WO2022111940A1 - Procédé d'étalonnage de positions de points de miroir, appareil lithographique et procédé de fabrication de dispositif - Google Patents

Procédé d'étalonnage de positions de points de miroir, appareil lithographique et procédé de fabrication de dispositif Download PDF

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Publication number
WO2022111940A1
WO2022111940A1 PCT/EP2021/080019 EP2021080019W WO2022111940A1 WO 2022111940 A1 WO2022111940 A1 WO 2022111940A1 EP 2021080019 W EP2021080019 W EP 2021080019W WO 2022111940 A1 WO2022111940 A1 WO 2022111940A1
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WO
WIPO (PCT)
Prior art keywords
interferometers
mirror
pairs
measurement
rotational position
Prior art date
Application number
PCT/EP2021/080019
Other languages
English (en)
Inventor
Johannes Mathias Theodorus Antonius ADRIAENS
Original Assignee
Asml Netherlands B.V.
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 B.V. filed Critical Asml Netherlands B.V.
Priority to KR1020237017428A priority Critical patent/KR20230109640A/ko
Priority to CN202180078767.4A priority patent/CN116472436A/zh
Publication of WO2022111940A1 publication Critical patent/WO2022111940A1/fr

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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
    • G03F7/70691—Handling of masks or workpieces
    • G03F7/70775—Position control, e.g. interferometers or encoders for determining the stage position
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02017—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations
    • G01B9/02018—Multipass interferometers, e.g. double-pass
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02017—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations
    • G01B9/02019—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations contacting different points on same face of object
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02017—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations
    • G01B9/02021—Interferometers characterised by the beam path configuration with multiple interactions between the target object and light beams, e.g. beam reflections occurring from different locations contacting different faces of object, e.g. opposite faces
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02015—Interferometers characterised by the beam path configuration
    • G01B9/02027—Two or more interferometric channels or interferometers
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01B—MEASURING LENGTH, THICKNESS OR SIMILAR LINEAR DIMENSIONS; MEASURING ANGLES; MEASURING AREAS; MEASURING IRREGULARITIES OF SURFACES OR CONTOURS
    • G01B9/00—Measuring instruments characterised by the use of optical techniques
    • G01B9/02—Interferometers
    • G01B9/02055—Reduction or prevention of errors; Testing; Calibration
    • G01B9/0207—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer
    • G01B9/02072—Error reduction by correction of the measurement signal based on independently determined error sources, e.g. using a reference interferometer by calibration or testing of interferometer

