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WO2024153591A1 - Procédé et appareil de détermination de performances de processus de formation de motifs - Google Patents

Procédé et appareil de détermination de performances de processus de formation de motifs Download PDF

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Publication number
WO2024153591A1
WO2024153591A1 PCT/EP2024/050817 EP2024050817W WO2024153591A1 WO 2024153591 A1 WO2024153591 A1 WO 2024153591A1 EP 2024050817 W EP2024050817 W EP 2024050817W WO 2024153591 A1 WO2024153591 A1 WO 2024153591A1
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WIPO (PCT)
Prior art keywords
patterning process
substrate
performance
image
determining
Prior art date
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PCT/EP2024/050817
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English (en)
Inventor
Maurits Van Der Schaar
Olger Victor ZWIER
Sergey TARABRIN
Vincenzo Giuseppe ZACCA
Shu-jin WANG
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ASML Netherlands BV
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ASML Netherlands BV
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Priority to KR1020257021289A priority Critical patent/KR20250137571A/ko
Priority to CN202480006841.5A priority patent/CN120476348A/zh
Publication of WO2024153591A1 publication Critical patent/WO2024153591A1/fr
Anticipated expiration legal-status Critical
Ceased legal-status Critical Current

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Classifications

    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70425—Imaging strategies, e.g. for increasing throughput or resolution, printing product fields larger than the image field or compensating lithography- or non-lithography errors, e.g. proximity correction, mix-and-match, stitching or double patterning
    • G03F7/70475—Stitching, i.e. connecting image fields to produce a device field, the field occupied by a device such as a memory chip, processor chip, CCD, flat panel display
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/70—Microphotolithographic exposure; Apparatus therefor
    • G03F7/70483—Information management; Active and passive control; Testing; Wafer monitoring, e.g. pattern monitoring
    • G03F7/70605—Workpiece metrology
    • G03F7/70616—Monitoring the printed patterns
    • G03F7/70633—Overlay, i.e. relative alignment between patterns printed by separate exposures in different layers, or in the same layer in multiple exposures or stitching

Definitions

  • the present invention relates apparatuses and methods for determining performance of a patterning process such as a lithographic process. In particular, it relates to determination of a performance of a patterning process based on characteristics of a boundary between first and second regions.
  • a lithographic apparatus is a machine constructed to apply a desired pattern onto a substrate.
  • a lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs).
  • a lithographic apparatus may, for example, project a pattern (also often referred to as “design layout” or “design”) at a patterning device (e.g., a mask) onto a layer of radiation- sensitive material (resist) provided on a substrate (e.g., a wafer).
  • Low-ki lithography may be used to process features with dimensions smaller than the classical resolution limit of a lithographic apparatus.
  • CD kix /NA
  • NA the numerical aperture of the projection optics in the lithographic apparatus
  • CD is the “critical dimension” (generally the smallest feature size printed, but in this case half-pitch)
  • ki is an empirical resolution factor.
  • sophisticated fine-tuning steps may be applied to the lithographic projection apparatus and/or design layout.
  • RET resolution enhancement techniques
  • Patterning of a layer on a substrate may comprise a multiple steps.
  • a patterning device such as a mask
  • the pattern to be exposed may fit into a single mask.
  • the single mask may then be moved across the substrate, to expose the same pattern multiple times onto the same substrate.
  • the pattern to be exposed onto the substrate for example a pattern forming a device, may be too big to fit on a single mask.
  • Several masks, each comprising a different portion of the pattern to be exposed may be moved across the substrate in multiple independent steps. The multiple masks be moved across regions of a substrate, to pattern different portions of the pattern sequentially.
  • This breaking up of a pattern across different regions on a substrate may give rise to positioning errors of the exposed portions of the pattern on the substrate, relative to each other.
  • An exposed pattern may comprise for example alignment and/or magnification errors. Due to the small dimensions of patterned features, high precision and accuracy may be required in positioning different patterned regions relative to each other. Errors in the relative positions may be referred to as stitching errors. Stitching errors may affect the quality of exposed pattern on a substrate, and the resulting yield of the patterning process. It is therefore desirable to provide methods and apparatuses to reduce stitching errors and their negative effects on lithographic patterning processes. Stitching errors may be measured in a multitude of ways as known in the state of the art.
  • Stitching errors may be measured using overlay targets wherein the overlay error is an indication of the stitching error. Stitching errors may be measured with SEM imaging tools wherein the positioning of the imaged features is an indication of the stitching error.
  • SEM imaging tools wherein the positioning of the imaged features is an indication of the stitching error.
