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WO2024160479A1 - Sélecteur de second mode d'éclairage (ims) pour yieldstar - Google Patents

Sélecteur de second mode d'éclairage (ims) pour yieldstar Download PDF

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Publication number
WO2024160479A1
WO2024160479A1 PCT/EP2024/050114 EP2024050114W WO2024160479A1 WO 2024160479 A1 WO2024160479 A1 WO 2024160479A1 EP 2024050114 W EP2024050114 W EP 2024050114W WO 2024160479 A1 WO2024160479 A1 WO 2024160479A1
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WO
WIPO (PCT)
Prior art keywords
selector
ims
quadrants
substrate
radiation
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Ceased
Application number
PCT/EP2024/050114
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English (en)
Inventor
Changsik YOON
Roxana REZVANI NARAGHI
Alexander Kenneth RAUB
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ASML Netherlands BV
Original Assignee
ASML Netherlands BV
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by ASML Netherlands BV filed Critical ASML Netherlands BV
Priority to CN202480010303.3A priority Critical patent/CN120641820A/zh
Priority to KR1020257023908A priority patent/KR20250141704A/ko
Priority to IL322019A priority patent/IL322019A/en
Publication of WO2024160479A1 publication Critical patent/WO2024160479A1/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
    • G03F7/70483—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
    • 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
    • G03F7/706835—Metrology information management or control
    • G03F7/706837—Data analysis, e.g. filtering, weighting, flyer removal, fingerprints or root cause analysis
    • 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
    • G03F7/706843—Metrology apparatus
    • G03F7/706851—Detection branch, e.g. detector arrangements, polarisation control, wavelength control or dark/bright field detection

Definitions

  • the present disclosure relates to a metrology apparatus for measuring multiple marks in parallel using parallel sensor concepts that geometrically arrange sensors in a space to allow parallel acquisitions.
  • a lithographic apparatus is a machine that applies a desired pattern onto a substrate, usually onto a target portion of the substrate.
  • a lithographic apparatus can be used, for example, in the manufacture of integrated circuits (ICs).
  • a patterning device which is alternatively referred to as a mask or a reticle, can be used to generate a circuit pattern to be formed on an individual layer of the IC.
  • This pattern can be transferred onto a target portion (e.g., comprising part of, one, or several dies) on a substrate (e.g., a silicon wafer). Transfer of the pattern is typically via imaging onto a layer of radiation-sensitive material (resist) provided on the substrate.
  • resist radiation-sensitive material
  • a single substrate will contain a network of adjacent target portions that are successively patterned.
  • lithographic apparatus include so-called steppers, in which each target portion is irradiated by exposing an entire pattern onto the target portion at one time, and so-called scanners, in which each target portion is irradiated by scanning the pattern through a radiation beam in a given direction (the “scanning”-direction) while synchronously scanning the target portions parallel or anti-parallel to this scanning direction. It is also possible to transfer the pattern from the patterning device to the substrate by imprinting the pattern onto the substrate.
  • lithographic operation During lithographic operation, different processing steps can require different layers to be sequentially formed on the substrate. Accordingly, it can be necessary to position the substrate relative to prior patterns formed thereon with a high degree of accuracy.
  • alignment marks are placed on the substrate to be aligned and are located with reference to a second object.
  • a lithographic apparatus can use an alignment apparatus for detecting positions of the alignment marks and for aligning the substrate using the alignment marks to ensure accurate exposure from a mask. Misalignment between the alignment marks at two different layers is measured as overlay error.
  • parameters of the patterned substrate are measured. Parameters can include, for example, the overlay error between successive layers formed in or on the patterned substrate and critical linewidth of developed photosensitive resist.
  • This measurement can be performed on a product substrate and/or on a dedicated metrology target.
  • a fast and non-invasive form of a specialized inspection tool is a scatterometer in which a beam of radiation is directed onto a target on the surface of the substrate and properties of the scattered or reflected beam are measured. By comparing the properties of the beam before and after it has been reflected or scattered by the substrate, the properties of the substrate can be determined. This can be done, for example, by comparing the reflected beam with data stored in a library of known measurements associated with known substrate properties.
  • Spectroscopic scatterometers direct a broadband radiation beam onto the substrate and measure the spectrum (intensity as a function of wavelength) of the radiation scattered into a particular narrow angular range.
  • angularly resolved scatterometers use a monochromatic radiation beam and measure the intensity of the scattered radiation as a function of angle.
  • Such optical scatterometers can be used to measure parameters, such as critical dimensions of developed photosensitive resist or overlay error (OV) between two layers formed in or on the patterned substrate.
  • Properties of the substrate can be determined by comparing the properties of an illumination beam before and after the beam has been reflected or scattered by the substrate.
  • Past technology for alignment sensors measure a single alignment mark at a time.
  • first and second selectors are configured to pass two quadrants of light.
  • the first selector is configured to block a first pair of the two quadrants and to generate a first image.
  • the second selector is configure to block a second, different pair of the two quadrants and to generate a second image.
  • a comparator is configured to compare an intensity difference between the first and second images.
  • a calibration device is configured to balance an intensity difference between the first and second images, such that incoherent internal cross talk is substantially eliminated.
  • the first selector is at a first pupil conjugate plane.
  • the second selector is at a second pupil conjugate plane.
  • the first and second selectors each comprise an illumination mode selector.
  • the first and second images are taken sequentially for each quadrant of the illumination mode selectors.
  • each illumination mode selector comprises an aperture
  • the substantial elimination of incoherent internal cross talk substantially eliminates its effect on overlay error.
  • the incoherent internal cross talk does not affect an overlay error.
  • FIG. 1 A shows a schematic of a reflective lithographic apparatus, according to some embodiments.
  • FIG. IB shows a schematic of a transmissive lithographic apparatus, according to some embodiments.
  • FIG. 2 shows a more detailed schematic of the reflective lithographic apparatus, according to some embodiments.
  • FIG. 3 shows a schematic of a lithographic cell, according to some embodiments.
  • FIGS. 4A and 4B show schematics of lithographic apparatuses, according to some embodiments.
  • FIGS. 5 A and 5B show micro diffraction based overlay imaging, according to some embodiments.
  • FIGS. 6 A and 6B show uDBO imaging associated with a first quadrant of illumination pupils with no incoherent internal cross talk, according to some embodiments.
  • FIGS. 7A and 7B show uDBO imaging associated with a third quadrant of illumination pupils with no incoherent internal cross talk, according to some embodiments.
  • FIG. 8 is a flowchart illustrating a process calibrating out impacts by homogeneity and incoherent internal cross talk, according to some embodiments.
