Passive integrated optical system and method for reducing spatial light coherence

Abstract

A passive integrated optical system and method are described. The system and method facilitate the reduction of the spatial optical coherence of light source emissions, for example, for use in metrology. Current coherence scramblers used in metrology typically include one or more (movable) mechanical components configured to reduce the coherence of light source emissions. However, these mechanical coherence scramblers occupy volume within the system and are subject to mechanical wear and failure. In contrast, the present system and method form a coherence scrambler using a combination of passive integrated optical elements. This has advantages such as reduced or eliminated use of mechanical components and improved durability.

Description

Technical Field

[0001] [Cross - Reference to Related Applications] This application claims the benefit of U.S. Application No. 63 / 342,305, filed May 16, 2022, which is hereby incorporated by reference in its entirety.

[0002] [Technical Field] The present invention relates to optical systems and methods for measurement.

Background Art

[0003] A lithographic projection apparatus can, for example, be used in the manufacture of integrated circuits (ICs). A patterning device (e.g., a mask) can contain or provide a pattern corresponding to an individual layer of the IC (the “design layout”), which pattern can be transferred onto a target portion (e.g., containing one or more dies) on a substrate (e.g., a silicon wafer) coated with a layer of radiation-sensitive material (the “resist”) by, for example, irradiating the target portion through the pattern on the patterning device. Generally, a single substrate contains a plurality of adjacent target portions in which the pattern is successively transferred, one target portion at a time, by the lithographic projection apparatus. In one type of lithographic projection apparatus, the pattern over the entire patterning device is transferred in one operation to one target portion. Such an apparatus is generally referred to as a stepper. In an alternative apparatus (generally referred to as a step-and-scan apparatus), the projection beam scans over the patterning device in a given reference direction (the “scan” direction), while simultaneously moving the substrate parallel or anti-parallel to this reference direction. Different parts of the pattern on the patterning device are gradually transferred to one target portion. Generally, since the lithographic projection apparatus has a reduction ratio M (e.g., 4), the speed F at which the substrate moves is 1 / M times the speed at which the projection beam scans the patterning device. Details of the lithographic apparatus described herein can be obtained, for example, from U.S. Patent No. 6,046,792, which is incorporated herein by reference.

[0004] Before transferring a pattern from a patterning device to a substrate, the substrate may undergo various procedures such as priming, resist coating, and soft baking. After exposure, the substrate may undergo other procedures ( "post-exposure procedures") such as post-exposure bake (PEB), development, hard bake, and measurement / inspection of the transferred pattern. This large number of procedures is used as a basis for creating individual layers of a device, such as an IC. The substrate may then undergo various processes such as etching, ion implantation (doping), metallization, oxidation, chemical mechanical polishing, etc. (all intended to finish the individual layers of the device). If several layers are required for the device, the entire procedure or a variant thereof is repeated for each layer. Finally, there are devices present at each target portion on the substrate. These devices are then separated from each other by techniques such as dicing or sawing, as a result of which it is possible to attach the individual devices onto a carrier, connect them to pins, etc.

[0005] Thus, a manufacturing device such as a semiconductor device generally involves processing a substrate (e.g., a semiconductor wafer) using a number of fabrication processes for forming various features and multiple layers of the device. Such layers and features are generally fabricated and processed using, for example, deposition, lithography, etching, chemical mechanical polishing, and ion implantation. Multiple devices may be fabricated on multiple dies on the substrate and then separated into individual devices. This device manufacturing process can be regarded as a patterning process. The patterning process includes patterning steps such as using light and / or nanoimprint lithography in a lithography apparatus to transfer a pattern on a patterning device to a substrate, and generally (but optionally) includes one or more related pattern processing steps such as resist development by a development device, baking of the substrate using a bake tool, and etching using the pattern with an etching device.

[0006] Lithography is a central step in the manufacture of devices such as ICs, and the functional elements of devices such as microprocessors and memory chips are defined by patterns formed on a substrate. Similar lithography techniques are also used in the formation of flat panel displays, microelectromechanical systems (MEMS), and other devices.

[0007] As semiconductor manufacturing processes continue to advance, the dimensions of functional elements are continuously reduced, and the number of functional elements such as transistors per device has been steadily increasing over several decades according to a trend generally known as "Moore's Law". In current technology, the layers of a device are manufactured using a lithography projection apparatus that projects a design layout onto a substrate using illumination from a deep ultraviolet light source, and individual functional elements with dimensions significantly less than 100 nm, i.e., less than half the wavelength of the radiation from the light source (e.g., a 193 nm light source), are created.

[0008] This process of printing features with dimensions smaller than the conventional resolution limit of a lithography projection apparatus is generally known as low-k1 lithography according to the resolution formula CD = k1 × λ / NA. Here, λ is the wavelength of the radiation used (currently, mostly 248 nm or 193 nm), NA is the numerical aperture of the projection optics of the lithography projection apparatus, CD is the "critical dimension" (generally the smallest feature size printed), and k1 is an empirical resolution factor. Generally, the smaller k1 is, the more difficult it becomes to reproduce on the substrate a pattern similar to the shape and dimensions planned by the designer to achieve a specific electrical function and performance. To overcome these difficulties, advanced fine-tuning steps are applied to the lithography projection apparatus, the design layout, or the patterning device. These include, for example, optimization of NA and the optical coherence setting, customized illumination schemes, the use of phase-shifting patterning devices, optical proximity effect correction (also called OPC "optical and process correction") in the design layout, or other methods generally defined as "resolution enhancement techniques" (RET), but are not limited to these. Measurement is an essential part of these fine-tuning steps.

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0009] A passive integrated optical system and method are described. The system and method facilitate, for example, the reduction of the spatial coherence of a light source used for measurement. Current coherence scramblers used for measurement typically include one or more (movable) mechanical components configured to reduce the coherence of the light source. However, these mechanical coherence scramblers occupy volume within the system and are subject to mechanical wear and failure. In contrast, the present system and method form a coherence scrambler using a combination of passive integrated optical elements. This has advantages such as reducing or eliminating the use of mechanical components and improving durability.

MEANS FOR SOLVING THE PROBLEMS

[0010] According to an embodiment, a system is provided that is configured to convert spatially coherent radiation completely or partially into spatially incoherent radiation. The system includes a splitter configured to receive spatially coherent radiation and split it into channels. The system includes optical paths of different lengths coupled to the channels. The different lengths are configured to convert spatially coherent radiation completely or partially into spatially incoherent radiation. The system includes a combiner coupled to the optical paths and configured to couple the completely or partially spatially incoherent radiation from the optical paths into a single multimode output.

[0011] In some embodiments, the optical paths are configured such that the radiation of a single channel does not become incoherent because the radiation of the single channel is single-mode radiation, but the radiation of the single channel becomes incoherent with respect to the radiation of an adjacent channel due to an appropriate path difference.

[0012] In some embodiments, the splitter, optical path, and combiner are integrated into an integrated optical body. In some embodiments, the integrated optical body includes a microchip manufactured using complementary metal-oxide semiconductor (CMOS) and / or indium phosphide manufacturing technology, lithography and / or electron beam lithography technology, and / or other technologies. In some embodiments, the waveguide layer of the integrated optical body is formed from silicon, silicon-on-oxide, indium phosphide, silicon nitride, and / or aluminum oxide.

[0013] In some embodiments, the system includes a stacked integrated optical body that forms a multi-dimensional array of waveguide emitters.

[0014] In some embodiments, the system is passive and has no moving parts or electrically controlled components.

[0015] In some embodiments, the splitter is configured to split spatially coherent radiation into at least 2 to 100 channels. In some embodiments, the splitter is a binary tree beam splitter or a non-binary beam splitter. In some embodiments, the splitter is a multimode interference (MMI) device.

[0016] In some embodiments, each optical path includes a waveguide and forms part of a corresponding channel.

[0017] In some embodiments, the different lengths are configured to reduce or eliminate interference between the radiations passing through different optical paths, thereby converting spatially coherent radiation into fully or partially spatially incoherent radiation.

[0018] In some embodiments, the optical path length difference from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation.

[0019] In some embodiments, the combiner includes an optical fiber array. In some embodiments, the combiner includes a photonic lantern. In some embodiments, the combiner includes a microlens array and / or one or more macroscopic lenses.

[0020] In some embodiments, the spatially coherent radiation includes visible light.

[0021] In some embodiments, the system further comprises a multimode fiber configured to receive a single multimode output from the combiner.

[0022] In some embodiments, the system further comprises a controller configured to actively control the outputs from the individual optical paths.

[0023] In some embodiments, the spatially coherent radiation is converted, fully or partially, into spatially incoherent radiation for measurements related to semiconductor manufacturing processes.

[0024] According to another embodiment, a method is provided for converting spatially coherent radiation, fully or partially, into spatially incoherent radiation. The method includes receiving the spatially coherent radiation using a splitter and splitting it into channels, using optical paths of different lengths coupled to the channels to convert the spatially coherent radiation, fully or partially, into spatially incoherent radiation, and using a combiner coupled to the optical paths to combine the fully or partially spatially incoherent radiation from the optical paths into a single multimode output.

