Multi-field scanning overlay measurement

Abstract

The metrology tool may include an illumination subsystem for illuminating the sample in two or more acquisition fields with two or more illumination beams, the two or more acquisition fields being distributed along the scan direction in a non-overlapping configuration, and a translation stage for sequentially translating a metrology object on the sample along the scan direction through the two or more acquisition fields. The metrology tool may further include an imaging subsystem for imaging the two or more acquisition fields while the sample is scanned along the scan direction. The imaging subsystem may include a field relocation optical relay for relaying images of the two or more acquisition fields to a scanning detector including one or more rows of pixels distributed along a column direction, the field relocation optical relay positioning the images of the two or more acquisition fields on the scanning detector along the column direction.

Description

[Technical field]

[0001] The present disclosure relates generally to scanning metrology, and more particularly to providing multiple optical configurations in a single metrology scan. [Background technology]

[0002] Scanning metrology systems offer a promising approach to interrogate a sample as it moves and achieve high throughput measurements to meet increasing demands on the number and / or sensitivity of metrology measurements. However, scanning metrology introduces additional challenges when a particular location on the sample (e.g., a location of measurement interest) needs to be measured multiple times with different measurement parameters. For example, performing multiple scans of the sample with different illumination or collection configurations may provide a desired data set, but the time required for multiple scans may offset the throughput capabilities of scanning metrology. As another example, splitting the collected light into multiple paths based on a particular optical parameter of the collected light, such as wavelength or polarization, may provide the ability to generate measurements using different collection conditions, but this approach does not have the ability to change the illumination parameters during the scan and uses the illumination light inefficiently, resulting in increased measurement noise. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] US Patent Application Publication No. 2003 / 0179369 [Patent Document 2] US Patent Application Publication No. 2019 / 0331903 [Patent Document 3] U.S. Patent No. 6,211,955 [Patent Document 4] US Patent Application Publication No. 2017 / 0058343 [Patent Document 5] U.S. Patent No. 8,760,662 Summary of the Invention [Problem to be solved by the invention]

[0004] It would therefore be desirable to provide a system and method that addresses the above-mentioned shortcomings. [Means for solving the problem]

[0005] A metrology tool is disclosed according to one or more exemplary embodiments of the present disclosure. In one exemplary embodiment, the metrology tool includes an illumination subsystem for illuminating a sample in two or more acquisition fields with two or more illumination beams, the two or more acquisition fields being distributed along a scan direction in a non-overlapping configuration, and a translation stage sequentially translates a measurement object on the sample through the two or more acquisition fields along the scan direction. In another exemplary embodiment, the metrology tool includes an imaging subsystem for imaging the two or more acquisition fields while the sample is scanned along the scan direction by the translation stage. In another exemplary embodiment, the imaging subsystem includes an objective lens for capturing light from the sample within a measurement field of view, the two or more acquisition fields being within the measurement field of view. In another exemplary embodiment, the imaging subsystem includes a scanning detector including one or more pixel columns distributed along a column direction to generate two or more images of the two or more acquisition fields as the sample is scanned. In another exemplary embodiment, the imaging subsystem includes a field relocation optical relay for relaying images of the two or more acquisition fields to the scanning detector, the field relocation optical relay positions the images of the two or more acquisition fields along the column direction on the scanning detector such that the scan direction in the two or more acquisition fields is perpendicular to the column direction.

[0006] A metrology tool is disclosed according to one or more exemplary embodiments of the present disclosure. In one exemplary embodiment, the metrology tool includes one or more illumination sources. In another exemplary embodiment, the metrology tool includes a translation stage for translating the sample along a scan direction. In another exemplary embodiment, the metrology tool includes an illumination subsystem for illuminating the sample in two or more acquisition fields with two or more illumination beams from the one or more illumination sources, the two or more acquisition fields being distributed along the scan direction in a non-overlapping configuration, and the translation stage sequentially translates a measurement object on the sample through the two or more acquisition fields along the scan direction. In another exemplary embodiment, the metrology tool includes an imaging subsystem for imaging the two or more acquisition fields while the sample is scanned along the scan direction by the translation stage. In another exemplary embodiment, the imaging subsystem includes an objective lens for capturing light from the sample within a measurement field of view, the two or more acquisition fields being within the measurement field of view. In another exemplary embodiment, the imaging subsystem includes a scanning detector including one or more pixel columns distributed along a column direction to generate two or more images of the two or more acquisition fields as the sample is scanned. In another exemplary embodiment, the imaging subsystem includes a field relocation optical relay for relaying images of the two or more acquisition fields to the scanning detector, the field relocation optical relay positioning the images of the two or more acquisition fields along the row direction on the scanning detector such that a scan direction in the two or more acquisition fields is orthogonal to the row direction. In another exemplary embodiment, the metrology tool includes a controller communicatively coupled to the imaging subsystem. In another exemplary embodiment, the controller receives two or more images of the sample associated with the two or more acquisition fields. In another exemplary embodiment, the controller generates metrology measurements associated with the sample based on the two or more images.

[0007] A metrology method is disclosed according to one or more exemplary embodiments of the present disclosure. In one exemplary embodiment, the method includes illuminating a sample in two or more acquisition fields with two or more illumination beams in a measurement field of view of the objective, the two or more acquisition fields being distributed along a scan direction in a non-overlapping configuration. In another exemplary embodiment, the method includes sequentially translating the sample through the two or more acquisition fields along the scan direction. In another exemplary embodiment, the method includes relaying images of the two or more acquisition fields through the objective to a scanning detector using a field relocation optical relay, the field relocation optical relay positions the images of the two or more acquisition fields on the scanning detector along the row direction such that the scan direction in the two or more acquisition fields is orthogonal to the row direction. In another exemplary embodiment, the method includes generating two or more images of the sample associated with the two or more acquisition fields. In another exemplary embodiment, the method includes generating metrology measurements associated with the sample based on the two or more images.

[0008] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not necessarily restrictive of the invention as claimed. The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the general description, serve to explain the principles of the invention.

[0009] Many advantages of the present disclosure may be better understood by those skilled in the art by reference to the following drawings. [Brief description of the drawings]

[0010] [Figure 1A] FIG. 1A is a block diagram of a scanning metrology system in accordance with one or more embodiments of the present disclosure. [Figure 1B] FIG. 1B is a conceptual diagram of an imaging metrology tool showing a single illumination channel illuminating a single acquisition field in accordance with one or more embodiments of the present disclosure. [Figure 1C]FIG. 1C is a conceptual diagram of an imaging metrology tool with six illumination channels providing out-of-lens (OTL) dipole illumination for three acquisition fields in accordance with one or more embodiments of the present disclosure. [Figure 2A] FIG. 2A is a sample top view showing the placement of acquisition fields, in accordance with one or more embodiments of the present disclosure. [Figure 2B] FIG. 2B is a top view of the plane of a scanning detector where the acquisition field has been repositioned by a field repositioning optical relay in accordance with one or more embodiments of the present disclosure. [Figure 2C] FIG. 2C is a top view of a face of a scanning detector with a bi-directional scanning sensor in which the acquisition field has been repositioned by a field repositioning optical relay in accordance with one or more embodiments of the present disclosure. [Figure 3A] FIG. 3A is a perspective view of a field reconfiguration optical relay in accordance with one or more embodiments of the present disclosure. [Figure 3B] FIG. 3B is a perspective view of a series of k-mirrors for rotating an image of an acquisition field in accordance with one or more embodiments of the present disclosure. [Figure 3C] FIG. 3C is a top view of a field relocation optical relay configured to position the acquisition field on a detector with a bidirectional sensor located at an intermediate field plane, in accordance with one or more embodiments of the present disclosure. [Figure 4] FIG. 4 is a flow diagram illustrating steps performed in a metrology method in accordance with one or more embodiments of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Reference will now be made in detail to the disclosed subject matter, as illustrated in the accompanying drawings. The present disclosure has been particularly shown and described with respect to certain embodiments and certain features thereof. The embodiments described herein are considered to be illustrative and not limiting. It will be readily apparent to those skilled in the art that various changes and modifications in form and detail can be made therein without departing from the spirit and scope of the present disclosure.