  • an embodiment “an example embodiment,” etc., indicate that the embodiment(s) described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is understood that it is within the knowledge of one skilled in the art to effect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.
  • spatially relative terms such as “beneath,” “below,” “lower,” “above,” “on,” “upper” and the like, can be used herein for ease of description to describe one element or feature’s relationship to another element(s) or feature(s) as illustrated in the figures.
  • the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures.
  • the apparatus can be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein may likewise be interpreted accordingly.
  • the term “about” as used herein indicates the value of a given quantity that can vary based on a particular technology. Based on the particular technology, the term “about” can indicate a value of a given quantity that varies within, for example, 10-30% of the value (e.g., ⁇ 10%, ⁇ 20%, or ⁇ 30% of the value).
  • Embodiments of the disclosure can be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the disclosure may also be implemented as instructions stored on a machine -readable medium, which can be read and executed by one or more processors.
  • a machine- readable medium may include any mechanism for storing or transmitting information in a form readable by a machine (e.g., a computing device).
  • a machine-readable medium may include read only memory (ROM); random access memory (RAM); magnetic disk storage media; optical storage media; flash memory devices; electrical, optical, acoustical or other forms of propagated signals (e.g., carrier waves, infrared signals, digital signals, etc.), and others.
  • firmware, software, routines, and/or instructions can be described herein as performing certain actions. However, it should be appreciated that such descriptions are merely for convenience and that such actions in fact result from computing devices, processors, controllers, or other devices executing the firmware, software, routines, instructions, etc. [0034] Before describing such embodiments in more detail, however, it is instructive to present an example environment in which embodiments of the present disclosure can be implemented.
  • FIGS. 1A and IB show schematic illustrations of a lithographic apparatus 100 and lithographic apparatus 100’, respectively, in which embodiments of the present disclosure can be implemented.
  • Lithographic apparatus 100 and lithographic apparatus 100’ each include the following: an illumination system (illuminator) IL configured to condition a radiation beam B (for example, deep ultra violet or extreme ultra violet radiation); a support structure (for example, a mask table) MT configured to support a patterning device (for example, a mask, a reticle, or a dynamic patterning device) MA and connected to a first positioner PM configured to accurately position the patterning device MA; and, a substrate table (for example, a wafer table) WT configured to hold a substrate (for example, a resist coated wafer) W and connected to a second positioner PW configured to accurately position the substrate W.
  • an illumination system illumination system
  • IL for example, deep ultra violet or extreme ultra violet radiation
  • a support structure for example, a mask table
  • MT configured to support
  • Lithographic apparatus 100 and 100’ also have a projection system PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion (for example, comprising one or more dies) C of the substrate W.
  • the patterning device MA and the projection system PS are reflective.
  • the patterning device MA and the projection system PS are transmissive.
  • the illumination system IL can include various types of optical components, such as refractive, reflective, catadioptric, magnetic, electromagnetic, electrostatic, or other types of optical components, or any combination thereof, for directing, shaping, or controlling the radiation beam B.
  • the support structure MT holds the patterning device MA in a manner that depends on the orientation of the patterning device MA with respect to a reference frame, the design of at least one of the lithographic apparatus 100 and 100’, and other conditions, such as whether or not the patterning device MA is held in a vacuum environment.
  • the support structure MT can use mechanical, vacuum, electrostatic, or other clamping techniques to hold the patterning device MA.
  • the support structure MT can be a frame or a table, for example, which can be fixed or movable, as required. By using sensors, the support structure MT can ensure that the patterning device MA is at a desired position, for example, with respect to the projection system PS.
  • the term “patterning device” MA should be broadly interpreted as referring to any device that can be used to impart a radiation beam B with a pattern in its cross-section, such as to create a pattern in the target portion C of the substrate W.
  • the pattern imparted to the radiation beam B can correspond to a particular functional layer in a device being created in the target portion C to form an integrated circuit.
  • the terms “inspection apparatus,” “metrology system,” or the like can be used herein to refer to, e.g., a device or system used for measuring a property of a structure (e.g., overlay error, critical dimension parameters) or used in a lithographic apparatus to inspect an alignment of a wafer (e.g., alignment apparatus).
  • the patterning device MA can be transmissive (as in lithographic apparatus 100’ of FIG.
  • patterning devices MA include reticles, masks, programmable mirror arrays, or programmable LCD panels.
  • Masks are well known in lithography, and include mask types such as binary, alternating phase shift, or 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 so as to reflect an incoming radiation beam in different directions. The tilted mirrors impart a pattern in the radiation beam B, which is reflected by a matrix of small mirrors.
  • projection system PScan encompass any type of projection system, including refractive, reflective, catadioptric, magnetic, electromagnetic and electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, or for other factors, such as the use of an immersion liquid on the substrate W or the use of a vacuum.
  • a vacuum environment can be used for EUV or electron beam radiation since other gases can absorb too much radiation or electrons.
  • a vacuum environment can therefore be provided to the whole beam path with the aid of a vacuum wall and vacuum pumps.
  • Lithographic apparatus 100 and/or lithographic apparatus 100’ can be of a type having two (dual stage) or more substrate tables WT (and/or two or more mask tables).
  • the additional substrate tables WT can be used in parallel, or preparatory steps can be carried out on one or more tables while one or more other substrate tables WT are being used for exposure.
  • the additional table may not be a substrate table WT.
  • the lithographic apparatus can also be of a type wherein at least a portion of the substrate can be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system and the substrate.
  • a liquid having a relatively high refractive index e.g., water
  • An immersion liquid can be applied to other spaces in the lithographic apparatus, for example, between the mask and the projection system. Immersion techniques are well known in the art for increasing the numerical aperture of projection systems.
  • immersion as used herein does not mean that a structure, such as a substrate, must be submerged in liquid, but rather only means that liquid is located between the projection system and the substrate during exposure.
  • the illuminator IL receives a radiation beam from a radiation source SO.
  • the source SO and the lithographic apparatus 100, 100’ can be separate physical entities, for example, when the source SO is an excimer laser. In such cases, the source SO is not considered to form part of the lithographic apparatus 100 or 100’, and the radiation beam B passes from the source SO to the illuminator IL with the aid of a beam delivery system BD (in FIG. IB) including, for example, suitable directing mirrors and/or a beam expander.
  • the source SO can be an integral part of the lithographic apparatus 100, 100’, for example, when the source SO is a mercury lamp.
  • the source SO and the illuminator IL, together with the beam delivery system BD, if required, can be referred to as a radiation system.
