Dispersion engineered beam modifier for metrology systems

Abstract

A metrology system is described. Metasurfaces are used to replace (or enhance) existing objective lenses to focus radiation such as light, tune focal lengths, and / or correct aberrations in metrology systems. The metasurface is configured to receive a diffracted incident radiation beam from the radiation source, where the diffracted incident radiation beam has a known wavelength range, and is configured to transmit individual narrowband sub-beams of radiation having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation. The metasurface includes different sub-portions configured to transmit individual narrowband radiation sub-beams. The different sub-portions are configured for different non-overlapping radiation wavelength bandwidths within a known wavelength range.

Description

[0001] Cross - reference to related applications

[0002] This application claims priority to U.S. Application No. 63 / 431,377, filed Dec. 9, 2022, which is incorporated herein by reference in its entirety. Technical field

[0003] This description relates to a dispersion - engineered beam modifier for a metrology system. Background art

[0004] A lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A patterning device (e.g., a mask) can include or provide a pattern corresponding to the various layers of the IC (“design layout”), and by methods such as irradiating a target portion through the pattern on the patterning device, the pattern can be transferred onto a target portion (e.g., including one or more dies) on a substrate (e.g., a silicon wafer), which has been coated with a layer of radiation - sensitive material (“resist”). Generally, a single substrate includes a plurality of adjacent target portions, and the pattern is continuously transferred to the target portions by the lithographic projection apparatus, one target portion at a time. In one type of lithographic projection apparatus, the pattern over the entire patterning device is transferred onto one target portion in one operation. Such a device is generally referred to as a stepper. In an alternative device, generally referred to as a step - scan device, the projection beam is scanned over the patterning device in a given reference direction (“scan direction”), while the substrate is moved synchronously parallel or anti - parallel to this reference direction. Different portions of the pattern on the patterning device are gradually transferred onto one target portion.

[0005] Before transferring the pattern from the patterning device to the substrate, the substrate may undergo various processes, such as priming, resist coating, and soft baking. After exposure, the substrate can undergo other processes (“post - exposure processes”), such as post - exposure bake (PEB), development, hard baking, and measurement / inspection of the transferred pattern. This process array serves as a basis for manufacturing the various layers of a device (e.g., an IC). Then, the substrate can undergo various processes, such as etching, ion implantation (doping), metallization, oxidation, deposition, chemical - mechanical polishing, etc., all of which are intended to complete the various layers of the device. If several layers are required in the device, then the whole process or a variant thereof is repeated for each layer. Finally, the devices will be present in each target portion on the substrate. Then, these devices are separated from each other by techniques such as dicing or sawing, such that the individual devices can be mounted on a carrier, connected to pins, etc.

[0006] The manufacturing process of the device can be considered a patterning process. The patterning process involves patterning steps such as performing optical and / or nanoimprint lithography using a patterning device in a lithographic apparatus to transfer the pattern on the patterning device to a substrate, and typically but optionally involves one or more associated pattern processing steps such as resist development by a developing device, baking of the substrate using a baking tool, etching using a pattern by an etching device, deposition, etc.

[0007] Lithography is a core step in the manufacture of devices such as ICs, where the patterns formed on a substrate define the functional elements of the device, such as microprocessors, memory chips, etc. Similar lithography techniques are also used in the formation of flat panel displays, microelectromechanical systems (MEMS), and other devices.

[0008] With the continuous progress of semiconductor manufacturing processes, the sizes of functional elements have been continuously decreasing, while the number of functional elements (such as transistors) per device has been steadily increasing over the decades, following a trend commonly known as "Moore's Law". At the current state of the art, the layers of a device are manufactured using a lithographic projection apparatus that uses irradiation from a deep ultraviolet irradiation source to project a design layout onto a substrate, thereby creating individual functional elements with sizes far below 100 nm (i.e., less than half of the radiation wavelength from the irradiation source (e.g., a 193 nm irradiation source)).

[0009] According to the resolution formula CD = k1×λ / NA, the process of printing features with sizes smaller than the classical resolution limit of a lithographic projection apparatus is generally referred to as low k1 lithography, where λ is the wavelength of the radiation employed (currently mostly 248 nm or 193 nm), NA is the numerical aperture of the projection optics in the lithographic projection apparatus, CD is the "critical dimension", typically the smallest feature size printed, and k1 is an empirical resolution factor. Generally, the smaller k1 is, the more difficult it is to reproduce on the substrate a pattern similar in shape and size to that planned by the designer to achieve specific electrical functionality and performance. To overcome these difficulties, complex fine-tuning steps are applied to the lithographic projection apparatus, the design layout, or the patterning device. For example, these include but are not limited to optimization of the NA and optical coherence settings, customized irradiation schemes, use of phase-shifting patterning devices, optical proximity correction (OPC, sometimes also referred to as "optical and process correction") in the design layout, or other methods generally defined as "resolution enhancement techniques" (RET). Summary of the Invention

[0010] A measurement system is described. A beam modifier, such as a metasurface, is used to replace (or enhance) an existing objective lens to focus radiation such as light, tune the focal length, and / or correct aberrations in the measurement system. The beam modifier (e.g., a metasurface) is configured to receive a diffracted incident radiation beam from a radiation source (the diffracted incident radiation beam having a known wavelength range), and transmit a separate, narrower-band radiation sub-beam having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation. The beam modifier (e.g., a metasurface) includes different sub-parts that are configured to transmit separate, narrower-band radiation sub-beams. The different sub-parts are configured for different non-overlapping radiation wavelength bandwidths within the known wavelength range.

[0011] According to an embodiment, a beam modifier is provided. The beam modifier is configured to receive a diffracted incident radiation beam from a radiation source. The diffracted incident radiation beam has a known wavelength range. The beam modifier is configured to transmit a separate, narrower-band radiation sub-beam having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam. The beam modifier includes different sub-parts that are configured to transmit separate, narrower-band radiation sub-beams. The different sub-parts are configured for different non-overlapping radiation wavelength bandwidths within the known wavelength range.

[0012] In some embodiments, the beam modifier is a metasurface, and the metasurface includes nanoantennas, meta-atoms, scatterers, and / or nanoparticles.

[0013] In some embodiments, the separate, narrower-band radiation sub-beams include non-overlapping radiation sub-beams with a locally narrowed bandwidth having a modified amplitude, phase, and / or polarization. Each sub-part can be associated with a different set of color wavelengths and has a wavelength bandwidth for the associated color.

[0014] In some embodiments, the different sub-parts include adjacent local regions of a single monolithic metasurface formed by nanoantennas, meta-atoms, scatterers, and / or nanoparticles configured for specific non-overlapping radiation wavelength bandwidths.

[0015] In some embodiments, the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include blocks of material having a height, width, length, and / or rotation angle configured for specific non-overlapping radiation wavelength bandwidths.

[0016] In some embodiments, the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include freeform shapes configured for specific non-overlapping radiation wavelength bandwidths.

[0017] In some embodiments, the different sub-parts are configured to focus the transmitted radiation of a specific color onto a target at a target location for that color.

[0018] In some embodiments, different sub - portions are configured to collimate transmitted radiation of a specific color to form a collimated radiation beam of that color.

[0019] In some embodiments, different sub - portions are configured to disperse transmitted radiation of a specific color toward a target and target location of that color.

[0020] In some embodiments, the beam modifier includes a two - dimensional (2D) array of adjacent sub - portions.

[0021] In some embodiments, the non - overlapping radiation wavelength bandwidth is fixed and is determined based on the pitch of the grating that generates the diffracted incident radiation beam, the grating height, the wavelength, and / or the distance between the grating and the beam modifier.

[0022] In some embodiments, the distance between the grating and the beam modifier is configured to be adjusted based on the grating pitch and / or different operating wavelengths, where the different operating wavelengths correspond to different sets of color wavelengths associated with different sub - portions.

[0023] In some embodiments, adjusting the distance between the grating and the beam modifier changes the angle of incidence of the diffracted incident radiation beam on the beam modifier.

[0024] In some embodiments, the beam modifier includes a first metasurface and a second metasurface spaced apart from the first metasurface along the optical path.

[0025] In some embodiments, the spacing between the second metasurface and the first metasurface controls the focal length, corrects defocus, and / or corrects the wavefront aberration of the narrow - band radiation sub - beams of different colors transmitted by the sub - portions.

[0026] In some embodiments, a mechanical system is configured to adjust the spacing.

[0027] In some embodiments, the beam modifier focuses the diffracted incident radiation beam, collimates the diffracted incident radiation beam, or divides the diffracted incident radiation beam into a series of non - overlapping radiation bands, with each non - overlapping radiation band being focused at a different spot on the target.

[0028] According to another embodiment, a metrology system is provided. The metrology system includes: a radiation source configured to generate an incident radiation beam; a diffractive body configured to diffract the incident radiation beam; and a beam modifier. The beam modifier is configured to receive the diffracted incident radiation beam from the radiation source and the diffractive body. The diffracted incident radiation beam has a known wavelength range. The beam modifier is configured to transmit separate, narrower-band radiation sub-beams having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam. The beam modifier includes different sub-parts configured to transmit separate narrow-band radiation sub-beams. The different sub-parts are configured for different non-overlapping radiation wavelength bandwidths within the known wavelength range. The diffracted incident radiation beam received by the beam modifier is spatially separated by color into different wavelength groups and directed to color-corresponding sub-parts in the different sub-parts.

[0029] In some embodiments, the diffractive body includes a grating. The diffracted incident radiation beam received by the beam modifier is spatially separated by color into different wavelength groups and directed by the grating to color-corresponding sub-parts in the different sub-parts. The non-overlapping radiation wavelength bandwidth requirement is a function of the grating pitch.

[0030] In some embodiments, the metrology system further includes a detector configured to receive reflected radiation after reflection from a target and generate a detection signal. The reflected radiation includes separate, narrower-band radiation sub-beams after reflection from the target.

[0031] In some embodiments, the metrology system forms part of an alignment sensor and / or an overlay detection sensor. The alignment sensor and / or the overlay detection sensor is configured for semiconductor wafers and is used in semiconductor manufacturing processes.

[0032] According to another embodiment, a metrology method is provided. The method includes one or more of the above operations performed by the beam modifier and / or the metrology system. Description of the Drawings

[0033] The above aspects as well as other aspects and features will become apparent to those of ordinary skill in the art when reading the following detailed description in conjunction with the accompanying drawings.

[0034] Figure 1 A lithographic apparatus according to an embodiment is schematically depicted.

[0035] Figure 2 An embodiment of a lithography cell or cluster according to an embodiment is schematically depicted.

[0036] Figure 3 An example inspection system according to an embodiment is schematically depicted.

[0037] Figure 4 An example metrology technique according to an embodiment is schematically depicted.