Definitions

  • a MIRROR SPOT POSITION CALIBRATING METHOD A MIRROR SPOT POSITION CALIBRATING METHOD.
  • a LITHOGRAPHIC APPARATUS AND A DEVICE MANUFACTURING METHOD A LITHOGRAPHIC APPARATUS AND A DEVICE MANUFACTURING METHOD
  • the present invention relates to a method for calibrating spot positions on a mirror of an interferometer system.
  • the invention further relates to a lithographic apparatus and a device manufacturing method.
  • 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) onto a layer of radiation-sensitive material (resist) provided on a substrate (e.g., a wafer).
  • a patterning device e.g., a mask
  • resist radiation-sensitive material
  • 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
  • Lithographic apparatus usually comprise positioning systems to position an object, wherein use is made of an interferometer system configured to measure a position of the object.
  • an interferometer system configured to measure a position of the object.
  • one or more light beams are directed to a mirror on an object to determine an optical path length difference of the one or more light beams compared to a reference optical path length.
  • the position of an interferometer light beam incident on a surface such as a mirror is indicated by a spot of light on the surface.
  • a light beam may be directed to and reflected off the mirror more than once.
  • Examples are so-called 2-pass interferometers in which the light beam is directed towards the object twice, so that two spots can be distinguished on the respective mirror, and 4-pass interferometers in which the light beam is directed towards the object four times, so that four spots can be distinguished on the mirror.
  • the mirror on the object in general does not have a perfectly flat mirror surface and/or does not extend perfectly in an intended direction.
  • the imperfect mirror may prevent carrying out such accurate measurements or can be seen as disturbances on the respective position signal, respectively.
  • a method for calibrating spot positions on a mirror of an interferometer system including at least two pairs of interferometers to provide a redundant measurement of a rotational position of an object about a rotation axis, wherein the method comprises the following steps: a. rotating the object; b. measuring a change of the rotational position of the object about the rotation axis with each of the at least two pairs of interferometers; c.
  • a lithographic apparatus comprising: an object to be positioned; an actuator system to position the object; a measurement system including an interferometer system, which interferometer system includes at least two pairs of interferometers to provide a redundant measurement of a rotational position of the object about a rotation axis; and a control system to drive the actuator system based on an output of the measurement system, wherein the control system is configured to carry out the method according to the invention.
  • a device manufacturing method wherein use is made of a lithographic apparatus according to the invention.
  • Figure 1 depicts a schematic overview of a lithographic apparatus
  • Figure 2 depicts a detailed view of a part of the lithographic apparatus of Figure 1;
  • Figure 3 schematically depicts a position control system
  • Figure 4 schematically depicts a top view of an interferometer system
  • Figure 5 schematically depict spot positions on a mirror of the interferometer system of Fig.
  • Figure 6 schematically depicts a side view of the object of Fig. 4 after rotating the object about an Y-axis;
  • Figure 7A schematically depicts a simplified top view of the interferometer system of Fig. 4 in a first rotational position about an axis parallel to the Z-axis;
  • Figure 7B schematically depicts a simplified top view of the interferometer system of Fig. 4 in a second rotational position about an axis parallel to the Z-axis.
  • 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.
  • the term “light valve” can also be used in this context.
  • examples of other such patterning devices include a programmable mirror array and a programmable FCD array.
  • FIG 1 schematically depicts a lithographic apparatus FA.
  • the lithographic apparatus FA includes an illumination system (also referred to as illuminator) IF 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)
  • 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 projection system e.g., a refractive projection lens system
  • PS configured to project a pattern imparted to the radiation beam B by patterning device MA onto a target portion C (e.g., comprising one or more dies) of the substrate W.
  • the illumination system IL receives a radiation beam from a radiation source SO, e.g. via a beam delivery system BD.
  • the illumination system IL may include various types of optical components, such as refractive, reflective, magnetic, electromagnetic, electrostatic, and/or other types of optical components, or any combination thereof, for directing, shaping, and or controlling radiation.
  • the illuminator IL may be used to condition the radiation beam B to have a desired spatial and angular intensity distribution in its cross section at a plane of the patterning device MA.
  • projection system PS used herein should be broadly interpreted as encompassing various types of projection system, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic and/or electrostatic optical systems, or any combination thereof, as appropriate for the exposure radiation being used, and or for other factors such as the use of an immersion liquid or the use of a vacuum. Any use of the term “projection lens” herein may be considered as synonymous with the more general term “projection system” PS.
  • the lithographic apparatus LA may be of a type wherein at least a portion of the substrate may be covered by a liquid having a relatively high refractive index, e.g., water, so as to fill a space between the projection system PS and the substrate W - which is also referred to as immersion lithography. More information on immersion techniques is given in US6952253, which is incorporated herein by reference.