  • the illuminator IL can include an adjuster AD (in FIG. IB) for adjusting the angular intensity distribution of the radiation beam.
  • AD adjuster
  • the illuminator IL can comprise various other components (in FIG. IB), such as an integrator IN and a condenser CO.
  • the illuminator IL can be used to condition the radiation beam B to have a desired uniformity and intensity distribution in its cross section.
  • the radiation beam B is incident on the patterning device (for example, mask) MA, which is held on the support structure (for example, mask table) MT, and is patterned by the patterning device MA.
  • the radiation beam B is reflected from the patterning device (for example, mask) MA.
  • the radiation beam B passes through the projection system PS, which focuses the radiation beam B onto a target portion C of the substrate W.
  • the substrate table WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B).
  • the first positioner PM and another position sensor IF1 can be used to accurately position the patterning device (for example, mask) MA with respect to the path of the radiation beam B.
  • Patterning device (for example, mask) MA and substrate W can be aligned using mask alignment marks Ml, M2 and substrate alignment marks Pl, P2.
  • the radiation beam B is incident on the patterning device (for example, mask MA), which is held on the support structure (for example, mask table MT), and is patterned by the patterning device. 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.
  • the projection system has a pupil conjugate PPU to an illumination system pupil IPU. Portions of radiation emanate from the intensity distribution at the illumination system pupil IPU and traverse a mask pattern without being affected by diffraction at the mask pattern and create an image of the intensity distribution at the illumination system pupil IPU.
  • the projection system PS projects an image of the mask pattern MP, where the image is formed by diffracted beams produced from the mark pattern MP by radiation from the intensity distribution, onto a photoresist layer coated on the substrate W.
  • the mask pattern MP can include an array of lines and spaces. A diffraction of radiation at the array and different from zeroth order diffraction generates diverted diffracted beams with a change of direction in a direction perpendicular to the lines. Undiffracted beams (i.e., so-called zeroth order diffracted beams) traverse the pattern without any change in propagation direction.
  • the zeroth order diffracted beams traverse an upper lens or upper lens group of the projection system PS, upstream of the pupil conjugate PPU of the projection system PS, to reach the pupil conjugate PPU.
  • the portion of the intensity distribution in the plane of the pupil conjugate PPU and associated with the zeroth order diffracted beams is an image of the intensity distribution in the illumination system pupil IPU of the illumination system IL.
  • the aperture device PD for example, is disposed at or substantially at a plane that includes the pupil conjugate PPU of the projection system PS.
  • the projection system PS is arranged to capture, by means of a lens or lens group L, not only the zeroth order diffracted beams, but also first-order or first- and higher-order diffracted beams (not shown).
  • dipole illumination for imaging line patterns extending in a direction perpendicular to a line can be used to utilize the resolution enhancement effect of dipole illumination.
  • first-order diffracted beams interfere with corresponding zeroth-order diffracted beams at the level of the wafer W to create an image of the line pattern MP at highest possible resolution and process window (i.e., usable depth of focus in combination with tolerable exposure dose deviations).
  • astigmatism aberration can be reduced by providing radiation poles (not shown) in opposite quadrants of the illumination system pupil IPU. Further, in some embodiments, astigmatism aberration can be reduced by blocking the zeroth order beams in the pupil conjugate PPU of the projection system associated with radiation poles in opposite quadrants. This is described in more detail in US 7,511,799 B2, issued Mar. 31, 2009, which is incorporated by reference herein in its entirety.
  • the substrate table WT can be moved accurately (for example, so as to position different target portions C in the path of the radiation beam B).
  • the first positioner PM and another position sensor can be used to accurately position the mask MA with respect to the path of the radiation beam B (for example, after mechanical retrieval from a mask library or during a scan).
  • movement of the mask table MT can be realized with the aid of a long-stroke module (coarse positioning) and a short-stroke module (fine positioning), which form part of the first positioner PM.
  • movement of the substrate table WT can be realized using a long-stroke module and a short-stroke module, which form part of the second positioner PW.
  • the mask table MT can be connected to a short-stroke actuator only or can be fixed.
  • Mask MA and substrate W can be aligned using mask alignment marks Ml, M2, and substrate alignment marks Pl, P2.
  • the substrate alignment marks (as illustrated) occupy dedicated target portions, they can be located in spaces between target portions (known as scribe-lane alignment marks). Similarly, in situations in which more than one die is provided on the mask MA, the mask alignment marks can be located between the dies.
  • Mask table MT and patterning device MA can be in a vacuum chamber V, where an invacuum robot IVR can be used to move patterning devices such as a mask in and out of vacuum chamber.
  • an out- of-vacuum robot can be used for various transportation operations, similar to the in-vacuum robot IVR. Both the in-vacuum and out-of-vacuum robots need to be calibrated for a smooth transfer of any payload (e.g., mask) to a fixed kinematic mount of a transfer station.
  • the lithographic apparatus 100 and 100’ can be used in at least one of the following modes:
  • step mode the support structure (for example, mask table) MT and the substrate table WT are kept essentially stationary, while an entire pattern imparted to the radiation beam B 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.
  • the support structure (for example, mask table) MT and the substrate table WT are scanned synchronously while a pattern imparted to the radiation beam B is projected onto a target portion C (i.e., a single dynamic exposure).
  • the velocity and direction of the substrate table WT relative to the support structure (for example, mask table) MT can be determined by the (de-)magnification and image reversal characteristics of the projection system PS.
  • the support structure (for example, mask table) MT is kept substantially stationary holding a programmable patterning device, and the substrate table WT is moved or scanned while a pattern imparted to the radiation beam B is projected onto a target portion C.
  • a pulsed radiation source SO can be employed and the programmable patterning device is updated as required after each movement of the substrate table WT or in between successive radiation pulses during a scan.
  • This mode of operation can be readily applied to maskless lithography that utilizes a programmable patterning device, such as a programmable mirror array.
  • lithographic apparatus 100 includes an extreme ultraviolet
  • EUV EUV
  • the EUV source is configured in a radiation system, and a corresponding illumination system is configured to condition the EUV radiation beam of the EUV source.
  • FIG. 2 shows the lithographic apparatus 100 in more detail, including the source collector apparatus SO, the illumination system IL, and the projection system PS.
  • the source collector apparatus SO is constructed and arranged such that a vacuum environment can be maintained in an enclosing structure 220 of the source collector apparatus SO.
  • An EUV radiation emitting plasma 210 can be formed by a discharge produced plasma source. EUV radiation can be produced by a gas or vapor, for example Xe gas, Li vapor, or Sn vapor in which the very hot plasma 210 is created to emit radiation in the EUV range of the electromagnetic spectrum.
