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WO2025078101A1 - Correction d'aberration dans un système de métrologie - Google Patents

Correction d'aberration dans un système de métrologie Download PDF

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Publication number
WO2025078101A1
WO2025078101A1 PCT/EP2024/075580 EP2024075580W WO2025078101A1 WO 2025078101 A1 WO2025078101 A1 WO 2025078101A1 EP 2024075580 W EP2024075580 W EP 2024075580W WO 2025078101 A1 WO2025078101 A1 WO 2025078101A1
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WO
WIPO (PCT)
Prior art keywords
metasurfaces
radiation beam
metrology
aberration
target
Prior art date
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PCT/EP2024/075580
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English (en)
Inventor
Saman Jahani
Ali Basiri
Roxana REZVANI NARAGHI
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ASML Netherlands BV
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ASML Netherlands BV
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Publication of WO2025078101A1 publication Critical patent/WO2025078101A1/fr
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Classifications

    • 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
    • G03F7/706843—Metrology apparatus
    • G03F7/706849—Irradiation branch, e.g. optical system details, illumination mode or polarisation control
    • 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
    • G03F7/706843—Metrology apparatus
    • G03F7/706851—Detection branch, e.g. detector arrangements, polarisation control, wavelength control or dark/bright field detection

Definitions

  • This description relates to aberration correction in 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 whole procedure, or a variant thereof, is repeated for each layer.
  • a device will be present in each target portion on the substrate. These devices are then separated from one another by a technique such as dicing or sawing, such that the individual devices can be mounted on a carrier, connected to pins, etc.
  • 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.
  • 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, micro-electro mechanical systems (MEMS) and other devices.
  • MEMS micro-electro mechanical systems
  • RET resolution enhancement techniques
  • one or more metasurfaces are used to correct aberrations caused by optical element(s) (e.g., lenses, beam splitters, mirrors, refractive or diffractive optical components, etc.).
  • a metasurface also known as a metalens
  • a metasurface is a relatively thin 2D planar surface array of structures configured to modify the trajectory, amplitude, phase, polarization, and/or other characteristics of an incident beam.
  • the one or more metasurfaces are configured to replace one or more refractive elements, diffractive elements, and/or a moving stage, for example, previously used for aberration correction in prior metrology systems. This makes the present metrology systems more compact, lighter, and cheaper than prior systems, among other advantages.
  • a metrology system associated with semiconductor manufacturing comprises an optical element configured to receive and transmit an incident radiation beam.
  • the optical element causes an aberration in the incident radiation beam.
  • the aberration comprises an undesired change in a target characteristic of the incident radiation beam.
  • the system comprises one or more metasurfaces configured to reverse the change in the target characteristic to correct the aberration caused by the optical element.
  • the one or more metasurfaces comprises an array of metasurfaces.
  • the array of metasurfaces comprises a two dimensional (2D) array of metasurfaces.
  • each metasurface comprises nano-antennas, meta-atoms, or nano-particles.
  • the one or more metasurfaces are active. In some embodiments, the one or more metasurfaces are passive.
  • a corrected radiation beam is configured to be used in an illumination branch of the metrology system to illuminate a metrology target on a patterned substrate and/or be used by a detector in a detection branch of the metrology system to generate a metrology detection signal.
  • the aberration comprises a chromatic aberration, a spherical aberration, and/or a coma aberration. In some embodiments, the aberration comprises a lateral color aberration.
  • the undesired change in the target characteristic of the incident radiation beam comprises a shift in the incident radiation beam due to a change in wavelength.
  • the one or more metasurfaces are configured to adjust the incident radiation beam back to a target position, which helps to eliminate needed mechanical movement of a stage of the metrology system.
  • the undesired change comprises a change in trajectory of the incident radiation beam away from a target focal point.
  • the one or more metasurfaces are configured to re-direct the incident radiation beam back toward the target focal point.
  • the one or more metasurfaces are positioned before the optical element along an optical path of the incident radiation beam. In some embodiments, the one or more metasurfaces are positioned after the optical element along an optical path of the incident radiation beam.
