Optical component array replacement for metrology

Abstract

An optical component array replacement that simplifies a metrology system for imaging a substrate is described. A cheaper and optically relatively simple array of optical components replaces typical optical wedges for imaging and / or other metrology operations. In some embodiments, two of the optical components in the array are configured to create two relatively defocused 0-order images in two different imaging positions on the radiation sensor, which helps to determine the focus position without requiring a separate focus branch in the metrology system. In some embodiments, two of the optical components in the array include an array of microlenses, each microlens in the array of microlenses being configured to form a focal spot on the radiation sensor, the position of which can be used to determine the radiation wavefront aberration, without the need for a conventional wavefront aberration sensor.

Description

[0001] Cross-reference to related applications

[0002] This application claims priority to U.S. Application 63 / 452,422, filed on March 15, 2023, which is incorporated herein by reference in its entirety. Technical Field

[0003] This disclosure relates to an optical component array replacement for measurement. Background Technology

[0004] Photolithography projection apparatuses can be used, for example, in the fabrication of integrated circuits (ICs). Patterning apparatus (e.g., a mask) can include or provide a pattern (“design layout”) corresponding to the various layers of the IC, and this pattern can be transferred onto target portions (e.g., comprising one or more dies) on a substrate (e.g., a silicon wafer) coated with a radiation-sensitive material (“resist”) by methods such as irradiating target portions with the pattern on the patterning apparatus. Typically, a single substrate comprises multiple adjacent target portions, onto which the pattern is sequentially transferred by the photolithography projection apparatus, one target portion at a time. In one type of photolithography projection apparatus, the entire pattern on the patterning apparatus is transferred onto a single target portion in one operation. This type of apparatus is generally referred to as a stepper. In an alternative apparatus, generally referred to as a step-scan apparatus, the projection beam scans along a given reference direction (“scan” direction) on the patterning apparatus while the substrate moves synchronously parallel to or antiparallel to that reference direction. Different portions of the pattern on the patterning apparatus are progressively transferred onto a single target portion.

[0005] Before a pattern is transferred from a patterning device to a substrate, the substrate may undergo various processes such as primer coating, resist coating, and soft baking. After exposure, the substrate can undergo other processes (“post-exposure processes”) such as post-exposure baking (PEB), development, hard baking, and measurement / inspection of the transferred pattern. This array of processes is used as the basis for manufacturing the individual layers of a device (e.g., an IC). The substrate can then undergo various processes such as etching, ion implantation (doping), metallization, oxidation, deposition, chemical mechanical polishing, etc., all of which are designed to complete the individual layers of the device. If several layers are required in the device, the entire process or its variations are repeated for each layer. Ultimately, the device will exist in each target portion on the substrate. These devices are then separated from each other using techniques such as dicing or sawing, allowing the individual devices to be mounted on a carrier, connected to pins, etc. This device manufacturing process can be viewed as a patterning process.

[0006] Photolithography is a central step in the manufacturing of devices such as integrated circuits (ICs), in which patterns formed on a substrate define the functional elements of the device, such as microprocessors and memory chips. Similar photolithography techniques are also used in the fabrication of flat panel displays, microelectromechanical systems (MEMS), and other devices.

[0007] As semiconductor manufacturing processes continue to advance, the size of functional components has been continuously reduced, while the number of functional components (such as transistors) in each device has been steadily increasing for decades, following a trend often referred to as "Moore's Law." At the current level of technology, the layers of a device are fabricated using a photolithography projection apparatus, which uses irradiation from a deep ultraviolet light source to project a design layout onto a substrate, thereby creating individual functional components with dimensions well below 100 nm (i.e., less than half the wavelength of radiation from the irradiation source, such as a 193 nm source).

[0008] According to the resolution formula CD = k1 × λ / NA, the process of printing features smaller than the classical resolution limit of a photolithography projection apparatus is generally referred to as low-k1 lithography, where λ is the wavelength of the radiation used (currently mostly 248 nm or 193 nm), NA is the numerical aperture of the projection optics in the photolithography projection apparatus, CD is the "critical size," typically the smallest feature size that can be printed, and k1 is an empirical resolution factor. Generally, the smaller k1 is, the more difficult it is to reproduce patterns on the substrate that are similar in shape and size to those planned by the designer to achieve specific electrical functionality and performance. To overcome these difficulties, complex fine-tuning steps are applied to the photolithography projection apparatus, design layout, or patterning equipment. These include, but are not limited to, optimization of NA and optical coherence settings, custom illumination schemes, the use of phase-shifting patterning equipment, optical proximity correction (OPC, sometimes also called "optical and process correction") in the design layout, or other methods generally defined as "resolution enhancement techniques" (RET). Summary of the Invention

[0009] An optical component array replacement for a simplified metrology system used for substrate imaging is described. An inexpensive and optically relatively simple optical component array replaces the typical optical wedge used for imaging and / or other metrological operations. In some embodiments, two optical components in the array are configured to create two relatively defocused 0th-order images at two different imaging locations on a radiation sensor, which helps determine the focal point location without requiring a separate focusing branch in the metrology system. In some embodiments, the two optical components in the array include a microlens array, each microlens being configured to form a focal spot on the radiation sensor, the location of which can be used to determine radiation wavefront aberrations without requiring a conventional wavefront aberration sensor.

[0010] According to an embodiment, a measurement system is provided. The measurement system includes a radiation sensor configured to generate measurement signals based on radiation received at different imaging positions on the radiation sensor. The measurement system includes 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 toward different imaging positions on the radiation sensor.

[0011] In some embodiments, the optical component array includes four optical components, two of which are associated with 0 diffraction order radiation and two of which are associated with 1 diffraction order radiation.

[0012] In some embodiments, the optical component array includes a lens array. In some embodiments, each lens has a circular or square cross-sectional shape.

[0013] In some embodiments, the optical component array 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, a digital micromirror device (DMD), and / or a pattern configured to change the angles of different diffraction orders of radiation and to guide the different diffraction orders of radiation toward different imaging positions on a radiation sensor.

[0014] In some embodiments, the optical component array includes a superlens array.

[0015] In some embodiments, the system includes one or more processors operatively connected to a radiation sensor and configured to determine measurement values ​​based on measurement signals. In some embodiments, the measurement values ​​include alignment values, overlay values, focal point values, and / or critical dimension values ​​associated with a semiconductor manufacturing process performed on the substrate.

[0016] In some embodiments, two optical components in the optical component array are configured to create two relatively defocused 0th-order images at two different imaging positions on the radiation sensor. In some embodiments, one or more processors are operatively connected to the radiation sensor and configured to determine a focal position for imaging the substrate with the measurement system based on the relatively defocused 0th-order images at the two different imaging positions on the radiation sensor. In some embodiments, the one or more processors are also configured to automatically adjust the position of the measurement system's substrate-holding platform based on the focal position, such that subsequent images of the substrate are in focus.

[0017] In some embodiments, two optical components in the optical component array include a microlens array, each microlens being configured to form a focal spot on the radiation sensor, the position of which can be used to determine radiation wavefront aberrations. In some embodiments, one or more processors are operatively connected to the radiation sensor and configured to detect radiation wavefront aberrations based on the position of the focal spot relative to a reference position.

[0018] In some embodiments, the radiation sensor includes a sub-section configured to sense a focal spot, and the system further includes a segmented mirror configured to direct radiation from the microlens array to the sub-section of the radiation sensor. In some embodiments, the microlens array is positioned in a different plane of the measurement system than other optical components in the optical component array, such that the radiation sensor is located at the focal plane of the microlens array and the other optical components in the optical component array.

[0019] 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 direct the radiation toward a substrate.

[0020] 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 micro-diffraction-based overlay camera associated with the overlay measurement.

[0021] In some embodiments, the radiation sensor includes a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS) array, and / or a photodiode array.

[0022] According to another embodiment, a measurement method including one or more of the above operations is provided. Attached Figure Description

[0023] The above aspects, as well as other aspects and features, will become apparent to those skilled in the art when examining the following description of specific embodiments in conjunction with the accompanying drawings.

[0024] Figure 1 A photolithography apparatus according to an embodiment is schematically depicted.

[0025] Figure 2 An embodiment of a photolithography unit or cluster according to an embodiment is schematically depicted.

[0026] Figure 3 An example inspection system according to an embodiment is schematically depicted.

[0027] Figure 4 An example measurement technique according to an embodiment is schematically depicted.

[0028] Figure 5 The diagram illustrates the relationship between the radiation spot and the measurement target of the inspection system according to an embodiment.

[0029] Figure 6 The figure illustrates a measurement system according to an embodiment.

[0030] Figure 7 The illustration shows an optical element according to an embodiment, including an optical wedge, a lens, a sensor, an illumination pupil, a detection pupil, and an example field image.

[0031] Figure 8 The illustration shows a simplified version according to an embodiment. Figure 6 The optical component array replacement of the system shown (for) Figure 7 (The wedge and one or more lenses shown).

[0032] Figure 9 The illustration shows a diagram from an embodiment of the invention. Figure 8 Two optical components in the optical component array (located in quadrants Q1 and Q3 in this example) are configured to create two relatively defocused 0th-order images at two different imaging positions on the radiation sensor for focus determination.

[0033] Figure 10 The illustration shows microlenses in a microlens array according to an embodiment, configured to form focal spots on a radiation sensor, the positions of which can be used to determine radiation wavefront aberrations.

[0034] Figure 11 The illustration also shows microlenses in a microlens array according to an embodiment, configured to form focal spots on a radiation sensor, the positions of which can be used to determine radiation wavefront aberrations, but in conjunction with... Figure 8 and 9 In the context of similar optical component arrays shown.

[0035] Figure 12 The illustration shows a diagram from an embodiment of the invention. Figure 11 The focal plane of the (multiple) microlens array may differ from the focal plane of the radiation spots from other optical components in the optical component array (located in quadrants Q2 and Q3 in this example).

[0036] Figure 13 An embodiment of the measurement system according to the embodiments is illustrated, wherein the radiation sensor includes a sub-section configured to sense a focal spot, and the optical elements of the measurement system include a segmented mirror (and / or similar functional components) configured to guide radiation from a microlens array to the sub-section of the radiation sensor.

