WO2024088727A1 - Agencement optique compact pour un système de métrologie - Google Patents

Agencement optique compact pour un système de métrologie Download PDF

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Publication number
WO2024088727A1
WO2024088727A1 PCT/EP2023/077661 EP2023077661W WO2024088727A1 WO 2024088727 A1 WO2024088727 A1 WO 2024088727A1 EP 2023077661 W EP2023077661 W EP 2023077661W WO 2024088727 A1 WO2024088727 A1 WO 2024088727A1
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Prior art keywords
radiation
portions
metasurfaces
target
optical component
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PCT/EP2023/077661
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English (en)
Inventor
Roxana REZVANI NARAGHI
Saman Jahani
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Asml Netherlands B.V.
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Publication of WO2024088727A1 publication Critical patent/WO2024088727A1/fr

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70653—Metrology techniques
    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
    • G02B1/002—Optical elements characterised by the material of which they are made; Optical coatings for optical elements made of materials engineered to provide properties not available in nature, e.g. metamaterials

Definitions

  • This description relates to a compact optical arrangement for a metrology system.
  • a lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs).
  • a patterning device e.g., a mask
  • a substrate e.g., silicon wafer
  • a target portion e.g. comprising one or more dies
  • a substrate e.g., silicon wafer
  • resist radiation-sensitive material
  • a single substrate includes a plurality of adjacent target portions to which the pattern is transferred successively by the lithographic projection apparatus, one target portion at a time.
  • the pattern on the entire patterning device is transferred onto one target portion in one operation.
  • Such an apparatus is commonly referred to as a stepper.
  • a projection beam scans over the patterning device in a given reference direction (the “scanning” direction) while synchronously moving the substrate parallel or anti-parallel to this reference direction. Different portions of the pattern on the patterning device are transferred to one target portion progressively.
  • the substrate Prior to transferring the pattern from the patterning device to the substrate, the substrate may undergo various procedures, such as priming, resist coating, and a soft bake. After exposure, the substrate may be subjected to other procedures (“post-exposure procedures”), such as a post-exposure bake (PEB), development, a hard bake and measurement/inspection of the transferred pattern.
  • post-exposure procedures such as a post-exposure bake (PEB), development, a hard bake and measurement/inspection of the transferred pattern.
  • PEB post-exposure bake
  • This array of procedures is used as a basis to make an individual layer of a device, e.g., an IC.
  • the substrate may then undergo various processes such as etching, ion-implantation (doping), metallization, oxidation, deposition, chemo-mechanical polishing, etc., all intended to finish the individual layer of the device.
  • This device manufacturing process may be considered a patterning process.
  • a patterning process involves a patterning step, such as optical and/or nanoimprint lithography using a patterning device in a lithographic apparatus, to transfer a pattern on the patterning device to a substrate and typically, but optionally, involves one or more related pattern processing steps, such as resist development by a development apparatus, baking of the substrate using a bake tool, etching using the pattern using an etch apparatus, deposition, etc.
  • a patterning step such as optical and/or nanoimprint lithography using a patterning device in a lithographic apparatus, to transfer a pattern on the patterning device to a substrate and typically, but optionally, involves one or more related pattern processing steps, such as resist development by a development apparatus, baking of the substrate using a bake tool, etching using the pattern using an etch apparatus, deposition, etc.
  • Lithography is a central step in the manufacturing of device such as ICs, where patterns formed on substrates define functional elements of the devices, such as microprocessors, memory chips, etc. Similar lithographic techniques are also used in the formation of flat panel displays, microelectro mechanical systems (MEMS) and other devices.
  • MEMS microelectro mechanical systems
  • RET resolution enhancement techniques
  • a metrology system is described. Active or passive metasurfaces are used to replace (or to augment) an existing objective lens to focus radiation such as light, tune a focal length, and/or correct aberrations in the metrology system, which enhances metrology system sensitivity, among other advantages.
  • the system comprises an optical component comprising an array of beam modifiers (e.g., metasurfaces) configured to modify an amplitude, phase, and/or polarization of an incident radiation beam from a radiation source.
  • the array of beam modifiers comprises first portions configured to receive the incident radiation beam from the radiation source, and transmit radiation having a modified amplitude, phase, and/or polarization, and focus the transmitted radiation toward a target.
  • the array of beam modifiers comprises second portions configured to receive diffracted radiation from the target, and transmit the diffracted radiation toward a detector.
  • the array of beam modifiers can be arranged in one plane, in a stack of planes of beam modifiers, and/or in other arrangements.
  • the first portions and the second portions overlap.
  • the optical component comprises a two dimensional (2D) array of beam modifiers.
  • the optical component comprises stacked two dimensional (2D) arrays of beam modifiers. In some embodiments, the optical component comprises a non-flat surface. [0014] In some embodiments, the first portions and the second portions are included in a single metasurface.
  • the first portions and the second portions comprise a plurality of metasurfaces.
  • the metrology system further comprises a wavelength-division multiplexer in a multi-core fiber, a blazed grating, or an additional metasurface.
  • the incident radiation received by the first portions is spatially separated by color into different wavelength groups using wavelength-division multiplexing in the multi-core fiber, using the blazed grating, using the additional metasurface, and/or another device
  • the first portions comprise individual metasurfaces formed in the optical component, are associated with different color wavelength groups, and are configured to receive incident radiation of an associated color and focus the transmitted radiation of that color on the target in a target location for that color.
  • the second portions comprise additional individual metasurfaces formed in the optical component, which are also associated with the different color wavelength groups, receive diffracted radiation of the associated color from the target, and transmit the diffracted radiation toward the detector.
  • each metasurface associated with the different color wavelength groups has a wavelength bandwidth for the associated color.
  • each metasurface comprises nano-antennas, meta-atoms, or nanoparticles.
  • the metasurfaces are active. In some embodiments, the metasurfaces are passive.
  • the optical component further comprises a second 2D array of beam modifiers.
  • the second 2D array comprises a second plurality of metasurfaces spaced from the plurality of metasurfaces along an optical path.
  • a spacing of the second plurality of metasurfaces from the plurality of metasurfaces controls a focal length of the optical component, corrects a defocus of the optical component, and/or corrects a wave front aberration.
  • the optical component further comprises a micro electrical mechanical system (MEMS) configured to adjust the spacing.
  • MEMS micro electrical mechanical system
  • the optical component further comprises a material filling a space between the second plurality of metasurfaces and the plurality of metasurfaces.
  • the material has a refractive index configured to be controlled to adjust a focus of the optical component.
  • the refractive index of the material is configured to be controlled by applying a voltage to the material or by applying an optical control signal to the material, the first portions, and/or the second portions.
  • the diffracted radiation from the target comprises + and - first order diffracted radiation, the + and - first order diffracted radiation configured to be received and transmitted with different corresponding second portions.
  • the different corresponding second portions comprise two different metasurfaces, each associated with the same color.
  • modifying an amplitude, phase, and/or polarization of the incident radiation beam facilitates focusing, tuning a focal length, and/or correcting an aberration of the radiation.
  • the system comprises the radiation source.
  • the radiation source is configured to generate the incident radiation beam.
  • the system comprise the detector.
  • the detector is configured to receive diffracted first or higher order radiation from the target via the second portions of the array, and generate a detection signal.
  • the optical component forms a portion of an alignment sensor and/or an overlay detection sensor.
  • the alignment sensor and/or the overlay detection sensor is configured for a semiconductor wafer, and is used in a semiconductor manufacturing process.
  • a metrology method comprises one or more of the operations described above performed by the metrology system.
  • FIG. 1 schematically depicts a lithography apparatus, according to an embodiment.
  • FIG. 2 schematically depicts an embodiment of a lithographic cell or cluster, according to an embodiment.
  • FIG. 3 schematically depicts an example inspection system, according to an embodiment.
  • Fig. 4 schematically depicts an example metrology technique, according to an embodiment.
  • Fig. 5 illustrates the relationship between a radiation illumination spot of an inspection system and a metrology target, according to an embodiment.
  • Fig. 6 illustrates a metrology system having an objective configured for directing radiation to or from one or more metrology targets, according to an embodiment.
  • Fig. 7 illustrates additional components of the metrology system that are associated with the objective, which add to the bulk and expense of the objective, according to an embodiment.
  • Fig. 8 illustrates a metrology system that provides a new compact optical design architecture compared to the objective and system shown in Fig. 6, according to an embodiment.
  • Fig. 9 illustrates spatially separating incident radiation by color into different wavelength groups using wavelength-division multiplexing in a multi-core fiber, or using a blazed grating, according to an embodiment.
  • Fig. 10 illustrates adjusting (e.g., changing a “z” dimension in this figure) the spacing “h” of a second two dimensional (2D) array of beam modifiers (e.g., a second plurality or layer of metasurfaces) from a first 2D array of beam modifiers (e.g., a first plurality or layer of metasurfaces), according to an embodiment.
  • 2D array of beam modifiers e.g., a second plurality or layer of metasurfaces
  • Fig. 11 illustrates a material filling a space between the second plurality or layer of metasurfaces and the first plurality or layer of metasurfaces, according to an embodiment.