  • a method for determining the performance of a patterning process comprising receiving an image of a portion of a substrate, the portion of a substrate comprising a first region comprising a first feature associated with a first patterning process and at least a second region comprising a second feature associated with a second patterning process wherein the first feature and the second feature form the image comprising a Moire pattern when illuminated with radiation and determining the performance of the patterning process based on characteristics of the Moire pattern.
  • an apparatus for determining the performance of a lithographic process comprising one or more processors configured to: receive an image of a portion of a substrate, the portion of a substrate comprising a first region comprising a first feature associated with a first patterning process and at least a second region comprising a second feature associated with a second patterning process wherein the first feature and the second feature form the image comprising a Moire pattern when illuminated with radiation and determine the performance of the patterning process based on characteristics of the Moire pattern.
  • Figure 1 depicts a schematic overview of a lithographic apparatus
  • Figure 2 depicts a schematic overview of a lithographic cell
  • Figure 3 depicts a schematic representation of holistic lithography, representing a cooperation between three key technologies to optimize semiconductor manufacturing
  • Figure 4 depicts an exposure field in figure 4(a) and (b), a target arrangement according to multiple exposure fields as in figure 4(c), patterns to be exposed in figure 4(d), (e) and (f) and in figure 4(g) an image formed when the target of figure 4(c) is illuminated with radiation.;
  • Figure 5 depicts a further embodiment of the invention wherein the exposure field are in the same layer as in figure 5(a) and further depicts patterns to be exposed as in figure 5(b) and figure 5(c).
  • the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g. with a wavelength of 365, 248, 193, 157 or 126 nm) and EUV (extreme ultra-violet radiation, e.g. having a wavelength in the range of about 5-100 nm).
  • ultraviolet radiation e.g. with a wavelength of 365, 248, 193, 157 or 126 nm
  • EUV extreme ultra-violet radiation
  • reticle may be broadly interpreted as referring to a generic patterning device that can be used to endow an incoming radiation beam with a patterned cross-section, corresponding to a pattern that is to be created in a target portion of the substrate.
  • the term “light valve” can also be used in this context.
  • examples of other such patterning devices include a programmable mirror array and a programmable LCD array.
  • FIG. 1 schematically depicts a lithographic apparatus LA.
  • the lithographic apparatus LA includes an illumination system (also referred to as illuminator) IL configured to condition a radiation beam B (e.g., UV radiation, DUV radiation or EUV radiation), a mask support (e.g., a mask table) T constructed to support a patterning device (e.g., a mask) MA and connected to a first positioner PM configured to accurately position the patterning device MA in accordance with certain parameters, a substrate support (e.g., a wafer table) WT constructed to hold a substrate (e.g., a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate support in accordance with certain parameters, and a projection system (e.g., a refractive projection lens system) PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.
  • the illumination system IL receives a radiation beam from a radiation source SO, e.g. via a beam delivery system BD.
  • the illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and/or other types of optical components, or any combination thereof, for directing, shaping, and/or controlling radiation.
  • the illuminator IL may be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in its cross section at a plane of the patterning device MA.
  • projection system PS used herein should be broadly interpreted as encompassing various types of projection system, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and/or electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, and/or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system” PS.
  • the lithographic apparatus LA may be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system PS and the substrate W - which is also referred to as immersion lithography. More information on immersion techniques is given in US6952253, which is incorporated herein by reference.
  • the lithographic apparatus LA may also be of a type having two or more substrate supports WT (also named “dual stage”).
  • the substrate supports WT may be used in parallel, and/or steps in preparation of a subsequent exposure of the substrate W may be carried out on the substrate W located on one of the substrate support WT while another substrate W on the other substrate support WT is being used for exposing a pattern on the other substrate W.
  • the lithographic apparatus LA may comprise a measurement stage.
  • the measurement stage is arranged to hold a sensor and/or a cleaning device.
  • the sensor may be arranged to measure a property of the projection system PS or a property of the radiation beam B.
  • the measurement stage may hold multiple sensors.
  • the cleaning device may be arranged to clean part of the lithographic apparatus, for example a part of the projection system PS or a part of a system that provides the immersion liquid.
  • the measurement stage may move beneath the projection system PS when the substrate support WT is away from the projection system PS.
  • the radiation beam B is incident on the patterning device, e.g. mask, MA which is held on the mask support T, and is patterned by the pattern (design layout) present on patterning device MA. Having traversed the mask MA, the radiation beam B passes through the projection system PS, which focuses the beam onto a target portion C of the substrate W. With the aid of the second positioner PW and a position measurement system IF, the substrate support WT can be moved accurately, e.g., so as to position different target portions C in the path of the radiation beam B at a focused and aligned position.
