FIELD

[0001] Embodiments described herein relate to a processing system in which a carrier is provided. More specifically, embodiments described herein relate to methods for determining an alignment of a device for guiding a carrier in a processing system.

BACKGROUND

[0002] Systems are known for performing various processes, e.g. coating of a substrate in a processing chamber. Several methods are known for depositing a material on a substrate. As an example, substrates may be coated by using an evaporation process, a physical vapor deposition (PVD) process, such as a sputtering process, a spraying process, etc., or a chemical vapor deposition (CVD) process. The process can be performed in a processing chamber of a deposition apparatus, where the substrate to be coated is located. A deposition material is provided in the processing chamber. A plurality of materials, such as small molecules, metals, oxides, nitrides, and carbides may be used for deposition on a substrate. Further, other processes like etching, structuring, annealing, or the like can be conducted in processing chambers.

[0003] For example, coating processes may be considered for large area substrates, e.g. in display manufacturing technology. Coated substrates can be used in several applications and in several technical fields. For instance, an application can be organic light emitting diode (OLED) panels. Further applications include insulating panels, microelectronics, such as semiconductor devices, substrates with thin film transistors (TFTs), color filters or the like. OLEDs are solid-state devices composed of thin films of (organic) molecules that create light with the application of electricity. As an example, OLED displays can provide bright displays on electronic devices and use reduced power compared to, for example, liquid crystal displays (LCDs). In the processing chamber, the organic molecules are generated (e.g., evaporated, sputtered, or sprayed etc.) and deposited as layers on the substrates. The particles can for example pass through a mask having a boundary or a specific pattern to deposit material at desired positions on the substrate, e.g. to form an OLED pattern on the substrate. [0004] A processing system can include a guiding device for guiding a carrier in the processing chamber, e.g. during a coating process. A guiding device may be adapted for providing the carrier in a processing position and/or for transporting the carrier within the processing chamber. An alignment of the guiding device can be provided. As an example, the alignment should be accurate in order to achieve good process results, e.g. to ensure that the carrier is supported in the processing chamber in a target position or that the carrier moves in the processing chamber according to a target path. Determining the alignment of the guiding device should preferably be performed in a time-efficient and cost-efficient manner.

[0005] In view of the above, there is a need for apparatuses and methods which can provide for an improved alignment of a device for guiding a carrier in a processing system.

SUMMARY

[0006] According to an embodiment, a method for determining an alignment of a carrier levitation system is provided. The carrier levitation system includes a plurality of magnetic units adapted for contactlessly levitating a carrier, wherein the plurality of magnetic units includes a first magnetic unit and a second magnetic unit. The method includes measuring a first distance from the first magnetic unit to the carrier. The method includes measuring a second distance from the second magnetic unit to the carrier. The method includes determining, from at least the first distance and the second distance, an alignment of the carrier levitation system.

[0007] According to a further embodiment, a method for determining an alignment of a carrier levitation system is provided. The carrier levitation system includes a plurality of magnetic units adapted for contactlessly levitating a carrier. The plurality of magnetic units includes a first magnetic unit and a second magnetic unit. The method includes measuring a first distance from the first magnetic unit to the carrier while the carrier is contactlessly levitated by at least the first magnetic unit. The method includes measuring a second distance from the second magnetic unit to the carrier while the carrier is contactlessly levitated by at least the second magnetic unit. The method includes determining, from at least the first distance and the second distance, an alignment of the carrier levitation system.

[0008] According to a further embodiment, a method for determining an alignment of a carrier levitation system is provided. The carrier levitation system includes a plurality of magnetic units adapted for contactlessly levitating a carrier. The plurality of magnetic units includes a first magnetic unit and a second magnetic unit. The method includes measuring a first distance from the first magnetic unit to the carrier while the carrier is mechanically supported by a mechanical support. The method includes measuring a second distance from the second magnetic unit to the carrier while the carrier is mechanically supported by the mechanical support. The method includes determining, from at least the first distance and the second distance, an alignment of the carrier levitation system and/or of the mechanical support.

