Magnetic levitation system and method for a levitation carrier

Abstract

A magnetic levitation system for a transport vehicle is described. The magnetic levitation system includes a plurality of active magnetic bearings extending along a transport track and at least a first power stage and a second power stage, wherein a first group of the plurality of active magnetic bearings is connected to the first power stage, and a second group of the plurality of active magnetic bearings is connected to the second power stage.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to systems and methods for a transport carrier, particularly a carrier used to carry a large-area substrate. More specifically, embodiments of the present disclosure relate to a magnetic levitation system for levitating and transporting a carrier, particularly in a vacuum chamber. In particular, embodiments of the present disclosure relate to a magnetic levitation system for transporting a carrier and a method for levitating a carrier. Background Art

[0002] Techniques for layer deposition on substrates include physical vapor deposition (PVD) (e.g., sputter deposition such as thermal evaporation or sputtering) and chemical vapor deposition (CVD). The coated substrates can be used in several applications and several technical fields. For example, the coated substrates can be used in the field of display devices. Display devices can be used to manufacture television screens, computer monitors, mobile phones, other handheld devices, etc. for showing information. Typically, a display is produced by coating a substrate with a stack of layers of different materials.

[0003] Typically, substrates are coated in a vacuum deposition system that may include multiple deposition sources and other substrate processing equipment. Typically, substrates are transported along a transport track via a vacuum deposition system, e.g., from a first deposition source to a second deposition source and to other substrate processing equipment. Substrates can be transported via the vacuum system in a substantially vertical orientation.

[0004] Typically, substrates are carried by a carrier, i.e., a load-bearing device for carrying a substrate. Typically, a carrier transport system (e.g., a magnetic levitation system in which the weight of the carrier is held by magnetic force) transports the carrier via a vacuum system. The carrier transport system can be configured to convey a carrier carrying a substrate along a base structure that defines, for example, a transport track.

[0005] Precisely and smoothly transporting a carrier via a vacuum system is challenging. For example, particle generation due to friction between moving parts can lead to degradation in the manufacturing process. Transporting a carrier with a magnetic levitation system can reduce particle generation because mechanical contact between moving parts is reduced. For example, a magnetic levitation system can include a base having a plurality of actively controlled magnetic bearings that generate a magnetic levitation force to hold the carrier at the base in a contactless or substantially contactless manner. However, it is difficult to transport a large-area carrier having dimensions of several square meters with a magnetic levitation system because the tolerance requirements increase with the size of the object being transported.

[0006] Accordingly, it is beneficial to provide an improved magnetic levitation system for levitating and transporting carriers in a vacuum system and an improved method for levitating carriers in a vacuum system that overcome at least some of the problems in the prior art. Specifically, it is beneficial to provide a magnetic levitation system for a transport carrier for carrying a large-area substrate. SUMMARY OF THE INVENTION

[0007] In view of the above, a magnetic levitation system for a transport carrier and a method for levitating a carrier are provided. Other aspects, advantages, and features will be apparent from the dependent claims, description, and drawings.

[0008] According to one embodiment, a magnetic levitation system for a transport carrier is provided. The magnetic levitation system includes a plurality of active magnetic bearings extending along a transport track and at least a first power stage and a second power stage, wherein a first group of the plurality of active magnetic bearings is connected to the first power stage and a second group of the plurality of active magnetic bearings is connected to the second power stage.

[0009] According to one embodiment, a method for levitating a carrier is provided. The method includes routing the output of the first power stage to a first magnetic bearing of the first group of active magnetic bearings, routing the output of the second power stage to a second magnetic bearing of the second group of active magnetic bearings, switching the first power stage to a first subsequent magnetic bearing of the first group of active magnetic bearings, and switching the second power stage to a second subsequent magnetic bearing of the second group of active magnetic bearings. The carrier can be a carrier for carrying a large-area substrate, particularly a substrate having a size of 1 m 2 or larger, particularly 5 m 2 or larger, and more particularly 10 m 2 or larger. The substrate carried by the carrier can be a large-area substrate for display manufacturing. The carrier can be configured to carry the substrate in a substantially vertical orientation.

[0010] The magnetic levitation system can be configured to transport the carrier via a vacuum deposition system having a deposition source for depositing a layer stack on the substrate carried by the carrier.

[0011] The magnetic levitation system can be configured for contactless or substantially contactless transport of the carrier such that particle generation due to friction can be reduced or avoided.

[0012] Embodiments also relate to devices for performing the disclosed methods and include device parts for performing the various described method aspects. These method aspects can be performed via hardware components, a computer programmed with suitable software, by any combination of the two, or in any other way. Additionally, embodiments according to the present disclosure also relate to methods for operating the described devices. The methods for operating the described devices include method aspects for performing each function of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] To understand the above features of the present disclosure in a detailed manner, a more specific description of the present disclosure briefly outlined above can be obtained by referring to the embodiments. The drawings relate to embodiments of the present disclosure and are described as follows:

[0014] Figure 1 A schematic front view of a magnetic levitation system according to embodiments described herein;

[0015] Figure 2 A schematic perspective view of a magnetic levitation system according to embodiments described herein;

[0016] Figure 3 Shows Figure 2 A cross-sectional view of the magnetic levitation system in a first cross-section (A);

[0017] Figure 4 Shows Figure 2 A cross-sectional view of the magnetic levitation system in a second cross-section (B);

[0018] Figure 5 A graph showing the power of the levitation force or power level for transporting along a subsequent levitation actuator (i.e., an active magnetic bearing); and

[0019] Figure 6 Is a flowchart showing a method for levitating a carrier according to embodiments described herein. DETAILED DESCRIPTION

[0020] Reference will now be made in detail to various embodiments of the present disclosure, one or more examples of which are shown in the drawings. In the following description of the figures, the same reference numerals indicate the same components. Only the differences with respect to individual embodiments are described. Each example is provided in an illustrative form and is not intended as a limitation of the present disclosure. Additionally, the characteristic structures shown or described as part of one embodiment can be used on or combined with other embodiments to yield another embodiment. The description is intended to include such modifications and variations.

