Damper, damping method, and apparatus including damper

Abstract

This disclosure provides a damper for an object table. The damper comprises a pair of plates (22, 24) arranged to define a volume (30) between them, a plurality of support columns (26) arranged in the volume and extending between the pair of plates, and an elastomer portion (32) surrounding the support columns and extending between the plates. The support columns may be uniformly distributed in the volume. The damper may be configured to function as an interface between a magnet assembly and an actuator frame.

Description

[Technical Field]

[0001] Cross-reference of related applications This application claims priority to European Application No. 23175545.5, filed on 26 May 2023, which is incorporated herein by reference in its entirety.

[0002] The present invention relates to a damper, a damping method, and a device equipped with the damper. The damper may be intended for damping short distances and high acceleration. It may be applied, for example, to the support of a moving object such as a wafer stage in a lithography apparatus. [Background technology]

[0003] A lithography apparatus is a machine built to form a desired pattern on a substrate. Lithography apparatus is used, for example, in the manufacture of integrated circuits (ICs). A lithography apparatus projects, for example, the pattern (also called a "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).

[0004] As semiconductor manufacturing processes continue to advance, the dimensions of circuit elements continue to shrink, while the number of functional elements per device, such as transistors, has steadily increased over decades—a trend commonly known as Moore's Law. To keep pace with Moore's Law, the semiconductor industry is pursuing technologies to create increasingly smaller features. Lithography equipment sometimes utilizes electromagnetic radiation to project patterns onto substrates. The wavelength of this radiation determines the minimum size of features patterned on the substrate. Commonly used wavelengths today are 365 nm (i-line), 248 nm, 193 nm, and 13.5 nm. Lithography equipment utilizing extreme ultraviolet (EUV) radiation with wavelengths in the 4 nm to 20 nm range, for example, 6.7 nm or 13.5 nm, can be used to create smaller features on a substrate than lithography equipment utilizing radiation with a wavelength of, for example, 193 nm.

[0005] This lithography system has multiple moving parts. For example, the wafer stage, a relatively heavy component that supports the substrate, is moved over short distances and at relatively high speeds between different positions on the substrate. This makes it possible to irradiate the same pattern onto multiple locations on the substrate (typically arranged in a grid).

[0006] To improve substrate throughput in lithography equipment, it is necessary to increase the speed and acceleration of the substrate table. However, beyond certain speeds and accelerations, the substrate table and its connected components begin to exhibit undesirable effects such as deflection, warping, heat generation, and vibration. To mitigate these effects, dampers can be applied to the actuator design. Furthermore, it is possible to significantly increase the servo bandwidth. Designing these dampers requires relatively complex balancing, such as improving servo bandwidth, feedforward model error, substrate table internal deformation error, and reliability.

[0007] US20190294057 discloses a stage system for positioning an object. The stage system comprises an object table configured to support an object to be positioned, and a positioning system configured to position the object table. The positioning system comprises an actuator for positioning the object table in the operating direction. The actuator comprises a magnet assembly and a coil assembly, the magnet assembly comprising a first magnetic material and a second magnetic material. The magnet assembly may comprise a damper positioned between the first magnetic material and the second magnetic material and connected thereto. Optionally, the damper comprises a viscoelastic material, such as natural rubber or synthetic rubber.

[0008] US20160238953 discloses a system in which actuator forces are applied to a base frame via an interface mass. The interface mass is attached to the base frame via a damping member (i.e., a compressible or flexible connector, e.g., a spring or rubber or rubber-like component). Applying the force via the interface mass provides filtering of the applied force.

[0009] The drawbacks of conventional dampers are related, for example, to the inherent mass of the damper itself. A damper requires a frame surrounding actuator components such as magnets and shielding iron. This can add about 1 kg of mass to the actuator system. As a result, for example, up to approximately 50 m / s 2 Performance is limited to accelerations up to a certain point. At such accelerations, the stress on the damper becomes very high, so stringent requirements are imposed on the damper manufacturing process to meet the specifications.

[0010] This disclosure aims to provide an improved damper system. [Overview of the project]

[0011] This disclosure provides a damper for an object table. The damper comprises a pair of plates arranged to define a volume between them, a plurality of supports arranged in the volume and extending between the pair of plates, and an elastomer portion surrounding the supports and extending between the plates.

[0012] In one embodiment, the support columns are uniformly distributed throughout the volume.

[0013] The damper may be configured to function as an interface between the magnet assembly and the actuator frame.

[0014] In one embodiment, the support column is made of a non-magnetic metal, such as titanium.

[0015] The support posts may have a length of approximately 1 to 10 mm and / or a diameter of approximately 0.1 to 0.5 mm.