  • Fig. 12 illustrates a top view and a side view of an example embodiment of an optical component having a body and various beam modifiers (metasurfaces) associated with radiation of different wavelength ranges (colors), according to an embodiment.
  • Fig. 13 illustrates possible examples of a beam modifier (metasurface) design layout for illuminating a micro diffraction based overlay target, according to an embodiment.
  • Fig. 14 illustrates a metrology method, according to an embodiment.
  • Fig. 15 is a block diagram of an example computer system, according to an embodiment.
  • metrology operations typically include determining the position of a metrology target (or marks) and/or other target in a layer of a semiconductor device structure. This position is typically determined by irradiating a metrology target with radiation, and comparing characteristics of different diffraction orders of radiation reflected from the metrology target. Such techniques are used to measure overlay, alignment, and/or other parameters.
  • Prior metrology systems use a bulky, multi-element objective to transmit radiation to a target such as a metrology mark, and reflect diffracted radiation from the metrology mark to a detector. These objectives increase the costs and size of a typical metrology system, cannot avoid chromatic aberration, and cannot correct all radiation beam aberrations.
  • active or passive metasurfaces are used to replace (or augment) an existing objective lens to focus radiation, tune a focal length, and/or correct aberrations in the metrology system, which enhances metrology system sensitivity.
  • the metrology system is more compact, lighter, and cheaper than prior systems.
  • the metrology system comprises first metasurfaces configured to receive an incident radiation beam from a radiation source, transmit radiation having a modified amplitude, phase, and/or polarization, and focus the transmitted radiation toward a target; and second metasurfaces configured to receive diffracted radiation from the target, and transmit the diffracted radiation toward a detector.
  • a size of a focal spot generated using metasurfaces is about 1.5 to 2 times smaller than the size of a focal spot for prior objectives.
  • the present system is configured to cover the operating radiation wavelength bandwidth of typical metrology sensors. As described below, incoming radiation is separated by color, and for each color, a specific metasurface focuses light on a metrology target, and another metasurface collects the reflected/ diffracted light coming from the target. All colors may be incident at the same time, which eliminates any required switching between radiation colors as in prior metrology systems.
  • projection optics should be broadly interpreted as encompassing various types of optical systems, including refractive optics, reflective optics, apertures and catadioptric optics, for example.
  • the term “projection optics” may also include components operating according to any of these design types for directing, shaping, or controlling the projection beam of radiation, collectively or singularly.
  • the term “projection optics” may include any optical component in the lithographic projection apparatus, no matter where the optical component is located on an optical path of the lithographic projection apparatus.
  • Projection optics may include optical components for shaping, adjusting and/or projecting radiation from the source before the radiation passes the patterning device, and/or optical components for shaping, adjusting and/or projecting the radiation after the radiation passes the patterning device.
  • the projection optics generally exclude the source and the patterning device.
  • Fig. 1 schematically depicts an embodiment of a lithographic apparatus LA.
  • the apparatus comprises an illumination system (illuminator) IL configured to condition a radiation beam B (e.g. UV radiation, DUV radiation, or EUV radiation); 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 positioner PM configured to accurately position the patterning device in accordance with certain parameters; a substrate table (e.g. a wafer table) WT (e.g., WTa, WTb or both) configured to hold a substrate (e.g.
  • a radiation beam B e.g. UV radiation, DUV radiation, or EUV radiation
  • 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 positioner PM configured to accurately position the patterning device in accordance with certain parameters
  • a substrate table e.
  • a resist-coated wafer W and coupled to a second positioner PW configured to accurately position the substrate in accordance with certain parameters; and a projection system (e.g. a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g. comprising one or more dies and often referred to as fields) of the substrate W.
  • the projection system is supported on a reference frame RF.
  • the apparatus is of a transmissive type (e.g. employing a transmissive mask).
  • the apparatus may be of a reflective type (e.g. employing a programmable mirror array, or employing a reflective mask).
  • the illuminator IL receives a beam of radiation from a radiation source SO.
  • the source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In such cases, the source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising for example suitable directing mirrors and/or a beam expander. In other cases, the source may be an integral part of the apparatus, for example when the source is a mercury lamp.
  • the source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.
  • the illuminator IL may alter the intensity distribution of the beam.
  • the illuminator may be arranged to limit the radial extent of the radiation beam such that the intensity distribution is non- zero within an annular region in a pupil plane of the illuminator IL. Additionally or alternatively, the illuminator IL may be operable to limit the distribution of the beam in the pupil plane such that the intensity distribution is non-zero in a plurality of equally spaced sectors in the pupil plane.
  • the intensity distribution of the radiation beam in a pupil plane of the illuminator IL may be referred to as an illumination mode.
  • the illuminator IL may comprise adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam.
  • adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam.
  • at least the outer and/or inner radial extent (commonly referred to as o-outer and o-inner, respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted.
  • the illuminator IL may be operable to vary the angular distribution of the beam.
  • the illuminator may be operable to alter the number, and angular extent, of sectors in the pupil plane wherein the intensity distribution is non-zero.
  • the intensity distribution may have a multi-pole distribution such as, for example, a dipole, quadrupole or hexapole distribution.
  • a desired illumination mode may be obtained, e.g., by inserting an optic which provides that illumination mode into the illuminator IL or using a spatial light modulator.
  • the illuminator IL may be operable to alter the polarization of the beam and may be operable to adjust the polarization using adjuster AD.
  • the polarization state of the radiation beam across a pupil plane of the illuminator IL may be referred to as a polarization mode.
  • the use of different polarization modes may allow greater contrast to be achieved in the image formed on the substrate W.
  • the radiation beam may be unpolarized.
  • the illuminator may be arranged to linearly polarize the radiation beam.
  • the polarization direction of the radiation beam may vary across a pupil plane of the illuminator IL.
  • the polarization direction of radiation may be different in different regions in the pupil plane of the illuminator IL.
  • the polarization state of the radiation may be chosen in dependence on the illumination mode.
  • the polarization of each pole of the radiation beam may be generally perpendicular to the position vector of that pole in the pupil plane of the illuminator IL.
  • the radiation may be linearly polarized in a direction that is substantially perpendicular to a line that bisects the two opposing sectors of the dipole.
  • the radiation beam may be polarized in one of two different orthogonal directions, which may be referred to as X-polarized and Y-polarized states.
  • the radiation in the sector of each pole may be linearly polarized in a direction that is substantially perpendicular to a line that bisects that sector.
  • This polarization mode may be referred to as XY polarization.
  • the radiation in the sector of each pole may be linearly polarized in a direction that is substantially perpendicular to a line that bisects that sector.
  • This polarization mode may be referred to as TE polarization.
  • the illuminator IL generally comprises various other components, such as an integrator IN and a condenser CO.
  • the illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping, or controlling radiation.
  • the illuminator provides a conditioned beam of radiation B, having a desired uniformity and intensity distribution in its cross section.
  • the support structure MT supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions, such as for example whether or not the patterning device is held in a vacuum environment.
  • the support structure may use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device.
  • the support structure may be a frame or a table, for example, which may be fixed or movable as required.
  • the support structure may ensure that the patterning device is at a desired position, for example with respect to the projection system. Any use of the terms “reticle” or “mask” herein may be considered synonymous with the more general term “patterning device.”
  • a patterning device used herein should be broadly interpreted as referring to any device that can be used to impart a pattern in a target portion of the substrate.
  • a patterning device is any device that can be used to impart a radiation beam with a pattern in its crosssection to create a pattern in a target portion of the substrate.
  • the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so called assist features.
  • the pattern imparted to the radiation beam will correspond to a particular functional layer in a device being created in a target portion of the device, such as an integrated circuit.
  • a patterning device may be transmissive or reflective.
  • Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels.
  • Masks are well known in lithography, and include mask types such as binary, alternating phase-shift, and attenuated phaseshift, as well as various hybrid mask types.
  • An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in a radiation beam, which is reflected by the mirror matrix.
  • projection system should be broadly interpreted as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system.”
  • the projection system PS may comprise a plurality of optical (e.g., lens) elements and may further comprise an adjustment mechanism configured to adjust one or more of the optical elements to correct for aberrations (phase variations across the pupil plane throughout the field).
  • the adjustment mechanism may be operable to manipulate one or more optical (e.g., lens) elements within the projection system PS in one or more different ways.
  • the projection system may have a coordinate system wherein its optical axis extends in the z direction.
  • the adjustment mechanism may be operable to do any combination of the following: displace one or more optical elements; tilt one or more optical elements; and/or deform one or more optical elements. Displacement of an optical element may be in any direction (x, y, z, or a combination thereof).
  • Tilting of an optical element is typically out of a plane perpendicular to the optical axis, by rotating about an axis in the x and/or y directions although a rotation about the z axis may be used for a non-rotationally symmetric aspherical optical element.
