Passive integrated optical system and method for reducing spatial optical coherence

Abstract

Passive integrated optical systems and methods are described. For example, the present systems and methods facilitate reduction of spatial optical coherence in source radiation for metrology. The currently coherent scrambler for metrology generally includes one or more (mobile) mechanical components configured to reduce coherence of source radiation. However, these mechanical interferers occupy volume within the system and introduce threats of mechanical wear and / or failure. In contrast, the present systems and methods utilize a combination of passive integrated optical elements to form a phase interference transducer. This reduces or eliminates the use of mechanical components, and improves durability, among other advantages.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. Application No. 63 / 342,305, filed on May 16, 2022, and incorporated herein by reference in its entirety. Technical Field

[0003] The description relates to optical systems and methods for metrology. Background Art

[0004] A lithographic projection apparatus may, for example, be used in the manufacture of integrated circuits (ICs). A pattern forming device (e.g., a mask) may include or provide a pattern corresponding to a separate layer of the IC (a "design layout"), and the pattern may be transferred to a target portion (e.g., including one or more dies) on a substrate (e.g., a silicon wafer) that has been coated with a layer of radiation-sensitive material ("resist") by methods such as irradiating the target portion through the pattern on the pattern forming device. Typically, a single substrate includes a plurality of adjacent target portions to which the pattern is transferred continuously by the lithographic projection apparatus, one target portion at a time. In one type of lithographic projection apparatus, the pattern on the entire pattern forming device is transferred to one target portion in one operation. Such an apparatus is generally referred to as a stepper. In an alternative apparatus generally referred to as a step-scan apparatus, the projection beam is scanned over the pattern forming device along a given reference direction (the "scanning" direction) while moving the substrate parallel to or antiparallel to the reference direction. Different portions of the pattern on the pattern forming device are gradually transferred to one target portion. Typically, since the lithographic projection apparatus will have a demagnification M (eg 4), the speed F at which the substrate is moved will be 1 / M times that of the projection beam scanning patterning device. Further information on the lithographic apparatus described herein can be gleaned, for example, from US 6,046,792, which is incorporated herein by reference.

[0005] Before the pattern is transferred from the pattern forming device to the substrate, the substrate may undergo various procedures, such as primer coating, resist coating and soft baking. After exposure, the substrate can undergo other procedures ("post-exposure procedures"), such as post-exposure baking (PEB), development, hard baking and measurement / inspection of the transfer pattern. This array of procedures is used as the basis for manufacturing the individual layers of the device (e.g., IC). Then, the substrate can undergo various processes, such as etching, ion implantation (doping), metallization, oxidation, deposition, chemical mechanical polishing, etc., all of which are intended to complete the individual layers of the device. If several layers are needed in the device, the entire procedure or its variant is repeated for each layer. Ultimately, the device will be present in each target portion on the substrate. Then, these devices are separated from each other by techniques such as cutting or sawing, so that the individual devices can be mounted on a carrier, connected to pins, etc.

[0006] Therefore, manufacturing devices such as semiconductor devices typically involves processing a substrate (e.g., a semiconductor wafer) using a number of fabrication processes to form various features and multiple layers of the device. Such layers and features are typically manufactured and processed using, for example, deposition, lithography, etching, deposition, chemical mechanical polishing, and ion implantation. Multiple devices can be fabricated on multiple bare chips on a substrate and then separated into individual devices. The device manufacturing process can be considered a patterning process. The patterning process involves a patterning step, such as optical and / or nanoimprint lithography using a pattern forming device in a lithography apparatus to transfer the pattern on the pattern forming device to the substrate, and typically but optionally involves one or more related pattern processing steps, such as resist development by a developing device, baking of the substrate using a baking tool, etching, deposition, etc. using a pattern using an etching device.

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

[0008] As semiconductor manufacturing processes continue to advance, following a trend generally referred to as "Moore's Law," the size of functional elements has been continuously reduced, while the number of functional elements (such as transistors) per device has steadily increased for decades. At the current state of the art, 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 illumination source, thereby creating individual functional elements with dimensions well below 100 nm (i.e., less than half the wavelength of the radiation from the illumination source (e.g., a 193 nm illumination source)).

[0009] The process in which features with dimensions smaller than the classical resolution limit of the lithographic projection apparatus are printed is generally referred to as low-k1 lithography, according to the resolution formula CD = k1 × λ / NA, where λ is the wavelength of the radiation employed (currently 248 nm or 193 nm in most cases), NA is the numerical aperture of the projection optics in the lithographic projection apparatus, CD is the "critical dimension", usually the minimum feature size printed, and k1 is an empirical resolution factor. In general, the smaller the k1, the more difficult it is to reproduce on the substrate a pattern similar to the shape and size planned by the designer in order to achieve specific electrical functionality and performance. In order to overcome these difficulties, complex fine-tuning steps are applied to the lithographic projection apparatus, the design layout or the pattern forming device. For example, these include but are not limited to the optimization of NA and optical coherence settings, customized illumination schemes, the use of phase-shifted pattern forming devices, optical proximity correction (OPC, sometimes also called "optical and process correction") in the design layout, or other methods generally defined as "resolution enhancement technology" (RET). Metrology is an integral part of these fine-tuning steps. Summary of the invention

[0010] Passive integrated optical systems and methods are described. For example, the present system and method facilitates reducing the spatial optical coherence in the source radiation used for measurement. Current interference interferometers used for measurement typically include one or more (moving) mechanical components configured to reduce the coherence of the source radiation. However, these mechanical interference interferometers take up volume within the system and introduce the threat of mechanical wear and / or failure. In contrast, the present system and method utilize a combination of passive integrated optical components to form an interference interferometer. This reduces or eliminates the use of mechanical components and improves other advantages such as durability.

[0011] According to an embodiment, a system configured to convert spatially coherent radiation into fully or partially spatially incoherent radiation is provided. The system includes a splitter configured to receive spatially coherent radiation and split the spatially coherent radiation into channels. The system includes an optical path having different lengths coupled to the channels. The different lengths are configured to convert spatially coherent radiation into fully or partially spatially incoherent radiation. The system includes a combiner coupled to the optical path and configured to combine fully or partially spatially incoherent radiation from the optical path into a single multimode output.

[0012] In some embodiments, the optical paths are configured such that radiation in a single channel does not become incoherent because it is single mode radiation, but with appropriate path differences, radiation in a single channel becomes incoherent relative to radiation in adjacent channels.

[0013] 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 made using complementary metal oxide semiconductor (CMOS) and / or indium phosphide manufacturing technology, photolithography and / or electron beam writing technology and / or other technologies. In some embodiments, the waveguide layer of the integrated optical body is formed of silicon, silicon on oxide, indium phosphide, silicon nitride and / or aluminum oxide.

[0014] In some embodiments, the system includes stacked integrated optical bodies forming a multi-dimensional array of waveguide launchers.

[0015] In some embodiments, the system is passive, with no moving parts or electronically controlled components.

[0016] In some embodiments, the splitter is configured to split the 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 multi-mode interference (MMI) device.

[0017] In some embodiments, each optical path comprises a waveguide and forms part of a corresponding channel.

[0018] In some embodiments, the different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, which converts spatially coherent radiation into fully or partially spatially incoherent radiation.

[0019] In some embodiments, the difference in optical path length from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation.

[0020] In some embodiments, the combiner comprises an optical fiber array. In some embodiments, the combiner comprises a photonic lantern. In some embodiments, the combiner comprises a microlens array and / or one or more macro lenses.

[0021] In some embodiments, the spatially coherent radiation includes visible light.

[0022] In some embodiments, the system further includes a multimode optical fiber configured to receive the single multimode output from the combiner.

[0023] In some embodiments, the system further includes a controller configured to actively control outputs from the individual optical paths.

[0024] In some embodiments, spatially coherent radiation is converted to fully or partially spatially incoherent radiation for use in metrology associated with semiconductor manufacturing processes.

[0025] According to another embodiment, a method for converting spatially coherent radiation into fully or partially spatially incoherent radiation is provided. The method includes: using a splitter, receiving the spatially coherent radiation and splitting the spatially coherent radiation into channels; using optical paths with different lengths coupled to the channels, converting the spatially coherent radiation into fully or partially spatially incoherent radiation; and using a combiner coupled to the optical paths, combining the fully or partially spatially incoherent radiation from the optical paths into a single multimode output.

[0026] According to another aspect, a system is provided that is configured to convert spatially coherent radiation into fully or partially spatially incoherent radiation to reduce speckle in illumination for measurement as part of a semiconductor manufacturing process. The system is configured with a combination of passive integrated optical elements so that the volume and threat of mechanical wear is reduced relative to mechanical interference frequency converters. The system includes a source configured to generate spatially coherent radiation and a passive integrated optical body. The body includes a separator configured to receive spatially coherent radiation and split the spatially coherent radiation into channels. The separator includes a binary tree beam splitter and / or a multimode interference (MMI) device. The body includes optical paths with different lengths coupled to the channels. The different lengths are configured to convert spatially coherent radiation conducted by the optical paths into fully or partially spatially incoherent radiation. The different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, which converts the spatially coherent radiation into fully or partially spatially incoherent radiation. The optical path is configured such that radiation in a single channel does not become incoherent because the radiation in the single channel is single mode radiation, but with appropriate path differences, the radiation in the single channel becomes incoherent relative to radiation in adjacent channels. The body includes a combiner configured to combine fully or partially spatially incoherent radiation from the optical path into a single multimode output. The system includes a multimode optical fiber configured to receive the single multimode output from the combiner and direct the fully or partially spatially incoherent radiation for measurement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above aspects and other aspects and features will become apparent to those of ordinary skill in the art upon reviewing the following description of specific embodiments in conjunction with the accompanying drawings.