[0016] The elastomer portion may include an elastomer. In one embodiment, the elastomer portion has a laminated structure.

[0017] In another embodiment, the present disclosure provides an object table for a lithography apparatus. The object table comprises at least a base and a short-stroke module movable relative to the base. The short-stroke module is provided with one or more magnetic actuators positioned on each side of the short-stroke module and at least one damper as described in claim 1, positioned between the one or more magnetic actuators and the short-stroke module.

[0018] In further other embodiments, the present disclosure provides a lithography apparatus comprising at least one object table as described in claim 8 and / or at least one damper as described in claim 1.

[0019] In one embodiment, the present disclosure provides a measuring tool for a lithography process comprising at least one object table as described in claim 8 and / or at least one damper as described in claim 1.

[0020] In further other embodiments, the present disclosure provides a method for damping the movement of a module. The method comprises the steps of providing an apparatus comprising at least one movable module, the module being provided with at least one actuator, and connecting at least one damper between the at least one actuator and the module. The damper comprises at least a pair of plates defining a volume between them, a plurality of supports arranged in the volume and extending between the pair of plates, and an elastomer portion surrounding the supports and extending between the plates. The method further comprises the step of moving the module using at least one actuator.

[0021] In one embodiment, the struts are uniformly distributed in volume.

[0022] In one embodiment, the step of connecting at least one damper between the module and the actuator comprises connecting the damper as an interface between the magnet assembly and the frame of the actuator.

[0023] In one embodiment, the step of moving the module accelerates the module at an acceleration exceeding 60 m / s 2 for example, 90 m / s 2 for example, 100 m / s 2 at an acceleration exceeding that, for example.

[0024] In one embodiment, the method comprises 3D printing the struts and a pair of plates integrally with the struts and the plates, filling the volume between the plates with an elastomer, and curing the elastomer.

Brief Description of the Drawings

[0025] [Figure 1] A schematic view of a lithographic apparatus is shown. [Figure 2] A schematic side view of an object table comprising a long stroke module and a short stroke module is shown. [Figure 3] A perspective view of an object table is shown. [Figure 4A] A perspective view of a magnet assembly including an embodiment of a damper according to the present disclosure is shown. [Figure 4B] A perspective view of a magnet assembly including an embodiment of a damper according to the present disclosure is shown. [Figure 4C] A partial cross-sectional view of the magnet assembly is shown. [Figure 5] A perspective view of an embodiment of a damper according to the present disclosure is shown. [Figure 6] A perspective view of a plate provided with a plurality of struts suitable for the damper of FIG. 5 is shown. [Figure 7] Figure 5 shows a perspective view of the elastomer used for the damper. [Figure 8] The simulation results for the behavior of short-stroke modules with and without dampers are shown. [Modes for carrying out the invention]

[0026] In this specification, the terms “radiation” and “beam” are used to encompass all types of electromagnetic radiation, including ultraviolet radiation (e.g., having wavelengths of 365 nm, 248 nm, 193 nm, 157 nm, or 126 nm) and EUV (extreme ultraviolet radiation, e.g., having wavelengths in the range of approximately 5 to 100 nm).

[0027] As used in this document, the terms “reticle,” “mask,” or “patterning device” can be broadly interpreted to refer to a general-purpose patterning device that can be used to impart a patterned cross-section to an incident radiation beam, corresponding to a pattern formed on a target portion of a substrate. The term “light bulb” may also be used in this context. In addition to conventional masks (transmissive, reflective, binary, phase-shifted, hybrid, etc.), other examples of patterning devices include programmable mirror arrays and programmable liquid crystal arrays.

[0028] As used herein, the term “damper” refers to a device for reducing mechanical vibration, in particular a shock absorber.

[0029] As used herein, the term "long stroke" refers to a portion of a lithography apparatus, such as a substrate table, that can move a relatively large distance relative to the apparatus. This relatively large distance may range from one meter to several meters.

[0030] As used herein, the term "short stroke" refers to a portion of a device, such as a substrate table, that can move a relatively short distance (typically ranging from one millimeter to several millimeters) relative to the long stroke portion. While the positioning accuracy of the long stroke is usually optimized, the short stroke portion enables significantly higher positioning accuracy. This high positioning accuracy may typically be in the nanometer range, i.e., within one nm of the target position.

