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WO2025067839A1 - Système de mesure de hauteur - Google Patents

Système de mesure de hauteur Download PDF

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Publication number
WO2025067839A1
WO2025067839A1 PCT/EP2024/074772 EP2024074772W WO2025067839A1 WO 2025067839 A1 WO2025067839 A1 WO 2025067839A1 EP 2024074772 W EP2024074772 W EP 2024074772W WO 2025067839 A1 WO2025067839 A1 WO 2025067839A1
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WO
WIPO (PCT)
Prior art keywords
radiation
wavelength
substrate
resist
height
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.)
Pending
Application number
PCT/EP2024/074772
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English (en)
Inventor
Sandy Claudia SCHOLZ
Christian Oliver SCHOLZ
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ASML Netherlands BV
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ASML Netherlands BV
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Filing date
Publication date
Application filed by ASML Netherlands BV filed Critical ASML Netherlands BV
Publication of WO2025067839A1 publication Critical patent/WO2025067839A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
    • G03F9/7023—Aligning or positioning in direction perpendicular to substrate surface
    • G03F9/7034—Leveling
    • 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
    • G03F9/00—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically
    • G03F9/70—Registration or positioning of originals, masks, frames, photographic sheets or textured or patterned surfaces, e.g. automatically for microlithography
    • G03F9/7003—Alignment type or strategy, e.g. leveling, global alignment
    • G03F9/7023—Aligning or positioning in direction perpendicular to substrate surface
    • G03F9/7026—Focusing