[0038] Figure 5 Illustrates the relationship between a metrology target and the radiation illumination spot of an inspection system according to an embodiment.

[0039] Figure 6 Illustrates a beam modifier (e.g., metasurface) according to an embodiment.

[0040] Figure 7 Schematically illustrates the separation of an incident radiation beam into wavelength bands according to an embodiment.

[0041] Figure 8 Illustrates a graph of the local metasurface sub - portion bandwidth wavelength range Δλ as a function of height h according to an embodiment (see Figure 6 - the distance between the diffractive body and the beam modifier).

[0042] Figure 9 Illustrates a beam modifier (e.g., metasurface) double peak according to an embodiment.

[0043] Figure 10 Illustrates a beam modifier (e.g., metasurface) according to an embodiment, which is configured to divide a diffracted incident radiation beam into a series of non - overlapping radiation wavelength bands, each non - overlapping radiation wavelength band being focused at different spots on a target, on a detector, and / or at another location.

[0044] Figure 11 Illustrates a metrology method according to an embodiment.

[0045] Figure 12 Is a block diagram of an example computer system according to an embodiment. Detailed Description

[0046] In semiconductor device manufacturing, metrology operations typically include determining the location of metrology marks (or a plurality of marks) and / or other targets in a layer of a semiconductor device structure. This location is typically determined by irradiating the metrology marks with radiation and comparing the characteristics of different diffracted - order radiations reflected from the metrology marks. This technique is used to measure overlay, alignment, and / or other parameters. Existing metrology systems use bulky multi - element objective lenses to emit radiation onto a target, such as a metrology mark, and reflect the diffracted radiation from the metrology mark to a detector. These objective lenses increase the cost and size of a typical metrology system, cannot avoid chromatic aberration, and cannot correct all radiation beam aberrations.

[0047] The use of metasurfaces to replace or enhance bulky objective lenses in metrology systems or to modify the incident radiation beam of integrated optical alignment sensors is described in U.S. Provisional Patent Application No. 63 / 420,208, filed Oct. 28, 2022, entitled “Compact Optical Arrangement for Metrology Systems” and U.S. Provisional Patent Application No. 63 / 415,246, both of which are incorporated herein by reference in their entirety. Beam modifiers such as metasurfaces (also referred to as metalenses or flat lenses) are used to replace (or enhance) existing objective lenses to focus radiation, tune the focal length, and / or correct aberrations in metrology systems, thereby enhancing metrology system sensitivity. The metrology system is also more compact, lighter, and less expensive than existing systems. Using the features described below, metrology and / or other systems that utilize beam modifiers such as metasurfaces are not limited to any specific grating pitch or to a specific discrete set of wavelengths with a limited bandwidth.

[0048] A beam modifier that includes a metasurface having square cross-section nanocolumns, columns with holes therein, circular columns with rectangular holes therein, or any other combination of column and / or hole shapes can achieve efficient transmission and normal and anomalous dispersion of visible or infrared radiation by varying the size of the (nano)columns. Metasurfaces are inherently narrowband, but can be configured for a wider range of radiation wavelengths to achieve an achromatic metasurface over a 60 to 200 nm bandwidth. However, designing a metasurface with a high numerical aperture but relatively thin and that covers the entire range of the available radiation spectrum (e.g., far exceeding 60 to 200 nm) is a challenge.

[0049] Advantageously, for many metrology systems, the characteristics of the incident beam and the diffracted radiation beam are known. For example, the beam waist at focus, the diffraction angle, and the beam profile as a function of grating pitch can be known. By considering the known characteristics of the radiation beam and considering various aspects of metasurface design, the beam modifiers (e.g., metasurfaces) described below are configured to operate over the entire operating wavelength range of a typical metrology system and are adjustable to focus the radiation beam diffracted by a grating with any pitch. For example, the beam modifiers described below can be broadband metasurfaces (e.g., configured as a whole for polychromatic light) that are locally narrowband (e.g., having different sub-parts configured to transmit separate, narrower-band radiation sub-beams (monochromatic or grayscale in this example)).

[0050] By way of brief introduction, the following description relates to semiconductor device fabrication and patterning processes. The following paragraphs also describe several components of systems and / or methods for semiconductor device metrology. These systems and methods can be used to measure, for example, overlay, alignment, etc. during semiconductor device fabrication or for other operations.

[0051] Although specific mention may be made in this text of the measurement of overlay, alignment or other parameters and of the manufacture of integrated circuits (ICs) in semiconductor devices, it should be understood that the description herein has many other applications. For example, it may be used in the manufacture of integrated optical systems, for guiding and detecting patterns in magnetic domain memories, display panels, thin film magnetic heads, etc. Those skilled in the art will appreciate that, in the context of such alternative applications, any use of the terms "reticle", "wafer" or "die" herein should be considered to be interchangeable with the more general terms "mask", "substrate" and "target portion" respectively.

[0052] The term "projection optics" as used herein should be interpreted broadly to encompass various types of optical systems, such as including refractive optics, reflective optics, apertures and catadioptric optics. The term "projection optics" may also include components operating according to any of these design types to jointly or separately direct, shape or control a projection radiation beam. The term "projection optics" may include any optical component in a lithographic projection apparatus, regardless of where the optical component is located in the optical path of the lithographic projection apparatus. The projection optics may include optical components for shaping, conditioning and / or projecting radiation from a source before the radiation passes through the patterning device and / or for shaping, conditioning and / or projecting the radiation after the radiation passes through the patterning device. The projection optics generally do not include the source and the patterning device.

[0053] Figure 1 An embodiment of a lithographic apparatus LA is schematically depicted. The apparatus includes: 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 according to 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 according to 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 the patterning device MA onto a target portion C (e.g., including one or more dies and commonly referred to as a field) of the substrate W. The projection system is supported on a reference frame RF. As depicted, the apparatus is of the transmissive type (e.g., using a transmissive mask). Alternatively, the apparatus may be of the reflective type (e.g., using a programmable mirror array or using a reflective mask).

[0054] The illuminator IL receives a radiation beam 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 a case, the source is not regarded as part of the lithographic apparatus, and the radiation beam is transferred from the source SO to the illuminator IL by means of a beam delivery system BD including, for example, suitable directing mirrors and / or beam expanders. 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, the illuminator IL and, if required, the beam delivery system BD may be referred to as the radiation system.

[0055] The illuminator IL can change 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 the 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 number of equally spaced sectors in the pupil plane. The intensity distribution of the radiation beam in the pupil plane of the illuminator IL may be referred to as the illumination mode.

[0056] The illuminator IL may include a regulator AD configured to adjust the (angular / spatial) intensity distribution of the beam. In general, at least the outer and / or inner radial extent (commonly referred to as σ outer and σ inner respectively) of the intensity distribution in the pupil plane of the illuminator may be adjusted. The illuminator IL may be operable to change the angular distribution of the beam. For example, the illuminator may be operable to change the number and angular extent of the sectors in the pupil plane in which 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 multipole distribution, such as for example a dipole, quadrupole or hexapole distribution. For example, a desired illumination mode may be obtained by inserting the optics providing that illumination mode into the illuminator IL or using a spatial light modulator.

[0057] The illuminator IL can be operable to change the polarization of the beam and can be operable to adjust the polarization using the adjuster AD. The polarization state of the radiation beam on the pupil plane of the illuminator IL can be referred to as the polarization pattern. Using different polarization patterns can allow for greater contrast to be achieved in the image formed on the substrate W. The radiation beam can be unpolarized. Alternatively, the illuminator can be arranged to produce a linearly polarized radiation beam. The polarization direction of the radiation beam can vary on the pupil plane of the illuminator IL. In different regions in the pupil plane of the illuminator IL, the polarization direction of the radiation may be different. The polarization state of the radiation can be selected according to the illumination mode. For a multipole illumination mode, the polarization of each pole of the radiation beam can generally be 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 can be linearly polarized in a direction substantially perpendicular to the line bisecting the two opposite sectors of the dipole. The radiation beam can be polarized in one of two different orthogonal directions, which can be referred to as the X polarization state and the Y polarization state. For a quadrupole illumination mode, the radiation in each sector of each pole can be linearly polarized in a direction substantially perpendicular to the line bisecting that sector. This polarization pattern can be referred to as XY polarization. Similarly, for a hexapole illumination mode, the radiation in each sector of each pole can be linearly polarized in a direction substantially perpendicular to the line bisecting that sector. This polarization pattern can be referred to as TE polarization.

[0058] In addition, the illuminator IL generally includes various other components, such as the integrator IN and the condenser CO. The illumination system can 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 the radiation. Thus, the illuminator provides a conditioned radiation beam B having a desired uniformity and intensity distribution in its cross-section.

[0059] 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 the patterning device is held in a vacuum environment. The support structure can hold the patterning device using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure can be a frame or a table, for example, which can be fixed or movable as required. The support structure can ensure that the patterning device is located at a desired position relative to the projection system, for example. Any use of the terms "reticle" or "mask" in this document can be considered synonymous with the more general term "patterning device".

[0060] The term "pattern formation device" as used herein should be construed broadly to mean any device that can be used to impart a pattern in a target portion of a substrate. In an embodiment, a pattern formation device is any device that can be used to impart a pattern to a radiation beam in its cross-section to create a pattern in a target portion of a 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 (such as an integrated circuit) created in the target portion of the device.

[0061] The pattern formation device can be transmissive or reflective. Examples of pattern formation devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography and include mask types such as binary mask types, alternating phase-shift mask types, and attenuated phase-shift mask types, 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 so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam reflected by the mirror matrix.

[0062] The term "projection system" should be construed broadly to cover 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 can be considered synonymous with the more general term "projection system".

[0063] The projection system PS may include a plurality of optical (e.g., lens) elements and may also include an adjustment mechanism configured to adjust one or more of the optical elements in order to correct for aberrations (phase variations across the pupil plane over the entire field). To achieve this, the adjustment mechanism may be operable to manipulate one or more of the optical (e.g., lens) elements within the projection system PS in one or more different ways. The projection system may have a coordinate system in which the optical axis of the projection system extends in the z-direction. The adjustment mechanism may be operable to effect any combination of the following: displacing one or more of the optical elements; tilting one or more of the optical elements; and / or deforming one or more of the optical elements. The displacement of the optical element may be in any direction (x, y, z, or a combination thereof). Although rotation about the z-axis may be used for non-rotationally symmetric aspherical optical elements, the tilting of the optical element is generally out of the plane perpendicular to the optical axis by rotation about an axis in the x and / or y directions. The deformation of the optical element may include a low-frequency shape (e.g., astigmatism) and / or a high-frequency shape (e.g., freeform aspheric). The deformation of the optical element may be performed, for example, by applying a force on one or more sides of the optical element using one or more actuators and / or by heating one or more selected regions of the optical element using one or more heating elements. In general, it may not be possible to adjust the projection system PS to correct for apodization (transmission variation in the pupil plane). When designing a patterning device (e.g., a mask) MA for a lithographic apparatus LA, the transmission map of the projection system PS may be used. Using computational lithography techniques, the patterning device MA may be designed to at least partially correct for apodization.