[0021] Figure 1is a schematic view of a magnetic levitation system 100 according to an embodiment described herein. The magnetic levitation system 100 may include a base 20 that defines a transport track. The carrier 10 may move along the transport track in a transport direction T that may be a substantially horizontal direction.

[0022] The magnetic levitation system 100 described herein may be a carrier transport system that is configured to hold and transport a carrier in a vacuum environment, particularly in a vacuum chamber or in a vacuum system that includes a plurality of vacuum chambers arranged adjacent to each other, for example, in a linear or two-dimensional array. Specifically, the magnetic levitation system 100 may be a part of a vacuum processing system, particularly a vacuum deposition system that is configured to deposit materials on a substrate carried by a carrier.

[0023] As used herein, a "carrier" may be understood as a carrier device that is configured to carry an object, particularly a substrate to be coated, via a vacuum environment. The carrier may include a carrier body and a holding device, such as a mechanical, electrostatic, or magnetic clamping device, that is configured to hold the substrate at a support surface of the carrier body.

[0024] The carrier may be configured to carry a large-area substrate, i.e., a substrate having a size of 1 m 2 or larger, particularly 5 m 2 or larger, more particularly 8 m 2 or larger up to 10 m 2 or larger. Thus, the carrier may be a large and heavy component, and the carrier body has a substrate support surface of several square meters. For example, the carrier may have a weight of 200 kg or more, such as from 400 kg to 2000 kg, such as 1000 kg or more, and / or a length of several meters. Transporting and holding a large and heavy carrier with the levitation magnets of a magnetic levitation system is challenging.

[0025] As used herein, a "magnetic levitation system" may be understood as a carrier transport system that is configured to hold at least a part of the weight of the carrier or the entire weight of the carrier by magnetic force. For example, during transport along the transport track, the carrier may be held relative to the base in a contactless manner or in a substantially contactless manner. The magnetic levitation system may include a plurality of levitation magnets for levitating the carrier relative to the base, such as active and / or passive levitation magnets, such as a plurality of active magnetic bearings.

[0026] The base can be a fixed structure along which the carrier can move. In one embodiment, the base includes a guide rail or track structure with levitation magnets provided at regular intervals. For example, the base can extend from a first vacuum chamber where a substrate can be loaded onto the carrier to a second vacuum chamber where a deposition source for coating the substrate is arranged. A drive unit (such as a linear motor) can be used to transport the carrier along the base.

[0027] As schematically shown in Figure 1 , the magnetic levitation system 100 includes a plurality of active magnetic bearings 30 provided, for example, at the base 20. An active magnetic bearing is an actively controlled magnetic bearing. The actively controlled magnetic bearing is configured to hold the carrier at the base by applying a magnetic force at a predetermined distance. For example, each active magnetic bearing can include an actuator having a controllable magnet (such as an electromagnet) provided at the base (such as at the top guide rail of the base). The actuator can be actively controllable to maintain a predetermined distance (or "gap G") between the base 20 and the carrier 10.

[0028] For example, the output parameter (such as the current applied to the actuator) can be controlled according to input parameters (such as the distance between the carrier and the base). The distance between the base and the carrier can be measured with a distance sensor, and the magnetic field strength of the actuator can be set according to the measured distance. Specifically, in the case where the distance is higher than a predetermined threshold, the magnetic field strength can be increased, and in the case where the distance is lower than the threshold, the magnetic field strength can be decreased. The actuator can be controlled in a closed-loop control or feedback control manner.

[0029] Each magnetic bearing of the plurality of active magnetic bearings 30 can include an actuator (such as an electromagnet) and a distance sensor. A controller can be provided to control the actuator according to the distance measured by the distance sensor. Each magnetic bearing can have an individual controller. Alternatively, a common controller can be provided to control the plurality of active magnetic bearings. According to some embodiments that can be combined with other embodiments described herein, a first group of active magnetic bearings can be associated with a first controller and a second group of active magnetic bearings can be associated with a second controller.

[0030] The plurality of active magnetic bearings 30 are configured to face the guiding structure 12 of the carrier during transportation of the carrier along the transportation track. The guiding structure 12 of the carrier can include magnetic components having an upward-facing surface that points towards the plurality of active magnetic bearings 30. The magnetic components of the guiding structure 12 can include ferromagnetic materials, such as ferroalloys, such as steel. A controlled attractive force can be generated between the guiding structure 12 of the carrier and at least some of the active magnetic bearings so that the carrier can be levitated. The guiding structure 12 can be an upper part of the carrier body configured to interact magnetically with the plurality of active magnetic bearings 30.

[0031] While the carrier 10 is being transported in a floating state in the transport direction T, the plurality of active magnetic bearings 30 can be controlled such that the distance (or "gap G") between the base 20 and the carrier 10 remains substantially constant, for example in the range of 0.5 mm to 2 mm, such as being about 1 mm or 1.5 mm.

[0032] If the carrier 10 is very long and heavy, it is difficult to maintain a substantially constant gap over the entire length of the carrier 10. In such a case, the guiding structures of the base and the carrier need to be manufactured with extremely high precision and flatness, because variations in surface flatness or carrier curvature beyond the permitted levels will result in contact between the carrier and the base or will even make magnetic levitation of the carrier impossible. In addition, there is a risk that the base or the carrier may bend due to pressure or temperature variations in the vacuum system, making it difficult or impossible to maintain a constant gap width by controlling the plurality of active magnetic bearings.