[0037] Figure 14 The figure illustrates a measurement method according to an embodiment.

[0038] Figure 15This is a block diagram of an example computer system according to an embodiment. Detailed Implementation

[0039] In semiconductor device manufacturing, metrology operations typically involve measuring measurement markers (or multiple markers) and / or other targets within the semiconductor device's structural layers. Measurements are usually performed by irradiating the measurement markers with radiation and comparing the characteristics of the radiation reflected from the markers at different diffraction orders. This technique is used to measure overlay, alignment, and / or other parameters.

[0040] Many metrology systems include optical wedges configured to direct radiation of different diffraction orders to specific locations on a radiation sensor, and separate focusing branches (e.g., part of the metrology system, including radiation sources, several lenses, and many other optical components) to determine the focal position for imaging a substrate, wavefront aberration sensor, and / or other components. These systems are bulky, complex, and expensive. For example, the cost of optical wedges and the physical system space required to implement them are high compared to other optical components. These systems require additional components (such as additional beam splitters) to integrate the focusing branch with the rest of the metrology system, which reduces the radiation throughput of the central sensor. Focal position determination in such systems is not continuous because the radiation used to determine the focal position propagates along at least a portion of the same optical path as the radiation ultimately used for metrological measurements. This means that the metrology system switches back and forth between a focal position determination mode where the radiation source and optics are "on" in the focusing branch and a metrological image acquisition mode where the radiation source and optics are "off" in the focusing branch. The focal gap between these modes can lead to overlay errors due to defocusing and / or other issues. Furthermore, different orders of diffracted light from the measurement target on the substrate have different focal positions based on the objective wavefront error, which current measurement systems do not take into account.

[0041] An optical component array replacement for a measurement system used for measurement operations, including substrate imaging, is described. Advantageously, an inexpensive and optically relatively simple optical component array replaces the typical optical wedge used for imaging and / or other measurement operations. In some embodiments, two optical components in the array are configured to create two relatively defocused 0th-order images at two different imaging locations on a radiation sensor, which helps determine the focal point location without requiring a separate focusing branch in the measurement system. In some embodiments, the two optical components in the array comprise a microlens array, each microlens being configured to form a focal spot on the radiation sensor, the location of which can be used to determine radiation wavefront aberrations without requiring a conventional wavefront aberration sensor.

[0042] The following description, in brief, pertains to semiconductor device fabrication and patterning processes. The following paragraphs also describe several components of systems and / or methods used for semiconductor device measurement. For example, these systems and methods can be used to measure overlay, alignment, and other operations in semiconductor device fabrication processes.

[0043] While specific references may be made herein to measurements of overlay, alignment, or other parameters, and to the fabrication of integrated circuits (ICs) for semiconductor devices, it should be understood that the description herein has many other possible applications. For example, it can be used for the fabrication of integrated optical systems, for guiding and detecting patterns for magnetic domain memories, liquid crystal display panels, thin-film magnetic heads, etc. Those skilled in the art will understand that, in the context of such alternative applications, any use of the terms “mask,” “wafer,” or “die” herein should be considered interchangeable with the more general terms “mask,” “substrate,” and “target portion,” respectively.

[0044] The term "projection optics" as used herein should be interpreted broadly to encompass various types of optical systems, including, for example, refractive optics, reflective optics, aperture and reflective-refractive optics. The term "projection optics" may also include components operating according to any of these design types to guide, shape, or control the projected radiation beam, either jointly or individually. The term "projection optics" can include any optical component in a lithography projection apparatus, regardless of its location in the optical path of the lithography projection apparatus. Projection optics can include optical components for shaping, modulating, and / or projecting radiation from a source before it passes through the patterning apparatus and / or for shaping, modulating, and / or projecting radiation after it has passed through the patterning apparatus. Projection optics typically do not include the source and the patterning apparatus.

[0045] Figure 1An embodiment of a photolithography apparatus LA is schematically depicted. The apparatus includes: an irradiation system (irradiator) IL configured to modulate a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation); a support structure (e.g., a mask stage) MT configured to support a patterning apparatus (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning apparatus according to certain parameters; a substrate stage (e.g., a wafer stage) WT (e.g., WTa, WTb, or both) configured to hold a substrate (e.g., a resist-coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate according to certain parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted by the radiation beam B by the patterning apparatus MA onto a target portion C (e.g., comprising one or more dies and commonly referred to as a field) of the substrate W. The projection system is supported on a reference frame RF. As depicted, the apparatus is transmissive (e.g., employing a transmissive mask). Alternatively, the device can be reflective (e.g., using a programmable array of mirrors or a reflective mask).

[0046] The irradiator IL receives a radiation beam from the radiation source SO. The source and the lithography apparatus can be separate entities, for example, when the source is an excimer laser. In this case, the source is not considered part of forming the lithography apparatus, and the radiation beam is delivered from the source SO to the irradiator IL by means of a beam delivery system BD, which includes, for example, suitable directional mirrors and / or beam expanders. In other cases, the source can be an integral part of the apparatus, for example, when the source is a mercury lamp. The source SO, the irradiator IL, and (if necessary) the beam delivery system BD can be referred to as the radiation system.

[0047] The illuminator IL can modify the intensity distribution of the beam. The illuminator can be arranged to limit the radial range of the radiation beam such that the intensity distribution is non-zero within an annular region in the pupil plane of the illuminator IL. Additionally or alternatively, the illuminator IL can be operable to limit the beam distribution in the pupil plane such that the intensity distribution in multiple equidistant sectors within the pupil plane is non-zero. The intensity distribution of the radiation beam in the pupil plane of the illuminator IL can be referred to as the illumination mode.

[0048] An illuminator IL may include an adjuster AD configured to adjust the (angular / spatial) intensity distribution of a beam. Typically, at least the outer and / or inner radial ranges of the intensity distribution in the pupil plane of the illuminator (generally referred to as σ_outer and σ_inner, respectively) can be adjusted. The illuminator IL may be operable to change the angular distribution of the beam. For example, the illuminator may be operable to change the number and angular range of sectors in the pupil plane, where the intensity distribution is not zero. Different illumination modes can be achieved by adjusting the intensity distribution of the beam in the pupil plane of the illuminator. For example, by limiting the radial and angular ranges of the intensity distribution in the pupil plane of the illuminator IL, the intensity distribution can have a multipole distribution, such as, for example, a dipole, tetrapole, or hexapole distribution. For example, a desired illumination mode can be obtained by inserting an optics providing that illumination mode into the illuminator IL or by using a spatial light modulator.

[0049] The illuminator IL is operable to change the polarization of the beam and operable to adjust the polarization using an adjuster AD. The polarization state of the radiation beam in the pupil plane of the illuminator IL can be referred to as the polarization mode. Using different polarization modes allows for greater contrast in the image formed on the substrate W. The radiation beam can be unpolarized. Alternatively, the illuminator can be arranged as a linearly polarized radiation beam. The polarization direction of the radiation beam can vary in the pupil plane of the illuminator IL. The polarization direction of the radiation may differ in different regions of the pupil plane of the illuminator IL. The polarization state of the radiation can be selected according to the illuminator mode. For a multi-pole illuminator mode, the polarization of each pole of the radiation beam can generally be perpendicular to the position vector of that pole in the pupil plane of the illuminator IL. For example, for a dipole illuminator mode, the radiation can be linearly polarized in a direction substantially perpendicular to the line bisecting the two opposing sectors of the dipole. The radiation beam can be polarized in one of two different orthogonal directions, which can be referred to as the X-polarization state and the Y-polarization state. For a quadrupole illuminator mode, the radiation in the sector of each pole can be linearly polarized in a direction substantially perpendicular to the line bisecting that sector. This polarization mode can be called XY polarization. Similarly, for the hexapole illumination mode, the radiation in the sector of each pole can be linearly polarized in a direction substantially perpendicular to the line bisecting the sector. This polarization mode can be called TE polarization.

[0050] In addition, the irradiator IL typically includes various other components, such as the integrator IN and the convergent CO. The irradiation system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for guiding, shaping, or controlling radiation. Therefore, the irradiator provides a conditioned radiation beam B with desired uniformity and intensity distribution in its cross-section.

[0051] The support structure (MT) supports the patterning apparatus in a manner dependent on the orientation of the patterning apparatus, the design of the lithography apparatus, and other conditions such as whether the patterning apparatus is held in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning apparatus. The support structure can be a frame or a stage, which may be fixed or movable as needed. The support structure ensures that the patterning apparatus is positioned, for example, relative to the projection system. Any use of the terms "mask" or "mask" herein is to be considered synonymous with the more general term "patterning apparatus".

[0052] As used herein, the term "patterning apparatus" should be broadly interpreted to refer to any apparatus that can be used to impart a pattern in a target portion of a substrate. In embodiments, a patterning apparatus is any apparatus that can be used to impart a pattern of radiation beams in its cross-section to create a pattern in a target portion of the substrate. It should be noted that the pattern imparted by the radiation beams may not correspond exactly to the desired pattern in the target portion of the substrate, for example, if the pattern includes phase-shifting features or so-called auxiliary features. Typically, the pattern imparted by the radiation beams will correspond to a specific functional layer in the apparatus (such as an integrated circuit) created in the target portion of the apparatus.

[0053] Patterning apparatus can be transmissive or reflective. Examples of patterning apparatus include masks, programmable mirror arrays, and programmable LCD panels. Masks are well-known in photolithography and include mask types such as binary mask types, alternating phase-shift mask types, attenuation phase-shift mask types, and various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect incoming radiation beams in different directions. The tilted mirrors impart a pattern to the radiation beam reflected by the mirror matrix.

[0054] The term “projection system” should be interpreted broadly to encompass any type of projection system, including refractive, reflective, reflective-refractive, magnetic, electromagnetic, and electrostatic optical systems or any combination thereof, as appropriate, depending on the exposure radiation or other factors used, such as the use of immersion or vacuum. Any use of the term “projection lens” in this document may be considered synonymous with the more general term “projection system.”

