TW202107210A - Metrology apparatus and method using mechanical filter - Google Patents

Abstract

A metrology apparatus includes: a diagnostic apparatus configured to interact a diagnostic probe with a current target at a diagnostic region before the current target enters a target space; a detection apparatus; and a control system in communication with the detection apparatus. The detection apparatus includes: a light sensor having a field of view overlapping with the diagnostic region and configured to sense light produced from the interaction between the diagnostic probe and the current target at the diagnostic region; and a mechanical filter between the diagnostic region and the light sensor. The mechanical filter includes an optical beam reducer and an optical mask defining an aperture positioned between the optical beam reducer and the light sensor. The control system is configured to estimate a property of the current target based on the output from the light sensor.

Description

Metrology device and method using mechanical filter

The subject of the disclosure relates to metrology devices and the use of mechanical filters to distinguish between two types of light in extreme ultraviolet light sources.

In semiconductor lithography (or photolithography), manufacturing an integrated circuit (IC) includes performing various physical and chemical processes on a semiconductor (eg, silicon) substrate (which is also referred to as a wafer). A photolithography exposure device or scanner is a machine that applies a desired pattern to a target portion of a substrate. The wafer is irradiated by a beam extending in the axial direction, and the wafer is fixed to the stage so that the wafer extends substantially along a horizontal plane substantially orthogonal to the axial direction. The light beam may have a wavelength within the range of ultraviolet (UV) from about 10 nanometers (nm) to about 400 nm, and in particular, deep UV (deep UV) from about 100 nm to about 400 nm. DUV) or a wavelength in the extreme ultraviolet (EUV) range of less than about 100 nm (or about 50 nm or less, and including 13 nm). The light beam travels in the axial direction (which is orthogonal to the lateral plane along which the wafer extends).

Methods for generating EUV light include, but are not necessarily limited to, using emission lines in the EUV range to convert a material with an element (for example, xenon, lithium, or tin) into a plasma state. In one such method, often referred to as laser produced plasma ("LPP"), a target material (e.g., a small amount of material) can be irradiated with an amplified light beam that can be called a driving laser. In the form of drops, plates, ribbons, strings, or clusters) to generate the required plasma. For this process, plasma is usually generated in a sealed container such as a vacuum chamber, and various types of metrology equipment are used to monitor the plasma.

In some general aspects, the metrology device includes: a diagnostic device, which is configured to cause the diagnostic probe to interact with the current target at the diagnostic area before the current target enters the target space; a detection device; and a control system, which Communicate with the detection device. The detection device includes: a light sensor that has a field of view overlapping with the diagnostic area and is configured to sense light generated by the interaction between the diagnostic probe and the current target at the diagnostic area; and mechanical filtering Detector, which is between the diagnostic area and the light sensor. The mechanical filter includes a beam reducer and an optical shield that defines an aperture positioned between the beam reducer and the light sensor. The control system is configured to estimate the attributes of the current target based on the output from the light sensor.

Implementations can include one or more of the following features. For example, the mechanical filter can be configured to angularly separate the diagnostic light emitted from the diagnostic area and the non-diagnostic light emitted from the target space. The diagnostic light can be generated by the interaction between the current target and the diagnostic probe at the diagnostic area. Non-diagnostic light may include light emitted from plasma generated by a previous target in the target space. The lateral extent of the aperture can be approximately the same as or greater than the lateral extent of the diagnostic light in the plane of the optical shield, and the lateral extent of the optical shield can be greater than that of the optical shield. The lateral extent of the non-diagnostic light in the plane of the cover may be approximately the same as the lateral extent of the non-diagnostic light in the plane of the optical cover. The optical shield may be positioned such that non-diagnostic light emitted from the target space is substantially blocked by the optical shield, while the diagnostic light substantially passes through the aperture.

The mechanical filter may include an optical collimator between the diagnostic zone and the beam reducer. The beam reducer can be an afocal beam reducer and can be configured to be combined with an optical collimator to project finite objects to infinity. The components of the optical collimator and the beam reducer with a positive focal length closest to the optical collimator can be integrated into a single refractive element. The beam reducer can be configured to maintain the collimated state of the light.

The light sensor may include one or more of the following: a photodiode, a photocrystal, a light-dependent resistor, a photomultiplier tube, a multi-unit light receiver, a four-unit light receiver, and a camera.

The diagnostic probe may include at least one diagnostic beam, and the light sensor is configured to sense the diagnostic light generated by the interaction between the current target and the at least one diagnostic beam. The diagnostic light may include the diagnostic beam reflected from the current target, scattered from the current target, or blocked by the current target.

The detection device may include one or more of a spectral filter and a polarization filter.

The diagnostic probe may include a first diagnostic beam and a second diagnostic beam. The first diagnostic beam and the second diagnostic beam are each configured to interact with the current target before it enters the target space. Each interaction occurs at a different District and different time.

The beam reducer may include a refracting telescope, a reflecting telescope or a catadioptric telescope. The refracting telescope may include: a positive focal length lens configuration and a negative focal length lens configuration, which are separated by the sum of their focal lengths; or a pair of positive focal length lens configurations, which are separated by the sum of their focal lengths.

The beam reducer can be configured to reduce the lateral size of the illumination light by at least five times, at least ten times, at least twenty times, or about ten times.

The orifice may include a circular opening, an elliptical opening, a polygonal opening, or an elongated slit opening.

The detection device can be positioned outside the chamber of the extreme ultraviolet (EUV) light source, the diagnosis area can be inside the chamber, and the detection device can receive light from the chamber through the optical window in the wall of the chamber. The distance between the diagnostic area and the optical window may be about 200 to 500 times the size of the distance between the diagnostic area and the target space.

The detection device may include a focusing lens at the output end of the aperture, the focusing lens being configured to focus the sensed light onto the light sensor.

The orifice may have a range of at least 2 millimeters (mm). The orifice can be positioned to receive the diagnostic light at a location where the diagnostic light is collimated or non-convergent and non-divergent.

In another general aspect, the metrology method includes: interacting the diagnostic probe with the current target at the diagnostic area before the current target enters the target space; collecting the interaction between the diagnostic probe and the current target at the diagnostic area The diagnostic light generated, the collection also includes collecting the non-diagnostic light generated by the target space; collimating the diagnostic light and the non-diagnostic light; separating the diagnostic light and the non-diagnostic light from each other in angle, including reducing the diagnostic light and the non-diagnostic light Lateral range; after the diagnostic light and the non-diagnostic light have been angularly separated, the diagnostic light is sensed at the sensing area laterally displaced from the non-sensing area through which the non-diagnostic light passes; and the current is estimated based on the sensed diagnostic light The attributes of the target.

Implementations can include one or more of the following features. For example, the diagnostic probe can interact with the current target at the diagnostic area by causing one or more diagnostic beams to interact with the current target at the diagnostic area; and the diagnostic light can interact with the current target at the diagnostic area. One or more diagnostic beams are collected by reflection from the current target, scattering from the current target, or blocked by the current target.

The metrology method may further include filtering the diagnostic light based on one or more of its spectral properties and its polarization state.

The diagnostic area can be inside an airtight sealed chamber of an extreme ultraviolet (EUV) light source, and also includes collecting non-diagnostic light. Collecting diagnostic light can include receiving diagnostic light including non-diagnostic light transmitted through an optical window in the wall of the chamber .

The lateral extent of the diagnostic light and the non-diagnostic light can be reduced by reducing the lateral extent of the diagnostic light and the non-diagnostic light by five times, at least ten times, at least twenty times, or about ten times.

The metrology method may also include blocking or redirecting the non-diagnostic light at the non-sensing area. The lateral range of the diagnostic light and the non-diagnostic light can be reduced by one or more of the following: refracting the light and reflecting the light.

The metrology method may also include focusing the diagnostic light at the sensing area.

The lateral range of the diagnostic light and the non-diagnostic light can be reduced by maintaining the collimation state of the diagnostic light and the non-diagnostic light.

The metrology method may also include, after the diagnostic light and the non-diagnostic light are angularly separated from each other and before the diagnostic light is sensed, passing the diagnostic light through the aperture of the optical shield, the aperture having a range larger than the range of the diagnostic light .

Referring to FIG. 1, the metrology apparatus 100 is configured to estimate one or more attributes of the current target 105 c traveling along the trajectory TR toward the target space 110 within the environment 115. The metrology device 100 is configured to estimate the current target 105c by analyzing the light (referred to as the diagnostic light 120) generated by the interaction between the one or more diagnostic probes 125 and the current target 105c before the current target 105c enters the target space 110. At least one attribute of the target 105c (such as speed, bearing, velocity, direction). However, the non-diagnostic light 122 and the diagnostic light 120 are generated at the same time and similarly. This non-diagnostic light 122 may saturate the light sensor 130 in the metrology device 100 or may interfere with the operation of the light sensor 130 in the metrology device 100. Because of this, the non-diagnostic light 122 can reduce the accuracy of the analysis performed by the metrology device 100 and thus cause errors in the estimated attributes of the current target 105c.

The metrology apparatus 100 can more effectively and accurately estimate the attributes of the current target 105c because it can more effectively distinguish between the diagnostic light 120 and the non-diagnostic light 122. For this purpose, the metrology apparatus 100 includes a detection device 135, which includes a light sensor 130 and a light sensor 130 in the diagnostic area 145 (where the current target 105c interacts with the diagnostic probe 125) Between the mechanical filter 140. The mechanical filter 140 includes a beam reducer 150 and an opaque optical shield 155 defining a light-transmitting aperture 160. The aperture 160 is positioned between the beam reducer 150 and the light sensor 130. In order to properly sense the diagnostic light 120, the light sensor 130 is positioned so that its field of view overlaps the diagnostic area 145. The measurement device 100 also includes a diagnosis device 165 that generates a diagnosis probe 125 and a control system 170 that communicates with the detection device 135. The control system 170 receives output from the sensor 130 and performs analysis on this output to estimate one or more attributes of the current target 105c.

