Optical vortex based metrology systems and methods

Abstract

Optical vortex based metrology systems and methods are described. A radiation source is configured to irradiate a metrology target in one or more layers of a patterned substrate with radiation. The metrology target is configured to diffract and impart orbital angular momentum to the radiation from the radiation source. A radiation sensor is configured to generate a metrology signal based on the orbital angular momentum of the diffracted radiation received from the metrology target. The metrology signal comprises alignment position information and / or overlay information for the one or more layers. Advantageously, orbital angular of momentum of diffracted radiation can carry additional information useful to generate more accurate measurement compared to existing metrology systems, where only phase or intensity information is used.

Description

OPTICAL VORTEX BASED METROLOGY SYSTEMS AND METHODSCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority of US application 63 / 539,035 which was filed on September 18, 2023 and which is incorporated herein in its entirety by reference.TECHNICAL FIELD

[0002] This description relates to optical vortex based metrology systems and methods.BACKGROUND

[0003] A lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A patterning device (e.g., a mask) may include or provide a pattern corresponding to an individual layer of the IC (“design layout”), and this pattern can be transferred onto a target portion (e.g. comprising one or more dies) on a substrate (e.g., silicon wafer) that has been coated with a layer of radiation-sensitive material (“resist”), by methods such as irradiating the target portion through the pattern on the patterning device. In general, 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. In one type of lithographic projection apparatus, 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. In an alternative apparatus, commonly referred to as a step-and-scan apparatus, 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. Since, in general, the lithographic projection apparatus will have a reduction ratio M (e.g., 4), the speed F at which the substrate is moved will be 1 / M times that at which the projection beam scans the patterning device.

[0004] 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. 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. If several layers are required in the device, then the whole procedure, or a variant thereof, is repeated for each layer. Eventually, 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 individualdevices can be mounted on a carrier, connected to pins, etc.

[0005] Thus, manufacturing devices, such as semiconductor devices, typically involves processing a substrate (e.g., a semiconductor wafer) using a number of fabrication processes to form various features and multiple layers of the devices. Such layers and features are typically manufactured and processed using, e.g., deposition, lithography, etch, deposition, chemical-mechanical polishing, and ion implantation. Multiple devices may be fabricated on a plurality of dies on a substrate and then separated into individual devices. 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.

[0006] 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.

[0007] As semiconductor manufacturing processes continue to advance, the dimensions of functional elements have continually been reduced while the number of functional elements, such as transistors, per device has been steadily increasing over decades, following a trend commonly referred to as “Moore’s law.” At the current state of technology, layers of devices are manufactured using lithographic projection apparatuses that project a design layout onto a substrate using illumination from a deep-ultraviolet illumination source, creating individual functional elements having dimensions well below 100 nm, i.e. less than half the wavelength of the radiation from the illumination source (e.g., a 193 nm illumination source).

[0008] This process in which features with dimensions smaller than the classical resolution limit of a lithographic projection apparatus are printed, is commonly known as low-ki lithography, according to the resolution formula CD = kjxk / NA, where I is the wavelength of radiation employed (currently in most cases 248nm or 193nm), NA is the numerical aperture of projection optics in the lithographic projection apparatus, CD is the “critical dimension’ -generally the smallest feature size printed-and ki is an empirical resolution factor. In general, the smaller ki the more difficult it becomes to reproduce a pattern on the substrate that resembles the shape and dimensions planned by a designer in order to achieve particular electrical functionality and performance. To overcome these difficulties, sophisticated fine-tuning steps are applied to the lithographic projection apparatus, the design layout, or the patterning device. These include, for example, but are not limited to, optimization of NA and optical coherence settings, customized illumination schemes, use of phase shifting patterning devices, optical proximity correction (OPC, sometimes also referred to as “optical and process correction”) inthe design layout, or other methods generally defined as “resolution enhancement techniques” (RET). Accurate metrology is important for these operations.SUMMARY

[0009] Optical vortex based metrology systems and methods are described. A radiation source is configured to irradiate a metrology target in one or more layers of a patterned substrate with radiation. The metrology target is configured to diffract and impart orbital angular momentum to the radiation from the radiation source. A radiation sensor is configured to generate a metrology signal based on the orbital angular momentum of the diffracted radiation received from the metrology target. The metrology signal comprises alignment position information and / or overlay information for the one or more layers. Advantageously, orbital angular of momentum of diffracted radiation can carry additional information useful to generate more accurate measurements compared to existing metrology systems, where only phase or intensity information associated with diffracted radiation is used.

[0010] According to an embodiment, a metrology system is provided. The metrology system comprises a radiation source configured to irradiate a metrology target in one or more layers of a patterned substrate with radiation. The metrology target is configured to diffract and impart orbital angular momentum to the radiation from the radiation source. The system comprises a radiation sensor configured to generate a metrology signal based on the orbital angular momentum of the diffracted radiation received from the metrology target. The metrology signal comprises alignment position information and / or overlay information for the one or more layers.

[0011] In some embodiments, the radiation from radiation source comprises a Gaussian radiation beam or a vortex radiation beam.

[0012] In some embodiments, diffracting and imparting the orbital angular momentum to the radiation from the radiation source forms a diffracted radiation beam with non-zero orbital angular momentum and / or having an optical vortex.

[0013] In some embodiments, the system comprises a vortex sorter configured to split the diffracted radiation with the orbital angular momentum into an even orbital angular momentum component and an odd orbital angular momentum component.

[0014] In some embodiments, the radiation sensor comprises a first sensor configured to detect an even orbital angular momentum component, and a second sensor configured to detect an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum. In some embodiments, the first and second sensors comprise first and second single pixel photo-detectors, or first and second cameras. In some embodiments, the first and second sensors comprise first and second interferometers.

[0015] In some embodiments, the system comprises the metrology target. The metrology target is configured to generate a singularity in a phase of a diffracted beam. The metrology target may comprisea grating having a fork shape or having a Vernier scale appearance, for example. In some embodiments, the metrology target comprises a first grating in a first portion of a layer of the patterned substrate and a second grating in a second adjacent portion of the patterned substrate. In some embodiments, the metrology target comprises a first grating in a first layer of the one or more layers of the patterned substrate and a second grating in a second layer of the one or more layers of the patterned substrate. These together may form the grating having the fork shape or the Vernier scale appearance.

[0016] In some embodiments, the metrology target comprises a fork shaped grating in a single layer of the patterned substrate. In some embodiments, the metrology target comprises a first fork shaped grating in the first layer of the one or more layers of the patterned substrate and a second fork shaped grating in the second layer of the one or more layers of the patterned substrate. The second fork shaped grating may be rotated approximately 90 degrees relative to the first fork shaped grating.

[0017] In some embodiments, the metrology signal is an alignment signal or an overlay signal.

[0018] In some embodiments, the radiation sensor is configured to detect a phase, intensity, wavelength, and / or polarization of the diffracted radiation received from the metrology target, along with the orbital angular momentum, and generate the metrology signal based on the orbital angular momentum and the phase, intensity, wavelength, and / or polarization.