Definitions

  • the present disclosure relates to a system for measuring the height of a resist-covered surface of a substrate.
  • the system may be located in a lithographic apparatus.
  • 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”) of a patterning device (e.g., a mask also referred to as a reticle) onto a layer of radiationsensitive material (resist) provided on a substrate (e.g., a wafer).
  • a lithographic apparatus may use electromagnetic radiation.
  • the wavelength of this radiation determines the minimum size of features which are patterned on the substrate. Typical wavelengths currently in use are 365 nm (i-line), 248 nm, 193 nm and 13.5 nm.
  • a lithographic apparatus which uses extreme ultraviolet (EUV) radiation, having a wavelength within a range of 4 nm to 20 nm, for example 6.7 nm or 13.5 nm, may be used to form smaller features on a substrate than a lithographic apparatus which uses, for example, radiation with a wavelength of 193 nm.
  • EUV extreme ultraviolet
  • Different points across a surface of the substrate may be at different heights, and so lithographic radiation focused on the surface of the substrate at a first point (at a first height) may not be in focus at a second point (at a second height).
  • the height of the surface of the substrate is measured and corresponding adjustments of the lithographic apparatus are made. Measuring the height of a substrate may be referred to as a topography measurement.
  • a problem associated with conventional height measurement systems is that they are unable to accommodate variations of resist thickness on a substrate. Consequently, resist thickness variations may cause inaccurate outputs from a conventional height measurement system. This may in turn cause inaccurate focusing of a pattern which is projected by the lithographic apparatus. [0007] It may be desirable to provide a system that obviates or mitigates one or more problems associated with the prior art.
  • a system for measuring the height of a resist-covered surface of a substrate comprising a projection unit comprising at least one radiation source configured to emit radiation having a first wavelength and radiation having a second wavelength, the projection unit being configured to direct the radiation having the first and second wavelengths onto the resist covered surface of the substrate, the first wavelength being absorbed more by the resist than the second wavelength, a detection system configured to measure the radiation reflected from the substrate and resist in the first and second wavelengths, and a processor configured to process the measured first and second wavelength radiation to obtain a height map for the substrate, wherein the height map substantially compensates for thickness variation of the resist on the substrate.
  • the system substantially compensates for thickness variation of the resist on the substrate, inaccurate focusing of a pattern which is projected by the lithographic apparatus is reduced.
  • the projection unit may be configured to direct the radiation having the first wavelength and the radiation having the second wavelength simultaneously onto the resist covered surface of the substrate.
  • the first wavelength may be ultraviolet.
  • the second wavelength may be infrared.
  • the processor may be configured to determine a weighted average of the measured first wavelength radiation and the measured second wavelength radiation.
  • the projection unit may be configured to direct the first and second wavelength radiation as collinear beams of radiation.
  • the at least one radiation source may comprise a broadband emitter and a wavelength selective filter.
  • the wavelength selective filter may be a grating light valve.
  • the second wavelength may be infrared and the second radiation source may form part of an alignment system.
  • the detection system may comprise one or more first detectors configured to detect radiation having the first wavelength, and one or more second detectors configured to detect radiation having the second wavelength.
  • the one or more second detectors may be located adjacent to the one or more first detectors.
  • the system may further comprise at least one dichroic mirror configured to separate the second wavelength radiation from the first wavelength radiation.
  • the one or more first detectors may be a first pair of detectors and the one or more second detectors may be a second pair of detectors.
  • the detection system may comprise a detector configured to detect the first wavelength radiation and the second wavelength radiation.
  • a lithographic apparatus comprising the system of the first aspect.
  • a method of measuring the height of a resist-covered surface of a substrate comprising directing a first beam of radiation having a first wavelength and a second beam of radiation onto the resist-covered surface of the substrate, the first wavelength being absorbed more by the resist than the second wavelength, measuring the radiation reflected from the substrate and resist in the first and second wavelengths, and processing the measured first and second wavelength radiation to obtain a height map for the substrate, wherein the height map substantially compensates for thickness variation of the resist on the substrate.
  • the method substantially compensates for thickness variation of the resist on the substrate, inaccurate focusing of a pattern which is projected by the lithographic apparatus is reduced.
  • the first and second beams of radiation may be directed onto the resist-covered surface of the substrate simultaneously and are measured simultaneously.
  • the processing may comprise determining a weighted average of the measured first wavelength radiation and the measured second wavelength radiation.
  • Weights used to obtain the weighted average may be determined during a calibration.
  • the calibration may be performed using test exposures of substrates which correspond with the substrate being measured.
  • the resist may have a thickness of at least 5pm.
  • Figure 1 schematically depicts a lithographic apparatus which includes a height measurement system according to an embodiment of the disclosure
  • FIG. 2 schematically depicts the height measurement system in more detail
  • Figure 3 schematically depicts an alternative detection system of the height measurement system.
  • 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).
  • 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.
  • 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) MT 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.
  • 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 radiation beam B is incident on the patterning device, e.g. mask, MA which is held on the mask support MT, 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 MT, and is patterned by the pattern (design layout) present on patterning device 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 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
  • 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.
