CN113574650A - Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system - Google Patents

Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system Download PDF

Info

Publication number
CN113574650A
CN113574650A CN201980093452.XA CN201980093452A CN113574650A CN 113574650 A CN113574650 A CN 113574650A CN 201980093452 A CN201980093452 A CN 201980093452A CN 113574650 A CN113574650 A CN 113574650A
Authority
CN
China
Prior art keywords
damping
carrier
frequency
tuned
units
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
CN201980093452.XA
Other languages
Chinese (zh)
Inventor
亚历山大·森多布里
乔格·舒勒
马丁·恩斯特
克里斯蒂安·沃尔夫冈·埃曼
布里塔·斯帕
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Applied Materials Inc
Original Assignee
Applied Materials Inc
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 Applied Materials Inc filed Critical Applied Materials Inc
Publication of CN113574650A publication Critical patent/CN113574650A/en
Pending legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
    • H01L21/67703—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations between different workstations
    • H01L21/67709—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations between different workstations using magnetic elements
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
    • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
    • F16F7/00—Vibration-dampers; Shock-absorbers
    • F16F7/10—Vibration-dampers; Shock-absorbers using inertia effect
    • F16F7/104—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted
    • F16F7/116—Vibration-dampers; Shock-absorbers using inertia effect the inertia member being resiliently mounted on metal springs
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
    • H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
    • H01L21/677—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations
    • H01L21/67703—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations between different workstations
    • H01L21/67712—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere for conveying, e.g. between different workstations between different workstations the substrate being handled substantially vertically

Abstract

There is provided a magnetic levitation system comprising: a base structure; a carrier movable relative to the base structure in a transport direction; and at least one active magnetic bearing configured to generate a magnetic holding force acting in a holding direction for holding the carrier at the base structure. The carrier and/or the base structure comprises a plurality of damping units, a first damping unit of the plurality of damping units being tuned to a first frequency or a first frequency range and a second damping unit of the plurality of damping units being tuned to a second frequency or a second frequency range.

