, showing a cross section along line XX of FIG11. FIG11 is a cross-sectional view of an example of the light source device 2 according to the second embodiment, showing a cross section along line XI-XI of FIG10.

[0121] As shown in Figures 10 and 11, the light source device 2 includes a target holding unit 210, a capturing unit 220, and a processing unit 222. It should be noted that, in addition to the target holding unit 210, the capturing unit 220, and the processing unit 222, the light source device 2 may further include a driving unit DU, a forming unit 230, a supply unit 240, a cover 260, an output optical system 270, and a control unit 280.

[0122] The target holding unit 210 holds the target material 212. The target holding unit 210 includes a cylindrical (cylindrical) tube 213. The interior of the tube 213 is filled with a coolant 214 such as liquid nitrogen. The target holding unit 210 holds the target material 212 by fixing a solid (e.g., frozen xenon (Xe)) serving as the target material 212 to the outer peripheral surface 215 of the tube 213. In this embodiment, the holding surface 217 of the target holding unit 210 includes the outer peripheral surface 215 of the tube 213.

[0123] In this embodiment, the outer peripheral surface 215 of the cylinder 213, which serves as the holding surface 217, may include a groove H1. That is, in this embodiment, the holding surface 217 may also include a groove H1. For example, the groove H1 is formed along the intersection line of the outer peripheral surface 215 and the surface orthogonal to the rotation axis R. The groove H1 is a recess formed on the outer peripheral surface 215 in a direction close to the rotation axis R. When the outer peripheral surface 215 has the groove H1, the target material 212 can be held in the groove H1.

[0124] FIG12 is a cross-sectional view showing an example of the groove H1 of the target holding unit 210 in the light source device 2 according to the second embodiment. As shown in FIG12, in this embodiment, the groove H1 may also include a first region H11, a second region H12, and a third region H13. Therefore, the holding surface 217 may include the first region H11, the second region H12, and the third region H13. Therefore, the first region H11, the second region H12, and the third region H13 are formed on the outer peripheral surface 215 of the cylinder 213. Each part of the first region H11, the second region H12, and the third region H13 in the groove H1 may have different depths from each other. It should be noted that each part of the first region H11, the second region H12, and the third region H13 may be disposed at different depths relative to the cylindrical surface H0 on which the groove H1 is formed in the direction close to the rotation axis R.

[0125] As described above, when the distance from the cylindrical surface H0 on which the groove H1 is formed to the rotation axis R is defined as the reference distance, the absolute value of the difference between the reference distance and the distance from each part of the first region H11, the second region H12, and the third region H13 to the rotation axis R is called the depth. Furthermore, the depth of each part of the first region H11, the second region H12, and the third region H13 is also the distance from a predetermined surface to each part in a direction orthogonal to the surface of the target material 12. In this embodiment, the depth is the length obtained by subtracting the reference distance from the distance between each part of the first region H11, the second region H12, and the third region H13 and the rotation axis R. In this embodiment, the distance from the rotation axis R to the first region H11 is shorter than the distance from the rotation axis R to the second region H12. The distance to the second region H12 is shorter than the distance to the third region H13. Furthermore, the distance to the third region H13 is shorter than the distance to the cylindrical surface H0, which may be the region furthest from the rotation axis R.

[0126] FIG13 is a side view showing an example of another groove H1 in the target holding unit 210 of the light source device 2 according to the second embodiment. FIG14 is a perspective view showing an example of another groove H1 in the target holding unit 210 of the light source device 2 according to the second embodiment. As shown in FIG13, in this embodiment, the first region H11 and the second region H12 may each include a portion extending about the rotation axis R along the rotation direction. The holding surface 217 may include a plurality of grooves H1. The plurality of grooves H1 are aligned in the direction of the rotation axis R. There is a protrusion H4 between the grooves H1, where the inclined surfaces of the grooves H1 on both sides are connected together. Therefore, the cross section along the rotation axis R on the side surface of the cylinder 213 is serrated.

