Improved Alignment Apparatus for a Lithography System

Abstract

A measuring device is disclosed in which a portion of the measured radiation that interacts with the mark is split into a plurality of channels or arms, and each channel or arm is spatially separated. In one version, the alignment information comprises polarization channel intensity information. In other versions, the alignment information comprises color channel intensity information.

Description

Technical Field

[0001] Cross - reference to Related Applications This application claims the priority of U.S. Application No. 63 / 390,509, filed on July 19, 2017, the entire content of which is incorporated herein by reference.

[0002] The subject matter disclosed and described herein relates to an apparatus for obtaining alignment information in a lithography system.

Background Art

[0003] A lithography apparatus applies a desired pattern to a substrate, often to a target portion of the substrate. A lithography apparatus can be used, for example, in the manufacture of integrated circuits (ICs). In this case, a patterning device, also referred to as a mask or reticle, can be used to form a circuit pattern in an individual layer of the IC. This pattern can be transferred to a target portion (e.g., including one or more dies or parts of a die) on a substrate (e.g., a silicon wafer).

[0004] Transfer of the pattern is typically achieved by imaging onto a layer of radiation - sensitive material (resist) provided on the substrate. Generally, a single substrate contains a network of adjacent target portions that are patterned successively.

[0005] In a step-and-scan optical lithography tool, alignment is performed to i) align a mask with respect to a mask stage, ii) align a wafer with respect to a wafer stage, and iii) align the mask and the wafer with respect to each other. Generally, one or more marks, for example alignment marks, are provided on a substrate to control alignment for accurately placing device features on the substrate. Various types of marks and various types of systems are known from various eras and various manufacturers. The types of alignment marks include alignment marks in a smaller format such as bi-directional fine (BF) alignment marks and composite bi-directional (CB) alignment marks.

[0006] Alignment data is obtained by an alignment sensor, for example, by a SMASH (SMart Alignment Sensor Hybrid) sensor described in U.S. Patent No. 6,961,116, issued November 1, 2005, titled "Lithographic Apparatus, Device Manufacturing Method, and Device Manufactured Thereby". This sensor employs a self-referencing interferometer (SRI) having a single detector and four different wavelengths, and extracts alignment signals with software. Another system is ATHENA (Advanced Technology using High order ENhancement of Alignment) described in U.S. Patent No. 6,297,876, issued October 2, 2001, titled "Lithographic Projection Apparatus Comprising an Alignment System for Aligning a Substrate with a Mask", which directs each of seven diffraction orders to a dedicated detector. Yet another system uses the sensor described in U.S. Patent No. 10,508,906, issued December 17, 2019, titled "Method and Apparatus for Measuring Parameters". This uses multiple polarizations for each available signal (color).

[0007] All patent applications, patents, and printed publications cited in this specification are hereby incorporated by reference in their entirety, except for definitions and disclaimers of subject matter, and except to the extent that the incorporated material conflicts with the explicit disclosure of this specification.

[0008] To improve throughput, it is required to obtain alignment information simply and quickly. This brings about the need to acquire multiple types of data in parallel, that is, simultaneously, and to make that data similarly available. In non-image-based systems, it would be advantageous for multiple channels of polarization intensity data to be simultaneously available and in a form that is easily accessible from the system.

SUMMARY OF THE INVENTION

[0009] In the following, a concise summary of one or more embodiments is presented to provide an understanding of the present invention. This summary is not an extensive overview of all contemplated embodiments, nor is it intended to identify important or essential elements of the described embodiments, nor to delineate the full scope of the described embodiments. Its sole purpose is to present, in a concise form, some concepts related to one or more embodiments as a prelude to the more detailed description that follows.

[0010] According to one aspect of an embodiment, there is disclosed a measuring device comprising a beam splitting element provided to receive measurement radiation interacting with a mark, propagate a first portion of the measurement radiation to a first channel, and propagate a second portion having optical characteristics different from those of the first portion of the measurement radiation to a second channel.

[0011] The measuring device also includes a first channel separation element provided in the first channel for spatially separating a plurality of first channel components of the first part, a first channel optical element provided for condensing the plurality of first channel components, and a first multi-core fiber having a plurality of cores provided on the focal plane of the first channel optical element, each corresponding to one of the plurality of first channel components. The measuring device also includes a second channel separation element provided in the second channel for spatially separating a plurality of second channel components of the second part, a second channel optical element provided for condensing the plurality of second channel components, and a second multi-core fiber having a plurality of cores provided on the focal plane of the second channel optical element, each corresponding to one of the plurality of second channel components.

[0012] The optical property may be polarization or color. The first channel components and the second channel components may have diffraction orders.

[0013] The beam separation element may include a polarization beam splitter provided to receive the measurement radiation and propagate a first portion of the received radiation having a first polarization to the first channel and a second portion of the received radiation having a second polarization to the second channel.

[0014] The first channel separation element may include a first segmented optical wedge, and the second channel separation element may include a second segmented optical wedge. The first segmented optical wedge and the second segmented optical wedge may be transmissive or reflective.

[0015] The first channel separation element may include a first segmented lens or diffraction grating, and the second channel separation element may include a second segmented lens or diffraction grating.

[0016] The first multi-core fiber may include one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core. The second multi-core fiber may include one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core.

[0017] At least one of the first channel separation element and the second channel separation element may be configurable. At least one of the first multi-core fiber and the second multi-core fiber may be such that at least one of the position and orientation of the light-receiving end is configurable.

[0018] According to another aspect of an embodiment, a measuring device is disclosed that includes a spatial separation element configured to receive measurement radiation that has interacted with a mark and spatially separate components of the measurement radiation, and a beam separation element configured to receive the spatially separated measurement radiation and propagate a first portion of the spatially separated measurement radiation to a first channel and a second portion having optical characteristics different from those of the first portion of the spatially separated measurement radiation to a second channel.

[0019] The measuring device also includes a first channel optical element configured to collect the first portion, and a first multi-core fiber having a plurality of cores corresponding to components in the first channel and provided on the focal plane of the first channel optical element. The measuring device also includes a second channel optical element configured to collect the second portion, and a second multi-core fiber having a plurality of cores corresponding to components in the second channel and provided on the focal plane of the second channel optical element.

[0020] For this additional aspect, the optical characteristics may be polarization or color. For this additional aspect, the first channel components and the second channel components may have diffraction orders.

[0021] For this additional aspect, the first channel separation element may include a first segmented optical wedge, and the second channel separation element may include a second segmented optical wedge. The first segmented optical wedge and the second segmented optical wedge may be transmissive or reflective.

[0022] For this additional aspect, the first channel separation element may include a first segmented lens or diffraction grating, and the second channel separation element may include a second segmented lens or diffraction grating.