[0064] The lithographic apparatus may be of the type having two (dual stage) or more stages (e.g., two or more substrate stages WTa, WTb, two or more patterning device stages, a substrate stage WTa and a stage WTb located below the projection system without a substrate dedicated for, e.g., facilitating measurement and / or cleaning, etc.). In such a “multi-stage” machine, the additional stages may be used in parallel, or preparatory steps may be performed on one or more of the stages while one or more other stages are being used for exposure. For example, alignment measurements using an alignment sensor AS and / or leveling (height, tilt, etc.) measurements using a leveling sensor LS may be carried out.

[0065] A lithographic apparatus may also be of a type in which at least a portion of the substrate is covered by a liquid having a relatively high refractive index (e.g., water) to fill the space between the projection system and the substrate. The immersion liquid may also be applied to other spaces in the lithographic apparatus, such as the space between the patterning device and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of the projection system. The term "immersion" as used herein does not mean that structures such as the substrate must be submerged in the liquid; rather, immersion only means that the liquid is located between the projection system and the substrate during exposure.

[0066] In operation of the lithographic apparatus, a radiation beam is conditioned and supplied by an illumination system IL. The radiation beam B is incident on a patterning device (e.g., a mask) MA, which is patterned by the patterning device MA held on a support structure (e.g., a mask table) MT. After traversing the patterning device MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of a substrate W. By means of a second positioner PW and a position sensor IF (e.g., an interferometric device, a linear encoder, a 2D encoder, or a capacitive sensor), the substrate table WT can be accurately moved, e.g., to position different target portions C in the path of the radiation beam B. Similarly, e.g., after mechanically retrieving from a mask library or during scanning, a first positioner PM and another position sensor (not explicitly depicted in Figure 1 can be used to accurately position the patterning device MA relative to the path of the radiation beam B. Generally, the movement of the support structure MT can be realized by means of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming part of the first positioner PM. Similarly, the movement of the substrate table WT can be realized using a long-stroke module and a short-stroke module forming part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure MT may be connected only to a short-stroke actuator or may be fixed. The patterning device MA and the substrate W can be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks occupy dedicated target portions, they may be located in the space between the target portions (these are called scribe alignment marks). Similarly, in the case where more than one die is provided on the patterning device MA, the patterning device alignment marks may be located between the dies.

[0067] The apparatus depicted can be used in at least one of the following modes. In the step mode, when the pattern imparted to the radiation beam is projected onto the target portion C once (i.e., single static exposure), the support structure MT and the substrate table WT remain substantially stationary. Then, the substrate table WT is displaced in the X and / or Y directions such that different target portions C can be exposed. In the step mode, the maximum size of the exposure field is limited to the size of the target portion C imaged in a single static exposure. In the scan mode, when the pattern imparted to the radiation beam is projected onto the target portion C (i.e., single dynamic exposure), the support structure MT and the substrate table WT are scanned synchronously. The speed and direction of the substrate table WT relative to the support structure MT can be determined by the (reduction) magnification and image inversion characteristics of the projection system PS. In the scan mode, the maximum size of the exposure field is limited to the width of the target portion (in the non-scanning direction) in a single dynamic exposure, while the length of the scanning motion determines the height of the target portion (in the scanning direction). In another mode, while the pattern imparted to the radiation beam is projected onto the target portion C, the support structure MT remains substantially stationary, thus holding the programmable patterning device, and the substrate table WT is moved or scanned. In this mode, typically a pulsed radiation source is employed, and the programmable patterning device is updated as needed after each movement of the substrate table WT or between successive radiation pulses during scanning. This mode of operation can be readily applied to maskless lithography, which utilizes a programmable patterning device (such as a programmable mirror array of the type mentioned above).

[0068] Combinations and / or variations of the above-described usage modes or entirely different usage modes can also be employed.

[0069] The substrate can be processed before or after exposure, for example in a track (a tool typically used to apply a resist layer to the substrate and develop the exposed resist) or a metrology or inspection tool. Where applicable, the present disclosure herein can be applied to such and other substrate processing tools. Further, the substrate can be processed more than once, for example to create a multi-layer IC, such that the term substrate as used herein can also refer to a substrate that already includes multiple processed layers.

[0070] The terms "radiation" and "beam" as used herein with respect to lithography encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., wavelengths of 365, 248, 193, 157, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., wavelengths in the range of 5 to 20 nm) as well as particle beams, such as ion beams or electron beams.

[0071] Various patterns on or provided by a patterning device may have different process windows, i.e., a space of process variables under which the patterns will be produced within specifications. Examples of pattern specifications related to potential system defects include checking for necking, line pullback, line thinning, CD, edge placement, overlay, anti-top loss, anti-etch bias, and / or bridging. The process window of a pattern or a region thereof on the patterning device can be obtained by combining (e.g., overlapping) the process windows of each individual pattern. The boundaries of the process window of a set of patterns include the boundaries of the process windows of some of the individual patterns. In other words, these individual patterns limit the process window of the set of patterns.

[0072] As Figure 2 shown, a lithographic apparatus LA can form part of a lithocell LC, sometimes also referred to as a lithographic cell or cluster, which also includes equipment for performing pre-exposure and post-exposure processes on a substrate. Conventionally, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the 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 ports I / O1, I / O2, moves them between different process equipment, and then delivers them to the feed table LB of the lithographic apparatus. These devices, commonly referred to collectively as the track, are controlled by a track control unit TCU, which itself is controlled by a monitoring system SCS that also controls the lithographic apparatus via a lithography control unit LACU. Thus, the different devices can be operated to maximize throughput and processing efficiency.

[0073] In order for a substrate exposed by a lithographic apparatus to be correctly and consistently exposed and / or in order to monitor a part of a 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 the substrate or other object to measure or determine one or more properties such as alignment, overlay (e.g., between structures in an overlay layer or between structures in the same layer, which may be provided separately to the layer by, for example, a double patterning process), line thickness, critical dimension (CD), focus offset, material properties, etc. Thus, a manufacturing facility in which the lithocell LC is located typically also includes a metrology system that measures some or all of the substrates W ( Figure 1 ) that have been processed in the lithocell or other objects in the lithocell. The metrology system can be part of the lithocell LC, for example, it can be part of the lithographic apparatus LA (such as an alignment sensor AS ( Figure 1 )).

[0074] One or more measurement parameters can include, for example, alignment, overlap between successive layers formed in or on a patterned substrate, critical dimension (CD) (e.g., critical line width) of features formed in or on a patterned substrate, focus or focus error of an optical lithography step, dose or dose error of an optical lithography step, optical aberration of an optical lithography step, etc. The measurement is typically performed on one or more dedicated metrology targets provided on the substrate. The measurement can be performed after resist development but before etching, after etching, after deposition, and / or at other times.

[0075] There are a variety of techniques for measuring structures formed during a patterning process, including using a scanning electron microscope, image-based measurement tools, and / or various specialized tools. A fast and non-invasive form of specialized metrology tool is a metrology tool in which a radiation beam is directed onto a target on the substrate surface and the 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. Conventionally, this can be referred to as diffraction-based metrology. Applications of this diffraction-based metrology include measurement of overlap, alignment, etc. For example, overlap and / or alignment can be measured by comparing portions of diffraction spectra (e.g., comparing different diffraction orders in the diffraction spectrum of a periodic grating).

[0076] Thus, during a device fabrication process (e.g., a patterning process or a lithography process), the substrate or other object can be subjected to various types of measurements during or after the process. The measurement can determine whether a particular substrate is defective, can establish adjustments to the process and the equipment used in the process (e.g., aligning two layers on a substrate or aligning a patterning device with a substrate), can measure the performance of the process and the equipment, or may be used for other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements such as the ASML YieldStar metrology tool, the ASML SMASH metrology system), mechanical measurements (e.g., profiling using a stylus, atomic force microscope (AFM)), and / or non-optical imaging (e.g., scanning electron microscope (SEM)).

[0077] The metrology results can be provided directly or indirectly to a monitoring system SCS. If an error is detected, the adjustment can be made to the exposure of subsequent substrates (especially if the inspection can be completed quickly enough so that one or more other substrates in the batch are still to be exposed) and / or to the subsequent exposures of the exposed substrate. Moreover, the exposed substrate can be stripped and reworked to improve yield, or discarded, thus avoiding further processing of a known faulty substrate. In cases where only some target portions of the substrate are faulty, further exposure can be performed only on those target portions that meet the specifications. Other manufacturing process adjustments are also under consideration.

[0078] A metrology system can be used to determine one or more properties of a substrate structure, in particular how one or more properties of different substrate structures vary or how different layers of the same substrate structure vary between the layers. The metrology system can be integrated into a lithographic apparatus LA or a lithographic cell LC, or can be a stand-alone device.

[0079] To enable metrology, typically one or more targets are provided specifically on the substrate. Typically, the targets are specifically designed and can include periodic structures. For example, the targets on the substrate can include one or more 1D periodic structures (e.g., geometric features such as gratings) that are printed such that after development, the periodic structure features are formed by solid resist lines. As another example, the targets can include one or more 2D periodic structures (e.g., gratings) that are printed such that after development, one or more periodic structures are formed by solid resist pillars or vias in the resist. Alternatively, bars, pillars or vias can be etched into the substrate (e.g., into one or more layers on the substrate).

[0080] Figure 3 An example metrology (inspection) system 10 is depicted that can be used to detect overlay, alignment and / or perform other metrology operations. It includes a radiation or illumination source 2 that projects or otherwise irradiates radiation onto a substrate W (which can typically include metrology marks). The redirected radiation is transmitted to sensors such as a spectrometer detector 4 and / or other sensors that measure the spectrum (intensity as a function of wavelength) of the specularly reflected and / or diffracted radiation, as for example Figure 4 shown in the graph on the left. The sensors can generate metrology signals that convey metrology data indicative of the properties of the reflected radiation. From this data, the structure or profile of the detected spectrum can be reconstructed by one or more processors PRO, generally illustrated as Figure 4 shown, or can be reconstructed by other operations.