[0025] According to another embodiment, a system is provided that is configured to convert spatially coherent radiation into fully or partially spatially incoherent radiation in order to reduce the speckle in illumination for measurement as part of a semiconductor manufacturing process. This system is composed of a combination of passive integrated optical elements so as to reduce the threat of volume and mechanical wear compared to mechanical coherence scramblers. This system includes a radiation source configured to generate spatially coherent radiation and a passive integrated optical body. The integrated optical body includes a splitter configured to receive the spatially coherent radiation and split it into channels. The splitter includes a binary tree beam splitter and / or a multimode interference (MMI) device. The integrated optical body includes optical paths of different lengths coupled to the channels. The different lengths are configured to convert the spatially coherent radiation conducted by the optical paths into fully or partially spatially incoherent radiation. The different lengths are configured to reduce or eliminate the interference between the radiations passing through the different optical paths, whereby the spatially coherent radiation is converted into fully or partially spatially incoherent radiation. The optical paths are configured such that the radiation of a single channel does not become incoherent because the radiation of a single channel is single-mode radiation, but the radiation of a single channel becomes incoherent with respect to the radiation of an adjacent channel due to an appropriate path difference. The integrated optical body includes a combiner configured to combine the fully or partially spatially incoherent radiation from the optical paths into a single multimode output. This system includes a multimode fiber configured to receive a single multimode output from the combiner and direct the fully or partially spatially incoherent radiation for measurement.

Brief Description of the Drawings

[0026] The above aspects and other aspects and features will become apparent to those skilled in the art by considering the following description of specific embodiments in conjunction with the accompanying drawings.

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DETAILED DESCRIPTION OF THE INVENTION

[0041] In the manufacture of semiconductor devices, measurement operations typically involve determining the position of measurement marks (or groups of marks) and / or other targets within the layers of the semiconductor device structure. This position is usually determined by irradiating the measurement marks with radiation and comparing the characteristics of different diffraction orders of the radiation reflected from the measurement marks. Such techniques are used to measure overlay, alignment, and / or other parameters.

[0042] In conventional measurement systems, to address issues such as process robustness and opaque layers, a powerful broadband light source is used to accurately characterize weak measurement targets over a wide range of wavelengths. One of the issues associated with these light sources is the coherence of the light they output. Light can be generated from a spatially coherent laser light source, which can cause speckles in the measurement image. In scatterometry, which depends on the accurate determination of the angular resolved spectrum, this can lead to undesirable errors. Coherence scramblers configured to reduce the coherence of light are known. As an example, there is a rotating diffuser plate. Scattering of coherent light through a diffusing medium causes speckles in the transmitted light. By rotating the diffuser plate, the speckle pattern changes, and by measuring for a sufficiently long time, the influence of the speckles is averaged. However, these and other mechanical coherence scramblers occupy volume within the system, have the risk of mechanical wear and / or failure, generate undesirable vibrations, and / or have other drawbacks. For example, existing coherence scramblers are typically the same size as or larger than a shoe box. Due to the mechanical movement limiting the averaging speed of the speckles, a minimum measurement time is required. In current measurement systems, it is required that the switching and measurement times be less than 1 millisecond, which is very difficult.

[0043] In contrast, the present system and method utilize a combination of passive integrated optical elements to form a coherence scrambler without moving parts or electrically controlled parts. This offers advantages such as reduced or eliminated use of mechanical parts, significantly reduced required physical volume, and improved durability. The present system and method apply photonic integration technology and comprise a compact, high-speed, and low-cost coherence scrambling device. Coherent wavelength-filtered radiation from a light source is split into channels and provided to different optical paths (multiple waveguides). In each of these optical paths / waveguides, by making the optical path difference with respect to adjacent optical paths / waveguides larger than the coherence length of the radiation, the radiation in the waveguides becomes mutually incoherent. Optionally, a microlens array or a photonic lantern, etc. can be used to recombine the radiation into a multimode fiber. The radiation can be further processed using other existing measurement system components. Since coherence scrambling is generated by the optical path length difference (not mechanical movement), integrated optical elements that occupy a very small physical volume (e.g., a volume much smaller than a typical shoe box) can be used. These functions and other functions will be described in more detail below respectively.

[0044] Briefly, the following description relates to the manufacturing and patterning processes of semiconductor devices. Some components of systems and / or methods for semiconductor device measurement will also be described in the following paragraphs. These systems and methods can be used, for example, for measurements such as overlay and alignment in the manufacturing process of semiconductor devices, or for other operations.

[0045] Although specifically referring to the manufacture of integrated circuits (ICs) for semiconductor devices, it should be understood that this description has many other applications. For example, this description can be used in the manufacture of integrated optical systems, induction and detection patterns for magnetic domain memories, liquid crystal display panels, thin film magnetic heads, etc. One of ordinary skill in the art will understand that in the context of such alternative applications, the terms "reticle", "wafer" or "die" used in this text are considered to be compatible with the more general terms "mask", "substrate" and "target portion", respectively.

[0046] The term "projection optical system" should be broadly construed as encompassing various types of optical systems including, for example, refractive optical systems, reflective optical systems, diaphragms, catadioptric optical systems. The term "projection optical system" also includes components that operate according to any of these design types, acting collectively or individually to direct, shape or control the projected beam of radiation. The term "projection optical system" can include any optical component within a lithographic projection apparatus, regardless of where the optical component is located in the optical path of the lithographic projection apparatus. The projection optical system can include optical components for shaping, conditioning and / or projecting the radiation from the radiation source before the radiation passes through the patterning device, and / or optical components for shaping, conditioning and / or projecting the radiation after the radiation has passed through the patterning device. The projection optical system generally does not include the radiation source and the patterning device.

[0047] Figure 1 schematically shows an embodiment of a lithographic apparatus LA. The apparatus comprises an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation), a support structure (e.g., a mask table) MT constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning device in accordance with certain parameters, a substrate table (e.g., a wafer table) WT (e.g., WTa, WTb or both) configured to hold a substrate (e.g., a resist-coated wafer) W and connected to a second positioner PW configured to accurately position the substrate in accordance with certain parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device MA onto a target portion C (e.g., including one or more dies, often called a field) of the substrate W. The projection system is supported on a reference frame RF. As shown, the apparatus is of a transmissive type (e.g., employing a transmissive mask). Alternatively, the apparatus may be of a reflective type (e.g., employing a programmable mirror array or a reflective mask).

[0048] The illuminator IL receives the radiation beam from a radiation source SO. The radiation source and the lithographic apparatus may be separate entities, for example when the radiation source is an excimer laser. In such cases, the radiation source is not considered to form part of the lithographic apparatus and the radiation beam is passed from the radiation source SO to the illuminator IL with the aid of a beam delivery system BD including, for example, suitable directing mirrors and / or a beam expander. In other cases, such as when the radiation source is a mercury lamp, the radiation source may be an integral part of the apparatus. The radiation source SO and the illuminator IL, together with the beam delivery system BD if required, may be referred to as a radiation system.

[0049] The illumination device IL can change the intensity distribution of the beam. The illumination device can be arranged to limit the radius range of the radiation beam so that the intensity distribution is not zero within an annular region in the pupil plane of the illumination device IL. Additionally, or alternatively, the illumination device IL can be operable to limit the distribution of the beam within the pupil plane and make the intensity distribution non-zero within a plurality of equally spaced sectors in the pupil plane. The intensity distribution of the radiation beam within the pupil plane of the illumination device IL is sometimes called the illumination mode.

[0050] The illumination device IL can include an adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. Generally, at least the outer and / or inner radius ranges (generally called σouter and σinner respectively) of the intensity distribution within the pupil plane of the illumination device can be adjusted. The illumination device IL is operable to change the angular distribution of the beam. For example, the illumination device is operable to change the number and angular range of the sectors of the pupil plane where the intensity distribution is non-zero. By adjusting the intensity distribution of the beam in the pupil plane of the illumination device, different illumination modes can be realized. For example, by limiting the radius and angular range of the intensity distribution in the pupil plane of the illumination device IL, the intensity distribution can have a multipole distribution such as a dipole, quadrupole, or hexapole distribution. The desired illumination mode can be obtained, for example, by inserting an optical system providing that illumination mode into the illumination device IL or by using a spatial light modulator.

[0051] The illumination device IL is operable to change the polarization of the beam and may be operable to adjust the polarization using an adjuster AD. The polarization state of the radiation beam across the pupil plane of the illumination device IL is sometimes called the polarization mode. By using different polarization modes, a greater contrast can be achieved in the image formed on the substrate W. The radiation beam may not be polarized. Alternatively, the illumination device may be arranged to linearly polarize the radiation beam. The polarization direction of the radiation beam may vary across the pupil plane of the illumination device IL. The polarization direction of the radiation may be different in different regions within the pupil plane of the illumination device IL. The polarization state of the radiation may be selected according to the illumination mode. In the case of the multipole illumination mode, the polarization of each pole of the radiation beam may be substantially perpendicular to the position vector of that pole in the pupil plane of the illumination device IL. For example, in the case of the dipole illumination mode, the radiation may be linearly polarized in a direction substantially perpendicular to the line bisecting the two opposite sectors of the dipole. The radiation beam may be polarized in either of two different orthogonal directions. This is sometimes called the X polarization state and the Y polarization state. In the case of the quadrupole illumination mode, the radiation of each sector of each pole may be linearly polarized in a direction substantially perpendicular to the line bisecting that sector. This polarization mode is sometimes called XY polarization. Similarly, in the case of the hexapole illumination mode, the radiation of each sector of each pole may be linearly polarized in a direction substantially perpendicular to the line bisecting that sector. This polarization mode is sometimes called TE polarization.

[0052] Furthermore, the illumination device IL generally includes various other components such as an integrator IN and a capacitor CO. The illumination system can include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation. Thus, the illumination device provides an adjusted radiation beam B having a desired uniformity and intensity distribution in cross-section.