[0023] The first channel separation element may include a first segmented optical wedge, and the second channel separation element may include a second segmented optical wedge. The first segmented optical wedge and the second segmented optical wedge may be transmissive or reflective.

[0024] At least one of the first channel separation element and the second channel separation element may be configurable. At least one of the first multi-core fiber and the second multi-core fiber may be configurable in terms of at least one of the position and orientation of the light receiving end.

[0025] According to another aspect of an embodiment, there is disclosed a measuring device comprising a polarization beam splitter configured to receive measurement radiation interacting with a mark and propagate a first portion of the measurement radiation having a first polarization to a first arm and a second portion of the received radiation having a second polarization to a second arm. The first arm may include a polarization beam splitter configured to receive the first portion and separate the first polarized radiation from the first portion, a first optical system configured to receive the first polarized radiation and spatially separate and focus the first polarized radiation, and a first multi-core fiber provided on a focal plane of the first optical system. The second arm may include a second optical system configured to receive the second portion and spatially separate and focus the second portion, and a second multi-core fiber provided on a focal plane of the second optical system.

[0026] The measuring device may further include a polarization rotation element disposed between the polarization beam splitter and the first optical system in the first arm.

[0027] The first optical system may include a first segmented optical wedge, and the second optical system may include a second segmented optical wedge. The first segmented optical wedge may be transmissive or reflective. The first optical system may include a segmented lens. The first optical system may include a diffraction grating.

[0028] The first channel separation element may include a first segmented optical wedge, and the second channel separation element may include a second segmented optical wedge. The first segmented optical wedge and the second segmented optical wedge may be transmissive or reflective.

[0029] At least one of the first channel separation element and the second channel separation element may be configurable. At least one of the first multi-core fiber and the second multi-core fiber may be such that at least one of the position and orientation of the light receiving end is configurable.

[0030] According to another aspect of an embodiment, there is disclosed a measuring device comprising a beam splitting element configured to receive measurement radiation interacting with a mark, propagate a first portion of the measurement radiation through a first channel, and propagate a second portion having optical properties different from those of the first portion of the measurement radiation through a second channel. The measuring device also includes a first channel separation element provided in the first channel for spatially separating a plurality of first channel components of the first portion, a first channel optical element provided for focusing the plurality of first channel components, and a first segmented detector having a plurality of first detector segments each corresponding to one of the plurality of first channel components and provided on the focal plane of the first channel optical element. The measuring device also includes a second channel separation element provided in the second channel for spatially separating a plurality of second channel components of the second portion, a second channel optical element provided for focusing the plurality of second channel components, and a second segmented detector having a plurality of second detector segments each corresponding to one of the plurality of second channel components and provided on the focal plane of the second channel optical element.

[0031] The optical properties may be polarization or color. The first channel components and the second channel components may have diffraction orders.

[0032] The beam splitting element may include a polarization beam splitter configured to receive the measurement radiation, propagate a first portion of the received radiation having a first polarization through the first channel, and propagate a second portion of the received radiation having a second polarization through the second channel.

[0033] The first channel separation element may include a first segmented optical wedge, and the second channel separation element may include a second segmented optical wedge. The first segmented optical wedge and the second segmented optical wedge may be transmissive or reflective.

[0034] The first channel separation element may include a first segmented lens or diffraction grating, and the second channel separation element may include a second segmented lens or diffraction grating.

[0035] At least one of the first channel separation element and the second channel separation element may be configurable. At least one of the position and orientation of the detector segments of the first segmented detector and the second segmented detector may be configurable.

[0036] Further embodiments, features, and advantages of the subject matter of this disclosure, as well as the structure and operation of various embodiments, will be described in detail below with reference to the accompanying drawings.

Brief Description of the Drawings

[0037] The accompanying drawings, which are incorporated herein and constitute a part of this specification, illustrate several embodiments and, together with the description in words, explain the principles of the embodiments and are further useful to enable those skilled in the relevant art to manufacture and use the embodiments.

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[0051] Further features and advantages of the disclosed subject matter, as well as the structure and operation of various embodiments of the disclosed subject matter, will be described in detail below with reference to the accompanying drawings. It should be noted that the applicability of the disclosed subject matter is not limited to the specific embodiments described herein. Such embodiments are presented herein for illustrative purposes only. Additional embodiments will be apparent to those of ordinary skill in the relevant art based on the teachings contained herein.

DETAILED DESCRIPTION OF THE INVENTION

[0052] First, FIG. 1 schematically shows an embodiment of a lithographic apparatus LA that may be related to the present system. The lithographic apparatus LA includes an illumination system (illuminator) IL configured to condition a radiation beam B. As used herein, the terms “radiation” and “beam” include all types of electromagnetic radiation, such as ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., having a wavelength of about 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., having a wavelength in the range of 5 to 20 nm), and also include particle beams such as ion beams or electron beams.

[0053] The lithographic apparatus LA also includes a support structure (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioning unit PM configured to accurately position the patterning device according to several parameters, and one or more substrate tables (e.g., wafer tables) WT (e.g., two wafer tables WTa and WTb) constructed to hold a substrate (e.g., a wafer coated with a resist) W and mechanically connected to respective positioning units PW configured to accurately position the substrate on a wafer support surface WSS according to several parameters.

[0054] The lithographic apparatus LA also comprises a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., comprising one or more dies, often called a field) of the substrate W. The projection system is supported on a reference frame RF.

[0055] As shown, the apparatus is of the transmissive type (e.g., using a transmissive mask). Alternatively, the apparatus may be of the reflective type (e.g., using a programmable mirror array of the type described above, or a reflective mask).

[0056] The illuminator IL receives the radiation beam from the radiation source SO. The radiation source and the lithographic apparatus may be separate, for example when the radiation source is an excimer laser. In such cases, the radiation source is not considered to form part of the lithographic apparatus, and the radiation beam is passed from the radiation source SO to the illuminator IL via a beam delivery system BD which includes, for example, suitable directing mirrors and / or a beam expander. In other cases, the radiation source may be an integral part of the apparatus, for example when the radiation source is a mercury lamp. The radiation source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system. When the radiation source is of the type that generates EUV radiation, generally reflective optics are used.

[0057] The illuminator IL may include an adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. Further, the illuminator IL generally comprises various other components such as an integrator IN and a condenser CO. The illumination system can include various types of optical components for directing, shaping, or controlling the radiation. In this way, the illuminator IL provides an adjusted radiation beam B having a desired uniformity and intensity distribution in its cross-section.

[0058] Illuminator IL may be operable to change the polarization of the beam, and may be operable to adjust the polarization state of the radiation beam across the pupil plane of illuminator IL using adjuster AD or a similar component. The polarization state of the radiation beam across the pupil plane of illuminator IL may sometimes be referred to as the polarization mode. By using different polarization modes, greater contrast can be achieved in the image formed on substrate W. Alternatively, the radiation beam may be unpolarized.