[0012] Embodiments of the present disclosure are directed to systems and methods for performing multiple measurements of a measurement object or other sample location using different illumination and / or collection parameters (e.g., measurement recipes) in a single scan with a scanning metrology system. In this regard, high measurement sensitivity may be achieved by combining multiple measurements using different measurement recipes in a single scan to provide high throughput measurements. For purposes of this disclosure, the term metrology object is used to generally describe a portion of a sample that is inspected using a metrology system. In this manner, the term metrology object may include, but is not limited to, a dedicated metrology object (e.g., a portion of a sample with features designed to facilitate metrology) or a portion of a device feature suitable for direct metrology measurement.

[0013] Optical metrology tools are typically configurable according to a recipe that includes a set of parameters for controlling the illumination of the sample and the collection of light from the sample. It is recognized herein that different optical metrology techniques may require different illumination profiles of light on the sample and may further utilize light from different portions of the collection pupil for measurement. For example, the recipe of an optical metrology tool may include illumination parameters such as, but are not limited to, illumination intensity, illumination wavelength, illumination pupil distribution (e.g., distribution of illumination angles and associated intensity of illumination at those angles), polarization of incident illumination, spatial distribution of illumination, or sample height (e.g., object focus). As another example, the recipe of an optical metrology tool may include collection parameters such as, but are not limited to, collection pupil distribution (e.g., desired distribution of angular light from the sample used for measurement and associated filtered intensity at those angles), acquisition field aperture settings for selecting portions of the sample of interest, polarization of collected light, or wavelength filters.

[0014] Additionally, various metrology target designs, measurement techniques, and corresponding metrology tools have been developed, and different techniques may utilize different measurement recipes. For example, in the case of image-based overlay metrology, an image-based overlay metrology tool may illuminate an overlay target (e.g., advanced imaging metrology (AIM) target, box-in-box metrology target, etc.) having non-overlapping resolvable features associated with two or more lithographic exposures on one or more sample layers, and capture an overlay signal including an image of the overlay target based on various imaging techniques, including, but not limited to, bright-field imaging or dark-field imaging, etc. Overlay may thus be determined by measuring the relative positions of the features (e.g., field plane distribution) of the overlay target in the captured image. Additionally, a pupil mask in the collection pupil may be used to selectively block (and pass) specific diffraction orders from periodic structures on the sample. In this manner, the characteristics of the resulting image may be highly tuned to provide highly sensitive metrology measurements using corresponding metrology algorithms. Measurement of moving samples and associated measurement target layouts are generally described in U.S. Patent Application No. 16 / 586,504, filed September 27, 2019, U.S. Patent Application No. 16 / 598,146, filed October 10, 2019, and U.S. Patent Application No. 17 / 140,999, filed January 4, 2021, which are incorporated herein by reference in their entireties. As another example, a scatterometry-based overlay metrology tool may illuminate a grating-on-grating measurement target including periodic structures on two or more sample layers in overlapping regions (e.g., associated with lithography exposures on those layers) and capture an overlay signal including an angular distribution of light emanating from the overlay target associated with diffraction, scattering, and / or reflection of the illumination beam from the grating-on-grating structures. Overlay may then be determined based on one or more images generated based on one or more selected diffraction orders. For example, one or more images of the overlay target may be generated based on a single diffraction order.In this manner, features of the overlay target may not be resolved, but overlay may be determined based on a comparison of the intensity or gray levels of imaged target regions when imaged with symmetrically opposing illumination. Scanning scatterometry overlay is generally described in U.S. Patent Application No. 17 / 140,999, filed January 4, 2021, which is incorporated herein by reference in its entirety.

[0015] It is contemplated herein that the systems and methods disclosed herein may be suitable for any scanning metrology technique, including, but not limited to, imaging techniques in which the features of the measurement object are well resolved, scatterometry techniques in which the features of the measurement object are not well resolved, or any diffraction-based technique in which a measurement signal is generated based on selected diffraction orders produced by the measurement object.

[0016] It is contemplated herein that the sensitivity and / or accuracy of a metrology measurement (e.g., an overlay metrology measurement) may be improved by collecting multiple measurement signals having different measurement recipes (e.g., illumination and / or collection parameters) that may be associated with the same or different measurement techniques (e.g., imaging or scatterometry techniques, etc.). For example, different measurement conditions may provide different measurement accuracy and / or may be more or less sensitive to a particular source of measurement error, such as, but not limited to, asymmetric features, tool-induced shift (TIS) errors, or the degree of error that a measurement of a metrology object accurately characterizes a device feature of interest. Thus, measuring a common portion of a sample, such as a metrology object, under different measurement conditions may facilitate robust and accurate measurements.

[0017] It is further contemplated herein that taking multiple measurements of a particular location of a sample (e.g., a location of measurement interest) may be straightforward if the sample is stationary. In particular, the measurement recipe can be changed sequentially to make sequential measurements before moving the sample. However, taking multiple measurements of a sample with different measurement recipes poses additional challenges.

[0018] In some embodiments, the scanning measurement system defines two or more acquisition fields (or subfields) within the measurement field of view, the acquisition fields being distributed along the scan direction such that the measurement object, or other portion of the sample being measured, passes through each of the acquisition fields sequentially during the scan. The scanning measurement system may further include one or more field relocation relay optics for repositioning and / or rotating the position of the acquisition fields on the scanning sensor such that the two or more acquisition fields are distributed in a line direction perpendicular to the scan direction. For example, the scanning sensor may generate an image of one line of pixels at a time as the sample is translated along the scan direction. Thus, the field relocation relay optics may distribute each acquisition field to a different set of pixels on the scanning sensor (or possibly a different adjacent sensor). As the sample is scanned through the two or more acquisition fields, the measurement object will be sequentially represented on each of the different sets of pixels on the scanning sensor. This configuration may be suitable, but is not limited to, imaging with a time-delay-integration (TDI) sensor, where the motion of the sample is synchronized to the charge transfer between pixel rows along the scan direction, extending the effective exposure time of the resulting image.

[0019] The field relocation relay optics may include any combination of optical elements suitable for transposing and / or rotating acquisition fields distributed along the line direction of the line scan sensor rather than the scan direction. In one embodiment, the field relocation relay optics includes separated or decentered optical elements for individually relaying two or more acquisition fields to an intermediate field plane in a transposed orientation. Additionally, the field relocation relay optics may include image rotation elements such as k-mirrors, Dove prisms, etc., that rotate the acquisition fields to facilitate the generation of sequential images as the sample is scanned along the scan direction.

[0020] It is contemplated herein that this configuration may enable separate measurements of each of the acquisition fields using different measurement recipes (e.g., different illumination and / or collection parameters). In one embodiment, the scanning metrology system provides a separate illumination channel for each (or at least a portion of) the acquisition fields, facilitating independent control of various illumination parameters, such as, but not limited to, wavelength, polarization, angle of incidence (e.g., illumination pupil control), and illumination field (e.g., illumination field control). Additionally, the scanning metrology system may incorporate any combination of out-of-lens (OTL) and through-the-lens (TTL) illumination techniques. For example, OTL illumination and TTL illumination are generally described in U.S. Patent Application No. 16 / 996,328, filed August 18, 2020, and U.S. Patent Application No. 17 / 140,999, filed January 4, 2021, both of which are incorporated herein by reference in their entireties. In another embodiment, the scanning metrology system includes a separate collection channel for each (or at least some) of the acquisition fields to facilitate independent control of various collection parameters, such as, but not limited to, polarization filtering, wavelength filtering, collection pupil control (e.g., to block selected diffraction orders to implement a selected metrology algorithm), collection field control (e.g., to select a collection field of view on the sample), etc. For example, the scanning metrology system may include a field relay to generate intermediate collection field planes and / or intermediate collection pupil planes for each (or at least some) of the collection channels.

[0021] 1A-4, systems and methods for scanning metrology using multiple measurement recipes in accordance with one or more embodiments of the present disclosure will now be described in more detail.