[0127] Each groove H1 includes a first region H11. A second region H12 is disposed between the first regions H11 that are perpendicularly adjacent to each other. Therefore, the second region H12 of the cylinder 213 can form the aforementioned protrusion H4. When the protrusion H4, which is the second region H12, protrudes to the surface of the target material 212, the target material 212 is held in the first region H11, rather than in the second region H12. In this case, the amount of the target material 212 is a first amount 12a. When the protrusion H4 is covered by and hidden by the target material 212, the target material 212 is held in both the first region H11 and the second region H12. Therefore, in this case, the amount of the target material 212 is a second amount 12b.

[0128] For example, when the target 212 is held in the first region H11 instead of in the second region H12, the supply amount of gas 242 to the target 212 by the supply unit 240 increases. Therefore, the exposure of the protrusion H4 of the serrated top can be reduced.

[0129] As shown in Figure 14, the first region H11 and the second region H12 may each have a portion extending in the direction of the rotation axis R. The retaining surface 217 may include a plurality of grooves H1. The plurality of grooves H1 are aligned in the rotation direction of the rotation axis R. There is a protrusion H4 between the grooves H1, where the inclined surfaces of the grooves H1 on both sides are connected together. Therefore, the cross section orthogonal to the rotation axis R on the side surface of the cylinder 213 is serrated.

[0130] Each groove H1 includes a first region H11. A second region H12 is disposed between the first regions H11 that are perpendicularly adjacent to each other in the rotational direction. Therefore, the second region H12 of the cylinder 213 can form the aforementioned protrusion H4. When the protrusion H4, which is the second region H12, protrudes to the surface of the target material 212, the target material 212 is held in the first region H11, rather than in the second region H12. In this case, the amount of the target material 212 is a first amount 12a. When the protrusion H4 is covered by and hidden by the target material 212, the target material 212 is held in both the first region H11 and the second region H12. Therefore, in this case, the amount of the target material 212 is a second amount 12b.

[0131] For example, when the target 212 is held in the first region H11 instead of the second region H12, the target 212 is disposed in a dispersed manner on the outer peripheral surface 215 of the cylinder 213 in the rotational direction of the rotation axis R. In this case, the supply amount of gas 242 to the target 212 by the supply unit 240 is increased. Alternatively, the emission mode of the excitation light LR is such that the rotation period of the first region H11 through the irradiation position is synchronized with the emission period of the excitation light LR, so that the target 212 in the first region H11 is irradiated by the excitation light LR.

[0132] The drive unit DU drives the target holding unit 210 to move the holding surface 217. The drive unit DU causes the target holding unit 210 to rotate about the rotation axis R.

[0133] The capturing unit 220 is disposed on the +Y axis direction side of the target holding unit 210. The capturing unit 220 acquires state information of the holding surface 217 of the target holding unit 210. For example, the capturing unit 220 may include a camera 221. The capturing unit 220 acquires image information of the holding surface 217 captured by the camera 221 as state information of the holding surface 217 of the target holding unit 210. The camera 221 captures an image of the holding surface 217 of the target holding unit 210 via a condenser lens 231.

[0134] The forming unit 230 is disposed on the +Y axis direction side of the target holding unit 210. The forming unit 230 irradiates the target material 212 held on the holding surface 217 on the +Y axis direction side of the target holding unit 210 with an excitation light LR that moves in the -Y axis direction. The forming unit 230 focuses the excitation light LR via a condenser lens 231.

[0135] A 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. The supply port 241 is connected to a supply source 243 for gas 242 of the target material 212. The supply source 243 supplies gas 242 of the target material 212 to the holding surface 217 through the supply port 241. The gas 242 of the target material 212 supplied through the supply port 241 is fixed on the surface of the cylinder 213, thereby forming the target material 212.

[0136] The cover portion 260 includes debris covers 261 and 262. The debris cover 261 is configured to cover the holding surface 217 between the location where the plasma 11 is formed and the supply port 241. The debris cover 262 is configured to cover the holding surface 217 between the supply port 241 and the location where the plasma 11 is formed. The output optical system 270 extracts light L0, such as EUV light (LE), through the optical element 271.