[0009] According to a further embodiment, an apparatus is provided. The apparatus includes a carrier levitation system including a plurality of magnetic units. The plurality of magnetic units is adapted for contactlessly levitating a carrier. The plurality of magnetic units includes a first magnetic unit and a second magnetic unit. The apparatus includes a first distance sensor. The apparatus includes a second distance sensor. The apparatus includes a control unit connected to the first distance sensor and the second distance sensor. The control unit is configured for determining, from at least a first distance from the first magnetic unit to the carrier and a second distance from the second magnetic unit to the carrier, an alignment of the carrier levitation system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] A full and enabling disclosure to one of ordinary skill in the art is set forth more particularly in the remainder of the specification including reference to the accompanying drawings wherein:

Fig. 1 shows an apparatus according to embodiments described herein;

Fig. 2a-b illustrate different alignments for a plurality of magnetic units according to embodiments described herein;

Figs. 3a-b, 4 and 5a-b illustrate a method for determining an alignment of a carrier levitation system according to embodiments described herein; and

Figs. 6a-c, and 7-9 show an apparatus according to embodiments described herein. DETAILED DESCRIPTION

[0011] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation. 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.

[0012] Embodiments described herein involve contactless levitation and/or transportation of a carrier, e.g. a substrate carrier. The term "contactless" as used throughout the present disclosure can be understood in the sense that a weight of the carrier is not held by a mechanical contact or mechanical forces, but is held by a magnetic force. Specifically, the carrier may be held in a levitating or floating state using magnetic forces instead of mechanical forces. In some implementations, there can be no mechanical contact between the carrier and the rest of the apparatus at all during levitation, and for example movement, of the carrier in the system.

[0013] An advantage, as compared to mechanical devices for guiding a carrier in a processing system, is that a contactless levitation does not suffer from friction affecting the linearity and/or precision of the movement of the carrier. The contactless transportation of the carrier allows for a frictionless movement of the carrier, wherein a position of the carrier, e.g. relative to a mask in a deposition process, can be controlled and maintained with high precision. Further, the levitation allows for fast acceleration or deceleration of the carrier and/or a fine adjustment of the carrier speed.

[0014] For example, a contactless levitation or transportation of a carrier during a deposition process is beneficial in that no particles are generated due to a mechanical contact between the carrier and sections of the apparatus, such as mechanical rails, during the transport of the carrier. Accordingly, a contactless levitation or transportation provides for an improved purity and uniformity of the layers deposited on the substrate, in particular since a particle generation is minimized when using contactless levitation. [0015] According to embodiments, which can be combined with other embodiments described herein, a carrier may be a carrier adapted for carrying or supporting an object. A carrier may define a plane, e.g. a plane substantially parallel to a substrate receiving area.

[0016] According to embodiments, which can be combined with other embodiments described herein, a carrier may be adapted for carrying a substrate and/or a plurality of substrates. A carrier may be a substrate carrier. For example, a carrier may be adapted for carrying a large area substrate and/or a plurality of large area substrates.

[0017] According to embodiments, a large area substrate or a respective carrier may have a size of at least 0.67 m ² . The size may be from about 0.67m (0.73x0.92m - Gen 4.5) to about 8 m ² , more specifically from about 2 m ² to about 9 m ² or even up to 12 m ² . For instance, a large area substrate or carrier can be GEN 4.5, which corresponds to about 0.67 m ² substrates (0.73x0.92m), GEN 5, which corresponds to about 1.4 m ² substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m ² substrates (1.95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7m ² substrates (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m ² substrates (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.

[0018] The term "substrate" as used herein embraces both inflexible substrates, e.g., a glass substrate, a wafer, slices of transparent crystal such as sapphire or the like, or a glass plate, and flexible substrates, such as a web or a foil. According to embodiments, which can be combined with other embodiments described herein, embodiments described herein can be utilized for Display PVD, i.e. sputter deposition on large area substrates for the display market.

[0019] According to embodiments, which can be combined with other embodiments described herein, a carrier may be adapted for carrying a mask, e.g. an edge exclusion mask for preventing the edges of a substrate to be coated in a deposition process. A carrier may be a mask carrier.