[0022] FIG. 1A is a block diagram of a scanning metrology system 100 in accordance with one or more embodiments of the present disclosure.

[0023] In one embodiment, the scanning metrology system 100 includes an imaging metrology tool 102 that acquires metrology signals from a measurement object or other measurable portion of a sample 104. For example, the imaging metrology tool 102 may include, but is not limited to, an overlay metrology tool for performing overlay measurements.

[0024] In one embodiment, the imaging metrology tool 102 includes an illumination subsystem 106 with two or more illumination channels 108 for illuminating two or more acquisition fields 110 on the sample 104 with illumination in the form of two or more illumination beams 112. Each of the two or more illumination channels 108 may direct the illumination beam 112 to a particular acquisition field 110. Furthermore, each acquisition field 110 may be illuminated simultaneously or sequentially by one or more illumination channels 108. In this manner, various illumination parameters, such as, but not limited to, intensity, wavelength, polarization, or angle of incidence, may be independently adjusted for each illumination channel 108 and acquisition field 110. For example, the one or more illumination beams 112 may be angularly constrained such that periodic structures (e.g., in one or more cells of the measurement object) may generate discrete diffraction orders. Furthermore, the one or more illumination beams 112 may be spatially constrained such that selected portions of the sample 104 within the acquisition field 110 may be illuminated. For example, each of the one or more illumination beams 112 can be spatially restricted to illuminate a particular cell of the measurement object.

[0025] In another embodiment, the imaging metrology tool 102 includes a scanning subsystem 114 for translating the sample 104 relative to the illumination subsystem 106 and the imaging subsystem 116. For example, the scanning subsystem 114 may include one or more actuators or translation stages fixed to the sample 104 and / or to a portion of the imaging subsystem 116 (e.g., the objective lens).

[0026] In another embodiment, the scanning metrology system 100 includes an imaging subsystem 116 for collecting light (e.g., measurement light 118) from two or more acquisition fields 110 and directing the light to a scanning detector 120. For example, the two or more acquisition fields 110 may be distributed within a measurement field of view (e.g., a field of view of an objective lens used to collect the measurement light 118) of the imaging subsystem 116. The imaging subsystem 116 may further include two or more collection channels 122, each of which may be associated with a particular acquisition field 110. Thus, various collection parameters associated with the measurement light 118 from each acquisition field 110, such as, but not limited to, wavelength, polarization, or collection angle, may be independently controlled.

[0027] The scanning detector 120 may include any type of sensor or combination of sensors known in the art suitable for capturing the measurement light 118 as the sample 104 is scanned. In one embodiment, the scanning detector 120 includes a line scan detector including a single row of pixels distributed along the column direction 206 to continuously generate an image of one line of pixels at a time as the sample 104 is scanned along a scan direction 202 orthogonal to the column direction 206. In another embodiment, the scanning detector 120 includes a time delay integration (TDI) detector. The TDI detector may generate a continuous image of the sample 104 when the motion of the sample 104 is synchronized to a charge transfer clock signal in the TDI detector. In particular, the TDI detector includes a clock pulse to acquire charge from exposure in multiple columns of pixels and transfer the charge between adjacent columns of pixels along the scan direction 202. When the motion of the sample 104 along the scan direction 202 is synchronized with the charge transfer in the TDI detector, charge accumulates continuously during the scan. This process continues until the charge reaches the last row of pixels and is then read out of the TDI detector. In this way, an image of the object is accumulated over a longer time frame than would be possible with a simple line scan camera. This relatively long acquisition time reduces the photon noise level in the image. Furthermore, the synchronous movement of the image and the charge can prevent blurring in the recorded image.

[0028] In another embodiment, the scanning detector 120 includes a bidirectional detector in which two successive images are generated based on readout in opposite directions. In this configuration, a single bidirectional detector can generate two successive images simultaneously. For example, a bidirectional TDI detector can have two sets of pixel columns with opposite charge transfer directions. Imaging with bidirectional detectors is generally described in U.S. Patent No. 7,528,943, filed December 27, 2005, and U.S. Patent No. 9,426,400, filed December 10, 2012, both of which are incorporated herein by reference in their entireties.

[0029] 2A is a top view of the sample 104 illustrating the arrangement of the acquisition fields 110 in accordance with one or more embodiments of the present disclosure. In one embodiment, two or more acquisition fields 110 are linearly distributed along the scan direction 202 and are located within a measurement field of view 204 of the imaging subsystem 116 (e.g., the field of view of an objective lens of the imaging subsystem 116). In this configuration, as the sample 104 is scanned, a measurement object (or other desired portion of the sample 104 to be measured) may pass sequentially through the acquisition fields 110. In particular, FIG. 2A illustrates three acquisition fields 110a, b, c within the measurement field of view 204 arranged such that during scanning, a measurement object passes sequentially through acquisition field 110a, acquisition field 110b, and then acquisition field 110c.

[0030] In another embodiment, the scanning metrology system 100 includes a field relocation optical relay 124 for repositioning an image of the acquisition field 110 to facilitate positioning of the acquisition field 110 along the column direction of the scanning detector 120. For example, the field relocation optical relay 124 can relay an acquisition field 110 located at one intermediate field plane in the imaging subsystem 116 to another intermediate field plane, where the field relocation optical relay 124 separately images, repositions, and / or rotates the acquisition field 110 between the two intermediate field planes.

[0031] It is considered herein that simply imaging the measurement field 204 (e.g., as shown in FIG. 2A ) onto the scanning detector 120 may be inadequate for generating separate images of the acquisition field 110, especially with a TDI detector. For example, the scanning detector 120 may include one or more pixel columns, with the pixels in each column distributed along a column direction. In this manner, the scanning detector 120 may generate successive images of the sample 104 as the sample 104 is scanned along a scan direction 202 orthogonal to the column direction. In this configuration, multiple acquisition fields 110 are imaged sequentially when the column direction of the scanning detector 120 is positioned orthogonal to the scan direction to generate successive images of the sample. When a TDI detector is used, this configuration may result in a blending of images of the acquisition field 110.

[0032] In one embodiment, the field relocation optical relay 124 can reposition or otherwise redistribute the acquisition fields 110 along the column direction of the scanning detector 120, and can further rotate the image of the acquisition fields 110 so that the scan direction is orthogonal to the column direction of the scanning detector 120. In another embodiment, the field relocation optical relay 124 can reposition or otherwise redistribute the acquisition fields 110 along the column direction of two or more individual scanning detectors 120, and can further rotate the image of the acquisition fields 110 so that the scan direction is orthogonal to the column direction of each scanning detector 120.

[0033] 2B is a top view of the surface of the scanning detector 120 with the acquisition fields 110 repositioned by the field repositioning optical relay 124, according to one or more embodiments of the present disclosure. As shown in FIG. 2B, the acquisition fields 110a, b, c are distributed along a column direction 206 of the scanning detector 120, and the scan direction 202 in each of the acquisition fields 110 is orthogonal to the column direction 206. As a result, a continuous image generated by the scanning detector 120 may include a separate region for each of the acquisition fields 110. In particular, each acquisition field 110 may be associated with a fixed set of pixels of the scanning detector 120 along the column direction 206. Alternatively, in the case of multiple scanning detectors 120, one or more acquisition fields 110 may be imaged onto separate scanning detectors 120, each of which may provide a separate image.

[0034] 2C is a top view of a face of a scanning detector 120 with a bidirectional scanning sensor in which the acquisition fields 110 have been repositioned by a field repositioning optical relay 124, in accordance with one or more embodiments of the present disclosure. In particular, FIG. 2C illustrates a configuration having two acquisition fields 110 distributed along the scan direction 202, instead of three as shown in FIG. 2A.