Description

Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system
Technical Field
Embodiments of the present disclosure relate to a magnetic levitation system configured for holding and transporting a carrier, in particular in a vacuum chamber. More specifically, a magnetic levitation system configured to contactlessly hold, position and/or move a carrier in a vacuum chamber is described. Embodiments further relate to a carrier for a magnetic levitation system, the carrier being configured to carry an object, such as a substrate or a mask, in a vacuum chamber. Furthermore, a method of operating a magnetic levitation system is described.
Background
The magnetic levitation system can be used for contactless or substantially contactless transport of the carrier relative to the base structure, for example at sub-atmospheric pressure in a vacuum chamber. An object, such as a substrate or a mask, carried by a carrier can be transported from a first position, i.e. a loading position, in the vacuum system to a second position, e.g. a deposition position, in the vacuum system. The magnetic levitation system allows for the transport of the carrier substantially without contact and can reduce the generation of small particles in the vacuum processing system since friction between the carrier and the transport system is reduced or completely avoided.
Magnetic levitation systems typically comprise one or more actively controlled magnetic bearings configured to hold a carrier at a predetermined distance at a base structure via magnetic forces. Accurate active control of the carrier position can be difficult because the carrier, which is held substantially contactless via magnetic forces, tends to vibrate. Such vibrations may be caused by active magnetic bearings or other sources of the magnetic levitation system.
Complex control algorithms for active magnetic bearings can be used to reduce carrier vibration. However, reducing or avoiding oscillations of the carrier of a magnetic levitation system can be challenging, in particular because the oscillation behavior of the carrier is typically complex and depends on the size, shape and material of the carrier and of the object carried by the carrier. The oscillation of the carrier may adversely affect the transportation stability and positioning accuracy of the carrier.
Therefore, it would be beneficial to improve the transport and positioning accuracy of the carrier of a magnetic levitation system. In addition, it would be beneficial to provide a carrier for a magnetic levitation system which is adapted to be accurately and precisely transported and held at a base structure of the magnetic levitation system.
Disclosure of Invention
In view of the above, a magnetic levitation system, a carrier for a magnetic levitation system and a method of operating a magnetic levitation system are provided.
According to an aspect of the present disclosure, a magnetic levitation system is provided. The magnetic levitation system includes: a base structure; a carrier movable relative to the base structure in a transport direction; and at least one active magnetic bearing configured to generate a magnetic holding force acting in a holding direction for holding the carrier at the base structure. The carrier includes a plurality of damping units, a first damping unit of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit of the plurality of damping units being tuned to a second frequency or a second frequency range.
According to another aspect of the present disclosure, a magnetic levitation system is provided. The magnetic levitation system includes: a base structure; a carrier movable relative to the base structure in a transport direction; and at least one active magnetic bearing configured to generate a magnetic holding force acting in a holding direction for holding the carrier at the base structure. The base structure comprises a plurality of damping units, a first damping unit of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit of the plurality of damping units being tuned to a second frequency or a second frequency range.
The first frequency is different from the second frequency. In some embodiments, the first frequency may substantially correspond to a first normal frequency of the carrier, and the second frequency may substantially correspond to a second normal frequency of the carrier. Thus, different normal modes of the carrier can be damped with the plurality of damping units.
According to another aspect of the present disclosure, a carrier for a magnetic levitation system is provided, the carrier being configured to interact with a base structure of the magnetic levitation system such that the carrier can be held at the base structure and is movable relative to the base structure. The carrier includes a plurality of damping units, a first damping unit of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit of the plurality of damping units being tuned to a second frequency or a second frequency range.
According to another aspect of the present disclosure, a base structure of a magnetic levitation system is provided, the base structure being configured to interact with a carrier of the magnetic levitation system such that the carrier can be held at the base structure and is movable relative to the base structure. At least one active magnetic bearing is provided at the carrier or the base structure for generating a magnetic holding force acting in a holding direction for holding the carrier at the base structure. The base structure comprises a plurality of damping units, a first damping unit of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit of the plurality of damping units being tuned to a second frequency or a second frequency range.
According to another aspect described herein, there is provided a method of operating a magnetic levitation system comprising a base structure and a carrier movable relative to the base structure in a transport direction. The method comprises actively controlling at least one active magnetic bearing to generate a magnetic holding force to hold a carrier at the base structure. Additionally, the method includes damping the vibration of the carrier with a plurality of damping units fixed to the carrier, a first damping unit of the plurality of damping units tuned to a first frequency or a first frequency range, and a second damping unit of the plurality of damping units tuned to a second frequency or a second frequency range.
According to another aspect described herein, there is provided a method of operating a magnetic levitation system comprising a base structure and a carrier movable relative to the base structure in a transport direction. The method comprises actively controlling at least one active magnetic bearing to generate a magnetic holding force holding a carrier at the base structure. Additionally, the method includes damping the vibration of the base structure with a plurality of damping units fixed to the base structure, a first damping unit of the plurality of damping units tuned to a first frequency or a first frequency range, and a second damping unit of the plurality of damping units tuned to a second frequency or a second frequency range.
Further aspects, advantages and features of the present disclosure are apparent from the description and the accompanying drawings.
Drawings
So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The drawings relate to various embodiments of the present disclosure and are described below. Exemplary embodiments are depicted in the drawings and are detailed in the following description.
Fig. 1 is a schematic side view of a magnetic levitation system according to various embodiments described herein.
Fig. 2 is a schematic side view of a magnetic levitation system according to various embodiments described herein.
Fig. 3A is a schematic side view of a carrier according to various embodiments described herein.
Fig. 3B is a graph showing the oscillating behavior of the carrier of fig. 3A, the carrier vibrating in different normal modes.
Fig. 4A is a schematic diagram illustrating the principle of operation of a damping unit configured as a tuned mass damper as used in various embodiments described herein.
Fig. 4B is a schematic view showing the damping unit mounted to the carrier.
Fig. 4C is a schematic cross-sectional view illustrating two damping units in a common housing as used in various embodiments described herein.
Fig. 5 is a graph showing the location of the natural frequency of a typical undamped carrier.
Fig. 6 is a flow diagram illustrating a method of operating a magnetic levitation system according to various embodiments described herein.
Detailed Description
Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not intended as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. The present disclosure is intended to encompass such modifications and variations.
Within the following description of the drawings, like reference numerals refer to the same or similar parts. Generally, only the differences with respect to the individual embodiments are described. Unless otherwise indicated, descriptions of parts or aspects in one embodiment also apply to corresponding parts or aspects in another embodiment.
Fig. 1 is a schematic cross-sectional view of a magnetic levitation system 100 according to various embodiments described herein. The magnetic levitation system 100 comprises a base structure 110 and a carrier 120, which can be held at the base structure 110 in a contactless or substantially contactless manner and which is movable relative to the base structure 110 in a transport direction T. The base structure 110 may include one or more rails. At least one active magnetic bearing 112 may be disposed at the track of the base structure 110. In some embodiments, a plurality of active magnetic bearings are provided at the base structure 110 and arranged such that the carrier is movable along the base structure 110 while being held non-contactingly or substantially non-contactingly at the base structure by the plurality of active magnetic bearings. In another embodiment, one or more active magnetic bearings may be provided at the carrier and configured to magnetically interact with the base structure.
The at least one active magnetic bearing 112 may be arranged above the carrier 120 during carrier transport, and the magnetic holding force generated by the at least one active magnetic bearing 112 may act on the carrier in a holding direction V, which is typically a substantially vertical (vertical) direction. In other words, the at least one active magnetic bearing 112 may provide a controlled magnetic force that pulls the carrier in an upward direction towards the at least one active magnetic bearing 112 and maintains the carrier at a predetermined distance from the at least one active magnetic bearing.
In the embodiment depicted in fig. 1, the base structure 110 includes a top rail disposed above the carrier 120, and the carrier 120 is held below the top rail. Alternatively or additionally, the base structure 110 may comprise a bottom rail arranged below the carrier, wherein the carrier is held above the bottom rail. The at least one active magnetic bearing 112 may be configured to generate a magnetic force acting between the base structure 110 and the carrier 120 in the holding direction V such that the carrier is held at a predetermined distance from the base structure. In some embodiments, the at least one active magnetic bearing 112 is configured to generate a magnetic force acting in a substantially vertical direction.
In some embodiments, the at least one active magnetic bearing 112 comprises an actuator arranged at the base structure 110, in particular at a top rail of the base structure 110. The actuator may comprise a controllable magnet, such as an electromagnet. The actuators may be actively controllable for maintaining a predetermined distance between the base structure 110 and the carrier 120. The magnetic counterpart 118 may be arranged at the carrier 120, in particular at a head portion of the carrier. The magnetic counterpart 118 of the carrier may magnetically interact with the actuator of the at least one active magnetic bearing 112.