[0020] A carrier according to embodiments described herein need not be limited to a substrate carrier or mask carrier. The methods described herein also apply to other types of carriers, i.e. carriers adapted for carrying objects or devices other than, e.g., substrates or masks. [0021] For the sake of concreteness, the figures show a vertically oriented carrier. Embodiments described herein are not limited to vertically oriented carriers. Other orientations, e.g. a horizontal orientation, of the carrier can also be provided.

[0022] In the present disclosure, the terminology of "substantially parallel" directions may include directions which form a small angle of up to 10 degrees with each other, or even up to 15 degrees. The terminology of "substantially perpendicular" directions may include directions which form an angle of less than 90 degrees with each other, e.g. at least 80 degrees or at least 75 degrees. Similar considerations apply to the notions of substantially parallel or perpendicular axes, planes, areas, orientations or the like.

[0023] Some embodiments described herein involve the notion of a "vertical direction". A vertical direction is considered a direction parallel or substantially parallel to the direction along which the force of gravity extends. A vertical direction may deviate from exact verticality (the latter being defined by the gravitational force) by an angle of, e.g., up to 15 degrees.

[0024] Embodiments described herein may further involve the notion of a "horizontal direction". A horizontal direction is to be understood to distinguish over a vertical direction. A horizontal direction may be perpendicular or substantially perpendicular to the exact vertical direction defined by gravity.

[0025] Embodiments described herein relate to a method for determining the alignment of a carrier levitation system. Before providing a detailed discussion of embodiments, for the sake of concreteness reference is first made to Fig. 1 showing an example of an apparatus 100 according to embodiments described herein. Embodiments of the method described herein may be performed using the apparatus 100 shown in Fig. 1. The methods described herein are not restricted to be performed using the apparatus 100 shown in Fig. 1.

[0026] The apparatus 100 shown in Fig. 1 includes a carrier 110. The carrier 110 supports a substrate 120. The carrier 110 includes a first passive magnetic unit 150, e.g. a bar of ferromagnetic material. The apparatus 100 includes a carrier levitation system including a plurality of magnetic units 170, e.g. active magnetic units such as electromagnetic devices, solenoids, coils or superconducting magnets. Individual magnetic units of the plurality of magnetic units are indicated with reference numeral 175. The carrier levitation system extends in a first direction 192. The carrier 110 is movable along the plurality of magnetic units 170. The first passive magnetic unit 150 and the plurality of active magnetic units 170 are configured for providing a magnetic levitation force for levitating the carrier 110. The magnetic levitation force extends in a second direction 194.

[0027] The apparatus 100 shown in Fig. 1 may include a plurality of distance sensors (not shown) provided at the plurality of magnetic units 170. A distance sensor may be provided at each active magnetic unit of the plurality of magnetic units 170. The distance sensors may be configured for measuring the distances between the plurality of magnetic units and the carrier during contactless levitation of the carrier.

[0028] The apparatus 100 shown in Fig. 1 includes a magnetic drive structure 180. The magnetic drive structure 180 includes a further plurality of magnetic units, e.g. active magnetic units. Individual magnetic units of the magnetic drive structure are indicated with reference numeral 185. The carrier 110 can include a second passive magnetic unit 160 to interact with the magnetic units of the magnetic drive structure 180. The magnetic units of the magnetic drive structure 180 drive the carrier within the processing system, for example along the first direction 192. For example, the second passive magnetic unit 160 can include a plurality of permanent magnets, which are arranged with an alternating polarity. The resulting magnetic fields of the second passive magnetic unit 160 can interact with the plurality of magnetic units of the magnetic drive structure 180 to move the carrier 110 in the first direction 192 while being levitated.

[0029] The apparatus 100 shown in Fig. 1 includes a mechanical support 140, e.g. a plurality of rollers, retainer bearings or emergency bearings. The mechanical support 140 is provided below the levitated carrier. The mechanical support 140 is mounted to the magnetic drive structure 180. The mechanical support 140 may be adapted for catching the carrier 110 in case of a failure of the carrier levitation system levitating the carrier 110. For example, in a coating process or other process, the carrier 110 may be magnetically levitated by the plurality of magnetic units 170. In case the levitation of the carrier 110 is suddenly interrupted, e.g. due to a loss of power, the carrier 110 can in the worst case cease to be magnetically levitated and fall down. According to embodiments described herein, the carrier 110 can land on the mechanical support, which can catch the carrier and prevent damage to the carrier or other parts of the system.