[0055] The projection system PS may include multiple optical (e.g., lens) elements and may also include an adjustment mechanism configured to adjust one or more optical elements to correct for aberrations (phase changes across the pupil plane throughout the field). To achieve this, the adjustment mechanism may be operable to manipulate one or more optical (e.g., lens) elements within the projection system PS in one or more different ways. The projection system may have a coordinate system in which its optical axis extends in the z-direction. The adjustment mechanism may be operable to perform any combination of: displacing one or more optical elements; tilting one or more optical elements; and / or deforming one or more optical elements. Displacement of the optical elements may be in any direction (x, y, z, or a combination thereof). Although rotation about the z-axis can be used for non-rotationally symmetric aspherical optical elements, tilting of the optical element by rotation about axes in the x and / or y directions typically occurs outside the plane perpendicular to the optical axis. Deformation of the optical elements may include low-frequency shapes (e.g., astigmatism) and / or high-frequency shapes (e.g., free aspherical). Deformation of an optical element 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 areas of the optical element using one or more heating elements. Typically, the projection system PS may not be adjustable to correct apodization (transmission variations on the pupil plane). When designing a patterning apparatus (e.g., a mask) MA for a lithography device LA, the transmission pattern of the projection system PS can be used. Using computational lithography techniques, the patterning apparatus MA can be designed to at least partially correct apodization.

[0056] Photolithography apparatuses can be of the type having two (dual-platform) or more stages (e.g., two or more substrate stages WTa, WTb, two or more patterning equipment stages, substrate stages WTa and stages WTb located below the projection system without dedicated substrates for, for example, facilitating measurement and / or cleaning). In such "multi-platform" machines, additional stages can be used in parallel, or preparatory steps can be performed on one or more stages while one or more other stages are being used for exposure. For example, alignment measurements using alignment sensors AS and / or level (height, tilt, etc.) measurements using level sensors LS can be performed.

[0057] Photolithography apparatuses can also be of the type in which at least a portion of the substrate can be covered with a liquid (e.g., water) having a relatively high refractive index to fill the space between the projection system and the substrate. Immersion liquid can also be applied to other spaces in a photolithography apparatus, such as the space between a patterning device and the projection system. Immersion techniques are well known in the art to increase the numerical aperture of the projection system. As used herein, the term “immersion” does not mean that structures such as the substrate must be submerged in the liquid; rather, immersion simply means that the liquid is located between the projection system and the substrate during exposure.

[0058] In the operation of a photolithography apparatus, a radiation beam is regulated and provided by an illumination system IL. The radiation beam B is incident on a patterning apparatus (e.g., a mask) MA and patterned by the patterning apparatus MA, which is held on a support structure (e.g., a mask stage) MT. After traversing the patterning apparatus MA, the radiation beam B passes through a projection system PS, which focuses the beam onto a target portion C of a substrate W. The substrate stage WT can be precisely moved, for example, to position different target portions C within the path of the radiation beam B, by means of a second positioner PW and a position sensor IF (e.g., an interferometer, linear encoder, 2D encoder, or capacitive sensor). Similarly, for example, after mechanical retrieval from a mask library or during scanning, a first positioner PM and another position sensor (not in use) are also moved. Figure 1 The patterning apparatus MA (as explicitly depicted) can be used to accurately position itself relative to the path of the radiation beam B. Typically, movement of the support structure MT can be achieved using a long-stroke module (coarse positioning) and a short-stroke module (fine positioning) forming part of the first positioner PM. Similarly, movement of the substrate stage WT can be achieved using a long-stroke module and a short-stroke module forming part of the second positioner PW. In the case of a stepper (opposite to the scanner), the support structure MT can be connected only to the short-stroke actuator, or it can be fixed. The patterning apparatus MA and the substrate W can be aligned using patterning apparatus alignment marks M1, M2 and substrate alignment marks P1, P2. Although the illustrated substrate alignment marks occupy dedicated target portions, they can be located in the space between the target portions (these are called scribing alignment marks). Similarly, when more than one die is provided on the patterning apparatus MA, the patterning apparatus alignment marks can be located between the dies.

[0059] The described apparatus can be used in at least one of the following modes. In stepping mode, the support structure MT and substrate stage WT remain substantially stationary while a pattern with an applied radiation beam is projected onto the target portion C in a single exposure (i.e., a single static exposure). The substrate stage WT is then displaced in the X and / or Y directions, allowing different target portions C to be exposed. In stepping mode, the maximum size of the exposure field is limited to the size of the target portion C imaged in a single static exposure. In scanning mode, the support structure MT and substrate stage WT are scanned synchronously while the pattern with an applied radiation beam is projected onto the target portion C (i.e., a single dynamic exposure). The velocity and direction of the substrate stage WT relative to the support structure MT can be determined by the (reduced) magnification and image inversion characteristics of the projection system PS. In scanning mode, the maximum size of the exposure field limits the width of the target portion (in the non-scanning direction) in a single dynamic exposure, while the length of the scanning motion determines the height of the target portion (in the scanning direction). In another mode, the support structure MT remains substantially stationary while the pattern with an applied radiation beam is projected onto the target portion C, thereby maintaining the programmable pattern forming apparatus, and the substrate stage WT is moved or scanned. In this mode, a pulsed radiation source is typically employed, and the programmable patterning apparatus is updated as needed, either after each movement of the substrate stage WT or between consecutive radiation pulses during scanning. This operating mode can be readily applied to maskless lithography, which utilizes programmable patterning apparatus (such as programmable mirror arrays of the type mentioned above).

[0060] Combinations and / or variations of the above usage patterns, or entirely different usage patterns, may also be adopted.

[0061] The substrate can be processed before or after exposure, for example in a track (a tool typically used to apply a resist layer to the substrate and develop the exposed resist) or in a measurement or inspection tool. Where applicable, this disclosure can be applied to such and other substrate processing tools. Furthermore, the substrate can be processed more than once, for example to create a multilayer IC, such that the term substrate as used herein can also refer to a substrate that already includes multiple processed layers.

[0062] The terms “radiation” and “beam” used in this article in relation to lithography encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., wavelengths of 365, 248, 193, 157, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., wavelengths in the range of 5 to 20 nm), as well as particle beams, such as ion beams or electron beams.

[0063] Various patterns on or provided by a patterning apparatus can have different process windows, i.e., a space of processing variables in which the pattern will be generated within a specification. Examples of pattern specifications associated with potential system defects include checking for necking, line backing, line thinning, CD, edge placement, overlay, resistance to top loss, resistance to undercut, and / or bridging. The process window of a pattern or its region on a patterning apparatus can be obtained by merging (e.g., overlaying) 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 some individual patterns. In other words, these individual patterns limit the process window of the set of patterns.

[0064] like Figure 2 As shown, a lithography apparatus LA can form part of a lithography unit LC, sometimes referred to as a lithography unit or cluster, which also includes apparatus for performing pre- and post-exposure processes on the substrate. Typically, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the post-exposure resist, one or more cooling plates CH, and / or one or more baking plates BK. A substrate handler or robot RO picks up one or more substrates from input / output ports I / O1, I / O2, moves them between different process units, and then delivers them to the lithography apparatus's feed stage LB. These apparatuses, generally referred to collectively as tracks, are controlled by a track control unit TCU, which in turn is controlled by a monitoring system SCS, which in turn controls the lithography apparatus via the lithography control unit LACU. Therefore, different apparatuses can be operated to maximize throughput and processing efficiency.

[0065] To ensure that the substrate exposed by the photolithography apparatus is correctly and consistently exposed and / or to monitor a portion of a patterning process (e.g., an equipment manufacturing process) that includes at least one pattern transfer step (e.g., an optical lithography step), it is desirable to inspect the substrate or other object to measure or determine one or more properties, such as alignment, overlay (e.g., which may be provided separately to layers via, for example, a dual-patterning process), line thickness, critical dimension (CD), focus offset, material properties, etc. Therefore, the manufacturing facility where the photolithography unit (LC) is located typically also includes a metrology system that measures some or all of the substrate W (which has been processed in the photolithography unit) Figure 1 The measurement system can be part of the lithography unit (LC), for example, it can be a lithography apparatus (LA) such as an alignment sensor (AS). Figure 1 Part of ))

[0066] One or more measurement parameters may include, for example, alignment, overlay between successive layers formed in or on a patterned substrate, critical dimensions (CD) (e.g., critical linewidth) of features formed in or on a patterned substrate, focal point or focal point error of an optical lithography step, dose or dose error of an optical lithography step, optical aberration of an optical lithography step, etc. The measurement is typically performed against one or more dedicated measurement targets provided on the substrate. The measurement may be performed after resist development but before etching, after etching, after deposition, and / or at other times.

[0067] Various techniques exist for measuring structures formed in patterning processes, including the use of scanning electron microscopy, image-based measurement tools, and / or various specialized instruments. One rapid and non-invasive form of specialized metrology involves directing a radiation beam onto a target on a 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. Traditionally, this can be referred to as diffraction-based metrology. Applications of this diffraction-based metrology include measurements of overlay, alignment, etc. For example, overlay and / or alignment can be measured by comparing portions of diffraction spectra (e.g., comparing different diffraction orders in the diffraction spectrum of a periodic grating).

[0068] Therefore, in device fabrication processes (such as patterning or photolithography), substrates or other objects can be measured during or after the process. Measurements can determine whether a particular substrate has defects, establish adjustments to the process and the apparatus used in the process (e.g., aligning two layers on a substrate or aligning a patterning apparatus with a substrate), measure the performance of the process and apparatus, or be used for other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements, such as the ASML YieldStar metrology tool and the ASML SMASH metrology system), mechanical measurements (e.g., profiling using a stylus, atomic force microscopy (AFM), and / or non-optical imaging (e.g., scanning electron microscopy (SEM)).

[0069] Measurement results can be provided directly or indirectly to the monitoring system (SCS). If an error is detected, adjustments can be made to the subsequent exposure of substrates (especially if the inspection can be completed quickly enough that one or more other substrates in the batch still need to be exposed) and / or subsequent exposure of the exposed substrates. Furthermore, already exposed substrates can be stripped and reworked to increase yield, or discarded, thus avoiding further processing of known faulty substrates. In cases where only some target portions of the substrate are faulty, further exposure can be performed only on those target portions that meet specifications. Other manufacturing process adjustments are also under consideration.