[0053] The support structure MT supports the patterning device depending on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions such as whether the patterning device is held in a vacuum environment. The support structure can hold the patterning device using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure may be, for example, a fixed or movable frame or table as required. The support structure can ensure that the patterning device is in a desired position relative to, for example, the projection system. The terms "reticle" or "mask" as used herein are all considered to be synonymous with the more general term "patterning device".

[0054] The term "patterning device" as used herein should be broadly construed to refer to any device that can be used to impart a pattern to a target portion of a substrate. In one embodiment, a patterning device is any device that can be used to provide a radiation beam having a pattern in its cross-section for creating a pattern in a target portion of a substrate. It should be noted that the pattern imparted to the radiation beam may not exactly match the desired pattern in the target portion of the substrate, for example, when the pattern includes a phase shift function or a so-called assist function. In general, the pattern imparted to the radiation beam corresponds to a particular functional layer of the device being created in the target portion of a device such as an integrated circuit.

[0055] The patterning device may be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, programmable LCD panels, etc. Masks are well known in lithography and there are mask types such as binary, alternating phase shift, attenuated phase shift, and various hybrid mask types. As an example of a programmable mirror array, a matrix arrangement of small mirrors is employed. Each mirror can be tilted individually to reflect an incident radiation beam in various directions. The tilted mirrors impart a pattern to the radiation beam, which is reflected by the mirror matrix.

[0056] The term "projection system" should be broadly construed as encompassing any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic optical systems, or any combination thereof, depending on the exposure radiation used, or other factors such as the use of immersion liquid or the use of vacuum. When the term "projection lens" is used in this specification, it can be considered synonymous with the more general term "projection system".

[0057] The projection system PS includes a plurality of optical elements (e.g., lenses), and may further include an adjustment mechanism configured to adjust one or more of the optical elements to correct aberrations (phase changes of the pupil plane across the entire field of view). To achieve this, the adjustment mechanism is operable to operate one or more optical elements (e.g., lenses) within the projection system PS in one or more different ways. The projection system can have a coordinate system whose optical axis extends in the z direction. The adjustment mechanism is operable to perform any combination of displacing one or more optical elements, tilting one or more optical elements, and / or deforming one or more optical elements. The displacement of the optical element can be in any direction (x, y, z, or a combination thereof). The tilting of the optical element is typically performed by rotating about an axis in the x direction and / or y direction from a plane perpendicular to the optical axis, but in the case of a non-rotationally symmetric aspherical optical element, it may be rotated about the z axis. The deformation of the optical element may include a low-frequency shape (e.g., coma) and / or a high-frequency shape (e.g., freeform aspherical). The deformation of the optical element can be performed, for example, by applying a force to one or more sides of the optical element using one or more actuators and / or by heating one or more selected regions of the optical element using one or more heating elements. Generally, the projection system PS cannot be adjusted to correct apodization (change in transmittance across the pupil plane). The transmittance map of the projection system PS can be used when designing a patterning device (e.g., a mask) MA for the lithographic apparatus LA. Using computational lithography techniques, the patterning device MA can be designed to at least partially correct for apodization.

[0058] The lithographic apparatus may be of a type having two (dual-stage) or more tables (e.g., two or more substrate tables WTa, WTb, two or more patterning device tables, a substrate table WTa, and a table WTb under the projection system, e.g., for facilitating measurement and / or for a dedicated substrate-free table such as for cleaning). In such a “multi-stage” machine, additional tables can be used in parallel, or preparation steps can be carried out on one or more tables while one or more other tables are used for exposure. For example, alignment measurements using an alignment sensor AS and / or level (height, tilt, etc.) measurements using a level sensor LS can be performed.

[0059] The lithographic apparatus may be of a type in which at least a portion of the substrate is covered with a liquid having a relatively high refractive index, such as water, to fill the space between the projection system and the substrate. The immersion liquid can also be applied to other spaces within the lithographic apparatus, such as between the patterning device and the projection system. Immersion techniques are well known in the art as techniques for increasing the numerical aperture of the projection system. As used herein, the term “immersion” does not mean that a structure such as a substrate must be immersed in the liquid, but only that the liquid is present between the projection system and the substrate during exposure.

[0060] During operation of a lithographic apparatus, a radiation beam is conditioned and provided by an illumination system IL. The radiation beam B is incident on a patterning device (e.g., a mask) MA held on a support structure (e.g., a mask table) MT and is patterned by the patterning device. After traversing the patterning device MA, the radiation beam B passes through a projection system PS that focuses the beam onto a target portion C of a substrate W. With the aid of a second positioner PW and a position sensor IF (e.g., an interferometer device, a linear encoder, a 2D encoder, or a capacitance sensor), the substrate table WT can be accurately moved, for example, to place different target portions C within the path of the radiation beam B. Similarly, a first positioner PM and another position sensor (not explicitly shown in FIG. 1) can be used to accurately position the patterning device MA with respect to the path of the radiation beam B. After a mechanical search from a mask library or during a scan, movement of the support structure MT can generally be realized with the aid of a long stroke module (coarse positioning), which is part of the first positioner PM, and a short stroke module (fine positioning). Similarly, movement of the substrate table WT can be realized using a long stroke module and a short stroke module that are part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure MT is either connected only to a short stroke actuator or is fixed. The patterning device MA and the substrate W can be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. As shown in the figure, the substrate alignment marks occupy dedicated target portions, but may also be placed in the space between the target portions (these are called scribe lane alignment marks). Similarly, in a situation where a plurality of dies are provided on the patterning device MA, the patterning device alignment marks can be placed between the dies.

[0061] The illustrated apparatus can be used in at least one of the following modes. In the step mode, the support structure MT and the substrate table WT are basically kept stationary, and the pattern applied to the radiation beam is projected onto the target portion C at once (i.e., single static exposure). Next, the substrate table WT is shifted in the X direction and / or Y direction so as to be able to expose different target portions C. In the step mode, the size of the target portion C imaged by a single static exposure is limited by the maximum size of the exposure field. In the scan mode, the support structure MT and the substrate table WT are such that the pattern applied to the radiation beam is projected onto the target portion C (i.e., single dynamic exposure). The speed and direction of the substrate table WT with respect to the support structure MT can be determined by the (reduction) magnification and image inversion characteristics of the projection system PS. In the scan mode, while the width (non-scan direction) of the target portion in a single dynamic exposure is limited by the maximum size of the exposure field, the height (scan direction) of the target portion is determined by the length of the scan operation. In another mode, the support structure MT is basically kept stationary while holding the programmable patterning device, and the substrate table WT is moved or scanned while the pattern applied to the radiation beam is projected onto the target portion C. In this mode, generally a pulsed radiation source is used, and the programmable patterning device is updated as necessary after each movement of the substrate table WT or during successive radiation pulses during the scan. This operating mode can be easily applied to maskless lithography using a programmable patterning device such as the type of programmable mirror array mentioned above.

[0062] Combinations and / or variations of the above usage modes, or entirely different usage modes can also be used.

[0063] The substrate may be processed, before or after exposure, by, for example, a track (usually a tool for applying a resist layer to a substrate and developing the exposed resist) or a metrology or inspection tool. Where applicable, the disclosure herein may apply to such substrate processing tools and other substrate processing tools. Further, the substrate may be processed multiple times, for example, to create a multilayer IC, and thus, the term substrate as used herein may refer to a substrate that already includes multiple processed layers.

[0064] As used herein in the context of lithography, the terms "radiation" and "beam" include all types of electromagnetic radiation, such as ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., having a wavelength of 365, 248, 193, 157, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., in the range of 5 - 20 nm wavelength), as well as particle beams such as ion beams or electron beams.

[0065] The various patterns on or provided by the patterning device may have different process windows, i.e., a space of process variables within which the pattern is generated. Examples of pattern specifications related to potential systematic defects include checks for necking, line pullback, line slimming, CD, edge placement, overlap, resist top loss, resist undercut, and / or bridging. The process window of a pattern on or in a region of the patterning device is obtained by merging (e.g., overlaying) the process windows of the individual patterns. The boundaries of the process window of a pattern group include the boundaries of the process windows of some of the individual patterns. In other words, these individual patterns limit the process window of the pattern group.

[0066] As shown in FIG. 2, the lithography apparatus LA also includes an apparatus that forms part of a lithography cell LC, also called a litho cell or cluster, and performs pre-exposure and post-exposure processes on a substrate. Conventionally, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the exposed resist, one or more chill plates CH and / or one or more bake plates BK. A substrate handler, or robot RO, picks up one or more substrates from the input / output ports I / O1, I / O2, moves them between various process apparatuses, and delivers them to the loading bay LB of the lithography apparatus. These apparatuses are collectively called a track and are controlled by a track control unit TCU. The track control unit TCU itself is controlled by a monitoring control system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Thus, various apparatuses can be operated to maximize throughput and processing efficiency.

[0067] In order to ensure that the substrate exposed by the lithography apparatus is exposed accurately and consistently, and / or to monitor part of a patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., a photolithography step), it is desirable to inspect a substrate or other object to measure or determine one or more characteristics such as alignment, overlay (e.g., between upper layer structures, or between structures of the same layer provided separately to a layer by, for example, a double patterning process), line width, critical dimension (CD), focus offset, material properties, etc. Thus, the manufacturing facility in which the litho cell LC is located usually also includes a metrology system for measuring part or all of the substrate W (FIG. 1) processed in the litho cell, or other objects within the litho cell. The metrology system may be part of the litho cell LC, or for example, part of the lithography apparatus LA (such as an alignment sensor AS (FIG. 1)).