[0081] As with Figure 1 the lithographic apparatus LA in Figure 4 (not shown in Figure 1The substrate tables WT (WTa or WTb or both) are similar or identical. In an example where the inspection system 10 is integrated with a lithographic apparatus, they can even be the same substrate table. A coarse locator and a fine locator can be provided and configured to accurately position the substrate with respect to the measurement optical system. Various sensors and actuators are provided, for example to obtain the position of an object part of interest of the structure (such as a metrology mark) and place it in a position under the objective lens. Typically, many measurements of the object part of the structure will be made at different positions across the substrate W. The substrate support can be moved in the X and Y directions to acquire different objects, and can be moved in the Z direction to obtain a desired position of the object part with respect to the focus of the optical system. When, for example, in practice the optical system may remain substantially stationary (usually in the X and Y directions, but also possibly in the Z direction) and the substrate is moved, it is convenient to think and describe the operation as if the objective lens were placed in different positions relative to the substrate. As long as the relative positions of the substrate and the optical system are correct, in principle it does not matter which of these is moving, or both are moving, or a part of the optical system is moving (such as in the Z and / or tilt directions) while the rest of the optical system is stationary and the substrate is moving (such as in the X and Y directions, but also optionally in the Z and / or tilt directions).

[0082] For a typical metrology measurement, the object (part) 30 on the substrate W can be a 1D grating, which is printed such that after development, the grating bars are formed by solid resist lines (which can be covered by a deposited layer, for example) and / or other materials. Alternatively, the object 30 can be a 2D grating, which is printed such that after development, the grating is formed by solid resist pillars and / or other features in the resist.

[0083] The grating bars, pillars, vias, and / or other features can be etched into or onto the substrate (such as into one or more layers on the substrate), deposited on the substrate, covered by a deposited layer, and / or have other properties. The object (part) 30 (such as the grating bars, pillars, vias, etc.) is sensitive to changes in the processing during the patterning process (such as optical aberrations, focus changes, dose changes, etc. in a lithographic projection apparatus such as a projection system), such that changes in the process manifest as changes in the object 30. Therefore, the measurement data from the object 30 can be used to determine the adjustment of one or more manufacturing processes and / or serve as a basis for making actual adjustments.

[0084] For example, measurement data from target 30 can indicate an overlap of layers of a semiconductor device. The measurement data from target 30 can be used (e.g., by one or more processors PRO and / or other processors) to determine one or more semiconductor device manufacturing process parameters based on the overlap and to determine an adjustment of a semiconductor device manufacturing apparatus based on the one or more determined semiconductor device manufacturing process parameters. In some embodiments, this can include, for example, stage position adjustment, or this can include determining an adjustment of a mask design, a metrology target design, a semiconductor device design, radiation intensity, radiation incident angle, radiation wavelength, pupil size and / or shape, resist material, and / or other process parameters.

[0085] Figure 5 illustrates a plan view of a typical target (e.g., a metrology mark) 30 and Figure 4 the extent of a typical radiation illumination spot S in the system of. Generally, in order to obtain a diffraction spectrum that is not disturbed by surrounding structures, in one embodiment, target 30 is a periodic structure (e.g., a grating) that is larger than the width (e.g., diameter) of illumination spot S. The width of spot S can be less than the width and length of the target. In other words, the target is 'underfilled' with illumination, and the diffraction signal is substantially not affected by any signals from product features, etc., outside of the target itself. For example, the illumination arrangement can be configured to provide illumination of uniform intensity in the back focal plane of the objective lens. Alternatively, the illumination can be restricted to an on-axis or off-axis direction, e.g., by including an aperture in the illumination path.

[0086] Figure 6 illustrates beam modifiers 600a and 600b. For example, in this example, beam modifiers 600a and / or 600b are broadband metasurfaces (e.g., configured as a whole for polychromatic light) that are locally narrowband (e.g., having different sub-parts configured to transmit separate, narrower-band radiation sub-beams, which are monochromatic or grayscale in this example). Different radiation wavelength ranges or bands are Figure 6 shown as different grayscales in. The local operating wavelength of different sub-parts of the beam modifier is defined by the diffraction manner of light. For example, if the incident radiation beam 604 is a plane wave and beam modifiers 600a and / or 600b (e.g., metasurfaces) are in the far field, each point of the metasurface operates at a single wavelength. However, for a Gaussian input beam 604, at each point, the metasurface has a finite wavelength bandwidth Δλ, which is a function of the beam waist w0 of the incident radiation beam 604.

[0087] Beam modifier 600a or 600b can be used in a metrology system, such as Figure 3The illustrated system 10 replaces or enhances an objective lens configured to direct radiation between one or more metrology targets 30, such as one or more diffraction grating targets. The radiation can be used to obtain an image of the metrology target and / or for other purposes. The radiation can include illumination, such as light and / or other radiation. For example, the target 30 can include one or more metrology marks formed in a substrate such as a semiconductor wafer, such as a diffraction grating target. In some embodiments, beam modifiers 600a and 600b can form part of or be part of the system 10 described above with respect to Figure 3 For example, as described herein, beam modifiers 600a and / or 600b can form part of an alignment sensor and / or an overlay detection sensor represented by the system 10 ( Figure 3 ). For example, the alignment sensor and / or the overlay detection sensor can be configured for a semiconductor wafer and can be used in a semiconductor manufacturing process.

[0088] Beam modifiers 600a and / or 600b are configured to modify the amplitude, phase, and / or polarization of the incident radiation beam 604 from a radiation source (e.g., Figure 3 the source 2 shown and described above) and / or a diffractor 602. The radiation beam 604 can be, for example, a broadband radiation beam and / or other radiation beam. Modifying the amplitude, phase, and / or polarization of the incident radiation beam aids in focusing, tuning the focal length, and / or correcting aberrations of the radiation.

[0089] Figure 6 The illustrated beam modifiers 600a and / or 600b can be configured to receive the incident radiation beam 604 from a radiation source (see Figure 3 ), and transmit radiation 610a or 610b having a modified amplitude, phase, and / or polarization, respectively. The diffractor 602 can be a grating and / or other diffractor. The diffractor 602 can be configured to separate the beam 604 into specific wavelength ranges and direct the specific wavelength ranges to different sub-parts (601a or 601b, 603a or 603b, 605a or 605b, and / or 607a and 607b) of the beam modifiers 600a and / or 600b. In some embodiments, beam modifiers 600a and / or 600b include a two-dimensional (2D) array of adjacent sub-parts (601a or 601b, 603a or 603b, 605a or 605b, and / or 607a and 607b). In some embodiments, diffraction can include spatially separating the incident radiation beam 604 into different wavelength groups by color and / or other diffraction.

[0090] The diffracted incident radiation beam 625 has a known wavelength range. This known wavelength range can be used to configure beam modifiers 600a and / or 600b. As Figure 6As shown, in some embodiments, beam modifier 600a may be configured to collimate the transmitted radiation 610a. In some embodiments, beam modifier 610b may be configured to focus 630 the transmitted radiation 610b towards the target 30. In some embodiments, a beam modifier ( Figure 6 not shown) may be configured to divide the diffracted incident radiation beam 625 into a series of non-overlapping wavelength radiation bands, each wavelength radiation band being focused at different spots on the target 30, the detector, and / or other locations. Note that beam modifiers similar and / or identical to Figure 6 the shown beam modifiers 600a and / or 600b may be similarly configured to receive diffracted radiation from the target 30 (the grating thereon) and transmit the diffracted radiation towards the detector (e.g., in a collimated, focused, divided, and / or other form).

[0091] As Figure 6 shown, beam modifiers 600a and 600b are configured to transmit separate narrow sub-beams (651a and 651b, 653a and 653b, 655a and 655b, and 657a and 657b) of radiation 610a and 610b having modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam 625. Beam modifiers 600a and 600b include different sub-parts (601a or 601b, 603a or 603b, 605a or 605b, and / or 607a and 607b), which are configured to transmit separate narrower-band radiation sub-beams (651a and 651b, 653a and 653b, 655a and 655b, and 657a and 657b). Different sub-parts (e.g., of the same metasurface) are configured for different non-overlapping radiation wavelength bandwidths within a known wavelength range. The diffracted incident radiation beam 625 received by beam modifier 600a and / or 600b is spatially separated into different wavelength groups by color (in this example, different grayscales) and directed to the color-corresponding sub-parts in different sub-parts (601a or 601b, 603a or 603b, 605a or 605b, and / or 607a and 607b). In some embodiments, the diffracted incident radiation beam 625 received by beam modifier 600a and / or 600b is spatially separated into different wavelength groups by color and directed by the diffractor 602 (e.g., a grating) to the color-corresponding sub-parts in different sub-parts.

[0092] In some embodiments, for example, the non-overlapping radiation wavelength bandwidth requirements may be a function of the grating pitch. If the grating pitch is reduced, the diffraction angle increases, and thus different wavelengths are further separated. For example, this results in less overlap between different color bands, thereby reducing the required bandwidth.

[0093] In some embodiments, the separated narrowband radiation sub-beams (651a and 651b, 653a and 653b, 655a and 655b, and 657a and 657b) include non-overlapping radiation sub-beams with locally narrowed bandwidths having modified amplitude, phase, and / or polarization. For example, each sub-section can be associated with a different set of color wavelengths and have a wavelength bandwidth for the associated color (as shown by different grayscale levels in Figure 6 ). In some embodiments, the non-overlapping radiation wavelength bandwidths are fixed and are determined based on the pitch of the grating (e.g., diffractive body 602) that generates the diffraction of the incident radiation beam 625, the grating height, the wavelength, the distance (h) between the grating and the beam modifier, the beam waist (or generally the shape), and / or other information.

[0094] In some embodiments, as described above, the beam modifiers 600a and / or 600b are metasurfaces. The metasurfaces include nanoantennas, meta-atoms, scatterers, nanoparticles, and / or other structures. In some embodiments, the different sub-sections (601a or 601b, 603a or 603b, 605a or 605b, and / or 607a and 607b) include adjacent local regions of a single integral beam modifier 600a and / or 600b (e.g., metasurface) formed by nanoantennas, meta-atoms, scatterers, and / or nanoparticles configured for specific non-overlapping radiation wavelength bandwidths. In some embodiments, the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include blocks of material having heights, widths, lengths, and / or rotation angles configured for specific non-overlapping radiation wavelength bandwidths. In some embodiments, the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include free-form shapes configured for specific non-overlapping radiation wavelength bandwidths.

[0095] In some embodiments, as shown in Figure 6 , the different sub-sections (601b, 603b, 605b, and / or 607b) are configured to focus 630 the transmitted radiation of a specific color (e.g., radiation sub-beams 651b, 653b, 655b, and 657b) onto a target 30 at a target location for that color. In some embodiments, the different sub-sections (601a, 603a, 605a, and / or 607a) are configured to collimate 620 the transmitted radiation of a specific color to form a collimated radiation beam of that color (e.g., radiation sub-beams 651a, 653a, 655a, and 657a). In some embodiments, the different sub-sections are configured to disperse the transmitted radiation of a specific color towards the target and target location for that color ( Figure 6 , not shown).