[0033] The embodiments described herein allow for the magnetic levitation of a long and heavy carrier. The guiding structure 12 of the carrier 10 described herein includes a first guiding region 13 and a second guiding region 14 configured to interact with the plurality of active magnetic bearings 30, and a recessed region 15 disposed between the first guiding region 13 and the second guiding region 14 in the transport direction T of the carrier (i.e., longitudinally of the carrier). The recessed region 15 is recessed with respect to the first guiding region 13 and the second guiding region 14. For example, the recessed region 15 may be recessed with respect to the first and second guiding regions by at least 2 mm or more, particularly 3 mm or more ( Figure 1 the recess depth X in). In other words, during carrier transportation, the recessed region 15 may form a deepened or recessed portion in the guiding structure 12 of the carrier that is further away from the plurality of active magnetic bearings 30 compared to the first guiding region 13 and the second guiding region 14.

[0034] During carrier transportation, only the first guiding region 13 and the second guiding region 14 can magnetically interact with the actively controlled magnetic bearings of the plurality of active magnetic bearings 30. Specifically, the first gap between the first guiding region 13 and the base 20 can be controlled to remain substantially constant, for example in the range of G = 0.5 mm to G = 2 mm, and the second gap between the second guiding region 14 and the base can be controlled to remain substantially constant, for example in the range of G = 0.5 mm to G = 2 mm. The distance between the recessed region 15 and the base 20 (corresponding to the sum of the gap G and the recess depth X) is greater, for example 4 mm or more, particularly 5 mm or more.

[0035] According to an embodiment of the present disclosure, the active magnetic bearings (i.e., actuators) of the levitation carrier (e.g., the three-zone carrier as described above) can be reduced or minimized. For example, one actuator (i.e., active magnetic bearing) can levitate the carrier at the front (along the transport direction), and one actuator (i.e., active magnetic bearing) can levitate the carrier at the rear (along the transport direction).

[0036] As described with respect to Figure 5 exemplarily, two actuators can be simultaneously activated on the first side (e.g., the front side), and two actuators can be simultaneously activated on the second side (e.g., the rear side). For example, two actuators can be activated on one side during the movement of the carrier during the transfer of the carrier from one actuator to a subsequent actuator. According to other embodiments, for example, in the case of a large-area carrier with a weight that cannot be carried by one actuator, two actuators can be activated at the first end and two actuators can be activated at the second end. For an arrangement with two front actuators and two rear actuators, similar to the example described with respect to Figure 5 three actuators can be simultaneously activated during the transfer of the actuators for movement. Embodiments of the present disclosure allow for the simultaneous activation of a smaller number of actuators (i.e., active magnetic bearings). Therefore, the number of power stages that can simultaneously supply power can be reduced.

[0037] According to an embodiment of the present disclosure, the number of power stages can be reduced. In particular, the number of power stages can be less than the number of actuators (i.e., active magnetic bearings). According to one embodiment, a magnetic levitation system for transporting a carrier is provided. The magnetic levitation system includes a plurality of active magnetic bearings 30. The plurality of active magnetic bearings extend along a transport track (e.g., along the base 20). At least a first power stage and a second power stage are provided, wherein a first group of the plurality of active magnetic bearings 30 of the plurality of active magnetic bearings is connected to the first power stage and a second group of the plurality of active magnetic bearings is connected to the second power stage.

[0038] Since the number of actuators that are simultaneously activated is reduced, for example, only the actuator at the front end of the rear of the carrier, power stages dedicated to each actuator can be avoided. A switching of the power stages can be provided to send the output of the power stage to the currently activated actuator, i.e., the active magnetic bearing.

[0039] According to some embodiments that can be combined with other embodiments described herein, the switching of the power stages can be provided by a multiplexer, a high-power switch such as an IGBT (insulated gate bipolar transistor), a relay, or other switches configured to switch the power of the power stage from a first actuator associated with the power stage to a second actuator associated with the power stage. The power stage can be associated with a first group of actuators (i.e., active magnetic bearings).

[0040] The power stage as described herein can be understood as the following switching module: the switching module activates the output of the switching module for a predetermined time and selectively activates the output of the switching module at a predetermined output power, a power supply that can be understood to be activatable for a predetermined time and selectively activated at a predetermined output power, or another power source that can be understood to be activatable for a predetermined time and selectively activated at a predetermined output power.

[0041] Figure 1 A power stage assembly having two or more power stages is shown, such as a first power stage and a second power stage. The power stage assembly can be connected to a plurality of active magnetic bearings (i.e., a plurality of actuators) using electrical connectors (such as bus 120). As Figure 1 exemplarily shown, three channels can be provided to the plurality of actuators such that every third actuator along the transport direction is connected to one channel.

[0042] According to some embodiments that can be combined with other embodiments described herein, two or more channels can be provided for connecting the power stage assembly to the actuators. In particular, four channels, six channels, or eight channels can be provided for connecting the power stage assembly to the actuators. The power stage assembly can be disposed adjacent to the transport system, switchgear, or can be distributed along the transport system.

[0043] Embodiments of the present disclosure reduce the number of power stages and can reduce the number of power stages to a minimum. This can result in cost savings due to the reduced number of power stages and reduced installation spacing requirements.

[0044] In Figure 1 , every third actuator is connected to a channel of bus 120, and bus 120 is connected to power stage assembly 110. Thus, compared to having nine power stages for each actuator as shown in Figure 1 , the number of power stages can be reduced, for example, by a factor of three. According to some embodiments that can be combined with other embodiments described herein, the bus is connected to the first power stage, the second power stage, and a plurality of active magnetic bearings (i.e., actuators).

[0045] The switching between actuators will be described in more detail with respect to Figure 5 . Given the fact that subsequent active magnetic bearings are activated in order to transport the carrier 10 along the transport direction T, a multiplexer can be provided. The multiplexer active output can be selected by a shift register, an address control bus (such as an XOR control bus and / or a control bus having multiple addresses). According to some embodiments that can be combined with other embodiments described herein, the magnetic levitation system can include a multiplexer that is configured to via a connector (such as Figure 1The bus 120 shown in [figure number] sends the output of the first power stage to the first magnetic bearing of the first set of magnetic bearings and sends the output of the second power stage to the second magnetic bearing of the second set of magnetic bearings via the bus.