The mechanical filter 140 includes an optical collimator 142 that forms the corresponding collimated light beams from the diagnostic light 120 and the non-diagnostic light 122, and then the beam reducer 150 optically reduces the size of these collimated light beams to form reduced-size collimators. Straight beams 121, 123. The beam reducer 150 increases the angular separation between the images generated by the collimated diagnostic beam 121 and the collimated non-diagnostic beam 123. The non-diagnostic light 122 is derived from the position outside the current target 105c (which generates the diagnostic light 120). For example, the diagnostic light 120 originates from the diagnostic area 145, and the non-diagnostic light 122 originates from outside the diagnostic area 145, such as from the target space 110. Because of this, the non-diagnostic light 122 enters the mechanical filter 140 at an angle slightly different from the angle at which the diagnostic light 120 enters the mechanical filter 140. This fact can be used in the design of the mechanical filter 140, which can further separate the diagnostic light 120 and the non-diagnostic light 122 by increasing the angular separation between the corresponding collimated beams 121 and 123. image. After the light beam has advanced the length of the optical path 152 between the beam reducer 150 and the mask 155, the increase in the angular separation allows a greater distinction between the two images at the aperture 160. Therefore, in this embodiment, the mask 155 is placed so that the aperture 160 allows the diagnostic beam 121 (formed by the diagnostic light 120) to pass to the sensor 130, and the mask 155 blocks the non-diagnostic beam 123 (formed by the non-diagnostic light 120). The light 122 is formed) and is transmitted to the sensor 130.

The optical collimator 142 forms a corresponding collimated beam for input to the beam reducer 150. A collimated beam is a beam with a beam divergence that is low enough so that the beam radius does not undergo a large amount of change within a medium propagation distance. In this case, in the absence of any additional beam shaping (hence, in the absence of the beam reducer 150), the beam radius of each collimated beam output from the optical collimator 142 extends to There will be no significant changes within the distance of the sensor 130. For example, the beam radius of the collimated beam output from the optical collimator 142 changes less than 1%, less than 5%, or less than 10% within the distance from the sensor 130 along the Z direction (in the absence of any intermediate optical element in the case of). In some examples, the distance along the Z direction between the optical collimator 142 and the sensor 130 is about one meter, but it can be shorter or longer depending on the design of the beam reducer 150.

The beam reducer 150 is an afocal system (that is, a system without a focus), which means that the beam reducer 150 does not generate net convergence or divergence of the collimated beam input to the beam reducer 150. That is, the beam reducer 150 can be regarded as having an infinite effective focal length that maintains or maintains the collimated state of the beam output from the optical collimator 142. This type of system can be formed to have a pair of optical elements, where the distance d between the elements is equal to the sum of the focal lengths f1 and f2 of each element (ie, d = f1 + f2). Although the afocal system does not change the divergence of the collimated beam, it does change the width of the beam, thereby increasing or reducing its magnification. In general, the beam reducer 150 can reduce the lateral size (ie, the size in the XsYs plane) of the collimated beam output from the optical collimator 142 by at least five times, at least ten times, or at least twenty times. In some embodiments, the beam reducer 150 reduces the lateral size of the collimated beam by about 10 or about 20 times.

The beam reducer 150 may be, for example, a refracting telescope, a reflecting telescope or a catadioptric telescope.

The refracting telescope uses refractive optics, such as a lens or a mirror, to form an image of the corresponding collimated beam on the plane of the mask 155. In some embodiments, the refracting telescope is a Galilean telescope that includes a positive focal length lens configuration and a negative focal length lens configuration separated by the sum of its focal lengths. In other embodiments, the refracting telescope is a Keplerian telescope that includes a lens configuration with a positive focal length separated by the sum of its focal lengths. An example of a refracting telescope used as the beam reducer 150 is discussed below with reference to FIGS. 3 and 4.

The reflecting telescope includes a single piece or a combination of curved mirrors, which reflect the collimated light beam output from the optical collimator 142 and form a corresponding image on the plane of the mask 155. For example, in some embodiments, the reflecting telescope is a Gregorian telescope, a Newtonian telescope, or a Cassegrain (and its variants) telescope. In other embodiments, the reflecting telescope is an off-axis design, such as Herschelian or Schiefspiegler (which is a variant of Cassegrain). An example of a reflecting telescope is shown and described with respect to Figure 13.

A catadioptric telescope is a telescope in which refraction and reflection are incorporated into an optical system that usually implements a lens (ie, refractive optics) and a curved mirror (ie, reflective optics). For example, in some embodiments, catadioptric telescopes include Schmidt-Cassegrain telescopes and Maksutov-Cassegrain telescopes. In other embodiments, the catadioptric telescope is the catadioptric variant of the Herschelian telescope (which uses both lenses and mirrors) or the off-axis variant of the Stevick-Paul telescope. An example of a catadioptric telescope is shown and described with respect to Figure 14.

The environment 115 may be a vacuum environment in the chamber of an extreme ultraviolet (EUV) light source (such as the EUV light source discussed below with reference to FIG. 7). In some embodiments, the detection device 135 is placed outside the chamber of the EUV light source, the diagnostic area 145 is inside the chamber, and the detection device 135 receives the diagnostic light 120 and non-diagnostic light through the optical window in the wall of the chamber光122. The optical window is transparent to the wavelength of the diagnostic light 120. This situation is discussed below with reference to FIG. 7.

As discussed with reference to FIG. 7, the EUV light source supplies EUV light to an output device that can be a lithography device. EUV light is formed in the environment 115 by converting the target 105 into plasma that emits EUV light when the target 105 reaches the target space 110, and this EUV light is collected and transmitted to the lithography device. The target 105 reaching the target space 110 is converted by the interaction of the target 105 with the radiation pulse in the target space 110, and the radiation pulse provides enough energy to the target 105 to convert it into plasma. A continuous stream 106 of targets (each generally designated 105) is guided from the target supply device 175 toward the target space 110 along the trajectory TR.

The trajectory TR extends in a direction that can be regarded as a target (or axial) direction, which is located in a three-dimensional X, Y, and Z coordinate system defined by the physical form of the environment 115. Therefore, the X, Y, and Z coordinate system can be defined by the walls or spots of the chamber defining the environment 115. The axial direction of each target 105 substantially has a component parallel to the -X direction of the coordinate system of the environment 115. The axial direction of each target 105 may also have a component along one or more of the directions Y and Z perpendicular to the -X direction. In addition, each target 105 released by the target supply device 175 may have a slightly different actual trajectory and the trajectory depends at least in part on the physical properties of the target supply device 175 and the environment 115 when the target 105 is released.

On the other hand, the detection device 135 defines a local three-dimensional Xs, Ys, and Zs coordinate system, and this local coordinate system can be defined by the image plane of the sensor 130.

Each target 105 includes a component that emits EUV light when converted to plasma. These targets 105 travel from the generating area (such as from the target supply device 175) toward the target space 110 (for example, the ballistic ground). The attributes of the current target 105c (such as speed, azimuth, velocity, direction, arrival, or movement) are detected by the metrology device 100 by using the diagnostic probe 125 generated by the diagnostic system 165 when the current target 105c is traveling along the trajectory TR. , Detect or sense the diagnostic light 120 generated by the interaction between the diagnostic probe 125 and the current target 105c and analyze the detected diagnostic light 120 to estimate.

As mentioned above, the non-diagnostic light 122 may also exist, and this non-diagnostic light 122 can interfere with the accurate estimation of the attributes of the current target 105c. This non-diagnostic light 122 may include broadband light radiation emitted by plasma before or when the current target 105c interacts with the diagnostic probe 125, which is generated by entering the target space 110 by one or more of the previous targets 105p . In addition, the intensity of the non-diagnostic light 122 may be much greater than the intensity of the diagnostic light 120.

The non-diagnostic light 122 may include, for example, EUV light emitted from the plasma of the previous target 105p, light having a wavelength range that overlaps the wavelength of the diagnostic light 120, and/or any light that exists and can be detected by the sensor 130 Any light in the wavelength range of the wavelength range.

On the other hand, the diagnostic light 120 is generated by the interaction between the diagnostic probe 125 and the current target 105c, and the diagnostic light 120 has a spectral bandwidth that is substantially narrower than the spectral bandwidth of the non-diagnostic light 122. For example, the spectral bandwidth of the diagnostic light 120 may be hundreds of times lower than the overall spectral bandwidth of the non-diagnostic light 122. In some embodiments, such as shown in FIGS. 6A to 6C, the diagnostic light 120 is generated from a portion of the diagnostic probe 125 that is reflected from or scattered from the current target 105c.

Generally speaking, the sensor 130 may include one or more of a photodiode, a photocrystal, a light-dependent resistor, and a photomultiplier tube. In other embodiments, the sensor 130 includes one or more thermal detectors, such as a pyroelectric detector, a bolometer, or a calibrated charged coupled device (CCD) or CMOS. In other embodiments, the sensor 130 includes a multi-unit optical receiver, a four-unit optical receiver, or a camera.

As shown in the embodiment of FIG. 1, the optical shield 155 is positioned so that the collimated non-diagnostic light beam 123 (generated by the non-diagnostic light 122) is substantially or mostly blocked, while the collimated diagnostic light beam 121 substantially passes through the hole口160. Another implementation is shown and discussed with respect to FIG. 15 in which the collimated non-diagnostic beam 123 substantially passes through the aperture and the collimated diagnostic beam 121 is substantially blocked by the aperture.

2A, in some embodiments, the mask 155 is a mask 255A that defines an aperture 260A having a circular shape in the XsYs plane. In other embodiments, such as shown in FIG. 2B, the mask 155 is a mask 255B that defines a slit-shaped aperture 260B that is not rotationally symmetric and has an edge larger than the range along the Xs direction. Range in Ys direction. The design of FIG. 2B can be useful for a situation where the collimated diagnostic beam 121 is moving, oscillating or disturbing so that its image plane moves along the Ys direction. The range along the Ys direction adapts to this fluctuation in the image plane of the collimated diagnostic beam 121. The mask 155 may be configured to define other shapes in the image plane (XsYs plane) such as the elliptical aperture and the polygonal aperture 160.