[0068] One or more measurement parameters include, for example, alignment, overlay between successive layers formed within or on the patterned substrate, for example, critical dimension (CD) (e.g., critical linewidth) of features formed within or on the patterned substrate, focus or focus error of a photolithography step, dose or dose error of a photolithography step, optical aberration of a photolithography step, etc. This measurement is often performed on one or more dedicated metrology targets provided on the substrate. The measurement can be performed after resist development, before etching, after etching, after deposition, and / or at other times.

[0069] There are various techniques for measuring structures formed in a patterning process, including the use of scanning electron microscopes, image-based measurement tools, and / or various dedicated tools. A dedicated metrology tool in a fast and non-invasive form directs a radiation beam at a target on the surface of the substrate and measures the characteristics of the scattered (diffracted / reflected) beam. By evaluating one or more characteristics of the radiation scattered by the substrate, one or more characteristics of the substrate can be determined. Traditionally, this has been called diffraction-based metrology. Applications of this diffraction-based metrology include measurements such as overlay and alignment. For example, overlay and / or alignment can be measured by comparing parts of the diffraction spectrum (e.g., comparing different diffraction orders of the diffraction spectrum of a periodic grating).

[0070] Therefore, in a device manufacturing process (e.g., a patterning process or a lithography process), various types of measurements may be performed on a substrate or other object during or after the process. The measurements can be used to determine whether a particular substrate has defects, to adjust the process and the equipment used in the process (e.g., align two layers on a substrate or align a patterning device to a substrate), to measure the performance of the process and the equipment, or for other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements such as the ASML YieldStar metrology tool, the ASML SMASH metrology system), mechanical measurements (e.g., profiling using a stylus, atomic force microscope (AFM)), and / or non-optical imaging (e.g., scanning electron microscope (SEM)). The SMASH (Smart Alignment Sensor Hybrid) system described in U.S. Patent No. 6,961,116 generates two overlapping and relatively rotated images of alignment markers, detects the intensity of the pupil plane where the Fourier transform of the images interferes, and employs a self-referencing interferometer that extracts position information from the phase difference between the diffraction orders of the two images, which appears as the intensity change of the interfered orders.

[0071] The measurement results can be provided directly or indirectly to the monitoring control system SCS. If an error is detected, adjustments can be made to subsequent substrate exposures (especially if the inspection can be performed immediately and one or more other substrates in the batch have not yet been exposed) and / or subsequent exposures of the exposed substrates. Also, substrates that have already been exposed can be stripped and reprocessed to improve yield or discarded to prevent further processing of substrates known to be defective. If there are defects only in some target portions of a substrate, further exposure can be performed only on the target portions that meet the specifications. Other manufacturing process adjustments are also conceivable.

[0072] Using a measurement system, one or more characteristics of a substrate structure, in particular how one or more characteristics of different substrate structures change, or how different layers of the same substrate structure change from layer to layer, can be determined. The measurement system can be integrated into a lithography apparatus LA or a lithocell LC, or can be a stand-alone device.

[0073] To enable measurement, often one or more targets are specially provided on the substrate. Usually, the targets can be specially designed and can include periodic structures. For example, a target on a substrate can include one or more one-dimensional periodic structures (such as geometric features like a grating), and after development, the periodic structure features are printed such that they are formed by solid resist lines. As another example, a target can include one or more two-dimensional periodic structures (such as a grating), and after development, one or more periodic structures are printed such that they are formed by solid resist pillars or vias in the resist. The bars, pillars, or vias may be etched into the substrate (such as one or more layers on the substrate).

[0074] Figure 3 shows an example of a measurement (inspection) system 10 that can be used for overlay, alignment detection, and / or performing other measurement operations. This system includes a radiation source or illumination source 2 that projects or irradiates radiation onto a substrate W (such as a substrate including measurement marks). The redirected radiation is passed to a sensor such as a spectrometer detector 4 and / or other sensors, and measures the spectrum (intensity as a function of wavelength) of the specularly reflected and / or diffracted radiation, as shown in the left graph of Figure 4. The sensor can generate a measurement signal that transmits measurement data indicating the characteristics of the reflected radiation. From this data, the structure or profile that gives rise to the detected spectrum can be reconstructed by one or more processors PRO or other operations, as shown in the generalized example of Figure 4.

[0075] Similar to the lithography apparatus LA of FIG. 1, one or more substrate tables (not shown in FIG. 4) may be provided to hold the substrate W during the measurement operation. The one or more substrate tables may be similar or identical in shape to the substrate table WT (WTa or WTb, or both) of FIG. 1. In an example where the inspection system 10 is integrated with the lithography apparatus, they may be the same substrate table. Coarse and fine positioners may be provided and configured to accurately position the substrate relative to the measurement optical system. For example, various sensors and actuators are provided to acquire the position of the target portion (e.g., measurement mark) of the structure to be measured and place it under the objective lens. Usually, many measurements are performed on the target portions of the structure at various locations on the substrate W. The substrate support can move in the X and Y directions to acquire various targets and in the Z direction to acquire the desired position of the target portion relative to the focus of the optical system. For example, in practice, when the substrate moves while the optical system remains substantially stationary (usually in the X and Y directions, and in some cases in the Z direction), it is convenient to consider and explain the operation as if the objective lens is being moved to different positions relative to the substrate. If the relative position of the substrate and the optical system is correct, in principle, it does not matter whether one or both are moving, or a combination where a part of the optical system is moving (e.g., in the Z direction and / or tilt direction) and the rest of the optical system is stationary while the substrate is moving (e.g., in the X and Y directions, and in some cases in the Z direction and / or tilt direction).

[0076] In the case of typical measurement measurements, the target (portion) 30 on the substrate W is a one-dimensional grid and is printed such that after development, bars are formed of solid resist lines (e.g., covered with a deposited layer) and / or other materials. Alternatively, the target 30 is a 2D grid and is printed such that after development, the grid is formed of solid resist pillars and / or other features within the resist.

[0077] Bars, pillars, vias, and / or other features are etched in or on a substrate (e.g., in one or more layers on the substrate), deposited on the substrate, covered by a deposited layer, and / or have other characteristics. The target (portion) 30 (e.g., bar, pillar, via, etc.) is sensitive to process variations in a patterning process (e.g., optical aberrations of a lithographic projection apparatus such as a projection system, focus variations, dose variations, etc.), and the process variations appear as variations of the target 30. Thus, the measurement data from the target 30 can be used to determine adjustments to one or more manufacturing processes or as a basis for making actual adjustments.

[0078] For example, the measurement data from the target 30 can indicate the overlay of layers of a semiconductor device. The measurement data from the target 30 can be used (e.g., by one or more processors PRO and / or other processors) to determine one or more semiconductor device manufacturing process parameters based on the overlay and to determine adjustments to a semiconductor device manufacturing apparatus based on the determined one or more semiconductor device manufacturing process parameters. In some embodiments, this can include, for example, adjustment of stage position, or can include determining adjustments to mask design, metrology target design, semiconductor device design, radiation intensity, radiation angle of incidence, radiation wavelength, pupil size and / or shape, resist material, and / or other process parameters.

[0079] FIG. 5 shows a plan view of a typical target (e.g., a measurement mark) 30 in the system of FIG. 4 and indicates the extent of a typical radiation irradiation spot S. Usually, in order to obtain a diffraction spectrum that is not affected by interference from surrounding structures, in certain embodiments, the target 30 is a periodic structure (e.g., a grating) that is larger than the width (e.g., diameter) of the irradiation spot S. The width of the spot S may be smaller than the width and length of the target. In other words, the target is in a state of being “not filled” by the illumination, and the diffraction signal essentially does not include signals from features of products outside the target itself. The irradiation arrangement may be configured to provide uniform-intensity irradiation over the entire rear focal plane of the objective lens, for example. Alternatively, the irradiation may be restricted axially or off-axially, for example, by including an aperture in the irradiation path.

[0080] FIG. 6 shows a system 600 for converting spatially coherent radiation into fully or partially spatially incoherent radiation. The radiation can be used to obtain measurements from a measurement target and / or for other purposes. The radiation can include illumination such as visible light and / or other radiation. The target can include one or more measurement marks such as a diffraction grating target formed on a substrate such as a semiconductor wafer. System 600 can form part of system 10 described above with respect to FIG. 3. System 600 can be, for example, a subsystem of system 10. In some embodiments, one or more components of system 600 can be similar and / or identical to one or more components of system 10. In some embodiments, one or more components of system 600 can replace, be used together with, and / or otherwise augment one or more components of system 10.

[0081] System 600 provides a new optical design architecture. As described above, System 600 is a passive integrated optical system configured to reduce, for example, the spatial optical coherence of a light source used for measurement. Current coherence scramblers used for measurement typically include one or more (movable) mechanical components configured to reduce the coherence of a light source. However, these mechanical coherence scramblers occupy volume within the system and are subject to mechanical wear and failure. In contrast, System 600 forms a coherence scrambler using a combination of passive integrated optical elements. This has advantages such as reducing or eliminating the use of mechanical components and improving durability. System 600 includes a splitter 602, an optical path 604, a combiner 608, and / or other components. In some embodiments, the components of System 600 form part of a measurement sensor used in a semiconductor manufacturing process.