[0035] As previously described herein, the bidirectional detector may include two sets of pixel columns 208a,b to generate two consecutive images simultaneously. For example, the bidirectional TDI detector may have opposite charge transfer directions for the two sets of pixel columns 208a,b. In one embodiment, the field relocation optical relay 124 places one acquisition field 110 on the first set of pixel columns 208a and the second acquisition field 110 on the second set of pixel columns 208b. Furthermore, as shown in FIG. 2C, the two acquisition fields 110 may be rotated such that the scanning directions 202 of the two acquisition fields 110 are in opposite directions. In this way, separate images of the two acquisition fields 110 may be generated using a single bidirectional scanning detector 120. For a bidirectional TDI detector, the charge transfer direction 210 may also be aligned with the scanning direction 202 of each acquisition field 110.

[0036] 2C may be suitable for configurations of imaging metrology tool 102 that provide an even number of acquisition fields 110. For example, a field relocation optical relay 124 may relocate (and optionally rotate) pairs of acquisition fields 110 onto multiple bidirectional detectors.

[0037] Now referring to Figures 1B-3B, various configurations of scanning metrology system 100 that sequentially provide multiple measurements of a measurement object or other portion of a sample in the acquisition field 110 using different measurement recipes are described in more detail in accordance with one or more embodiments of the present disclosure.

[0038] FIG 1B is a conceptual diagram of an imaging metrology tool 102 showing a single illumination channel 108 illuminating a single acquisition field 110, in accordance with one or more embodiments of the present disclosure. As such, FIG 1B illustrates various components of a scanning metrology system 100 that may be included in any particular illumination channel 108 or collection channel 122. FIG 1B and FIG 1C generally illustrate various configurations of the illumination subsystem 106 and imaging subsystem 116. FIG 3A and FIG 3B illustrate the operation of a field relocation optical relay 124.

[0039] In one embodiment, the imaging metrology tool 102 includes at least one illumination source 126 configured to generate one or more illumination beams 112. The illumination beam 112 from the illumination source 126 may include one or more selected wavelengths of light, including but not limited to ultraviolet (UV) radiation, visible radiation, or infrared (IR) radiation. Furthermore, the illumination beam 112 from the illumination source 126 may have any temporal profile, including but not limited to a continuous wave (CW) profile, a pulsed profile, or a modulated profile.

[0040] The illumination source 126 may generally include any type of illumination source suitable for providing at least one illumination beam 112. In one embodiment, the illumination source 126 is a laser source. For example, the illumination source 126 may include, but is not limited to, one or more narrowband laser sources, broadband laser sources, supercontinuum laser sources, white light laser sources, and the like. In this regard, the illumination source 126 may provide an illumination beam 112 having high coherence (e.g., high spatial coherence and / or temporal coherence). In another embodiment, the illumination source 126 includes a laser sustained plasma (LSP) source. For example, the illumination source 126 may include, but is not limited to, an LSP lamp, an LSP bulb, or an LSP chamber suitable for housing one or more elements that may emit broadband illumination when excited into a plasma state by a laser source. In another embodiment, the illumination source 126 includes a lamp source. For example, the illumination source 126 may include, but is not limited to, an arc lamp, a discharge lamp, an electrodeless lamp, and the like. In this regard, the illumination source 126 may provide an illumination beam 112 having low coherence (eg, low spatial coherence and / or temporal coherence).

[0041] The illumination subsystem 106 may include any number of illumination beams 112. In this manner, a particular illumination source 126 may provide illumination for a single illumination channel 108 (e.g., as shown in FIG. 1B ) or for multiple illumination channels 108 (e.g., using one or more beam splitters, etc.).

[0042] Illumination channel 108 may include one or more optical components suitable for modifying and / or conditioning illumination beam 112 and directing illumination beam 112 to sample 104. In one embodiment, illumination channel 108 includes one or more illumination channel lenses 128 (e.g., for collimating illumination beam 112, relaying pupil and / or field planes, etc.). In another embodiment, illumination channel 108 includes one or more illumination channel optics 130 for shaping or otherwise controlling illumination beam 112. For example, illumination channel optics 130 may include, but are not limited to, one or more illumination field apertures, one or more illumination pupil apertures, one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, one or more beam shapers, or one or more mirrors (e.g., stationary mirrors, translating mirrors, scanning mirrors, etc.). Further, the illumination channel optics 130 may be located at any suitable location in the illumination channel 108, such as, without limitation, at the illumination pupil plane 132 or the illumination field plane 134. For example, the imaging metrology tool 102 may include one or more relay optics (e.g., including one or more illumination channel lenses 128) to provide the illumination pupil plane 132 and / or the illumination field plane 134.

[0043] In another embodiment, the imaging subsystem 116 includes an objective lens 136 for collecting measurement light 118 from the acquisition field 110 and directing the measurement light 118 to a scanning detector 120 positioned in an acquisition field plane 138 to generate an image of the sample 104.

[0044] In another embodiment, the field relocation optical relay 124 is disposed in the imaging subsystem 116 to reposition the acquisition field 110 (e.g., as shown in FIGS. 2A-2C). For example, the field relocation optical relay 124 may relay an image of the acquisition field 110 between two acquisition field planes 138. Additionally, as shown in FIG. 1B, the scanning detector 120 may be disposed in one of the acquisition field planes 138.

[0045] In another embodiment, imaging subsystem 116 includes two or more collection channels 122 to provide independent control of various optical parameters of measurement light 118 from any of acquisition fields 110. For example, collection channel 122 may include one or more optical elements suitable for modifying and / or conditioning measurement light 118 from acquisition field 110. In one embodiment, collection channel 122 may include one or more collection channel lenses 140, which may include, but are not required to include objective lens 136 (e.g., to collimate measurement light 118, relay pupil plane and / or field plane, etc.). In another embodiment, collection channel 122 includes one or more collection channel optics 142 for shaping or otherwise controlling illumination beam 112. For example, the collection channel optics 142 may include, but are not limited to, one or more field stops, one or more pupil stops, one or more polarizers, one or more filters, one or more beam splitters, one or more diffusers, one or more homogenizers, one or more apodizers, one or more beam shapers, or one or more mirrors (e.g., stationary mirrors, translating mirrors, scanning mirrors, etc.). Furthermore, the collection channel optics 142 may be located in any suitable location, such as, but not limited to, the collection pupil plane 144 or the acquisition field plane 138. For example, the imaging metrology tool 102 may include one or more relay optics (e.g., including one or more collection channel lenses 140) to provide the collection pupil plane 144 and / or the acquisition field plane 138. In addition, it is contemplated herein that various components of the collection channel 122, such as the collection channel optics 142, the collection channel lenses 140, etc., may be located before or after the field relocation optical relay 124.

[0046] 1B and 1C, various configurations of the imaging metrology tool 102 for illuminating the acquisition field 110, in accordance with one or more embodiments of the present disclosure, will now be described in greater detail.

[0047] As previously described herein, the imaging metrology tool 102 may illuminate any particular acquisition field 110 with any number of illumination beams 112 from any number of illumination channels 108. Additionally, the acquisition field 110 may be illuminated simultaneously or sequentially with multiple illumination beams 112. For example, the imaging metrology tool 102 may illuminate the acquisition field 110 simultaneously or sequentially with normal illumination, monopole oblique illumination, dipole illumination, quadrupole illumination, or any other desired illumination profile.

[0048] Additionally, the two or more acquisition fields 110 may be illuminated with different illumination conditions (e.g., associated with different measurement recipes), such as, but not limited to, intensity, wavelength, polarization, or angle of incidence. In this manner, the measurement object or other portion of the sample 104 being measured may be illuminated with multiple illumination conditions in a single scan to facilitate one or more metrology measurements in a single scan.

[0049] In one embodiment, as shown in FIG. 1B, one or more illumination channels 108 direct the illumination beam 112 through the objective lens 136 to provide through-the-lens (TTL) illumination. In this configuration, the imaging metrology tool 102 may include a beam splitter 146 to combine beam paths for the imaging subsystem 116 and at least one illumination channel 108. Additionally, although not shown, multiple illumination channels 108 may provide TTL illumination. For example, light from multiple illumination channels 108 may be directed to different positions and / or angles via the beam splitter 146. As another example, a field mask may be positioned in the illumination field plane 134 to provide multiple illumination beams 112 that are directed to multiple acquisition fields 110.