[0028] Figure 1 A lithographic apparatus according to an embodiment is schematically depicted.

[0029] Figure 2 Embodiments of a lithocell or cluster according to embodiments are schematically depicted.

[0030] Figure 3 An example inspection system according to an embodiment is schematically depicted.

[0031] Figure 4An example metrology technique according to an embodiment is schematically depicted.

[0032] Figure 5 The diagram illustrates the relationship between the radiation irradiation spot and the measurement target of the inspection system according to the embodiment.

[0033] Figure 6 A system for converting spatially coherent radiation into fully or partially spatially incoherent radiation according to an embodiment is illustrated.

[0034] Figure 7 The separator of the present system formed as a binary tree according to an embodiment is illustrated.

[0035] Figure 8 The optical path of the present system according to an embodiment is illustrated.

[0036] Fig. 9 A combiner of the present system formed from an array of optical fibers according to an embodiment is illustrated.

[0037] Fig.10 A combiner of the present system formed of photonic lanterns according to an embodiment is illustrated.

[0038] Fig.11 A combiner of the present system formed of a microlens array and a macrolens according to an embodiment is illustrated.

[0039] Fig.12 A stacked integrated optical body according to an embodiment is illustrated.

[0040] Fig.13 A method for converting spatially coherent radiation into fully or partially spatially incoherent radiation according to an embodiment is illustrated.

[0041] Fig.14 is a block diagram of an example computer system according to an embodiment. DETAILED DESCRIPTION

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

[0043] Previous metrology systems have used intense broadband light sources to accurately characterize weak metrology targets over a wide range of wavelengths to address challenges such as process robustness and opaque layers. One of the challenges associated with these light sources is the coherence of the light they output. The light can come from a spatially coherent laser source, which can cause speckle in the metrology image. For scatter measurements that rely on accurately determining the angularly resolved spectrum, this can cause unwanted errors. Interference interferometers that are configured to reduce the coherence of light are known. An example is a rotating diffuser. The scattering of coherent light through a diffuse medium causes speckle in the transmitted light. By rotating the diffuser, the speckle pattern changes so that the effects of the speckle are averaged over a sufficiently long period of time. However, these and other mechanical interference interferometers take up volume within the system, introduce threats of mechanical wear and / or failure, generate unwanted vibrations, and / or have other disadvantages. For example, existing interference interferometers can often be as large as a shoebox or larger. The mechanical motion limits the speed at which the speckle can be averaged, so a minimum measurement time is required. This becomes very challenging when the measurement system requires switching and measurement times of less than one millisecond.

[0044] In contrast, the present system and method utilize a combination of passive integrated optical components to form a coherent interferometer without moving or electrically controlled parts. This reduces or eliminates the use of mechanical parts, requires less physical volume, and improves durability, among other advantages. The present system and method apply photonic integration technology and include compact, fast, and low-cost coherent interferometer devices. Wavelength-filtered radiation from a source is split into channels and provided to different optical paths (multiple waveguides). By making the optical path difference of each of these optical paths / waveguides relative to its neighbors greater than the coherence length of the radiation, the radiation in the waveguides becomes mutually incoherent. For example, if necessary, a microlens array or photon lantern can be used to reorganize the radiation into a multimode optical fiber. The radiation can be further processed using other existing measurement system components. Since coherent interferometers occur through optical path length differences (rather than mechanical motion), integrated optical components can be used that occupy only a very small physical volume (e.g., a volume much smaller than a typical shoebox). These and other features are described below in additional detail.

[0045] By way of brief introduction, the following description relates to semiconductor device manufacturing and patterning processes. The following paragraphs also describe several components of systems and / or methods for semiconductor device measurement. For example, these systems and methods can be used to measure overlay, alignment, etc. in semiconductor device manufacturing processes, or for other operations.

[0046] Although specific reference may be made to the manufacture of integrated circuits (ICs) of semiconductor devices, it should be understood that the description has many other possible applications. For example, it can be used in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid crystal display panels, thin film magnetic heads, etc. Those skilled in the art will appreciate that in the context of such alternative applications, any use of the terms "reticle", "wafer" or "die" herein should be considered interchangeable with the more general terms "mask", "substrate" and "target portion", respectively.

[0047] The term "projection optics" should be broadly interpreted to cover various types of optical systems, including, for example, refractive optics, reflective optics, apertures, and reflective-refractive optics. The term "projection optics" may also include components that operate according to any of these design types to collectively or individually direct, shape, or control a projection beam of radiation. The term "projection optics" may include any optical component in a lithographic projection apparatus, regardless of where the optical component is located on the optical path of the lithographic projection apparatus. Projection optics may include optical components for shaping, adjusting, and / or projecting radiation from a source before the radiation passes through a pattern forming device and / or optical components for shaping, adjusting, and / or projecting radiation after the radiation passes through a pattern forming device. Projection optics typically do not include a source and a pattern forming device.

[0048] Figure 1 An embodiment of a lithographic apparatus LA is schematically depicted. 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. mask table) MT constructed to support a pattern forming device (e.g. mask) MA and connected to a first positioner PM configured to accurately position the pattern forming device according to certain parameters; a substrate table (e.g. wafer stage) WT (e.g. WTa, WTb or both) configured to hold a substrate (e.g. a resist coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate according to certain parameters; and a projection system (e.g. refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the pattern forming device MA onto a target portion C (e.g. comprising one or more dies and generally referred to as a field) of the substrate W. The projection system is supported on a reference frame RF. As depicted, the apparatus is of a transmissive type (e.g. employing a transmissive mask). Alternatively, the device may be reflective (eg using a programmable mirror array or using a reflective mask).

[0049] The illuminator IL receives a radiation beam from a radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In this case, the source is not considered to form part of the lithographic apparatus, and the radiation beam is transferred from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising, for example, suitable directing mirrors and / or a beam expander. In other cases, the source may be an integral part of the apparatus, for example when the source is a mercury lamp. The source SO and the illuminator IL and, if desired, the beam delivery system BD may be referred to as a radiation system.

[0050] The illuminator IL may modify the intensity distribution of the beam. The illuminator may be arranged to limit the radial extent of the radiation beam so that the intensity distribution is non-zero within an annular region in a pupil plane of the illuminator IL. Additionally or alternatively, the illuminator IL may be operable to limit the distribution of the beam in the pupil plane so that the intensity distribution is non-zero in a plurality of equally spaced sectors in the pupil plane. The intensity distribution of the radiation beam in the pupil plane of the illuminator IL may be referred to as an illumination pattern.

[0051] The illuminator IL may include an adjuster AD configured to adjust the (angular / spatial) intensity distribution of the beam. Typically, at least the outer and / or inner radial extent (generally referred to as σ outer and σ inner, respectively) of the intensity distribution in a pupil plane of the illuminator may be adjusted. The illuminator IL may be operable to change the angular distribution of the beam. For example, the illuminator may be operable to change the number and angular extent of sectors in the pupil plane in which the intensity distribution is non-zero. By adjusting the intensity distribution of the beam in the pupil plane of the illuminator, different illumination modes may be achieved. For example, by limiting the radial extent and the angular extent of the intensity distribution in the pupil plane of the illuminator IL, the intensity distribution may have a multipolar distribution, such as, for example, a dipole, quadrupole or hexapole distribution. For example, the desired illumination mode may be obtained by inserting an optical device providing the illumination mode into the illuminator IL or by using a spatial light modulator.

[0052] The illuminator IL may be 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 on the pupil plane of the illuminator IL may be referred to as a polarization mode. Using different polarization modes may allow greater contrast to be achieved in the image formed on the substrate W. The radiation beam may be unpolarized. Alternatively, the illuminator may be arranged to linearly polarize the radiation beam. The polarization direction of the radiation beam may vary across the pupil plane of the illuminator IL. In different regions in the pupil plane of the illuminator IL, the polarization direction of the radiation may be different. The polarization state of the radiation may be selected according to the illumination mode. For a multipolar illumination mode, the polarization of each pole of the radiation beam may be generally perpendicular to the position vector of the pole in the pupil plane of the illuminator IL. For example, for a dipole illumination mode, the radiation may be linearly polarized in a direction substantially perpendicular to a line that bisects two opposing sectors of the dipole. The radiation beam may be polarized in one of two different orthogonal directions, which may be referred to as an X polarization state and a Y polarization state. For a quadrupole illumination mode, the radiation in the sector of each pole may be linearly polarized in a direction substantially perpendicular to a line that bisects the sector. This polarization mode may be referred to as XY polarization. Similarly, for a hexapole illumination mode, the radiation in a sector of each pole may be linearly polarized in a direction substantially perpendicular to a line bisecting the sector. This polarization mode may be referred to as TE polarization.