[0046] Thereafter, the first magnetic bearing can be turned off and the second magnetic bearing can be turned off. Power can be supplied to a first subsequent bearing downstream of the first magnetic bearing in the transport direction and a second subsequent bearing downstream of the second magnetic bearing in the transport direction. According to an example, the first subsequent magnetic bearing can be powered by the first power stage and the second subsequent bearing can be powered by the second power stage. According to some embodiments that can be combined with other embodiments described herein, the transfer of the carrier to the subsequent bearings can be improved by having the first subsequent magnetic bearing powered by a third power stage and the second subsequent magnetic bearing powered by a fourth power stage.

[0047] In Figure 1 In the exemplary embodiment shown in [figure number], the controller 50 is connected to each channel of the bus 120 to allow control of the actuators (i.e., the active magnetic bearings 30) via the controller 50. According to some embodiments that can be combined with other embodiments described herein, the controller can be associated with the power stages of the power stage assembly. Thus, the number of controllers can correspond to the number of power stages. One or more controllers can be configured to turn off the active control of the first magnetic bearing or the second magnetic bearing when the first magnetic bearing or the second magnetic bearing faces the recessed area 15 of the carrier 10, respectively. According to some embodiments that can be combined with other embodiments described herein, one or more controllers can control the gap G (i.e., the suspension gap) to be substantially constant. Additionally, one or more controllers 50 can receive a signal indicating the position of the carrier (e.g., a signal providing the position of the carrier along the transport track), and the plurality of active magnetic bearings can be controlled based on the carrier position.

[0048] Embodiments of the present disclosure allow for a power electronics concept and / or a controlled electronics concept along a transport track with a reduced number of electronic components or a minimum number of electronic components, such as a track having a plurality of active magnetic bearings (i.e., magnetic actuators for levitation).

[0049] For a three-zone carrier as described herein, there is no need to provide a single highly flat actuator surface of the base 20 and a single highly flat guiding zone of the carrier 10. Rather, the active magnetic bearings interact magnetically with two separate and spaced-apart carrier zones, namely the first guiding zone 13 and the second guiding zone 14. The active magnetic bearings are controlled to hold the first and second guiding zones at a predetermined short distance from the base, respectively. Thus, even if the carrier and / or the base bend due to temperature or pressure variations, there is no risk of contact between the guiding structure 12 and the base 20; during carrier transportation, the distance between the recessed zone 15 and the base 20 is large enough to avoid any risk of contact. Smooth and reliable levitation of the long carrier becomes possible.

[0050] In some embodiments, which may be combined with other embodiments described herein, the first guiding zone 13 and the second guiding zone 14 define a first plane P1. In other words, during carrier transportation, the first guiding zone 13 and the second guiding zone 14 are substantially in the same plane, and the first plane P1 has a first distance (corresponding to the gap G) from the plurality of active magnetic bearings 30. For example, the guiding structure 12 of the carrier may include a magnetic material component having a first upward-facing surface constituting the first guiding zone 13 in the front portion of the carrier and a second upward-facing surface constituting the second guiding zone 14 in the rear portion of the carrier in the transportation direction T. During carrier transportation, the first and second upward-facing surfaces may be substantially in the same plane, i.e., in the first plane P1.

[0051] In some embodiments, the recessed zone 15 defines a second plane P2, which has a second distance from the plurality of active magnetic bearings during carrier transportation, and the second distance is greater than the first distance. The recessed zone 15 may have an upward-facing surface disposed between the first guiding zone and the second guiding zone, and the upward-facing surface is recessed from the first guiding zone and the second guiding zone by at least the second distance. The recessed zone 15 may have a substantially flat surface. In other embodiments, the recessed zone 15 is not completely flat. However, advantageously, the recessed zone 15 is recessed from the first guiding zone 13 and the second guiding zone 14 by a recess depth X of at least 2 mm or at least 4 mm over the entire extension length between the first guiding zone 13 and the second guiding zone 14, so that contact between the base and the carrier can be reliably avoided.

[0052] In some embodiments, the first distance (corresponding to the gap G) is 2 mm or less, particularly about 1.5 mm, and / or the second distance (corresponding to the sum G+X) is 3 mm or more, particularly about 5 mm. In other words, the second plane P2 may be recessed relative to the first plane P1 by at least 1 mm, particularly a recess depth X of 3 mm or more. Thus, when the gap G between the first and second guiding regions and the base is controlled to be maintained within a predetermined range below 2 mm, there is no risk of contact between the recessed region 15 and the base 20 even if the recessed region 15 has some curvature or unevenness.

[0053] In some embodiments, during carrier transportation, the carrier has a substantially vertical orientation. In other words, the carrier may be oriented such that during carrier transportation, the main surface of the carrier is substantially vertical (vertical + / - 10°). The guiding structure 12 may form an upper portion of the carrier 10 and is configured to interact magnetically with a plurality of active magnetic bearings 30. During carrier transportation, the top track of the base 20 having the plurality of active magnetic bearings 30 may be disposed above the guiding structure 12 of the carrier. The transportation direction T may be a substantially horizontal direction. The transportation direction T may correspond to the longitudinal direction of the carrier along which the carrier moves.

[0054] In some embodiments that may be combined with other embodiments described herein, the carrier 10 has an upper carrier surface. During carrier transportation, the upper carrier surface faces the plurality of active magnetic bearings 30. The front portion of the upper carrier surface in the transportation direction T may form a first guiding region 13 and the rear portion of the upper carrier surface in the transportation direction T may form a second guiding region 14. The spacing in the transportation direction T between the first guiding region 13 and the second guiding region 14 corresponding to the recessed region 15 may have a length of 1 m or more, particularly 2 m or more.

[0055] The gap G between the carrier and the base may be actively controlled only in the front and rear portions of the carrier, and no active control may be provided for the gap in the central portion of the carrier where the recessed region 15 is located. Smooth and reliable carrier transportation may be provided without the risk of control difficulties due to variations in the gap width. In addition, the number of electronic components, particularly the number of power stages and optionally the number of controllers, may be reduced or minimized. The power output from the power stage may be switched or multiplexed to various active magnetic bearings (i.e., actuators for levitation) to reduce the number of electronic devices.