[0050] In another embodiment, as shown in FIG. 1C, one or more illumination channels 108 may direct an illumination beam 112 into the acquisition field 110 at an angle of incidence outside the numerical aperture (NA) of the objective lens 136 to provide out-of-lens (OTL) illumination.

[0051] FIG. 1C is a conceptual diagram of an imaging metrology tool 102 with six illumination channels 108 providing OTL dipole illumination for three acquisition fields 110, in accordance with one or more embodiments of the present disclosure. In FIG. 1C, light from each of the illumination channels 108 is provided by a separate optical fiber. Additionally, in FIG. 1C, the illumination subsystem 106 includes two illumination heads 148 providing dipole illumination for each of the acquisition fields 110. In this manner, the illumination heads may provide a common set of optical elements, such as, but not limited to, lenses, mirrors, prisms, filters, etc., for directing illumination beams 112 from the multiple illumination channels 108 to the sample 104. For example, the illumination heads 148 in FIG. 1C each include a prism 150 and a set of focusing lenses 152 for directing illumination beams 112 from the three illumination channels 108 to the three acquisition fields 110 along a common direction (here with an azimuthal incidence angle along the X direction). Similarly, although not shown, the imaging metrology tool 102 may include an additional illumination head 148 that provides illumination of the acquisition field 110 along an additional direction, such as, but not limited to, an azimuthal incidence angle along the Y direction, to provide quadrupole illumination.

[0052] 1B-1C and the associated description are provided for illustrative purposes only and should not be construed as limiting. Rather, the imaging metrology tool 102 may include any number of illumination channels 108 to illuminate any number of acquisition fields 110 within the measurement field of view 204. Additionally, the imaging metrology tool 102 may include, without limitation, one or more illumination heads 148, as shown in FIG. 1C , that direct any number of illumination beams 112 to the sample 104 using common optical elements. Alternatively or additionally, the imaging metrology tool 102 may utilize separate optical elements to direct one or more illumination beams 112 to the sample 104.

[0053] Now referring to Figures 3A-3C, various configurations of the field repositioning optical relay 124 and scanning detector 120 for imaging the acquisition field 110, in accordance with one or more embodiments of the present disclosure, are described in more detail.

[0054] 3A is a perspective view of a field relocation optical relay 124 in accordance with one or more embodiments of the present disclosure. In one embodiment, the field relocation optical relay 124 includes multiple off-center relay optics 302 for individually relaying images of the acquisition fields 110 from one acquisition field plane 138 to another acquisition field plane 138, arranging the images of the acquisition fields 110 along the column direction 206, and / or rotating the acquisition fields 110 such that the scan direction 202 in each of the acquisition fields 110 is orthogonal to the column direction 206 (e.g., as shown in FIG. 2B ).

[0055] The decentered relay optics 302 may include any type of optical element or combination of optical elements known in the art suitable for independently imaging, positioning, and / or rotating the acquisition field 110. In one embodiment, the decentered relay optics 302 is formed as a segmented optical element 304 having a different surface profile at each segment 306, as shown in FIG. 3A. In another embodiment, the decentered relay optics 302 is formed from individual optical elements. In another embodiment, the decentered relay optics 302 is formed from a lens array, where various lenses in the lens array are adjusted to provide the desired repositioning of the acquisition field 110, as shown in FIG. 2B and / or FIG. 2C. Furthermore, the profiles of the various segments or lens elements may have any spherical or aspherical profile to provide the desired repositioning of the acquisition field 110. For example, the decentered relay optics 302 may include spherical elements oriented in different directions. In another example, the decentered relay optics 302 may include one or more aspherical elements. As an example, FIG. 3A shows a pair of segmented optical elements 304, each having three segments 306 with individually tailored surface profiles for individually imaging, positioning, and rotating the image of the acquisition field 110.

[0056] In some embodiments, the field relocation optical relay 124 includes separate elements for rotating the images of the acquisition fields 110. For example, the field relocation optical relay 124 may separately rotate the images of the acquisition fields 110 using separate beam rotating elements such as, but not limited to, k-mirrors or Dove prisms. In this configuration, the decentered relay optics 302 may adjust the relative positions of the acquisition fields 110 but are not required to rotate them.

[0057] 3B is a perspective view of a series of k-mirrors 308 for rotating the image of the acquisition field 110, in accordance with one or more embodiments of the present disclosure. In particular, FIG. 3B shows a first set of k-mirrors 308a for rotating the image of the acquisition field 110a, a second set of k-mirrors 308a for rotating the image of the acquisition field 110b, and a third set of k-mirrors 308c for rotating the image of the acquisition field 110c. Additionally, the k-mirrors 308 in FIG. 3B are oriented to rotate each of the acquisition fields 110 by 90 degrees, such that the scan direction 202 is orthogonal to the row direction 206, as shown in FIG. 2B and FIG. 3A. The k-mirrors 308 provide twice the optical rotation as the physical rotation, so that the k-mirrors 308a, b, c are each oriented at 45 degrees to provide an optical rotation of 90 degrees.

[0058] 3C is a top view of a field relocation optical relay 124 arranged to position the acquisition field 110 on a detector 120 with a bidirectional sensor arranged at an intermediate field plane 206, according to one or more embodiments of the present disclosure. In one embodiment, the decentered relay optics 302 includes a beam splitter 310 for splitting the two acquisition fields 110 along two separate paths, one providing an odd number of reflections (e.g., folds) and the other providing an even number of reflections (e.g., folds). In this way, the scanning directions of the two acquisition fields 110 can be arranged to point in opposite directions at the intermediate field plane 206 for readout by the bidirectional sensor. For example, FIG. 3C illustrates a configuration in which the field relocation optical relay 124 includes a first path 312 with a mirror providing a single reflective surface 314 (e.g., odd number of reflections) and a second path 316 with a prism having two reflective surfaces 318 providing two reflections (e.g., even number of reflections). Additionally, the reflective surfaces in each of the paths of the field relocation optical relay 124 may be any type of reflective surface known in the art, including, but not limited to, mirror or prism surfaces. In another embodiment, the field relocation optical relay 124 includes one or more relay lenses 320 (or reflective optics) for relaying the acquisition field 110 to the intermediate field plane 206. For example, FIG. 3C illustrates a configuration in which one or more relay lenses include a telecentric lens.

[0059] As shown herein with reference to FIGS. 1A-3B, it is contemplated herein that the imaging metrology tool 102 may generate multiple images of a measurement object or other portion of a sample 104 during a single scan as it passes through multiple acquisition fields 110 distributed along a scan direction 202 in a measurement field of view 204. Furthermore, a measurement recipe (e.g., various illumination and / or collection parameters) may be controlled independently for each of the acquisition fields 110. These multiple images may then be used to generate metrology data, such as, but not limited to, overlay data. It is further contemplated herein that in some applications it may be beneficial to perform multiple scans of a particular measurement object or other portion of a sample to generate additional images using additional metrology recipes. However, even in such cases, the imaging metrology tool 102 may provide a high throughput measurement compared to a tool that generates a single image of the object per scan.

[0060] The following description provides various examples of the imaging metrology tool 102 used in the context of overlay metrology to more fully illustrate various advantages of the imaging metrology tool 102. However, it should be understood that the imaging metrology tool 102 disclosed herein is not limited to overlay metrology, and the following examples are provided for illustrative purposes only and should not be construed as limiting.

