Position detection device and position detection method

Abstract

To provide a position detection device and a position detection method which can detect a position of plasma in a target.SOLUTION: A position detection device 1 includes: a visible light optical system 30 for condensing visible light V1 which is generated together with EUV light E1 from plasma 27 generated by condensing laser light L1 on a target 12 with a condensing lens 31; a position detection sensor 40 for detecting the visible light V1 condensed by the visible light optical system 30; and a position detection processing unit 50 for detecting a change of a position of the plasma 27 on the target 12 from a change of a spot of the visible light V1 detected by the position detection sensor 40.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a position detection device and a position detection method for plasma generated in a target by irradiating it with laser light, for example, in an EUV (Extreme Ultra Violet) light source. [Background technology]

[0002] Patent Documents 1 to 3 describe a light source that irradiates a target such as tin (Sn) with an IR (Infra Red) laser beam to excite the target and generate plasma that emits EUV light. The EUV light extracted from the light source is used in an inspection device, an exposure device, etc. for semiconductor substrates. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2021-001924 A [Patent Document 2] JP 2014-086523 A [Patent Document 3] JP 2011-003887 A Summary of the Invention [Problem to be solved by the invention]

[0004] When a target is irradiated with IR laser light, if the target position changes, the optical axis of the generated EUV light changes, and the optical axis of the EUV light extracted to the equipment side such as the inspection equipment and exposure equipment also changes. In order to stabilize the optical axis of the EUV light, it is necessary to detect the change in the target position.

[0005] The object of the present disclosure has been made to solve such problems, and is to provide a position detection device and a position detection method capable of detecting the position of plasma in a target. [Means for solving the problem]

[0006] The position detection device of the present disclosure includes a visible light optical system that collects visible light generated together with EUV light from plasma generated by focusing laser light on a target with a focusing lens, a position detection sensor that detects the visible light collected by the visible light optical system, and a position detection processing unit that detects a change in the position of the plasma on the target from a change in the spot of visible light detected by the position detection sensor.

[0007] In the above-mentioned position detection device, the position detection processing unit may calculate a change in the optical axis of the EUV light optical system for correcting the optical axis of the EUV light optical system that collects the EUV light, based on a change in the detected position of the plasma.

[0008] In the above-mentioned position detection device, the position detection processing unit may detect a change in the position of the plasma in the optical axis direction of the focusing lens, and a change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens, from the position of the visible light spot detected by the position detection sensor.

[0009] In the above position detection device, the position detection processing unit may detect a change in the position of the plasma in the optical axis direction of the focusing lens from a size of the spot of the visible light detected by the position detection sensor.

[0010] The above-mentioned position detection device may further include a shielding plate disposed between the position detection sensor and the visible light optical system, shielding a central portion including the optical axis of the focusing lens in the cross section of the visible light from the position detection sensor, and the position detection processing unit may detect a change in the position of the plasma in the optical axis direction of the focusing lens from the size of the annular spot detected by the position detection sensor.

[0011] In the above-mentioned position detection device, the position detection processing unit may detect a change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens from the position of the annular spot detected by the position detection sensor.

[0012] In the above-mentioned position detection device, the shielding plate may have a mirror that reflects the central portion and may further include another position detection sensor that detects the central portion, and the position detection processing unit may detect a change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens from the position of the spot detected by the other position detection sensor.

[0013] In the above position detection device, the position detection processing unit may calculate a change in the optical axis of the laser light for correcting the optical axis of the laser light, based on a change in the detected position of the plasma.

[0014] The position detection method according to the present disclosure includes the steps of: focusing visible light generated together with EUV light from plasma generated by focusing laser light on a target with a focusing lens using a visible light optical system; detecting the visible light focused by the visible light optical system with a position detection sensor; and detecting a change in the position of the plasma on the target from a change in the spot of visible light detected by the position detection sensor with a position detection processing unit.

[0015] The above-mentioned position detection method may further include a step of calculating a change in the optical axis of the EUV light optical system for correcting the optical axis of the EUV light optical system that collects the EUV light, based on a change in the position of the plasma detected by the position detection processing unit.

[0016] In the position detection method, in the step of detecting by the position detection processing unit, A change in position of the plasma in the optical axis direction of the focusing lens and a change in position of the plasma in a direction perpendicular to the optical axis of the focusing lens may be detected from the position of the visible light spot detected by the position detection sensor.

[0017] In the position detection method, in the step of detecting by the position detection processing unit, A change in the position of the plasma in the optical axis direction of the focusing lens may be detected from the size of the spot of the visible light detected by the position detection sensor.

[0018] The above-mentioned position detection method further includes a step of shielding a central portion including the optical axis of the focusing lens in the cross section of the visible light with a shielding plate disposed between the position detection sensor and the visible light optical system, from the position detection sensor, and in the step of detection by the position detection processing unit, a change in the position of the plasma in the optical axis direction of the focusing lens may be detected from the size of the annular spot detected by the position detection sensor.

[0019] In the position detection method, in the step of detecting by the position detection processing unit, A change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens may be detected from the position of the annular spot detected by the position detection sensor.

[0020] In the above-mentioned position detection method, the shielding plate has a mirror that reflects the central portion, and the method further includes a step of detecting the central portion by another position detection sensor, and in the step of detecting by the position detection processing unit, a change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens may be detected from the position of the spot detected by the other position detection sensor.

[0021] The above position detection method may further include a step of calculating a change in the optical axis of the laser light to correct the optical axis of the laser light, based on a change in the position of the plasma detected by the position detection processing unit. Effect of the Invention

[0022] According to the present invention, it is possible to provide a position detection device and a position detection method capable of detecting the position of plasma in a target. [Brief description of the drawings]