[0030] The apparatus shown in Fig. 1 may include a deposition source (not shown). The deposition source may be arranged for coating a substrate, e.g. a vertically arranged substrate, supported by the levitated carrier 110. During the coating process, the contactlessly levitated carrier 110 may be moved in the first direction 192 by the magnetic drive structure 180.

[0031] The apparatus 100 includes a control unit 130. The control unit 130 may be connected to the plurality of magnetic units 170 and/or to the distance sensors. The control unit 130 may be configured for controlling the magnetic levitation of the carrier 110. The control unit 130 may be configured for controlling the distance between the carrier 110 and the plurality of magnetic units 170 during levitation of the carrier 110, e.g. based on measured distances supplied to the control unit 130 by the distance sensors. The magnetic drive structure 180 may drive the carrier 110 under the control of the control unit 130.

[0032] According to embodiments, which can be combined with other embodiments described herein, a control unit may include a plurality of controllers, e.g. a plurality of local controllers. Each controller of the plurality of controllers may be connected to and/or provided at a respective magnetic unit of the plurality of magnetic units 170. A controller of the plurality of controllers may be configured for controlling a distance between the carrier 110 and a magnetic unit during levitation of the carrier 110, e.g. based on a measured distance supplied to the controller by a distance sensor provided at the magnetic unit.

[0033] Embodiments described herein provide for a method for determining an alignment of a carrier levitation system including a plurality of magnetic units 170. Embodiments described herein further allow determining an alignment of a mechanical support 140 and of a magnetic drive structure 180. Embodiments of the method may be carried out by the control unit 130 or by a further control unit of the apparatus.

[0034] Figs. 2a-b show a plurality of magnetic units 170 adapted for contactlessly levitating a carrier 110 according to embodiments described herein. Figs. 2a-b show a magnetic drive structure 180 including a further plurality of magnetic units for driving the carrier 110 in a carrier transport direction. The plurality of magnetic units 170 are arranged in a first direction 192. The magnetic drive structure 180 is arranged in the first direction 192. The plurality of magnetic units 170 and the further plurality of magnetic units of the magnetic drive structure 180 are schematically depicted as rectangles. A carrier 110, indicated by dashed lines, may be contactlessly levitated and/or transported by the plurality of magnetic units 170.

[0035] The magnetic units of the plurality of magnetic units 170 shown in Fig. 2a are well aligned. The magnetic units of the magnetic drive structure 180 shown in Fig. 2a are well aligned. For example, the rectangles depicting the plurality of magnetic units 170 all have the same angular orientation and the bottom edge of each of the rectangles aligns with a first reference line 212 extending in the first direction 192. The first reference line 212 indicates a target alignment for the plurality of magnetic units 170. The rectangles depicting the plurality of magnetic units of the magnetic drive structure 180 all have the same angular orientation and the top edge of each of the rectangles aligns with a second reference line 222 extending in the first direction 192. The second reference line 222 indicates a target alignment for the magnetic drive structure.

[0036] For the plurality of magnetic units 170 and the magnetic drive structure 180 shown in Fig. 2b, a misalignment is present. As shown, the bottom edges of some of the plurality of magnetic units 170 are not aligned with the first reference line 212 but are at an angle with respect to the first reference line 212 and/or are at a distance from the first reference line 212. The top edges of some of the magnetic units of the magnetic drive structure 180 are not aligned with the second reference line 222 but are at an angle with respect to the second reference line 222 and/or are at a distance from the second reference line 222. The misalignment shown in Fig. 2b is depicted in an exaggerated way for easier understanding.

[0037] To determine the alignment of a carrier levitation system according to embodiments described herein, measurements using laser trackers or precision scales may be used. Such measurements may be complex and time-consuming. It may be difficult with such methods to reach the measuring points for gathering the required date regarding the positions of the magnetic units.

[0038] Figs. 3a-b illustrate a method for determining an alignment of a carrier levitation system according to embodiments described herein.

