Detection system using metasurface and integrated optical system for lithography

Abstract

An inspection system includes an integrated optical system having a substrate, a waveguide system, and first and second grating couplers disposed on the substrate, first and second detectors, and a microstructured illumination adjuster. An integrated optical system receives first to fourth portions of illumination scattered from a target having respective first to fourth wavelengths. The first to fourth grating couplers emit the first to fourth portions into the waveguide system. The first and second wavelengths are different from the third and fourth wavelengths. The first detector receives a combination of the first portion and the second portion to generate a first measurement signal. A second detector receives a combination of the third portion and the fourth portion to generate a second measurement signal. The microstructured illumination adjuster includes first to fourth microstructured regions to direct the first to fourth portions to respective ones of the first to fourth grating couplers.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application No. 63 / 415,246, filed on October 11, 2022, the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to inspection systems, such as alignment sensors for wafer positioning in lithographic apparatus and systems. Background Art

[0004] A lithographic apparatus is a machine that applies a desired pattern to a substrate, typically on a target portion of the substrate. For example, a lithographic apparatus may be used in the manufacture of integrated circuits (ICs). In this case, a pattern forming device, which may be a mask or a reticle, may be used to produce a circuit pattern to be formed on a single layer of the IC. The pattern may be transferred to a target portion (e.g., including a portion of a die, one or several dies) on a substrate (e.g., a silicon wafer). Typically, the transfer of the pattern is performed by imaging the pattern onto a layer of radiation-sensitive material (photoresist or simply "resist") disposed on the substrate. Typically, a single substrate will contain a grid of adjacent target portions that are patterned in succession. Known lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing the entire pattern to the target portion at once, and so-called scanners, in which each target portion is irradiated by scanning the target portion synchronously parallel or antiparallel to this scanning direction while the radiation beam scans the pattern in a given direction (the "scanning" direction). The pattern may also be transferred from the patterning device to the substrate by imprinting the pattern onto the substrate.

[0005] During a lithography operation, different processing steps may require different layers to be sequentially formed on the substrate. Therefore, it may be necessary to position the substrate with high accuracy relative to a previous pattern formed on the substrate. Typically, alignment marks are placed on the substrate to be aligned and positioned relative to a second object. The lithography apparatus may use an alignment device to detect the position of the alignment marks and to align the substrate using the alignment marks to ensure accurate exposure from the mask. The misalignment between alignment marks at two different layers is measured as an overlay error.

[0006] To monitor the lithography process, the alignment position of one or more alignment marks can be measured. Due to many limitations, lithography systems can only output a limited number of prepared devices in a given time frame. An exemplary limitation is the speed of alignment measurements. Although multiple inspection sensors can be implemented in parallel within a lithography device to speed up the inspection of multiple targets, conventional sensors used in lithography measurement can be bulky and expensive due to their bulky optics, hindering their scalability. In addition, optical inspection using multiple photon wavelengths may pose some design challenges. Summary of the invention

[0007] Therefore, it is desirable to improve manufacturing throughput and accuracy.For example, aspects of the optical systems described herein can be used to build a scalable and accurate inspection system capable of using multiple photon wavelengths simultaneously.

[0008] In some aspects, the inspection system may include an integrated optical system, a first detector and a second detector, and a microstructured illumination adjuster. The integrated optical system may include a substrate, a waveguide system, and a first grating coupler, a second grating coupler, a third grating coupler, and a fourth grating coupler. The integrated optical system may be configured to receive, guide, and couple a first portion, a second portion, a third portion, and a fourth portion of the illumination scattered by the target. The first portion, the second portion, the third portion, and the fourth portion may have a corresponding first wavelength, a second wavelength, a third wavelength, and a fourth wavelength. The waveguide system may be disposed on a substrate. The first grating coupler may be disposed on a substrate and may be configured to emit the first portion into the waveguide system based on the first wavelength. The second grating coupler may be disposed on a substrate and may be configured to emit the second portion into the waveguide system based on the second wavelength. The first wavelength and the second wavelength may be the same. The third grating coupler may be disposed on a substrate and may be configured to emit the third portion into the waveguide system based on the third wavelength. The first wavelength and the third wavelength may be different. The fourth grating coupler may be disposed on a substrate and may be configured to emit the fourth portion into the waveguide system based on the fourth wavelength. The third wavelength and the fourth wavelength may be the same. The first detector may be configured to receive a combination of the first part and the second part via a waveguide system, and generate a first measurement signal including information of the phase delay of the first part and the second part. The second detector may be configured to receive a combination of the third part and the fourth part via a waveguide system, and generate a second measurement signal including information of the phase delay of the third part and the fourth part. The microstructured illumination adjuster may include a first microstructured area, a second microstructured area, a third microstructured area, and a fourth microstructured area, wherein the first microstructured area, the second microstructured area, the third microstructured area, and the fourth microstructured area are configured to guide corresponding parts of the first part, the second part, the third part, and the fourth part to corresponding grating couplers of the first grating coupler, the second grating coupler, the third grating coupler, and the fourth grating coupler.

[0009] In some aspects, the inspection system may include an integrated optical system, a first detector and a second detector, and a microstructured illumination adjuster. The integrated optical system may include a substrate, a waveguide system, and a first grating coupler and a second grating coupler. The integrated optical system may be configured to receive, guide and couple a first portion and a second portion of the illumination scattered by the target. The first portion and the second portion may have a corresponding first wavelength and a second wavelength. The waveguide system may be disposed on a substrate. The first grating coupler may be disposed on a substrate and may be configured to emit the first portion into the waveguide system based on a first wavelength. The second grating coupler may be disposed on a substrate and may be configured to emit the second portion into the waveguide system based on a second wavelength. The first wavelength and the second wavelength may be different. The first detector may be configured to receive the first portion via the waveguide system and generate a first measurement signal based on the intensity of the first portion. The second detector may be configured to receive the second portion via the waveguide system and generate a second measurement signal based on the intensity of the second portion. The microstructured illumination modulator may include first and second microstructured regions configured to direct respective ones of the first and second portions to respective ones of the first and second grating couplers.

[0010] In some aspects, the lithographic apparatus may include an illumination system, a projection system, and an inspection system. The illumination system may be configured to illuminate a pattern of a pattern forming device. The projection system may be configured to project an image of the pattern onto a substrate. The inspection system may include an integrated optical system, a first detector and a second detector, and a microstructured illumination adjuster. The integrated optical system may include a substrate, a waveguide system, and a first grating coupler and a second grating coupler. The integrated optical system may be configured to receive, guide, and couple a first portion and a second portion of the illumination scattered by a target on a substrate. The first portion and the second portion may have a corresponding first wavelength and a second wavelength. The waveguide system may be disposed on a substrate. The first grating coupler may be disposed on a substrate and may be configured to emit the first portion into the waveguide system based on a first wavelength. The second grating coupler may be disposed on a substrate and may be configured to emit the second portion into the waveguide system based on a second wavelength. The first wavelength and the second wavelength may be different. The first detector may be configured to receive the first portion via the waveguide system and generate a first measurement signal based on the intensity of the first portion. The second detector may be configured to receive the second portion via the waveguide system and generate a second measurement signal based on the intensity of the second portion. The microstructured illumination modulator may include first and second microstructured regions configured to direct respective ones of the first and second portions to respective ones of the first and second grating couplers.

[0011] The following detailed description of the additional features of various aspects of the present disclosure is made with reference to the accompanying drawings. Note that the present disclosure is not limited to the specific aspects described herein. These aspects are presented herein only for illustrative purposes. Based on the teachings contained in the present invention, (multiple) technicians in the relevant fields will understand additional aspects. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] The accompanying drawings, which are incorporated herein and constitute a part of the specification, illustrate the present disclosure and, together with the description, further serve to explain the principles of the present disclosure and enable one skilled in the relevant art(s) to make and use the aspects described herein.

[0013] Figure 1A A reflective lithographic apparatus according to some aspects is shown.

[0014] Figure 1B A transmissive lithographic apparatus according to some aspects is shown.

[0015] Figure 2 More details of a reflective lithographic apparatus according to some aspects are shown.

[0016] Figure 3 A lithography cell according to some aspects is shown.

[0017] Figure 4A and Figure 4B An inspection apparatus according to some aspects is shown.

[0018] Figures 5 to 9 An integrated optical system according to some aspects is shown.

[0019] Fig. 10A , Fig. 10B , Fig. 10C and Fig. 10D Shown is a periodic structure for a grating coupler in accordance with some aspects.

[0020] Fig.11A and Fig. 11B A unit cell of a metasurface according to some aspects is shown.

[0021] From the specific embodiments set forth below, the features of the present disclosure will become more apparent when combined with the accompanying drawings, in which the same reference numerals always identify corresponding elements. In the drawings, similar reference numerals generally indicate identical, functionally similar, and / or structurally similar elements. In addition, generally, the leftmost digit (s) of a reference numeral identifies the drawing in which the reference numeral first appears. Unless otherwise stated, the drawings provided throughout the present disclosure should not be interpreted as drawings to scale. DETAILED DESCRIPTION

[0022] The embodiments described herein and the phrases "one aspect", "an aspect", "exemplary aspect" and the like mentioned in the specification indicate that the described aspects may include specific features, structures or characteristics, but each aspect may not necessarily include the specific features, structures or characteristics. In addition, such phrases do not necessarily refer to the same aspects. In addition, when specific features, structures or characteristics are described in conjunction with aspects, it should be understood that, whether or not explicitly described, it is within the knowledge of those skilled in the art to combine with other aspects to achieve such features, structures or characteristics.

