Broad spectrum metrology system and method for various metrology marker types

Abstract

Broad spectrum metrology for various metrology marker types is described. The systems and methods utilize a modulator, such as a spatial light modulator (SLM). The alignment mark is projected onto the SLM through the imaging lens. A pattern sequence on the SLM modulates the incoming image and all reflected energy collected by a collection lens, and a time-varying signal may be generated from a single detector or array of detectors. Color demultiplexers may be added to separate the signals at different wavelengths and direct them to respective detectors to allow for simultaneous multi-color measurements. The alignment mark may be irradiated in a static or scanning mode. The combination of the varying mark positions and SLM patterns allows various signals to be generated for alignment position measurements. Moreover, the SLM may readily accommodate the size of a region of interest and the marker.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to U.S. application 63 / 450,273, filed on March 6, 2023, and incorporated herein by reference in its entirety. Technical Field

[0003] The present description generally relates to broad spectrum metrology systems and methods for various metrology marker types. Background Art

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

[0005] Before the pattern is transferred from the pattern forming device to the substrate, the substrate may undergo various 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 process array 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 intended to complete the individual layers of the device. If several layers are required in the device, the entire process or a variation thereof is repeated for each layer. Ultimately, a device will be present in each target portion on the substrate. These devices are then separated from each other by techniques such as cutting or sawing so that the individual devices can be mounted on a carrier, connected to pins, etc.

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

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

[0008] As semiconductor manufacturing processes continue to advance, following a trend generally referred to as "Moore's Law," the size of functional elements has been continuously reduced, while the number of functional elements (such as transistors) per device has steadily increased for decades. At the current state of the art, the layers of a device are fabricated using a lithography projection apparatus that projects a design layout onto a substrate using radiation from a deep ultraviolet or extreme ultraviolet radiation source, thereby creating individual functional elements with dimensions well below 100 nm (i.e., less than half the wavelength of radiation from the radiation source (e.g., a 193 nm radiation source)).

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

[0010] The systems and methods described herein facilitate broad spectrum measurement for a variety of measurement mark types. As a measurement example, generation of alignment signals to align features in a substrate (e.g., semiconductor wafer) layer as part of a semiconductor manufacturing process is described. The system and method utilize a modulator such as a spatial light modulator (SLM). Alignment marks are projected onto the SLM through an imaging lens. The pattern sequence on the SLM modulates the incoming image and the reflected energy collected by the collection lens, and a time-varying signal can be generated from a single detector or an array of detectors. A color demultiplexer can be added to separate signals of different wavelengths and direct them to corresponding detectors to allow simultaneous multi-color measurement. The alignment marks can be irradiated in static or scanning mode. The combination of varying mark positions and SLM patterns allows various signals to be generated for alignment position measurement. Moreover, the SLM can be easily adapted to the size of the region of interest and the mark.

[0011] According to an embodiment, a metrology system is provided. The system includes a radiation source configured to irradiate a feature in a patterned substrate with radiation. The system includes a modulator configured to modulate radiation received from the feature to generate time-varying radiation. The system includes a radiation sensor configured to receive the time-varying radiation and generate a measurement signal. The measurement signal includes measurement information related to the feature.

[0012] In some embodiments, the features include metrology marks. For example, the metrology marks may include a diffraction grating. Radiation is diffracted by the diffraction grating. In some embodiments, the metrology marks are associated with alignment and / or overlay measurements of the patterned substrate.

[0013] In some embodiments, the modulator is a spatial light modulator (SLM). In some embodiments, the SLM is a digital micromirror device (DMD). In some embodiments, the SLM comprises a sequence of binary or grayscale patterns configured to modulate incoming radiation. In some embodiments, the SLM is transmissive or reflective.

[0014] In some embodiments, the modulation comprises continuously transmitting one or more sub-portions of the received radiation over time.

[0015] In some embodiments, the time-varying radiation conveys position information associated with different portions of the feature.

[0016] In some embodiments, the patterned substrate is configured to be scanned by a radiation source, and the modulator is configured such that as the substrate moves relative to the radiation source to generate time-varying radiation, reflected or transmitted radiation received from different portions is transmitted to the radiation sensor. In some embodiments, the patterned substrate is configured to remain stationary relative to the radiation source, and the modulator is configured to generate time-varying radiation by sequentially selecting reflected or transmitted radiation from different portions and transmitting it to the radiation sensor.

[0017] In some embodiments, the system includes an imaging lens configured to receive radiation from the feature and direct the received radiation toward the modulator.

[0018] In some embodiments, the system includes a collection lens configured to receive the time-varying radiation from the modulator and direct the time-varying radiation toward the radiation sensor.

[0019] In some embodiments, the system includes a color demultiplexer configured to receive the time-varying radiation from the modulator and separate the time-varying radiation into different signals for different color radiation. In some embodiments, the radiation sensor includes different detectors for different color radiation.

[0020] In some embodiments, the system includes a polarizing beam splitter configured to facilitate detection of radiation having various polarizations.

[0021] In some embodiments, the system includes one or more processors configured to determine an alignment check position or an overlay check position of the feature based on the metrology signal.

[0022] In some embodiments, the one or more processors are configured to adjust a semiconductor device manufacturing process based on the metrology signal.

[0023] According to another embodiment, a measurement method including one or more of the above operations is provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The above aspects and other aspects and features will become apparent to those of ordinary skill in the art upon reviewing the following description of specific embodiments in conjunction with the accompanying drawings.

[0025] Figure 1 A lithographic apparatus according to an embodiment is schematically depicted.

[0026] Figure 2 Embodiments of a lithocell or cluster according to embodiments are schematically depicted.

[0027] Figure 3 An example inspection system according to an embodiment is schematically depicted.

[0028] Figure 4 An example metrology technique according to an embodiment is schematically depicted.

[0029] Figure 5 The diagram illustrates the relationship between a radiation illumination spot and a measurement target of an inspection system according to an embodiment.

[0030] Figure 6 A measurement method according to an embodiment is illustrated.

[0031] Figure 7 A metrology system including a modulator according to an embodiment is illustrated.

[0032] Figure 8 is a block diagram of an example computer system according to an embodiment. DETAILED DESCRIPTION

[0033] In semiconductor device manufacturing, determining alignment typically involves determining the position of an alignment mark (or marks) in a semiconductor device structural layer. Alignment is typically determined by irradiating the alignment mark with radiation and comparing the characteristics of different diffraction order radiation reflected from the alignment mark. Similar techniques are used to measure overlay and / or other parameters. To meet the needs of increasingly smaller node sizes, increasingly smaller metrology (e.g., alignment, overlay, etc.) marks with increased measurement accuracy and robustness are needed. Smaller marks facilitate the placement of multiple marks in a limited area, placing marks closer to the substrate edge and / or other locations.

[0034] A challenge in measuring features in patterned substrates is that the spot size of the radiation used for inspection often overlaps other uncontrolled structures, such as other alignment marks, overlay targets, and / or other product features. This creates noise or other unwanted portions of the measurement signal that can overwhelm desired portions of the signal (e.g., those corresponding to the desired metrology target). The present systems and methods overcome this and other difficulties by modulating the radiation received from the target metrology mark, which helps obtain measurement information from the desired structure while excluding unwanted information from surrounding structures.

[0035] As mentioned above, advantageously, the systems and methods described herein facilitate broad-spectrum metrology for a variety of metrology mark types, including these increasingly smaller alignment marks. The systems and methods described herein are robust and can be used for one- and two-dimensional (1D and 2D) marks having a range of pitches, can facilitate mark area selection and / or defect removal / analysis, can be used to analyze polychromatic radiation, and / or have other applications.

