WO2020126040A1

WO2020126040A1 - Magnetic levitation system, carrier for a magnetic levitation system, vacuum system, and method of transporting a carrier

Info

Publication number: WO2020126040A1
Application number: PCT/EP2018/086639
Authority: WO
Inventors: Christian Wolfgang Ehmann; Ralph Lindenberg
Original assignee: Applied Materials, Inc.
Priority date: 2018-12-21
Filing date: 2018-12-21
Publication date: 2020-06-25
Also published as: CN113169105A; KR20210104134A

Abstract

A magnetic levitation system (100) for transporting a carrier (10) in a transport direction (T) is described. The magnetic levitation system includes one or more magnetic levitation units (120, 220) for holding a carrier (10) in a carrier transportation space (15), and a drive unit (130) for moving the carrier (10) in a transport direction (T), the drive unit (130) comprising a stator part (132) of an asynchronous linear motor being arranged laterally with respect to the carrier transportation space (15). Further, a carrier for a magnetic levitation system, as well as a method of transporting a carrier, are described.

Description

MAGNETIC LEVITATION SYSTEM, CARRIER FOR A MAGNETIC LEVITATION SYSTEM, VACUUM SYSTEM, AND METHOD OF

TRANSPORTING A CARRIER

TECHNICAL FIELD [0001] Embodiments of the present disclosure relate to apparatuses and methods for transporting carriers, particularly carriers for carrying large area substrates during processing. More specifically, embodiments of the present disclosure relate to apparatuses and methods for transporting carriers with a magnetic levitation system, employable in vacuum systems for vertical substrate processing. In particular, embodiments of the present disclosure relate to magnetic levitation systems, carriers for magnetic levitation systems, vacuum systems, and methods for carrier transportation in vacuum systems.

BACKGROUND

[0002] Techniques for layer deposition on a substrate include, for example, sputter deposition, physical vapor deposition (PVD), chemical vapor deposition (CVD) and thermal evaporation. Coated substrates can be used in several applications and in several technical fields. For instance, coated substrates may be used in the field of display devices. Display devices can be used for the manufacture of television screens, computer monitors, mobile phones, other hand-held devices, and the like for displaying information. Typically, displays are produced by coating a substrate with a stack of layers of different materials.

[0003] In order to deposit a layer stack, an in-line arrangement of processing modules can be used. An in-line processing system includes a plurality of processing modules, such as deposition modules and optionally further processing modules, e.g., cleaning modules and/or etching modules, wherein processing aspects are subsequently conducted in the processing modules such that a plurality of substrates can continuously or quasi-continuously be processed in the in-line processing system.

[0004] The substrate may be carried by a carrier, i.e. a carrying device for carrying the substrate in the vacuum system. The carrier carrying the substrate is typically transported through the vacuum system using a transport system. The transport system may be a magnetic levitation system, such that the carrier can be transported contactlessly or essentially contactlessly. The transport system may be configured for conveying the carrier having the substrate positioned thereon along one or more transport paths in the vacuum system, e.g. from one processing device to another processing device.

[0005] An accurate and smooth transportation of the carriers through the vacuum system is challenging. For instance, particle generation due to wear of moving parts can cause a deterioration in the manufacturing process. Accordingly, there is a demand for transportation of carriers in processing systems with reduced or minimized particle generation. Further challenges are, for example, to provide robust carrier transport systems for high temperature vacuum environments at low costs.

[0006] Accordingly, providing improved apparatuses and methods for transporting carriers, and providing improved vacuum processing systems, which overcome at least some of the problems mentioned above, would be beneficial. SUMMARY

[0007] In light of the above, a magnetic levitation system for transporting a carrier, a carrier for a magnetic levitation system, a vacuum system including a magnetic levitation system, and a method of transporting a carrier in a vacuum chamber are provided according to the independent claims. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0008] According to an aspect of the present disclosure, a magnetic levitation system for transporting a carrier in a transport direction is provided. The magnetic levitation system includes one or more magnetic levitation units for holding a carrier in a carrier transportation space, and a drive unit for moving the carrier in a transport direction, the drive unit comprising a stator part of an asynchronous linear motor being arranged laterally with respect to the carrier transportation space.

[0009] According to an aspect of the present disclosure, a magnetic levitation system for transporting a carrier in a transport direction is provided. The magnetic levitation system includes one or more magnetic levitation units for holding a carrier, and a drive unit for moving the carrier in the transport direction, the drive unit comprising a stator part of an asynchronous linear motor configured to interact with a mover part of the asynchronous linear motor arranged at a lateral face of the carrier.

[0010] According to another aspect of the present disclosure, a carrier for a magnetic levitation system is provided. The carrier includes a holding device for carrying an object, one or more magnet units configured to magnetically interact with one or more magnetic levitation units of the magnetic levitation system for levitating the carrier; and a mover part of an asynchronous linear motor for moving the carrier in a transport direction, the mover part being arranged at a lateral face of the carrier and configured to interact with a stator part of the asynchronous linear motor.