[0023] For ease of description, spatially relative terms, such as "below," "beneath," "lower," "above," "on," "higher," etc., may be used herein to describe the relationship of one element or feature to another element or feature(s) as illustrated in the accompanying drawings. The spatially relative terms are intended to encompass different orientations of the device when in use or operation in addition to the orientation depicted in the figures. The device may be otherwise oriented (rotated 90 degrees or in other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.

[0024] The terms "about," "approximately," "approximately," and the like may be used herein to indicate a value for a given quantity that may vary based on a particular technology. Based on the particular technology, the terms "about," "approximately," and the like may indicate a value for a given quantity that varies, for example, within 10% to 30% above or below the value (e.g., ±10%, ±20%, or ±30% of the value).

[0025] Aspects of the present disclosure may be implemented in hardware, firmware, software, or any combination thereof. Aspects of the present disclosure may also be implemented as instructions stored on a computer-readable medium that can be read and executed by one or more processors. A machine-readable medium may include any mechanism for storing or transmitting information in a form that can be read by a machine (e.g., a computing device). For example, a machine-readable magnetic storage medium may include a read-only memory (ROM); a random access memory (RAM); a disk storage medium; an optical storage medium; a flash memory device; an electrical, optical, acoustic, or other form of propagation signal (e.g., a carrier wave, an infrared signal, a digital signal, etc.), etc. In addition, firmware, software, routines, and / or instructions may be described herein as performing certain actions. However, it should be understood that such descriptions are merely for convenience, and that these actions are generated by a computing device, a processor, a controller, or other devices that execute firmware, software, routines, instructions, etc. The term "machine-readable medium" may be interchangeable with similar terms, such as "computer program product", "computer-readable medium", "non-transitory computer-readable medium", etc. The term "non-transitory" may be used herein to characterize one or more forms of computer-readable media other than transient propagation signals.

[0026] However, before describing these aspects in further detail, it is instructive to present an example environment in which aspects of the disclosure may be implemented.

[0027] Exemplary Lithography System

[0028] Figure 1A and Figure 1B A lithographic apparatus 100 and a lithographic apparatus 100' are shown, respectively, in which aspects of the present disclosure may be implemented. The lithographic apparatus 100 and the lithographic apparatus 100' each include the following components: an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., deep ultraviolet or extreme ultraviolet radiation); a support structure (e.g., a mask stage) MT configured to support a patterning device (e.g., a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device MA; and a substrate stage (e.g., a wafer stage) WT configured to hold a substrate (e.g., a wafer coated with resist) W and connected to a second positioner PW configured to accurately position the substrate W. The lithographic apparatus 100 and 100' also have a projection system PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion (e.g., including one or more dies) C of the substrate W. In the lithographic apparatus 100, the patterning device MA and the projection system PS are reflective. In the lithographic apparatus 100', the patterning device MA and the projection system PS are of the transmissive type.

[0029] The illumination system IL may include various types of optical components, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping or controlling the radiation beam B.

[0030] The support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA relative to a reference frame, the design of at least one of the lithographic apparatuses 100 and 100', and other conditions, such as whether the patterning device MA is held in a vacuum environment. The support structure MT may employ mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA. The support structure MT may be a frame or a stage, for example, which may be fixed or movable. By using sensors, the support structure MT may ensure that the patterning device MA is in a desired position, for example relative to the projection system PS.

[0031] The term “patterning device” MA is to be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section so as to create a pattern in a target portion C of a substrate W. The pattern imparted to the radiation beam B may correspond to a specific functional layer of a device to be created in the target portion C to form an integrated circuit.

[0032] The pattern forming device MA may be a transmissive type (e.g. Figure 1B lithographic apparatus 100 ′) or a reflective type (such as Figure 1A 100). Examples of pattern forming devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels. Masks are well known in lithography and include mask types such as binary masks, alternating phase shift masks, or attenuated phase shift masks, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incident radiation beam in different directions. The tilted mirrors impart a pattern to the radiation beam B reflected by the matrix of small mirrors.

[0033] The term "projection system" PS may include 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 used or other factors such as the use of an immersion liquid or the use of a vacuum on the substrate W. A vacuum environment may be used for EUV or electron beam radiation, as other gases may absorb too much radiation or electrons. A vacuum environment may therefore be provided to the entire beam path by means of vacuum walls and a vacuum pump.

[0034] The lithographic apparatus 100 and / or the lithographic apparatus 100' may be of a type having two (dual stage) or more substrate tables WT (and / or two or more mask tables). In such a "multi-stage" machine, the additional substrate tables WT may be used in parallel, or preparatory steps may be performed on one or more tables while one or more other substrate tables WT are being used for exposure. In some cases, the additional tables may not be substrate tables WT.

[0035] The lithographic apparatus may also be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index (e.g., water) so as to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, such as the space between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of a projection system. The term "immersion" as used herein does not mean that structures such as substrates must be immersed in liquid. For example, during exposure, the liquid may be located between the projection system and the substrate.

[0036] refer to Figure 1A and Figure 1B , the illuminator IL receives a radiation beam from a radiation source SO. When the source SO is an excimer laser, the source SO and the lithographic apparatus 100, 100' may be separate physical entities. In this case, the source SO is not considered to constitute part of the lithographic apparatus 100 or 100', and the radiation beam B is delivered to the lithographic apparatus 100 or 100' by means of a beam delivery system BD (in the case of a beam delivery system BD) comprising, for example, suitable directional mirrors and / or a beam expander. Figure 1B The radiation system may include a source SO, an illuminator IL and / or a beam delivery system BD.

[0037] The illuminator IL may comprise an adjuster AD (at Figure 1B Typically, at least the outer radial extent and / or the inner radial extent (commonly referred to as "σ-outer" and "σ-inner", respectively) of the intensity distribution in a pupil plane of the illuminator can be adjusted. Furthermore, the illuminator IL may include various other components (in Figure 1B The illuminator IL may be used to condition the radiation beam B so as to have a desired uniformity and intensity distribution in its cross-section.

[0038] refer to Figure 1A , the radiation beam B is incident on and patterned by the pattern forming device (e.g., mask) MA, which is held on the support structure (e.g., mask table) MT. In the lithographic apparatus 100, the radiation beam B is reflected from the pattern forming device (e.g., mask) MA. After having been reflected from the pattern forming device (e.g., mask) MA, the radiation beam B passes through a projection system PS, which focuses the radiation beam B onto a target portion C of a substrate W. With the aid of a second positioner PW and a position sensor IF2 (e.g., an interferometer device, a linear 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, a first positioner PM and a further position sensor IF1 can be used to accurately position the pattern forming device (e.g., mask) MA relative to the path of the radiation beam B. The patterning device (eg, mask) MA and the substrate W may be aligned using mask alignment marks M1 , M2 and substrate alignment marks P1 , P2 .

[0039] refer to Figure 1B, the radiation beam B is incident on and patterned by the patterning device (e.g., mask MA), which is held on the support structure (e.g., mask table MT). Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. The projection system has a pupil PPU that is conjugate to the illumination system pupil IPU. Portions of the radiation originate from the intensity distribution at the illumination system pupil IPU and traverse the mask pattern without being affected by diffraction at the mask pattern, and produce an image of the intensity distribution at the illumination system pupil IPU.

[0040] The projection system PS projects an image of the mask pattern MP onto a photoresist layer coated on the substrate W, wherein the image is formed by a diffraction beam generated from the mask pattern MP by radiation of the intensity distribution. For example, the mask pattern MP may include an array of lines and spaces. The diffraction of radiation different from the zero-order diffraction at the array produces a diverted diffraction beam having a direction change in a direction perpendicular to the lines. The undiffracted beam (i.e., the so-called zero-order diffraction beam) traverses the pattern without any change in the propagation direction. The zero-order diffraction beam passes through an upper lens or upper lens group of the projection system PS located upstream of the conjugate pupil PPU of the projection system PS to reach the conjugate pupil PPU. A portion of the intensity distribution in the plane of the conjugate pupil PPU and associated with the zero-order diffraction beam is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL. The aperture device PD is, for example, arranged at or approximately located at a plane including the conjugate pupil PPU of the projection system PS.

[0041] The projection system PS is arranged to capture (e.g., using a lens or lens group L) a zero-order diffraction beam, a first-order diffraction beam, and / or higher-order diffraction beams (not shown). In some aspects, dipole illumination for imaging a line pattern extending in a direction perpendicular to the line can be used to exploit the resolution enhancement effect of dipole illumination. For example, the first-order diffraction beam interferes with the corresponding zero-order diffraction beam at the level of the wafer W to produce an image of the line pattern MP with the highest possible resolution and process window (i.e., the available depth of focus combined with the tolerable exposure dose deviation). In some aspects, astigmatic aberrations can be reduced by providing radiation poles (not shown) in opposite quadrants of the illumination system pupil IPU. In addition, in some aspects, astigmatic aberrations can be reduced by blocking the zero-order beam associated with the radiation poles in the opposite quadrant in the conjugate pupil PPU of the projection system. This is described in more detail in US 7,511,799 B2, issued on March 31, 2009, the entire contents of which are incorporated herein by reference.

[0042] With the aid of a second positioner PW and a position sensor IFD (e.g. an interferometer arrangement, a linear encoder, or a capacitive sensor), the substrate table WT can be accurately moved (e.g. to position a different target portion C in the path of the radiation beam B). Similarly, the first positioner PM and another position sensor (not in use) can be moved (e.g. after mechanical retrieval from a mask library or during scanning). Figure 1B ) is used to accurately position the mask MA relative to the path of the radiation beam B.

