Optical device

Abstract

The present disclosure provides an optical device that, in addition to being capable of stably illuminating an object regardless of a change in state of a component of the optical device, is also capable of stably observing the result of illuminating the object irrespective of the change in state of the optical device component. The optical device according to the present disclosure comprises: a detection unit that detects light generated by illumination light being projected onto an object; and an optical system in which, in response to a change in the state of a component which occurs when the illumination of the object is performed, the illumination distribution of the illumination light in an inspection visual field of the detection unit fluctuates in a prescribed direction associated with the state change. The illumination distribution has a shape such that the length in a prescribed direction is longer than the length in a direction perpendicular to the prescribed direction.

Description

optical device

[0001] The present disclosure relates to optical devices.

[0002] Patent Document 1 describes a light source in which a target material is formed on the surface of a cylindrical member that rotates around a rotation axis, and the formed target material is irradiated with excitation light to emit illumination light.

[0003] Patent document 2 describes a light source that uses centrifugal force to hold a molten metal target material on the inner wall of a crucible that rotates around a rotation axis, and emits illumination light by irradiating the held target material with excitation light.

[0004] JP 2020-077007 A JP 2022-168463 A

[0005] In an optical device that irradiates an object with illumination light, the position where the illumination light should be irradiated on the object may deviate from its original position, or the illumination profile for the object may change from its original position, depending on changes in the state of the components of the optical device. One example is a change in state in a light source device, as described in the background art. That is, in a light source device that supplies illumination light to an optical device, if a state change occurs, such as a fluctuation in the surface position of a target material, the position where excitation light is irradiated on the target material may deviate from its original position. In this case, as mentioned at the beginning, the position where illumination light (light generated by irradiating a target material with excitation light, also referred to as reaction light) should be irradiated on the object may deviate from its original position, or the illumination profile for the object may change from its original position.

[0006] The present disclosure has been made to solve such problems, and aims to provide an optical device that can stably illuminate an object regardless of changes in the state of the components of the optical device, and further aims to provide an optical device that can stably observe the results of illuminating an object regardless of changes in the state of the components of the optical device.

[0007] An optical device according to a first aspect of the present disclosure includes a detection unit that detects light generated by irradiating an object with illumination light, and an optical system that guides the illumination light to the object and also guides the light to the detection unit, wherein an illumination distribution of the illumination light in an inspection field of view of the detection unit varies in a predetermined direction associated with a change in state of a component that occurs when the object is illuminated. The illumination distribution has a shape in which a length in the predetermined direction is longer than a length in a direction perpendicular to the predetermined direction.

[0008] In the optical device, the illumination light is reaction light generated when the target material held in the target holding unit is excited by the excitation light, and the state change may include a change in the amount of the target held in the target holding unit.

[0009] In the optical device, the state change may include at least one of a position change of the optical element due to vibration and a temperature change of the optical element.

[0010] In the optical device, the illumination light may be reaction light generated when a target material held by a target holder is excited by excitation light. The optical device may further include a focusing unit that focuses the excitation light toward a position of the target material corresponding to the illumination distribution.

[0011] In the optical device, the focusing unit may include a focusing lens that focuses the excitation light onto the target material, a polarization separation element provided before the focusing lens, and a wavelength plate provided after the focusing lens.

[0012] In the optical device, the focusing unit may include a focusing lens that focuses the excitation light onto the target material, a polarization separation element provided before the focusing lens, and a wavelength plate provided after the focusing lens.

[0013] The illumination light is reaction light generated when a target material held in a target holding unit is excited by excitation light, and the optical device may further include a control unit that determines whether or not there is a fluctuation in the illumination distribution in a direction different from the specified direction, and if it determines that there is a fluctuation, controls the irradiation of the excitation light so that the illumination distribution has a shape in which the length in the different direction is longer than the length in a direction perpendicular to the different direction.

[0014] The illumination distribution may be an ellipse whose major axis direction is substantially the same as the predetermined direction.

[0015] The illumination light may be reaction light generated when a target material held in a target holder is excited by excitation light. The optical device further includes an input optical system that irradiates the excitation light toward the target material, and an output optical system that guides the reaction light to the optical system. The state change includes a change in the relative position of at least one of the input optical system or the output optical system and the target holder.

[0016] An optical device according to a second aspect of the present disclosure includes components including a detection unit that detects light generated by irradiating an object with illumination light, and an optical system that guides the illumination light to the object and also guides the light to the detection unit. The center position of the illumination distribution of the illumination light in the field of view of the detection unit, formed by the optical system, shifts in a predetermined direction corresponding to a predetermined state change that occurs in a predetermined component when the object is illuminated. The shape of the illumination distribution has a length in the predetermined direction that is longer than a length in a direction perpendicular to the predetermined direction.

[0017] In the optical device, the components may include a light source that generates reaction light by irradiating a surface of the target material with excitation light, the illumination light being the reaction light, and the predetermined state change includes a change in the position of the light source on the surface of the target material.

[0018] The optical device may further include a profile adjustment mechanism that changes the shape of the illumination distribution from a first shape to a second shape that is different from the first shape.

[0019] The optical device may further include a control unit that determines whether or not there is a fluctuation in the center position of the illumination distribution in a direction different from the specified direction, and, if the presence of the fluctuation is determined, controls the profile adjustment mechanism to change the shape of the illumination distribution so that the length in the different direction is longer than the length in a direction perpendicular to the different direction.

[0020] The illumination light may be reaction light generated when a target material is excited by excitation light, and the optical device may further include a focusing unit that focuses the excitation light toward a position of the target material corresponding to the illumination distribution. The profile adjustment mechanism includes the focusing unit.

[0021] According to the present disclosure, it is possible to stably illuminate an object regardless of changes in the state of the components of an optical device, and / or it is possible to stably observe the results of illuminating an object regardless of changes in the state of the components of an optical device.

[0022] 1 is a configuration diagram illustrating an optical device according to a first embodiment. FIG. 2 is a cross-sectional view illustrating a light source device of the optical device according to the first embodiment. FIG. 3 is a perspective view illustrating a container as a target holder in the light source device of the optical device according to the first embodiment. FIG. 4 is a plan view illustrating the light source device of the optical device according to the first embodiment. FIG. 5 is a view illustrating a profile adjustment mechanism of the optical device according to the first embodiment. FIG. 6 is a schematic diagram illustrating a field of view of a detector that detects light from an object in the optical device according to the first embodiment. FIG. 7 is a schematic diagram illustrating the relationship between the displacement of the surface position of a target material and the movement of a bright spot in the light source device of the optical device according to the first embodiment, as viewed from the direction of the rotation axis of the container. FIG. 8 is a schematic diagram illustrating the relationship between the displacement of the surface position of a target material and the movement of a bright spot in the light source device of the optical device according to the first embodiment, as viewed from a direction perpendicular to the rotation axis. FIG. 9 is a schematic diagram illustrating the field of view of a detector that detects light from an object in the optical device 1 according to the first embodiment, when illumination light has an illumination distribution of a predetermined shape. 1 is a schematic diagram illustrating a field of view of a detector that detects light from an object in the optical device 1 according to the first embodiment when the illumination light has an illumination distribution that does not have a predetermined shape. FIG.