[0031] Figure 1 schematically shows a lithography apparatus LA. The lithography apparatus LA includes an illumination system (also called an illuminator) IL configured to adjust a radiation beam B (e.g., UV radiation, DUV radiation, or EUV radiation); a mask support (e.g., a mask table) MT connected to a first positioning device PM constructed to support a patterning device (e.g., a mask) MA and configured to precisely position the patterning device MA according to specific parameters; a substrate support (e.g., a wafer table) WT connected to a second positioning device PW constructed to hold a substrate (e.g., a resist-coated wafer) W and configured to precisely position the substrate support according to specific parameters; and a projection system (e.g., a refractive projection lens system) PS configured to project the pattern applied to the radiation beam B by the patterning device MA onto a target portion C of the substrate W (e.g., including one or more dies).

[0032] During operation, the illumination system IL receives the radiated beam from the radiation source SO, for example, via the beam transport system BD. The illumination system IL may include various types of optical components, including refractive, reflective, magnetic, electromagnetic, electrostatic, and / or other types of optical components, or any combination thereof, for directing, shaping, and / or controlling the radiation. The illuminator IL may be used to tune the radiated beam B so that it has a desired spatial and angular intensity distribution in a cross-section in the plane of the patterning device MA.

[0033] As used herein, the term “projection system” PS should be interpreted as broadly encompassing various types of projection systems, including refractive, reflective, catadioptric, anamorphic, magnetic, electromagnetic, and / or electrostatic optical systems, or any combination thereof, depending on the exposure radiation used and / or other factors such as the use of immersion liquid or vacuum. The use of the term “projection lens” herein can be considered synonymous with the more general term “projection system” PS.

[0034] As shown in Figure 1, the lithography apparatus is transmissive (for example, employing a transmissive mask). Alternatively, the lithography apparatus may be reflective (for example, employing the aforementioned type of programmable mirror array or reflective mask).

[0035] The lithography apparatus LA may be of a type that can coat at least a portion of the substrate with a liquid having a relatively high refractive index (e.g., water) to fill the space between the substrate W and the projection system PS, and this is also called immersion lithography. Details relating to immersion technology are described in U.S. Patent No. 6,952,253, which is incorporated herein by reference.

[0036] The lithography apparatus LA may be of a type having two or more substrate supports WT (also called a "dual-stage" apparatus). In such a "multi-stage" apparatus, the substrate supports WT may be used in parallel, and / or, while a pattern is being exposed on a substrate W on one substrate support WT, preparation steps for exposure to the next substrate W may be performed on a substrate W placed on the other substrate support WT.

[0037] In addition to the substrate support WT, the lithography apparatus LA may include a measurement stage. The measurement stage is configured to hold sensors and / or a cleaning device. The sensors may be configured to measure the characteristics of the projection system PS or the characteristics of the radiation beam B. The measurement stage may hold multiple sensors. The cleaning device may be configured to clean a part of the lithography apparatus, such as a part of the projection system PS or a part of the system that supplies the immersion fluid. The measurement stage may move below the projection system PS when the substrate support WT is away from the projection system PS.

[0038] During operation, the radiating beam B is incident on a patterning device (e.g., mask MA) held by a mask support MT, and is patterned by a pattern (design layout) present on the patterning device MA. After passing through the mask MA, the radiating beam B passes through a projection system PS, where it is focused onto a target portion C of the substrate W. Using a second positioning device PW and a position measurement system IF, the substrate support WT may be precisely moved so that, for example, various target portions C are positioned on the path of the radiating beam B and are focused and aligned. Similarly, a first positioning device PM and another position sensor (not shown in Figure 1) may be used to precisely position the patterning device MA relative to the path of the radiating beam B. The patterning device MA and the substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. In the illustration, the substrate alignment marks P1, P2 occupy dedicated target portions, but they may be placed in the spaces between target portions. When substrate alignment marks P1 and P2 are positioned between target portions C, they are known as scribe lane alignment marks.

[0039] To clarify the invention, a Cartesian coordinate system is used. The Cartesian coordinate system has three axes: the x-axis, y-axis, and z-axis. Each of the three axes is perpendicular to the other two axes. A rotation around the x-axis is called an Rx rotation. A rotation around the y-axis is called a Ry rotation. A rotation around the z-axis is called an Rz rotation. The x-axis and y-axis define the horizontal plane, and the z-axis is vertical. This Cartesian coordinate system is not limiting to the invention and is used only for explanatory purposes. Alternatively, the invention could be described using another coordinate system, such as a cylindrical coordinate system. The orientation of the Cartesian coordinate system may differ; for example, the z-axis may be defined so that it has a component along the horizontal plane.

[0040] Referring to Figure 1, the illuminator IL receives the radiation beam from the radiation source SO. The radiation source and the lithography apparatus may be separate, for example, when the radiation source is an excimer laser. In such cases, the radiation source is not considered part of the lithography apparatus, and the radiation beam is guided from the radiation source SO to the illuminator IL via a beam transport system BD, which may include, for example, appropriate light guide mirrors and beam expanders. In other cases, for example, when the radiation source is a mercury lamp, the radiation source may be integrated with the lithography apparatus. The radiation source SO and the illuminator IL, together with the beam transport system BD as needed, may be referred to as a radiation system.