  • the patterning device e.g. mask, MA which is held on the mask support T
  • the pattern design layout
  • first positioner PM and possibly another position sensor may be used to accurately position the patterning device MA with respect to the path of the radiation beam B.
  • Patterning device MA and substrate W may be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2.
  • substrate alignment marks Pl, P2 as illustrated occupy dedicated target portions, they may be located in spaces between target portions.
  • Substrate alignment marks Pl, P2 are known as scribe-lane alignment marks when these are located between the target portions C.
  • the lithographic apparatus LA may form part of a lithographic cell LC, also sometimes referred to as a lithocell or (litho)cluster, which often also includes apparatus to perform pre- and post-exposure processes on a substrate W.
  • a lithographic cell LC also sometimes referred to as a lithocell or (litho)cluster
  • these include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH and bake plates BK, e.g. for conditioning the temperature of substrates W e.g. for conditioning solvents in the resist layers.
  • a substrate handler, or robot, RO picks up substrates W from input/output ports VOl, I/O2, moves them between the different process apparatus and delivers the substrates W to the loading bay LB of the lithographic apparatus LA.
  • the devices in the lithocell which are often also collectively referred to as the track, are typically under the control of a track control unit TCU that in itself may be controlled by a supervisory control system SCS, which may also control the lithographic apparatus LA, e.g. via lithography control unit LACU.
  • a supervisory control system SCS which may also control the lithographic apparatus LA, e.g. via lithography control unit LACU.
  • inspection tools may be included in the lithocell LC. If errors are detected, adjustments, for example, may be made to exposures of subsequent substrates or to other processing steps that are to be performed on the substrates W, especially if the inspection is done before other substrates W of the same batch or lot are still to be exposed or processed.
  • An inspection apparatus which may also be referred to as a metrology apparatus, is used to determine properties of the substrates W, and in particular, how properties of different substrates W vary or how properties associated with different layers of the same substrate W vary from layer to layer.
  • the inspection apparatus may alternatively be constructed to identify defects on the substrate W and may, for example, be part of the lithocell LC, or may be integrated into the lithographic apparatus LA, or may even be a stand-alone device.
  • the inspection apparatus may measure the properties on a latent image (image in a resist layer after the exposure), or on a semi-latent image (image in a resist layer after a post-exposure bake step PEB), or on a developed resist image (in which the exposed or unexposed parts of the resist have been removed), or even on an etched image (after a pattern transfer step such as etching).
  • the patterning process in a lithographic apparatus LA is one of the most critical steps in the processing which requires high accuracy of dimensioning and placement of structures on the substrate W.
  • three systems may be combined in a so called “holistic” control environment as schematically depicted in Fig. 3.
  • One of these systems is the lithographic apparatus LA which is (virtually) connected to a metrology tool MT (a second system) and to a computer system CL (a third system).
  • the key of such “holistic” environment is to optimize the cooperation between these three systems to enhance the overall process window and provide tight control loops to ensure that the patterning performed by the lithographic apparatus LA stays within a process window.
  • the process window defines a range of process parameters (e.g. dose, focus, overlay) within which a specific manufacturing process yields a defined result (e.g. a functional semiconductor device) - typically within which the process parameters in the lithographic process or patterning process are allowed to vary.
  • the computer system CL may use (part of) the design layout to be patterned to predict which resolution enhancement techniques to use and to perform computational lithography simulations and calculations to determine which mask layout and lithographic apparatus settings achieve the largest overall process window of the patterning process (depicted in Fig. 3 by the double arrow in the first scale SCI).
  • the resolution enhancement techniques are arranged to match the patterning possibilities of the lithographic apparatus LA.
  • the computer system CL may also be used to detect where within the process window the lithographic apparatus LA is currently operating (e.g. using input from the metrology tool MT) to predict whether defects may be present due to e.g. sub-optimal processing (depicted in Fig. 3 by the arrow pointing “0” in the second scale SC2).
  • the metrology tool MT may provide input to the computer system CL to enable accurate simulations and predictions, and may provide feedback to the lithographic apparatus LA to identify possible drifts, e.g. in a calibration status of the lithographic apparatus LA (depicted in Fig. 3 by the multiple arrows in the third scale SC3).