[0011] According to another aspect of the present disclosure, a vacuum system is provided. The vacuum system includes a vacuum chamber, a carrier for carrying an object, particularly a large-area substrate, in the vacuum chamber, and a magnetic levitation system for transporting the carrier in a transport direction. The magnetic levitation system includes one or more magnetic levitation units for holding the carrier in a carrier transportation space in the vacuum chamber, and a drive unit for moving the carrier in the transport direction, the drive unit comprising a stator part of an asynchronous linear motor being arranged laterally with respect to the carrier transportation space. The carrier includes a mover part of the asynchronous linear motor being arranged at a lateral face of the carrier.

[0012] According to another aspect described herein, a method of transporting a carrier in a vacuum chamber in a transport direction is provided. The method includes levitating a carrier in a carrier transportation space in the vacuum chamber with one or more magnetic levitation units of a magnetic levitation system, and moving the carrier in the transport direction with a drive unit, the drive unit including a stator part of an asynchronous linear motor which is arranged laterally with respect to the carrier and interacts with a mover part provided at a lateral face of the carrier. [0013] According to another aspect of the present disclosure, an apparatus for transporting of a carrier in a vacuum chamber is provided. The apparatus includes a first magnetic levitation system provided along a first transport path and a second magnetic levitation system provided along a second transport path. The first magnetic levitation system and the second magnetic levitation system are configured according to any of the embodiments described herein, respectively. Further, the apparatus includes a path switch assembly for moving the carrier away from the first transport path in a lateral direction to at least one of the second transport path and a processing position horizontally offset from the first transport path and the second transport path. [0014] According to another aspect of the present disclosure, a processing system for vertically processing a substrate is provided. The processing system includes at least one vacuum system according to any of the embodiments described herein, wherein the vacuum chamber of the vacuum system houses a processing device, particularly a deposition source such as an evaporation source for depositing a layer on a substrate carried by a carrier.

[0015] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the disclosure are also directed at methods for operating the described apparatus. The methods for operating the described apparatus include method aspects for carrying out every function of the apparatus. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] 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 accompanying drawings relate to embodiments of the disclosure and are described in the following:

FIG. 1 shows a schematic sectional view of a magnetic levitation system and of a carrier according to embodiments described herein;

FIG. 2A shows a schematic sectional view of a magnetic levitation system and of a carrier according to embodiments described herein;

FIG. 2B shows a schematic side view of the magnetic levitation system and of the carrier of FIG. 2A; and

FIG. 3 shows a flowchart for illustrating a method of transporting a carrier according to embodiments described herein. DETAILED DESCRIPTION OF EMBODIMENTS

[0017] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, same reference numbers refer to same components. Only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, 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. It is intended that the description includes such modifications and variations. [0018] With exemplary reference to FIG. 1, a magnetic levitation system 100 for transporting a carrier 10 in a transport direction T according to the present disclosure is described. The transport direction T is perpendicular to the paper plane of FIG. 1. The transport direction T is typically an essentially horizontal direction (horizontal +/-10°).

[0019] The magnetic levitation system 100 includes one or more magnetic levitation units 120 for holding the carrier 10 in a carrier transportation space 15. The carrier transportation space 15 may be understood as a zone where the carrier 10 is arranged during the transport of the carrier in the transportation direction T along a transport path.

[0020] In particular, as is exemplarily shown in FIG. 1, the carrier transportation space 15 can be a vertical carrier transportation space having a height H extending in a vertical direction and a width W extending in a horizontal direction. For instance, the aspect ratio of H/W can be H/W > 5, particularly H/W > 10. The magnetic levitation system may be configured to transport an essentially vertically oriented carrier. In particular, the substrate that is carried by the carrier may be essentially vertically oriented during the transport.

[0021] As is exemplarily shown in FIG. 1, the one or more magnetic levitation units 120 can be arranged above the carrier transportation space 15. In particular, the one or more magnetic levitation units 120 may be attached to an outside of an upper chamber wall of a vacuum chamber 101. In the embodiment of FIG. 1, the one or more magnetic levitation units 120 may include one or more active magnetic bearings 121 with actuators arranged above the carrier transportation space 15, particularly outside the vacuum chamber 101. More specifically, the one or more magnetic levitation units 120 may include actively controlled magnetic bearings that are controlled depending on a current position of the carrier 10 which can be measuring with one or more gap sensors (not shown in FIG. 1). In other embodiments, the one or more magnetic levitation units 120 can be passive magnetic units, e.g. including one or more permanent levitation magnets, which may not be actively controlled.

[0022] The magnetic levitation system 100 of embodiments described herein further includes a drive unit 130 for moving the carrier 10 in the transport direction T. The drive unit 130 includes a stator part 132 of an asynchronous linear motor being arranged laterally with respect to the carrier transportation space 15. In particular, the stator part 132 of the asynchronous linear motor may be arranged such as to interact with a mover part 182 of the asynchronous linear motor being arranged at a lateral face 11 of the carrier.

[0023] In particular, the stator part 132 of the asynchronous linear motor may be configured to interact with a mover part 182 of the asynchronous linear motor that is provided at a lateral face 11 of the carrier, the lateral face extending essentially vertically during the transport of the carrier. In some implementations, the stator part 132 of the asynchronous linear motor is laterally arranged at a lower portion 16 of the carrier transportation space 15. In some implementations, the mover part 182 of the asynchronous linear motor is arranged at a lower portion of the lateral face 11 of the carrier such as to face toward the stator part 132 when the carrier is moved past the stator part 132. The stator part 132 of the asynchronous linear motor may be arranged at or fixed at a base 20 that extends along the transport path of the carrier.