More specifically, an output parameter, such as the current applied to the actuator, may be controlled in dependence of an input parameter, such as the distance between the carrier and the base structure. In particular, the distance between the base structure 110 and the carrier 120 may be measured by a distance sensor, and the magnetic field strength of the actuator may be set in dependence of the measured distance. In particular, in case the distance is above a predetermined threshold value, the magnetic field strength may be increased, and in case the distance is below the threshold value, the magnetic field strength may be decreased. The actuator may be controlled in a closed loop or feedback control.
There is a risk that the control of the at least one active magnetic bearing 112 causes carrier vibrations. A specific control algorithm for controlling the at least one active magnetic bearing may be provided to reduce carrier vibrations at least in the low frequency range, e.g. below 30 Hz. However, it is typically difficult to reduce or avoid carrier vibrations in the higher frequency range (e.g., above 30Hz or above 50Hz) with control of the active magnetic bearing. The reduction of vibrations in the so-called "critical damping range" between 50Hz and 250Hz is particularly difficult. The high frequency range, e.g. above 300Hz, is typically less problematic, as the control of the active magnetic bearing 112 typically does not provide sufficient power in said range to cause the carrier to vibrate.
Depending on the size, shape and material of the carrier 120, so-called "eigenmodes" or natural vibrations of the carrier may hinder a stable and robust control of the active magnetic bearing over the carrier position. For example, an already small excitation amplitude caused by the control of the at least one active magnetic bearing 112 may lead to a large resonance of the carrier at the natural frequency of the carrier. The complex control algorithms of the active magnetic bearing can be utilized to reduce the vibration of the carrier during magnetic levitation at least in the low frequency range. Alternatively or additionally, a damping unit may be used to reduce the vibration of the carrier. For example, an active or passive damping unit may be provided for damping the carrier vibration during magnetic levitation.
However, the above measures may not be sufficient to allow accurate positioning and stable transport of the carrier with magnetic forces. The various embodiments described herein aim to further improve the transport stability and positioning accuracy of the carrier of a magnetic levitation system.
According to various embodiments described herein, the carrier 120 comprises a plurality of damping units 130, wherein a first damping unit 131 of the plurality of damping units is tuned to a first frequency or a first frequency range and a second damping unit 132 of the plurality of damping units is tuned to a second frequency or a second frequency range. The first frequency (first frequency range) is different from the second frequency (second frequency range). Alternatively or additionally, the base structure comprises a plurality of damping units or a second plurality of damping units.
In other words, the carrier 120 and/or the base structure comprises a plurality of damping units, which are each specifically tuned to specifically damp vibrations of a predetermined frequency. As used herein, a damping unit that is "tuned" to a particular frequency provides a maximum damping effect substantially at the frequency to which the damping unit is tuned (hereinafter referred to as the "damping frequency" of the damping unit). The damping effect provided by the tuned damping unit typically decreases from the damping frequency towards higher and lower frequencies. In other words, the damping curve of the damping unit has a minimum value at the damping frequency and rises towards both sides of the damping frequency, so that the carrier vibrations at the damping frequency are damped efficiently. This rise is slow in the case of tuning the broadband damper to an extended frequency range, whereas it is steep in the case of a small-bandwidth damper (small-bandwidth damper) tuned to a specific frequency (e.g. a specific natural frequency of the carrier). In particular, the damping unit is configured such that vibrations at the frequency to which the damping unit is tuned can be effectively damped. As used herein, a damping unit "tuned" to a specific natural frequency of the carrier may be understood as a damping unit having a damping frequency within 10Hz of the natural frequency to which the damping unit is tuned.
The damping ratio is a dimensionless constant of the damping unit, and the damping ratio characterizes the damping strength of the damping unit. In the mathematical description of the oscillation, the damping ratio characterizes the factor preceding the first derivative of the local function. A damping ratio of 1 (critical damping) characterizes a damping unit that damps vibrations within one cycle (i.e., without exceeding specifications). A zero damping ratio characterizes an undamped system. Values of damping ratio between 0 and 1 characterize low damping systems. A damping unit tuned to a damping frequency as used herein typically provides a damping ratio of 0.1 or greater at the damping frequency.
There are a number of ways to tune the damping unit to a particular damping frequency. For example, the damping unit may be a passive damper, such as a shock absorber or a tuned mass damper with a damping mass movably fixed to the body to be damped via spring elements. The damping frequency depends on the spring constant of the damping mass and the spring element. Thus, the damping frequency can be set by providing a specific combination of e.g. damping mass, length and material of the spring element.
The carrier is characterized by a plurality of natural modes in which the carrier can vibrate. Each oscillation state of the carrier can be described by a superposition of the natural modes of the carrier. Each natural mode is characterized by a natural frequency. The fundamental natural mode of the carrier is the natural mode with the lowest natural frequency, i.e. the fundamental natural frequency. The fundamental natural frequency of the carrier (which is understood to be the vibration frequency of the vibration mode in which the carrier as a whole vibrates, i.e. the vibration frequency of the rigid body mode) is typically in the frequency range between 5Hz and 30 Hz. Higher order natural modes are characterized by higher natural frequencies at which the carrier can vibrate.
The natural modes of the carrier may be rigid body modes (in which the carrier vibrates as a whole) and elastic modes (in which different parts of the carrier vibrate with respect to each other, e.g. torsional or bending modes). Typically, the oscillation state of the carrier is a superposition of rigid body and elastic modes at a plurality of natural frequencies. Depending on the nature of the carrier, the first elastic natural frequency may occur in a range between 50Hz and 80 Hz.
The corresponding considerations apply to the oscillatory behavior of the base structure caused by the at least one active magnetic bearing.
In magnetic levitation systems, the majority of the carrier vibrations are typically caused by the magnetic holding force of at least one active magnetic bearing, which acts in a holding direction V, typically in the vertical direction. Therefore, the vibration amplitude of the carrier is highest in the holding direction V. Thus, according to various embodiments described herein, at least some of the plurality of damping units 130 are oriented such that carrier vibrations in the holding direction V are damped.
However, carrier vibrations having amplitudes in other directions (e.g. in the lateral direction) are also possible. A lateral direction as used herein is a direction transverse to the holding direction V, in particular a horizontal direction perpendicular to the holding direction V. For example, the lateral carrier oscillation may be caused by a horizontally acting component of the magnetic force generated by the at least one active magnetic bearing. It may be reasonable in some embodiments to provide at least one damping unit (hereinafter lateral vibration damping unit) oriented such that carrier vibrations in the lateral direction are damped.
As mentioned above, carrier vibrations in the low frequency range below 30Hz can be damped efficiently by active control of the at least one active magnetic bearing. However, the higher-order natural modes of the carrier characterized by higher natural frequencies typically cannot be sufficiently suppressed by control of the magnetic levitation force. At least some of the damping units are tunable to such higher natural frequency of the carrier or to a frequency range comprising at least one or more higher natural frequencies.
According to some embodiments described herein, the first damping unit 131 is tuned to a first frequency in the frequency range from 50Hz to 250Hz, in particular to a first natural frequency of the carrier in said range, and the second damping unit 132 is tuned to a second frequency in the frequency range from 50Hz to 250Hz, in particular to a second natural frequency of the carrier in said range, different from the first frequency. For example, the first damping unit 131 is tuned to the natural frequency of the second order natural mode of the carrier, and the second damping unit 132 is tuned to the natural frequency of the third order natural mode of the carrier. Typically, the natural frequency of the at least second to fifth order natural modes of the carrier is in the frequency range from 50Hz to 250 Hz.
Fig. 5 is a graph showing the natural frequency of a typical undamped carrier. The x-axis shows the frequency in hertz and the y-axis shows the relative amplitude of the carrier oscillation at the corresponding frequency expressed in logarithmic scale (in dB). Only the oscillating behavior of the carrier in the holding direction V is shown. As is clearly shown in fig. 5, the fundamental natural mode of the carrier has a fundamental natural frequency E0 in the frequency range between 5Hz and 30 Hz. As shown by the high peaks in fig. 5, the carrier can be excited to high amplitude vibrations at the fundamental natural frequency E0 without damping.
The plurality of natural modes of the carrier have natural frequencies E2, E3, E4, E5 within a critical damping range X between 50Hz and 250 Hz. Other higher order natural modes may exist in the critical damping range X, depending on the carrier characteristics. As shown by the peaks in the critical frequency range X in fig. 5, without damping, the carrier can be excited to vibrations with considerable amplitudes at these frequencies. A damping carrier with a plurality of damping units tuned to frequencies in the critical frequency range X has a less pronounced peak in the critical frequency range X.
During transport of the carrier, the carrier can be vibrationally excited at the fundamental natural frequency E0 and/or at one or more higher natural frequencies E1, E2, E3, E4, E5, E6. The vibration excitation can take place in a forced manner by means of a magnetic retaining force generated by the at least one active magnetic bearing 112. The fundamental natural mode can be damped at least to some extent by a controller of the at least one active magnetic bearing. The plurality of damping units 130 may be tuned to at least some natural frequencies, such as natural frequencies E1, E2, E3, E4, and/or E5 of first-order to fifth-order natural modes of the carrier. In some embodiments, the plurality of damping units are tuned to different frequencies within a critical damping range from 50Hz to 250Hz, which frequencies do not necessarily correspond exactly to the natural frequency. If several damping units are tuned to different frequencies distributed within the critical frequency range, the natural modes of the carrier within said range will also be significantly damped.