[0096] In some embodiments, the distance h between the diffractive element 602 (e.g., grating) and the beam modifier 600a or 600b is configured to be adjusted based on the grating pitch and / or different operating wavelengths, which correspond to different sets of color wavelengths associated with different sub - parts. In some embodiments, adjusting the height does not change the angle of incidence, but increasing the distance increases the area required for the metasurface. (As described below Figure 8 shows that adjusting the height helps reduce the required bandwidth.)

[0097] Figure 7 Schematically illustrates separating an incident radiation beam into bands. The phase distribution of the beam modifier (e.g., metasurface) is a function of the wavelength λ of the incident radiation beam and / or other factors. Figure 7 Shows three beams with three different wavelengths: λ0, λ0 - Dλ1, λ0 + Dλ2. The minimum values of Dλ1 and Dλ2 are sought to avoid overlap between them. However, at each point (x, y) on the metasurface, the operating wavelength is determined by the diffraction angle sin -1 (λ / P) (when the incoming beam is normally incident on the grating), where P represents the pitch of the diffractive element (e.g., Figure 6 the diffractive element 602 shown). If the incident radiation beam is a plane wave and the metasurface is far from the grating (e.g., diffractive element 602) (e.g., Figure 6 the "h" in it is relatively large), then the metasurface operates at a single wavelength at each point. But for a Gaussian input beam, at each point, the metasurface has a finite bandwidth Δλ, which is a function of the beam waist (w0), pitch size, and other parameters. Figure 7 Illustrates two different images 700 and 702, showing the wavelength bandwidth range Δλ for different (diffractive element / grating) pitches and the waist of the incident radiation beam 1,2 . Shows three beams with three different wavelengths: λ0, λ0 - Dλ1, λ0 + Dλ2. In Figure 7 the local bandwidth of different sub - parts of the metasurface (as Figure 6 shown) is defined as the minimum difference in wavelength Δλ 1,2 to avoid overlap between adjacent diffractive Gaussian beams, and it is a function of the pitch, wavelength, and height h. The sensitivity to wavelength and h is less than the sensitivity to pitch. In the calculation of this example shown in Figure 7 , h = 1 mm is considered. For a beam waist of 10 μm (e.g., see the dashed lines in images 700 and 702) and a pitch size less than 2.5 μm, a local bandwidth of 100 nm is sufficient to cover the measurement system wavelength range from, for example, 400 nm to 900 nm.

[0098] For a specific example wavelength λ = 635 nm, Figure 7Shows the results determined for a local bandwidth (e.g., for a non-overlapping radiation wavelength bandwidth within a known wavelength range for a sub-part of a beam modifier, such as a metasurface) wavelength range Δλ, as a function of the pitch of a grating (e.g., Figure 6 the diffractive body 602 shown) and the beam waist of the incident radiation beam 604 (e.g., Figure 6 shown) at the focal position. To simplify the determination of this example, Figure 7 it is assumed that the incident beam (e.g., beam 604) is a Gaussian beam and the grating (e.g., diffractive body 602) is infinite. The bandwidth is insensitive to wavelength, and as Figure 7 shown, the bandwidths on either side of the operating wavelength are nearly similar, especially for smaller pitch sizes. It can be seen that if the pitch is less than 2 μm, a bandwidth of 100 nm is sufficient to cover the entire wavelength range of a typical measurement system (e.g., as shown in the graph 704).

[0099] For h = 1, 2, 3, and 5 mm, Figure 8 graph 800 shows the local metasurface sub-part bandwidth wavelength range Δλ as a function of height h (see Figure 6 - the distance between the diffractive body 602 and the beam modifier 600a or 600b). As Figure 8 shown, the line for h = 1 mm is above and spaced from the lines for h = 2, 3, and 5 mm. Increasing the height h helps to reduce (arrow 802) the bandwidth required for the same pitch. In other words, the required bandwidth can be reduced by increasing the distance between the diffractive body (e.g., grating) and the beam modifier (e.g., metasurface).

[0100] The measurement sensor needs to work with diffractive bodies (e.g., Figure 6 the diffractive body 602 shown) having different pitches. The beam modifier 600a and / or 600b is configured for specific . The term represents the radiation incident angle, and h is the height described above. The distance from the center is the tangent of the angle multiplied by the height. This is the center position of the metasurface for each wavelength. When the pitch changes, only a corresponding change in height is required. In other words, if the pitch P of the diffractive body changes, the beam modifier (e.g., metasurface) also needs to change accordingly. However, when the pitch is greater than 1.5 , can be approximated as . This means that if the pitch changes, only h must change to maintain the same . Note that even without an exact one-to-one mapping, any errors can be compensated for by designing more broadband meta-atoms in the beam modifier (metasurface).

[0101] When the pitch changes, the angle of incidence of the incident radiation on the beam modifier (e.g., metasurface) also changes. Due to coma and / or other factors, the focal spot (e.g., on the target 30 shown and described above) may be distorted. For example, if the angle of incidence changes to approximately 25 degrees, the aberration can be corrected. Such correction can be performed using beam modifier doublets and / or other devices. Figure 6 As shown and described above, on the target 30) may be distorted. For example, if the angle of incidence changes to approximately 25 degrees, the aberration can be corrected. Such correction can be performed using beam modifier doublets and / or other devices.

[0102] Figure 9 Illustrated is a beam modifier (e.g., metasurface) doublet 900 (e.g., the above-described (multiple) beam modifiers may include beam modifier doublets). In some embodiments, the beam modifier doublet 900 includes a first metasurface 902 and a second metasurface 904 spaced apart from the first metasurface 902 along the optical path. Figure 9 Also illustrated are the incident beam 910, diffractors 912a and 912b, diffracted incident beams 914a and 914b, and narrowband radiation sub-beams 916a and 916b transmitted by sub-parts of the first metasurface 902 and the second metasurface 904 (see the description of the sub-parts in Figure 6 ). The spacing s between the second metasurface 904 and the first metasurface 902 controls the focal length, corrects defocus, and / or corrects the wavefront aberration of the narrowband radiation sub-beams 916a and 916b of different colors transmitted by the sub-parts. Additionally, the spacing s can be adjusted based on the pitch P of the diffractors 912a and / or 912b. In Figure 9 ), the pitch P2 of the diffractor 912b is less than the pitch P1 of the diffractor 912a. In Figure 9 ), the spacing s of the diffractor 912b relative to the diffractor 912a has changed.

[0103] In some embodiments, a mechanical system (e.g., controlled by the processor PRO shown in Figure 3 ) is configured to adjust the spacing s between the metasurfaces 902 and 904, between the metasurface 902 and the diffractors 912a and / or 912b, and / or control other parameters. In some embodiments, the space between the second metasurface 904 and the first metasurface 902 is filled with a material. The material can have a refractive index configured to be controlled to adjust the focusing of the beam modifier doublet 900. For example, the refractive index of the material can be controlled by applying a voltage to the material or by applying an optical control signal to the material. The material can include liquid crystal, electro-optic material, and / or other materials. Electro-optic materials include some polymers, lithium niobate, aluminum nitride, etc. The liquid crystal can be any commercially available liquid crystal, including, for example, E7® from Merck. For example, the refractive index of the material can be controlled by applying a voltage to the material or by applying an optical control signal to the material. Note that an active material is not strictly required but can be included. As described herein, the doublet can move.

[0104] In some embodiments, the movement can be electronically controlled by a processor, such as Figure 3 (and the processor PRO shown below Figure 12 ). The processor PRO can be included in a computing system (e.g., Figure 12 CS in), and can operate based on computer or machine-readable instructions MRI (e.g., as described below with respect to Figure 12 ). Electronic communication can be achieved by sending electronic signals between separate components, sending data between separate components, sending values and / or other communication between separate components. The components of the metrology system can communicate via wires or wirelessly via a network, such as the Internet or the Internet combined with various other networks, such as a local area network, a cellular network, or a personal area network, an internal organizational network, and / or other networks.

[0105] In some embodiments, one or more actuators can be coupled to and configured to move one or more of the above-described components. The actuators can be coupled to one or more of these components by adhesives, clips, fixtures, screws, collars, and / or other mechanisms. The actuators can be configured to be electronically controlled. Each actuator can be configured to convert an electrical signal into mechanical displacement. The mechanical displacement is configured to move components, such as one or more metasurfaces. As an example, one or more actuators can be piezoelectric. One or more processors PRO can be configured to control the actuators. One or more processors PRO can be configured to individually control each of the one or more actuators.

[0106] As described above, if the radiation incident angle is changed to about 25 degrees using the metasurface bimodal 900 ( Figure 9 , upper right panel), then the aberration can be corrected. If the pitch P varies between 1.5 and 3 μm, the incident angle change at the two extremes of the spectrum is less than 15 degrees ( Figure 9 , middle upper). Note that the speckle has shifted, but by moving the detector of the metrology system, the speckle shift can be corrected. Since the pitch of the diffractive body (e.g., grating) typically does not change across the substrate, the mechanical movement of the detector does not slow down the measurement process. Figure 9 The upper left panel in shows how the incident angle changes with the change in pitch. For a wide range of pitches, the incident angle only changes by 20 degrees, indicating that the bimodal operates as expected.

[0107] For some applications, beam dispersion may be desirable. In some embodiments, the beam modifier may be configured for beam dispersion rather than beam focusing or beam collimation. In these embodiments, the light is still focused, but each color is focused at a different spot. In some embodiments, the metasurface is still dispersive, but the metasurface geometric dispersion compensates for the material dispersion. Here, the metasurface geometric dispersion enhances the material dispersion. Thus, different wavelengths are separated.

[0108] Figure 10 Illustrated is a beam modifier 1000 (e.g., a metasurface) configured to divide a diffracted incident radiation beam 1025 (after the incident radiation beam 1030 is diffracted by a diffractor 1040) into a series of non-overlapping radiation bands 1002, 1004, 1006, 1008, each non-overlapping radiation band being focused at a different spot on a target 30, a detector, and / or other locations. The beam modifier 1000 is configured to enhance spectral dispersion rather than reduce spectral dispersion. In some embodiments, for example, the beam modifier 1000 may be a hyper-dispersive metasurface. The beam modifier 1000 is configured to perform spatial demultiplexing of the bands of the incident radiation beam 1030, as Figure 10 shown. This type of metasurface is useful for many applications, such as integrated optical alignment sensors, where the bandwidth of a capture grating coupler is narrow and the overlap between beams hinders efficient beam capture. Such a metasurface also helps to demultiplex the beams, and each beam can be coupled to a different optical fiber or waveguide (or generally a detector). By focusing different wavelengths at different spots, smaller grating couplers can be used, which are easier to sufficiently separate from each other (e.g., such that they operate properly).