[0056] In some embodiments, which can be combined with other embodiments described herein, the first guiding region 13 and the second guiding region 14 have a dimension of 30 cm or greater in the transport direction, and / or the recessed region 15 can have a dimension of 1 m or greater, particularly 2 m or greater in the transport direction T. According to the embodiments described herein, actively controlling the gap between the carrier and the base in two remote regions of the carrier is sufficient to provide reliable carrier levitation. Active control in the central region of the carrier where the recessed region is arranged may not be required. In some embodiments, the total length of the carrier in the transport direction can be 2 m or greater, particularly 3 m or greater. The recessed region 15 can extend over more than half of the length of the carrier in the transport direction.

[0057] In some embodiments, the magnetic levitation system can further include one or more controllers 50 for individually controlling the plurality of active magnetic bearings 30 according to the position of the carrier along the transport track.

[0058] According to some embodiments, which can be combined with other embodiments described herein, the number of controllers can correspond to the number of power stages. For example, the controller signals can be arranged on a bus, and the controller signals can be switched and / or multiplexed from one active magnetic bearing to another active magnetic bearing, for example after the carrier has moved along the transport direction T.

[0059] In particular, the position of the carrier along the transport track can be determined, and the plurality of active magnetic bearings can be controlled according to the carrier position.

[0060] For example, when a magnetic bearing 30 faces one of the first guiding region 13 and the second guiding region 14, one or more controllers 50 can be configured to actively control at least one or more of the plurality of active magnetic bearings 30. In other words, when it is determined that the carrier is at a carrier position along the transport track where at least one of the magnetic bearings 30 faces the first guiding region 13 or the second guiding region 14, these magnetic bearings 30 are actively controlled to maintain a constant gap G between the respective guiding region and the base. Alternatively or additionally, one or more controllers 50 can be configured to deactivate the active control of these magnetic bearings 30 when at least one magnetic bearing 30 faces the recessed region 15. In other words, when it is determined that the carrier is at a carrier position along the transport track where at least one of the magnetic bearings 30 faces the recessed region 15, the at least one magnetic bearing 30 can be not actively controlled and / or can be deactivated.

[0061] In some embodiments, multiple active magnetic bearings 30 can be controlled such that a first subset of the multiple active magnetic bearings facing one of the first guiding region 13 and the second guiding region 14 is actively controlled or turned on, and a second subset of the multiple active magnetic bearings facing the recessed region 15 is not actively controlled or turned off. The third subset of the active magnetic bearings of the guiding structure 12 that does not face the carrier at all can also be not actively controlled or turned off.

[0062] Thus, in some embodiments, only the active magnetic bearings facing the first guiding region 13 or the second guiding region 14 can be actively controlled, and the remaining magnetic bearings can be turned off or the active control can be deactivated. Smooth and reliable carrier transportation can be ensured.

[0063] Figure 5 Illustrates the transfer between actuators when the carrier 10 moves along the transport direction T. The carrier 10 is transferred or "handed over" from one actuator (i.e., the active magnetic bearing) to the subsequent actuator. Figure 5 Illustrates three actuators at the end portion of the carrier 10 along the transport direction T. The end portion of the carrier includes a guiding region (see the reference numeral 14 in Figure 1 ). Three subsequent actuators are shown, and the corresponding actuator forces or powers provided to the actuators are shown in the graph 500, which vary with the carrier position.

[0064] In Figure 5 , the first line 512 corresponds to the left actuator, the second (dashed) line 514 corresponds to the middle actuator, and the third (dotted) line 516 corresponds to the right actuator. In the initial state, for example, at the top carrier position shown in Figure 5 , full power or levitation force is provided by the left actuator. As the carrier moves along the transport direction T, the power or levitation force of the left actuator decreases (see line 512) while the power or levitation force of the middle actuator increases (see line 514). For a period of time, the carrier (i.e., the end portion shown in Figure 5 ) is levitated by the left actuator and the middle actuator shown in Figure 5 . After further movement of the carrier, the left actuator is turned off and the levitation force or power of the central actuator is further increased until the carrier is levitated by the central actuator. As the carrier further moves along the transport direction T, the power or levitation force of the central actuator decreases (see line 514) while the power levitation force of the right actuator in Figure 5 increases (see line 516). For a period of time, the carrier is levitated by the central actuator and the right actuator shown in Figure 5 . After further movement of the carrier along the transport direction T, the central actuator is turned off and the levitation force or power of the right actuator is further increased until the carrier is levitated by the right actuator.

[0065] As Figure 5 shown, the carrier can be levitated at one end of the carrier by two actuators simultaneously. In addition, when the right actuator starts to provide an actuator force, i.e., when the right actuator is driven, the left actuator is turned off. Therefore, the power stage that supplies power to the left actuator can also supply power to the right actuator. The left actuator and the right actuator are not activated simultaneously. Therefore, Figure 5 the left actuator in Figure 5 and the right actuator in

[0066] Figure 5 can share a common power stage. The switching or multiplexing of the output of the power stage can be controlled; thus, the number of power stages can be reduced or minimized. Figure 5 shows one side of the carrier 10, e.g., the end side along the transport direction T. Similarly, the opposite side can be switched between actuators and can share a common power stage. Considering Figure 5 the example in which two power stages are at least partially driven simultaneously at the rear end of the carrier 10, two power stages can be provided on each side of the carrier 10 according to the embodiments described herein. According to some embodiments that can be combined with other embodiments described herein, the number of power stages for the levitation system can be 2*N, where N is an integer greater than or equal to 1. In Figure 5 the example shown, N is equal to 2. Depending on the number of actuators that can receive power simultaneously, e.g., depending on the length of the guiding zone of the carrier relative to the length of the actuators (i.e., active magnetic bearings) along the transport direction, N can be in particular 1, 2, 3, or 4.