[0061] In one embodiment, the imaging metrology tool 102 illuminates the sample 104 with different combinations of illumination beams 112 at different angles of incidence in multiple acquisition fields 110. In one embodiment, the imaging metrology tool 102 illuminates the sample 104 in one acquisition field 110 with normal illumination of the illumination beam 112, which may be suitable for overlay measurements along any direction, but is not limited to this. In another embodiment, the imaging metrology tool 102 illuminates the sample 104 with two illumination beams 112 arranged as a dipole at opposite azimuth angles (e.g., as shown in FIG. 1C), which may be useful for overlay measurements along the dipole direction. For example, the imaging metrology tool 102 may illuminate the sample 104 with two opposing illumination beams 112 simultaneously in a single acquisition field 110 or sequentially in different acquisition fields 110. In another embodiment, the imaging metrology tool 102 illuminates the sample 104 with four illumination beams 112 arranged as a quadrupole (e.g., two dipoles oriented in orthogonal dipole directions), which may be suitable for overlay measurements along two orthogonal directions. For example, the imaging metrology tool 102 may illuminate the sample 104 with four illumination beams 112 simultaneously in a single acquisition field 110. As another example, the imaging metrology tool 102 may sequentially illuminate the sample 104 with four illumination beams 112 in four acquisition fields 110. As a further example, the imaging metrology tool 102 may illuminate the sample 104 with two illumination beams 112 (e.g., one along each dipole direction) in a first acquisition field 110 and then with the remaining two illumination beams 112 in a second acquisition field 110.

[0062] In one embodiment, the imaging metrology tool 102 illuminates the sample 104 with different wavelengths of light in different acquisition fields 110. For example, if the imaging metrology tool 102 and / or the algorithms used to generate the measurements are sensitive to wavelength, metrology measurements generated based on a combination of images generated at different wavelengths may be more accurate than a single image at a single wavelength.

[0063] In another embodiment, the imaging metrology tool 102 generates images at different focal planes in different acquisition fields 110. For example, the different focal planes may correspond to depths of overlaid features of interest on different sample layers. In this manner, high quality, in-focus images of different features on different sample layers may be generated.

[0064] In some embodiments, one or more of the illumination channels 108 and / or one or more of the collection channels 122 can be adjusted during run-time to facilitate selectable control of a measurement recipe associated with one or more of the acquisition fields 110. In this regard, the imaging metrology tool 102 can be dynamically configured to provide a variety of measurements. In one embodiment, a measurement recipe for an acquisition field 110 can be configured prior to measurement of a particular metrology object or other portion of the sample 104 being measured. In another embodiment, the imaging metrology tool 102 can rapidly switch between two or more measurement recipes for the acquisition field 110 to generate an interleaved image of the acquisition field 110, where separate images of the sample 104 associated with the acquisition field 110 based on different measurement recipes can be extracted from the interleaved image. Generation of interleaved images associated with multiple metrology recipes is generally described in U.S. patent application Ser. No. 16 / 586,504, filed Sep. 27, 2019, which is incorporated herein by reference in its entirety. In one embodiment, the imaging metrology tool 102 rapidly switches between N metrology recipes and further directs image light to every Nth pixel column of the TDI sensor (e.g., using a lens array and / or a mask on the remaining pixel columns). In this way, every Nth pixel row of the resulting interleaved image can be based on a common measurement recipe, and separate images can be extracted from each measurement recipe.

[0065] Referring again now to FIG. 1A, additional components of the scanning metrology system 100, in accordance with one or more embodiments of the present disclosure, will now be described in greater detail.

[0066] In another embodiment, the scanning metrology system 100 includes a controller 154 communicatively coupled to the imaging metrology tool 102 and / or any components therein.

[0067] In another embodiment, the controller 154 includes one or more processors 156. For example, the one or more processors 156 may be configured to execute a set of program instructions held in the memory device 158 or memory. The one or more processors 156 of the controller 154 may include any processing element known in the art. In this sense, the one or more processors 156 may include any microprocessor-type device configured to execute algorithms and / or instructions.

[0068] The one or more processors 156 of the controller 154 may include any processor or processing element known in the art. For purposes of this disclosure, the term "processor" or "processing element" may be broadly defined to encompass any device having one or more processing or logic elements (e.g., one or more microprocessor devices, one or more application specific integrated circuit (ASIC) devices, one or more field programmable gate arrays (FPGAs), or one or more digital signal processors (DSPs)). In this sense, the one or more processors 156 may include any device configured to execute algorithms and / or instructions (e.g., program instructions stored in a memory). In one embodiment, the one or more processors 156 may be embodied as a desktop computer, a mainframe computer system, a workstation, an image computer, a parallel processor, a network computer, or any other computer system configured to execute programs configured to operate in conjunction with the scanning metrology system 100, as described throughout this disclosure, or configured to operate in conjunction with the scanning metrology system 100. Furthermore, different subsystems of the scanning metrology system 100 may include processors or logic elements suitable for performing at least some of the steps described in the present disclosure. Thus, the above description should not be construed as limiting the embodiments of the present disclosure, but merely as examples. Furthermore, the steps described throughout the present disclosure may be performed by a single controller or by multiple controllers. In addition, the controller 154 may include one or more controllers housed in a common housing or in multiple housings. In this manner, any controller or combination of controllers may be packaged separately as a module suitable for integration into the scanning metrology system 100.

[0069] The memory device 158 may include any storage medium known in the art suitable for storing program instructions executable by the associated one or more processors 156. For example, the memory device 158 may include a non-transitory memory medium. As another example, the memory device 158 may include, but is not limited to, a read-only memory (ROM), a random access memory (RAM), a magnetic or optical memory device (e.g., disk), a magnetic tape, a solid-state drive, and the like. It is further noted that the memory device 158 may be housed in a common controller housing with the one or more processors 156. In one embodiment, the memory device 158 may be located remotely with respect to the physical location of the one or more processors 156 and the controller 154. For example, the one or more processors 156 of the controller 154 may access a remote memory (e.g., a server) accessible via a network (e.g., the Internet, an intranet, etc.).

[0070] In this manner, the controller 154 may direct (e.g., via control signals) or receive data from the imaging metrology tool 102 or any components therein. The controller 154 may be further configured to perform any of the various process steps described throughout this disclosure, such as, but not limited to, directing any of the illumination channels 108 and / or collection channels 122 to generate one or more images based on one or more selected recipes, receiving images from the scanning detector 120, or generating metrology data based on the received images.

[0071] In one embodiment, the scanning metrology system 100 includes a user interface 160 communicatively coupled to the controller 154. In one embodiment, the user interface 160 may include, but is not limited to, one or more desktops, laptops, tablets, etc. In another embodiment, the user interface 160 includes a display used to display data of the scanning metrology system 100 to a user. The display of the user interface 160 may include any display known in the art. For example, the display may include, but is not limited to, a liquid crystal display (LCD), an organic light emitting diode (OLED)-based display, or a CRT display. Those skilled in the art should recognize that any display device that can be integrated with the user interface 160 is suitable for implementation in the present disclosure. In another embodiment, a user may input selections and / or instructions in response to data displayed to the user via a user input device of the user interface 160.

[0072] 4, a flow diagram illustrating steps performed in a metrology method 400 is described in accordance with one or more embodiments of the present disclosure. Applicant notes that the embodiments and enabling techniques described herein above in the context of the scanning metrology system 100 should be construed to extend to the method 400 as well. However, it is further noted that the method 400 is not limited to the architecture of the scanning metrology system 100.

[0073] In one embodiment, the method 400 includes illuminating 402 a sample in two or more acquisition fields with two or more illumination beams in a measurement field of view of the objective (or, more generally, an imaging system). In another embodiment, the method 400 includes sequentially translating 404 the sample through the two or more acquisition fields along a scan direction. In another embodiment, the method 400 includes relaying 406 images of the two or more acquisition fields through the objective to a scanning detector using a field relocation optical relay, which positions the images of the two or more acquisition fields along the row direction on the scanning detector such that the scan direction in the two or more acquisition fields is orthogonal to the row direction. In another embodiment, the method 400 includes generating 408 two or more images of the sample associated with the two or more acquisition fields.

[0074] In this manner, two or more images of a metrology object, or any other portion of a sample being measured, may be generated at two or more acquisition fields according to two or more different measurement recipes in a single scan. A measurement recipe may include any combination of illumination or collection conditions associated with the acquisition fields, such as, but not limited to, illumination intensity, illumination wavelength, illumination polarization, illumination angle, imaging depth of field, collection angle, wavelength of collected light, polarization of collected light, etc.

[0075] In another embodiment, the method 400 includes generating 410 metrology measurements associated with the sample based on the two or more images. For example, step 410 may include generating overlay measurements associated with relative displacements of features produced by two or more lithography steps in one or more layers of the sample.