  • Deformation of an optical element may include a low frequency shape (e.g. astigmatic) and/or a high frequency shape (e.g. free form aspheres). Deformation of an optical element may be performed for example by using one or more actuators to exert force on one or more sides of the optical element and/or by using one or more heating elements to heat one or more selected regions of the optical element.
  • the transmission map of a projection system PS may be used when designing a patterning device (e.g., mask) MA for the lithography apparatus LA.
  • the patterning device MA may be designed to at least partially correct for apodization.
  • the lithographic apparatus may be of a type having two (dual stage) or more tables (e.g., two or more substrate tables WTa, WTb, two or more patterning device tables, a substrate table WTa and a table WTb below the projection system without a substrate that is dedicated to, for example, facilitating measurement, and/or cleaning, etc.).
  • the additional tables may be used in parallel, or preparatory steps may be conducted on one or more tables while one or more other tables are being used for exposure. For example, alignment measurements using an alignment sensor AS and/or level (height, tilt, etc.) measurements using a level sensor LS may be made.
  • the lithographic apparatus may also be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g. water, to fill a space between the projection system and the substrate.
  • a liquid having a relatively high refractive index e.g. water
  • An immersion liquid may also be applied to other spaces in the lithographic apparatus, for example, between the patterning device and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems.
  • immersion as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure.
  • a radiation beam is conditioned and provided by the illumination system IL.
  • the radiation beam B is incident on the patterning device (e.g., mask) MA, which is held on the support structure (e.g., mask table) MT, and is patterned by the patterning device.
  • the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W.
  • the substrate table WT can be moved accurately, e.g. to position different target portions C in the path of the radiation beam B.
  • the first positioner PM and another position sensor can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan.
  • movement of the support structure MT may be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM.
  • movement of the substrate table WT may be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW.
  • the support structure MT may be connected to a short-stroke actuator only, or may be fixed.
  • Patterning device MA and substrate W may be aligned using patterning device alignment marks Ml, M2 and substrate alignment marks Pl, P2.
  • the substrate alignment marks as illustrated occupy dedicated target portions, they may be located in spaces between target portions (these are known as scribe-lane alignment marks).
  • the patterning device alignment marks may be located between the dies.
  • the depicted apparatus may be used in at least one of the following modes.
  • step mode the support structure MT and the substrate table WT are kept essentially stationary, while a pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e. a single static exposure).
  • the substrate table WT is then shifted in the X and/or Y direction so that a different target portion C can be exposed.
  • step mode the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure.
  • scan mode the support structure MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam is projected onto a target portion C (i.e. a single dynamic exposure).
  • the velocity and direction of the substrate table WT relative to the support structure MT may be determined by the (de-) magnification and image reversal characteristics of the projection system PS.
  • scan mode the maximum size of the exposure field limits the width (in the non-scanning direction) of the target portion in a single dynamic exposure, whereas the length of the scanning motion determines the height (in the scanning direction) of the target portion.
  • the support structure MT is kept essentially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam is projected onto a target portion C.
  • a pulsed radiation source is employed, and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan.
  • This mode of operation can be readily applied to maskless lithography that utilizes programmable patterning device, such as a programmable mirror array of a type as referred to above. [0069] Combinations and/or variations on the above-described modes of use or entirely different modes of use may also be employed.
  • the substrate may be processed, before or after exposure, in for example a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or a metrology or inspection tool. Where applicable, the disclosure herein may be applied to such and other substrate processing tools. Further, the substrate may be processed more than once, for example in order to create a multi-layer IC, so that the term substrate used herein may also refer to a substrate that already includes multiple processed layers.
  • UV radiation and “beam” used herein with respect to lithography encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g. having a wavelength of 365, 248, 193, 157 or 126 nm) and extreme ultra-violet (EUV) radiation (e.g. having a wavelength in the range of 5-20 nm), as well as particle beams, such as ion beams or electron beams.
  • UV radiation ultraviolet
  • DUV radiation deep ultraviolet
  • EUV radiation extreme ultra-violet radiation
  • particle beams such as ion beams or electron beams.
  • Various patterns on or provided by a patterning device may have different process windows, i.e., a space of processing variables under which a pattern will be produced within specification. Examples of pattern specifications that relate to potential systematic defects include checks for necking, line pull back, line thinning, CD, edge placement, overlapping, resist top loss, resist undercut and/or bridging.
  • the process window of the patterns on a patterning device or an area thereof may be obtained by merging (e.g., overlapping) process windows of each individual pattern.
  • the boundary of the process window of a group of patterns comprises boundaries of process windows of some of the individual patterns. In other words, these individual patterns limit the process window of the group of patterns.
  • the lithographic apparatus LA may form part of a lithographic cell LC, also sometimes referred to a lithocell or cluster, which also includes apparatuses to perform pre- and post-exposure processes on a substrate.
  • a lithographic cell LC also sometimes referred to a lithocell or cluster
  • these include one or more spin coaters SC to deposit one or more resist layers, one or more developers to develop exposed resist, one or more chill plates CH and/or one or more bake plates BK.
  • a substrate handler, or robot, RO picks up one or more substrates from input/output port I/Ol, I/O2, moves them between the different process apparatuses and delivers them to the loading bay LB of the lithographic apparatus.
  • a substrate that is exposed by the lithographic apparatus is exposed correctly and consistently and/or in order to monitor a part of the patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., an optical lithography step)
  • a pattern transfer step e.g., an optical lithography step
  • a manufacturing facility in which lithocell LC is located also typically includes a metrology system that measures some or all of the substrates W (Fig. 1) that have been processed in the lithocell or other objects in the lithocell.
  • the metrology system may be part of the lithocell LC, for example it may be part of the lithographic apparatus LA (such as alignment sensor AS (Fig. 1)).
  • the one or more measured parameters may include, for example, alignment, overlay between successive layers formed in or on the patterned substrate, critical dimension (CD) (e.g., critical linewidth) of, for example, features formed in or on the patterned substrate, focus or focus error of an optical lithography step, dose or dose error of an optical lithography step, optical aberrations of an optical lithography step, etc.
  • CD critical dimension
  • This measurement is often performed on one or more dedicated metrology targets provided on the substrate. The measurement can be performed afterdevelopment of a resist but before etching, after-etching, after deposition, and/or at other times.
  • a fast and non-invasive form of specialized metrology tool is one in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered (diffracted/reflected) beam are measured. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. Traditionally, this may be termed diffraction-based metrology.
  • Applications of this diffraction-based metrology include the measurement of overlay, alignment, etc. For example, overlay and/or alignment can be measured by comparing parts of the diffraction spectrum (for example, comparing different diffraction orders in the diffraction spectrum of a periodic grating).
  • a substrate or other objects may be subjected to various types of measurement during or after the process.
  • the measurement may determine whether a particular substrate is defective, may establish adjustments to the process and apparatuses used in the process (e.g., aligning two layers on the substrate or aligning the patterning device to the substrate), may measure the performance of the process and the apparatuses, or may be for other purposes.
  • measurement examples include optical imaging (e.g., optical microscope), non-imaging optical measurement (e.g., measurement based on diffraction such as the ASML YieldStar metrology tool, the ASML SMASH metrology system), mechanical measurement (e.g., profiling using a stylus, atomic force microscopy (AFM)), and/or non- optical imaging (e.g., scanning electron microscopy (SEM)).
  • optical imaging e.g., optical microscope
  • non-imaging optical measurement e.g., measurement based on diffraction such as the ASML YieldStar metrology tool, the ASML SMASH metrology system
  • mechanical measurement e.g., profiling using a stylus, atomic force microscopy (AFM)
  • non- optical imaging e.g., scanning electron microscopy (SEM)
  • Metrology results may be provided directly or indirectly to the supervisory control system SCS. If an error is detected, an adjustment may be made to exposure of a subsequent substrate (especially if the inspection can be done soon and fast enough that one or more other substrates of the batch are still to be exposed) and/or to subsequent exposure of the exposed substrate. Also, an already exposed substrate may be stripped and reworked to improve yield, or discarded, thereby avoiding performing further processing on a substrate known to be faulty. In a case where only some target portions of a substrate are faulty, further exposures may be performed only on those target portions which meet specifications. Other manufacturing process adjustments are contemplated.
  • a metrology system may be used to determine one or more properties of the substrate structure, and in particular, how one or more properties of different substrate structures vary, or different layers of the same substrate structure vary from layer to layer.
  • the metrology system may be integrated into the lithographic apparatus LA or the lithocell LC, or may be a stand-alone device.
  • targets are specifically provided on the substrate.
  • the target is specially designed and may comprise a periodic structure.
  • the target on a substrate may comprise one or more 1-D periodic structures (e.g., geometric features such as gratings), which are printed such that after development, the periodic structural features are formed of solid resist lines.
  • the target may comprise one or more 2- D periodic structures (e.g., gratings), which are printed such that after development, the one or more periodic structures are formed of solid resist pillars or vias in the resist.
  • the bars, pillars, or vias may alternatively be etched into the substrate (e.g., into one or more layers on the substrate).