[0023] Hereinafter, a specific configuration of this 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, components with the same reference numerals indicate substantially the same content.

[0024] (Embodiment 1) An optical device according to embodiment 1 will be described. FIG. 1 is a configuration diagram illustrating an optical device 1 according to embodiment 1. The optical device 1 may be an inspection device that inspects and evaluates a sample (object) by illuminating the sample with illumination light. Hereinafter, for convenience of explanation, the optical device 1 will be described as a mask inspection device using EUV light, and the optical device 1 will also be referred to as an inspection device 1. However, the optical device 1 does not necessarily have to be configured as an inspection device, and may be configured as an exposure device, a review device, or the like. Furthermore, the illumination light is not limited to EUV light.

[0025] As shown in FIG. 1 , the inspection apparatus 1 includes an illumination optical system 200, an inspection optical system 300, a detector 410, and an image processing unit 420. The inspection apparatus 1 may further include a light source device 100. The inspection apparatus 1 is an apparatus that inspects a sample 500 (also referred to as an object) for defects and the like using light L0 generated by the light source device 100 as illumination light L1. The sample 500 is, for example, an EUV mask. The sample 500 is not limited to an EUV mask and may be a semiconductor substrate or the like. The illumination optical system 200 and the inspection optical system 300 are also referred to as an optical system. That is, the optical system includes the illumination optical system 200 and the inspection optical system 300. The optical system guides illumination light L1 to the object and guides light generated by irradiating the object with the illumination light L1 to a detector 410.

[0026] The illumination optical system 200 includes an ellipsoidal mirror 210, an ellipsoidal mirror 220, and a drop mirror 230. The inspection optical system 300 includes a perforated concave mirror 310, a convex mirror 320, a plane mirror 330, and a concave mirror 340. The perforated concave mirror 310 and the convex mirror 320 configure a Schwarzschild magnification optical system.

[0027] The light source device 100 generates illumination light L1. The illumination light L1 includes, for example, EUV light LE having a wavelength of 13.5 nm, which is the same as the exposure wavelength of the EUV mask serving as the sample 500. Note that the illumination light L1 may include light other than EUV light. The illumination light L1 generated from the light source device 100 is reflected by the ellipsoidal mirror 210. The illumination light L1 reflected by the ellipsoidal mirror 210 travels while being narrowed, and is collected at a convergence point IF1. Therefore, the ellipsoidal mirror 210 reflects the illumination light L1 generated from the light source device 100 as convergent light. The convergence point IF1 is located at a position conjugate with the upper surface 510 of the sample 500, such as an EUV mask, and the detection surface 411 of the detector 410.

[0028] After passing through the convergence point IF1, the illumination light L1 travels while diverging and is incident on a reflecting mirror such as the ellipsoidal mirror 220. Therefore, the illumination light L1 reflected by the ellipsoidal mirror 210 is incident on the ellipsoidal mirror 220 as divergent light via the convergence point IF1. The illumination light L1 incident on the ellipsoidal mirror 220 is reflected by the ellipsoidal mirror 220, travels while being narrowed, and is incident on the drop-in mirror 230. In other words, the ellipsoidal mirror 220 reflects the incident illumination light L1 as converging light. The ellipsoidal mirror 220 then causes the illumination light L1 to be incident on the drop-in mirror 230. The drop-in mirror 230 is disposed directly above the EUV mask. The illumination light L1 incident on and reflected by the drop-in mirror 230 is incident on the sample 500. Therefore, the drop mirror 230 reflects the illumination light L1 reflected by the ellipsoidal mirror 220 onto the sample 500, thereby making the illumination light L1 incident on the sample 500.

[0029] The ellipsoidal mirror 220 focuses the illumination light L1 on the sample 500. The illumination optical system 200 is installed so that, when the illumination light L1 illuminates the sample 500, an image of the light source device 100 is formed on the upper surface 510 of the sample 500. Therefore, the illumination optical system 200 provides critical illumination. In this manner, the illumination optical system 200 illuminates the sample 500, such as an EUV mask, using critical illumination provided by the illumination light L1 generated by the light source device 100.

[0030] The sample 500 is placed on a stage 520. Here, a plane parallel to the upper surface 510 of the sample 500 is defined as the αβ plane, and a direction perpendicular to the αβ plane is defined as the γ axis direction. The illumination light L1 is incident on the sample 500 from a direction tilted from the γ axis direction. That is, the illumination light L1 is incident obliquely and illuminates the sample 500.

[0031] The stage 520 is a three-dimensional drive stage having a drive unit 530. The drive unit 530 can illuminate a desired area of ​​the sample 500 by moving the stage 520 in the αβ plane. Furthermore, the drive unit 530 can perform focus adjustment by moving the stage 520 in the γ-axis direction.

[0032] Illumination light L1 from the light source device 100 illuminates an inspection area of ​​the sample 500. The inspection area illuminated by illumination light L1 is, for example, 0.5 mm square. Note that the inspection area is not limited to 0.5 mm square. Illumination light L1 is incident on the sample 500 from a direction tilted with respect to the γ-axis direction. Light from the sample 500 illuminated by illumination light L1 is incident on the perforated concave mirror 310. In the following, light from the sample 500 illuminated by illumination light L1 will be described as reflected light L2. Note that the light incident on the perforated concave mirror 310 from the sample 500 is not limited to reflected light L2 and may include diffracted light, etc. The reflected light L2 reflected by the sample 500 is incident on the perforated concave mirror 310. A hole 311 is provided at the center of the perforated concave mirror 310. The perforated concave mirror 310 collects the reflected light L2 from the sample 500 and reflects the collected reflected light L2 as convergent light.

[0033] The reflected light L2 reflected by the perforated concave mirror 310 is incident on the convex mirror 320. The convex mirror 320 reflects the reflected light L2 reflected by the perforated concave mirror 310 toward the hole 311 in the perforated concave mirror 310. The reflected light L2 that passes through the hole 311 is incident on the plane mirror 330. The plane mirror 330 causes the reflected light L2 reflected by the convex mirror 320 to be incident as convergent light through the hole 311 in the perforated concave mirror 310. The reflected light L2 that is incident on the plane mirror 330 is reflected by the plane mirror 330. The reflected light L2 reflected by the plane mirror 330 travels while being narrowed, and is collected at a convergence point IF2. Therefore, the plane mirror 330 reflects the incident reflected light L2 as convergent light. The convergence point IF2 is sometimes called an aperture stop. The convergence point IF2 is located at a position conjugate with the upper surface 510 of the sample 500 and the detection surface 411 of the detector 410.

[0034] After passing through the convergence point IF2, the reflected light L2 travels while diverging and is incident on the concave mirror 340. Therefore, the reflected light L2 reflected by the plane mirror 330 as convergent light is incident on the concave mirror 340 as divergent light via the convergence point IF2. The concave mirror 340 reflects the incident reflected light L2 as convergent light toward the detector 410. The reflected light L2 reflected by the concave mirror 340 is detected by the detector 410. In this manner, the inspection optical system 300 inspects the sample 500, which is the inspection target, with the illumination light L1 extracted from the output optical system 130 of the light source device 100. In other words, the inspection optical system 300 collects the reflected light L2 from the sample 500 illuminated by the illumination light L1 and guides the collected reflected light L2 to the detector 410.