[0070] Measurement systems can be used to determine one or more properties of a substrate structure, particularly how one or more properties vary between different substrate structures or between different layers of the same substrate structure. Measurement systems can be integrated into a photolithography apparatus (LA) or a photolithography unit (LC), or they can be stand-alone devices.

[0071] To enable measurement, one or more targets are typically provided specifically on a substrate. Typically, the targets are specially designed and may include periodic structures. For example, a target on the substrate may include one or more 1D periodic structures (e.g., geometric features such as gratings) that are printed such that, after development, the periodic structure features are formed by solid resist lines. As another example, a target may include one or more 2D periodic structures (e.g., gratings) that are printed such that, after development, one or more periodic structures are formed by solid resist pillars or vias in the resist. Alternatively, the gratings, pillars, or vias may be etched into the substrate (e.g., etched into one or more layers on the substrate).

[0072] Figure 3 An example measurement (inspection) system 10 is depicted that can be used for overlay detection, alignment, and / or performing other measurement operations. It includes a radiation or irradiation source 2 that projects or otherwise irradiates radiation onto a substrate W (e.g., which may typically include measurement marks). The redirected radiation is passed to sensors such as a spectrometer detector 4 and / or other sensors that measure the spectrum (intensity as a function of wavelength) of specularly reflected and / or diffracted radiation, such as, for example... Figure 4 The graph on the left is shown. The sensor can generate a measurement signal, conveying measurement data indicating the properties of reflected radiation. From this data, the structure or profile of the detected spectrum can be reconstructed by one or more processors (PROs), a generalized example of which is... Figure 4 As shown, it can be reconstructed through other operations.

[0073] and Figure 1 Similar to the LA lithography apparatus in lithography, it can provide one or more substrate stages ( Figure 4 (Not shown in the image) to hold the substrate W during measurement operations. One or more substrate stages may be in the form of... Figure 1The substrate stages WT (WTa or WTb or both) are similar or identical. In the example where the inspection system 10 is integrated with the lithography apparatus, they can even be the same substrate stages. Coarse and fine positioners can be provided and configured to accurately position the substrate with respect to the measurement optics. Various sensors and actuators are provided, for example, to obtain the position of the target portion of the structure (e.g., a measurement mark) and to position it under the objective lens. Typically, many measurements will be performed on the target portion of the structure at different locations on the substrate W. The substrate support can be moved in the X and Y directions to obtain different targets and can be moved in the Z direction to obtain the desired position of the target portion relative to the focus of the optical system. It is convenient to think of and describe the operation as if the objective lens were placed in different positions relative to the substrate, for example, when the optical system may actually remain substantially stationary (typically in the X and Y directions, but also possibly in the Z direction) and the substrate moves. As long as the relative positions of the substrate and the optical system are correct, it does not matter in principle which one of them is moving, or both are moving, or a combination of a part of the optical system moving (e.g. in the Z and / or tilt directions) while the rest of the optical system is stationary and the substrate is moving (e.g. in the X and Y directions, but optionally in the Z and / or tilt directions).

[0074] For typical metrological measurements, the target 30 on the substrate W can be a 1D grating, which is printed such that, after development, the grating strips are formed from solid resist lines (e.g., which may be covered by a deposited layer) and / or other materials. Alternatively, the target 30 can be a 2D grating, which is printed such that, after development, the grating is formed from solid resist pillars and / or other features in the resist.

[0075] Gates, pillars, vias, and / or other features may be etched into or on the substrate (e.g., etched into one or more layers on the substrate), deposited on the substrate, covered by a deposition layer, and / or have other properties. The target (partial) 30 (e.g., gates, pillars, vias, etc.) is sensitive to processing variations in the patterning process (e.g., optical aberrations, focus variations, dose variations, etc. in the photolithography projection apparatus (such as a projection system), causing process variations to manifest 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 as a basis for making actual adjustments.

[0076] For example, measurement data from target 30 can indicate overlay of semiconductor device layers. The measurement data from target 30 can be used (e.g., by one or more processors PRO and / or other processors) to determine one or more semiconductor device fabrication process parameters based on the overlay, and to determine adjustments for a semiconductor device fabrication apparatus based on one or more determined semiconductor device fabrication process parameters. In some embodiments, this may include, for example, platform position adjustments, or it may include determining adjustments for mask design, measurement target design, semiconductor device design, radiation intensity, radiation incident angle, radiation wavelength, pupil size and / or shape, resist material, and / or other process parameters.

[0077] Figure 5 The illustration shows a plan view of a typical target (e.g., a measurement marker) 30 and Figure 4 The typical range of the radiation spot S in the system. Typically, to obtain a diffraction spectrum unaffected by surrounding structures, in embodiments, the target 30 is a periodic structure (e.g., a grating) larger than the width (e.g., diameter) of the radiation spot S. The width of the spot S can be smaller than the width and length of the target. In other words, the target is 'under-filled' by illumination, and the diffraction signal is substantially unaffected by any signals from product features or other external sources. For example, the illumination arrangement can be configured to provide uniform intensity of illumination on the back focal plane of the objective lens. Alternatively, illumination can be restricted to on-axis or off-axis directions, for example, by including an aperture in the illumination path.

[0078] Figure 6 A measurement system 600 is illustrated. Measurement operations performed by the system 600 may include imaging one or more measurement targets 30. For example, a target 30 may include one or more measurement markers, such as diffraction grating targets, collectively referred to as targets 30, formed in a substrate 602 (such as a semiconductor wafer). A target 30 may include one or more structures in a patterned substrate capable of providing diffraction signals. One or more targets 30 may be included in a substrate layer, for example, in a semiconductor device structure. In some embodiments, the feature includes geometric features such as 1D or 2D features and / or other geometric features. By way of several non-limiting examples, the feature may include gratings, lines, edges, lines and / or edges with a series of fine pitches, and / or other features.

[0079] System 600 includes a radiation sensor 604 configured to receive radiation from target 30 and generate a measurement signal. The radiation can be used to obtain an image from the measurement target 30 and / or for other purposes. The radiation can 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 direct the radiation toward sensor 604. Optical element 606 includes an array of optical components 605, as described below. System 600 includes one or more processors PRO operatively connected to the radiation sensor 604 and configured to: determine measurement values ​​based on the measurement signal; determine a focal position for imaging the substrate; detect wavefront aberrations; and / or perform other operations.

[0080] System 600 can be with Figure 3 The system 10 shown is similar to and / or identical to that shown. Figure 6 In this diagram, additional details are illustrated for system 600 compared to system 10. In some embodiments, system 600 may form the above-described configuration relative to system 10. Figure 3 This describes a portion of system 10. For example, system 600 may be a subsystem of system 10. In some embodiments, one or more components of system 600 may be similar to and / or identical to one or more components of system 10. In some embodiments, one or more components of system 600 may replace, be used with, and / or otherwise enhance one or more components of system 10.

[0081] System 600 includes a radiation source 612; optical elements 606; an overlay detection branch 660 with a sensor 604; a beam splitter 670; an alignment branch 680; and various lenses, reflectors, and other optical components. Figure 6 The example objective lens 690 is marked in the diagram; and / or other components. In some embodiments, components of system 600 are formed as part of an overlay and / or alignment sensor used in a semiconductor manufacturing process. Radiation source 612 is configured to generate radiation reflected from target 30 along an optical path (such as optical path 621). The radiation may have a target wavelength and / or wavelength range, target intensity, and / or other characteristics. Target wavelength and / or wavelength range, target intensity, etc., may be entered and / or selected by the user, or determined by the system (e.g., [example objective lens 690]); and / or other components. Figure 3 The system 10 shown is determined based on previous measurements and / or otherwise. In some embodiments, radiation includes light and / or other radiation. In some embodiments, light includes visible light, infrared light, and / or other light. In some embodiments, radiation can be any radiation suitable for interferometric measurements.

[0082] System 600 does not include a separate focusing branch 650 (e.g. Figure 6(The illustrated removal) or a separate wavefront aberration sensor. System 600 provides a novel optical design architecture. Instead of using focusing branch 650 and the aforementioned focus measurement principle, system 600 determines the focus location using the position of a field image captured by the sensing components of the system (e.g., sensor 604, optical element 606, optical component array 605, etc.) of the target 30 in the substrate during a measurement process. System 600 can also be configured such that two optical components in optical component array 605 include microlens arrays, each microlens in the microlens array being configured to form a focal spot on sensor 604, the position of which can be used to determine radiation wavefront aberrations.

[0083] Compared to existing systems, this new architecture reduces cost and size because it eliminates the need for components such as the wedge (and associated lens), the focusing branch 650, and / or a separate wavefront aberration sensor. This new architecture increases the radiation throughput of sensor 604 because an additional beam splitter is no longer required to combine the focusing branch 650 with the rest of system 600. This new architecture eliminates the need for color focus calibration because the radiation wavelength between sensor 604 and the focusing branch 650 no longer changes (e.g., because the focusing branch 650 is not present at all). This new architecture provides continuous focus determination because switching back and forth between focusing and measurement modes is no longer necessary. This new architecture takes into account objective wavefront errors and / or offers other advantages.

[0084] Radiation reflected from a target 30 in a substrate 602 (such as a semiconductor wafer) is received by an optical element 606 (including an array of optical components 605), which alters the angle of the radiation and directs it toward a radiation sensor 604. The radiation from the optical component array 605 is received by the sensor 604, and a signal indicating the location of the radiation field image is generated. The radiation sensor 604 can be coupled with… Figure 3 The detector 4 and / or processor PRO and / or other components shown are similar and / or identical. In some embodiments, sensor 604 includes a camera, charge-coupled device (CCD) array, complementary metal-oxide-semiconductor (CMOS), photodiode array, and / or other sensors. In some embodiments, sensor 604 includes a microdiffraction-based overlay camera associated with overlay measurements. In existing systems, overlay detection branch 660 includes a wedge and / or other optical components, such as a microdiffraction-based overlay wedge.