[0059] Illuminator IL may also be configured to linearly polarize the radiation beam such that the polarization direction of the radiation beam varies across the pupil plane of illuminator IL, i.e., the polarization direction of the radiation is different in different regions within the pupil plane of illuminator IL. The polarization state of the radiation may be selected depending on the illumination mode.

[0060] Support structure MT supports the patterning device using mechanical, vacuum, electrostatic, or other clamping techniques for holding a patterning device. The term "patterning device" as used herein should be broadly construed to refer to any device that can be used to impart a pattern to a target portion of a substrate.

[0061] The lithographic apparatus may be of a type having two or more substrate tables WTa, WTb as shown in the figure. The lithographic apparatus may be of a type having two or more patterning device tables. The lithographic apparatus may be of a type having substrate tables WTa and table WTb below the projection system without using a dedicated substrate for, for example, facilitating measurement and / or cleaning. In such a "multi-stage" machine, the additional tables may be used in parallel, or the preparation process may be carried out on one or more other tables while one or more tables are being used for exposure. For example, alignment measurement using the alignment sensor AS, and / or level (height, inclination, etc.) measurement using the level sensor LS may be performed as preparation for exposure while a wafer on one wafer table is being exposed to a wafer on another wafer table.

[0062] The lithographic apparatus may also be of a type in which at least a portion of the substrate can be covered so as to fill the space between the projection system and the substrate with a liquid having a relatively high refractive index, such as water.

[0063] In the operation of a lithographic apparatus, a radiation beam B is conditioned and supplied by an illumination system IL. The radiation beam B is incident on a patterning device (e.g., a mask) MA held on a support structure (e.g., a mask table) MT and is patterned by the patterning device. The radiation beam B that has passed through and been patterned by the patterning device MA passes through a projection system PS, which focuses the beam onto a target portion C of a substrate W. With the aid of respective positioning units PW and position sensors IF (e.g., an interferometer device, a linear encoder, a two-dimensional encoder, or a capacitive sensor), the wafer table WTa or WTb can be accurately moved, for example, to position different target portions C within the path of the patterned radiation beam B. Similarly, another positioning unit and another position sensor (not explicitly depicted in FIG. 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, for example, after mechanical retrieval from a mask library or during a scan.

[0064] The patterning device MA and the substrate W may be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. The illustrated substrate alignment marks occupy dedicated target portions, but may also be arranged in the space between target portions (scribe lane alignment marks). Similarly, in applications where a plurality of dies are provided on the patterning device MA, the alignment marks of the patterning device may be arranged between the dies.

[0065] The substrate referred to in this specification may be processed, before or after exposure, by, for example, a track (usually a tool for applying a resist layer to the substrate and developing the exposed resist), a metrology tool, or an inspection tool. Where applicable, the disclosure of this specification can be applied to such substrate processing tools and other substrate processing tools. Further, the substrate may be processed multiple times, for example, to create a multilayer IC, and the term "substrate" as used herein may refer to a substrate that already includes one or more processed layers.

[0066] In an alignment sensor, a plane wave of incident light strikes an alignment mark, generating both positive and negative reflection diffraction orders. The zero order is removed by a physical stop within the alignment sensor, and the diffracted plus and minus orders interfere with each other, causing a sinusoidal intensity signal. From this sinusoidal intensity signal, the alignment position is calculated from the phase of the Fourier transform of the intensity signal. In the absence of mark asymmetry, the phase of the plus order is equal to the phase of the minus order, and no alignment position deviation (APD) due to the interference of the plus and minus orders occurs. However, in the presence of mark asymmetry, the phases of the plus and minus orders are not equal, and this phase difference causes an APD error. Since this phase difference depends on wavelength and polarization, different APDs are measured for each wavelength and polarization channel.

[0067] FIG. 2 is a schematic diagram of an alignment device 200 that may be implemented as part of a lithographic apparatus LA according to some embodiments. In some embodiments, the alignment device 200 may be configured to align a substrate (e.g., the substrate W of FIG. 1) with respect to a patterning device (e.g., the patterning device MA of FIG. 1). The alignment device 200 may further be configured to detect the position of an alignment mark on the substrate and use the detected position of the alignment mark to align the substrate with respect to the patterning device or other components of the lithographic apparatus LA.

[0068] In some embodiments, the alignment device 200 can include an illumination system 212, a beam splitter 214, an interferometer 226, a detector 228, a beam analyzer 230, and a processor 232. The illumination system 212 may be configured to supply a radiation beam 213. In some embodiments, the beam splitter 214 may be configured to receive the radiation beam 213 and split the radiation beam 213 into at least two radiation sub - beams. For example, the radiation beam 213 may be split into radiation sub - beams 215 and 217 as shown in FIG. 2. The beam splitter 214 may further be configured to direct the radiation sub - beam 215 onto a substrate 220 placed on the stage 222. In one example, the stage 222 is movable along direction 224. The radiation sub - beam 215 may be configured to irradiate an alignment mark or target 218 disposed on the substrate 220.

[0069] In some embodiments, the beam splitter 214 may further be configured, according to one embodiment, to receive the diffracted radiation beam 219 and split the diffracted radiation beam 219 into at least two radiation sub - beams. The diffracted radiation beam 219 may be split into diffracted radiation sub - beams 229 and 239 as shown in FIG. 2.

[0070] It should be noted that the present disclosure is not limited in this way even though the beam splitter 214 is shown as directing the radiation sub - beam 215 towards the alignment mark or target 218 and the diffracted radiation sub - beam 229 towards the interferometer 226. It will be apparent to those skilled in the relevant art that other optical configurations may be used to illuminate the alignment mark or target 218 on the substrate 220 and obtain a similar result of detecting the image of the alignment mark or target 218.

[0071] As shown in FIG. 2, the interferometer 226 may be configured to receive the radiation sub-beam 217 and the diffracted radiation sub-beam 229 via the beam splitter 214. In an exemplary embodiment, the diffracted radiation sub-beam 229 may be at least a portion of the radiation sub-beam 215 that has interacted with (e.g., been reflected from) the alignment mark or target 218. In an example of this embodiment, the interferometer 226 may comprise any suitable set of optical elements, such as a combination of prisms, configured to form two images of the alignment mark or target 218 based on the received diffracted radiation sub-beam 229. It should be understood that a good quality image need not be formed, but the features of the alignment mark 218 should be resolvable. The interferometer 226 may further be configured as an SRI that rotates one of the two images 180° relative to the other of the two images and recombines the rotated image and the non-rotated image by interference.