In order to properly allow the collimated diagnostic beam 121 to be transmitted to the sensor 130, the aperture 160 along the XsYs plane is at least as large as the lateral extent of the collimated diagnostic beam 121 in the XsYs plane. In addition, in order to properly block the collimated non-diagnostic beam 123, the optical shield 155 should have a range along the XsYs plane that is at least as large as the lateral range of the collimated non-diagnostic beam 123 in the XsYs plane. This means that, referring to FIG. 2A, the range 261A of the aperture 260A in the XsYs plane is as large as the lateral range of the collimated diagnostic beam 121 in the XsYs plane, and the range 256A of the mask 255A is large enough to block the collimation in the plane XsYs The full range of the non-diagnostic beam 123. As another example, referring to FIG. 2B, the shortest range 261B of the aperture 260B in the XsYs plane is as large as the lateral range of the collimated diagnostic beam 121 in the XsYs plane, and the range 256B of the mask 255B is large enough to block one of the planes XsYs The entire range of the non-diagnostic beam 123 is collimated.

In some embodiments, the range 261A, 261B of the corresponding orifice 260A, 260B in the XsYs plane is at least 2 millimeters (mm) or about 4 mm. The range of the collimated diagnostic beam 121 in the XsYs plane at the aperture 260A or 260B is about 3 mm. In some embodiments, the range 256A, 256B of the corresponding mask 255A, 255B is greater than 3 mm.

Different from the spatial filter, in which the light is focused at the aperture of the mask, in the mechanical filter 140, the light (diagnostic beam 121) passing through the aperture 160 (such as aperture 260A or 260B) is collimated And therefore, it has a larger lateral range than the light focused at the aperture of the spatial filter. Therefore, the size of the aperture 160 (such as the aperture 260A or 260B) in the XsYs plane can be much larger than the aperture used in the spatial filter to block the focused non-diagnostic light and pass the focused diagnostic light. Because of this, the effect of undesired particles (such as dirt in the environment 115) on the orifice 160 (such as the orifice 260A or 260B) is much less than that of such particles on the orifice of the spatial filter. For example, the size of the orifice 160 in the XsYs plane is about a few millimeters, and is much larger than the size of the undesired particles. On the other hand, the typical size of the orifice of the spatial filter can be a fraction of a millimeter (for example, in the range of 100 µm) and the undesired particles can be of comparable size. Because of this, when compared with the spatial filter, the interference between the undesired particles and the collimated beam 121 in the mechanical filter 140 is reduced.

In addition, it is easier to guide the collimated diagnostic beam 121 through the aperture 160 (260A, 260B) because of the tolerance in the relative positioning between the collimated diagnostic beam 121 and the 4 mm aperture 160 (or 260A, 260B) It is about 0.2 to 0.4 mm. On the other hand, the tolerance in the relative positioning between the collimated diagnostic beam 121 and the 100 µm aperture of the spatial filter is about 5 to 10 µm.

Referring to FIG. 3, an implementation 335 of the detection device 135 is shown. In this illustration, the coordinate system XsYsZs of the detection device 335 makes Ys the output of the page and Zs extends perpendicular to the imaging area of the sensor 330. The detection device 335 includes an optical collimator 342 that generates a corresponding collimated light beam for each of the diagnostic light 120 and the non-diagnostic light 122 for input to the beam reducer 350. As discussed above, in the absence of the beam reducer 350, the beam radius of each collimated beam output from the optical collimator 342 will not be within the distance extending from the optical collimator 342 to the sensor 330. Going through a lot of changes. The optical collimator 342 is a doublet lens (two lenses 342a, 342b) in this example. The focal length or radius of curvature of the doublet lens 342 is selected so that the initial curved wavefront of the diagnostic light 120 and the non-diagnostic light 122 becomes flat or substantially flat at least for the distance extending a certain length to the sensor 330.

In this embodiment, the beam reducer 350 is designed as a Galilean type refracting telescope. The beam reducer 350 optically reduces the size of the collimated light beam output from the optical collimator 342 to form collimated light beams 121 and 123 of reduced size, respectively. The beam reducer 350 includes a positive focal length lens configuration 351 at the input side (which may be a convergent lens configuration including one or more of a positive biconvex lens, a plano-convex lens, or a meniscus lens). The beam reducer 350 includes a negative focal length lens configuration 353 (which may be a divergent lens configuration including a concave lens) at the output side. The positive focal length lens configuration 351 and the negative focal length lens configuration 353 are separated by the sum of their focal lengths. The convergent lens configuration 351 in this example is a compound lens (having a convex lens 351a and a concave lens 351b) that can help correct distortion in the light beam. The beam reducer 350 lacks an intermediate focus (there is no focus between the convergent lens configuration 351 and the divergent lens configuration 353). Although not required, in this embodiment, the divergent lens configuration 353 includes an auxiliary lens 354 between the convergent lens 351 and the divergent lens 353. The auxiliary lens 354 can be used in combination with the divergent lens configuration 353 to collimate the light beam from the positive focal length lens configuration 351. The auxiliary lens 354 may be a positive focal length lens, such as a meniscus lens (as shown), a biconvex lens, or a plano-convex lens. In general, the beam reducer 350 can reduce the lateral size (ie, the size in the XsYs plane) of the collimated beam output from the optical collimator 342 by at least five times, at least ten times, or at least twenty times.

The beam reducer 350 outputs the reduced collimated diagnostic beam 121 and the reduced collimated non-diagnostic beam 123, which then proceed to the length of the optical path 352 of the mask 355. The longer the optical path 352, the greater the degree of separation between the corresponding images from the light beams 121 and 123 at the mask 355. In this embodiment, the mask 355 is placed so that the aperture 360 allows the diagnostic beam 121 (formed by the diagnostic light 120) to pass to the sensor 330, and the mask 355 blocks the non-diagnostic beam 123 (formed by the non-diagnostic light 122). The formation) is transmitted to the sensor 330. The collimated diagnostic beam 121 that has passed through the aperture 360 can be focused on the imaging area of the sensor 330 by means of the convergent lens 357.

Referring to FIG. 4, another implementation 435 of the detection device 135 is shown. In this illustration, the coordinate system XsYsZs of the detection device 435 is aligned with the page. The detection device 435 includes an optical collimator 442 that generates a corresponding collimated beam for each of the diagnostic light 120 and the non-diagnostic light 122 for input to the beam reducer 450 of the detection device 435. As discussed above, the beam radius of each collimated beam output from the optical collimator 442 does not undergo a large amount of change within the distance extending to the sensor 430. The optical collimator 442 is similar to the optical collimator 342 in this example and includes a doublet lens (two lenses 442a, 442b). The focal length or radius of curvature of the doublet lens 442 is selected so that the initial curved wavefront of the diagnostic light 120 and the non-diagnostic light 122 becomes flat or substantially flat at least for the distance extending a certain length to the sensor 430.

In this embodiment, the beam reducer 450 is designed as a Keplerian type refracting telescope. The beam reducer 450 optically reduces the size of the collimated light beam output from the optical collimator 442 to form collimated light beams 121 and 123 of reduced size, respectively. The beam reducer 450 includes an input positive focal length lens configuration 451 at the input side (which may be a convergent lens configuration including one or more of a positive biconvex lens, a plano-convex lens, or a meniscus lens). The beam reducer 450 includes an output positive focal length lens configuration 453 at the output side (which may be a convergent lens configuration including one or more of a positive biconvex lens, a plano-convex lens, or a meniscus lens). For example, the positive focal length lens configuration 453 is shown as the aspheric lens element in FIG. 4. It is possible that the positive focal length lens configuration 453 is a compound lens group. The positive focal length lens arrangements 451, 453 are separated by the sum of their focal lengths. The convergent lens configuration 451 in this example is a compound lens (having a convex lens 451a and a concave lens 451b) that can help correct distortion in the light beam. The intermediate focal point IF (or intermediate focal plane IF) is between the input convergent lens configuration 451 and the output convergent lens configuration 453. In general, the beam reducer 450 can reduce the lateral size (ie, the size in the XsYs plane) of the collimated beam output from the optical collimator 442 by at least five times, at least ten times, or at least twenty times. The range of the beam reducer 450 along the Zs direction tends to be larger than the range of the beam reducer 350 along the Zs direction, and therefore, the space requirement can determine the design of the beam reducer 350 or 450 which is more suitable. In addition, if the power of the diagnostic light 120 or the non-diagnostic light 122 is too high to apply the intermediate focus IF (such as present in the beam reducer 450), the beam reducer 350 may be more appropriately designed.

The beam reducer 450 outputs the reduced collimated diagnostic beam 121 and the reduced collimated non-diagnostic beam 123, which then proceed to the length of the optical path 452 of the mask 455. The longer the optical path 452 is, the greater the degree of separation between the corresponding images from the light beams 121 and 123 at the mask 455 is. In this embodiment, the mask 455 is placed so that the aperture 460 allows the diagnostic beam 121 (formed by the diagnostic light 120) to pass to the sensor 430, and the mask 455 blocks the non-diagnostic beam 123 (formed by the non-diagnostic light 122). The formation) is transmitted to the sensor 430. The collimated diagnostic beam 121 that has passed through the aperture 460 can be focused on the imaging area of the sensor 430 by means of the convergent lens 457.

Referring to FIG. 5, in other embodiments, the detecting device 135 is a detecting device 535 that also includes one or more spectral filters 543 and polarization filters 544 that can be configured in series or in parallel with the mechanical filter 140. The spectral filter 543 is a filter that transmits light in a specific wavelength range, such as a band pass filter. The polarization filter 544 is a filter that transmits light with a specific polarization. For example, the diagnostic light 120 may have a different polarization depending on the polarization of the diagnostic probe 125, and the non-diagnostic light 122 may be unpolarized. Therefore, the polarization filter can select the polarization of the diagnostic light 120 to be transmitted.