[0085] For example, Figure 7 The diagram illustrates the overlay detection branch 660, which includes an optical wedge 700 and a lens 702 (e.g., with...). Figure 6 Objectives 690 (similar and / or identical), 704, 706 and 708, sensor 604, illumination pupil 711, detection pupil 712 and example field image 714 (not included here) Figure 6The optical component array 605. The wedge 700 comprises four parts placed within the plane of the detection pupil 712, and redirects the +1 and -1 diffraction orders (in the upper right and lower left quadrants) and the 0th order (in the upper left and lower right quadrants) of the radiation 720 from the substrate 602 to four separate locations in the field image 714. However, these components are bulky, complex, and expensive. For example, the cost of the optical wedge and the physical system space required to implement it are high compared to other optical components.

[0086] Figure 8 The diagram illustrates the replacement of the optical component array (optical component array 605) in the simplified system 600. This is in contrast to the optical wedge 700 ( Figure 7 Compared to the previous method, the optical component array 605 is cheaper and relatively simpler optically. The wedge 700 and lens 708 are replaced by the optical component array 605, which reduces the number of components in the system 600. Figure 6 For example, the optical component array 605 replaces... Figure 7 The wedge 700 and one or more lenses (e.g., lens 708) are shown. The optical component array 605 is configured to receive radiation 710 of different diffraction orders from the substrate 602, change the angle of the different diffraction orders of the radiation 710, and guide the different diffraction orders of the radiation 710 to generate a field image 714 toward different imaging positions on the radiation sensor 604.

[0087] In some embodiments, the optical component array 605 includes four optical components (e.g., divided into quadrants Q1 to Q4), wherein two of the four optical components are associated with the 0th diffraction order radiation 710, and two of the four optical components are associated with the 1st diffraction order radiation 710. Each quadrant is configured to direct a portion of the radiation (e.g., 0th order radiation and / or + / - 1st order radiation) to different regions of interest on the sensor 604 to form a radiation spot on the sensor 604 (see corresponding field image 714). In some embodiments, the optical component array 605 includes a lens array and / or other components. For example, each lens may have a circular 800, a square 802, and / or other cross-sectional shapes.

[0088] In some embodiments, an array of four circular lenses may be used. While circular lenses may not capture a small portion of illumination in or near the center of the pupil, they may be easier to implement and / or have other advantages. In some embodiments, an array of four square lenses may be used, which would capture the entire pupil. In some embodiments, cylindrical lenses may be used for the 0th quadrants Q1 and Q3, which may be less expensive than square lenses. Other configurations are under consideration.

[0089] The lens power of these lenses can be configured to maintain the edge ray angle at sensor 604, maintain the target magnification at sensor 604, and / or have other effects. This can reduce the system 600 ( Figure 6 The detection branch 660 has cost and size advantages, and / or other benefits. The optical axis position of the lenses can also be optimized. The angle of light rays leaving each lens can be linearly modulated by changing the optical axis on each lens in the y-axis in this example. Moreover, each lens has its own optical axis and can be independently selected to produce the desired tilt of light rays leaving the lens. This may change the xy position of each quadrant image from sensor 604.

[0090] In some embodiments, the optical component array 605 includes a spatial light modulator (SLM). The SLM may be transmissive or reflective, or have transmissive or reflective portions. The SLM may include liquid crystal, a digital micromirror device (DMD), a pattern configured to change the angles of different diffraction orders of radiation, and / or other features configured to guide different diffraction orders of radiation toward different imaging positions on a radiation sensor. In some embodiments, the optical component array 605 includes a superlens array. One or more processors PRO (e.g., described below) Figure 3 , Figure 6 and Figure 15 (As shown) is operatively connected to radiation sensor 604 and configured to determine measurement values ​​based on measurement signals. For example, measurement values ​​may include alignment values, overlay values, focal point values, critical dimension values, and / or other measurement values ​​associated with semiconductor manufacturing processes performed on substrate 602.

[0091] In some embodiments, such as Figure 9 As shown, two optical components in the optical component array 605 (located in quadrants Q1 and Q3 in this example) are configured to create two relatively defocused (900, 902) 0th-order images at two different imaging positions on the radiation sensor 604 (see corresponding defocused images 904, 906 in field image 910). This configuration may include, for example, changing the curvature of the two optical components such that positive and negative defocus are produced at the image planes of the two quadrants. Differential defocus signals can be measured from these two 0th-order images, enabling real-time focus detection and / or other operations.

[0092] For example, the shift of field image position images 904 and / or 906 from the expected field image position is determined by one or more processors PRO. Defocused radiation incident on the detection pupil 712 causes the shift. The signal generated by sensor 604 indicates the four individual field image positions of the radiation spot. Additionally, blurring of images 904 and / or 906 can also be used in the same manner. For example, ideal focus can be achieved when images 904 and 906 are shifted by the same distance and blurred at the same level. One or more processors PRO (and / or, for example, those operatively connected to the radiation sensor 604) are... Figure 3 , Figure 6 The PRO shown and / or the following about Figure 15 The described (multiple) processors can be configured to determine the use of system 600 based on the relative defocus of the 0th-order images 904, 906, blur and / or other information at two different imaging positions on the radiation sensor 604. Figure 6 The focal position for imaging substrate 602.

[0093] In some embodiments, the focal position is determined based on the relationship between the shift and the defocusing of the measurement system 600 objective lens. This relationship can be linear and / or have other corresponding relationships. For example, one or more processors (e.g., Figure 3 The PRO shown and / or the following about Figure 15 The described processors are configured to determine the shifts of 0th and 1st order spots and to determine the focal position based on the shifts of the 0th and 1st order spots. The linear relationship between the shifts and objective lens defocus means that as defocus increases, the spot moves further from its intended position. This shift and this relationship can be used to determine the (optimal) focal position for an optical component (such as objective lens 690) to image the target 30. In some embodiments, one or more processors PRO can determine the shift of the field image position of field images 904, 906, for example, based on the centroid of the radiation spot in image 910 and / or by other methods. In some embodiments, the shift of the field image position of field images 904, 906 is determined based on intensity detection of field images 904, 906. In some embodiments, the intensity detection, for example, is determined at one or more halves of one or more radiation spot rings in field images 904, 906. Additionally, as described above, blurring of images 904 and / or 906 can also be used in a similar manner. For example, ideal focus can be achieved when images 904 and 906 are shifted by the same distance and blurred at the same level.

[0094] In some embodiments, one or more processors are configured as a platform for maintaining substrate 602 based on the focus position auto-adjustment system 600 (e.g., with...). Figure 1The positions shown are similar to and / or identical to those described above for WTa and / or WTb, so that subsequent images of substrate 602 are focused. Note that, as a possible example, Figure 9 The diagram shows the sources from Figure 8 An optical component array 605 is a lens array with a square 802 cross-sectional shape. However, these lenses can have any shape that allows them to function as described herein.

[0095] In some embodiments, two optical components in the optical component array 605 include a microlens array, each microlens being configured to form a focal spot on the radiation sensor 604, the location of which can be used to determine radiation wavefront aberrations. The individual microlenses in the microlens array can collect light filling their aperture and form focal spots on the sensor 604, these focal spots being located at the focal plane of the microlens array. A wavefront without aberrations (e.g., zero slope) may produce spots at the center behind the individual microlenses, these spots can be used as reference positions. In a wavefront with aberrations (e.g., non-zero slope), the position of the spot is displaced relative to its corresponding reference position. Measuring the displacement helps in determining wavefront aberrations (e.g., the slope of the wavefront). For example, one or more processors PRO(s) operably connected to the radiation sensor 604 Figure 3 , Figure 6 , Figure 15 The sensor can be configured to detect radiation wavefront aberrations based on the (displacement) position of the focal spot relative to a reference position. Additionally, the minimum slope detectable by one or more processors corresponds to the minimum defocus that sensor 604 and / or one or more processors PRO can measure.

[0096] As an example, Figure 10 The illustration shows microlenses 1000 (e.g., small lenses) in a microlens array 1001, configured to form a focal spot 1002 on a radiation sensor 604. The position of the focal spot 1002 can be used to determine the aberrations of the radiation wavefronts 1004, 1006. Each microlens 1000 in the microlens array 1001 can collect light filling its aperture and form the focal spot 1002 on the sensor 604. A wavefront 1004 without aberrations (e.g., zero slope) can produce a spot 1002 located directly behind and centered on each small lens, as shown in view 1020, which can be used as a reference position 1003. In a wavefront 1006 with aberrations (e.g., non-zero slope), the position 1008 of the spot is displaced relative to its corresponding reference position 1003 (as shown in view 1021). Measuring the displacement helps determine the wavefront aberrations (e.g., the slope of the wavefront). For example, one or more processors PRO (Programmable Processors) operatively connected to the radiation sensor 604 Figure 3 , Figure 6 , Figure 15It can be configured to detect radiation wavefront aberrations based on the (displacement) position of the focal spot relative to a reference position. Figure 10 The example shown illustrates several displacement spots 1012 and a missing spot 1014.

[0097] Figure 11 The illustration also shows microlenses 1000 (e.g., small lenses) in a microlens array 1001 (located in Q1 and Q4 in this example), configured to form a focal spot 1002 on the radiation sensor 604 (see also the corresponding image 1100 of focal spot 1002 in image 1102), the position of which can be used to determine radiation wavefront aberrations, but in relation to Figure 8 and 9 In an optical component array 605 similar to the one shown. Figure 11 As shown, two optical components in the optical component array 605 include a microlens array 1001, each microlens 1000 (small lens) in the microlens array 1001 being configured to form a focal spot 1002 on the radiation sensor 604. In this example, the microlens array 1001 in Q1 and Q4 and the 0th-order radiation 710 can be used for aberration detection.

[0098] Each microlens 1000 (small lens) in the microlens array 1001 can collect light that fills its aperture and form a focal spot 1002 located at the focal plane 1110 of the microlens array (multiple) 1001. Figure 12 As shown, the focal plane 1110 of the (multiple) microlens array 1001 may differ from the focal plane 1202 of the spot 1200 of radiation 710 from other optical components in the optical component array 605 (e.g., lenses located at Q2 and Q3 in this example). Therefore, in some embodiments, the microlens array 1001 may be positioned in the system 600 (...) compared to other optical components in the optical component array 605. Figure 6 The radiation sensor 604 is positioned in different planes such that it is located at the focal plane 1110 of the microlens array 1001 and other optical components in the optical component array 605 (lenses located at Q2 and Q3 in this example). For example, the microlens array 1001 can be positioned such that... Figure 12 The example shown has focal planes 1110 and 1202 that coincide (e.g., at or near sensor 604).