[0109] Figure 11 Illustrated is a measurement method 1101. In some embodiments, for example, the method 1101 is performed as part of an overlay and / or alignment sensing operation in a semiconductor device manufacturing process. In some embodiments, for example, one or more operations of the method 1101 may be implemented in or by a metrology system such as Figure 3 the system 10 illustrated, a beam modifier such as Figure 6 the beam modifiers 600a and / or 600b illustrated (e.g., a metasurface), a computer system (e.g., Figure 12 illustrated and described below), and / or other systems. In some embodiments, the method 1101 includes generating and diffracting (operation 1102) an incident radiation beam, receiving and transmitting (operation 1104) the diffracted incident radiation beam, generating (operation 1106) a detection signal, and / or other operations. For example, the diffractor may be a grating and / or other diffractors described above.

[0110] The operations of method 1101 are intended to be illustrative. In some embodiments, method 1101 may be completed with one or more additional operations not described and / or without one or more of the operations discussed. For example, in some embodiments, method 1101 may include additional operations that include determining the overlap and / or alignment of semiconductor wafers and / or determining the adjustment of semiconductor device manufacturing processes. Additionally, the operations of method 1101 in Figure 11 shown and described herein in the order presented is not intended to be limiting.

[0111] In some embodiments, one or more portions of method 1101 may be implemented and / or controlled in one or more processing devices (e.g., digital processors, analog processors, digital circuits designed to process information, analog circuits designed to process information, state machines, and / or other mechanisms that electronically process information). The one or more processing devices may include one or more devices that execute some or all of the operations of method 1101 in response to instructions electronically stored on an electronic storage medium. The one or more processing devices may include one or more devices that are configured by hardware, firmware, and / or software to be specifically designed to perform one or more operations of method 1101 (e.g., see the discussion related to Figure 12 below).

[0112] In operation 1102, an incident radiation beam is generated. The incident radiation beam is generated by a radiation source that is part of a metrology system. Additionally, operation 1102 may include diffracting the incident radiation beam using a diffracting body. In some embodiments, the radiation source is the same as or similar to Figure 3 the illumination source 2 shown and described above. The incident radiation beam may be diffracted using a diffracting body that is similar and / or the same as Figure 6 the diffracting body 602 shown.

[0113] In some embodiments, the metrology system and / or the diffracting body includes a wavelength division multiplexer in a multi-core optical fiber, a blazed grating, and / or other components. Operation 1102 may include, for example, using wavelength division multiplexing in a multi-core optical fiber and / or using a blazed grating to spatially separate the incident radiation received by the diffracting body into different wavelength groups by color.

[0114] In operation 1104, a diffracted incident radiation beam is received by a beam modifier. The diffracted incident radiation beam is received from a radiation source and a diffracting body. The diffracted incident radiation beam has a known wavelength range. Operation 1104 also includes transmitting, using the beam modifier, a separate, narrower-band radiation sub-beam having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam. The beam modifier includes different sub-parts that are configured to transmit the separate, narrower-band radiation sub-beams. The different sub-parts are configured for different, non-overlapping radiation wavelength bandwidths within the known wavelength range. The diffracted incident radiation beam received by the beam modifier is spatially separated into different wavelength groups by color and directed to color-corresponding sub-parts in the different sub-parts. In some embodiments, the diffracted incident radiation beam received by the beam modifier is spatially separated into different wavelength groups by color and directed to color-corresponding sub-parts in the different sub-parts by the diffracting body (e.g., a grating). For example, the non-overlapping radiation wavelength bandwidth requirement can be a function of the grating pitch. In some embodiments, the beam modifier focuses the diffracted incident radiation beam, collimates the diffracted incident radiation beam, or divides the diffracted incident radiation beam into a series of non-overlapping radiation bands, each non-overlapping radiation band being focused at a different spot on a target.

[0115] In some embodiments, the separate, narrower-band radiation sub-beams include non-overlapping radiation sub-beams with a locally narrowed bandwidth having a modified amplitude, phase, and / or polarization. For example, each sub-part can be associated with a different color wavelength group and have a wavelength bandwidth for the associated color.

[0116] In some embodiments, the beam modifier is a metasurface, and the metasurface includes nanoantennas, meta-atoms, scatterers, nanoparticles, and / or other structures. In some embodiments, the different sub-parts include adjacent local regions of a single monolithic metasurface formed by nanoantennas, meta-atoms, scatterers, and / or nanoparticles configured for specific, non-overlapping radiation wavelength bandwidths. In some embodiments, the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include blocks of material having heights, widths, lengths, and / or rotation angles configured for specific, non-overlapping radiation wavelength bandwidths. In some embodiments, the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include free-form shapes configured for specific, non-overlapping radiation wavelength bandwidths.

[0117] In some embodiments, the different sub-parts are configured to focus the transmitted radiation of a specific color onto a target at a target location for that color. In some embodiments, the different sub-parts are configured to collimate the transmitted radiation of a specific color to form a collimated radiation beam for that color. In some embodiments, the different sub-parts are configured to disperse the transmitted radiation of a specific color toward a target and a target location for that color.

[0118] In some embodiments, the distance between the diffractive element (e.g., grating) and the beam modifier is configured to be adjusted based on the grating pitch and / or different operating wavelengths, which correspond to different groups of color wavelengths associated with different sub-parts. In some embodiments, adjusting the distance between the grating and the beam modifier changes the angle of incidence of the diffracted incident radiation beam on the beam modifier.

[0119] In some embodiments, the beam modifier includes a two-dimensional (2D) array of adjacent sub-parts. In some embodiments, the non-overlapping radiation wavelength bandwidth is fixed and determined based on the pitch, height, wavelength of the grating (e.g., diffractive element) that generates the diffracted incident radiation beam, and / or the distance between the grating and the beam modifier.

[0120] In some embodiments, the beam modifier includes a first metasurface and a second metasurface spaced apart from the first metasurface along the optical path. The spacing between the second metasurface and the first metasurface controls the focal length, corrects defocus, and / or corrects the wavefront aberration of the narrowband radiation sub-beams of different colors transmitted by the sub-parts. A mechanical system (e.g., controlled by the processor PRO) is configured to adjust the spacing between the metasurfaces, between the metasurfaces and the grating, and / or control other parameters.

[0121] In some embodiments, a material fills the space between the second metasurface and the first metasurface. The material may have a refractive index configured to be controlled to adjust the focusing of the beam modifier. Operation 1104 may include controlling the refractive index of the material, for example, by applying a voltage to the material or applying an optical control signal to the material.

[0122] In some embodiments, the beam modifier may include a beam modifier array. The beam modifier array may include a first part, a second part, and / or other beam modifiers. The first part is configured to receive the incident radiation beam from the radiation source, transmit the radiation with modified amplitude, phase, and / or polarization, and focus the transmitted radiation towards the target. The second part is configured to receive the diffracted radiation from the target and transmit the diffracted radiation towards the detector. In some embodiments, for example, the first part and the second part overlap and / or mix on the overall body. In some embodiments, the first part and the second part are included in a single metasurface. In some embodiments, the first part and the second part include multiple metasurfaces (e.g., separate bodies or only a single metasurface within the body).

[0123] In some embodiments, radiation can be directed by a radiation source onto multiple targets, a single target, sub - parts of a target (e.g., things less than the whole) on a substrate (such as a semiconductor wafer) and / or otherwise onto the substrate. In some embodiments, radiation can be directed onto the target in a time - varying manner. For example, the radiation can be rasterized over the target (e.g., by moving the target under the radiation) such that different parts of the target are irradiated at different times. As another example, the characteristics of the radiation (e.g., wavelength, intensity, etc.) can vary. This may create a time - varying data envelope or window for analysis. The data envelope may assist in analyzing individual sub - parts of the target, comparing one part of the target to another part and / or other targets (e.g., in other layers) and / or performing other analyses.

[0124] In operation 1106, a detection signal is generated. As described above, the detection signal can be generated based on the detected reflected radiation from the diffraction grating target(s). The detection signal is generated by a sensor (such as Figure 3 detector 4, a camera, and / or other sensors in) based on the radiation received by the sensor. The detection signal includes measurement information related to the target(s). For example, the detection signal can be an overlap and / or alignment signal and / or other metrology signal that includes overlap and / or alignment measurement information. The measurement information (e.g., overlap value, alignment value, and / or other information) can be determined using interferometry principles and / or other principles.

[0125] The detection signal includes an electrical signal that represents and / or otherwise corresponds to the radiation reflected from the target(s). The diffracted radiation from the target can include +1 and - 1 order diffracted radiation.

[0126] For example, the detection signal can indicate a metrology value and / or other information associated with the diffraction grating target. Generating the detection signal includes sensing the reflected radiation and converting the sensed reflected radiation into an electrical signal. In some embodiments, generating the detection signal includes sensing different parts of the reflected radiation from different regions and / or different geometries and / or multiple targets of the target, and combining the different parts of the reflected radiation to form the detection signal. This can include using the radiation generation and / or analysis described herein to generate one or more images of the target. Such sensing and conversion can be performed by components similar and / or identical to Figure 3 detector 4 and / or processor PRO shown and / or other components.

[0127] In some embodiments, method 1101 includes detecting reflected radiation from one or more diffraction grating targets. Detecting the reflected radiation includes detecting one or more phase and / or amplitude (intensity) shifts in the 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 the target. For example, the phase and / or amplitude of the reflected radiation from one side of the target is different from the phase and / or amplitude of the reflected radiation from the other side of the target.

[0128] Detecting one or more phase and / or amplitude (intensity) shifts in the reflected radiation from the target includes measuring local phase shifts (such as local phase increments) and / or amplitude variations corresponding to different parts of the target. For example, the reflected radiation from a specific region of the target may include a sinusoidal waveform with a specific phase and / or amplitude. The reflected radiation from different regions of the target (or targets in different layers) may also include sinusoidal waveforms, but with different phases and / or amplitudes. The detected reflected radiation also includes measuring the phase and / or amplitude differences of the reflected radiation of different diffraction orders. For example, detecting one or more local phase and / or amplitude shifts can be performed using Hilbert transform and / or other techniques. Interferometric techniques and / or other operations can be used to measure the phase and / or amplitude differences of the reflected radiation of different diffraction orders.

[0129] In some embodiments, method 1101 includes determining an adjustment of a semiconductor device manufacturing process. In some embodiments, method 1101 includes determining one or more semiconductor device manufacturing process parameters. The one or more semiconductor device manufacturing process parameters can be determined based on one or more detected phase and / or amplitude changes, overlay and / or alignment values indicated by detection signals, and / or other similar systems and / or other information. The one or more parameters can include parameters of the radiation (radiation for metrology), overlay values, alignment values, metrology inspection locations on semiconductor device structure layers, radiation beam trajectories on the target, and / or other parameters. In some embodiments, the process parameters can be broadly interpreted to include stage position, mask design, metrology target design, semiconductor device design, radiation intensity (for exposing resist, etc.), radiation incident angle (for exposing resist, etc.), radiation wavelength (for exposing resist, etc.), pupil size and / or shape, resist material, and / or other parameters.