Referring to Figure 6A, in some embodiments, the diagnostic device 165 is designed as a diagnostic device 665A. The diagnostic device 665A generates a single probe beam 625A from the light source 626A as one or more diagnostic probes 125. The probe beam 625A is guided as a light curtain to cross the trajectory TR at position x so that each of the targets 105 passes through the light curtain in its way to the target space 110. The light source 626A generates a single beam 611A that is directed through the modified beam 611A to form one or more of the optical elements 627A (such as mirrors, lenses, apertures, and/or filters) of a single probe beam 625A.

The light source 626A may be a solid state laser, such as a YAG laser, which may be a neodymium-doped YAG (Nd:YAG) laser operating at 1070 nm and at a power of 50 W. In this example, when the current target 105c passes through the probe beam 625A at time t, at least some of the probe beams 625A are reflected or scattered from the current target 105c to form the diagnostic light 620A detected by the detection device 135. The control system 170 uses the information from the sensor 130 to estimate the movement attributes of the current target 105, which can be used to estimate the arrival time of an existing target (which may be the current target 105c or a subsequent target) at the target space 110. This estimate can be used to adjust the characteristics of the radiation pulse guided to the target space 110 to ensure that the radiation pulse interacts with existing targets in the target space 110. The control system 170 can also rely on some assumptions about the path of the existing target to perform calculations to estimate the arrival time of the existing target at the target space 110.

The probe beam 625A can be a Gaussian beam so that the lateral distribution of its optical intensity can be described as having a Gaussian function. The focal point or beam waist of the probe beam 625A can be configured to overlap in the trajectory TR or -X direction. In addition, the optical element 627A may include a refractive optical device that ensures that the focus (or beam waist) of the probe beam 625A overlaps the track TR.

Referring to Figure 6B, in some embodiments, the diagnostic device 165 is designed as a diagnostic device 665B. The diagnostic device 665B generates two probe beams 625B_1 and 625B_2 as one or more diagnostic probes 125. The probe beam 625B_1 is guided as a first light curtain to cross the trajectory TR at a first orientation (for example, the orientation along the X axis x1) so that each of the targets 105 passes through in a way to the target space 110 The first light curtain. The probe beam 625B_2 is guided as a second light curtain to cross the trajectory TR at a second orientation (for example, the orientation along the X axis x2) so that each of the targets 105 reaches the target space 110 and in After passing through the first light curtain, pass through the second light curtain. The probe beams 625B_1, 625B_2 are separated by a distance Δd equal to x2-x1 at the track TR. The dual-screen diagnostic device 665B can be used not only to determine the orientation and arrival information of the target 105, but also to determine the speed or velocity of the target 105.

In some implementations, the diagnostic device 665B includes a single light source 626B that generates a single light beam 611B and an optical element 627B that receives the single light beam and splits the light beam 611B into one of two probe beams 625B_1, 625B_2. In addition, the optical element 627B may include components for guiding the probe beams 625B_1, 625B_2 toward the corresponding directions x1, x2 along the track TR.

In some embodiments, the optical assembly 627B includes a beam splitter that splits a single beam from a single light source 626B into two probe beams 625B_1, 625B_2. For example, the beam splitter can be a dielectric mirror, a beam splitter block, or a polarizing beam splitter. One or more of the optical components 627B may be reflective optics that are placed to redirect either or both of the probe beams 625B_1, 625B_2 such that both of the probe beams 625B_1, 625B_2 are directed toward the trajectory TR.

In other embodiments, the optical component 627B includes splitting optics (such as diffraction optics or binary phase diffraction gratings, birefringent crystals, intensity beam splitters, polarizing beam splitters, or dichroic beam splitters) and Refractive optics, such as focusing lenses. The beam 611B is guided through the splitting optics, which splits the beam 611B into two beams that travel in different directions and are guided through the refractive optics to produce the probe beam 625B_1, 625B_2. The splitting optics can split the beam 611B so that the probe beams 625B_1, 625B_2 are separated by a set distance (for example, 0.65 mm along the X direction) at the track TR. In this example, x2-x1=0.65 mm. In addition, the refractive optics can ensure that the focal point (or beam waist) of each of the probe beams 625B_1 and 625B_2 overlaps the track TR.

As shown in this example, the probe beams 625B_1, 625B_2 are directed so that they intersect the trajectory TR at different orientations x1, x2 but substantially at a substantially similar angle with respect to the X axis. For example, the probe beams 625B_1, 625B_2 are guided at approximately 90° with respect to the X axis. In other embodiments, split optics and refractive optics can be used to adjust the angles of the probe beams 625B_1, 625B_2 with respect to the X axis, so that the probe beams fan out toward the trajectory TR and have different phases. The different angle intersects the trajectory TR. For example, the probe beam 625B_1 may intersect the track TR at substantially 90° with respect to the -X direction, and the probe beam 625B_2 may intersect the track TR at an angle of less than 90° with respect to the -X direction.

Each of the probe beams 625B_1, 625B_2 can be a Gaussian beam, so that the lateral distribution of the optical intensity of each probe beam 625B_1, 625B_2 can be described by a Gaussian function. The focal point or beam waist of each probe beam 625B_1, 625B_2 can be configured to overlap in the trajectory TR or -X direction.

The light source 626B may be a solid state laser, such as a YAG laser, which may be a neodymium-doped YAG (Nd:YAG) laser operating at 1070 nm and at a power of 50 W. In this example, the current target 105c passes through the first probe beam 625B_1 at time t1 (and position x1), and at least some of the probe beams 625B_1 are reflected or scattered from the current target 105c to form a detection device 135 ( The diagnostic light 620B_1 detected by the mechanical filter 140). In addition, the current target 105c passes through the second probe beam 625B_2 at time t2 (and azimuth x2), and at least some of the probe beams 625B_2 are reflected or scattered from the current target 105c to form a detection device 135 (by means of mechanical filtering). The light device 140) detects the light 620B_2.

The separation Δd between the probe beams 625B_1 and 625B_2 at the trajectory TR can be adjusted or customized depending on the rate at which the target 105 is released from the target supply device 175 and the size and material of the target 105. For example, the degree of separation Δd may be smaller than the distance between adjacent targets 105. As another example, the separation Δd can be determined or set based on the distance between adjacent targets 105 to provide greater accuracy in the measurement performed based on the interaction between the probe beams 625B_1, 625B_2 and the current target 105c . To a certain extent and generally speaking, the greater the separation Δd, the higher the accuracy of the measurement performed. For example, the resolution Δd can be between about 250 µm and 800 µm.

The interaction between the probe beams 625B_1, 625B_2 and the current target 105c enables the control system 170 to determine movement attributes, such as the velocity V of the current target 105c in the -X direction. It is also possible to determine the velocity V across many targets 105 or the tendency to change the velocity V. If some assumptions about the movement of the current target 105c are made, it is also possible to use only the probe beams 625B_1, 625B_2 to determine changes in the movement attributes of the current target 105c along the -X direction.

The wavelength of the diagnostic probe 125 (such as the probe beam 625A and the probe beams 625B_1, 625B_2) generated by the diagnostic device 165 should be the same as the wavelength of the radiation pulse guided to the target space 110 (for interaction with the target 105) It is sufficiently different to help distinguish between the diagnostic light 120 and the non-diagnostic light 122. In some embodiments, the wavelengths of the probe beams 125, 625A, 625B_1, and 625B_2 are 532 nm or 1550 nm.

In other implementations such as that shown in FIG. 6C, the diagnostic device 665C includes a pair of light sources 626C_1, 626C_2 (such as two lasers) that each generate one of the light beams 611C_1, 611C_2, instead of having a light source 626B such as in the diagnostic device 665B The single light source. Each of the light beams 611C_1, 611C_2 passes through the corresponding one or more optical elements 627C_1, 627C_2 that can change or adjust the characteristics of the light beams 611C_1, 611C_2. The output end of each of the one or more optical elements is the corresponding probe beam 625C_1, 625C_2. The optical components 627C_1, 627C_2 may include components for guiding the corresponding probe beams 625C_1, 625C_2 toward the corresponding directions x1, x2 along the track TR. Examples of the optical components 627C_1, 627C_1 are discussed above with reference to the optical component 608B.

As discussed above, and referring to FIG. 7, in some implementations, the metrology device 100 is implemented as the metrology device 700 in the EUV light source 776 to measure one or more attributes of the target 105. The EUV light source 776 includes a target supply device 775 that generates a continuous flow 706 of targets (each generally designated 105) along the trajectory TR toward the target space 710 inside the vacuum environment 715 defined by the chamber 716. The EUV light source 776 supplies EUV light 777 that has been generated by the interaction between the target 105 and the radiation pulse 778 to the output device 779. As discussed above, when the current target 105c travels toward the target space 710 along the trajectory TR, the metrology device 700 measures and analyzes one or more movement attributes (such as speed, velocity, and acceleration) of the current target 105c. The trajectory TR extends in a direction that can be regarded as the target (or axial) direction, which is in the three-dimensional X, Y, and Z coordinate system defined by the cavity 716. As discussed above, the axial direction of the target 105 generally has a component parallel to the −X direction of the coordinate system of the chamber 716. However, the axial direction of the target 105 may also have a component along one or more of the directions Y and Z perpendicular to the −X direction. In addition, each target 105 released by the target supply device 775 may have a slightly different actual trajectory and the trajectory depends on the physical properties of the target supply device 775 and the environment 715 in the chamber 716 when the target 105 is released.

The EUV light source 776 generally includes an EUV concentrator 780, an optical source 781, an actuation system 782 that communicates with the optical source 781, a control system 770 that communicates with the metrology device 700, and a target supply device 775, an optical source 781, and an actuation system 782 in communication.的控制装置783。 Control device 783.

The EUV light collector 780 collects as much EUV light 784 emitted from the plasma 785 as possible and redirects it toward the output device 779 as the other EUV light 784 of the collected EUV light 777. The light collector 780 may be a reflective optical device, such as a curved mirror surface capable of reflecting light having EUV wavelengths (ie, EUV light 784) to form the generated EUV light 777.