[0035] The detector 410 may include a TDI (Time Delay Integration) sensor. The detector 410 receives light from the sample 500 illuminated by the illumination light L1. The area on the sample 500 detected by the detector 410 is called a field of view 511. The detector 410 receives reflected light L2 from the field of view 511 illuminated by the illumination light L1. The field of view 511 may be included in the inspection area illuminated by the illumination light L1. The detector 410 acquires image data of the sample 500, such as an EUV mask. When the detector 410 includes a TDI sensor, the detector 410 includes a plurality of image sensors arranged in a line in one direction. The image sensors are, for example, charge coupled devices (CCDs). Note that the image sensors are not limited to CCDs.

[0036] The image data of the sample 500 acquired by the detector 410 is output to the image processing unit 420 and processed in the image processing unit 420. The image processing unit 420 may be, for example, an information processing device such as a server device or a personal computer.

[0037] The reflected light L2 contains information such as defects in the sample 500. The specularly reflected light of the illumination light L1 that is incident on the sample 500 from a direction tilted with respect to the Z-axis direction is detected by the inspection optical system 300. If a defect exists in the sample 500, the defect is observed as a dark image. This observation method is called bright-field observation. Note that the inspection device 1 may also cause the illumination light L1 to be incident on the sample 500 from the Z-axis direction and detected by the inspection optical system 300. If a defect exists in the sample 500, the defect is observed as a bright image. This observation method is called dark-field observation.

[0038] The optical system of the optical device 1 according to the first embodiment includes an illumination optical system 200 and an inspection optical system 300. The optical system guides illumination light L1 to an object, and guides light generated by irradiating the object with the illumination light L1 to a detector 410. As will be described in detail later, in response to a state change of the components of the optical device 1 that occurs when illuminating the object, the illumination distribution of the illumination light L1 in the inspection field of view (field of view area 511) of the detector 410 varies in a predetermined direction associated with the state change.

[0039] Furthermore, the illumination distribution has a shape in which the length in a predetermined direction associated with the state change is longer than the length in a direction perpendicular to the predetermined direction.

[0040] In other words, in the optical device 1 according to the first embodiment, the illumination distribution of the illumination light L1 in the field of view of the detector 410, which is formed by the optical system, satisfies the following two requirements. First, the center position of the illumination distribution varies in a predetermined direction associated with a predetermined state change in a predetermined component that occurs when illuminating the object. Second, the shape of the illumination distribution has a length in the predetermined direction associated with the predetermined state change that is longer than the length in the direction perpendicular to the predetermined direction. Note that such a shape of the illumination distribution may be referred to as a "predetermined shape."

[0041] Here, the predetermined state change may be a state change that occurs with a frequency equal to or greater than a predetermined frequency among a plurality of state changes that can occur in the optical device 1. In this case, the length of the illumination distribution shape in the direction of variation corresponding to the state change that occurs with a frequency equal to or greater than the predetermined frequency is longer than the length in the direction perpendicular to the direction of variation. Furthermore, the predetermined state change may be a state change that displaces the center position of the illumination distribution by a predetermined distance or more among a plurality of state changes that can occur in the optical device 1. In this case, the length of the illumination distribution shape in the direction of variation corresponding to the state change that displaces the center position of the illumination distribution by a predetermined distance or more is longer than the length in the direction perpendicular to the direction of variation.

[0042] Furthermore, the predetermined state change may not include active state changes such as scanning of excitation light or illumination light by an optical element, as will be described later.

[0043] The shape of the illumination distribution may be set to a predetermined shape by previously adjusting the attitude, shape, arrangement, etc. of the output optical system 130 and the illumination optical system 200, which will be described later. In other words, the attitude, shape, arrangement, etc. of the output optical system 130 and the illumination optical system 200 may be adjusted in advance so that the shape of the illumination distribution has a length in the direction in which the illumination distribution varies corresponding to a predetermined state change that is longer than the length in the direction perpendicular to the direction of variation.

[0044] The optical device 1 according to the first embodiment may include a profile adjustment mechanism 170, which will be described in detail later. The profile adjustment mechanism 170 can change the shape of the illumination distribution from a first shape to a second shape. The shape of the illumination distribution may be set to a predetermined shape by the profile adjustment mechanism 170. The profile adjustment mechanism 170 may be provided in the light source device 100, which will be described later.

[0045] The optical device 1 according to the first embodiment may include a control unit 160 that controls the profile adjustment mechanism 170. Furthermore, the control unit 160 may determine whether or not there is a variation in the illumination distribution in a direction different from the predetermined direction, and, if it determines that such a variation exists, may control the profile adjustment mechanism 170 so that the length in the different direction is longer than the length in a direction perpendicular to the different direction.

[0046] Furthermore, the control unit 160 may determine a variation in the center position of the illumination distribution in a specific direction, and if it determines that such a variation exists, may control the profile adjustment mechanism 170 so that the length of the illumination distribution in the specific direction is longer than the length in a direction perpendicular to the specific direction. Here, the specific direction may be at least one of the variation directions that are assumed and recorded in advance as the variation directions of the illumination distribution that occur due to a change in the state of the components of the optical device 1. The specific direction may also be a unique variation direction that is not included in the variation directions that are assumed and recorded in advance as the variation directions of the illumination distribution that occur due to a change in the state of the components of the optical device 1.

[0047] The control unit 160 is a control device including one or more processors (processing devices). The processor is connected to a memory (not shown) and reads and executes a computer program from the memory to control the operation of the optical device 1. This control will be described in detail later.

[0048] As an example of a processor, one of a CPU (Central Processing Unit), an MPU (Micro Processing Unit), an FPGA (Field-Programmable Gate Array), a DSP (Digital Signal Processor), and an ASIC (Application Specific Integrated Circuit) may be used, or multiple of these may be used in parallel.

[0049] The memory may be a volatile memory, a nonvolatile memory, or a combination thereof. The number of memories is not limited to one, and multiple memories may be provided. The volatile memory may be, for example, a random access memory (RAM) such as a dynamic random access memory (DRAM) or a static random access memory (SRAM). The nonvolatile memory may be, for example, a read-only memory (ROM) such as a programmable random-only memory (PROM) or an erasable programmable read-only memory (EPROM), a flash memory, or a solid-state drive (SSD).

[0050] The memory is used to store one or more instructions. Here, the one or more instructions are stored in the memory as a program. The processor can perform the processes described in the above embodiments by reading and executing the program from the memory.

[0051] The memory may be external to the processor or may be built into the processor. The memory may also include storage located away from the processor. In this case, the processor can access the memory via an I / O (Input / Output) interface.

[0052] As described above, one or more processors included in the optical device 1 execute one or more programs including a set of instructions for causing a computer to execute an information processing algorithm. By executing the programs, the following information processing can be realized.

[0053] <Relationship Between State Changes of Components and Fluctuations in Illumination Distribution> Hereinafter, a description will be given of the relationship between state changes of the components of the optical device 1 and fluctuations in the illumination distribution of the illumination light L1 in the field of view (field of view area 511) of the detector 410. Note that in the present disclosure, fluctuations in the illumination distribution of the illumination light L1 may refer to fluctuations in the center position of the illumination distribution of the illumination light L1 in the field of view of the detector 410.