[0039] Figs. 3a-b show a carrier 110. The carrier 110 may, e.g., be adapted for supporting a substrate or mask. Other types of carriers may also be considered. The apparatus shown in Figs. 3a-b includes a carrier levitation system including a plurality of magnetic units 170.

[0040] According to embodiments, which can be combined with other embodiments described herein, a carrier levitation system may be adapted for contactlessly levitating and/or transporting the carrier 110. The carrier levitation system may be adapted for transporting the carrier 110 in a first direction 192. [0041] The plurality of magnetic units 170 includes a first magnetic unit 312 and a second magnetic unit 314. In some embodiments, the plurality of magnetic units 170 may include further magnetic units, e.g. magnetic units 316 indicated with dashed lines. The plurality of magnetic units 170 may be arranged in the first direction 192. The plurality of magnetic units 170 are adapted for contactlessly levitating the carrier 110.

[0042] As shown in Figs. 3a-b, a first distance 322 from the first magnetic unit 312 to the carrier 110 is measured. The first distance 322 may be measured by a first distance sensor (not shown) provided at the first magnetic unit 312. A second distance 324 from the second magnetic unit 314 to the carrier 110 is measured. The second distance 324 may be measured by a second distance sensor (not shown) provided at the second magnetic unit 314. One or more further distances from the plurality of magnetic units 170 to the carrier 110 may be measured. A third distance from a third magnetic unit, e.g. one of the magnetic units 316, to the carrier 110 may be measured. The third distance may be measured by a third distance sensor provided at the third magnetic unit. A fourth distance from a fourth magnetic unit of the plurality of magnetic units 170 to the carrier 110 may be measured. The fourth distance may be measured by a fourth distance sensor provided at the fourth magnetic unit. Even further distances from the plurality of magnetic units 170 to the carrier 110 may be measured.

[0043] In the exemplary embodiment shown in Fig. 3a, the first distance 322 and the second distance 324 are measured while the carrier 110 is in a state of magnetic levitation. The carrier 110 shown in Fig. 3a is contactlessly levitated by the carrier levitation system, as indicated by the upward arrow 390. There is no mechanical contact between the carrier 110 and other parts of the apparatus, e.g. mechanical support 140. The carrier 110 shown in Fig. 3a is not mechanically supported.

[0044] As shown in Fig. 3a, the first distance 322 and the second distance 324 may be measured while the carrier 110 is magnetically levitated by the first magnetic unit 312 and the second magnetic unit 314. In the exemplary embodiment illustrated in Fig. 3a, the carrier 110 is contactlessly levitated by the first magnetic unit 312 and the second magnetic unit 314 jointly. In other embodiments, e.g. depending on the application considered, the carrier 110 may be contactlessly levitated by a single magnetic unit or by more than two magnetic units of the plurality of magnetic units 170.

[0045] The carrier 110 need not be in a state of magnetic levitation for measuring the first distance 322 and the second distance 324. For example, as shown in Fig. 3b, the first distance 322 and the second distance 324 may be measured while the carrier 110 is mechanically supported.

[0046] The apparatus shown in Fig. 3b includes a mechanical support 140. The mechanical support 140 may include a plurality of support elements 142. The carrier 110 shown in Fig. 3b is mechanically supported by the mechanical support 140. The carrier 110 shown in Fig. 3b is not in a state of contactless levitation. In the exemplary embodiment shown in Fig. 3b, the first distance 322 and the second distance 324 are measured while the carrier 110 is supported by the mechanical support 140.

[0047] The first distance 322 and the second distance 324, and any further distance from the plurality of magnetic units 170 to the carrier 110 measured according to embodiments described herein, provide information regarding the alignment of the plurality of magnetic units 170. For example, if the first distance 322 is substantially the same as the second distance 324, it may be determined that the first magnetic unit 312 and the second magnetic unit 314 are well aligned, e.g. as shown in Fig. 2a. If the first distance 322 is substantially different from the second distance 324, it may be the case that a misalignment exists, e.g. as shown in Fig. 2b. Using the measured distances, a possible misalignment can be detected.