[0019] In some embodiments, the system comprises one or more processors configured to determine alignment and / or overlay for the one or more layers based on the metrology signal. In some embodiments, the one or more processors are configured to filter and separate diagonal orders of the diffracted radiation from the metrology target with the orbital angular momentum with even optical vortexes, and non-diagonal orders with odd optical vortexes, or vice versa. In some embodiments, the one or more processors are configured to filter and separate to avoid cross-talk.

[0020] In some embodiments, the metrology target is different than structures adjacent to, proximate to, and / or surrounding the metrology target in the one or more layers which are not capable of generating a diffracted vortex beam.

[0021] In some embodiments, the alignment position information and / or overlay information for the one or more layers comprises an indication, in the metrology signal, of shape changes in a diffracted radiation vortex beam.

[0022] In some embodiments, the system comprises one or more optical splitter cubes, prisms, mirrors, and / or lenses configured to receive the diffracted radiation from the metrology target with the orbital angular momentum and direct received diffracted radiation with the orbital angular momentum toward the radiation sensor. In some embodiments, the one or more optical splitter cubes, prisms, mirrors, and / or lenses form a first pathway for an even orbital angular momentum component, and a second pathway for an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.

[0023] In some embodiments, the metrology signal is configured to be used by one or moreprocessors to adjust a semiconductor device manufacturing process.

[0024] According to another embodiment, there is provided a corresponding metrology method comprising one or more of the operations described above.BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The above aspects and other aspects and features will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments in conjunction with the accompanying figures.

[0026] Fig. 1 schematically depicts a lithography apparatus, according to an embodiment.

[0027] Fig. 2 schematically depicts an embodiment of a lithographic cell or cluster, according to an embodiment.

[0028] Fig. 3 schematically depicts an example inspection system, according to an embodiment.

[0029] Fig. 4 schematically depicts an example metrology technique, according to an embodiment.

[0030] Fig. 5 illustrates the relationship between a radiation illumination spot of an inspection system and a metrology target, according to an embodiment.

[0031] Fig. 6 illustrates a system configured to generate a metrology signal based on the orbital angular momentum of diffracted radiation received from a metrology target, according to an embodiment.

[0032] Fig. 7 illustrates examples of diffracted radiation with orbital angular momentum, according to an embodiment.

[0033] Fig. 8 illustrates several different example metrology target gratings (which show an increasingly defined fork shaped grating), and corresponding end view intensity patterns associated with different topological charges, m, for first order diffracted radiation with different angular momentums, according to an embodiment.

[0034] Fig. 9 illustrates examples of a Vernier scale appearance and a fork shape which may be used for a metrology target, according to an embodiment.

[0035] Fig. 10 illustrates an example vortex sorter configured to split diffracted radiation with orbital angular momentum into an even orbital angular momentum component and an odd orbital angular momentum component, according to an embodiment.

[0036] Fig. 11 illustrates how the intensity on two detectors changes as a radiation beam hits a fork shape grating, which diffracts the beam and imparts orbital angular momentum, according to an embodiment.

[0037] Fig. 12 illustrates an example a metrology target comprising a first grating in a first layer of one or more layers of a patterned substrate, and a second grating in a second layer of the one or more layers of the patterned substrate (rotated 90 degrees relative to each other in this example), which together may form a grating having a fork shape, and / or some other geometry, according to anembodiment.

[0038] Fig. 13 illustrates how diagonal diffraction orders change their vortex states from odd to even or even to odd when metrology target gratings are aligned versus not aligned, according to an embodiment.

[0039] Fig. 14 illustrates a metrology target, an intensity pattern for diffracted radiation having orbital angular momentum, and a corresponding pattern of topological charges, according to an embodiment.

[0040] Fig. 15 illustrates a metrology method, according to an embodiment.

[0041] Fig. 16 is a block diagram of an example computer system, according to an embodiment.DETAILED DESCRIPTION

[0042] In semiconductor device manufacturing, metrology operations typically include determining the position of a metrology mark (or marks) and / or other target in a layer of a semiconductor device structure. This position is typically determined by irradiating a metrology mark with radiation, and comparing characteristics of different diffraction orders of radiation reflected from the metrology mark. Such techniques are used to measure overlay, alignment, and / or other parameters.

[0043] An optical vortex based metrology system and / or method that utilizes diffracted radiation having orbital angular momentum is advantageous for many reasons. For example, orbital angular momentum of diffracted radiation can carry additional information (compared to the information carried by diffracted radiation in prior systems) useful to generate more accurate measurements compared to existing metrology systems, where only phase or intensity information is used. Diffracted radiation with orbital angular momentum has zero or close to zero sensitivity to structures that neighbor metrology marks in a patterned substrate. There is typically no (or very little) cross talk between diffraction orders if beams with different orbital angular momentum are separated. Orbital angular momentum is conserved with propagation through lenses, apertures, and / or other components of a metrology system. A phase map provides stable measurement of orbital angular momentum. Diffracted radiation with orbital angular momentum is less sensitive to noise, less sensitive to aberrations, and less sensitive to alignment issues compared to typical diffracted radiation. Diffracted radiation with orbital angular momentum also enables use of smaller metrology marks and / or enables overfilling of these marks. Diffracted radiation with orbital angular momentum also works with multiple metrology target pitches, multiple radiation wavelengths, and may use camera based and / or interferometry based detection techniques.

[0044] By way of a brief introduction, the description below relates to semiconductor device manufacturing and patterning processes. The following paragraphs also describe several components of systems and / or methods for semiconductor device metrology. These systems and methods may be used for measuring overlay, alignment, etc., in a semiconductor device manufacturing process, forexample, or for other operations.

[0045] Although specific reference may be made in this text to the measurement of overlay, alignment, or other parameters, and the manufacture of integrated circuits (ICs) for semiconductor devices, it should be understood that the description herein has many other possible applications. For example, it may be employed in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid-crystal display panels, thin-film magnetic heads, etc. The skilled artisan will appreciate that, in the context of such alternative applications, any use of the terms “reticle,” “wafer” or “die” in this text should be considered as interchangeable with the more general terms “mask,” “substrate” and “target portion,” respectively.

[0046] The term “projection optics” as used herein 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.

[0047] 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 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. As depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g. employing a programmable mirror array, or employing a reflective mask).

[0048] 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 radiationbeam 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.

[0049] 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.

[0050] The illuminator IL may comprise adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. Generally, 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. For example, 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. By adjusting the intensity distribution of the beam in the pupil plane of the illuminator, different illumination modes may be achieved. For example, by limiting the radial and angular extent of the intensity distribution in the pupil plane of the illuminator IL, 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.

[0051] 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. Alternatively, 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. For multi-pole illumination modes, 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. For example, for a dipole illumination mode, 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. For a quadrupole illumination mode, 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. Similarly, for a hexapole illumination mode 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.