[0053] In addition, the illuminator IL typically includes various other components, such as an integrator IN and a condenser CO. The illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping or controlling the radiation. The illuminator thus provides a conditioned radiation beam B having a desired uniformity and intensity distribution in its cross-section.

[0054] The support structure MT supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions such as, for example, whether the patterning device is held in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic or other clamping techniques to hold the patterning device. The support structure can be a frame or a table, which can be fixed or movable as required, for example. The support structure can ensure that the patterning device is located at a desired position, for example relative to a projection system. Any use of the term "reticle" or "mask" herein can be considered to be synonymous with the more general term "patterning device".

[0055] The term "patterning device" as used herein should be broadly interpreted as referring to any device that can be used to impart a pattern in a target portion of a substrate. In an embodiment, a patterning device is any device that can be used to impart a radiation beam with a pattern in its cross-section to create a pattern in a target portion of a substrate. It should be noted that the pattern imparted to the radiation beam may not correspond exactly to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so-called assist features. Typically, the pattern imparted to the radiation beam will correspond to a specific functional layer in a device (such as an integrated circuit) created in the target portion of the device.

[0056] The pattern forming device may be transmissive or reflective. Examples of pattern forming devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography and include mask types such as binary mask types, alternating phase shift mask types, and attenuated phase shift mask types, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam reflected by the matrix of mirrors.

[0057] The term "projection system" should be broadly interpreted as covering any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems or any combination thereof, as is appropriate with regard to the exposure radiation used or other factors such as the use of immersion liquid or the use of a vacuum. Any use of the term "projection lens" herein may be considered synonymous with the more general term "projection system".

[0058] The projection system PS may include multiple optical (e.g., lens) elements and may also include an adjustment mechanism that is configured to adjust one or more optical elements to correct aberrations (phase variations across the pupil plane throughout the field). To achieve this, the adjustment mechanism may be operable to manipulate one or more optical (e.g., lens) elements within the projection system PS in one or more different ways. The projection system may have a coordinate system in which its optical axis extends in the z-direction. The adjustment mechanism may be 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 elements may be in any direction (x, y, z, or a combination thereof). Although rotation about the z-axis can be used for non-rotationally symmetric aspheric optical elements, the tilt of the optical element is typically out of a plane perpendicular to the optical axis by rotating about an axis in the x and / or y directions. Deformations of the optical element may include low-frequency shapes (e.g., astigmatism) and / or high-frequency shapes (e.g., free-form aspheric surfaces). Deformation of the optical element may be performed, for example, by applying a force on one or more sides of the optical element using one or more actuators and / or heating one or more selected regions of the optical element using one or more heating elements. Typically, it may not be possible to adjust the projection system PS to correct for apodization (transmission variations in the pupil plane). When designing a patterning device (e.g., mask) MA for the lithographic apparatus LA, a transmission map of the projection system PS may be used. Using computational lithography techniques, the patterning device MA may be designed to at least partially correct for apodization.

[0059] 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 without a substrate dedicated to, for example, facilitating measurement and / or cleaning, located below the projection system, etc.). In such a "multi-stage" machine, additional tables may be used in parallel, or preparatory steps may be performed on one or more tables while one or more other tables are being used for exposure. For example, alignment measurements using the alignment sensor AS and / or level (height, tilt, etc.) measurements using the level sensor LS may be performed.

[0060] The lithographic apparatus may also be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, such as water, to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, such as the space between the pattern forming device and the projection system. Immersion techniques are well known in the art to increase the numerical aperture of the projection system. The term "immersion" as used herein does not mean that structures such as the substrate must be submerged in the liquid, but rather, immersion only means that the liquid is located between the projection system and the substrate during exposure.

[0061] In operation of the lithographic apparatus, a radiation beam is conditioned and provided by an illumination system IL. The radiation beam B is incident on and patterned by a pattern forming device (e.g. a mask) MA, which is held on a support structure (e.g. a mask table) MT. After traversing the pattern forming device MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position sensor IF (e.g. an interferometric measurement device, a linear encoder, a 2D encoder or a capacitive sensor), the substrate table WT can be accurately moved, for example to position different target portions C in the path of the radiation beam B. Similarly, for example after mechanical retrieval from a mask library or during scanning, a first positioner PM and a further position sensor (not in Figure 1 The support structure MT (as explicitly depicted in Figure 1) can be used to accurately position the pattern forming device MA relative to the path of the radiation beam B. Typically, movement of the support structure MT can be achieved with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming part of the first positioner PM. Similarly, movement of the substrate table WT can be achieved using a long-stroke module and a short-stroke module forming part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure MT may be connected only to the short-stroke actuator, or may be fixed. The pattern forming device MA and the substrate W may be aligned using pattern forming device alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks occupy dedicated target portions, they may be located in the space between target portions (these are referred to as scribe alignment marks). Similarly, in the case where more than one die is provided on the pattern forming device MA, the pattern forming device alignment marks may be located between the die.

[0062] The depicted apparatus can be used in at least one of the following modes. In step mode, the support structure MT and the substrate table WT remain substantially stationary while a pattern imparted to a radiation beam is projected onto a target portion C at one time (i.e. a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. In scan mode, the support structure MT and the substrate table WT are scanned synchronously while a pattern imparted to a radiation beam is projected onto a target portion C (i.e. a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT may be determined by the (de-)magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target portion (in the non-scanning direction) in a single dynamic exposure, while the length of the scanning movement determines the height of the target portion (in the scanning direction). In another mode, the support structure MT remains essentially stationary, thereby holding the programmable patterning device, and the substrate table WT is moved or scanned, while a pattern imparted to the radiation beam is projected onto a target portion C. In this mode, typically a pulsed radiation source is employed, and the programmable patterning device is updated as required after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography, which makes use of a programmable patterning device (such as a programmable mirror array of the type cited above).

[0063] Combinations and / or variations on the above described modes of use or entirely different modes of use may also be employed.

[0064] The substrate may be processed before or after exposure, such as in a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or in a metrology or inspection tool. The disclosure herein may be applied to such and other substrate processing tools, where applicable. In addition, a substrate may be processed more than once, such as to create a multi-layer IC, so that the term substrate as used herein may also refer to a substrate that already includes multiple processed layers.

[0065] The terms "radiation" and "beam" as used herein with respect to lithography encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., having a wavelength in the range of 5 nm to 20 nm), as well as particle beams, such as ion beams or electron beams.

[0066] Various patterns provided on or by a pattern forming device may have different process windows, i.e., the space of process variables under which the pattern will be produced within specifications. Examples of pattern specifications associated with potential system defects include checking for necking, line pullback, line thinning, CD, edge placement, overlap, anti-top loss, anti-bite edge, and / or bridging. The process window of a pattern on a pattern forming device or a region thereof may be obtained by merging (e.g., overlapping) the process windows of each individual pattern. The boundaries of the process window of a group of patterns include the boundaries of the process windows of some individual patterns. In other words, these individual patterns limit the process window of the group of patterns.

[0067] like Figure 2 As shown, the lithography apparatus LA may form part of a lithography cell LC, sometimes also referred to as a lithography cell or cluster, which also includes apparatus for performing pre-exposure and post-exposure processes on a substrate. Conventionally, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers DE for developing the exposed resist, one or more cooling plates CH and / or one or more baking plates BK. A substrate handler or robot RO picks up one or more substrates from input / output ports I / O1, I / O2, moves them between different process apparatuses, and then delivers them to a feed station LB of the lithography apparatus. These apparatuses, which are generally collectively referred to as tracks, are controlled by a track control unit TCU, which itself is controlled by a monitoring system SCS, which also controls the lithography apparatus via a lithography control unit LACU. Thus, the different apparatuses may be operated to maximize throughput and processing efficiency.

[0068] In order to ensure that a substrate exposed by a lithography apparatus is correctly and consistently exposed and / or to monitor a portion of a patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., an optical lithography step), it is desirable to inspect a substrate or other object to measure or determine one or more characteristics, such as alignment, overlay (e.g., between structures in an overlay layer or between structures in the same layer that are provided to the layer separately by, for example, a double patterning process), line thickness, critical dimension (CD), focus offset, material properties, etc. Therefore, a manufacturing facility in which a lithography cell LC is located typically also includes a metrology system that measures some or all of the substrates W ( Figure 1 ) or other objects in the lithography cell. The metrology system may be part of the lithography cell LC, for example it may be a lithography apparatus LA (such as an alignment sensor AS ( Figure 1 )).

[0069] The one or more measured parameters may include, for example, alignment, overlay between successive layers formed in or on a patterned substrate, critical dimensions (CD) of features formed in or on a patterned substrate (e.g., critical line width), focus or focus error of an optical lithography step, dose or dose error of an optical lithography step, optical aberrations of an optical lithography step, etc. The measurements are typically performed on one or more dedicated metrology targets provided on the substrate. The measurements may be performed after resist development but before etching, after etching, after deposition, and / or at other times.