[0048] In light of the above, a method for determining an alignment of a carrier levitation system is provided. The carrier levitation system includes a plurality of magnetic units 170. The plurality of magnetic units 170 are adapted for contactlessly levitating a carrier 110. The plurality of magnetic units 170 includes a first magnetic unit 312 and a second magnetic unit 314. The method includes measuring a first distance 322 from the first magnetic unit 312 to the carrier 110. The method includes measuring a second distance 324 from the second magnetic unit 314 to the carrier 110. The method includes determining, from at least the first distance 322 and the second distance 324, an alignment of the carrier levitation system.

[0049] For example, the method may be performed according to the embodiments described in relation to Figs. 3a-b. According to embodiments, which can be combined with other embodiments described herein, the method may include contactlessly levitating the carrier 110 by the carrier levitation system. The first distance 322 and the second distance 324 may be measured while the carrier 110 is contactlessly levitated. Alternatively or additionally, the method may include mechanically supporting the carrier by a mechanical support 140. The first distance 322 and the second distance 324 may be measured while the carrier is mechanically supported. [0050] According to a further embodiment, a method for determining an alignment of a carrier levitation system is provided. The carrier levitation system includes a plurality of magnetic units 170. The plurality of magnetic units 170 are adapted for contactlessly levitating a carrier 110. The plurality of magnetic units 170 includes a first magnetic unit 312 and a second magnetic unit 314. The method may include contactlessly levitating the carrier 110 by one or more magnetic units of the plurality of magnetic units 170. The method includes measuring a first distance 322 from the first magnetic unit 312 to the carrier 110 while the carrier is contactlessly levitated by at least the first magnetic unit 312. The method includes measuring a second distance 324 from the second magnetic unit 314 to the carrier 110 while the carrier is contactlessly levitated by at least the second magnetic unit 314. The method includes determining, from at least the first distance 322 and the second distance 324, an alignment of the carrier levitation system.

[0051] According to a further embodiment, a method for determining an alignment of a carrier levitation system is provided. The carrier levitation system includes a plurality of magnetic units 170. The plurality of magnetic units 170 is adapted for contactlessly levitating a carrier 110. The plurality of magnetic units 170 includes a first magnetic unit 312 and a second magnetic unit 314. The method may include mechanically supporting the carrier 110 by a mechanical support 140. The method includes measuring a first distance 322 from the first magnetic unit 312 to the carrier 110 while the carrier 110 is mechanically supported by a mechanical support 140. The method includes measuring a second distance 324 from the second magnetic unit 314 to the carrier 110 while the carrier 110 is mechanically supported by the mechanical support 140. The method includes determining, from at least the first distance 322 and the second distance 324, an alignment of the mechanical support 140 and/or of the carrier levitation system.

[0052] Embodiments described herein involve using the carrier itself for determining the alignment of the carrier levitation system and/or of the mechanical support.

[0053] An advantage is that additional devices such as laser trackers, reflectors or inclination sensors for measuring the alignment are not required. The methods described herein provide for a simple and efficient method which is less complex and time-consuming as compared to other methods, such as e.g. methods using laser measurements.

[0054] The distances from the magnetic units to the carrier 110 may be measured using distance sensors. For example, distance sensors may be present in or at the plurality of magnetic units 170 for assisting in the control of magnetic levitation processes carried out by the apparatus. The same distance sensors may also be used for measuring, e.g., the first distance 322 and the second distance 324 according to embodiments described herein. In some cases, no additional distance sensors apart from those already present in the system for controlling the contactless levitation may be needed for determining the alignment of the plurality of magnetic units 170. According to embodiments, which can be combined with other embodiments described herein, the first distance 322 may be measured by a first distance sensor provided at the first magnetic unit 312. The second distance 324 may be measured by a second distance sensor provided at the second magnetic unit 314. The method may include using the first distance sensor and/or the second distance sensor for controlling the contactless levitation of the carrier 110 or a further carrier.

