Replacement of metrology components with optical component arrays

Abstract

The replacement of a metronome system used for substrate imaging with an array of optical components is described. A typical optical wedge for imaging and / or other metronome operations is replaced with an array of optical components that is less expensive and optically relatively simple. In some embodiments, two of the optical components in the array are configured to create two zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor, thereby facilitating the determination of the focal position without requiring a separate focal branch in the metronome system. In some embodiments, two of the optical components in the array include a microlens array, where each microlens in the microlens array is configured to form a focal spot on the radiation sensor, the position of which can be used to determine radiation wavefront aberration, eliminating the need for a conventional wavefront aberration sensor.

Description

Technical Field

[0001] Cross-reference of related applications

[0001] This application claims priority to U.S. Application No. 63 / 452,422, filed Mar. 15, 2023, which is hereby incorporated by reference in its entirety.

[0002]

[0002] This description relates to the replacement of optical components arrays for metrology.

Background Art

[0003]

[0003] A lithographic projection apparatus can be used, for example, in the manufacture of integrated circuits (ICs). A patterning device (e.g., a mask) can contain or provide a pattern (“design layout”) corresponding to an individual layer of an IC, and this pattern can be transferred to a target portion (e.g., including one or more dies) on a substrate (e.g., a silicon wafer) coated with a radiation-sensitive material (“resist”), for example, by irradiating the target portion through the pattern on the patterning device. Generally, one substrate contains a plurality of adjacent target portions to which patterns are successively transferred by the lithographic projection apparatus, and one target portion is pattern-transferred at a time. In one type of lithographic projection apparatus, the pattern of the entire patterning device is transferred to one target portion in one operation. Such a device is generally called a stepper. In an alternative device, generally called a step-and-scan type device, the projection beam scans the patterning device in an arbitrary reference direction (“scan” direction), while at the same time moving the substrate parallel or antiparallel to this reference direction. For one target portion, different portions of the pattern on the patterning device are transferred step by step.

[0004]

[0004] Before transferring the pattern from the patterning device to the substrate, various procedures such as priming, resist coating, and soft baking may be performed on the substrate. After exposure, other procedures ("post-exposure procedures") such as post-exposure baking (PEB), development, hard baking, and measurement / inspection of the transferred pattern may be performed on the substrate. This series of procedures is used as the basis for creating the individual layers of a device, such as an IC. Subsequently, the substrate may undergo various processes such as etching, ion implantation (doping), metallization, oxidation, deposition, and chemical mechanical polishing, all of which are used to finish the individual layers of the device. If the device requires multiple layers, the entire procedure or a variation thereof is repeated for each layer. Finally, the device will be present in each target area on the substrate. These devices are then separated from each other by techniques such as dicing and sawing, so that the individual devices can be mounted on a carrier or connected to pins. This device manufacturing process can also be considered a patterning process.

[0005]

[0005] Lithography is a central process in the manufacturing of devices such as ICs, and the patterns formed on the substrate define the functional elements of the device, such as microprocessors and memory chips. Similar lithography techniques are also used to form flat panel displays, microelectromechanical systems (MEMS), and other devices.

[0006]

[0006] With the continuous advancement of semiconductor manufacturing processes, the dimensions of functional elements continue to shrink, while the number of functional elements such as transistors per device has steadily increased over the decades, following a trend generally known as "Moore's Law." At the current level of technology, each layer of a device is manufactured using a lithography projection system that projects the design layout onto a substrate using illumination from a deep ultraviolet light source, creating individual functional elements with dimensions well below 100 nm, i.e., dimensions less than half the wavelength of radiation from the light source (e.g., a 193 nm light source).

[0007]

[0007] This process, in which features having dimensions smaller than the traditional resolution limits of a lithography projector are printed, is generally known as low-k1 lithography, according to the resolution formula: CD = k1 × λ / NA. Here, λ is the wavelength of the radiation used (currently, in most cases, 248 nm or 193 nm), NA is the numerical aperture of the projection optics of the lithography projector, CD is the "critical dimension" (usually the smallest feature size to be printed), and k1 is the empirical resolution coefficient. Generally, the smaller k1, the more difficult it becomes to reproduce a pattern on the substrate that resembles the shape and dimensions planned by the designer to achieve a particular electrical function and performance. To overcome these difficulties, a fine-tuning process is applied to the lithography projector, design layout, or patterning device. These include, but are not limited to, optimizing NA and optical coherence settings, customized lighting schemes, using phase-shift patterning devices, optical proximity effect correction (OPC, sometimes called "optical and process correction") in the design layout, or other methods typically defined as "resolution enhancement techniques" (RET). [Overview of the Initiative]

[0008]

[0008] A replacement of the metrology system used for imaging the substrate with an array of optical components is described to simplify it. A typical optical wedge for imaging and / or other metrology operations is replaced with an array of optical components that is inexpensive and optically relatively simple. In some embodiments, two of the optical components in the array are configured to create two zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor, thereby facilitating the determination of the focal position without providing a separate focal branch in the metrology system. In some embodiments, two of the optical components in the array include a microlens array, and each microlens in the microlens array is configured to form a focal spot on the radiation sensor, the position of which can be used to determine radiation wavefront aberration, eliminating the need for a conventional wavefront aberration sensor.

[0009]

[0009] According to one embodiment, a metrology system. The metrology system includes a radiation sensor, which is configured to generate a metrology signal based on radiation received at different imaging positions on the radiation sensor. The metrology system also includes an array of optical components, which are configured to receive radiation of different diffraction orders from a substrate, change the angles of the different diffraction orders of this radiation, and guide the different diffraction orders of this radiation to different imaging positions on the radiation sensor.

[0010]

[0010] In some embodiments, the array of optical components includes four optical components, two of which are related to zero-order diffraction radiation and two of which are related to first-order diffraction radiation.

[0011]

[0011] In some embodiments, the array of optical components includes a lens array. In some embodiments, the cross-sectional shape of each lens is circular or square.

[0012]

[0012] In some embodiments, the array of optical components includes a spatial light modulator (SLM). In some embodiments, the SLM is transmissive or reflective, or has transmissive or reflective portions. In some embodiments, the SLM includes liquid crystal, digital micromirror devices (DMDs), and / or patterns configured to change the angles of different diffraction orders of radiation and guide different diffraction orders of radiation to different imaging positions on the radiation sensor.

[0013]

[0013] In some embodiments, the array of optical components includes a metalens array.

[0014]

[0014] In some embodiments, the system includes one or more processors operably connected to a radiation sensor and configured to determine metronome measurements based on metronome signals. In some embodiments, metronome measurements include alignment values, overlay values, focus values, and / or critical dimension values ​​related to semiconductor manufacturing processes performed on a substrate.

[0015]

[0015] In some embodiments, two optical components in an array of optical components are configured to create two zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor. In some embodiments, one or more processors are operably connected to the radiation sensor and are configured to determine a focal position for imaging the substrate in this metrology system based on the zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor. In some embodiments, one or more processors are further configured to automatically adjust the position of the stage in the metrology system that holds the substrate based on the focal position so that the subsequent image of the substrate is in focus.

[0016]

[0016] In some embodiments, two optical components in an array of optical components include a microlens array, where each microlens in the microlens array is configured to form a focal spot on a radiation sensor, the position of which can be used to determine radiation wavefront aberration. In some embodiments, one or more processors are operably connected to the radiation sensor and are configured to detect radiation wavefront aberration based on the position of the focal spot relative to a reference position.

[0017]

[0017] In some embodiments, the radiation sensor includes a sub-part configured to detect a focal spot, and the system further includes segmented mirrors configured to guide radiation from the microlens array to the sub-part of the radiation sensor. In some embodiments, the microlens array is positioned in different planes of the metrology system compared to other optical components in the array of optical components, such that the radiation sensor is located at the focal plane of the microlens array and the focal plane of other optical components in the array of optical components.

[0018]

[0018] In some embodiments, the system includes a radiation source and one or more lenses. The radiation source and one or more lenses are configured to generate radiation and guide the radiation to a substrate.

[0019]

[0019] In some embodiments, the substrate includes a semiconductor wafer having one or more overlay targets configured to reflect radiation toward an array of optical components, and the sensor includes a microdiffraction-based overlay camera associated with overlay measurement.

[0020]

[0020] In some embodiments, the radiation sensor includes a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS) and / or a photodiode array.

[0021] According to another embodiment, a metrology method including one or more of the above operations is provided.

Brief Description of the Drawings

[0022]

[0022] The above aspects, as well as other aspects and features, will become apparent to those skilled in the art by referring to the following description of specific embodiments in conjunction with the accompanying drawings. [Figure 1]

[0023] According to one embodiment, a lithography apparatus is schematically shown. [Figure 2]

[0024] According to one embodiment, an embodiment of a lithography cell or a lithography cluster is schematically shown. [Figure 3]

[0025] According to one embodiment, an exemplary inspection system is schematically shown. [Figure 4]

[0026] According to one embodiment, an exemplary metrology technique is schematically shown. [Figure 5]

[0027] According to one embodiment, the relationship between the radiation illumination spot of an inspection system and a metrology target is shown. [Figure 6]

[0028] According to one embodiment, a metrology system is shown. [Figure 7]

[0029] According to one embodiment, an optical element including an optical wedge, a lens, a sensor, an illumination pupil, a detection pupil, and an exemplary field image is shown. [Figure 8]

[0030] According to one embodiment, the replacement of the system shown in FIG. 6 with an optical component array (from the wedge and one or more lenses shown in FIG. 7) to simplify the system is shown. [Figure 9]

[0031] According to one embodiment, two optical components in the array of optical components in Figure 8 (components in quadrants Q1 and Q3 in this example) are shown, configured to create two zero-order images defocused in opposite directions at two different imaging positions on a radiation sensor for focus determination. [Figure 10]

[0032] The present invention illustrates a microlens of a microlens array configured to form a focal spot on a radiation sensor, the position of which can be used to determine radiation wavefront aberration. [Figure 11]

[0033] The following also shows microlenses of a microlens array configured to form a focal spot on a radiation sensor according to one embodiment, and the position of the focal spot can be used for determining radiation wavefront aberration, but the microlenses of the microlens array are shown in relation to an array of optical components similar to those described in Figures 8 and 9. [Figure 12]

[0034] According to one embodiment, Figure 11 shows how the focal plane of one or more microlens arrays may differ from the focal plane of radiation spots from other optical components in the array of optical components (components in quadrants Q2 and Q3 in this example). [Figure 13]

[0032] According to one embodiment, an embodiment of a metrology system is shown in which a sub-part of a radiation sensor is configured to detect a focal spot, the optical elements of which include a segmented mirror (and / or similar functional component) configured to guide radiation from a microlens array to the sub-part of the radiation sensor. [Figure 14]

[0036] A metrology method is shown according to one embodiment. [Figure 15]

[0037] This is a block diagram of an exemplary computer system according to one embodiment. [Modes for carrying out the invention]

[0023]

[0038] In semiconductor device manufacturing, metronome operations typically involve measuring one (or more) metronome marks and / or other targets within a layer of the semiconductor device structure. Measurements are usually performed by irradiating the metronome marks with radiation and comparing the properties of radiation of different diffraction orders reflected from those marks. Using such techniques, overlay, alignment, and / or other parameters are measured.