  • metrology tools MT In lithographic processes, it is desirable to make frequently measurements of the structures created, e.g., for process control and verification. Tools to make such measurement are typically called metrology tools MT. Different types of metrology tools MT for making such measurements are known, including scanning electron microscopes or various forms of scatterometer metrology tools MT. Scatterometers are versatile instruments which allow measurements of the parameters of a lithographic process by having a sensor in the pupil or a conjugate plane with the pupil of the objective of the scatterometer, measurements usually referred as pupil based measurements, or by having the sensor in the image plane or a plane conjugate with the image plane, in which case the measurements are usually referred as image or field based measurements.
  • Aforementioned scatterometers may measure gratings using light from soft x-ray and visible to near-IR wavelength range.
  • the scatterometer MT is an angular resolved scatterometer.
  • reconstruction methods may be applied to the measured signal to reconstruct or calculate properties of the grating.
  • Such reconstruction may, for example, result from simulating interaction of scattered radiation with a mathematical model of the target structure and comparing the simulation results with those of a measurement. Parameters of the mathematical model are adjusted until the simulated interaction produces a diffraction pattern similar to that observed from the real target.
  • the scatterometer MT is a spectroscopic scatterometer MT.
  • the radiation emitted by a radiation source is directed onto the target and the reflected or scattered radiation from the target is directed to a spectrometer detector, which measures a spectrum (i.e. a measurement of intensity as a function of wavelength) of the specular reflected radiation. From this data, the structure or profile of the target giving rise to the detected spectrum may be reconstructed, e.g. by Rigorous Coupled Wave Analysis and non-linear regression or by comparison with a library of simulated spectra.
  • the scatterometer MT is a ellipsometric scatterometer.
  • the ellipsometric scatterometer allows for determining parameters of a lithographic process by measuring scattered radiation for each polarization states.
  • Such metrology apparatus emits polarized light (such as linear, circular, or elliptic) by using, for example, appropriate polarization filters in the illumination section of the metrology apparatus.
  • a source suitable for the metrology apparatus may provide polarized radiation as well.
  • metrology tools for example an angular resolved scatterometter illuminating an underfilled target, such as a grating
  • an underfilled target such as a grating
  • reconstruction methods where the properties of the grating can be calculated by simulating interaction of scattered radiation with a mathematical model of the target structure and comparing the simulation results with those of a measurement. Parameters of the model are adjusted until the simulated interaction produces a diffraction pattern similar to that observed from the real target.
  • the scatterometer MT is adapted to measure the overlay of two misaligned gratings or periodic structures by measuring asymmetry in the reflected spectrum and/or the detection configuration, the asymmetry being related to the extent of the overlay.
  • the two (typically overlapping) grating structures may be applied in two different layers (not necessarily consecutive layers), and may be formed substantially at the same position on the wafer.
  • the scatterometer may have a symmetrical detection configuration as described in the patent application EPl, 628, 164 A, such that any asymmetry is clearly distinguishable. This provides a straightforward way to measure misalignment in gratings.
  • Focus and dose may be determined simultaneously by scatterometry (or alternatively by scanning electron microscopy) as described in US patent application US2011-0249244, incorporated herein by reference in its entirety.
  • a single structure may be used which has a unique combination of critical dimension and sidewall angle measurements for each point in a focus energy matrix (FEM - also referred to as Focus Exposure Matrix). If these unique combinations of critical dimension and sidewall angle are available, the focus and dose values may be uniquely determined from these measurements.
  • FEM focus energy matrix
  • a metrology target may be an ensemble of composite gratings, formed by a lithographic process, mostly in resist, but also after etch process for example.
  • the pitch and line-width of the structures in the gratings strongly depend on the measurement optics (in particular the NA of the optics) to be able to capture diffraction orders coming from the metrology targets.
  • the diffracted signal may be used to determine shifts between two layers (also referred to ‘overlay’) or may be used to reconstruct at least part of the original grating as produced by the lithographic process. This reconstruction may be used to provide guidance of the quality of the lithographic process and may be used to control at least part of the lithographic process.
  • Targets may have smaller sub-segmentation, which are configured to mimic dimensions of the functional part of the design layout in a target. Due to this sub-segmentation, the targets will behave more similar to the functional part of the design layout such that the overall process parameter measurements resembles the functional part of the design layout better.
  • the targets may be measured in an underfilled mode or in an overfilled mode. In the underfilled mode, the measurement beam generates a spot that is smaller than the overall target. In the overfilled mode, the measurement beam generates a spot that is larger than the overall target. In such overfilled mode, it may also be possible to measure different targets simultaneously, thus determining different processing parameters at the same time.
  • substrate measurement recipe may include one or more parameters of the measurement itself, one or more parameters of the one or more patterns measured, or both.