[0043] Typically, movement of the mask table MT may be achieved with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming part of the first positioner PM. Similarly, movement of the substrate table WT may be achieved 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 mask table MT may be connected to a short-stroke actuator, or may be fixed. The mask MA and substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. Although the (illustrated) substrate alignment marks occupy dedicated target portions, the substrate alignment marks may be located in the spaces between multiple target portions (these are referred to as scribe alignment marks). Similarly, where more than one die is provided on the mask MA, the mask alignment marks may be located between these dies.

[0044] The mask table MT and the patterning device MA may be located in a vacuum chamber, wherein an in-vacuum robot IVR may be used to move the patterning device (such as a mask) into and out of the vacuum chamber. Alternatively, when the mask table MT and the patterning device MA are outside the vacuum chamber, an out-of-vacuum robot may be used for various transport operations similar to the in-vacuum robot IVR. Both the in-vacuum robot and the out-of-vacuum robot should be calibrated to smoothly transfer any payload (e.g., a mask) to the fixed kinematic mount of the transfer station.

[0045] The lithographic apparatus 100 and 100 may be used in at least one of the following modes:

[0046] 1. In step mode, the support structure (e.g. mask table) MT and the substrate table WT remain substantially stationary while an entire pattern imparted to the radiation beam is projected at once onto a target portion C (i.e. a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed.

[0047] 2. In scan mode, the support structure (e.g. mask table) MT and substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e. a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure (e.g. mask table) MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS.

[0048] 3. In another mode, the support structure (e.g. mask table) MT holding the programmable patterning device is held substantially fixed and the substrate table WT is moved or scanned, while a pattern imparted to the radiation beam B is projected onto a target portion C. A pulsed radiation source SO may be employed, and the programmable patterning device updated as required after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation may be readily applied in maskless lithography using a programmable patterning device, such as a programmable mirror array.

[0049] Combinations and / or variations of the described modes of use or entirely different modes of use may also be employed.

[0050] In another aspect, the lithographic apparatus 100 includes an extreme ultraviolet (EUV) source configured to generate an EUV radiation beam for EUV lithography. Typically, the EUV source is configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.

[0051] Figure 2The lithographic apparatus 100 is shown in more detail and includes the source collector apparatus SO, the illumination system IL and the projection system PS. The source collector apparatus SO is constructed and arranged so that a vacuum environment in an enclosure 220 of the source collector apparatus SO can be maintained. The plasma 210 emitting EUV radiation can be formed by a discharge-generated plasma source. In some aspects, an excited plasma of tin (Sn) is provided (e.g., via laser excitation) to generate EUV radiation.

[0052] Radiation emitted by EUV radiation emitting plasma 210 is transferred from source chamber 211 to collector chamber 212 via an optional gas barrier or contaminant trap 230 (also referred to as a contaminant barrier or fin trap in some cases) positioned in or behind an opening in source chamber 211. The contaminant trap 230 may include a channel structure. The contaminant trap 230 may also include a gas barrier, or a combination of a gas barrier and a channel structure. The contaminant trap 230, as further noted herein, includes at least a channel structure.

[0053] The collector chamber 211 may include a radiation collector CO which may be a so-called grazing incidence collector. The radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation traversing the collector CO may be reflected off a grating spectral filter 240 to be focused at a virtual source point INIF. The virtual source point INIF is often referred to as an intermediate focus, and the source collector device is arranged so that the intermediate focus INTF is located at or near an opening 219 in the enclosure structure 220. The virtual source point INTF is an image of the plasma 210 emitting EUV radiation. The grating spectral filter 240 is particularly used to suppress infrared (IR) radiation.

[0054] The radiation then traverses the illumination system IL which may include a faceted field mirror arrangement 222 and a faceted pupil mirror arrangement 224 arranged to provide a desired angular distribution of the radiation beam 221 at the patterning device MA, and a desired uniformity of radiation intensity at the patterning device MA. When the radiation beam 221 is reflected at the patterning device MA held by the support structure MT, a patterned beam 226 is formed, and the patterned beam 226 is imaged by the projection system PS via reflective elements 228, 229 onto a substrate W held by a wafer stage or substrate table WT.

[0055] There may typically be more elements than shown in the illumination optics unit IL and the projection system PS. A grating spectral filter 240 may optionally be present, depending on the type of lithographic apparatus. In addition, there may be more than Figure 2 More mirrors than the one shown in FIG. 1 may be present in the projection system PS. Figure 2 The reflective elements shown in FIG. 5 may be increased by one to six additional reflective elements.

[0056] Collector optics CO (eg Figure 2 254 and 255 are depicted as a nested collector with grazing incidence reflectors 253, 254 and 255 as just one example of a collector (or collector mirror). The grazing incidence reflectors 253, 254 and 255 are arranged axially symmetrically around the optical axis O, and this type of collector optics CO is preferably used in conjunction with a discharge produced plasma source (often referred to as a DPP source).

[0057] Exemplary Lithography Cell

[0058] Figure 3 A lithography unit 300, sometimes also referred to as a lithography cell or cluster, according to some aspects is shown. The lithography apparatus 100 or 100' may form part of the lithography unit 300. The lithography unit 300 may also include one or more devices for performing pre-exposure processes and post-exposure processes on a substrate. Conventionally, these devices include: a spin coater SC for depositing a resist layer, a developer DE for developing the exposed resist, a chill plate CH, and a bake plate BK. A substrate conveyor or robot RO picks up a substrate from an input / output port I / O1, I / O2, moves the substrate between different process devices, and transfers the substrate to a feed station LB of the lithography apparatus 100 or 100'. These devices are generally collectively referred to as a track or coating and developing system, and are under the control of a track or coating and developing system control unit TCU, which is itself controlled by a management control system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Therefore, different devices can be operated to maximize production volume and processing efficiency.

[0059] Exemplary Inspection Equipment

[0060] In order to control the lithography process to accurately place the device features on the substrate, alignment marks are usually provided on the substrate, and the lithography apparatus includes one or more inspection devices to accurately position the marks on the substrate. These alignment devices are effectively position measurement devices. Different types of marks and different types of alignment devices and / or systems are known from different times and different manufacturers. One type of system widely used in current lithography apparatus is based on a self-reference interferometer as described in U.S. Patent No. 6,961,116 (den Boef et al.). Typically, the marks are measured separately to obtain the X position and the Y position. However, the combined X and Y measurements can be performed using the techniques described in U.S. Publication No. 2009 / 195768 A (Bijnen et al.). The entire contents of these two disclosures are incorporated herein by reference.

[0061] Figure 4A A cross-sectional view of an inspection apparatus 400 is shown, which can be implemented as part of a lithographic apparatus 100 or 100', according to some aspects. In some aspects, the inspection apparatus 400 can be configured to align a substrate (e.g., substrate W) relative to a patterning device (e.g., patterning device MA). The inspection apparatus 400 can also be configured to detect positions of alignment marks on the substrate, and use the detected positions of the alignment marks to align the substrate relative to the patterning device or other components of the lithographic apparatus 100 or 100'. Such alignment of the substrate can ensure that one or more patterns are accurately exposed on the substrate.

[0062] The terms "inspection equipment", "measurement system", etc. may be used herein to refer to, for example, a device for measuring properties of a structure (e.g., an overlay sensor, a critical dimension sensor, etc.), or a device or system used in a lithography device to check the alignment of a wafer (e.g., an alignment sensor), etc.

[0063] In some aspects, the inspection device 400 may include an illumination system 412, a beam splitter 414, an interferometer 426, a detector 428, a beam analyzer 430, and a processor 432. The illumination system 412 may be configured to provide an electromagnetic narrowband radiation beam 413 having one or more passbands. In one example, the one or more passbands may be within a spectrum of wavelengths between about 500 nm and about 900 nm. In another example, the one or more passbands may be discrete narrow passbands within a spectrum of wavelengths between about 500 nm and about 900 nm. The illumination system 412 may also be configured to provide one or more passbands having a substantially constant center wavelength (CWL) value over a long period of time (e.g., over the useful life of the illumination system 412). As discussed above, in the current alignment system, such a configuration of the illumination system 412 may help prevent the actual CWL value from drifting from the desired CWL value. And, therefore, using a constant CWL value may improve the long-term stability and accuracy of an alignment system (eg, inspection apparatus 400 ) as compared to the current alignment apparatus.

[0064] In some aspects, beam splitter 414 can be configured to receive radiation beam 413 and split radiation beam 413 into at least two radiation sub-beams. For example, radiation beam 413 can be split into radiation sub-beams 415 and 417, as shown in FIG. Figure 4A. The beam splitter 414 can also be configured to direct the radiation sub-beam 415 onto a substrate 420 placed on a platform 422. In one example, the platform 422 can be moved along a direction 424. The radiation sub-beam 415 can be configured to illuminate an alignment mark or target 418 located on the substrate 420. The alignment mark or target 418 can be coated with a radiation-sensitive film. In some aspects, the alignment mark or target 418 can have a one hundred and eighty degree (i.e., 180°) symmetry. That is, when the alignment mark or target 418 is rotated 180° around an axis of symmetry perpendicular to the plane of the alignment mark or target 418, the rotated alignment mark or target 418 can be substantially the same as the unrotated alignment mark or target 418. The target 418 on the substrate 420 can be: (a) a resist layer grating comprising bars formed of solid resist lines; or (b) a product layer grating; or (c) a composite grating stack in an overlay target structure comprising a resist grating overlaid or interlaced on a product layer grating. The bars may alternatively be etched into the substrate. Such patterns are sensitive to chromatic aberrations in the lithographic projection apparatus (particularly the projection system PL) and to illumination symmetry, and the presence of such aberrations will manifest themselves as variations in the printed grating. One in-line method for measuring line width, pitch and critical dimensions in device manufacturing utilizes a technique known as "scatterometry". Scatterometry methods are described in Raymond et al., "Multiparameter Grating Metrology Using SPIE Scatterometry," J. Vac. Sci. Tech. B, Vol. 15, No. 2, pp. 361-368 (1997) and Niu et al., "Specular Spectroscopic Scatterometry in DUV Lithography," SPIE, Vol. 3677 (1999), both of which are incorporated herein by reference in their entirety. In scatterometry, light is reflected by a periodic structure in the target, and the resulting reflection spectrum is detected at a given angle. The structure that produced the reflection spectrum is reconstructed, for example, using rigorous coupled wave analysis (RCWA) or by comparison with a library of patterns derived from simulations. Thus, scatterometry data of the printed grating is used to reconstruct the grating. The parameters of the grating, such as line width and line shape, may be input into a reconstruction process performed by the processing unit PU based on knowledge of the printing step and / or other scatterometry processes.