[0024]

[0039] Many metronome systems include optical wedges configured to guide radiation of different diffraction orders to predetermined locations on a radiation sensor, a separate focal branch (e.g., part of the metronome system including a radiation source, several lenses, and many other optical components) that determines the focal point for imaging the substrate, wavefront aberration sensors, and / or other components. These systems are bulky, complex, and expensive. For example, the cost of the optical wedge and the physical system space required to incorporate it are high compared to other optical components. Such systems require additional components, such as an additional beam splitter to couple the focal branch with the rest of the metronome system, which reduces the throughput of radiation to the central sensor. Focal position determination in such systems is not continuous, as the radiation used to determine the focal position travels along at least a portion of the same optical path as the radiation ultimately used for metronome measurements. This means the metronome system switches between a focus position determination mode in which the radiation source and optics within the focus branch are "on" and a metronome image acquisition mode in which the radiation source and optics within the focus branch are "off". The focus gap between these modes can cause overlay errors and / or other problems due to defocusing. Furthermore, diffracted light of different orders from metronome targets on the substrate has different focal positions based on objective system wavefront errors, but this is not taken into account in current metronome systems.

[0025]

[0040] A replacement with an array of optical components is described to simplify the metrologic system used for metrologic operations, including substrate imaging. It is advantageous to replace a typical optical wedge for imaging and / or other metrologic operations with an array of inexpensive and optically relatively simple optical components. In some embodiments, two optical components in the array are configured to create two zero-order images defocused in opposite directions at two different imaging positions on a radiation sensor, thereby facilitating the determination of the focal position without requiring a separate focal branch in the metrologic system. In some embodiments, the two optical components in the array include a microlens array, where each microlens in the microlens array is configured to form a focal spot on the radiation sensor, the position of which can be used to determine radiation wavefront aberration, eliminating the need for a conventional wavefront aberration sensor.

[0026]

[0041] As a brief introduction, the semiconductor device manufacturing and patterning processes are described below. The following paragraphs also describe some components of systems and / or methods for semiconductor device metrology. These systems and methods can be used, for example, to measure overlay, alignment, etc., in the semiconductor device manufacturing process, or for other operations.

[0027]

[0042] While this specification may contain specific references to the measurement of overlays, alignments, or other parameters, and to the manufacture of integrated circuits (ICs) for semiconductor devices, it should be understood that the descriptions herein are applicable to many other uses. For example, they can be used in the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memory, liquid crystal display panels, thin-film magnetic heads, and the like. As will be obvious to those skilled in the art, in the context of such alternative applications, the terms “reticle,” “wafer,” or “die” used herein should all be considered interchangeable with the more general terms “mask,” “substrate,” and “target portion,” respectively.

[0028]

[0043] As used herein, the term “projection optics” should be interpreted broadly to encompass various types of optical systems, including, for example, refractive optics, reflective optics, apertures, and reflective-refractory optics. The term “projection optics” may also include components that operate to guide, shape, or control the radiation projection beam collectively or individually, according to any of these design types. The term “projection optics” may include any optical component within a lithography projection apparatus, regardless of where it is located in the optical path of the lithography projection apparatus. Projection optics may include optical components for shaping, adjusting, and / or projecting radiation from a radiation source before it passes through a patterning device, and / or optical components for shaping, adjusting, and / or projecting such radiation after it has passed through a patterning device. Generally, radiation sources and patterning devices are excluded from projection optics.

[0029]

[0044] Figure 1 schematically shows one embodiment of a lithography apparatus LA. This apparatus includes an illumination system (illuminator) IL configured to adjust 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 patterning device (e.g., mask) MA, and coupled to a first positioner PM configured to precisely position the patterning device according to specific parameters; a substrate table (e.g., wafer table) WT (e.g., WTa, WTb, or both) configured to hold a substrate (e.g., resist-coated wafer) W, and coupled to a second positioner PW configured to precisely position the substrate according to specific parameters; and a projection system (e.g., refractive projection lens system) PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., including one or more dies, often called a field). The projection system is supported on a reference frame RF. As described, this lithography apparatus is a transmissive type (for example, one employing a transmissive mask). Alternatively, it may be a reflective type (for example, one employing a programmable mirror array or one employing a reflective mask).

[0030]

[0045] The illuminator IL receives the radiated beam from the radiation source SO. For example, if the radiation source is an excimer laser, the radiation source and the lithography apparatus may be separate components. In such cases, the radiation source is not considered to form part of the lithography apparatus, and the radiated beam from the radiation source SO is delivered to the illuminator IL using a beam delivery system BD, which includes, for example, appropriate guide mirrors and / or beam expanders. In other cases, for example, if the radiation source is a mercury lamp, the radiation source may be an integral part of the lithography apparatus. The radiation source SO and the illuminator IL, together with the beam delivery system BD if necessary, may be called a radiation system.

[0031]

[0046] The illuminator IL can alter the beam intensity distribution. The illuminator may be positioned to restrict the radial range of the emitted beam so that the intensity distribution within the annular region of the pupil plane of the illuminator IL is non-zero. Additionally or alternatively, the illuminator IL may be operable to restrict the beam distribution within the pupil plane so that the intensity distribution in multiple equally spaced sections within the pupil plane is non-zero. The intensity distribution of the emitted beam within the pupil plane of the illuminator IL is sometimes called the illumination mode.

[0032]

[0047] An illuminator IL may include an adjuster AD configured to adjust the (angle / spatial) intensity distribution of the beam. Generally, at least the outer and / or inner radial ranges (usually called σ-outer and σ-inner, respectively) of the intensity distribution within the pupil plane of the illuminator can be adjusted. The illuminator IL may also be operable to change the angular distribution of the beam. For example, the illuminator may be operable to change the number of segments within the pupil plane where the intensity distribution is non-zero, and the angular range thereof. By adjusting the intensity distribution of the beam within the pupil plane of the illuminator, various illumination modes can be achieved. For example, by limiting the radial and angular ranges of the intensity distribution within the pupil plane of the illuminator IL, the intensity distribution can be made to have a multipolar distribution, such as a bipolar, quadrupole, or hexapole distribution. The desired illumination mode can be obtained, for example, by inserting an optical system that provides such illumination mode into the illuminator IL, or by using a spatial light modulator.

[0033]

[0048] The illuminator IL may be operable to change the polarization of the beam, or it may be operable to adjust the polarization using an adjuster AD. The polarization state of the radiated beam across the entire pupil plane of the illuminator IL is sometimes called the polarization mode. By using various polarization modes, it is possible to obtain higher contrast in the image formed on the substrate W. The radiated beam may be unpolarized. Alternatively, the illuminator may be arranged to linearly polarize the radiated beam. The polarization direction of the radiated beam may vary across the pupil plane of the illuminator. The polarization direction of the radiation may differ depending on the different regions within the pupil plane of the illuminator IL. The polarization state of the radiation may be selected depending on the illumination mode. In the case of a multi-pole illumination mode, the polarization of each pole of the radiated beam may be approximately perpendicular to the position vector of that pole in the pupil plane of the illuminator IL. For example, in the case of a bi-pole illumination mode, the radiation may be linearly polarized in a direction substantially perpendicular to the line that bisects the two opposing sections of the two poles. The radiated beam may be polarized in one of two different orthogonal directions, sometimes referred to as the X-polarization state and the Y-polarization state. In the quadrupole illumination mode, the radiation in each pole interval may be linearly polarized in a direction substantially perpendicular to the line bisecting the interval. This polarization mode is sometimes referred to as XY polarization. Similarly, in the hexapole illumination mode, the radiation in each pole interval may be linearly polarized in a direction substantially perpendicular to the line bisecting the interval. This polarization mode is sometimes referred to as TE polarization.

[0034]

[0049] Furthermore, illuminators IL typically include various other components such as integrators IN and capacitors CO. Illumination systems may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, to guide, shape, and / or control radiation. Thus, the illuminator provides a tuned radiation beam B with desired uniformity and intensity distribution in its cross-section.

[0035]

[0050] The support structure MT supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithography apparatus, and other conditions such as whether the patterning device is held in a vacuum environment. The support structure can hold the patterning device using mechanical, vacuum, electrostatic, or other clamping techniques. The support structure may be, for example, a frame or table that can be fixed or movable as needed. The support structure can reliably position the patterning device, for example, relative to the projection system. All terms used herein, “reticle” or “mask,” should be considered synonymous with the more general term “patterning device.”

[0036]

[0051] As used herein, the term “patterning device” should be broadly interpreted to refer to any device that can be used to impart a pattern to a target portion of a substrate. In one embodiment, a patterning device is any device that can be used to create a pattern to a target portion of a substrate by imparting a pattern to the cross-section of a radiation beam. It should be noted that the pattern imparted to the radiation beam may not precisely match the desired pattern to the target portion of the substrate, for example, if the pattern includes phase-shift features or so-called assist features. Typically, the pattern imparted to the radiation beam corresponds to a specific functional layer within a device, such as an integrated circuit, which is being created within the target portion of the device.

[0037]

[0052] Patterning devices can be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well-known in lithography and include various hybrid mask types, as well as binary, Levenson (alternating) phase-shift, and halftone (attenuated) phase-shift masks. In one example of a programmable mirror array, a matrix of small mirrors is used, each of which can be individually tilted to reflect the incident radiation beam in various directions. The tilted mirrors pattern the radiation beam reflected by the mirror matrix.

[0038]

[0053] The term “projection system” should be broadly interpreted to encompass all types of projection systems, including refractive, reflective, reflective-refracting, magnetic, electromagnetic, and electrostatic optical systems, or any combination thereof, that are appropriate for the exposure radiation used or for other factors such as the use of immersion liquid or vacuum. All use of the term “projection lens” in this specification should be considered synonymous with the more general term “projection system.”