  • the lithographic apparatus LA may also be of a type having two or more substrate supports WT (also named “dual stage”). In such “multiple stage” machine, the substrate supports WT may be used in parallel, and/or steps in preparation of a subsequent exposure of the substrate W may be carried out on the substrate W located on one of the substrate support WT while another substrate W on the other substrate support WT is being used for exposing a pattern on the other substrate W.
  • the lithographic apparatus LA may comprise a measurement stage.
  • the measurement stage is arranged to hold a sensor and or a cleaning device.
  • the sensor may be arranged to measure a property of the projection system PS or a property of the radiation beam B.
  • the measurement stage may hold multiple sensors.
  • the cleaning device may be arranged to clean part of the lithographic apparatus, for example a part of the projection system PS or a part of a system that provides the immersion liquid.
  • the measurement stage may move beneath the projection system PS when the substrate support WT is away from the projection system PS.
  • the radiation beam B is incident on the patterning device, e.g. mask, MA which is held on the mask support MT, and is patterned by the pattern (design layout) present on patterning device MA. Having traversed the 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. 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
  • the pattern (design layout) present on patterning device MA Having traversed the 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
  • the 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 PI, P2.
  • the substrate alignment marks PI, P2 as illustrated occupy dedicated target portions, they may be located in spaces between target portions.
  • Substrate alignment marks PI, 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 axes.
  • 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 invention and is used for clarification only. Instead, another coordinate system, such as a cylindrical coordinate system, may be used to clarify the invention.
  • the orientation of the Cartesian coordinate system may be different, for example, such that the z-axis has a component along the horizontal plane.
  • FIG. 2 shows a more detailed view of a part of the lithographic apparatus LA of Figure 1.
  • the lithographic apparatus LA may be provided with a base frame BF, a balance mass BM, a metrology frame MF and a vibration isolation system IS.
  • the metrology frame MF supports the projection system PS. Additionally, the metrology frame MF may support a part of the position measurement system PMS.
  • the metrology frame MF is supported by the base frame BF via the vibration isolation system IS.
  • the vibration isolation system IS is arranged to prevent or reduce vibrations from propagating from the base frame BF to the metrology frame MF.
  • the second positioner PW is arranged to accelerate the substrate support WT by providing a driving force between the substrate support WT and the balance mass BM.
  • the driving force accelerates the substrate support WT in a desired direction. Due to the conservation of momentum, the driving force is also applied to the balance mass BM with equal magnitude, but at a direction opposite to the desired direction.
  • the mass of the balance mass BM is significantly larger than the masses of the moving part of the second positioner PW and the substrate support WT.
  • the second positioner PW is supported by the balance mass BM.
  • the second positioner PW comprises a planar motor to levitate the substrate support WT above the balance mass BM.
  • the second positioner PW is supported by the base frame BF.
  • the second positioner PW comprises a linear motor and wherein the second positioner PW comprises a bearing, like a gas bearing, to levitate the substrate support WT above the base frame BF.
  • the position measurement system PMS may comprise any type of sensor that is suitable to determine a position of the substrate support WT.
  • the position measurement system PMS may comprise any type of sensor that is suitable to determine a position of the mask support MT.
  • the sensor may be an optical sensor such as an interferometer or an encoder.
  • the position measurement system PMS may comprise a combined system of an interferometer and an encoder.
  • the sensor may be another type of sensor, such as a magnetic sensor a capacitive sensor or an inductive sensor.
  • the position measurement system PMS may determine the position relative to a reference, for example the metrology frame MF or the projection system PS.
  • the position measurement system PMS may determine the position of the substrate table WT and/or the mask support MT by measuring the position or by measuring a time derivative of the position, such as velocity or acceleration.
  • the position measurement system PMS may comprise an encoder system.
  • An encoder system is known from for example, United States patent application US2007/0058173A1, filed on September 7, 2006, hereby incorporated by reference.
  • the encoder system comprises an encoder head, a grating and a sensor.
  • the encoder system may receive a primary radiation beam and a secondary radiation beam. Both the primary radiation beam as well as the secondary radiation beam originate from the same radiation beam, i.e., the original radiation beam. At least one of the primary radiation beam and the secondary radiation beam is created by diffracting the original radiation beam with the grating.
  • the encoder system optically combines the primary radiation beam and the secondary radiation beam into a combined radiation beam.
  • a sensor in the encoder head determines a phase or phase difference of the combined radiation beam.
  • the sensor generates a signal based on the phase or phase difference.
  • the signal is representative of a position of the encoder head relative to the grating.
  • One of the encoder head and the grating may be arranged on the substrate structure WT.