[0054] First, a description will be given of the relationship between a change in state of the light source device 100 as a component of the optical device 1 and a variation in illumination distribution. In this regard, a description will be given of the light source device of the optical device 1 according to embodiment 1. The light source device is one of the components of the optical device 1, and generates illumination light L1 used by the optical device 1.

[0055] FIG. 2 is a cross-sectional view illustrating the light source device 100 of the optical device 1 according to the first embodiment. FIG. 3 is a perspective view illustrating a container 111 as the target holder 110 in the light source device 100 of the optical device 1 according to the first embodiment. FIG. 4 is a plan view illustrating the light source device 100 of the optical device 1 according to the first embodiment. Some components are omitted in FIG. 4. As shown in FIGS. 2 to 4, the light source device 100 includes the target holder 110, an input optical system 120, an output optical system 130, an acquisition unit 140, a sensor 141, a driver 150, and a controller 160. In FIG. 2, the driver 150A is connected to the mirror 121, and the driver 150B is connected to the collector mirror 131. However, the driver does not necessarily need to be connected to all of these optical components. To avoid cluttering the diagram, the controller 160 is connected to only some components, but it may also be connected to other components.

[0056] The target holder 110 holds a target material 112. The target holder 110 includes a container 111, such as a crucible. The container 111 can melt metal inside. The container 111 holds the target material 112, such as molten metal, which generates plasma 127 when irradiated with excitation light LR. The excitation light LR is, for example, laser light including IR (Infrared) light. The target holder 110 may be stored in a chamber the inside of which is in a vacuum state.

[0057] The target holder 110 is not limited to the container 111, and may be a cylindrical drum. In this case, the target holder 110 holds the target material 112 by fixing a solid, such as xenon (Xe), that becomes the target material 112 on the surface of the drum.

[0058] The target material 112 may include molten metal. Note that the target material 112 is not limited to the molten metal held in the container 111, and may be a solid metal, liquid droplets, or the like, as long as it is a substance that generates plasma 127 when irradiated with excitation light LR. The molten metal is, for example, melted tin (Sn) or lithium (Li), but is not limited to tin or lithium as long as it generates plasma 127 when irradiated with excitation light LR.

[0059] The container 111 has a rotation axis R and rotates around the rotation axis R. The container 111 has, for example, a cylindrical shape with one opening closed. The closed portion of the container 111 is called the bottom 113. The cylindrical portion of the container 111 is called the cylindrical portion 114. The inner surface of the bottom 113 is called the bottom surface 115. The inner surface of the cylindrical portion 114 is called the inner wall surface 116. A groove 117 may be formed at the joint between the bottom 113 and the cylindrical portion 114. Note that the container 111 may have a shape other than those described above as long as it can hold molten metal.

[0060] The target holder 110 supports the target material 112 on an inner wall surface 116 of the container 111 by centrifugal force. The inner wall surface 116, which is formed to surround the rotation axis R, may include a cylindrical portion that is at a constant distance from the rotation axis R, or may include a cone-shaped portion that widens outward as it approaches the upper part. For example, the cone-shaped portion of the inner wall surface 116 may be connected to a groove 117.

[0061] In addition to the target holder 110, the light source device 100 may also include a heater 118 and a debris shield 119. By heating with the heater 118, a target material 112 such as molten metal can be formed in the container 111. The debris shield 119 is disposed at the opening 111a of the container 111 so as to cover the target material 112.

[0062] As the container 111 rotates about the rotation axis R, the target material 112 also rotates about the rotation axis R. As shown in Fig. 4 , for example, the target material 112, which is located at position P1 facing the sensor 141 at time t1, moves to the irradiation position PS at time t2 as the container 111 rotates. In this way, the target holder 110 moves the target material 112 to the irradiation position PS where it is irradiated with the excitation light LR as the target holder 110 moves (i.e., rotates).

[0063] The input optical system 120 includes a first optical member OP1. The first optical member OP1 irradiates the target material 112 with the excitation light LR. The first optical member OP1 includes, for example, at least one of a mirror 121 and a profile adjustment mechanism 170. Note that the first optical member OP1 is not limited to the mirror 121 and the profile adjustment mechanism 170, as long as it is an optical member that irradiates the target material 112 with the excitation light LR, and may also be a laser LS that generates the excitation light LR.

[0064] The first optical member OP1 irradiates the target material 112 with the excitation light LR at an angle tilted from an axis perpendicular to the surface of the target material 112. Specifically, for example, the first optical member OP1 irradiates the surface of the irradiation position PS where the excitation light LR is irradiated with the excitation light LR at an incident angle tilted. By irradiating the excitation light LR at an inclined angle in this way, it is possible to suppress the influence of debris on optical members including the collector mirror 131 and the like. The reason why the influence of debris on optical members such as the collector mirror 131 can be suppressed will be explained below.

[0065] When the excitation light LR is irradiated from a direction perpendicular to the surface of the target material 112, debris scatters in all directions centered on the direction perpendicular to the surface. This can result in the debris adhering to the collector mirror 131 facing the irradiation position PS. On the other hand, when the excitation light LR is irradiated at an incident angle tilted toward the front of the irradiation position PS with respect to the direction of movement of the target holder 110, that is, when the excitation light LR is irradiated from a direction having an incident angle component tilted toward the front in a plane perpendicular to the rotation axis R, the angular velocity in the rotation direction of the container 111 is added to the velocity in the direction in which the debris scatters. Therefore, the debris can be further scattered in the reflection direction of the excitation light LR. In this way, the impact of debris on optical components such as the collector mirror 131 can be suppressed.

[0066] The mirror 121, for example, reflects the excitation light LR generated by the laser LS toward the irradiation position PS of the target material 112. The mirror 121 may include, for example, a mirror such as a piezo steering mirror. Note that the mirror 121 is not limited to a piezo steering mirror, and may include a galvanometer mirror, a polygon mirror, or the like, as long as it can reflect the excitation light LR toward the target material 112.

[0067] The profile adjustment mechanism 170 includes a condenser lens and the like, and condenses the excitation light LR reflected by the mirror 121 onto the irradiation position PS of the target material 112. The detailed configuration of the profile adjustment mechanism 170 will be described later.

[0068] The light source device 100 may include a laser LS that generates excitation light LR. Alternatively, the light source device 100 may introduce the excitation light LR from a laser LS that is installed outside the light source device 100 and separate from the light source device 100 into the light source device 100. The excitation light LR may be, for example, laser light including IR light. The excitation light LR may irradiate the target material 112 by controlling the oscillation and stopping of the control unit 160. For example, the excitation light LR is reflected by a mirror 121 and condensed by a condenser lens in the profile adjustment mechanism 170. As a result, the excitation light LR irradiates the target material 112.

[0069] The output optical system 130 extracts light L0 (also referred to as reaction light) generated by irradiating the target material 112 with the excitation light LR from the light source device 100 and guides it to an optical system (more specifically, an illumination optical system 200). The output optical system 130 includes a second optical member OP2. The second optical member OP2 extracts light L0 generated by irradiating the target material 112 with the excitation light LR from the light source device 100. The second optical member OP2 includes, for example, a collector mirror 131. Note that the second optical member OP2 is not limited to the collector mirror 131 as long as it is an optical member that extracts light L0 generated by irradiating the target material 112 with the excitation light LR, and may also be a second collector mirror (not shown) that further reflects the light L0 reflected by the collector mirror 131.