  • a Cartesian coordinate system is used.
  • the Cartesian coordinate system has three axes, i.e., an x-axis, a y-axis and a z-axis. Each of the three axes is orthogonal to the other two axis.
  • a rotation around the x-axis is referred to as an Rx-rotation.
  • a rotation around the y- axis is referred to as an Ry -rotation.
  • a rotation around about the z-axis is referred to as an Rz-rotation.
  • the x-axis and the y-axis define a horizontal plane, whereas the z-axis is in a vertical direction.
  • Cartesian coordinate system is not limiting the disclosure and is used for clarification only. Instead, another coordinate system, such as a cylindrical coordinate system, may be used to clarify the disclosure.
  • the orientation of the Cartesian coordinate system may be different, for example, such that the z-axis has a component along the horizontal plane.
  • the height of the substrate W is indicated as the Z-direction.
  • a height measurement system LS is arranged to provide a height map of a resist covered surface of the substrate W.
  • the height measurement system LS may be referred to as a level sensor, or a topography measurement system.
  • a map of the height (z) of the resist covered surface of the substrate as a function of position (x, y) on the substrate may be generated from measurements obtained using the height measurement system LS. This height map may subsequently be used to adjust the vertical position of the substrate W, and/or to adjust the projection system PS, during projection of a pattern from the patterning device MA into the resist on the substrate.
  • the measured height of the resist covered surface of the substrate compensates for variations of thickness of resist on the substrate.
  • the height measurement system LS may be stationary.
  • the substrate table WT and substrate W may be moved in a scanning movement beneath the height measurement system LS. This allows the height measurement system to measure height across a surface of the substrate W and thereby generate a height map.
  • the height measurement system LS comprises a projection unit 10, a detection system 12, and a processor 15.
  • the projection unit 10 comprises a radiation source and optics.
  • the projection unit 10 is configured to provide a first beam of radiation having a first wavelength in an ultraviolet (UV) range between 10-400 nm, and a second beam of radiation having a second wavelength in an infra-red (IR) range between 700-1000 nm.
  • the first and second beams of radiation are incident upon the substrate W (including any patterned layers thereon) and are then detected by the detection system 12.
  • the positions at which the first and second beams of radiation are incident at the detection system 12 depend upon the height of the substrate W and the thickness of resist on the substrate (as explained further below). This allows the height of the substrate W to be measured, including compensation for thickness variation of the resist on the substrate.
  • the height measurement system LS is depicted in more detail in Figure 2.
  • the projection unit 10 comprises a radiation source 18.
  • the radiation source provides two beams of radiation, which in this embodiment comprises a UV beam 16 and an IR beam 17.
  • the UV beam 16 and the IR beam 17 are collinear when they are output from the projection unit 10.
  • the UV and IR beams are depicted as a single line 16,17 in Figure 2.
  • the radiation source 18 may for example be a broadband radiation source which emits both UV and IR radiation. Where this is the case, filters may be provided such that UV and IR radiation is filtered from the broadband radiation to provide collinear UV and IR beams.
  • the radiation source 18 may comprise a first emitter configured to emit UV radiation and a second emitter configured to emit IR radiation. Where this is the case, a dichroic mirror or other optics may be arranged to combine the UV and IR radiation to form collinear UV and IR beams.
  • the projection unit 10 further comprises optics in the form of a diffraction grating 20.
  • the diffraction grating is referred to as the projection grating 20, and applies a periodic structure to the UV and IR beams 16, 17.
  • the projection unit 10 may comprise additional optics (not depicted).
  • the UV and IR beams 16, 17 are incident upon the substrate W.
  • a layer of resist R is present on the substrate W.
  • the UV and IR beams 16, 17 are incident upon the substrate W and resist R.
  • UV and IR beams 16, 17 subtend an acute angle 0 with respect to a normal which extends from the substrate W (in other words, with respect to the Z-direction).
  • the UV beam 16 may be predominantly reflected from an upper surface of the resist R. This is schematically depicted in Figure 2 by a dotted line 16.
  • the IR beam 17 may be predominantly reflected by the upper surface of the substrate W. This is schematically depicted in Figure 2 by a dashed line 17.
  • the separation between the reflected UV beam 16 and the reflected IR beam 17 (and the thickness of the resist R) is exaggerated for ease of illustration.
  • some of the UV beam 16 may be reflected from the substrate W.
  • the UV beam 16 is strongly absorbed by the resist R.
  • the power of a portion of the UV beam 16 which is incident at the detection system 12 may be relatively low.
  • part of the IR beam 17 may be reflected from an upper surface of the resist R.
  • the IR beam 17 is not absorbed by the resist R.
  • a relatively high portion of the IR beam 17 incident at the detection system 12 has been reflected from the substrate W.
  • the term “relatively high portion” means a higher portion of the IR beam than of the UV beam.
  • the reflected UV beam 16 may tend to indicate the top of the resist R, and the reflected IR beam 17 may tend to indicate the bottom of the resist R (equivalently the top of the substrate W).
  • the detection system 12 comprises a diffraction grating 24 (referred to as the detection grating 24) and two pairs of detectors 26a, b, 27a, b.
  • the first pair of detectors 26a, b is positioned to detect the UV beam 16.
  • the second pair of detectors 27 a, b is positioned to detect the IR beam 17.
  • the reflected UV and IR beams 16, 17 form two images of the projection grating 20 at the detection grating 24.
  • the detection grating 24 may have a period which corresponds with the period of the grating images formed by the reflected radiation beams 16, 17.
  • the detection grating 24 diffracts the UV and IR beams 16, 17.
  • the first detector pair 26a, b is positioned to detect +1 and -1 diffraction orders of the diffracted UV beam 16.
  • the angle at which IR beam 17 is diffracted by the diffraction grating 24 is relatively large (compared with the angle at which the UV beam 16 is diffracted).
  • the second pair of detectors 27a,b are positioned to detect the +1 and -1 diffraction orders of the UV beam 17. Due to the difference in diffraction angles of the UV beam and IR beam 16, 17, the first and second pairs of detectors 26a, b, 27 a, b may be positioned adjacent to each other (for example as schematically depicted).