[0023] [Figure 1] 1 is a cross-sectional view illustrating a light source according to a first embodiment. [Diagram 2] FIG. 2 is a perspective view illustrating a container of the light source according to the first embodiment. [Diagram 3] 1 is a configuration diagram illustrating a position detection device according to a first embodiment. [Figure 4] 4 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in the Z-axis direction in the position detection device according to the first embodiment. FIG. [Diagram 5] 4 is a diagram illustrating an example of a visible light spot detected by a position detection sensor before and after a change in the position of plasma on a target in the position detection device according to the first embodiment. FIG. [Figure 6] 4 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in at least one of the X-axis direction and the Y-axis direction in the position detection device according to the first embodiment. FIG. [Figure 7] 2 is a block diagram illustrating a position detection processing unit in the position detection device according to the first embodiment. [Figure 8] FIG. 2 is a flowchart illustrating a position detection method according to the first embodiment. [Figure 9] FIG. 11 is a configuration diagram illustrating a position detection device according to a second embodiment. [Figure 10] 11 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in the Z-axis direction in the position detection device according to the second embodiment. FIG. [Figure 11] 13 is a diagram illustrating an example of a visible light spot detected by a position detection sensor before and after a change in the position of plasma on a target in the position detection device according to the second embodiment. FIG. [Figure 12]11 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in at least one of the X-axis direction and the Y-axis direction in the position detection device according to the second embodiment. FIG. [Figure 13] FIG. 11 is a configuration diagram illustrating a position detection device according to a third embodiment. [Figure 14] FIG. 11 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in the Z-axis direction in the position detection device according to the third embodiment. [Figure 15] 13 is a diagram illustrating an example of a visible light spot detected by a position detection sensor before and after a change in the position of plasma on a target in the position detection device according to the third embodiment. FIG. [Figure 16] FIG. 11 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in at least one of the X-axis direction and the Y-axis direction in a position detection device according to a third embodiment. [Figure 17] 13 is a diagram illustrating an example of a spot of visible light detected by a position detection sensor when a shielding plate is present in the position detection device according to the third embodiment. FIG. [Figure 18] 13 is a diagram illustrating a spot of visible light detected by a position detection sensor in the position detection device according to the third embodiment when there is no shielding plate. FIG. [Figure 19] FIG. 11 is a configuration diagram illustrating a position detection device according to a fourth embodiment. [Figure 20] 13 is a configuration diagram illustrating an example of visible light when the position of plasma in a target changes in the Z-axis direction in a position detection device according to embodiment 4. FIG. [Figure 21] 13 is a diagram illustrating an example of a visible light spot detected by a position detection sensor before and after a change in the position of plasma on a target in a position detection device according to embodiment 4. FIG. [Figure 22] 13 is a configuration diagram illustrating an example of visible light V1 when the position of plasma in a target changes in at least one of the X-axis direction and the Y-axis direction in a position detection device according to a fourth embodiment. FIG. [Diagram 23]FIG. 13 is a configuration diagram illustrating a position detection device according to a fifth embodiment. [Figure 24] FIG. 13 is a diagram illustrating an example of a spot of visible light V1 detected by a position detection sensor before and after a change in the position of plasma in a target due to a change in the pointing of a laser beam in a position detection device of embodiment 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0024] Hereinafter, a specific configuration of the present embodiment will be described with reference to the drawings. The following description shows a preferred embodiment of the present disclosure, and the scope of the present disclosure is not limited to the following embodiment. In the following description, parts with the same reference numerals indicate substantially the same contents.

[0025] (Embodiment 1) A position detection device according to a first embodiment will be described. The position detection device of this embodiment detects the position of a target of a light source that generates EUV light, for example. The light source excites a target such as tin by irradiating the target with laser light including IR light, and generates EUV light from the generated plasma. The light source is, for example, a light source of illumination light that illuminates an inspection object in an inspection device. The light source may also be used as a light source of exposure light in an exposure device. As an example of a light source, an example in which a molten metal held in a container is used as a target will be described. Note that the light source is not limited to a light source that uses a molten metal held in a container as a target, and may be a light source that uses a solid metal, liquid droplets, or the like that generates plasma by irradiation with laser light. In the following, first, the <light source> will be described, and then the <configuration of the position detection device> will be described.

[0026] <Light source> FIG. 1 is a cross-sectional view illustrating a light source according to the first embodiment. FIG. 2 is a perspective view illustrating a container of the light source according to the first embodiment. As shown in FIGS. 1 and 2, the light source 10 includes a container 11. The container 11 is, for example, a crucible, and can melt metal inside. The container 11 holds a target 12 such as a molten metal that generates plasma by irradiation with a laser beam L1. The target 12 is, for example, a molten metal held in the container 11. Note that the target 12 is not limited to the molten metal held in the container 11, but may be a solid metal, liquid droplets, or the like, as long as it is a substance that generates plasma by irradiation with a laser beam L1. The molten metal is, for example, tin (Sn) or lithium (Li) melted, but is not limited to tin or lithium, as long as it generates plasma by irradiation with a laser beam L1.

[0027] The container 11 has a rotation axis R1 and rotates around the rotation axis R1. The container 11 is, for example, cylindrical with one opening closed. The closed part of the container 11 is called the bottom 13. The cylindrical part of the container 11 is called the cylindrical part 14. The rotation axis R1 of the container 11 extends, for example, in the vertical direction. The inner surface of the bottom 13 is called the bottom surface 15. The inner surface of the cylindrical part 14 is called the inner circumferential surface 16. A groove 17 may be formed at the joint between the bottom 13 and the cylindrical part 14.

[0028] The inner circumferential surface 16 formed to surround the rotation axis R1 may include a cylindrical portion with a constant distance from the rotation axis R1, or may include a cone-shaped portion that expands outward as it approaches the upper part. For example, the cone-shaped portion of the inner circumferential surface 16 is connected to the groove 17.

[0029] The light source 10 may include a heater 18, a mirror 19, a debris shield 20, and a concave mirror 21 in addition to the container 11. A target 12 such as molten metal can be formed in the container 11 by heating with the heater 18. The mirror 19 reflects the generated EUV light E1. The EUV light E1 is generated from plasma generated by irradiating the target 12 with a laser beam L1. The debris shield 20 is disposed in an opening 22 so as to cover the target 12. The concave mirror 21 reflects the EUV light E1 reflected by the mirror 19, and guides the EUV light E1 to a device such as an inspection device.

[0030] The light source 10 may include an excitation laser that generates the laser light L1, or may introduce the laser light L1 from an excitation laser installed outside the light source 10 to irradiate the target 12. The laser light L1 is, for example, an IR laser light. The laser light L1 is focused by a focusing lens 31 and irradiates the target 12.

[0031] <Configuration of position detection device> Next, a position detection device of this embodiment will be described. Fig. 3 is a configuration diagram illustrating a position detection device according to embodiment 1. As shown in Fig. 3, the position detection device 1 includes a visible light optical system 30, a position detection sensor 40, and a position detection processing unit 50.

[0032] The laser light L1 is incident on the condenser lens 31 via, for example, mirrors 23 to 26. The condenser lens 31 condenses the laser light L1 on the target 12. The target 12 is excited by irradiation with the laser light L1. This causes the target 12 to generate plasma 27 and generate EUV light E1. The generated EUV light E1 is extracted to the side of an apparatus such as an inspection apparatus. Visible light V1 is also generated from the plasma 27 together with the EUV light E1. In this way, visible light V1 is generated together with the EUV light E1 from the plasma 27 generated by condensing the laser light L1 on the target 12 with the condenser lens 31.

[0033] Here, an XYZ orthogonal coordinate system is introduced for the convenience of explanation of the position detection device 1. For example, the optical axis of the focusing lens 31 that focuses the laser light L1 on the target 12 is defined as the Z-axis direction, and two directions perpendicular to the optical axis of the focusing lens 31 are defined as the X-axis direction and the Y-axis direction.

[0034] The visible light optical system 30 collects the visible light V1 generated together with the EUV light E1. The visible light optical system 30 includes a collecting lens 31 and a lens 32. The visible light optical system 30 may include optical members other than these. The collecting lens 31 is disposed at a position facing the target 12. For example, the collecting lens 31 is disposed in the +Z axis direction of the target 12. The collecting lens 31 collects the visible light V1 generated from the target 12. The collecting lens 31 may also be used as a lens that collects the laser light L1 and irradiates the target 12. In this case, the collecting lens 31 collects the laser light L1 on the target 12 and transmits the visible light V1 generated by irradiating the laser light L1.