[0067] A plurality of active magnetic bearings 30 can be distributed at constant intervals along a transport track defined by a base, wherein in the transport direction T, the interval between two adjacent active magnetic bearings can be smaller than the size of the first guiding zone 13 (and the second guiding zone 14). Therefore, it can be ensured that at any time during the movement of the carrier along the transport track, at least one active magnetic bearing faces the first guiding zone 13 (and the second guiding zone 14). For example, at any time during the movement of the carrier, at least two active magnetic bearings face the first guiding zone 13 and at least two other active magnetic bearings face the second guiding zone 14.

[0068] In some embodiments that can be combined with other embodiments described herein, the magnetic levitation system further includes a drive unit for moving the carrier 10 along the transport track. The drive unit can include a linear motor 60 that moves the carrier in the transport direction T by magnetic force. The linear motor 60 can be selectively arranged at the lower guide rail of the base disposed below the carrier, as in Figure 1is schematically shown. The linear motor 60 can interact with a magnetic mating member (such as an array of permanent magnets disposed at the carrier) disposed at the bottom portion of the carrier.

[0069] In some embodiments, the linear motor 60 can be configured to determine the position of the carrier along the transport track and forward the carrier position to one or more controllers 50 for controlling the plurality of active magnetic bearings 30. For example, the linear motor 60 can include position detection devices, such as encoders or resolvers, which provide information about the current carrier position. Thus, one or more controllers 50 of the plurality of active magnetic bearings 30 are aware of the current carrier position and can control the plurality of active magnetic bearings 30 based on the current carrier position along the transport track. Alternatively or additionally, a separate position detection device, such as a sensor, such as a distance sensor, can be provided to determine whether a carrier is present at a specific position along the base. The sensor output can be forwarded to one or more controllers of the plurality of active magnetic bearings.

[0070] According to some embodiments, which can be combined with other embodiments described herein, switching of two or more power levels, such as multiplexing, can be provided based on the current carrier position.

[0071] Thus, the position of the carrier along the transport track can be determined and information about the carrier position can be forwarded to one or more controllers and / or the power stage assembly 110 to drive and / or control the plurality of active magnetic bearings. Thus, the plurality of active magnetic bearings can be controlled and / or driven based on the current carrier position, and a subset of the plurality of active magnetic bearings facing the recessed area 15 can be temporarily turned off or deactivated.

[0072] The carrier 10 as described herein can move along a transport track defined by the base 20. A plurality of magnetic bearings can be provided at the base for holding the carrier in a contactless or substantially contactless manner. Figure 1 The carrier 10 according to the embodiments described herein during contactless transport along the base 20 is shown.

[0073] The carrier includes a guiding structure 12. The guiding structure 12 can include magnetic material components having a surface facing upward that points to the magnetic bearings of the base during carrier transport. The guiding structure 12 includes a first guiding region 13 and a second guiding region 14 configured to interact magnetically with the plurality of active magnetic bearings 30, and a recessed area 15 disposed between the first guiding region 13 and the second guiding region 14 in the transport direction T of the carrier. The entire longitudinal extension length along the recessed area is recessed by a recess depth X of at least 2 mm relative to the first guiding region 13 and the second guiding region 14.

[0074] The carrier 10 may further include a holding device for holding the substrate 11 on the holding surface of the carrier. The substrate 11 may be a large-area substrate for display manufacturing, having a size of, for example, several square meters. Alternatively, the substrate 11 may be a semiconductor wafer or may include multiple wafers. The holding device may be a mechanical clamping device, such as a clamp, an electrostatic chuck, or a magnetic chuck.

[0075] In particular, the substrate 11 may be a large-area substrate having a size of at least 1 m 2 . The size may be about 1.375 m 2 (1.1 m x 1.25 m - GEN 5) to about 15 m 2 , more specifically about 5 m 2 to about 9 m 2 and even up to 15 m 2 . For example, the substrate may be GEN 7.5 corresponding to a surface area of about 4.39 m 2 (1.95 m x 2.25 m), GEN 8.5 corresponding to a surface area of about 5.7 m 2 (2.2 m x 2.5 m), or GEN 10 corresponding to a surface area of about 9 m 2 (2.88 m X 3.13 m). Even larger generations, such as GEN 11 and GEN 12, may be implemented. The carrier 10 has a substrate support surface for supporting and holding the substrate.

[0076] The carrier 10 may have a size of 1 m or greater, particularly 2 m or greater, and even 3 m or greater in the vertical direction V. The carrier 10 may have a size of 1 m or greater, particularly 2 m or greater, and even 3 m or greater in the longitudinal direction corresponding to the transport direction T. The carrier may have a size of 5 m 2 or greater, particularly 9 m 2 or greater, and even 15 m 2 or greater.

[0077] Figure 2 A schematic perspective view of the upper part of the magnetic levitation system 200 according to the embodiments described herein is shown. The magnetic levitation system 200 is similar to Figure 1 the magnetic levitation system 100 such that the above description can be referred to and will not be repeated here.

[0078] The magnetic levitation system 200 includes a base having a plurality of active magnetic bearings 30 arranged along a transport track, and a carrier 10 that can be levitated using the plurality of active magnetic bearings 30. Figure 2 Only the upper front part of the carrier 10 is shown in

[0079] A plurality of active magnetic bearings 30 interact magnetically with a guiding structure 12 on the carrier. The guiding structure 12 can be arranged at the head portion of the carrier and can include a magnetic material having a surface facing upward, such as a magnetic steel. The guiding structure 12 can be attracted toward the plurality of active magnetic bearings 30, wherein the plurality of active magnetic bearings are actively controlled such that a constant gap G is maintained between the carrier 10 and the base 20 (see Figure 3 ).

[0080] The guiding structure 12 of the carrier includes a first guiding region 13, a recessed region 15, and a second guiding region. The recessed region 15 is arranged between the first guiding region 13 and the second guiding region in the transport direction T of the carrier. Figure 2 Only the upper front portion of the carrier without the second guiding region is shown. The recessed region 15 can be recessed by at least 2 mm or a greater recess depth X with respect to the first and second guiding regions, as schematically indicated in Figure 3 and Figure 4 .