The optical source 781 generates one or more beams of radiation pulses 778 and guides one or more beams of radiation pulses 778 to the target space 710 generally along the Z direction (but the beams of the radiation pulses 778 may be at an angle relative to the Z direction ). In FIG. 7 as a schematic representation, the beam of radiation pulse 778 is shown as being guided along the -Y direction. The optical source 781 includes one or more light sources that generate a radiation pulse 778, a beam delivery system including an optical steering component that changes the direction or angle of the beam of the radiation pulse 778, and a focusing assembly that focuses the beam of the radiation pulse 778 to a target space 710 . Exemplary optical steering components include optical elements such as lenses and mirrors that redirect or guide the beam of radiation pulse 778 by refraction or reflection as necessary. The actuation system 782 can be used to control or move various features of the optical components and focusing assembly of the beam delivery system, and to adjust the configuration of the optical source 781 that generates the radiation pulse 778.

The optical source 781 includes at least one gain medium and an energy source for exciting the gain medium to generate a radiation pulse 778. The radiation pulses 778 constitute a plurality of optical pulses separated from each other in time. In other embodiments, the light beam output from the optical source 781 may be a continuous wave (CW) light beam. The optical source 781 may be or include, for example, a solid state laser (eg, Nd:YAG laser, Erbium-doped fiber (Er:glass) laser, or neodymium doped at 1070 nm and 50 W power). YAG (Nd:YAG) laser).

The actuation system 782 is coupled to the components of the optical source 781 and also communicates with the control device 783 and is under the control of the control device 783. The actuation system 782 can modify or control the relative position between the radiation pulse 778 and the target 105 in the target space 710. For example, the actuation system 782 is configured to adjust one or more of the timing of the release of the radiation pulse 778 and the direction in which the radiation pulse 778 travels.

The target supply device 775 is configured to release the stream of targets 105 (or more 706) at a certain rate. When determining the total amount of time required to perform measurement and analysis on one or more of the movement attributes of the current target 105c and the changes to other aspects or components of the EUV light source 776 based on the measurement and analysis, the measurement device 700 consider this rate. For example, the control system 170 may transmit the measurement and analysis results to the control device 783, which determines how to adjust one or more signals to adapt to the actuation system 782, thereby adjusting the radiation pulse 778 guided to the target space 710 One or more characteristics.

The adjustment of one or more characteristics of the radiation pulse 778 can improve the relative alignment between the existing target 105 ′ and the radiation pulse 778 in the target space 710. The existing target 105 ′ is a target that has entered the target space 710 when the radiation pulse 778 (which happens to have been adjusted) reaches the target space 710. Such adjustments to one or more of the characteristics of the radiation pulse 778 improve the interaction between the existing target 105' and the radiation pulse 778 and increase the amount of EUV light 784 generated by such interaction. As shown in Figure 7, the previous target 105p has interacted with previous radiation pulses (not shown) to produce (in addition to EUV light 784) plasma 785 that emits non-diagnostic light 122.

In some embodiments, the existing target 105' is the current target 105c. In these embodiments, adjustments to one or more of the characteristics of the radiation pulse 778 occur within a relatively short time frame. The relatively short time frame means that one or more characteristics of the radiation pulse 778 are adjusted between the time after the analysis of the movement attributes of the current target 105c is completed to the time when the current target 105c enters the target space 710. Because one or more of the characteristics of the radiation pulse 778 can be adjusted within a relatively short time frame, there is sufficient time to affect the interaction between the current target 105c (whose movement properties have just been analyzed) and the radiation pulse 778.

In other embodiments, the existing target 105' is another target, that is, a target other than the current target 105c and temporally after the current target 105c. In these embodiments, the adjustment of one or more of the characteristics of the radiation pulse 778 occurs within a relatively long time frame, so as to affect the interaction between the current target 105c (whose movement properties happen to be analyzed) and the radiation pulse 778 Department is not feasible. On the other hand, it is possible to influence the interaction between another (or later) target and the radiation pulse 778. The relatively long time frame is a time frame that is greater than the time after the analysis of the movement attributes of the current target 105c is completed to the time the current target 105c enters the target space 710. Depending on the relatively long time frame, another target may be adjacent to the current target 105c. Alternatively, another target may be adjacent to an intermediate target, which is adjacent to the current target 105c. In these other embodiments, it is assumed that another target (which is not the current target 105c) is traveling with a movement attribute sufficiently similar to the detected or estimated movement attribute of the current target 105c.

Each of the targets 105 (including the previous target 105p and the current target 105c, and all other targets generated by the target supply device 775 (or 175)) includes a material that emits EUV light when converted to plasma. Each target 105 is converted at least partially or mostly into plasma by interacting in the target space 710 with the radiation pulse 778 generated by the optical source 781. Each target 105 generated by the target supply device 775 (or 1750) is a target mixture, which includes the target material and optional impurities, such as non-target particles. The target material is capable of being converted into a plasma state with EUV Spectral-emitting substances within the range. Target 105 can be, for example, liquid or molten metal droplets, part of a liquid stream, solid particles or clusters, solid particles contained in the droplets, foams or liquid streams of target materials Solid particles contained in a part. The target material can include, for example, water, tin, lithium, xenon, or any material that has an emission spectrum in the EUV range when converted to a plasma state. For example, the target material can be as elemental tin, which can be used as pure tin (of Sn); as a tin compound, such as _{SnBr 4, SnBr 2, SnH 4} ; as a tin alloy, such as tin - gallium alloy, tin - indium alloys, tin - indium - gallium Alloy or any combination of these alloys. In the absence of impurities, each target 105 includes only the target material. The discussion provided herein is that each target 105 is made of a molten metal such as tin. An example of drops. However, each target 105 generated by the target supply device 775 (or 175) may take other forms.

The target 105 can be provided to the target space 710 by passing the molten target material through the nozzle of the target supply device 775 (or 175) and allowing the target 105 to drift into the target space 710 along the trajectory TR. In some embodiments, the target 105 may be guided to the target space 710 by force (in addition to or regardless of gravity). As discussed below, the existing target 105' (which may be the current target 105c) that interacts with the radiation pulse 778 may also have interacted with one or more previous radiation pulses. Alternatively, the existing target 105' interacting with the radiation pulse 778 can reach the target space 710 without interacting with any other radiation pulses.

In this embodiment, the detection device 735 is positioned outside the chamber 716, and the diagnostic zone 745 is inside the environment 715 of the chamber 716. The wall of the chamber 716 is equipped with an optical window 736 which is transparent to the wavelength of the diagnostic light 120 and can withstand any pressure difference at the wall. The optical window 736 can be held in the mounting member and hermetically sealed in the wall to maintain the pressure in the environment 715. For example, the optical window 736 may be made of crown glass with relatively low refractive index and low dispersion, such as borosilicate glass (BK7 or N-BK7) or fused silica. The optical window 736 has an aperture large enough to fit the range of the diagnostic light 120. The distance between the diagnostic area 745 and the optical window may be about hundreds of millimeters (or about 600 to 700 mm), and the distance between the diagnostic area 745 and the target space 710 may be about several millimeters (or about 1 to 5 mm) . Therefore, the distance between the diagnostic area 745 and the optical window may be 200 to 500 times the distance between the diagnostic area 745 and the target space 710.

The control device 783 communicates with the control system 170 and also communicates with other components of the EUV light source 776, such as the actuation system 782, the target supply device 775, and the optical source 781. Referring to FIG. 8, an implementation 883 of the control device 783 is shown and an implementation 870 of the control system 170 is shown. The control device 883 includes the control system 870, but the control system 870 may be physically separated from the control device 883 and still maintain communication. In addition, the features or components of the control device 883 can be shared with the control system 870, including features not shown in FIG. 8.

The control system 870 includes a signal processing module 871 configured to receive and output from the detection device 735 (or 135, 335, 435). The control system 870 includes a diagnosis control module 872 that communicates with the diagnosis device 765 (or 165). For example, the signal processing module 871 receives a signal from the sensor 130 in the detection device 735 (135, 335, 435), where the signal is related to the current generated by the light detected at the sensor 130 Voltage signal. Generally speaking, the signal processing module 871 analyzes the output from the sensor 730, and determines one or more movement attributes of the current target 105c based on this analysis. The diagnosis control module 872 controls the operation of the diagnosis device 765. For example, the diagnostic control module 872 may provide a signal to the diagnostic device 765 for adjusting one or more characteristics of the diagnostic device 765 and for adjusting one or more characteristics of the one or more diagnostic probes 725.

The signal processing module 871 also determines whether it is necessary to adjust the subsequent radiation pulse 778 output from the optical source 781 based on the determination of one or more movement attributes of the current target 105c. Moreover, if adjustment is required, the signal processing module 871 sends an appropriate signal to the optical source actuation module 884 which interfaces with the optical source 781 or the actuation system 782. The optical source actuation module 884 may be in the control device 883 (as shown in FIG. 8) or it may be integrated in the control system 870.

The signal processing module 871 may include one or more field-programmable hardware circuits, such as a field-programmable gate array (FPGA). FPGAs are integrated circuits that are designed to be configured by customers or designers after manufacturing. The field programmable hardware circuit may be dedicated hardware that receives one or more values of the time stamp, performs calculations on the received values, and uses one or more look-up tables to estimate the time for the existing target 105' to reach the target space 710. In particular, the field programmable hardware circuit can be used to quickly perform calculations to adjust one or more of the characteristics of the radiation pulse 778 within a relatively short time frame, so as to achieve alignment with the current target 105c (its movement attribute It happens to have been analyzed by the signal processing module 871) to adjust one or more characteristics of the interacting radiation pulse 778.

The control device 883 includes a target delivery module 885 configured to interface with the target supply device 775. In addition, the control device 883 and the control system 870 may include other modules specifically configured to interface with other components of the EUV light source 776 not shown.

