Metrology system for extreme ultraviolet light source

Abstract

This invention discloses a measurement system comprising: a light-emitting device, a detection device, and a control device communicating with the detection device. The light-emitting device is configured to generate an optical probe propagating along a detection optical axis, which intersects a target axial path at a detection area. The target axial path extends primarily along the X-axis of an X, Y, Z coordinate system. The detection device is configured to detect light generated at a plurality of different wavelengths, each wavelength associated with a different position along the X-axis of the X, Y, Z coordinate system. The generated light is generated from an interaction between the optical probe and a target traveling along the target axial path within the detection area. The control device is configured to analyze the detected light and determine positioning information related to the target along the X-axis of the X, Y, Z coordinate system.

Description

[Technical Field]

[0001] The subject matter disclosed relates to a measurement system for determining the positioning information of a target traveling along a target axial path. [Previous Technology]

[0002] Extreme ultraviolet (EUV) light (e.g., electromagnetic radiation with wavelengths of about 50 nm or less (sometimes referred to as soft X-rays) and including light with wavelengths of about 13 nm) can be used in lithography processes to create extremely small features in substrates such as silicon wafers.

[0003] Methods for generating EUV light include, but are not limited to, converting materials having emission spectra in the EUV range in a plasma state. In one such method, often referred to as laser-generated plasma ("LPP"), the desired plasma can be generated by irradiating a target material, such as a droplet, plate, strip, stream, or cluster, with an amplified beam, which may be called a driving laser. For this process, the plasma is typically generated in a sealed container, such as a vacuum chamber, and various types of measuring devices are used to monitor the plasma.

[0004] A lithography apparatus is a machine that applies a desired pattern onto a substrate (typically onto a target portion of the substrate). Lithography apparatuses can be used, for example, in the manufacture of integrated circuits (ICs). In this case, a patterning device, interchangeably referred to as a mask or magnifying mask, can be used to generate a circuit pattern to be formed on individual layers of the IC being formed. This pattern can be transferred onto a target portion (e.g., including a portion of a die, a die, or several dies) on a substrate (e.g., a silicon wafer). The transfer of the pattern is typically performed by imaging onto a radiation-sensitive material (e.g., a resist) layer disposed on the substrate. Generally, a single substrate will contain a network of sequentially patterned adjacent target portions. Conventional lithography apparatuses include: a so-called stepper, in which each target portion is irradiated by exposing the entire pattern onto the target portion at once; and a so-called scanner, in which each target portion is irradiated by scanning the pattern in a given direction ("scanning" direction) with a radiation beam, while simultaneously scanning the target portion parallel or antiparallel to this scanning direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0005] Extreme ultraviolet (EUV) light (e.g., electromagnetic radiation with wavelengths of about 50 nanometers (nm) or smaller (sometimes also called soft X-rays) and including light with wavelengths of about 13 nm) can be used in or with lithography apparatuses to produce extremely small features in substrates such as silicon wafers. Methods for generating EUV light include, but are not limited to, converting materials containing elements such as xenon (Xe), lithium (Li), or tin (Sn) into a plasma state using emission spectral lines in the EUV range. For example, in one such method known as laser-generated plasma (LPP), plasma can be generated by irradiating a target material, such as in the form of droplets, plates, strips, streams, or clusters, using an amplified beam, which may be called a driving laser, interchangeably referred to as fuel in the context of the LPP source. For this process, plasma is typically generated in a sealed container, such as a vacuum chamber, and various types of measuring devices are used to monitor the plasma. [Summary of the Invention]

[0006] In some general embodiments, a measurement system includes: a light-emitting device, a detection device, and a control device communicating with the detection device. The light-emitting device is configured to generate an optical probe including light having a plurality of different wavelengths. The optical probe includes the different wavelengths of the light propagating along a detection optical axis, which intersects a target axial path at a detection region. The detection device is configured to detect the light generated at the plurality of different wavelengths. The generated light is generated from an interaction between the optical probe and a target traveling along the target axial path in the detection region. The control device is configured to analyze the detected light and, based on the analysis, adjust one or more characteristics related to the target and one or more of the target axial path.

[0007] Embodiments may include one or more of the following features. For example, the control device may also communicate with the light-emitting device.

[0008] The light-emitting device may include a plurality of probe beams configured to generate one or more optical sources as the optical probe, each probe beam propagating along the probe optical axis intersecting the axial path of the target, and each probe beam having a different center wavelength. Each probe beam may have a different center wavelength, which is focused at a different position along the probe optical axis and within the detection region. The light-emitting device may include a probe beam configured to generate one or more optical sources as the optical probe, the probe beam propagating along the probe optical axis intersecting the axial path of the target, and the probe beam being defined by a continuous spectrum of one center wavelength.

[0009] The optical probe may have a dissimilar focal point along the detection optical axis and within the detection area. The measurement system may also include a cylindrical focusing optic in the path of the optical probe, the cylindrical focusing optic being configured to form the dissimilar focal point along a direction perpendicular to the detection optical axis as an optical screen for the optical probe.

[0010] The optical probe can be collimated along the detection optical axis or can be imaged on the detection area.

[0011] The detection device may include a plurality of detectors, each configured to detect light generated by the interaction between a separate probe beam from one of the optical probes and the target. Each detector may be configured to detect a portion of the separate probe beam incident on the target. The portion of the separate probe beam incident on the target may include a portion of the separate probe beam reflected or scattered from the target. Each detector may be configured to detect generated light having a wavelength different from the wavelength of the generated light detected by the other detectors. The detection device may be configured to distinguish the generated light between each of these different wavelengths.

[0012] The light generated can travel along a path that is different from the optical axis of the detector and also different from the axial path of the target.

[0013] The generated light can travel along a path parallel to an operating axis, which is defined by a direction along which one or more operating beams travel, and the one or more operating beams interact with a target in a target region downstream of the detection region. The generated light may be or include a portion of the detection beam reflected back from the target along the operating axis. The generated light can interact with at least some of the same optics that interact with the one or more operating beams.

[0014] Along the target axial path, the detection area may be upstream of one of the target areas where the target interacts with one or more operational beams. The target axial path may extend at least along an X-axis, and the detection optical axis may not be parallel to the X-axis. The control device may be configured to determine a position of the target along a Y-direction perpendicular to the X-axis. The detection optical axis may be parallel to a Y-axis, and the operational beams may travel substantially along a Z-axis. The light having the plurality of wavelengths may have a range such that the wavelength of the light changes along the Y-axis. The detection optical axis may be perpendicular to the Y-axis. The light having the plurality of wavelengths may extend such that the wavelength of the light changes along the Y-axis.

[0015] The one or more operating beams may include: a first amplified beam configured to interact with the target to modify the shape and movement of the target, thereby forming a modified target; and a second amplified beam configured to interact with the modified target, thereby converting the modified target into plasma that emits extreme ultraviolet light.

[0016] The control device is configured to adjust one or more characteristics related to one or more of the target and the target axial path, including one or more of the following: the control device is configured to instruct a target material supply to adjust one or more states related to the generation of the target; and the control device is configured to instruct an operating light source to adjust one or more states related to the generation of one or more operating beams, which interact with the target in a target area downstream of the detection area.

[0017] The detection device can be configured to detect the generated light at a rate as fast as or faster than the rate at which the target passes through the detection zone. The control device can be configured to adjust one or more characteristics related to the target, and the analysis of the target is based on one or more characteristics. The control device can be configured to adjust one or more characteristics related to the target, which may include instructing an operating light source to adjust the direction of one or more operating beams that interact with the target in a target area downstream of the detection zone, the adjustment of the direction being relative to the Z-axis of an X, Y, Z coordinate system, wherein the target axial path extends primarily along an X-axis, and the detection optical axis is aligned with the Y-axis or the Z-axis.