[0099] Figure 13 Another embodiment is illustrated, wherein the radiation sensor 604 includes one or more sub-sections 1300 configured to sense radiation from... Figures 10 to 12 The focal spot is 1002. In this example, system 600 ( Figure 6The overlay detection branch 660 includes a segmented mirror 1302 (and / or similar functional components) configured to direct radiation from the microlens array 1001 (located in quadrants Q1 and Q4 in this example) to a sub-section 1300 of the radiation sensor 604. The sub-section 1300 may also be a separate sensor with different operating specifications (and therefore not a sub-section at all, but a separate sensor), mounted separately from the radiation sensor 604. For example, if high defocus detection speed is required, the sub-section 1300 may have a higher detection speed than the sensor 604. If high spatial resolution for defocus detection is not required (or is less required), the sub-section 1300 may have fewer pixels than the sensor 604 (e.g., faster and cheaper). The mirror 1302 may be, for example, an edge-mounted segmented mirror and / or other components configured for similar functionality. Figure 13 The illustration shows a side view 1305, a front view 1310, and a top view 1320 of the reflector 1302. As described above, radiation from the optical components 605 in quadrants Q2 and Q3 can be directed toward the sensor 604. The reflector 1302 can be positioned and / or otherwise configured such that a spot 1002 of radiation 710 is formed at a focal plane corresponding to the sub-part 1300. In this example, the focal length of the microlens array 1001 in quadrants Q1 and Q4 can be approximately 10 to 20 nm, while the focal length of the optical components 605 in quadrants Q2 and Q3 can be approximately 190 nm. Other configurations are under consideration.

[0100] Return to Figure 6 Various lenses Figure 6The example objective lens 690, reflectors, and other optical components are configured to receive, transmit, reflect, focus, be generated by source 612, be separated by beam splitter 670, be transmitted or reflected by various optical elements, be received by detection branch 660, be received by alignment branch 680, and / or be used by other parts of system 600 for illumination and / or to perform other operations thereon. These various lenses, reflectors, and / or other optical components can include any type of lens, mirror, and / or other optical components configured to allow system 600 to operate as described herein. For example, objective lens 690 can be formed of any transparent material and has a curved surface configured to focus or otherwise concentrate one or more radiation spots onto target(s)30. Various lenses, reflectors, optical elements, beam splitters, and other optical elements can be positioned in any location and / or at any angle relative to each other to allow system 600 to operate as described herein. This can include positioning by specific relative distances between elements, specific angles between elements, etc. In some embodiments, various lenses, reflectors, optical elements, beam splitters, and other optical components are positioned relative to each other in system 600 via structural members, clips, jigs, screws, nuts, bolts, adhesives, and / or other mechanical means. In some embodiments, various of the lenses, reflectors, optical elements, beam splitters, and other optical elements may be movable relative to each other. For example, movement may be configured to adjust the position of corresponding illumination spots on one or more targets 30. In some embodiments, movement includes tilting, translating, or otherwise changing the distance between the various lenses, reflectors, and other optical components. Other examples of movement are also considered.

[0101] In some embodiments, movement can be electronically controlled by a processor, such as a processor PRO (also discussed below). Figure 3 and Figure 15 The processor PRO can be included in the computing system CS (in the middle). Figure 15 It can be operated based on computer or machine-readable instructions (e.g., as shown below regarding...). Figure 15 (Described). Electronic communication can be achieved by sending electronic signals between individual components, sending data between individual components of system 600, sending values ​​between individual components, and / or other communications. Components of system 600 can communicate via wires or wirelessly via networks, such as the Internet or combinations thereof, such as local area networks, cellular networks or personal area networks, internal organizational networks, and / or other networks.

[0102] In some embodiments, one or more actuators ( Figure 6An actuator (not shown) may be coupled to one or more components of system 600 and configured to move one or more components of system 600. An actuator may be coupled to one or more components of system 600 via adhesive, clamp, jig, screw, collar, and / or other mechanisms. The actuator may be configured for electronic control. Each actuator may be configured to convert an electrical signal into mechanical displacement. The mechanical displacement is configured to move a component of system 600. As an example, one or more actuators may be piezoelectric. One or more processors PRO may be configured to control the actuators. One or more processors PRO may be configured to individually control each of the one or more actuators.

[0103] Figure 6 The number of various lenses, reflectors, and / or other optical components shown is not intended to be limiting. The principles described herein can be extended such that, in some embodiments, system 600 includes additional or fewer lenses, reflectors, and / or other optical components.

[0104] Figure 14 Measurement method 1400 is illustrated. In some embodiments, such as method 1400, it is performed as part of an overlay and / or alignment sensing operation in a semiconductor device manufacturing process. In some embodiments, one or more operations of method 1400 may be performed within... Figure 6 The illustrated system 600, Figure 3 System 10 shown in the figure, computer system (e.g., as shown in the figure) Figure 15 Implemented or embodied in (as illustrated and described below) and / or other systems. In some embodiments, method 1400 includes receiving (operation 1402) radiation reflected from a substrate using an array of optical components, changing the angles of different diffraction orders of the radiation, and directing the different diffraction orders of the radiation toward different imaging positions on a radiation sensor; determining (operation 1404) a focal position for imaging the substrate; detecting (operation 1406) wavefront aberrations; generating (operation 1408) a measurement signal based on the radiation received at different imaging positions; determining (operation 1410) a measurement value based on the measurement signal, focal position, wavefront aberrations, and / or other information; and / or performing other operations.

[0105] The operation of method 1400 is intended to be illustrative. In some embodiments, method 1400 may be performed with one or more additional operations not described and / or without the one or more operations discussed. For example, in some embodiments, method 1400 may include additional operations that include determining adjustments to the semiconductor device manufacturing process. Additionally, the operation of method 1400 in Figure 14 The order illustrated in the diagram and described herein is not intended to be restrictive.

[0106] In some embodiments, one or more portions of method 1400 may be implemented in and / or controlled by one or more processing devices (e.g., digital processors, analog processors, digital circuitry designed to process information, analog circuitry designed to process information, state machines, and / or other mechanisms that process information electronically). The 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 on an electronic storage medium. The one or more processing devices may include one or more devices configured by hardware, firmware, and / or software to specifically design for performing one or more operations of method 1400 (e.g., see below). Figure 15 (Related discussion).

[0107] In operation 1402, an array of optical components receives radiation reflected from a substrate. The optical component array is configured to change the angles of different diffraction orders of the radiation and guide these different diffraction orders toward different imaging positions on a radiation sensor. The radiation sensor can be coupled with… Figure 3 and Figure 6 The detector 4, sensor 604, and / or processor PRO (operably coupled to the radiation sensor) and / or other components shown are similar to and / or identical to those described above. In some embodiments, the optical component array is the same as described above. Figures 8 to 13 One or more optical component arrays 605 shown are similar and / or identical. These optical component arrays may include four optical components (e.g., divided into quadrants Q1 to Q4), two of which are associated with 0th diffraction order radiation and two of which are associated with 1st diffraction order radiation. Each quadrant is configured to direct a portion of the radiation (e.g., 0th order radiation and / or + / - 1st order radiation) to different regions of interest on the sensor to form a radiation spot on the sensor.

[0108] In some embodiments, the optical component array includes a lens array. For example, each lens may have a circular or square cross-sectional shape. In some embodiments, the optical component array includes a spatial light modulator (SLM). The SLM may be transmissive or reflective, or have transmissive or reflective portions. The SLM may include liquid crystal, a digital micromirror device (DMD), a pattern configured to change the angles of different diffraction orders of radiation, and / or other features configured to guide different diffraction orders of radiation toward different imaging positions on a radiation sensor. In some embodiments, the optical component array includes a superlens array.

[0109] In some embodiments, operation 1402 includes using a radiation source (such as...) Figure 3 Source 2 and / or shown Figure 6As shown in 612), radiation is generated and directed toward the substrate. In some embodiments, the substrate comprises a semiconductor wafer having one or more targets configured to reflect radiation toward the optical component array. In some embodiments, the sensor includes a camera, a charge-coupled device (CCD) array, a complementary metal-oxide-semiconductor (CMOS) array, a photodiode array, and / or other sensors. In some embodiments, the sensor includes a micro-diffraction-based overlay camera associated with overlay measurements.

[0110] In some embodiments, operation 1402 includes irradiating (and / or otherwise irradiating) one or more targets in a patterned substrate (e.g., Figure 3 (Target 30 shown). Radiation includes light and / or other radiation. In some embodiments, radiation may be directed by a radiation source to multiple targets, a single target, a sub-part of a target (e.g., something smaller than the whole), and / or otherwise directed to a substrate. In some embodiments, radiation may be directed to the target in a time-varying manner by a radiation source. For example, radiation may be rasterized on the target (e.g., by moving the target below the radiation) so that different parts of the target are irradiated at different times. As another example, the characteristics of the radiation (e.g., wavelength, intensity, etc.) may vary. This may create a time-varying data envelopment or window for analysis. The data envelopment may facilitate the analysis of individual sub-parts of the target, comparing one part of the target with another part and / or other targets (e.g., in other layers) and / or performing other analyses.

[0111] In some embodiments, operation 1402 includes detecting reflected radiation from one or more diffraction grating targets (using the radiation sensor described above). Detecting reflected radiation includes detecting one or more phase and / or amplitude (intensity) shifts in reflected radiation from one or more geometric features of the targets(s). One or more phase and / or amplitude shifts correspond to one or more dimensions of the targets. For example, the phase and / or amplitude of reflected radiation from one side of the target is different from the phase and / or amplitude of reflected radiation from the other side of the target.

[0112] Detecting one or more phase and / or amplitude (intensity) shifts in reflected radiation from a target involves measuring local phase shifts (e.g., local phase increments) and / or amplitude changes corresponding to different portions of the target. For example, reflected radiation from a specific region of the target may include a sinusoidal waveform with a specific phase and / or amplitude. Reflected radiation from different regions of the target (or targets in different layers) may also include sinusoidal waveforms, but with different phases and / or amplitudes. Detected reflected radiation also includes measuring the phase and / or amplitude differences of reflected radiation at different diffraction orders. For example, detecting one or more local phase and / or amplitude shifts can be performed using Hilbert transforms and / or other techniques. Interferometry techniques and / or other operations can be used to measure the phase and / or amplitude differences of reflected radiation at different diffraction orders.