The control system 870 generally includes or can be connected to one or more of digital electronic circuits, computer hardware, firmware, and software. For example, the control system 870 can access the memory 873 which can be a read-only memory and/or a random access memory. Storage devices suitable for tangibly embodying computer program instructions and data include all forms of non-volatile memory, including (by way of example): semiconductor memory devices, such as EPROM, EEPROM, and flash memory devices; magnetic disks, such as Internal hard disks and removable disks; magneto-optical disks; and CD-ROM disks. The control system 870 may also include or one or more input devices 874i (such as a keyboard, touch screen, microphone, mouse, handheld input device, etc.) and one or more output devices 874o (such as speakers and monitors) or The one or more input devices 874i and the one or more output devices 874o interface.

The control system 870 may also include or be connected to one or more programmable processors, and be tangibly embodied in a machine-readable storage device for the programmable processor to execute one or more computer program products. One or more programmable processors can each execute a program of instructions to perform desired functions by operating on input data and generating appropriate output. Generally speaking, the processor receives commands and data from the memory 873. Any of the foregoing can be supplemented by or incorporated into a specially designed application-specific integrated circuit (ASIC).

In addition, any one or more of the modules may include its own digital electronic circuits, computer hardware, firmware and software, as well as dedicated memory, input and output devices, programmable processors, and computer program products. Similarly, any one or more of the modules can access and use the memory 873, the input device 874i, the output device 874o, the programmable processor, and the computer program product.

Although the control system 870 is shown as a separate and complete unit, each of its components and modules may be a separate unit. The control device 883 may include other components not shown in FIG. 8, such as dedicated memory, input/output devices, processors, and computer program products.

Referring to Figure 9, an implementation 979 of the lithography device 779 is shown. The lithography device 979 exposes the substrate (which may be referred to as a wafer) W by the exposure beam B. The lithography device 979 includes a plurality of reflective optical elements R1, R2, R3, a mask M, and a slit S all in the housing 10. The housing 10 is a housing, a storage tank, or other structure that can support the reflective optical elements R1, R1, R2, the mask M, and the slit S, and can also maintain the evacuated space in the housing 10.

The EUV light 777 enters the housing 10 and is reflected by the optical element R1 toward the mask M via the slit S. The slit S partially defines the shape of the scattered light used to scan the substrate W in the lithography process. The dose delivered to the substrate W or the number of photons delivered to the substrate W depends on the size of the slit S and the speed at which it scans the slit S.

The mask M can also be referred to as a reduction mask or a patterned device. The mask M includes a space pattern representing features in the photoresist to be formed on the substrate W. The EUV light 777 interacts with the mask M. The interaction between the EUV light 777 and the mask M causes the pattern of the mask M to be imparted to the EUV light 777 to form the exposure beam B. The exposure light beam B passes through the slit S and is guided to the substrate W by the optical elements R2 and R3. The interaction between the substrate W and the exposure beam B exposes the pattern of the mask M to the substrate W, and the photoresist feature is formed at the substrate W by this. The substrate W includes a plurality of parts 20 (for example, dies). The area of each part 20 in the Y-Z plane is smaller than the area of the entire substrate W in the Y-Z plane. Each part 20 can be exposed by the exposure beam B to include a copy of the mask M so that each part 20 includes electronic features indicated by the pattern on the mask M.

The lithography device 979 may include a lithography control system 30 that communicates with the control device 783 of the EUV light source 776.

Referring to FIG. 10, the process 1090 is performed by the metrology apparatus 100 (or the metrology apparatus 700). Before the current target 105c enters the target space 110, the diagnostic probe 125 interacts with the current target 105c in the diagnostic area 145 (1091). The diagnostic light 120 generated by the interaction (1091) is collected, and at the same time, some undesired non-diagnostic light 122 generated by the target space 110 is also collected (1092). For example, the pupil diagnostic light 120 and the non-diagnostic light 122 at the entrance of the mechanical filter 140. The diagnostic light 120 and the non-diagnostic light 122 are collimated (1093). The optical collimator 142 collimates the diagnostic light 120 and the non-diagnostic light 122 that have entered the mechanical filter 140. The collimated diagnostic light and the non-diagnostic light are angularly separated from each other (1094). The beam reducer 150 reduces the lateral range (along the XsYs plane) of the collimated diagnostic beam and the collimated non-diagnostic beam, and these reduced beams 121 and 123 respectively leave the beam reducer 150 and follow the optical path 152 toward the shield The cover 155 travels, and its angular separation increases. The collimated diagnostic beam 121 is sensed at the sensing area (for example, the sensor 130) in optical communication with the open image plane, which is laterally shifted from the closed image plane blocking the collimated non-diagnostic beam 123 (at In the XsYs plane) (1095). For example, the sensor 130 senses the collimated diagnostic beam 121, the sensor 130 optically communicates with the aperture 160 (open image plane), and the aperture 160 self-collimates the non-diagnostic beam 123 in the XsYs plane to irradiate it. The upper mask 155 is shifted laterally. The attributes of the current target 105c are estimated based on the sensed diagnostic light (1096). Specifically, the control system 170 analyzes the output from the sensor 130 to estimate one or more movement attributes of the current target 105c.

As discussed above with reference to FIGS. 6A to 6C, the diagnostic probe 125 may be one or more probe beams that are guided to intersect the trajectory of the target 105. Therefore, the interaction (1091) between the diagnostic probe 125 and the current target 105c can be between these probe beams and the current target 105c. In some embodiments, the collected (1092) diagnostic light 120 may be a portion of the probe beam 125 reflected or scattered from the current target 105c. In other embodiments, the collected (1092) diagnostic light 120 is light generated by the current target 105c. In other embodiments, the collected (1092) diagnostic light 120 is light blocked by the current target 105c (as shown in Figure 12).

By blocking or redirecting the non-diagnostic light 122 with the mechanical filter 140, the influence of the non-diagnostic light 122 on the analysis of the output from the sensor 130 is reduced, and thus the non-diagnostic light 122 is prevented from being irradiated on the sensor 130 and This non-diagnostic light 122 is actually blocked by the mask 155. In addition, the collimated state of the collimated diagnostic beam and the collimated non-diagnostic beam output from the collimator 142 is maintained to the plane of the mask 155, and the collimated diagnostic beam 121 is further focused to the plane after passing through the aperture 160 On the sensor 130.

11, in other implementations, the components of the optical collimator 142 and the beam reducer 150 having a positive focal length and closest to the optical collimator 142 are integrated into a single refractive element 1142/1151. The integrated single refracting element 1142/1151 can be applied to a Galilean type refracting telescope (such as the telescope shown in FIG. 3 and FIG. 11) or a Keplerian type refracting telescope (such as the telescope shown in FIG. 4).

12, in other embodiments, the diagnostic light 120 is generated by a portion of the diagnostic probe beam 1225 blocked by the current target 105c. In this embodiment of the metrology apparatus 1200, the diagnostic probe 1225 provides backlighting of the current target 105c. The sensor 130 is a two-dimensional (eg, imaging) sensor 1230, such as a camera. Therefore, when the current target 105c crosses the diagnostic probe 1225, the shadow of the target 105c is formed by the target 105c covering at least a part of the diagnostic probe 1225, as shown in the inset of FIG. 12. This configuration can be regarded as a shadowgraph configuration. In such an implementation, the sensor 1230 is configured on a side of the target trajectory TR opposite to the side on which the diagnostic device 1265 is configured. The sensor 1230 is a camera that captures a two-dimensional representation of the diagnostic light 1220 (which can be regarded as an image). Thus, for example, the sensor 1230 includes a two-dimensional array of thousands or millions of light spots (or pixels). The diagnostic light 1220 is guided to the photosensitive area of each pixel, where it is converted into electrons collected in a voltage signal and the array of these signals forms a two-dimensional image. As discussed above, the non-diagnostic light 1222 is substantially blocked from reaching the sensor 1230.

Referring to FIG. 13, in other embodiments, the beam reducer 150 is designed as a reflected beam reducer 1350 that receives a collimated light beam from an optical collimator such as the collimator 342. The reflected beam reducer 1350 includes a concave reflective element (curved mirror) 1351, which causes the beam to converge toward the convex reflective element (curved mirror) 1353, thereby collimating the light in a different direction (or angle) The collimated diagnostic beam 121 and the collimated non-diagnostic beam 123 travel along the optical path 1352 toward the mask 155.

Referring to FIG. 14, in other embodiments, the beam reducer 150 is designed as a catadioptric (hybrid) beam reducer 1450 that receives a collimated light beam from an optical collimator such as the collimator 342. The hybrid beam reducer 1450 includes a flat reflective element (flat mirror) 1451a that guides the beam to a curved reflective element (curved mirror) 1451b, and the curved reflective element 1451b directs the beam toward the curved mirror 1451b and convex The intermediate focal point IF between the shaped or convergent refractive elements (lenses) 1453 converges. The lens 1453 collimates the light into a collimated diagnostic beam 121 and a collimated non-diagnostic beam 123 that travel along the optical path toward the mask 155 in different directions (or angles).

Referring to FIG. 15, in other embodiments, the mask 155 is designed as a mask 1555, which defines an aperture 1560 aligned with the path of the collimated non-diagnostic beam 123, and the mask 1555 is used to stop or prevent collimated diagnosis The light beam 121 passes to the sensor 130. This type of design can be useful if it is necessary to analyze the state related to the non-diagnostic light 122.