[0024] “Laterally with respect to the carrier transportation space” as used herein is meant to distinguish from positions“above” or“below” the carrier transportation space. In particular, the stator part 132 of the asynchronous linear motor is arranged laterally next to the carrier, facing toward the mover part 182 of the asynchronous linear motor, when the carrier is moving past the stator part 132, such that a horizontal sectional place intersects both the stator part 132 and the mover part 182. The minimum distance between the mover part 182 and the stator part 132 during the carrier transport may be 1 cm or less in the lateral direction L. The lateral direction L as used herein is meant to designate a horizontal direction transverse to the transport direction T in which the driving force of the drive unit 130 is directed. Accordingly, a stator part 132 being arranged“laterally” with respect to the carrier transportation space specifies that the stator part 132 and the carrier transportation space 15 are at least partially arranged at the same vertical level, and that the stator part 132 and the mover part 182 are facing each other in the lateral direction L.

[0025] The “stator part” of the asynchronous linear motor as used herein designates the stationary part of the asynchronous linear motor that is fixed to a base 20 of the magnetic levitation system 100. In other words, the“stator part” may be understood as the stator of the asynchronous linear motor that is stationary with respect to the moving armature. The“mover part” of the asynchronous linear motor as used herein designates the part of the asynchronous linear motor that is moved relative to the stator part and that is provided at the movable carrier. In other words, the“mover part” may be understood as the moving armature or as the rotor of the asynchronous linear motor that is linearly moved with respect to the stator.

[0026] Synchronous linear motors typically work in a so-called “feedback mode”. A position sensor, e.g. a Hall sensor, may be provided, which can measure the carrier position on a magnet track of the motor. The sensor signal is used for the feedback control of the synchronous motor. However, the sensor signal may not be very reliable, leading to vibrations or even errors of the drive system. The downtime of the system may increase, and there may be a risk of substrate breakage, especially when the carriers have a comparably high temperature, such as during sputtering.

[0027] As compared to synchronous motors, asynchronous motors can work in an“open-loop mode” in which no position sensor for a feedback control of the motor is needed. Accordingly, it may not be necessary to provide an expensive and sensitive magnet track for allowing a continuous position measurement. Since the asynchronous motor can work in the open-loop mode, expensive and fault-prone control equipment and sensors can be dispensed with. Further, the uptime of the system can be increased according to embodiments described herein, which use an asynchronous linear motor for the carrier movement.

[0028] According to some embodiments described herein, the asynchronous linear motor is configured for an open-loop operation. In particular, the asynchronous linear motor may (at least temporarily) operate without an input signal designating the current carrier position.

[0029] Further, synchronous linear motors are typically provided as iron-core linear motors. Iron-core motors generate, in addition to the driving force that acts in the transport direction T, an attractive force that acts between the stator and the rotor and may pull the rotor toward the stator. The attractive force of typical iron-core synchronous linear motors may be in the range from 200 N to 1000 N. The attractive force between the mover part and the stator part may be undesired in a magnetic levitation system because magnets behave like soft springs, and the motor attractive force may generate a motion perpendicular to the transport direction, leading to vibrations of the carrier than cannot be easily compensated with magnets of the system.

[0030] As compared to synchronous linear motors, asynchronous linear motors typically do not have permanent magnets and/or coils with iron cores at both the stator part (stator) and at the mover part (rotor). Rather, the mover part of an asynchronous linear motor does typically not include any permanent magnets. Accordingly, attractive forces between the stator part and the mover part are small or even zero, such that no additional forces need to be compensated with magnets of the magnetic levitation system, and the risk of carrier vibrations is reduced. In particular, the asynchronous linear motor of embodiments described herein may be an induction motor which generates the drive force of the carrier in the transport direction with Eddy currents that are induced in the mover part of the carrier.

[0031] According to embodiments described herein, the mover part of the asynchronous linear motor does not include permanent magnets and/or does not include coils with iron cores, which can reduce or avoid an attraction force between the mover part and the stator part of the motor.

[0032] The“drive unit” as used herein can be understood as a unit configured for moving the carrier in the transport direction T. In particular, the drive unit 130 as described herein may be configured to generate a driving force acting on the carrier in the transport direction T. The drive unit 130 includes the stator part 132 of the asynchronous linear motor. In embodiments, the stator part 132 comprises a plurality of coil units arranged laterally with respect to the carrier transportation space. The coil units may be configured to generate a magnetic field for inducing currents in the mover part 182 of the asynchronous linear motor provided at the lateral face 11 of the carrier.

[0033] In some embodiments, the stator part 132 may include stator units including three-phase coils which may (optionally) be wound on a core. The three- phase coils may be connected to a three-phase AC power supply. Thus, a shifting alternating three-phase magnetic field can be generated by the stator part 132 on the mover part 182, wherein the mover part 182 may include a simple conductive plate. The driving force applied to the mover part may act in the transport direction T due to the interaction between the magnetic field generated by the induced current and the magnetic field generated by the stator part. As a result, the carrier can be moved in the transport direction T. In some embodiments, several stators may be provided along the transport path of the carrier. In some implementations, several stator parts may be provided along the transport path of the carriers at predetermined distances with respect to each other, such that a transport along the transport path is enabled. The transport path can extend over 5 m or more, particularly 10 m or more.