[0052] In addition, 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. Thus, the illuminator provides a conditioned beam of radiation B, having a desired uniformity and intensity distribution in its cross section.

[0053] 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.”

[0054] The term “patterning device” should be broadly interpreted as referring to any device that can be used to impart a pattern in a target portion of the substrate. In an embodiment, a patterning device is any device that can be used to impart a radiation beam with a pattern in its cross-section to create a pattern in a target portion of the substrate. It should be noted that 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. Generally, 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.

[0055] 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.

[0056] The term “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.”

[0057] 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). To achieve this, 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. In general, it may not be possible to adjust the projection system PS to correct for apodization (transmission variation across the pupil plane). 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. Using a computational lithography technique, the patterning device MA may be designed to at least partially correct for apodization.

[0058] 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.). In such “multiple stage” machines, 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.

[0059] 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. An immersion liquid may also be applied to other spaces in thelithographic 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. The term “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.

[0060] In operation of the lithographic apparatus, a radiation beam B 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. Having traversed the patterning device MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and position sensor IF (e.g. an interferometric device, linear encoder, 2-D encoder or capacitive sensor), the substrate table WT can be moved accurately, e.g. to position different target portions C in the path of the radiation beam B. Similarly, the first positioner PM and another position sensor (which is not explicitly depicted in Fig. 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B, e.g. after mechanical retrieval from a mask library, or during a scan. In general, 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. Similarly, 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. In the case of a stepper (as opposed to a scanner), the support structure MT may be connected to a shortstroke 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. Although 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). Similarly, in situations in which more than one die is provided on the patterning device MA, the patterning device alignment marks may be located between the dies.

[0061] The depicted apparatus may be used in at least one of the following modes. In 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. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. In 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. In scan mode, the maximum size of theexposure 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. In another mode, 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. In this mode, generally 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.

[0062] Combinations and / or variations on the above-described modes of use or entirely different modes of use may also be employed.

[0063] 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.

[0064] The terms “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.

[0065] 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.

[0066] As shown in Fig. 2, 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. Conventionally 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 anddelivers them to the loading bay LB of the lithographic apparatus. These apparatuses, which are often collectively referred to as the track, are under the control of a track control unit TCU which is itself controlled by the supervisory control system SCS, which also controls the lithographic apparatus via lithography control unit LACU. Thus, the different apparatuses can be operated to maximize throughput and processing efficiency.

[0067] In order that 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), it is desirable to inspect a substrate or other object to measure or determine one or more properties such as alignment, 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, critical dimension (CD), focus offset, a material property, etc. Accordingly, 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)).

[0068] 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. 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.

[0069] There are various techniques for making measurements of the structures formed in the patterning process, including the use of a scanning electron microscope, an image -based measurement tool and / or various specialized tools. 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).

[0070] Thus, in a device fabrication process (e.g., a patterning process or a lithography process), 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 adjustmentsto 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. Examples of measurement include optical imaging (e.g., optical microscope), non-imaging optical measurement (e.g., measurement based on diffraction such as the ASML Orion, YieldStar, and / or SMASH metrology systems), mechanical measurement (e.g., profiling using a stylus, atomic force microscopy (AFM)), and / or non-optical imaging (e.g., scanning electron microscopy (SEM)).

[0071] 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.

[0072] 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.

[0073] To enable the metrology, often one or more targets are specifically provided on the substrate. Typically, the target is specially designed and may comprise a periodic structure. For example, 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. As another example, 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).

[0074] 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 4 such as a spectrometer detector 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, orby other operations.

[0075] As in the lithographic apparatus LA in Fig. 1 , one or more substrate tables (not shown in Fig. 3 or 4) 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. In an example where inspection system 10 is integrated with the lithographic apparatus, they may even be the same substrate table. 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. Typically, many measurements will be made on target portions of a structure at different locations across the substrate W. 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. Provided 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).

[0076] For typical metrology measurements, 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. Or 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.

[0077] 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., of bars, pillars, vias, etc.) is sensitive to changes in processing in the patterning process (e.g., optical aberration in the lithographic projection apparatus such as in the projection system, focus change, dose change, etc.) such that process variation manifests in variation in target 30. Accordingly, 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.

[0078] For example, the measured data from target 30 may indicate alignment and / or 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 asemiconductor device manufacturing apparatus based on the one or more determined semiconductor device manufacturing process parameters. In some embodiments, 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.

[0079] 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. 3. Typically, to obtain a diffraction spectrum that is free of interference from surrounding structures, 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, for example, by including a spot size selector in the illumination path, illumination may be provided from on axis and off axis directions.

[0080] Fig. 6 illustrates a system 600 configured to generate a metrology signal based on the orbital angular momentum of diffracted radiation received from a metrology target. Note that 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 diffracted radiation that has orbital angular momentum. Examples of such systems include ASML’s Orion 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). In some embodiments, one or more components of system 600 may replace, be used with, and / or otherwise augment one or more components of system 10. System 600 comprises a radiation source 612 (e.g., similar to and / or the same as source 2 shown in Fig. 3), sensor(s) 604 (e.g., similar to and / or the same as sensor 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, and / or other components (e.g., see the various unlabeled boxes in system 600). One or more processors PRO are operatively connected with sensor 604, and / or other components of system 600.

[0081] Fig. 6 illustrates an illumination branch 625 of system 600 including radiation source 612; a detection branch 660 including sensor(s) 604 and one or more processors PRO; an objective lens 690; and / or other components. In some embodiments, the components of system 600 form a portion of an alignment and / or overlay sensor configured to be used in a semiconductor manufacturing process.

[0082] Fig. 6 also illustrates a metrology target 30 which may comprise one or more metrologymarks, 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 with orbital angular momentum. One or more targets 30 may be included in a single layer of a substrate in a semiconductor device structure, for example, and / or in multiple (e.g., two) layers. In some embodiments, the feature comprises a geometric feature such as a ID or 2D feature, and / or other geometric features. By way of several non-limiting examples, the feature may comprise a grating, a line, an edge, a fine -pitched series of lines and / or edges, and / or other features. More information about metrology target 30 is described below.

[0083] Various lenses (example objective lens 690 is labeled in Fig. 6), reflectors, splitters, and other optical components are configured to receive, transmit, reflect, focus, and / or perform other operations on the illumination generated by illumination source 612, received by detection branch 660, and / or used by other portions of system 600. These various lenses, reflectors, splitters, and / or other optical components may comprise any type of lens, reflector, splitter, and / or other optical component configured to allow system 600 to function as described. For example, system 600 may include one or more splitters in detection branch 660 configured to split radiation between polarization and overlapping diffraction orders, and / or one or more splitters configured to split radiation with different orbital angular momentums, such that two phase and two orbital angular momentum channels are created for each polarization.

[0084] As another example, objective lens 690 may be 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. In some embodiments, 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. In some embodiments, 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.