[0039]

[0054] The projection system PS may include a plurality of optical (e.g., lens) elements and may further include an adjustment mechanism configured to adjust one or more of these optical elements to correct aberrations (phase variations across the pupil plane of the entire field). To achieve this, the adjustment mechanism may be operable to manipulate one or more optical (e.g., lens) elements in 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 displacement of one or more optical elements, tilt of one or more optical elements, and / or deformation of one or more optical elements. The displacement of an optical element may be in any direction (x, y, z, or a combination thereof). The tilt of an optical element usually moves away from the plane perpendicular to the optical axis by rotating about the x and / or y axes, but in the case of non-rotationally symmetric aspherical optical elements, rotation about the z axis may be used. Deformations of optical elements may include low-frequency shapes (e.g., astigmatism) and / or high-frequency shapes (e.g., free-form aspherical surfaces). Deformations of optical elements can be performed, for example, by applying force to one or more sides of the optical element using one or more actuators, and / or by heating one or more selected regions of the optical element using one or more heating elements. Generally, it may not be possible to adjust the projection system PS to compensate for apodization (transmittance variations across the pupil plane). A transmittance map of the projection system PS can be used when designing a patterning device (e.g., a mask) MA for the lithography apparatus LA. Computational lithography techniques can be used to design the patterning device MA to compensate for apodization, at least partially.

[0040]

[0055] The lithography apparatus may be of a type having two or more tables (dual stage) (for example, two or more substrate tables WTa, WTb, two or more patterning device tables, a substrate table WTa and a table WTb without a substrate below the projection system, specialized for facilitating measurement and / or cleaning). In such a "multistage" machine, additional tables can be used in parallel, or preliminary processes can be performed on one or more tables while another one or more tables are used for exposure. For example, alignment measurements can be performed using an alignment sensor AS, and / or level (height, tilt, etc.) measurements can be performed using a level sensor LS.

[0041]

[0056] Furthermore, the lithography apparatus may be of a type that can cover at least a portion of the substrate with a liquid having a relatively high refractive index (e.g., water) to fill the space between the projection system and the substrate. Alternatively, an immersion liquid may be applied to another space within the lithography apparatus (e.g., between the patterning device and the projection system). Immersion techniques are well known in the art for increasing the numerical aperture of the projection system. As used herein, the term "immersion" does not mean that a structure such as a substrate must be submerged in a liquid, but simply means that there is a liquid between the projection system and the substrate during exposure.

[0042]

[0057] During operation of the lithography apparatus, the radiant beam is regulated and supplied by the illumination system IL. This radiant beam B is incident on a patterning device (e.g., a mask) MA held on a support structure (e.g., a mask table) MT, and is patterned by the patterning device. After passing through the patterning device MA, the radiant beam B passes through the projection system PS, which focuses the beam onto a target portion C on the substrate W. A second positioner PW and position sensors IF (e.g., an interferometer device, a linear encoder, a 2D encoder, or a capacitive sensor) can be used to precisely move the substrate table WT to position, for example, various target portions C within the path of the radiant beam B. Similarly, a first positioner PM and another position sensor (not explicitly shown in Figure 1) can be used to precisely position the patterning device MA relative to the path of the radiant beam B, for example, after mechanically removing it from the mask library or during scanning. Typically, the movement of the support structure MT can be achieved using long-stroke modules (coarse positioning) and short-stroke modules (fine positioning) that form part of the first positioner PM. Similarly, the movement of the substrate table WT can also be achieved using long-stroke modules and short-stroke modules that form part of the second positioner PW. In the case of a stepper (as opposed to a scanner), the support structure MT may be connected only to short-stroke actuators, or it may be fixed. The patterning device MA and the substrate W may be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. In the example, the substrate alignment marks occupy dedicated target areas, but the substrate alignment marks may also be placed in the space between target areas (these are known as scribe line alignment marks). Similarly, if multiple dies are provided on the patterning device MA, the patterning device alignment marks may be placed between the dies.

[0043]

[0058] The example apparatus can be used in at least one of the modes described below. In step mode, the support structure MT and substrate table WT are kept essentially stationary while the pattern attached to the radiation beam is projected onto the target area C in one step (i.e., single static exposure). The substrate table WT is then moved in the X and / or Y directions, thereby exposing another target area C. In step mode, the maximum size of the exposure field limits the size of the target area C that is imaged during single static exposure. In scan mode, the support structure MT and substrate table WT are scanned synchronously while the pattern attached to the radiation beam is projected onto the target area C (i.e., single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT can be determined by the (reduction) magnification and image inversion characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target area (non-scanning direction) during single dynamic exposure, while the length of the scan operation determines the height of the target area (scanning direction). In another mode, the support structure MT is kept essentially stationary while the programmable patterning device is held, and the substrate table WT is moved or scanned while the pattern attached to the radiation beam is projected onto the target area C. In this mode, a pulsed radiation source is typically employed, and the programmable patterning device is updated as needed after each movement of the substrate table WT, or between consecutive radiation pulses during scanning. This operating mode can be easily applied to maskless lithography utilizing programmable patterning devices such as the aforementioned type of programmable mirror array.

[0044]

[0059] Combinations and / or variations of the above-mentioned usage modes, or completely different usage modes, can also be employed.

[0045]

[0060] The substrate may be processed before or after exposure, for example, with a track (typically a tool for coating a resist layer onto the substrate and developing the exposed resist), or with a metronome or inspection tool. Where applicable, the disclosures herein may be applied to such substrate processing tools or other substrate processing tools. Furthermore, since the substrate may be processed multiple times, for example, to create a multilayer IC, the term "substrate" as used herein may also refer to a substrate that already contains multiple processing layers.

[0046]

[0061] As used herein in relation to lithography, the terms “radiation” and “beam” encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., those with wavelengths of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm), extreme ultraviolet (EUV) radiation (e.g., those with wavelengths in the range of 5 to 20 nm), and particulate beams such as ion beams and electron beams.

[0047]

[0062] Various patterns on a patterning device, or various patterns provided by a patterning device, may have different process windows (i.e., the space of processing variables within which the pattern will be generated within the specified range). Examples of pattern specifications regarding potential systematic defects include checks for necking, line pullback, line thinning, CD, edge placement, overlapping, resist top loss, resist undercut, and / or bridging. The process window of a pattern on a patterning device, or a pattern on an area thereof, can be obtained by integrating (e.g., overlapping) the process windows of each individual pattern. The boundary of the process window of a set of patterns includes the boundary of the process windows of several individual patterns; that is, these individual patterns limit the process window of the set of patterns.

[0048]

[0063] As shown in Figure 2, the lithography apparatus LA may form part of a lithographic cell LC, also called a lithocell or cluster, which includes equipment for pre-exposure and post-exposure processes on the substrate. Conventionally, these devices include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the exposed resist, one or more cooling plates CH, and / or one or more bake plates BK. A substrate handler or robot RO picks up one or more substrates from input / output ports I / O1 and I / O2, moves these substrates between different process devices, and delivers them to the loading bay LB of the lithography apparatus. These devices, often collectively referred to as tracks, are controlled by a track control unit TCU, which in turn is controlled by a monitoring and control system SCS, which also controls the lithography apparatus via a lithography control unit LACU. In this way, various devices can be operated to maximize throughput and processing efficiency.

[0049]

[0064] To ensure that substrates exposed by a lithography apparatus are exposed accurately and consistently, and / or to monitor a patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., a photolithography step), it is desirable to inspect the substrate or other object and measure or determine one or more properties, such as alignment, overlay (e.g., overlay of structures within multiple overlapping layers, or overlay of multiple structures within the same layer, which may be structures separately provided in that layer by, for example, a double patterning process), line width, critical dimension (CD), focus offset, material properties, etc. Therefore, a manufacturing facility where a lithocell LC is located usually also includes a metronome system for measuring some or all of the substrates W (Figure 1) processed in the lithocell or other objects within the lithocell. The metronome system may be part of the lithocell LC, for example, part of the lithography apparatus LA (e.g., alignment sensor AS (Figure 1)).

[0050]

[0065] One or more parameters to be measured include, for example, alignment, overlays of consecutive layers formed on or within a patterned substrate, critical dimension (CD) of features formed on or within a patterned substrate (e.g., critical linewidth), focus or focus error of a photolithography step, dose or dose error of a photolithography step, and optical aberration of a photolithography step. This measurement is often performed on one or more dedicated metronidatory targets provided on the substrate. The measurement can be performed after resist development but before etching, after etching, after deposition, and / or at other times.

[0051]

[0066] Various techniques exist for measuring structures formed by patterning processes, including scanning electron microscopes, image-based measurement tools, and / or various specialized tools. A fast and non-invasive form of specialized metrology tool involves guiding a radiation beam to a target on the substrate surface and measuring the properties of the scattered (diffracted / reflected) beam. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. This is sometimes referred to as diffraction-based metrology. Applications of diffraction-based metrology include measurements of overlay and alignment. For example, overlay and / or alignment can be measured by comparing portions of the diffraction spectrum (e.g., comparing different diffraction orders within the diffraction spectrum of a periodic grating).

[0052]

[0067] Therefore, in device manufacturing processes (e.g., patterning or lithography processes), various types of measurements may be performed on the substrate or other objects during or after the process. These measurements may serve purposes such as determining whether a particular substrate is defective, setting adjustments to the process or the equipment used in the process (e.g., alignment of two layers on the substrate or alignment of a patterning device on the substrate), measuring the performance of the process and equipment, or other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements such as the ASML YieldStar metrology tool or ASML SMASH metrology system), mechanical measurements (e.g., shape measurement using a stylus, atomic force microscopy (AFM)), and / or non-optical imaging (e.g., scanning electron microscopy (SEM)).

[0053]

[0068] Metrology results may be provided directly or indirectly to the monitoring and control system (SCS). If an error is detected, adjustments can be made to subsequent exposure of substrates (especially if inspection could be performed quickly and promptly, and one or more other substrates in the batch have not yet been exposed) and / or subsequent exposure of exposed substrates. Furthermore, already exposed substrates can be removed and reprocessed or discarded to improve yield, thus avoiding further processing of substrates found to be defective. If only a portion of the target area of ​​the substrate is defective, further exposure may be performed only on the target area that meets the specifications. Other adjustments to the manufacturing process are also possible.

[0054]

[0069] A metronome system can be used to determine one or more properties of a substrate structure, particularly how one or more properties of different substrate structures change, or how different layers of the same substrate structure change layer by layer. The metronome system may be integrated with a lithography apparatus (LA) or lithocell (LC), or it may be a standalone device.