[0036] The systems and methods described herein utilize a modulator such as a spatial light modulator (SLM). Alignment marks (as an example of measurement marks) can be projected onto the SLM through an imaging lens. The pattern sequence on the SLM modulates the incoming image and the reflected energy collected by the collection lens, and a time-varying signal can be generated from a single detector or an array of detectors. A color demultiplexer can be added to separate signals of different wavelengths and direct them to corresponding detectors to allow simultaneous multi-color measurements. The alignment marks can be irradiated in static or scanning mode. The combination of varying mark positions and SLM patterns allows a variety of signals to be generated for alignment position measurement. Moreover, the SLM can be easily adapted to the size of the region of interest and the mark.

[0037] By way of brief introduction, the following description generally relates to semiconductor device manufacturing and patterning processes. More specifically, the following paragraphs describe several components of systems and / or related systems. As described above, these systems and methods can be used to measure alignment, for example, in semiconductor device manufacturing processes, or for other operations.

[0038] Although specific reference may be made herein to alignment measurement and fabrication of integrated circuits (ICs) of semiconductor devices, it should be understood that the description has many other possible applications. For example, it may be used to measure overlay and / or other parameters. It may be used in the fabrication of integrated optical systems, guidance and detection patterns for magnetic domain memories, liquid crystal display panels, thin film magnetic heads, and the like. One skilled in the art will appreciate that in the context of such alternative applications, any use of the terms "reticle," "wafer," or "die" herein should be considered interchangeable with the more general terms "mask," "substrate," and "target portion," respectively.

[0039] The term "projection optics" should be broadly interpreted to cover various types of optical systems, including, for example, refractive optics, reflective optics, apertures and catadioptric optics. The term "projection optics" may also include components that operate according to any of these design types to collectively or individually direct, shape or control a projection beam of radiation. The term "projection optics" may include any optical component in a lithographic projection apparatus, regardless of where the optical component is located in the optical path of the lithographic projection apparatus. Projection optics may include optical components for shaping, conditioning and / or projecting radiation from a source before it passes through a pattern forming device and / or optical components for shaping, conditioning and / or projecting radiation after it passes through a pattern forming device. Projection optics typically do not include a source and a pattern forming device.

[0040] Figure 1 An embodiment of a lithographic apparatus LA is schematically depicted. The apparatus comprises an illumination system (illuminator) IL configured to condition a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation); a support structure (e.g., mask table) MT constructed to support a patterning device (e.g., mask) MA and coupled to a first positioner PM configured to accurately position the patterning device according to certain parameters; a substrate table (e.g., wafer stage) WT (e.g., WTa, WTb, or both) configured to hold a substrate (e.g., a resist-coated wafer) W and coupled to a second positioner PW configured to accurately position the substrate according to certain parameters; and a projection system (e.g., refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by the patterning device 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 may be reflective (for example using a programmable mirror array or using a reflective mask).

[0041] The illuminator IL receives a radiation beam from a radiation source SO. The source and the lithographic apparatus may be separate entities, for example when the source is an excimer laser. In this case, the source is not considered to form part of the lithographic apparatus, and the radiation beam is transferred from the source SO to the illuminator IL with the aid of a beam delivery system BD comprising, for example, suitable directing mirrors and / or a beam expander. In other cases, the source may be an integral part of the apparatus, for example when the source is a mercury lamp. The source SO and illuminator IL, and, if desired, the beam delivery system BD, may be referred to as a radiation system.

[0042] The illuminator IL may modify the intensity distribution of the beam. The illuminator may be arranged to limit the radial extent of the radiation beam so that the intensity distribution is non-zero within an annular region in a pupil plane of the illuminator IL. Additionally or alternatively, the illuminator IL may be operable to limit the distribution of the beam in the pupil plane so that the intensity distribution is non-zero in a plurality of equally spaced sectors in the pupil plane. The intensity distribution of the radiation beam in the pupil plane of the illuminator IL may be referred to as an illumination pattern.

[0043] The illuminator IL may include an adjuster AM configured to adjust the (angular / spatial) intensity distribution of the beam. Typically, at least the outer and / or inner radial extent (generally referred to as σ outer and σ inner, respectively) of the intensity distribution in the pupil plane of the illuminator 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 extent of sectors in the pupil plane in which the intensity distribution is non-zero. By adjusting the intensity distribution of the beam in the pupil plane of the illuminator, different illumination modes can be achieved. For example, by limiting the radial and angular extent of the intensity distribution in the pupil plane of the illuminator IL, the intensity distribution can have a multipolar distribution, such as, for example, a dipole, quadrupole, or hexapole distribution. For example, the desired illumination mode can be obtained by inserting an optical device that provides the illumination mode into the illuminator IL or by using a spatial light modulator.

[0044] The illuminator IL can be operable to change the polarization of the beam and can be 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 a polarization mode. Using different polarization modes can allow greater contrast to be achieved in the image formed on the substrate W. The radiation beam can be unpolarized. Alternatively, the illuminator can be arranged to linearly polarize the 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 can be different in different regions in the pupil plane of the illuminator IL. The polarization state of the radiation can be selected according to the illumination mode. For a multipolar illumination mode, the polarization of each pole of the radiation beam can generally be perpendicular to the position vector of the pole in the pupil plane of the illuminator IL. For example, for a dipole illumination mode, the radiation can be linearly polarized in a direction substantially perpendicular to a line bisecting 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 illumination mode, the radiation in each sector of the pole can be linearly polarized in a direction substantially perpendicular to a line bisecting the sector. This polarization mode can be referred to as XY polarization. Similarly, for a hexapole illumination mode, the radiation in the sector of each pole can be linearly polarized in a direction substantially perpendicular to a line bisecting the sector. This polarization mode can be referred to as TE polarization.

[0045] Additionally, the illuminator IL typically includes various other components, such as an integrator IN and a condenser CO. The illumination system may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic or other types of optical components, or any combination thereof, for directing, shaping or controlling the radiation.

[0046] The illuminator thus provides a conditioned radiation beam B having a desired uniformity and intensity distribution in its cross-section.

[0047] The support structure MT supports the patterning device in a manner that depends on the orientation of the patterning device, the design of the lithographic apparatus, and other conditions such as, for example, whether the patterning device is held in a vacuum environment. The support structure can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device. The support structure can be a frame or a table, for example, which can be fixed or movable as required. The support structure can ensure that the patterning device is located at a desired position, for example relative to a projection system. Any use of the term "reticle" or "mask" can be considered synonymous with the more general term "patterning device."

[0048] The term "patterning device" should be broadly interpreted as referring to any device that can be used to impart a pattern in a target portion of a substrate. In embodiments, the patterning device is any device that can be used to impart a radiation beam with a pattern in its cross-section so as to create a pattern in the target portion of the substrate. It should be noted that the pattern imparted to the radiation beam may not exactly correspond to the desired pattern in the target portion of the substrate, for example if the pattern includes phase-shifting features or so-called assist features. Typically, the pattern imparted to the radiation beam will correspond to a specific functional layer in a device (such as an integrated circuit) being created in the target portion of the device.

[0049] Patterning devices can be transmissive or reflective. Examples of patterning devices include masks, programmable mirror arrays, and programmable LCD panels. Masks are well known in lithography and include types such as binary, alternating phase-shift, and attenuated phase-shift, as well as various hybrid mask types. An example of a programmable mirror array employs a matrix arrangement of small mirrors, each of which can be individually tilted to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam that is reflected by the mirror matrix.

[0050] The term "projection system" should be interpreted broadly as covering any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems or any combination thereof, as appropriate to the exposure radiation used or other factors such as the use of immersion liquid or the use of a vacuum. Any use of the term "projection lens" may be considered synonymous with the more general term "projection system".