[0035] The laser light L1 passes through a central portion of the collecting lens 31, which includes the optical axis, and is collected on the target 12. Visible light V1 generated from the plasma 27 in the target 12 passes through a peripheral portion of the collecting lens 31, which does not include the optical axis. The visible light V1 that has passed through the collecting lens 31 is incident on the lens 32. The lens 32 collects the visible light V1 on the position detection sensor 40.

[0036] The position detection sensor 40 detects the visible light V1 collected by the visible light optical system 30. The position detection sensor 40 may detect the spot of the visible light V1 as an image. The position detection sensor 40 outputs information such as the image of the spot of the detected visible light V1 to the position detection processing unit 50. The position detection processing unit 50 detects a change in the position of the plasma 27 on the target 12 from a change in the spot of the visible light V1 detected by the position detection sensor 40.

[0037] <Visible light V1 passes through the peripheral part of the condenser lens 31. Change in position in the Z-axis direction> 4 is a configuration diagram illustrating visible light V1 when the position of plasma 27 in target 12 changes in the Z-axis direction in the position detection device 1 according to the first embodiment. As shown in FIG. 4, for example, when the position of target 12 changes in the Z-axis direction, the position of plasma 27 generated in target 12 also changes in the Z-axis direction. This changes the optical axis of EUV light E1 generated from plasma 27, and the optical axis of EUV light E1 in an apparatus such as an inspection apparatus. This causes a malfunction in the apparatus such as an inspection apparatus.

[0038] When the position of plasma 27 generated in target 12 changes, the optical axis of visible light V1 also changes. Visible light optical system 30 has a configuration for extracting the generated visible light V1 and detecting a change in the position of target 12 using an optical lever method. Specifically, visible light V1 passes through the peripheral portion of condenser lens 31 and is condensed by lens 32 onto position detection sensor 40. Position detection sensor 40 detects visible light V1 as a spot.

[0039] 5 is a diagram illustrating a spot of visible light V1 detected by the position detection sensor 40 before and after a change in the position of the plasma 27 on the target 12 in the position detection device 1 according to the first embodiment. In FIG. 5, NO.1-A shows a change ΔZ in the position of the plasma 27 in the Z-axis direction equal to or less than the focal depth D of the condenser lens 31, and NO.1-B shows a change ΔZ in the position of the plasma 27 in the Z-axis direction greater than the focal depth D of the condenser lens 31. NO.1-C shows a change ΔXΔY in the position of the plasma 27 in at least one of the X-axis and Y-axis directions, and NO.1-D shows a change ΔZ in the position of the plasma 27 in the Z-axis direction equal to or less than the focal depth D of the condenser lens 31, and a change ΔXΔY in the position of the plasma 27 in at least one of the X-axis and Y-axis directions. NO.1-E shows a change ΔZ in the position of the plasma 27 in the Z-axis direction greater than the focal depth D of the condenser lens 31, and a change ΔXΔY in the position of the plasma 27 in at least one of the X-axis and Y-axis directions.

[0040] As shown in No. 1-A and No. 1-B, in this embodiment, the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is detected by the position detection sensor 40 in different states depending on the relationship with the focal depth D.

[0041] First, as shown in No. 1-A of FIG. 5, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is equal to or less than the focal depth D, the change ΔZ in position does not affect the size of the spot of the visible light V1, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot does not change. However, the visible light V1 passes through the peripheral portion of the focusing lens 31. Therefore, the position detection sensor 40 detects the change ΔZ in the position in the Z-axis direction as a change in the position of the spot of the visible light V1.

[0042] Next, as shown in No. 1-B of FIG. 5, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is larger than the focal depth D, the change ΔZ in position affects the size of the spot, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot changes. Also, the visible light V1 passes through the peripheral portion of the condenser lens 31. Therefore, the position detection sensor 40 detects the change ΔZ in position in the Z-axis direction as a change in the position of the spot of the visible light V1.

[0043] In this way, when visible light V1 is transmitted through the peripheral portion of collecting lens 31, position detection sensor 40 detects change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in position of the spot of visible light V1, regardless of focal depth D. Furthermore, when change ΔZ in position in the Z-axis direction is larger than focal depth D, position detection sensor 40 detects change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in size of the spot of visible light V1.

[0044] <Visible light passes through the peripheral part of the lens. Change in position in the X and Y directions> Fig. 6 is a configuration diagram illustrating visible light V1 when the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction in the position detection device 1 according to the first embodiment. As shown in Fig. 6, for example, when the pointing of laser light L1, that is, the focusing position of laser light L1, changes, the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction. Position detection sensor 40 detects the change ΔXΔY in the position of plasma 27 in the X-axis direction and the Y-axis direction as a change in the position of the spot of visible light V1.

[0045] 5, the position detection sensor 40 detects a change ΔXΔY in at least one of the position of the plasma 27 in the target 12 in the X-axis direction and the Y-axis direction as a change in the position of the spot of the visible light V1. It is difficult for the position detection sensor 40 to detect the change ΔXΔY in position as a change in the size of the spot of the visible light V1.

[0046] <Visible light passes through the peripheral part of the lens. Position changes in the X, Y and Z directions> 5, when the change in position ΔZ of the plasma 27 in the target 12 in the Z-axis direction is equal to or smaller than the focal depth D, it is difficult for the position detection sensor 40 to detect the change in position ΔZ as a change in the size of the spot. In contrast, when the change in position ΔZ is larger than the focal depth D, the position detection sensor 40 detects the change in position ΔZ as a change in the size of the spot.

[0047] On the other hand, as shown in No. 1-D and No. 1-E, the position detection sensor 40 detects the change ΔXΔY in the position of the plasma 27 on the target 12 as a change in the position of the spot of the visible light V1.

[0048] The position detection processing unit 50 detects a change in the position of the plasma 27 in the optical axis direction of the condenser lens 31 and a change in the position of the plasma 27 in a direction perpendicular to the optical axis of the condenser lens 31 from the position of the spot of the visible light V1 detected by the position detection sensor 40. The position detection processing unit 50 also detects a change in the position of the plasma 27 in the optical axis direction of the condenser lens 31 from the size of the spot of the visible light V1 detected by the position detection sensor 40. The position detection processing unit 50 may calculate a change in the optical axis of the EUV optical system for correcting the optical axis of the EUV optical system that collects the EUV light based on the detected change in the position of the plasma 27 on the target 12. The position detection processing unit 50 may, for example, previously associate the change in the position of the plasma 27 with the change in the optical axis of the EUV optical system. The position detection processing unit 50 may be, for example, an information processing device such as a server device or a personal computer.