[0070] There are various techniques for measuring structures formed in patterning processes, including the use of scanning electron microscopes, image-based measurement tools, and / or various specialized tools. A fast and non-invasive form of specialized measurement tool is a measurement tool in which a radiation beam is directed onto a target on the surface of a substrate and the properties of the scattered (diffraction / reflection) beam are measured. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. Traditionally, this can be referred to as diffraction-based measurement. Applications of such diffraction-based measurement include measurement of overlay, alignment, and the like. For example, overlay and / or alignment can be measured by comparing portions of the diffraction spectrum (e.g., comparing different diffraction orders in the diffraction spectrum of a periodic grating).

[0071] Thus, in a device fabrication process (e.g., a patterning process or a lithography process), a substrate or other object may be subjected to various types of measurements during or after the process. The measurements may determine whether a particular substrate is defective, may establish adjustments to the process and the devices used in the process (e.g., aligning two layers on a substrate or aligning a pattern forming device to a substrate), may measure the performance of the process and the devices, or may be used for other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements, such as ASML YieldStar metrology tools, ASML SMASH metrology systems), 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 (as described in U.S. Pat. No. 6,961,116, which is incorporated herein by reference in its entirety) employs a self-referencing interferometer that produces two overlapping and relatively rotated images of the alignment mark, detects the intensity in the pupil plane where the Fourier transform of the images results in interference, and extracts position information from the phase difference between the diffraction orders of the two images, which manifests itself as intensity variations of the interference orders.

[0072] The measurement results may be provided directly or indirectly to the monitoring system SCS. If an error is detected, adjustments may be made to the exposure of subsequent substrates (particularly if the inspection can be completed quickly enough so that one or more other substrates of the batch are still to be exposed) and / or to subsequent exposures of the exposed substrate. Furthermore, already exposed substrates may be stripped and reworked to improve yield, or discarded to avoid further processing of substrates known to be faulty. In the event that only some target portions of the substrate are faulty, further exposures may be performed only on those target portions that meet the specification. Other manufacturing process adjustments are also under consideration.

[0073] The metrology system may be used to determine one or more characteristics of a substrate structure, in particular how one or more characteristics vary between different substrate structures or how different layers of the same substrate structure vary from layer to layer. The metrology system may be integrated into the lithography apparatus LA or the lithography cell LC, or may be a stand-alone device.

[0074] In order to achieve the measurement, one or more targets are usually provided specifically on the substrate. Typically, the target is specially designed and may include a periodic structure. For example, the target on the substrate may include one or more 1D periodic structures (e.g., geometric features, such as gratings), which are printed so that after development, the periodic structural features are formed by solid resist lines. As another example, the target may include one or more 2D periodic structures (e.g., gratings), which are printed so that after development, one or more periodic structures are formed by solid resist columns or vias in the resist. Alternatively, the bars, columns, or vias may be etched into the substrate (e.g., etched into one or more layers on the substrate).

[0075] Figure 3 An example metrology (inspection) system 10 is depicted that can be used to detect overlay, alignment and / or perform other metrology operations. It includes a radiation or illumination source 2 that projects or otherwise irradiates radiation onto a substrate W (which may typically include metrology marks, for example). The redirected radiation is passed to a sensor such as a spectrometer detector 4 and / or other sensors that measure the spectrum (intensity according to wavelength) of the specularly reflected and / or diffracted radiation, such as, for example Figure 4 The sensor may generate a measurement signal conveying measurement data indicative of the characteristics of the reflected radiation. From this data, the structure or profile generating the detected spectrum may be reconstructed by one or more processors PRO, a generalized example of which is Figure 4 as shown, or may be reconstructed by other operations.

[0076] and Figure 1 Like the lithography apparatus LA in FIG. 1 , one or more substrate tables ( Figure 4) to hold the substrate W during the measurement operation. The one or more substrate tables may be similar in form to Figure 1 The substrate tables WT (WTa or WTb or both) of the inspection system 10 are similar or identical. In examples where the inspection system 10 is integrated with a lithographic apparatus, they may even be identical substrate tables. Coarse and fine positioners may be provided and configured to accurately position the substrate with respect to the measuring optical system. Various sensors and actuators are provided, for example to obtain the position of a target portion of interest (e.g. a measurement mark) of the structure and place it in a position under the objective lens. Typically, many measurements will be made of the target portion of the structure at different positions on the substrate W. The substrate support may be moved in the X and Y directions to obtain different targets, and may be moved in the Z direction to obtain the desired position of the target portion relative to the focus of the optical system. When, for example, in practice the optical system may remain substantially stationary (usually in the X and Y directions, but also possibly in the Z direction) and the substrate moves, it is convenient to think of and describe the operation as if the objective lens is placed in different positions relative to the substrate. As long as the relative position of substrate and optical system is correct, it is in principle unimportant which of these is moving, or whether both are moving, or a combination in which part of the optical system is moving (e.g. in Z and / or tilt direction) while the rest of the optical system is stationary and the substrate is moving (e.g. in X and Y direction, but optionally also in Z and / or tilt direction).

[0077] For typical metrology measurements, the target (portion) 30 on the substrate W may be a 1D grating, which is printed so that after development, the grating bars are formed by solid resist lines (which may be covered by a deposited layer, for example) and / or other materials. Alternatively, the target 30 may be a 2D grating, which is printed so that after development, the grating is formed by solid resist pillars and / or other features in the resist.

[0078] The bars, posts, vias, and / or other features may be etched into or onto the substrate (e.g., etched into 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., bars, posts, vias, etc.) is sensitive to process variations in the patterning process (e.g., optical aberrations in a lithography projection apparatus (such as a projection system), focus variations, dose variations, etc.), such that process variations manifest as variations in the target 30. Therefore, measurement data from the target 30 may be used to determine adjustments to one or more manufacturing processes, and / or used as a basis for making actual adjustments.

[0079] For example, the measurement data from the target 30 may indicate the overlay of the semiconductor device layer. The measurement data from the target 30 may 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 the adjustment of the semiconductor device manufacturing apparatus based on the one or more determined semiconductor device manufacturing process parameters. In some embodiments, this may include, for example, stage position adjustment, or this may include determining adjustments to mask design, measurement target design, semiconductor device design, radiation intensity, radiation incident angle, radiation wavelength, pupil size and / or shape, resist material, and / or other process parameters.

[0080] Figure 5 A plan view of a typical target (eg, measurement mark) 30 is shown and Figure 4 The range of a typical radiation illumination spot S in a system of. Typically, in order to obtain a diffraction spectrum that is not interfered with by surrounding structures, in an embodiment, the target 30 is a periodic structure (e.g., a grating) that is larger than the width (e.g., diameter) of the illumination 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 'underfilled' by the illumination, and the diffraction signal is substantially unaffected by any signal from product features, etc., other than the target itself. For example, the illumination arrangement may be configured to provide illumination of uniform intensity on the back focal plane of the objective. Alternatively, the illumination may be limited to an on-axis or off-axis direction, for example by including an aperture in the illumination path.

[0081] Figure 6 A system 600 for converting spatially coherent radiation into fully or partially spatially incoherent radiation is illustrated. The radiation can be used to obtain measurements from a metrology target and / or for other purposes. The radiation can include illumination, such as visible light and / or other radiation. For example, the target can include one or more metrology marks, such as a diffraction grating target, formed in a substrate such as a semiconductor wafer. The system 600 can form the above relative to Figure 3 For example, system 600 may be a subsystem of system 10. In some embodiments, one or more components of system 600 may be similar to and / or identical to one or more components of system 10. In some embodiments, one or more components of system 600 may replace, be used together with, and / or otherwise enhance one or more components of system 10.

[0082] System 600 provides a new optical design architecture. As described above, system 600 is a passive integrated optical system, which is configured to, for example, reduce the spatial optical coherence in the source radiation used for measurement. Current interference frequency generators for measurement generally include one or more (moving) mechanical components configured to reduce the coherence of the source radiation. However, these mechanical interference frequency generators occupy the volume within the system and introduce the threat of mechanical wear and / or failure. In contrast, system 600 uses a combination of passive integrated optical components to form an interference frequency generator. This reduces or eliminates the use of mechanical components and improves other advantages such as durability. System 600 includes a separator 602, an optical path 604, a combiner 608 and / or other components. In some embodiments, the components of system 600 form a part of a measurement sensor used in a semiconductor manufacturing process.

[0083] In some embodiments, the separator 602, optical path 604, combiner 608 and / or other components of the system 600 are integrated into the integrated optical body 601. In some embodiments, the integrated optical body 601 is passive, with no moving parts or electrically controlled components. For example, in some embodiments, the integrated optical body 601 includes a microchip made using complementary metal oxide semiconductor (CMOS) manufacturing technology, indium phosphide manufacturing technology, photolithography and / or electron beam writing technology, and / or other technologies. The integrated optical platform may include silicon, silicon nitride (Si3N4), indium phosphide (InP), aluminum oxide (Al2O3) (for example, for UV radiation), and / or other platforms. As an example, the waveguide (optical path forming) layer of the integrated optical body can be formed of Si3N4 (for example, for radiation wavelengths as low as about 25nm to 300nm, deep UV requires alternate materials), Si, silicon on oxide, and / or other materials. For example, for wavelengths of 250nm to 400nm, another material other than Si3N4, such as aluminum oxide (Al2O3) or other materials can be used.