[0055]

[0070] To enable metrologic, one or more targets are often provided specifically on the substrate. Typically, the targets are specially designed and may include periodic structures. For example, a target on the substrate may include one or more one-dimensional periodic structures (e.g., geometric features such as a grid), which are printed such that after development, the periodic structural features are formed by solid resist lines. As another example, the target may include one or more two-dimensional periodic structures (e.g., a grid), which are printed such that after development, one or more periodic structures are formed by solid resist pillars or vias in the resist. Alternatively, bars, pillars, or vias may be etched into the substrate (e.g., one or more layers on the substrate).

[0056]

[0071] Figure 3 shows an example of a metrology (inspection) system 10 that can be used to perform overlay, alignment detection, and / or other metrology operations. This system includes a radiation source or illumination source 2 that projects or otherwise irradiates a substrate W (e.g., a substrate that may typically contain metrology marks) with radiation. The redirected radiation is sent to a sensor, such as a spectrometer detector 4 and / or other sensors, which measures the spectrum (intensity as a function of wavelength) of specularly reflected and / or diffracted radiation, for example, as shown in the graph on the left side of Figure 4. The sensor may generate a metrology signal that transmits metrology data describing the characteristics of the reflected radiation. From this data, the structure or profile that yields the detected spectrum can be reconstructed by one or more processors PRO (a generalized example of which is shown in Figure 4) or by other operations.

[0057]

[0072] Similar to the lithography apparatus LA in Figure 1, one or more substrate tables (not shown in Figure 4) may be provided to hold the substrate W during measurement. One or more substrate tables may be similar to or identical in form to the substrate table WT (WTa or WTb, or both) in Figure 1. If the inspection system 10 is integrated with the lithography apparatus, they may be the same substrate table. Coarse and fine positioners may be provided and configured to precisely position the substrate relative to the measuring optical system. For example, various sensors and actuators may be provided to acquire the position of a target portion of a structure (e.g., a metrologic mark) and position it under the objective lens. Typically, many measurements will be taken on the target portion of the structure at various positions on the entire substrate W. The substrate support can be moved in the X and Y directions to acquire different targets, and can also be moved in the Z direction to obtain the desired position of the target portion relative to the focal point of the optical system. For example, when the optical system is actually substantially stationary (usually in the X and Y directions, but sometimes in the Z direction as well) and the substrate is moving, it is convenient to explain the operation by considering that the objective lens is being placed in various positions relative to the substrate. If the relative positions of the substrate and the optical system are correct, then, in principle, it does not matter whether one or both are moving, or whether a part of the optical system is moving (for example in the Z direction and / or the tilt direction) while the rest of the optical system is stationary, and the substrate is moving (for example in the X and Y directions, and sometimes in the Z direction and / or the tilt direction as well).

[0058]

[0073] In a typical metronidometry measurement, the target 30 on the substrate W may be a one-dimensional grid, which is printed so that after development (for example, it may be covered with a deposited layer) bars are formed of solid resist lines and / or other materials. Alternatively, the target 30 may be a two-dimensional grid, which is printed so that after development the grid is formed of solid resist pillars and / or other features in the resist.

[0059]

[0074] Bars, pillars, vias, and / or other features may be etched in or on the substrate (e.g., in one or more layers on the substrate), deposited on the substrate, covered by a deposited layer, and / or have other properties. The target (part) 30 (e.g., consisting of bars, pillars, vias, etc.) is susceptible to changes in the patterning process (e.g., optical aberrations, changes in focus, changes in dose, etc. in the lithography projection apparatus (projection system, etc.)), so process variations appear as variations in the target 30. Therefore, measurement data from the target 30 can be used to determine adjustments for one or more manufacturing processes, and / or the measurement data from the target 30 can be used as a basis for making actual adjustments.

[0060]

[0075] For example, measurement data from target 30 may indicate the overlay of a particular layer of a semiconductor device. Based on this overlay, the measurement data from 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, and based on the determined one or more semiconductor device manufacturing process parameters, to determine adjustments to the semiconductor device manufacturing equipment. In some embodiments, this may include, for example, adjustments to the stage position, or it may include determining adjustments to the mask design, the design of the metrology target, the design of the semiconductor device, the intensity of radiation, the angle of incidence of radiation, the wavelength of radiation, the pupil size and / or shape, the resist material, and / or other process parameters.

[0061]

[0076] Figure 5 shows a typical range of the radiant illumination spot S in the system of Figure 4, along with a plan view of a typical target (e.g., a metrologic mark) 30. Typically, to obtain a diffraction spectrum free from interference from the surrounding structure, the target 30 is, in one embodiment, a periodic structure (e.g., a grating) 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. That is, the target is "underfilled" by the illumination, and the diffraction signal does not include signals from product features, etc., outside the target itself. The illumination arrangement can be configured, for example, to provide illumination of uniform intensity across the entire back focal plane of the objective system. Alternatively, illumination can be restricted in the on-axis or off-axis direction, for example, by including an aperture in the illumination path.

[0062]

[0077] Figure 6 shows a metronome system 600. Metrology operations performed by the system 600 may include imaging of one or more metronome targets 30. The targets 30 may include one or more metronome marks (such as diffraction grating targets) formed on a substrate 602, such as a semiconductor wafer, and these are collectively referred to as targets 30. The targets 30 may include one or more structures in a patterned substrate that are capable of providing diffraction signals. For example, one or more targets 30 may be included in a layer of a substrate of a semiconductor device structure. In some embodiments, features may include geometric features such as one-dimensional or two-dimensional features, and / or other geometric features. In some non-limiting examples, features may include grids, lines, edges, a series of fine-pitch lines and / or edges, and / or other features.

[0063]

[0078] System 600 includes a radiation sensor 604 configured to receive radiation from target 30 and generate a metronome signal. The radiation can be used to obtain an image of the metronome target 30 and / or the radiation can be used for other purposes. The radiation may include illumination such as light and / or other radiation. System 600 includes an optical element 606 configured to receive radiation reflected from target 30 and substrate 602, change the angle of the radiation, and guide the radiation to sensor 604. The optical element 606 includes an array of optical components 605, as described below. System 600 also includes one or more processors PRO operably connected to the radiation sensor 604, which are configured to determine metronome measurements based on the metronome signal, determine the focal position for imaging the substrate, detect wavefront aberrations, and / or perform other operations.

[0064]

[0079] System 600 may be similar to, and / or identical to, system 10 shown in Figure 3. Figure 6 provides additional details of system 600 compared to system 10. In some embodiments, system 600 may form a part of system 10 as described above with reference to Figure 3. System 600 may be, for example, 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 one or more components of system 10, be used together with those components, and / or extend those components in other ways.

[0065]

[0080] System 600 comprises a radiation source 612, an optical element 606, an overlay detection branch 660 including a sensor 604, a beam splitter 670, an alignment branch 680, various lenses, reflectors and other optical components (including the exemplary objective lens 690 labeled in Figure 6), and / or other components. In some embodiments, the components of System 600 form part of an overlay sensor and / or alignment sensor used in a semiconductor manufacturing process. The radiation source 612 is configured to generate radiation reflected from the target 30 along an optical path such as the optical path 621. The radiation may have a target wavelength and / or wavelength range, a target intensity, and / or other properties. The target wavelength and / or wavelength range, target intensity, etc., may be input and / or selected by the user, determined by the system (e.g., System 10 shown in Figure 3) based on past measurements, and / or determined in other ways. In some embodiments, the radiation includes light and / or other radiation. In some embodiments, the light includes visible light, infrared light, and / or other light. In some embodiments, the radiation may be any radiation suitable for interferometry.

[0066]

[0081] System 600 does not include a separate focal branch 650 (shown as deleted in Figure 6) or a separate wavefront aberration sensor. System 600 provides a novel optical design architecture. Instead of using a focal branch 650 or the principle of focus measurement described above, System 600 determines the focal position using the position of a field image acquired from the target 30 in the substrate during a metrologic measurement using the sensing components of this system (e.g., sensor 604, optical element 606, array of optical components 605, etc.). System 600 may include a microlens array in which two of the optical components in the array of optical components 605 include a microlens array, and each microlens in the microlens array is configured to form a focal spot on sensor 604, the position of which can be used to determine the radiated wavefront aberration.

[0067]

[0082] This novel architecture eliminates the need for wedges (and associated lenses), components of the focal branch 650, and / or separate wavefront aberration sensors, resulting in reduced cost and bulk compared to conventional systems. This novel architecture improves radiation throughput to the sensor 604 because it eliminates the need for an additional beam splitter to couple the focal branch 650 with the rest of the system 600. This novel architecture eliminates the need for color focus calibration because there is no change in radiation wavelength between the sensor 604 and the focal branch 650 (for example, because the focal branch 650 does not exist). This novel architecture enables continuous focus determination because switching between focus mode and measurement mode is unnecessary. This novel architecture takes into account wavefront errors in the objective system and / or offers other advantages.

[0068]

[0083] Radiation reflected from a target 30 within a substrate 602, such as a semiconductor wafer, is received by an optical element 606, including an array of optical components 605, which changes the angle of the radiation and directs it to a radiation sensor 604. The radiation from the array of optical components 605 is received by the sensor 604, which generates a signal indicating the field image position of this radiation. The radiation sensor 604 may be similar to, and / or identical to, the detector 4 and / or processor PRO and / or other components shown in Figure 3. In some embodiments, the sensor 604 includes a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS), a photodiode array, and / or other sensors. In some embodiments, the sensor 604 includes a microdiffraction-based overlay camera related to overlay measurement. In conventional systems, the overlay detection branch 660 included a wedge and / or other optical components, such as a microdiffraction-based overlay wedge.

[0069]

[0084] For example, Figure 7 shows an overlay detection branch 660 including an optical wedge 700, a lens 702 (e.g., similar to and / or identical to the objective lens 690 in Figure 6), lenses 704, 706, 708, a sensor 604, an illumination pupil 711, a detection pupil 712, and an exemplary field image 714 (the array of optical components 605 in Figure 6 is not included here). The wedge 700 includes four pieces positioned in the plane of the detection pupil 712, which redirect the +1st and -1st order diffraction (in the upper right and lower left quadrants) and the zeroth order (in the upper left and lower right quadrants) of radiation 720 from the substrate 602 to four spaced-apart positions in the field image 714. However, these components are bulky, complex, and expensive. For example, the cost of the optical wedge and the cost of the physical system space required to incorporate the optical wedge are high compared to other optical components.