[0051] The projection system PS may include multiple optical (e.g., lens) elements and may also include an adjustment mechanism that is configured to adjust one or more optical elements to correct for aberrations (phase variations across the pupil plane across 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 whose optical axis extends in the z-direction. The adjustment mechanism may be operable to perform any combination of: displacing one or more optical elements; tilting one or more optical elements; and / or deforming one or more optical elements. The displacement of the optical elements may be in any direction (x, y, z, or a combination thereof). Although rotation about the z-axis can be used for non-rotationally symmetric aspheric optical elements, the tilt of the optical element is typically out of a plane perpendicular to the optical axis by rotating about axes in the x and / or y directions. Deformations of the optical element may include low-frequency shapes (e.g., astigmatism) and / or high-frequency shapes (e.g., freeform aspheric surfaces). Deformation of the optical element can be performed, for example, by applying forces on one or more sides of the optical element using one or more actuators and / or heating one or more selected regions of the optical element using one or more heating elements. Typically, it may not be possible to adjust the projection system PS to correct for apodization (transmission variations in the pupil plane). When designing a patterning device (e.g., a mask) MA for a lithographic apparatus LA, a transmission map of the projection system PS can be used. Using computational lithography techniques, the patterning device MA can be designed to at least partially correct for apodization.

[0052] The lithographic apparatus may be of a type having two (dual stage) or more work tables (e.g. two or more substrate tables WTa, WTb, two or more patterning device tables, a substrate table WTa and a work table WTb located below the projection system without a dedicated substrate, e.g. to facilitate measurement and / or cleaning, etc.). In such a "multi-stage" machine, the additional tables may be used in parallel, or preparatory steps may be performed on one or more work tables while one or more other tables are being used for exposure. For example, alignment measurements using the alignment sensor AS and / or level (height, tilt, etc.) measurements using the level sensor LS may be performed.

[0053] The lithographic apparatus may also be of a type in which at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, such as water, to fill the space between the projection system and the substrate. Immersion liquid may also be applied to other spaces in the lithographic apparatus, such as the space between the patterning device and the projection system. Immersion techniques are well known in the art to increase the numerical aperture of the projection system. The term "immersion" 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.

[0054] In operation of the lithographic apparatus, a radiation beam is conditioned and provided by an illumination system IL. A radiation beam B is incident on a patterning device (e.g. a mask) MA, which is held on a support structure (e.g. a mask table) MT, and is patterned by the patterning device. After traversing the patterning device MA, the radiation beam B passes through a projection system PS which focuses the beam onto a target portion C of the substrate W. With the aid of a second positioner PW and a position sensor IF (e.g. an interferometric device, a linear encoder, a 2D encoder or a capacitive sensor), the substrate table WT can be accurately moved, for example to position different target portions C in the path of the radiation beam B. Similarly, a first positioner PM and a further position sensor (not in the position sensor) are used, for example after mechanical retrieval from a mask library or during a scan. Figure 1 The support structure MT and the substrate table W may be aligned using patterning device alignment marks M1, M2 and substrate alignment marks P1, P2. Although the substrate alignment marks shown occupy dedicated target portions, they may be located in the space between target portions (these are known as scribe alignment marks). Similarly, where more than one die is provided on the patterning device MA, the patterning device alignment marks may be located between the dies.

[0055] The depicted apparatus can be used in at least one of the following modes. In step mode, the support structure MT and substrate table WT remain essentially stationary while a pattern imparted to the radiation beam is projected onto a target portion C at one time (i.e., a single static exposure). The substrate table WT is then shifted in the X and / or Y direction so that a different target portion C can be exposed. In step mode, the maximum size of the exposure field limits the size of the target portion C imaged in a single static exposure. In scan mode, the support structure MT and substrate table WT are scanned synchronously while a pattern imparted to the radiation beam is projected onto a target portion C (i.e., a single dynamic exposure). The speed and direction of the substrate table WT relative to the support structure MT can be determined by the (de-)magnification and image reversal characteristics of the projection system PS. In scan mode, the maximum size of the exposure field limits the width of the target portion (in the non-scanning direction) in a single dynamic exposure, while the length of the scanning motion determines the height of the target portion (in the scanning direction). In another mode, the support structure MT remains essentially stationary, thereby maintaining the programmable patterning device, while the pattern imparted to the radiation beam is projected onto the target portion C, and the substrate table WT is moved or scanned. In this mode, typically a pulsed radiation source is employed and the programmable patterning device is updated as required after each movement of the substrate table WT or between successive radiation pulses during a scan. This mode of operation can be readily applied to maskless lithography, which utilizes a programmable patterning device (such as a programmable mirror array of the type mentioned above).

[0056] Combinations and / or variations on the above-described modes of use or entirely different modes of use may also be employed.

[0057] The substrate may be processed before or after exposure, for example in a track (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) or in a metrology or inspection tool. Where applicable, the present disclosure may be applied to such and other substrate processing tools. Furthermore, a substrate may be processed more than once, for example to create a multi-layer IC, so that the term substrate may also refer to a substrate that already includes multiple processed layers.

[0058] The terms “radiation” and “beam” as used with respect to lithography encompass all types of electromagnetic radiation, including ultraviolet (UV) or deep ultraviolet (DUV) radiation (e.g., having a wavelength of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and extreme ultraviolet (EUV) radiation (e.g., having a wavelength in the range of 5 nm to 20 nm), as well as particle beams, such as ion beams or electron beams.

[0059] The various patterns on or provided by a pattern forming device can have different process windows, i.e., the space of process variables under which the pattern will be produced within specifications. Examples of pattern specifications related to potential system defects include checking for necking, line pullback, line thinning, CD, edge placement, overlap, anti-top loss, anti-bite and / or bridging. The process window of a pattern on a pattern forming device or a region thereof can be obtained by merging (e.g., overlaying) the process windows of each individual pattern. The boundaries of the process window of a group of patterns include the boundaries of the process windows of some of the individual patterns. In other words, these individual patterns limit the process window of the group of patterns.

[0060] like Figure 2 As shown, the lithography apparatus LA can form part of a lithography cell LC, sometimes also referred to as a lithography unit or cluster, which also includes apparatus for performing pre- and post-exposure processes on substrates. Conventionally, these include one or more spin coaters SC for depositing one or more resist layers, one or more developers for developing the exposed resist, one or more cooling plates CH, and / or one or more bake plates BK. A substrate handler or robot RO picks up one or more substrates from input / output ports I / O1, I / O2, moves them between the different process apparatuses, and then delivers them to a loading station LB of the lithography apparatus. These apparatuses, often collectively referred to as tracks, are controlled by a track control unit TCU, which is itself controlled by a monitoring system SCS, which also controls the lithography apparatus via the lithography control unit LACU. Thus, the different apparatuses can be operated to maximize throughput and processing efficiency.

[0061] In order to ensure that substrates exposed by a lithographic apparatus are correctly and consistently exposed and / or to monitor a portion of a patterning process (e.g., a device manufacturing process) that includes at least one pattern transfer step (e.g., an optical lithography step), it is desirable to inspect the substrate or other object to measure or determine one or more properties, such as alignment, overlay (e.g., between structures in overlaid layers or between structures in the same layer, which may be provided to the layers separately by, for example, a double patterning process), line thickness, critical dimension (CD), focus shift, material properties, etc. Therefore, the manufacturing facility where the litho cell LC is located typically also includes a metrology system that measures some or all of the substrates W ( Figure 1 ) or other objects in the lithocell. The metrology system may be part of the lithocell LC, for example it may be a lithographic apparatus LA (such as an alignment sensor AS ( Figure 1 )).

[0062] The one or more measured parameters may include, for example, alignment, overlay between successive layers formed in or on a patterned substrate, critical dimensions (CDs) of features formed in or on the patterned substrate (e.g., critical line widths), focus or focus error of an optical lithography step, dose or dose error of an optical lithography step, optical aberrations of an optical lithography step, etc. The measurement is performed on a dedicated metrology target provided on the substrate. The measurement may be performed after resist development but before etching, after etching, after deposition, and / or at other times.