[0084] For example, the use of Si3N4 integrated optical platforms facilitates the use of radiation with a bandwidth of approximately 400nm to 1700nm, which is sufficient for measurement systems (e.g. Figure 3 However, for such waveguides, the radiation source power may be an issue, and in situations where it is necessary to handle optical powers greater than 1 W, such waveguides can handle optical powers up to about 1 W. However, system 600 (and / or Figure 3 The system 10) shown may be configured such that wavelength selection required for measurement is performed before the radiation enters the splitter 602, which alleviates the problem of high radiation source power because the power is reduced by limiting the bandwidth.

[0085] The splitter 602 is configured to receive spatially coherent radiation (e.g., from a source) and split it into channels 607, 609, 611, etc. Radiation (e.g., light) from a single channel delivered to a multimode optical fiber (described below) produces the aforementioned (undesirable) speckle at the end of the multimode optical fiber. In contrast, the splitter 602 is configured to split the spatially coherent radiation into a sufficient number of channels 607, 609, 611 required to reduce and / or eliminate the speckle effect. For example, an estimate of 600 nm radiation (e.g., light) with a bandwidth of 6 nm gives a minimum number of channels for the splitter 602 of about 750 (e.g., the number of channels or modes is equal to the size of the entrance aperture of the multimode optical fiber divided by the size of a single channel or mode (roughly the size of the point spread function) - see example mathematical details below). The photonic lantern technology (described below) combines approximately 100 optical fibers. Using an optical fiber array followed by a microlens array (as another example, this number can be easily expanded to several thousand. Thus, in some embodiments, for example, spatially coherent radiation is split by separator 602 into at least 2 to 100, 2 to 200, 2 to 500, 2 to 750, 2 to 1000, 2 to 3000, or more channels.

[0086] In some embodiments, the splitter 602 includes a binary tree splitter and / or other splitters. A binary tree splitter may include a series of channels that are successively split into two halves, thereby forming two channels from one channel. After several splits, a tree structure is formed in which one input channel 605 becomes multiple output channels 611. In some embodiments, the splitter 602 includes a multi-mode interference (MMI) device.

[0087] For example, Figure 7 The diagram shows a separator 602 formed as a binary tree 700. The binary tree 700 includes channels 607, 609, 611, 613, 615, etc. Figure 7 As shown, at each split position 621 to 681, the radiation of one channel is split into two channels, and the incident radiation at each split position is evenly divided into the two channels. The split occurs because the walls of the channel are arranged so that a single channel becomes two channels. The dividing wall is formed in the center of the channel so that the radiation is separated into two substantially equal parts. The split is repeated one or more times until the separator 602 creates multiple channels.

[0088] Back to Figure 6In some embodiments, the splitter 602 includes a non-binary beam splitter and / or other splitters. Typically, a binary beam splitter is one that splits one channel into two channels. However, in principle, non-binary splitters may also be used, such as non-binary splitters that split one channel into three and / or some other number of channels. For example, these may include directional couplers, ultra-wideband nanophotonic beam splitters using metamaterials, and / or other non-binary beam splitters.

[0089] The optical paths 604 are directly coupled (e.g., without any intervening air or lens space) to the corresponding channels 611. The optical paths 604 are configured to convert spatially coherent radiation into completely or partially spatially incoherent radiation. For example, in this example, each of the optical paths 604a, 604b, 604c, 604d, 604e, and 604f may include a waveguide and form a portion of the corresponding channel 611. The optical paths 604 have different lengths and are coupled to the channels 611. The different lengths are configured to convert 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 radiation traversing different optical paths 604, which converts spatially coherent radiation into completely or partially spatially incoherent radiation. The optical paths 604 are configured so that the radiation in a single channel 611 does not become incoherent because the radiation in the single channel 611 is single-mode radiation, but with appropriate path differences, the radiation in the single channel 611 becomes incoherent relative to the radiation in the adjacent channel 611.

[0090] In some embodiments, the difference in optical path length from the first optical path 604a to the second optical path 604b (and from the first optical path 604a to the third optical path 604c, from the second optical path 604b to the third optical path 604c, etc.) is greater than the coherence length of the spatially coherent radiation from 605. Using optical path 604, the degree of coherence between channels can be adjusted by changing the individual optical path lengths and / or other characteristics of optical path 604.

[0091] For example, Figure 8 The optical path 604 (including optical paths 604a to 604f) is shown. Figure 6 The radiation at the output of the channel 611 shown in FIG. 6 is still single mode and coherent, but if each channel is configured with a coherence length (L) greater than the radiation c ), then the radiation from the separate channels will not interfere with each other. This integrated structure is formed using optical paths 604a to 604f, which can be considered as delay lines (where radiation arriving at the end of one optical path is delayed compared to radiation in a different optical path due to path length differences - some radiation travels a longer route). Figure 8 Only one of many possible configurations is shown. Figure 8, each optical path 604a to 604f has an OPD relative to its neighbors imposed by the additional zigzag curved paths 800, 802, 804, 806. Each optical path has several tunable parameters. For example, R is the minimum radius of curvature in which radiation does not leak from the path; Δs and Δy are the minimum distances between paths required to prevent coupling; and h is a parameter that can be used to tune the OPD.

[0092] By way of non-limiting practical example, assuming a Gaussian emission spectrum, the coherence length is:

[0093] For (λ, Δλ) = (600, 6) nm Since the path difference of a zigzag shape is:

[0094] OPD=(2πR+2R+3h)-(2R+h)=2πR+2h

[0095] For λ=1550 nm, R≥10 μm, and decreases for smaller wavelengths.

[0096] (for h = 10 μm) OPD = 83 μm > L c =26.5μm

[0097] For λ = 1550nm, the optical path (waveguide) width is 400nm. Taking (Δs, Δy) = 10μm as an example value, the total width is

[0098] For N cnl =100

[0099] The height is determined by the spacing between channels. Assuming the channel outputs are edge-coupled to single-mode fibers, the height is

[0100] For N cnl =100

[0101] return Figure 6 , the combiner 608 is configured to combine fully or partially spatially incoherent radiation into a single multimode output. In some embodiments, the combiner 608 is directly coupled (e.g., without any intervening air or lens space) to the corresponding optical path 604. After crosstalk through the optical path 604, a 1D array of single-mode waveguides emitting mutually incoherent light is created. cnl The system 600 effectively increases the surface area of ​​radiation by N by splitting the incident radiation from the source on the waveguides. cnl times, while keeping the numerical aperture the same. This means that the scope increases by the same N cnl For example, by reorganizing the output from optical path 604 into a multimode fiber (MMF), it is possible to integrate the optical path 604 into an existing measurement system (e.g. Figure 3 In some embodiments, the combiner 608 includes an optical fiber array 900 (see Fig. 9 ), microlens array 1100 and / or one or more macro lenses 1102 (see Fig.11 ) and / or other components.

[0102] For example, Fig. 9 The combiner 608 is illustrated as a fiber array 900. Fig. 9 As shown, after interfering with each other, a 1D array of single mode waveguides (optical paths 604) emitting mutually incoherent light is created. These can be reassembled into a 2D profile 902 via the optical fiber array 900. Fig. 9 A schematic diagram 904 of the optical fiber array 900, a wide view 906 of the combined optical fibers 908, and an end view 910 of the 2D profile 902 are illustrated.

[0103] In some embodiments, combiner 608 ( Figure 6 ) including photon lanterns. For example, Fig.10 The combiner 608 is illustrated as a photonic lantern 1000. The photonic lantern 1000 is a multimode fiber optic device having an array of single mode fiber optic cores 1002. For example, the single mode fiber optic cores 1002 are fused 1003 to form a multimode optical fiber 1004.

[0104] In some embodiments, combiner 608 ( Figure 6 ) includes a microlens array and / or one or more macro lenses. For example, Fig.11 The combiner 608 is illustrated as a microlens array 1100 and a macrolens 1102. The output from the ID array of single mode optical paths 604 (waveguides) can be shaped 1103 using micro-optical components (e.g., microlens array 1100) and / or other optical components (e.g., lens 1102). Fig.11 As shown, placing a 1D microlens array 1100 at the same period as the output of optical path 604 shapes the output into an array of parallel spots. Macro lenses 1102 can then reassemble these spots into a multimode optical fiber 1110.

[0105] In some embodiments, the system 600 ( Figure 6 ) is configured to form a stacked integrated optical body (e.g. Figure 6601 shown), which together form a multi-dimensional array of waveguide launchers. For example, multiple planar interfering frequency systems (such as multiple systems 600 described above) can be stacked on top of each other to form a 2D array of waveguide launchers (optical path 604). If this is made with the same periodicity as the 2D microlens array, a macro lens can be used to reassemble the spot array into a multimode fiber. Using a configuration of two microlens arrays and two macro lenses, a dense array of spots can fit into the entrance aperture of a multimode fiber.