  • the optical element comprises a lens, a beam splitter, a mirror, and/or a refractive or diffractive optical component.
  • the one or more metasurfaces are configured to replace one or more refractive elements, diffractive elements, and or a moving stage in the metrology system previously used for aberration correction.
  • the one or more metasurfaces are configured to modify an amplitude, phase, and/or polarization of the incident radiation beam.
  • the metrology system comprises a radiation source.
  • the radiation source is configured to generate the incident radiation beam.
  • the metrology system comprises a detector.
  • the detector is configured to receive diffracted first or higher order radiation from a metrology target.
  • the metrology target diffracts the incident radiation beam before or after the optical element causes the aberration and the one or metasurfaces reverse the change in the target characteristic to correct the aberration.
  • the detector is also configured to generate a detection signal.
  • the optical element and one or more metasurfaces form 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 metrology 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 a metrology system and a metrology target, according to an embodiment.
  • Fig. 6 illustrates a metrology system comprising one or more metasurfaces configured to correct an aberration in an incident radiation beam, according to an embodiment.
  • Fig. 7 illustrates an example metasurface, according to an embodiment.
  • Fig. 8 illustrates a side view of an incident radiation beam, an optical element (a lens in this example), and a lateral color aberration, according to an embodiment.
  • Fig. 9 illustrates a side view of the same incident radiation beam from Fig. 8, and optical element, but with one or more metasurfaces configured to correct the lateral color aberration, according to an embodiment.
  • Fig. 10 illustrates a metrology method, according to an embodiment.
  • Fig. 11 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 targets) 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 one or more bulky, multi-element, assemblies to correct for chromatic aberrations in the radiation. These assemblies may include multiple refractive (e.g. positive and negative doublets) and/or diffractive (e.g. Fresnel lens) optical elements with opposite dispersion slopes, moving stages, and/or other components.
  • corrective assemblies in prior metrology systems may include multiple corrective crown or flint lenses for color correction, which contribute to a higher metrology system cost of goods, mass, and volume.
  • the optical design of these assemblies for chromatic aberration correction is fundamentally limited by glass dispersion properties and optical element surface form, such that often there is some residual aberration not easily corrected by the traditional approach.
  • mechanical movement of an objective or other lens assemblies for chromatic aberration correction is time consuming (which impacts product throughput), and requires mechatronic assemblies (which further increase the metrology system cost of goods, mass, and volume, and reduces the lifetime of the machine).
  • one or more metasurfaces are used to correct aberrations.
  • the bulky, multi-element, assemblies used in prior metrology systems to correct for chromatic aberrations in radiation are eliminated.
  • a metasurface is a two dimensional (2D) array of custom- designed subwavelength nano-antennas (a.k.a. meta-atoms) which is capable of modifying the amplitude, phase, and polarization of an incident beam of radiation.
  • Custom engineering of the meta- atoms facilitates use of non-conventional materials (e.g., materials other than glass) on a subwavelength thickness scale. Since one or more metasurfaces are used instead of the bulky, multi-element assemblies, the present metrology system is more capable, more compact, lighter, and cheaper than prior systems, among other advantages.
  • aberration correction (which is not limited to chromatic aberration correction, but instead also includes spherical, coma, and/or other aberration correction) is achieved by engineering an optical response (e.g., controlling the effective index, unit cell geometry, phase, amplitude and polarization, etc.) of the one or more metasurfaces.
  • the one or more metasurfaces reduce metrology system volume and mass by shrinking an optics footprint from three dimensional (which is more bulky) to 2D (e.g., with a subwavelength-thickness), improve the metrology system cost of goods (e.g., resulting from at least lower material, handing, and shipping costs), and enhance metrology process throughput (e.g., by enabling denser integration, parallel operations in a given volume, and faster scanning due to reduced mass).
  • new functionalities beyond what was possible for conventional optical elements and their conventional optical materials e.g. FS, Si, etc.
  • engineered dispersion, polarization response, light attenuation and phase control, etc. is provided by the one or more metasurfaces.