[0063] There are a variety of techniques for measuring structures formed in patterning processes, including the use of scanning electron microscopes, image-based measurement tools and / or various specialized tools. As discussed above, a rapid and non-invasive form of specialized inspection tool is one in which a radiation beam is directed onto a target on the surface of a substrate and the properties of the scattered (diffraction / reflection) beam are measured. By evaluating one or more properties of the radiation scattered by the substrate, one or more properties of the substrate can be determined. Traditionally, this can be referred to as diffraction-based measurement. One such application of such diffraction-based measurement is alignment measurement. For example, alignment can be measured by comparing portions of a diffraction spectrum (e.g., comparing different diffraction orders in the diffraction spectrum of a periodic grating).

[0064] Thus, in a device fabrication process (e.g., a patterning process or a lithography process), a substrate or other object may be subjected to various types of measurements during or after the process. The measurements may determine whether a particular substrate is defective, may establish adjustments to the process and the equipment used in the process (e.g., aligning two layers on a substrate or aligning a patterning device to a substrate), may measure the performance of the process and the equipment, or may be used for other purposes. Examples of measurements include optical imaging (e.g., optical microscopy), non-imaging optical measurements (e.g., diffraction-based measurements, such as ASML YieldStar metrology tools, ASML SMASH metrology systems), mechanical measurements (e.g., profiling using a stylus, atomic force microscope (AFM)), and / or non-optical imaging (e.g., scanning electron microscope (SEM)).

[0065] The measurement results can be provided directly or indirectly to the monitoring system SCS. If an error is detected, adjustments can be made to the exposure of subsequent substrates (especially if the inspection can be completed quickly enough so that one or more other substrates of the batch are still to be exposed) and / or to subsequent exposures of the exposed substrate. Moreover, already exposed substrates can be stripped and reworked to improve yield, or discarded to avoid further processing of substrates known to be faulty. In the event that only some target portions of the substrate are faulty, further exposures can be performed only on those target portions that meet the specifications. Other manufacturing process adjustments are also under consideration.

[0066] The metrology system can be used to determine one or more properties of a substrate structure, in particular how one or more properties vary between different substrate structures or how different layers of the same substrate structure vary from layer to layer. The metrology system can be integrated into the lithographic apparatus LA or lithocell LC, or can be a standalone device.

[0067] In order to achieve the measurement, one or more targets are typically provided specifically on the substrate. For example, the target may include alignment marks and / or other targets. Typically, the target is specially designed and may include a periodic structure. For example, the target on the substrate may include one or more 1D periodic structures (e.g. geometric features, such as a grating), which are printed so that after development, the periodic structural features are formed by solid resist lines. As another example, the target may include one or more 2D periodic structures (e.g. gratings), which are printed so that after development, the one or more periodic structures are formed by solid resist columns or vias in the resist. Alternatively, the bars, columns or vias may be etched into the substrate (e.g. etched into one or more layers on the substrate).

[0068] Figure 3 An example inspection system 10 is depicted that can be used to detect alignment and / or perform other metrology operations. It includes a radiation source 2 that projects or otherwise irradiates radiation onto a substrate W (which may typically include alignment marks, for example). The redirected radiation is passed to a radiation sensor such as a spectrometer detector 4 and / or other sensor that measures the spectrum (intensity according to wavelength) of the specularly reflected and / or diffracted radiation, such as, for example, Figure 4 The sensor may generate an alignment signal conveying alignment data indicative of the nature of the reflected radiation. From this data, the structure or profile generating the detected spectrum may be reconstructed by one or more processors PRO, a generalized example of which is Figure 4 As shown, or can be reconstructed by other operations. Note that these are generalized examples. Typically, illumination of a target such as an alignment mark is performed orthogonally to the target and / or mark, rather than at the angles shown in these figures.

[0069] and Figure 1 Like the lithographic apparatus LA in FIG. 1 , one or more substrate tables ( Figure 4 ) to hold the substrate W during the measurement operation. The substrate table or tables may be similar in form to Figure 1The substrate tables WT (WTa or WTb or both) of the inspection system 10 are similar or identical. In examples where the inspection system 10 is integrated with a lithographic apparatus, they may even be identical substrate tables. Coarse and fine positioners may be provided and configured to accurately position the substrate with respect to the measuring optical system. Various sensors and actuators are provided, for example to acquire the position of a target portion of interest of the structure (e.g. an alignment mark) and to bring it into position under the objective lens. Typically, a number of measurements will be made of the target portion of the structure at different positions on the substrate W. The substrate support may be moved in the X and Y directions to acquire different targets and 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 is placed in different positions relative to the substrate when, for example, the optical system may in practice remain essentially stationary (typically in the X and Y directions, but possibly also in the Z direction) and the substrate moves. As long as the relative position of substrate and optical system is correct, it is in principle unimportant which of these is moving, or whether both are moving, or a combination in which part of the optical system is moving (e.g. in Z and / or tilt direction) while the rest of the optical system is stationary and the substrate is moving (e.g. in X and Y direction, but optionally also in Z and / or tilt direction).

[0070] For typical alignment measurements, the target (portion) 30 on the substrate W may be a 1D grating that is printed such that after development, the bars are formed of solid resist lines (which may be covered by a deposited layer, for example) and / or other materials. Alternatively, the target 30 may be a 2D grating that is printed such that after development, the grating is formed of solid resist pillars and / or other features in the resist.

[0071] The bars, pillars, vias, and / or other features may be etched into or onto the substrate (e.g., etched into one or more layers on the substrate), deposited on the substrate, covered by a deposited layer, and / or have other properties. Target (portion) 30 (e.g., bars, pillars, vias, etc.) is sensitive to process variations in the patterning process (e.g., optical aberrations in a lithographic projection apparatus (such as a projection system), focus variations, dose variations, etc.), such that process variations manifest as variations in target 30. Thus, measurement data from target 30 may be used to determine adjustments to one or more manufacturing processes and / or used as a basis for making actual adjustments.

[0072] For example, the measurement data from target 30 may indicate the alignment of a semiconductor device layer. The measurement data from target 30 may be used (e.g., by one or more processors) to determine one or more semiconductor device manufacturing process parameters based on the alignment, and to determine adjustments to semiconductor device manufacturing equipment based on the one or more determined semiconductor device manufacturing process parameters. In some embodiments, this may include, for example, stage position adjustments, or may include determining adjustments to mask design, metrology target (e.g., alignment mark) design, semiconductor device design, radiation intensity, radiation incident angle, radiation wavelength, pupil size and / or shape, resist material, and / or other process parameters.

[0073] Angle-resolved scatterometry can be used to measure the asymmetry of features in products and / or resist patterns. A particular application of asymmetry measurement is calibration measurement. For example, the use of Figure 3 The concepts underlying asymmetry measurement using system 10 are incorporated herein in their entirety. Briefly, for alignment measurements, the positions of diffraction orders in the target's diffraction spectrum are determined by the target's periodicity (e.g., alignment marks). The asymmetry of the diffraction spectrum indicates the asymmetry of the individual features comprising the target. For example, any region, from a large portion of the exposure field to the entire exposure field, is a useful region for more accurate intra-field alignment fitting.

[0074] Figure 5 A plan view of a typical target (eg, alignment mark) 30 is shown and Figure 4 The range of the radiation illumination spot S in the system. Typically, in order to obtain a diffraction spectrum that is not disturbed by surrounding structures, in an embodiment, the target 30 is a periodic structure (e.g., a grating) that is larger than the width (e.g., diameter) of the illumination spot S. The width of the spot S can be smaller than the width and length of the target. In other words, the target is "underfilled" by the illumination, and the diffraction signal is substantially unaffected by any signal from product features other than the target itself. For example, the illumination arrangement can be configured to provide uniform intensity illumination on the back focal plane of the objective lens. Alternatively, the illumination can be limited to the on-axis direction or the off-axis direction, for example, by including an aperture in the illumination path.