[0070]

[0085] Figure 8 shows the replacement of system 600 with an optical component array (optical component array 605) to simplify the system. The optical component array 605 is less expensive and optically relatively simpler than the optical wedge 700 (Figure 7). Replacing the wedge 700 and lens 708 with the optical component array 605 reduces the number of elements in system 600 (Figure 6). For example, the optical component array 605 replaces the wedge 700 and one or more lenses (e.g., lens 708) shown in Figure 7. The optical component array 605 is configured to receive radiation 710 of different diffraction orders from the substrate 602, change the angles of the radiation 710 of different diffraction orders, and guide the radiation 710 of different diffraction orders to different imaging positions on the radiation sensor 604 to generate a field image 714.

[0071]

[0086] In some embodiments, the array of optical components 605 includes four optical components (e.g., divided into quadrants Q1 to Q4), where two of the four optical components are associated with zero-order diffraction radiation 710 and two of the four optical components are associated with first-order diffraction radiation 710. Each quadrant is configured to direct a portion of the radiation (e.g., zero-order radiation and / or + / -1st-order radiation) to different regions of interest of the sensor 604 to form spots of radiation on the sensor 604 (see corresponding field image 714). In some embodiments, the array of optical components 605 includes an array of lenses and / or other components. The cross-sectional shape of each lens may be, for example, circular 800, square 802, and / or other shapes.

[0072]

[0087] In some embodiments, an array of four circular lenses may be used. While circular lenses may not capture a small portion of the illumination in or near the central area of ​​the pupil, they may be convenient in terms of integration and / or have other advantages. In some embodiments, an array of four square lenses may be used, in which case the entire pupil will be captured. In some embodiments, cylindrical lenses, which may be less expensive than square lenses, may be used for the zero-order quadrants Q1 and Q3. Other configurations are also conceivable.

[0073]

[0088] The lens power of these lenses may be configured to maintain the peripheral ray angle at sensor 604, the target magnification at sensor 604, and / or to have other effects. This may enable lower costs and miniaturization of the detection branch 660 of system 600 (Figure 6), and / or other advantages. It is also possible to optimize the optical axis position of the lenses. By changing the y-dimension of the optical axis of each lens, in this example, the angle of the rays emanating from each lens can be linearly adjusted. Each lens also has its own optical axis, and each lens can be individually selected to obtain the desired inclination of the rays emanating from it. This makes it possible to change the xy position of the image in each quadrant from sensor 604.

[0074]

[0089] In some embodiments, the array of optical components 605 includes a spatial light modulator (SLM). This SLM may be transmissive or reflective, or may have transmissive or reflective portions. The SLM may include liquid crystals, digital micromirror devices (DMDs), patterns configured to change the angle of radiation of different diffraction orders, and / or other functions configured to guide different diffraction orders of radiation to different imaging positions on the radiation sensor. In some embodiments, the array of optical components 605 includes a metalens array. One or more processors PRO (for example, shown in Figures 3, 6, and 15 below) are operably connected to the radiation sensor 604 and configured to determine metronome measurements based on metronome signals. Metronome measurements may include, for example, alignment values, overlay values, focus values, critical dimension values, and / or other metronome measurements related to the semiconductor manufacturing process performed on the substrate 602.

[0075]

[0090] In some embodiments, as shown in Figure 9, two optical components within an array of optical components 605 (components in quadrants Q1 and Q3 in this example) are configured to create two oppositely defocused (900, 902) zero-order images at two different imaging positions on the radiation sensor 604 (see corresponding defocused images 904, 906 in the field image 910). This configuration may include, for example, changing the curvature of the two optical components so that positive and negative defocus occurs on the image planes of these two quadrants. A differential defocus signal can be measured from these two zero-order images, thus enabling real-time focus detection and / or other operations.

[0076]

[0091] For example, one or more processors PRO determine the deviation of images 904 and / or 906 at the field image position from the predicted field image position. This deviation is caused by defocused radiation incident on the detection pupil 712. The signal generated by sensor 604 indicates four separate field image positions of the radiation spot. Furthermore, the blur of images 904 and / or 906 can be used in the same way. For example, if images 904 and 906 are shifted by the same distance and blurred to the same level, an ideal focus can be achieved. One or more processors PRO (e.g., the PROs shown in Figures 3 and 6, and / or one or more processors described below in relation to Figure 15) operably connected to the radiation sensor 604 may be configured to determine a focal position for imaging the substrate 602 in system 600 (Figure 6) based on the oppositely defocused zero-order images 904 and 906, blur, and / or other information at two different imaging positions on the radiation sensor 604.

[0077]

[0092] In some embodiments, the focal position is determined based on the relationship between the above-mentioned displacement and the defocus of the objective system of the metrology system 600. This relationship may be linear and / or other corresponding relationships may exist. For example, one or more processors (e.g., the PRO shown in Figure 3, and / or one or more processors described below in relation to Figure 15) are configured to determine the displacement of the zero-order spot and the primary spot, and to determine the focal position based on the displacement of the zero-order spot and the primary spot. A linear relationship between the above-mentioned displacement and the defocus of the objective system means that the more the defocus increases, the further the spot moves from its predicted position. This displacement and this relationship can be used to determine the (best) focal position of an optical component such as the objective system 690 for imaging the target 30. In some embodiments, one or more processors PRO can determine the displacement of the field image positions of field images 904, 906, for example, based on the centroid of the radiating spot in image 910, and / or by other means. In some embodiments, the displacement of the field images 904 and 906 is determined based on intensity detection of the field images 904 and 906. In some embodiments, for example, intensity detection is determined in one or more semi-circular portions of one or more annular portions of the radiation spot in the field images 904 and 906. Furthermore, as described above, blurring of images 904 and / or 906 can also be used. For example, if images 904 and 906 are shifted by the same distance and blurred to the same level, an ideal focus can be achieved.

[0078]

[0093] In some embodiments, one or more processors are configured to automatically adjust the position of the stage of the system 600 holding the substrate 602 (e.g., a stage similar to WTa and / or WTb shown in Figure 1 and described above, and / or the same stage) based on the focal position so that the subsequent image of the substrate 602 is in focus. Figure 9 shows an array of optical components 605 including an array of lenses having the cross-sectional shape of the square 802 of Figure 8 as a possible example. However, these lenses may have any shape that enables them to perform the functions described herein.

[0079]

[0094] In some embodiments, two optical components within the array of optical components 605 include a microlens array, where each microlens in the microlens array is configured to form a focal spot on the radiation sensor 604, the position of which can be used to determine the radiation wavefront aberration. Individual lenslets in the microlens array may collect light filling their apertures to form a focal spot on the sensor 604, these spots located on the focal plane of the microlens array. For aberration-free wavefronts (e.g., zero gradient), a spot is created at the center behind each individual lenslet, which can be used as a reference position. For aberration-affected wavefronts (e.g., non-zero gradient), the position of the spot is displaced relative to the corresponding reference position. Measuring this displacement facilitates the determination of wavefront aberration (e.g., wavefront gradient). For example, one or more processors PRO (Figures 3, 6, and 15) operably connected to the radiation sensor 604 may be configured to detect radiation wavefront aberration based on the (displaced) position of the focal spot relative to the reference position. Furthermore, the minimum gradient detectable by one or more processors corresponds to the minimum defocus measurable by sensor 604 and / or one or more processors PRO.

[0080]

[0095] As an example, Figure 10 shows microlenses 1000 (e.g., lenslets) in a microlens array 1001 configured to form a focal spot 1002 on a radiation sensor 604, and the position of the focal spot 1002 can be used to determine the aberrations of the radiation wavefronts 1004 and 1006. Each microlens 1000 in the microlens array 1001 can collect light filling its aperture to form a focal spot 1002 on the sensor 604. For aberration-free wavefronts 1004 (e.g., zero gradient), the spot 1002 is created at the center directly behind each lenslet, as shown in Figure 1020, and these can be used as reference positions 1003. For aberration-affected wavefronts 1006 (e.g., non-zero gradient), the position of the spot 1008 is displaced relative to the corresponding reference position 1003 (as shown in Figure 1021). Measuring this displacement facilitates the determination of wavefront aberration (e.g., wavefront gradient). For example, one or more processors PRO (Figures 3, 6, and 15) operably connected to the radiation sensor 604 may be configured to detect radiation wavefront aberration based on the (displaced) position of the focal spot relative to a reference position. In the example in Figure 10, several displaced spots 1012 are shown along with missing spots 1014.

[0081]

[0096] Figure 11 also shows microlenses 1000 (e.g., lenslets) in a microlens array 1001 (Q1 and Q4 in this example) configured to form a focal spot 1002 on the radiation sensor 604 (see also image 1100 in image 1102, corresponding to the focal spot 1002), the position of the focal spot 1002 which can be used to determine radiation wavefront aberration, but is available in conjunction with an array of optical components 605 similar to those shown in Figures 8 and 9. As shown in Figure 11, two optical components in the array of optical components 605 include a microlens array 1001, and each microlens 1000 (lenslet) in the microlens array 1001 is configured to form a focal spot 1002 on the radiation sensor 604. In this example, the microlens arrays 1001 of Q1 and Q4 and the zero-order radiation 710 may be used to detect aberrations.

[0082]

[0097] Each microlens 1000 (lenslet) within the microlens array 1001 can collect light filling its aperture to form a focal spot 1002 located at the focal plane 1110 of the (one or more) microlens array 1001. As shown in Figure 12, the focal plane 1110 of the (one or more) microlens array 1001 may not be the same as the focal plane 1202 of the spot 1200 of radiation 710 from other optical components in the array of optical components 605 (e.g., lenses Q2 and Q3 in this example). Therefore, in some embodiments, the microlens array 1001 may be positioned in a different plane of the system 600 (Figure 6) compared to other optical components in the array of optical components 605, such that the radiation sensor 604 is located at the focal plane 1110 of the microlens array 1001 and other optical components in the array of optical components 605 (lenses Q2 and Q3 in this example). For example, the microlens array 1001 may be positioned such that the illustrative focal planes 1110 and 1202 shown in Figure 12 coincide (for example, on or near the sensor 604).