[0070] The collector mirror 131 reflects light L0 generated from the target material 112 by irradiation with the excitation light LR. The collector mirror 131 reflects, for example, EUV (Extreme Ultraviolet Lithography) light LE generated by irradiation with the excitation light LR. That is, the light L0 may include the EUV light LE. The EUV light LE is generated from plasma 127 generated by irradiating the target material 112 with the excitation light LR. The EUV light LE generated from the plasma 127 generated in the target material 112 is emitted to the illumination optical system 200 of the optical device 1 as illumination light L1. Therefore, the illumination light L1 includes the EUV light LE generated from the plasma 127.

[0071] The acquisition unit 140 acquires the surface position of the target material 112. The acquisition unit 140 is connected to a sensor 141 and acquires from the sensor 141 the surface position of the target material 112 actually measured by the sensor 141. The acquisition unit 140 acquires the surface position of the target material 112 at an irradiation position PS where the excitation light LR irradiates the target material 112. The acquisition unit 140 may acquire the surface position actually measured by the sensor 141 at the irradiation position PS, or may predict the surface position at the irradiation position PS from surface positions actually measured by the sensor 141 at peripheral positions, as described below. Furthermore, the acquisition unit 140 may predict the surface position of the target material 112 taking into account the tilt and vibration of the target holder 110 with respect to the rotation axis.

[0072] The acquisition unit 140 may be a separate entity from the sensor 141, or may be integrated with the sensor 141. Specifically, the sensor 141 may include, for example, a displacement meter, a high-speed camera, a low-speed camera, a four-segment photodiode (PD), or a time delay integration (TDI) camera. The acquisition unit 140 may acquire the surface position of the target material 112 by combining the sensor 141, such as a displacement meter, with another sensor. This allows the other sensor to supplement phase information that is difficult for the sensor 141, such as a displacement meter, to acquire.

[0073] The acquisition unit 140 may acquire the surface position of the target material 112 as a relative position with respect to the second optical member OP2. Specifically, the acquisition unit 140 may acquire the surface position of the target material 112 at the irradiation position PS as a relative position with respect to the second optical member OP2, or may acquire the surface position at a peripheral position as a relative position with respect to the second optical member OP2. The acquisition unit 140 may acquire the surface position of the target material 112 based on the distance from the sensor 141 to the surface of the molten metal. The acquisition unit 140 may also acquire the surface position of the target material 112 based on the thickness of the molten metal from the inner wall surface 116. Note that, in the case where the target material 112 is solid metal fixed to a cylindrical drum, the acquisition unit 140 may acquire the surface position of the target material 112 based on the thickness of the solid metal surface from the upper surface (surface) of the drum, as well as the tilt and vibration amount of the drum.

[0074] The acquisition unit 140 may acquire surface positions of peripheral positions other than the irradiation position PS. The peripheral positions include portions of the inner wall surface 116 of the container 111 other than the irradiation position PS. The acquisition unit 140 may predict the surface position of the irradiation position PS from the surface positions of the peripheral positions acquired from the sensor 141. Specifically, the acquisition unit 140 predicts the surface position of the irradiation position PS from the surface position of a position just before the irradiation position PS in the direction of movement of the target holding unit 110. At this time, by taking into account the movement speed (rotation speed) of the target holding unit 110, it is possible to predict the surface position at the irradiation position PS at the time when the excitation light reaches the irradiation position PS (the time of irradiation). The acquisition unit 140 acquires the surface position of the irradiation position PS by predicting the surface position of the irradiation position PS in this manner.

[0075] If the sensor 141 is positioned opposite the irradiation position PS so that the surface position of the irradiation position PS can be measured and acquired, there is a risk that it will be affected by debris. Furthermore, since plasma 127 is generated at the irradiation position PS, there is a risk that the surface position will not be acquired accurately. Therefore, the sensor 141 is positioned to face a peripheral position away from the irradiation position PS. This makes it possible to suppress the influence of debris and improve the measurement accuracy of the surface position. For example, the sensor 141 may be positioned to face a position P1 on the opposite side of the irradiation position PS with respect to the rotation axis R. Note that the sensor 141 may also be positioned to face a peripheral position other than position P1 if the influence of debris can be reduced.

[0076] FIG. 5 is a diagram illustrating a profile adjustment mechanism 170 in the optical device 1 according to the first embodiment. The profile adjustment mechanism 170 may be provided in the light source device 100. As shown in FIG. 5, the profile adjustment mechanism 170 includes a condenser lens 122, a wave plate 171, and a quartz plate (also referred to as a quartz wave plate) 172. In FIG. 5, the driver 150C is connected to the condenser lens 122. However, the driver 150C does not necessarily have to be connected to the condenser lens 122. In the irradiation direction of the excitation light LR, the wave plate 171 is disposed before the condenser lens 122, and the quartz plate 172 is disposed after the condenser lens 122. In this example, the wave plate 171 is a half-wave plate.

[0077] The condenser lens 122 condenses the excitation light LR reflected by the mirror 121 onto the irradiation position PS of the target material 112. The wave plate 171 is made of a birefringent material and has two different refractive indices depending on the crystal orientation. Therefore, the wave plate 171 functions as an element (polarization separation element) that adjusts the polarization state of the incident excitation light LR by imparting a predetermined phase difference to two polarization components defined by the crystal orientation of the incident excitation light LR. The adjusted polarization direction is defined by the axis of the quartz plate 172. The excitation light LR with its polarization state adjusted is incident on the condenser lens 122.

[0078] The quartz plate 172 is located immediately after the condenser lens 122 and is made of a birefringent material. The quartz plate 172 imparts different refractive indices to the p-polarized and s-polarized light of the incident excitation light LR. As a result, when the cross section of the excitation light LR emitted from the quartz plate 172 is cut along a plane perpendicular to the irradiation direction, the illumination distribution (also referred to as the illumination profile) has a shape that extends in a predetermined direction. Furthermore, because the quartz plate 172 is configured to be rotatable, the direction in which the illumination distribution extends can be changed.

[0079] 5, one or more pairs of wave plates 171 and quartz plates 172 may be provided downstream of the quartz plate 172. By increasing the number of quartz plates provided in the profile adjustment mechanism 170, the number of collected beams can be increased.

[0080] 6 is a schematic diagram illustrating the field of view FOV of the detector 410 that detects light from the object (sample 500) in the optical device 1 according to the first embodiment. For ease of explanation, as shown in FIG. 6 , one direction in the field of view FOV detected by the detector 410 is defined as the X-axis direction, and the other direction perpendicular to the X-axis direction is defined as the Y-axis direction. In this case, the Z-axis direction is the defocus direction of the beam spot BS. The defocus direction corresponds to the optical axis direction of the collector mirror 131.

[0081] As shown in Fig. 6, the beam spot BS, which is the illumination distribution of the illumination light L1, is elliptical, with a length W1 in the major axis direction and a length W2 (<W1) in the minor axis direction. As will be described later, the major axis direction of the beam spot BS can be set to be substantially the same as the direction of movement of the beam spot BS. However, the beam spot BS is not limited to an elliptical shape as long as it has a shape that extends in a predetermined direction.