[0137] Similarly, even if the solid target 212 is held in a target holding unit 210 such as a cylindrical tube 213, the same effect as the first embodiment can be obtained.

[0138] Next, the control methods for the light source devices 1 and 2 will be described. FIG15 is a flowchart showing examples of the control methods for the light source devices 1 and 2 according to the first embodiment and the second embodiment. As shown in FIG15, the control methods for the light source devices 1 and 2 include an acquisition step S11 and a processing step S12. Although the symbols used in the light source device 1 will be used in the following description, the same symbols will also be used in the light source device 2.

[0139] In step S11, state information of the holding surface 17 of the target holding unit 10, which holds the holding surface 17 of the target material 12 used for generating light, is acquired. Specifically, the capturing unit 20 acquires the state information. For example, the capturing step S11 may include image information of the holding surface 17 captured by the camera 21 as state information.

[0140] In step S12, the amount of the target material 12 is obtained based on the state information. Specifically, the processing unit 22 obtains the amount of the target material 12 based on the state information. For example, processing step S12 includes obtaining the amount of the target material 12 based on the area occupied by the target material 12 on the holding surface 17 in the state information. In addition, processing step S12 may include obtaining the amount of the target material 12 based on the area occupied by the target material 12 on the holding surface 17 identified in the image information. In addition, processing step S12 may include obtaining the amount of the target material 12 based on the presence or absence of specific light in the discontinuity H3 identified in the image information. In addition, processing step S12 may include obtaining the amount of the target material 12 based on the presence or absence of specific light in the second region H12. Therefore, the light source device 1 can be controlled.

[0141] Therefore, embodiments of the present invention have been described above. However, the present invention is covered by suitable modifications that do not impair the purpose and advantages of the present invention. Furthermore, the present invention is not limited to the above embodiments. The configurations and components of the first and second embodiments, as well as modified examples, can be appropriately combined with each other.

[0142] Control unit 80 may include processing unit 22. Processing unit 22 may include control unit 80. Control unit 280 may include processing unit 222. Processing unit 222 may include control unit 80. The processing unit (processing unit 22 or processing unit 222) may be, for example, an information processing device such as a server or personal computer. The processing unit may further include one or more processors, memory, storage devices, and a user interface. The storage device stores the processing to be performed by each configuration of the processing unit in the form of a program. In addition, the processor reads the program from the storage device into memory and executes the program. The processing unit may be configured to execute program instructions to cause one or more processors to acquire the amount of target material based on status information. In this way, the processor implements the function of each configuration in the processing unit. The user interface may include input devices such as a keyboard, mouse, and image acquisition device, and output devices such as a display, printer, and speaker.

[0143] Each configuration included in the processing unit can be implemented through dedicated hardware. Furthermore, some or all of the components can be implemented by general-purpose or special-purpose circuits, processors, or combinations thereof. These can be configured as a single chip or as multiple chips connected via buses. Some or all of the components can be implemented by a combination of the aforementioned circuits and programs. Furthermore, a central processing unit (CPU), a graphics processing unit (GPU), a field-programmable gate array (FPGA), a quantum processor (quantum computer control chip), etc., can be used as the processor.

[0144] Those skilled in the art can combine the first and second embodiments according to their needs.

[0145] As will be apparent from the invention described herein, many variations are possible in the embodiments of the invention. Such variations should not be considered as departing from the spirit and scope of the invention, and all such modifications that are obvious to those skilled in the art are intended to be included within the scope of the following claims. The following configurations are also covered in the technical concept of the embodiments.

[0146] (Supplementary Explanation 1) A control method for a light source device, the method comprising: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; and the processing step comprises acquiring the amount of the target material based on the region of the holding surface occupied by the target material in the state information.