[0083]

[0098] Figure 13 shows another embodiment in which the radiation sensor 604 includes one or more sub-parts 1300 configured to detect the focus spot 1002 in Figures 10-12. In this example, the overlay detection branch 660 of system 600 (Figure 6) includes a segmented mirror 1302 (and / or similar functional component) configured to direct radiation from the microlens array 1001 (in this example, quadrants Q1 and Q4) to the sub-parts 1300 of the radiation sensor 604. The sub-parts 1300 can also be independent sensors with different operating specifications (and thus, in fact, separate sensors rather than sub-parts) introduced separately from the radiation sensor 604. For example, if a high defocus monitoring speed is required, the sub-part 1300 may have a faster detection speed than the sensor 604. If high spatial resolution is not required (or is not needed) for defocus monitoring, the sub-part 1300 may have fewer pixels than the sensor 604 (e.g., faster and less expensive). The mirror 1302 may be, for example, a segmented mirror mounted on an edge, and / or another component configured for a similar function. Figure 13 shows a side view 1305, a front view 1310, and a top view 1320 of the mirror 1302. Radiation from the optical components 605 in quadrants Q2 and Q3 may be directed to the sensor 604 as described above. The mirror 1302 may be positioned and / or otherwise configured such that the spot 1002 of radiation 710 is formed on the focal plane corresponding to the sub-part 1300. In this example, the focal length of the microlens array 1001 in quadrants Q1 and Q4 may be approximately 10-20 nm, and the focal length of the optical components 605 in quadrants Q2 and Q3 may be approximately 190 nm. Other configurations are also conceivable.

[0084]

[0099] Returning to Figure 6, various lenses (labeled as an objective lens 690 in Figure 6 as an example), reflectors, and other optical components are configured to receive, transmit, reflect, focus, and / or otherwise perform illumination, which is generated by the radiation source 612, split by the beam splitter 670, transmitted or reflected by various optical elements, received by the detection branch 660, received by the alignment branch 680, and / or used by other parts of the system 600. These various lenses, reflectors, and / or other optical components may include any type of lens, reflector, and / or other optical component configured to enable the system 600 to function as described. For example, the objective lens 690 may be formed from any transparent material and may have a curved surface configured to concentrate or otherwise focus one or more radiation spots on (one or more) targets 30. Various lenses, reflectors, optical elements, beam splitters, and other optical elements may be positioned relative to each other at any position and / or angle, enabling the system 600 to function as described herein. This may include positioning at a specific relative distance between elements, a specific angle between elements, etc. In some embodiments, various lenses, reflectors, optical elements, beam splitters, and other optical components are positioned relative to each other within the system 600 via structural members, clips, clamps, screws, nuts, bolts, adhesives, and / or other mechanical devices. In some embodiments, various lenses, reflectors, optical elements, beam splitters, and other optical elements are movable relative to each other. The movement may be configured, for example, to adjust the position of a corresponding illumination spot on one or more targets 30. In some embodiments, the movement includes tilting, translating, or otherwise changing the distance between various lenses, reflectors, and other optical components. Other examples of movement are also conceivable.

[0085]

[0100] In some embodiments, movement may be electronically controlled by a processor such as processor PRO (also shown in Figure 3 and Figure 15, which is referred to below). Processor PRO may be included in a computing system CS (Figure 15), and processor PRO may operate on computer or machine-readable instructions (for example, as described below in relation to Figure 15). Electronic communication may be performed by transmitting electronic signals between separate components, transmitting data between separate components of system 600, transmitting values ​​between separate components, and / or other communications. Components of system 600 may communicate by wire or wirelessly over a network, such as the Internet, or a combination of the Internet and various other networks such as local area networks, cellular networks, personal area networks, internal organization networks, and / or other networks.

[0086]

[0101] In some embodiments, one or more actuators (not shown in Figure 6) may be coupled to one or more components of the system 600 and configured to move those components. The actuators may be coupled to one or more components of the system 600 by adhesive, clips, clamps, screws, retaining rings, and / or other mechanisms. The actuators may be configured to be electronically controlled. Individual actuators may be configured to convert electrical signals into mechanical displacements. The mechanical displacements are configured to move components of the system 600. As an example, one or more of the actuators may be piezoelectric. One or more processors PRO may be configured to control these actuators. One or more processors PRO may be configured to control each of the one or more actuators separately.

[0087]

[0102] The quantities of various lenses, reflectors, and / or other optical components shown in Figure 6 are not intended to be limiting. The principles described herein may be extended in some embodiments to include additional lenses, reflectors, and / or other optical components in the system 600, or fewer lenses, reflectors, and / or other optical components.

[0088]

[0103] Figure 14 shows the metrologic method 1400. In some embodiments, the method 1400 is performed, for example, as part of an overlay and / or alignment detection operation in a semiconductor device manufacturing process. In some embodiments, one or more operations of the method 1400 are performed in, or may be performed by, a system, for example, the system 600 shown in Figure 6, the system 10 shown in Figure 3, a computer system (for example, one shown in Figure 15 and described below), and / or other systems. In some embodiments, Method 1400 includes receiving radiation reflected from a substrate by an array of optical components (operation 1402), changing the angles of different diffraction orders of this radiation to guide the radiation of those different diffraction orders to different imaging positions on a radiation sensor, determining a focal position for imaging the substrate (operation 1404), detecting wavefront aberration (operation 1406), generating a metronome signal based on the radiation received at the different imaging positions (operation 1408), determining a metronome measurement based on the metronome signal, focal position, wavefront aberration, and / or other information (operation 1410), and / or performing other operations.

[0089]

[0104] The operations of Method 1400 described above are for illustrative purposes only. In some embodiments, Method 1400 may be completed with one or more additional operations not described and / or without performing one or more of the operations described. For example, in some embodiments, Method 1400 may include additional operations including determining adjustments to the semiconductor device manufacturing process. Furthermore, the order of operations of Method 1400 shown in Figure 14 and described herein is not intended to be limiting.

[0090]

[0105] In some embodiments, one or more parts of Method 1400 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 for electronically processing information). One or more processing devices may include one or more devices that perform some or all of the operations of Method 1400 in response to instructions electronically stored in an electronic storage medium. One or more processing devices may include one or more devices configured via hardware, firmware, and / or software to be specifically designed to perform one or more operations of Method 1400 (see, for example, the description related to Figure 15 below).

[0091]

[0106] In operation 1402, radiation reflected from the substrate is received by an array of optical components. The array of optical components is configured to change the angles of different diffraction orders of this radiation, guiding those different diffraction orders to different imaging positions on the radiation sensor. The radiation sensor may be similar to, and / or identical to, the detector 4, sensor 604, and / or processor PRO (operably coupled with the radiation sensor), and / or other components shown in Figures 3 and 6. In some embodiments, the array of optical components may be similar to and / or identical to one or more of the arrays 605 of optical components shown in Figures 8-13 above. These arrays of optical components may include four optical components (e.g., divided into quadrants Q1-Q4), two of which relate to zero-order diffraction radiation and two relate to first-order diffraction radiation. Each quadrant is configured to guide a portion of the radiation (e.g., zero-order radiation and / or + / -1st-order radiation) to a different region of interest of the sensor, thereby forming a spot of radiation on the sensor.

[0092]

[0107] In some embodiments, the array of optical components includes a lens array. The cross-sectional shape of each lens may be, for example, circular or square. In some embodiments, the array of optical components includes a spatial light modulator (SLM). The SLM may be transmissive or reflective, or may have transmissive or reflective portions. The SLM may include liquid crystal, a digital micromirror device (DMD), a pattern configured to change the angle of different diffraction orders of radiation, and / or other functions configured to guide different diffraction orders of radiation to different imaging positions on the radiation sensor. In some embodiments, the array of optical components includes a metalens array.

[0093]

[0108] In some embodiments, operation 1402 includes generating radiation using a radiation source (e.g., radiation source 2 shown in Figure 3, and / or radiation source 612 shown in Figure 6) and directing the radiation to a substrate. In some embodiments, the substrate includes a semiconductor wafer having one or more targets configured to reflect the radiation to an array of optical components. In some embodiments, the sensor includes a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS), a photodiode array, and / or other sensors. In some embodiments, the sensor includes a microdiffraction-based overlay camera related to overlay measurement.

[0094]

[0109] In some embodiments, operation 1402 includes illuminating (and / or otherwise irradiating) one or more targets (e.g., target 30 shown in Figure 3) within a patterned substrate with radiation. The radiation includes light and / or other radiation. In some embodiments, the radiation may be directed by the radiation source onto multiple targets, onto a single target, onto a sub-part of a target (e.g., a part smaller than the whole), and / or onto the substrate in other ways. In some embodiments, the radiation may be directed by the radiation source onto the target in a time-varying manner. For example, the radiation may be raster-scanned over the target (e.g., by moving the target under the radiation) so that different parts of the target are irradiated at different times. As another example, the properties of the radiation (e.g., wavelength, intensity, etc.) may be varied. This can create a time-varying data envelope or window for analysis. The data envelope can facilitate analysis of individual sub-parts of a target, comparison of one part of a target with another, and / or comparison with other targets (e.g., in other layers), and / or other analyses.

[0095]

[0110] In some embodiments, operation 1402 includes detecting reflected radiation from one or more diffraction grating targets (by the radiation sensors described above). Detection of reflected radiation includes detecting one or more phase shifts and / or amplitude (intensity) shifts in the reflected radiation from one or more geometric features of the target (one or more). The one or more phase shifts and / or amplitude shifts correspond to one or more dimensions of the target. For example, the phase and / or amplitude of reflected radiation from one face of the target is different from the phase and / or amplitude of reflected radiation from another face of the target.

[0096]

[0111] Detecting one or more phase shifts and / or amplitude (intensity) shifts in reflected radiation from a target involves measuring local phase shifts (e.g., local phase deltas) and / or amplitude variations corresponding to different parts of the target. For example, reflected radiation from a particular area of ​​a target may include a sinusoidal waveform with constant phase and / or amplitude. Reflected radiation from another area of ​​the target (or a target in another layer) may also include a sinusoidal waveform, but with a different phase and / or amplitude. Detecting the detected reflected radiation also involves measuring the phase difference and / or amplitude difference in reflected radiation of different diffraction orders. Detecting one or more local phase shifts and / or amplitude shifts may be done, for example, using a Hilbert transform, and / or other techniques. Interferometry techniques and / or other operations may be used to measure the phase difference and / or amplitude difference in reflected radiation of different diffraction orders.

[0097]

[0112] In operation 1404, the focal position for imaging the substrate is determined. In some embodiments, two optical components in an array of optical components are configured to create two oppositely defocused zero-order images at two different imaging positions on the radiation sensor (see Figure 9). One or more processors, such as processor PRO, are configured to determine the focal position for imaging the substrate in the metrology system based on the oppositely defocused zero-order images at the two different imaging positions on the radiation sensor. In some embodiments, one or more processors are configured to automatically adjust the position of the stage in the metrology system holding the substrate based on the above focal position so that the subsequent image of the substrate is in focus.