[0049] Fig. 7 is a block diagram illustrating the position detection processing unit 50 in the position detection device 1 according to the embodiment 1. As shown in Fig. 7, the position detection processing unit 50 has a control unit 51, a communication unit 52, a storage unit 53, and an interface unit 54. The control unit 51, the communication unit 52, the storage unit 53, and the interface unit 54 each have the functions of a control means, a communication means, a storage means, and an interface means.

[0050] The control unit 51 includes a processor such as a central processing unit (CPU), a micro processing unit (MPU), an electronic control unit (ECU), a field-programmable gate array (FPGA), or an application specific integrated circuit (ASIC). The control unit 51 functions as a calculation device that performs position detection processing, calculation processing, and the like. The control unit 51 also controls the operations of the communication unit 52, the storage unit 53, the interface unit 54, and each component for executing the function of each device.

[0051] Each component of the information processing device can be realized, for example, by executing a program under the control of the control unit 51. More specifically, each component can be realized by the control unit 51 executing a program stored in the storage unit 53. Each component may be realized by recording a necessary program on an arbitrary non-volatile recording medium and installing it as necessary. Each component may be realized not only by software using a program, but also by any combination of hardware, firmware, and software.

[0052] The communication unit 52 performs communication necessary for the position detection processing unit 50 to perform position detection processing. The storage unit 53 is, for example, a ROM (Read Only Memory) or a RAM (Random Access Memory). The storage unit 53 has a function for storing a control program and an arithmetic program executed by the control unit 51. The storage unit 53 also has a function for temporarily storing image data detected by the position detection sensor 40.

[0053] The interface unit 54 is, for example, a user interface. The interface unit 54 is connected to an input means such as a keyboard, a touch panel, or a mouse, and an output means such as a display or a speaker. The interface unit accepts data input operations by a user (such as an operator), and outputs information to the user.

[0054] Next, a position detection method of this embodiment will be described. Fig. 8 is a flow chart illustrating a position detection method according to the first embodiment. As shown in step S11 of Fig. 8, the position detection method of this embodiment first collects visible light V1 generated together with EUV light E1 from plasma 27 in target 12. Specifically, laser light L1 is collected on target 12 by a collecting lens 31. Visible light V1 generated together with EUV light E1 from the plasma 27 thus generated is collected by a visible light optical system 30.

[0055] Next, the visible light V1 collected by the visible light optical system 30 is detected by the position detection sensor 40, as shown in step S12.

[0056] Next, as shown in step S13, the position detection processing unit 50 detects a change in the position of the plasma 27 on the target 12 from a change in the spot of the visible light V1 detected by the position detection sensor 40.

[0057] When detecting a change in the position of the plasma 27 by the position detection processing unit 50, a change in the position of the plasma 27 in the optical axis direction of the collecting lens 31 and a change in the position of the plasma 27 in a direction perpendicular to the optical axis of the collecting lens 31 may be detected from the position of the spot of visible light V1 detected by the position detection sensor 40. Furthermore, when detecting a change in the position of the plasma 27 by the position detection processing unit 50, a change in the position of the plasma 27 in the optical axis direction of the collecting lens 31 may be detected from the size of the spot of visible light V1 detected by the position detection sensor 40.

[0058] After the change in the position of the plasma 27 is detected by the position detection processing unit 50, a change in the optical axis of the EUV light optical system for correcting the optical axis of the EUV light optical system that collects the EUV light E1 may be calculated based on the change in the position of the plasma 27 in the target 12 detected by the position detection processing unit 50.

[0059] Next, the effects of this embodiment will be described. In the position detection device 1 of this embodiment, visible light V1 generated from the plasma 27 together with the EUV light E1 is transmitted through the peripheral portion of the condenser lens 31. Therefore, from the position of the spot of visible light V1 on the position detection sensor 40, it is possible to detect a change ΔZ in the position of the plasma 27 in the optical axis direction of the condenser lens 31, and a change ΔXΔY in the position of the plasma 27 in a direction perpendicular to the optical axis of the condenser lens 31.

[0060] Furthermore, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is greater than the focal depth D of the focusing lens 31, the change ΔZ in the position of the plasma 27 in the optical axis direction of the focusing lens 31 can be detected from the size of the spot of the visible light V1.

[0061] Furthermore, since the changes ΔX, ΔY, and ΔZ in the position of the plasma 27 in the target 12 can be detected, the optical axis of the EUV light E1 in an inspection device or the like that uses the EUV light E1 can be corrected.

[0062] (Embodiment 2) Next, a position detection device according to embodiment 2 will be described. In the position detection device of this embodiment, visible light V1 passes through a central portion including the optical axis of the condenser lens 31. Fig. 9 is a configuration diagram illustrating the position detection device according to embodiment 2.

[0063] As shown in FIG. 9, the position detection device 2 according to this embodiment includes a visible light optical system 30, a position detection sensor 40, and a position detection processing unit 50. The visible light optical system 30 includes a condensing lens 31 and a lens 33. The optical axes of the condensing lens 31 and the lens 33 are aligned. In this embodiment, visible light V1 passes through a central portion of the condensing lens 31 that includes the optical axis. The visible light V1 that passes through the condensing lens 31 is incident on the lens 33. The visible light V1 passes through a central portion of the lens 33 that includes the optical axis. The lens 33 collects the visible light V1 on the position detection sensor 40.

[0064] <Visible light passes through the center of the lens. Change in position in the Z-axis direction> Fig. 10 is a configuration diagram illustrating visible light V1 when the position of plasma 27 in target 12 changes in the Z-axis direction in the position detection device 2 according to the second embodiment. As shown in Fig. 10, when the position of plasma 27 generated in target 12 changes, the optical axis of visible light V1 also changes. Visible light V1 passes through the center portion of condenser lens 31 and is condensed by lens 33 onto position detection sensor 40. Position detection sensor 40 detects visible light V1 as a spot.

[0065] 11 is a diagram illustrating spots of visible light V1 detected by the position detection sensor 40 before and after the position of the plasma 27 on the target 12 changes in the position detection device 2 according to embodiment 2. NO.2-A, NO.2-B, NO.2-C, NO.2-D, and NO.2-E in Fig. 11 are similar to the conditions of NO.1-A, NO.1-B, NO.1-C, NO.1-D, and NO.1-E in Fig. 5.

[0066] As shown in No. 2-A of Fig. 11, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is equal to or less than the focal depth D, the change ΔZ in position does not affect the size of the spot of the visible light V1, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot does not change. Also, the visible light V1 passes through the central portion of the condenser lens 31. Therefore, the position of the spot does not change in the position detection sensor 40.

[0067] Next, as shown in No. 2-B of FIG. 11, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is larger than the focal depth D, the change ΔZ in position affects the size of the spot, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot changes. Also, the visible light V1 passes through the center part of the condenser lens 31. Therefore, the position of the spot does not change in the position detection sensor 40.

[0068] In this way, when visible light V1 is transmitted through the central portion of collecting lens 31, it is difficult for position detection sensor 40 to detect change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in position of the spot of visible light V1, regardless of focal depth D. On the other hand, when change ΔZ in position in the Z-axis direction is larger than focal depth D, position detection sensor 40 detects change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in size of the spot of visible light V1.