  • the other of the encoder head and the grating may be arranged on the metrology frame MF or the base frame BF.
  • a plurality of encoder heads is arranged on the metrology frame MF, whereas a grating is arranged on a top surface of the substrate support WT.
  • a grating is arranged on a bottom surface of the substrate support WT, and an encoder head is arranged below the substrate support WT.
  • the position measurement system PMS may comprise an interferometer system.
  • An interferometer system is known from, for example, United States patent US6,020,964, filed on July 13, 1998, hereby incorporated by reference.
  • the interferometer system may comprise a beam splitter, a mirror, a reference mirror and a sensor.
  • a beam of radiation is split by the beam splitter into a reference beam and a measurement beam.
  • the measurement beam propagates to the mirror and is reflected by the mirror back to the beam splitter.
  • the reference beam propagates to the reference mirror and is reflected by the reference mirror back to the beam splitter.
  • the measurement beam and the reference beam are combined into a combined radiation beam.
  • the combined radiation beam is incident on the sensor.
  • the sensor determines a phase or a frequency of the combined radiation beam.
  • the sensor generates a signal based on the phase or the frequency.
  • the signal is representative of a displacement of the mirror.
  • the mirror is connected to the substrate support WT.
  • the reference mirror may be connected to the metrology frame MF.
  • the measurement beam and the reference beam are combined into a combined radiation beam by an additional optical component instead of the beam splitter.
  • the first positioner PM may comprise a long-stroke module and a short-stroke module.
  • the short-stroke module is arranged to move the mask support MT relative to the long-stroke module with a high accuracy over a small range of movement.
  • the long-stroke module is arranged to move the short-stroke module relative to the projection system PS with a relatively low accuracy over a large range of movement.
  • the first positioner PM is able to move the mask support MT relative to the projection system PS with a high accuracy over a large range of movement.
  • the second positioner PW may comprise a long-stroke module and a short-stroke module.
  • the short-stroke module is arranged to move the substrate support WT relative to the long- stroke module with a high accuracy over a small range of movement.
  • the long-stroke module is arranged to move the short-stroke module relative to the projection system PS with a relatively low accuracy over a large range of movement.
  • the second positioner PW is able to move the substrate support WT relative to the projection system PS with a high accuracy over a large range of movement.
  • the first positioner PM and the second positioner PW each are provided with an actuator to move respectively the mask support MT and the substrate support WT.
  • the actuator may be a linear actuator to provide a driving force along a single axis, for example the y-axis. Multiple linear actuators may be applied to provide driving forces along multiple axis.
  • the actuator may be a planar actuator to provide a driving force along multiple axis. For example, the planar actuator may be arranged to move the substrate support WT in 6 degrees of freedom.
  • the actuator may be an electro magnetic actuator comprising at least one coil and at least one magnet. The actuator is arranged to move the at least one coil relative to the at least one magnet by applying an electrical current to the at least one coil.
  • the actuator may be a moving-magnet type actuator, which has the at least one magnet coupled to the substrate support WT respectively to the mask support MT.
  • the actuator may be a moving-coil type actuator which has the at least one coil coupled to the substrate support WT respectively to the mask support MT.
  • the actuator may be a voice-coil actuator, a reluctance actuator, a Lorentz-actuator or a piezo- actuator, or any other suitable actuator.
  • the lithographic apparatus LA comprises a position control system PCS as schematically depicted in Figure 3.
  • the position control system PCS comprises a setpoint generator SP, a feedforward controller FF and a feedback controller FB.
  • the position control system PCS provides a drive signal to the actuator ACT.
  • the actuator ACT may be the actuator of the first positioner PM or the second positioner PW.
  • the actuator ACT drives the plant P, which may comprise the substrate support WT or the mask support MT.
  • An output of the plant P is a position quantity such as position or velocity or acceleration.
  • the position quantity is measured with the position measurement system PMS.
  • the position measurement system PMS generates a signal, which is a position signal representative of the position quantity of the plant P.
  • the setpoint generator SP generates a signal, which is a reference signal representative of a desired position quantity of the plant P.
  • the reference signal represents a desired trajectory of the substrate support WT.
  • a difference between the reference signal and the position signal forms an input for the feedback controller FB.
  • the feedback controller FB Based on the input, the feedback controller FB provides at least part of the drive signal for the actuator ACT.
  • the reference signal may form an input for the feedforward controller FF.
  • the feedforward controller FF provides at least part of the drive signal for the actuator ACT.
  • the feedforward FF may make use of information about dynamical characteristics of the plant P, such as mass, stiffness, resonance modes and eigenfrequencies.
  • FIG. 4 schematically depicts a practical embodiment of an interferometer system, e.g. as part of the position measurement system PMS, configured to measure a position of an object OB, wherein the object OB may for instance be the substrate support WT or the mask support MT.