[0075] Figure 6 The measurement method 600 is shown. In some embodiments, the method 600 is performed as part of a semiconductor device manufacturing process. In some embodiments, for example, one or more operations of the method 600 may be performed in a Figure 3 and Figure 4 (and described below Figure 7 ) system 10, a computer system (eg Figure 86. In some embodiments, method 600 includes irradiating (operation 602) features in a patterned substrate with radiation, modulating (operation 604) the radiation received from the features to generate time-varying radiation, generating (operation 606) a measurement signal based on the received time-varying radiation, and / or other operations. Method 600 is described below in the context of alignment, but this is not intended to be limiting. Method 600 can generally be applied to many different processes.

[0076] The operations of method 600 presented below are intended to be illustrative. In some embodiments, method 600 may be performed with one or more additional operations not described and / or without one or more of the operations discussed. For example, in some embodiments, method 600 may include additional operations including determining adjustments to a semiconductor device manufacturing process. Additionally, the operations of method 600 may be performed in Figure 6 The order illustrated in and described below is not intended to be limiting.

[0077] In some embodiments, one or more portions of method 600 may be implemented in and / or controlled by one or more processing devices (e.g., digital processors, analog processors, digital circuits designed to process information, analog circuits designed to process information, state machines, and / or other mechanisms that electronically process information, see the description of processor PRO). The one or more processing devices may include one or more devices that perform some or all of the operations of method 600 in response to instructions electronically stored on an electronic storage medium. The one or more processing devices may include one or more devices that are configured through hardware, firmware, and / or software to be specifically designed to perform one or more operations of method 600 (e.g., see the description of processor PRO below). Figure 8 Related discussions).

[0078] Operation 602 includes irradiating a feature in a patterned substrate with radiation. The feature may include metrology marks and / or other features on the patterned substrate. In some embodiments, the metrology marks are associated with alignment and / or overlay measurements of the patterned substrate. For example, the metrology marks may be or include specialized alignment marks, such as a diffraction grating. The radiation may be diffracted by the diffraction grating. In some embodiments, the feature includes one or more structures in the patterned substrate capable of providing a diffraction signal. In some embodiments, the feature may be any structure in the pattern design layout capable of generating a wide-angle diffraction signal.

[0079] Features can be included, for example, in a substrate layer in a semiconductor device structure. In some embodiments, the features include geometric features such as 1D or 2D features and / or other geometric features. By way of several non-limiting examples, the features can include lines, edges, a series of fine-pitch lines and / or edges and / or other features. In some embodiments, for example, the fine pitch has a pitch size of less than one micron. In some embodiments, the length of the features (e.g., lines, edges, series, etc.) spans a measurement area of ​​interest (e.g., an area larger than a normal target, such as the width / length of a die, but up to the entire wafer diameter).

[0080] The radiation can have a target wavelength and / or wavelength range, a target intensity, and / or other characteristics. The target wavelength and / or wavelength range, target intensity, etc. can be entered and / or selected by the user, determined by the system based on previous alignment measurements, and / or determined in other ways. In some embodiments, the radiation includes light and / or other radiation. In some embodiments, the light includes visible light, infrared light, near-infrared light, and / or other light. In some embodiments, the radiation can be any radiation suitable for interferometry.

[0081] Radiation can be provided by a radiation source (e.g. Figure 3 and Figure 4 In some embodiments, radiation can be directed by a radiation source (e.g., via one or more lenses, modulators, and / or other components) onto a feature, a sub-portion (e.g., a portion less than the entirety) of a feature, multiple features, and / or otherwise onto a substrate.

[0082] Operation 604 includes modulating the radiation received from the feature to generate time-varying radiation. The modulation can be performed by a modulator and / or other components. In some embodiments, the modulator is a spatial light modulator (SLM) and / or other modulator. Generally, an SLM is any device configured to cause some form of spatial variation in a radiation beam. The SLM can control whether radiation is transmitted (e.g., whether the radiation is turned on or off), which parts of the radiation are transmitted, the intensity of the radiation (e.g., the intensity level between on and off), and / or perform other modulations. In some embodiments, the SLM can be electronically controlled by a processor (see processor PRO described herein), or have parts that are electronically controlled by a processor, or mechanically controlled by actuators and / or other mechanical components, can be static, or have static parts, and / or have other configurations. In some embodiments, the SLM can be and / or have transmissive or reflective parts. For example, in some embodiments, the SLM includes a sequence of binary or grayscale patterns configured to modulate the incoming radiation.

[0083] By way of non-limiting example, the SLM can be a digital micromirror device (DMD). The DMD has a plurality of microscopic mirrors, for example, arranged in an array. The mirrors can be individually moved (e.g., electronically controlled by a processor PRO via electrodes, hinges, springs, and / or other components associated with each individual mirror) so that selected radiation from certain mirrors can be reflected toward a radiation sensor. Each mirror on the DMD can be independently modulated in a time series to provide grayscale modulation of the incoming radiation. For example, the mirrors can have a very high refresh rate (tens of kilohertz), which allows for the generation of rapidly modulated signals.

[0084] In some embodiments, the modulation includes continuously transmitting one or more sub-portions of the received radiation over time. The time-varying radiation conveys position information associated with different portions of the feature. The different portions of the feature can be different regions of interest and / or other portions. For example, in some embodiments, the patterned substrate is configured to be scanned by a radiation source, and the modulator is configured such that as the substrate moves relative to the radiation source to form the time-varying radiation, reflected or transmitted radiation received from different portions (e.g., sub-portions of the received radiation corresponding to different portions of the feature) is transmitted to the radiation sensor.

[0085] Scanning can include rastering radiation across a feature so that different portions of the feature are irradiated at different times. In some embodiments, scanning is performed at a predefined scanning speed for a given sampling rate. The predefined scanning speed and / or the given sampling rate are determined based on the size of the feature and / or other information. In some embodiments, the predefined scanning speed and / or the given sampling rate are adjustable based on the size and / or other characteristics of the feature. Conversely, in some embodiments, the size of a feature that can be scanned is determined based on a ratio of the predefined scanning speed to the given sampling rate.

[0086] In some embodiments, the modulator can be configured so that all or only certain sub-portions of the radiation are transmitted for scanning. For example, at a given moment during a scan, the modulator can be configured to transmit all radiation for the entire portion of the measurement mark visible at that time, or to transmit certain sub-portions of the radiation for a specific region of interest visible at that time (e.g., using radiation from certain mirrors of the DMD). The sub-portion of the radiation can be configured so that, for example, it corresponds to a smaller area of ​​the measurement mark, radiation of certain wavelengths, radiation of certain diffraction orders, radiation of a certain polarization, or other sub-portion.

[0087] As another example, in some embodiments, the patterned substrate is configured to remain stationary relative to the radiation source, and the modulator is configured to generate time-varying radiation by sequentially selecting reflected or transmitted radiation from different portions and transmitting it to the radiation sensor (e.g., using different mirrors of a DMD, mirrors moved to different positions, etc.). For example, sequentially selecting reflected or transmitted radiation from different portions and transmitting it to the radiation sensor can simulate scanning. For example, the modulator can be configured to sequentially transmit sub-portions of the radiation corresponding to smaller areas of the metrology mark (e.g., the portions described above), radiation of certain wavelengths, radiation of certain diffraction orders, radiation of certain polarizations, or other sub-portions.

[0088] In some embodiments, the characteristics of the transmitted radiation (e.g., wavelength, intensity, etc.) can be varied over time by the modulator (whether in scanning or stationary mode). This can produce and / or supplement time-varying radiation for analysis. This can also facilitate analyzing individual portions of a feature, comparing one portion of a feature to another portion and / or other features, and / or performing other analyses.