[0098]

[0113] In operation 1406, wavefront aberration is detected. In some embodiments, two optical components in an array of optical components include a microlens array and / or other components. Each microlens in the microlens array is configured to form a focal spot on the radiation sensor, and its position can be used to determine the radiation wavefront aberration (see Figures 10-11 and the corresponding descriptions above). One or more processors PRO may be configured to detect wavefront aberration based on the position of the focal spot relative to a reference position and / or other information. In some embodiments, the microlens array is positioned in a different plane of the metrology system compared to other optical components in the array of optical components, such that the radiation sensor is located at the focal plane of the microlens array and the focal plane of other optical components in the array of optical components. In some embodiments, the radiation sensor includes a sub-part (located in a different plane) configured to detect the focal spot (see Figure 12 above). Operation 1406 may also include using segmented mirrors to guide radiation from the microlens array to the sub-part of the radiation sensor (e.g., as shown in Figure 13 and described above).

[0099]

[0114] In operation 1408, a metrology signal is generated based on radiation received at different imaging locations and / or other information. The metrology signal is generated by a radiation sensor (e.g., detector 4 and / or other sensors shown in Figure 3). The metrology signal includes an electronic signal representing radiation reflected from (one or more) targets and / or an electronic signal otherwise corresponding to such radiation. The metrology signal may indicate, for example, a metrology value related to a diffraction grating target and / or other information. Generating a metrology signal involves detecting reflected radiation and converting the detected reflected radiation into an electronic signal. In some embodiments, generating a metrology signal includes detecting different portions of reflected radiation from different areas and / or different geometric shapes of a target and / or different portions of reflected radiation from multiple targets and combining these different portions of reflected radiation to form a metrology signal. This may include generating and / or analyzing one or more images of a target using the radiation described herein. This detection and conversion may be performed by the detector 4, sensor 604, and / or components similar to and / or the processor PRO shown in Figures 3 and 6, and / or by other components.

[0100]

[0115] In operation 1410, a metronome measurement is determined based on the metronome signal, focal position, wavefront aberration, and / or other information. This metronome measurement may be determined by one or more processors (e.g., processor PRO as described herein) and / or other components. In some embodiments, the metronome measurement includes alignment values, overlay values, focal values, critical dimension values, and / or other metronome values ​​related to the semiconductor manufacturing process performed on the substrate. The measurement information (e.g., overlay values, alignment values, and / or other information) may be determined using the principles of interferometry and / or other principles. In some embodiments, for example, operation 1410 includes determining the overlay and / or alignment. The overlay and / or alignment may be determined based on reflected and diffracted radiation from a diffraction grating target on the substrate, focal position, wavefront aberration, and / or other information.

[0101]

[0116] In some embodiments, Method 1400 includes determining adjustments to the semiconductor device manufacturing process. For example, this may include, by having one or more processors PRO automatically adjust the position of the stage of the metrology system holding the substrate based on the determined focal position so that the subsequent image of the substrate is in focus (as described above). In some embodiments, Method 1400 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 variations, overlay and / or alignment values ​​indicated by the metrology signal, and / or other information. One or more parameters may include radiation (radiation used for metrology), metrology inspection positions on layers of the semiconductor device structure, trajectories of the radiation beam across the target, and / or other parameters. In some embodiments, process parameters can be broadly interpreted to include stage position, mask design, metronome target design, semiconductor device design, radiation intensity (used in resist exposure, etc.), radiation incidence angle (used in resist exposure, etc.), radiation wavelength (used in resist exposure, etc.), pupil size and / or shape, resist material, and / or other parameters.

[0102]

[0117] In some embodiments, Method 1400 includes determining process adjustments based on one or more determined semiconductor device manufacturing process parameters, adjusting semiconductor device manufacturing equipment based on the determined adjustments, and / or other operations. This may be performed by one or more processors, e.g., the PRO shown in Figures 3 and 6, the processor described in Figure 15 and described as part of the computer system described below, and / or other processors. For example, if a determined metronome measurement is not within the range of process tolerances, such out-of-range measurement may be caused by drift and / or other changes in the process parameters of one or more manufacturing processes, resulting in the process no longer manufacturing acceptable devices (e.g., the measurement may exceed an acceptable threshold). Based on the determination of the measurement, one or more new or adjusted process parameters may be determined. The new or adjusted process parameters may be configured such that the manufacturing process again manufactures acceptable devices.

[0103]

[0118] For example, a new or adjusted process parameter may be one that adjusts a previously unacceptable measurement back into an acceptable range. The new or adjusted process parameter may be compared to an existing parameter for a given process. If there is a difference, that difference may be used to determine, for example, adjustments to the equipment used in device manufacturing (for example, parameter "x" needs to be increased / decreased / changed so that it matches a new or adjusted version of parameter "x" determined as part of Method 1400). In some embodiments, Method 1400 may include electronically adjusting the equipment (for example, based on the determined process parameter). Electronically adjusting the equipment may include, for example, sending electronic signals and / or other communications to the equipment that cause changes in the equipment. This electronic adjustment may include, for example, changing settings and / or other adjustments related to the equipment.

[0104]

[0119] Figure 15 is a diagram representing an exemplary 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 transmitting information and a processor PRO coupled to the bus BS for processing the information (or multiple processors similar to the processor PRO shown in Figures 3 and 6, and / or multiple processors similar thereto). The computer system CS also includes main memory MM coupled to the bus BS for storing information and instructions executed by the processor PRO (e.g., random access memory (RAM) or other dynamic storage devices). The main memory MM can also be used to store temporary variables and other intermediate information during the execution of instructions by the processor PRO. Furthermore, the computer system CS also includes read-only memory (ROM) ROM or other static storage devices coupled to the bus BS for storing static information and instructions to the processor PRO. A storage device SD, such as a magnetic disk or optical disk, is also provided, which is coupled to the bus BS to store information and instructions.

[0105]

[0120] The computer system CS may be coupled via a bus BS to a display DS, such as a flat panel or touch panel display or a cathode ray tube (CRT), for displaying information to the computer user. An input device ID, including alphanumeric keys and other keys, is coupled to the bus BS to transmit information and command selections to the processor PRO. Another type of user input device is a cursor controller CC, such as a mouse, trackball, or cursor directional keys, which transmits directional information and command selections to the processor PRO and controls the movement of a cursor on the display DS. This input device typically has two degrees of freedom in two axes, a first axis (e.g., x) and a second axis (e.g., y), allowing the device to determine its position on a plane. A touch panel (screen) display can also be used as an input device.

[0106]

[0121] In some embodiments, one or more operations described herein may be executed by a computer system CS in response to a processor PRO executing one or more sequences of one or more instructions contained in main memory MM. Such instructions may be read into main memory MM from another computer-readable medium, such as a storage device SD. By executing the sequence of instructions contained in main memory MM, the processor PRO performs the process steps (operations) described herein. One or more processors in a multiprocessing configuration may be employed to execute the sequence of instructions contained in main memory MM. In some embodiments, hardwired circuits may be used instead of or in combination with software instructions. Therefore, the description herein is not limited to any particular combination of hardware circuits and software.

[0107]

[0122] As used herein, the terms “computer-readable medium” or “machine-readable medium” mean any medium involved in providing instructions for execution to the processor PRO. Such mediums can take many forms and include, but are not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical or magnetic 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 the bus BS. Transmission media can also take the form of sound waves or light waves, including, for example, those generated during radio frequency (RF) and infrared (IR) data communications. Computer-readable media can be non-temporary, such as floppy disks, flexible disks, hard disks, magnetic tapes, and other magnetic media, CD-ROMs, DVDs, and other optical media, punch cards, paper tapes, and other physical media with hole patterns, RAM, PROMs, EPROMs, FLASH-EPROMs, and other memory chips or cartridges. Instructions can be recorded on non-temporary computer-readable media. When an instruction is executed by a computer, it can perform any of the operations described herein. Temporary computer-readable media may include, for example, carrier waves or other propagating electromagnetic signals.

[0108]

[0123] Various forms of computer-readable media may be involved in transmitting one or more sequences of one or more instructions for execution to the processor PRO. For example, the instructions may initially reside on a magnetic disk of a remote computer. The remote computer may load the instructions into its dynamic memory and transmit them via a telephone line using a modem. The local modem of the computer system CS can receive data on the telephone line and convert that data into an infrared signal using an infrared transmitter. An infrared detector coupled to the bus BS can receive the data transmitted as an infrared signal and place that data on the bus BS. The bus BS transmits this data to the main memory MM, from which the processor PRO retrieves and executes the instructions. The instructions received by the main memory MM may optionally be stored in the storage device SD before or after execution by the processor PRO.

[0109]

[0124] The computer system CS may include a communication interface CI coupled to a bus BS. The communication interface CI provides bidirectional data communication coupling to a network link NDL connected to a local network LAN. For example, the communication interface CI may be an Integrated Digital Telecommunications Network (ISDN) card or modem, which provides data communication connectivity to a corresponding type of telephone line. As another example, the communication interface CI may be a local area network (LAN) card, which provides data communication connectivity to a compatible LAN. Wireless links are also possible. In any of these embodiments, the communication interface CI transmits and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0110]

[0125] A network data link (NDL) typically provides data communication to other data devices over one or more networks. For example, a network data link (NDL) may provide a connection to a host computer (HC) over a local network (LAN). This may include data communication services provided over a global packet data communication network now commonly referred to as the "Internet" (INT). The local network (LAN) (Internet) may use electrical, electromagnetic, or optical signals to transmit digital data streams. These signals over various networks, as well as signals over a network data link (NDL) and over a communication interface (CI), transmit digital data exchanged with a computer system (CS) and are exemplary forms of carrier waves that carry information.

[0111]

[0126] A computer system CS can send messages and receive data, including program code, via (one or more) networks, network data links (NDL), and communication interfaces (CI). In the case of the Internet, a host computer HC can send request code for an application program via the Internet (INT), network data link (NDL), local network (LAN), and communication interface (CI). One application thus downloaded may provide, for example, all or part of the method described herein. The received code may be executed by the processor PRO upon receipt and / or executed after being stored in a storage device (SD) or other non-volatile storage. In this way, the computer system CS can obtain application code in carrier form.