[0018] In other general embodiments, an extreme ultraviolet (EUV) light system includes: a target supply device configured to form a target stream directed to a target region, each target traveling along a target axial path extending primarily along the X-axis of an X, Y, Z coordinate system; an operational optical source configured to generate one or more operational beams directed to the target region, at least one operational beam configured to interact with the target to form a modified target; and a measurement system. The measurement system includes a light-emitting device, a detection device, and a control device communicating with the detection device. The light-emitting device is configured to generate an optical probe propagating along a detection optical axis that intersects the target axial path at a detection region. The detection device is configured to detect light generated at a plurality of different wavelengths, each wavelength being associated with a different position along the X-axis of the X, Y, Z coordinate system. The generated light is produced by an interaction between the optical probe and a target traveling along the target's axial path within the detection area. The control device is configured to analyze the detected light and determine the target-related positioning information along the X-axis of the X, Y, Z coordinate system.

[0019] Embodiments may include one or more of the following features. For example, the one or more operating beams may include: a first amplified beam configured to interact with the target to modify the shape and movement of the target, thereby forming a modified target; and a second amplified beam configured to interact with the modified target, thereby converting the modified target into plasma that emits extreme ultraviolet light.

[0020] In other general embodiments, a measurement system includes a light-emitting device, a detection device, and a control device communicating with the detection device. The light-emitting device is configured to generate an optical probe propagating along a detection optical axis that intersects a target axial path at a detection area, the target axial path extending primarily along the X-axis of an X, Y, Z coordinate system. The detection device is configured to detect light generated at a plurality of different wavelengths, each wavelength associated with a different position along the X-axis of the X, Y, Z coordinate system, the generated light arising from an interaction between the optical probe and a target traveling along the target axial path in the detection area. The control device is configured to analyze the detected light and determine positioning information related to the target along the X-axis of the X, Y, Z coordinate system.

[0021] Embodiments may include one or more of the following features. For example, the optical probe may be a broadband optical probe. The control device may be configured to determine, based on the analysis of the detected light, positioning information related to the target along the X-axis of the X, Y, Z coordinate system.

Implementation Method

[0037] Referring to FIG1, the measurement system 100 is configured to determine the positioning information of a target 105 traveling along a target axial path 110 toward a target region 115. In the target region 115, the target 105 interacts with one or more operational beams 120. The target axial path 110 extends generally along the -X direction of an X, Y, Z coordinate system defined by a cavity enclosing the target region 115 (an example of cavity 673 is shown in FIG6), and one or more operational beams 120 extend generally along the Z-axis of this X, Y, Z coordinate system. Therefore, the target 105 travels generally along the -X direction in its path to the target region 115. However, due to various disturbances within the cavity or due to the flow physics of the target 105, the target 105 may also include movement along one or more directions perpendicular to the X-axis, and such movement is in the YZ plane. The measurement system 100 is configured to determine the positioning information of the target 105 along the X-axis and also along a direction perpendicular or transverse to the X-axis (X-axis). Furthermore, in some embodiments, the measurement system 100 is particularly suitable for determining the positioning information of the target 105 along the Y-axis, which is generally perpendicular to the Z-axis, along which one or more operating beams travel (Figures 2A and 3A).

[0038] The measurement system 100 includes a light-emitting device 125, a detection device 135, and a control device 150. The light-emitting device 125 is configured to generate an optical probe 130 that propagates along a detection optical axis 130OA, which intersects with a target axial path 110 at a detection area 131. The detection device 135 is configured to detect the generated light 136. The generated light 136 is generated by the interaction between the optical probe 130 and a target 105 (within the detection area 131) traveling along the target axial path 110 in the detection area 131. For example, the generated light 136 may be a portion of the optical probe 130 reflected from the target 105. This signal increases as the target 105 first arrives at the optical probe 130 until it reaches its maximum value when the target 105 is completely contained within the thickness of the optical probe 103, and then decreases as the target 105 leaves the optical probe 130.

[0039] The generated light 136 can have a specific wavelength selected from a plurality of different wavelengths at any given time. The detection device 135 is configured to detect light at any of these different wavelengths. Furthermore, each wavelength is associated with a different position along the X-axis of the X, Y, Z coordinate system, which is either the Y or Z axis of the X, Y, Z coordinate system. In some specific instances, the X-axis is the Y axis.

[0040] The control device 150 communicates with the detection device 135. The control device 150 can also communicate with the light-emitting device 125. The control device 150 is configured to analyze the detected light 136 and determine positioning information related to the target 105 along both the X-axis and the X-axis of the X, Y, Z coordinate system. Therefore, in addition to determining the time of interaction between the target 105 and the optical probe 130, the control device 150 can also determine positioning information about the target 105 along the same direction of wavelength change of the generated light 136 (i.e., along the X-axis). The control device 150 can further adjust one or more characteristics related to one or more of the target 105 and the target axial path 110 based on the determined positioning information of the target 105 along both the X-axis and the X-axis (based on the analysis of the detected light 136). For example, one or more operating beams 120 can be adjusted 160 to change one or more of their states relative to the target 105. As another example, the direction and / or timing of the pulses of the operating beams 120 can be adjusted. As yet another example, the target supply device (Figures 2 and 3) that generates the target 105 can be adjusted 160 to adjust the state related to how the target 105 is generated. In this way, the control device 150 controls the trajectory of the target 105 and the timing of the target's arrival at the target area 115, such that the pulses of the operating beams 105 irradiate the target 105 at the target area 115.

[0041] Target 105 is a target mixture including target material and, where appropriate, impurities (such as non-target particles). Target 105 may be, for example, a droplet of liquid or molten metal, a portion of a liquid stream, solid particles or clusters, solid particles contained within a droplet, a foam of target material, or solid particles contained within a portion of a liquid stream. Target 105 may include, for example, water, tin, lithium, xenon, or any material having an emission spectrum in the EUV range when converted to a plasma state. For example, target 105 may include elemental tin, which may be used as pure tin (Sn); as tin compounds, such as SnBr4, SnBr2, SnH4; as tin alloys, such as tin-gallium alloys, tin-indium alloys, tin-indium-gallium alloys, or any combination of such alloys. Target 105 is formed as a stream of target 105 directed through detector region 131 to target region 115. The rate at which target 105 is generated and the rate at which target 105 passes through detection zone 131 can be approximately several kilohertz (kHz) or tens of kHz, such as, for example, at least 50 kHz and up to or exceeding 100 kHz. Details on how target 105 is generated are provided below with reference to Figure 6.

[0042] The light-emitting device 125 can be configured to generate an optical probe 130 comprising light simultaneously at a plurality of different wavelengths. Furthermore, each component of light within the optical probe 130 having different wavelengths can interact with the target 105 at different positions along the X-axis within the detection region 131. Therefore, the optical probe 130 has a color variation along the X-axis. For example, the optical probe 130 may include a first wavelength generated at a first position along the X-axis, a second wavelength generated at a second position along the X-axis, and a third wavelength generated at a third position along the X-axis. As another example, the optical probe 130 generates a light curtain or other beam shape as a beam passing through a target axial path 110 across the target 105. In some embodiments, the optical probe 130 is a continuous wave beam. In some embodiments, if the optical probe 130 is pulsed at a sufficiently high frequency (e.g., higher than the rate generated by the target 105), it may be a pulsed beam. In some embodiments, the optical probe 130 is composed of one or more laser beams. In other embodiments, the optical probe 130 may consist of one or more beams that are not laser beams.

[0043] This X-axis color change within the optical probe 130 enables the detection device 135 and control device 150 to measure changes in the positioning of the target 105 along the X-axis. This is because the detection device 135 is configured to sense this change in the wavelength distribution along the X-axis. Different embodiments of the light-emitting device 125 and the optical probe 130 are described with reference to Figures 2A, 3A, and 5.