[0065] In some aspects, according to aspects, beam splitter 414 can also be configured to receive diffracted radiation beam 419 and split diffracted radiation beam 419 into at least two radiation sub-beams. Diffracted radiation beam 419 can be split into diffracted radiation sub-beams 429 and 439, as shown in FIG. Figure 4A As shown in .

[0066] It should be noted that even though beam splitter 414 is shown as directing radiation sub-beam 415 toward alignment mark or target 418 and directing diffracted radiation sub-beam 429 toward interferometer 426, the present disclosure is not limited thereto. Other optical arrangements may be used to obtain similar results of illuminating alignment mark or target 418 on substrate 420 and detecting an image of alignment mark or target 418.

[0067] like Figure 4A As illustrated in FIG. 4 , the interferometer 426 can be configured to receive the radiation sub-beam 417 and the diffracted radiation sub-beam 429 through the beam splitter 414. In an exemplary aspect, the diffracted radiation sub-beam 429 can be at least a portion of the radiation sub-beam 415 that can be reflected from the alignment mark or target 418. In an example of this aspect, the interferometer 426 includes any suitable set of optical elements, for example, a prismatic combination that can be configured to form two images of the alignment mark or target 418 based on the received diffracted radiation sub-beam 429. It should be understood that it is not necessary to form an image of good quality. It may be sufficient to resolve the features of the alignment mark 418. The interferometer 426 can also be configured to rotate one of the two images 180° relative to the other of the two images, and to recombinate the rotated image and the unrotated image in an interferometric manner.

[0068] In some aspects, the detector 428 can be configured to receive the recombined image via the interferometer signal 427 and detect interference caused by the recombined image when the alignment axis 421 of the inspection device 400 passes through the center of symmetry of the alignment mark or target 418 (not shown). According to exemplary aspects, such interference may be caused by the alignment mark or target 418 being 180° symmetrical and interfering constructively or destructively via the recombined image. Based on the detected interference, the detector 428 can also be configured to determine the position of the center of symmetry of the alignment mark or target 418 and thus detect the position of the substrate 420. According to an example, the alignment axis 421 can be aligned with an optical beam that is perpendicular to the substrate 420 and passes through the center of the image rotation interferometer 426. The detector 428 can also be configured to estimate the position of the alignment mark or target 418 by implementing sensor characteristics and interacting with wafer marking process variations.

[0069] In further aspects, the detector 428 determines the location of the center of symmetry of the alignment mark or target 418 by performing one or more of the following measurements:

[0070] 1. Measure the position change for each wavelength (position shift between colors);

[0071] 2. Measure the position change for each order (position shift between diffraction orders); and

[0072] 3. The position change is measured for each polarization (position shift between the polarizations).

[0073] For example, the data can be acquired using any type of alignment sensor, such as a SMASH (SMart Alignment Sensor Hybrid) sensor, as described in U.S. Pat. No. 6,961,116, which employs a self-referencing interferometer with a single detector and four different wavelengths and extracts the alignment signal in software, or Athena (Advanced Technology using High Order Alignment Enhancement), as described in U.S. Pat. No. 6,297,876, which directs each of the seven diffraction orders to a dedicated detector, both of which are incorporated herein by reference in their entirety.

[0074] In some aspects, the beam analyzer 430 can be configured to receive and determine the optical state of the diffracted radiation sub-beam 439. The optical state can be a measure of the beam wavelength, polarization, or beam profile. The beam analyzer 430 can also be configured to determine the position of the platform 422 and correlate the position of the platform 422 with the position of the symmetry center of the alignment mark or target 418. In this way, the position of the alignment mark or target 418 relative to the alignment platform 422 can be accurately known, and therefore the position of the substrate 420 relative to the alignment platform 422 is known. Alternatively, the beam analyzer 430 can be configured to determine the position of the inspection device 400 or any other reference element, so that the symmetry center of the alignment mark or target 418 can be known relative to the inspection device 400 or any other reference element. The beam analyzer 430 can be a point or imaging polarimeter with some form of band selectivity. In some aspects, according to other aspects, the beam analyzer 430 can be directly integrated into the inspection device 400, or connected via several types of optical fibers: polarization-maintaining single-mode fiber, multimode fiber, or imaging fiber.

[0075] In some aspects, the beam analyzer 430 may also be configured to determine overlap data between two patterns on the substrate 420. One of the patterns may be a reference pattern on a reference layer. Another pattern may be an exposure pattern on an exposure layer. The reference layer may be an etch layer already present on the substrate 420. The reference layer may be generated by a reference pattern exposed on the substrate by the lithography apparatus 100 and / or 100'. The exposure layer may be an exposed resist layer adjacent to the reference layer. The exposure layer may be generated by an exposure pattern exposed on the substrate 420 by the lithography apparatus 100 or 100'. The exposure pattern on the substrate 420 may correspond to the movement of the substrate 420 caused by the platform 422. In some aspects, the measured overlap data may also indicate an offset between the reference pattern and the exposure pattern. The measured overlap data may be used as calibration data to calibrate the exposure pattern exposed by the lithography apparatus 100 or 100', so that after calibration, the offset between the exposure layer and the reference layer may be minimized.

[0076] In some aspects, the beam analyzer 430 can also be configured to determine a model of the product stack profile of the substrate 420, and can be configured to measure the overlay, critical dimension, and focus of the target 418 in a single measurement. The product stack profile contains information about the stack product such as alignment marks, the target 418, or the substrate 420, and can include optical signature measurements caused by marking process variations, which are a function of illumination variations. The product stack profile can also include product raster profiles, mark stack profiles, and mark asymmetry information. An example of a beam analyzer 430 is the Yieldstar manufactured by ASML of Veldhoven, The Netherlands. TM , as described in U.S. Patent No. 8,706,442, which is incorporated herein by reference in its entirety. The beam analyzer 430 may also be configured to process information related to specific properties of the exposure pattern in the layer. For example, the beam analyzer 430 may process: an overlay parameter (indicating the accuracy of positioning of the layer relative to the previous layer on the substrate, or the accuracy of positioning of the first layer relative to a mark on the substrate), a focus parameter, and / or a critical dimension parameter of the image depicted in the layer (e.g., line width and its variation). Other parameters are image parameters related to the quality of the image of the depicted exposure pattern.

[0077] In some aspects, a detector array (not shown) can be connected to the beam analyzer 430 and allow the possibility of accurate stack profile detection, as discussed below. For example, the detector 428 can be a detector array. There may be multiple options for the detector array: a multimode fiber bundle, a discrete pin detector per channel, or a CCD or CMOS (linear) array. For stability reasons, the use of a multimode fiber bundle allows any dissipative elements to be remotely located. Discrete pin detectors provide a larger dynamic range, but each discrete pin detector requires a separate preamplifier. Therefore, the number of elements is limited. The CCD linear array provides many elements that can be read at high speed and are particularly noteworthy when using phase step detection.

[0078] In some aspects, the second beam analyzer 430' can be configured to receive and determine the optical state of the diffracted radiation sub-beam 429, such as Figure 4B . The optical state may be a measure of the beam wavelength, polarization, or beam profile. The second beam analyzer 430' may be identical to the beam analyzer 430. Alternatively, the second beam analyzer 430' may be configured to perform one or more functions of the beam analyzer 430, such as determining the position of the platform 422, and associating the position of the platform 422 with the position of the center of symmetry of the alignment mark or target 418. In this way, the position of the alignment mark or target 418 relative to the alignment platform 422 may be accurately known, and therefore the position of the substrate 420 relative to the alignment platform 422 may be accurately known. The second beam analyzer 430' may also be configured to determine the position of the inspection device 400 or any other reference element, so that the center of symmetry of the alignment mark or target 418 may be known relative to the inspection device 400 or any other reference element. The second beam analyzer 430' may also be configured to determine the overlap data between the two patterns and a model of the product stack profile of the substrate 420. The second beam analyzer 430' may also be configured to measure the overlap, critical dimension, and focus of the target 418 in a single measurement.

[0079] In some aspects, second beam analyzer 430' may be directly integrated into inspection device 400, or second beam analyzer 430' may be connected via several types of optical fibers: polarization-maintaining single-mode fiber, multimode fiber, or imaging fiber, according to other aspects. Alternatively, second beam analyzer 430' and beam analyzer 430 may be combined to form a single analyzer (not shown) configured to receive and determine the optical state of both diffracted radiation sub-beams 429 and 439.

[0080] In some aspects, processor 432 may receive and analyze information from detector 428 and beam analyzer 430 .