[0113] In operation 1404, a focal position for imaging the substrate is determined. In some embodiments, two optical components in the optical component array are configured to create two relatively defocused 0th-order images at two different imaging positions on the radiation sensor (see [link to relevant documentation]). Figure 9 One or more processors (such as processor PRO) are configured to determine a focal position for imaging the substrate with the metrology system based on 0th-order images of relative defocus at two different imaging positions on the radiation sensor. In some embodiments, one or more processors are configured to automatically adjust the position of the metrology system's substrate-holding platform based on the focal position, such that subsequent images of the substrate are in focus.

[0114] In operation 1406, wavefront aberration is detected. In some embodiments, two optical components in the optical component array 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, the location of which can be used to determine radiation wavefront aberration (see [link to relevant documentation]). Figures 10 to 11 (and the corresponding description above). One or more processors PRO can be configured to detect wavefront aberrations based on the position of the focal spot relative to a reference location and / or other information. In some embodiments, the microlens array is positioned in a different plane of the measurement system compared to other optical components in the optical component array, such that the radiation sensor is located at the focal plane of the microlens array and the other optical components in the optical component array. In some embodiments, the radiation sensor includes a sub-section configured to sense the focal spot (located in a different plane) (see above). Figure 12 Operation 1406 may include using segmented mirrors to direct radiation from the microlens array to a sub-section of the radiation sensor (e.g., as shown in the image). Figure 13 (As shown and as described above).

[0115] In operation 1408, a measurement signal is generated based on the radiation and / or other information received at different imaging locations. The measurement signal is generated by a radiation sensor (e.g., Figure 3 The measurement signal is generated by the detector 4 and / or other sensors shown herein. The measurement signal includes an electronic signal representing and / or otherwise corresponding to radiation reflected from the target(s). For example, the measurement signal may indicate a measurement value and / or other information associated with a diffraction grating target. Generating the measurement signal includes sensing the reflected radiation and converting the sensed reflected radiation into an electronic signal. In some embodiments, generating the measurement signal includes sensing different portions of reflected radiation from different regions and / or different geometries and / or multiple targets, and combining the different portions of reflected radiation to form the measurement signal. This may include generating and / or analyzing one or more images of the target using the radiation described herein. This sensing and conversion may be performed by a sensor and / or a sensor that is compatible with the radiation distribution described herein. Figure 3 and Figure 6 The detector 4, sensor 604 and / or processor PRO shown are similar and / or the same components and / or other components that perform the operation.

[0116] In operation 1410, measurement values ​​are determined based on measurement signals, focal position, wavefront aberrations, and / or other information. Measurement values ​​may be determined by one or more processors (e.g., the processor PRO described herein) and / or other components. In some embodiments, measurement values ​​include alignment values, overlay values, focal value, critical size values, and / or other measurements associated with a semiconductor manufacturing process performed on the substrate. Measurement information (e.g., overlay values, alignment values, and / or other information) may be determined using interferometry principles and / or other principles. For example, in some embodiments, operation 1410 includes determining overlay and / or alignment. Overlay and / or alignment are determined based on reflected diffraction radiation from a diffraction grating target on the substrate, focal position, displacement, and / or other information.

[0117] In some embodiments, method 1400 includes determining adjustments for a semiconductor device fabrication process. For example, this may include automatically adjusting the position of a platform holding the substrate in a metrology system based on a determined focal position using one or more processors PRO, such that subsequent images of the substrate are focused (as described above). In some embodiments, method 1400 includes determining one or more semiconductor device fabrication process parameters. The one or more semiconductor device fabrication process parameters may be determined based on one or more detected phase and / or amplitude changes, overlay and / or alignment values ​​indicated by metrology signals, and / or other information. The one or more parameters may include parameters of radiation (radiation used for metrology), metrology inspection locations on semiconductor device structural layers, radiation beam trajectories across targets, and / or other parameters. In some embodiments, process parameters may be broadly interpreted to include platform position, mask design, metrology target design, semiconductor device design, radiation intensity (for exposing resists, etc.), radiation incident angle (for exposing resists, etc.), radiation wavelength (for exposing resists, etc.), pupil size and / or shape, resist material, and / or other parameters.

[0118] In some embodiments, method 1400 includes determining process adjustments based on one or more defined semiconductor device manufacturing process parameters, and adjusting semiconductor device manufacturing apparatus and / or other operations based on the determined adjustments. This can be performed by one or more processors, such as... Figure 3 and Figure 6 The PRO shown is described as follows: Figure 15 The processor and / or other processors that form part of the computer system illustrated and described below. For example, if a determined measurement value is outside the process tolerance, the out-of-tolerance measurement value may be caused by one or more manufacturing processes whose process parameters have drifted and / or changed in other ways, rendering the process no longer acceptable for the device (e.g., the measurement value may violate an acceptability threshold). One or more new or adjusted process parameters may be determined based on the measurement. The new or adjusted process parameters may be configured to make the manufacturing process produce acceptable device again.

[0119] For example, new or adjusted process parameters may cause previously unacceptable measurements to be adjusted back to an acceptable range. The new or adjusted process parameters can be compared to existing parameters for a given process. For example, if a difference exists, that difference can be used to determine adjustments to the apparatus used to generate the device (e.g., parameter "x" should be increased / decreased / changed to match a new or adjusted version of parameter "x" determined as part of method 1400). In some embodiments, method 1400 may include electronically adjusting the apparatus (e.g., based on the determined process parameters). Electronic adjustment may include sending electronic signals and / or other communications to the apparatus, such as causing changes to the apparatus. Electronic adjustment may include, for example, changing settings and / or other adjustments on the apparatus.

[0120] Figure 15 This is a diagram of an example computer system CS that can be used for one or more operations described herein. The computer system CS includes a bus BS or other communication mechanism for transmitting information and a processor PRO (or multiple processors, coupled to the bus BS for processing information) for processing information. Figure 3 and Figure 6 The processor PRO shown is similar to and / or identical to that shown. The computer system CS also includes main memory MM, such as random access memory (RAM) or other dynamic storage devices, which is coupled to the bus BS for storing information and instructions to be executed by the processor PRO. The main memory MM can also be used to store temporary variables or other intermediate information during instruction execution by the processor PRO. The computer system CS also includes read-only memory (ROM) or other static storage devices coupled to the bus BS for storing static information and instructions from the processor PRO. Storage devices such as disks or optical discs SD are provided and coupled to the bus BS for storing information and instructions.

[0121] A computer system (CS) can be coupled to a display (DS), such as a flat panel or touchpad display or a cathode ray tube (CRT), via a bus (BS) for displaying information to the computer user. Input devices (IDs), including alphanumeric keys and other keys, are coupled to the bus (BS) to transmit information and command selections to the processor (PRO). Another type of user input device is a cursor control (CC), such as a mouse, trackball, or arrow keys, to transmit directional information and command selections to the processor (PRO) and control cursor movement on the display (DS). This input device typically has two degrees of freedom on two axes (a first axis, e.g., x) and a second axis, e.g., y), allowing the device to specify its position in a plane. Touchpad (screen) displays can also be used as input devices.

[0122] In some embodiments, all or some of the operations described herein may be executed by a computer system CS in response to the processor PRO executing one or more sequences of one or more instructions contained in the main memory MM. Such instructions may be read into the main memory MM from another computer-readable medium, such as a storage device SD. Execution of the sequence of instructions included in the main memory MM causes the processor PRO to perform the process steps (operations) described herein. One or more processors in a multiprocessor arrangement may also be employed to execute the sequence of instructions contained in the main memory MM. In some embodiments, hardwired circuitry may be used in place of or in combination with software instructions. Therefore, the description herein is not limited to any specific combination of hardware circuitry and software.

[0123] As used herein, the term "computer-readable medium" or "machine-readable medium" refers to any medium that participates in providing instructions to a processor (PRO) for execution. Such media can take many forms, including, but not limited to, non-volatile media, volatile media, and transmission media. Non-volatile media include, for example, optical discs 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 forming a bus (BS). Transmission media can also take the form of sound waves or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Computer-readable media can be non-transient, such as floppy disks, retractable disks, hard disks, magnetic tape, any other magnetic media, CD-ROMs, DVDs, any other optical media, punched cards, paper tape, any other physical media with a perforated pattern, RAM, PROMs and EPROMs, flash memory EPROMs, any other memory chips, or memory cartridges. Non-transient computer-readable media may have instructions written on them. When executed by a computer, the instructions can perform any of the operations described herein. For example, transient computer-readable media may include a carrier wave or other propagating electromagnetic signals.

[0124] Various forms of computer-readable media can involve carrying one or more sequences of one or more instructions to a processor PRO for execution. For example, the instructions may initially be carried on a disk of a remote computer. The remote computer can load the instructions into its dynamic memory and transmit them over a telephone line using a modem. A modem local to the computer system CS can receive data over the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector coupled to a bus BS can receive the data carried in the infrared signal and place the data on the bus BS. The bus BS carries the data to 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 on a storage device SD before or after execution by the processor PRO.

[0125] The computer system CS may also include a communication interface CI coupled to the bus BS. The communication interface CI provides bidirectional data communication coupling with a network link NDL connected to the local network LAN. For example, the communication interface CI may be an Integrated Services Digital Network (ISDN) card or a modem to provide data communication connectivity with a corresponding type of telephone line. As another example, the communication interface CI may be a Local Area Network (LAN) card to provide data communication connectivity with a compatible LAN. Wireless links may also be implemented. In any such implementation, the communication interface CI transmits and receives electrical, electromagnetic, or optical signals carrying digital data streams representing various types of information.

[0126] A network link (NDL) typically provides data communication to other data devices over one or more networks. For example, a network link NDL can provide connectivity to a host computer (HC) via a local network (LAN). This can include data communication services provided via a global packet data communication network (now commonly referred to as the "Internet" INT). A local network (LAN) (Internet) can use electrical, electromagnetic, or optical signals carrying digital data streams. Signals over various networks, as well as signals on the network data link (NDL) and through the communication interface (CI) (carrying digital data to and from the computer system (CS)), are exemplary forms of carriers for transmitting information.