[0130] In some embodiments, method 1101 includes determining a process adjustment based on one or more determined semiconductor device manufacturing process parameters, and adjusting a semiconductor device manufacturing apparatus and / or other operations based on the determined adjustment. For example, if a determined metrology measurement is outside of a process tolerance, the measurement outside of the tolerance may be caused by one or more manufacturing processes whose process parameters have drifted and / or otherwise changed such that the process no longer produces acceptable devices (e.g., the measurement may violate a threshold of 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 the manufacturing process to again produce acceptable devices.

[0131] For example, the new or adjusted process parameters may cause a previously unacceptable measurement to be adjusted back into an acceptable range. The new or adjusted process parameters may be compared to existing parameters of a given process. For example, if there is a difference, the difference may be used to determine an adjustment to the apparatus for producing the devices (e.g., parameter "x" should be increased / decreased / changed such that it matches a new or adjusted version of parameter "x" determined as part of method 1101). In some embodiments, method 1401 may include electronically adjusting the apparatus (e.g., based on the determined process parameters). Electronically adjusting the apparatus may include sending an electronic signal and / or other communication to the apparatus, such as which causes a change to the apparatus. Electronically adjusting may include, for example, changing settings on the apparatus and / or other adjustments.

[0132] Figure 12 is a diagram of an example computer system CS that may be used for one or more operations described herein. Computer system CS includes a bus BS or other communication mechanism for passing information, and a processor PRO (or multiple processors, similar and / or identical to the Figure 3 illustrated processor PRO) coupled to 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 may also be used to store temporary variables or other intermediate information during execution of instructions by processor PRO. Computer system CS also 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.

[0133] A computer system CS can be coupled via a bus BS to a display DS, such as a flat panel or touchpad display or a cathode ray tube (CRT), for displaying information to a computer user. An input device ID, including alphanumeric keys and other keys, is coupled to the bus BS for passing information and command selections to a processor PRO. Another type of user input device is a cursor control CC, such as a mouse, trackball, or cursor direction keys, for passing direction information and command selections to the processor PRO and controlling cursor movement on the 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)), allowing the device to specify a position in a plane. A touchpad (screen) display can also be used as an input device.

[0134] In some embodiments, one or more operations described herein can be performed by the computer system CS in response to one or more sequences of one or more instructions contained in a main memory MM executed by the processor PRO. Such instructions can be read into the main memory MM from another computer-readable medium, such as a storage device SD. Execution of the instruction sequences included in the main memory MM causes the processor PRO to perform the process steps (operations) described herein. One or more processors in a multiprocessing arrangement can also be employed to execute the instruction sequences contained in the main memory MM. In some embodiments, hardwired circuitry can 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.

[0135] As used herein, the term "computer-readable medium" or "machine-readable medium" refers to any medium that participates in providing instructions to the processor PRO for execution. Such a medium can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks, such as the storage device SD. Volatile media includes dynamic memory, such as the main memory MM. Transmission media includes coaxial cables, copper wire, and fiber optics, including the wires that make up the 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. A computer-readable medium can be non-transitory, such as a floppy disk, flexible disk, hard disk, magnetic tape, any other magnetic medium, CD-ROM, DVD, any other optical medium, punch cards, paper tape, any other physical medium with hole patterns, RAM, PROM, and EPROM, flash EPROM, any other memory chip or memory cartridge. Instructions can be recorded on the non-transitory computer-readable medium. When executed by a computer, the instructions can implement any of the operations described herein. For example, a transitory computer-readable medium can include a carrier wave or other propagating electromagnetic signal.

[0136] Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to a processor PRO for execution. For example, the instructions may initially be borne on a magnetic disk of a remote computer. The remote computer may load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. A modem local to the computer system CS may receive the data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector coupled to the bus BS may receive the data carried in the infrared signal and place the data on the bus BS. The bus BS carries the data to the main memory MM, from which the processor PRO retrieves and executes the instructions. Before or after execution by the processor PRO, the instructions received by the main memory MM may optionally be stored on the storage device SD.

[0137] The computer system CS may also include a communication interface CI coupled to the bus BS. The communication interface CI provides a two-way data communication coupling with a network link NDL connected to a local network LAN. For example, the communication interface CI may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection with a corresponding type of telephone line. As another example, the communication interface CI may be a local area network (LAN) card to provide a data communication connection with a compatible LAN. A wireless link may also be implemented. In any such implementation, the communication interface CI transmits and receives electrical, electromagnetic, or optical signals that carry a digital data stream representing various types of information.

[0138] The network link NDL typically provides data communication to other data devices through one or more networks. For example, the network link NDL may provide a connection to a host computer HC through a local network LAN. This may include data communication services provided through the global packet data communication network (now commonly referred to as the "Internet" INT). The local network LAN (Internet) may use electrical, electromagnetic, or optical signals that carry a digital data stream. Signals through various networks and signals on the network data link NDL and through the communication interface CI (which carry digital data to and from the computer system CS) are exemplary forms of carriers that convey information.

[0139] The computer system CS can send messages and receive data, including program code, via one or more networks, network data links NDL, and communication interfaces CI. In an Internet example, the host computer HC can send request code for an application via the Internet INT, network data link NDL, local network LAN, and communication interface CI. For example, such a download application can provide all or part of the methods described herein. The received code can be executed by the processor PRO upon receipt, and / or stored in the storage device SD or other non-volatile storage device for later execution. In this way, the computer system CS can obtain application code in the form of a carrier wave.

[0140] Various embodiments of the present system and method are disclosed in the following numbered list of items. Hereinafter, further features, characteristics, and exemplary technical solutions of the present disclosure will be described in terms of items that can optionally be claimed in any combination:

[0141] 1. A beam modifier configured to receive a diffracted incident radiation beam from a radiation source, the diffracted incident radiation beam having a known wavelength range, the beam modifier being configured to transmit a separate, narrower-band radiation sub-beam having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam, wherein the beam modifier includes different sub-parts configured to transmit separate, narrower-band radiation sub-beams, the different sub-parts being configured for different, non-overlapping radiation wavelength bandwidths within the known wavelength range.

[0142] 2. The beam modifier according to item 1, wherein the beam modifier is a metasurface, and the metasurface includes nanoantennas, meta-atoms, scatterers, and / or nanoparticles.

[0143] 3. The beam modifier according to any one of the preceding items, wherein the separate, narrower-band radiation sub-beams include non-overlapping radiation sub-beams with a locally narrowed bandwidth having a modified amplitude, phase, and / or polarization, and wherein each sub-part is associated with a different group of color wavelengths and has a wavelength bandwidth for the associated color.

[0144] 4. The beam modifier according to any one of the preceding items, wherein the different sub-parts include adjacent local regions of a single integral metasurface formed by nanoantennas, meta-atoms, scatterers, and / or nanoparticles configured for specific, non-overlapping radiation wavelength bandwidths.

[0145] 5. The beam modifier according to any one of the preceding items, wherein the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include blocks of material having a height, width, length, and / or rotation angle configured for specific, non-overlapping radiation wavelength bandwidths.

[0146] 6. The beam modifier according to any one of the preceding clauses, wherein the nanoantennas, meta-atoms, scatterers, and / or nanoparticles comprise freeform shapes configured for specific non-overlapping radiation wavelength bandwidths.

[0147] 7. The beam modifier according to any one of the preceding clauses, wherein different sub-parts are configured to focus transmitted radiation of a specific color onto a target at a target location for that color.

[0148] 8. The beam modifier according to any one of the preceding clauses, wherein different sub-parts are configured to collimate transmitted radiation of a specific color to form a collimated radiation beam of that color.

[0149] 9. The beam modifier according to any one of the preceding clauses, wherein different sub-parts are configured to disperse transmitted radiation of a specific color towards a target and target location for that color.

[0150] 10. The beam modifier according to any one of the preceding clauses, wherein the beam modifier comprises a two-dimensional (2D) array of adjacent sub-parts.

[0151] 11. The beam modifier according to any one of the preceding clauses, wherein the non-overlapping radiation wavelength bandwidths are fixed and are determined based on the pitch, grating height, wavelength of a grating that generates a diffracted incident radiation beam, and / or the distance between the grating and the beam modifier.

[0152] 12. The beam modifier according to any one of the preceding clauses, wherein the distance between the grating and the beam modifier is configured to be adjusted based on the grating pitch and / or different operating wavelengths, which correspond to different groups of color wavelengths associated with different sub-parts.

[0153] 13. The beam modifier according to any one of the preceding clauses, wherein adjusting the distance between the grating and the beam modifier changes the angle of incidence of the diffracted incident radiation beam on the beam modifier.

[0154] 14. The beam modifier according to any one of the preceding clauses, wherein the beam modifier comprises a first metasurface and a second metasurface spaced apart from the first metasurface along the optical path.

[0155] 15. The beam modifier according to any one of the preceding clauses, wherein the spacing between the second metasurface and the first metasurface controls the focal length, corrects defocus, and / or corrects wavefront aberrations of narrowband radiation sub-beams of different colors transmitted by the sub-parts.

[0156] 16. The beam modifier according to any one of the preceding clauses, wherein a mechanical system is configured to adjust the spacing.

[0157] 17. A beam modifier according to any one of the preceding clauses, wherein the beam modifier focuses the diffracted incident radiation beam, collimates the diffracted incident radiation beam, or divides the diffracted incident radiation beam into a series of non-overlapping radiation bands, each non-overlapping radiation band being focused at a different spot on the target.

[0158] 18. A measurement system, comprising: a radiation source configured to generate an incident radiation beam; a diffractor configured to diffract the incident radiation beam; and a beam modifier configured to receive the diffracted incident radiation beam from the radiation source and the diffractor, the diffracted incident radiation beam having a known wavelength range, the beam modifier being configured to transmit separate, narrower-band radiation sub-beams having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam, wherein the beam modifier comprises different sub-parts configured to transmit the separate, narrower-band radiation sub-beams, the different sub-parts being configured for different non-overlapping radiation wavelength bandwidths within the known wavelength range, wherein the diffracted incident radiation beam received by the beam modifier is spatially separated into different wavelength groups by color and directed to color-corresponding sub-parts in the different sub-parts.

[0159] 19. The system according to clause 18, wherein the diffractor comprises a grating, wherein the diffracted incident radiation beam received by the beam modifier is spatially separated into different wavelength groups by color and directed by the grating to color-corresponding sub-parts in the different sub-parts, and wherein the requirement for non-overlapping radiation wavelength bandwidths is a function of the grating pitch.