  • 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 phase-shift, 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 co- ordinate 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.
  • 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.
  • 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 and UV radiation 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 ultraviolet
  • DUV deep ultraviolet
  • EUV extreme ultra-violet
  • 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 part of the patterning process e.g., a device manufacturing process
  • at least one pattern transfer step e.g., an optical lithography step
  • overlay which can be, for example, between structures in overlying layers or between structures in a same layer that have been provided separately to the layer by, for example, a double patterning process
  • line thickness e.g., critical dimension (CD), focus offset
  • 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 after-development 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 metrology target such as 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.
  • Fig. 3 depicts an example metrology system 10 that may be used to detect overlay, alignment, and/or perform other metrology operations. It comprises a radiation source 2 which projects or otherwise irradiates radiation onto a substrate W such as a semiconductor wafer (e.g., which may typically include a metrology target). 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 detector may generate a metrology detection 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. 3.
  • a radiation source 2 which projects or otherwise irradiates radiation onto a substrate W such as a semiconductor wafer (e.g.,
  • 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.
  • WTa or WTb or both 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 metrology target 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 30 e.g., 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 metrology target 30 (e.g., a metrology mark), 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 comprising one or more metasurfaces 650 configured to correct an aberration in an incident radiation beam.
  • system 600 is just one representative example of several different possible types of systems (which may or may not have some or all of the same components and/or may function in slightly different ways) that may utilize metasurface(s) 650. Examples of such systems include ASML’s YieldStar system and/or other systems.
  • System 600 is the same as or similar to system 10 described above with respect to Fig. 3, with one or more components of system 600 being similar to and/or the same as one or more components of system 10 (and Fig. 6 illustrating several additional possible components of the system).
  • System 600 comprises a radiation source 612 (e.g., similar to and/or the same as source 2 shown in Fig. 3), one or more detectors 604 and/or 610 (e.g., similar to and/or the same as detector 4 shown in Fig. 3), one or more processors PRO (similar to and/or the same as processor PRO shown in Fig. 3), and various lenses, beam splitters, mirrors, refractive or diffractive components, and/or other components (e.g., see the various labeled boxes in system 600) which comprise optical elements 675.
  • One or more processors PRO are operatively connected with detector 604, detector 610, and/or other components of system 600.
  • Fig. 6 illustrates an illumination branch 625 of system 600 including radiation source 612, an overlay detection branch 660 including detector 604 and one or more processors PRO; a focus branch 655; an alignment branch 680 with a detector 610 (which may be, and/or be the same as or similar to detector 604) and one or more processors PRO (which may be, and/or be similar and/or the same as the processors in overlay detection branch 660); an objective 690; and/or other components.
  • the components of system 600 form a portion of an overlay and/or alignment sensor configured to be used in a semiconductor manufacturing process.
  • Fig. 6 also illustrates a metrology target 30 which may comprise one or more metrology marks, such as diffraction grating targets, formed in a substrate 602 such as a semiconductor wafer, collectively referred to as metrology target 30, for example.
  • Target 30 may comprise one or more structures in the patterned substrate capable of providing a diffraction signal.
  • targets 30 may be included in a layer of a substrate in a semiconductor device structure, for example.
  • target 30 comprises a geometric feature such as a ID or 2D feature, and/or other geometric features.
  • the feature may comprise a grating, a line, an edge, a fine-pitched series of lines and/or edges, and/or other features.
  • Various lenses (example objective 690 is labeled in Fig. 6), reflectors, mirrors, refractive or diffractive optical components, and other optical elements 675 are configured to receive, transmit, reflect, focus, and/or perform other operations on the illumination generated by illumination source 612, focused by focus branch 655, received by an overlay detection branch 660, received by alignment branch 680, and/or used by other portions of system 600.
  • These various lenses, reflectors, and/or other optical components may comprise optical elements.
  • the optical elements are configured for directing, shaping, focusing, or otherwise controlling the projection beam of radiation, collectively or singularly. They may include any type of lens, reflector, and/or other optical component configured to allow system 600 to function as described.