[0034] In some embodiments, which can be combined with other embodiments described herein, the mover part 182 of the asynchronous linear motor comprises a conductive material portion extending in the transport direction T along the lateral face 11 of the carrier 10. For example, the conductive material portion may be an aluminum portion or a portion made of another conductive metal, such that currents can be induced in the conductive material portion of the carrier 10 by the stator part 132.

[0035] In particular, the mover part 182 of the asynchronous linear motor may include an aluminum plate or aluminum trace being provided at the lateral face 11 of the carrier 10. Alternatively, another conductive material, such as copper or another metal, can be used. The plate or trace may extend at the lateral face 11 of the carrier 10 from a first end of the carrier, e.g. the leading end of the carrier, to a second end of the carrier, e.g. the trailing end of the carrier. During transport, the conductive plate or trace may extend on the lateral face 11 of the carrier along the transport direction T. Specifically, the mover part 182 may be provided as a conductor plate provided on the lateral face 11 of the carrier 10. No complex coils or windings may be needed at the carrier, and a conductive plate may be sufficient for moving the carrier with the drive unit 130, the drive unit 130 being provided as the stator part 132 of an asynchronous linear motor. [0036] In some conventional magnetic levitation systems, a drive unit for moving a carrier is provided below or above a carrier transportation space, and the magnetic levitation units of the magnetic levitation system compensate potential forces that are generated between the stator part and the mover part of the drive unit. On the other hand, according to embodiments described herein, the drive unit is not arranged above or below the carrier transportation space, such that no forces are generated in the vertical direction by a drive unit. Accordingly, a smooth levitation of the carrier can be ensured, and the control of the magnetic levitation units can be facilitated. Providing the drive unit 130 laterally with respect to the carrier transportation space 15 is particularly beneficial in the case of a magnetic levitation system using passive magnetic levitation units, as is depicted in FIG. 2 A. The reason is that the drive unit does not apply substantial forces in the vertical direction, such that a smooth levitation of the carrier with less vibration and a reduced risk of failure can be provided.

[0037] According to embodiments described herein, the stator part 132 is provided laterally with respect to the carrier transportation space 15. In this case, any forces that may be generated between the stator part 132 and the mover part 182 in the lateral direction L can be compensated by a magnetic side stabilization device 140 acting in the lateral direction L.

[0038] According to embodiments, which may be combined with other embodiments described herein, the magnetic levitation system includes a magnetic side stabilization device 140 configured to stabilize the carrier in a lateral direction L perpendicular to the transport direction L. In some implementations, the magnetic side stabilization device 140 may be a passive stabilization device including at least one first permanent magnet 141, particularly including permanent magnets only. The at least one first permanent magnet 141 may magnetically interact with at least one second permanent magnet 142 which is provided at the carrier 10.

[0039] In some implementations, the magnetic side stabilization device 140 is not an actively controlled device, but the magnetic side stabilization device 140 may stabilize the carrier 10 passively at a predetermined position in the lateral direction L. For example, the carrier can be passively stabilized via attractive or repulsive magnetic forces acting on the carrier and holding the carrier in an equilibrium position, as is depicted in FIG. 1. The magnetic side stabilization device 140 may apply a restoring force on the carrier 10 in the lateral direction L in the case of a lateral displacement of the carrier from the equilibrium position, such that the carrier can be stabilized at the predetermined lateral position. The restoring force pushes or pulls the carrier back to the predetermined lateral position. The lateral direction L may be a direction essentially perpendicular to the extension direction of the transport track of the magnetic levitation system 100.

[0040] The magnetic side stabilization device 140 may include a guiding rail extending along the transport path of the magnetic levitation system. At least one first permanent magnet 141 may be provided at the guiding rail in such a way that the carrier 10 which is transported along the transport path can be stabilized at the predetermined lateral position. The at least one first permanent magnet 141 may magnetically interact with at least one second permanent magnet 142 arranged at the carrier. The at least one first permanent magnet 141 may have a first north pole and a first south pole (shaded differently in FIG. 1), and the at least one second permanent magnet 142 may have a second north pole and a second south pole (shaded differently in FIG. 1). The at least one first permanent magnet 141 and the at least one second permanent magnet 142 may be arranged one above the other such that a lateral displacement of the carrier both toward the left side and toward the right side in FIG. 1 may cause a restoring force exerted on the carrier. The restoring force can urge the carrier back toward the equilibrium position that is depicted in FIG. 1. In other words, the side stabilization device may be a bidirectionally acting side stabilization device.

[0041] As already mentioned above, the asynchronous linear motor of the magnetic levitation system described herein may only generate a small or negligible attraction force between the stator part 132 and the mover part 182 in the lateral direction L, i.e. between the carrier 10 and the base 20. Since the stator part 132 is arranged laterally with respect to the carrier transportation space 15, only a small or negligible attraction force between the carrier and the base is caused by the drive unit in the lateral direction L. Accordingly, a magnetic side stabilization device 140 including permanent magnets only can be used for stabilizing the carrier in the lateral direction L, and a reliable side stabilization can be provided.