[0106] By way of non-limiting example, Fig.12 A stack of 1200 (eg, moving across the image from left to right) integrated optical bodies is shown. First, Fig.12 The diagram shows Fig.11 The microlens array 1100 and lens 1102 shown are similar and / or identical to a 2D microlens array and a single macro lens. Fig.12 It is shown how stacking multiple such microlens arrays 1100 and lenses 1102 on top of each other changes the radiation 1202 from having a small spot size and a large pitch 1204 to having a large spot size and a large pitch 1206 and then to having a small spot size and a small pitch 1208. Fig.12 It is also illustrated how, using this configuration of two microlens arrays 1100 and two macrolenses 1102, a sparse array of radiation spots 1210 can be transformed into a dense array of spots 1212, which can fit into the entrance aperture of a multimode optical fiber.

[0107] System 600( Figure 6 ) is extended to have amplitude and phase modulators for each channel to switch the light. In some embodiments, the modulation can be controlled electronically by a processor, such as Figure 3 (and discussed below Fig.14 ) shown in FIG. The processor PRO may be included in the computing system CS ( Fig.14 ) and can be operated based on computer or machine readable instructions MRI (e.g., as described below with respect to Fig.14 ). Electronic communication may occur by sending electronic signals between separate components, sending data between separate components of system 600, sending values ​​between separate components, and / or other communications. The components of system 600 may communicate via wires or wirelessly via a network, such as the Internet or the Internet in combination with various other networks, such as a local area network, a cellular network or a personal area network, an internal organizational network, and / or other networks.

[0108] In some embodiments, one or more actuators ( Figure 6) can be coupled to system 600 and configured to move one or more components of system 600 to facilitate modulation. The actuator can be coupled to one or more components of system 600 by adhesives, clips, clamps, screws, collars and / or other mechanisms. The actuator can be configured to be electronically controlled. Individual actuators can be configured to convert electrical signals into mechanical displacement and / or other modulation. Mechanical displacement and / or other modulation are configured to modulate components of system 600. As an example, one or more actuators can be piezoelectric. One or more processors PRO can be configured to control the actuators. One or more processors PRO can be configured to individually control each of the one or more actuators.

[0109] Fig.13 A method 1300 for converting spatially coherent radiation into fully or partially spatially incoherent radiation is illustrated. For example, the method 1300 may be performed to reduce speckle in illumination for metrology as part of a semiconductor manufacturing process. For example, the method 1300 may be performed with a combination of passive integrated optical components such that the volume and threat of mechanical wear is reduced relative to mechanical interference frequency converters. In some embodiments, for example, one or more operations of the method 1300 may be performed in Figure 6 The illustrated system 600, Figure 3 The system 10 shown in the figure, a computer system (such as Fig.14 In some embodiments, method 1300 includes generating spatially coherent radiation (operation 1302), splitting the spatially coherent radiation into channels (operation 1304), converting the spatially coherent radiation into fully or partially spatially incoherent radiation (operation 1306), combining the fully or partially spatially incoherent radiation into a single multimode output (operation 1308), receiving and directing the single multimode output for measurement (operation 1310), and / or other operations.

[0110] The operations of method 1300 are intended to be illustrative. In some embodiments, method 1300 may be performed with one or more additional operations not described and / or without one or more operations discussed. For example, in some embodiments, method 1300 may include additional operations related to determining adjustments to a semiconductor device manufacturing process. Additionally, the operations of method 1300 may be performed in Fig.13 The order illustrated in and described herein is not intended to be limiting.

[0111] In some embodiments, one or more portions of method 1300 may be implemented in and / or controlled by one or more processing devices (e.g., digital processors, analog processors, digital circuits designed to process information, analog circuits designed to process information, state machines, and / or other mechanisms that electronically process information). The one or more processing devices may include one or more devices that perform some or all of the operations of method 1300 in response to instructions stored electronically on an electronic storage medium. The one or more processing devices may include one or more devices that are configured through hardware, firmware, and / or software to be specifically designed to perform one or more operations of method 1300 (e.g., see the instructions described below). Fig.14 Related discussion).

[0112] In operation 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 entered and / or selected by a user and may be generated by a system (e.g., Figure 3 The system 10 shown in the figure) is determined based on previous measurements, and / or is otherwise determined. 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 can be considered to be visible light. In some embodiments, the spatially coherent radiation is generated by a single source configured to generate radiation along the first axis. In some embodiments, operation 1302 is performed by a Figure 3 Source 2 shown performs similar and / or identical radiation sources.

[0113] In operation 1304, the spatially coherent radiation is split into channels. In some embodiments, for example, the spatially coherent radiation is split into at least 2 to 100 channels. In some embodiments, operation 1304 is performed by Figure 6 The same or similar splitter as splitter 602 shown and described above is implemented. In some embodiments, the splitter comprises a binary tree beam splitter or a non-binary beam splitter. In some embodiments, the splitter comprises, for example, a multi-mode interference (MMI) device.

[0114] In operation 1306, the spatially coherent radiation is converted to fully or partially spatially incoherent radiation. In some embodiments, operation 1306 is performed by Figure 6The optical paths 604 shown and described above are performed in the same or similar manner. For example, each optical path may include a waveguide and form a portion of a corresponding channel. The optical paths have different lengths and are coupled to the channels. The different lengths are configured to convert spatially coherent radiation conducted by the optical paths into completely or partially spatially incoherent radiation. The different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, which converts spatially coherent radiation into completely or partially spatially incoherent radiation. The optical paths are configured so that the radiation in a single channel does not become incoherent because the radiation in the single channel is single-mode radiation, but with appropriate path differences, the radiation in a single channel becomes incoherent relative to the radiation in an adjacent channel. In some embodiments, the optical path length difference from the first optical path to the second optical path (and from the first optical path to the 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.

[0115] In operation 1308, the fully or partially spatially incoherent radiation is combined into a single multimode output. In some embodiments, operation 1308 is performed by Figure 6 In some embodiments, the combiner may be implemented in the same or similar manner as the combiner 608 shown and described above. 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 macro lenses.

[0116] In operation 1310, a single multimode output from the combiner is received and fully or partially spatially incoherent radiation is directed for measurement. In some embodiments, operation 1310 is performed by a multimode optical fiber configured to receive a single multimode output from the combiner and direct fully or partially spatially incoherent radiation for measurement. In some embodiments, operation 1310 is performed by various components of the system, such as Figure 3 The illustrated system 10, for example, comprises a detector 4 and a processor PRO etc. For example, the system may comprise a controller (eg, processor PRO) configured to actively control the outputs from the individual optical paths.

[0117] In some embodiments, overlay and / or alignment and / or other measurements may be determined in operation 1310. Overlay and / or alignment may be determined based on reflected diffracted radiation from a diffraction grating target and / or other information. For example, in some embodiments, operation 1310 includes illuminating (and / or otherwise irradiating) one or more targets (e.g., Figure 3 The radiation may be emitted by a radiation source (e.g., the target 30 shown). The radiation may include the above-mentioned completely and / or partially spatially incoherent radiation. Figure 3The radiation may be generated by a source 2 as shown. In some embodiments, the radiation may be directed onto multiple targets, a single target, a sub-portion of a target (e.g., something smaller than the whole), and / or otherwise directed onto a substrate. In some embodiments, the radiation may be directed onto a 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) so 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 vary. This may create a time-varying data envelope or window for analysis. The data envelope may facilitate analyzing separate sub-portions of a target, comparing one portion of a target to another portion and / or other targets (e.g., in other layers), and / or performing other analysis.

[0118] In some embodiments, operation 1310 includes generating a measurement signal based on detected reflected radiation from a diffraction grating target(s), as described above. The measurement signal is generated by a sensor such as Figure 3 The detector 4 in the embodiment of the present invention and / or other sensors) is generated based on the radiation received by the sensor. The measurement signal includes measurement information related to the target(s). For example, the measurement signal can be an overlay and / or alignment signal and / or other measurement signal including overlay and / or alignment measurement information. The measurement information (e.g., overlay value, alignment value and / or other information) can be determined using interferometry principles and / or other principles.

[0119] The measurement signal includes an electronic signal representing and / or otherwise corresponding to radiation reflected from (multiple) targets. For example, the measurement signal may indicate measurement values ​​and / or other information associated with different grating targets. Generating the measurement signal includes sensing the reflected radiation and converting the sensed reflected radiation into the electronic signal. In some embodiments, generating the measurement signal includes sensing different portions of the reflected radiation from different areas of the target and / or different geometries and / or multiple targets, and combining the different portions of the reflected radiation to form the measurement signal. This may include generating and / or analyzing one or more images of the target using the radiation described herein. Such sensing and conversion may be performed by a computer program product associated with the computer program product. Figure 3 The detector 4 and / or the processor PRO shown may be implemented with similar and / or identical components and / or other components.