[0041] The illuminator IL may include an adjuster AD configured to adjust the angular intensity distribution of the radiated beam. Generally, at least the outer and / or inner radial ranges of the intensity distribution at the pupil plane of the illuminator (usually called σ-outer and σ-inner, respectively) are adjustable. Furthermore, the illuminator IL may include various other components such as an integrator IN and a capacitor CO. The illuminator may be used to adjust the radiated beam and obtain desired uniformity and intensity distribution in its cross-section.

[0042] The radiant beam B is incident on a patterning device (e.g., mask MA) held in a mask support structure (e.g., mask table MT), and is patterned by the patterning device. After passing through mask MA, the radiant beam B passes through a projection system PS, where it is focused onto a target portion C of the substrate W. Using a second positioning device PW and a position sensor IF (e.g., an interferometer, linear encoder, or capacitive sensor), the substrate table WT may be precisely moved to position, for example, various target portions C along the path of the radiant beam B. Similarly, a first positioning device PM and another position sensor (not shown in Figure 1) may be used to precisely position mask MA relative to the path of the radiant beam B, for example, after mechanical retrieval from a mask library or during scanning.

[0043] Optionally, the substrate table WT is equipped with a position measurement system PMS. The position measurement system measures the position of the substrate table relative to a reference point. The position measurement system may be an encoder type or an interferometer type. For details on interferometers and their use in position measurement, see, for example, US2021072088.

[0044] Figure 2 schematically shows a system 1 comprising an object table 2. The object table may be placed on a base 4 and is usually movable relative to the base. The object table 2 may include a long-stroke section 6 and a short-stroke section 8. The object table may be a mask table MT or a substrate table WT. Movement of the object table 2 relative to the base 4 may be achieved using the long-stroke module for relatively coarse positioning and the short-stroke module 8 for fine positioning. Coarse positioning here may relate to movement over a distance of 1 meter or more. The lower limit of the positioning accuracy of the long-stroke module may typically be limited to, for example, an accuracy on the order of micrometers (μm). Fine positioning relates to positioning with the highest possible accuracy, for example, on the order of nanometers (nm), for example, an accuracy of about 1 nm.

[0045] Referring to Figure 1, with respect to the mask table MT, the short-stroke module 8 and the long-stroke module 6 may be part of the first positioning device PM. The movement of the substrate table WT or "substrate support" may be achieved using separate long-stroke and short-stroke modules, which may constitute part of the second positioning device PW. If the lithography apparatus LA is a stepper, (in contrast to the scanner) the mask table MT may be connected only to the short-stroke actuator, or it may be fixed.

[0046] The mask MA and the substrate W may be aligned using mask alignment marks M1, M2 and substrate alignment marks P1, P2. In the illustration, the substrate alignment marks occupy dedicated target areas, but they may also be placed in the spaces between target areas (these are known as scribelane alignment marks). Similarly, if multiple dies are placed on the mask MA, the mask alignment marks may be placed between the dies.

[0047] The lithography apparatus may be used in at least one of the following modes:

[0048] 1. In step mode, with the mask table MT (or "mask support") and substrate table WT (or "substrate support") substantially stationary, the entire pattern applied to the radiation beam is projected onto the target portion C at once (i.e., a single stationary exposure). Subsequently, the substrate table WT (or "substrate support") is moved in the X and / or Y directions to allow exposure of another target portion C. In step mode, the maximum size of the exposure area limits the size of the target portion C that can be imaged in a single stationary exposure.

[0049] 2. In scan mode, the pattern applied to the radiation beam is projected onto the target portion C while the mask table MT (or "mask support") and the substrate table WT (or "substrate support") are scanned synchronously (i.e., single dynamic exposure). The speed and direction of the substrate table WT (or "substrate support") relative to the mask table MT (or "mask support") may be determined by the scaling (or reduction) and image inversion characteristics of the projection system PS. In scan mode, the width of the target portion (non-scan direction) in a single dynamic exposure is limited by the maximum size of the exposure area, while the height of the target portion (scan direction) is determined by the length of the scan movement.

[0050] 3. In another mode, the mask table MT (or “mask support”) is held in a substantially stationary state, holding the programmable patterning device, while the substrate table WT (or “substrate support”) moves or scans, projecting the pattern applied to the radiation beam onto the target portion C. In this mode, a pulsed radiation source is typically used, and the programmable patterning device is updated as needed each time the substrate table WT (or “substrate support”) moves, or between consecutive radiation pulses during scanning. This mode of operation is readily applicable to maskless lithography utilizing programmable patterning devices such as programmable mirror arrays of the type described above.