[0081] The first and second guiding regions can include guiding surfaces 17, which are flat and lie in the same plane during the transport of the carrier, particularly in a substantially horizontal plane. The guiding surfaces 17 can extend along the transport direction T of the carrier such that the guiding surfaces 17 can interact with the magnetic bearings of the plurality of active magnetic bearings. The guiding surfaces 17 can be the surface facing upward of the carrier, particularly the top surface of the carrier.

[0082] Figure 3 Shown Figure 2 is a schematic cross-sectional view of the magnetic levitation system 200 in a first cross-section (A). The position of the first cross-section (A) is indicated in Figure 2 . The first cross-section (A) intersects the first guiding region 13.

[0083] Figure 4 Shown Figure 2 is a schematic cross-sectional view of the magnetic levitation system 200 in a second cross-section (B). The position of the second cross-section (B) is indicated in Figure 2 . The second cross-section (B) intersects the recessed region 15.

[0084] As schematically indicated in Figure 3 and Figure 4 , the distance between the first guiding region 13 (and the second guiding region) and the base 20 corresponds to the actively controlled gap G and is smaller than the distance between the recessed region and the base by a recess depth X of, for example, 2 mm or more.

[0085] In some embodiments, which can be combined with other embodiments described herein, a plurality of permanent magnets 18 configured to contribute to the levitation force of the carrier can be provided at the recessed region 15.

[0086] The attractive magnetic force can act between the permanent magnet 18 in the recessed area 15 and the magnetic bearings of the plurality of active magnetic bearings facing the permanent magnet, even when the active control of the magnetic bearings is turned off. The reason is that the active magnetic bearings include actuators (such as electromagnets), which include magnetic material components 19, such as the iron or steel cores of the electromagnets. Even when the actuators are not actively controlled, the permanent magnet 18 in the recessed area 15 can be attracted towards the magnetic material components 19 of the actuators, thereby resulting in a levitation force acting on the carrier.

[0087] In particular, the first (actively controlled) part of the levitation force that levitates the carrier can act between the first subset of the plurality of active magnetic bearings and the first and second guiding areas, and the second (passive) part of the levitation force that levitates the carrier can act between the permanent magnet 18 and the magnetic material components 19 of some of the actuators of the plurality of active magnetic bearings, while the actuators may not be actively controlled. The first part of the levitation force is actively controlled to maintain a constant gap G between the first subset of the plurality of active magnetic bearings and the first and second guiding areas. Therefore, it may not be necessary for all the weight of the carrier to be borne by the actively controlled magnetic bearings. Specifically, at least a part of the weight of the carrier can be borne by the magnetic interaction between the passive element (i.e., the permanent magnet 18) acting as a weight compensation element and the magnetic material components 19 of the actuators (such as the iron core of the electromagnet).

[0088] Figure 6 is a flowchart showing a method of levitating a carrier according to an embodiment described herein. In operation 610, the output of the first power stage is sent to the first magnetic bearing of the first group of active magnetic bearings. This can be, for example, Figure 5 the left active magnetic bearing in Figure 5 shows the rear end of the carrier 10. The corresponding active magnetic bearing can be the active magnetic bearing corresponding to the front end of the carrier. In operation 630, the output of the first power stage can be sent to or switched to the first subsequent magnetic bearing, such as Figure 5 the right active magnetic bearing shown in

[0089] As described with respect to Figure 5 a third power stage can be turned on, for example, for the power stage of the central active magnetic bearing shown in Figure 5 This is shown by operation 620. As described above, the output of the power stage can be sent to the active magnetic bearings via a bus.

[0090] The embodiments described herein can be used for a transport carrier configured to carry at least one of a large area substrate, a glass substrate, a wafer, a semiconductor substrate, a mask, a shield, and other articles. The carrier can carry a single article, such as a large area substrate that is 1 m 2 or larger, particularly 5 m 2 or 10 m 2 or larger, or multiple articles of smaller size, such as multiple semiconductor wafers. The carrier can include a holding device configured to hold the article at the carrier, such as a magnetic chuck, an electrostatic chuck, or a mechanical clamping device.

[0091] During transportation, the carrier can have a substantially vertical orientation (e.g., vertical + / - 10°). Alternatively, during transportation, the carrier can have a substantially horizontal orientation (e.g., horizontal + / - 10°). Specifically, a vacuum deposition system can be configured for vertical substrate transport and processing.

[0092] Although the foregoing relates to embodiments, other and further embodiments can be envisioned without departing from the basic scope, and the scope is determined by the appended claims.

Claims

1. A magnetic levitation system (100) for a transport vehicle, comprising: a plurality of active magnetic bearings (30) extending along a transport track; at least a first power stage and a second power stage, wherein a first group of the plurality of active magnetic bearings (30) is connected to the first power stage, and a second group of the plurality of active magnetic bearings is connected to the second power stage; a vehicle (10) movable along the transport track, the plurality of active magnetic bearings (30) being configured to face a guiding structure (12) of the vehicle, the guiding structure (12) comprising: a first guiding region (13) and a second guiding region (14), the first guiding region and the second guiding region being configured to interact with the plurality of active magnetic bearings (30); and a recessed region (15) disposed between the first guiding region (13) and the second guiding region (14) in a transport direction (T) of the vehicle, the recessed region being recessed relative to the first guiding region (13) and the second guiding region (14); and one or more controllers configured to deactivate active control of the magnetic bearings when an active magnetic bearing of the plurality of active magnetic bearings faces the recessed region.

2. The magnetic levitation system according to claim 1, further comprising: a bus connected to the first power stage, the second power stage, and the plurality of active magnetic bearings.

3. The magnetic levitation system according to claim 2, further comprising: a multiplexer configured to send an output of the first power stage to a first magnetic bearing of the first group of active magnetic bearings via the bus and send an output of the second power stage to a second magnetic bearing of the second group of active magnetic bearings via the bus.