  • the position of the grating image formed by the UV beam 16 at the detection grating 24 will generally depend upon the height of the resist R.
  • the first and second detectors 26a, b will provide an output signal which generally depends upon the height of the resist R.
  • the position of the grating image formed by the IR beam 17 at the detection grating 24 will generally depend upon the height of the substrate W (i.e. the bottom of the resist R).
  • the second detector pair 27 a, b will detect an output signal which generally indicates the height of the substrate W.
  • the reflected UV beam 16 may include a component which has been reflected from the substrate W (i.e. the bottom of the resist R).
  • the UV beam 17 may include a component which has been reflected from the top of the resist R.
  • the UV beam 16 will tend to pick up the top of the resist R, and the IR beam 17 will tend to pick up the bottom of the resist R (i.e. the top of the substrate W).
  • the processor 15 receives signals output from the first and second pairs of detectors 26a, b, 27 a, b, and based on these signals determines a height map for the substrate W which compensates for variations in the thickness of the resist R. This is explained in detail further below.
  • the UV beam 16 may have a wavelength of 250nm and the IR beam 17 may have a wavelength of 1500nm.
  • the angle of incidence of the UV and IR beams 16, 17 may be 78°.
  • the UV and IR beams 16, 17 may both be S-polarized.
  • reflection from the surface of the resist R may be around 0.55 for the UV beam 16 and around 0.49 for the IR beam 17.
  • similar amounts of UV and IR may be reflected from the surface of the resist R.
  • the IR beam 17 has an absorption coefficient in the resist R of close to zero, whereas the UV beam 16 may be strongly absorbed by the resist R. Consequently, the position of the UV beam incident at the detection system 12 carries little or no information regarding the thickness of the resist R. In contrast, the position of the IR beam 17 may be significantly influenced by the thickness of the resist R.
  • the processor 15 may receive two signals from the detection system 12.
  • a first signal may be provided from the first pair of detectors 26a, b and may relate to the UV beam 16.
  • the second signal may be received from the second pair of detectors 27a, b and may relate to the IR beam 17.
  • the processor 15 may generate two surface maps using the two output signals.
  • a first surface map w uv generated using the first signal generally represents the upper surface of the resist R.
  • a second surface map wm generated using the second signal generally represents the surface of the substrate W (although this map may include a contribution connected to the height of the surface of the resist R).
  • the processor 15 may generate a weighted average f(w aV g) of both maps:
  • the values of A and B may be selected to determine the extent to which a map output from the processor 15 indicates the top surface of the resist R, the top surface of the substrate W or a position between the top surface of the resist and the top surface of the substrate (i.e. a position within the resist).
  • the map consists only of signals obtained from the UV beam. This may generally correspond with a map obtained using a conventional level sensing system, and may lead to imaging errors arising from variations of the thickness of the resist R.
  • the map consists only of signals obtained from the IR beam.
  • the resulting map may generally indicate the top surface of the substrate W. However, this map may include a contribution from the top surface of a resist R (and possibly also contributions from reflections within the substrate W itself).
  • a user may select values for A and B so that the map provides a position within the resist R. This reduces or eliminates errors arising from variations of the resist thickness.
  • the lithographic apparatus is then configured to focus at the height provided by the map. Patterns which are projected by the lithographic apparatus at a position within the resist may be formed more accurately in the resist (compared with patterns which are projected at the top of the resist - as may occur when a conventional height measurement system is used).
  • the processor 15 may provide a substrate height map which indicates the substrate height as being at a position between the bottom and top of the resist R. This position may be selected by the selection of the values A and B used by the weighted average.
  • test exposures using different values of A and B may be performed. The results may then be analyzed to determine values of A and B which will provide the most consistently accurate exposure of patterns. These values of A and B may then be used for subsequent exposures of that pattern. This is one example of a calibration of the weighted average. Other forms of calibration may be used.
  • Using a weighted average to obtain a height map using signals obtained from the UV and IR beams is one example of processing those signals to obtain a height map.
  • the signals may be processed in other ways.
  • the UV beam 16 and IR beam 17 are emitted simultaneously (and are measured simultaneously).
  • An advantage of this arrangement is that the UV and IR beams 16, 17 provide two height maps simultaneously. This means that there is no reduction of throughput of the lithographic apparatus when using embodiments of the invention, and no reduction of spatial resolution of the height maps.
  • the UV beam and IR beam are not simultaneously incident upon the resist covered surface of the substrate.
  • the UV beam may be chopped and the IR beam may be chopped, such that the UV and IR beams are alternately incident upon the resist covered surface of the substrate.
  • the UV beam and the IR beam may be incident at different times (e.g. alternating periodically) upon the resist covered surface of the substrate.
  • a disadvantage of this arrangement is that less height measurement data may be received (the height measurement data may have a lower spatial resolution). Interpolation between successive measured UV or measured IR values may be used when generating a height map.
  • a UV beam 16 and an IR beam 17 are used, this does not require extensive modification of the projection unit 10 or the detection system 12 (compared with a conventional height measurement system).
  • the gratings 20, 24 may be conventional.
  • Associated optics may also be conventional.
  • beams with other wavelengths may be used (e.g. an IR beam and a visible beam, or an IR beam and some other wavelength beam).
  • the first and second beams 16, 17 may have different polarizations. The use of different polarizations may allow further discrimination between the top of the resist R and the top of the substrate W.
  • Figure 3 depicts an alternative arrangement of the detection system 12.