Returning to fig. 1, the first damping unit 131 and the second damping unit 132 are tunable to different frequencies, in particular to different natural frequencies of the carrier, more in particular to different frequencies within a critical frequency range between 50Hz and 250 Hz. In some embodiments, the first and second damping units 131, 132 are tuned to different higher order natural frequencies within a critical frequency range between 50Hz and 250 Hz. Thus, carrier vibrations in the critical damping range between 50Hz and 250Hz can be reliably damped and a smooth and reliable carrier transport can be provided.
In some embodiments, the first and second damping units 131, 132 are oriented to damp carrier vibrations in the holding direction V or vibrations of the base structure in the holding direction V. In particular, the plurality of damping units 130 may be configured as passive dampers, wherein the damping mass is configured to be movable in the holding direction V. The damping mass, which is movably fixed to the carrier (or to the base structure) to vibrate in the holding direction V, can counteract the carrier vibrations (or the vibrations of the base structure) in the holding direction V. Therefore, the carrier vibration in the holding direction caused by the at least one active magnetic bearing 112 can be reliably reduced.
In some embodiments, the plurality of damping units 130 includes three or more damping units, five or more damping units, eight or more damping units, or even fifteen or more damping units, each oriented to damp vibrations in the holding direction V.
As depicted in fig. 1, the carrier may comprise a head portion magnetically interacting with the base structure 110 and a bottom portion configured to carry the object, in particular the substrate 10. The first damping unit 131 and/or the second damping unit 132 may be disposed at a head portion of the carrier. In particular, five or more damping units of the plurality of damping units may be disposed at the head portion of the carrier 120. The elastic mode of the carrier caused by the at least one active magnetic bearing is typically stronger at the head portion of the carrier compared to the bottom portion of the carrier, since the head portion is closer to the base structure during transport of the carrier. Therefore, the carrier vibration can be damped more efficiently.
In some embodiments, which can be combined with other embodiments described herein, the plurality of damping units 130 comprises at least one central damping unit arranged in a central portion of the carrier in the transport direction T and/or at least one edge damping unit arranged in a front portion or a rear portion of the carrier in the transport direction T. The central damping unit 133 may be tuned substantially to the natural frequency of the natural mode with the largest amplitude in the central part of the carrier. Alternatively or additionally, the edge damping unit 134 may be tuned substantially to the natural frequency of the natural mode having the largest amplitude in the respective edge portion of the carrier where the edge damping unit 134 is arranged. Thus, different natural modes of the carrier can be damped efficiently with associated damping units, which are also adapted to damp the respective natural modes by a respective positioning. In some embodiments, two or more edge damping units are provided, at least one edge damping unit being arranged in a front portion of the carrier and at least one edge damping unit being arranged in a rear portion of the carrier in the transport direction T.
In some embodiments, two or more central damping units are arranged in a central portion of the carrier. The central damping unit may be tuned to the same frequency or to different frequencies, respectively, in particular to different natural frequencies of the natural modes of the carrier having the largest vibration amplitude at the central portion of the carrier. In some embodiments, two or more edge damping units are arranged in the edge portion of the carrier in the transport direction T. The edge damping units may be tuned to the same frequency or to different frequencies, respectively, in particular to different natural frequencies of the natural modes of the carrier having the largest vibration amplitudes in the edge portions of the carrier.
In some embodiments, the edge damping units 134 are tuned to a higher frequency than the central damping unit 133. This is because the higher-order natural modes of the carrier in the critical damping range typically have a maximum vibration amplitude in the edge region of the carrier. For example, the central damping unit 133 is tuned to a frequency in the range between 50Hz and 120Hz, and the edge damping unit 134 is tuned to a frequency in the range between 150Hz and 250 Hz.
Fig. 2 is a schematic side view of a magnetic levitation system 200 according to various embodiments described herein. Most of the details of the magnetic levitation system 200 of fig. 2 correspond to the details of the magnetic levitation system 100 of fig. 1, so that reference can be made to the above description, which is not repeated here.
The magnetic levitation system 200 includes a base structure 110, which may include a top rail and a bottom rail. At least one active magnetic bearing 112 may be provided at the base structure 110, in particular the top rail. The at least one active magnetic bearing 112 is configured to generate a magnetic holding force acting in a holding direction V for holding the carrier at the base structure in a floating state. In some embodiments, at least one drive unit 114 for moving the carrier in the transport direction T may be provided at the base structure 110, e.g. at a bottom rail of the base structure. The at least one drive unit 114 may be a linear motor configured to transport the carrier along the base structure in the transport direction T. The carrier may comprise a counterpart at the bottom portion configured to magnetically interact with the at least one drive unit 114.
The carrier 120 comprises a plurality of damping units 130, a first damping unit being tuned to a first frequency f1The second damping unit being tuned to a second frequency f2And the third damping unit is tuned to a third frequency f3Wherein the first frequency, the second frequency, and the third frequency are different. Other damping units may be provided which are tunable to other frequencies or at least partly to the same frequency. In the example depicted in fig. 2, five damping units are arranged at the head portion 121 of the carrier, in particular in a linear array. Two edge damping units tuned to the same frequency f1(e.g., a frequency between 120Hz and 200Hz, such as about 160Hz) and are symmetrically arranged with respect to a vertical axis that intersects the center of the carrier. A central damping unit is arranged in the middle of the carrier in the transport direction T and is tuned to the frequency f3(e.g., a frequency between 80Hz and 120Hz, such as about 105 Hz). Two further central damping units are arranged in the central part of the carrier and tuned to the same frequency f2(e.g., a frequency between 60Hz and 90Hz, such as about 85 Hz).
As depicted in fig. 2, in some embodiments, the arrangement of the damping units may be symmetrical with respect to an axis intersecting the center of the carrier. In some embodiments, five or more damping units may be provided, each tuned to a different frequency or different frequency range.
In some embodiments, which can be combined with other embodiments described herein, the plurality of damping units comprises 3 or more damping units, in particular 5 or more damping units, more in particular 8 or more damping units, tuned to 3 or more different frequencies, in particular to frequencies within a critical damping range between 50Hz and 250 Hz.
If a number of damping units tuned to different frequencies distributed in a critical frequency range from 50Hz to 250Hz are provided, it may not be necessary to tune the damping units precisely to the natural frequency of the carrier. This is because many damping units (for example, five or more damping units) having a damping frequency within the critical damping range can also significantly damp natural frequencies within said range even if the damping frequency of the damping unit does not exactly correspond to the natural frequency of the carrier. This approach, which aims to damp dynamic carrier eigenmodes in a specific frequency range with a plurality of differently tuned damping units, is referred to herein as the "multi damper concept". It may not be necessary to tune the damping unit precisely to the natural or eigenmode of the carrier.
Three or more damping units, in particular five or more damping units, may be arranged in a linear array, in particular at the head portion 121 of the carrier configured to interact with the at least one active magnetic bearing 112. An arrangement of a plurality of damping units 130 in a linear array, wherein the linear array extends in the transport direction T, may be beneficial for reliable damping over an extended frequency range without causing further vibration modes. In particular, as schematically depicted in fig. 2, the array of damping units may be symmetrical or substantially symmetrical with respect to an axis vertically intersecting the center of the carrier.
The outermost damping unit may be tuned to a higher frequency, while the centrally arranged damping unit may be tuned to a lower frequency.
The carrier has a dimension in the transport direction T and/or the holding direction V of 1m or more, in particular 2m or more, more in particular 3m or more or even 4m or more. Large carriers have a considerable weight, which generally reduces the value of the simple frequency of the corresponding eigenmodes. Lower frequencies can generally be more easily damped than higher frequencies.
In some embodiments, which can be combined with other embodiments described herein, the carrier comprises a plurality of compartments (compartments) or slots (slots) (also referred to herein as "damper boxes"), each compartment or slot accommodating a damping unit. In one embodiment, at least one or more compartments house one damping unit. For example, in the embodiment depicted in fig. 2, each compartment houses one damping unit. In another embodiment, at least one or more compartments house two damping units. For example, in the embodiment depicted in fig. 3, each compartment houses two damping units tuned to different frequencies.
The damping unit can be inserted into the compartment or slot to be fixed to the carrier. In particular, the carrier may comprise a plurality of compartments or slots having the same size, and the plurality of damping units tuned to different frequencies may have the same size, such that each damping unit can be inserted into any of a plurality of identically shaped compartments. The replacement of the damping units and the rearrangement of the damping units can be easily performed (e.g. in order to optimize the damping effect provided by a plurality of damping units). In particular, the carrier may comprise a plurality of correspondingly shaped compartments or slots in the head portion of the carrier, the compartments being arranged in a linear array. This allows for a fast and easy mounting of the damping unit at the carrier and for a fast and easy replacement and optimization of the overall damping effect provided by the plurality of damping units.
According to a separate aspect described herein, the at least one damping unit is tunable to a fundamental natural frequency of the carrier and/or a damping frequency in a range between 5Hz and 30 Hz. Therefore, the vibration of the carrier at the fundamental natural frequency can be damped more reliably. The fundamental natural frequency of the carrier is typically in the range between 5Hz and 30 Hz. The fundamental natural frequency of the carrier typically refers to the rigid body mode in which the carrier vibrates in its entirety. Thus, control loop based damping in the frequency range between 5Hz and 30Hz can be supplemented with structural damping via one or more damping units. Since in this case the control loop of the active magnetic bearing has to be less vibration damped in the low frequency range, the excitation of the active magnetic bearing to carrier vibrations in the higher frequency range can be reduced. Thus, a better overall damping result can be achieved.