  • the interferometer system comprises a plurality of pairs of interferometers of which three pairs of interferometers are visible in the top view of Fig. 4. Only these three pairs of interferometers will be used throughout the description, but it will be apparent that other interferometers may be provided as well even though they are omitted from the drawings for clarity purposes.
  • a first pair of interferometers comprises a first interferometer IF1 and a second interferometer IF2.
  • the first interferometer IF1 is arranged to provide a first position signal PS1 representative of a position of the object OB in an X-direction by directing a first measurement beam MB1 on a first mirror FM.
  • the second interferometer IF2 is arranged to provide a second position signal PS2 representative of a position of the object OB in the X-direction by directing a second measurement beam MB2 on the first mirror FM.
  • a second pair of interferometers comprises a third interferometer IF3 and a fourth interferometer IF4.
  • the third interferometer IF3 is arranged to provide a third position signal PS3 representative of a position of the object OB in a Y-direction by directing a third measurement beam MB3 on a second mirror SM.
  • the fourth interferometer IF4 is arranged to provide a fourth position signal PS4 representative of a position of the object OB in the Y-direction by directing a fourth measurement beam MB4 on the second mirror SM.
  • a third pair of interferometers comprises a fifth interferometer IF5 and a sixth interferometer IF6.
  • the fifth interferometer IF5 is arranged to provide a fifth position signal PS5 representative of a position of the object OB in the X-direction by directing a fifth measurement beam MB5 on a third mirror TM.
  • the sixth interferometer IF6 is arranged to provide a sixth position signal PS6 representative of a position of the object OB in the X-direction by directing a sixth measurement beam MB6 on the third mirror TM.
  • the first mirror FM and the third mirror TM are arranged on opposite sides of the object OB and mainly extend in a Y-direction.
  • the second mirror SM is arranged at a side of the object OB mainly extending in the X-direction.
  • the interferometer system may include an interferometer arranged to provide a position signal representative of a position of the object OB in a Z-direction, which Z-direction is perpendicular to both the X- and Y-directions and thus perpendicular to the plane of drawing in Fig. 4, by directing a measurement beam on a mirror.
  • the interferometers may be single-pass interferometers in which the respective measurement beam is directed only once to the corresponding mirror, reflected back to interfere with a reference beam.
  • one or more, but preferably all interferometers may be multi-pass interferometers in which the respective measurement beam is directed more than once to the corresponding mirror.
  • An example for one mirror is schematically indicated in Fig. 5.
  • Fig. 5 schematically depicts the third mirror TM, but the same may apply mutatis mutandis to the first and/or second mirror FM, SM.
  • the fifth measurement beam MB5 is directed by the fifth interferometer IF5 for a first time towards the third mirror TM to be reflected off the third mirror TM at a spot position SP5a back towards the fifth interferometer IF5.
  • the fifth interferometer IF5 is configured to direct the fifth measurement beam MB5 a second time towards the third mirror TM to be reflected off the third mirror TM at a spot position SP5b back towards the fifth interferometer IF5.
  • the sixth measurement beam MB6 is directed by the sixth interferometer IF6 for a first time towards the third mirror TM to be reflected off the third mirror TM at a spot position SP6a back towards the sixth interferometer IF6.
  • the sixth interferometer IF6 is configured to direct the sixth measurement beam MB6 a second time towards the third mirror TM to be reflected off the third mirror TM at a spot position SP6b back towards the sixth interferometer IF6.
  • the spot position SP5a only has a spot position error in the Y-direction while the spot position SP5b has a spot position error in both the Y- and Z- directions. Further, the spot position SP6a only has a spot position error in the Z-direction while the spot position SP6b has a spot position error in both the Y- and Z-directions.
  • Each of the beam portions directed to and reflected off the third mirror TM has a contribution to the position signal of the corresponding interferometer. However, as only the total contribution is determined in the interferometer it is not possible to determine which part can be contributed to which beam portion. The same applies to the spot position errors.
  • Each spot position error has a contribution to the total error, but it may not be possible to attribute a portion of the error to a specific spot position error.
  • a multi-pass interferometer can be simplified by a single beam with an average spot position, which average spot position is the geometrical center of the spot positions. With the exception of Fig. 5, this simplified depiction is used in Fig. 1, 4, 6, 7 A and 7B. In Fig.
  • an intended spot center IC5 and IC6 which are the average spot positions of the dashed spot positions, respectively, and an actual spot center AC5 and AC6, which are the average spot positions of the solid spot positions, respectively.
  • the intended spot centers IC5 and IC6 are at the same level in the Z- direction.
  • the simplified depictions of the multi-pass interferometers here in fact relate to multi-beam reflections of the mirrors per interferometer, it also illustrates that the principle of the invention can be easily applied to a single -pass interferometer system as well.
  • the first, second and third pairs of interferometers are all able to measure an orientation of the object OB about a rotation axis parallel to a Z-direction perpendicular to the X- and Y-directions, here referred to as Rz.
  • Rz rotation axis parallel to a Z-direction perpendicular to the X- and Y-directions
  • Fig. 6 depicts a side view of the object OB in accordance with a Z-X plane.