  • Fig. 3 depicts an example metrology (inspection) system 10 that may be used to detect overlay, alignment, and/or perform other metrology operations. It comprises a radiation or illumination source 2 which projects or otherwise irradiates radiation onto a substrate W (e.g., which may typically include a metrology mark). The redirected radiation is passed to a sensor such as a spectrometer detector 4 and/or other sensors, which measures a spectrum (intensity as a function of wavelength) of the specular reflected and/or diffracted radiation, as shown, e.g., in the graph on the left of Fig. 4. The sensor may generate a metrology signal conveying metrology data indicative of properties of the reflected radiation. From this data, the structure or profile giving rise to the detected spectrum may be reconstructed by one or more processors PRO, a generalized example of which is shown in Fig. 4, or by other operations.
  • a sensor such as a spectrometer detector 4 and/or other sensors, which measures a spectrum (intensity
  • one or more substrate tables may be provided to hold the substrate W during measurement operations.
  • the one or more substrate tables may be similar or identical in form to the substrate table WT (WTa or WTb or both) of Fig. 1.
  • Coarse and fine positioners may be provided and configured to accurately position the substrate in relation to a measurement optical system.
  • Various sensors and actuators are provided, for example, to acquire the position of a target portion of interest of a structure (e.g., a metrology mark), and to bring it into position under an objective lens.
  • the substrate support can be moved in X and Y directions to acquire different targets, and in the Z direction to obtain a desired location of the target portion relative to the focus of the optical system. It is convenient to think and describe operations as if the objective lens is being brought to different locations relative to the substrate, when, for example, in practice the optical system may remain substantially stationary (typically in the X and Y directions, but perhaps also in the Z direction) and the substrate moves.
  • the relative position of the substrate and the optical system is correct, it does not matter in principle which one of those is moving, or if both are moving, or a combination of a part of the optical system is moving (e.g., in the Z and/or tilt direction) with the remainder of the optical system being stationary and the substrate is moving (e.g., in the X and Y directions, but also optionally in the Z and/or tilt direction).
  • a target (portion) 30 on substrate W may be a 1-D grating, which is printed such that after development, the bars are formed of solid resist lines (e.g., which may be covered by a deposition layer), and/or other materials.
  • the target 30 may be a 2-D grating, which is printed such that after development, the grating is formed of solid resist pillars, and/or other features in the resist.
  • the bars, pillars, vias, and/or other features may be etched into or on the substrate (e.g., into one or more layers on the substrate), deposited on a substrate, covered by a deposition layer, and/or have other properties.
  • Target (portion) 30 e.g., of bars, pillars, vias, etc.
  • the measured data from target 30 may be used to determine an adjustment for one or more of the manufacturing processes, and/or used as a basis for making the actual adjustment.
  • the measured data from target 30 may indicate overlay for a layer of a semiconductor device.
  • the measured data from target 30 may be used (e.g., by the one or more processors PRO and/or other processors) for determining one or more semiconductor device manufacturing process parameters based the overlay, and determining an adjustment for a semiconductor device manufacturing apparatus based on the one or more determined semiconductor device manufacturing process parameters.
  • this may comprise a stage position adjustment, for example, or this may include determining an adjustment for a mask design, a metrology target design, a semiconductor device design, an intensity of the radiation, an incident angle of the radiation, a wavelength of the radiation, a pupil size and/or shape, a resist material, and/or other process parameters.
  • Fig. 5 illustrates a plan view of a typical target (e.g., metrology mark) 30, and the extent of a typical radiation illumination spot S in the system of Fig. 4.
  • the target 30, in an embodiment, is a periodic structure (e.g., grating) larger than the width (e.g., diameter) of the illumination spot S.
  • the width of spot S may be smaller than the width and length of the target.
  • the target in other words, is ‘underfilled’ by the illumination, and the diffraction signal is essentially free from any signals from product features and the like outside the target itself.
  • the illumination arrangement may be configured to provide illumination of a uniform intensity across a back focal plane of an objective, for example. Alternatively, by, for example, including an aperture in the illumination path, illumination may be restricted to on axis or off axis directions.
  • Fig. 6 illustrates a metrology system 600 having an objective 602 configured for directing radiation to or from one or more metrology targets 30, such as one or more diffraction grating targets.
  • the radiation may be used to obtain images of the metrology targets, and/or for other uses.
  • the radiation may comprise illumination such as light and/or other radiation.
  • a target 30 may comprise one or more metrology marks, such as diffraction grating targets, formed in a substrate such as a semiconductor wafer, for example.
  • Fig. 6 and system 600 may show a more detailed version of system 10 shown in Fig. 3.
  • system 600 may form, or form a portion of, system 10 described above with respect to Fig. 3.
  • System 600 may illustrate various subsystems of system 10, for example.
  • one or more components of system 600 may be similar to and/or the same as one or more components of system 10.
  • one or more components of system 600 may replace, be used with, and/or otherwise augment one or more components of system 10.
  • Objective 602 is a bulky, multi-element 604 objective.
  • Object 602 is a relatively expensive component of system 600, which increases the overall cost and size of system 600.
  • objective 602 includes multiple aspherical lenses which require accurate polishing, perfect alignment, and/or have other requirements.
  • objective 602 is configured for a wide range of radiation wavelengths, and thus cannot avoid chromatic aberration, and cannot correct all radiation beam aberrations. Aberrations introduce error in metrology detection signals, leading to overlay measurement deviation, as one example.
  • measurements made by system 600 are typically performed sequentially for radiation of different wavelengths (e.g., colors). Switching between the wavelengths slows down the metrology process and impacts manufacturing (e.g., semiconductor manufacturing) throughput.
  • Fig. 7 illustrates additional components 700 of system 600 (Fig. 6) that are associated with objective 602, which add to the bulk and expense of objective 602 and/or system 600.
  • components 700 include a leaf spring body 702 configured to move objective 602 (and provide guiding stiffness in the “x” and “y” directions (in this figure) for objective 602), an encoder bracket assembly 704 (associated with an encoder that measures a “z” position (in this figure) of objective 602), a magnet assembly 706 configured to provide force to counteract gravity and provide an emergency retraction force for objective 602 if needed, and motors 708 configured to actuate objective 602 (in the “z” direction) along with the other components 700.
  • Components 700 are configured to mechanically move objective 602 to modify a focal length of radiation, and/or for other reasons. Lenses within objective 602 may also be moved to adjust a lateral color offset. This mechanical movement slows down the metrology process, and inherent hysteresis can cause instability in metrology measurements. In addition, driving bulky components generates a significant amount of heat in the system, which then must be extracted, adding more complexity to system 600 and increasing costs.
  • Fig. 8 illustrates a metrology system 800 that provides a new optical design architecture compared to objective 602 and system 600 shown in Fig. 6.
  • Metrology system 800 may be part of, and/or be a subsystem of system 600, system 10 shown in Fig. 3, and/or other systems.
  • system 800 may form a portion of an alignment sensor and/or an overlay detection sensor represented by system 600 and/or system 10, as described herein.
  • the alignment sensor and/or the overlay detection sensor may be configured for a semiconductor wafer, for example, and may be used in a semiconductor manufacturing process.
  • system 800 may replace objective 602 and additional components 700 shown in Fig. 7.
  • system 800 may be used in conjunction with objective 602.
  • System 800 comprises an optical component 802 and/or other components.
  • Optical component 802 may include a body 803, beam modifiers 804, and/or other components.
  • Optical component 802 is configured to modify an amplitude, phase, and/or polarization of an incident radiation beam 810 from a radiation source (e.g., source 2 shown in Fig. 3 and described above). Modifying an amplitude, phase, and/or polarization of the incident radiation beam facilitates focusing, tuning a focal length, and/or correcting an aberration of the radiation.
  • Optical component 802 comprises an array of beam modifiers 804 and/or other components.
  • the array of beam modifiers may include first portions 820, second portions 830, and/or other beam modifiers.
  • First portions 820 are configured to receive incident radiation beam 810 from the radiation source, and transmit radiation 840 having a modified amplitude, phase, and/or polarization, and focus the transmitted radiation toward a target 850.
  • Second portions 830 are configured to receive diffracted radiation from target 850, and transmit the diffracted radiation toward a detector.
  • the modifying described above comprises receiving, with first portions 820 of the array of beam modifiers 804, the incident radiation beam 810 from the radiation source; transmitting, with first portions 820, radiation having a modified amplitude, phase, and/or polarization; and focusing, with first portions 820, the transmitted radiation toward target 850.
  • the modifying further comprises receiving, with second portions 830 of the array of beam modifiers 804, diffracted radiation from target 850; and transmitting, with second portions 830, the diffracted radiation toward a detector.
  • first portions 820 and second portions 830 overlap and/or are intermixed on body 803 of optical component 802, as shown in Fig. 8 for example.
  • optical component 802 comprises a two dimensional (2D) array of beam modifiers 804.
  • optical component 802 comprises stacked two dimensional (2D) arrays of beam modifiers 804.
  • optical component 802 comprises one or more non-flat surfaces.
  • first portions 820 and second portions 830 are included in a single body (e.g., in body 803 of optical component 802 shown in Fig. 8), which may be collectively referred to as a metasurface.