[0072] In some embodiments, the detector 228 may be configured to receive the recombined image via the interferometer signal 227 and detect interference as a result of the recombined image when the alignment axis 221 of the alignment device 200 passes through the center of symmetry (not shown) of the alignment mark or target 218. Such interference may, according to an exemplary embodiment, be due to the alignment mark or target 218 being 180° symmetric and the recombined images interfering constructively or destructively. Based on the detected interference, the detector 228 may further be configured to determine the position of the center of symmetry of the alignment mark or target 218 and, as a result, detect the position of the substrate 220. According to one example, the alignment axis 221 may be aligned with an optical beam that is perpendicular to the substrate 220 and passes through the image rotation center of the interferometer 226. The detector 228 may further be configured to implement sensor characteristics and estimate the position of the alignment mark or target 218 by interacting with the wafer mark process variations.

[0073] In a further embodiment, the detector 228 determines the position of the center of symmetry of the alignment mark or target 218 by performing one or more of the following measurements.

[0074] Measuring the positional variation (positional shift due to color) for various wavelengths.

[0075] Measuring the positional variation (positional shift due to diffraction order) for various orders.

[0076] Measuring the positional variation (positional shift due to polarization) for various polarizations.

[0077] This data can be obtained by any type of alignment sensor, such as, for example, the above-described SMASH sensor that employs a single detector and an SRI having four different wavelengths and extracts the alignment signal with software, as described in U.S. Patent No. 6,961,116, or the above-described ATHENA sensor that directs each of seven diffraction orders to a dedicated detector, as described in U.S. Patent No. 6,297,876, or a sensor that uses multiple polarizations for each available signal (color), as described in U.S. Patent No. 10,508,906. See also U.S. Patent No. 10,962,887, issued March 30, 2021 (entitled "Lithography Method"), and H. Megens et al., "Holistic feedforward control for the 5 nm node and beyond," Optical Microlithography XXXII, Proc. of SPIE Vol. 10961 109610K, doi: 10.1117 / 12.2515449.

[0078] In some embodiments, the beam analyzer 230 may be configured to receive and determine the optical state of the diffracted radiation of the sub-beam 239. The optical state may be a measurement of the beam wavelength, polarization, or beam profile. The beam analyzer 230 may further be configured to determine the position of the stage 222 and to correlate the position of the stage 222 with the position of the alignment mark or the center of symmetry of the target 218. Thereby, the position of the alignment mark or the target 218, and thus the position of the substrate 220, can be accurately known with reference to the stage 222. Alternatively, the beam analyzer 230 may be configured to determine the position of the alignment device 200 or other reference elements, whereby the center of symmetry of the alignment mark or the target 218 can be known with reference to the alignment device 200 or other reference elements. The beam analyzer 230 may be a point polarimeter or an imaging polarimeter having some form of wavelength band selectivity. In some embodiments, the beam analyzer 230 may be directly integrated into the alignment device 200, or according to other embodiments, may be connected via some types of optical fibers such as polarization-maintaining single-mode, multi-mode, or imaging.

[0079] In some embodiments, an array of detectors (not shown) may be connected to the beam analyzer 230. For example, the detector 228 may be an array of detectors. Many options are conceivable for the detector array, such as multi-mode fibers, discrete PIN detectors per channel, CCD or CMOS (linear) arrays. By using a bundle of multi-mode fibers, the heat dissipation element can be placed away from the location, and the stability can be enhanced. Discrete PIN detectors provide a wide dynamic range, but each requires an independent preamplifier. Therefore, the number of PIN detectors that can be used is limited. The CCD linear array has many elements capable of high-speed readout and is particularly meaningful when phase step detection is used.

[0080] FIG. 3 shows an example of marks 252, 254 that can be provided on a substrate W to measure X-position alignment and Y-position alignment, respectively. Each mark in this example comprises a series of bars formed in a process layer applied or etched on the substrate W. The bars are arranged at regular intervals and function as a diffraction grating, so the marks can be regarded as diffraction gratings having a well-known spatial period (pitch). The bars of the X-direction mark 252 are parallel to the Y-axis and give periodicity in the X direction, and the bars of the Y-direction mark 254 are parallel to the X-axis and give periodicity in the Y direction. The circle 256 represents the illumination spot, i.e., the effective grating area for a given illumination spot position.

[0081] FIG. 4 shows the design of a bidirectional fine (“BF”) alignment mark 260 for use in a similar alignment measurement system, whereby X-position alignment and Y-position alignment can be obtained in a single optical scan by the illumination spot 256. The mark 260 has bars arranged at 45 degrees with respect to both the X-axis and the Y-axis. The use of such a modified mark 260 for alignment measurement can be performed using the technique described in U.S. Patent No. 8,208,121, issued on June 26, 2012, entitled “Alignment Marks and Alignment Method of a Substrate Having Alignment Marks”. The BF alignment mark has typical dimensions of 160 μm × 40 μm. Another type of alignment mark that can be used is a composite bidirectional (“CB”) mark having typical dimensions of 40 μm × 50 μm.

[0082] Generally, an alignment sensor is configured to determine the position of such an alignment target having a periodic structure by emitting radiation in a plurality of intensity channels. See U.S. Patent No. 10,466,601, issued on November 5, 2019, entitled “Alignment Sensor for a Lithographic Apparatus”. The plurality of radiation beams output by the arrangement of the optical components may be coupled to a delivery element that may be an optical multi-core fiber. Each radiation beam is coupled to a different physical channel of the delivery element, i.e., a different core of the multi-core fiber.

[0083] More specifically, in a known configuration, the illumination light source may comprise four individual light sources for providing radiation at four wavelengths, for example, green (G), red (R), near infrared (N), and far infrared (F). These four different wavelength radiations are referred to herein as four-color radiations regardless of whether they are in the visible or non-visible part of the electromagnetic spectrum. All light sources are linearly polarized, the radiations of G and N are oriented in the same direction as each other, the radiations of R and F are polarized in the same direction as each other, and the polarization of G and N is orthogonal to each other.

[0084] The four colors are transported by polarization-maintaining fibers to a multiplexer, where they are combined into a single composite beam comprising all four colors. The composite beam is focused into a narrow beam that interacts (e.g., reflects and / or diffracts) with a periodic structure (e.g., a diffraction grating) of alignment marks formed on a substrate. At least a part of the interacting beam, i.e., at least a part of the portion of the beam that has interacted with the alignment marks, can be focused by an objective lens.

[0085] The interacting beam carrying alignment information is then carried to the SRI. The SRI splits this information-carrying beam into two parts with orthogonal polarizations, rotates these parts 180° relative to each other about the optical axis, and combines them into an output radiation beam. After exiting the SRI, the optical signal of the output radiation beam is split into two paths by a beam splitter. One path contains the sum of the two rotated fields, and the other path contains the difference thereof.

[0086] In this example, one polarization is used for the illumination of each color. It is also possible to use two polarizations for each color, in which case the polarization is changed between readings (or time-division multiplexed during reading).