[0069] <Visible light passes through the center of the lens. Change in position in the X and Y directions> Fig. 12 is a configuration diagram illustrating visible light V1 when the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction in the position detection device 2 according to the second embodiment. As shown in Fig. 12, when the pointing of laser light L1, that is, the focusing position of laser light L1, changes, the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction. Position detection sensor 40 detects the change ΔXΔY in the position of plasma 27 in the X-axis direction and the Y-axis direction as a change in the position of the spot of visible light V1.

[0070] 11, the position detection sensor 40 detects a change ΔXΔY in at least one of the position of the plasma 27 in the target 12 in the X-axis direction and the Y-axis direction as a change in the position of the spot of the visible light V1. It is difficult for the position detection sensor 40 to detect the change ΔXΔY in position as a change in the size of the spot of the visible light V1.

[0071] <Visible light passes through the center of the lens. Position changes in the X, Y, and Z directions> 11, when the change in position ΔZ of the plasma 27 in the target 12 in the Z-axis direction is equal to or smaller than the focal depth D, the position detection sensor 40 cannot detect the change in position ΔZ as a change in the size of the spot. In contrast, when the change in position ΔZ is larger than the focal depth D, the position detection sensor 40 detects the change in position ΔZ as a change in the size of the spot.

[0072] On the other hand, as shown in No. 2-D and No. 2-E, the position detection sensor 40 detects the change ΔXΔY in the position of the plasma 27 on the target 12 as a change in the center position of the spot of the visible light V1.

[0073] The position detection processing unit 50 detects a change in the position of the plasma 27 in a direction perpendicular to the optical axis of the collecting lens 31 from the position of the spot of visible light V1 detected by the position detection sensor 40. The position detection processing unit 50 also detects a change in the position of the plasma 27 in the optical axis direction of the collecting lens 31 from a change in the size of the spot of visible light V1 detected by the position detection sensor 40.

[0074] Next, the effect of this embodiment will be described. The position detection device 2 of this embodiment transmits the visible light V1 through the central portion including the optical axis of the condenser lens 31. As a result, when the position change ΔZ is larger than the focal depth D, the position detection processing unit 50 can detect the change ΔZ in the position of the plasma 27 in the optical axis direction of the condenser lens 31 from the change in the size of the spot of the visible light V1. In addition, the position detection processing unit 50 can detect the change ΔXΔY in the position of the plasma 27 in the direction perpendicular to the optical axis of the condenser lens 31 from the change in the position of the spot of the visible light V1. In this way, in this embodiment, the position change ΔZ and the position change ΔXΔY can be distinguished. Therefore, the position detection device 2 can distinguish between the position of the target 12 in the Z-axis direction and the pointing of the laser light L1. Other configurations and effects are included in the description of the first embodiment.

[0075] (Embodiment 3) Next, a position detection device according to a third embodiment will be described. The position detection device according to this embodiment includes a shielding plate disposed between the position detection sensor and the visible light optical system. FIG. 13 is a configuration diagram illustrating the position detection device according to the third embodiment.

[0076] 13, in this embodiment, the shading plate 34 of the position detection device 3 is disposed between the position detection sensor 40 and the visible light optical system 30. Specifically, the shading plate 34 is disposed between the position detection sensor 40 and the lens 33. The shading plate 34 is disposed on the optical axis of the condenser lens 31 and the lens 33. The shading plate 34 blocks a central portion including the optical axis in a cross section of the visible light V1 from the position detection sensor 40.

[0077] Visible light V1 passes through the central portion of collecting lens 31, which includes the optical axis. Visible light V1 that has passed through collecting lens 31 is incident on lens 33. Visible light V1 passes through the central portion of lens 33, which includes the optical axis. Lens 33 collects visible light V1 on position detection sensor 40. At that time, shielding plate 34 blocks the central portion, which includes the optical axis, of the cross section of visible light V1. Therefore, the peripheral portion other than the central portion of visible light V1 that has passed through lens 33 is collected on position detection sensor 40.

[0078] <Visible light passes through the center of the lens. Change in position in the Z-axis direction> 14 is a configuration diagram illustrating visible light V1 when the position of plasma 27 in target 12 changes in the Z-axis direction in the position detection device 3 according to embodiment 3. As shown in Fig. 14, when the position of plasma 27 generated in target 12 changes, the optical axis of visible light V1 also changes. Visible light V1 passes through the center part of condenser lens 31 and is condensed by lens 33 onto position detection sensor 40. At that time, the center part of visible light V1 is shielded by shielding plate 34.

[0079] 15 is a diagram illustrating spots of visible light V1 detected by the position detection sensor 40 before and after the position of the plasma 27 on the target 12 changes in the position detection device 3 according to embodiment 3. NO.3-A, NO.3-B, NO.3-C, NO.3-D, and NO.3-E in Fig. 15 are similar to the conditions of NO.1-A, NO.1-B, NO.1-C, NO.1-D, and NO.1-E in Fig. 5.

[0080] As shown in No. 3-A of Fig. 15, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is equal to or less than the focal depth D, the change ΔZ in position does not affect the size of the spot of the visible light V1, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot does not change. Also, the visible light V1 passes through the central portion of the condenser lens 31. Therefore, the position of the spot does not change in the position detection sensor 40.

[0081] Next, as shown in No. 3-B of FIG. 15, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is larger than the focal depth D, the change ΔZ in position affects the size of the spot, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot changes. In this embodiment, the central part of the visible light V1 is blocked by the shielding plate 34. Therefore, the position detection sensor 40 detects the annular spot. Also, the visible light V1 passes through the central part of the condenser lens 31. Therefore, the central position of the annular spot does not change in the position detection sensor 40.

[0082] In this way, when visible light V1 is transmitted through the central portion of collecting lens 31, it is difficult for position detection sensor 40 to detect change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in position of the spot of visible light V1, regardless of focal depth D. On the other hand, when change ΔZ in position in the Z-axis direction is larger than focal depth D, position detection sensor 40 detects change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in size of the annular spot of visible light V1.

[0083] <Visible light passes through the center of the lens. Change in position in the X and Y directions> Fig. 16 is a configuration diagram illustrating visible light V1 when the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction in the position detection device 3 according to the third embodiment. As shown in Fig. 16, when the pointing of laser light L1, that is, the focusing position of laser light L1, changes, the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction. Position detection sensor 40 detects the change ΔXΔY in the position of plasma 27 in the X-axis direction and the Y-axis direction as a change in the position of the spot of visible light V1.

[0084] 15, the position detection sensor 40 detects a change ΔXΔY in at least one of the position of the plasma 27 in the target 12 in the X-axis direction and the Y-axis direction as a change in the position of the spot of the visible light V1. It is difficult for the position detection sensor 40 to detect the change ΔXΔY in position as a change in the size of the spot of the visible light V1.