  • first portions 820 and second portions 830 comprise a plurality of metasurfaces (e.g., in separate bodies or simply individual metasurfaces within body 803 of optical component 802).
  • active or passive metasurfaces are used to replace (or to be added to) an existing objective lens (e.g., objective 602 shown in Fig. 6) to focus radiation, tune a focal length, and/or correct aberrations in metrology system 600 (Fig. 6), which enhances metrology system 600 sensitivity. This also makes metrology system 600, system 10 (Fig. 3), and/or other systems more compact, lighter, and cheaper than prior systems.
  • An active metasurface may be a reconfigurable metasurface.
  • a passive metasurface may be stationary and/or have no moving parts, and/or may include any metasurface that has a time unvarying properties: i.e., mechanical or optical properties are fixed.
  • each metasurface comprises nano-antennas, meta-atoms, or nanoparticles.
  • a metasurface also known as a metalens
  • a metasurface is a 2D array of nano-antennas, meta-atoms, or nanoparticles configured to modify the amplitude, phase, and/or polarization of an incident beam.
  • a metasurface may be used to replace bulky optical lenses (such as those included in objective 602 shown in Fig. 6) to focus light for applications such as metrology.
  • the efficiency of a metasurface can reach more than 80 percent for a specific incident radiation wavelength, and the numerical aperture of the metasurface can reach near unity.
  • a metasurface can also correct an aberration or be added to conventional lenses to correct a chromatic aberration.
  • a challenge of using metasurfaces in is that a useable incident radiation bandwidth is usually narrow, and a metasurface is sensitive to an incident angle and polarization of incident radiation.
  • a metasurface is sensitive to an incident angle and polarization of incident radiation.
  • metasurfaces may be used to replace or to be added to existing lenses.
  • system 800 (and/or metrology system 600 shown in Fig. 6) comprises a wavelength-division multiplexer in a multi-core fiber, a blazed grating, or one or more additional metasurfaces (e.g., having their own separate body that is different than optical component 802).
  • the additional metasurface(s) may be phase only transmissive spatial light modulators, for example.
  • incident radiation beam 810 received by first portions 820 may be spatially separated by color into different wavelength groups.
  • optical component 802 comprises a second 2D array of beam modifiers 804.
  • the second 2D array comprises a second plurality of metasurfaces (e.g., in a second body) spaced from the plurality of metasurfaces along an optical path.
  • a spacing of the second plurality of metasurfaces from the plurality of metasurfaces may be adjusted to control a focal length of optical component 802, correct a defocus of optical component 802, correct a wave front aberration, and/or for other reasons.
  • adjusting the spacing comprises moving one of the 2D arrays of beam modifiers relative to the other 2D array. Movement may comprise translating or otherwise changing a distance between the arrays.
  • the optical component comprises a micro electrical mechanical system (MEMS), and the spacing may be adjusted via movement by the MEMS system.
  • MEMS micro electrical mechanical system
  • movement may be controlled electronically by a processor, such as processor PRO shown in Fig. 3 (and also in Fig. 15 discussed below).
  • Processor PRO may be included in a computing system (e.g., CS in Fig. 15) and may operate based on computer or machine readable instructions MRI (e.g., as described below related to Fig. 15).
  • Electronic communication may occur by transmitting electronic signals between separate components, transmitting data between separate components of system 800, transmitting values between separate components, and/or other communication.
  • the components of system 800 may communicate via wires or wirelessly via a network, such as the Internet or the Internet in combination with various other networks, like local area networks, cellular networks, or personal area networks, internal organizational networks, and/or other networks.
  • one or more actuators may be coupled to and configured to move one or more components of system 800.
  • the actuators may be coupled to one or components of system 800 by adhesive, clips, clamps, screws, a collar, and/or other mechanisms.
  • the actuators may be configured to be controlled electronically.
  • Individual actuators may be configured to convert an electrical signal into mechanical displacement.
  • the mechanical displacement is configured to move a component of system 800, such as one or more metasurfaces.
  • one or more of the actuators may be piezoelectric.
  • One or more processors PRO may be configured to control the actuators.
  • One or more processors PRO may be configured to individually control each of the one or more actuators.
  • Figs. 9 and 10 illustrate several of the above described features.
  • Fig. 9 illustrates spatially separating incident radiation beam 810 by color into different wavelength groups using wavelength-division multiplexing in a multi-core fiber 900, or using a blazed grating 904.
  • Fig. 9 also illustrates how optical component 802 may comprise a second 2D array of beam modifiers 910.
  • the second 2D array comprises a second plurality of metasurfaces (e.g., in a second body or on a bottom surface of body 803 shown in Fig. 8) spaced 920 from the (first) plurality of beam modifiers (e.g., metasurfaces) 804, along an optical path 930.
  • Fig. 10 illustrates adjusting 1000 (e.g., changing a “z” dimension in this figure) the spacing “h” of the second 2D array of beam modifiers 910 (e.g., the second plurality of metasurfaces) from the (first) plurality of beam modifiers (e.g., metasurfaces) 804, to control a focal length of the optical component, correct a defocus of the optical component, correct a wave front aberration, and/or for other reasons.
  • the adjusting 1000 is performed by a MEMS system, responsive to a voltage “V” that is applied to the system being changed from 0 to some alternate value “Vo”, which actuates the MEMS system.
  • beam modifiers 910 are closer to beam modifiers 804 on the right side of the figure compared to the left side.
  • Active tuning of the focal length with metasurfaces facilitates elimination of the mechanical movement of bulky components (as described above) for a focus adjustment and/or for other purposes.
  • this metasurface based design is configured to cover the entire operating bandwidth of an existing overlay sensor, for example. This is accomplished by spatially separating the colors of incident radiation (e.g., as shown in Fig. 9 and 10), and for each color, a specific metasurface (e.g., one or more beam modifiers 804) focuses radiation on a mark (e.g., target 850) and another metasurface (e.g., one or more beam modifiers 910) collects the reflected/ diffracted light coming back from the marks. All colors of radiation can be used at the same time. This helps to eliminate the switching between colors necessary in prior systems.
  • meta-atoms in metasurfaces may be resonant-type nanostructures. Hence, they have a limited wavelength bandwidth. If each unit-cell in a metasurface is composed of multiple meta-atoms, system 800 can achieve the same functionality at multiple wavelengths, but covering an entire wavelength range of visible light remains difficult. Thus, system 800 is configured to spatially separate different wavelengths (as shown on the left side of both Fig. 9 and Fig. 10). Again, this can be done by wavelength-division multiplexing in a multi-core fiber (see the left side of Fig. 9 and the description above), by using a blazed grating (right side of Fig. 9 and described above), and/or by other methods.
  • a blazed grating can be fabricated using a single step etching by varying a filling fraction of a uniform slab, for example.
  • This color separating functionality can also be done by a metasurface.
  • system 800 may include additional metasurfaces fabricated on the same wheel as was used to switch input colors. This reduces the complexity of the design. For example, for each color, a separate metasurface can be fabricated and the metasurfaces can be placed on a rotating disc. Depending on which wavelength is being exposed, the disc is configured to be rotated to place the corresponding metasurface in the path of beam.
  • each color passes through a different metasurface (e.g., beam modifiers 804 and/or beam modifiers 910) which is designed for that specific color.
  • a different metasurface e.g., beam modifiers 804 and/or beam modifiers 910
  • Two sets or layers of metasurfaces e.g., a metasurface doublet - a 2D array of beam modifiers 804 and a 2D array of beam modifiers 910) may be used to enhance the flexibility in designing the metasurfaces, to correct aberrations, and/or for other purposes.
  • system 800 is configured to control the focal length as described above.
  • a second metasurface layer in the examples shown in Fig.
  • the separate colors are focused on the same spot (at target 850) and/or in specific locations for specific colors on the spot. Separating colors facilitates elimination of chromatic aberration, and as a result, system 800 does not need a mechanical stage to correct a defocus for each wavelength.
  • system 800 may be configured such that the focal length of incident radiation beam 810 / optical component 802 is tunable.
  • the distance between the two layers of metasurfaces e.g., the spacing “h” of the second 2D array of beam modifiers 910 (e.g., the second plurality of metasurfaces) from the (first) plurality of beam modifiers (e.g., metasurfaces) 804), can be controlled using MEMS (e.g., a MEMS tunable dielectric metasurface lens).
  • MEMS e.g., a MEMS tunable dielectric metasurface lens
  • optical component 802 (also shown in Fig. 8) comprises a material 1100 filling a space between the second plurality (layer) of metasurfaces and the first plurality (layer) of metasurfaces (the second 2D array of beam modifiers 910 and the first 2D array of beam modifiers 804).
  • the material may have a refractive index configured to be controlled to adjust a focus of optical component 802 / focal length of incident radiation beam 810.
  • the material may comprise liquid crystals, an electro-optic material, and/or other materials.
  • the electro-optic materials comprise some polymers, lithium niobate, aluminum nitride, etc.
  • a liquid crystal may be any commercially available liquid crystal, including for example E7® from Merck.