  • the measurement used in a substrate measurement recipe is a diffraction-based optical measurement
  • one or more of the parameters of the measurement may include the wavelength of the radiation, the polarization of the radiation, the incident angle of radiation relative to the substrate, the orientation of radiation relative to a pattern on the substrate, etc.
  • One of the criteria to select a measurement recipe may, for example, be a sensitivity of one of the measurement parameters to processing variations. More examples are described in US patent application US2016-0161863 and published US patent application US 2016/0370717A1 incorporated herein by reference in its entirety.
  • a reticle may comprise a pattern to be exposed on a substrate a plurality of times.
  • the reticle may be moved relative to the substrate, in order to expose different regions on the substrate sequentially.
  • a reticle may be associated with to a first positioner PM for accurately positioning the reticle inside a lithographic apparatus LA.
  • a substrate W may be associated with a second positioner PW for accurately positioned the substrate W inside lithographic apparatus LA.
  • the positioners PM and PW may be used to accurately position a substrate W and reticle relative to each other, in order to set a position of an exposed pattern on the substrate.
  • Other settings and elements that may affect the position of a pattern on a substrate may include for example, the projection system PS for projecting the pattern of the reticle onto the substrate W, properties (e.g. topography) of the substrate, wafer table, WT, and properties of the radiation used for exposing a pattern.
  • the projection system PS for projecting the pattern of the reticle onto the substrate W properties (e.g. topography) of the substrate, wafer table, WT, and properties of the radiation used for exposing a pattern.
  • a full device to be lithographically exposed may be too big to fit on a single reticle.
  • the full device may therefore be divided into two or more separate regions.
  • the regions may be exposed separately from each other, for example sequentially.
  • the separately exposed regions need to be connected accurately and precisely at or proximal to a boundary between regions.
  • Measurement data may be obtained of an exposed substrate for determining the positioning of a plurality of regions. Measurement data may be used to check whether an exposed substrate has acceptable positioning of exposed regions, e.g. for quality control. Measurements may also be used to determine how to improve settings for future exposures performed by the lithographic apparatus LA. For example, positioning errors may be determined for a plurality of regions. The determined positioning errors may indicate that there is an error in the x-direction alignment of two neighbouring regions.
  • the error may be analysed to determine one or more causes of the error.
  • One or more apparatus or recipe settings may be updated to address the error, in order to avoid the mistake in future exposures.
  • Positioning of sequentially exposed regions relative to each other may be discussed in relation to stitching errors.
  • the performance of a lithographic patterning process may comprise one or more stitching errors.
  • Stitching errors may be errors in the desired position of exposed regions. Stitching may refer to the connection, or relative placement, of two regions.
  • the regions may be neighbouring regions.
  • the regions may comprise features having an association with each other. For example, the regions may belong to a same device exposed on the substrate W.
  • the lithographic exposure may expose a pattern onto a two-dimensional region.
  • the region may be rectangular.
  • a region may be square.
  • the region may have any two-dimensional shape in the plane of the substrate.
  • a boundary with a neighbouring region may exist.
  • the directions along which the borders of a region lie may be referred to as the x-direction and y -direction.
  • the directions of the borders may also be referred to as a horizontal and vertical directions.
  • the in-plane placement of exposed regions on a substrate may be controlled using measurement data. Measurement data may for example be used to determine and/or analyse stitching errors between regions on a substrate W.
  • the measurement data may be obtained based on a metrology target.
  • the metrology target may for example be an overlay metrology target.
  • One or more metrology targets may be positioned on substrate as part of a pattern design exposed on the substrate.
  • a metrology target may be exposed as part of the lithographic exposure.
  • the structures included in the target e.g. diffraction gratings
  • Analysis of the metrology target(s) may comprise measurements to determine a position of one or more metrology targets relative to one or more further metrology targets on the substrate.
  • the measurements may comprise for example overlay and/or alignment measurements.
  • the metrology target(s) and further metrology target(s) may be positioned in different regions on the substrate. Including metrology targets adds costs by taking up space on the substrate W, as it leads to less space being available for exposing product features.
  • Metrology target are formed within the layers representing each exposure or patterning step, and these metrology targets are used to determine information that is needed for quantifying the patterning process, in particular the stitching errors between different exposure fields.
  • the lithographic process is a patterning process.
  • the lithographic process pattens a layer of resist, as it is known from state of the art. Decreasing the pattern features dimensions, which may be employed in an EUV lithographic process, may lead to a decrease of the resist layer thickness. In this case however, the resist layer thickness does not have sufficient optical properties needed for the metrology needs.
  • the diffraction efficiency of a resist layers of 40 nm or less, in particular layers of 10 nm, is so low that, when illuminated with light, such metrology targets do not provide a measurable signal.