  • the difference of diffraction angle experienced by the UV beam 16 and the diffraction angle experienced by the IR beam 17 is not sufficient to allow the detectors to be located adjacent to each other in the manner depicted in Figure 2.
  • dichroic mirrors 30 are used to reflect the IR beam 17.
  • the UV beam 16 passes through the dichroic mirrors 30 and is incident upon the first pair of detectors 26a, b.
  • the IR beam 17 is reflected by the dichroic mirrors 30 and is incident upon a second pair of detectors 28a, b.
  • the remainder of this embodiment of the invention may be the same as the embodiment described above in connection with Figure 2.
  • Embodiments of the invention may be particularly advantageous when patterning a substrate provided with a layer of resist that is thicker than a conventional layer of resist.
  • a conventional layer of resist may for example have a thickness of around lOOnm.
  • a substrate may however have a layer of resist that has a thickness of 5pm or more (e.g. up to 50pm). Substrates with such a thick layer of resist may be used for example when making 3D NAND devices.
  • a thick layer of resist is present on a substrate (e.g. 5pm or more)
  • a conventional height measurement system may provide a height map which is inaccurate due to variations of the thickness of the resist.
  • Embodiments of the invention may provide a more accurate height map.
  • Embodiments of the invention provide a height map which substantially compensates for resist thickness variation whilst a substrate is held on a substrate table in a lithographic apparatus. This is advantageous compared with for example measuring resist thickness variation in a metrology tool before the substrate is loaded into the lithographic apparatus.
  • a first advantage is that a metrology tool (which may be expensive) is not required.
  • a second advantage is that distortion of the substrate caused by the substrate table is measured by embodiments of the invention (but is not measured when a measurement is performed in a metrology tool).
  • the UV beam and IR beam are collinear.
  • the UV and IR beams do not have to be collinear and may for example have different angles of incidence at the substrate.
  • An advantage of the UV and IR beams being collinear is that they can both use the same optics.
  • separate detectors are used to detect the UV and IR beams.
  • a single detector may be used to detect both the UV and IR beams (or beams of other wavelengths).
  • the UV and IR beams (or beams of other wavelengths) may be incident at different positions on a single detector thereby allowing discrimination between them.
  • a pair of detectors is used to detect the UV beam and a pair of detectors is used to detect the IR beam.
  • other numbers of detectors may be used.
  • a single detector may be used to detect the UV beam.
  • a single detector may be used to detect the IR beam. Using a single detector for each wavelength in this manner may reduce a signal to noise ratio provided by the detection system.
  • the radiation source may comprise a first emitter configured to emit UV radiation and a second emitter configured to emit IR radiation.
  • the emitter configured to emit IR radiation may for example form part of an alignment sensing system of the lithographic apparatus.
  • an embodiment of the invention may include a so-called grating light valve to select wavelengths to form the first and second beams.
  • a grating light valve which is capable of selecting UV and IR wavelengths, is described in WO 2023046420 Al.
  • the grating light valve is an example of a wavelength selective filter. Other wavelength selective filters may be used.
  • Embodiments of the disclosure may form part of a lithographic apparatus (e.g. as depicted). Embodiments of the disclosure may form part of a lithographic tool. Examples of lithographic tools are mentioned further below.
  • Embodiments of the disclosure 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). These apparatus may be generally referred to as lithographic tools. Such a lithographic tool may use vacuum conditions or ambient (non-vacuum) conditions.
  • embodiments of the disclosure may 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 may 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 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, instructions may 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. and in doing that may cause actuators or other devices to interact with the physical world.
  • a system for measuring the height of a resist-covered surface of a substrate comprising: a projection unit comprising at least one radiation source configured to emit radiation having a first wavelength and radiation having a second wavelength, the projection unit being configured to direct the radiation having the first and second wavelengths onto the resist covered surface of the substrate, the first wavelength being absorbed more by the resist than the second wavelength; a detection system configured to measure the radiation reflected from the substrate and resist in the first and second wavelengths; and a processor configured to process the measured first and second wavelength radiation to obtain a height map for the substrate, wherein the height map substantially compensates for thickness variation of the resist on the substrate.
  • the projection unit is configured to direct the first and second wavelength radiation as collinear beams of radiation.
  • the at least one radiation source comprises a broadband emitter and a wavelength selective filter.
  • the at least one radiation source comprises a first radiation source configured to emit radiation at the first wavelength and a second radiation source configured to emit radiation at the second wavelength.
  • the detection system comprises one or more first detectors configured to detect radiation having the first wavelength, and one or more second detectors configured to detect radiation having the second wavelength.
  • system further comprises at least one dichroic mirror configured to separate the second wavelength radiation from the first wavelength radiation.
  • the detection system comprises a detector configured to detect the first wavelength radiation and the second wavelength radiation.
  • a lithographic apparatus comprising the system of any preceding clause.
  • a method of measuring the height of a resist-covered surface of a substrate comprising: directing a first beam of radiation having a first wavelength and a second beam of radiation onto the resist-covered surface of the substrate, the first wavelength being absorbed more by the resist than the second wavelength; measuring the radiation reflected from the substrate and resist in the first and second wavelengths; and processing the measured first and second wavelength radiation to obtain a height map for the substrate, wherein the height map substantially compensates for thickness variation of the resist on the substrate.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Length Measuring Devices By Optical Means (AREA)