[0042] As is further exemplarily depicted in FIG. 1, the present disclosure relates to a carrier 10 for a magnetic levitation system, which includes a holding device for carrying an object. The carrier further includes one or more magnet units 181 configured to magnetically interact with the one or more magnetic levitation units of the magnetic levitation system 100 for levitating the carrier 10 in the carrier transportation space 15. The carrier 10 further includes the mover part 182 of the asynchronous linear motor that is configured for moving the carrier in the transport direction T. The mover part 182 is provided at a lateral face 11 of the carrier and configured to interact with the stator part 132 of the asynchronous linear motor for moving the carrier in the transport direction T.

[0043] In some implementations, the mover part 182 is arranged at a lower portion of the lateral face 11 of the carrier, particularly in the lower half of the carrier or in an end portion of the carrier at a distance of 30 cm or less from the bottom end of the carrier.

[0044] The holding device may be configured to hold an object, particularly a substrate, at an upper portion of the lateral face 11. The upper portion is located above the lower portion of the lateral face 11 during transport. During the transport of the carrier with the magnetic levitation system, the lateral face 11 may be essentially vertically oriented.“Essentially vertically” as used herein may encompass a deviation of 10° or less from an exactly vertical orientation of the lateral face.

[0045] FIG. 2A is a schematic sectional view of a magnetic levitation system 200 configured for levitating a carrier 10’ according to embodiments described herein. FIG. 2B is a schematic side view of the magnetic levitation system 200 and of the carrier 10’ of FIG. 2A. The magnetic levitation system 200 and the carrier 10’ are similar to the magnetic levitation system 100 and the carrier 10 of FIG. 1, such that reference can be made to the above explanations, which are not repeated here. The differences will be further explained in the following paragraphs. [0046] The magnetic levitation system 200 according to embodiments described herein includes one or more magnetic levitation units 220 for holding the carrier 10’ and a drive unit 130 for moving the carrier 10’ in a transport direction T. The drive unit 130 includes a stator part 132 of an asynchronous linear motor adapted to interact with a mover part 182 of the asynchronous linear motor arranged at a lateral face 11 of the carrier. In particular, the stator part 132 of the asynchronous linear motor is arranged laterally with respect to a carrier transportation space 15, the carrier being held in the carrier transportation space 15 contactlessly or essentially contactlessly by the magnetic levitation units 220. [0047] The drive unit 130 essentially corresponds to the drive unit of the magnetic levitation system of FIG. 1, such that reference can be made to the above explanations, which are not repeated here. Further, the stator part 132 and the mover part 182 of the asynchronous linear motor essentially correspond to the respective components described above. [0048] As is schematically depicted in FIG. 2A, the stator part 132 is provided laterally with respect to a lower portion 16 of the carrier transportation space and is configured to interact with the mover part 182 that is provided laterally at a lower portion of the carrier. In particular, the mover part 182 is provided at the lower half of the carrier, particularly in an end portion adjacent to the lower end of the carrier, the distance to the lower carrier end being 30 cm or less.

[0049] As is visible from the side view of FIG. 2B, the mover part 182 of the asynchronous linear motor may include a conductive material portion extending along the lateral face 11 of the carrier, particularly in the transport direction T during the transport of the carrier. The conductive material portion is shown as a shaded portion in FIG. 2B which extends at the lateral face 11 of the carrier from a front end of the carrier to a rear end of the carrier. In some embodiments, the conductive material portion may be comprised of an aluminum plate provided at the lateral face 11 of the carrier. The aluminum plate may extend in the transport direction T, particularly from a leading edge to a trailing edge of the carrier. [0050] The magnetic levitation units 220 of the magnetic levitation system 200 may be passive units including permanent levitation magnets 221 configured to apply a lifting force on the carrier. In particular, the carrier 10’ may be lifted and be held in a floating state with purely passive levitation units, which may not be actively controlled. The passive levitation units may include or be comprised of permanent levitation magnets 221. In some embodiments, the magnetic levitation units 220 may be arranged laterally with respect to the carrier transportation space 15, i.e. not above or below the carrier during transport, but at a lateral side thereof.

[0051] One or more magnet units 181 configured to magnetically interact with the permanent levitation magnets 221 of the magnetic levitation system 200 may be provided at the carrier 10’. The one or more magnet units 181 may include or be permanent magnets. The permanent levitation magnets 221 of the magnetic levitation system 200 and the one or more magnet units 181 of the carrier may face each other such that the resulting lifting force can hold the carrier in a floating state in the carrier transportation space 15.

[0052] In some embodiments, the north poles of the permanent levitation magnets 221 of the magnetic levitation system face towards the south poles of the one or more magnet units 181 of the carrier, and the south poles of the permanent levitation magnets 221 face towards the north poles of the one or more magnet units 181 of the carrier, as is indicated by different shadings in FIG. 2A. A displacement of the carrier in the vertical direction from the floating position depicted in FIG. 2A leads to the south poles (or the north poles) approaching each other and to a resulting increase of repulsive force between the permanent levitation magnets 221 and the one or more magnet units 181. Accordingly, the floating position of the carrier is an equilibrium position that can be maintained by the purely passive levitation magnets.