[0044] The detection device 135 may include one or more photosensors, such as photodiodes, that operate at a sufficiently high bandwidth to detect each target 105 in the stream (via the generated light 136). Thus, if the target 105 is generated at a rate of 50 kHz, the photosensors within the detection device 135 are fast enough to detect and process the generated light 136 at a rate of 50 kHz (without aliasing). The detection device 135 is configured to sense the wavelength distribution of the generated light 136. This means that the detection device 135 is able to distinguish light of different wavelengths within the generated light 136 by the X-lateral color variation within the optical probe 130. Details of the detection device 135 are discussed below with reference to Figures 2A, 3A, and 5.

[0045] The control device 150 includes an electronic processor and an electronic storage device. The processor may be any type of electronic processor and there may be more than one electronic processor. The processor may include one or more processors adapted to execute computer programs, such as a general-purpose or special-purpose microprocessor, and one or more processors of any kind of digital computer. Generally, the processor receives instructions and data from a read-only memory or a random access memory or both. The electronic storage device stores instructions that may serve as computer programs, which, when executed, cause the processor to communicate with other components of the measurement system 100 (such as the detection device 135) and components affecting the adjustment 160 of one or more characteristics relating to one or more of the target 105 and the target axial path 110. The electronic storage device may include volatile memory, such as RAM. The electronic storage device may include both non-volatile components and volatile components. Furthermore, the control device 150 may include various individual modules, and each module may be dedicated to a specific task. Furthermore, these modules can be physically separated from each other or integrated with other components of the measurement system 100.

[0046] Referring to Figures 2A and 2B, an embodiment 200 of the measurement system 100 is shown. In the measurement system 200, the probe optical axis 230OA is parallel to the Y-axis of the X, Y, Z coordinate system. Therefore, the optical probe 230 travels along the Y-axis of this measurement system 200. The measurement system 200 includes a light-emitting device 225 that generates the optical probe 230. The optical probe 230 includes three probe beams 230_1, 230_2, and 230_3 (shown more clearly in Figure 2B), each probe beam 230_1, 230_2, and 230_3 having different center wavelengths λ1, λ2, and λ3. Each probe beam 230_1, 230_2, and 230_3 propagates along the probe optical axis 230OA (which is parallel to the Y-axis) and intersects with the target axial path 210. In addition, each detection beam 230_1, 230_2, 230_3 is focused along the detection optical axis 230OA at different positions Y_1, Y_2, Y_3.

[0047] In some embodiments, the probe beams 230_1, 230_2, and 230_3 are laser beams. The probe beams 230_1, 230_2, and 230_3 may be circular in intensity profile (i.e., in the XZ plane), and therefore will have a typical defocused laser waist profile. In these embodiments, the probe beams 230_1, 230_2, and 230_3 have a lateral shape symmetrical about the Y-axis. In some embodiments, the probe beams 230_1, 230_2, and 230_3 may be non-circular beams, wherein the longitudinal position of the beam waist may vary for different lateral directions. This shape can be produced by using a cylindrical lens. In the case of a cylindrical focused beam ("screen"), the lateral profile has a chisel-like shape and extends along the Z-axis.

[0048] In some embodiments, the light-emitting device 225 includes a light source, such as a laser, and three probe beams 230_1, 230_2, 230_3 at different wavelengths λ1, λ2, λ3 and also at different focal points at Y_1, Y_2, Y_3. In other embodiments, the light-emitting device 225 includes three lasers, each laser generating separate probe beams 230_1, 230_2, 230_3 at different wavelengths λ1, λ2, λ3. In still other embodiments, the light-emitting device 225 includes a single laser or broadband light source that generates three probe beams 230_1, 230_2, 230_3 at different wavelengths λ1, λ2, λ3. The probe beams 230_1, 230_2, 230_3 may be coupled from one or more light sources toward the detection region 231 by using one or more fiber optic devices. The light-emitting device 225 may further include a focusing device in the path of each detection beam 230_1, 230_2, 230_3, which is configured to focus a specific detection beam along the detection optical axis 230OA to its respective and different focal positions Y_1, Y_2, Y_3.

[0049] In some embodiments, wavelengths λ1, λ2, and λ3 may be in the visible and / or near-infrared (NIR) range. The separation between each wavelength (e.g., the separation between λ1 and λ2 or between λ2 and λ3) depends on the type and design of the optics (such as filters) within the light-emitting device 225. Furthermore, in some embodiments, the wavelength separation may be about tens of nanometers (nm), about 20 nm, about 30 nm, or about 40 nm.

[0050] Although three probe beams 230_1, 230_2, 230_3 are shown in the embodiment of the measurement system 200, in other embodiments, the optical probe 230 includes more than three probe beams.

[0051] Referring also to FIG. 2C, the detection device 235 is configured to receive the generated light 236. Furthermore, the detector 235 is oriented so that it can detect the generated light 236 (which may be light reflected from the target 205), regardless of the location of the target 205 within the detection area 231. The generated light 236 may correspond to portions of the respective detection beams 230_1, 230_2, 230_3 reflected from or scattered from the target 205. As shown, the generated light 236 may travel along a path different from the detection optical axis 230OA and also different from the target axial path 210.

[0052] The detection device 235 includes an optical assembly 237 for processing and modifying the generated light 236, and a sensor device 242 for receiving the processed light 239 from the optical assembly 237. The optical assembly 237 includes one or more collecting optics 238, such as lenses for beam shaping of the generated light 236, and may include spatial filters and / or slit diaphragms, depending on the application. The optical assembly 237 may also include folding optics, such as mirrors and / or prisms. The optical assembly 237 includes a color separation device 240, which may be a set of passive optics for separating the generated light 236 into light portions 241_1, 241_2, 241_3, each having different wavelengths λ1, λ2, λ3. For example, the color separation device 240 may include a set of dichroic beam splitters or mirrors. In this way, the detection device 235 can distinguish the light 236 generated between each of the different wavelengths λ1, λ2, and λ3.

[0053] Referring also to FIG. 2D, the sensor device 242 includes a plurality of detectors 242_1, 242_2, and 242_3. Each detector is configured to detect light 236 generated at one of different wavelengths λ1, λ2, and λ3. This generated light 236 is generated from the interaction between the optical probe 230 and the target 205 in the detection area 231. Each detector 242_1, 242_2, and 242_3 may be a region or area of ​​a photodetector. For example, detector 242_1 may correspond to the first group of pixels in the photodiode array, detector 242_2 may correspond to the second group of pixels in the photodiode array, and detector 242_3 may correspond to the third group of pixels in the photodiode array. In other embodiments, each detector 242_1, 242_2, 242_3 may correspond to a single and distinct photodiode or photodiode array.

[0054] The outputs 243_1, 243_2, and 243_3 of each of the individual detectors 242_1, 242_2, and 242_3 are provided to the control device 250 for analysis. If the detector is a photodetector, the outputs 243_1, 243_2, and 243_3 correspond to the amplitude of the photocurrent generated by the light interacting with the active region of the other detector over time. This photocurrent is proportional to the intensity of the absorbed (or incident) light over a wide range of optical power. Furthermore, the use of photodetectors enables high-speed detection, as fast as the target 205 is being generated, and thus allows the control device 250 to perform analysis on each target 205 interacting with the optical probe 230.

[0055] As shown in Figure 2E, the respective outputs 243_1, 243_2, and 243_3 of detectors 242_1, 242_2, and 242_3 are shown in relation to the interaction in Figure 2B. Specifically, and for example, in Figure 2B, target 205 is primarily aligned with the focal point Y_2 of the probe beam 230_2. Therefore, output 243_2 of detector 242_2 has a higher amplitude than output 243_1 of detector 242_1 and output 243_3 of detector 242_3.