In some embodiments, which can be combined with the other embodiments described herein, at least one damping unit can be provided for damping a rigid body mode of the carrier and/or at least one damping unit can be provided for damping an elastic mode of the carrier.
In some embodiments, the plurality of damping units comprises at least one lateral vibration damping unit 136 oriented to damp carrier vibrations in a second direction different from the holding direction V, in particular substantially perpendicular to the holding direction V. At least one lateral vibration damping unit 136 may be tuned to damp horizontal carrier vibrations fh. The at least one lateral vibration damping unit 136 may have a similar structure to other damping units oriented to damp vibrations in the holding direction V, however, the lateral vibration damping unit is mounted at the carrier in a rotational manner (e.g. rotated by 90 °) so that horizontal vibrations can be damped. For example, the carrier may include at least one compartment or slot oriented such that a damping unit inserted in the at least one compartment or slot damps horizontal carrier vibrations.
In some embodiments, the carrier may comprise at least one first compartment having a shape rotated, in particular rotated 90 °, relative to the shape of at least one second compartment. Thus, the damping unit inserted in the at least one first compartment may damp vertical carrier vibrations and the damping unit inserted in the at least one second compartment may damp horizontal carrier vibrations.
In some embodiments, the carrier comprises at least one lateral vibration damping unit 136 tuned to a fundamental natural frequency of the carrier. Carrier vibrations at the fundamental natural frequency of the carrier typically have high amplitudes without damping (see E0 in fig. 5), so that even horizontal components of such carrier vibrations may not be negligible. Therefore, it may be reasonable to damp the horizontal vibration component of the vibrations at the fundamental natural frequency of the carrier with at least one lateral vibration damping unit 136.
In some embodiments, which may be combined with other embodiments described herein, at least one damping unit of the plurality of damping units may be arranged at the bottom portion 122 of the carrier, in particular below a substrate holding portion of the carrier configured to hold the substrate 10. In particular, at least one lateral vibration damping unit 136 may be arranged at the bottom portion 122 of the carrier, and at least one damping unit configured to damp vibrations in the holding direction V may be arranged at the head portion 121 of the carrier.
In some embodiments, which can be combined with other embodiments described herein, the plurality of damping units comprises at least one broadband damper, in particular a broadband damper tuned to a frequency range between 30Hz and 60 Hz. The wideband damper may be configured to provide a damping ratio of at least 0.1 over an extended frequency range of, for example, 10Hz or higher and/or 30Hz or lower. For example, the wideband damper may be configured to provide a damping ratio of at least 0.1 over at least a frequency range extending from 40Hz to 50 Hz. The broadband damper can not only damp frequencies within a particular damping range of the broadband damper, but can also affect the natural frequencies of the carrier outside the damping range of the broadband damper. For example, a broadband damper tuned to a frequency range between 30Hz and 60Hz may attenuate vibration peaks even to some extent at higher order natural frequencies, such as E2 and E3 depicted in FIG. 5. The damping effect of the small-bandwidth damper may be stronger compared to the wide-band damper, but is locally limited to a frequency region close to the damping frequency of the small-bandwidth damper. In some embodiments, the broadband damper is a lanchester damper.
Fig. 3A is a schematic view of a carrier 320 of a magnetic levitation system according to various embodiments described herein. Most of the details of carrier 320 of fig. 3A correspond to the details of carrier 120 of fig. 1 and 2, so that reference can be made to the above description, which is not repeated here. In particular, the carrier 320 of fig. 3A is configured such that the carrier can be transported in a magnetic levitation system as depicted in fig. 1 and 2. In particular, as explained in further detail above, the carrier 320 is configured to interact with a base structure of the magnetic levitation system such that the carrier can be held at the base structure and movable relative to the base structure.
The carrier comprises a plurality of damping units 130, in particular three or more damping units tuned to different frequencies. In particular, the carrier 320 includes eight or more damping units or sixteen or more damping units. The damping unit may be tuned to eight or more different frequencies or even sixteen or more different frequencies. In some embodiments, each of the damping units is tuned to a different frequency than the other damping units. In other embodiments, some damping units are tuned to the same or substantially the same frequency. In the exemplary embodiment of fig. 3A, carrier 320 includes sixteen damping units tuned to sixteen different frequencies. For example, the carrier may have eight compartments containing sixteen damping units. In other embodiments, more or fewer damping units may be provided that may be partially tuned to the same frequency. Each damping unit may be provided in a separate compartment of the carrier, or alternatively, as schematically depicted in fig. 3A, two or more damping units may be received in one compartment of the carrier, respectively.
In the embodiment of fig. 3A, sixteen damping units are tuned to different frequencies within a critical frequency range from 50Hz to 250 Hz. In other various embodiments, at least some of the damping units may be tuned to frequencies outside of the critical frequency range.
In some embodiments, which may be combined with other embodiments described herein, the plurality of damping units comprises eight or more damping units tuned to eight or more different frequencies within a frequency range from 65Hz to 200Hz, in particular wherein the frequencies are distributed within the frequency range from 65Hz to 200Hz, e.g. substantially evenly distributed. For example, there may be at least one damping unit associated with each frequency sector having a width of 20Hz within the frequency range from 65Hz to 200 Hz. In the frequency range from 65Hz to 250Hz, the distance between two adjacent damping frequencies damped with the respective damping unit may be not more than 20 Hz.
In the exemplary embodiment depicted in FIG. 3A, tuning toSixteen damping units of lower damping frequency: f. ofa＝200Hz、fb＝186Hz、fc＝172Hz、fd＝160Hz、fe＝148Hz、ff＝138Hz、fg＝128Hz、fh＝118Hz、fi＝110Hz、fj＝88Hz、fk＝102Hz、fl＝95Hz、fm＝81Hz、fn＝76Hz、fo＝70Hz、fp65 Hz. Such a frequency distribution dispersed within the critical damping range is to be understood as an example. It is clear that a different number of damping units tuned to different frequencies may be provided. However, it is beneficial to provide a plurality of damping units having damping frequencies distributed within the critical frequency range. This "multi-damper concept" allows for a reliable damping of carrier vibrations, including carrier vibrations at natural frequencies within a critical frequency range, and does not require that the dampers be specifically tuned to the natural frequencies of the carrier within said range. Instead, by providing a plurality of dampers tuned to damping frequencies scattered over the frequency range to be damped, natural modes in said frequency range can also be reliably damped.
As depicted in FIG. 3A, the outermost damping unit is tuned to a higher frequency (here: f)a+b+c+d) The edge damping unit of (1). The centrally arranged damping unit is tuned to a lower frequency (here: f)e+f+g+h+i+j+k+i+m+n+o+p) The central damping unit of (1).
Fig. 3B is a graph showing the oscillating behavior of the carrier of fig. 3A, the carrier vibrating in different normal modes. The x-axis shows the carrier size in the transport direction T and the y-axis shows the vibration amplitude of different normal modes of the carrier in the holding direction V at different positions of the carrier. For example, there may be a normal mode of the carrier with a normal frequency of about f-85 Hz, the corresponding normal mode having a maximum vibration amplitude in the center of the carrier. The normal mode can be controlled by having a damping frequency fj(88Hz) and fmThe central damping unit of (81Hz) damps particularly efficiently. For example, there may be one normal mode of the carrier with a normal frequency of about f-200 Hz, the respective normal mode having the most frequent at the edge of the carrierLarge vibration amplitude. The normal mode can be controlled by having a damping frequency fa(200Hz) and fbThe (186Hz) edge damping unit damps particularly efficiently.
In some embodiments, two, four or more edge damping units may be provided in the front and rear portions of the carrier in the transport direction T, and two, four or more central damping units may be provided in the central portion of the carrier in the transport direction. In various implementations, the edge damping units may be tuned to a higher frequency than the central damping unit. This is because higher order natural modes with higher natural frequencies typically have the largest vibration amplitude at the carrier edge, at least when a frequency range from 50Hz to 300Hz is envisaged.
The carrier 320 may have a head portion 121 configured to interact with the active magnetic bearing of the base structure and a bottom portion 122 configured to hold the object, in particular the substrate 10. The head portion 121 and the bottom portion 122 may be connected to each other via a flexible connection 127. In some embodiments, the flexible connection comprises a flexible material, in particular an elastic material that allows relative movement of the head portion 121 with respect to the base portion 122. The carrier 320 having a number of movably connected carrier parts has a lower natural frequency than a rigid one-piece carrier with a corresponding weight. In some embodiments, a plurality of damping units 130 are arranged at the head portion of the carrier 120, for example in one or more linear arrays.
As depicted in fig. 3A, the carrier 320 may include a plurality of compartments 125, each compartment 125 housing two damping units of the plurality of damping units tuned to different frequencies. For example, the plurality of compartments 125 may be provided in a linear array, each compartment being shaped to accommodate two damping units. A space-saving damping unit arrangement can be provided. Fig. 4C schematically depicts two damping units configured to be received in one compartment 125.
The plurality of damping units used in the various embodiments described herein may be passive damping units, active damping units, and/or semi-active damping units. In particular, the plurality of damping units may be passive damping units, in particular mechanical passive damping units. Passive damping units, in particular passive vibration absorbers or tuned mass dampers, can also be referred to as "shock absorbers" (tilgers).