[0120] In some embodiments, method 1300 includes determining adjustments to a semiconductor device manufacturing process. In some embodiments, method 1300 includes determining one or more semiconductor device manufacturing process parameters. One or more semiconductor device manufacturing process parameters may be determined based on one or more detected phase and / or amplitude changes, overlay and / or alignment values ​​indicated by a measurement signal, and / or other similar systems and / or other information. One or more parameters may include parameters of radiation (radiation for measurement), overlay values, alignment values, measurement inspection positions on semiconductor device structure layers, radiation beam trajectories on targets, and / or other parameters. In some embodiments, process parameters may be broadly interpreted as including platform position, mask design, measurement target design, semiconductor device design, radiation intensity (for exposure resist, etc.), radiation incident angle (for exposure resist, etc.), radiation wavelength (for exposure resist, etc.), pupil size and / or shape, resist material, and / or other parameters.

[0121] In some embodiments, method 1300 includes determining a process adjustment based on one or more determined semiconductor device manufacturing process parameters, and adjusting semiconductor device manufacturing equipment and / or other operations based on the determined adjustment. For example, if the determined metrology measurement value is not within the process tolerance, the out-of-tolerance measurement may be caused by one or more manufacturing processes whose process parameters have drifted and / or otherwise changed such that the process no longer produces acceptable devices (e.g., the measurement results may violate a threshold of acceptability). One or more new or adjusted process parameters can be determined based on the measurement determination. The new or adjusted process parameters can be configured to cause the manufacturing process to once again produce acceptable devices.

[0122] For example, a new or adjusted process parameter may cause a previously unacceptable measurement to be adjusted back into an acceptable range. The new or adjusted process parameter may be compared to the existing parameters for a given process. For example, if there is a difference, the difference may be used to determine an adjustment for a device used to produce the equipment (e.g., parameter "x" should be increased / decreased / changed so that it matches a new or adjusted version of parameter "x" determined as part of method 1300). In some embodiments, method 1001 may include electronically adjusting the device (e.g., based on the determined process parameter). Electronically adjusting the device may include sending an electronic signal and / or other communication to the device, which may, for example, result in a change to the device. Electronic adjustments may include, for example, changing settings on the device and / or other adjustments.

[0123] Fig.141 is a diagram of an example 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 transferring information and a processor PRO (or multiple processors, coupled to the bus BS) for processing information. Figure 3 The computer system CS also includes a main memory MM, such as a random access memory (RAM) or other dynamic storage device, which is coupled to the bus BS for storing information and instructions to be executed by the processor PRO. The main memory MM can also be used to store temporary variables or other intermediate information during the execution of instructions by the processor PRO. The computer system CS also includes a read-only memory (ROM) ROM or other static storage device coupled 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 coupled to the bus BS for storing information and instructions.

[0124] The computer system CS can be coupled to a display DS via a bus BS, 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 coupled to the bus BS for transmitting information and command selections to the processor PRO. Another type of user input device is a cursor control CC, such as a mouse, trackball or cursor direction keys, for transmitting direction information and command selections to the processor PRO and controlling cursor movement on the display DS. The input device typically has two degrees of freedom on two axes (a first axis (e.g., x) and a second axis (e.g., y)), which allows the device to specify a position in a plane. A touch panel (screen) display can also be used as an input device.

[0125] In some embodiments, in response to the processor PRO executing one or more sequences of one or more instructions contained in the main memory MM, all or some operations of one or more operations described herein can be performed by the computer system CS. Such instructions can be read from another computer-readable medium (such as a storage device SD) into the main memory MM. Executing the instructions contained in the main memory MM causes the processor PRO to perform the process steps (operations) described herein. One or more processors in a multi-processing arrangement can also be adopted to execute the instruction sequence contained in the main memory MM. In some embodiments, a hard-wired circuit device can be used instead of a software instruction or used in combination with a software instruction. Therefore, the description herein is not limited to any specific combination of hardware circuit devices and software.

[0126] The term "computer-readable medium" or "machine-readable medium" used herein refers to any medium that participates in providing instructions to the processor PRO for execution. This medium can take many forms, including but not limited to non-volatile media, volatile media and transmission media. Non-volatile media include, for example, optical disks or disks, such as storage devices SD. Volatile media include dynamic memory, such as main memory MM. Transmission media include coaxial cables, copper wires and optical fibers, including wires that constitute bus BS. Transmission media can also take the form of sound waves or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Computer-readable media can be non-transient, such as floppy disks, foldable disks, hard disks, tapes, any other magnetic media, CD-ROMs, DVDs, any other optical media, punch cards, paper tapes, any other physical media with hole patterns, RAM, PROMs and EPROMs, flash EPROMs, any other memory chips or memory cartridges. Non-transient computer-readable media can have instructions recorded thereon. When executed by a computer, instructions can implement any operation described herein. For example, transient computer-readable media can include carrier waves or other propagating electromagnetic signals.

[0127] Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to the processor PRO for execution. For example, the instructions may initially be carried on a disk of a remote computer. The remote computer may load the instructions into its dynamic memory and send the instructions over a telephone line using a modem. The modem local to the computer system CS may receive data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector coupled to the bus BS may receive the data carried in the infrared signal and place the data on the bus BS. The bus BS carries the data to the main memory MM, from which the processor PRO retrieves and executes the instructions. Before or after execution by the processor PRO, the instructions received by the main memory MM may optionally be stored on a storage device SD.

[0128] The computer system CS may also include a communication interface CI coupled to the bus BS. The communication interface CI provides a bidirectional data communication coupling with a network link NDL connected to the local network LAN. For example, the communication interface CI may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection with a corresponding type of telephone line. As another example, the communication interface CI may be a local area network (LAN) card to provide a data communication connection with a compatible LAN. A wireless link may also be implemented. In any such implementation, the communication interface CI sends and receives electrical, electromagnetic or optical signals that carry digital data streams representing various types of information.

[0129] The network link NDL typically provides data communication to other data devices through one or more networks. For example, the network link NDL can provide a connection to the host computer HC through a local network LAN. This can include data communication services provided through the global packet data communication network (now generally referred to as the "Internet" INT). The local network LAN (Internet) can use electrical signals, electromagnetic signals or optical signals that carry digital data streams. The signals through the various networks and the signals on the network data link NDL and through the communication interface CI - which carry digital data to and from the computer system CS are exemplary forms of carrier waves that transport information.

[0130] The computer system CS can send messages and receive data, including program code, through (multiple) networks, network data links NDL and communication interfaces CI. In the Internet example, the host computer HC can send the request code of the application program through the Internet INT, the network data link NDL, the local network LAN and the communication interface CI. For example, one such downloaded application can provide all or part of the method described herein. The received code can be executed by the processor PRO when it is received, and / or stored in the storage device SD or other non-volatile storage device for later execution. In this way, the computer system CS can obtain the application code in the form of a carrier wave.

[0131] Various embodiments of the present system and method are disclosed in the subsequent numbered clause list. In the following, further features, characteristics and exemplary technical solutions of the present disclosure will be described according to the clauses that can be optionally claimed in any combination:

[0132] 1. A system configured to convert spatially coherent radiation into fully or partially spatially incoherent radiation, the system comprising: a splitter configured to receive spatially coherent radiation and split the spatially coherent radiation into channels; an optical path having different lengths coupled to the channels, the different lengths being configured to convert the spatially coherent radiation into the fully or partially spatially incoherent radiation; and a combiner coupled to the optical path and configured to combine the fully or partially spatially incoherent radiation from the optical path into a single multimode output.

[0133] 2. A system according to clause 1, wherein the optical path is configured so that radiation in a single channel does not become incoherent because the radiation in the single channel is single mode radiation, but with appropriate path differences, the radiation in the single channel becomes incoherent relative to radiation in adjacent channels.

[0134] 3. A system according to any of the preceding clauses, wherein the splitter, the optical path and the combiner are integrated into an integrated optical body.

[0135] 4. A system according to any of the preceding clauses, wherein the integrated optical body comprises a microchip fabricated using complementary metal oxide semiconductor (CMOS) and / or indium phosphide fabrication technology.

[0136] 5. A system according to any of the preceding clauses, wherein the waveguide layer of the integrated optical body is formed from silicon, silicon on oxide, indium phosphide, silicon nitride and / or aluminum oxide.

[0137] 6. A system according to any of the preceding clauses, wherein the system comprises stacked integrated optical bodies forming a multi-dimensional array of waveguide emitters.

[0138] 7. A system according to any of the preceding clauses, wherein the system is passive, having no moving parts or electronically controlled components.

[0139] 8. A system according to any of the preceding clauses, wherein the separator is configured to split the spatially coherent radiation into at least 2 to 100 channels.

[0140] 9. The system of any of the preceding clauses, wherein the splitter is a binary tree beam splitter or a non-binary beam splitter.

[0141] 10. The system of any of the preceding clauses, wherein the separator is a multi-mode interference (MMI) device.

[0142] 11. A system according to any of the preceding clauses, wherein each optical path comprises a waveguide and forms part of a corresponding channel.