  • objective 690 may include one or more lenses formed from any transparent material and have curved surfaces configured to concentrate or otherwise focus one or more spots of radiation on target(s) 30.
  • the various lenses, reflectors, optical elements, beam splitters, and other optical elements may be positioned in any location and/or at any angle relative to each other that allows system 600 to function as described herein. This may include positioning at specific relative distances between elements, specific angles between elements, etc.
  • the various lenses, reflectors, optical elements, beam splitters, and other optical components are positioned relative to each other in system 600 via structural members, clips, clamps, screws, nuts, bolts, adhesive, and/or other mechanical devices.
  • various ones of the lenses, reflectors, optical elements, beam splitters, and other optical elements are movable relative to each other. Movement may be configured to adjust locations of corresponding spots of illumination on one or more targets 30, for example. In some embodiments, movement comprises tilting, translating or otherwise changing a distance between various lenses, reflectors, and other optical components. Other examples of movement are contemplated.
  • movement may be controlled electronically by a processor, such as processor PRO.
  • processor PRO may be included in a computing system CS (Fig. 11) and may operate based on computer or machine readable instructions (e.g., as described below related to Fig. 11).
  • Electronic communication may occur by transmitting electronic signals between separate components, transmitting data between separate components of system 600, transmitting values between separate components, and/or other communication.
  • the components of system 600 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 600.
  • the actuators may be coupled to one or components of system 600 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 600.
  • 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.
  • Radiation source 612 is configured to generate radiation.
  • the generated radiation may be in the form of an incident radiation beam (noting that an incident radiation beam described herein may simply be any radiation beam that is incident on some optical element 675, for example).
  • the radiation may comprise illumination such as light and/or other radiation.
  • the radiation from radiation source 612 comprises a Gaussian radiation beam and/or other radiation.
  • the radiation may have a target wavelength and/or wavelength range, a target intensity, and/or other characteristics.
  • the target wavelength and/or wavelength range, the target intensity, etc. may be entered and/or selected by a user, determined by system 600 based on previous measurements, and/or determined in other ways.
  • the light comprises visible light, infrared light, near infrared light, and/or other light.
  • the radiation may be any radiation appropriate for interferometry.
  • system 600 is configured such that an optical element 675 (or one or more optical element(s) 675) is configured to receive and transmit an incident radiation beam.
  • optical element 675 may be any of the boxes labeled as optical element 675.
  • optical element 675 comprises a lens, a beam splitter, a mirror, a refractive or diffractive optical component, and/or other optical elements.
  • the optical element 675 causes an aberration in the incident radiation beam.
  • the aberration comprises an undesired change in a target characteristic of the incident radiation beam.
  • the target characteristic may be angle, amplitude, phase/wavefront, polarization, focus position, focal spot quality/uniformity, and/or other characteristics.
  • the aberration comprises a chromatic aberration, a spherical aberration, a coma aberration, and/or other aberrations.
  • the aberration may be a lateral color aberration.
  • Chromatic aberration causes different colors to be focused at different spots. If all colors are focused on the same longitudinal axis (parallel to the optical axis of the lens system), the aberration is called axial color aberration. On the other hand, if different colors are focused along the same focal plane but they are laterally shifted irrespective to each other, the aberration is called lateral color aberration. Lateral color aberration can happen due to odd aberration of the lens or due to off-axis illumination, for example.
  • One or more metasurfaces 650 are configured to reverse the change in the target characteristic of the incident radiation beam to correct the aberration caused by the optical element 675.
  • Corrected radiation may be used in illumination branch 625 of metrology system 600 to illuminate metrology target 30 on patterned substrate 602, be used by a detector 604 in an overlay detection branch 660 of metrology system 600 to generate a detection signal (e.g., a metrology signal), be used by a detector 610 in an alignment branch 680 of metrology system 600 to generate the detection signal (e.g., a metrology signal), and/or may be used for other purposes.