As used herein, a "passive damping unit" may be understood as a damping unit that does not include an active control. For example, the damping mass may be mounted on the carrier such that the motion induced by the damping mass relative to the carrier naturally damps the vibration of the carrier. In another embodiment, the damping mass may be mounted at the base structure via a spring element so as to be movable relative to the base structure. In other words, the passive damping unit does not comprise an actuator and/or a sensor. For example, the passive damping unit may comprise a damping mass movably connected to the carrier, e.g. via a spring element and/or an elastic material. The properties of the damping mass and the spring element may be set such that the damping effect of the damping unit has a maximum value at a specific damping frequency. For example, the weight of the damping mass and/or the spring constant of the spring element may be adapted to tune the damping unit to a predetermined damping frequency.
Fig. 4A is a schematic diagram illustrating the principle of operation of a passive damping unit, in particular a tuned mass damper 135, that may be used in the various embodiments described herein. At least some or all of the plurality of damping units 130 may be respectively configured as tuned mass dampers 135. Fig. 4A shows only one damping unit among the plurality of damping units 130. Other damping units may have a similar arrangement.
In some embodiments described herein, the plurality of damping units 130 are passive damping units, in particular shock absorbers, more in particular tuned mass dampers 135.
In some embodiments, tuned mass damper 135 includes a damping mass 145 and at least one spring element 141 that movably connects damping mass 145 to a carrier such that damping mass 145 can oscillate relative to the carrier. The at least one spring element 141 may comprise one or more leaf springs (leaf springs). Optionally, the tuned mass damper may further comprise a damping mechanism 142 for damping vibrations of the damping mass 145. Damping mechanism 142 may comprise a flexible material, for example, an elastomeric material such as a foam or viscous material, wherein damping mass 145 is at least partially embedded in the flexible material to dampen movement of damping mass 145. Alternatively or additionally, the damping mechanism 142 may include a magnet element (magnet element) configured to induce a current in the conductor element when the damping mass oscillates relative to the carrier. The induced current can be released as heat, so that the vibration energy of the oscillation damping block can be reduced quickly.
In some embodiments, as schematically depicted in fig. 4B, tuned mass damper 135 may be provided with a vacuum tight enclosure 146 that is insertable in compartment 125 provided at the carrier. Both the first damping unit 131 and the second damping unit 132 may be tuned mass dampers 135, the first damping unit 131 and the second damping unit 132 being received in respective compartments of the carrier. The damping unit can be replaced and rearranged quickly and easily at the carrier.
Fig. 4C is a schematic cross-sectional view illustrating two damping units in a common housing as used in various embodiments described herein. The damping unit is provided in a vacuum tight enclosure 146 which can be easily inserted into one compartment 125 of the carrier, so that a compact damping unit arrangement can be provided at the carrier.
The damping unit depicted in fig. 4C is a tuned mass damper 135 comprising a damping mass 145, at least one spring element 141 movably connecting the damping mass 145 to the carrier via a vacuum-tight enclosure 146, and a damping mechanism 142 for damping vibrations of the damping mass 145, respectively.
The damping mechanism 142 includes a magnet element that may be disposed at the damping mass 145 such that when the damping mass 145 vibrates, the magnet element moves relative to the vacuum sealed enclosure 146. The moving magnet elements induce currents in the conductor elements disposed at the vacuum-tight enclosure 146, so that the vibrational energy of the damping mass 145 can be dissipated as heat. Therefore, the vibration of the damping mass 145 can be damped more rapidly.
As schematically depicted in fig. 4C, two damping units may be arranged in a common housing, wherein the two damping units may be tuned to different frequencies. In particular, the characteristics of the at least one spring element 141 of the first damping unit may be different from the characteristics of the at least one spring element 141' of the second damping unit (depicted thicker for showing a greater spring constant). Alternatively, the damping masses and/or damping mechanisms of the two damping units may be different in order to adjust the damping frequency, bandwidth and/or damping ratio of the damping units.
According to another aspect described herein, a method of operating a magnetic levitation system is described, the magnetic levitation system comprising a base structure 110 and a carrier 120 movable relative to the base structure in a transport direction T.
Fig. 6 is a flow diagram illustrating a method of operating a magnetic levitation system according to various embodiments described herein. In block 610, the method comprises actively controlling at least one active magnetic bearing 112 to generate a magnetic holding force in a holding direction V for holding the carrier at the base structure, and damping vibrations of the carrier with a plurality of damping units 130 fixed to the carrier during active control. In particular, a plurality of normal modes of the carrier caused by the active control of the at least one active magnetic bearing can be damped by a plurality of damping units. The plurality of damping units includes a first damping unit 131 tuned to a first frequency or a first frequency range and a second damping unit 132 tuned to a second frequency or a second frequency range. Additional damping units may be provided. For example, the plurality of damping units may include three or more damping units, eight or more damping units, or even sixteen or more damping units fixed to the carrier.
Alternatively or additionally, the vibrations of the base structure may be damped with a (second) plurality of damping units fixed to the base structure. In particular, a plurality of normal modes of the base structure caused by active control of the at least one active magnetic bearing may be damped by the (second) plurality of damping units. The (second) plurality of damping units may comprise three or more damping units, eight or more damping units or even sixteen or more damping units fixed to the base structure, specifically tuned to different frequencies or frequency ranges.
In optional block 620, the carrier is transported along the base structure in the vacuum system with the drive unit while levitating the carrier with the at least one active magnetic bearing until the carrier reaches the processing position.
In optional block 630, the substrate 10 carried by the carrier is processed at a processing location. During processing, the carrier is not necessarily suspended by a magnetic suspension system. For example, the material is deposited on a substrate 10, the substrate 10 being in a processing position. In some embodiments, the substrate 10 may be a semiconductor wafer processed at a processing location, or the substrate may be a large area substrate for display manufacturing, and a deposition material, such as an organic material or a metal, may be deposited on the large area substrate at the processing location. The large area substrate may have a thickness of greater than 1m2Of size (e.g. 10 m)2Or larger, and/or the large area substrate may be a glass substrate.
In some embodiments, which can be combined with other embodiments described herein, damping the vibration of the carrier comprises damping a plurality of normal modes of the carrier with a plurality of damping units tuned to three or more different frequencies, in particular eight or more different frequencies, in particular in a frequency range between 50Hz and 250 Hz.
In some embodiments, which may be combined with the other various embodiments described herein, damping the vibration of the carrier further comprises damping at least one normal mode of the carrier, in particular a rigid body mode of the carrier, within a frequency range between 5Hz and 30Hz via a controller actively controlling the at least one active magnetic bearing.
According to a separate aspect described herein, damping vibrations of the carrier comprises damping a substantially normal mode, in particular a rigid body mode, of the carrier with at least one damping unit tuned to a frequency in a range between 5Hz and 30 Hz. In particular, the at least one damping unit may be tuned to a frequency in a range between 5Hz and 30Hz and may be configured to supplement the damping provided by the controller of the at least one active magnetic bearing in said frequency range.
In some embodiments, which may be combined with other embodiments described herein, damping the vibration of the carrier comprises damping at least one carrier vibration with a lateral vibration damping unit oriented to damp the carrier vibration in a lateral direction perpendicular to the holding direction V, in particular wherein the lateral vibration damping unit is tuned to a frequency in a range between 5Hz and 100 Hz.
In some embodiments, which can be combined with the other embodiments described herein, damping the vibration of the carrier comprises damping at least one normal mode of the carrier in a frequency range between 20Hz and 60Hz with a broadband damper, in particular with a damping unit tuned to a frequency range from 40Hz to 50 Hz.
In some embodiments, which can be combined with other embodiments described herein, the vibration of the carrier is damped with a plurality of tuned mass dampers tuned to eight or more different frequencies within a frequency range between 50Hz and 250 Hz. The tuned mass damper may be oriented to damp vertical carrier vibrations.
Embodiments described herein relate in particular to magnetic levitation systems configured to transport a carrier in a substantially vertical orientation. As used herein, "substantially vertical" may be understood as the carrier orientation being perfectly vertical or having a deviation of 10 ° or less from vertical. The carrier can thus be transported with a magnetic levitation system while carrying the substantially vertically oriented substrate. In other various embodiments, the magnetic levitation system can be configured to transport differently oriented carriers, such as carriers that are oriented substantially horizontally during transport.
The above description describes in detail the damping of carrier vibrations with a plurality of damping units arranged at the carrier. It is to be noted, however, that the at least one magnetic bearing may cause vibrations of not only the carrier but also of the base structure. The base structure may be a fixed rail or frame along which the carrier can be moved with a magnetic levitation system. Thus, in some embodiments, a plurality of damping units may be arranged at the base structure such that vibrations of the base structure can be damped with the plurality of damping units. In further embodiments, a first plurality of damping units may be provided at the carrier for damping carrier vibrations and a second plurality of damping units may be provided at the base structure for damping vibrations of the base structure.
The plurality of damping units disposed at the base structure and configured to damp vibrations of the base structure may be similar or identical to the plurality of damping units disposed at the carrier as described in detail herein. In particular, the critical damping range of the base structure may substantially correspond to the critical damping range of the base structure, and a plurality of damping units may be provided at the base structure, the plurality of damping units being tuned to different frequencies within the critical damping range. It is to be understood that any details of the plurality of damping units provided at the carrier as described herein may be applied to the plurality of damping units provided at the base structure.
While the foregoing is directed to embodiments of the present disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims (19)