Other aspects of the present invention are described in the following numbered items. 1. A weighing and measuring device, which includes: A diagnostic device that is configured to cause the diagnostic probe to interact with the current target at the diagnostic area before the current target enters the target space; Detection device, which includes: A light sensor that has a field of view overlapping the diagnostic area and is configured to sense light generated by the interaction between the diagnostic probe and the current target at the diagnostic area; and A mechanical filter between the diagnostic area and the light sensor. The mechanical filter includes a beam reducer and an optical shield defining a hole positioned between the beam reducer and the light sensor Mouth; and A control system that communicates with the detection device and is configured to estimate the attributes of the current target based on the output from the light sensor. 2. The weights and measures device of Clause 1, in which the mechanical filter is configured to angularly separate the diagnostic light emitted from the diagnostic area and the non-diagnostic light emitted from the target space, wherein the diagnostic light is generated by the current target in the diagnostic area The interaction with the diagnostic probe occurs. 3. As in the measurement device of Clause 2, the non-diagnostic light includes the light emitted from the plasma generated by the previous target in the target space. 4. For the metrology device of Clause 2, the lateral range of the aperture is approximately the same as or greater than the lateral range of the diagnostic light in the plane of the optical cover, and the optical cover The lateral range is greater than or approximately the same as the lateral range of the non-diagnostic light in the plane of the optical shield. 5. As the weights and measures device of Clause 2, wherein the optical mask is positioned so that the non-diagnostic light emitted from the target space is substantially blocked by the optical mask, and the diagnostic light substantially passes through the aperture. 6. Such as the metrology device of Clause 1, in which the mechanical filter includes an optical collimator between the diagnostic area and the beam reducer. 7. For the metrology device of Clause 6, the beam reducer is an afocal beam reducer and is configured to be combined with an optical collimator to project a finite object to infinity. 8. As the weights and measures device of Clause 6, the components of the optical collimator and the beam reducer with a positive focal length closest to the optical collimator are integrated into a single refraction element. 9. Such as the metrology device of Clause 6, in which the beam reducer is configured to maintain the collimation state of the light. 10. Such as the measurement device of Clause 1, where the optical sensor includes one or more of the following: photodiode, photoelectric crystal, optical dependent resistor, photomultiplier tube, multi-unit optical receiver, four-unit optical receiver And camera. 11. The metrology device of clause 1, wherein the diagnostic probe includes at least one diagnostic beam, and the light sensor is configured to sense the diagnostic light generated by the interaction between the current target and the at least one diagnostic beam. 12. For the weights and measures device of Clause 11, the diagnostic light includes the diagnostic light beam reflected from the current target, scattered from the current target, or blocked by the current target. 13. Such as the metrology device of Clause 1, wherein the detection device further includes one or more of a spectral filter and a polarization filter. 14. The metrology device of clause 1, wherein the diagnostic probe includes a first diagnostic beam and a second diagnostic beam, and the first diagnostic beam and the second diagnostic beam are each configured to interact with the current target before it enters the target space. Each interaction occurs in a different area and at a different time. 15. Such as the weights and measures device of Clause 1, where the beam reducer includes a refracting telescope, a reflecting telescope or a reflective refracting telescope. 16. Such as the weights and measures device of Clause 15, in which the refracting telescope includes: The positive focal length lens configuration and the negative focal length lens configuration are separated by the sum of their focal lengths; or A pair of positive focal length lens configurations are separated by the sum of their focal lengths. 17. The weights and measures device of Clause 1, wherein the beam reducer is configured to reduce the lateral size of the irradiated light by at least five times, at least ten times, at least twenty times, or about ten times. 18. For the weighing and measuring device of Clause 1, wherein the orifice includes a circular opening, an elliptical opening, a polygonal opening or an elongated slit opening. 19. The metrology device of Clause 1, in which the detection device is positioned outside the chamber of the extreme ultraviolet (EUV) light source, the diagnostic area is inside the chamber, and the detection device is from the cavity through the optical window in the wall of the chamber The room receives light. 20. For the weights and measures device of Clause 19, the distance between the diagnostic area and the optical window can be about 200 to 500 times the distance between the diagnostic area and the target space. 21. Such as the measurement device of Clause 1, wherein the detection device includes a focusing lens at the output end of the aperture, and the focusing lens is configured to focus the sensed light onto the light sensor. 22. Such as the weights and measures device of Clause 1, in which the orifice has a range of at least 2 millimeters (mm). 23. Such as the weights and measures device of Clause 1, wherein the orifice is positioned to receive the diagnostic light at the position where the diagnostic light is collimated or non-convergent and non-divergent. 24. A measurement method, which includes: Make the diagnostic probe interact with the current target at the diagnostic area before the current target enters the target space; Collecting the diagnostic light generated by the interaction between the diagnostic probe and the current target in the diagnostic area. Collection also includes collecting the non-diagnostic light generated by the target space; Collimate diagnostic light and non-diagnostic light; The angular separation of diagnostic light and non-diagnostic light includes reducing the lateral range of diagnostic light and non-diagnostic light; After the diagnostic light and the non-diagnostic light have been angularly separated, the diagnostic light is sensed at the sensing area that is laterally displaced from the non-sensing area through which the non-diagnostic light passes; and Estimate the attributes of the current target based on the sensed diagnostic light. 25. Such as the weights and measures method of item 24, in which: Interacting the diagnostic probe with the current target at the diagnostic zone includes interacting one or more diagnostic beams with the current target at the diagnostic zone; and Collecting the diagnostic light includes collecting one or more diagnostic light beams that have been reflected from the current target, scattered from the current target, or blocked by the current target at the diagnostic area. 26. As the measurement method of Clause 24, it further includes filtering the diagnostic light based on one or more of its spectral properties and its polarization state. 27. The weights and measures method of Clause 24, wherein the diagnostic area is inside the hermetic sealed chamber of the extreme ultraviolet (EUV) light source, and also includes collecting non-diagnostic light. The diagnostic light includes receiving the light through the wall of the chamber. The non-diagnostic light transmitted by the optical window. 28. In the weights and measures method of Clause 24, reducing the lateral extent of diagnostic light and non-diagnostic light includes reducing the lateral extent of diagnostic light and non-diagnostic light by at least five times, at least ten times, at least twenty times, or about ten times. 29. As the weights and measures method of Clause 24, it further includes blocking the non-diagnostic light at the non-sensing area or redirecting the non-diagnostic light. 30. For the weights and measures method of Clause 24, the reduction of the lateral range of diagnostic light and non-diagnostic light includes one or more of the following: refracting the light and reflecting the light. 31. Such as the measurement method of Clause 24, which further includes focusing the diagnostic light at the sensing area. 32. As in the measurement method of Clause 24, reducing the horizontal range of diagnostic light and non-diagnostic light includes maintaining the collimation state of diagnostic light and non-diagnostic light. 33. As the weights and measures method of Clause 24, it further includes after the diagnostic light and the non-diagnostic light are angularly separated from each other and before the diagnostic light is sensed, passing the diagnostic light through the aperture of the optical shield, the aperture having A range larger than the range of the diagnostic light.

Other embodiments are within the scope of the following patent applications.

10: Shell 20: part 30: lithography control system 100: Weights and Measures Device 105: Goal 105': Existing target 105c: current target 105p: previous target 106: continuous flow 110: target space 115: Environment 120: Diagnostic light 121: collimated beam 122: non-diagnostic light 123: collimated beam 125: Diagnostic Probe 130: light sensor 135: Detection Device 140: mechanical filter 142: Optical collimator 145: Diagnosis area 150: beam reducer 152: Optical Path 155: Optical Mask 160: Orifice 165: Diagnostic Device 170: Control System 175: Target Supply Device 255A: Mask 255B: Mask 256A: Range 256B: range 260A: Orifice 260B: Orifice 261A: Range 261B: Range 330: Sensor 335: Detection Device 342: Optical collimator 342a: lens 342b: lens 350: beam reducer 351: Positive focal length lens configuration 351a: Convex lens 351b: Concave lens 352: Optical Path 353: Negative focal length lens configuration 354: auxiliary lens 355: Mask 357: Convergent lens 360: Orifice 430: Sensor 435: Detection Device 442: Optical collimator 442a: lens 442b: lens 450: beam reducer 451: Enter the positive focal length lens configuration 451a: Convex lens 451b: concave lens 452: Optical Path 453: Output positive focal length lens configuration 455: Mask 457: Convergent lens 460: Orifice 535: Detection Device 543: Spectral filter 544: Polarizing filter 611A: beam 611B: beam 611C_1: beam 611C_2: beam 620A: Diagnostic light 620B_1: Diagnostic light 620B_2: light 625A: Probe beam 625B_1: Probe beam 625B_2: Probe beam 625C_1: Probe beam 625C_2: Probe beam 626A: light source 626B: light source 626C_1: light source 626C_2: light source 627A: Optical components 627B: Optical components 627C_1: Optical components 627C_2: Optical components 665A: Diagnostic device 665B: Diagnostic device 665C: Diagnostic device 700: Weights and Measures Device 706: continuous flow 710: target space 715: vacuum environment 716: Chamber 725: Diagnostic Probe 735: Detection Device 736: Optical Window 745: Diagnostic Area 765: Diagnostic Device 775: Target Supply Device 776: EUV light source 777: EUV light 778: Radiation Pulse 779: output device 780: EUV Concentrator 781: Optical Source 782: Actuation System 783: control device 784: EUV light 785: Plasma 870: Control System 871: Signal Processing Module 872: Diagnostic Control Module 873: memory 874i: Input device 874o: output device 883: control device 884: Optical source actuation module 885: Target Delivery Module 979: Lithography Device 1090: process 1091, 1092, 1093, 1094, 1095, 1096: steps 1142: Refractive element 1151: Refractive element 1200: Weights and Measures Device 1220: diagnostic light 1222: non-diagnostic light 1225: Diagnostic probe beam 1230: two-dimensional sensor 1265: diagnostic device 1350: reflected beam reducer 1351: concave reflective element 1352: Optical Path 1353: convex reflective element 1450: catadioptric beam reducer 1451a: Flat reflective element 1451b: curved reflective element 1453: Convex/convergent refractive element 1555: Mask 1560: Orifice B: Exposure beam d: distance f1: focal length f2: focal length IF: Intermediate focus M: Mask R1: reflective optics R2: reflective optics R3: reflective optics S: slit t: time t1: time t2: time TR: trajectory V: rate W: substrate x: location x1: bearing x2: bearing Δd: distance/separation