[0085] In some embodiments, movement may be controlled electronically by a processor, such as processor PRO. Processor PRO may be included in a computing system CS (Fig. 16) and may operate based on computer or machine readable instructions (e.g., as described below related to Fig. 16).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.

[0086] In some embodiments, one or more actuators (not shown in Fig. 6) 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. As an example, 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.

[0087] The quantity of the various lenses, reflectors, and / or other optical components shown in Fig. 6 is not intended to be limiting. The principles described herein may be extended such that, in some embodiments system 600 comprises additional or fewer lenses, reflectors, and / or other optical components.

[0088] Radiation source 612 is configured to generate radiation. The radiation may comprise illumination such as light and / or other radiation. In some embodiments, the radiation from radiation source 612 comprises a Gaussian radiation beam, a vortex 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. In some embodiments, the radiation comprises light and / or other radiation. In some embodiments, the light comprises visible light, infrared light, near infrared light, and / or other light. In some embodiments, the radiation may be any radiation appropriate for interferometry.

[0089] Metrology target 30, in one or more layers of patterned substrate 602, is configured to be irradiated with the radiation. Metrology target 30 is configured to diffract and impart orbital angular momentum to the radiation. Diffracting and imparting the orbital angular momentum to the radiation forms a diffracted radiation beam with non-zero orbital angular momentum. The beam may have an optical vortex, for example. In some embodiments, metrology target 30, which is configured to diffract and impart the orbital angular momentum to the radiation from the radiation source, is different than structures adjacent to, proximate to, and / or surrounding the metrology target in the one or more layers, which are not capable of generating a diffracted vortex beam.

[0090] By way of a non-limiting example, Fig. 7 illustrates examples of diffracted radiation 700 withorbital angular momentum. Fig. 7 contrasts beam 702, which does not have orbital angular momentum (and so appears as a series of flat plates), with beams 704, 706, 708, and 710, which each have different amounts of orbital angular momentum. Since the total orbital angular momentum is conserved, the summation of orbital angular momentum for positive and negative diffraction orders adds up to the orbital angular momentum of the incident beam. Fig. 7 shows perspective views 711 and end views 712, along with an end view intensity pattern 714 for each beam. End view intensity patterns 715 show how beams 704, 706, 708, and 710 each have an optical vortex. For example, the dark circle at the center of each image indicates an optical vortex. The optical vortex may be considered a singularity. In an optical vortex, light is twisted like a corkscrew around its axis of travel. When projected onto a flat surface, an optical vortex looks like a ring of light, with a dark hole in the center (see end view intensity patterns and the phase patterns). The vortex is given a number, called the topological charge, m, according to how many twists the light does over one wavelength. The topological charge, m, is an integer, and can be positive or negative, depending on the direction of the twist. The higher the number of the twist, the faster the light is spinning around the axis. An m = 0 indicates a beam with no orbital angular momentum.

[0091] Fig. 8 illustrates several different example metrology target 30 gratings 800, 802, 804, 806, 808 (which show an increasingly defined fork shaped grating in a single layer of a substrate), and corresponding end view intensity patterns 810 associated with different topological charges, m, for first order diffracted radiation with different angular momentums. End view intensity patterns 810 vary with topological charge as shown, and also with diffraction order and / or other factors. Thus, end view intensity patterns 810 may be used for metrology (e.g., detecting and / or separate different diffraction orders, etc.)

[0092] Returning to Fig. 6, in some embodiments, metrology target 30 may comprise a grating having a fork shape (e.g., as shown in Fig. 8), a Vernier scale appearance, with two gratings having slightly different periods, and / or other geometries, for example. In some embodiments, metrology target 30 comprises a fork shaped grating in a single layer of a substrate; a first grating in a first portion of a layer of the patterned substrate and a second grating (having a slightly different period) in a second adjacent portion of the layer of the patterned substrate; or a first grating in a first layer of the one or more layers of the patterned substrate and a second grating in a second layer of the one or more layers of the patterned substrate; which together form the grating having the fork shape or the Vernier scale appearance. In some embodiments, target 30 comprises the grating having the fork shape in a single layer of the patterned substrate; or a first fork shaped grating in a first layer of the one or more layers of the patterned substrate and a second fork shaped grating in a second layer of the one or more layers of the patterned substrate, with the second fork shaped grating being rotated approximately 90 degrees relative to the first fork shaped grating.

[0093] Fig. 9 illustrates examples of a Vernier scale 900 appearance and a fork shape 902 (see dottedovals) which may be used for metrology target 30 (Fig. 6). Vernier scale 900 is shown in a top view in Fig. 9. In this example, Vernier scale 900 comprises a first grating 910 in a first portion 912 of a layer of a patterned substrate 602 and a second grating 916 in a second adjacent portion 918 of the layer of patterned substrate 602, which together form a grating having the Vernier scale 900 appearance. Gratings 910 and 916 have different periodicities relative to each other, which creates diffracted radiation with orbital angular momentum as described above.

[0094] Fork shape 902 grating 920 is shown in a top view in Fig. 9. A fork shape 902 grating 920 may be formed by a single grating in a single layer of a patterned substrate, and / or may be formed by different gratings in different layers that, when aligned, form a fork shape 902 grating 920 when viewed in the top view shown in Fig. 9. In some embodiments, the fork shape 902 grating 920 may be formed by two Vernier scale 900 gratings in two different layers that are shifted relative to each other, for example. The fork shape 902 grating 920 is configured such that, when an incident beam illuminates the fork shape 902 grating 920, the beam diffracted from the fork shape 902 grating 920 will have an optical vortex.

[0095] Returning to Fig. 6, sensor 604 (which may be separate sensors, or one in the same sensor even though they are drawn separately in Fig. 6) is configured to receive diffracted radiation from target 30 and generate a metrology signal. The metrology signal is generated based on the orbital angular momentum of the diffracted radiation received from metrology target 30 and / or other information. In some embodiments, radiation sensor 604 is configured to detect a phase, intensity, wavelength, and / or polarization of the diffracted radiation received from metrology target 30, along with the orbital angular momentum, and generate the metrology signal based on the orbital angular momentum and the phase, intensity, wavelength, and / or polarization.

[0096] In some embodiments, the metrology signal comprises measurement information pertaining to metrology target 30. For example, the metrology 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. In some embodiments, alignment position information and / or overlay information for the one or more layers included in the measurement information comprises an indication, in the metrology signal, of shape changes in a diffracted radiation vortex beam.

[0097] The metrology signal comprises an electronic signal that represents and / or otherwise corresponds to the radiation reflected from target 30. The metrology signal may indicate a metrology value associated with a diffraction grating, for example, and / or other information. Generating the metrology signal comprises sensing the diffracted radiation and converting the sensed diffracted radiation into the electronic signal. In some embodiments, generating the metrology signal comprises sensing different portions of the diffracted radiation from different areas and / or different geometries oftarget 30, and / or multiple targets, and combining the different portions of the reflected radiation to form the metrology signal. This may include generating and / or analyzing one or more images of a target 30, using the radiation described herein.