[0089] Operation 606 includes generating a measurement signal based on the received time-varying radiation and / or other information. The measurement signal may be generated by a radiation sensor (e.g., such as Figure 3 Operation 606 includes detecting reflected and / or transmitted radiation from the feature. Detecting such radiation may include detecting one or more phase and / or amplitude (intensity) shifts in radiation received from one or more geometric features. The one or more phase and / or amplitude shifts may correspond to one or more dimensions of the feature. For example, the phase and / or amplitude of reflected radiation from one side of the feature may be different relative to the phase and / or amplitude of reflected radiation from the other side of the feature.

[0090] Detecting one or more phase and / or amplitude (intensity) shifts in radiation from a feature includes measuring local phase shifts (e.g., local phase increments) and / or amplitude changes corresponding to different portions of the feature. For example, radiation from a specific region of a feature may include a sinusoidal waveform having a particular phase and / or amplitude. Radiation from different regions of a feature may also include sinusoidal waveforms, but with different phases and / or amplitudes. Detecting radiation also includes measuring phase and / or amplitude differences of radiation of different diffraction orders. For example, detecting one or more local phase and / or amplitude shifts can be performed using a Hilbert transform and / or other techniques. Interferometry techniques and / or other operations can be used to measure phase and / or amplitude differences of reflected radiation of different diffraction orders.

[0091] By way of non-limiting example, Figure 7An example measurement system 700 including a modulator 702 and / or other components is shown. The system 700 is similar to the one described above with respect to Figure 3 The system 10 described above is the same as or similar to one or more components of the system 700, and one or more components of the system 10 are similar to and / or the same as one or more components of the system 10 (and Figure 7 10. In some embodiments, one or more components of system 700 may replace, be used in conjunction with, and / or otherwise enhance one or more components of system 10. For example, Figure 7 The modulator 702, imaging lens 704, collection lens 706, color demultiplexer 708, sensor (detector 4), and / or other components are shown. Figure 7 In the case of radiation sources (such as Figure 3 The source 2 shown can generate radiation and direct it to a feature (e.g., target 30) (but Figure 7 There are no repetitions in ).

[0092] The imaging lens 704 is configured to receive radiation 701 from a feature (e.g., target 30, in this example a diffraction grating) and direct the received radiation 701 toward a modulator 702. The collecting lens 706 is configured to receive time-varying radiation 703 from the modulator 702 and direct the time-varying radiation 703 toward a radiation sensor (detector 4). The color demultiplexer 708 is configured to receive the time-varying radiation 703 from the modulator 702 and separate the time-varying radiation 703 into different signals 707, 709, 711 for different colors of radiation. The sensor (detector 4) includes different detectors 4a, 4b, 4c for the different colors of radiation 703. In some embodiments, the system 700 includes a polarization beam splitter configured to facilitate detection of radiation having various polarizations. For example, the polarization beam splitter may be located Figure 7 Any position between the reference numerals 703 and 708, 30 and 704, or 708 and 4a / 4b / 4c.

[0093] In some embodiments, the system 700 includes one or more processors ( Figure 7 Not shown, but see description below Figure 3 and Figure 8 In some embodiments, the one or more processors are configured to control the modulator 702 to modulate the received radiation (e.g., by moving the modulator 702 and / or an actuatable portion of the modulator 702). In some embodiments, the one or more processors are configured to determine an alignment check position or an overlay check position of a feature based on the measurement signal. In some embodiments, the one or more processors are configured to adjust a semiconductor device manufacturing process based on the measurement signal.

[0094] As described above, modulation by the modulator 702 includes continuously transmitting one or more sub-portions of the received radiation over time. Figure 7 In the example, time-varying radiation 703 includes sub-portions 705 (e.g., Figure 7 Sub-portion 705 is generated because the pattern of modulator 702 (e.g., black and white squares in this example) reflects or transmits radiation only from certain overlaid areas of target 30 (e.g., see Figure 7 702). The modulator 702 is configured such that the process is continuously repeated for different portions of the target 30 (and / or other surrounding structures) at later time instances to form the time-varying radiation 703. For example, the sub-portion 705 may change at each successive moment. The continuous repetition may be caused by the modulator 702 when the modulator 702 is configured such that reflected or transmitted radiation received from different portions of the target 30 (e.g., sub-portions of received radiation corresponding to different portions of the feature) is transmitted to the radiation sensor (detector 4) as the substrate moves relative to the radiation source to form the time-varying radiation; when the patterned substrate (and the target 30 in this example) is configured to remain stationary relative to the radiation source and the modulator 702 is configured to generate the time-varying radiation by continuously selecting reflected or transmitted radiation from different portions and transmitting to the radiation sensor (e.g., from different portions of the black and white pattern in this example); and / or some combination of these techniques. For example, the modulator 702 can be configured to sequentially transmit sub-portions of radiation corresponding to smaller areas (e.g., the portion described above), radiation of certain wavelengths, radiation of certain diffraction orders, radiation of certain polarizations, or other sub-portions of the target 30. This flexibility (static or scanning mode, different selectable portions of the metrology mark, different selectable portions of the wavelength spectrum, etc.) can facilitate broad spectrum measurement of various metrology mark types and / or have other advantages.

[0095] Return to Figure 6 , and as described above, operation 606 includes generating a measurement signal based on the detected modulated radiation from the feature. The measurement signal includes measurement information related to the feature. For example, the measurement signal can be an alignment signal including alignment measurement information, an overlay signal including overlay measurement information, and / or other measurement signals. In some embodiments, operation 606 includes determining an alignment check position of the feature based on the measurement signal. The measurement information (e.g., the alignment check position of the feature) can be determined using interferometry principles and / or other principles.

[0096] The measurement signal includes an electronic signal representing and / or otherwise corresponding to the modulated radiation from the feature. For example, the measurement signal may indicate an alignment value of the feature and / or other information. Generating the measurement signal includes sensing the modulated radiation and converting the sensed modulated radiation into the electronic signal. In some embodiments, generating the measurement signal includes sensing different portions of the modulated radiation from different portions and / or different geometries of the feature and combining the different portions of the sensed modulated radiation to form the measurement signal. This sensing and conversion may be performed by a computer program product associated with the measurement signal. Figure 3 、 Figure 4 and Figure 7 The radiation sensor detector 4 and / or the processor PRO shown may be implemented with similar and / or identical components and / or other components.

[0097] In some embodiments, generating the metrology signal may include directly measuring the size of the feature. For example, a scatterometer and / or other system may be used to perform direct size measurements on the feature. In some embodiments, direct size measurements may be used in combination with and / or in place of the local phase and / or amplitude shifts described herein to determine the alignment of the feature. For example, the output size measurements from the scatterometer system may be provided to a processor PRO ( Figure 3 ) and / or other system components that can generate metrology signals based at least in part on output size measurements from the scatterometer system.

[0098] In some embodiments, operation 606 includes determining adjustments to the semiconductor device manufacturing process. In some embodiments, operation 606 includes determining one or more semiconductor device manufacturing process parameters. The one or more semiconductor device manufacturing process parameters can be determined based on one or more detected phase and / or amplitude changes, alignment values ​​indicated by measurement signals, dimensions determined by a scatterometer system, and / or other similar systems and / or other information. The one or more parameters can include parameters of the radiation (radiation used to determine alignment), alignment check locations within features, alignment check locations on semiconductor device structure layers, and / or other parameters. In some embodiments, process parameters can be broadly interpreted to include platform position, mask design, measurement target design, semiconductor device design, radiation intensity (for exposing resist, etc.), radiation incident angle (for exposing resist, etc.), radiation wavelength (for exposing resist, etc.), radiation polarization, pupil size and / or shape, resist material, and / or other parameters.