[0082] The shape of the beam spot BS, which is the illumination distribution of the illumination light L1, depends at least on (1) the shape of the excitation light LR in the light source device 100 (illumination distribution of the excitation light LR), (2) the output optical system 130 of the light source device 100, and (3) the illumination optical system 200 of the optical device 1. Furthermore, the center position of the beam spot BS, which is the illumination distribution of the illumination light L1, depends at least on (1) the position where the excitation light LR is irradiated onto the target material 112 of the light source device 100 (i.e., the position where plasma is generated), (2) the output optical system 130 of the light source device 100, and (3) the illumination optical system 200 of the optical device 1.

[0083] Therefore, when the state (position, arrangement, attitude, etc.) of the output optical system 130 of the light source device 100 and the state (position, arrangement, attitude, etc.) of the illumination optical system 200 of the optical device 1 are constant (or can be considered constant), the center position of the beam spot BS, which is the illumination distribution of the illumination light L1, fluctuates depending on the position at which the excitation light LR is irradiated onto the target material 112 (i.e., the position at which plasma is generated). This will be described in further detail below.

[0084] 7 is a schematic diagram illustrating the relationship between the displacement of the surface position of the target material 112 and the movement of the bright spot in the light source device 100 of the optical device 1 according to the first embodiment, as viewed from the direction of the rotation axis R of the container 111. FIG. 8 is a schematic diagram illustrating the relationship between the displacement of the surface position of the target material 112 and the movement of the bright spot in the light source device 100 of the optical device 1 according to the first embodiment, as viewed from a direction perpendicular to the rotation axis R. Note that while the displacement of the surface position of the target material 112 held in the container 111 is described here as an example, the same can be said when considering the surface position of the target material 112 held on the surface of a cylindrical drum.

[0085] 7 and 8 show the relationship between the fluctuation in the position of the plasma 127 generated on the target material 112 due to the displacement of the surface position of the target material 112 and the resulting movement direction of the center position of the illumination distribution of the illumination light L1 in the field of view FOV of the detector 410. In FIGS. 7 and 8 , as described above, one direction in the field of view FOV detected by the detector 410 is the X-axis direction, and the other direction perpendicular to the one direction is the Y-axis direction. It can be considered that the plasma 127 is projected onto the field of view FOV as the illumination distribution of the illumination light L1. Thus, in the optical device 1 according to the first embodiment, although this is merely an example, as the surface position of the target material 112 approaches the collector mirror 131, the center position of the illumination distribution of the illumination light L1 moves toward the positive X-axis direction and the positive Y-axis direction in the field of view FOV. 7 and 8 show that in the optical device 1 according to the first embodiment, as the surface position of the target material 112 moves farther from the collector mirror 131, the center position of the illumination distribution of the illumination light L1 moves toward the negative X-axis direction and the negative Y-axis direction in the field of view FOV.

[0086] The displacement of the surface position of the target material 112 includes surface vibration caused by vibration due to rotation of the container 111 or the like propagating to the surface position, and displacement caused by a change in the amount of the target material 112 due to consumption or replenishment of the target material 112. In addition, if the target material is a solid such as frozen xenon, displacement due to roughness or irregularities on the target surface is also included.

[0087] 9 is a schematic diagram illustrating the field of view FOV of the detector 410 that detects light from the object (sample 500) in the optical device 1 according to the first embodiment when the illumination light L1 has an illumination distribution with a predetermined shape. As shown in FIGS. 7 to 9 , when the surface position of the target material 112 is displaced, the beam spot BS, which is the illumination distribution of the illumination light L1, moves in a direction having components in the X-axis direction and the Y-axis direction on the field of view FOV. In FIG. 9 , the beam spot BS moves in the direction D1.

[0088] In other words, the center position of the illumination distribution of the illumination light L1 in the field of view (FOV) of the detector 410, which is formed by the optical system, fluctuates in a predetermined direction, i.e., the D1 direction, corresponding to a predetermined state change in a predetermined component that occurs when the target is illuminated. This state change occurs in response to a change in the surface position of the target material 112 in the light source device 100 (more specifically, the surface position of the target material 112 in the region where the excitation light RL is irradiated to form plasma). The fluctuation in the surface position of the target material 112 can be caused by the amount of target material 112, vibration of the target holder 110, or the like. Therefore, the predetermined state change in the predetermined component may include a change in the amount of target material 112 held by the target holder 110. Furthermore, the predetermined state change in the predetermined component may include a change in the relative position of at least one of the input optical system 120 and the output optical system 130 relative to the target holder 110.

[0089] Note that the direction perpendicular to the D1 direction on the XY plane is defined as the D2 direction. Thus, displacement of the bright spot in a direction perpendicular to the optical axis of the collector mirror 131 results in displacement of the beam spot BS in the X-axis and Y-axis directions on the field of view FOV. By adjusting the attitude, shape, and layout of the output optical system 130 and the illumination optical system 200 in advance, or by operating the profile adjustment mechanism 170 automatically by the control unit 160 or manually by the user, for example, by adjusting the rotation angle of the quartz plate 172, it is possible to give the illumination distribution of the illumination light L1 a predetermined shape, as shown in FIG. 9 , i.e., make the major axis direction of the beam spot BS approximately equal to the D1 direction, in which the beam spot BS moves. That is, the shape of the illumination distribution is such that the length in the predetermined direction D1 is longer than the length in the direction D2 perpendicular to the predetermined direction.

[0090] FIG. 10 is a schematic diagram illustrating the field of view FOV of the detector 410 that detects light from an object (sample 500) in the optical device 1 according to the first embodiment when the illumination light L1 has an illumination distribution that does not have a predetermined shape. In FIG. 10 , the illumination distribution of the illumination light L1 differs from the predetermined shape (a shape in which the major axis direction of the beam spot BS is substantially the same as the direction D1, in which the beam spot BS moves). Here, the beam spot BS' is circular. Therefore, when the beam spot BS' moves in the direction D1, there is no common area between the area illuminated by the beam spot BS' before the movement and the area illuminated by the beam spot BS' after the movement, or the area of ​​the common area is small. In this case, the amount of light included in the field of view FOV detected by the detector 410 changes as the illumination distribution moves, making it impossible to stably illuminate the object. Alternatively, it is impossible to stably observe the results of illuminating the object.

[0091] On the other hand, in FIG. 9 , the beam spot BS is elliptical, and its major axis direction is approximately equal to the D1 direction. Therefore, if the movement distance of the beam spot is the same in FIG. 9 and FIG. 10 , the area of ​​the region common to the region irradiated by the beam spot BS before movement and the region irradiated by the beam spot BS after movement is larger than in the case of FIG. 10 . Therefore, compared to the situation in FIG. 10 , the object can be stably illuminated, and the results of illuminating the object can be stably observed. Note that this effect is not limited to when the major axis direction of the beam spot BS is approximately equal to the D1 direction, but is also achieved when the angle between the major axis of the beam spot BS and the axis indicating the D1 direction is between −45° and 45°. This is because, even when this condition is met, the length of the beam spot BS in the D1 direction is longer than its length in the D2 direction. However, the effect can be enhanced by making the angle between the major axis direction of the beam spot BS and the movement direction of the beam spot BS as small as possible.