[0087] The radiation of each path is focused by its respective collector lens assembly. Thereafter, the radiation passes through an aperture that removes most of the radiation from outside the spot on the substrate. The multimode fiber transmits the focused radiation of each path to its respective demultiplexer. The demultiplexer splits each path into the original four colors, and a total of eight optical signals are sent to the detector. The processing unit receives the intensity waveforms from the eight detectors and processes them to perform position measurement.

[0088] Note that the alignment sensor may include optical components and elements other than those described above. For example, the alignment sensor may be composed of one or more beam shaping components such as a polarizer, a quarter-wave plate, or a half-wave plate.

[0089] According to one aspect of an embodiment, the use of a channel separation element, such as a wedge, can be combined with the use of a multicore fiber or a segmented detector to improve the detection of intensity channels. In one embodiment, the light beam for detection passes through a segmented wedge and a lens. At the focus of the lens, a number of spots corresponding to the number of segments of the wedge appear. For example, if the wedge has four segments or quadrants, four spots corresponding to the four quadrants of the wedge appear.

[0090] According to one aspect of an embodiment, as shown in FIG. 5, the radiation 802 from an illumination light source (not shown explicitly in FIG. 5) interacts with a mark 805 that may be an alignment mark. The objective lens 800 receives the radiation 815 that has interacted with the alignment mark 805. The interacted radiation 815 passes through the spot mirror 810.

[0091] In other words, the radiation 815 that interacts with the mark 805 is captured by the objective lens 800 and collimated into an information transfer beam. This beam propagates to a dual self-referencing interferometer (DSRI) (not explicitly shown in FIG. 5) of the type disclosed in U.S. Patent No. 6,961,116 mentioned above. The DSRI processes a portion of the received beam 815 and outputs separate beams for different wavelengths. The intensity of each of the separate beams is detected by sensors. The intensity signals from the individual sensors are supplied to a processor. By a combination of optical processing and computational processing, values of the X and Y positions on the substrate with respect to the frame MF are obtained.

[0092] However, depending on the implementation, it may be beneficial to split a portion of the radiation that interacts with the mark and process that radiation in another way to obtain additional measurement information. Thus, according to one aspect of an embodiment, as shown in FIG. 5, a non-polarizing beam splitter (NBS) 820 splits the beam 815 into two portions. One portion of the split beam continues to the DSRI for alignment analysis as described above. The other portion of the split beam passes through a polarizing beam splitter (PBS) 830.

[0093] The PBS830 functions as a beam splitting element that splits a beam into two beams with different optical characteristics (polarization in this example), thereby forming a first polarization arm or channel 835 and a second polarization arm or channel 837. The radiation within the first polarization channel 835 passes through a first channel separation element 854 that can be implemented as an optical wedge. However, as will be explained in more detail below, those skilled in the art will understand that in all embodiments, the channel separation element may be implemented using components other than a transmissive optical wedge. However, it is necessary for those components to perform the function of creating a spatial separation of the radiation passing through them. Other examples include a reflective optical wedge, a diffraction grating, a segmented lens array, etc. The orientation of the first channel separation element 854 implemented as an optically wedged segmented into four is shown in the inset WO (wedge orientation) where different patterns are assigned to each segment or quadrant of the wedge.

[0094] The radiation within the second channel 837 is directed by a folding mirror 840 to pass through a second channel separation element 856 that can also be implemented as an optical wedge. In the illustrated example, the optical wedge is divided into four segments, but different numbers of segments may be used depending on the position of the diffraction order and if it is desired to separate lower diffraction orders from higher diffraction orders. Also, the orientation of the second channel separation element 856 implemented as a four-segment optical wedge is shown in the inset WO where different patterns are assigned to each quadrant of the wedge. The same is true for the insets WO shown in FIGS. 6 and 7.

[0095] Channel separation elements 854 and 856 create a spatial separation of the radiation passing through them. A plurality of radiation spots can be regarded as channel components that pass through the optical channel separation element 854 and pass through the lens 860. The channel components passing through the channel separation element 856 are focused by the lens 865. Thereafter, the intensities of the channel components are individually detected. In the illustrated example, each of the lens 860 and the lens 865 includes an optical element provided to focus each of the respective channel components, i.e., radiation spots. It will be understood that in this embodiment and other embodiments, these optical elements may be composed of one lens or a plurality of lenses.

[0096] In the example of FIG. 5, the multi-core fiber 870 may include a multi-mode fiber core, a single-mode fiber core, or both, and is disposed at the focal point of the lens 860. The lens 865 focuses the received plurality of radiation spots onto a multi-core fiber 880 that may include a multi-mode fiber core, a single-mode fiber core, or both. Thus, the spots are optically coupled to the respective cores of the multi-core fiber. According to one aspect of this embodiment, the multi-core fiber transmits the radiation to a remote detector that generates a signal based on the radiation. And this signal is processed to derive alignment information.

[0097] Those skilled in the art will understand that the channel separation elements disclosed herein are configurable. For example, they may be movable, i.e., translatable in any direction parallel or orthogonal to the beam passing through them. Those skilled in the art will also understand that the channel separation elements disclosed herein may be configurable in the sense that they are rotatable. For example, they may be rotatable about an axis parallel or orthogonal to the beam passing through them.

[0098] One skilled in the art will understand that the multi-core fiber implemented as disclosed herein can be similarly configured and changed. For example, the portion of the multi-core fiber arranged to receive the radiation spot, i.e., the light receiving end, may be movable, i.e., translatable in any direction such as parallel or perpendicular to the arriving beam. One skilled in the art will also understand that the light receiving end of the multi-core fiber disclosed herein may be configurable in the sense that it has different possible orientations. For example, it may be rotatable about an axis parallel or perpendicular to the arriving radiation.

[0099] The number of cores in each multi-core fiber generally corresponds to the number of segments of the optical wedge. As described above, it can include multi-mode fiber cores, single-mode fiber cores, or both, so as to apply to all multi-core fibers described herein. Thus, in the illustrated example, each of the multi-core fibers 870 and 880 includes four cores. The multi-core fiber 870 receives the radiation 872 having one polarization state, and the other multi-core fiber 880 receives the radiation 882 having another polarization state.

[0100] Each of the four spots 872 of the radiation respectively corresponds to a similarly patterned segment of such a wedge when the channel separation element 854 is implemented as the optical wedge of the insertion diagram WO. Each of the four spots 882 of the radiation respectively corresponds to a similarly patterned segment of such a wedge when the channel separation element 856 is implemented as the optical wedge of the insertion diagram WO. The same also applies to the insertion diagram WO shown in FIGS. 6 and 7. The multi-core optical fiber transmits the radiation it receives to a sensor coupled to an analyzer that extracts alignment information from the respective intensities of the spots. This enables the use of two wedges to simultaneously read out the information of each of the two polarization states.