[0099] For example, radiation parameters used to determine alignment can include wavelength, intensity, angle of incidence, and / or parameters of the radiation. These parameters can be adjusted to better measure features having specific shapes, enhance the intensity of reflected radiation, increase and / or otherwise enhance (e.g., maximize) the phase and / or amplitude shift (if any) of reflected radiation from one region of the feature to the next, and / or for other purposes. This can enable and / or enhance the detection of more subtle deviations, make phase and / or amplitude shifts easier to detect, and / or have other advantages.

[0100] In some embodiments, operation 606 includes determining a process adjustment based on one or more determined semiconductor device manufacturing process parameters, and adjusting semiconductor device manufacturing equipment and / or other operations based on the determined adjustment. For example, if the determined alignment is not within process tolerance, the misalignment may be caused by one or more manufacturing processes whose process parameters have drifted and / or otherwise changed, such that the process no longer produces acceptable devices (e.g., the alignment measurement may violate a threshold of acceptability). One or more new or adjusted process parameters may be determined based on the alignment determination. The new or adjusted process parameters may be configured to cause the manufacturing process to once again produce acceptable devices. For example, the new or adjusted process parameters may cause a previously unacceptable alignment (or misalignment) to be adjusted back to an acceptable range. The new or adjusted process parameters may be compared to existing parameters for a given process. For example, if a difference exists, the difference may be used to determine an adjustment to the equipment used to produce the device (e.g., whether parameter "x" should be increased / decreased / changed so that it matches the new or adjusted version of parameter "x" determined as part of operation 606). In some embodiments, operation 606 may include electronically adjusting the equipment (e.g., based on the determined process parameters). Electronically adjusting a device may include sending electronic signals and / or other communications to the device, for example, which may result in a change to the device. Electronic adjustment may include, for example, changing settings and / or other adjustments on the device.

[0101] Figure 8is 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. The computer system CS also includes a main memory MM, such as a random access memory (RAM) or other dynamic storage device, which is coupled to the bus BS for storing information and instructions to be executed by the processor PRO. The main memory MM can also be used to store temporary variables or other intermediate information during the execution of instructions by the processor PRO. The computer system CS also includes a read-only memory (ROM) ROM or other static storage device coupled to the bus BS for storing static information and instructions of the processor PRO. A storage device SD such as a magnetic disk or optical disk is provided and coupled to the bus BS for storing information and instructions.

[0102] The computer system CS can be coupled to a display DS via a bus BS, such as a cathode ray tube (CRT) or a flat panel or touch panel display, for displaying information to the computer user. An input device ID comprising alphanumeric keys and other keys is coupled to the bus BS for transmitting information and command selections to the processor PRO. Another type of user input device is a cursor control CC, such as a mouse, trackball or cursor direction keys, for transmitting direction information and command selections to the processor PRO and controlling cursor movement on the display DS. 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 a position in a plane. A touch panel (screen) display can also be used as an input device.

[0103] In some embodiments, in response to the processor PRO executing one or more sequences of one or more instructions contained in the main memory MM, the part of one or more methods can be performed by the computer system CS. Such instructions can be read into the main memory MM from another computer-readable medium (such as a storage device SD). Executing the instruction sequence included in the main memory MM causes the processor PRO to perform a process step (operation). One or more processors in a multi-processing arrangement can also be adopted to execute the instruction sequence included in the main memory MM. In some embodiments, hard-wired circuitry can be used instead of software instructions or used in combination with software instructions. Therefore, this description is not limited to any specific combination of hardware circuitry and software.

[0104] The term "computer-readable medium" or "machine-readable medium" refers to any medium that participates in providing instructions to the 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 or magnetic disks, such as storage devices SD. Volatile media include dynamic memory, such as main memory MM. Transmission media include coaxial cables, copper wire, and optical fiber, including the wires that make up the bus BS. Transmission media can also take the form of sound waves or light waves, such as those generated during radio frequency (RF) and infrared (IR) data communications. Computer-readable media can be non-transient, such as floppy disks, foldable disks, hard disks, magnetic tape, any other magnetic medium, CD-ROMs, DVDs, any other optical media, punched cards, paper tape, any other physical medium with a pattern of holes, RAM, PROMs and EPROMs, flash EPROMs, any other memory chips, or memory cartridges. Non-transient computer-readable media can have instructions recorded thereon. When executed by a computer, the instructions can implement any of the described operations. For example, transient computer-readable media can include carrier waves or other propagating electromagnetic signals.

[0105] Various forms of computer-readable media may be involved in carrying one or more sequences of one or more instructions to the processor PRO for execution. For example, the instructions may initially be carried on a disk of a remote computer. The remote computer may load the instructions into its dynamic memory and send the instructions via a telephone line using a modem. A modem local to the computer system CS may receive data on the telephone line and convert the data into an infrared signal using an infrared transmitter. An infrared detector coupled to the bus BS may receive the data carried in the infrared signal and place the data on the bus BS. The bus BS carries the data to the main memory MM, from which the processor PRO retrieves and executes the instructions. Before or after execution by the processor PRO, the instructions received by the main memory MM may optionally be stored on a storage device SD.

[0106] The computer system CS may also include a communication interface CI coupled to the bus BS. The communication interface CI provides a bidirectional data communication coupling with a network link NDL connected to the local network LAN. For example, the communication interface CI may be an integrated services digital network (ISDN) card or a modem to provide a data communication connection to a corresponding type of telephone line. As another example, the communication interface CI may be a local area network (LAN) card to provide a data communication connection to a compatible LAN. A wireless link may also be implemented. In any such implementation, the communication interface CI sends and receives electrical, electromagnetic, or optical signals that carry digital data streams representing various types of information.

[0107] The network link NDL typically provides data communications to other data devices via one or more networks. For example, the network link NDL may provide a connection to a host computer HC via a local network LAN. This may include data communications services provided via the global packet data communications network (now commonly referred to as the "Internet" INT). The local network LAN (Internet) may use electrical, electromagnetic or optical signals that carry digital data streams. The signals through the various networks and the signals on the network data link NDL and through the communication interface CI (carrying digital data to and from the computer system CS) are exemplary forms of carrier waves that transport information.

[0108] The computer system CS can send messages and receive data, including program code, via the network(s), the network data link NDL, and the communication interface CI. In the example of the Internet, the host computer HC can send a request code for an application program via the Internet INT, the network data link NDL, the local network LAN, and the communication interface CI. For example, one such download application can provide all or part of the method described herein. The received code can be executed by the processor PRO upon receipt and / or stored in a storage device SD or other non-volatile storage device for later execution. In this way, the computer system CS can obtain the application code in the form of a carrier wave.

[0109] Various embodiments of the present systems and methods are disclosed in the following list of numbered clauses:

[0110] 1. A metrology system comprising: a radiation source configured to irradiate a feature in a patterned substrate with radiation; a modulator configured to modulate radiation received from the feature to generate time-varying radiation; and a radiation sensor configured to receive the time-varying radiation and generate a metrology signal comprising measurement information related to the feature.

[0111] 2. The system of clause 1 , wherein the feature comprises a measurement mark.

[0112] 3. A system according to any of the preceding clauses, wherein the measurement mark comprises a diffraction grating.

[0113] 4. A system according to any of the preceding clauses, wherein the radiation is diffracted by the diffraction grating.

[0114] 5. The system of any of the preceding clauses, wherein the metrology marks are associated with alignment and / or overlay measurements of the patterned substrate.

[0115] 6. A system according to any of the preceding clauses, wherein the modulator is a spatial light modulator (SLM).

[0116] 7. A system according to any of the preceding clauses, wherein the SLM is a digital micromirror device (DMD).

[0117] 8. A system according to any of the preceding clauses, wherein the SLM comprises a sequence of binary or greyscale patterns configured to modulate incoming radiation.

[0118] 9. A system according to any of the preceding clauses, wherein the SLM is transmissive or reflective.

[0119] 10. The system of any of the preceding clauses, wherein modulation comprises continuously transmitting one or more sub-portions of the received radiation over time.