[0051] Combinations and / or variations of the above-described modes of use may be employed, or entirely different modes of use may be employed.

[0052] Figures 2 and 3 show a system 1 comprising an object table 2 and a base 4. An object 3 (e.g., a substrate W, a wafer, or a mask) may be placed on the object table 2. Optionally, the object table 2 may include optical elements such as a mirror block.

[0053] System 1 may be configured to position an object such as a substrate W relative to a reference. Base 4 is not mandatory. Base 4 may be stationary and can be considered a fixed reference. Alternatively, Base 4 may be movable relative to another fixed reference (e.g., a balance mass).

[0054] System 1 may include a positioning system configured to position an object table 2. The positioning system is configured, for example, to position the object table 2 in a two-dimensional plane referred to as the xy-plane. The positioning system may be configured to position the object table 2 with six degrees of freedom. System 1 may be included in a lithography apparatus LA.

[0055] Base 4 may typically include a long-stroke positioning device for moving the long-stroke module 6 of the object table. The positioning system may also include a short-stroke system. The short-stroke system of the positioning system may include an encoder base included in this module. The encoder translates the positioning command. In practical embodiments, the encoder essentially extends across the entire volume of the short-stroke module. One or more actuators 10 are located on each side of the short-stroke module 8. The short-stroke module 8 may, for example, have at least one actuator 10 on each side of the module. Each actuator 10 may be able to move the module 8 in at least one direction. For example, each actuator 10 may be able to move the module 8 in a linear direction indicated by arrow 15. This linear direction may be perpendicular to the side of the short-stroke module or oriented along the side of the module.

[0056] In the example shown in Figure 3, the short-stroke module 8 is provided with four actuators 10. Two actuators located on opposite sides of the module 8 are configured to position the module 8 in the x-direction relative to the base 4. The other two actuators 10 located on opposite sides of the module 8 are configured to position the module 8 in the y-direction.

[0057] The object table 2 may be provided with any number of actuators 10. Referring to Figure 4B, for example, the actuators may be applied as pairs of actuators arranged side by side and working together.

[0058] In addition to the planar motion illustrated in Figure 3, the object table 2 may be provided with additional actuators that enable movement in other degrees of freedom. An object has six degrees of freedom that define its position in space: three translational degrees of freedom and three rotational degrees of freedom. Translational degrees of freedom are generally represented as the x, y, and z directions in a Cartesian coordinate system. The x, y, and z directions are orthogonal to each other. Rotational degrees of freedom are generally represented as the rx, ry, and rz directions, where rx is a rotation with an axis of rotation in the x direction, ry is a rotation with an axis of rotation in the y direction, and rz is a rotation with an axis of rotation in the z direction.

[0059] Each actuator 10 may comprise a magnet assembly 11 and a coil 12. The magnet assembly 11 may comprise a first magnetic body 14 and a second magnetic body 16. The magnetic bodies may comprise magnets. The magnets may be permanent magnets and / or electromagnets comprising an electric coil and an iron or ferromagnetic core. Preferably, the magnets are permanent magnets. The magnet assembly may be enclosed in a housing or container that at least partially encloses the corresponding magnets, typically having an open side facing the other magnetic body. This container is sometimes called a back iron. The coil 12 can be actuated to function as an electromagnet. Actuating the coil 12 generates an electromagnetic force, which causes the magnet assembly 11 to move relative to the coil 12. The short-stroke module 8, being connected to the magnet assembly, moves similarly.

[0060] The first magnetic material 14 and the second magnetic material 16 may attract each other due to their respective magnetic forces. Alternatively, the forces of the first magnetic material 14 and the second magnetic material 16 may repel each other. In either case, the magnetic force is usually directed perpendicular to the operating direction 15. In Figures 2 and 3, the magnetic force may be directed perpendicular to the xy-plane. The operating direction 15 may be in the xy-plane.

[0061] The coil assembly 12 extends at least partially between the first magnetic material 14 and the second magnetic material 16. The coil assembly 12 may be connected to the long-stroke module 6. Alternatively, the coil assembly 12 may be fixed to the base 4 (for example, if the system does not have a long-stroke module and the short-stroke module is movable relative to the base).

[0062] The magnetic bodies 14 and 16 may be housed in a housing 18, also called a yoke. The housing may be U-shaped. The housing may be made of or comprise a ceramic and / or mineral such as cordierite. The housing 18 may be connected to a movable object such as a short-stroke module 8.