  • the measurement beams are depicted as single beams incident to a respective mirror at the actual spot center of the spot positions of the respective interferometer on the object OB.
  • the actual spot center AC5 is at a higher level in Z-direction than the actual spot center AC6, which is reflected in Fig. 6 as the fifth measurement beam MB5 being above the sixth measurement beam MB6.
  • the first measurement beam MB1 is above the second measurement beam MB2
  • the third measurement beam MB3 is above the fourth measurement MB4.
  • the object OB is rotated, in this example about an axis parallel to the Y-direction that is perpendicular to the plane of the drawing and thus perpendicular to both the X- and Y-direction.
  • This rotational direction will be referred to as Ry.
  • the first, second and third mirror FM, SM, TM will be considered to be perfectly flat and aligned mirrors unless indicated otherwise.
  • the Rz measurement of the first and second pairs of interferometers may be affected by the rotation, but only when the corresponding actual spot centers are not at the same level in Z-direction as shown in Fig. 6. Due to the different levels of the measurement beams MB1, MB5 compared to measurement beams MB2, MB6, respectively, the optical path length difference caused by the rotation of the first and third mirrors FM, TM is different. As a result, the position signals PS1, PS2 will change differently and thus result in a change in the Rz measurement although the object OB has not rotated about an axis extending in Z-direction.
  • the change in Rz measurement provides information about a distance between the actual spot centers in Z- direction. Hence, in case the actual spot centers are at the same level in Z-direction, the Rz measurement should not have changed.
  • Fig. 7A depicts a simplified top view of the interferometer system of Fig. 4 and indicates the object OB and all measurement beams MB1-MB6.
  • all pairs of interferometers are able to provide an Rz measurement due to a distance between actual spot centers in Y-direction for the first and third pair of interferometers and due to a distance between actual spot centers in X-direction for the second pair of interferometers.
  • Fig. 7B depicts the top view of Fig. 7A after rotating the object OB about an axis extending in a Z-direction.
  • the Rz measurements of all pairs of interferometers will change due to the rotation, but depending on the actual distance between the respective actual spot centers which may be different from the distance between the intended spot centers.
  • the change of the Rz measurements due to the rotation provides information about the distance between the actual spot centers. It is possible to determine a difference between the actual change of the Rz measurement and the expected change of the Rz measurement, but it is also possible to only use the Rz measurements itself to determine a reference Rz and determine a difference between the actual change of the Rz measurement and the change of the reference Rz.
  • Rz i. Rz measurement provided by the first pair of interferometers; ii. Rz measurement provided by the second pair of interferometers; iii. Rz measurement provided by the third pair of interferometers; iv. An average of the Rz measurement provided by the first pair of interferometers and the Rz measurement provided by the second pair of interferometers; v. An average of the Rz measurement provided by the first pair of interferometers and the Rz measurement provided by the third pair of interferometers; vi. An average of the Rz measurement provided by the second pair of interferometers and the
  • Rz measurement provided by the third pair of interferometers An average of the Rz measurement provided by the first pair of interferometers, the Rz measurement provided by the second pair of interferometers, and the Rz measurement provided by the third pair of interferometers.
  • a deviation in the change of the rotational position measured by one of the at least two pairs of interferometers is determined compared to the change of the rotational position measured by another one of the at least two pairs of interferometers (options L, ii. and iii.) or compared to an average change of the rotational position measured by two or more pairs of interferometers (options iv. to vii.) to obtain information about the distance between the actual spot centers in X- or Y-direction.
  • the orientation of the object OB after rotating the object OB about Ry and indicated using solid lines may be referred to as a first rotated orientation, while the object OB may also have a neutral orientation indicated by dashed lines in Fig. 6.
  • the neutral orientation in this example corresponds to an alignment with the X-, Y- and Z-direction, which is usually determined by a support structure delimiting the movement of the object in X-, Y- and Z- directions.
  • the method was carried out by rotating the object OB from the neutral orientation to the first rotated orientation. It is possible to repeat the method for a second rotated orientation different from the first rotated orientation and different from the neutral orientation.
  • the second rotated orientation may be obtained by rotating the object OB in the opposite direction starting from the neutral orientation compared to the required rotation when rotating from the neutral orientation to the first rotated orientation.
  • the first rotated orientation and the second rotated orientation may be arranged at opposite sides of the neutral orientation.
  • the orientation of the object OB after rotating the object OB about Rz is indicated in Fig. 7B and may be referred to as a first rotated orientation, while the object OB may also have a neutral orientation as indicated in Fig. 7A.
  • the neutral orientation in this example also corresponds to an alignment with the X-, Y- and Z-direction, which is usually determined by a support structure delimiting the movement of the object in X-, Y- and Z-directions.