  • One or more metasurfaces 650 comprise a new optical design architecture compared to the optical design architecture used in prior metrology systems. As described above, the bulky, multielement, assemblies that often included mechatronic stages used in prior metrology systems to correct for chromatic aberrations in radiation are eliminated. Instead, aberration correction is achieved by engineering an optical response (e.g., controlling the effective index, unit cell geometry, phase, amplitude and polarization, etc.) of the one or more metasurfaces 650.
  • One or more metasurfaces may be reflective (or partially reflective), transmissive (or partially transmissive), and/or have other properties.
  • the one or more metasurfaces 650 are positioned before or after a specific optical element 675 (or elements) along an optical path of the incident radiation beam.
  • the specific optical element 675 may be known to cause aberrations.
  • one or more metasurfaces 650 are positioned just before objective 690, and just after another optical element 675, along an optical path of an incident radiation beam that proceeds from source 612 to metrology target 30.
  • this arrangement is not intended to be limiting.
  • One or more metasurfaces 650 may be placed in any position that allows metrology system 600 to function as described herein.
  • the one or more metasurfaces 650 may comprise a single metasurface 651, as shown in the enlarged portion of Fig. 6.
  • the one or more metasurfaces 650 may comprise an array of metasurfaces 653, each configured to modify an amplitude, phase, polarization, and/or other characteristics of the incident radiation beam.
  • the array may be two dimensional (2D) and/or have other dimensionality. It may also consist of one or more layers of metasurface. Other configurations that allow system 600 to function as described herein are contemplated.
  • One or more metasurfaces 650 each (e.g., each metasurface 651 and/or 653) comprise a body; beam modifiers such as nano-antennas, meta-atoms, nano-particles; and/or other structures.
  • One or more metasurfaces 650 may comprise electro-optic materials, liquid crystals, phase change materials (e.g., dielectric to metal or vice versa), and/or other materials.
  • One or more metasurfaces 650 are configured to replace one or more refractive elements, diffractive elements, and/or a moving stage in a metrology system previously used for aberration correction, as described herein.
  • One or metasurfaces 650 may include different individual metasurfaces, and/or a single metasurface 650 may include different portions, configured for different wavelengths, polarizations, diffraction orders, angles of incidence, phases, polarizations, and/or other characteristics of incident radiation.
  • the different metasurfaces and/or portions of a single metasurface may overlap on a metasurface body, and/or may be otherwise intermixed on the body.
  • different metasurfaces 650 and/or different portions of a single metasurface 650 are included in a single body, which may be collectively referred to as a metasurface.
  • the different metasurfaces 650 and/or different portions of a single metasurface 650 comprise a plurality of metasurfaces in separate bodies or simply individually separated metasurfaces within the body.
  • One or more metasurfaces 650 may be active or passive.
  • An active metasurface may be a reconfigurable metasurface. This can be done by modifying the structure (moving the parts, stretching, etc.) and/or by changing the material parameters (applying voltage to change refractive index in electrooptics materials, changing the orientation direction in liquid crystals, changing the phase of matter (dielectric to metal or vice versa) in phase change materials, etc.), and/or other methods.
  • 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.
  • Fig. 7 illustrates an example metasurface 700.
  • Metasurface 700 is a possible example of one or more metasurfaces 650 shown in Fig. 6.
  • Fig. 7 includes a schematic view 702 of a portion of metasurface 700, along with magnified and widened scanning electron microscope views 704 and 706, respectively, of metasurface 700.
  • Schematic view 702 includes a perspective view 703, a top view 705, and a side view 707.
  • Metasurface 700 comprises a body 710; beam modifiers 712 such as nanoantennas, meta-atoms, nano-particles; and/or other structures.
  • Metasurface 700 may comprise electro- optic materials, liquid crystals, phase change materials (e.g., dielectric to metal or vice versa), and/or other materials.
  • Metasurface 700 is reflective.
  • Metasurface 700 comprises silicon (Si) beam modifiers and/or any high index material, (e.g. SiN, TiO2, Lithium Niobate, AIN, etc.), and body 710 comprises a silicon dioxide (SiO2) base layer.