[0112]

[0127] Various embodiments of the System and Method are disclosed in the following numbered list of clauses. Further features, characteristics, and exemplary technical solutions of the Disclosure are described below as clauses, which may be claimed in any combination of any of the clauses at the discretion of the party. 1. A metrology system comprising: a radiation sensor configured to generate a metrology signal, wherein the metrology signal is generated based on radiation received at different imaging positions on the radiation sensor; and an array of optical components configured to receive radiation of different diffraction orders from a substrate, change the angles of the different diffraction orders of the radiation, and guide the different diffraction orders of the radiation to different imaging positions on the radiation sensor. 2. The system described in Clause 1, wherein the array of optical components comprises four optical components, two of which are related to zero-order diffraction radiation and two of which are related to first-order diffraction radiation. 3. An array of optical components is a system described in any of the preceding clauses, including a lens array. 4. The system described in any of the preceding clauses, wherein each lens has a circular or square cross-sectional shape. 5. An array of optical components, including a spatial light modulator (SLM), as described in any of the preceding clauses. 6. The SLM is a system as described in any of the preceding clauses, which is transmissive or reflective, or has a transmissive or reflective portion. 7. The system according to any of the preceding clauses, comprising a liquid crystal, a digital micromirror device (DMD), and / or a pattern, configured to change the angle of different diffraction orders of radiation and to guide different diffraction orders of radiation to different imaging positions on a radiation sensor. 8. An array of optical components, including a metalens array, is a system as described in any of the preceding clauses. 9. The system according to any of the preceding clauses, further comprising one or more processors operably connected to a radiation sensor, the processors being configured to determine a metronome measurement based on a metronome signal. 10. Metrology measurements include alignment values, overlay values, focus values, and / or critical dimension values ​​related to the semiconductor manufacturing process performed on the substrate, as described in any of the preceding clauses. 11. The system according to any of the preceding clauses, wherein two optical components in an array of optical components are configured to create two zero-order images defocused in opposite directions at two different imaging positions on a radiation sensor. 12. The system according to any of the preceding clauses, further comprising one or more processors operably connected to a radiation sensor, the one or more processors configured to determine a focal position for imaging a substrate in the metrology system based on zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor. 13. The system according to any of the preceding clauses, wherein one or more processors are further configured to automatically adjust the position of the stage of the metrology system holding the substrate based on the focal position so that the subsequent image of the substrate is in focus. 14. The system according to any of the preceding clauses, wherein two optical components in an array of optical components include a microlens array, and each microlens in the microlens array is configured to form a focal spot on a radiation sensor, the position of which can be used to determine radiation wavefront aberration. 15. The system according to any of the preceding clauses, further comprising one or more processors operably connected to a radiation sensor, each processor configured to detect radiation wavefront aberrations based on the position of a focal spot relative to a reference position. 16. The system according to any of the preceding clauses, wherein the radiation sensor includes a sub-part configured to detect a focal spot, and the system further includes segmented mirrors configured to guide radiation from a microlens array to the sub-part of the radiation sensor. 17. The system according to any of the preceding clauses, wherein the microlens array is positioned in a different plane of the metrology system compared to the other optical components in the array of optical components, such that the radiation sensor is located at the focal plane of the microlens array and at the focal plane of the other optical components in the array of optical components. 18. The system according to any of the preceding clauses, further comprising a radiation source and one or more lenses, wherein the radiation source and one or more lenses are configured to generate radiation and guide the radiation onto a substrate. 19. The system described in any of the preceding clauses, wherein the substrate comprises a semiconductor wafer having one or more overlay targets configured to reflect radiation toward an array of optical components, and the sensor comprises a microdiffraction-based overlay camera related to overlay measurement. 20. The radiation sensor is a system as described in any of the preceding clauses, including a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS) system, and / or a photodiode array. 21. A metrology method comprising: using an array of optical components to receive radiation of different diffraction orders from a substrate, changing the angles of these radiation of different diffraction orders, and guiding these radiation of different diffraction orders to different imaging positions on a radiation sensor; and using the radiation sensor to generate a metrology signal based on the radiation received at the different imaging positions on the radiation sensor. 22. The method according to Clause 21, wherein the array of optical components comprises four optical components, two of which are related to zero-order diffraction radiation and two of which are related to first-order diffraction radiation. 23. An array of optical components, including a lens array, as described in any of the preceding clauses. 24. The method according to any of the preceding clauses, wherein each lens has a circular or square cross-sectional shape. 25. An array of optical components, including a spatial light modulator (SLM), as described in any of the preceding clauses. 26. The method according to any of the preceding clauses, wherein the SLM is transmissive or reflective, or has a transmissive or reflective portion. 27. The method according to any of the preceding clauses, wherein the SLM includes a liquid crystal, a digital micromirror device (DMD), and / or a pattern configured to change the angle of different diffraction orders of radiation and guide different diffraction orders of radiation to different imaging positions on a radiation sensor. 28. An array of optical components, including a metalens array, as described in any of the preceding clauses. 29. The method according to any of the preceding clauses, further comprising determining a metronome measurement based on a metronome signal by one or more processors operably connected to a radiation sensor. 30. Metrology measurements, including alignment values, overlay values, focus values, and / or critical dimension values ​​related to the semiconductor manufacturing process performed on the substrate, as described in any of the preceding clauses. 31. The method according to any of the preceding clauses, wherein two optical components in an array of optical components are configured to create two zero-order images defocused in opposite directions at two different imaging positions on a radiation sensor. 32. The method of any of the preceding clauses, further comprising determining a focal position for imaging a substrate based on zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor, using one or more processors operably connected to the radiation sensor. 33. The method according to any of the preceding clauses, wherein one or more processors are further configured to automatically adjust the position of a stage in a metrology system holding a substrate based on the focal position so that a subsequent image of the substrate is in focus. 34. The method according to any of the preceding clauses, wherein two optical components in an array of optical components include a microlens array, and each microlens in the microlens array is configured to form a focal spot on a radiation sensor, the position of which can be used to determine radiation wavefront aberration. 35. The method according to any of the preceding clauses, further comprising detecting radiation wavefront aberration based on the position of a focal spot relative to a reference position using one or more processors operably connected to a radiation sensor. 36. The method according to any of the preceding clauses, wherein the radiation sensor includes a sub-part configured to detect a focal spot, and further includes guiding radiation from a microlens array to the sub-part of the radiation sensor by a segmented mirror. 37. The method according to any of the preceding clauses, wherein the microlens array is positioned in a different plane from other optical components in the array of optical components, such that the radiation sensor is located at the focal plane of the microlens array and at the focal plane of other optical components in the array of optical components. 38. The method of any of the preceding clauses, further comprising generating radiation with a radiation source and inducing the radiation to a substrate. 39. The method according to any of the preceding clauses, wherein the substrate comprises a semiconductor wafer having one or more overlay targets configured to reflect radiation toward an array of optical components, and the sensor comprises a microdiffraction-based overlay camera related to overlay measurement. 40. The method according to any of the preceding clauses, wherein the radiation sensor includes a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS) and / or a photodiode array.

[0113]

[0128] The concepts disclosed herein can be associated with any common imaging system for imaging subwavelength features and may be particularly useful for new imaging techniques capable of generating even shorter wavelengths. New techniques already in use include EUV (extreme ultraviolet) and DUV lithography. DUV lithography can generate wavelengths up to 193 nm using ArF lasers, and further, 157 nm using fluorine lasers. EUV lithography can generate wavelengths in the 20–5 nm range, which is achieved by using a synchrotron or by generating photons in this range by irradiating a (solid or plasma) material with high-energy electrons.

[0114]

[0129] The concepts disclosed herein may be used for imaging on substrates such as silicon wafers, but it should be understood that the disclosed concepts may be used with any type of lithography imaging system (e.g., those used for imaging on substrates other than silicon wafers). Furthermore, combinations and partial combinations of the disclosed elements may constitute separate embodiments.

[0115]

[0130] The above description is intended as an example, not a limitation. Therefore, as will be apparent to those skilled in the art, modifications may be made as described herein without departing from the scope of the appended claims.

Claims

1. A radiation sensor configured to generate a metronome signal, wherein the metronome signal is generated based on radiation received at different imaging positions on the radiation sensor, An array of optical components configured to receive radiation of different diffraction orders from a substrate, change the angles of the radiation of the different diffraction orders, and guide the radiation of the different diffraction orders to the different imaging positions on the radiation sensor. Metrology systems, including...

2. The system according to claim 1, wherein the array of optical components comprises four optical components, two of which are related to zero-order diffraction radiation and two of which are related to first-order diffraction radiation.

3. The system according to claim 1 or 2, wherein the array of optical components includes a lens array.

4. The system according to claim 3, wherein each lens has a circular or square cross-sectional shape.

5. The system according to claim 1 or 2, wherein the array of optical components includes a spatial light modulator (SLM).

6. The system according to claim 5, wherein the SLM is transmissive or reflective, or has a transmissive or reflective portion.

7. The system according to claim 5 or 6, wherein the SLM includes a liquid crystal, a digital micromirror device (DMD), and / or a pattern configured to change the angle of the different diffraction orders of the radiation and to guide the different diffraction orders of the radiation to the different imaging positions on the radiation sensor.

8. The system according to claim 1 or 2, wherein the array of optical components includes a metalens array.

9. The system according to any one of claims 1 to 8, further comprising one or more processors operably connected to the radiation sensor and configured to determine a metronome measurement based on the metronome signal.

10. The system according to claim 9, wherein the metrologic measurement values ​​include alignment values, overlay values, focus values, and / or critical dimension values ​​related to a semiconductor manufacturing process performed on the substrate.

11. The system according to any one of claims 1 to 10, wherein two of the optical components in the array of optical components are configured to produce two zero-order images defocused in opposite directions at two different imaging positions on the radiation sensor.

12. The system according to claim 11, further comprising one or more processors operably connected to the radiation sensor and configured to determine a focal position for imaging the substrate in the metrology system based on the zero-order images defocused in the opposite direction at two different imaging positions on the radiation sensor.

13. The system according to claim 12, wherein one or more processors are further configured to automatically adjust the position of the stage of the metrology system holding the substrate based on the focal position so that a subsequent image of the substrate is in focus.

14. The system according to any one of claims 1 to 10, wherein two of the optical components in the array of optical components include a microlens array, each microlens in the microlens array is configured to form a focal spot on the radiation sensor, and the position of the focal spot can be used to determine radiation wavefront aberration.

15. The system according to claim 14, further comprising one or more processors operably connected to the radiation sensor and configured to detect the radiation wavefront aberration based on the position of the focal spot relative to a reference position.

Images