Figure 1 is a schematic illustration of a metrology device including a detection device with a mechanical filter for collecting diagnostic light and non-diagnostic light generated in the environment, the diagnostic light is generated by a target in the diagnostic area and the non-diagnostic light Generated by a target in a target space different from the diagnosis area;

Figure 2A is a schematic illustration of an embodiment of a mask that can be used in the mechanical filter of Figure 1;

Fig. 2B is a schematic illustration of an embodiment of a mask that can be used in the mechanical filter of Fig. 1;

Fig. 3 is a schematic illustration of an implementation of the detection device of Fig. 1 including a beam reducer designed as a refracting Galilean telescope;

FIG. 4 is a schematic diagram of an implementation of the detection device of FIG. 1 including a beam reducer designed as a refraction Keplerian telescope;

5 is a schematic diagram of an implementation of the metrology device of FIG. 1, wherein the detection device includes one or more spectral filters and polarization filters;

Figure 6A is a schematic diagram and block diagram of an implementation of a diagnostic device that generates a single diagnostic beam;

Fig. 6B is a schematic diagram and block diagram of an implementation of a diagnostic device that generates two diagnostic beams from a single light source;

Figure 6C is a schematic diagram and block diagram of an implementation of a diagnostic device that generates two diagnostic light beams from corresponding light sources;

FIG. 7 is a schematic diagram of an embodiment of the metrology device of FIG. 1 implemented in an extreme ultraviolet (EUV) light source;

Figure 8 is a block diagram of an implementation of the control device of the metrology device of Figure 1;

FIG. 9 is a schematic diagram of an embodiment of a lithography device that receives EUV light output from the EUV light source of FIG. 7;

FIG. 10 is a flowchart of a process performed by the metrology apparatus of FIG. 1 to estimate one or more attributes of the current target;

11 is a schematic diagram of an implementation of the detection device of FIG. 1 including a beam reducer designed as a refractive Galilean telescope and in which the optical collimator and the positive focal length lens of the beam reducer are integrated into a single refractive element;

FIG. 12 is a schematic illustration of an embodiment of the metrology device of FIG. 1, in which the diagnostic probe provides backlighting to the target so that the shadow of the target is formed by the target covering at least a part of the diagnostic probe;

FIG. 13 is a schematic illustration of an implementation of the detection device of FIG. 1 including a beam reducer designed as a reflection off-axis telescope;

Fig. 14 is a schematic illustration of an implementation of the detection device of Fig. 1 including a beam reducer designed as a catadioptric off-axis telescope; and

Fig. 15 is a schematic illustration of an embodiment of the metrology device of Fig. 1, wherein the mechanical filter includes a shield that blocks diagnostic light while allowing non-diagnostic light to pass through to the sensor.

Applicants should note that the drawings may not be to scale. For example, the distance between the optical elements in the schematic illustration can be greater or less than that shown.

100: Weights and Measures Device

105: Goal

105c: current target

105p: previous target

106: continuous flow

110: target space

115: Environment

120: Diagnostic light

121: collimated beam

122: non-diagnostic light

123: collimated beam

125: Diagnostic Probe

130: light sensor

135: Detection Device

140: mechanical filter

142: Optical collimator

145: Diagnosis area

150: beam reducer

152: Optical Path

155: Optical Mask

160: Orifice

165: Diagnostic Device

170: Control System

175: Target Supply Device

TR: trajectory

Claims (33)

A weighing and measuring device, which comprises: A diagnostic device configured to allow a diagnostic probe to interact with the current target at a diagnostic area before the current target enters a target space; A detection device, which includes: A light sensor having a field of view overlapping the diagnostic area and configured to sense the light generated by the interaction between the diagnostic probe and the current target at the diagnostic area; and A mechanical filter is located between the diagnostic area and the light sensor. The mechanical filter includes a beam reducer and an optical shield. The optical shield defines a position between the beam reducer and the light sensor. An opening between the sensors; and A control system that communicates with the detection device and is configured to estimate an attribute of the current target based on the output from the light sensor. The measurement device of claim 1, wherein the mechanical filter is configured to angularly separate the diagnostic light emitted from the diagnostic area and the non-diagnostic light emitted from the target space, wherein the diagnostic light is generated in the diagnostic area An interaction between the current target and the diagnostic probe is generated. The metrology device of claim 2, wherein the non-diagnostic light includes light emitted from a plasma generated by a previous target in the target space. The measurement device of claim 2, wherein the lateral extent of the aperture is approximately the same as or greater than the lateral extent of the diagnostic light in the plane of the optical shield, and The lateral range of the optical shield is larger than or approximately the same as the lateral range of the non-diagnostic light in the plane of the optical shield. The metrology device of claim 2, wherein the optical shield is positioned such that the non-diagnostic light emitted from the target space is substantially blocked by the optical shield, and the diagnostic light substantially passes through the aperture. The metrology device of claim 1, wherein the mechanical filter includes an optical collimator between the diagnostic area and the beam reducer. Such as the metrology device of claim 6, wherein the beam reducer is an afocal beam reducer and is configured to be combined with the optical collimator to project a finite object to infinity. The metrology device of claim 6, wherein the optical collimator and the components of the beam reducer with a positive focal length closest to the optical collimator are integrated into a single refractive element. Such as the measurement device of claim 6, wherein the beam reducer is configured to maintain a collimated state of light. For example, the metrology device of claim 1, wherein the light sensor includes one or more of the following: photodiode, photoelectric crystal, light-dependent resistor, photomultiplier tube, multi-unit light receiver, four-unit light receiver, and camera. The metrology device of claim 1, wherein the diagnostic probe includes at least one diagnostic beam, and the light sensor is configured to sense the diagnosis generated by the interaction between the current target and the at least one diagnostic beam Light. The measurement device of claim 11, wherein the diagnostic light includes the diagnostic light beam reflected from the current target, scattered from the current target, or blocked by the current target. The measurement device of claim 1, wherein the detection device further includes one or more of a spectral filter and a polarization filter. The metrology device of claim 1, wherein the diagnostic probe includes a first diagnostic beam and a second diagnostic beam, and the first diagnostic beam and the second diagnostic beam are each configured to interact with the current target before it enters the target space. Interaction, each interaction occurs in a different area and a different time. Such as the measurement device of claim 1, wherein the beam reducer includes a refracting telescope, a reflecting telescope or a reflective refracting telescope. Such as the weights and measures device of claim 15, wherein the refracting telescope includes: A positive focal length lens configuration and a negative focal length lens configuration, which are separated by the sum of their focal lengths; or A pair of positive focal length lens configurations are separated by the sum of their focal lengths. The metrology device of claim 1, wherein the beam reducer is configured to reduce a lateral size of the illuminating light by at least five times, at least ten times, at least twenty times, or about ten times. The weighing device of claim 1, wherein the orifice includes a circular opening, an elliptical opening, a polygonal opening, or an elongated slit opening. The measurement device of claim 1, wherein the detection device is positioned outside a chamber of an extreme ultraviolet (EUV) light source, the diagnosis area is inside the chamber, and the detection device passes through a wall of the chamber One of the optical windows receives light from the cavity. Such as claim 19, wherein a distance between the diagnostic area and the optical window is about 200 to 500 times the size of a distance between the diagnostic area and the target space. The measurement device of claim 1, wherein the detection device includes a focusing lens at an output end of the aperture, the focusing lens is configured to focus the sensed light onto the light sensor. Such as the weighing device of claim 1, wherein the aperture has a range of at least 2 millimeters (mm). Such as the weighing device of claim 1, wherein the aperture is positioned to receive the diagnostic light at a position where the diagnostic light is collimated or non-convergent and non-divergent. A method of weights and measures, which includes: Before a current target enters a target space, a diagnostic probe is made to interact with the current target at a diagnostic area; Collecting the diagnostic light generated by the interaction between the diagnostic probe and the current target at the diagnostic area, the collection also includes collecting non-diagnostic light generated by the target space; Collimate the diagnostic light and the non-diagnostic light; Separating the diagnostic light and the non-diagnostic light angularly from each other includes reducing the lateral range of the diagnostic light and the non-diagnostic light; After the diagnostic light and the non-diagnostic light have been angularly separated, sensing the diagnostic light at a sensing area that is laterally displaced by the non-diagnostic light through a non-sensing area; and An attribute of the current target is estimated based on the sensed diagnostic light. Such as the weights and measures method of claim 24, where: Interacting the diagnostic probe with the current target at the diagnostic zone includes interacting one or more diagnostic beams with the current target at the diagnostic zone; and Collecting diagnostic light includes collecting one or more diagnostic light beams at the diagnostic area that have been reflected from the current target, scattered from the current target, or blocked by the current target. Such as the measurement method of claim 24, which further includes filtering the diagnostic light based on one or more of its spectral properties and its polarization state. The metrology method of claim 24, wherein the diagnostic area is inside an airtight chamber of an extreme ultraviolet (EUV) light source, and also includes collecting non-diagnostic light. The non-diagnostic light transmitted by one of the optical windows is the diagnostic light. The weighing method of claim 24, wherein reducing the lateral extent of the diagnostic light and the non-diagnostic light comprises reducing the lateral extent of the diagnostic light and the non-diagnostic light by at least five times, at least ten times, at least twenty times, or about ten times Times. Such as the measurement method of claim 24, which further includes blocking the non-diagnostic light at the non-sensing area or redirecting the non-diagnostic light. For the weighing method of claim 24, wherein reducing the lateral range of the diagnostic light and the non-diagnostic light includes one or more of the following: refracting the light and reflecting the light. Such as the measurement method of claim 24, which further includes focusing the diagnostic light at the sensing area. For example, the measurement method of claim 24, wherein reducing the lateral range of the diagnostic light and the non-diagnostic light includes maintaining a collimation state of the diagnostic light and the non-diagnostic light. The metrology method of claim 24, further comprising after the diagnostic light and the non-diagnostic light are angularly separated from each other and before the diagnostic light is sensed, passing the diagnostic light through an aperture of an optical shield, The aperture has a range larger than the range of the diagnostic light.

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