4. The magnetic levitation system according to claim 1, wherein the one or more controllers are configured to switch the first power stage from a first magnetic bearing of the first group of active magnetic bearings to a first subsequent magnetic bearing downstream of the first magnetic bearing in the transport direction, and switch the second power stage from a second magnetic bearing of the second group of active magnetic bearings to a second subsequent magnetic bearing downstream of the second magnetic bearing in the transport direction.

5. The magnetic levitation system according to claim 2, wherein the one or more controllers are configured to switch the first power stage from a first magnetic bearing of the first group of active magnetic bearings to a first subsequent magnetic bearing downstream of the first magnetic bearing in the transport direction, and switch the second power stage from a second magnetic bearing of the second group of active magnetic bearings to a second subsequent magnetic bearing downstream of the second magnetic bearing in the transport direction.

6. The magnetic levitation system according to claim 3, wherein The one or more controllers are configured to switch the first power stage from the first magnetic bearing to a first subsequent magnetic bearing that is downstream of the first magnetic bearing in the transport direction, and to switch the second power stage from the second magnetic bearing to a second subsequent magnetic bearing that is downstream of the second magnetic bearing in the transport direction.

7. The magnetic levitation system according to any one of claims 1 to 6, further comprising: A base (20) extending along the transport track, at which the plurality of active magnetic bearings are provided.

8. The magnetic levitation system according to claim 1, wherein the first guiding region (13) and the second guiding region (14) define a first plane (P1), which is at a first distance from the plurality of active magnetic bearings (30) during the transport of the carrier, and wherein the recessed region (15) defines a second plane (P2), which is at a second distance from the plurality of active magnetic bearings during the transport of the carrier, the second distance being greater than the first distance.

9. The magnetic levitation system according to claim 8, wherein the first distance is 2 mm or less, and / or wherein the second distance is 3 mm or more.

10. A magnetic levitation system (100) for transporting a carrier, comprising: A plurality of active magnetic bearings (30) extending along a transport track; At least a first power stage and a second power stage, wherein a first set of the plurality of active magnetic bearings (30) is connected to the first power stage, and a second set of the plurality of active magnetic bearings is connected to the second power stage; One or more controllers configured to switch the first power stage from a first magnetic bearing of the first set of active magnetic bearings to a first subsequent magnetic bearing that is downstream of the first magnetic bearing in the transport direction, and to switch the second power stage from a second magnetic bearing of the second set of active magnetic bearings to a second subsequent magnetic bearing that is downstream of the second magnetic bearing in the transport direction; A base (20) extending along the transport track, at which the plurality of active magnetic bearings are provided; A carrier (10) movable along the transport track, the plurality of active magnetic bearings (30) being configured to face a guiding structure (12) of the carrier, the guiding structure (12) comprising: A first guiding region (13) and a second guiding region (14), the first guiding region and the second guiding region being configured to interact with the plurality of active magnetic bearings (30); and A recessed region (15) arranged between the first guiding region (13) and the second guiding region (14) in the transport direction (T) of the carrier, the recessed region being recessed relative to the first guiding region (13) and the second guiding region (14); Wherein the one or more controllers (50) are configured to actively control the first magnetic bearing (30) of the plurality of active magnetic bearings (30) when the first magnetic bearing (30) of the plurality of active magnetic bearings (30) faces the first guiding region (13), and wherein the one or more controllers (50) are configured to actively control the second magnetic bearing (30) when the second magnetic bearing (30) of the plurality of active magnetic bearings (30) faces the second guiding region, and wherein the one or more controllers (50) are configured to turn off the active control of the first magnetic bearing (30) or the second magnetic bearing when the first magnetic bearing or the second magnetic bearing faces the recessed region (15) respectively.

11. The magnetic levitation system according to claim 10, further comprising a linear motor (60) for moving the carrier (10) along the transportation track.

12. The magnetic levitation system according to claim 10, further comprising: A plurality of permanent magnets (18), the plurality of permanent magnets being configured to contribute to a carrier levitation force provided at the recessed region (15).

13. The magnetic levitation system according to claim 12, wherein the plurality of permanent magnets (18) are arranged as two parallel traces at a distance corresponding to the distance between the magnetic material components (19) of the plurality of active magnetic bearings (30).

14. The magnetic levitation system according to claim 11, further comprising: A plurality of permanent magnets (18), the plurality of permanent magnets being configured to contribute to a carrier levitation force provided at the recessed region (15).

15. A method of levitating a carrier (10), the method comprising: Sending the output of a first power stage to a first magnetic bearing of a first set of active magnetic bearings of a plurality of active magnetic bearings; Sending the output of a second power stage to a second magnetic bearing of a second set of active magnetic bearings of the plurality of active magnetic bearings; Switching the first power stage to a first subsequent magnetic bearing of the first set of active magnetic bearings; and Switching the second power stage to a second subsequent magnetic bearing of the second set of active magnetic bearings, wherein the carrier has a guiding structure (12) facing the plurality of active magnetic bearings, and the guiding structure (12) includes: A first guiding region (13) and a second guiding region (14), the first guiding region and the second guiding region being configured to interact with the plurality of active magnetic bearings; and A recessed region (15), the recessed region being arranged between the first guiding region (13) and the second guiding region (14) in the transportation direction (T) of the carrier, and the recessed region being recessed relative to the first guiding region (13) and the second guiding region (14), The method further includes: Turning off the active control of the magnetic bearing when an active magnetic bearing among the plurality of active magnetic bearings faces the recessed region.

16. The method according to claim 15, wherein the first power stage is deactivated between switching from the first magnetic bearing to the first subsequent magnetic bearing, and when the first power stage is deactivated, a third power stage is activated, wherein the third power stage is different from the first power stage and the second power stage.

17. The method according to any one of claims 15 to 16, wherein the output of the first power stage and the output of the second power stage are sent via a bus.

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