  • the refractive index of the material may be controlled by applying a voltage to the material or by applying an optical control signal, for example.
  • Fig. 11 illustrates voltage off on the left side of the figure, and the right side of the figure illustrates voltage on.
  • system 800 may change an effective optical path length between the two layers and change the focal length by few microns.
  • the layers are significantly lighter (in weight) than existing bulky objectives, the natural frequencies of the MEMS-tunable metasurfaces (in this example) are significantly higher, which allows system 800 to perform focal adjustment with a higher speed.
  • the tuning speed of liquid crystal-based and electro-optics-based metasurfaces are even higher.
  • system 800 may comprise metasurfaces (e.g., beam modifiers 804 and/or 910) with high index electro-optic materials such as lithium niobate configured to reach GHz -range tuning speeds.
  • the metasurfaces can be made of silicon, silicon nitride, titanium dioxide, and/or other materials which have high refractive index.
  • system 800 may be configured to control the focus, and also correct errors in a phase-front of the radiation by adjusting an applied phase by each meta-atom.
  • system 800 (e.g., in combination with one or more components shown in Fig. 6 and/or Fig. 3) is configured to measure the radiation beam (e.g., the wavefront), calculate the error (e.g., error in the wavefront), and apply the proper phase to each meta- atom.
  • This type of metasurface can be added to an existing metrology system, without the need to replace the objective lens, for example.
  • first portions 820 of beam modifiers 804 comprise individual metasurfaces formed in optical component 802, are associated with different color wavelength groups (e.g., as described above and shown in Fig. 9-11), and are configured to receive incident radiation beam 810 of an associated color and focus the transmitted radiation of that color on target 850 in a target location for that color (e.g., as described above and shown in Fig. 9-11).
  • Second portions 830 of beam modifiers 804 comprise additional individual metasurfaces formed in optical component 802, which are also associated with the different color wavelength groups, receive diffracted radiation of the associated color from target 850, and transmit the diffracted radiation toward a detector (described above).
  • each metasurface associated with the different color wavelength groups has a wavelength bandwidth for the associated color.
  • metasurfaces (beam modifiers 804), which are working at different wavelengths, are spatially separated (e.g., in body 803 of optical component 802 and/or in one more bodies of one or more optical components), and capture the reflected and diffracted radiation (e.g., light) of different colors coming from target 850.
  • Fig. 12 illustrates a top view 1200 and a side view 1202 of an example embodiment of optical component 802 having body 803 and various beam modifiers 804 (metasurfaces) associated with radiation of different wavelength ranges (colors).
  • a dimension “d” of each metasurface (beam modifier 804) is on the order of a few hundred microns (at a working distance of few millimeters), so optical component 802 is configured such that the metasurfaces do not overlap with each other.
  • each metasurface can be designed to work at multiple wavelengths, or may be configured for wider bandwidths by using more complex meta-atoms.
  • optical component 802 shown in Fig. 12 is configured to facilitate illumination 1201 of one or more targets (marks) with different colors of radiation via first portion 820 of beam modifiers 804 (metasurfaces), and capture 1203 reflected (0 th order) 1210 and diffracted (+/- 1 st order in this example) 1212, 1214 radiation coming back from the one or more targets via second portion 830 of beam modifiers 804 (metasurfaces).
  • Each of the metasurfaces (beam modifiers 804) may be made of the same materials, but to distinguish their operating wavelengths, are shown as corresponding to different colors in Fig. 12.
  • Fig. 13 illustrates a first possible example (top half of Fig. 13) of a beam modifier 804 (metasurface) design layout 1302 (in top view 1300 and side view 1301) for illuminating a micro diffraction based overlay target 1304.
  • Various beam modifiers 804 are again associated with radiation of different wavelength ranges (colors).
  • Beam modifiers 804 are configured to facilitate illumination 1310 of one or more targets 1304 (marks) with different colors of radiation via first portion 820 of beam modifiers 804 (metasurfaces), and capture 1312 diffracted (+/- 1st order in this example) 1320, 1322 radiation coming back from the one or more targets 1304 via second portion 830 of beam modifiers 804 (metasurfaces). As shown in Fig.
  • Fig. 13 also illustrates a second possible example (bottom half of Fig. 13) of a beam modifier 804 (metasurface) design layout 1375 (in top view 1376) for illuminating a micro diffraction based overlay target 1380.
  • Design layout 1375 is configured such that beam modifiers 804 (metasurfaces) illuminate all four quadrants 1382, 1384, 1386, and 1388 of target 1380 and capture one diffraction order at the adjacent quadrant.
  • Encircled 1390 beam modifiers 804 (metasurfaces) are the emitters (first portion 820 described above) and the rest are the capturing metasurfaces (second portion 830 described above).
  • Fig. 12 shows the side view and the top view of one design for a second metasurface layer that may be used to illuminate a target and capture the Oth and 1st diffraction orders.
  • Fig. 13 For micro diffraction based overlay targets (e.g., as shown in Fig. 13), the design is more complicated, but can still be configured to illuminate and capture the diffracted lights using metasurfaces without having an overlap (Fig. 13).
  • Fig. 14 illustrates a metrology method 1401.
  • method 1401 is performed as part of an overlay and/or alignment sensing operation in a semiconductor device manufacturing process, for example.
  • one or more operations of method 1401 may be implemented in or by a metrology system such as system 800 illustrated in Fig. 8, system 10 illustrated in Fig. 3, a computer system (e.g., as illustrated in Fig. 15 and described below), and/or in or by other systems, for example.
  • method 1401 comprises generating (operation 1402) an incident radiation beam, modifying (operation 1404) the incident radiation beam, generating (operation 1406) a detection signal, and/or other operations.
  • method 1401 may be accomplished with one or more additional operations not described, and/or without one or more of the operations discussed.
  • method 1401 may include an additional operation comprising determining overlay and/or alignment for a semiconductor wafer, and determining an adjustment for a semiconductor device manufacturing process. Additionally, the order in which the operations of method 1401 are illustrated in Fig. 14 and described herein is not intended to be limiting.
  • one or more portions of method 1401 may be implemented in and/or controlled by one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and/or other mechanisms for electronically processing information).
  • the one or more processing devices may include one or more devices executing some or all of the operations of method 1401 in response to instructions stored electronically on an electronic storage medium.
  • the one or more processing devices may include one or more devices configured through hardware, firmware, and/or software to be specifically designed for execution of one or more of the operations of method 1401 (e.g., see discussion related to Fig. 14 below).
  • an incident radiation beam is generated.
  • the incident radiation beam is generated by a radiation source that is part of the metrology system.
  • the radiation source is the same as or similar to illumination source 2 shown in Fig. 3 and described above.
  • an amplitude, phase, and/or polarization of the incident radiation beam from the radiation source is modified. Modifying an amplitude, phase, and/or polarization of the incident radiation beam facilitates focusing, tuning a focal length, and/or correcting an aberration of the radiation.
  • the modifying is performed by an optical component of the metrology system.
  • the optical component may be similar to and/or the same as optical component 802 shown in Fig. 8.
  • the optical component forms a portion of an alignment sensor and/or an overlay detection sensor.
  • the alignment sensor and/or the overlay detection sensor may be configured for a semiconductor wafer, for example, and may be used in a semiconductor manufacturing process.
  • the optical component comprises an array of beam modifiers and/or other components.
  • the beam modifiers may be similar to and/or the same as beam modifiers 804 shown in Fig. 8, for example.
  • the array of beam modifiers may include first portions, second portions, and/or other beam modifiers.
  • the first portions are configured to receive the incident radiation beam from the radiation source, and transmit radiation having a modified amplitude, phase, and/or polarization, and focus the transmitted radiation toward a target.
  • the second portions are configured to receive diffracted radiation from the target, and transmit the diffracted radiation toward a detector.
  • the first portions and the second portions overlap and/or are intermixed on a body of the optical component, for example.
  • the optical component comprises a two dimensional (2D) array of beam modifiers.
  • the optical component comprises stacked two dimensional (2D) arrays of beam modifiers.
  • the optical component comprises one or more non-flat surfaces.
  • the first portions and the second portions are included in a single metasurface (e.g., in the body of optical component 802 shown in Fig. 8).
  • the first portions and the second portions comprise a plurality of metasurfaces (e.g., separate bodies or simply individual metasurfaces within the body of optical component 802).
  • the metasurfaces may be active or passive.
  • the modifying comprises receiving, with first portions of the array of beam modifiers, the incident radiation beam from the radiation source; transmitting, with the first portions, radiation having a modified amplitude, phase, and/or polarization; and focusing, with the first portions, the transmitted radiation toward a target.
  • the modifying comprises receiving, with second portions of the array of beam modifiers, diffracted radiation from the target; and transmitting, with the second portions, the diffracted radiation toward a detector.
  • the metrology system comprises a wavelength-division multiplexer in a multi-core fiber, a blazed grating, or an additional metasurface (e.g., having its own separate body that is different than optical component 802).