[0085] <Visible light passes through the center of the lens. Position changes in the X, Y, and Z directions> 15, when the change in position ΔZ of the plasma 27 in the target 12 in the Z-axis direction is equal to or smaller than the focal depth D, the position detection sensor 40 cannot detect the change in position ΔZ as a change in the size of the spot. In contrast, when the change in position ΔZ is larger than the focal depth D, the position detection sensor 40 detects the change in position ΔZ as a change in the size of the annular spot.

[0086] On the other hand, as shown in No. 3-D and No. 3-E, the position detection sensor 40 detects the change ΔXΔY in the position of the plasma 27 on the target 12 as a change in the center position of the annular spot of the visible light V1.

[0087] The position detection processing unit 50 detects a change in the position of the plasma 27 in a direction perpendicular to the optical axis of the collecting lens 31 from the position of the annular spot of the visible light V1 detected by the position detection sensor 40. The position detection processing unit 50 also detects a change in the position of the plasma 27 in the optical axis direction of the collecting lens 31 from a change in the size of the annular spot of the visible light V1 detected by the position detection sensor 40.

[0088] Next, the effects of this embodiment will be described. The position detection device 3 of this embodiment transmits visible light V1 through the central portion including the optical axis of the condenser lens 31. The central portion of the visible light V1 is blocked by the shielding plate 34. This allows the position detection processing unit 50 to detect the change in position ΔZ of the plasma 27 in the optical axis direction of the condenser lens 31 from the change in size of the annular spot when the change in position ΔZ is greater than the focal depth D. Making the spot annular can clarify the contour of the spot and improve the measurement accuracy of the spot size.

[0089] Furthermore, from the change in the center position of the annular spot, the position detection processing unit 50 can detect a change ΔXΔY in the position of the plasma 27 in the direction perpendicular to the optical axis of the focusing lens 31. By making the spot annular, the center position of the spot can be clarified from the spot contour, and the measurement accuracy of the spot position can be improved.

[0090] In this manner, in this embodiment, it is possible to distinguish between the position change ΔZ and the position change ΔXΔY. Therefore, the position detection device 3 can distinguish between the position of the target 12 in the Z-axis direction and the pointing of the laser light L1. In addition, it is possible to improve the measurement accuracy of the size and position of the spot.

[0091] Fig. 17 is a diagram illustrating a spot of visible light detected by the position detection sensor 40 in the position detection device 3 according to the third embodiment when the shielding plate 34 is present. Fig. 18 is a diagram illustrating a spot of visible light detected by the position detection sensor 40 in the position detection device 3 according to the third embodiment when the shielding plate 34 is not present.

[0092] As shown in 3-F of Figure 17, for example, when the radius of lens 33 is 60 mm and the radius of the shielding plate 34 placed on lens 33 is 59 mm, visible light V1 emitted from plasma 27 on the left end passes through focusing lens 31, lens 33 and shielding plate 34 and enters position detection sensor 40 on the right end.

[0093] As shown in Fig. 17, 3-G, the spot of visible light V1 detected by position detection sensor 40 before the position of plasma 27 changes is shown as an image with one side measuring 0.5 mm. Fig. 17, 3-H and 3-I show the spot when the plasma position changes by +50 μm and +100 μm, respectively, in the Z-axis direction. The larger the change in the plasma position, the larger the size of the spot.

[0094] As shown in 3-J of Figure 18, for example, when the radius of the lens 33 is 60 mm and a shielding plate 34 is not placed on the lens 33, visible light V1 emitted from the plasma 27 on the left end passes through the focusing lens 31 and the lens 33 and enters the position detection sensor 40 on the right end.

[0095] As shown in Fig. 18, 3-K, the spot of visible light V1 detected by position detection sensor 40 before the position of plasma 27 changes is shown as an image with one side measuring 1.5 mm. Fig. 18, 3-L and 3-M show the spots when the plasma position changes by +50 μm and +100 μm, respectively, in the Z-axis direction. The larger the change in the plasma position, the larger the size of the spot.

[0096] 17 and 18, by disposing the shielding plate 34, the focal depth becomes shallow, the NA is improved, and the aberration can be reduced. Therefore, the amount of change in the position of the plasma 27 that can be detected by the position detection sensor 40 can be improved. Other configurations and effects are included in the description of the first and second embodiments.

[0097] (Embodiment 4) Next, a position detection device according to a fourth embodiment will be described. In the position detection device of this embodiment, the central part of the visible light V1 is reflected by a mirror and detected by another position detection sensor. Fig. 19 is a configuration diagram illustrating the position detection device according to the fourth embodiment.

[0098] 19, in this embodiment, the shading plate 35 of the position detection device 4 has a mirror 36 that reflects a central portion of the visible light V1. The position detection device 4 also has a position detection sensor 41 that is different from the position detection sensor 40. The position detection sensor 41 detects the central portion of the visible light V1 reflected by the mirror 36 of the shading plate 35. By providing central shading to the position detection sensor 40, it is possible to expect the same effect as in the case of providing central shading in the third embodiment.

[0099] The visible light V1 passes through the central portion of the condensing lens 31, including the optical axis. The visible light V1 that passes through the condensing lens 31 is incident on the lens 33. The visible light V1 passes through the central portion of the lens 33, including the optical axis. The lens 33 collects the visible light V1 on the position detection sensor 40. At that time, the mirror 36 in the shielding plate 35 reflects the central portion of the visible light V1, including the optical axis, in the cross section. The mirror 36 reflects the central portion of the visible light V1 to the position detection sensor 41. On the other hand, the shielding plate 35 shields the central portion of the visible light V1, including the optical axis, in the cross section, from the position detection sensor 40. Therefore, the central portion of the visible light V1 that passes through the lens 33 is collected on the position detection sensor 41. The peripheral portion of the visible light V1 that passes through the lens 33, other than the central portion, is collected on the position detection sensor 40.

[0100] <Visible light passes through the center of the lens. Change in position in the Z-axis direction> Fig. 20 is a configuration diagram illustrating visible light V1 when the position of plasma 27 in target 12 changes in the Z-axis direction in the position detection device 4 according to embodiment 4. As shown in Fig. 20, when the position of plasma 27 generated in target 12 changes, the optical axis of visible light V1 also changes. Visible light V1 passes through the center portion of condenser lens 31 and is condensed by lens 33 onto position detection sensor 40. At that time, the center portion of visible light V1 is reflected by mirror 36 of shielding plate 35 to position detection sensor 41.

[0101] 21 is a diagram illustrating spots of visible light V1 detected by the position detection sensors 40 and 41 before and after the position of the plasma 27 on the target 12 is changed in the position detection device 4 according to embodiment 4. NO.4-A, NO.4-B, NO.4-C, NO.4-D, and NO.4-E in FIG. 21 are similar to the conditions of NO.1-A, NO.1-B, NO.1-C, NO.1-D, and NO.1-E in FIG.

[0102] As shown in No. 4-A of Fig. 21, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is equal to or less than the focal depth D, the change ΔZ in position does not affect the size of the spot of the visible light V1, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot detected by the position detection sensors 40 and 41 does not change. Also, the visible light V1 passes through the center part of the condenser lens 31. Therefore, the position of the spot detected by the position detection sensors 40 and 41 does not change.