  • the very hot plasma 210 is created by, for example, an electrical discharge causing at least a partially ionized plasma.
  • Partial pressures of, for example, 10 Pa of Xe, Li, Sn vapor, or any other suitable gas or vapor can be required for efficient generation of the radiation.
  • a plasma of excited tin (Sn) is provided to produce EUV radiation.
  • the radiation emitted by the hot plasma 210 is passed from a source chamber 211 into a collector chamber 212 via an optional gas barrier or contaminant trap 230 (in some cases also referred to as contaminant barrier or foil trap), which is positioned in or behind an opening in source chamber 211.
  • the contaminant trap 230 can include a channel structure.
  • Contamination trap 230 can also include a gas barrier or a combination of a gas barrier and a channel structure.
  • the contaminant trap or contaminant barrier 230 further indicated herein at least includes a channel structure.
  • the collector chamber 212 can include a radiation collector CO, which can be a so-called grazing incidence collector.
  • Radiation collector CO has an upstream radiation collector side 251 and a downstream radiation collector side 252. Radiation that traverses collector CO can be reflected off a grating spectral filter 240 to be focused in a virtual source point INTF.
  • the virtual source point INTF is commonly referred to as the intermediate focus, and the source collector apparatus is arranged such that the intermediate focus INTF is located at or near an opening 219 in the enclosing structure 220.
  • the virtual source point INTF is an image of the radiation emitting plasma 210.
  • Grating spectral filter 240 is used in particular for suppressing infra-red (IR) radiation.
  • the radiation traverses the illumination system IL, which can include a faceted field mirror device 222 and a faceted pupil mirror device 224 arranged to provide a desired angular distribution of the radiation beam 221, at the patterning device MA, as well as a desired uniformity of radiation intensity at the patterning device MA.
  • the illumination system IL can include a faceted field mirror device 222 and a faceted pupil mirror device 224 arranged to provide a desired angular distribution of the radiation beam 221, at the patterning device MA, as well as a desired uniformity of radiation intensity at the patterning device MA.
  • More elements than shown can generally be present in illumination optics unit IL and projection system PS.
  • the grating spectral filter 240 can optionally be present, depending upon the type of lithographic apparatus. Further, there can be more mirrors present than those shown in the FIG. 2, for example there can be one to six additional reflective elements present in the projection system PS than shown in FIG. 2.
  • Collector optic CO is depicted as a nested collector with grazing incidence reflectors 253, 254, and 255, just as an example of a collector (or collector mirror).
  • the grazing incidence reflectors 253, 254, and 255 are disposed axially symmetric around an optical axis O and a collector optic CO of this type is preferably used in combination with a discharge produced plasma source, often called a DPP source.
  • FIG. 3 shows a lithographic cell 300, also sometimes referred to a lithocell or cluster, according to some embodiments.
  • Lithographic apparatus 100 or 100’ can form part of lithographic cell 300.
  • Lithographic cell 300 can also include one or more apparatuses to perform pre- and post-exposure processes on a substrate. In some examples, these include spin coaters SC to deposit resist layers, developers DE to develop exposed resist, chill plates CH, and bake plates BK.
  • a substrate handler, or robot, RO picks up substrates from input/output ports I/Ol, I/O2, moves them between the different process apparatuses and delivers them to the loading bay LB of the lithographic apparatus 100 or 100’.
  • alignment marks are generally provided on the substrate, and the lithographic apparatus includes one or more inspection apparatuses for accurate positioning of marks on a substrate.
  • These alignment apparatuses are effectively position measuring apparatuses.
  • Different types of marks and different types of alignment apparatuses and/or systems are known from different times and different manufacturers.
  • a type of system widely used in current lithographic apparatus is based on a selfreferencing interferometer as described in U.S. Patent No. 6,961,116 (den Boef et al.). Generally marks are measured separately to obtain X- and Y-positions.
  • a combined X- and Y-measurement can be performed using the techniques described in U.S. Publication No. 2009/195768 A (Bijnen et al.), however. The full contents of both of these disclosures are incorporated herein by reference.
  • FIG. 4A shows a schematic of a cross-sectional view of an inspection apparatus 400 that can be implemented as a part of lithographic apparatus 100 or 100’, according to some embodiments.
  • inspection apparatus 400 can be configured to align a substrate (e.g., substrate W) with respect to a patterning device (e.g., patterning device MA).
  • Inspection apparatus 400 can be further configured to detect positions of alignment marks on the substrate and to align the substrate with respect to the patterning device or other components of lithographic apparatus 100 or 100’ using the detected positions of the alignment marks.
  • Such alignment of the substrate can ensure accurate exposure of one or more patterns on the substrate.
  • inspection apparatus 400 can include an illumination system 412, a beam splitter 414, an interferometer 426, a detector 428, a beam analyzer 430, and an overlay calculation processor 432.
  • Illumination system 412 can be configured to provide an electromagnetic narrow band radiation beam 413 having one or more passbands.
  • the one or more passbands can be within a spectrum of wavelengths between about 500 nm to about 900 nm.
  • the one or more passbands can be discrete narrow passbands within a spectrum of wavelengths between about 500 nm to about 900 nm.
  • Illumination system 412 can be further configured to provide one or more passbands having substantially constant center wavelength (CWL) values over a long period of time (e.g., over a lifetime of illumination system 412).
  • CWL center wavelength
  • Such configuration of illumination system 412 can help to prevent the shift of the actual CWL values from the desired CWL values, as discussed above, in current alignment systems. And, as a result, the use of constant CWL values can improve long-term stability and accuracy of alignment systems (e.g., inspection apparatus 400) compared to the current alignment apparatuses.
  • beam splitter 414 can be configured to receive radiation beam 413 and split radiation beam 413 into at least two radiation sub-beams.
  • radiation beam 413 can be split into radiation sub-beams 415 and 417, as shown in FIG. 4A.
  • Beam splitter 414 can be further configured to direct radiation sub-beam 415 onto a substrate 420 placed on a stage 422.
  • the stage 422 is movable along direction 424.
  • Radiation sub-beam 415 can be configured to illuminate an alignment mark or a target 418 located on substrate 420. Alignment mark or target 418 can be coated with a radiation sensitive film.
  • alignment mark or target 418 can have one hundred and eighty degrees (i.e., 180°) symmetry. That is, when alignment mark or target 418 is rotated 180° about an axis of symmetry perpendicular to a plane of alignment mark or target 418, rotated alignment mark or target 418 can be substantially identical to an unrotated alignment mark or target 418.