  • Operation 1404 may comprise spatially separating the incident radiation received by the first portions by color into different wavelength groups using wavelength-division multiplexing in the multi-core fiber, using the blazed grating, or using the additional metasurface.
  • the first portions comprise individual metasurfaces formed in the optical component, are associated with different color wavelength groups, and are configured to receive incident radiation of an associated color and focus the transmitted radiation of that color on the target in a target location for that color.
  • the second portions comprise additional individual metasurfaces formed in the optical component, which are also associated with the different color wavelength groups, receive diffracted radiation of the associated color from the target, and transmit the diffracted radiation toward the detector.
  • each metasurface associated with the different color wavelength groups has a wavelength bandwidth for the associated color.
  • each metasurface comprises nano-antennas, meta-atoms, or nanoparticles.
  • the optical component comprises a second 2D array of beam modifiers.
  • the second 2D array comprises a second plurality of metasurfaces (e.g., in a second body) spaced from the plurality of metasurfaces along an optical path.
  • Operation 1404 may include adjusting a spacing of the second plurality of metasurfaces from the plurality of metasurfaces to control a focal length of the optical component, correct a defocus of the optical component, and/or correct a wave front aberration, for example.
  • the optical component comprises a micro electrical mechanical system (MEMS), and operation 1404 comprises adjusting the spacing with the MEMS.
  • MEMS micro electrical mechanical system
  • the optical component comprises a material filling a space between the second plurality of metasurfaces and the plurality of metasurfaces.
  • the material may have a refractive index configured to be controlled to adjust a focus of the optical component.
  • Operation 1404 may include controlling the refractive index of the material by applying a voltage to the material or by applying an optical control signal to the material, the first portions, and/or the second portions.
  • the radiation may be directed onto multiple targets on a substrate such as a semiconductor wafer, a single target, sub-portions (e.g., something less than the whole) of a target, and/or onto a substrate in other ways.
  • the radiation may be directed onto the target in a time varying manner.
  • the radiation may be rastered over a target (e.g., by moving the target under the radiation) such that different portions of the target are irradiated at different times.
  • characteristics of the radiation e.g., wavelength, intensity, etc.
  • This may create time varying data envelopes, or windows, for analysis.
  • the data envelopes may facilitate analysis of individual sub-portions of a target, comparison of one portion of a target to another and/or to other targets (e.g., in other layers), and/or other analysis.
  • a detection signal is generated.
  • the detection signal may be generated based on detected reflected radiation from diffraction grating target(s), as described above.
  • the detection signal is generated by a sensor (such as detector 4 in Fig. 3, a camera, and/or other sensors) based on radiation received by the sensor.
  • the detection signal comprises measurement information pertaining to the target(s).
  • the detection signal may be an overlay and/or alignment signal comprising overlay and/or alignment measurement information, and/or other metrology signals.
  • the measurement information (e.g., an overlay value, an alignment value, and/or other information) may be determined using principles of interferometry and/or other principles.
  • the detection signal comprises an electronic signal that represents and/or otherwise corresponds to the radiation reflected from the target(s).
  • Diffracted radiation from a target may comprise + and - first order diffracted radiation.
  • the + and - first order diffracted radiation is configured to be received and transmitted with different corresponding second portions.
  • the different corresponding second portions comprise two different metasurfaces, each associated with the same color.
  • the detection signal may indicate a metrology value associated with a diffraction grating target, for example, and/or other information.
  • Generating the detection signal comprises sensing the reflected radiation and converting the sensed reflected radiation into the electronic signal.
  • generating the detection signal comprises sensing different portions of the reflected radiation from different areas and/or different geometries of the target, and/or multiple targets, and combining the different portions of the reflected radiation to form the detection signal. This may include generating and/or analyzing one or more images of a target, using the radiation described herein. This sensing and converting may be performed by components similar to and/or the same as detector 4 and/or processors PRO shown in Fig. 3, and/or other components.
  • method 1401 comprises detecting reflected radiation from one or more diffraction grating targets.
  • Detecting reflected radiation comprises detecting one or more phase and/or amplitude (intensity) shifts in reflected radiation from one or more geometric features of the target(s).
  • the one or more phase and/or amplitude shifts correspond to one or more dimensions of a target.
  • the phase and/or amplitude of reflected radiation from one side of a target is different relative to the phase and/or amplitude of reflected radiation from another side of the target.
  • Detecting the one or more phase and/or amplitude (intensity) shifts in the reflected radiation from the target comprises measuring local phase shifts (e.g., local phase deltas) and/or amplitude variations that correspond to different portions of a target.
  • the reflected radiation from a specific area of a target may comprise a sinusoidal waveform having a certain phase and/or amplitude.
  • the reflected radiation from a different area of the target (or a target in a different layer) may also comprise a sinusoidal waveform, but one with a different phase and/or amplitude.
  • Detected reflected radiation also comprises measuring a phase and/or amplitude difference in reflected radiation of different diffraction orders.
  • Detecting the one or more local phase and/or amplitude shifts may be performed using Hilbert transformations, for example, and/or other techniques. Interferometry techniques and/or other operations may be used to measure phase and/or amplitude differences in reflected radiation of different diffraction orders.
  • method 1401 comprises determining an adjustment for a semiconductor device manufacturing process.
  • method 1401 includes determining one or more semiconductor device manufacturing process parameters.
  • the one or more semiconductor device manufacturing process parameters may be determined based on one or more detected phase and/or amplitude variations, an overlay and/or alignment value indicated by the detection signal, and/or other similar systems, and/or other information.
  • the one or more parameters may include a parameter of the radiation (the radiation used for metrology), an overlay value, an alignment value, a metrology inspection location on a layer of a semiconductor device structure, a radiation beam trajectory across a target, and/or other parameters.
  • process parameters can be interpreted broadly to include a stage position, a mask design, a metrology target design, a semiconductor device design, an intensity of the radiation (used for exposing resist, etc.), an incident angle of the radiation (used for exposing resist, etc.), a wavelength of the radiation (used for exposing resist, etc.), a pupil size and/or shape, a resist material, and/or other parameters.
  • method 1401 includes determining a process adjustment based on the one or more determined semiconductor device manufacturing process parameters, adjusting a semiconductor device manufacturing apparatus based on the determined adjustment, and/or other operations. For example, if a determined metrology measurement is not within process tolerances, the out of tolerance measurement may be caused by one or more manufacturing processes whose process parameters have drifted and/or otherwise changed so that the process is no longer producing acceptable devices (e.g., measurements may breach a threshold for acceptability). One or more new or adjusted process parameters may be determined based on the measurement determination. The new or adjusted process parameters may be configured to cause a manufacturing process to again produce acceptable devices.
  • a new or adjusted process parameter may cause a previously unacceptable measurement value to be adjusted back into an acceptable range.
  • the new or adjusted process parameters may be compared to existing parameters for a given process. If there is a difference, that difference may be used to determine an adjustment for an apparatus that is used to produce the devices (e.g., parameter “x” should be increased / decreased / changed so that it matches the new or adjusted version of parameter “x” determined as part of method 1401), for example.
  • method 1401 may include electronically adjusting an apparatus (e.g., based on the determined process parameters).
  • Electronically adjusting an apparatus may include sending an electronic signal, and/or other communications to the apparatus, for example, which causes a change in the apparatus.
  • the electronic adjustment may include changing a setting on the apparatus, for example, and/or other adjustments.
  • FIG 15 is a diagram of an example computer system CS that may be used for one or more of the operations described herein.
  • Computer system CS includes a bus BS or other communication mechanism for communicating information, and a processor PRO (or multiple processors similar to and/or the same as processor PRO shown in Fig. 3) coupled with bus BS for processing information.
  • Computer system CS also includes a main memory MM, such as a random access memory (RAM) or other dynamic storage device, coupled to bus BS for storing information and instructions to be executed by processor PRO.
  • Main memory MM also may be used for storing temporary variables or other intermediate information during execution of instructions by processor PRO.
  • Computer system CS further includes a read only memory (ROM) ROM or other static storage device coupled to bus BS for storing static information and instructions for processor PRO.
  • ROM read only memory
  • a storage device SD such as a magnetic disk or optical disk, is provided and coupled to bus BS for storing information and instructions.
  • Computer system CS may be coupled via bus BS to a display DS, such as a flat panel or touch panel display or a cathode ray tube (CRT) for displaying information to a computer user.
  • a display DS such as a flat panel or touch panel display or a cathode ray tube (CRT) for displaying information to a computer user.
  • An input device ID is coupled to bus BS for communicating information and command selections to processor PRO.
  • cursor control CC such as a mouse, a trackball, or cursor direction keys for communicating direction information and command selections to processor PRO and for controlling cursor movement on display DS.
  • This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), that allows the device to specify positions in a plane.
  • a touch panel (screen) display may also be used as an input device.
  • all or some of one or more operations described herein may be performed by computer system CS in response to processor PRO executing one or more sequences of one or more instructions contained in main memory MM.
  • Such instructions may be read into main memory MM from another computer-readable medium, such as storage device SD.
  • Execution of the sequences of instructions included in main memory MM causes processor PRO to perform the process steps (operations) described herein.
  • processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory MM.
  • hard-wired circuitry may be used in place of or in combination with software instructions. Thus, the description herein is not limited to any specific combination of hardware circuitry and software.
  • Non-volatile media include, for example, optical or magnetic disks, such as storage device SD.
  • Volatile media include dynamic memory, such as main memory MM.
  • Transmission media include coaxial cables, copper wire and fiber optics, including the wires that comprise bus BS. Transmission media can also take the form of acoustic or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications.
  • RF radio frequency
  • IR infrared
  • Computer-readable media can be non-transitory, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magnetic medium, a CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with patterns of holes, a RAM, a PROM, and EPROM, a FLASH-EPROM, any other memory chip or cartridge.
  • Non-transitory computer readable media can have instructions recorded thereon. The instructions, when executed by a computer, can implement any of the operations described herein.
  • Transitory computer-readable media can include a carrier wave or other propagating electromagnetic signal, for example.
  • Various forms of computer readable media may be involved in carrying one or more sequences of one or more instructions to processor PRO for execution.
  • the instructions may initially be borne on a magnetic disk of a remote computer.
  • the remote computer can load the instructions into its dynamic memory and send the instructions over a telephone line using a modem.
  • a modem local to computer system CS can receive the data on the telephone line and use an infrared transmitter to convert the data to an infrared signal.
  • An infrared detector coupled to bus BS can receive the data carried in the infrared signal and place the data on bus BS.
  • Bus BS carries the data to main memory MM, from which processor PRO retrieves and executes the instructions.
  • the instructions received by main memory MM may optionally be stored on storage device SD either before or after execution by processor PRO.
  • Computer system CS may also include a communication interface CI coupled to bus BS.
  • Communication interface CI provides a two-way data communication coupling to a network link NDL that is connected to a local network LAN.
  • communication interface CI may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line.
  • ISDN integrated services digital network
  • communication interface CI may be a local area network (LAN) card to provide a data communication connection to a compatible LAN.
  • LAN local area network
  • Wireless links may also be implemented.
  • communication interface CI sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.
  • Network link NDL typically provides data communication through one or more networks to other data devices.
  • network link NDL may provide a connection through local network LAN to a host computer HC.
  • This can include data communication services provided through the worldwide packet data communication network, now commonly referred to as the “Internet” INT.
  • Internet may use electrical, electromagnetic, or optical signals that carry digital data streams.
  • the signals through the various networks and the signals on network data link NDL and through communication interface CI, which carry the digital data to and from computer system CS, are exemplary forms of carrier waves transporting the information.
  • Computer system CS can send messages and receive data, including program code, through the network(s), network data link NDL, and communication interface CL
  • host computer HC might transmit a requested code for an application program through Internet INT, network data link NDL, local network LAN, and communication interface CI.
  • One such downloaded application may provide all or part of a method described herein, for example.
  • the received code may be executed by processor PRO as it is received, and/or stored in storage device SD, or other nonvolatile storage for later execution. In this manner, computer system CS may obtain application code in the form of a carrier wave.
  • a metrology system comprising: an optical component comprising an array of beam modifiers configured to modify an amplitude, phase, and/or polarization of an incident radiation beam from a radiation source, the array of beam modifiers comprising: first portions configured to receive the incident radiation beam from the radiation source, and transmit radiation having a modified amplitude, phase, and/or polarization, and focus the transmitted radiation toward a target; and second portions configured to receive diffracted radiation from the target, and transmit the diffracted radiation toward a detector.
  • optical component comprises a two dimensional (2D) array of beam modifiers.
  • optical component comprises stacked two dimensional (2D) arrays of beam modifiers.
  • the metrology system further comprises a wavelength-division multiplexer in a multi-core fiber, a blazed grating, or an additional metasurface, and wherein the incident radiation received by the first portions is spatially separated by color into different wavelength groups using wavelength-division multiplexing in the multi-core fiber, using the blazed grating, or using the additional metasurface.
  • first portions comprise individual metasurfaces formed in the optical component, are associated with different color wavelength groups, and are configured to receive incident radiation of an associated color and focus the transmitted radiation of that color on the target in a target location for that color.
  • the second portions comprise additional individual metasurfaces formed in the optical component, which are also associated with the different color wavelength groups, receive diffracted radiation of the associated color from the target, and transmit the diffracted radiation toward the detector.
  • each metasurface associated with the different color wavelength groups has a wavelength bandwidth for the associated color.
  • each metasurface comprises nano-antennas, meta-atoms, or nanoparticles.
  • optical component further comprises a second 2D array of beam modifiers, the second 2D array comprising a second plurality of metasurfaces spaced from the plurality of metasurfaces along an optical path.
  • optical component further comprises a micro electrical mechanical system (MEMS) configured to adjust the spacing.
  • MEMS micro electrical mechanical system
  • optical component further comprises a material filling a space between the second plurality of metasurfaces and the plurality of metasurfaces, the material having a refractive index configured to be controlled to adjust a focus of the optical component.
  • the refractive index of the material is configured to be controlled by applying a voltage to the material or by applying an optical control signal to the material, the first portions, and/or the second portions.
  • the diffracted radiation from the target comprises + and - first order diffracted radiation, the + and - first order diffracted radiation configured to be received and transmitted with different corresponding second portions, the different corresponding second portions comprising two different metasurfaces, each associated with the same color.
  • a metrology method comprising: modifying, with an optical component comprising an array of beam modifiers, an amplitude, phase, and/or polarization of an incident radiation beam from a radiation source, the modifying comprising: receiving, with first portions of the array of beam modifiers, the incident radiation beam from the radiation source; transmitting, with the first portions, radiation having a modified amplitude, phase, and/or polarization; and focusing, with the first portions, the transmitted radiation toward a target; and receiving, with second portions of the array of beam modifiers, diffracted radiation from the target; and transmitting, with the second portions, the diffracted radiation toward a detector.
  • optical component comprises a two dimensional (2D) array of beam modifiers.
  • first portions comprise individual metasurfaces formed in the optical component, are associated with different color wavelength groups, and are configured to receive incident radiation of an associated color and focus the transmitted radiation of that color on the target in a target location for that color.
  • the second portions comprise additional individual metasurfaces formed in the optical component, which are also associated with the different color wavelength groups, receive diffracted radiation of the associated color from the target, and transmit the diffracted radiation toward the detector.
  • each metasurface associated with the different color wavelength groups has a wavelength bandwidth for the associated color.
  • each metasurface comprises nano-antennas, meta-atoms, or nanoparticles.
  • the optical component further comprises a second 2D array of beam modifiers, the second 2D array comprising a second plurality of metasurfaces spaced from the plurality of metasurfaces along an optical path.
  • the optical component further comprises a micro electrical mechanical system (MEMS), and wherein the method comprises adjusting the spacing with the MEMS.
  • MEMS micro electrical mechanical system
  • the optical component further comprises a material filling a space between the second plurality of metasurfaces and the plurality of metasurfaces, the material having a refractive index configured to be controlled to adjust a focus of the optical component.
  • the diffracted radiation from the target comprises + and - first order diffracted radiation, the + and - first order diffracted radiation configured to be received and transmitted with different corresponding second portions, the different corresponding second portions comprising two different metasurfaces, each associated with the same color.
  • the concepts disclosed herein may be associated with any generic imaging system for imaging sub wavelength features, and may be especially useful with emerging imaging technologies capable of producing increasingly shorter wavelengths.
  • Emerging technologies already in use include EUV (extreme ultra violet), DUV lithography that is capable of producing a 193nm wavelength with the use of an ArF laser, and even a 157nm wavelength with the use of a Fluorine laser.
  • EUV lithography is capable of producing wavelengths within a range of 20-5nm by using a synchrotron or by hitting a material (either solid or a plasma) with high energy electrons in order to produce photons within this range.
  • the concepts disclosed herein may be used for imaging on a substrate such as a silicon wafer, it shall be understood that the disclosed concepts may be used with any type of lithographic imaging systems, e.g., those used for imaging on substrates other than silicon wafers.
  • the combination and sub-combinations of disclosed elements may comprise separate embodiments.

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Abstract

L'invention concerne un système de métrologie. Des métasurfaces actives ou passives sont utilisées pour remplacer (ou augmenter) une lentille d'objectif existante pour focaliser un rayonnement tel que la lumière, pour accorder une longueur focale, et/ou pour corriger des aberrations dans le système de métrologie. Le système de métrologie comprend des premières métasurfaces ou des parties d'une métasurface conçues pour recevoir le faisceau de rayonnement incident provenant de la source de rayonnement, pour transmettre un rayonnement ayant une amplitude, une phase et/ou une polarisation modifiées, et pour focaliser le rayonnement transmis vers une cible ; et des secondes métasurfaces ou parties de la métasurface conçues pour recevoir un rayonnement diffracté provenant de la cible et pour transmettre le rayonnement diffracté vers un détecteur.
PCT/EP2023/077661 2022-10-28 2023-10-05 Agencement optique compact pour un système de métrologie WO2024088727A1 (fr)

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