[0098] In some embodiments, system 600 is configured for receiving, with one or more optical splitter cubes, prisms, mirrors, and / or lenses, the diffracted radiation from metrology target 30 with the orbital angular momentum, and directing received diffracted radiation with the orbital angular momentum toward a radiation sensor (e.g., 604). For example, in some embodiments, system 600 comprises a vortex sorter, such as vortex sorter 1000 shown in Fig. 10. Sorter 1000 is shown in a top view 1003. In sorter 1000, diffracted radiation 1002 with the orbital angular momentum is split into an even orbital angular momentum component 1004 and an odd orbital angular momentum component 1006. Optical splitter cubes 1010 and 1012, prisms 1014 and 1016, mirrors 1018 and 1020, lenses, and / or other components form a first pathway 1024 for even orbital angular momentum component 1004, and a second pathway 1026 for odd orbital angular momentum component 1006, of diffracted radiation 1002 with the orbital angular momentum. In some embodiments, the radiation sensor (e.g., see Fig. 6 and the description above) comprises a first sensor 1050 configured to detect even orbital angular momentum component 1004, and a second sensor 1052 configured to detect odd orbital angular momentum component 1006, of diffracted radiation 1002 with the orbital angular momentum. In some embodiments, first and second sensors 1050 and 1052 comprise first and second single pixel photodetectors, first and second cameras, first and second interferometers, and / or other sensors.

[0099] Fig. 11 illustrates how the intensity on two detectors (e.g., sensors 1050 and 1052 shown in Fig. 10) changes as a radiation beam hits a fork shape grating (e.g., fork shape 902 grating 920 shown in Fig. 9), which diffracts the beam and imparts orbital angular momentum as described above. As shown in the progression of images 1100, 1102, and 1104, the intensity pattern 1110 of diffracted radiation changes from a single bright spot 1112 to a bright spot 1114 with an optical vortex 1116 at or near a center of bright spot 1114. This indicates that radiation diffracted from the fork shape grating has orbital angular momentum. An image similar to and / or the same as image 1104 may be analyzed to determine alignment, overlay, and / or other metrics, for example. In Fig. 11, the right hand side of images 1100, 1102, and 1104 show a detected image of an even orbital angular momentum arm and the left hand side of these images shows an odd orbital angular momentum arm. As a mark is scanned, a modulation signal on each arm is observed, but the envelope of each signal depends on which area of the mark is being illuminated. When at the center of the mark (the top and the bottom layer are on top of each other and there is no fork) most of the diffracted beam appears in the even arm (no orbital angular momentum) but as the mark scanned and movement is toward the middle of the mark where the top grating is in the middle of the bottom grating, most of the power is in the odd arm (vortex beam). The modulation signal is the alignment signal, and by using a fitting algorithm, the center of the mark can be defined. However, when there is a neighboring structure, the modulation signal is shifted a smallamount (depending on the relative position of the mark and the neighboring structure) which causes an alignment position deviation. But if orbital angular momentums are separated, the alignment signal is not sensitive to the neighboring structures.

[0100] Fig. 12 illustrates an example of metrology target 30 comprising different portions oriented at 90 degrees (in this example) to each other. In some embodiments, the different portions may be present in a single layer of a patterned substrate. In some embodiments, the different portions may comprise a first grating in a first layer of a patterned substrate (e.g., such as patterned substrate 602 shown in Fig. 6) and a second grating in a second layer of the patterned substrate, which together form a grating 1200 having a fork shape 1202. Such a grating may be used to measure overlay, for example, and / or determine other metrics. Similar gratings and / or a similar arrangement may be used to form the Vernier scale appearance described above, and / or some other geometry. In Fig. 12, the first and second fork shaped gratings are rotated approximately 90 degrees relative to each other, though the first fork shaped grating and the second fork shaped grating are difficult to separately distinguish because grating 1200 is shown in a top view. Fig. 12 is one possible example. Other amounts of rotation and / or other grating shapes and / or configurations that allow the present systems and methods to function as described are contemplated.

[0101] Rotating gratings (or portions of a grating) relative to each other as shown in Fig. 12 creates a pattern 1250 of topological charges, m (i.e., + / - 1, + / - 2, + / - 3, and + / - 4 in this example) in diffracted radiation. Pattern 1250 may be used to enhance alignment and / or overlay determinations, and / or may be used for other purposes. For example, pattern 1250 may be used separate orbital angular momentum information from other information in diffracted radiation, separate and / or otherwise sort (with sorter 1000 shown in Fig. 10 and described above) even and odd diffraction orders of the diffracted radiation (e.g., as indicated by corresponding even and odd topological charges), and / or may be used for other operations.

[0102] Fig. 13 shows an overlay application when two marks are on two different layers, but for alignment, a mark or marks are on the same layer, as shown in Fig. 14. For an alignment application, all diffraction orders hit the sensor - the ones with +1 and -1 orbital angular momentum orders are the ones that define the alignment position. However, the overlap of the other diffraction orders (diagonal terms / corners) with the desired signal causes error in defining alignment position. For an overlay sensor, if there is an overlay, the orbital angular momentum order changes for all orders (Fig. 13) depending if there is an overlay or not. One diffraction order or more may be used. By measuring the portion of light in different orbital angular momentum arms (as described above), the overlay can be defined.

[0103] Fig. 13 illustrates how diagonal diffraction orders - the center one in Fig. 13 is also undesirable signal but something to block it physically is often included in a metrology system - (in patterns 1300 and 1302) change their vortex states (e.g., m values) from odd to even or even to odd when gratings 1304 and 1306 are aligned 1310 versus not aligned 1320. In Fig. 13, grating 1304 is afirst grating in a first layer of a patterned substrate (e.g., such as patterned substrate 602 shown in Fig. 6) and grating 1306 is a second grating in a second layer of the patterned substrate, which together form a grating having a fork shape. In Fig. 13, the first and second fork shaped gratings 1304 and 1306 are rotated approximately 90 degrees relative to each other. Misalignment (e.g., see 1320) is caused by a shift 1330 of grating 1306, for example. Patterns 1300 and / or 1302, the change from one pattern to the other, and / or other associated data, may be used to enhance alignment and / or overlay determinations, and / or may be used for other purposes, as described above. For example, a change in a pattern may indicate a misalignment between layers (associated with shift 1330 in this example), a certain overlay value, etc.