  • the target 418 on substrate 420 can be (a) a resist layer grating comprising bars that are formed of solid resist lines, or (b) a product layer grating, or (c) a composite grating stack in an overlay target structure comprising a resist grating overlaid or interleaved on a product layer grating. The bars can alternatively be etched into the substrate.
  • This pattern is sensitive to chromatic aberrations in the lithographic projection apparatus, particularly the projection system PL, and illumination symmetry and the presence of such aberrations will manifest themselves in a variation in the printed grating.
  • One in-line method used in device manufacturing for measurements of line width, pitch, and critical dimension makes use of a technique known as “scatterometry”. Methods of scatterometry are described in Raymond et al., “Multiparameter Grating Metrology Using Optical Scatterometry”, J. Vac. Sci. Tech. B, Vol. 15, no. 2, pp. 361-368 (1997) and Niu et al., “Specular Spectroscopic Scatterometry in DUV Lithography”, SPIE, Vol.
  • beam splitter 414 can be further configured to receive diffraction radiation beam 419 and split diffraction radiation beam 419 into at least two radiation sub-beams, according to an embodiment.
  • Diffraction radiation beam 419 can be split into diffraction radiation subbeams 429 and 439, as shown in FIG. 4A.
  • beam splitter 414 is shown to direct radiation subbeam 415 towards alignment mark or target 418 and to direct diffracted radiation sub-beam 429 towards interferometer 426, the disclosure is not so limiting. It would be apparent to a person skilled in the relevant art that other optical arrangements can be used to obtain the similar result of illuminating alignment mark or target 418 on substrate 420 and detecting an image of alignment mark or target 418.
  • interferometer 426 can be configured to receive radiation subbeam 417 and diffracted radiation sub-beam 429 through beam splitter 414.
  • diffracted radiation sub-beam 429 can be at least a portion of radiation sub-beam 415 that can be reflected from alignment mark or target 418.
  • interferometer 426 comprises any appropriate set of optical-elements, for example, a combination of prisms that can be configured to form two images of alignment mark or target 418 based on the received diffracted radiation sub-beam 429. It should be appreciated that a good quality image need not be formed, but that the features of alignment mark 418 should be resolved.
  • Interferometer 426 can be further configured to rotate one of the two images with respect to the other of the two images 180° and recombine the rotated and unrotated images interferometrically.
  • detector 428 can be configured to receive the recombined image via interferometer signal 427 and detect interference as a result of the recombined image when alignment axis 421 of inspection apparatus 400 passes through a center of symmetry (not shown) of alignment mark or target 418.
  • Such interference can be due to alignment mark or target 418 being 180° symmetrical, and the recombined image interfering constructively or destructively, according to an example embodiment.
  • detector 428 can be further configured to determine a position of the center of symmetry of alignment mark or target 418 and consequently, detect a position of substrate 420.
  • alignment axis 421 can be aligned with an optical beam perpendicular to substrate 420 and passing through a center of image rotation interferometer 426.
  • Detector 428 can be further configured to estimate the positions of alignment mark or target 418 by implementing sensor characteristics and interacting with wafer mark process variations.
  • detector 428 determines the position of the center of symmetry of alignment mark or target 418 by performing one or more of the following measurements:
  • This data can, for example, be obtained with any type of alignment sensor, for example a
  • beam analyzer 430 can be configured to receive and determine an optical state of diffracted radiation sub-beam 439.
  • the optical state can be a measure of beam wavelength, polarization, or beam profile.
  • Beam analyzer 430 can be further configured to determine a position of stage 422 and correlate the position of stage 422 with the position of the center of symmetry of alignment mark or target 418. As such, the position of alignment mark or target 418 and, consequently, the position of substrate 420 can be accurately known with reference to stage 422.
  • beam analyzer 430 can be configured to determine a position of inspection apparatus 400 or any other reference element such that the center of symmetry of alignment mark or target 418 can be known with reference to inspection apparatus 400 or any other reference element.
  • Beam analyzer 430 can be a point or an imaging polarimeter with some form of wavelength-band selectivity.
  • beam analyzer 430 can be directly integrated into inspection apparatus 400, or connected via fiber optics of several types: polarization preserving single mode, multimode, or imaging, according to other embodiments.
  • beam analyzer 430 can be further configured to determine the overlay data between two patterns on substrate 420.
  • One of these patterns can be a reference pattern on a reference layer.
  • the other pattern can be an exposed pattern on an exposed layer.
  • the reference layer can be an etched layer already present on substrate 420.
  • the reference layer can be generated by a reference pattern exposed on the substrate by lithographic apparatus 100 and/or 100’.
  • the exposed layer can be a resist layer exposed adjacent to the reference layer.
  • the exposed layer can be generated by an exposure pattern exposed on substrate 420 by lithographic apparatus 100 or 100’.
  • the exposed pattern on substrate 420 can correspond to a movement of substrate 420 by stage 422.
  • the measured overlay data can also indicate an offset between the reference pattern and the exposure pattern.
  • the measured overlay data can be used as calibration data to calibrate the exposure pattern exposed by lithographic apparatus 100 or 100’, such that after the calibration, the offset between the exposed layer and the reference layer can be minimized.
  • beam analyzer 430 can be further configured to determine a model of the product stack profile of substrate 420, and can be configured to measure overlay, critical dimension, and focus of target 418 in a single measurement.
  • the product stack profile contains information on the stacked product such as alignment mark, target 418, or substrate 420, and can include mark process variation-induced optical signature metrology that is a function of illumination variation.
  • the product stack profile can also include product grating profile, mark stack profile, and mark asymmetry information.
  • An example of beam analyzer 430 is YieldstarTM, manufactured by ASML, Veldhoven, The Netherlands, as described in U.S. Patent No. 8,706,442, which is incorporated by reference herein in its entirety.
  • Beam analyzer 430 can be further configured to process information related to a particular property of an exposed pattern in that layer.
  • beam analyzer 430 can process an overlay parameter (an indication of the positioning accuracy of the layer with respect to a previous layer on the substrate or the positioning accuracy of the first layer with respective to marks on the substrate), a focus parameter, and/or a critical dimension parameter (e.g., line width and its variations) of the depicted image in the layer.
  • Other parameters are image parameters relating to the quality of the depicted image of the exposed pattern.
  • an array of detectors can be connected to beam analyzer 430, and allows the possibility of accurate stack profile detection as discussed below.
  • detector 428 can be an array of detectors.