[0120] 11. A system according to any of the preceding clauses, wherein the time-varying radiation conveys position information associated with different parts of the feature.

[0121] 12. A system according to any of the preceding clauses, wherein the patterned substrate is configured to be scanned by a radiation source and the modulator is configured such that when the substrate moves relative to the radiation source to form the time-varying radiation, reflected or transmitted radiation received from the different portions is transmitted to the radiation sensor.

[0122] 13. A system according to any of the preceding clauses, wherein the patterned substrate is configured to remain stationary relative to the radiation source and the modulator is configured to generate time-varying radiation by continuously selecting reflected or transmitted radiation from different portions and transmitting it to the radiation sensor.

[0123] 14. The system of any preceding clause, further comprising an imaging lens configured to receive radiation from the feature and to direct the received radiation toward the modulator.

[0124] 15. The system of any of the preceding clauses, further comprising a collection lens configured to receive the time-varying radiation from the modulator and direct the time-varying radiation towards the radiation sensor.

[0125] 16. The system of any preceding clause, further comprising a color demultiplexer configured to receive the time-varying radiation from a modulator and to separate the time-varying radiation into different signals for different color radiation.

[0126] 17. The system of any of the preceding clauses, wherein the radiation sensor comprises different detectors for the different colors of radiation.

[0127] 18. The system of any preceding clause, further comprising a polarizing beam splitter configured to facilitate detection of radiation having various polarizations.

[0128] 19. The system of any preceding clause, further comprising one or more processors configured to determine an alignment check position or an overlay check position of the feature based on the metrology signal.

[0129] 20. The system of any preceding clause, wherein the one or more processors are further configured to adjust a semiconductor device manufacturing process based on the metrology signal.

[0130] 21. A measurement method, comprising: using a radiation source to irradiate a feature in a patterned substrate with radiation; using a modulator to modulate the radiation received from the feature to generate time-varying radiation; and using a radiation sensor to receive the time-varying radiation and generate a measurement signal, wherein the measurement signal includes measurement information related to the feature.

[0131] 22. The method of clause 21, wherein the feature comprises a metrology mark.

[0132] 23. A method according to any of the preceding clauses, wherein the metrology mark comprises a diffraction grating.

[0133] 24. A method according to any of the preceding clauses, wherein the radiation is diffracted by the diffraction grating.

[0134] 25. A method according to any of the preceding clauses, wherein the metrology marks are associated with alignment and / or overlay measurements of the patterned substrate.

[0135] 26. A method according to any of the preceding clauses, wherein the modulator is a spatial light modulator (SLM).

[0136] 27. A method according to any of the preceding clauses, wherein the SLM is a digital micromirror device (DMD).

[0137] 28. A method according to any of the preceding clauses, wherein the SLM comprises a sequence of binary or greyscale patterns configured to modulate incoming radiation.

[0138] 29. A method according to any of the preceding clauses, wherein the SLM is transmissive or reflective.

[0139] 30. A method according to any of the preceding clauses, wherein modulating comprises continuously transmitting one or more sub-portions of the received radiation over time.

[0140] 31. A method according to any of the preceding clauses, wherein the time-varying radiation conveys position information relating to different parts of the feature.

[0141] 32. A method according to any of the preceding clauses, wherein the patterned substrate is configured to be scanned by the radiation source and the modulator is configured such that when the substrate moves relative to the radiation source to form time-varying radiation, reflected or transmitted radiation received from the different parts is transmitted to the radiation sensor.

[0142] 33. A method according to any of the preceding clauses, wherein the patterned substrate is configured to remain stationary relative to the radiation source and the modulator is configured to generate the time-varying radiation by continuously selecting reflected or transmitted radiation from different portions and transmitting it to the radiation sensor.

[0143] 34. The method of any preceding clause, further comprising receiving the radiation from the feature with an imaging lens and directing the received radiation toward the modulator.

[0144] 35. The method of any preceding clause, further comprising receiving the time-varying radiation from the modulator with a collection lens and directing the time-varying radiation toward the radiation sensor.

[0145] 36. The method of any preceding clause, further comprising receiving the time-varying radiation from the modulator using a color demultiplexer and separating the time-varying radiation into different signals for different color radiation.

[0146] 37. A method according to any of the preceding clauses, wherein the radiation sensor comprises different detectors for the different colours of radiation.

[0147] 38. The method of any preceding clause, further comprising utilizing a polarizing beam splitter to facilitate detection of radiation having various polarizations.

[0148] 39. The method of any preceding clause, further comprising determining, using one or more processors, an alignment check position or an overlay check position of the feature based on the metrology signal.

[0149] 40. The method of any preceding clause, further comprising adjusting, using the one or more processors, a semiconductor device manufacturing process based on the measurement signal.

[0150] The concepts disclosed herein can be associated with any general imaging system for imaging subwavelength features and may be particularly useful for emerging imaging technologies that can produce shorter and shorter wavelengths. Emerging technologies already in use include EUV (extreme ultraviolet), DUV lithography, which can produce wavelengths of 193 nm using ArF lasers, and even 157 nm using fluorine lasers. Furthermore, EUV lithography can produce wavelengths in the 20 nm to 5 nm range by using synchrotrons or by colliding materials (solid or plasma) with high-energy electrons to produce photons in this range.

[0151] Although the concepts disclosed herein can be used for imaging on substrates such as silicon wafers, it should be understood that the disclosed concepts can be used with any type of lithography imaging system, such as those used for imaging on substrates other than silicon wafers. Additionally, combinations and subcombinations of the disclosed elements can comprise separate embodiments.

[0152] The above description is intended to be illustrative, and not restrictive. It will therefore be apparent to those skilled in the art that modifications may be made as described without departing from the scope of the claims set out below.

Claims

1. A measurement system comprising: a radiation source configured to irradiate features in the patterned substrate with radiation; a modulator configured to modulate radiation received from the feature to generate time-varying radiation; as well as A radiation sensor is configured to receive the time-varying radiation and generate a measurement signal, wherein the measurement signal includes measurement information related to the characteristic.

2. The system of claim 1, wherein the feature comprises a measurement mark.

3. The system of claim 2, wherein the metrology mark comprises a diffraction grating.

4. The system of claim 3, wherein the radiation is diffracted by the diffraction grating.

5. The system according to any one of claims 2 to 4, wherein the metrology marks are associated with alignment and / or overlay measurements of the patterned substrate.

6. The system of any one of claims 1 to 5, wherein the modulator is a spatial light modulator (SLM).

7. The system of claim 6, wherein the SLM is a digital micromirror device (DMD).

8. A system according to claim 6 or 7, wherein the SLM comprises a sequence of binary or greyscale patterns configured to modulate incoming radiation.

9. A system according to any one of claims 6 to 8, wherein the SLM is transmissive or reflective.

10. The system of any one of claims 1 to 9, wherein modulation comprises continuously transmitting one or more sub-portions of the received radiation over time.

11. The system of any one of claims 1 to 10, wherein the time-varying radiation conveys position information associated with different portions of the feature.

12. The system of claim 11 , wherein the patterned substrate is configured to be scanned by the radiation source, and the modulator is configured such that reflected or transmitted radiation received from the different portions is transmitted to the radiation sensor as the substrate moves relative to the radiation source to form the time-varying radiation.

13. The system of claim 11, wherein the patterned substrate is configured to remain stationary relative to the radiation source, and the modulator is configured to generate the time-varying radiation by sequentially selecting reflected or transmitted radiation from the different portions and transmitting it to the radiation sensor.

14. The system of any one of claims 1 to 13, further comprising an imaging lens configured to receive radiation from the feature and direct the received radiation toward the modulator.

15. The system of any one of claims 1 to 14, further comprising a collection lens configured to receive the time-varying radiation from the modulator and direct the time-varying radiation toward the radiation sensor.

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