[0147] (Supplementary Explanation 2) A light source device includes: a target holding unit having a holding surface for holding a target material for generating light; an acquisition unit including a camera and acquiring image information of the holding surface captured by the camera; and a processing unit configured to acquire an amount of the target material based on the image information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; and the processing unit acquires the amount of the target material based on the region of the holding surface occupied by the target material identified in the image information.

[0148] (Supplementary Explanation 3) A control method for a light source device, the method comprising: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; the acquisition step includes acquiring image information of the holding surface captured by a camera as the state information; and the processing step includes acquiring the amount of the target material based on the area of ​​the holding surface occupied by the target material identified in the image information.

[0149] (Supplementary Explanation 4) A control method for a light source device, the method comprising: an acquisition step of acquiring state information of the holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; the holding surface includes a discontinuity between the first region and the second region; when the amount of the target material is the first amount, the discontinuity is not covered by the target material; when the amount of the target material is the second amount, the discontinuity is covered by the target material. The acquisition step includes acquiring image information of the holding surface captured by the camera as the state information; and the processing step includes acquiring the amount of the target material based on the presence or absence of specific light in the discontinuity identified in the image information.

[0150] (Supplementary Explanation 5) A control method for a light source device, the method comprising: an acquisition step of acquiring state information of a holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step of acquiring an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; the second region has a protruding tip; the acquisition step includes acquiring image information of the holding surface captured by a camera as the state information; and the processing step includes acquiring the amount of the target material based on the presence or absence of a specific light in the second region identified in the image information.

[0151] (Supplementary Explanation 6) A light source device includes: a target holding unit having a holding surface for holding a target material for generating light; an acquisition unit configured to acquire state information of the holding surface; and a processing unit including one or more processors configured to execute program instructions to acquire an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; and the processing unit acquires the amount of the target material based on the area of ​​the holding surface occupied by the target material in the acquired state information.

[0152] (Supplementary Explanation 7) A control method for a light source device, wherein one or more processors execute a program stored in memory, the method comprising: a retrieving step, wherein a retrieving unit acquires state information of the holding surface of a target holding unit having a holding surface for holding a target material for generating light; and a processing step, wherein the one or more processors acquire an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; and the processing step comprises acquiring the amount of the target material based on the region of the holding surface occupied by the target material in the state information. [Simplified Explanation of the Diagram]

[0030] FIG1 is a cross-sectional view showing an example of a light source device according to the first embodiment, and shows a section along line II of FIG2;

[0031] FIG2 is a cross-sectional view showing an example of a light source device according to the first embodiment, and shows a section along line II-II of FIG1;

[0032] FIG3 is a cross-sectional view showing an example of the groove of the target holding unit in the light source device according to the first embodiment;

[0033] FIG4 is a cross-sectional view showing an example of another recess in the target holding unit of the light source device according to the first embodiment;

[0034] FIG5 is a cross-sectional view showing an example of another recess in the target holding unit of the light source device according to the first embodiment;

[0035] FIG6 is a cross-sectional view showing an example of another recess in the target holding unit of the light source device according to the first embodiment;

[0036] FIG7 is a diagram showing an example of another recess in the target holding unit of the light source device according to the first embodiment;

[0037] FIG8 is a cross-sectional view showing an example of another recess in the target holding unit of the light source device according to the first embodiment;

[0038] FIG9 is a configuration diagram showing an example of the capturing unit in the light source device according to the first embodiment;

[0039] FIG10 is a cross-sectional view of an example of a light source device according to the second embodiment, and shows a cross section along line XX in FIG11;

[0040] FIG11 is a cross-sectional view of an example of a light source device according to the second embodiment, and shows a cross section along line XI-XI of FIG10;

[0041] FIG12 is a cross-sectional view showing an example of the groove of the target holding unit in the light source device according to the second embodiment;

[0042] FIG13 is a side view showing an example of another recess of the target holding unit in the light source device according to the second embodiment;

[0043] FIG14 is a perspective view showing an example of another recess in the target holding unit of the light source device according to the second embodiment; and

[0044] Figure 15 is a flowchart illustrating an example of a control method for a light source device according to the first embodiment and the second embodiment.