[0056] As another example, in Figure 2F, target 205 has traveled along the -Y direction and is now more closely aligned with the focal point Y_1 of the probe beam 230_1. Figure 2G shows the respective outputs 243_1, 243_2, and 243_3 of detectors 242_1, 242_2, and 242_3 for the positioning of target 205 in Figure 2F. As shown, the amplitude of output 243_1 at detector 242_1 is the largest. In addition, since target 205 is offset from Y=0, the output 243_3 at detector 242_3 is smaller than the output 243_2 at detector 242_2.

[0057] The control device 250 can determine the position of the target 205 along the Y direction by analyzing the ratios of these output signals relative to each other. For example, the control device 250 can analyze the ratio R12 of output 243_1 to output 243_2, the ratio R32 of output 243_3 to output 243_2, or the ratio R13 of output 243_1 to output 243_3.

[0058] In the embodiment of FIG. 2A, one or more operational beams 220 are generated by the operational light source 221. The one or more operational beams 220 extend generally along a direction parallel to the Z-axis, such that the operational beams 220 interact with the target 205 in the target region 215 downstream of the detection region 231. In this embodiment, the optical probe 230 and the detection beams 230_1, 230_2, 230_3 propagate in a direction not parallel to the direction of the operational beams 220. For example, the optical probe 230 (and the detection beams 230_1, 230_2, 230_3) may be perpendicular to the direction of the operational beams 220. In addition, the target 205 is generated by the target supply device 206. Based on the analysis of the output from the detection device 235 by the control device 250, one or more of the target supply device 206 and the operational light source 221 receive instructions from the control device 250 for adjustment 260. Specifically, the control device 250 determines the positioning information (e.g., positioning) of the target 205 along the Y-axis of the X, Y, Z coordinate system. Furthermore, the control device 250 can determine whether and how to adjust the target supply device 206 and / or the operating light source 221 to account for the drift of the target 205 along the Y-axis, thereby ensuring that the target 205 enters the target area 215 at the appropriate time and position to interact with one or more operating beams 220, thereby efficiently generating EUV light.

[0059] Referring to FIG3A, another embodiment 300 of the measurement system 100 is shown. In the measurement system 300, the probe optical axis 330OA is parallel to the Z-axis of the X, Y, Z coordinate system, such that the probe optical axis 330OA intersects the target axial path 310. Therefore, in the measurement system 300, the optical probe 330 travels along the Z-axis at least in the detection area 331.

[0060] The measurement system 300 includes a light-emitting device 325 that generates an optical probe 330. The optical probe 330 is a light beam with a lateral color change. That is, the color change extends along a direction perpendicular to the direction along which the optical probe 330 travels. In this example, the color change extends along the Y-axis. The lateral color change of the optical probe 330 enables the measurement of changes in the positioning of the target 305 along the Y-axis, because the wavelength distribution in the generated light 336 changes as the target 305 moves along the Y-axis.

[0061] For this purpose, the measurement system 300 includes: a detection device 335 configured to receive generated light 336; and a control device 350 configured to receive output from the detection device 335, analyze the output, and determine positioning information of the target 305 along the X and Y directions. The control device 350 may further influence adjustments 360 to one or more characteristics related to one or more of the target 305 and the target axial path 310 based on the determined positioning information of the target 305 along the X-axis and X-axis (based on the analysis of the detected generated light 336). Adjustments 360 may be made to one or both of the operating light source 321 (thereby changing the state of the operating beam 320 relative to one or more of the target 305) and the target supply device 306 that generates the target 305, thereby adjusting the state related to how the target 305 is generated. In this way, the control device 350 controls the trajectory of the target 305 and the timing of the target's arrival at the target area 315, so that the pulse of the operating beam 305 irradiates the target 305 at the target area 315 and effectively generates EUV light.

[0062] Referring to Figures 3B and 3C, the optical probe 330 has a lateral range along the Y-axis, and furthermore, there is a color variation along this lateral range. In this particular embodiment, for simplicity, the color variation of the optical probe 330 across its respective portions 330_1, 330_2, 330_3, 330_4, and 330_5 represents five different wavelengths λ1, λ2, λ3, λ4, and λ5. However, there may be fewer or more than five different wavelengths. Furthermore, the color variation may be at a different center wavelength (as shown in Figure 3C); or alternatively, the color variation may be a continuous variation of wavelength within the lateral range.

[0063] The detection device 335 includes a color separation device 340, which may be a set of passive optical devices for separating the generated light 336 into light portions 341_1, 341_2, 341_3, 341_4, and 341_5, each portion having a different wavelength λ1, λ2, λ3, λ4, and λ5. The color separation device 340 converts wavelength separation into spatial separation. For example, the color separation device 340 may include a set of dichroic beam splitters or mirrors. As another example, the color separation device 340 includes a dispersive element such as a grating (which may be transmissive or reflective) or a dispersive optical element such as a prism. In this way, the detection device 335 can distinguish the generated light 336 between each of the different wavelengths λ1, λ2, λ3, λ4, and λ5.

[0064] The detection device 335 also includes a sensor device 342 that receives the processed light portions 341_1, 341_2, 341_3, 341_4, and 341_5. The sensor device 342 includes a plurality of detectors 342_1, 342_2, 342_3, 342_4, and 342_5, each detector being configured to detect light 336 generated at one of different wavelengths λ1, λ2, λ3, λ4, and λ5, such generated light 336 arising from the interaction between the optical probe 330 and the target 305 in the detection area 331. The sensor device 342 may further include a color beam separation system, such as a dispersive element (e.g., a grating or prism), or a series of dichroic filters or beam splitters, or a single-unit filter configuration.

[0065] Each detector 342_1, 342_2, 342_3, 342_4, and 342_5 may be a region or area of ​​a photodetector. For example, detector 342_1 may correspond to the first group of pixels in the photodiode array, detector 342_2 may correspond to the second group of pixels in the photodiode array, detector 342_3 may correspond to the third group of pixels in the photodiode array, detector 342_4 may correspond to the fourth group of pixels in the photodiode array, and detector 342_5 may correspond to the fifth group of pixels in the photodiode array. In other embodiments, each detector 342_1, 342_2, 342_3, 342_4, and 342_5 may correspond to a single and distinct photodiode or photodiode array.

[0066] In the example shown in Figure 3C, the target 305 interacts with a portion 330_3 of the optical probe 330. In this example, the target 305 is fairly well aligned with the X-axis and does not travel too far along the Y-axis. The generated light 336 will therefore have a dominant wavelength λ3, and the signal associated with wavelength λ3 will dominate the overall signal analyzed by the detection device 335. Therefore, the amplitude and power of the light portion 341_3 are much larger than those of the other light portions, and the signal at the detector 342_3 is much larger than the signal at the other detectors.

[0067] Figures 4A to 4C illustrate the light 336 generated by the target 305 at different positions along the Y-axis. For example, in Figure 4A, the target 305 is offset along the -Y direction, causing the target 305 to interact with part 330_4, and the dominant wavelength λ4 is reflected as the generated light 336 to the detection device 335. Therefore, detector 342_4 senses the maximum amplitude of the light, while other detectors sense the relatively smaller amplitude of the light. In Figure 4B, the target 305 is offset along the +Y direction, causing the target 305 to interact with part 330_2, and the dominant wavelength λ2 is reflected as the generated light 336 to the detection device 335. Therefore, detector 342_2 senses the maximum amplitude of the light, while other detectors sense the relatively smaller amplitude of the light. In Figure 4C, target 305 is significantly offset along the -Y direction, causing target 305 to interact with part 330_5, and the dominant wavelength λ5 is reflected as the generated light 336 to the detection device 335. Therefore, detector 342_5 senses the maximum amplitude of the light, while other detectors sense the relatively smaller amplitude of the light.