  • Each beam modifier 712 may have a square or rectangular cross section, and/or any other cross sectional shape that facilitates performance as described herein.
  • Beam modifiers 712 may be arranged in parallel and perpendicular rows, a honeycomb lattice, other types of lattices, and/or in any other layout that facilitates performance as described herein. These shapes and/or this configuration is only an example, and may be changed depending on the application.
  • metasurface 700 can be used to locally control the sign of the dispersion of an incident radiation beam (e.g., so that the beam disperses, or focuses, for example). This allows system 600 (Fig. 6) to decrease or increase a lateral shift of the incident radiation beam (caused by an aberration) at different wavelengths. In conjunction with controlling a shift, an angle of deflected radiation may also be controlled using a metasurface similar to metasurface 700.
  • the undesired change in the target characteristic of the incident radiation beam comprises a shift in the incident radiation beam due to a change in wavelength. It also comprises distorting the beam quality and uniformity.
  • the one or more metasurfaces are configured to adjust the incident radiation beam back to a target position, which helps to eliminate needed mechanical movement of a stage of the metrology system.
  • the undesired change comprises a change in trajectory of the incident radiation beam away from a target focal point.
  • the one or more metasurfaces are configured to re-direct the incident radiation beam back toward the target focal point.
  • Fig. 8 and Fig. 9 illustrate an optical element 800 (e.g., a representative example of optical elements 675 shown in Fig. 6 and described above) configured to receive and transmit an incident radiation beam 802, and metasurface(s) 804 (e.g., a representative example of one or more metasurfaces 650 shown in Fig. 6 and described above) configured to reverse a change in a target characteristic of beam 802 to correct an aberration caused by optical element 800.
  • the aberration is a lateral color aberration 808, and optical element 800 is part of an illumination branch of a metrology system (e.g., illumination branch 625 of system 600 shown in Fig. 6).
  • a detection branch of a metrology system and/or in other locations of a metrology system.
  • Fig. 8 illustrates a side view of incident radiation beam 802, optical element 800 (a lens in this example), and lateral color aberration 808.
  • Fig. 9 illustrates a side view of the same incident radiation beam 802, and optical element 800, but with metasurface(s) 804 configured to correct lateral color aberration 808.
  • Fig. 8 and 9 both also illustrate an aperture stop 810 and an image plane 812 associated with incident radiation beam 802 and optical element 800.
  • a substrate such as a semiconductor wafer may be positioned in image plane 812.
  • Optical element 800 causes lateral color aberration 808 in incident radiation beam 802.
  • Lateral color aberration 808 comprises an undesired change in a target characteristic of incident radiation beam 802.
  • the undesired change in the target characteristic of the incident radiation beam comprises a shift (see the doubled sided arrow indicated as part of lateral color aberration 808) of spot center on image plane 812, for different wavelengths within the incident radiation beam 802.
  • the darker and lighter colored arrows that make up incident radiation beam 802 may shift in color (from darker to lighter or lighter to darker) depending on the shift caused by optical element 800.
  • the undesired change comprises a change in trajectory of incident radiation beam 802 away from a target focal point.
  • metasurface(s) 804 are configured to adjust incident radiation beam 802 back to a target position or focal point 820 on image plane 812 (in this example). Here, this may reverse any shift in color of the darker and lighter arrows.
  • a metasurface can be located before the optics 800, depending on the application.
  • aberrations can be classified into monochromatic and chromatic categories. The former depends on the geometry of optics 800 and the incident beam 802 orientation and distribution with respect to it, while the latter is caused by dispersive properties of optics 800. Metasurfaces can help with correction of both types of aberrations.
  • detectors 604 and/or 610 are configured to generate a detection signal.
  • the detection signal may be generated based on detected reflected radiation from diffraction grating target(s) (e.g., metrology target 30).
  • detectors 604 and/or 610 comprise interferometers, cameras, single or multi-pixel photo-detectors, and/or other detectors.