[0143] 12. A system according to any of the preceding clauses, wherein the different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, which converts spatially coherent radiation into fully or partially spatially incoherent radiation.

[0144] 13. A system according to any of the preceding clauses, wherein the difference in optical path length from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation.

[0145] 14. A system according to any of the preceding clauses, wherein the combiner comprises an optical fiber array.

[0146] 15. A system according to any of the preceding clauses, wherein the combiner comprises a photonic lantern.

[0147] 16. A system according to any of the preceding clauses, wherein the combiner comprises a microlens array and / or one or more macro lenses.

[0148] 17. A system according to any of the preceding clauses, wherein the spatially coherent radiation comprises visible light.

[0149] 18. The system of any of the preceding clauses, wherein the system further comprises a multimode optical fiber configured to receive the single multimode output from the combiner.

[0150] 19. A system according to any of the preceding clauses, wherein the system further comprises a controller configured as a controller to actively control the output from the individual optical paths.

[0151] 20. A system according to any of the preceding clauses, wherein spatially coherent radiation is converted into said fully or partially spatially incoherent radiation for use in metrology associated with a semiconductor manufacturing process.

[0152] 21. A method for converting spatially coherent radiation into completely or partially spatially incoherent radiation, the method comprising: using a separator to receive the spatially coherent radiation and split the spatially coherent radiation into channels; using optical paths with different lengths coupled to the channels to convert the spatially coherent radiation into the completely or partially spatially incoherent radiation; and using a combiner coupled to the optical paths to combine the completely or partially spatially incoherent radiation from the optical paths into a single multimode output.

[0153] 22. A method according to any of the preceding clauses, wherein the optical path is configured so that radiation in a single channel does not become incoherent because the radiation in the single channel is single mode radiation, but by utilizing appropriate path differences, the radiation in the single channel becomes incoherent relative to radiation in adjacent channels.

[0154] 23. The method according to any of the preceding clauses, wherein the splitter, the optical path and the combiner are integrated into an integrated optical body.

[0155] 24. The method according to any of the preceding clauses, wherein the integrated optical body comprises a microchip fabricated using complementary metal oxide semiconductor (CMOS) and / or indium phosphide fabrication technology.

[0156] 25. A method according to any of the preceding clauses, wherein the waveguide layer of the integrated optical body is formed from silicon, silicon on oxide, indium phosphide, silicon nitride and / or aluminium oxide.

[0157] 26. The method of any of the preceding clauses, further comprising forming a stacked integrated optical body that forms a multi-dimensional array of waveguide emitters.

[0158] 27. A method according to any of the preceding clauses, wherein the splitter, the optical path and the combiner have no moving parts or electronically controlled components.

[0159] 28. The method of any preceding clause, further comprising: using the separator to split the spatially coherent radiation into at least 2 to 100 channels.

[0160] 29. A method according to any of the preceding clauses, wherein the splitter is a binary tree beam splitter or a non-binary beam splitter.

[0161] 30. A method according to any of the preceding clauses, wherein the separator is a multi-mode interference (MMI) device.

[0162] 31. A method according to any of the preceding clauses, wherein each optical path comprises a waveguide and forms part of a corresponding channel.

[0163] 32. A method according to any of the preceding clauses, wherein the different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, which converts the spatially coherent radiation into the fully or partially spatially incoherent radiation.

[0164] 33. A method according to any of the preceding clauses, wherein the difference in optical path length from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation.

[0165] 34. A method according to any of the preceding clauses, wherein the combiner comprises an optical fiber array.

[0166] 35. A method according to any of the preceding clauses, wherein the combiner comprises a photon lantern.

[0167] 36. A method according to any of the preceding clauses, wherein the combiner comprises a microlens array and / or one or more macro lenses.

[0168] 37. A method according to any of the preceding clauses, wherein the spatially coherent radiation comprises visible light.

[0169] 38. The method of any preceding clause, further comprising receiving the single multimode output from the combiner using a multimode optical fiber.

[0170] 39. A method according to any of the preceding clauses, further comprising: actively controlling output from separate optical paths using a controller.

[0171] 40. A method according to any of the preceding clauses, wherein the spatially coherent radiation is converted into the fully or partially spatially incoherent radiation for use in metrology associated with a semiconductor manufacturing process.

[0172] 41. A system configured to convert spatially coherent radiation into fully or partially spatially incoherent radiation to reduce speckle in illumination for measurement as part of a semiconductor manufacturing process, the system being configured with a combination of passive integrated optical elements such that the volume and threat of mechanical wear is reduced relative to a mechanical interference frequency converter, the system comprising: a source configured to generate the spatially coherent radiation; a passive integrated optical body, the body comprising: a splitter configured to receive the spatially coherent radiation and split the spatially coherent radiation into channels, wherein the splitter comprises a binary tree beam splitter and / or a multi-mode interference (MMI) device; an optical path having different lengths coupled to the channels, the different lengths being configured to separate the spatially coherent radiation conducted by the optical path; The invention relates to a method for converting the spatially coherent radiation into the fully or partially spatially incoherent radiation, wherein the different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, wherein the different optical paths convert the spatially coherent radiation into the fully or partially spatially incoherent radiation, wherein the optical paths are configured such that the radiation in a single channel does not become incoherent because the radiation in the single channel is single-mode radiation, but the radiation in the single channel becomes incoherent relative to the radiation in adjacent channels by utilizing appropriate path differences; and a combiner configured to combine the fully or partially spatially incoherent radiation from the optical paths into a single multimode output; and a multimode optical fiber configured to receive the single multimode output from the combiner and guide the fully or partially spatially incoherent radiation for measurement.

[0173] 42. A system according to any of the preceding clauses, wherein the passive integrated optical body comprises a silicon, silicon-on-oxide, indium phosphide, silicon nitride and / or aluminum oxide microchip.

[0174] 43. A system according to any of the preceding clauses, wherein the system comprises stacked integrated optical bodies forming a multi-dimensional array of waveguide emitters.

[0175] 44. A system according to any of the preceding clauses, wherein the difference in optical path length from the first optical path to the second optical path is greater than the coherence length of the spatially coherent radiation.

[0176] 45. A system according to any of the preceding clauses, wherein the combiner comprises an optical fiber array, a photonic lantern, a microlens array and / or one or more macro lenses.

[0177] The concepts disclosed herein can be associated with any general imaging system for imaging sub-wavelength features, and may be particularly useful for emerging imaging technologies that are capable of producing shorter and shorter wavelengths. Emerging technologies already in use include EUV (extreme ultraviolet), DUV lithography, which is capable of producing wavelengths of 193nm using ArF lasers, and even 157nm using fluorine lasers. In addition, EUV lithography is capable of producing wavelengths in the range of 20nm to 5nm by using synchrotrons or by colliding materials (solid or plasma) with high-energy electrons to produce photons in this range.

[0178] Although the concepts disclosed herein can be used for imaging on substrates such as silicon wafers, it should be understood that the disclosed concepts can be used with any type of lithography imaging system, such as those used for imaging on substrates other than silicon wafers. In addition, combinations and sub-combinations of the disclosed elements can include separate embodiments.

[0179] The above description is intended to be illustrative rather than limiting. It will therefore be apparent to those skilled in the art that modifications may 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 into fully or partially spatially incoherent radiation, the system comprising: a splitter configured to receive the spatially coherent radiation and split the spatially coherent radiation into channels; an optical path having different lengths coupled to the channel, the different lengths configured to convert the spatially coherent radiation into the fully or partially spatially incoherent radiation; as well as A combiner is coupled to the optical path and is configured to combine the fully or partially spatially incoherent radiation from the optical path into a single multimode output.

2. The system of claim 1 , wherein the optical path is configured such that radiation in a single channel does not become incoherent because the radiation in the single channel is single mode radiation, but with appropriate path differences, the radiation in the single channel becomes incoherent relative to radiation in adjacent channels.

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

4. The system of claim 3, wherein the integrated optical body comprises a microchip fabricated using complementary metal oxide semiconductor (CMOS) and / or indium phosphide fabrication technology.

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

6. The system of any one of claims 1 to 5, wherein the system comprises stacked integrated optical bodies forming a multi-dimensional array of waveguide launchers.

7. A system according to any one of claims 1 to 6, wherein the system is passive, having no moving parts or electronically controlled components.

8. The system of any one of claims 1 to 7, wherein the separator 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 of any one of claims 1 to 9, wherein the separator is a multi-mode interference (MMI) device.

11. A 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 of any one of claims 1 to 11, wherein the different lengths are configured to reduce or eliminate interference between radiation traversing different optical paths, which converts the spatially coherent radiation into the fully or partially spatially incoherent radiation.

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

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

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

16. The system of any one of claims 1 to 13, wherein the combiner comprises a microlens array and / or one or more macrolenses.

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

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

19. The system of any one of claims 1 to 18, wherein the system further comprises a controller configured to actively control output from the individual optical paths.

20. The system of any one of claims 1 to 19, wherein the spatially coherent radiation is converted into the fully or partially spatially incoherent radiation for use in metrology associated with a semiconductor manufacturing process.

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