[0068] In some embodiments, the optical probe 305 may be a broadband optical probe beam, which is a beam with a continuous spectrum across the Y-axis. In this example, the light-emitting device 325 may include a single broadband light source generating the optical probe 305. In other embodiments, the optical probe 305 may consist of a plurality of probe beams, each probe beam having a different center wavelength. In this example, the light-emitting device 325 may include a plurality of physically dissimilar light sources, each light source generating a probe beam with a different center wavelength. In other embodiments, the light-emitting device 325 may be a supercontinuum light source, which converts laser light into light with an extremely wide spectral bandwidth to generate an ultra-wide continuous spectrum. The light-emitting device 325 may use prisms and / or gratings to achieve color separation. Furthermore, the design of the light-emitting device 325 may include an evaluation of physical distance (the distance the optical probe 305 must travel to reach the detection area 331) and signal level to determine parameters of the components used to generate the optical probe 305, such as magnification and numerical aperture.

[0069] The detection device 335 can be implemented in any suitable manner, such as a linear sensor array having a grating for converting the wavelength of the generated light 336 into spatial separation. The detection device 335 may include a camera pixel array with an integrated color filter, or may include a plurality of photodiodes with a dichroic coating.

[0070] Figure 5 illustrates an embodiment 500 of the measurement system 300. Similar to the measurement system 300, in the measurement system 500, the probe optical axis 530OA is parallel to the Z-axis of the X, Y, Z coordinate system, such that the probe optical axis 530OA intersects the target axial path 510. Therefore, in the measurement system 500, the optical probe 530 travels along the Z-axis at least in the detection area 531.

[0071] The measurement system 500 includes a light-emitting device 525 that generates an optical probe 530. The optical probe 530 is a light beam with a lateral color change projected onto the target axial path 510. That is, the color change extends along a direction perpendicular to the direction along which the optical probe 530 travels. In this example, the color change extends along the Y-axis (as shown in Figures 3B and 3C). The lateral color change of the optical probe 530 enables the measurement of changes in the positioning of the target 505 along the Y-axis, because the wavelength distribution in the generated light 536 changes as the target 505 moves along the Y-axis.

[0072] For this purpose, the measurement system 500 includes: a detection device 535 configured to receive generated light 536; and a control device 550 configured to receive output from the detection device 535, analyze the output, and determine positioning information of the target 505 along the X and Y directions. The control device 550 may further influence adjustments 560 to one or more characteristics related to one or more of the target 505 and the target axial path 510 based on the determined positioning information of the target 505 along the X-axis and X-axis (based on the analysis of the detected generated light 536). Adjustments 560 may be made to one or both of the operating light source 521 (thereby changing the state of the operating beam 520 relative to one or more of the target 505) and the target supply device 506 that generates the target 505, thereby adjusting the state related to how the target 505 is generated. In this way, the control device 550 controls the trajectory of the target 505 and the timing of the target's arrival at the target area 515, so that the pulse of the operating beam 505 irradiates the target 305 at the target area 515 and effectively generates EUV light.

[0073] In this embodiment, the light-emitting device 525 includes: a broadband light source 526 that generates a broadband light beam 526b having all wavelengths of interest; a color-forming optics element 527; and an imaging optics element 528. The color-forming optics element 527 separates the broadband light beam 526b into probe beams 530_1, 530_2, 530_3, 530_4, and 530_5, each probe beam being at a different center wavelength λ1, λ2, λ3, λ4, and λ5. In some embodiments, the imaging optics element 528 includes a cylindrical focusing optics element (such as a cylindrical lens) in the path of the probe beams 530_1, 530_2, 530_3, 530_4, and 530_5, the cylindrical focusing optics element being configured to form different focal points along the Y-axis at the detection region 531 as an optical screen. In other embodiments, the imaging optics 528 includes a collimating optics element for one of the paths of the probe beams 530_1, 530_2, 530_3, 530_4, and 530_5, configured to collimate the probe beams 530_1, 530_2, 530_3, 530_4, and 530_5 at the probe region 531. In other embodiments, the imaging optics 528 images the probe beams 530_1, 530_2, 530_3, 530_4, and 530_5 onto the probe region 531. That is, the imaging optics 528 delivers an image of each probe beam to the probe region.

[0074] In this embodiment, the optical probe 530 (collectively referred to as probe beams 530_1, 530_2, 530_3, 530_4, and 530_5) travels along a path parallel to the operating axis in the probe region 531. This operating axis is defined by the direction along which one or more operating beams 520 travel in the target region 515. Furthermore, the optical probe 530 can interact with at least some of the optical elements 523 (which may be referred to as operating optical elements). For example, this can be achieved if the operating optical elements have an operating range covering the center wavelengths λ1, λ2, λ3, λ4, and λ5 of the optical probe 530. The optical probe 530 also passes through an EUV light collector (such as a mirror) 524 along a path parallel to the operating beams 520.

[0075] The generated light 536 may be the portion of the optical probe 530 reflected from the target 505. Furthermore, the generated light 536 may be reflected back along the operating axis within the detection area 531. In this way, the generated light 536 also interacts with at least some of the operating optical elements. The optical probe 530 is coupled into the operating optical path by means of a beam splitter 522, and the generated light 536 is coupled out of the operating optical path by means of the beam splitter 522. The beam splitter 522 may be a color splitter, such that the generated light 536 is transmitted, for example, and the optical probe 530 is reflected.

[0076] Although the optical probe 530 and the generated light 536 interact with at least some of the operating optical elements 523 in the measurement system 500, the optical probe 530 and / or the generated light 536 may follow a path completely different from that of the operating optical elements 523.

[0077] As discussed above, the detection device 535 includes a color separation device 540, which may be a set of passive optical devices 540_1, 540_2, 540_3, 540_4, 540_5 configured to separate the generated light 536 into light portions 541_1, 541_2, 541_3, 541_4, 541_5, each portion having a different wavelength λ1, λ2, λ3, λ4, λ5. In this embodiment, the optical devices 540_1, 540_2, 540_3, 540_4, 540_5 are dichroic beam splitters or mirrors. In this way, the detection device 535 can distinguish the generated light 536 between each of the different wavelengths λ1, λ2, λ3, λ4, λ5.

[0078] The detection device 535 also includes a sensor device 542, which receives the processed light portions 541_1, 541_2, 541_3, 541_4, and 541_5. In fact, the relative size of the light portions 541_1, 541_2, 541_3, 541_4, and 541_5 will indicate the position of the target 505 along the Y-axis, while the overall signal or amplitude of all the light portions 541_1, 541_2, 541_3, 541_4, and 541_5 will indicate the position of the target 505 along the X-axis. The sensor device 542 includes a plurality of detectors 542_1, 542_2, 542_3, 542_4, and 542_5. Each detector is configured to detect a portion of light 536 generated at one of different wavelengths λ1, λ2, λ3, λ4, and λ5. This generated light 536 is generated from the interaction between the optical probe 530 and the target 505 in the detection area 531. Each detector 542_1, 542_2, 542_3, 542_4, and 542_5 can be a region or area of ​​a photodetector. For example, detector 542_1 may correspond to the first group of pixels in the optical diode array, detector 542_2 may correspond to the second group of pixels in the optical diode array, detector 542_3 may correspond to the third group of pixels in the optical diode array, detector 542_4 may correspond to the fourth group of pixels in the optical diode array, and detector 542_5 may correspond to the fifth group of pixels in the optical diode array. In other embodiments, each detector 542_1, 542_2, 542_3, 542_4, and 542_5 may correspond to a single and distinct optical diode or optical diode array.

[0079] In other embodiments, the generated light 536 may be separated from the optical probe 530 using polarization management instead of a beam splitter 522. For example, this polarization management may include a polarized beam splitter system, with a polarizer preceding it and a quarter-wave plate following it, to generate and separate rotatingly polarized beams with different chiralities.

[0080] Referring to FIG6, embodiment 600 of the measurement system 100 is incorporated into the EUV light source 670. In operation, the EUV light source 670 supplies an EUV beam 671 to an output device 672, which may be a lithography exposure device. The EUV light source 670 includes a vacuum chamber 673 defining: a first target space, where each target 605 interacts with a first operating beam 620A to form a modified target 605m; and a second target space, where each modified target 605m interacts with a second operating beam 620B. The first and second target spaces are located within a target region 615.