[0063] A damper 20 may be provided at the interface between each magnetic material 14, 16 and the housing 18. Another damper 21 may be provided between adjacent magnetic materials, as illustrated in Figure 4B.

[0064] Referring generally to Figures 5, 6, and 7, in one embodiment, the damper 20 comprises two plates, namely a first plate 22 and a second plate 24. Multiple connecting elements, such as supports or columns 26, may be provided between the plates 22 and 24. The plates 22 and 24 may be arranged parallel to each other. Parallel here may include plates that are slightly inclined relative to each other. For example, the first plate 22 may extend at an angle α relative to the second plate 24. When angle α is 0, the two plates are strictly parallel. This angle α may be in the range of, for example, 5 to 20 degrees, or, for example, about 10 degrees. The plates 22 and 24 may be arranged at an angle to each other, for example, to accommodate the design characteristics and specifications of other devices. The two plates do not need to be strictly parallel to each other. In practical embodiments, the two plates 22 and 24 achieve relatively low shear stiffness relative to each other compared to the stiffness in the direction perpendicular to the plates. Connecting elements or supports may be connected to each plate. Alternatively, the support columns may be integrated with each plate. The assembly 28, consisting of the first plate 22, the second plate 24, and the support columns 26, may be manufactured, for example, using three-dimensional (3D) printing technology.

[0065] A pair of parallel plates 22 and 24 define a volume 30 between them. Multiple support columns 26 are arranged in the volume 30. An elastomer section 32 is also arranged in the volume 30. The elastomer section 32 surrounds the support columns and extends between the plates 22 and 24.

[0066] In practical embodiments, the elastomer portion 32 comprises an elastomer. For example, the elastomer portion may be entirely formed of an elastomer. Alternatively, the elastomer portion may comprise a layered or laminated structure of a suitable material that provides elastic or elastomer properties. Elastomers are also called viscoelastic materials. Elastomers may be rubber or rubber-like materials, or viscoelastic polymers. As materials, EPDM rubber or similar relatively hard rubbers may be used. For applications in lithography equipment that typically operates in medium vacuum (e.g., 5 kPa) to high vacuum (e.g., 5 Pa), elastomers suitable for use under vacuum are preferred. Examples include elastomer materials marketed by DuPont® under trademarks such as Hytrel® and Kalrez®.

[0067] To manufacture the damper, an assembly 28 consisting of a first plate 22, a second plate 24, and a support column 26 may be formed, for example, using three-dimensional (3D) printing technology. The viscoelastic material may be introduced in an uncured state into the volume between the two plates, for example, by injection or pump delivery. In a subsequent step, the elastomer material may be cured, for example, using an appropriate curing step involving a curing agent and / or heat contained in the material.

[0068] In practical embodiments, the supports are distributed substantially uniformly across the volume. That is, the supports are provided on the surface of the plate facing the opposing plate, and the supports are distributed across the surface of each plate. In one embodiment, the supports are uniformly distributed across the surface. The supports may have any shape and size. In one embodiment, the supports are relatively thin. Therefore, the supports allow for some degree of bending. For example, the supports may be substantially circular. On the surface of each plate, for example, 1 cm 2Approximately 1 to 10 support columns may be provided per plate. The diameter of the support columns may be approximately 0.1 to 0.5 mm, for example, about 0.3 mm. The distance between plates, i.e., the length of the support columns, may be approximately 1 to 50 mm, for example, about 2 to 10 mm, for example, about 5 mm. Depending on the application, the required damping and / or stiffness, the number of support columns and volume may be larger or smaller. In one embodiment, the distribution of connecting elements or support columns may be non-uniform. Such a distribution may be useful when, for some reason, the force distribution on the plate is non-uniform, for example, because the stiffness of the mating mounting surface to which the plate is attached (e.g., bonded) is non-uniform.

[0069] In future applications, the board throughput per hour could increase to, for example, 500 boards. The short-stroke module 8 doubles the acceleration compared to the current 400 boards / hour system (dry system). The short-stroke acceleration will ultimately reach 100 to 110 m / s². 2 It may exceed this. At such accelerations, dampers often lack the overall characteristics to provide sufficient damping across the entire frequency range.

[0070] For example, Figure 8 shows the simulation results for the behavior of a short-stroke module without a damper, indicated by line 100. Any damping effect originates from the materials contained in the short-stroke module and the magnet assembly. At multiple frequencies, particularly in higher-order modes, the system exhibits significant disturbance, hysteresis, and vibration. For the short-stroke module, some form of compensation will be necessary, for example, by allowing time to stabilize the short-stroke module after each movement, or by accepting an increased tolerance for error. Line 110 shows the modeling results when using the damper according to this disclosure. The damper of this disclosure provides damping over a wide bandwidth. The damper eliminates spring-like behavior through the combined properties of the elastomer and the support. The damper dampens the major modes of vibration over a wide frequency range.