[0082] In some embodiments, splitter 602, optical path 604, combiner 608, and / or other components of system 600 are integrated into integrated optical body 601. In some embodiments, integrated optical body 601 is passive and has no moving parts or electrically controlled components. In some embodiments, integrated optical body 601 includes, for example, a microchip manufactured using complementary metal oxide semiconductor (CMOS) manufacturing technology, indium phosphide manufacturing technology, lithography and / or electron beam writing technology, and / or other technologies. Integrated optical platforms may include silicon, silicon nitride (Si3N4), indium phosphide (InP), aluminum oxide (AL2O3) (e.g., for UV radiation), and / or other platforms. The waveguide (optical path forming) layer of the integrated optical body may be formed from, for example, Si3N4 (e.g., for radiation wavelengths up to about 25 - 300 nm, alternative materials are required for deep ultraviolet), Si, silicon-on-oxide, and / or other materials. For example, for wavelengths in the range of 250 - 400 nm, another material other than Si3N4, such as aluminum oxide (AL2O3) or other materials, may be used.

[0083] For example, using a Si3N4 integrated optical platform facilitates the use of radiation with a bandwidth of about 400 - 1700 nm, which is sufficient for illuminating a measurement system (e.g., system 10 shown in FIG. 3). However, if it is necessary to process optical power exceeding 1 W, in such waveguides that can process a maximum of about 1 W of optical power, the power of the radiation source may become a problem. However, system 600 (and / or system 10 shown in FIG. 3) can be configured such that the wavelength selection required for measurement is performed before the radiation enters splitter 602, and the power is reduced by limiting the bandwidth, thus alleviating the problem of high power of the radiation source.

[0084] Splitter 602 is configured to receive spatially coherent radiation (e.g., from a radiation source) and split it into channels 607, 609, 611, etc. When radiation (e.g., light) from a single channel is passed to a multimode fiber (described later), at the end of the multimode fiber, the above-mentioned (undesirable) speckles occur. In contrast, splitter 602 is configured to split spatially coherent radiation into a sufficient number of channels 607, 609, 611 necessary to reduce and / or eliminate the speckle effect. For example, in the estimation of 600 nm radiation (such as light) with a bandwidth of 6 nm, the minimum number of channels of splitter 602 is about 750 (for example, the number of channels or modes is equal to the size of the entrance aperture of the multimode fiber divided by the size of a single channel or mode, which is approximately the size of the point spread function. See the mathematical details of the following examples). In photonic lantern technology (described below), about 100 fibers are combined. If a microlens array follows the fiber array (as another example), this number can be easily extended to thousands. Thus, in some embodiments, spatially coherent radiation is split by splitter 602 into at least 2 - 100, 2 - 200, 2 - 500, 2 - 750, 2 - 1000, 2 - 3000, or more channels.

[0085] In some embodiments, splitter 602 is composed of a binary tree beam splitter and / or other splitters. The binary tree beam splitter may include a series of channels that are successively split in half so that two channels are formed from one channel. After several splits, a tree structure is formed in which one input channel 605 becomes a plurality of output channels 611. In some embodiments, splitter 602 is composed of a multimode interference (MMI) device.

[0086] For example, FIG. 7 shows a splitter 602 formed as a binary tree 700. The binary tree 700 includes channels 607, 609, 611, 613, 615, etc. As shown in FIG. 7, at each splitting position 621-681, one radiation channel is split into two channels, and the incident radiation at each splitting position is evenly split into the two channels. The splitting occurs because the channel walls are arranged such that one channel becomes two. A partition wall is formed in the center of the channel, and the radiation is separated into two substantially equal parts. The splitting is repeated one or more times until a plurality of channels are created by the splitter 602.

[0087] Returning to FIG. 6, in some embodiments, the splitter 602 comprises a non-binary beam splitter and / or other splitters. Generally, a binary beam splitter splits one channel into two. However, in principle, non-binary splitters can also be used. For example, those that split one channel into three and / or other numbers of channels. These include, for example, directional couplers, ultra-wideband nanophotonic beam splitters using metamaterials, and / or other non-binary beam splitters.

[0088] The optical path 604 is directly coupled to the corresponding channel 611 (e.g., without passing through air or lens space). The optical path 604 is configured to convert spatially coherent radiation into completely or partially spatially incoherent radiation. Each optical path 604a, 604b, 604c, 604d, 604e, and 604f in this example includes, for example, a waveguide and forms part of the corresponding channel 611. The optical paths 604 have different lengths and are coupled to the channel 611. The different lengths are configured to convert the spatially coherent radiation conducted by the optical paths 604 into completely or partially spatially incoherent radiation. The different lengths are configured to reduce or eliminate interference between the radiations passing through the different optical paths 604, whereby the spatially coherent radiation is converted into completely or partially spatially incoherent radiation. The optical path 604 is configured such that the radiation of a single channel 611 does not become incoherent because the radiation of a single channel 611 is single-mode radiation, but with an appropriate path difference, the radiation of a single channel 611 becomes incoherent with respect to the radiation of an adjacent channel 611.

[0089] In some embodiments, the optical path length difference between the first optical path 604a and the second optical path 604b (and between the first optical path 604a and the third optical path 604c, between the second optical path 604b and the third optical path 604c, etc.) is greater than the coherence length of the spatially coherent radiation coming from 605. In the optical path 604, the degree of coherence between channels can be adjusted by changing the individual optical path lengths and / or other characteristics of the optical path 604.

[0090] For example, FIG. 8 shows an optical path 604 (including optical paths 604a - 604f). The radiation at the output of the channel (e.g., channel 611 shown in FIG. 6) is still single - mode and coherent. However, if each channel is configured with an optical path difference (OPD) greater than the coherence length (Lc) of the radiation, the radiation from individual channels does not interfere with each other. Such an integrated structure is formed using optical paths 604a - 604f that can be considered as delay lines (the radiation reaching the end of one optical path is delayed compared to the radiation of another optical path due to the difference in path lengths. Some radiation passes through a longer path). FIG. 8 shows one of many possible configurations. In FIG. 8, each optical path 604a - 604f has an OPD imposed on it with respect to adjacent optical paths by additional zig - zag curves 800, 802, 804, 806. Each optical path has several adjustable parameters. For example, R is the minimum radius of curvature such that radiation does not leak from the path. ΔsΔy is the minimum distance between paths required to prevent coupling. And h is a parameter that can be used to adjust the OPD.

[0091] As a non - limiting practical example, assuming a Gaussian radiation spectrum, the coherence length is as follows.

Equation

Equation

Equation

Equation

number

[0092] Returning to FIG. 6, combiner 608 is configured to combine the fully or partially spatially incoherent radiation into a single multimode output. In some embodiments, combiner 608 is directly coupled to the corresponding optical paths 604 (e.g., without air or lens space). After coherence scrambling by optical paths 604, a 1D array of single mode waveguides emitting mutually incoherent light is created. Incident radiation from a radiation source is combined into N cnl By splitting into waveguides, system 600 increases the radiating surface area by a factor of N while keeping the numerical aperture the same. cnl This effectively increases the étendue by the same factor N cnl 6, the output from optical path 604 is increased by 100 ns. For example, by recombining the output from optical path 604 into a multimode fiber (MM), the radiation can be further processed by the illumination hardware of an existing measurement system (e.g., system 1100 shown in FIG. 3). In some embodiments, combiner 608 is comprised of an optical fiber array 900 (see FIG. 9), a microlens array 1100, and / or one or more macroscopic lenses 1102 (see FIG. 11), and / or other components.

[0093] For example, Figure 9 illustrates the combiner 608 as an optical fiber array 900. As shown in Figure 9, after coherence scrambling, a 1D array of single mode waveguides (optical paths 604) that emit mutually incoherent light is created. These can be recombined into a 2D profile 902 by the optical fiber array 900. Figure 9 illustrates a schematic 904 of the optical fiber array 900, a wide angle view 906 of the coupled fibers 908, and an end view 910 of the 2D profile 902.

[0094] In some embodiments, the combiner 608 (FIG. 6) includes a photonic lantern. For example, FIG. 10 shows the combiner 608 as a photonic lantern 1000. The photonic lantern 1000 is a multimode fiber device having an array of single-mode fiber cores 1002. The single-mode fiber cores 1002 are fused 1003, for example, to form the multimode fiber 1004.

[0095] In some embodiments, the combiner 608 (FIG. 6) includes a microlens array and / or one or more macroscopic lenses. For example, FIG. 11 shows the combiner 608 as a microlens array 1100 and a macroscopic lens 1102. The output from the 1D array of single-mode optical paths 604 (waveguides) can be shaped 1103 using micro (e.g., microlens array 1100) and / or other optical components (e.g., lens 1102). As shown in FIG. 11, when the 1D microlens array 1100 is placed at the same period as the output of the optical path 604, the output is shaped into an array of parallel spots. The macroscopic lens 1102 can recombine these spots into the multimode fiber 1110.

[0096] In some embodiments, the system 600 (FIG. 6) is configured such that stacked integrated optical bodies (e.g., 601 shown in FIG. 6) are formed, which together form a multi-dimensional array of waveguide emitters. For example, a plurality of planar coherence scrambling systems (e.g., the plurality of systems 600 described above) can be stacked on top of each other to form a 2D array of waveguide emitters (optical paths 604). If this is manufactured at the same period as the 2D microlens array, a macroscopic lens can be used to recombine the array of spots into the multimode fiber. Using a configuration of two microlens arrays and two macroscopic lenses, a densely packed array of spots can fit into the entrance aperture of the multimode fiber.