[0081] The light-emitting device 625 and the detection device 635 are configured to interact with the target 605 in the detection area 631 before the target enters the target area 615.

[0082] The EUV light source 670 includes an EUV light collector (such as a mirror) 624 spatially disposed relative to the second target. The EUV light collector 624 collects EUV light 674 emitted from plasma 675 generated when the modified target 605m interacts with the second operating beam 620B. The EUV light collector 624 redirects the collected EUV light 674 as an EUV beam 671 toward the output device 672. The EUV light collector 624 may be a reflective optics device, such as a curved mirror, capable of reflecting light having an EUV wavelength (i.e., EUV light 674) to form the generated EUV beam 671.

[0083] The EUV light source 670 includes a target supply device 606 that forms a stream of target 605 directed to a first target space for interaction with a first operating beam 620A. Target 605 is formed from target material that generates EUV light 674 when in a plasma state (e.g., after interaction with a second operating beam 620B). The first target space is, for example, the location where target 605 is in a plasma state. The target supply device 606 includes a reservoir 607 that defines a hollow interior configured to contain fluid target material. The target supply device 606 includes a nozzle structure 608 having an opening (or orifice) 609 at one end in fluid communication with the interior of the reservoir 607. Target material in a fluid state under pressure P (and other possible forces, such as gravity) flows from the interior of the reservoir 607 and through the opening 609 to form the stream of target 605. The trajectory of the target 605 ejected from the opening 609 (target axial path 610) generally extends along the -X direction, but as discussed above, the trajectory of the target 605 may include components along a plane perpendicular to the -X direction (i.e., Y and Z components).

[0084] Each modified target 605m is at least partially or primarily converted into plasma through its interaction with pulses in the second operating beam 620B generated by the operating light source 621, the interaction occurring in the second target space. As discussed above, each target 605 is a target mixture comprising target material and, where applicable, impurities (such as non-target particles). Target 605 may be, for example, a droplet of liquid or molten metal, a portion of a liquid stream, a solid particle or cluster, solid particles contained within a droplet, a foam of target material, or solid particles contained within a portion of a liquid stream. Target 605 may include, for example, water, tin, lithium, xenon, or any material having an emission spectrum in the EUV range when converted to a plasma state. For example, target 605 may include elemental tin, which may be used as pure tin (Sn); as tin compounds, such as SnBr4, SnBr2, SnH4; as tin alloys, such as tin-gallium alloys, tin-indium alloys, tin-indium-gallium alloys, or any combination of such alloys.

[0085] The EUV light source 670 may include a dedicated controller 678 that communicates with the control device 650 and other components of the EUV light source 670, such as the target supply device 606. Alternatively, the control device 650 may be part of the controller 678.

[0086] The X, Y, Z coordinate system of the EUV light source 670 can be fixed or determined based on the configuration of the vacuum chamber 673. For example, the chamber 673 may be defined by a set of walls, and three points on one or more walls of the chamber 673 or within the space of the chamber 673 can provide a reference for its X, Y, Z coordinate system. It is possible to fix one or more components of the light-emitting device 625 and the detection device 635 to one or more walls of the chamber 673.

[0087] The EUV light source 670 may further include other measuring devices not shown in the figures. For example, the EUV light source 670 may include a coarse target turning camera and a fine target turning camera positioned to view the target 605 as it moves toward the first target space, the turning cameras communicating with the controller 678. The controller 678 may analyze data from the turning cameras to determine the position of the target 815 in one or more of the Y and Z directions. As another example, the EUV light source 670 may include a set of sensors configured and configured to detect or sense the EUV light 674; this information about the EUV light 674 may be analyzed by the controller 678 for other configurations or controls of the EUV light source 670.

[0088] Referring to FIG7, the measurement system 100 (which may be measurement system 200, 300 or 500) executes program 780. The measurement system 100 generates an optical probe 130, as described above (781). The optical probe 130 is guided as a screen to cross the target axial path 110 along the X-lateral direction (which may be in the YZ plane). When the target 105 crosses the screen of the optical probe 130 (and interacts with the optical probe 130), light 136 is generated and then detected (782). Specifically, the detection device 135 detects the generated light 136 at a plurality of different wavelengths, wherein each wavelength is associated with a different position along the X-lateral direction of the X, Y, Z coordinate system. The control device 150 analyzes this detected light and determines the target-related positioning information along the X-axis and also along the X-lateral axis (783). The control device 150 determines, based on the determined positioning information (783), whether the target 105 is on the required trajectory (or target axial path 110) to the target area 115 (784). If the target 105 is not on the required trajectory (784), the control device 150 affects the adjustment 160 (785) of one or more characteristics related to one or more of the target 105 and the target axial path 110 based on the determined positioning information of the target 105 along the X-axis and also along the X-axis. The control device 150 may also perform other analyses, such as calculating the time when the target 105 will arrive at the target area 115 (786), and also send a signal to the operating light source (such as 221, 331), which instructs the operating light source 221, 331 to generate the pulse at the time when the pulse of the operating beam 220 arrives at the target area 115 simultaneously with the target 105 in question (787). The control device 150 may also use information obtained for diagnostic purposes to form a long-term prediction of the components or stability of the EUV light source 670 over time.

[0089] The flowchart shown in Figure 7 only illustrates the actions related to a single target 105. In reality, the target supply devices 206 and 306 continuously generate targets 105 as described above. Furthermore, since there is a series of consecutive targets 105, there will similarly be a series of consecutive flashes of light 136 detected at the detection device 135, and a series of timing signals generated at the detection device 135 and analyzed by the control device 150. This causes the operating light sources 221 and 321 to emit a series of pulses and irradiate a series of targets 105 at the target area 115 to generate EUV light 674. In addition, the control device 150 also operates in a feedforward manner (i.e., before the target 105 reaches the target area 115) to sequentially influence the adjustment 160 of each target 105. This allows the target 105 to be adjusted before it reaches the target area 115.