[0104] In some embodiments, one or more processors (e.g., PRO shown in Fig. 3, 6, and 16, and described herein) are configured to filter and / or separate diagonal orders of the diffracted radiation from metrology target 30 (Fig. 6) with the orbital angular momentum with even optical vortexes, and nondiagonal orders with odd optical vortexes, or vice versa. Filtering and / or separating may be performed to avoid cross-talk, and / or for other purposes. For example, Fig. 14 illustrates a metrology target 30, an intensity pattern 1400 for diffracted radiation having orbital angular momentum, and a corresponding pattern 1402 of topological charges. Intensities (e.g., the shapes and shading of the various circular patterns) in intensity pattern 1400 vary with the corresponding topological charge. In this example, target 30 comprises a fork shape 1401 in vertical and horizontal directions. Target 30 diffracts radiation to create diagonal diffraction orders 1410 with even topological charges (i.e., even diffraction orders) and the non-diagonal orders 1420 with odd topological charges (i.e., odd diffraction orders). Sorter 1000 (Fig. 10) can be used as a filter to separate the diagonal and non-diagonal diffraction orders to avoid cross talk, and / or for other reasons. In this example, this is a 2D mark used to define the alignment position of the mark in both X and Y. The mark can be scanned horizontally, vertically, or diagonally. A modulation signal similar to a ID mark may be obtained, and by using a fitting algorithm, the center of the mark can be defined.

[0105] Fig. 15 illustrates a metrology method 1500. In some embodiments, method 1500 is performed as part of an overlay and / or alignment sensing operation in a semiconductor device manufacturing process, for example. In some embodiments, one or more operations of method 1500 may be implemented in or by system 600 illustrated in Fig. 6, system 10 illustrated in Fig. 3, a computer system (e.g., as illustrated in Fig. 16 and described below), and / or in or by other systems, for example. In some embodiments, method 1500 comprises irradiating (operation 1502) a metrology target with radiation so that the metrology target can diffract and impart orbital angular momentum to the radiation; generate (operation 1504) a metrology signal based on the orbital angular momentum; and determine (operation 1506) alignment and / or overlay based on the metrology signal. The operations of method 1500 are intended to be illustrative. In some embodiments, method 1500 may be accomplished with one or more additional operations not described, and / or without one or more of the operations discussed.For example, in some embodiments, method 1500 may include an additional operation comprising determining an adjustment for a semiconductor device manufacturing process. Additionally, the order in which the operations of method 1500 are illustrated in Fig. 15 and described herein is not intended to be limiting.

[0106] In some embodiments, one or more portions of method 1500 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 1500 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 1500 (e.g., see discussion related to Fig. 16 below).

[0107] At operation 1502, a metrology target in one or more layers of a patterned substrate is irradiated with radiation. Operation 1502 may include generating and directing, with the radiation source and one or more lenses, the radiation toward the metrology target. In some embodiments, the radiation from radiation source comprises a Gaussian radiation beam, a vortex radiation beam, and / or other radiation. The patterned substrate may be a semiconductor wafer, for example, and / or other substrates. In some embodiments, method 1500 is configured for a semiconductor wafer, and is used in a semiconductor manufacturing process.

[0108] The metrology target is configured to diffract and impart orbital angular momentum to the radiation. Diffracting and imparting the orbital angular momentum to the radiation forms a diffracted radiation beam with non-zero orbital angular momentum. The beam may have an optical vortex, for example. In some embodiments, the metrology target, which is configured to diffract and impart the orbital angular momentum to the radiation from the radiation source, is different than structures adjacent to, proximate to, and / or surrounding the metrology target in the one or more layers, which are not capable of generating a diffracted vortex beam.

[0109] In some embodiments, operation 1502 comprises generating, with the metrology target, a singularity in a phase of a diffracted beam. The metrology target may comprise a grating having a fork shape or having a Vernier scale appearance, for example. In some embodiments, the metrology target comprises a single grating in a single layer; first and second gratings in adjacent portions of a single layer; a first grating in a first layer of the one or more layers of the patterned substrate and a second grating in a second layer of the one or more layers of the patterned substrate; and / or other configurations which form the grating having the fork shape or the Vernier scale appearance. In some embodiments, the metrology target comprises a fork shaped grating in a single layer; a first fork shaped grating in the first layer of the one or more layers of the patterned substrate and a second fork shaped grating in thesecond layer of the one or more layers of the patterned substrate, with the second fork shaped grating being rotated approximately 90 degrees relative to the first fork shaped grating; and / or other configurations. In some embodiments, operation 1502 is performed by a radiation source the same as or similar to radiation source 2 shown in Fig. 3 and source 612 in Fig. 6, a metrology target such as target 30 shown in these same figures, and / or other components described above.

[0110] At operation 1504, a metrology signal is generated based on the orbital angular momentum of the diffracted radiation received from the metrology target and / or other information. In some embodiments, operation 1504 comprises receiving, with one or more optical splitter cubes, prisms, mirrors, and / or lenses, the diffracted radiation from the metrology target with the orbital angular momentum and directing received diffracted radiation with the orbital angular momentum toward a radiation sensor. In some embodiments, operation 1504 comprises splitting, with a vortex sorter, the diffracted radiation with the orbital angular momentum into an even orbital angular momentum component and an odd orbital angular momentum component. For example, the one or more optical splitter cubes, prisms, mirrors, and / or lenses may form a first pathway for an even orbital angular momentum component, and a second pathway for an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.

[0111] In some embodiments, the metrology signal comprises measurement information pertaining to the target(s). For example, the metrology 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. In some embodiments, alignment position information and / or overlay information for the one or more layers included in the measurement information comprises an indication, in the metrology signal, of shape changes in a diffracted radiation vortex beam.

[0112] The metrology signal comprises an electronic signal that represents and / or otherwise corresponds to the radiation reflected from the target(s). The metrology signal may indicate a metrology value associated with a diffraction grating target, for example, and / or other information. Generating the metrology signal comprises sensing the reflected radiation and converting the sensed reflected radiation into the electronic signal. In some embodiments, generating the metrology 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 metrology signal. This may include generating and / or analyzing one or more images of a target, using the radiation described herein.

[0113] Operation 1504 may be performed by a radiation sensor similar to and / or the same as detector 4, sensor 604, and / or processors PRO shown in Fig. 3, Fig. 6, and Fig. 16 (described below) and / or other components. In some embodiments, the radiation sensor comprises a first sensor configured todetect an even orbital angular momentum component, and a second sensor configured to detect an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum. In some embodiments, the first and second sensors comprise first and second single pixel photodetectors, first and second cameras, first and second interferometers, and / or other sensors.

[0114] In some embodiments, operation 1504 comprises detecting reflected radiation from one or more diffraction gratings that make up the metrology target. In some embodiments, operation 1504 may comprise detecting, with a radiation sensor, a phase, intensity, wavelength, and / or polarization of the diffracted radiation received from the metrology target, along with the orbital angular momentum, and generating the metrology signal based on the orbital angular momentum and the phase, intensity, wavelength, and / or polarization; based on the mark position (for alignment) and / or based on the overlay between the two layers on which the targets are located; and / or other information. In some embodiments, 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. For example, 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.

[0115] 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. For example, 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.