[0101] FIG. 6 shows a configuration similar to that of the embodiment of FIG. 5, except that the embodiment of FIG. 6 uses only a single wedge disposed between NBS820 and PBS830. Accordingly, the configuration of FIG. 6 includes an objective lens 800 that receives radiation interacting with mark 805. The radiation from objective lens 800 passes through a spot mirror 810 that blocks radiation not used for alignment determination.

[0102] The radiation from spot mirror 810 propagates to NBS820. One split portion of the radiation from NBS820 travels towards DSRI. The other portion of the radiation passes through optical wedge 825 and travels towards PBS830. Thus, the spatial separation of the channels of each beam is achieved before the radiation is split into two separate beams, making it possible to use only a single wedge. One beam from PBS830, the first channel radiation 835, propagates through lens 860 to the point where it is coupled to multi-core fiber 870. Similarly, the other beam from PBS830, the second channel radiation 837, is reflected by folding mirror 840, passes through lens 865, and is then coupled to multi-core optical fiber 880. Four spots corresponding to the four quadrants of wedge 825 appear at the focal point of the lens. Accordingly, in this embodiment, it is possible to read out both polarization states using a single wedge.

[0103] Furthermore, various alternative designs are possible. For example, a configuration with two separate polarization resolution arms is also possible. Such a configuration is shown in FIG. 7. In the embodiment shown in FIG. 7, the radiation from the spot mirror 810 is split by the PBS 1000. A portion of the split radiation is reflected by the folding mirror 840 towards the optical wedge 856, focused by the lens 885, and coupled to the multi-core fiber 880. The other portion of the radiation split by the PBS 1000 passes through the HWP 1010 that rotates the polarization by 90 degrees. The polarization-rotated radiation then passes through the second PBS 1020, which splits the radiation again. A portion of the radiation is directed towards the DSRI. The other portion of the radiation is directed towards the folding mirror 1030, passes through the optical wedge 854, and through the lens 860 and is coupled to the multi-core fiber 870.

[0104] In these embodiments, the diffraction order is extracted by the NBS between the spot mirror and the DSRI. The portion of the beam reflected from the NBS is reflected by a polarization beam splitter (PBS) into the "intensity channel" arm that filters the polarization channel. Each polarization channel is transmitted through an optical wedge so that each segment obtains a different beam direction.

[0105] Both polarization channels are focused using their respective lenses. Since each segment of the diffraction order is spatially separated, i.e., has a different angle, the foci on the fiber contain four spots. Each spot is coupled to a respective fiber core and in some embodiments can be connected to a demultiplexer (DMUX) in a known manner. Finally, signals based on the intensity of each spot are generated and these signals are processed to obtain alignment information.

[0106] As will be appreciated, according to one aspect of an embodiment, the design is compact in that the number of components used is relatively small. It also relies only on the use of passive fixed elements and does not require switchable components or actuators.

[0107] When diffraction orders are spatially separated in the pupil using segmented wedges, such wedges typically have the advantage of introducing only a small amount of dispersion. One possible implementation of such a segmented wedge is shown in FIG. 8. As shown, the segmented optical wedge 1100 is composed of four similar segments 1110 symmetrically arranged to divide the pupil into four separate regions. Such a segmented optical wedge 1100 can be fabricated, for example, by bonding four segments. The principles elucidated herein are not limited to systems using four segments, but can also be applied to systems using segments of different numbers and / or orientations and / or shapes, for example, to capture different higher orders. The number and position of the fiber cores generally scale with the number of segments. In some embodiments, each segment has the same dimensions and is uniformly distributed over the pupil. It will be appreciated that this need not be the case for all applications.

[0108] In the above description, the optical wedge used in the exemplary embodiment is transmissive. Instead, it will be appreciated that a reflective optical wedge can be used if the optical path and the arrangement of other components are appropriately changed.

[0109] In embodiments where dispersion is utilized, the spatial separation of diffraction orders can be performed, for example, using a diffraction grating, and as a result, the deflection angle will exhibit a strong dependence on the wavelength.

[0110] In the above example, individual channels are created using polarization filtering, but it will be understood that color filtering can also be used to create channels. This is shown in FIG. 9. Incident beam 803 is composed of four colors, for example red, green, near-infrared, and far-infrared. Spectral splitting element 827 splits the incident radiation into two beams (color channels) with different spectral characteristics. Spectral splitting element 827 may be, for example, a spectral beam splitter. Channel separation elements 852 and 858 may be diffraction gratings that cause physical separation for different colors. In such a case, depending on the application, it may be advantageous to use a multi-core fiber having more than four cores.

[0111] Another advantage of the above-described exemplary embodiments is that they can be implemented using a relatively small number of DMUX modules.

[0112] As another option for the combination of an optical wedge and a lens, it will be understood that, for example, as shown in FIG. 10, a segmented lens array may be used. A segmented lens array 1150 implemented as a 2×2 segmented lens array, such as used in partitioned aperture wavefront imaging (PAW lens), is shown. In the illustrated example, segmented lens array 1150 is a four-leaf lens composed of four lenses 1160 that are cut off-axis and adhered. Images are obtained for each quadrant from a portion 1170 near the intersection with the other lenses of lens 1160.

[0113] In the above-described embodiments, lenses such as lenses 860 and 865 focus the radiation spot on respective multi-core fibers for remote detection. According to another aspect of an embodiment, the radiation spot can be focused on respective segments of a segmented detector such as a 4-segment detector (also called a quadrant detector or simply a 4-detector). Such a configuration is shown in FIG. 11, where each set of spots is focused on a respective segmented detector. Specifically, the four spots focused by lens 860 are focused on respective segments of segment detector 1200, and the four spots focused by lens 865 are focused on respective segments of segment detector 1210. Segment detectors 1200 and 1210 generate signals indicating the intensity of the spots on each segment. These signals are supplied to processor 1230, and processor 1230 uses the signals to generate alignment information.

[0114] FIG. 12A is a side view of segmented detector 1200, and FIG. 12B is a plan view of segmented detector 1200. As seen in FIG. 12B, segmented detector 1200 can have four segments 1200a, 1200b, 1200c, 1200d. It will be understood that the rotational orientation of segmented detectors 1200 and 1210 can be set to be changed such that one or both of segmented detectors 1200 and 1210 are rotated to align the segments with respective radiation spots. In some embodiments, the positions of segmented detectors 1200 and 1210 can be set to be changed such that one or both of segmented detectors 1200 and 1210 are moved laterally to align the segments with respective radiation spots, or are moved axially to adjust the focus of the lens on the plane of the detector.