[0090] The embodiments may be further described using the following clauses: 1. A measurement system comprising: a light-emitting device configured to generate an optical probe including light having a plurality of different wavelengths, the optical probe including different wavelengths of light propagating along a probe optical axis, the probe optical axis intersecting a target axial path at a detection region; a detection device configured to detect the generated light at a plurality of different wavelengths, the generated light being generated from the interaction between the optical probe and a target traveling along the target axial path in the detection region; and a control device communicating with the detection device, the control device configured to analyze the detected light and adjust one or more characteristics related to one or more of the target and the target axial path based on the analysis. 2. The measurement system of clause 1, wherein the light-emitting device comprises: one or more optical sources configured to generate a plurality of probe beams as optical probes, each probe beam propagating along a probe optical axis intersecting the target axial path and each probe beam having a different center wavelength. 3. A measurement system as described in clause 2, wherein each probe beam having a different center wavelength is focused at a different location along a probe optical axis and within a detection region. 4. A measurement system as described in clause 1, wherein the light-emitting device comprises: one or more optical sources configured to generate a probe beam as an optical probe, the probe beam propagating along a probe optical axis intersecting a path along the target axis and the probe beam being defined by a continuous spectrum of center wavelengths. 5. A measurement system as described in clause 1, wherein the optical probe has different focal points along the probe optical axis and within a detection region. 6. A measurement system as described in clause 5, further comprising a cylindrical focusing optics in the path of the optical probe, the cylindrical focusing optics being configured to form different focal points along a direction perpendicular to the probe optical axis as an optical screen for the optical probe. 7. A measurement system as described in clause 1, wherein the optical probe is collimated or imaged along the probe optical axis at a detection region. 8. A measurement system as described in Clause 1, wherein the detection device comprises: a plurality of detectors, each detector configured to detect light generated by the interaction between a respective probe beam from an optical probe and a target. 9. A measurement system as described in Clause 8, wherein each detector is configured to detect a portion of a respective probe beam incident on the target. 10. A measurement system as described in Clause 9, wherein each detector configured to detect the portion of a respective probe beam incident on the target includes each detector configured to detect a portion of the respective probe beam reflected or scattered from the target. 11. A measurement system as described in Clause 8, wherein each detector is configured to detect generated light having a wavelength different from the wavelength of the generated light detected by the other detectors. 12. A measurement system as described in Clause 1, wherein the detection device is configured to distinguish generated light between each of the different wavelengths. 13. A measurement system as described in clause 1, wherein the generated light travels along a path that is different from the probe optical axis and also different from the target axial path.14. A measurement system of claim 1, wherein the generated light travels along a path parallel to an operating axis defined by the direction along which one or more operating beams travel, and the one or more operating beams interact with a target in a target region downstream of the detection zone. 15. A measurement system of claim 14, wherein the generated light is a portion of the detection beam reflected back from the target along the operating axis. 16. A measurement system of claim 15, wherein the generated light interacts with at least some of the same optics that interact with one or more operating beams. 17. A measurement system of claim 1, wherein the detection zone is upstream of the target region where the target interacts with one or more operating beams, along a target axial path. 18. A measurement system of claim 17, wherein the target axial path extends at least along the X-axis, and the detection optical axis is not parallel to the X-axis. 19. A measurement system of claim 18, wherein a control device is configured to determine the positioning of the target along a Y-direction perpendicular to the X-axis. 20. A measurement system of clause 19, wherein the probe optical axis is parallel to the Y-axis and the operating beam travels generally along the Z-axis. 21. A measurement system of clause 20, wherein light having a plurality of wavelengths has a range such that the wavelength of the light changes along the Y-axis. 22. A measurement system of clause 19, wherein the probe optical axis is perpendicular to the Y-axis. 23. A measurement system of clause 22, wherein light having a plurality of wavelengths extends such that the wavelength of the light changes along the Y-axis. 24. A measurement system of clause 17, wherein one or more operating beams include: a first amplified beam configured to interact with a target to modify the shape and movement of the target, thereby forming a modified target; and a second amplified beam configured to interact with the modified target, thereby converting the modified target into plasma emitting extreme ultraviolet light. 25. A measurement system as described in Clause 1, wherein the control device is configured to adjust one or more characteristics relating to one or more of the target and the target axial path, including one or more of the following: the control device is configured to instruct a target material supply to adjust one or more states relating to the generation of the target; and the control device is configured to instruct an operating light source to adjust one or more states relating to the generation of one or more operating beams, which interact with the target in a target area downstream of the detection zone. 26. A measurement system as described in Clause 1, wherein the detection device is configured to detect light generated at a rate as fast as or faster than the rate at which the target passes through the detection zone, at a rate that is equal to or faster than the rate at which the target passes through the detection zone, and the control device is configured to influence the adjustment of one or more characteristics relating to the target, the analysis of the target being based on one or more characteristics.27. A measurement system as described in clause 26, wherein a control device is configured to adjust one or more characteristics related to a target, including the control device being configured to instruct an operating light source to adjust the direction of one or more operating beams interacting with a target in a target area downstream of the detection area, the adjustment of the direction being relative to the Z-axis of an X, Y, Z coordinate system, wherein the target axial path extends primarily along the X-axis, and the detection optical axis is aligned with the Y-axis or the Z-axis. 28. An extreme ultraviolet (EUV) light system comprising: a target supply device configured to form a target stream directed to a target area, each target traveling along a target axial path extending primarily along the X-axis of an X, Y, Z coordinate system; an operating optical source configured to generate one or more operating beams directed to the target area, at least one operating beam configured to interact with a target to form a modified target; and a measurement system comprising: a light-emitting device configured to generate an optical probe propagating along a detection optical axis that intersects the target axial path at the detection area; A detection device configured to detect light generated at a plurality of different wavelengths, each wavelength being associated with a different position along the X-axis of an X, Y, Z coordinate system, the generated light arising from the interaction between an optical probe and a target traveling along a target axial path within a detection zone; and a control device communicating with the detection device, the control device being configured to analyze the detected light and determine target-related positioning information along the X-axis of the X, Y, Z coordinate system. 29. An EUV light system as described in clause 28, wherein one or more operating beams include: a first amplified beam configured to interact with a target to modify the shape and movement of the target, thereby forming a modified target; and a second amplified beam configured to interact with the modified target, thereby converting the modified target into plasma emitting extreme ultraviolet light. 30. A measurement system comprising: a light-emitting device configured to generate an optical probe propagating along a detection optical axis, the detection optical axis intersecting a target axial path at a detection area, the target axial path extending primarily along the X-axis of an X, Y, Z coordinate system; a detection device configured to detect a plurality of generated light at different wavelengths, each wavelength associated with a different position along the X-axis of the X, Y, Z coordinate system, the generated light arising from the interaction between the optical probe and a target traveling along the target axial path in the detection area; and a control device in communication with the detection device, the control device configured to analyze the detected light and determine target-related positioning information along the X-axis of the X, Y, Z coordinate system. 31. The measurement system of claim 30, wherein the optical probe is a broadband optical probe. 32. A measurement system as described in clause 30, wherein the control device is configured to determine, based on the analysis of detected light, positioning information relating to the target along the X-axis of the X, Y, Z coordinate system.

[0091] Other embodiments are within the scope of the claims. [Simplified Explanation of the Diagram]

[0022] Figure 1 is a block diagram of a measurement system, which includes a light-emitting device that generates an optical probe that is guided to the detection area through which the target passes, a detection device that detects the light generated from the detection area, and a control device configured to determine the positioning information of the target from which the light is generated.

[0023] Figure 2A is a block diagram of an embodiment of the measurement system of Figure 1, wherein the detection optical axis of the optical probe is parallel to the Y-axis of the X, Y, Z coordinate system;

[0024] Figure 2B is a schematic diagram of the detection area of ​​the measurement system in Figure 2A, wherein the target travels along the -X direction and does not deviate from Y=0, and the optical probe includes three detection beams;

[0025] Figure 2C is a schematic diagram illustrating the detection device of the measurement system in Figures 2A and 2B;

[0026] Figure 2D is a front view of an embodiment of the sensor device of the detection device in Figure 2C. The sensor device includes a plurality of detectors, wherein each detector is configured to detect light generated at one of different wavelengths λ1, λ2, and λ3.

[0027] Figure 2E is a set of graphs, where each graph corresponds to the output of each detector from the sensor device in Figures 2C and 2D for the target located as shown in Figure 2B;

[0028] Figure 2F is a schematic diagram showing the detection area of ​​the measurement system in Figure 2A, where the target is offset from Y=0;

[0029] Figure 2G is a set of curves, where each curve corresponds to the output of each detector from the sensor device of Figures 2C and 2D for the target located as shown in Figure 2F;

[0030] Figure 3A is a block diagram of an embodiment of the measurement system in Figure 1, wherein the detection optical axis of the optical probe is parallel to the Z-axis of the X, Y, Z coordinate system, such that the detection optical axis intersects with the target axial path;

[0031] Figure 3B is a schematic diagram of the detection area of ​​the measurement system of Figure 3A, wherein the target travels along the -X direction and does not deviate from Y=0, and the optical probe has a lateral range along the Y axis, and in addition, there is a color change along this lateral range.

[0032] Figure 3C is a schematic diagram showing the detection area of ​​the measurement system of Figures 3A and 3B, including a block diagram of an embodiment of the detection device;

[0033] Figures 4A to 4C are schematic illustrations of the detection area of ​​the measurement system of Figures 3A to 3C, wherein the target interacts with the optical probe at different positions along the Y-axis, and the detection device is configured to capture these differences in position along the Y-axis.