[0076] As an illustrative example, sequential images of an overlay measurement object may be generated with opposing dipole illumination beams along one or more azimuthal directions in a single scan by illuminating the overlay object with a first dipole illumination beam in a first acquisition field and illuminating the overlay object with an opposing illumination beam in a second acquisition field. Thus, an overlay measurement may be generated based on two images of the measurement object in the two acquisition fields. However, it should be understood that this example is provided merely for illustrative purposes and should not be construed as limiting. Rather, any combination of images suitable for one or more metrology algorithms may be generated in a single scan by utilizing a selected measurement recipe in each of two or more acquisition fields.

[0077] For purposes of this disclosure, the term overlay is generally used to describe the relative position of features on a sample fabricated by two or more lithographic patterning steps, and the term overlay error describes the deviation of a feature from a nominal position. For example, a multi-layer device may include features patterned on multiple sample layers, using a different lithographic step for each layer, and typically requires tight control of the alignment of features between layers to ensure proper performance of the resulting device. Thus, overlay measurements may characterize the relative position of features on two or more sample layers. As another example, multiple lithographic steps may be used to fabricate features on a single sample layer. Such techniques are commonly referred to as double or multi-patterning techniques and may facilitate the fabrication of high density features, approaching the resolution of lithographic systems. Overlay measurements in this context may characterize the relative position of features from different lithographic steps on this single layer. It should be understood that examples and figures throughout this disclosure of specific applications of overlay metrology are provided for illustrative purposes only and should not be construed as limiting the disclosure.

[0078] While in some applications overlay measurements may be performed directly on the fabricated device features (e.g., device features), overlay measurements are typically performed on dedicated overlay targets printed using the same lithography step as the device features. In this manner, the overlay target features (e.g., target features) may be specifically designed to facilitate overlay measurements. Furthermore, overlay measured in one fabrication step (e.g., after fabrication of one or more sample layers) may be used to generate correctives for precisely aligning process tools (e.g., lithography tools, etc.) for fabricating additional sample layers in subsequent fabrication steps.

[0079] However, it should be understood that the systems and methods disclosed herein are not limited to overlay metrology, but rather may be applicable to various optical metrology measurements, such as, but not limited to, process metrology measurements. For example, process metrology may be related to measuring exposure fluence and / or dose of illumination during a lithography step. In this regard, reference to overlay metrology is for illustrative purposes and not limiting.

[0080] As used throughout this disclosure, the term "sample" generally refers to a substrate (e.g., a wafer, etc.) formed of a semiconductor or non-semiconductor material. For example, the semiconductor or non-semiconductor material may include, but is not limited to, monocrystalline silicon, gallium arsenide, and indium phosphide. The sample may include one or more layers. For example, such layers may include, but are not limited to, resist, dielectric material, conductive material, and semiconductor material. Many different types of such layers are known in the art, and the term sample as used herein is intended to encompass samples on which all types of such layers may be formed. The one or more layers formed on the sample may be patterned or unpatterned. For example, the sample may include multiple dies, each having repeatable patterned features. The formation and processing of such material layers may ultimately result in a device. Many different types of devices may be formed on the sample, and the term sample as used herein is intended to encompass samples on which any type of device known in the art is fabricated. Furthermore, for purposes of this disclosure, the terms sample and wafer should be construed as interchangeable. Additionally, for the purposes of this disclosure, the terms patterning device, mask, and reticle should be considered interchangeable.

[0081] The subject matter described herein may depict different components contained within or connected to other components. It should be understood that such illustrated architectures are merely exemplary, and that in fact many other architectures that achieve the same functionality may be implemented. In a conceptual sense, any arrangement of components to achieve the same functionality is effectively "associated" such that the desired functionality is realized. Thus, any two components that are combined herein to achieve a particular functionality may be considered to be "associated" with one another such that the desired functionality is achieved, regardless of the architecture or intermediate components. Similarly, any two components so associated may also be considered to be "connected" or "coupled" with one another to achieve the desired functionality, and any two components that may be so associated may also be considered to be "couplable" with one another to achieve the desired functionality. Specific examples of components that may be coupled include, but are not limited to, physically interactable and / or physically interacting components, wirelessly interactable and / or wirelessly interacting components, and / or logically interactable and / or logically interacting components.

[0082] It will be apparent that the present disclosure and many of its attendant advantages will be understood from the foregoing description, and that various changes in the form, construction and arrangement of the elements may be made without departing from the disclosed subject matter or sacrificing all of its important advantages. The forms described are merely illustrative, and it is the intent of the following claims to embrace and include such modifications. It is to be understood, further, that the invention is defined by the appended claims.

Claims

1. an illumination subsystem including one or more optical components and configured to illuminate a sample in two or more acquisition fields with two or more illumination beams, the two or more acquisition fields being distributed along a scan direction in a non-overlapping configuration, a translation stage sequentially translating a metrology object on the sample along the scan direction through the two or more acquisition fields, the illumination subsystem configured to alternately illuminate at least one of the two or more acquisition fields with two or more measurement recipes while the sample is being scanned, and portions of an image associated with at least one of the two or more acquisition fields include interleaved images associated with the two or more measurement recipes; an imaging subsystem configured to image the two or more acquisition fields while the sample is scanned along the scan direction by the translation stage, the imaging subsystem comprising: an objective lens configured to capture light from a sample within a measurement field of view, the two or more acquisition fields being within the measurement field of view; a scanning detector including one or more rows of pixels distributed along a row direction configured to generate two or more images of the two or more acquisition fields as the sample is scanned; an imaging subsystem comprising: a field relocation optical relay for relaying images of the two or more acquisition fields to the scanning detector, the field relocation optical relay positioning the images of the two or more acquisition fields along a row direction on the scanning detector such that the scan direction in the two or more acquisition fields is orthogonal to the row direction; A measurement tool comprising:

2. 2. The metrology tool of claim 1 , wherein the scanning detector comprises:

11. A metrology tool comprising: a time domain integration (TDI) detector, wherein the scan direction in the two or more repositioned acquisition fields is aligned with a charge movement direction of the TDI detector.

3. 2. The metrology tool of claim 1 , wherein measurement recipes including configurations of at least one of the illumination subsystem or the imaging subsystem are different for at least a portion of the two or more acquisition fields.

4. 4. The metrology tool of claim 3, wherein the configuration of at least one of the illumination subsystem or the imaging subsystem associated with the measurement recipe comprises: comprising at least one of an intensity, wavelength, polarization, or angle of incidence of at least one of the two or more illumination beams.

5. 4. The metrology tool of claim 3, wherein the configuration of at least one of the illumination subsystem or the imaging subsystem associated with the measurement recipe comprises: A metrology tool comprising at least one of an intensity, wavelength, polarization, and collection angle of light directed to the scanning detector.

6. 4. The metrology tool of claim 3, wherein the configuration of at least one of the illumination subsystem or the imaging subsystem associated with the measurement recipe comprises: A metrology tool comprising an imaging depth of the imaging subsystem.

7. 2. The metrology tool of claim 1 , wherein the illumination subsystem includes two or more illumination channels for illuminating the two or more acquisition fields with two or more illumination beams.

8. 8. The metrology tool of claim 7, wherein at least one of the two or more illumination channels directs at least one of the two or more illumination beams into at least one of the two or more acquisition fields at an illumination angle greater than a numerical aperture of the objective lens.

9. 8. The metrology tool of claim 7, wherein at least one of the two or more illumination channels directs at least one of the two or more illumination beams through the objective lens to at least one of the two or more acquisition fields.

10. 8. The metrology tool of claim 7, wherein the two or more acquisition fields are: a first acquisition field, wherein the illumination subsystem illuminates the first acquisition field with at least one of the two or more illumination beams under a first illumination condition of intensity, wavelength, polarization, or angle of incidence; and a second acquisition field, wherein the illumination subsystem illuminates the first acquisition field with at least one of the two or more illumination beams under a second illumination condition different from the first illumination condition.