  • a SEM tool Sccanning Electron Microscope
  • resists layers of 40 nm thickness or less may be damaged thus not providing sufficient image quality of the measured targets. Described herein are methods to overcome at least some of these challenges.
  • a method for determining the performance of a patterning process comprising receiving an image of a portion of a substrate, the portion of a substrate comprising a first region comprising a first feature associated with a first patterning process and at least a second region comprising a second feature associated with a second patterning process wherein the first feature and the second feature form the image comprising a Moire pattern when illuminated with radiation and determining the performance of the patterning process based on characteristics of the Moire pattern.
  • Figure 4(a) illustrates element 405 which may be a pattern on a reticle which may be exposed with a lithographic apparatus in an exposure field 401.
  • 410a is an indication that this exposure field 401 is exposed without the loss of generality in layer N of the semiconductor device stack.
  • Figure 4(b) illustrates with element 410b that the exposure fields 402 and 403 are exposed in a next layer N+l of the semiconductor device stack.
  • Exposure field 402 prints a pattern 406 on a reticle as a target for measuring stitching errors.
  • Exposure field 403 prints a pattern 407 on a reticle as a target for measuring stitching errors.
  • the patterns 406 and 407 are adjacent.
  • the patterns 406 and 407 on the reticle result in regions on a substrate with features according to figure 4(e) and figure 4(f), that is regions of gratings, wherein each grating has a feature such a pitch.
  • the resulting pattern on the substrate is shown in figure 4(c).
  • 410c indicates that the pattern area 400x on the substrate is formed from an overlap of pattern 405 in layer N and patterns 406 and 407 in layer N+l.
  • the region on the substrate 400x thus comprises a region formed by gratings resulting from the top half of pattern 405 and gratings resulting from pattern 406, that is the region in figure 4(c) above the dotted line 400y.
  • the region on the substrate 400x further comprises a region formed by gratings resulting from the bottom half of the pattern 405 and gratings resulting from pattern 407 when exposed on the substrate, that is the region in figure 4(c) below the dotted line 400y.
  • the pitch of the gratings of the regions 406 and 407 is p2.
  • p2 is 600nm.
  • p2 is between 400nm and 900nm.
  • the pitch of the gratings of region 405 is pl.
  • pl is 500nm.
  • the pitch pl is between 400nm and 900nm.
  • the region 400x comprises therefore two targets: in the top half of region 400x, which is above dotted line 400y, is a target having overlaying gratings with a bottom grating in layer N having a pitch pl and a top grating in layer N+l having a pitch p2 and in the bottom half of region 400x, which is below dotted line 400y, is a target having overlaying gratings with a bottom grating in layer N having a pitch pl and a top grating in layer N+l having a pitch p2.
  • the target formed in region 400x above the dotted line 400y comprises patterning information during the exposure with exposure field 402.
  • the target formed in the region 400x below the dotted line 400y comprises patterning information during the exposure with exposure field 403.
  • the patterning information due to exposure field 401 is the same in both regions below and above dotted line 400y.
  • Figure 4(g) illustrates an image that is formed when region 400x is illuminated with radiation.
  • the target in the above the dotted line 400y is a target having different pitches, pl in layer N and p2 in layer N+l.
  • the target in the below the dotted line 400y is a target also having different pitches, pl in layer N and p2 in layer N+l . Both target, when illuminated with radiation, create an image on a detection camera as illustrated in figure 4(g).
  • Image 406i is the image formed by the target in the region 400x above the dotted line 400y and image 407i is the image formed by the target in the region 400x below the dotted line 400y.
  • Images 406i and 407i comprises Moire fringes having a period 400pm, well visible on a detection camera.
  • the signal from layer N is relatively strong since it is formed from a grating in layer N which has good optical properties, such as diffraction efficiency or reflectivity. Radiation scattered from layer N+l, despite being weak, is modulating the signal thus the resulting measurable Moire fringe, as imaged in 406i and 407i, is detectable.
  • the Moire fringes are positioned in a similar fashion on the measured images. However, if stitching errors are present in the exposure fields 402 and 403, the Moire fringes of image 406i and image 407i are shifted with respect to each other. By measuring the shift or phase between the Moire fringes, illustrated in figure 4(g) as 400, determination of the performance of the exposure fields 402 and 403 is determined.
  • FIG. 5(a) illustrates an exposure field 502 which would pattern on a substrate a pattern 506 and an exposure field 503 which would pattern on a substrate a pattern 507. Both exposure transfer the patterns 506 and 507 from a reticle to a region on the substrate in the same layer of the stack of the semiconductor device. Exposure fields 502 and 503 are overlapping in the region depicted by both 506 and 507.