  • the method was carried out by rotating the object OB from the neutral orientation to the first rotated orientation. It is possible to repeat the method for a second rotated orientation different from the first rotated orientation and different from the neutral orientation.
  • the second rotated orientation may be obtained by rotating the object OB in opposite direction starting from the neutral orientation compared to the required rotation when rotating from the neutral orientation to the first rotated orientation.
  • the first rotated orientation and the second rotated orientation may be arranged at opposite sides of the neutral orientation
  • the above examples have been described while assuming the mirrors to be perfect, which in practice is probably not the case.
  • the method according to the invention may be combined with a method to at least partially calibrate a mirror of an interferometer.
  • rotation of the object OB as indicated will move all measurement beams MB1 to MB6 over the respective mirrors FM, SM, TM. It is possible to adjust the method to translate the object in X- and /or Y-direction to allow at least one pair of measurement beams, possibly two pairs of measurement beams to be substantially at the same location on the mirror as was the case in the neutral orientation of the object OB. Additionally, the method may be repeated for the same rotation, but with another pair of measurement beams or with another combination of pairs of measurement beams being substantially held at the same location on the mirror.
  • Such additional measurements may allow to distinguish deviations caused by spot position deviations from deviations caused by an imperfect mirror and spot movements over the mirror.
  • the examples depict the use of three pairs of interferometers the invention can also be used with only two pairs of interferometers.
  • the example of Fig. 6 can also be used when one of the first or third pair of interferometers is omitted.
  • the example of Fig. 7 can also be used when any one of the pairs of interferometers is omitted.
  • the examples mainly talk about multi-pass interferometers and actual spot centers being the average of the spot positions, the invention may also be applied using single-pass interferometers in which case the actual spot centers coincide with the spot position and are no longer an average position. However, the same principles still apply.
  • Embodiments of the invention may form part of a mask inspection apparatus, a metrology apparatus, or any apparatus that measures or processes an object such as a wafer (or other substrate) or mask (or other patterning device). 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 invention may be implemented in hardware, firmware, software, or any combination thereof. Embodiments of the invention 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 method for calibrating spot positions on a mirror of an interferometer system including at least two pairs of interferometers to provide a redundant measurement of a rotational position of an object about a rotation axis, wherein the method comprises the following steps: a. rotating the object; b.
  • step a. the object is rotated about the rotation axis.
  • the at least two pairs of interferometers include a first pair of interferometers configured to measure a position of the object in a first direction perpendicular to the axis, and a second pair of interferometers configured to measure a position of the object in a second direction perpendicular to the axis and the first direction, wherein in step a. the object is rotated about an axis parallel to the first direction, wherein step c. includes determining a deviation in the change of the rotational position measured by the second pair of interferometers compared to the change of the rotational position measured by the first pair of interferometers, and wherein in step d. information is obtained about the spot positions on the mirror of the second pair of interferometers.
  • step a the object is rotated from a neutral orientation to a first rotated orientation, and wherein the steps b. to d. are repeated after rotating the object to a second rotated orientation, wherein the first rotated orientation and the second rotated orientation are arranged at opposite sides of the neutral orientation.
  • step d. the information obtained provides information about the spot positions on the mirror in a direction perpendicular to the rotation axis.
  • step d. the information obtained provides information about the spot positions on the mirror in a direction parallel to the rotation axis.
  • a lithographic apparatus comprising: an object to be positioned; an actuator system to position the object; a measurement system including an interferometer system, which interferometer system includes at least two pairs of interferometers to provide a redundant measurement of a rotational position of the object about a rotation axis; and - a control system to drive the actuator system based on an output of the measurement system, wherein the control system is configured to carry out the method according to any of the clauses 1-8.
  • the lithographic apparatus further comprising: an illumination system configured to condition a radiation beam; a support constructed to support a patterning device, the patterning device being capable of imparting the radiation with a pattern in its cross-section to form a patterned radiation beam; a substrate table constructed to hold a substrate; and a projection system configured to project the patterned radiation beam onto a target portion of the substrate, wherein the object is the support or the substrate table.
  • an illumination system configured to condition a radiation beam
  • a support constructed to support a patterning device, the patterning device being capable of imparting the radiation with a pattern in its cross-section to form a patterned radiation beam
  • a substrate table constructed to hold a substrate
  • a projection system configured to project the patterned radiation beam onto a target portion of the substrate, wherein the object is the support or the substrate table.