[0115] Embodiments of the present invention may be implemented in part in hardware, firmware, software, or any combination thereof. Embodiments of the present invention may also be implemented in part as instructions stored on a machine-readable medium that can be read and executed by one or more processors. The machine-readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device). For example, the machine-readable medium may include read-only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustic, or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), among others.

[0116] The above description includes examples of multiple embodiments. Of course, it is not possible to describe all possible combinations of components or methodologies for the purpose of describing the foregoing embodiments, but those skilled in the art will recognize that many more combinations and permutations of the various embodiments are possible. Accordingly, the described embodiments are intended to embrace all such changes, modifications, and variations that fall within the spirit and scope of the appended claims. Further, as long as the term "comprising" is used in either the detailed description or the claims, such term is intended to be inclusive in the same manner as the term "including" is used as a transitional phrase in a claim. Additionally, elements of the described aspects and / or embodiments may be described or claimed in the singular, but the plural is contemplated unless explicitly limited to the singular. Moreover, all or part of any aspect and / or embodiment may be utilized with all or part of any other aspect and / or embodiment, unless otherwise specified.

[0117] It should be understood that it is the section of the detailed description of the invention, rather than the sections of the abstract and summary, that is intended to be used for interpreting the claims. The sections of the abstract and summary can show one or more exemplary embodiments of the invention contemplated by the inventor, but not all, and thus are not intended to limit the invention and the appended claims in any way.

[0118] As described above, the present invention has been described with the aid of functional blocks showing the implementation of specific functions and their relationships. The boundaries of these functional blocks are arbitrarily defined herein for the convenience of explanation. As long as the specified functions and their relationships are properly implemented, other boundaries can be defined.

[0119] The embodiments can be further described using the following sections. 1. A beam splitting element configured to receive measurement radiation interacting with a mark, propagate a first portion of the measurement radiation through a first channel, and propagate a second portion having optical characteristics different from those of the first portion of the measurement radiation through a second channel; A first channel separation element provided in the first channel and configured to spatially separate a plurality of first channel components of the first portion; A first channel optical element configured to collect the plurality of first channel components; A first multi-core fiber having a plurality of cores each corresponding to one of the plurality of first channel components, the first multi-core fiber having a light receiving end provided on a focal plane of the first channel optical element; A second channel separation element provided in the second channel and configured to spatially separate a plurality of second channel components of the second portion; A second channel optical element configured to collect the plurality of second channel components; A second multi-core fiber having a plurality of cores each corresponding to one of the plurality of second channel components, the second multi-core fiber having a light receiving end provided on a focal plane of the second channel optical element, and a measuring device comprising the same. 2. The measurement device according to paragraph 1, wherein the optical characteristic is polarization. 3. The measurement device according to paragraph 1, wherein the optical characteristic is color. 4. The measurement device according to paragraph 1, wherein the first channel component and the second channel component have diffraction orders. 5. The measurement device according to paragraph 1, wherein the beam separation element comprises a polarization beam splitter provided to receive the measurement radiation and propagate a first portion of the received radiation having a first polarization to the first channel and a second portion of the received radiation having a second polarization to the second channel. 6. The measurement device according to paragraph 1, wherein the first channel separation element comprises a first segmented optical wedge, and the second channel separation element comprises a second segmented optical wedge. 7. The measurement device according to paragraph 6, wherein the first segmented optical wedge and the second segmented optical wedge are transmissive. 8. The measurement device according to paragraph 6, wherein the first segmented optical wedge and the second segmented optical wedge are reflective. 9. The measurement device according to paragraph 1, wherein the first channel separation element comprises a first segmented lens, and the second channel separation element comprises a second segmented lens. 10. The measurement device according to paragraph 1, wherein the first channel separation element comprises a first diffraction grating, and the second channel separation element comprises a second diffraction grating. 11. The measurement device according to paragraph 1, wherein the first multi-core fiber comprises one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core, and the second multi-core fiber comprises one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core. 12. The measurement device according to paragraph 1, wherein at least one of the first channel separation element and the second channel separation element is settable to be changeable. 13. The measuring device according to section 1, wherein at least one of the first multi-core fiber and the second multi-core fiber is capable of changing at least one of the position and orientation of the light-receiving end. 14. A spatial separation element that receives the measurement radiation interacting with the mark and is provided to spatially separate the components of the measurement radiation; A beam separation element that receives the spatially separated measurement radiation, propagates a first portion of the spatially separated measurement radiation having a first optical characteristic to a first channel, and propagates a second portion having an optical characteristic different from that of the first portion of the spatially separated measurement radiation to a second channel; A first channel optical element provided to condense the first portion; A first multi-core fiber having a plurality of cores provided on the focal plane of the first channel optical element, corresponding to the components in the first channel respectively; A second channel optical element provided to condense the second portion; A measuring device comprising a second multi-core fiber having a plurality of cores provided on the focal plane of the second channel optical element, corresponding to the components in the second channel respectively. 15. The measuring device according to section 14, wherein the optical characteristic is polarization. 16. The measuring device according to section 14, wherein the optical characteristic is color. 17. The measuring device according to section 14, wherein the components have diffraction orders. 18. The measuring device according to section 14, wherein the beam separation element comprises a polarization beam splitter provided to receive the spatially separated measurement radiation, propagate a first portion of the measurement radiation having a first polarization to the first channel, and propagate a second portion of the measurement radiation having a second polarization to the second channel. 19. The measuring device according to section 14, wherein the separation element comprises a segmented optical wedge. 20. The measuring device according to section 19, wherein the segmented optical wedge is a transmission type. 21. The measuring device according to section 19, wherein the segmented optical wedge is a reflection type. 22. The measurement device according to section 14, wherein the channel separation element comprises a segmented lens. 23. The measurement device according to section 14, wherein the channel separation element comprises a diffraction grating. 24. The measurement device according to section 14, wherein the first multi-core fiber comprises one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core, and the second multi-core fiber comprises one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core. 25. The measurement device according to section 14, wherein at least one of the first channel separation element and the second channel separation element is configurable. 26. The measurement device according to section 14, wherein at least one of the first multi-core fiber and the second multi-core fiber is configurable in terms of at least one of the position and orientation of the light-receiving end. 27. A polarizing beam splitter configured to receive measurement radiation that has interacted with a mark and propagate a first portion of the measurement radiation having a first polarization to a first arm and a second portion of the received radiation having a second polarization to a second arm. The first arm comprises a polarizing beam splitter configured to receive the first portion and separate a first polarized radiation from the first portion, a first optical system configured to receive the first polarized radiation and spatially separate and focus the first polarized radiation, and a first multi-core fiber provided on a focal plane of the first optical system. The second arm comprises a second optical system configured to receive the second portion and spatially separate and focus the second portion, and a second multi-core fiber provided on a focal plane of the second optical system. 28. The measurement device according to section 27, further comprising a polarization rotation element disposed between the polarizing beam splitter and the first optical system in the first arm. 29. The measurement device according to paragraph 27, wherein the first optical system includes a first segmented optical wedge, and the second optical system includes a second segmented optical wedge. 30. The measurement device according to paragraph 29, wherein the first segmented optical wedge is a transmissive type. 31. The measurement device according to paragraph 29, wherein the first segmented optical wedge is a reflective type. 32. The measurement device according to paragraph 27, wherein the first optical system includes a segmented lens. 33. The measurement device according to paragraph 27, wherein the first optical system includes a diffraction grating. 34. The measurement device according to paragraph 27, wherein the first multi-core fiber includes one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core, and the second multi-core fiber includes one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core. 35. The measurement device according to paragraph 27, wherein at least one of the first channel separation element and the second channel separation element is capable of setting change. 36. The measurement device according to paragraph 27, wherein at least one of the first multi-core fiber and the second multi-core fiber is capable of setting change in at least one of the position and orientation of the light receiving end. 37. A beam separation element configured to receive measurement radiation that has interacted with a mark, propagate a first portion of the measurement radiation to a first channel, and propagate a second portion having optical characteristics different from those of the first portion of the measurement radiation to a second channel; A first channel separation element provided in the first channel and spatially separating a plurality of first channel components of the first portion; A first channel optical element provided to condense the plurality of first channel components; A first segmented detector having a plurality of first detector segments corresponding to each of the plurality of first channel components, the plurality of first detector segments being provided on a focal plane of the first channel optical element; A second channel separation element provided in the second channel for spatially separating a plurality of second channel components of the second portion; A second channel optical element provided to collect the plurality of second channel components; A measuring apparatus comprising: a second segmented detector having a plurality of second detector segments corresponding to each of the plurality of second channel components, the plurality of second detector segments being provided on a focal plane of the second channel optical element. 38. The measuring apparatus according to paragraph 37, wherein the optical characteristic is polarization. 39. The measuring apparatus according to paragraph 37, wherein the optical characteristic is color. 40. The measuring apparatus according to paragraph 37, wherein the first channel component and the second channel component have diffraction orders. 41. The measuring apparatus according to paragraph 37, wherein the beam separation element includes a polarization beam splitter provided to receive the measurement radiation and propagate a first portion of the received radiation having a first polarization to the first channel and a second portion of the received radiation having a second polarization to the second channel. 42. The measuring apparatus according to paragraph 37, wherein the first channel separation element includes a first segmented optical wedge, and the second channel separation element includes a second segmented optical wedge. 43. The measuring apparatus according to paragraph 42, wherein the first segmented optical wedge and the second segmented optical wedge are transmissive. 44. The measuring apparatus according to paragraph 42, wherein the first segmented optical wedge and the second segmented optical wedge are reflective. 45. The measuring apparatus according to paragraph 37, wherein the first channel separation element includes a first segmented lens, and the second channel separation element includes a second segmented lens. 46. The measuring device according to paragraph 37, wherein the first channel separation element includes a first diffraction grating, and the second channel separation element includes a second diffraction grating. 47. The measuring device according to paragraph 37, wherein at least one of the first segmented detector and the second segmented detector is configured such that at least one of the position and orientation of the detector segments can be changed.