  • Figure 5(b) illustrate the pattern exposed during the exposure field 506. It comprises a top area with pitch p2, above line 500y, and a bottom area with pitch pl, under line 5 OOy.
  • Figure 5(c) illustrates the pattern exposed during the exposure field 507.
  • the created pattern in the region above the line 500y after exposure with both exposure field 506 and 507 is creating an image, when illuminated with radiation, having Moire fringes (resulting fringes not shown).
  • the created pattern in the region below the line 500y after exposure with both exposure field 506 and 507 is creating an image, when illuminated with radiation, having Moire fringes (resulting fringes not shown).
  • the stitching error between exposure field 506 and exposure field 507 is visible in the change in a characteristic of the Moire fringe of the image above line 500y and in a characteristic of the Moire fringe of the image below line 500y (of figure 5).
  • the characteristic may be the phase of each Moire fringe.
  • the images used for determining the performance of a patterning process may be obtained by illuminating the metrology targets with optical radiation.
  • the images used for determining the performance of the patterning process may be a scanning electron microscope image (SEM).
  • the image may be a voltage contrast image.
  • a voltage contrast image may provide a measure of the electrical contact of features to the underlying layer.
  • the image may be obtained after the exposed substrate has been processed, for example after one or more post-exposure development steps performed on the patterned substrate.
  • the measure of contact to an underlying layer may provide an indication of how well the features of the exposed layer match up with features of an underlying layer. This may in turn be used to determine whether a stitching error is present.
  • the image may be obtained while the substrate is in the lithographic cell LC.
  • the image may be of a patterned layer of photoresist on the substrate.
  • the image may be of a layer of material that has been patterned by an etching process.
  • the same lithographic patterning exposure may be performed on a plurality of substrates over a period of time.
  • the amount and positions of images to be analysed for determining the performance of the patterning process may be changed over time.
  • a more dense performance map may be prepared, as the new process may require more corrections initially.
  • the performance may improve, and/or stabilise.
  • the amount of images analysed to determine process performance may be reduced.
  • the method may also be flexible how dense the performance analysis is across the substrate.
  • the method may determine one or more areas of interest for performance analysis. For example, areas where the determined performance is worse may be analysed in more detail when performing that same exposure on another substrate.
  • a substrate may comprise critical areas, where product features may have more stringent fabrication requirements (i.e. lower tolerances on deviations from the design standard). These critical areas may receive more dense performance monitoring. This may lead to improved performance of the patterning process at the critical areas.
  • the methods of determining a performance of a lithographic patterning process may be determined in whole or in part using a model.
  • the model may comprise vision technology, for example machine vision technology.
  • the model may be a machine learning model.
  • a model may be used to determine one or more process characteristics.
  • a model may receive one or more feature characteristics as input.
  • a model may take as input one or more received images of the first and second region and the boundary thereof, such as 406i and 407i figure 4(g).
  • a method may use a plurality of models.
  • a method may for example use two separate models.
  • a first model may be a vision technology model.
  • the vision technology model may be used for interpreting one or more images provided as input to the model.
  • a model receiving one or more images as input may be a convolutional neural network.
  • the first model may provide one or more process characteristics as output.
  • a second model may receive one or more process characteristics determined by the first model.
  • the second model may receive process characteristics for a plurality of regions on a substrate.
  • the second model may interpret the received process characteristics to convert them to patterning corrections.
  • the second model may provide as output, correction data for adjusting the lithographic patterning process, for example for correcting stitching errors.
  • the correction data may comprise one or more updated values for lithographic patterning process settings.
  • a model may the model may comprise a classification model.
  • the classification model may for example be for verification of the patterning process.
  • the model may classify an image as having region stitching properties falling within (pass) or outside (fail) of one or more set exposure tolerances.
  • the methods as described herein may use one or more images to determine feature characteristics of patterns depicted in those images.
  • the feature characteristics e.g. overlay, alignment, or other properties indicating a stitching quality
  • Enhancing an image may for example comprise removing noise, filtering out unwanted signals, and/or extracting relevant features to the analysis.
  • An advantage of extracting relevant features may include a reduction in dimension of the analysis.
  • determining one or more feature characteristics from an image may comprise some or all steps of pre-processing the image, extracting features from a pre-processed image, and/or determining a metric for a stitching quality based on the pre-processed image.
  • the feature characteristic may comprise overlay. It may be desirable to separate an analysis of overlay into separate dimensions on the substrate, for example the two dimensions in the plane of the patterned substrate.