[0092] The above describes a case where the beam spot BS, which is the illumination distribution of the illumination light L1, moves in accordance with the displacement of the surface position of the target material 112. However, the beam spot BS may move for other reasons.

[0093] As described above, the center position of the beam spot BS, which is the illumination distribution of the illumination light L1, depends on at least (1) the position where the excitation light LR is irradiated onto the target material 112 of the light source device 100 (i.e., the position where plasma is generated), (2) the output optical system 130 of the light source device 100, and (3) the illumination optical system 200 of the optical device 1. Therefore, it is conceivable that the position where the excitation light LR is irradiated onto the target material 112 of the light source device 100 (i.e., the position where plasma is generated) may change due to a change in the state (position, arrangement, attitude, etc.) of the input optical system 120 in the light source device 100. It is also conceivable that the beam spot BS may move due to a change in the state (position, arrangement, attitude, etc.) of the output optical system 130 in the light source device 100 or a change in the state (position, arrangement, attitude, etc.) of the illumination optical system 200 of the optical device 1. Changes in the state (position, arrangement, attitude, etc.) of the optical elements included in the optical device 1, i.e., at least one of the optical elements of the input optical system 120, the output optical system 130, and the illumination optical system 200, may be caused by vibration, temperature change, or deformation of the chamber in which the target holder 110 or the optical system is stored. Deformation of the chamber may be caused by the pressure difference between the internal vacuum pressure and the external atmospheric pressure, or by heat. Generally speaking, when the illumination light L1 is irradiated onto the target, the beam spot BS moves in a predetermined direction corresponding to the state change in the components of the optical device 1.

[0094] In order to correctly adjust the quartz crystal plate 172 so that the long axis direction of the beam spot BS is set to be approximately the same as the direction of its movement, it is preferable that the control unit 160 detects the direction of movement of the beam spot BS. For example, if the direction of movement of the beam spot BS changes dynamically, this can be determined from the signal of the detector 410, or a sensor that monitors the illumination distribution of the illumination light L1 at a point conjugate with the field of view of the detector 410 can be provided to monitor the direction of movement and changes in the direction of movement of the beam spot BS. As another example, the optical device 1 may be provided with a sensor that detects the cause of movement of the beam spot BS. When the control unit 160 detects a movement cause, it can identify the direction of movement by referring to a table that associates the movement cause with the movement direction corresponding to the movement cause.

[0095] The control unit 160 may detect the movement direction of the beam spot BS to determine whether the beam spot BS moves in a direction D3 different from the initial movement direction D1. When the control unit 160 detects movement of the beam spot BS in the different direction D3, it may operate the profile adjustment mechanism 170. As an example, the control unit 160 adjusts the angle of the quartz plate 172 so that the length of the beam spot BS in the direction D3 is longer than the length in a direction perpendicular to the direction D3. This allows the control unit 160 to control the irradiation mode of the excitation light LR onto the target material. In this way, when the control unit 160 detects movement of the beam spot BS in a specific direction (e.g., the different direction D3), it may control the profile adjustment mechanism 170 so that the length of the beam spot BS in the specific direction is longer than the length of the beam spot BS in a direction perpendicular to the specific direction.

[0096] As described above, the shape of the beam spot BS, which is the illumination distribution of the illumination light L1, depends at least on the shape of the excitation light LR in the light source device 100 (illumination distribution of the excitation light LR).

[0097] In the above example, the excitation light LR is irradiated onto the target material 112 with a single light spot. However, the excitation light LR may be irradiated onto the target material 112 with multiple beams as appropriate. This allows the shape of the beam spot BS, which is the illumination distribution of the illumination light L1, to be formed into a desired shape. Furthermore, by driving the optical elements of the input optical system 120, one or more beams of the excitation light LR may be scanned over the target material 112 at high speed for a predetermined distance. This allows the shape of the beam spot BS, which is the illumination distribution of the illumination light L1, to be formed into a desired shape. Note that active state changes in optical elements, such as those caused by scanning the target material 112 with the excitation light LR, do not necessarily need to be included in the predetermined state changes of the components of the optical device 1 described above.

[0098] As described above, the shape of the beam spot BS, which is the illumination distribution of the illumination light L1, depends at least on the output optical system 130 of the light source device 100 and the illumination optical system 200 of the optical device 1. For example, the illumination light L1 may be focused on the object by at least one of the output optical system 130 and the illumination optical system 200 of the optical device 1 so as to have a plurality of beam spots BS. This allows the shape of the beam spot BS, which is the illumination distribution of the illumination light L1, to be formed into a desired shape. As an example, this can be achieved by using a facet mirror as at least one optical element, which includes a plurality of reflective elements and whose attitudes can be individually controlled. Furthermore, by driving at least one optical element of the output optical system 130 or the illumination optical system 200, the beam of the illumination light L1 may be scanned at high speed over a predetermined distance of the object. This allows the shape of the beam spot BS, which is the illumination distribution of the illumination light L1, to be formed into a desired shape.

[0099] Note that active state changes in optical elements, such as those caused by scanning the illumination light L1 on an object, do not necessarily have to be included in the predetermined state changes of the components of the optical device 1. In other words, when the center position of the illumination distribution moves due to an active state change, the direction of movement of the illumination distribution associated with the active state change does not necessarily have to be included in the movement in the different direction D3 or the movement in the specific direction. Designing the optical device 1 in this manner makes it possible to make the optical device 1 robust against unintended passive state changes.

[0100] Alternatively, state changes occurring within a period during which an image is generated based on the charge from the detector 410 (also referred to as a charge accumulation period) may not be included in the predetermined state changes of the components of the optical device 1. This is because, with respect to fluctuations in the central position of the illumination distribution in the field of view FOV due to state changes that occur repeatedly within a period during which an image is generated based on the charge from the detector 410, the influence of fluctuations in the light intensity is averaged over the charge accumulation time, thereby enabling an image to be acquired in which the influence of fluctuations in the central position of the illumination distribution is mitigated. On the other hand, with respect to fluctuations in the central position of the illumination distribution in the field of view FOV due to state changes that occur at intervals or frequencies that exceed the period during which an image is generated based on the charge from the detector 410, such averaging over the charge accumulation time is not achieved. Therefore, in some embodiments, the shape of the illumination distribution may be such that the length in the direction of fluctuation of the central position of the illumination distribution associated with a predetermined state change that occurs at intervals or frequencies that exceed the period during which an image is generated based on the charge from the detector 410 is longer than the length in the direction perpendicular to the direction of fluctuation. In other words, the optical system may vary the illumination distribution of illumination light in the field of view of detector 410 in a predetermined direction associated with state changes of the components that occur at intervals or frequencies exceeding the period in which an image is generated based on the charge from detector 410. Furthermore, the illumination distribution may have a shape in which the length in the predetermined direction associated with state changes of the components that occur at intervals or frequencies exceeding the period in which an image is generated based on the signal from detector 410 is longer than the length in a direction perpendicular to the predetermined direction.

[0101] In the above examples, the mechanism for varying the number of beams and the scanning pattern of the excitation light LR and the illumination light L1 may be included in the profile adjustment mechanism 170. That is, in some embodiments, the optical device 1 may be provided with a profile adjustment mechanism 170 realized by such a mechanism for varying the number of beams and the scanning pattern of the excitation light LR and the illumination light L1.