  • the detector array a number of options are possible: a bundle of multimode fibers, discrete pin detectors per channel, or CCD or CMOS (linear) arrays.
  • CCD or CMOS linear arrays.
  • the use of a bundle of multimode fibers enables any dissipating elements to be remotely located for stability reasons.
  • Discrete PIN detectors offer a large dynamic range but each need separate pre-amps. The number of elements is therefore limited.
  • CCD linear arrays offer many elements that can be read-out at high speed and are especially of interest if phase-stepping detection is used.
  • a second beam analyzer 430’ can be configured to receive and determine an optical state of diffracted radiation sub-beam 429, as shown in FIG. 4B.
  • the optical state can be a measure of beam wavelength, polarization, or beam profile.
  • Second beam analyzer 430’ can be identical to beam analyzer 430.
  • second beam analyzer 430’ can be configured to perform at least all the functions of beam analyzer 430, such as determining a position of stage 422 and correlating the position of stage 422 with the position of the center of symmetry of alignment mark or target 418. As such, the position of alignment mark or target 418 and, consequently, the position of substrate 420, can be accurately known with reference to stage 422.
  • Second beam analyzer 430’ can also be configured to determine a position of inspection apparatus 400, or any other reference element, such that the center of symmetry of alignment mark or target 418 can be known with reference to inspection apparatus 400, or any other reference element. Second beam analyzer 430’ can be further configured to determine the overlay data between two patterns and a model of the product stack profile of substrate 420. Second beam analyzer 430’ can also be configured to measure overlay, critical dimension, and focus of target 418 in a single measurement.
  • second beam analyzer 430’ can be directly integrated into inspection apparatus 400, or it can be connected via fiber optics of several types: polarization preserving single mode, multimode, or imaging, according to other embodiments.
  • second beam analyzer 430’ and beam analyzer 430 can be combined to form a single analyzer (not shown) configured to receive and determine the optical states of both diffracted radiation sub-beams 429 and 439.
  • processor 432 receives information from detector 428 and beam analyzer 430.
  • processor 432 can be an overlay calculation processor.
  • the information can comprise a model of the product stack profile constructed by beam analyzer 430.
  • processor 432 can construct a model of the product mark profile using the received information about the product mark.
  • processor 432 constructs a model of the stacked product and overlay mark profile using or incorporating a model of the product mark profile. The stack model is then used to determine the overlay offset and minimizes the spectral effect on the overlay offset measurement.
  • Processor 432 can create a basic correction algorithm based on the information received from detector 428 and beam analyzer 430, including but not limited to the optical state of the illumination beam, the alignment signals, associated position estimates, and the optical state in the pupil, image, and additional planes.
  • the pupil plane is the plane in which the radial position of radiation defines the angle of incidence and the angular position defines the azimuth angle of the radiation.
  • Processor 432 can utilize the basic correction algorithm to characterize the inspection apparatus 400 with reference to wafer marks and/or alignment marks 418.
  • processor 432 can be further configured to determine printed pattern position offset error with respect to the sensor estimate for each mark based on the information received from detector 428 and beam analyzer 430.
  • the information includes but is not limited to the product stack profile, measurements of overlay, critical dimension, and focus of each alignment marks or target 418 on substrate 420.
  • Processor 432 can utilize a clustering algorithm to group the marks into sets of similar constant offset error, and create an alignment error offset correction table based on the information.
  • the clustering algorithm can be based on overlay measurement, the position estimates, and additional optical stack process information associated with each set of offset errors.
  • the overlay is calculated for a number of different marks, for example, overlay targets having a positive and a negative bias around a programmed overlay offset.
  • the target that measures the smallest overlay is taken as reference (as it is measured with the best accuracy). From this measured small overlay, and the known programmed overlay of its corresponding target, the overlay error can be deduced. Table 1 illustrates how this can be performed.
  • the smallest measured overlay in the example shown is -1 nm. However this is in relation to a target with a programmed overlay of -30 nm. The process may have introduced an overlay error of 29 nm.
  • the smallest value can be taken to be the reference point and, relative to this, the offset can be calculated between measured overlay and that expected due to the programmed overlay. This offset determines the overlay error for each mark or the sets of marks with similar offsets.
  • the smallest measured overlay was -1 nm, at the target position with programmed overlay of 30 nm.
  • the difference between the expected and measured overlay at the other targets is compared to this reference.
  • a table such as Table 1 can also be obtained from marks and target 418 under different illumination settings, the illumination setting, which results in the smallest overlay error, and its corresponding calibration factor, can be determined and selected.
  • processor 432 can group marks into sets of similar overlay error. The criteria for grouping marks can be adjusted based on different process controls, for example, different error tolerances for different processes.
  • processor 432 can confirm that all or most members of the group have similar offset errors, and apply an individual offset correction from the clustering algorithm to each mark, based on its additional optical stack metrology. Processor 432 can determine corrections for each mark and feed the corrections back to lithographic apparatus 100 or 100’ for correcting errors in the overlay, for example, by feeding corrections into the inspection apparatus 400.
  • the present disclosure describes exemplary embodiments of a metrology apparatus and for measuring multiple directions of alignments, or overlays in parallel using parallel sensor concepts that geometrically arrange sensors in a space to allow parallel acquisitions.
  • a beam analyzer system may comprise a prism assembly, often referred to as an optical pupil symmetrizer (OPS).
  • OPS optical pupil symmetrizer
  • the OPS may remove all odd symmetry in an input beam. However, half of the light may be sacrificed in this process. OPS may also cover odd pupil homogeneity in a portion of the beam analyzer optics.
  • the odd symmetry may be removed by splitting the input beam into two beams and rotating one beam around the optical axis relative to the other beam, and eventually recombining the two beams.
  • the odd symmetry may be removed in this process, but the incoherent internal cross talk is not eliminated or its contribution to an overlay (OVL) error due to the introduction of an odd homogeneity coming after OPS.
  • OPL overlay
  • Most beam analyzers shine a beam of light onto a repeating pattern of alignment or, overlay marks on a substrate, and the resulting pattern may be predicted. If the scattered light is collected using a camera, the prediction may be compared to the reality to see if the patterns match. It also may be deduced how well the patterns of alignment or, overlay marks has been printed.
  • Most beam analyzers include one illumination mode selector (IMS).
  • IMS may have a plurality of apertures, where each aperture transmits light. The IMS may be arranged in such a way that a plurality of illumination modes exist.
  • multiple images may be created by micro diffraction based overlay (uDBO) at the same time, for both normal and complementary channels, in either the x- or y-direction.