  • the dimensions may be perpendicular to each other, and may be referred to as a x-direction and y-direction, or a horizontal direction and a vertical direction. These directions may be parallel and/or perpendicular to the directions of the boundaries to be analysed.
  • lithographic apparatus may have other applications. Possible other applications include the manufacture of integrated optical systems, guidance and detection patterns for magnetic domain memories, flat-panel displays, liquidcrystal displays (LCDs), thin-film magnetic heads, etc.
  • embodiments of the invention may be used in other apparatus.
  • Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or mask (or other patterning device).
  • lithographic tools Such a lithographic tool may use vacuum conditions or ambient (non- vacuum) conditions.
  • the inspection or metrology apparatus that comprises an embodiment of the invention may be used to determine characteristics of structures on a substrate or on a wafer.
  • the inspection apparatus or metrology apparatus that comprises an embodiment of the invention may be used to detect defects of a substrate or defects of structures on a substrate or on a wafer.
  • a characteristic of interest of the structure on the substrate may relate to defects in the structure, the absence of a specific part of the structure, or the presence of an unwanted structure on the substrate or on the wafer.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Analysing Materials By The Use Of Radiation (AREA)

Abstract

Un procédé permettant de déterminer les performances d'un processus de formation de motifs, le procédé consistant à recevoir une image d'une partie d'un substrat, la partie de substrat comprenant une première région comprenant une première caractéristique associée à un premier processus de formation de motifs et au moins une seconde région comprenant une seconde caractéristique associée à un second processus de formation de motifs, la première caractéristique et la seconde caractéristique formant un motif de moiré lorsqu'elles sont éclairées par un rayonnement, et à déterminer les performances du processus de formation de motifs sur la base des caractéristiques du motif de moiré.
PCT/EP2024/050817 2023-01-20 2024-01-15 Procédé et appareil de détermination de performances de processus de formation de motifs Ceased WO2024153591A1 (fr)

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CN202480006841.5A CN120476348A (zh) 2023-01-20 2024-01-15 用于图案化过程性能确定的方法和设备

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WO2020025231A1 (fr) * 2018-08-01 2020-02-06 Stichting Vu Appareil de métrologie et procédé de détermination d'une caractéristique d'une ou plusieurs structures sur un substrat
WO2020057900A1 (fr) * 2018-09-19 2020-03-26 Asml Netherlands B.V. Capteur de métrologie pour métrologie de position
WO2022122546A1 (fr) * 2020-12-08 2022-06-16 Asml Netherlands B.V. Procédé de métrologie et appareils associés

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Publication number Priority date Publication date Assignee Title
US6952253B2 (en) 2002-11-12 2005-10-04 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
EP1628164A2 (fr) 2004-08-16 2006-02-22 ASML Netherlands B.V. Procédé et dispositif pour caractérisation de la lithographie par spectrométrie à résolution angulaire
US20100328655A1 (en) 2007-12-17 2010-12-30 Asml, Netherlands B.V. Diffraction Based Overlay Metrology Tool and Method
US20110026032A1 (en) 2008-04-09 2011-02-03 Asml Netherland B.V. Method of Assessing a Model of a Substrate, an Inspection Apparatus and a Lithographic Apparatus
US20110102753A1 (en) 2008-04-21 2011-05-05 Asml Netherlands B.V. Apparatus and Method of Measuring a Property of a Substrate
US20110249244A1 (en) 2008-10-06 2011-10-13 Asml Netherlands B.V. Lithographic Focus and Dose Measurement Using A 2-D Target
WO2011012624A1 (fr) 2009-07-31 2011-02-03 Asml Netherlands B.V. Procédé et appareil de métrologie, système lithographique et cellule de traitement lithographique
US20120044470A1 (en) 2010-08-18 2012-02-23 Asml Netherlands B.V. Substrate for Use in Metrology, Metrology Method and Device Manufacturing Method
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US20160370717A1 (en) 2015-06-17 2016-12-22 Asml Netherlands B.V. Recipe selection based on inter-recipe consistency
WO2020025231A1 (fr) * 2018-08-01 2020-02-06 Stichting Vu Appareil de métrologie et procédé de détermination d'une caractéristique d'une ou plusieurs structures sur un substrat
WO2020057900A1 (fr) * 2018-09-19 2020-03-26 Asml Netherlands B.V. Capteur de métrologie pour métrologie de position
WO2022122546A1 (fr) * 2020-12-08 2022-06-16 Asml Netherlands B.V. Procédé de métrologie et appareils associés

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