[0071] The present invention makes it possible to eliminate the need for a heavy frame surrounding the magnets. Instead, the damper of this disclosure can be directly connected to the magnetic material and the housing for the magnets, for example, by adhesive. That is, the outer surfaces of plates 22, 24 may be connected to other devices by adhesive. The damper of this disclosure eliminates the need for a decoupling leaf spring between the magnets 14, 16 and the back iron, and can be directly connected to the material of the yoke 18.

[0072] A suitable adhesive may be, for example, Scotch-Weld®, which is commercially available from 3M®. Here, for example, Scotch-Weld's structural epoxy adhesive EC-9323-2 B / A, or Scotch-Weld's polyurethane adhesive may be suitable.

[0073] The material of the plates and supports may include titanium. The titanium may be of grade 1 to grade 23. The supports may also include a metal composition. The metal composition may be, for example, Ti6-Al-4V.

[0074] A damper is a combination of an elastomer material (such as rubber) and small solid pillars dispersed on the surface of the elastomer volume. The pillars are preferably made of metal. The metal may be any metal. In practical embodiments, the metal is nonmagnetic. In one embodiment, the metal is titanium or contains titanium. For applications near magnets, such as the short-stroke module movement applications described above, the metal is preferably nonmagnetic. In one embodiment, the pillars are formed of titanium or a titanium composition.

[0075] The design of the elastomer and metal support is optimized so that the stiffness in different directions (x, y, z) is suitable for both high bandwidth and low internal chuck deformation error (expressed as the Interest to Control Error (ICE)). The internal chuck deformation error referred to here is the mechanical deformation that occurs in the short-stroke module 8 under relatively high acceleration conditions, as mentioned above.

[0076] 110 m / s 2 Simulations using acceleration and a maximum speed of 1.6 m / s (equivalent to a throughput of up to 500 boards per hour) yielded the results shown in the table below. Here, the size and controller settings of both options were similar, and the jerk-to-acceleration ratio and snap-to-jerk ratio were also identical. The damper using only elastomer significantly exceeded the tolerance limit of chuck deformation error (ICE), making it impossible to achieve the target high throughput. In other words, the damper using only rubber causes deformation of the connected board stage when a certain acceleration level is exceeded, resulting in exceeding the tolerance limit. The simulation was conducted on a support column with a diameter of approximately 0.3 mm and a length of approximately 5 mm. This length corresponds to the thickness of the elastomer and provides an optimal value for low ICE. When using the damper of this disclosure, the chuck deformation error is very low and remains well below the tolerance limit or specification threshold. [Table 1]

[0077] The simulation yielded the following exemplary values ​​for the stiffness of each part of the damper. [Table 2]

[0078] The exemplary values ​​shown in the table above demonstrate that the balance between the rigidity of the elastomer and the rigidity of the metal support can provide optimal performance when combined as an assembly. Furthermore, compared to dampers made of elastomer alone, the dampers of this disclosure enable an increase in the controller bandwidth, for example, from approximately 350 Hz (elastomer damper only) to approximately 500 Hz (when using the dampers of this disclosure). In addition, the weight of the short-stroke module can be reduced, for example, from approximately 17 kg (conventional system) to approximately 13 to 14 kg (when using the dampers of this disclosure).

[0079] With the damper of the present disclosure, the following can be achieved. · Reduction of the mass of the short stroke module 8 by approximately 3 kg to enable an acceleration of up to approximately 110 m / s while keeping the actuator magnet and the back iron the same. 2 · A bandwidth of approximately 500 Hz in the important horizontal direction. · An ICE error of less than 0.1 nm at a stabilization time of substantially zero ("0" ms). Since the stabilization time is not required, for example, exposure can be performed immediately after the movement of the substrate table. This usually results in a time reduction on the order of milliseconds per exposure. Since the lithography apparatus described above is usually operated substantially non-stop, this time reduction contributes to the overall throughput and performance improvement. · The stress under high acceleration in the damper is well below the mechanical constraints of each material used (for example, for adhesives, less than 2 N / mm 2 for titanium struts, less than 50 N / mm 2 for elastomers, less than 0.5 N / mm 2 ). It should be noted that the stress limit of the adhesive is a limiting factor, and conventional dampers usually cannot meet this.

[0080] Although this specification may specifically refer to the use of a lithography apparatus in IC manufacturing, it should be understood that the lithography apparatus described herein is also applicable to other uses. Other examples of applications include the manufacture of integrated optical systems, induction and detection patterns for magnetic domain memories, flat panel displays, liquid crystal displays (LCDs), thin film magnetic heads, and the like.