[0053] In the embodiment depicted in FIG. 2A, the one or more magnet units 181 of the carrier are provided at the lateral face 11 of the carrier, particularly above the mover part 182 of the asynchronous linear motor and/or below the holding device 17 of the carrier. The permanent levitation magnets 221 of the magnetic levitation system may be provided laterally with respect to the carrier transportation space 15 at a base 20, particularly above the stator part 132 of the asynchronous linear motor. Typically, the magnetic levitation units 220 and the one or more magnet units 181 of the carrier are spaced apart from each other in the lateral direction L during transport with a small gap therebetween, the gap being 20 mm or less, particularly 10 mm or less, such as between 5 mm and 10 mm in some embodiments.

[0054] Since the drive unit 130 of embodiments described herein is arranged laterally with respect to the carrier (and not above or below the carrier), the drive units do not generate a substantial force in the vertical direction. Accordingly, a smooth and reliable levitation can be enabled by purely passive levitation units. The magnetic levitation units can bear the whole weight of the carrier, such that the carrier can be kept in a floating state during the transport. The transport of the carrier may be a completely contactless transport or an essentially contactless transport. A magnetic levitation system configured for an“essentially contactless transport” of the carrier as used herein may be understood as a magnetic levitation system configured to hold the carrier in a floating state via a magnetic levitation force, wherein a mechanical guiding arrangement is provided which at least temporarily comes into contact with the carrier in order to avoid a movement of the carrier out of the carrier transportation space 15 in an uncontrolled way. For example, in the embodiment depicted in FIG. 2A, a mechanical guiding arrangement for at least temporarily acting on the lateral face 11 of the carrier may be provided in order to ensure that the lower carrier portion cannot jump out of the carrier transportation space 15 in the lateral direction L.

[0055] Further, since the asynchronous linear motor of embodiments described herein does not cause substantial forces in the lateral direction L, a smooth and reliable magnetic side stabilization is enabled, and a passive side stabilization device can be used.

[0056] Accordingly, embodiments of the magnetic levitation system as described herein are improved compared to conventional carrier transportation apparatuses, particularly with respect to accurate and smooth transportation of the carriers in high temperature vacuum environments. Further, embodiments as described herein beneficially provide for more robust contactless carrier transportation at lower production costs compared to conventional carrier transportation apparatuses. In particular, embodiments of the magnetic levitation system as described herein are more insensitive against manufacturing tolerances, deformation, and thermal expansion.

[0057] In the present disclosure, the term“contactless” can be understood in the sense that a weight, e.g. the weight of a carrier, particularly the weight of a carrier carrying a substrate or a mask, is not held by a mechanical contact or mechanical forces, but is held by a magnetic force. In other words, the term“contactless” can be understood in that a carrier is held in a levitating or floating state using magnetic forces instead of mechanical forces, i.e. contact forces. The transport of the carrier may be completely contactless or essentially contactless.

[0058] According to some embodiments, which may be combined with other embodiments described herein, the magnetic levitation system may further include at least one sensor 201 configured to detect a presence of the carrier at a specific position along the transport direction. The sensor may be a distance sensor, e.g. a Hall sensor. A plurality of sensors may be provided along the transport path, e.g. two, three or more sensors. For example, at least one sensor may be provided at a path switch position at which a path switch device is provided for moving the carrier to another transport track. Alternatively or additionally, at least one sensor may be provided at a deposition position at which a deposition source for coating the substrate with a material is located. A controller may control the magnetic levitation system, e.g. the drive unit 130, based on the signal of the at least one sensor 201. For example, when the at least one sensor 201 senses the presence of the carrier at a specific position, e.g. a deposition position or a path switch position, the controller may control the drive unit 130 to change the transport speed of the carrier, e.g. in order to stop the carrier at the specific position.

[0059] In some embodiments, the at least one sensor 201 is configured to detect a leading edge 18 or a trailing edge of the carrier. The carrier may include a geometric profile or a specific material at the leading edge 18 that can be sensed by the sensor, such that the presence of the carrier can be determined. In some embodiments, the at least one sensor 201 is configured to detect a distance between the carrier and the at least one sensor. [0060] In some implementations, the carrier 10’ includes the holding device 17 for carrying an object, particularly a substrate or a mask, at a holding surface of the carrier. The holding device may be a mechanical holding device, e.g. a clamp, or an electrostatic or magnetic holding device, e.g. an electrostatic chucking device. In the present disclosure, a“carrier” can be understood as a carrier configured for holding a substrate, also referred to as substrate carrier. For instance, the carrier can be a substrate carrier for carrying a large area substrate. It is to be understood that the embodiments of the magnetic levitation system may also be used for other carrier types, e.g. mask carriers.

[0061] In the present disclosure, the term“substrate” may particularly embrace substantially inflexible substrates, e.g., a wafer, slices of transparent crystal such as sapphire or the like, or a glass plate. However, the present disclosure is not limited thereto, and the term“substrate” may also embrace flexible substrates such as a web or a foil. According to embodiments described herein, the substrate may be made of any material suitable for material deposition. For instance, the substrate may be made of a material selected from the group consisting of glass (for instance soda-lime glass, borosilicate glass etc.), metal, polymer, ceramic, compound materials, carbon fiber materials or any other material or combination of materials which can be coated by a deposition process.