[0081] Exemplary integrated optical system using metasurfaces

[0082] In some aspects, the term "throughput" can be used to characterize the rate of photolithography manufacturing. For example, throughput can refer to the rate at which photolithography manufacturing is completed on a wafer, the rate at which a wafer clears a specific preparation step and moves to the next step, etc. Throughput can be a performance indicator of a lithographic device. It is expected that the lithography system outputs as many products as possible in as little time as possible. Photolithography manufacturing can include several complex processes. Each process includes the selection of a technology that compromises between quality (e.g., sub-nanometer accuracy, high yield) and disadvantages (e.g., slower preparation, cost). An exemplary process involving improved accuracy can include inspecting printed marks on a substrate. As described above, an inspection device can be used to determine the consistency of a printed pattern on a substrate or to align a substrate to properly receive a new pattern. However, the inspection process can greatly affect the throughput (e.g., seeking higher accuracy can increase the inspection duration, resulting in reduced throughput). Other examples of integrated optical systems can be found in WO2021 / 058571 published on April 1, 2021, the entire contents of which are incorporated herein by reference.

[0083] In some aspects, multiple targets can be measured in conjunction with the lithography process. The throughput can be increased by increasing the speed of inspecting multiple targets. Although multiple inspection sensors can be implemented in parallel within the lithography equipment to speed up the inspection of multiple targets, conventional sensors used in lithography measurement may be bulky and expensive due to their bulky optics, which hinders their scalability. A solution may be to implement sensors using different operating principles, such as integrated optics. Terms such as "integrated optics", "integrated optical systems", "integrated optical circuits", "integrated photonic systems", "photonic integrated circuits", etc. may be used to refer to integrated devices that can propagate optical signals. For example, an integrated optics may include a waveguide disposed on a substrate. The waveguide may guide the optical signal to other areas of the substrate, where the optical signal may be received to be converted into measurement information. Compared to bulky free-space optics, integrated optics can be made very small and cost only a fraction of bulky free-space optics. Therefore, sensors based on integrated optics may be a scalable solution to increase the speed of inspecting multiple marks.

[0084] Figure 5 An integrated optical system 500 according to some aspects is shown. In some aspects, the integrated optical system 500 can be used to replace at least a portion of the detection branch of the inspection device 400 ( Figure 4A and Figure 4BThe term "detection branch" or the like may refer to a portion of an inspection device that includes directing and / or receiving radiation scattered from a target (eg, diffracted radiation beam 419 (eg, from target 418)). Figure 4A and Figure 4B Similarly, the term "irradiation branch" or the like may refer to a portion of an inspection device that includes a portion of a device that emits and / or directs illumination toward a target (eg, radiation sub-beam 415 ( ) toward target 418). Figure 4A and Figure 4B )) of the device. It should be understood that the illumination branch can be implemented as an integrated optical device. In some aspects, multiple parts of the illumination branch and the detection branch can be implemented on the same substrate (e.g., a shared integrated optical system).

[0085] In some aspects, the integrated optical system 500 may include grating couplers 506 and 508 (e.g., a first grating coupler and a second grating coupler) and a waveguide system 504. The elements of the integrated optical system 500 may be disposed on a substrate (not shown). The integrated optical system 500 may also include a detector 526. The detector 526 may be an integrated element or a discrete element (e.g., not integrated on a substrate). The waveguide system 504 may include a combiner 523.

[0086] In some aspects, enumerated adjectives (e.g., "first," "second," "third," etc.) can be used to distinguish similar elements without establishing an order, hierarchy, or amount (unless otherwise specified). For example, the terms "first grating coupler" and "second grating coupler" can distinguish two grating couplers without specifying a particular order, hierarchy, or upper or lower bound on the total number of grating couplers. Furthermore, the elements in the figures are not limited to any particular enumerated adjectives. For example, grating coupler 506 can be referred to as a first grating coupler in some aspects, or can be referred to as a second grating coupler in some other aspects.

[0087] In some aspects, an illumination source can generate illumination for irradiating a target (e.g., as described in reference Figure 4A and Figure 4B504 ). The target may scatter the illumination (e.g., as one or more diffraction orders, the 0th order, the ±1st order, etc.). Scattered illumination—illustrated as scattered illumination 520 and 522 (e.g., +1 and -1 diffraction orders, +2 and -2 diffraction orders, etc.) may be received at the integrated optical system 500. Scattered illumination 520 may be referred to as a first portion of scattered illumination. Scattered illumination 522 may be referred to as a second portion of scattered illumination. The grating coupler 506 may couple the scattered illumination 520 into the waveguide system 504. The grating coupler 508 may couple the scattered illumination 522 into the waveguide system 504. The combiner 523 may combine the received scattered illumination 520 and 522 (e.g., to perform interferometry). The combined illumination may be received at the detector 526. The detector 526 may generate a measurement signal based on the combined illumination.

[0088] It is instructive to consider an overview of a process for performing measurements that rely on varying properties of illumination (e.g., interferometry). Figure 4A and Figure 4B ) moves / scans, the phase of scattered illumination 520 and 522 may evolve over time due to the scanning. When scattered illumination 520 and 522 are interfered (due to combiner 523), the scanning motion of the illumination spot may cause the detected radiation at detector 526 to have an AC modulation characteristic. That is, the measurement signal generated by detector 526 may be an AC signal. The characteristics of the AC properties of the measurement signal (e.g., intensity) may be determined for target 418 ( Figure 4A and Figure 4B ) (e.g. alignment position). These characteristics may include the phase and / or amplitude of the modulation of the signal intensity. For example, the measurement signal may include information on the phase delay of the scattered radiation 520 and 522. The properties of the inspected object (e.g. the position of the object) can be determined from this.

[0089] In some aspects, optical inspection of targets on a wafer can be performed using illumination of multiple colors (or wavelengths). A given wavelength can provide information about a target that may not be readily apparent at another wavelength. As used herein, concepts such as "multi-wavelength," "multi-photon frequency," "multi-parameter value," and the like can be used to characterize narrowband values ​​in related properties or parameters. In a non-limiting example of a wavelength parameter, a first wavelength can be characterized as comprising a narrowband having a first center wavelength. A second wavelength can similarly be characterized as comprising a narrowband having a second center wavelength. The characterization that a first wavelength is different from a second wavelength can be interpreted as the first center wavelength being different from the second center wavelength.

[0090] In some aspects, it will be appreciated that the combiner and detector can be scaled with the number of grating couplers. Figures 6 to 9An implementation with an additional grating coupler is described.

[0091] In some aspects, using multiple wavelengths to illuminate the target can constrain the layout of the grating coupler. Figure 6 Describe some examples of constraints.

[0092] Figure 6 An integrated optical system 600 according to some aspects is shown. In some aspects, the integrated optical system 600 may include an integrated optical system similar to the reference Figure 5 The structure and function of the integrated optical system 500 are described in detail. Therefore, unless otherwise stated, Figure 5 The description of the elements can also be applied to Figure 6 Corresponding elements (eg, reference numerals sharing the two rightmost digits) will not be strictly reintroduced. Figure 6 Examples of such elements in may include grating couplers 606 and 608 and illuminations 620 and 622 .

[0093] In some aspects, the integrated optical system 600 can include a substrate 602 on which grating couplers 606 and 608 are disposed. The grating couplers 606 and 608 are a plurality of grating couplers, respectively. For example, the grating coupler 606 is drawn and labeled as 606-1 and 606-n ( ,exist Figure 6 ; that is, n can be two or more). Similarly, grating couplers 608 are drawn and labeled as grating couplers 608-1 and 608-2. Figure 5 In contrast, introducing additional grating couplers can take into account the sensitivity of the grating coupler structure to different wavelengths. That is, the grating coupler can be designed with a given structural size and a given shape so that (multiple) specific wavelengths of illumination can be launched into the waveguide. Different grating couplers with different structural parameters can be used for different wavelengths (for example, a first grating coupler can launch illumination with a first wavelength into the waveguide system based on a first wavelength).

[0094] In some aspects, the illumination beam 616 can be directed toward a target 618 (e.g., a grating target, an alignment mark, etc.). The interaction between the illumination beam 616 and the target 618 can scatter the illumination along these diffraction orders. The scattering angle can depend on the wavelength(s) of the illumination beam 616. For example, at a first wavelength (denoted by the suffix denoted as , the scattered illumination can be distributed between scattered illumination 620-1 and 622-1, which can be understood as + and - diffraction of the same order (e.g., +1 and -1, +2 and -2, etc.). The diffraction angles for scattered illumination 620-1 and 622-1 are denoted as At the second wavelength (suffix , the scattered illumination can be distributed between scattered illumination 620-2 and 622-2. The diffraction angle for scattered illumination 620-2 and 622-2 is represented as The scattered illumination 620-1, 620-2, 622-1, and 622-2 (eg, the first portion, the second portion, the third portion, and the fourth portion of the scattered illumination) may be launched into a waveguide system (eg, the waveguide system 504 ( Figure 5 )) for subsequent testing and analysis.

[0095] To better illustrate some of the problems and solutions, it is instructive to consider a non-limiting example where the diffraction order is constrained to be 1st order (i.e., +1 or -1). By eliminating the variability of the diffraction order (e.g., eliminating the difference in the diffraction angles associated with the 1st and 2nd orders), the variability due to wavelength can be better understood.

[0096] In some aspects, the illumination beam 616 can include multiple wavelengths. Some commercially available alignment sensors can use twelve wavelengths covering the spectrum including infrared (IR), visible light, and ultraviolet (UV) to check alignment marks. When using a broad spectrum of wavelengths, the target 618 can scatter the illumination along a wide range of diffraction angles. In excess of Figure 6 The angle shown in Problems may arise at large diffraction angles of. The placement of the grating couplers depends on the diffraction angle. Some locations of the grating couplers may expand the footprint of the integrated optical system 600, which is contrary to the goal of miniaturizing the inspection system. Another problem may be that some grating couplers may need to be positioned so close that some of the grating couplers conflict (overlap). When the diffraction angles of the two wavelengths are close and the cross-section of the beam of each wavelength at the target is large (for example, when the two wavelengths are similar and / or the grating pitch is large, and This may occur when the wavelengths are similar. This results in an overlap between the beams of the two wavelengths. Aspects of the present disclosure address such issues arising from the use of multiple wavelengths.