[0097] As a non-limiting example, FIG. 12 shows stacked 1200 integrated optical bodies (e.g., moving from left to right across the image). First, FIG. 12 shows a 2D microlens array and a single macroscopic lens similar and / or the same as the microlens array 1100 and lens 1102 shown in FIG. 11. Next, FIG. 12 shows that when multiple such microlens arrays 1100 and lenses 1102 are stacked, the radiation 1202 changes from a small spot size and a large spacing 1204, to a large spot size and a large spacing 1206, and then to a small spot size and a small spacing 1208. FIG. 12 also shows how this configuration of two microlens arrays 1100 and two macroscopic lenses 1102 is used to convert a sparse array of radiation spots 1210 into a dense array of spots 1212 to fit within the entrance aperture of a multimode fiber.

[0098] System 600 (FIG. 6) can be extended to switch light using an amplitude modulator and a phase modulator for each channel. In some embodiments, the modulation may be electronically controlled by a processor such as processor PRO shown in FIG. 3 (and FIG. 14 described below). Processor PRO may be included in computing system CS (FIG. 14) and may operate based on computer or machine-readable instructions MRI (e.g., as described below in connection with FIG. 14). Electronic communication may be performed by transmitting an electronic signal between separate components, transmitting data between separate components of system 600, transmitting a value between separate components, and / or performing other communication. The components of system 600 may communicate wirelessly via a network such as a wired or the Internet, or the Internet in combination with various other networks such as a local area network, a cellular network, or a personal area network, an internal organizational network, and / or other networks.

[0099] In some embodiments, one or more actuators (not shown in FIG. 6) may be coupled and configured to one or more components of system 600 to facilitate modulation. The actuator may be coupled to one or more components of system 600 by an adhesive, clip, clamp, screw, collar, and / or other mechanism. The actuator can be configured to be electronically controlled. An individual actuator can be configured to convert an electrical signal into mechanical displacement and / or other modulation. The mechanical displacement and / or other modulation is configured to modulate a component of system 600. For example, one or more actuators are piezoelectric. One or more processors PRO can be configured to control the actuator. One or more processors PRO can be configured to individually control each of the one or more actuators.

[0100] FIG. 13 shows a method 1300 for converting spatially coherent radiation into fully or partially spatially incoherent radiation. Method 1300 can be carried out, for example, to reduce the speckle in illumination for metrology as part of a semiconductor manufacturing process. Method 1300 can be carried out using a combination of passive integrated optical elements such that, for example, the volume and the threat of mechanical wear are reduced compared to a mechanical coherence scrambler. In some embodiments, one or more steps of method 1300 can be implemented in and / or by, for example, system 600 shown in FIG. 6, system 10 shown in FIG. 3, a computer system (such as, for example, the one shown in FIG. 14 and described below), and / or other systems. In some embodiments, method 1300 includes generating spatially coherent radiation (step 1302), splitting the spatially coherent radiation into channels (step 1304), converting the spatially coherent radiation into fully or partially spatially incoherent radiation (step 1306), combining the fully or partially spatially incoherent radiation into a single multimode output (step 1308), receiving the single multimode output and directing it for metrology (step 1310), and / or other steps.

[0101] The steps of method 1300 are for illustrative purposes. In some embodiments, method 1300 may be carried out with one or more additional steps not described and / or without one or more of the steps described. For example, in some embodiments, method 1300 may include additional steps related to determining adjustments to a semiconductor device manufacturing process. Further, the steps of method 1300 are shown in FIG. 13 and the order described herein is not limiting.

[0102] In some embodiments, one or more portions of method 1300 may be implemented and / or controlled by one or more processing devices (e.g., a digital processor, an analog processor, a digital circuit designed to process information, an analog circuit designed to process information, a state machine, and / or other mechanisms for electronically processing information). The one or more processing devices may include one or more devices that execute some or all of the steps of method 1300 in response to instructions electronically stored on an electronic storage medium. The one or more processing devices may include one or more devices configured by hardware, firmware, and / or software to be specifically designed to execute one or more steps of method 1300 (see, e.g., the description regarding FIG. 14 below).

[0103] In step 1302, spatially coherent radiation is generated. The radiation may have a target wavelength and / or wavelength range, a target intensity, and / or other characteristics. The target wavelength and / or wavelength range, the target intensity, etc. may be input and / or selected by a user, determined by the system (e.g., system 10 shown in FIG. 3) based on previous measurements, and / or determined by other means. In some embodiments, the radiation includes light and / or other radiation. In some embodiments, the light includes visible light, infrared light, near-infrared light, and / or other light. In some embodiments, the radiation can be any radiation suitable for interferometry. In this example, the spatially coherent radiation is considered to be visible light. In some embodiments, the spatially coherent radiation is generated by a single light source configured to generate radiation along a first axis. In some embodiments, step 1302 is performed by a radiation source similar to and / or the same as light source 2 shown in FIG. 3.

[0104] In operation 1304, spatially coherent radiation is split into channels. In some embodiments, the spatially coherent radiation is split into, for example, at least 2 to 100 channels. In some embodiments, operation 1304 is performed by a splitter that is the same as or similar to splitter 602 shown in and described above with reference to FIG. 6. In some embodiments, the splitter includes a binary tree beam splitter or a non-binary beam splitter. In some embodiments, the splitter includes, for example, a multimode interference (MMI) device.

[0105] In operation 1306, the spatially coherent radiation is converted to completely or partially spatially incoherent radiation. In some embodiments, operation 1306 is performed by an optical path that is the same as or similar to optical path 604 shown in and described above with reference to FIG. 6. Each optical path includes, for example, a waveguide and may form part of a corresponding channel. The optical paths have different lengths and are coupled to the channels. The different lengths are configured to convert the spatially coherent radiation conducted by the optical paths to completely or partially spatially incoherent radiation. The different lengths are configured to reduce or eliminate interference between the radiation passing through the different optical paths, thereby converting the spatially coherent radiation to completely or partially spatially incoherent radiation. The optical paths are configured such that radiation in a single channel does not become incoherent because the radiation in a single channel is single-mode radiation, but radiation in a single channel becomes incoherent with respect to radiation in adjacent channels if there is an appropriate path difference. In some embodiments, the optical path length difference from a first optical path to a second optical path (and from the first optical path to a third optical path, from the second optical path to the third optical path, etc.) is greater than the coherence length of the spatially coherent radiation.

[0106] In operation 1308, spatially incoherent radiation, either fully or partially, is combined into a single multimode output. In some embodiments, operation 1308 is performed by a combiner that is the same as or similar to combiner 608 shown and described above in FIG. 6. In some embodiments, the combiner includes an optical fiber array. In some embodiments, the combiner includes a photonic lantern. In some embodiments, the combiner includes a microlens array and / or one or more macroscopic lenses.

[0107] In operation 1310, a single multimode output from the combiner is received and spatially incoherent radiation, either fully or partially, is directed for measurement. In some embodiments, operation 1310 is performed by a multimode fiber configured to receive a single multimode output from the combiner and direct spatially incoherent radiation, either fully or partially, for measurement. In some embodiments, operation 1310 is performed by various components of a system such as system 10 shown in FIG. 3. This can include, for example, detector 4 and processor PRO. For example, the system can include a controller (e.g., processor PRO) configured to actively control the output from individual optical paths.

[0108] In some embodiments, an overlay and / or alignment and / or other measurements may be determined in step 1310. The overlay and / or alignment may be determined based on reflected diffracted radiation and / or other information from the diffraction grating target. For example, in some embodiments, step 1310 includes illuminating (and / or irradiating) one or more targets (e.g., target 30 shown in FIG. 3) in the patterned substrate with radiation. The radiation includes the fully and / or partially spatially incoherent radiation described above. The radiation may be generated by a radiation source (e.g., radiation source 2 shown in FIG. 3 above). In some embodiments, the radiation may be directed at multiple targets, a single target, a sub - portion of a target (e.g., a portion smaller than the whole), and / or in other ways to the substrate. In some embodiments, the radiation may be directed at the target in a time - varying manner. For example, the radiation may be rasterized on the target (e.g., by moving the target under the radiation) such that different portions of the target are irradiated at different times. As another example, the characteristics of the radiation (e.g., wavelength, intensity, etc.) may be varied. This may create a time - varying data envelope or window for analysis. The data envelope facilitates analysis of individual sub - portions of the target, comparison of one part of the target with other parts and / or other targets (e.g., other layers), and / or other analysis.

[0109] In some embodiments, step 1310 includes generating a measurement signal based on the reflected radiation detected from the diffraction grating target as described above. The measurement signal is generated by a sensor (such as detector 4 in FIG. 3 and / or other sensors) based on the radiation received by the sensor. The measurement signal includes measurement information about the target. For example, the measurement signal can be an overlay and / or alignment signal that includes overlay and / or alignment measurement information, and / or other measurement signals. The measurement information (such as overlay values, alignment values, and / or other information) can be determined using the principles of interferometry and / or other principles.

[0110] The measurement signal includes and / or corresponds to an electronic signal representing the radiation reflected from the target. The measurement signal can indicate, for example, measurement values associated with the diffraction grating target and / or other information. Generating the measurement signal includes sensing the reflected radiation and converting the sensed reflected radiation into an electronic signal. In some embodiments, generating the measurement signal includes sensing different regions and / or different shapes of the target and / or different portions of the reflected radiation from multiple targets, and combining the different portions of the reflected radiation to form the measurement signal. This includes generating and / or analyzing one or more images of the target using the radiation described herein. This sensing and conversion may be performed by components similar to and / or the same as detector 4 and / or processor PRO shown in FIG. 3, and / or other components.