Claims

1. A light source device, comprising: A target holding unit having a holding surface for holding a target material for generating light; an acquisition unit configured to acquire state information of the holding surface; and a processing unit configured to acquire an amount of the target material based on the state information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; and the processing unit acquires the amount of the target material based on the area of ​​the holding surface occupied by the target material in the acquired state information.

2. The light source device as described in claim 1, wherein, The holding surface further includes a third region, the second region being at a greater depth than the third region being at a greater depth than the predetermined surface, and the target being held in the first region, the second region, and the third region when the amount of the target is a third amount greater than the second amount.

3. The light source device as described in claim 1, wherein, The processing unit obtains the amount of the target material based on at least one of the width and area of ​​the region of the target material covering the retaining surface.

4. The light source device as described in claim 1, wherein, The capturing unit includes a camera, which acquires image information of the holding surface captured by the camera as the state information of the holding surface, and the processing unit acquires the amount of the target material based on the area of ​​the target material occupying the holding surface identified in the image information.

5. The light source device as described in claim 4 further comprises: The forming unit includes a condenser lens that focuses excitation light transmitted through the target to form plasma onto the target, and a camera that captures images of the holding surface via the condenser lens.

6. The light source device as described in claim 4, wherein, The acquisition unit further includes a displacement meter, which outputs the displacement amount of the surface position of the target material covering the holding surface, and the processing unit acquires the amount of the target material based on the image information and the displacement amount.

7. The light source apparatus as described in claim 1, wherein, The retaining surface includes a discontinuity between the first region and the second region. When the amount of the target material is the first amount, the discontinuity is not covered by the target material, and when the amount of the target material is the second amount, the discontinuity is covered by the target material.

8. The light source device as described in claim 7, wherein, The discontinuity is formed at the corner where the plane containing the retaining surface of the first region and the plane containing the retaining surface of the second region are joined together.

9. The light source apparatus as described in claim 1, wherein, The target holding unit includes a crucible that rotates about a rotation axis, and the first region and the second region formed on the inner circumferential surface of the crucible.

10. The light source device as described in claim 9, wherein, The first region and the second region each include a portion extending about the rotation axis along the rotation direction.

11. The light source device as described in claim 9, wherein, The first region and the second region each include a portion extending along the direction of the rotation axis.

12. The light source apparatus as described in claim 1, wherein, The target holding unit includes a cylinder that rotates about a rotation axis, and the first region and the second region are formed on the outer peripheral surface of the cylinder.

13. The light source device as described in claim 12, wherein, The first region and the second region each include a portion extending about the rotation axis along the rotation direction.

14. The light source apparatus as described in claim 12, wherein, The first region and the second region each include a portion extending along the direction of the rotation axis.

15. A light source device, comprising: A target holding unit has a holding surface for holding a target material for generating light; an acquisition unit includes a camera and acquires image information of the holding surface captured by the camera; and a processing unit configured to acquire an amount of the target material based on the image information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; the holding surface includes a discontinuity between the first region and the second region; when the amount of the target material is the first amount, the discontinuity is not covered by the target material; when the amount of the target material is the second amount, the discontinuity is covered by the target material; and the processing unit acquires the amount of the target material based on the presence or absence of specific light in the discontinuity identified in the image information.

16. A light source device, comprising: A target holding unit having a holding surface for holding a target material for generating light; an acquisition unit including a camera and acquiring image information of the holding surface captured by the camera; and a processing unit configured to acquire an amount of the target material based on the image information; wherein the holding surface includes a first region and a second region; the depth of the first region from a predetermined surface is greater than the depth of the second region from the predetermined surface; when the amount of the target material is a first amount, the target material is held in the first region; when the amount of the target material is a second amount greater than the first amount, the target material is held in both the first region and the second region; the second region has a protruding tip; and the processing unit acquires the amount of the target material based on the presence or absence of specific light in the second region identified in the image information.

Images