[0062] In the present disclosure, the term“large area substrate” refers to a substrate having a main surface with an area of 0.5 m² or larger, particularly of 1 m² or larger. In some embodiments, a large area substrate can be GEN 4.5, which corresponds to about 0.67 m² of substrate (0.73mx0.92m), GEN 5, which corresponds to about 1.4 m² of substrate (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m² of substrate (1.95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7 m² of substrate (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m² of substrate (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can similarly be implemented. Further, the substrate thickness can be from 0.1 mm to 1.8 mm, particularly about 0.9 mm or below, such as 0.7 mm or 0.5 mm. [0063] In the present disclosure, the term“transport direction” can be understood as the direction in which the carrier is transported along a transport path by the magnetic levitation system. Typically, the transport direction can be an essentially horizontal direction. The transport path can be curved, and the transport direction may vary along the transport path.

[0064] According to another aspect described herein, a vacuum system is provided. The vacuum system includes a vacuum chamber 101, a magnetic levitation system, and a carrier provided in the vacuum chamber. The carrier is configured to carry an object, e.g. a substrate, in the vacuum chamber.

[0065] The magnetic levitation system may be configured according to any of the embodiments described herein. In particular, the magnetic levitation system may include one or more magnetic levitation units 220 for holding the carrier in a carrier transportation space 15 in the vacuum chamber, and a drive unit for moving the carrier in a transport direction along a transport path. The drive unit includes a stator part 132 of an asynchronous linear motor that is arranged laterally with respect to the carrier transportation space. The carrier includes the mover part 182 of the asynchronous linear motor being arranged at a lateral face 11 of the carrier.

[0066] The magnetic levitation system may be configured for a vertical carrier transport, i.e. the carrier may be essentially vertically oriented during the transport (vertical +/- 10°). In particular, the substrate that is carried by the carrier may be held in an essentially vertical orientation during transport and/or during processing. In embodiments, a processing device, particularly a deposition source such as an evaporation or sputter source, may be positioned in the vacuum chamber. The deposition source may be configured to deposit a layer on a substrate carried by the carrier.

[0067] According to another aspect of the present disclosure, an apparatus for transporting a carrier in a vacuum chamber is provided. The apparatus includes a first magnetic levitation system provided along a first transport path and a second magnetic levitation system provided along a second transport path. The first magnetic levitation system and the second magnetic levitation system are configured according to any of the embodiments described herein. Further, the apparatus includes a path switch assembly for moving the carrier away from the first transport path in a lateral direction to at least one of the second transport path and a processing position horizontally offset from the first transport path and the second transport path. The path switch assembly may mechanically contact the carrier for the lateral movement of the carrier. Alternatively, the path switch assembly may be a contactless path switch assembly that contactlessly or essentially contactlessly moves the carrier in the lateral direction L, e.g. by applying magnetic forces.

[0068] FIG. 3 is a flowchart for illustrating a method 300 of transporting a carrier in a vacuum chamber in a transport direction T according to embodiments described herein.

[0069] In box 310, a carrier which may carry an object is levitated in a carrier transportation space in the vacuum chamber with one or more magnetic levitation units of a magnetic levitation system. [0070] In box 320, the carrier is moved in the transport direction T with a drive unit, the drive unit including a stator part 132 of an asynchronous linear motor which is laterally arranged with respect to the carrier and interacts with a mover part 182 of the asynchronous linear motor that is provided at a lateral face 11 of the carrier. The stator part and the mover part are at least partially located at the same height during the transport, i.e. in the same horizontal sectional plane.

[0071] In (optional) box 330, the carrier is moved with the drive unit 130 to a track switch position, where the carrier is moved away from the magnetic levitation system in a lateral direction L with a path switch assembly to at least one of a second transport path and a deposition position. A material may be deposited on a substrate carried by the carrier in the deposition position.

[0072] In some implementations, the carrier is stabilized in a lateral direction L perpendicular to the transport direction during the transport with a magnetic side stabilization device 140. The magnetic side stabilization device may be configured to apply a restoring force on the carrier in the lateral direction urging the carrier to an equilibrium position during the transport. In some embodiments, the magnetic side stabilization device includes at least one first permanent magnet 141 configured to interact with at least one second permanent magnet 142 provided at the carrier. In particular, the magnetic side stabilization device may be a passive side stabilization device that is operated without active control. The carrier can be passively stabilized in the lateral direction L.

[0073] In some implementations, the one or more magnetic levitation units include permanent levitation magnets 221 that magnetically interact with one or more magnet units provided at the carrier. In particular, the carrier may be levitated in a purely passive way in the vertical direction.

[0074] The position and the configuration of the drive unit 130 according to embodiments described herein is particularly beneficial when used in combination with passive levitation units and/or a passive side stabilization device. A smooth and reliable carrier transport can be achieved without complex control circuits and at reduced costs.