[0111] In some embodiments, method 1300 includes determining an adjustment to a semiconductor device manufacturing process. In some embodiments, method 1300 includes determining one or more semiconductor device manufacturing process parameters. The one or more semiconductor device manufacturing process parameters can be determined based on one or more detected phase and / or amplitude variations, overlay and / or alignment values indicated by a measurement signal, and / or other similar systems, and / or other information. The one or more parameters include radiation parameters (radiation used for measurement), overlay values, alignment values, measurement inspection locations on layers of the semiconductor device structure, the trajectory of the radiation beam across the target, and / or other parameters. In some embodiments, the process parameters can be broadly interpreted to include stage position, mask design, measurement target design, semiconductor device design, radiation intensity (used for resist exposure, etc.), radiation incident angle (used for resist exposure, etc.), radiation wavelength (used for resist exposure, etc.), pupil size and / or shape, resist material, and / or other parameters.

[0112] In some embodiments, method 1300 includes determining a process adjustment based on one or more determined semiconductor device manufacturing process parameters, adjusting a semiconductor device manufacturing apparatus based on the determined adjustment, and / or other operations. For example, if the determined measurement is outside the process tolerance, the out-of-tolerance measurement may be caused by one or more manufacturing processes in which the process parameters have drifted and / or been otherwise changed, such that the process may no longer be producing acceptable devices (e.g., the measured value may exceed an acceptability threshold). Based on the determination of the measurement, one or more new or adjusted process parameters may be determined. The new or adjusted process parameters may be configured such that the manufacturing process produces acceptable devices again.

[0113] For example, new or adjusted process parameters may adjust previously unacceptable measurements within an acceptable range. The new or adjusted process parameters may be compared to existing parameters of a particular process. If there is a difference, the difference may be used, for example, to determine an adjustment to an apparatus used in the manufacture of a device (e.g., parameter "x" should be increased / decreased / changed to match a new or adjusted version of parameter "x" determined as part of method 1300). In some embodiments, method 1001 may include electronically adjusting an apparatus (e.g., based on determined process parameters). Electronically adjusting an apparatus may include, for example, transmitting to the apparatus an electronic signal and / or other communication that causes a change to the apparatus. The electronic adjustment may include, for example, a change to the settings of the apparatus and / or other adjustments.

[0114] FIG. 14 is a diagram showing an example of a computer system CS that can be used for one or more operations described herein. The computer system CS includes a bus BS or other communication mechanism for communicating information, and a processor PRO (or multiple processors similar and / or identical to the processor PRO shown in FIG. 3) connected to the bus BS for processing information. The computer system CS also includes a main memory MM, such as a random access memory (RAM) or other dynamic storage device, connected to the bus BS for storing information and instructions executed by the processor PRO. The main memory MM can also be used to store temporary variables or other intermediate information during execution of instructions by the processor PRO. The computer system CS further includes a read-only memory (ROM) or other static storage device connected to the bus BS for storing static information and instructions of the processor PRO. A storage device SD, such as a magnetic disk or optical disk, is provided and connected to the bus BS for storing information and instructions.

[0115] Computer system CS can be connected via bus BS to a display DS, such as a flat panel or touch panel display or a cathode ray tube (CRT), for displaying information to a computer user. An input device ID, including alphanumeric keys and other keys, is connected to bus BS to convey information and command selections to processor PRO. Another type of user input device is a cursor control CC, such as a mouse, trackball, or cursor direction keys, which conveys direction information and command selections to processor PRO and controls the movement of a cursor on display DS. This input device typically has two degrees of freedom along two axes, a first axis (e.g., x) and a second axis (e.g., y), thereby enabling the device to specify a position within a plane. A touch panel (screen) display can also be used as an input device.

[0116] In some embodiments, all or part of one or more of the processes described herein may be performed by computer system CS in response to one or more sequences of one or more instructions contained in main memory MM, which are executed by processor PRO. Such instructions may be read into main memory MM from another computer-readable medium, such as storage device SD. Execution of the instruction sequences contained in main memory MM causes processor PRO to perform the process steps (processes) described herein. One or more processors in a multiprocessing configuration may also be used to execute the instruction sequences contained in main memory MM. In some embodiments, hardwired circuitry may be used in place of, or in combination with, software instructions. Accordingly, the description set forth herein is not limited to a particular combination of hardware circuitry and software.

[0117] As used herein, the term "computer-readable medium" or "machine-readable medium" refers to any medium that participates in providing instructions to processor PRO for execution. Such a medium can take many forms, including but not limited to non-volatile media, volatile media, and transmission media. Non-volatile media includes, for example, optical or magnetic disks such as storage device SD. Volatile media includes dynamic memory such as main memory MM. Transmission media includes coaxial cables, copper wire, fiber optics, including the wires that make up bus BS. The transmission media can also take the form of acoustic or light waves generated during radio frequency (RF) and infrared (IR) data communications. A computer-readable medium is non-transitory and can be, for example, a floppy disk, flexible disk, hard disk, magnetic tape, other magnetic media, CD-ROM, DVD, other optical media, punch cards, paper tape, other physical media with patterns of holes, RAM, PROM, EPROM, FLASH-EPROM, other memory chips or cartridges, etc. Instructions may be recorded on non-transitory computer-readable media. When executed by a computer, the instructions can implement any of the operations described herein. Transitory computer-readable media includes, for example, carrier waves and other propagating electromagnetic signals.

[0118] Various forms of computer-readable media can be involved in conveying one or more sequences of one or more instructions to processor PRO for execution. For example, the instructions can initially be held on the magnetic disk of a remote computer. The remote computer can load the instructions into dynamic memory and transmit the instructions via a telephone line using a modem. The local modem of computer system CS can receive the data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector connected to bus BS can receive the data carried by the infrared signal and place the data on bus BS. Bus BS conveys the data to main memory MM, and processor PRO fetches and executes the instructions therefrom. The instructions received by main memory MM can optionally be stored in storage device SD before or after execution by processor PRO.

[0119] Computer system CS may also include a communication interface CI connected to bus BS. Communication interface CI provides a bi-directional data communication connection to network link NDL connected to local network LAN. For example, communication interface CI can be an integrated services digital network (ISDN) card or a modem that provides a data communication connection to a corresponding type of telephone line. As another example, communication interface CI can be a local area network (LAN) card that provides a data communication connection to a compatible LAN. A wireless link can also be implemented. In such an implementation, communication interface CI transmits and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0120] A network link NDL typically provides data communication to other data devices via one or more networks. For example, the network link NDL can be connected to a host computer HC via a local area network LAN. This includes data communication services provided via the worldwide packet data communication network currently commonly referred to as the "Internet" INT. The local area network LAN (Internet) can use electrical, electromagnetic, or optical signals that carry digital data streams. Signals via various networks for transmitting digital data between a computer system CS, and signals via the network data link NDL and the communication interface CI are exemplary forms of carrier waves for transmitting information.

[0121] The computer system CS can send messages and receive data including program code via a network, a network data link NDL, and a communication interface CI. In the example of the Internet, the host computer HC can send the requested code of an application program via the Internet INT, the network data link NDL, the local area network LAN, and the communication interface CI. One of the downloaded applications may, for example, provide all or part of the methods described herein. The received code can be executed by a processor PRO upon reception and / or stored in a storage device SD or other non-volatile storage for later execution. In this way, the computer system CS can obtain application code in the form of a carrier wave.