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Exposure And Positioning Against Photoresist Photosensitive Materials (AREA)
  • Instruments For Measurement Of Length By Optical Means (AREA)

Abstract

L'invention concerne un procédé d'étalonnage de positions de points sur un miroir d'un système d'interférométrie comprenant au moins deux paires d'interféromètres pour fournir une mesure redondante de la position angulaire d'un objet autour d'un axe de rotation, le procédé comprenant les étapes suivantes consistant à : a. faire tourner l'objet ; b. mesurer un changement de position angulaire de l'objet autour de l'axe de rotation avec chaque interféromètre desdites paires d'interféromètres ; c. déterminer un écart de changement de position angulaire mesuré par un interféromètre desdites paires d'interféromètres par rapport au changement de position angulaire mesuré par un autre interféromètre desdites paires d'interféromètres ou par rapport à un changement moyen de position angulaire mesuré par au moins deux paires d'interféromètres ; et obtenir des informations concernant des positions de points sur le miroir dudit interféromètre desdites paires d'interféromètres sur la base de l'écart déterminé.
PCT/EP2021/080019 2020-11-26 2021-10-28 Procédé d'étalonnage de positions de points de miroir, appareil lithographique et procédé de fabrication de dispositif WO2022111940A1 (fr)

Priority Applications (2)

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KR1020237017428A KR20230109640A (ko) 2020-11-26 2021-10-28 미러 스폿 위치 교정 방법, 리소그래피 장치, 및 디바이스 제조 방법
CN202180078767.4A CN116472436A (zh) 2020-11-26 2021-10-28 镜斑位置校准方法、光刻设备和器件制造方法

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CN117806026A (zh) * 2024-02-28 2024-04-02 安徽瑞控信光电技术股份有限公司 高精度光束切换装置及快反镜

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US6020964A (en) 1997-12-02 2000-02-01 Asm Lithography B.V. Interferometer system and lithograph apparatus including an interferometer system
WO2005047974A2 (fr) * 2003-11-10 2005-05-26 Zygo Corporation Mesure et compensation d'erreurs dans des interferometres
US6952253B2 (en) 2002-11-12 2005-10-04 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
US20070058173A1 (en) 2005-09-12 2007-03-15 Wolfgang Holzapfel Position-measuring device
WO2019080888A1 (fr) * 2017-10-26 2019-05-02 清华大学 Procédé d'étalonnage d'écart d'installation destiné à un interféromètre dans un système de mesure de déplacement laser à axes multiples

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Publication number Priority date Publication date Assignee Title
US6020964A (en) 1997-12-02 2000-02-01 Asm Lithography B.V. Interferometer system and lithograph apparatus including an interferometer system
US6952253B2 (en) 2002-11-12 2005-10-04 Asml Netherlands B.V. Lithographic apparatus and device manufacturing method
WO2005047974A2 (fr) * 2003-11-10 2005-05-26 Zygo Corporation Mesure et compensation d'erreurs dans des interferometres
US20070058173A1 (en) 2005-09-12 2007-03-15 Wolfgang Holzapfel Position-measuring device
WO2019080888A1 (fr) * 2017-10-26 2019-05-02 清华大学 Procédé d'étalonnage d'écart d'installation destiné à un interféromètre dans un système de mesure de déplacement laser à axes multiples

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117806026A (zh) * 2024-02-28 2024-04-02 安徽瑞控信光电技术股份有限公司 高精度光束切换装置及快反镜
CN117806026B (zh) * 2024-02-28 2024-05-03 安徽瑞控信光电技术股份有限公司 高精度光束切换装置及快反镜

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