1. A magnetic levitation system (100) comprising
A base structure (110);
a carrier (120) movable in a transport direction (T) relative to the base structure (110); and
at least one active magnetic bearing (112) configured to generate a magnetic holding force acting in a holding direction (V) for holding the carrier (120) at the base structure (110),
wherein at least one of the carrier and the base structure comprises a plurality of damping units (130), a first damping unit (131) of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit (132) of the plurality of damping units being tuned to a second frequency or a second frequency range.
2. Magnetic levitation system as claimed in claim 1, wherein the first damping unit (131) and the second damping unit (132) are tuned to different natural frequencies of the carrier (120), in particular different natural frequencies in a frequency range between 50Hz and 250 Hz.
3. Magnetic levitation system as claimed in claim 1 or 2, wherein the first damping unit (131) and the second damping unit (132) are oriented to damp vibrations in the holding direction (V).
4. The magnetic levitation system as claimed in any of claims 1 to 3, wherein the plurality of damping units (130) comprises three or more damping units, in particular eight or more damping units, the plurality of damping units (130) being tuned to three or more different frequencies, in particular eight or more different frequencies.
5. The magnetic levitation system as claimed in claim 4, wherein the plurality of damping units (130) comprises eight or more damping units tuned to eight or more different frequencies within a frequency range from 65Hz to 200Hz, in particular wherein the 8 or more different frequencies are distributed within the frequency range from 65Hz to 200 Hz.
6. The magnetic levitation system as claimed in any of claims 1 to 5, wherein the carrier (120) comprises a head portion (121) configured to interact with the at least one active magnetic bearing (112), wherein three or more damping units of the plurality of damping units (130) are arranged in a linear array at the head portion (121).
7. Magnetic levitation system as claimed in any of claims 1 to 6, wherein the plurality of damping units (130) comprises at least one central damping unit (133) arranged in a central part of the carrier (120) and at least one edge damping unit (134) arranged in a front or rear part of the carrier (120) in the transport direction (T), wherein the edge damping unit (134) is tuned to a higher frequency than the central damping unit (133).
8. Magnetic levitation system as claimed in any one of claims 1 to 7, wherein the carrier (120) comprises a plurality of compartments (125), each compartment housing two or more of the plurality of damping units (130) tuned to different frequencies.
9. Magnetic levitation system as claimed in any of claims 1-8, wherein the plurality of damping units (130) are passive damping units, in particular shock absorbers, more particularly tuned mass dampers (135) mounted at the carrier (120) and/or the base structure.
10. Magnetic levitation system as claimed in any one of claims 1 to 9, wherein the plurality of damping units (130) each comprise:
-a damping mass (145);
-at least one spring element (141) movably connecting the damping mass (145) to the carrier (120) or the base structure; and
-a damping mechanism (142) for damping vibrations of the damping mass (145).
11. The magnetic suspension system of claim 10, wherein the damping mechanism comprises a magnet element configured to induce a current in a conductor element.
12. The magnetic levitation system as recited in any one of claims 1-11, wherein the plurality of damping units (130) comprises at least one damping unit tuned to at least one of:
a fundamental natural frequency of the carrier; and
a frequency in the range between 5Hz and 30 Hz.
13. Magnetic levitation system as claimed in any one of claims 1 to 12, wherein the plurality of damping units comprises at least one lateral vibration damping unit (136) oriented to damp carrier vibrations in a second direction different from the holding direction (V), in particular substantially perpendicular to the holding direction (V).
14. Magnetic levitation system as claimed in claim 13, wherein the at least one lateral vibration damping unit (136) is arranged at a bottom portion (122) of the carrier.
15. Magnetic levitation system as claimed in any of claims 1-14, wherein the plurality of damping units (130) comprises at least one broadband damper, in particular providing a damping ratio of at least 0.1 in the frequency range from 40Hz to 50 Hz.
16. A carrier (120) for a magnetic levitation system, the carrier being configured to interact with a base structure (110) of the magnetic levitation system such that the carrier is held at and movable relative to the base structure, the carrier comprising:
a plurality of damping units (130), a first damping unit (131) of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit (132) of the plurality of damping units being tuned to a second frequency or a second frequency range.
17. A method of operating a magnetic levitation system (100) comprising a base structure (110) and a carrier (120) movable relative to the base structure in a transport direction (T), the method comprising:
actively controlling at least one active magnetic bearing (112) to generate a magnetic holding force to hold a carrier at the base structure; and
damping vibrations of at least one of the carrier and the base structure with a plurality of damping units (130) fixed to at least one of the carrier and the base structure, a first damping unit (131) of the plurality of damping units being tuned to a first frequency or a first frequency range, and a second damping unit (132) of the plurality of damping units being tuned to a second frequency or a second frequency range.
18. The method of claim 17, wherein the plurality of damping units are secured to the carrier and damp vibrations comprises:
damping a plurality of normal modes of the carrier with the plurality of damping units (130) tuned to three or more different frequencies in a frequency range between 50Hz and 250Hz,
damping at least one normal mode of the carrier in a frequency range between 5Hz and 30Hz via a controller actively controlling the at least one active magnetic bearing,
damping at least one rigid body mode of the carrier with a damping unit tuned to a frequency in a frequency range between 5Hz and 30Hz,
damping at least one normal mode of the carrier in a frequency range between 20Hz and 60Hz with a broadband damper, and/or
Damping at least one carrier vibration with a lateral vibration damping unit oriented to damp carrier vibrations in a lateral direction perpendicular to the holding direction, in particular wherein the lateral vibration damping unit is tuned to a frequency in a range between 5Hz and 100 Hz.
19. The method of claim 17 or 18, wherein the vibration is damped with a plurality of tuned mass dampers tuned to eight or more different frequencies distributed over a frequency range between 50Hz and 250 Hz.
CN201980093452.XA 2019-03-01 2019-03-01 Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system Pending CN113574650A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/EP2019/055171 WO2020177842A1 (en) 2019-03-01 2019-03-01 Magnetic levitation system, carrier for a magnetic levitation system, and method of operating a magnetic levitation system