[0122] Various embodiments of the present system and method are disclosed in the list of the following numbered paragraphs. In the following, further features, characteristics, and exemplary technical solutions of the present disclosure are explained from the perspective of paragraphs that can be arbitrarily claimed in any combination. 1. A system configured to convert spatially coherent radiation completely or partially into spatially incoherent radiation, comprising: a splitter configured to receive the spatially coherent radiation and split it into channels; optical paths of different lengths coupled to the channels, the different lengths being configured to convert the spatially coherent radiation completely or partially into spatially incoherent radiation; and a combiner coupled to the optical paths and configured to combine the completely or partially spatially incoherent radiation from the optical paths into a single multimode output. 2. The system according to claim 1, wherein the optical paths are configured such that radiation in a single channel does not become incoherent because it is single-mode radiation, but becomes incoherent with respect to radiation in adjacent channels due to an appropriate path difference. 3. The system according to any of the preceding claims, wherein the splitter, the optical paths, and the combiner are integrated in an integrated optical body. 4. The system according to any of the preceding claims, wherein the integrated optical body includes a microchip manufactured using complementary metal-oxide semiconductor (CMOS) and / or indium phosphide manufacturing technology. 5. The system according to any of the preceding claims, wherein the waveguide layer of the integrated optical body is formed from silicon, silicon-on-oxide, indium phosphide, silicon nitride, and / or aluminum oxide. 6. The system according to any of the preceding claims, comprising a stacked integrated optical body forming a multi-dimensional array of waveguide emitters. 7. The system according to any of the preceding claims, wherein the system is passive and has no moving parts or electrically controlled components. 8. The system according to any of the preceding claims, wherein the splitter is configured to split the spatially coherent radiation into at least 2 to 100 channels. 9. The system according to any of the preceding claims, wherein the splitter is a binary tree beam splitter or a non-binary beam splitter. 10. The system according to any of the preceding paragraphs, wherein the splitter is a multimode interference (MMI) device. 11. The system according to any of the preceding paragraphs, wherein each optical path comprises a waveguide and forms part of a corresponding channel. 12. The system according to any of the preceding paragraphs, wherein the different lengths are configured to reduce or eliminate interference between the radiations passing through the different optical paths and to convert the spatially coherent radiation into the fully or partially spatially incoherent radiation. 13. The system according to any of the preceding paragraphs, wherein the optical path length difference from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation. 14. The system according to any of the preceding paragraphs, wherein the combiner includes an optical fiber array. 15. The system according to any of the preceding paragraphs, wherein the combiner includes a photonic lantern. 16. The system according to any of the preceding paragraphs, wherein the combiner includes a microlens array and / or one or more macroscopic lenses. 17. The system according to any of the preceding paragraphs, wherein the spatially coherent radiation includes visible light. 18. The system according to any of the preceding paragraphs, further comprising a multimode fiber configured to receive a single multimode output from the combiner. 19. The system according to any of the preceding paragraphs, further comprising a controller configured to actively control the outputs from the individual optical paths. 20. The system according to any of the preceding paragraphs, wherein the spatially coherent radiation is converted into the fully or partially spatially incoherent radiation for measurements related to semiconductor manufacturing processes. 21. A method for converting spatially coherent radiation into fully or partially spatially incoherent radiation, comprising: using a splitter to receive the spatially coherent radiation and split it into channels; using optical paths of different lengths coupled to the channels to convert the spatially coherent radiation into the fully or partially spatially incoherent radiation; and using a combiner coupled to the optical paths to combine the fully or partially spatially incoherent radiation from the optical paths into a single multimode output. 22. The method according to any of the preceding claims, wherein the optical paths are configured such that radiation in a single channel does not become incoherent because it is single-mode radiation, but becomes incoherent with respect to radiation in adjacent channels due to an appropriate path difference. 23. The method according to any of the preceding claims, wherein the splitter, the optical paths, and the combiner are integrated in an integrated optical body. 24. The method according to any of the preceding claims, wherein the integrated optical body includes a microchip manufactured using complementary metal-oxide-semiconductor (CMOS) and / or indium phosphide manufacturing technology. 25. The method according to any of the preceding claims, wherein the waveguide layer of the integrated optical body is formed from silicon, silicon-on-oxide, indium phosphide, silicon nitride, and / or aluminum oxide. 26. The method according to any of the preceding claims, comprising a stacked integrated optical body forming a multi-dimensional array of waveguide emitters. 27. The method according to any of the preceding claims, wherein the splitter, the optical paths, and the combiner do not have movable parts or electrically controlled components. 28. The method according to any of the preceding claims, wherein the splitter is configured to split the spatially coherent radiation into at least 2 to 100 channels. 29. The method according to any of the preceding claims, wherein the splitter is a binary tree beam splitter or a non-binary beam splitter. 30. The method according to any of the preceding paragraphs, wherein the splitter is a multimode interference (MMI) device. 31. The method according to any of the preceding paragraphs, wherein each optical path comprises a waveguide and forms part of a corresponding channel. 32. The method according to any of the preceding paragraphs, wherein the different lengths are configured to reduce or eliminate interference between the radiations passing through different optical paths, and to convert the spatially coherent radiation into the completely or partially spatially incoherent radiation. 33. The method according to any of the preceding paragraphs, wherein the optical path length difference from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation. 34. The method according to any of the preceding paragraphs, wherein the combiner comprises an optical fiber array. 35. The method according to any of the preceding paragraphs, wherein the combiner comprises a photonic lantern. 36. The method according to any of the preceding paragraphs, wherein the combiner comprises a microlens array and / or one or more macroscopic lenses. 37. The method according to any of the preceding paragraphs, wherein the spatially coherent radiation comprises visible light. 38. The method according to any of the preceding paragraphs, further comprising a multimode fiber configured to receive a single multimode output from the combiner. 39. The method according to any of the preceding paragraphs, further comprising a controller configured to actively control the outputs from the individual optical paths. 40. The method according to any of the preceding paragraphs, wherein the spatially coherent radiation is converted into the completely or partially spatially incoherent radiation for measurements related to semiconductor manufacturing processes. 41. A system configured to convert spatially coherent radiation completely or partially into spatially incoherent radiation in order to reduce the speckle in illumination for measurement as part of a semiconductor manufacturing process, the system being composed of a combination of passive integrated optical elements so as to reduce the threats of volume and mechanical wear compared to a mechanical coherence scrambler, the system comprising a radiation source configured to generate the spatially coherent radiation and a passive integrated optical body, the integrated optical body comprising a splitter configured to receive the spatially coherent radiation and split it into channels, the splitter being a binary tree beam splitter and / or a multimode interference (MMI) device, and optical paths having different lengths coupled to the channels, the different lengths being configured to convert the spatially coherent radiation conducted by the optical paths into the completely or partially spatially incoherent radiation, the different lengths being configured to reduce or eliminate interference between the radiation passing through the different optical paths, whereby the spatially coherent radiation is converted into the completely or partially spatially incoherent radiation, the optical paths being configured such that the radiation of a single channel does not become incoherent because the radiation of a single channel is single-mode radiation, but with an appropriate path difference, the radiation of the single channel becomes incoherent with respect to the radiation of an adjacent channel, an optical path, a combiner configured to combine the completely or partially spatially incoherent radiation from the optical paths into a single multimode output, and a multimode fiber configured to receive the single multimode output from the combiner and guide the completely or partially spatially incoherent radiation for measurement. 42. The system according to any of the preceding claims, wherein the passive integrated optical body comprises a silicon, silicon-on-oxide, indium phosphide, silicon nitride, and / or aluminum oxide microchip. 43. The system according to any of the preceding claims, comprising a stacked integrated optical body forming a multi-dimensional array of waveguide emitters. 44. The system according to any of the preceding items, wherein the optical path length difference from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation. 45. The system according to any of the preceding items, wherein the combiner includes an optical fiber array, a photonic lantern, a microlens array, and / or one or more macroscopic lenses.

[0123] The concepts disclosed herein are associated with any general imaging system for imaging features below the wavelength and are particularly useful for emerging imaging technologies that can generate increasingly shorter wavelengths. Emerging technologies already in use include EUV (extreme ultraviolet), DUV lithography that can generate a wavelength of 193 nm using an ArF laser, and further DUV lithography that can generate a wavelength of 157 nm using a fluorine laser. Furthermore, EUV lithography can generate wavelengths in the range of 20 - 5 nm by using a synchrotron or by applying high-energy electrons to a material (either solid or plasma) to generate photons within this range.

[0124] The concepts disclosed herein can be used for imaging on a substrate such as a silicon wafer, but it should be understood that the disclosed concepts can be used in any type of lithographic imaging system, such as those used for imaging on substrates other than silicon wafers. Furthermore, the disclosed combinations and sub - combinations of elements can constitute individual embodiments.

[0125] The above description is illustrative, not restrictive. Thus, it will be apparent to those skilled in the art that modifications can be made as described without departing from the scope of the claims set forth below.

Claims

1. A system configured to convert spatially coherent radiation completely or partially into spatially incoherent radiation, comprising: a splitter configured to receive the spatially coherent radiation and split it into channels; optical paths of different lengths coupled to the channels, the different lengths being configured to convert the spatially coherent radiation completely or partially into spatially incoherent radiation; a combiner coupled to the optical paths and configured to combine the completely or partially spatially incoherent radiation from the optical paths into a single multimode output; and the system comprising the above components.

2. The system according to claim 1, wherein the optical paths are configured such that radiation in a single channel does not become incoherent because the radiation in a single channel is single-mode radiation, but the radiation in the single channel becomes incoherent with respect to the radiation in adjacent channels due to an appropriate path difference.

3. The system according to claim 1 or 2, wherein the splitter, the optical paths, and the combiner are integrated in an integrated optical body.

4. The system according to claim 3, wherein the integrated optical body includes a microchip manufactured using complementary metal oxide semiconductor (CMOS) and / or indium phosphide manufacturing technology.

5. The system according to claim 3 or 4, wherein the waveguide layer of the integrated optical body is formed from silicon, silicon-on-oxide, indium phosphide, silicon nitride, and / or aluminum oxide.

6. The system according to any one of claims 1 to 5, comprising a stacked integrated optical body forming a multi-dimensional array of waveguide emitters.

7. The system according to any one of claims 1 to 6, wherein the system is passive and has no moving parts or electrically controlled components.

8. The system according to any one of claims 1 to 7, wherein the splitter is configured to split the spatially coherent radiation into at least 2 to 100 channels.

9. The system according to any one of claims 1 to 8, wherein the splitter is a binary tree beam splitter or a non-binary beam splitter.

10. The system according to any one of claims 1 to 9, wherein the splitter is a multimode interference (MMI) device.

11. The system according to any one of claims 1 to 10, wherein each optical path comprises a waveguide and forms part of a corresponding channel.

12. The system according to any one of claims 1 to 11, wherein the different lengths are configured to reduce or eliminate interference between the radiations passing through the different optical paths, thereby converting the spatially coherent radiation into the fully or partially spatially incoherent radiation.

13. The system according to any one of claims 1 to 12, wherein the optical path length difference from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation.

14. The system according to any one of claims 1 to 13, wherein the combiner includes an optical fiber array.

15. The system according to any one of claims 1 to 13, wherein the combiner includes a photonic lantern.

16. The system according to any one of claims 1 to 13, wherein the combiner includes a microlens array and / or one or more macroscopic lenses.

17. The system according to any one of claims 1 to 16, wherein the spatially coherent radiation includes visible light.

18. The system according to any one of claims 1 to 17, further comprising a multimode fiber configured to receive a single multimode output from the combiner.

19. The system according to any one of claims 1 to 18, further comprising a controller configured to actively control the outputs from the individual optical paths.

20. The system according to any one of claims 1 to 19, wherein the spatially coherent radiation is converted into the fully or partially spatially incoherent radiation for measurements related to semiconductor manufacturing processes.

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