[0097] Figure 7 An integrated optical system 700 is shown according to some aspects. In some aspects, the integrated optical system 700 may include an integrated optical system similar to that of reference Figure 5 and Figure 6 The structure and function of the integrated optical systems 500 and 600 described herein are described herein. Therefore, unless otherwise stated, Figure 5 and Figure 6 The description of the elements can also be applied to Figure 7 Corresponding elements (eg, reference numerals sharing the two rightmost digits) will not be strictly reintroduced. Figure 7 Examples of such elements in may include substrate 702, grating couplers 706-1, 706-2, 708-1, and 708-2, illumination beam 716, target 718, and scattered illumination 720-1, 720-2, 722-1, and 722-2.

[0098] In some aspects, the integrated optical system 700 may include a microstructured illumination modifier 710, which includes microstructured regions 712-1, 712-2, 714-1, and 714-2 (as previously described, the suffixes 1, 2, ..., n may indicate associations with different wavelengths). The microstructured illumination modifier 710 may be disposed on a substrate 702. The microstructured illumination modifier 710 may be disposed between the substrate 702 and a target 718. The microstructured region 712-1 may be disposed at a diffraction angle The structure of the microstructured region 712-1 can be designed so that the scattered illumination 720-1 is redirected toward the grating coupler 706-1. The structure of the microstructured region 712-2 can be designed so that the scattered illumination 720-2 is redirected toward the grating coupler 706-2. The structure of the microstructured region 714-1 can be designed so that the scattered illumination 722-1 is redirected toward the grating coupler 708-1. The structure of the microstructured region 714-2 can be designed so that the scattered illumination 722-2 is redirected toward the grating coupler 708-2. In other words, the first microstructured region, the second microstructured region, the third microstructured region, and the fourth microstructured region can direct corresponding portions of the first portion, the second portion, the third portion, and the fourth portion of the scattered illumination to corresponding grating couplers of the first grating coupler, the second grating coupler, the third grating coupler, and the fourth grating coupler.

[0099] In some aspects, microstructured regions 712-1, 712-2, 714-1, and 714-2 can include gratings designed specifically for the respective wavelengths used in illumination beam 716. For example, the microstructured regions can be gratings or metasurfaces. For gratings, the grating line width and / or spacing can be comparable to the order of the corresponding wavelengths in illumination beam 716.

[0100] Figure 8 An integrated optical system 800 is shown according to some aspects. In some aspects, the integrated optical system 800 may include an integrated optical system similar to that of reference Figures 5 to 7 The structure and function of the integrated optical systems 500, 600 and 700 are described in detail. Therefore, unless otherwise stated, Figures 5 to 7 The description of the elements can also be applied to Figure 8Corresponding elements (eg, reference numerals sharing the two rightmost digits) will not be strictly reintroduced. Figure 8 Examples of such elements in may include substrate 802, grating couplers 806-1, 806-2, 808-1, and 808-2, microstructured illumination modulator 810, microstructured regions 812-1, 812-2, 814-1, and 814-2, illumination beam 816, target 818, scattered illumination 820-1, 820-2, 822-1, and 822-2.

[0101] In some respects, Figure 7 Compared with the two wavelengths in the figure, Figure 8 The number of wavelengths n illustrated in FIG has been increased to 3 (non-limiting example; more wavelengths may be used). Therefore, additional grating couplers are provided on substrate 802, such as grating couplers 806-3 and 808-3 (806-n and 808-n, where ). The diffraction angle associated with the third wavelength is expressed by express.

[0102] In some aspects, the microstructured illumination modulator 810 can be a metasurface array, and the microstructured region can be a metasurface region. The metasurface can include a spatially varying metasurface. The metasurface is a form of metamaterial. Metamaterials are a class of functional materials designed using micron and / or nanometer-scale patterns or structures. The structural pattern can affect the illumination so as to interact with the metamaterial in a manner different from conventional non-patterned materials (an example of interaction with conventional non-patterned materials is refraction at a glass interface). Some examples of micron-scale and nanometer-scale patterns for metasurfaces are described with reference to FIG. 10.

[0103] In some aspects, the structure of the metasurface can be designed to adjust the phase, amplitude, and / or polarization of the illumination received at the metasurface. The metasurface can control the direction of the received radiation based on the adjustment of the phase, amplitude, and / or polarization of the incident beam.

[0104] In some aspects, the use of microstructured regions can avoid the use of bulky lenses to adjust the illumination. In traditional optical sensors, bulky optical devices such as lenses tend to increase the size of the sensor, which is contrary to the goal of miniaturization. Because the metasurface can change the phase, amplitude and / or polarization of the illumination in a predictable manner, the metasurface can adjust the illumination (e.g., collimation, focusing, phase correction, optical aberration correction, etc.) without relying on bulky optical devices. That is, in some aspects, no lens is provided between the microstructured illumination modulator 810 and the target 810.

[0105] In some aspects, the microstructured illumination modifier 810 can be disposed on the substrate 802. The microstructured illumination modifier 810 can include a transparent bulk material having a thickness such that a space for illumination propagation is formed between the microstructured illumination modifier 810 and the substrate 802. The microstructured regions 812-1, 812-2, 812-3, 814-1, 814-2, and 814-3 can include a metasurface that directs scattered radiation 820-1, 820-2, 820-3, 822-1, 822-2, and 822-3 toward corresponding ones of the grating couplers 806-1, 806-2, 806-3, 808-1, 808-2, and 808-3, respectively.

[0106] Fig. 9 An integrated optical system 900 is shown according to some aspects. In some aspects, the integrated optical system 900 may include an integrated optical system similar to that of reference Figures 5 to 8 The structures and functions of the integrated optical systems 500, 600, 700 and 800 are described in detail. Therefore, unless otherwise stated, Figures 5 to 8 The description of the elements can also be applied to Fig. 9 Corresponding elements (eg, reference numerals sharing the two rightmost digits) will not be strictly reintroduced. Fig. 9 Examples of such elements in can include substrate 902, grating couplers 906-1, 906-2, 906-3, 908-1, 908-2 and 908-3, microstructured illumination modulator 910, microstructured regions 912-1, 912-2, 912-3, 914-1, 914-2 and 914-3, illumination beam 916, target 918, scattered illumination 920-1, 920-2, 920-3, 922-1, 922-2 and 922-3.

[0107] In some aspects, the microstructured illumination modulator 910 can be designed to direct and / or split the illumination based on the polarization of the illumination. Each of the scattered illumination 920-1, 920-2, 920-3, 922-1, 922-2, and 922-3 can be polarized in a given direction. The interaction between the scattered illumination 920-1, 920-2, 920-3, 922-1, 922-2, and 922-3 and the microstructured areas 912-1, 912-2, 912-3, 914-1, 914-2, and 914-3 can cause the scattered illumination 920-1, 920-2, 920-3, 922-1, 922-2, and 922-3 to be split into two. The separated scattered illumination can be separated into orthogonally polarized components.

[0108] In some aspects, since the splitting of the polarization components results in doubling of the illumination paths, the number of grating couplers is doubled (e.g., with Figure 8The six grating couplers shown in Figure 2 are compared to Fig. 9 900). Additional grating couplers are indicated by primary labels (e.g., grating couplers 906-1', 906-2', 906-3', 908-1', 908-2', and 908-3'). In this way, the metasurface can be used to design the direction of the scattered illumination. In turn, the designer of the integrated optical system 900 has greater freedom in terms of optimal placement of the grating couplers and the ability to make the integrated optical system 900 as compact as possible.

[0109] Figures 5 to 9 The figure shows an interferometric inspection system analyzing inputs from two opposite diffraction orders (e.g., +1 and -1). However, the present disclosure is not limited to such paired detection. For example, the microstructured illumination modulator can also be implemented without the left side of the pairing grating coupler. As a non-limiting example, the left side of the pairing grating coupler can also be implemented without the left side of the pairing grating coupler. Figure 8 818 (e.g., implementing grating couplers 806-1, 806-2, and / or 806-3 and microstructured regions 812-1, 812-2, and / or 812-3, while omitting the grating coupler and metasurface region on the left side of target 818).

[0110] In some aspects, the ability to optically inspect a target using different illumination parameters (e.g., different wavelengths and / or polarizations) simultaneously allows for increased throughput by reducing inspection time. For example, a slower optical inspection method may involve using illumination beams 916 that cycle through different wavelengths one after the other.

[0111] Fig. 10A , Fig. 10B , Fig. 10C and Fig. 10D 1 shows a periodic structure for a grating coupler according to some aspects. In some aspects, the grating coupler may include a periodic block or line ( Fig. 10A ). The grating coupler may include a sawtooth periodic structure ( Fig. 10B ). The grating coupler may include a composite periodic structure having a unit cell and additional structural features within the unit cell ( Fig. 10C ). Fig. 10D Similar to Fig. 10A , but with a smaller periodicity. The pitch of the periodic structure (or unit cell) Can be used with one of the wavelengths used in optical inspection operations (or more wavelengths) equivalent.