Abstract

L'invention concerne un système de mesure de la hauteur d'une surface recouverte de réserve d'un substrat, le système comprenant une unité de projection comprenant au moins une source de rayonnement configurée pour émettre un rayonnement présentant une première longueur d'onde et un rayonnement présentant une seconde longueur d'onde, l'unité de projection étant configurée pour diriger le rayonnement présentant les première et seconde longueurs d'onde sur la surface recouverte de réserve du substrat, la première longueur d'onde étant davantage absorbée par la réserve que la seconde longueur d'onde, un système de détection configuré pour mesurer le rayonnement réfléchi par le substrat et pour résister dans les première et seconde longueurs d'onde, et un processeur configuré pour traiter le premier et le second rayonnement de longueur d'onde mesurés pour obtenir une carte de hauteur pour le substrat, la carte de hauteur compensant sensiblement la variation d'épaisseur de la réserve sur le substrat.
PCT/EP2024/074772 2023-09-28 2024-09-05 Système de mesure de hauteur Pending WO2025067839A1 (fr)

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EP23200407.7 2023-09-28
EP23200407 2023-09-28

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WO2025067839A1 true WO2025067839A1 (fr) 2025-04-03

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TW (1) TW202530889A (fr)
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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040130691A1 (en) * 1999-03-08 2004-07-08 Asml Netherlands B.V. Off-axis levelling in lithographic projection apparatus
US6952253B2 (en) 2002-11-12 2005-10-04 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
WO2018127266A1 (fr) 2017-01-09 2018-07-12 Max-Planck-Gesellschaft Zur Dispositif de source de lumière à large bande et procédé de création d'impulsions de lumière à large bande
US20180373171A1 (en) * 2015-12-22 2018-12-27 Asml Netherlands B.V. Topography measurement system
WO2023046420A1 (fr) 2021-09-22 2023-03-30 Asml Netherlands B.V. Module de sélection de sources, métrologie associée et appareils lithographiques

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040130691A1 (en) * 1999-03-08 2004-07-08 Asml Netherlands B.V. Off-axis levelling in lithographic projection apparatus
US6952253B2 (en) 2002-11-12 2005-10-04 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
US20180373171A1 (en) * 2015-12-22 2018-12-27 Asml Netherlands B.V. Topography measurement system
WO2018127266A1 (fr) 2017-01-09 2018-07-12 Max-Planck-Gesellschaft Zur Dispositif de source de lumière à large bande et procédé de création d'impulsions de lumière à large bande
WO2023046420A1 (fr) 2021-09-22 2023-03-30 Asml Netherlands B.V. Module de sélection de sources, métrologie associée et appareils lithographiques

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