[0075] The magnetic levitation system described herein may be configured for transporting different types of carriers, e.g. substrate carriers, mask carriers, or shield carriers. The carrier may be configured to carry a large-area substrate for display manufacturing, a substrate for being coated with an OLED material, or one or more wafers, e.g. semiconductor wafers. The substrates may be transported in an essentially vertical orientation or in an essentially horizontal orientation. For example, the magnetic levitation system described herein may be used in processing systems for at least one or more of wafer processing, glass substrate processing, web substrate processing, processing systems for processing flexible substrates, processing systems for processing large-area substrates, particularly deposition systems for at least one of physical vapor deposition (PVD), particularly sputtering or evaporation, or chemical vapor deposition (CVD).

[0076] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.

Claims

1. A magnetic levitation system (100, 200), comprising: one or more magnetic levitation units (120, 220) for holding a carrier (10) in a carrier transportation space (15); and a drive unit (130) for moving the carrier (10) in a transport direction (T), the drive unit (130) comprising a stator part (132) of an asynchronous linear motor being arranged laterally with respect to the carrier transportation space (15).

2. The magnetic levitation system of claim 1, wherein the stator part (132) of the asynchronous linear motor is configured to interact with a mover part (182) of the asynchronous linear motor provided at a lateral face (11) of the carrier extending essentially vertically.

3. The magnetic levitation system of claim 1 or 2, further comprising a magnetic side stabilization device (140) configured to stabilize the carrier in a lateral direction (L) perpendicular to the transport direction (T). 4. The magnetic levitation system of claim 3, wherein the magnetic side stabilization device (140) is a passive stabilization device comprising at least one first permanent magnet (141).

5. The magnetic levitation system of any of claims 1 to 4, wherein the stator part (132) of the asynchronous linear motor comprises a plurality of coil units configured to generate a magnetic field for inducing currents in a mover part

(182) of the asynchronous linear motor provided at the carrier (10).

6. The magnetic levitation system of any of claims 1 to 5, wherein the stator part (132) is provided laterally with respect to a lower portion (16) of the carrier transportation space (15) and configured to interact with a mover part (182) provided laterally at a lower portion of the carrier (10).

7. The magnetic levitation system of any of claims 1 to 6, wherein the one or more magnetic levitation units (220) are passive units comprising permanent levitation magnets (221) configured to apply a lifting force on the carrier.

8. The magnetic levitation system of any of claims 1 to 7, further comprising at least one sensor (201) configured to detect a presence of the carrier at a specific position along the transport direction (T), particularly for detecting a leading edge (18) of the carrier (10).

9. A carrier (10) for a magnetic levitation system, comprising: a holding device (17) for carrying an object; one or more magnet units (181) configured to magnetically interact with one or more magnetic levitation units (120, 220) of the magnetic levitation system for levitating the carrier; and a mover part (182) of an asynchronous linear motor for moving the carrier in a transport direction (T), the mover part being arranged at a lateral face (11) of the carrier and configured to interact with a stator part (132) of the asynchronous linear motor.

10. The carrier of claim 9, wherein the mover part (182) is arranged at a lower portion of the lateral face (11), and the holding device (17) is configured to hold the object at an upper portion of the lateral face (11), the lateral face (11) being essentially vertically oriented during transport.

11. The carrier of claim 9 or 10, wherein the mover part (182) comprises a conductive material portion extending in the transport direction (T) along the lateral face (11).

12. The carrier of any of claims 9 to 11, wherein the mover part (182) comprises an aluminum plate provided at the lateral face (11) of the carrier and extending in the transport direction (T).

13. A vacuum system, comprising: a vacuum chamber (101); a carrier (10) for carrying an object in the vacuum chamber; and a magnetic levitation system for transporting the carrier in a transport direction (T), comprising: one or more magnetic levitation units (120, 220) for holding the carrier in a carrier transportation space (15) in the vacuum chamber; and a drive unit (130) for moving the carrier in the transport direction (T), the drive unit comprising a stator part (132) of an asynchronous linear motor being arranged laterally with respect to the carrier transportation space; the carrier comprising a mover part (182) of the asynchronous linear motor being arranged at a lateral face (11) of the carrier.

14. A method of transporting a carrier in a vacuum chamber in a transport direction (T), comprising: levitating a carrier in a carrier transportation space in the vacuum chamber with one or more magnetic levitation units (120, 220) of a magnetic levitation system; and moving the carrier in the transport direction with a drive unit (130), the drive unit comprising a stator part (132) of an asynchronous linear motor which is arranged laterally with respect to the carrier and acts on a mover part (182) provided at a lateral face (11) of the carrier.

15. The method of claim 14, wherein the carrier is stabilized in a lateral direction (L) perpendicular to the transport direction (T) with a magnetic side stabilization device (140) comprising at least one first permanent magnet (141), and/or wherein the one or more magnetic levitation units (220) comprise at least one permanent levitation magnet (221), particularly wherein the carrier is passively levitated in the vertical direction (V) and passively stabilized in the lateral direction (L).

16. A magnetic levitation system (100) for transporting a carrier (10) in a transport direction, comprising: one or more magnetic levitation units (120, 220) for holding the carrier (10); and a drive unit (130) for moving the carrier (10) in the transport direction (T), the drive unit (130) comprising a stator part (132) of an asynchronous linear motor configured to interact with a mover part (182) of the asynchronous linear motor arranged at a lateral face (11) of the carrier.