[0112] Fig.11A and Fig. 11BUnit cell 1124 of a metasurface according to some aspects is shown. In some aspects, unit cell 1124 can include unit cell structures 1126 and 1128 (e.g., a first unit cell structure and a second unit cell structure). Unit cell structures 1126 and 1128 can have a shape and volume of a rectangular prism, respectively. Unit cell structures 1126 and 1128 are not limited to rectangular geometries. For example, the geometries can be elliptical, asymmetric, etc. Unit cell 1124 is not limited to two substructures. For example, there can be one or more structures (e.g., three structures). The shape and number of structures can be designed to inhibit a desired interaction between the metasurface and incident illumination). Unit cell structure 1126 can have a height ,length and width The unit cell structure 1128 may have a height (eg, equal to or different from ),length and width The unit cell structure 1126 may have a size different from that of the unit cell structure 1128. The unit cell structures 1126 and 1128 may be separated by a gap. One or both of the unit cell structures 1126 and 1128 may be at an angle relative to the plane of the metasurface. The unit cells 1124 can be iterated across the entire metasurface or across the metasurface to form a periodic structure.

[0113] These embodiments can be further described using the following aspects:

[0114] 1. An inspection system, comprising:

[0115] An integrated optical system configured to receive, direct, and couple first, second, third, and fourth portions of illumination scattered by a target, the first, second, third, and fourth portions having respective first, second, third, and fourth wavelengths, the integrated optical system comprising:

[0116] substrate;

[0117] a waveguide system disposed on the substrate;

[0118] a first grating coupler disposed on the substrate and configured to launch the first portion into the waveguide system based on the first wavelength;

[0119] a second grating coupler disposed on the substrate and configured to launch the second portion into the waveguide system based on the second wavelength, the first wavelength and the second wavelength being the same;

[0120] a third grating coupler disposed on the substrate and configured to launch the third portion into the waveguide system based on the third wavelength, the first wavelength and the third wavelength being different; and

[0121] a fourth grating coupler disposed on the substrate and configured to launch the fourth portion into the waveguide system based on the fourth wavelength, the third wavelength and the fourth wavelength being the same;

[0122] a first detector configured to receive a combination of the first portion and the second portion via the waveguide system and to generate a first measurement signal comprising information of a phase delay of the first portion and the second portion;

[0123] a second detector configured to receive a combination of the third portion and the fourth portion via the waveguide system and to generate a second measurement signal comprising information of a phase delay of the third portion and the fourth portion; and

[0124] A microstructured illumination adjuster, comprising a first microstructured area, a second microstructured area, a third microstructured area and a fourth microstructured area, wherein the first microstructured area, the second microstructured area, the third microstructured area and the fourth microstructured area are configured to guide corresponding parts of the first part, the second part, the third part and the fourth part to corresponding grating couplers of the first grating coupler, the second grating coupler, the third grating coupler and the fourth grating coupler.

[0125] 2. The inspection system according to aspect 1, further comprising:

[0126] A processor configured to:

[0127] analyzing the first and second measurement signals; and

[0128] The position of the target is determined based on information of the phase delays of the first portion, the second portion, the third portion, and the fourth portion.

[0129] 3. The inspection system of aspect 1, wherein the inspection system is an optical system configured to:

[0130] directing radiation toward the target to generate the first portion, the second portion, the third portion, and the fourth portion; and

[0131] The directed illumination is scanned across the target.

[0132] 4. The inspection system according to aspect 1, wherein:

[0133] The integrated optical system is further configured to receive, direct, and couple fifth and sixth portions of the illumination scattered by the target, the fifth and sixth portions having respective fifth and sixth wavelengths;

[0134] The integrated optical system further comprises:

[0135] a fifth grating coupler disposed on the substrate and configured to launch the fifth portion into the waveguide system based on the fifth wavelength, the fifth wavelength being different from the first wavelength and the third wavelength; and

[0136] a sixth grating coupler disposed on the substrate and configured to launch the sixth portion into the waveguide system based on the sixth wavelength, the fifth wavelength and the sixth wavelength being the same;

[0137] The inspection system further comprises a third detector configured to receive a combination of the fifth portion and the sixth portion via the waveguide system and to generate a third measurement signal comprising information of a phase delay of the fifth portion and the sixth portion; and

[0138] The microstructured illumination modulator further includes fifth and sixth microstructured regions configured to direct corresponding ones of the fifth and sixth portions to corresponding ones of the fifth and sixth grating couplers.

[0139] 5. The inspection system of clause 1, wherein at least the first microstructured region of the microstructured illumination modulator is polarization sensitive and configured to split and direct illumination based on polarization.

[0140] 6. The inspection system of clause 1, wherein the first, second, third, and fourth microstructured regions are gratings.

[0141] 7. The inspection system of aspect 1, wherein the microstructured illumination modulator is a metasurface array, and the first, second, third, and fourth microstructured regions are metasurface regions.

[0142] 8. An inspection system according to aspect 7, wherein the metasurface region includes a periodic structure, and the periodic structure is configured to adjust the phase, amplitude and / or polarization of the first part, the second part, the third part and the fourth part.

[0143] 9. An inspection system according to aspect 8, wherein the metasurface region is configured to control the directions of the first portion, the second portion, the third portion and the fourth portion based on the adjustment of the phase, amplitude and / or polarization.

[0144] 10. An inspection system according to aspect 7, wherein the metasurface region is configured to control the focusing of the first part, the second part, the third part and the fourth part or to control optical aberrations, and / or the metasurface region is configured to apply phase correction to the first part, the second part, the third part and the fourth part or to apply phase correction to optical aberrations.

[0145] 11. The inspection system of clause 1, wherein no lens is disposed between the microstructured illumination modulator and the target.

[0146] 12. An inspection system comprising:

[0147] An integrated optical system configured to receive, direct, and couple first and second portions of illumination scattered by a target, the first and second portions having respective first and second wavelengths, the integrated optical system comprising:

[0148] substrate;

[0149] a waveguide system disposed on the substrate;

[0150] a first grating coupler disposed on the substrate and configured to launch the first portion into the waveguide system based on the first wavelength; and

[0151] a second grating coupler disposed on the substrate and configured to launch the second portion into the waveguide system based on a second wavelength, the first wavelength and the second wavelength being different;

[0152] a first detector configured to receive the first portion via the waveguide system and to generate a first measurement signal based on an intensity of the first portion;

[0153] a second detector configured to receive the second portion via the waveguide system and to generate a second measurement signal based on an intensity of the second portion; and

[0154] A microstructured illumination modulator includes a first microstructured region and a second microstructured region configured to direct a corresponding portion of the first portion and the second portion to a corresponding grating coupler of the first grating coupler and the second grating coupler.

[0155] 13. The inspection system according to aspect 12, further comprising:

[0156] A processor configured to:

[0157] analyzing the first and second measurement signals; and

[0158] A property of the target is determined based on the intensities of the first portion and the second portion.

[0159] 14. The inspection system of aspect 12, wherein the inspection system is an optical system configured to:

[0160] directing radiation toward the target to generate the first portion and the second portion; and

[0161] The directed illumination is scanned across the target.

[0162] 15. The inspection system according to aspect 12, wherein:

[0163] The integrated optical system is further configured to receive, direct, and be scattered by the target a third portion of the illumination, the third portion having a corresponding third wavelength;

[0164] The integrated optical system further includes a third grating coupler disposed on the substrate and configured to launch the third portion into the waveguide system based on the third wavelength, the third wavelength being different from the first wavelength and the second wavelength;

[0165] The inspection system further comprises a third detector configured to receive the third portion via the waveguide system and to generate a third measurement signal based on an intensity of the third portion; and

[0166] The microstructured illumination modulator also includes a third microstructured region configured to direct the third portion to the third grating coupler.

[0167] 16. An inspection system according to aspect 12, wherein the microstructured illumination adjuster is a metasurface array, and the first microstructured area and the second microstructured area are metasurface areas including a periodic structure, and the periodic structure is configured to adjust the phase, amplitude and / or polarization of the first part and the second part.

[0168] 17. An inspection system according to aspect 16, wherein the metasurface region is configured to control the direction of the first portion and the second portion based on adjustment of the phase, amplitude and / or polarization.

[0169] 18. An inspection system according to aspect 16, wherein the metasurface region is configured to control the focusing of the first portion and the second portion, and / or apply phase correction to the first portion and the second portion.

[0170] 19. The inspection system of clause 12, wherein no lens is disposed between the microstructured illumination modulator and the target.

[0171] 20. A lithographic apparatus comprising:

[0172] an illumination system configured to illuminate a pattern forming device;

[0173] a projection system configured to project an image of the pattern onto a substrate; and

[0174] An inspection system, the inspection system comprising:

[0175] an integrated optical system configured to receive, direct, and couple first and second portions of illumination scattered by a target on the substrate, the first and second portions having respective first and second wavelengths, the integrated optical system comprising:

[0176] substrate;

[0177] a waveguide system disposed on the substrate;

[0178] a first grating coupler disposed on the substrate and configured to launch the first portion into the waveguide system based on the first wavelength; and

[0179] a second grating coupler disposed on the substrate and configured to launch the second portion into the waveguide system based on a second wavelength, the first wavelength and the second wavelength being different;

[0180] a first detector configured to receive the first portion via the waveguide system and to generate a first measurement signal based on an intensity of the first portion;

[0181] a second detector configured to receive the second portion via the waveguide system and to generate a second measurement signal based on an intensity of the second portion; and

[0182] A microstructured illumination modulator includes a first microstructured region and a second microstructured region configured to direct a corresponding portion of the first portion and the second portion to a corresponding grating coupler of the first grating coupler and the second grating coupler.