Publications (1)

Publication Number Publication Date
CN113574650A true CN113574650A (en) 2021-10-29

Family

ID=65729313

Family Applications (1)

Application Number Title Priority Date Filing Date
CN201980093452.XA Pending CN113574650A (en) 2019-03-01 2019-03-01 Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system

Country Status (3)

Country Link
KR (1) KR20210134015A (en)
CN (1) CN113574650A (en)
WO (1) WO2020177842A1 (en)

Family Cites Families (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE4441512C2 (en) * 1993-11-22 1996-03-28 Ebara Corp positioning
JPH11154698A (en) * 1997-11-21 1999-06-08 Nikon Corp Table supporting apparatus
KR101409524B1 (en) * 2007-05-28 2014-06-20 엘지디스플레이 주식회사 Apparatus for transferring substrates
US8164737B2 (en) * 2007-10-23 2012-04-24 Asml Netherlands B.V. Lithographic apparatus having an active damping subassembly
KR101049221B1 (en) * 2009-11-17 2011-07-13 한국기계연구원 Magnetic Levitation Carrier Using Linear Induction Motor
TWI589796B (en) * 2013-03-28 2017-07-01 克萊譚克公司 Hybrid vibration isolation systems for metrology platforms
DE102014005547B4 (en) * 2014-04-16 2016-09-15 Mecatronix Ag Device and method for holding, positioning and / or moving an object
DE102017002542A1 (en) * 2017-03-16 2018-09-20 Applied Materials, Inc. (N.D.Ges.D. Staates Delaware) Device for holding, positioning and / or moving an object
CN109643680B (en) * 2017-07-21 2023-03-28 应用材料公司 Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system

Also Published As

Publication number Publication date
WO2020177842A1 (en) 2020-09-10
KR20210134015A (en) 2021-11-08

Similar Documents

Publication Publication Date Title
KR102126341B1 (en) Apparatus for at least one of holding, positioning, and moving an object and a method of operating the apparatus for at least one of holding, positioning, and moving an object
US10267373B2 (en) Characteristic value variable dynamic vibration absorber and characteristic value variable vibration isolator
Yan et al. A state-of-the-art review on low-frequency nonlinear vibration isolation with electromagnetic mechanisms
US9745138B2 (en) Vibration device, article conveyance device, and article sorting device
CN109643680B (en) Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system
JP5227449B2 (en) Vibrating transfer device
CN111684173B (en) Magnetic levitation system and method for non-contact carrier transportation in vacuum environment
JP2019509440A (en) Active inertia damper system and method
CN108602167B (en) Suppression of machine vibrations
CN113574650A (en) Magnetic levitation system, carrier for a magnetic levitation system and method for operating a magnetic levitation system
RU172016U1 (en) Multi-axis active anti-vibration platform
JP7378765B2 (en) Machine tool vibration damping device
KR101084987B1 (en) Hybrid electromagnetic actuator against microvibration
JP5996895B2 (en) Vibrating parts conveyor
Hoque et al. A 3-DOF modular vibration isolation system using zero-power magnetic suspension with adjustable negative stiffness
US11059499B2 (en) Suspension system for levitation vehicles
KR20070070334A (en) Electromagnetic vibration actuator
JP2001165240A (en) Air spring with built-in superconductive actuator
JP6267940B2 (en) Vibrating parts conveyor
CN116292745A (en) Electromagnetic self-adjusting power anti-resonance vibration isolation system
Hoque et al. A Model-Based Controller for a Vibration Isolation System with Weight Support Springs
JPH06333733A (en) Damper for magnetic levitation train
JPS63130946A (en) Vibration isolator

Legal Events

Date Code Title Description
PB01 Publication
PB01 Publication
SE01 Entry into force of request for substantive examination
SE01 Entry into force of request for substantive examination