11. 8. The metrology tool of claim 7, wherein the two or more acquisition fields are: a first acquisition field, the illumination subsystem illuminating the first acquisition field with a first illumination beam of the two or more illumination beams; a second acquisition field, wherein the illumination subsystem illuminates the second acquisition field with a first of the two or more illumination beams having an azimuth angle that is symmetrically opposed to a first of the two or more illumination beams.

12. 8. The metrology tool of claim 7, wherein the two or more acquisition fields are: a first acquisition field, wherein the illumination subsystem illuminates the first acquisition field with a first pair of the two or more illumination beams having orthogonal azimuth angles; a second acquisition field, wherein the illumination subsystem illuminates the second acquisition field with a second pair of the two or more illumination beams having orthogonal azimuth angles, the second pair of the two or more illumination beams being symmetrically opposed to the first pair of illumination beams.

13. 2. The metrology tool of claim 1, wherein the field relocation optical relay comprises: A metrology tool comprising one or more decentered optical elements.

14. 14. The metrology tool of claim 13, wherein the one or more decentered optical elements are: A metrology tool comprising at least one of one or more segmented optical elements having different surface profiles in two or more segments, one or more lens arrays, or one or more sets of individual optical elements.

15. 14. The metrology tool of claim 13, wherein the one or more decentered optical elements are:

13. A metrology tool comprising: at least one beam rotator for rotating an image of at least one of the two or more acquisition fields.

16. 16. The metrology tool of claim 15, wherein the at least one beam rotator comprises:

1. A metrology tool comprising at least one of a k-mirror or a Dove prism.

17. one or more illumination sources; a translation stage configured to translate the sample along a scan direction; an illumination subsystem including one or more optical components and configured to illuminate a sample in two or more acquisition fields with two or more illumination beams from the one or more illumination sources, the two or more acquisition fields being distributed along a scan direction in a non-overlapping configuration, the translation stage sequentially translating a metrology object on the sample along the scan direction through the two or more acquisition fields, the illumination subsystem configured to alternately illuminate at least one of the two or more acquisition fields with two or more measurement recipes while the sample is being scanned, and portions of an image associated with the at least one of the two or more acquisition fields include interleaved images associated with the two or more measurement recipes; an imaging subsystem configured to image the two or more acquisition fields while the sample is scanned along the scan direction by the translation stage, the imaging subsystem comprising: an objective lens configured to capture light from a sample within a measurement field of view, the two or more acquisition fields being within the measurement field of view; a scanning detector including one or more rows of pixels distributed along a row direction configured to generate two or more images of the two or more acquisition fields as the sample is scanned; an imaging subsystem comprising: a field relocation optical relay for relaying images of the two or more acquisition fields to the scanning detector, the field relocation optical relay positioning the images of the two or more acquisition fields along the column direction on the scanning detector such that the scan direction in the two or more acquisition fields is orthogonal to the column direction; a controller communicatively coupled to the imaging subsystem, receiving two or more images of the sample associated with the two or more fields of acquisition; generating metrology measurements associated with the sample based on the two or more images; and a controller including one or more processors configured to execute program instructions that cause the one or more processors to

18. 20. The metrology tool of claim 17, wherein the metrology measurements are:

16. A metrology tool comprising an overlay measurement.

19. 20. The metrology tool of claim 17, wherein the measurement object includes non-overlapping features on one or more sample layers.

20. 18. The measurement tool of claim 17, wherein the measurement object is: A metrology tool comprising a grid-on-grid overlay object comprising periodic features on two or more sample layers in overlapping regions.

21. 20. The metrology tool of claim 17, wherein the scanning detector comprises:

11. A metrology tool comprising: a time domain integration (TDI) detector, wherein the scan direction in the two or more repositioned acquisition fields is aligned with a charge movement direction of the TDI detector.

22. 20. The metrology tool of claim 17, wherein measurement recipes including configurations of at least one of the illumination subsystem or the imaging subsystem are different for at least a portion of the two or more acquisition fields.

23. 23. The metrology tool of claim 22, wherein the configuration of at least one of the illumination subsystem or the imaging subsystem associated with the measurement recipe comprises: comprising at least one of an intensity, wavelength, polarization, or angle of incidence of at least one of the two or more illumination beams.

24. 23. The metrology tool of claim 22, wherein the configuration of at least one of the illumination subsystem or the imaging subsystem associated with the measurement recipe comprises: A metrology tool comprising at least one of an intensity, wavelength, polarization, and collection angle of light directed to the scanning detector.

25. 23. The metrology tool of claim 22, wherein the configuration of at least one of the illumination subsystem or the imaging subsystem associated with the measurement recipe comprises: A metrology tool comprising an imaging depth of the imaging subsystem.

26. 20. The metrology tool of claim 17, wherein the illumination subsystem includes two or more illumination channels for illuminating the two or more acquisition fields with two or more illumination beams.

27. 27. The metrology tool of claim 26, wherein at least one of the two or more illumination channels directs at least one of the two or more illumination beams into at least one of the two or more acquisition fields at an illumination angle greater than a numerical aperture of the objective lens.

28. 27. The metrology tool of claim 26, wherein at least one illumination channel of the two or more illumination channels directs at least one of the two or more illumination beams through the objective lens to at least one of the two or more acquisition fields.

29. 27. The metrology tool of claim 26, wherein the two or more fields of acquisition include: a first acquisition field, wherein the illumination subsystem illuminates the first acquisition field with at least one of the two or more illumination beams under a first illumination condition of intensity, wavelength, polarization, or angle of incidence; and a second acquisition field, wherein the illumination subsystem illuminates the first acquisition field with at least one of the two or more illumination beams under a second illumination condition different from the first illumination condition.

30. 27. The metrology tool of claim 26, wherein the two or more fields of acquisition include: a first acquisition field, the illumination subsystem illuminating the first acquisition field with a first illumination beam of the two or more illumination beams; a second acquisition field, wherein the illumination subsystem illuminates the second acquisition field with a first of the two or more illumination beams having an azimuth angle that is symmetrically opposed to a first of the two or more illumination beams.

31. 27. The metrology tool of claim 26, wherein the two or more fields of acquisition include: a first acquisition field, wherein the illumination subsystem illuminates the first acquisition field with a first pair of the two or more illumination beams having orthogonal azimuth angles; a second acquisition field, wherein the illumination subsystem illuminates the second acquisition field with a second pair of the two or more illumination beams having orthogonal azimuth angles, the second pair of the two or more illumination beams being symmetrically opposed to the first pair of illumination beams.

32. 20. The metrology tool of claim 17, wherein the field relocation optical relay comprises: A metrology tool comprising one or more decentered optical elements.

33. 33. The metrology tool of claim 32, wherein the one or more decentered optical elements comprise: A metrology tool comprising at least one of one or more segmented optical elements having different surface profiles in two or more segments, one or more lens arrays, or one or more sets of individual optical elements.

34. 33. The metrology tool of claim 32, wherein the one or more decentered optical elements comprise:

13. A metrology tool comprising: at least one beam rotator for rotating an image of at least one of the two or more acquisition fields.

35. 35. The metrology tool of claim 34, wherein the at least one beam rotator comprises:

1. A metrology tool comprising at least one of a k-mirror or a Dove prism.

36. illuminating a sample in two or more acquisition fields with two or more illumination beams within a measurement field of an objective, the two or more acquisition fields being distributed along a scan direction in a non-overlapping configuration, and at least one of the two or more acquisition fields being alternately illuminated with two or more measurement recipes while the sample is being scanned, and portions of an image associated with the at least one of the two or more acquisition fields include interleaved images associated with the two or more measurement recipes; translating the sample sequentially along the scan direction through the two or more acquisition fields; relaying images of the two or more acquisition fields through the objective lens to a scanning detector using a field relocation optical relay, the field relocation optical relay positioning the images of the two or more acquisition fields along a column direction on the scanning detector such that the scan direction in the two or more acquisition fields is perpendicular to the column direction; generating two or more images of the sample associated with the two or more fields of acquisition; and generating metrology measurements associated with the sample based on the two or more images.

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