[0116] At operation 1506, alignment and / or overlay are determined for the one or more layers of the substrate based on the metrology signal and / or other information. In some embodiments, operation 1506 is performed by one or more processors the same as or similar to processor PRO shown in Fig. 3 and Fig. 6, and described above (along with processor PRO shown in Fig. 16 and described below). In some embodiments, the one or more processors are configured to filter and separate diagonal orders of diffracted radiation from the metrology target with the orbital angular momentum with even optical vortexes, and non-diagonal orders with odd optical vortexes, or vice versa. The one or more processors may be configured to filter and separate to avoid cross-talk, for example, and / or for other reasons.

[0117] In some embodiments, operation 1506 comprises determining an adjustment for asemiconductor device manufacturing process. In some embodiments, operation 1506 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 metrology 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. In some embodiments, 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.

[0118] In some embodiments, operation 1506 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.

[0119] For example, 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 operation 1506), for example. In some embodiments, operation 1506 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.

[0120] Fig. 16 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 toand / 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. A storage device SD, such as a magnetic disk or optical disk, is provided and coupled to bus BS for storing information and instructions.

[0121] 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. An input device ID, including alphanumeric and other keys, is coupled to bus BS for communicating information and command selections to processor PRO. Another type of user input device is 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.

[0122] In some embodiments, 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. One or more processors in a multi-processing arrangement may also be employed to execute the sequences of instructions contained in main memory MM. In some embodiments, 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.

[0123] The term “computer-readable medium” or “machine -readable medium” as used herein refers to any medium that participates in providing instructions to processor PRO for execution. Such a medium may take many forms, including but not limited to, non-volatile media, volatile media, and transmission media. 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. Computer-readable media can be non- transitory, for example, a floppy disk, a flexible disk, hard disk, magnetic tape, any other magneticmedium, 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.

[0124] 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. For example, 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.

[0125] 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. For example, 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. As another example, communication interface CI may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. Wireless links may also be implemented. In any such implementation, communication interface CI sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0126] Network link NDL typically provides data communication through one or more networks to other data devices. For example, 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. Local network LAN (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.

[0127] Computer system CS can send messages and receive data, including program code, through the network(s), network data link NDL, and communication interface CL In the Internet example, host computer HC might transmit a requested code for an application program through Internet INT, networkdata 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.

[0128] Various embodiments of the present systems and methods are disclosed in the subsequent list of numbered clauses. In the following, further features, characteristics, and exemplary technical solutions of the present disclosure will be described in terms of clauses that may be optionally claimed in any combination:1. A metrology system, comprising: a radiation source configured to irradiate a metrology target in one or more layers of a patterned substrate with radiation, the metrology target configured to diffract and impart orbital angular momentum to the radiation from the radiation source; and a radiation sensor configured to generate a metrology signal based on the orbital angular momentum of the diffracted radiation received from the metrology target, the metrology signal comprising alignment position information and / or overlay information for the one or more layers.2. The system of clause 1 , wherein the radiation from radiation source comprises a Gaussian radiation beam or a vortex radiation beam.3. The system of any of the previous clauses, wherein diffracting and imparting the orbital angular momentum to the radiation from the radiation source forms a diffracted radiation beam with non-zero orbital angular momentum and / or having an optical vortex.4. The system of any of the previous clauses, further comprising a vortex sorter configured to split the diffracted radiation with the orbital angular momentum into an even orbital angular momentum component and an odd orbital angular momentum component.5. The system of any of the previous clauses, wherein the radiation sensor comprises: a first sensor configured to detect an even orbital angular momentum component, and a second sensor configured to detect an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.6. The system of any of the previous clauses, wherein the first and second sensors comprise first and second single pixel photo-detectors, or first and second cameras.7. The system of any of the previous clauses, wherein the first and second sensors comprise first and second interferometers.8. The system of any of the previous clauses, further comprising the metrology target, the metrology target configured to generate a singularity in a phase of a diffracted beam, the metrology target comprising a grating having a fork shape or having a Vernier scale appearance.9. The system of any of the previous clauses, wherein the metrology target comprises a first grating in a first portion of a layer of the patterned substrate and a second grating in a second adjacent portion ofthe layer of the patterned substrate; or a first grating in a first layer of the one or more layers of the patterned substrate and a second grating in a second layer of the one or more layers of the patterned substrate, which together form the grating having the fork shape or the Vernier scale appearance.10. The system of any of the previous clauses, wherein the metrology target comprises: a target shape configured to create a singularity in a phase of a diffracted beam in a single layer of the patterned substrate; or a first target shape in a first layer of the one or more layers of the patterned substrate and a second target shape in a second layer of the one or more layers of the patterned substrate, the second target shape being rotated approximately 90 degrees relative to the first target shape.11. The system of any of the previous clauses, wherein the metrology signal is an alignment signal or an overlay signal.12. The system of any of the previous clauses, wherein the radiation sensor is further configured to detect a phase, intensity, wavelength, and / or polarization of the diffracted radiation received from the metrology target, along with the orbital angular momentum, and generate the metrology signal based on the orbital angular momentum and the phase, intensity, wavelength, and / or polarization.13. The system of any of the previous clauses, further comprising one or more processors configured to determine alignment and / or overlay for the one or more layers based on the metrology signal.14. The system of any of the previous clauses, wherein the one or more processors are further configured to filter and separate diagonal orders of the diffracted radiation from the metrology target with the orbital angular momentum with even optical vortexes, and non-diagonal orders with odd optical vortexes, or vice versa.15. The system of any of the previous clauses, wherein the one or more processors are configured to filter and separate to avoid cross-talk.16. The system of any of the previous clauses, wherein the metrology target configured to diffract and impart the orbital angular momentum to the radiation from the radiation source is different than structures adjacent to, proximate to, and / or surrounding the metrology target in the one or more layers which are not capable of generating a diffracted vortex beam.17. The system of any of the previous clauses, wherein the alignment position information and / or overlay information for the one or more layers comprises an indication, in the metrology signal, of shape changes in a diffracted radiation vortex beam.18. The system of any of the previous clauses, further comprising one or more optical splitter cubes, prisms, mirrors, and / or lenses configured to receive the diffracted radiation from the metrology target with the orbital angular momentum and direct received diffracted radiation with the orbital angular momentum toward the radiation sensor.19. The system of any of the previous clauses, wherein the one or more optical splitter cubes, prisms, mirrors, and / or lenses form a first pathway for an even orbital angular momentum component, and asecond pathway for an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.20. The system of any of the previous clauses, wherein the metrology signal is configured to be used by one or more processors to adjust a semiconductor device manufacturing process.21. A metrology method, comprising: irradiating, with a radiation source, a metrology target in one or more layers of a patterned substrate with radiation, the metrology target configured to diffract and impart orbital angular momentum to the radiation from the radiation source; and generating, with a radiation sensor, a metrology signal based on the orbital angular momentum of the diffracted radiation received from the metrology target, the metrology signal comprising alignment position information and / or overlay information for the one or more layers.22. The method of clause 21, wherein the radiation from radiation source comprises a Gaussian radiation beam or a vortex radiation beam.23. The method of any of the previous clauses, wherein diffracting and imparting the orbital angular momentum to the radiation from the radiation source forms a diffracted radiation beam with non-zero orbital angular momentum and / or having an optical vortex.24. The method of any of the previous clauses, further comprising splitting, with a vortex sorter, the diffracted radiation with the orbital angular momentum into an even orbital angular momentum component and an odd orbital angular momentum component.25. The method of any of the previous clauses, wherein the radiation sensor comprises: a first sensor configured to detect an even orbital angular momentum component, and a second sensor configured to detect an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.26. The method of any of the previous clauses, wherein the first and second sensors comprise first and second single pixel photo-detectors, or first and second cameras.27. The method of any of the previous clauses, wherein the first and second sensors comprise first and second interferometers.28. The method of any of the previous clauses, further comprising generating, with the metrology target, a singularity in a phase of a diffracted beam, the metrology target comprising a grating having a fork shape or having a Vernier scale appearance.29. The method of any of the previous clauses, wherein the metrology target comprises: a first grating in a first portion of a layer of the patterned substrate and a second grating in a second adjacent portion of the layer of the patterned substrate; or a first grating in a first layer of the one or more layers of the patterned substrate and a second grating in a second layer of the one or more layers of the patterned substrate, which together form the grating having the fork shape or the Vernier scale appearance.30. The method of any of the previous clauses, wherein the metrology target comprises: a target shape configured to create a singularity in a phase of a diffracted beam in a single layer of the patternedsubstrate; or a first target shape in a first layer of the one or more layers of the patterned substrate and a second target shape in a second layer of the one or more layers of the patterned substrate, the second target shape being rotated approximately 90 degrees relative to the first target shape.31. The method of any of the previous clauses, wherein the metrology signal is an alignment signal or an overlay signal.32. The method of any of the previous clauses, further comprising detecting, with the radiation sensor, a phase, intensity, wavelength, and / or polarization of the diffracted radiation received from the metrology target, along with the orbital angular momentum, and generating the metrology signal based on the orbital angular momentum and the phase, intensity, wavelength, and / or polarization.33. The method of any of the previous clauses, further comprising determining, with one or more processors, alignment and / or overlay for the one or more layers based on the metrology signal.34. The method of any of the previous clauses, wherein the one or more processors are further configured to filter and separate diagonal orders of the diffracted radiation from the metrology target with the orbital angular momentum with even optical vortexes, and non-diagonal orders with odd optical vortexes, or vice versa.35. The method of any of the previous clauses, wherein the one or more processors are configured to filter and separate to avoid cross-talk.36. The method of any of the previous clauses, wherein the metrology target configured to diffract and impart the orbital angular momentum to the radiation from the radiation source is different than structures adjacent to, proximate to, and / or surrounding the metrology target in the one or more layers which are not capable of generating a diffracted vortex beam.37. The method of any of the previous clauses, wherein the alignment position information and / or overlay information for the one or more layers comprises an indication, in the metrology signal, of shape changes in a diffracted radiation vortex beam.38. The method of any of the previous clauses, further comprising receiving, with one or more optical splitter cubes, prisms, mirrors, and / or lenses, the diffracted radiation from the metrology target with the orbital angular momentum and directing received diffracted radiation with the orbital angular momentum toward the radiation sensor.39. The method of any of the previous clauses, wherein the one or more optical splitter cubes, prisms, mirrors, and / or lenses form a first pathway for an even orbital angular momentum component, and a second pathway for an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.40. The method of any of the previous clauses, wherein the metrology signal is configured to be used by one or more processors to adjust a semiconductor device manufacturing process.