[0034] Figure 5 is a schematic illustration of an embodiment of the measuring device of Figure 3A, wherein an optical probe (collectively referred to as a probe beam) travels along a path parallel to the operating axis in the probe area, the operating axis being defined by the direction along which one or more operating beams travel in the target area.

[0035] Figure 6 is a block diagram of an extreme ultraviolet (EUV) light source in an embodiment of the measurement system of Figure 1. When in operation, the EUV light source supplies an EUV beam to an output device, which may be a photolithography device; and

[0036] Figure 7 is a flowchart of the procedure executed by the measurement system of Figure 1, Figure 2A or Figure 3A for determining positioning information related to a target along the X-axis and also along the X-horizontal axis.

Claims

1. A measurement system comprising: a light-emitting device configured to generate an optical probe including light having a plurality of dissimilar wavelengths, the optical probe including the dissimilar wavelengths of the light propagating along a probe optical axis, the probe optical axis intersecting a target axial path at a detection region; a detection device configured to detect the generated light at the plurality of dissimilar wavelengths, the generated light being generated from an interaction between the optical probe and a target traveling along the target axial path in the detection region; and a control device communicating with the detection device, the control device configured to analyze the detected light and, based on the analysis, adjust one or more characteristics relating to one or more of the target and the target axial path.

2. The measurement system of claim 1, wherein the light-emitting device comprises: one or more optical sources configured to generate a plurality of probe beams as the optical probe, each probe beam propagating along the probe optical axis intersecting the axial path of the target and each probe beam having a different center wavelength.

3. The measurement system of claim 2, wherein each probe beam having a different central wavelength is focused along the probe optical axis and at a different position within the probe region.

4. The measurement system of claim 1, wherein the light-emitting device comprises: one or more optical sources configured to generate a probe beam as the optical probe, the probe beam propagating along the probe optical axis intersecting the axial path of the target and the probe beam being defined by a continuous spectrum of one of the center wavelengths.

5. The measurement system of claim 1, wherein the optical probe has a discontinuous focal point along the detection optical axis and within the detection region.

6. The measurement system of claim 5, further comprising a cylindrical focusing optic in the path of the optical probe, the cylindrical focusing optic configured to form the dissimilar focal point along a direction perpendicular to the probe optical axis as an optical screen of the optical probe.

7. The measurement system of claim 1, wherein the optical probe is collimated or imaged along the detection optical axis at the detection area.

8. The measurement system of claim 1, wherein the detection device comprises: a plurality of detectors, each detector configured to detect light generated by the interaction between a separate probe beam from one of the optical probes and the target.

9. The measurement system of claim 8, wherein each detector is configured to detect a portion of the individual probe beam incident on the target.

10. The measurement system of claim 9, wherein the portion of the individual probe beam incident on the target by each detector includes the portion of the individual probe beam reflected from or scattered from the target by each detector.

11. The measurement system of claim 8, wherein each detector is configured to detect generated light having a wavelength different from that of the generated light detected by the other detectors.

12. The measurement system of claim 1, wherein the detection device is configured to distinguish the light produced between each of the dissimilar wavelengths.

13. The measurement system of claim 1, wherein the generated light travels along a path that is different from the probe optical axis and also different from the target axial path.

14. The measurement system of claim 1, wherein the generated light travels along a path parallel to an operating axis defined by a direction along which one or more operating beams travel, the one or more operating beams interacting with the target in a target region downstream of the detection region.

15. The measurement system of claim 14, wherein the generated light is a portion of the probe beam reflected back from the target along the operating axis.

16. The measurement system of claim 15, wherein the generated light interacts with at least some of the same optical elements that interact with the one or more operating beams.

17. The measurement system of claim 1, wherein along the axial path of the target, the detection area is upstream of one of the target areas where the target interacts with one or more operating beams.

18. The measurement system of claim 17, wherein the axial path of the target extends at least along an X-axis, and the probe optical axis is not parallel to the X-axis.

19. The measurement system of claim 18, wherein the control device is configured to determine the positioning of the target along a Y direction perpendicular to the X-axis.

20. The measurement system of claim 19, wherein the probe optical axis is parallel to a Y-axis and the operating beams travel substantially along a Z-axis.

21. The measurement system of claim 20, wherein the light having the plurality of wavelengths has a range such that the wavelength of the light varies along the Y-axis.

22. The measurement system of claim 19, wherein the probe optical axis is perpendicular to the Y-axis.

23. The measurement system of claim 22, wherein the light has the plurality of wavelengths extended such that the wavelength of the light changes along the Y-axis.

24. The measurement system of claim 17, wherein the one or more operating beams include: A first amplified beam, configured to interact with the target to modify the shape and movement of the target, thereby forming a modified target; and a second amplified beam, configured to interact with the modified target, thereby converting the modified target into plasma emitting extreme ultraviolet light.

25. The measurement system of claim 1, wherein the control device is configured to adjust one or more characteristics relating to one or more of the target and the target axial path, including one or more of the following: the control device is configured to instruct a target material supply to adjust one or more states relating to the generation of the target; and the control device is configured to instruct an operating light source to adjust one or more states relating to the generation of one or more operating beams, the one or more operating beams interacting with the target in a target region downstream of the detection zone.

26. The measurement system of claim 1, wherein the detection device is configured to detect light generated at a plurality of different wavelengths at a rate as fast as or faster than the rate at which the target passes through the detection zone, and the control device is configured to influence the adjustment of one or more characteristics related to the target, the analysis of the target being based on the one or more characteristics.

27. The measurement system of claim 26, wherein the control device is configured to adjust one or more characteristics related to the target, including the control device being configured to instruct an operating light source to adjust the direction of one or more operating beams interacting with the target in a target area downstream of the detection area, the adjustment of the direction being relative to the Z-axis of an X, Y, Z coordinate system, wherein the axial path of the target extends primarily along an X-axis, and the detection optical axis is aligned with the Y-axis or the Z-axis.

28. An extreme ultraviolet (EUV) light system comprising: a target supply device configured to form a target stream directed to a target region, each target traveling along a target axial path extending primarily along an X-axis of an X, Y, Z coordinate system; an operational optical source configured to generate one or more operational beams directed to the target region, at least one operational beam configured to interact with the target to form a modified target; and a measurement system comprising: a light-emitting device configured to generate an optical probe propagating along a probe optical axis intersecting the target axial path at a probe region; A detection device configured to detect light generated at a plurality of different wavelengths, each wavelength being associated with a different position along the X-axis of the X, Y, Z coordinate system, the generated light arising from an interaction between the optical probe and a target traveling along the target axial path in the detection area; and a control device communicating with the detection device, the control device being configured to analyze the detected light and determine positioning information related to the target along the X-axis of the X, Y, Z coordinate system.

29. The EUV optical system of claim 28, wherein the one or more operating beams include: A first amplified beam, configured to interact with the target to modify the shape and movement of the target, thereby forming a modified target; and a second amplified beam, configured to interact with the modified target, thereby converting the modified target into plasma emitting extreme ultraviolet light.

30. A measurement system comprising: a light-emitting device configured to generate an optical probe propagating along a probe optical axis, the probe optical axis intersecting a target axial path at a detection region, the target axial path extending primarily along an X-axis of an X, Y, Z coordinate system; a detection device configured to detect a plurality of generated light at different wavelengths, each wavelength associated with a different position along a horizontal X-axis of the X, Y, Z coordinate system, the generated light arising from an interaction between the optical probe and a target traveling along the target axial path in the detection region; and a control device communicating with the detection device, the control device configured to analyze the detected light and determine positioning information related to the target along the horizontal X-axis of the X, Y, Z coordinate system.

31. The measurement system of claim 30, wherein the optical probe is a broadband optical probe.

32. The measurement system of claim 30, wherein the control device is configured to determine, based on the analysis of the detected light, positioning information relating to the target along the X-axis of the X, Y, Z coordinate system.

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