[0081] While embodiments of the present invention may be specifically referred to in the context of lithography apparatus, embodiments of the present invention may also be used in other apparatuses. Embodiments of the present invention may form part of a mask inspection apparatus, a measuring apparatus, or any apparatus for measuring or processing objects such as wafers (or other substrates) or masks (or other patterning devices). These apparatuses are also commonly referred to as lithography tools. Such lithography tools may operate under vacuum conditions or atmospheric pressure (non-vacuum) conditions.

[0082] While the use of embodiments of the present invention may be specifically mentioned above in the context of photolithography, it will be understood that, to the extent the context allows, the present invention is not limited to photolithography and can be used in other applications, such as imprint lithography.

[0083] Although specific embodiments of the present invention have been described above, it will be understood that the present invention can be implemented in ways other than those described. The above description is for illustrative purposes only and is not intended to be limiting. Accordingly, it will be clear to those skilled in the art that modifications to the described invention can be made without departing from the scope of the claims described below.

Claims

1. A damper for an object table, A pair of plates positioned between them to define their respective volumes, A plurality of support columns are arranged in the volume and extend between the pair of plates, A damper comprising an elastomer portion that surrounds the support column and extends between the plates.

2. The damper according to claim 1, wherein the support columns are uniformly distributed within the volume.

3. The damper according to claim 1 or 2, configured to function as an interface between a magnet assembly and the frame of an actuator.

4. The damper according to any one of claims 1 to 3, wherein the support column is made of a non-magnetic metal, such as titanium.

5. The damper according to any one of claims 1 to 4, wherein the support column has a length of about 1 to 10 mm and / or a diameter of about 0.1 to 0.5 mm.

6. The damper according to any one of claims 1 to 5, wherein the elastomer portion comprises an elastomer.

7. The damper according to any one of claims 1 to 6, wherein the elastomer portion has a laminated structure.

8. An object table for a lithography apparatus, Bass and, The system comprises at least a short-stroke module that is movable relative to the base, An object table comprising a short stroke module, one or more magnetic actuators arranged on each side of the short stroke module, and at least one damper according to claim 1, arranged between the one or more magnetic actuators and the short stroke module.

9. A lithography apparatus comprising at least one object table as described in claim 8, and / or at least one damper as described in claim 1.

10. A measuring tool for a lithography process comprising at least one object table as described in claim 8, and / or at least one damper as described in claim 1.

11. A method for dampening the movement of a module, The steps of providing a device comprising at least one movable module, the module being provided with at least one actuator, The step of connecting at least one damper between the at least one actuator and the module, The damper comprises at least a pair of plates that define a volume between them, a plurality of support columns arranged in the volume and extending between the pair of plates, and an elastomer portion surrounding the support columns and extending between the plates. A method further comprising the step of moving the module using at least one of the actuators.

12. The method according to claim 11, wherein the support columns are uniformly distributed in the volume.

13. The method according to claim 11 or 12, wherein the step of connecting at least one damper between the module and the actuator comprises connecting the damper as an interface between the magnet assembly and the frame of the actuator.

14. The step of moving the module involves moving the module at 60 m / s ２ Acceleration exceeding 90 m / s², for example. ２ Acceleration exceeding 100 m / s², for example, 100 m / s². ２ The method according to any one of claims 11 to 13, comprising accelerating to an acceleration exceeding a certain value.

15. The steps include: 3D printing the support column and the pair of plates as a single unit; The steps include filling the volume between the plates with an elastomer, The method according to any one of claims 11 to 14, comprising the step of curing the elastomer.

16. A damper for an object table, A pair of opposing plates positioned so as to define the volume between them, A plurality of connecting elements are arranged in the volume and extend between the pair of plates, A damper comprising an elastomer portion that surrounds the connecting element and extends between the plates.

17. The damper according to claim 16, wherein the connecting elements are uniformly distributed in the volume.

18. The damper according to claim 16 or 17, configured to function as an interface between a magnet assembly and the frame of an actuator.

19. The damper according to any one of claims 16 to 18, wherein the connecting element is made of a non-magnetic metal, such as titanium.

20. The damper according to any one of claims 16 to 19, wherein the connecting element has a length of about 1 to 10 mm and / or a diameter of about 0.1 to 0.5 mm.

21. The damper according to any one of claims 16 to 20, wherein the elastomer portion comprises an elastomer.

22. The damper according to any one of claims 16 to 21, wherein the elastomer portion has a laminated structure.

23. An apparatus comprising at least one damper as described in claim 16.

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