[0129] 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 technologiescapable 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. Moreover, 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.

[0130] While 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. In addition, the combination and sub-combinations of disclosed elements may comprise separate embodiments.

[0131] The descriptions above are intended to be illustrative, not limiting. Thus, it will be apparent to one skilled in the art that modifications may be made as described without departing from the scope of the claims set out below.

Claims

CLAIMS1. A metrology system, comprising: a radiation source configured to irradiate a metrology target in one or more layers of a patterned substrate with radiation, the metrology target configured to diffract and impart orbital angular momentum to the radiation from the radiation source; and a radiation sensor configured to generate a metrology signal based on the orbital angular momentum of the diffracted radiation received from the metrology target, the metrology signal comprising alignment position information and / or overlay information for the one or more layers.

2. The system of claim 1 , wherein the radiation from radiation source comprises a Gaussian radiation beam or a vortex radiation beam.

3. The system of claim 1 or 2, wherein diffracting and imparting the orbital angular momentum to the radiation from the radiation source forms a diffracted radiation beam with non-zero orbital angular momentum and / or having an optical vortex.

4. The system of any of claims 1-3, further comprising a vortex sorter configured to split the diffracted radiation with the orbital angular momentum into an even orbital angular momentum component and an odd orbital angular momentum component.

5. The system of any of claims 1-4, wherein the radiation sensor comprises: a first sensor configured to detect an even orbital angular momentum component, and a second sensor configured to detect an odd orbital angular momentum component, of the diffracted radiation with the orbital angular momentum.

6. The system of claim 5, wherein the first and second sensors comprise first and second single pixel photo-detectors, or first and second cameras.

7. The system of claim 5, wherein the first and second sensors comprise first and second interferometers.

8. The system of any of claims 1-7, further comprising the metrology target, the metrology target configured to generate a singularity in a phase of a diffracted beam, the metrology target comprising a grating having a fork shape or having a Vernier scale appearance.

9. The system of claim 8, wherein the metrology target comprises: a first grating in a first portion of a layer of the patterned substrate and a second grating in a second adjacent portion of the layer of the patterned substrate; or a first grating in a first layer of the one or more layers of the patterned substrate and a second grating in a second layer of the one or more layers of the patterned substrate, which together form the grating having the fork shape or the Vernier scale appearance.

10. The system of any of claims 1-9, wherein the metrology target comprises: a target shape configured to create a singularity in a phase of a diffracted beam in a single layer of the patterned substrate; or a first target shape in a first layer of the one or more layers of the patterned substrate and a second target shape in a second layer of the one or more layers of the patterned substrate, the second target shape being rotated approximately 90 degrees relative to the first target shape.

11. The system of any of claims 1-10, wherein the metrology signal is an alignment signal or an overlay signal.

12. The system of any of claims 1-11, wherein the radiation sensor is further configured to detect a phase, intensity, wavelength, and / or polarization of the diffracted radiation received from the metrology target, along with the orbital angular momentum, and generate the metrology signal based on the orbital angular momentum and the phase, intensity, wavelength, and / or polarization.

13. The system of any of claims 1-12, further comprising one or more processors configured to determine alignment and / or overlay for the one or more layers based on the metrology signal.

14. The system of claim 13, wherein the one or more processors are further configured to filter and separate diagonal orders of the diffracted radiation from the metrology target with the orbital angular momentum with even optical vortexes, and non-diagonal orders with odd optical vortexes, or vice versa.

15. The system of claim 14, wherein the one or more processors are configured to filter and separate to avoid cross-talk.

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