  • detector 604 and/or 610 is configured to detect a diffraction order, phase, intensity, wavelength, and/or polarization of the diffracted radiation received from metrology target 30, and generate the detection signal based on the diffraction order, the phase, intensity, wavelength, and/or polarization.
  • detectors 604 and/or 610 may receive diffracted first or higher order radiation from metrology target 30, which diffracts the incident radiation beam before or after an optical element 675 or objective 690 causes the aberration and the one or metasurfaces 650 reverse the change in the target characteristic to correct the aberration.
  • Detectors 604 and/or 610 generate the detection signal based on received diffracted radiation.
  • the detection signal comprises measurement information pertaining to the target(s).
  • the detection signal may be, and/or be used to determine, an overlay and/or alignment metrology signal comprising overlay and/or alignment measurement information, and/or other metrology signals.
  • the measurement information may be determined using principles of interferometry and/or other principles.
  • Detectors 604 and/or 610 may form a portion of an overlay detection sensor and/or an alignment sensor, respectively, 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.
  • Fig. 10 illustrates a metrology method 1001.
  • method 1001 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 1001 may be implemented in or by a metrology system such as system 600 illustrated in Fig. 6 (and further illustrated in Fig. 7-9), system 10 illustrated in Fig. 3, a computer system (e.g., as illustrated in Fig. 11 and described below), and/or in or by other systems, for example.
  • a metrology system such as system 600 illustrated in Fig. 6 (and further illustrated in Fig. 7-9), system 10 illustrated in Fig. 3, a computer system (e.g., as illustrated in Fig. 11 and described below), and/or in or by other systems, for example.
  • method 1001 comprises generating (operation 1002) an incident radiation beam, receiving and transmitting (operation 1004) the incident radiation beam, reversing (operation 1006) a change in a target characteristic of the incident radiation beam to correct an aberration caused at operation 1004, generating (operation 1008) a detection signal, and/or other operations.
  • one or more portions of method 1001 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 1001 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 1001 (e.g., see discussion related to Fig. 11 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 source 2 shown in Fig. 3 and/or source 612 shown in Fig. 6, and described above.
  • an optical element of the metrology system receives and transmits the incident radiation beam.
  • the optical element comprises a lens, a beam splitter, a mirror, a refractive or diffractive optical component, and/or other optical elements.
  • the optical element causes an aberration in the incident radiation beam.
  • the aberration comprises an undesired change in a target characteristic of the incident radiation beam.
  • the aberration comprises a chromatic aberration, a spherical aberration, a coma aberration, and/or other aberrations.
  • the aberration may be a lateral color aberration.
  • the optical element may be similar to and/or the same as one or more optical elements of metrology system 600 shown in Fig. 6 and described above.
  • Corrected radiation may be used in an illumination branch of the metrology system to illuminate a metrology target on a patterned substrate and/or be used by a detector in a detection branch of the metrology system to generate a detection signal (e.g., a metrology signal), for example.
  • a detection signal e.g., a metrology signal
  • One or more metasurfaces are used for this reversal and aberration correction.
  • the one or more metasurfaces may be similar to and/or the same as one or more metasurfaces 650 shown in Fig. 6 (and also Fig. 7-9) and described above.
  • the one or more metasurfaces are configured to modify an amplitude, phase, polarization, and/or other characteristics of the incident radiation beam.
  • the one or more metasurfaces are positioned before the optical element along an optical path of the incident radiation beam.
  • the one or more metasurfaces are positioned after the optical element along an optical path of the incident radiation beam.
  • the one or more metasurfaces comprise an array of metasurfaces.
  • the array may be two dimensional (2D) and/or have other dimensionality.
  • Each metasurface comprises nano-antennas, meta-atoms, nano-particles, and/or other structures.
  • the one or more metasurfaces may be active or passive.
  • the one or more metasurfaces are configured to replace one or more refractive elements, diffractive elements, and/or a moving stage in the metrology system previously used for aberration correction.
  • the undesired change in the target characteristic of the incident radiation beam comprises a shift in the incident radiation beam due to a change in wavelength.