[0102] Second Embodiment An optical device according to a second embodiment will be described. In this embodiment, the wave plate 171 and the quartz plate 172 according to the first embodiment are not essential, and the effects described in the first embodiment can be achieved.

[0103] (2A) The light source device 100 may include a set of two cylindrical lenses upstream of the condenser lens 122. For example, two plano-convex cylindrical lenses may be arranged so that their focal points are at a common position. The two plano-convex lenses may have different magnitudes of curvature and different directions of curvature. The directions of curvature may be perpendicular to each other between the two plano-convex lenses. With this configuration, the illumination distribution of the excitation light LR emitted from the downstream plano-convex lens has a shape that extends in a predetermined direction, as shown in embodiment 1. The control unit 160 can automatically, or the user can manually, adjust the angles at which the two plano-convex lenses are arranged, thereby changing the major axis direction of the illumination distribution of the excitation light LR. For example, when the control unit 160 detects that the beam spot BS of the illumination light L1 has moved in direction D3, which is different from the initial movement direction D1, the control unit 160 may adjust the angles at which the two plano-convex lenses are arranged so that the length of the beam spot BS in direction D3 is longer than the length in the direction perpendicular to direction D3.

[0104] As another example, the condenser lens 122 may be configured as a cylindrical lens.

[0105] (2B) The control unit 160 may control the beam spot BS to have its major axis in a predetermined direction by scanning the excitation light LR containing IR light over the target material at high speed.

[0106] (2C) The light source device 100 may include an optical element such as a cylindrical lens array or a DOE (Diffractive Optical Element) diffraction grating before the condenser lens 122. The illumination distribution of the excitation light LR formed by the excitation light LR emitted from this optical element has a shape that extends in a predetermined direction, as shown in the first embodiment.

[0107] 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-described embodiments. In the embodiments of the present disclosure, the target holder 110 is a container 111 such as a crucible, but the target holder 110 is not limited to this and may be one that holds the target material 112 on the surface of a cylindrical object, or one that holds the target material 112 using a tape-like object, etc. Furthermore, the configurations of embodiments 1 and 2 may be combined as appropriate.

[0108] This application claims priority based on Japanese Patent Application No. 2024-095585, filed on June 13, 2024, the disclosure of which is incorporated herein in its entirety by reference.

[0109] 1 Inspection device 100 Light source device 110 Target holder 111 Container 111a Opening 112 Target material 113 Bottom 114 Cylindrical portion 115 Bottom surface 116 Inner wall surface 117 Groove 118 Heater 119 Debris shield 120 Input optical system 121 Mirror 122 Collector lens 127 Plasma 130 Output optical system 131 Collector mirror 140 Acquisition unit 141 Sensor 150 Drive unit 160 Control unit 170 Profile adjustment mechanism 171 Wave plate 172 Quartz plate 200 Illumination optical system 210 Ellipsoidal mirror 220 Ellipsoidal mirror 230 Drop-in mirror 300 Inspection optical system 310 Perforated concave mirror 311 Hole 320 Convex mirror 330 Plane mirror 340 Concave mirror 410 Detector 411 Detection surface 420 Image processing unit 500 Sample 510 Upper surface 511 Field of view area 520 Stage 530 Drive unit BS Beam spot FOV Field of view area L0 Light L1 Illumination light L2 Reflected light LE EUV light LR Excitation light LS Laser OP1 First optical member OP2 Second optical member P1 Position PS Irradiation position R Rotation axis

Claims

1. A detection unit that detects light generated when illumination light is shone on the sample, An optical system that guides the illumination light to the sample and guides the light to the detection unit, wherein the illumination distribution of the illumination light in the inspection field on the sample detected by the detection unit changes in a predetermined direction corresponding to the change in the state of the components that occur when the sample is illuminated, The illumination distribution of the illumination light in the inspection field on the sample has a shape in which the length in the predetermined direction is longer than the length in the direction perpendicular to the predetermined direction. optical equipment.

2. The illumination light is reaction light generated when the target material held in the target holding section is excited by the excitation light. The aforementioned change in state includes a change in the amount of target held in the target holding unit. The optical apparatus according to claim 1.

3. The aforementioned state change is, This includes at least one of the following: a change in the position of an optical element due to vibration, or a change in the temperature of the optical element. The optical apparatus according to claim 1.

4. The illumination light is reaction light generated when the target material held in the target holding section is excited by the excitation light. The system further includes a light-gathering unit that focuses the excitation light toward the position of the target material corresponding to the illumination distribution. The optical apparatus according to any one of claims 1 to 3.

5. The light-gathering unit comprises a focusing lens for focusing the excitation light onto the target material, a polarization separation element provided in front of the focusing lens, and a waveplate provided behind the focusing lens. The optical apparatus according to claim 4.

6. The illumination light is reaction light generated when the target material held in the target holding section is excited by the excitation light. Determine whether or not there is a variation in the illumination distribution in a direction different from the predetermined direction. The control unit, when it determines the presence of the aforementioned variation, further controls the irradiation of the excitation light such that the length in the different direction is longer than the length in the direction perpendicular to the different direction in the illumination distribution. The optical apparatus according to any one of claims 1 to 3.

7. The illumination distribution is elliptical in shape, with its major axis being substantially the same as the predetermined direction. The optical apparatus according to any one of claims 1 to 3.

8. The illumination light is reaction light generated when the target material held in the target holding section is excited by the excitation light. An input optical system that irradiates the aforementioned excitation light toward the target material, The system further comprises an output optical system that guides the reaction light to the optical system, The state change includes a change in the relative position between at least one of the input optical system or the output optical system and the target holding unit. The optical apparatus according to claim 1.

9. A detection unit that detects light generated when illumination light is shone on the sample, The system includes an optical system that guides the illumination light to the sample and also guides the light to the detection unit, The central position of the illumination distribution of the illumination light in the inspection field on the sample detected by the detection unit, formed by the optical system, shifts in a predetermined direction corresponding to a predetermined state change in a predetermined component that occurs when illumination is performed on the sample. The shape of the illumination distribution of the illumination light in the inspection field on the sample is such that the length in the predetermined direction is longer than the length in the direction perpendicular to the predetermined direction. optical equipment.

10. The aforementioned component includes a light source that generates reaction light by irradiating the surface of a target material with excitation light, The illumination light is the reaction light, The predetermined state change includes a change in the surface position of the light source on the target material. The optical apparatus according to claim 9.

11. The system further includes a profile adjustment mechanism that changes the shape of the illumination distribution from a first shape to a second shape different from the first shape. The optical apparatus according to claim 9.

12. The system further includes a control unit that determines whether or not there is a change in the center position of the illumination distribution in a direction different from the predetermined direction, and, if the presence of such a change is determined, controls the profile adjustment mechanism to adjust the shape of the illumination distribution so that the length in the different direction is longer than the length in the direction perpendicular to the different direction. The optical apparatus according to claim 11.

13. The illumination light is reaction light generated when the target material is excited by the excitation light. The system further includes a light-gathering unit that focuses the excitation light toward the position of the target material corresponding to the illumination distribution, The profile adjustment mechanism includes the light-gathering section, The optical apparatus according to claim 11.