[0160] 20. The system according to any one of the preceding clauses, further comprising a detector configured to receive the reflected radiation after reflection from the target and generate a detection signal, the reflected radiation comprising separate, narrower-band radiation sub-beams after reflection from the target.

[0161] 21. The system according to any one of the preceding clauses, wherein the measurement system forms part of an alignment sensor and / or an overlay detection sensor, and wherein the alignment sensor and / or the overlay detection sensor is configured for semiconductor wafers and is used in semiconductor manufacturing processes.

[0162] 22. A method for transmitting radiation, the method comprising: receiving, using a beam modifier, a diffracted incident radiation beam from a radiation source, the diffracted incident radiation beam having a known wavelength range; and transmitting, using the beam modifier, separate, narrower-band radiation sub-beams having a modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam, wherein the beam modifier comprises different sub-parts configured to transmit the separate, narrower-band radiation sub-beams, the different sub-parts being configured for different non-overlapping radiation wavelength bandwidths within the known wavelength range.

[0163] 23. The method according to item 22, wherein the beam modifier is a metasurface, and the metasurface includes nanoantennas, meta-atoms, scatterers, and / or nanoparticles.

[0164] 24. The method according to any one of the preceding items, wherein the individual narrower-band radiation sub-beams include non-overlapping radiation sub-beams with locally narrowed bandwidths having modified amplitudes, phases, and / or polarizations, and wherein each sub-part is associated with a different group of color wavelengths and has a wavelength bandwidth for the associated color.

[0165] 25. The method according to any one of the preceding items, wherein the different sub-parts include adjacent local regions of a single integral metasurface formed by nanoantennas, meta-atoms, scatterers, or nanoparticles configured for specific non-overlapping radiation wavelength bandwidths.

[0166] 26. The method according to any one of the preceding items, wherein the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include blocks of material having heights, widths, lengths, and / or rotational angles configured for specific non-overlapping radiation wavelength bandwidths.

[0167] 27. The method according to any one of the preceding items, wherein the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include free-form shapes configured for specific non-overlapping radiation wavelength bandwidths.

[0168] 28. The method according to any one of the preceding items, wherein the different sub-parts are configured to focus the transmitted radiation of a specific color onto a target at the target location for that color.

[0169] 29. The method according to any one of the preceding items, wherein the different sub-parts are configured to collimate the transmitted radiation of a specific color to form a collimated radiation beam of that color.

[0170] 30. The method according to any one of the preceding items, wherein the different sub-parts are configured to disperse the transmitted radiation of a specific color towards the target and target location for that color.

[0171] 31. The method according to any one of the preceding items, wherein the beam modifier includes a two-dimensional (2D) array of adjacent sub-parts.

[0172] 32. The method according to any one of the preceding items, wherein the non-overlapping radiation wavelength bandwidths are fixed and are determined based on the pitch, grating height, wavelength of the grating generating the diffracted incident radiation beam, and / or the distance between the grating and the beam modifier.

[0173] 33. The method according to any one of the preceding clauses further includes adjusting the distance between the grating and the beam modifier based on the grating pitch and / or different operating wavelengths, where the different operating wavelengths correspond to different groups of color wavelengths associated with different sub-parts.

[0174] 34. The method according to any one of the preceding clauses, wherein adjusting the distance between the grating and the beam modifier changes the angle of incidence of the diffracted incident radiation beam on the beam modifier.

[0175] 35. The method according to any one of the preceding clauses, wherein the beam modifier includes a first metasurface and a second metasurface spaced apart from the first metasurface along the optical path.

[0176] 36. The method according to any one of the preceding clauses, wherein the spacing between the second metasurface and the first metasurface controls the focal length, corrects defocus, and / or corrects the wavefront aberration of the narrowband radiation sub-beams of different colors transmitted by the sub-parts.

[0177] 37. The method according to any one of the preceding clauses, wherein the mechanical system is configured to adjust the spacing.

[0178] 38. The method according to any one of the preceding clauses, wherein the beam modifier focuses the diffracted incident radiation beam, collimates the diffracted incident radiation beam, or divides the diffracted incident radiation beam into a series of non-overlapping radiation bands, and each non-overlapping radiation band is focused on different spots on the target.

[0179] 39. A measurement method, including: using a radiation source to generate an incident radiation beam; using a diffractor to diffract the incident radiation beam; and using a beam modifier to receive the diffracted incident radiation beam from the radiation source and the diffractor, where the diffracted incident radiation beam has a known wavelength range; and using the beam modifier to transmit individual narrower-band radiation sub-beams having modified amplitude, phase, and / or polarization compared to the diffracted incident radiation beam, wherein the beam modifier includes different sub-parts configured to transmit the individual narrower-band radiation sub-beams, the different sub-parts are configured for different non-overlapping radiation wavelength bandwidths within the known wavelength range, and wherein the diffracted incident radiation beam received by the beam modifier is spatially separated into different wavelength groups by color and directed to the color-corresponding sub-parts in the different sub-parts.

[0180] 40. The method according to any one of the preceding clauses, wherein the diffractor includes a grating, wherein the diffracted incident radiation beam received by the beam modifier is spatially separated into different wavelength groups by color and directed to the color-corresponding sub-parts in the different sub-parts by the grating, and wherein the requirement for the non-overlapping radiation wavelength bandwidth is a function of the grating pitch.

[0181] 41. The method according to any one of the preceding clauses further includes using a detector to receive reflected radiation after reflection from the target and generating a detection signal, the reflected radiation including individual, narrower-band radiation sub-beams after reflection from the target.

[0182] 42. The method according to any one of the preceding clauses, wherein the radiation source, the diffracting body, and the beam modifier are included in a metrology system, and the metrology system forms part of an alignment sensor and / or an overlap detection sensor, and wherein the alignment sensor and / or the overlap detection sensor are configured for a semiconductor wafer and are used in a semiconductor manufacturing process.

[0183] The concepts disclosed herein can be associated with any general imaging system for imaging sub-wavelength features and may be particularly useful for emerging imaging technologies capable of generating increasingly shorter wavelengths. Emerging technologies that have been used include EUV (extreme ultraviolet), DUV lithography, which is capable of generating a wavelength of 193 nm using an ArF laser, and even 157 nm using a fluorine laser. Moreover, EUV lithography can generate wavelengths in the range of 20 to 5 nm by using a synchrotron or by colliding high-energy electrons with a material (solid or plasma) to generate photons in that range.

[0184] Although the concepts disclosed herein can be used to image on substrates such as silicon wafers, it should be understood that the disclosed concepts can be used with any type of lithographic imaging system, such as those for imaging on substrates other than silicon wafers. Additionally, combinations and sub-combinations of the disclosed elements can include separate embodiments.

[0185] The above description is intended to be illustrative and not restrictive. Thus, it will be apparent to those skilled in the art that modifications can be made as described without departing from the scope of the claims set forth below.

Claims

1. A beam modifier, the beam modifier being configured to receive a diffracted incident radiation beam from a radiation source, the diffracted incident radiation beam having a known wavelength range, the beam modifier being configured to transmit a separate, narrower-band radiation sub-beam having a modified amplitude, phase, and / or polarization as compared to the diffracted incident radiation beam, wherein the beam modifier includes different sub-parts, the different sub-parts being configured to transmit the separate, narrower-band radiation sub-beam, the different sub-parts being configured for different, non-overlapping radiation wavelength bandwidths within the known wavelength range.

2. The beam modifier according to claim 1, wherein the beam modifier is a metasurface, and the metasurface includes nanoantennas, meta-atoms, scatterers, and / or nanoparticles.

3. The beam modifier according to claim 1 or 2, wherein the separate, narrower-band radiation sub-beam includes non-overlapping radiation sub-beams with a locally narrowed bandwidth having the modified amplitude, phase, and / or polarization, and wherein each sub-part is associated with a different set of color wavelengths and has a wavelength bandwidth for the associated color.

4. The beam modifier according to any one of claims 1 to 3, wherein the different sub-parts include adjacent local regions of a single, integral metasurface formed by nanoantennas, meta-atoms, scatterers, and / or nanoparticles configured for specific, non-overlapping radiation wavelength bandwidths.

5. The beam modifier according to claim 4, wherein the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include blocks of material having a height, width, length, and / or rotational angle configured for specific, non-overlapping radiation wavelength bandwidths.

6. The beam modifier according to claim 4, wherein the nanoantennas, meta-atoms, scatterers, and / or nanoparticles include free-form shapes configured for specific, non-overlapping radiation wavelength bandwidths.

7. The beam modifier according to any one of claims 1 to 6, wherein the different sub-parts are configured to focus the transmitted radiation of a specific color onto a target at a target location for that color.

8. The beam modifier according to any one of claims 1 to 6, wherein the different sub-parts are configured to collimate the transmitted radiation of a specific color to form a collimated radiation beam for that color.

9. The beam modifier according to any one of claims 1 to 6, wherein the different sub-parts are configured to disperse the transmitted radiation of a specific color towards a target and target location for that color.

10. The beam modifier according to any one of claims 1 to 9, wherein the beam modifier includes a two-dimensional (2D) array of adjacent sub-parts.

11. The beam modifier according to any one of claims 1 to 10, wherein the non-overlapping radiation wavelength bandwidths are fixed, and the non-overlapping radiation wavelength bandwidths are determined based on the pitch, grating height, wavelength of the grating that generates the diffracted incident radiation beam, and / or the distance between the grating and the beam modifier.

12. The beam modifier according to claim 11, wherein the distance between the grating and the beam modifier is configured to be adjusted based on the grating pitch and / or different operating wavelengths, the different operating wavelengths corresponding to different sets of color wavelengths associated with the different sub-parts.

13. The beam modifier according to claim 12, wherein adjusting the distance between the grating and the beam modifier changes the angle of incidence of the diffracted incident radiation beam on the beam modifier.

14. The beam modifier according to claim 13, wherein the beam modifier includes a first metasurface and a second metasurface spaced apart from the first metasurface along the optical path.

15. The beam modifier according to claim 14, wherein the spacing between the second metasurface and the first metasurface controls the focal length, corrects defocus, and / or corrects the wavefront aberration of the narrowband radiation sub-beams of different colors transmitted by the sub-parts.

16. The beam modifier according to claim 15, wherein a mechanical system is configured to adjust the spacing.

17. The beam modifier according to any one of claims 1 to 16, wherein the beam modifier focuses the diffracted incident radiation beam, collimates the diffracted incident radiation beam, or divides the diffracted incident radiation beam into a series of non-overlapping radiation bands, each non-overlapping radiation band being focused at different spots on the target.

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