[0127] A computer system CS can send and receive messages, including program code, via networks (multiple), network data links (NDL), and communication interfaces (CI). In the Internet example, the host computer HC can send application request codes via the Internet (INT), network data links (NDL), local network (LAN), and communication interface (CI). For example, such a download application can provide all or part of the methods described herein. The received code can be executed by the processor PRO upon receipt and / or stored in storage devices (SD) or other non-volatile storage devices for later execution. In this way, the computer system CS can obtain application code in carrier form.

[0128] Various embodiments of the system and method are disclosed in the list of subsequently numbered clauses. Further features, characteristics, and exemplary technical solutions of this disclosure will be described below based on clauses that may be optionally claimed in any combination:

[0129] 1. A measurement system comprising: a radiation sensor configured to generate a measurement signal based on radiation received at different imaging locations on the radiation sensor; and

[0130] An array of optical components is configured to receive radiation of different diffraction orders from a substrate, change the angle of the different diffraction orders of the radiation, and guide the different diffraction orders of the radiation toward different imaging positions on the radiation sensor.

[0131] 2. The system according to clause 1, wherein the optical component array comprises four optical components, two of which are associated with 0 diffraction order radiation and two of which are associated with 1 diffraction order radiation.

[0132] 3. The system according to any of the preceding clauses, wherein the optical component array includes a lens array.

[0133] 4. A system according to any of the preceding clauses, wherein each lens has a circular or square cross-sectional shape.

[0134] 5. The system according to any of the preceding clauses, wherein the array of optical components includes a spatial light modulator (SLM).

[0135] 6. A system according to any of the preceding clauses, wherein the SLM is transmissive or reflective, or has a transmissive or reflective portion.

[0136] 7. The system 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 angles of different diffraction orders of radiation and to direct the different diffraction orders of radiation toward different imaging positions on the radiation sensor.

[0137] 8. The system according to any of the preceding clauses, wherein the optical component array includes a superlens array.

[0138] 9. The system according to any of the preceding clauses further includes one or more processors, which are operatively connected to the radiation sensor and configured to determine the measurement value based on the measurement signal.

[0139] 10. A system according to any of the preceding clauses, wherein the measurement values ​​include alignment values, overlay values, focal point values ​​and / or critical dimension values ​​associated with a semiconductor manufacturing process performed on the substrate.

[0140] 11. A system according to any of the preceding clauses, wherein two optical components in an optical component array are configured to create two relatively defocused 0th-order images at two different imaging positions on a radiation sensor.

[0141] 12. The system according to any of the preceding clauses further includes one or more processors operatively connected to the radiation sensor and configured to determine a focal position for imaging the substrate with the measurement system based on a 0th-order image of relative defocus at two different imaging positions on the radiation sensor.

[0142] 13. In a system according to any of the preceding clauses, one or more processors are further configured to automatically adjust the position of the platform holding the substrate of the measurement system based on the focal position, so that subsequent images of the substrate are focused.

[0143] 14. A system according to any of the preceding clauses, wherein two of the optical components in the optical component array include a microlens array, each microlens in the microlens array being configured to form a focal spot on a radiation sensor, the position of which can be used to determine radiation wavefront aberrations.

[0144] 15. The system according to any of the preceding clauses further includes one or more processors operatively connected to the radiation sensor and configured to detect radiation wavefront aberrations based on the position of the focal spot relative to a reference position.

[0145] 16. A system according to any of the preceding clauses, wherein the radiation sensor includes a sub-section configured to sense a focal spot, and the system further includes a segmented mirror configured to direct radiation from the microlens array to the sub-section of the radiation sensor.

[0146] 17. A system according to any of the preceding clauses, wherein the microlens array is positioned in a different plane of the measurement system than other optical components in the optical component array, such that the radiation sensor is located at the focal plane of the microlens array and the other optical components in the optical component array.

[0147] 18. The system according to any of the preceding clauses further includes a radiation source and one or more lenses configured to generate radiation and direct the radiation toward the substrate.

[0148] 19. A system 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 wherein the sensor comprises a micro-diffraction-based overlay camera associated with overlay measurements.

[0149] 20. A system 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) array, and / or a photodiode array.

[0150] 21. A measurement method comprising: receiving radiation of different diffraction orders from a substrate using an array of optical components, changing the angles of the different diffraction orders of the radiation, and guiding the different diffraction orders of the radiation toward different imaging positions on a radiation sensor; and generating a measurement signal based on the radiation received at the different imaging positions on the radiation sensor using the radiation sensor.

[0151] 22. The method according to clause 21, wherein the optical component array comprises four optical components, two of which are associated with 0 diffraction order radiation and two of which are associated with 1 diffraction order radiation.

[0152] 23. The method according to any of the preceding clauses, wherein the optical component array includes a lens array.

[0153] 24. The method according to any of the preceding clauses, wherein each lens has a circular or square cross-sectional shape.

[0154] 25. The method according to any of the preceding clauses, wherein the optical component array includes a spatial light modulator (SLM).

[0155] 26. The method according to any of the preceding clauses, wherein the SLM is transmissive or reflective, or has a transmissive or reflective portion.

[0156] 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 angles of different diffraction orders of radiation and to direct the different diffraction orders of radiation toward different imaging positions on the radiation sensor.

[0157] 28. The method according to any of the preceding clauses, wherein the optical component array includes a superlens array.

[0158] 29. The method according to any of the preceding clauses further includes using one or more processors operatively connected to the radiation sensor to determine the measurement value based on the measurement signal.

[0159] 30. The method according to any of the preceding clauses, wherein the measured values ​​include alignment values, overlay values, focal point values ​​and / or critical dimension values ​​associated with the semiconductor manufacturing process performed on the substrate.

[0160] 31. The method according to any of the preceding clauses, wherein two optical components in the optical component array are configured to create two relatively defocused 0th-order images at two different imaging positions on the radiation sensor.

[0161] 32. The method according to any of the preceding clauses further includes using one or more processors operatively connected to the radiation sensor to determine a focal position for imaging the substrate based on 0th-order images of relative defocus at two different imaging positions on the radiation sensor.

[0162] 33. The method according to any of the preceding clauses, wherein one or more processors are further configured to automatically adjust the position of the platform holding the substrate of the measurement system based on the focal position, such that subsequent images of the substrate are focused.

[0163] 34. The method according to any of the preceding clauses, wherein two of the optical components in the optical component array include a microlens array, each microlens in the microlens array being configured to form a focal spot on a radiation sensor, the position of which can be used to determine radiation wavefront aberrations.

[0164] 35. The method according to any of the preceding clauses further includes using one or more processors operatively connected to the radiation sensor to detect radiation wavefront aberrations based on the position of the focal spot relative to a reference position.

[0165] 36. The method according to any of the preceding clauses, wherein the radiation sensor includes a sub-part configured for sensing a focal spot, the method further comprising using a segmented mirror to guide radiation from a microlens array to the sub-part of the radiation sensor.

[0166] 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 optical component array, such that the radiation sensor is located at the focal plane of the microlens array and the other optical components in the optical component array.

[0167] 38. The method according to any of the preceding clauses further includes generating radiation with a radiation source and directing the radiation toward the substrate.

[0168] 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 optical component array, and wherein the sensor comprises a micro-diffraction-based overlay camera associated with overlay measurements.

[0169] 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) array, and / or a photodiode array.

[0170] The concepts disclosed herein can be associated with any general imaging system used for imaging subwavelength features, and may be particularly useful for emerging imaging techniques capable of producing increasingly shorter wavelengths. Emerging techniques already in use include EUV (Extreme Ultraviolet) and DUV lithography, which can produce wavelengths of 193 nm using ArF lasers, and even 157 nm using fluorine lasers. Moreover, EUV lithography can produce wavelengths in the range of 20 to 5 nm by using synchrotrons or by generating photons in the solid or plasma range by colliding materials (solid or plasma) with high-energy electrons.

[0171] While the concepts disclosed herein can be used for imaging on substrates such as silicon wafers, it should be understood that the disclosed concepts can be used with any type of photolithography imaging system, such as those used for imaging on substrates other than silicon wafers. Furthermore, combinations and sub-combinations of the disclosed elements can include individual embodiments.

[0172] The above description is intended to be illustrative and not restrictive. Therefore, it will be apparent to those skilled in the art that modifications can be made as described without departing from the scope of the claims set forth below.

Claims

1. A measurement system, comprising: A radiation sensor is configured to generate a measurement signal based on radiation received at different imaging locations on the radiation sensor. as well as An array of optical components is configured to receive radiation of different diffraction orders from a substrate, change the angle of the different diffraction orders of the radiation, and guide the different diffraction orders of the radiation toward the different imaging positions on the radiation sensor.

2. The system of claim 1, wherein the optical component array comprises four optical components, two of which are associated with 0 diffraction order radiation and two of which are associated with 1 diffraction order radiation.

3. The system according to claim 1 or 2, wherein the optical component array comprises a lens array.

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

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

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

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

8. The system according to claim 1 or 2, wherein the optical component array comprises a superlens array.

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

10. The system of claim 9, wherein the measurement values ​​include alignment values, overlay values, focal point values, and / or critical dimension values ​​associated with the semiconductor manufacturing process performed on the substrate.

11. The system according to any one of claims 1 to 10, wherein two optical components in the optical component array are configured to create two relatively defocused 0th-order images at two different imaging positions on the radiation sensor.

12. The system of claim 11, further comprising one or more processors operatively connected to the radiation sensor and configured to determine a focal position for imaging the substrate with the measurement system based on the relative defocused 0th-order images at the two different imaging positions on the radiation sensor.

13. The system of claim 12, wherein the one or more processors are further configured to automatically adjust the position of the platform of the measurement system holding the substrate based on the focal position, such that subsequent images of the substrate are focused.

14. The system according to any one of claims 1 to 10, wherein two of the optical components in the optical component array comprise a microlens array, each microlens in the microlens array being configured to form a focal spot on the radiation sensor, the position of the focal spot being capable of determining radiation wavefront aberrations.

15. The system of claim 14, further comprising one or more processors operatively 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