[0103] 21, when the change ΔZ in the position of the plasma 27 in the target 12 in the Z-axis direction is larger than the focal depth D, the change ΔZ in the position affects the size of the spot, i.e., the blur of the spot, before and after the change. Therefore, the size of the spot detected by the position detection sensors 40 and 41 changes.

[0104] In this embodiment, the central portion of the visible light V1 is blocked from the position detection sensor 40 by the shielding plate 35. Therefore, the position detection sensor 40 detects an annular spot. Also, the central portion of the visible light V1 is focused on the position detection sensor 41 by the mirror 36. Therefore, the position detection sensor 41 detects a spot whose size has changed. The visible light V1 passes through the central portion of the focusing lens 31. Therefore, the central position of the spot does not change in the position detection sensors 40 and 41.

[0105] In this way, when visible light V1 is transmitted through the central portion of collecting lens 31, it is difficult for position detection sensors 40 and 41 to detect change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in position of the spot of visible light V1, regardless of focal depth D. On the other hand, when change ΔZ in position in the Z-axis direction is larger than focal depth D, position detection sensors 40 and 41 detect change ΔZ in position of plasma 27 in the optical axis direction of collecting lens 31 as a change in size of the spot of visible light V1.

[0106] <Visible light passes through the center of the lens. Change in position in the X and Y directions> Fig. 22 is a configuration diagram illustrating visible light V1 when the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction in the position detection device 4 according to embodiment 4. As shown in Fig. 22, when the pointing of laser light L1, that is, the focusing position of laser light L1, changes, the position of plasma 27 on target 12 changes in at least one of the X-axis direction and the Y-axis direction. Position detection sensors 40 and 41 detect the change ΔXΔY in the position of plasma 27 in the X-axis direction and the Y-axis direction as a change in the position of the spot of visible light V1.

[0107] 21, the position detection sensors 40 and 41 detect a change ΔXΔY in at least one of the positions of the plasma 27 in the X-axis direction and the Y-axis direction in the target 12 as a change in the position of the spot of the visible light V1. Note that it is difficult for the position detection sensor 40 to detect the change in position ΔXΔY as a change in the size of the spot of the visible light V1.

[0108] <Visible light passes through the center of the lens. Position changes in the X, Y, and Z directions> 21, when the change in position ΔZ of the plasma 27 in the target 12 in the Z-axis direction is equal to or smaller than the focal depth D, the position detection sensors 40 and 41 cannot detect the change in position ΔZ as a change in the size of the spot. In contrast, when the change in position ΔZ is greater than the focal depth D, the position detection sensor 40 detects the change in position ΔZ as a change in the size of the annular spot. Moreover, the position detection sensor 41 detects the change in position ΔZ as a change in the size of the spot.

[0109] On the other hand, as shown in No.4-D and No.4-E, the position detection sensor 40 detects the change ΔXΔY in the position of the plasma 27 on the target 12 as a change in the center position of the annular spot of the visible light V1. Also, the position detection sensor 41 detects the change ΔXΔY in the position of the plasma 27 on the target 12 as a change in the center position of the spot of the visible light V1.

[0110] The position detection processing unit 50 detects a change in the position of the plasma 27 in a direction perpendicular to the optical axis of the focusing lens 31 from the position of the annular spot of visible light V1 detected by the position detection sensor 40 and the position of the spot of visible light V1 detected by the position detection sensor 41.

[0111] In addition, the position detection processing unit 50 detects a change in the position of the plasma 27 in the optical axis direction of the focusing lens 31 from a change in the size of the annular spot of visible light V1 detected by the position detection sensor 40 and a change in the size of the spot of visible light V1 detected by the position detection sensor 41.

[0112] Next, the effects of this embodiment will be described. In the position detection device 4 of this embodiment, the position detection processing unit 50 can detect a change ΔZ in the position of the plasma 27 in the optical axis direction of the focusing lens 31 from a change in the size of the spot of the visible light V1 detected by the position detection sensors 40 and 41. By making the spot on the position detection sensor 40 annular, the outline of the spot can be made clear, and the measurement accuracy of the spot size can be improved.

[0113] Furthermore, the position detection processing unit 50 can detect a change ΔXΔY in the position of the plasma 27 in the direction perpendicular to the optical axis of the focusing lens 31, from the position of the spot of visible light V1 detected by the position detection sensors 40 and 41. By making the spot on the position detection sensor 40 annular, the central position of the spot can be clarified from the spot contour, and the measurement accuracy of the spot position can be improved.

[0114] In this embodiment, the position change ΔZ can be detected based on the size of the spot of the position detection sensor 40, and the position change ΔXΔY can be detected based on the position of the spot of the position detection sensor 41. In this way, the position change ΔZ and the position change ΔXΔY can be detected separately by the different position detection sensors 40 and 41. Therefore, the process in the position detection processing unit 50 can be differentiated between the position change ΔZ from the position detection sensor 40 and the position change ΔXΔY from the position detection sensor 41, and the efficiency can be improved. Other configurations and effects are included in the description of the first to third embodiments.

[0115] (Embodiment 5) Next, a position detection device according to a fifth embodiment will be described. The position detection device of this embodiment performs pointing correction of the laser light L1 based on a change in the position of the spot detected by at least one of the position detection sensors 40 and 41. FIG. 23 is a configuration diagram illustrating a position detection device according to the fifth embodiment. As shown in FIG. 23, the position detection device 5 may include galvanometer mirrors 24a and 25a instead of the mirrors 24 and 25. The galvanometer mirrors 24a and 25a can change the reflection direction under the control of the position detection processing unit 50.

[0116] Fig. 24 is a diagram illustrating the spots of visible light V1 detected by the position detection sensors 40 and 41 before and after the position of the plasma 27 on the target 12 changes as a result of a change in the pointing of the laser light L1 in the position detection device 5 according to embodiment 5. As shown in Fig. 24, the position of the spot detected by the position detection sensor 41 shows changes Δα and Δβ in the α and β directions on the image, respectively.

[0117] The position detection processing unit adjusts the galvanometer mirrors 24a and 25a based on the change Δα and the change Δβ. For example, the reflection direction of the galvanometer mirror 24a may be adjusted to correct the change Δα. The reflection direction of the galvanometer mirror 25a may be adjusted to correct the change Δβ.

[0118] In this manner, in the position detection device 5 of the present embodiment, the position detection processing unit 50 calculates the change in the optical axis of the EUV optical system in order to correct the optical axis of the EUV optical system on the side of the device such as an inspection device, and also calculates the change in the optical axis of the laser light L1 in order to correct the pointing of the laser light L1. Specifically, the position detection processing unit 50 calculates the adjustment amount of the galvanometer mirrors 24a and 25a based on the changes Δα and Δβ in the spot positions on at least one of the position detection sensors 40 and 41. Then, the position detection processing unit 50 may adjust the reflection directions of the galvanometer mirrors 24a and 25a based on the calculated adjustment amount. For example, the position detection processing unit 50 may perform PID control to adjust the reflection directions of the galvanometer mirrors 24a and 25a using the changes Δα and Δβ in the spot positions as input values.