[0120] The above-described embodiments and other embodiments are included in the following claims.

Claims

1. A beam splitting element configured to receive measurement radiation that has interacted with a mark, propagate a first portion of the measurement radiation through a first channel, and propagate a second portion of the measurement radiation that has optical characteristics different from those of the first portion of the measurement radiation through a second channel; A first channel separation element provided in the first channel and spatially separating a plurality of first channel components of the first portion; A first channel optical element provided to focus the plurality of first channel components; A first multi-core fiber having a plurality of cores each corresponding to one of the plurality of first channel components, the first multi-core fiber having a light receiving end provided on a focal plane of the first channel optical element; A second channel separation element provided in the second channel and spatially separating a plurality of second channel components of the second portion; A second channel optical element provided to focus the plurality of second channel components; A second multi-core fiber having a plurality of cores each corresponding to one of the plurality of second channel components, the second multi-core fiber having a light receiving end provided on a focal plane of the second channel optical element, the measuring device comprising the second multi-core fiber.

2. The measuring device according to claim 1, wherein the optical characteristic is polarization.

3. The measuring device according to claim 1, wherein the optical characteristic is color.

4. The measuring device according to claim 1, wherein the first channel components and the second channel components have diffraction orders.

5. The measuring device according to claim 1, wherein the beam splitting element comprises a polarization beam splitter configured to receive the measurement radiation, propagate a first portion of the received radiation having a first polarization through the first channel, and propagate a second portion of the received radiation having a second polarization through the second channel.

6. The measuring device according to claim 1, wherein the first channel separation element comprises a first segmented optical wedge, and the second channel separation element comprises a second segmented optical wedge.

7. The measuring device according to claim 6, wherein the first segmented optical wedge and the second segmented optical wedge are transmissive.

8. The measuring device according to claim 6, wherein the first segmented optical wedge and the second segmented optical wedge are reflective.

9. The measurement device according to claim 1, wherein the first channel separation element includes a first segmented lens, and the second channel separation element includes a second segmented lens.

10. The measurement device according to claim 1, wherein the first channel separation element includes a first diffraction grating, and the second channel separation element includes a second diffraction grating.

11. The measurement device according to claim 1, wherein the first multi-core fiber includes one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core, and the second multi-core fiber includes one of a multi-mode fiber core, a single-mode fiber core, and a combination of a multi-mode fiber core and a single-mode fiber core.

12. The measurement device according to claim 1, wherein at least one of the first channel separation element and the second channel separation element is configurable.

13. The measurement device according to claim 1, wherein at least one of the first multi-core fiber and the second multi-core fiber is configurable in terms of at least one of the position and orientation of the light receiving end.

14. A spatial separation element configured to receive measurement radiation that has interacted with a mark and spatially separate components of the measurement radiation; A beam separation element configured to receive the spatially separated measurement radiation, propagate a first portion of the spatially separated measurement radiation through a first channel, and propagate a second portion having optical characteristics different from those of the first portion of the spatially separated measurement radiation through a second channel; A first channel optical element configured to collect the first portion; A first multi-core fiber having a plurality of cores provided on a focal plane of the first channel optical element and corresponding to components in the first channel; A second channel optical element configured to collect the second portion; A measurement device comprising: a second multi-core fiber having a plurality of cores provided on a focal plane of the second channel optical element and corresponding to components in the second channel.

15. The measurement device according to claim 14, wherein the beam separation element comprises a polarization beam splitter provided to receive the spatially separated measurement radiation and to propagate a first portion of the measurement radiation having a first polarization to the first channel and a second portion of the measurement radiation having a second polarization to the second channel.

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