[0183] The terms "radiation", "beam", "light", "irradiation", and the like may be used herein to refer to one or more types of electromagnetic radiation, including ultraviolet (UV) radiation (e.g., having a wavelength λ of 365 nm, 355 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and extreme ultraviolet (EUV or soft X-ray) radiation (e.g., having a wavelength in the range of 5 nm to 20 nm, such as, for example, a wavelength of 13.5 nm), or hard X-rays operating at wavelengths less than 5 nm, and particle beams (such as ion beams or electron beams). Generally, radiation having wavelengths between about 400 nm and about 700 nm is considered visible radiation; radiation having wavelengths between about 780 nm and 3000 nm (or greater) is considered IR radiation. UV refers to radiation having wavelengths of about 100 nm to 400 nm. In lithography, the term "UV" also applies to wavelengths that can be produced by mercury discharge lamps: G line 436 nm; H line 405 nm; and / or I line 365 nm. Vacuum UV or VUV (i.e., UV absorbed by gases) refers to radiation having a wavelength of about 100 nm to 200 nm. Deep UV (DUV) generally refers to radiation having a wavelength range from 126 nm to 428 nm, and in some aspects, an excimer laser can produce DUV radiation used within a lithographic apparatus. It should be understood that radiation having a wavelength in the range of, for example, 5 nm to 20 nm refers to radiation having a certain wavelength band at least partially within the range of 5 nm to 20 nm. Some alignment sensors may use wavelengths between 500 nm and 900 nm.

[0184] Although some aspects of the present disclosure are described in the context of a lithographic apparatus in a license for an IC, it should be understood that the lithographic apparatus described herein can be used for other applications, such as the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat panel displays, LCDs, thin film heads, etc. It will be understood by those skilled in the art that in the context of such alternative applications, any term "wafer" or "die" used herein can be considered as a specific example of the more general term "substrate" or "target portion", respectively. The substrate can be processed before or after exposure, for example in a track unit or a coating and development system unit (a tool that typically applies a resist layer to a substrate and develops the exposed resist) and / or a measurement unit. Where applicable, the aspects disclosed herein can be applied to such and other substrate processing tools. In addition, the substrate can be processed more than once, for example to produce a multi-layer IC, so that the term "substrate" used herein can also refer to a substrate that already contains multiple processed layers.

[0185] In addition, although some aspects of the present disclosure are described in the context of optical lithography, it should be understood that aspects of the present disclosure are not limited to optical lithography. For example, in imprint lithography, the topography in the patterning device defines the pattern produced on the substrate. The topography of the patterning device can be imprinted into a resist layer supplied to the substrate, whereby the resist is cured by applying electromagnetic radiation, heat, pressure, or a combination thereof. After the resist is cured, the patterning device is removed from the resist, leaving a pattern in the resist.

[0186] It should be understood that the phraseology or terminology herein is for the purpose of description rather than limitation, so that the phraseology or terminology in this specification will be interpreted by persons skilled in the relevant art(s) in accordance with the teachings herein.

[0187] The present disclosure has been described above with the aid of functional building blocks illustrating the implementation methods of the specified functions and their interrelationships. For ease of description, the boundaries of these functional building blocks have been arbitrarily defined in this article. As long as the specified functions and their relationships are properly performed, the boundaries of replacement can be defined. The foregoing description of specific aspects will fully reveal the general nature of the present disclosure so that others can easily modify and / or adapt to various applications of these specific aspects by applying knowledge within the technical scope of the art without departing from the overall concept of the present disclosure and without excessive experimentation. Therefore, based on the teachings and guidance proposed herein, such adaptations and modifications are intended to fall within the meaning and scope of equivalents of the disclosed aspects.

[0188] It will be understood that the "Detailed Description" section, rather than the "Summary" and "Abstract" sections, is intended to be used to interpret the claims. The "Summary" and "Abstract" sections may set forth one or more, but not necessarily all, aspects of the present disclosure as contemplated by the inventor(s), and thus are not intended to limit the present disclosure and the appended claims in any way. The breadth and scope of the protected subject matter should not be limited by any of the aspects described above, but rather should be defined in accordance with the appended claims and their equivalents.

Claims

1. An inspection system, comprising: An integrated optical system configured to receive, direct, and couple first, second, third, and fourth portions of illumination scattered by a target, the first, second, third, and fourth portions having respective first, second, third, and fourth wavelengths, the integrated optical system comprising: substrate; a waveguide system disposed on the substrate; a first grating coupler disposed on the substrate and configured to launch the first portion into the waveguide system based on the first wavelength; a second grating coupler disposed on the substrate and configured to launch the second portion into the waveguide system based on the second wavelength, the first wavelength and the second wavelength being the same; a third grating coupler disposed on the substrate and configured to launch the third portion into the waveguide system based on the third wavelength, the first wavelength and the third wavelength being different; and a fourth grating coupler disposed on the substrate and configured to launch the fourth portion into the waveguide system based on the fourth wavelength, the third wavelength and the fourth wavelength being the same; a first detector configured to receive a combination of the first portion and the second portion via the waveguide system and to generate a first measurement signal comprising information of a phase delay of the first portion and the second portion; a second detector configured to receive a combination of the third portion and the fourth portion via the waveguide system and to generate a second measurement signal comprising information of a phase delay of the third portion and the fourth portion; and A microstructured illumination adjuster, comprising a first microstructured area, a second microstructured area, a third microstructured area and a fourth microstructured area, wherein the first microstructured area, the second microstructured area, the third microstructured area and the fourth microstructured area are configured to guide corresponding parts of the first part, the second part, the third part and the fourth part to corresponding grating couplers of the first grating coupler, the second grating coupler, the third grating coupler and the fourth grating coupler.

2. The inspection system according to claim 1, further comprising: A processor configured to: analyzing the first measurement signal and the second measurement signal; as well as The position of the target is determined based on information of the phase delays of the first portion, the second portion, the third portion, and the fourth portion.

3. The inspection system according to claim 1, wherein: The inspection system is an optical system configured to: directing radiation toward the target to generate the first portion, the second portion, the third portion, and the fourth portion; and The directed illumination is scanned across the target.

4. The inspection system according to claim 1, wherein: The integrated optical system is further configured to receive, direct, and couple fifth and sixth portions of the illumination scattered by the target, the fifth and sixth portions having respective fifth and sixth wavelengths; The integrated optical system further comprises: a fifth grating coupler disposed on the substrate and configured to launch the fifth portion into the waveguide system based on the fifth wavelength, the fifth wavelength being different from the first wavelength and the third wavelength; and a sixth grating coupler disposed on the substrate and configured to launch the sixth portion into the waveguide system based on the sixth wavelength, the fifth wavelength and the sixth wavelength being the same; The inspection system further comprises a third detector configured to receive a combination of the fifth portion and the sixth portion via the waveguide system and to generate a third measurement signal comprising information of a phase delay of the fifth portion and the sixth portion; and The microstructured illumination modulator further includes fifth and sixth microstructured regions configured to direct corresponding ones of the fifth and sixth portions to corresponding ones of the fifth and sixth grating couplers.

5. The inspection system according to claim 1, wherein: At least the first microstructured region of the microstructured illumination modulator is polarization sensitive and configured to split and direct illumination based on polarization.

6. The inspection system according to claim 1, wherein: The first, second, third and fourth microstructured regions are gratings.

7. The inspection system according to claim 1, wherein: The microstructured illumination modulator is a metasurface array, and the first, second, third, and fourth microstructured regions are metasurface regions.

8. The inspection system according to claim 7, wherein: The metasurface region includes a periodic structure configured to adjust the phase, amplitude and / or polarization of the first portion, the second portion, the third portion and the fourth portion.

9. The inspection system according to claim 8, wherein: The metasurface region is configured to control the directions of the first portion, the second portion, the third portion, and the fourth portion based on adjustment of the phase, amplitude, and / or polarization.

10. The inspection system according to claim 7, wherein: The metasurface region is configured to control the focusing of the first portion, the second portion, the third portion and the fourth portion or to control optical aberrations, and / or the metasurface region is configured to apply phase correction to the first portion, the second portion, the third portion and the fourth portion or to apply phase correction to optical aberrations.

11. The inspection system according to claim 1, wherein: No lens is disposed between the microstructured illumination modulator and the target.

12. An inspection system comprising: An integrated optical system configured to receive, direct, and couple first and second portions of illumination scattered by a target, the first and second portions having respective first and second wavelengths, the integrated optical system comprising: substrate; a waveguide system disposed on the substrate; a first grating coupler disposed on the substrate and configured to launch the first portion into the waveguide system based on the first wavelength; and a second grating coupler disposed on the substrate and configured to launch the second portion into the waveguide system based on a second wavelength, the first wavelength and the second wavelength being different; a first detector configured to receive the first portion via the waveguide system and to generate a first measurement signal based on an intensity of the first portion; a second detector configured to receive the second portion via the waveguide system and to generate a second measurement signal based on an intensity of the second portion; and A microstructured illumination modulator includes a first microstructured region and a second microstructured region configured to direct a corresponding portion of the first portion and the second portion to a corresponding grating coupler of the first grating coupler and the second grating coupler.

13. The inspection system according to claim 12, further comprising: A processor configured to: analyzing the first measurement signal and the second measurement signal; and A property of the target is determined based on the intensities of the first portion and the second portion.

14. The inspection system according to claim 12, wherein: The inspection system is an optical system configured to: directing radiation toward the target to generate the first portion and the second portion; and The directed illumination is scanned across the target.

15. The inspection system of claim 12, wherein: The integrated optical system is further configured to receive, direct, and be scattered by the target a third portion of the illumination, the third portion having a corresponding third wavelength; The integrated optical system further includes a third grating coupler disposed on the substrate and configured to launch the third portion into the waveguide system based on the third wavelength, the third wavelength being different from the first wavelength and the second wavelength; The inspection system further comprises a third detector configured to receive the third portion via the waveguide system and to generate a third measurement signal based on an intensity of the third portion; and The microstructured illumination modulator also includes a third microstructured region configured to direct the third portion to the third grating coupler.

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