  • the one or more metasurfaces are configured to adjust the incident radiation beam back to a target position, which helps to eliminate needed mechanical movement of a stage of the metrology system.
  • the undesired change comprises a change in trajectory of the incident radiation beam away from a target focal point.
  • the one or more metasurfaces are configured to re-direct the incident radiation beam back toward the target focal point.
  • a detection signal may be generated.
  • the detection signal may be generated based on detected reflected radiation from diffraction grating target(s), as described above.
  • operation 1008 may include receiving diffracted first or higher order radiation from a metrology target, which diffracts the incident radiation beam before or after the optical element causes the aberration and the one or metasurfaces reverse the change in the target characteristic to correct the aberration, and generating the detection signal.
  • the detection signal is generated by a detector (such as detector 4 in Fig. 3, one or more of the detectors such as detectors 604 and/or 610 shown in Fig. 6 and described above, and/or other detectors) based on radiation received by the detector.
  • the detection signal comprises measurement information pertaining to the target(s).
  • the detection signal may be, and/or be used to determine, an overlay and/or alignment metrology 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
  • the measurement information may be determined using principles of interferometry and/or other principles.
  • method 1001 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.
  • 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 1001 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 1001), for example.
  • method 1001 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.
  • 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.
  • 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 CL
  • 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 non-volatile storage for later execution. In this manner, computer system CS may obtain application code in the form of a carrier wave.
  • a metrology system associated with semiconductor manufacturing comprising: an optical element configured to receive and transmit an incident radiation beam, the optical element causing an aberration in the incident radiation beam, the aberration comprising an undesired change in a target characteristic of the incident radiation beam; and one or more metasurfaces configured to reverse the change in the target characteristic to correct the aberration caused by the optical element.
  • each metasurface comprises nano-antennas, meta-atoms, or nano-particles.
  • a corrected radiation beam is configured to be used in an illumination branch of the metrology system to illuminate a metrology target on a patterned substrate and/or be used by a detector in a detection branch of the metrology system to generate a metrology detection signal.
  • the aberration comprises a chromatic aberration, a spherical aberration, and/or a coma aberration.
  • the undesired change comprises a change in trajectory of the incident radiation beam away from a target focal point; and wherein the one or more metasurfaces is configured to re-direct the incident radiation beam back toward the target focal point.
  • the one or more metasurfaces are positioned before the optical element along an optical path of the incident radiation beam.
  • a metrology method associated with semiconductor manufacturing comprising: receiving and transmitting, with an optical element, an incident radiation beam, the optical element causing an aberration in the incident radiation beam, the aberration comprising an undesired change in a target characteristic of the incident radiation beam; and reversing, with one or more metasurfaces, the change in the target characteristic to correct the aberration caused by the optical element.
  • the aberration comprises a chromatic aberration, a spherical aberration, and/or a coma aberration.
  • the optical element comprises a lens, a beam splitter, a mirror, and/or a refractive or diffractive optical component.
  • 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 des systèmes et des procédés de métrologie. Dans ces systèmes et procédés, une ou plusieurs métasurfaces sont utilisées pour corriger des aberrations provoquées par un ou plusieurs éléments optiques (par exemple, des lentilles, des séparateurs de faisceau, des miroirs, des composants optiques de réfraction ou de diffraction, etc.). Une métasurface (également appelée métalentille) est un réseau de surfaces planes 2D relativement mince de structures configurées pour modifier la trajectoire, l'amplitude, la phase, la polarisation et/ou d'autres caractéristiques d'un faisceau incident. La ou les métasurfaces sont configurées pour remplacer un ou plusieurs éléments de réfraction, éléments de diffraction et/ou un étage mobile, par exemple, utilisés précédemment pour la correction d'aberrations dans les systèmes de métrologie antérieurs. Ceci rend les présents systèmes de métrologie plus compacts, plus légers et moins coûteux que les systèmes antérieurs, entre autres avantages.
PCT/EP2024/075580 2023-10-12 2024-09-12 Correction d'aberration dans un système de métrologie Pending WO2025078101A1 (fr)

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