  • uDBO is diffraction based overlay that enables overlay measurements on smaller alignment marks, but may require a very high contrast ratio.
  • any intensity from x into y, or vice versa, y into x is incoherent internal cross talk.
  • the intensity may be, for example, light that is projected in a false position or wrong direction.
  • the incoherent internal cross talk may directly affect the OVL error.
  • a second IMS may be added to the beam analyzer, such that at least two are present.
  • the second IMS will be able to block the light that crosses between quadrants.
  • FIGS. 5A and 5B show an illumination pupil and corresponding uDBO images, according to some embodiments.
  • FIG. 5A shows how illumination pupil can be configured with quadrants 510 and 520.
  • FIG. 5B shows how incoherent internal cross talk occurs in normal channels and complementary channels.
  • the incoherent internal cross talk occurs between all uDBO images associated with illumination pupils 510 and 520. .
  • each quadrant 510 and 520 may be followed with an intensity calibration in order to anticipate the amount of incoherent cross talk intensity that leaks to the image location assigned for the other quadrant for the overlay calculation.
  • the intensity difference balance may be between quadrant A 510 and quadrant B 520, as seen in FIG. 5 A. This intensity difference is the result of residual odd pupil homogeneity up to the uDBO camera.
  • Each single quadrant measurement enables imaging only in either the x- or y-direction, exclusively and sequentially. By measuring both separately, but sequentially, the possibility of incoherent internal cross talk is blocked and therefore, does not affect the OVL error.
  • the amount of incoherent internal cross talk may be better analyzed with sequential imaging, which can assist in the robustness of the beam analyzer.
  • IMS can allow a number of modes.
  • IMS matching from one beam analyzer machine to another beam analyzer machine may be difficult. Specifically, an image taken on one beam analyzer machine versus the same image taken on another beam analyzer machine may occasionally give different results. The difference may be due to any possible mismatches in the the aberrations and/or of the alignment mark configuration on the substrate or the calibration efficiency between machines may not be the same.
  • calibration can be used to increase consistency between multiple machines. Calibrations may include, but are not limited to DC offset, camera gain, and/or temperature. Aberrations may also occur when light from one image intrudes into another part of the image.
  • the present disclosure includes methods for blocking the aberrations, high coherence, or diffraction, and removing incoherent internal cross talk.
  • the second IMS is not eliminating aberrations or the such, but is blocking or removing an imaging channel such that there is only one active image channel at a time.
  • a second IMS may be added to remove incoherent internal cross talk. For example, by adding a second IMS, any image blurring mechanism by the aberrations, high coherence, or diffraction may be blocked, which may result in a more stable calibration.
  • a second IMS can allow for better accuracy in measurements and better correction factors, especially regarding the incoherence internal cross-talk.
  • systematic errors that result from the calibration may be hard to characterize. These systematic errors include, but are not limited to, wavelength, pitch of target, or how the light enters the optics.
  • a second IMS can be used to substantially eliminate incoherent internal cross talk between images taken. For example, at an alignment or overlay mark on a substrate, the target images for x- and y- alignment or overlay measurements are simultaneously formed during imaging. The alignment or overlay mark may be overfilled with light and when imaging, the light from neighboring features may be read out together, which is not intended. A smaller alignment or overlay mark may save the space required to measure the alignment or overlay. However, a too small of an alignment or overlay mark makes the incoherent internal cross talk more dominant.
  • a microchip may already exist on the substrate and surrounds the alignment or overlay mark. When imaged, the microchip may also generate undesired incoherent internal cross talk. Since the light may be on a different part of the image, aberration of the optics may occur, as light goes through the optics.
  • two quadrants may be illuminated at a different time to eliminate the incoherent internal cross talk.
  • the second IMS may be rotated such that only one pupil based quadrant is visible.
  • the light may enter one light path versus another light path, which leads to a system with no incoherent internal cross talk.
  • One light path may be probed, then the other light path in order to collect information.
  • This collected information may be used for calibration, which results in a correction factor.
  • This correction factor may be the factor used to eliminate the incoherent internal cross talk when two quadrants are utilized at the same time. Additionally, the correction factor may be used between multiple machines to take into account multiple machines.
  • a correction factor may be in a recipe to be used in many systems.
  • the recipe is a measurement program that allows the beam analyzer machine to add the correction factor calibrated into the software for that particular machine.
  • the correction factor may be used to train the systematic errors previously discussed. For example, by training the systematic errors into the recipe, systematic errors across multiple machines may be found to be similar and corrected for.
  • the recipe should not be used to teach the machines the incoherent internal cross talk, as the incoherent internal cross talk should be captured via additional hardware measurements, for example, by using a second IMS.
  • the second IMS characterizes optical hardware, which allows for software corrections, specifically the correction factor. Additionally, energy may be measured in a quadrant to evaluate the quality of the IMS.
  • the equation below describes how uDBO images calculate the overlay error out of four different intensities. Specifically, A + d, i x , A d, ix, B + d,+ix and B d,+ix would only for be for the x-overlay measurement.
  • a and B refer to the pupil quadrant, which is later depicted in FIGS. 6- 7, and are responsible for uDBO A- and B-images.
  • +d and -d refer to the bias programmed at the alignment or overlay target and +1/-1 refer to the first positive/negative diffraction from the target.
  • This formula may similarly be used for y. Under the influence of the incoherent internal crosstalk, for example, from y-image to x-image, the four x-intensities are partially contaminated by the proximity of neighboring y-images, as shown by arrows in FIG 5B.
  • the measured alignment or overlay information may be both stretched and shifted from the ideal alignment or overlay information, which should be measured under no crosstalk.
  • light may be shined into the two IMS present at the same time.
  • Either or both of the IMS may be changed and moved in order to get a measurement.
  • the incoherent internal cross talk may be calculated by measuring the leakage of intensity from X-image to Y-image or vice versa, and thereof. The cross talk may then be corrected for.
  • FIGS. 6 A and 6B show uDBO imaging associated with a first quadrant of illumination pupils with no incoherent internal cross talk, according to some embodiments.
  • FIG. 5A depicts the pupil after the first IMS.
  • FIG.. 6 A depicts the pupil allowing only a quadrant 620.
  • FIG. 6B shows the resulting uDBO images for the image made with the pupil in FIG. 6A and associated with illumination pupil 620. In such a way, only quadrant 620 is visible, but the other quadrants are not.
  • a correction factor may be calculated from the images taken in FIGS. 6A and 6B.
  • FIGS. 7A and 7B show uDBO imaging associated with a third quadrant of illumination pupils with no incoherent internal cross talk, according to some embodiments.