[0119] According to this embodiment, the position detection processing unit 50 calculates a change in the optical axis of the laser light L1 for correcting the optical axis of the laser light L1 based on a change in the position of the detected plasma 27. Then, the position detection processing unit 50 can correct the pointing of the laser light L1 based on the calculated change in the optical axis of the laser light L1. This makes it possible to improve the irradiation conditions of EUV light in an inspection apparatus, an exposure apparatus, and the like. Other configurations and effects are included in the description of embodiments 1 to 4.

[0120] Although the embodiments of the present disclosure have been described above, the present disclosure includes appropriate modifications that do not impair the objects and advantages thereof, and is not limited to the above-mentioned embodiments. In addition, the configurations in the first to fifth embodiments may be appropriately combined.

[0121] Furthermore, a part or all of the processing of the position detection processing unit 50 described above may be executed by a computer program. The above-mentioned program includes a set of instructions (or software code) for making the computer perform one or more functions described in the embodiment when the program is loaded into the computer. The program may be stored in a non-transitory computer-readable medium or a tangible storage medium. By way of example and not limitation, the computer-readable medium or tangible storage medium includes random-access memory (RAM), read-only memory (ROM), flash memory, solid-state drive (SSD) or other memory technology, CD-ROM, digital versatile disc (DVD), Blu-ray (registered trademark) disk or other optical disk storage, magnetic cassette, magnetic tape, magnetic disk storage or other magnetic storage device. The program may be transmitted on a temporary computer-readable medium or communication medium. By way of example and not limitation, the temporary computer-readable medium or communication medium includes electrical, optical, acoustic, or other forms of propagating signals.

[0122] The technical concept of the embodiment also includes the following position detection program for causing a computer to execute the position detection method of the embodiment.

[0123] A step of focusing a laser beam on a target with a focusing lens to generate plasma, and focusing visible light generated together with the EUV light from the plasma with a visible light optical system; detecting the visible light collected by the visible light optical system with a position detection sensor; detecting a change in the position of the plasma on the target from a change in the spot of the visible light detected by the position detection sensor using a position detection processing unit; A location detection program that causes a computer to execute the above. [Explanation of symbols]

[0124] 1, 2, 3, 4 Position detector 10 light source 11 Container 12. Target 13 Bottom 14 Cylindrical section 15 Bottom 16 Inner surface 17 Groove 18 Heater 19. Mirror 20 Debris Shield 21 concave mirror 22 Opening 23, 24, 25, 26 Mirror 24a, 25a Galvanometer mirror 27 Plasma 30 Visible light optical system 31 Condenser lens 32, 33 Lens 34, 35 Shielding plate 36 Mirror 40, 41 Position detection sensor 50 Position detection processing section 51 Control section 52 Communications Department 53 Storage section 54 Interface section E1 EUV light L1 Laser light R1 Rotation axis V1 visible light

Claims

1. a visible light optical system that focuses, with a focusing lens, visible light generated from plasma generated by focusing a laser beam on a target with the focusing lens, together with EUV light focused with the EUV light optical system; a position detection sensor that detects a spot of the visible light condensed by the visible light optical system; and a position detection processing unit that detects a change in the position of the plasma from a change in the spot of the visible light detected by the position detection sensor; Equipped with the position detection processing unit detects a change in a position of the plasma in a direction perpendicular to the optical axis of the condenser lens from a position of the spot of the visible light detected by the position detection sensor, and calculates a change in the optical axis of the laser light for correcting the optical axis of the laser light based on the detected change in the position of the plasma. Position detection device.

2. a visible light optical system that focuses a laser beam on a target with a focusing lens to generate plasma, and focuses visible light generated together with the EUV light from the plasma with the focusing lens; a position detection sensor that detects a spot of the visible light condensed by the visible light optical system; and a position detection processing unit that detects a change in the position of the plasma from a change in the spot of the visible light detected by the position detection sensor; Equipped with the position detection processing unit detects a change in a position of the plasma in a direction perpendicular to the optical axis of the collecting lens from a position of the spot of the visible light detected by the position detection sensor, and calculates a change in the optical axis of the EUV light optical system for correcting the optical axis of the EUV light optical system that collects the EUV light based on the detected change in the plasma position. Position detection device.

3. The target is molten metal held on the inner periphery of a vessel that rotates about an axis of rotation.

3. The position detection device according to claim 1 or 2.

4. a shielding plate disposed between the position detection sensor and the visible light optical system, the shielding plate shielding a central portion of the cross section of the visible light, the central portion including an optical axis of the condenser lens, from the position detection sensor; the position detection processing unit detects a change in the position of the plasma in the optical axis direction of the focusing lens from the size of the annular spot of the visible light detected by the position detection sensor.

3. The position detection device according to claim 1 or 2.

5. a step of focusing laser light on a target with a focusing lens in a visible light optical system to generate plasma, and focusing visible light generated from the plasma together with EUV light focused by an EUV light optical system with the focusing lens; detecting a spot of the visible light condensed by the condenser lens in the visible light optical system by a position detection sensor; detecting a change in the position of the plasma from a change in the spot of the visible light detected by the position detection sensor using a position detection processing unit; Equipped with In the step of detecting by the position detection processing unit, detecting a change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens from the position of the spot of the visible light detected by the position detection sensor; The method further includes calculating a change in the optical axis of the laser beam to correct the optical axis of the laser beam based on a change in the position of the plasma detected by the position detection processing unit. Location detection methods.

6. a step of focusing laser light on a target with a focusing lens in a visible light optical system to generate plasma, and focusing visible light generated together with EUV light from the plasma with the focusing lens; detecting a spot of the visible light condensed by the condenser lens in the visible light optical system by a position detection sensor; detecting a change in the position of the plasma from a change in the spot of the visible light detected by the position detection sensor using a position detection processing unit; Equipped with In the step of detecting by the position detection processing unit, detecting a change in the position of the plasma in a direction perpendicular to the optical axis of the focusing lens from the position of the spot of the visible light detected by the position detection sensor; a step of calculating a change in an optical axis of an EUV light optical system for collecting the EUV light based on a change in the position of the plasma detected by the position detection processing unit, for correcting the optical axis of the EUV light optical system; Location detection methods.

7. The target is molten metal held on the inner periphery of a vessel that rotates about an axis of rotation.

7. The position detection method according to claim 5 or 6.

8. a shielding plate disposed between the position detection sensor and the visible light optical system, shielding a central portion of the cross section of the visible light, the central portion including an optical axis of the condenser lens, from the position detection sensor; In the step of detecting by the position detection processing unit, detecting a change in the position of the plasma in the optical axis direction of the focusing lens from the size of the annular spot of the visible light detected by the position detection sensor; 7. The position detection method according to claim 5 or 6.

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