  • a different quadrant is imaged and a second IMS is selected.
  • FIG. 7A shows the second IMS imaging through a quadrant 710
  • FIG. 7B shows the resulting uDBO images for the image taken in FIG. 7A and associated with illumination pupils 710.
  • no incoherent internal cross talk occurs.
  • only quadrant 710 is visible, but the other quadrants are not.
  • a correction factor may be calculated from the images taken in FIGS. 7A and 7B.
  • IMS is positioned at its pupil conjugate location such that the other quadrants are blocked. Specifically, the first IMS opens two quadrants and the second IMS blocks one of the two quadrants at a post pupil conjugate.
  • the correction factor in order to increase accuracy, should be calculated at least once per system, per recipe.
  • the correction factor may be calculated multiple times using a first substrate. Once different substrates are used, the correction factor can be recalculated.
  • the correction factor may be calculated one per recipe per transfer on the machine, one per machine per recipe, one per recipe per substrate, etc.
  • the correction factor may be calculated every day or after a lapse of time. That lapse of time however, may be based on use of the machine.
  • FIG. 8 is a flowchart illustrating a method 800, according to some embodiments.
  • method 800 can be used for calibrating out the impact by pupil odd homogeneity and incoherent internal cross talk. It is to be appreciated that the operations may be performed in other orders, and that some operations may be optional.
  • a beam is passed sequentially through first and second selectors that each pass first and second quadrants of the beam.
  • the first and second selectors may be IMS’. Additionally, both of the selectors may be positioned at a corresponding pupil conjugate plane.
  • An aperture may also be used as the IMS’ or a mode-selecting selector a single quadrant filtering selector. At least one of the IMS may include at least one illumination mode at the other IMS.
  • step 804 the first and second quadrants are blocked using the second selector. By blocking a quadrant, a first image is generated.
  • step 806 the second selector is rotated around an optical axis.
  • step 808 third and fourth quadrants are blocked using the second selector. By blocking the different quadrant, a second image is generated. Additionally, the images may be taken sequentially. The images may be generated based on angular location of a quadrant.
  • step 810 an intensity difference in illumination is measured.
  • the difference is between the first and second quadrants and the third and fourth quadrants.
  • the comparison of the first and second images may be performed with a analyzer.
  • an intensity error is compensated, based on the measuring in step 810.
  • the intensity difference may be compensated using a calibration device, such that the intensity error is derived from such a calibration device.
  • the balancing may substantially eliminate any effects on an overlay error. This specifically refers to the overlay error being eliminated, which then substantially eliminates any incoherent internal cross talk and a pupil homogeneity based on the compensating.
  • a metrology system comprising: a first selector configured to pass first or second quadrants of light; a second selector configured to block the first or second quadrants to generate a first image before rotating around an optical axis and to block third or fourth quadrants to generate a second image; an analyzer configured to measure an intensity difference in illumination between the first or second quadrants and the third or fourth quadrants based on the first and second images; and a calibration device configured to compensate an intensity error between the first and second images, such that incoherent cross talk is substantially eliminated.
  • a method comprising: sequentially passing a beam through first and second selectors that each pass first or second quadrants of the beam; blocking, using the second selector, the first or second quadrants to generate a first image; rotating the second selector around an optical axis, blocking, using the second selector, third and fourth quadrants to generate a second image; measuring an intensity difference in illumination between the first and second quadrants and the third and fourth quadrants based on the first and second images; and compensating an intensity error based on the measuring, such that incoherent cross talk is substantially eliminated.
  • a lithographic apparatus comprising: an illumination system configured to illuminate a pattern of a patterning device; a support configured to support the patterning device; a substrate; a projection system configured to project an image of the pattern onto a substrate; and a metrology system comprising: a first selector configured to pass first and second quadrants of light; a second selector configured to block the first and second quadrants to generate a first image before rotating around an optical axis to block third and fourth quadrants to generate a second image; an analyzer configured to measure an intensity difference in illumination between the first and second quadrants and the third and fourth quadrants based on the first and second images; and a calibration device configured to compensate an intensity error between the first and second images, such that incoherent cross talk is substantially eliminated.
  • any use of the terms “wafer” or “die” herein can be considered as specific examples of the more general terms “substrate” or “target portion”, respectively.
  • the substrate referred to herein can be processed, before or after exposure, in for example a track unit (a tool that typically applies a layer of resist to a substrate and develops the exposed resist) and/or a metrology unit.
  • imprint lithography a topography in a patterning device defines the pattern created on a substrate.
  • the topography of the patterning device can be pressed into a layer of resist supplied to the substrate whereupon the resist is cured by applying electromagnetic radiation, heat, pressure or a combination thereof.
  • the patterning device is moved out of the resist leaving a pattern in it after the resist is cured.
  • UV radiation for example, having a wavelength I of 365, 248, 193, 157 or 126 nm
  • extreme ultraviolet (EUV or soft X-ray) radiation for example, having a wavelength in the range of 5-20 nm such as, for example, 13.5 nm
  • hard X-ray working at less than 5 nm as well as matter beams, such as ion beams or electron beams.
  • light can refer to non-matter radiation (e.g., photons, UV, X-ray, or the like).
  • UV refers to radiation with wavelengths of approximately 100-400 nm.
  • Vacuum UV, or VUV refers to radiation having a wavelength of approximately 100-200 nm.
  • Deep UV generally refers to radiation having wavelengths ranging from 126 nm to 428 nm, and in some embodiments, an excimer laser can generate DUV radiation used within a lithographic apparatus. It should be appreciated that radiation having a wavelength in the range of, for example, 5-20 nm relates to radiation with a certain wavelength band, of which at least part is in the range of 5-20 nm.

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Abstract

L'invention concerne des modes de réalisation qui concernent un appareil de métrologie et un procédé de mesure de multiples repères en parallèle à l'aide de concepts de capteurs parallèles qui permettent d'agencer géométriquement des capteurs dans un espace pour permettre des acquisitions parallèles. Des sélecteurs peuvent être conçus pour bloquer des quadrants d'un repère afin de générer des images. Une différence d'intensité entre des images acquises peut être comparée et équilibrée de telle sorte qu'une diaphonie interne incohérente est éliminée.
PCT/EP2024/050114 2023-02-02 2024-01-03 Sélecteur de second mode d'éclairage (ims) pour yieldstar Ceased WO2024160479A1 (fr)

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KR1020257023908A KR20250141704A (ko) 2023-02-02 2024-01-03 Yieldstar를 위한 제2 조명 모드 선택기(ims)
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