[0055] Since the method described herein is easy to carry out, the method may be performed periodically on a regular basis, to ensure that the magnetic units are well aligned over longer periods of time. After performing a first alignment, at some point the alignment of the magnetic units may deteriorate. This may happen, e.g., in light of small movements of the components of the system with respect to each other over time, e.g. as a result of repeatedly switching a vacuum on and off over different process cycles. Such small movements of the components may have an effect on the alignment of the magnetic units, e.g. in light of the fact that, during contactless levitation, the distance from the carrier to the magnetic units is very small, such as e.g. from 1 to 8 mm, more particularly from 1 to 4 mm, e.g. from 2 to 3 mm. It is beneficial to provide a high-precision alignment of the magnetic units on a regular basis. The method described herein, being simple and efficient, allows doing so. Other methods based on e.g. laser trackers are complex and involved, so that it is disadvantageous to carry them out frequently.

[0056] By determining an alignment according to embodiments described herein, misalignments, e.g. as shown in Fig. 2b, can be avoided. With well aligned magnetic units, a good operation of the contactless levitation and transportation of the carrier can be ensured and any disadvantageous effects of misaligned magnetic units are avoided. For example, such disadvantageous effects may include collisions of the levitated carrier with a misaligned magnetic unit (in light of the small distances between the levitated carrier and the carrier levitation system), which may lead to particle generation or damage to the carrier or to the magnetic units. Other disadvantageous effects of misaligned magnetic units include saturation effects in the control of the magnetic levitation process, which in the worst case may cause the levitated carrier to fall down. Embodiments described herein ensure that an accurate positioning of the carrier during contactless levitation is provided.

[0057] A further advantage is that embodiments involving a measurement of the distances from the magnetic units to the carrier 110 while the carrier 110 is mechanically supported allow determining the alignment of the mechanical support 140 relative to the plurality of magnetic units 170. The mechanical support 140, e.g. a plurality of retainer bearings, may be mechanically connected, e.g. mounted to, the magnetic drive structure 180. For example, the support elements of the mechanical support 140 may be fixed to the magnetic drive structure 180. In light of the mechanical connection between the mechanical support 140 and the magnetic drive structure 180, determining the alignment of the mechanical support 140 may allow determining the alignment of the magnetic units of the magnetic drive structure 180. Embodiments described herein allow determining the relative alignment of all components involved in the contactless levitation and transportation of the carrier in the apparatus.

[0058] Embodiments involving a measurement of the distances from the magnetic units to the carrier 110 while the carrier 110 is mechanically supported further provide the advantage that such embodiments may be carried out even in the case of a substantial misalignment of the magnetic units. In such a case, a measurement of the first distance 322 and the second distance 324 while the carrier 110 is contactlessly levitated may be difficult. For example, in the case of a substantial misalignment, it may not be possible to contactlessly levitate the carrier due to e.g. saturation effects in the levitation control circuit. Embodiments involving a measurement of the first distance 322 and the second distance 324 while the carrier is mechanically supported may be carried out even in the case of a substantial degree of misalignment of the magnetic units.

[0059] A further advantage is that the methods described herein may be performed under vacuum conditions. The latter is not feasible for some other methods, e.g. methods based on laser measurements or inclination sensors. The advantage of measuring the first distance 322 and the second distance 324 under vacuum conditions is that effects resulting from the vacuum conditions, such as e.g. deformations of the magnetic units or of other components of the system, can be taken into account for determining the alignment of the carrier levitation system and/or of the mechanical support. In other words, the alignment can be determined under the same process conditions as those which are present when vacuum processing e.g. a substrate in a carrier levitated by the magnetic units. [0060] According to embodiments, which can be combined with other embodiments described herein, the first distance 322, the second distance 324 and/or any other distance from a carrier to a magnetic unit according to embodiments described herein may be measured under vacuum conditions. The distances may be measured while a vacuum is applied in a processing chamber containing the carrier. The term "vacuum" can be understood in the sense of a technical vacuum having a vacuum pressure of less than, for example, 10 mbar. An apparatus according to embodiments described herein may include one or more vacuum pumps, such as turbo pumps and/or cryo-pumps, connected to a vacuum chamber for generation of a vacuum inside the vacuum chamber.

[0061] Embodiments described herein involve determining an alignment of the carrier levitation system. Determining the alignment of the carrier levitation system may involve comparing the measured position of a magnetic unit with the measured position of one or more further magnetic units or with one or more reference positions.

[0062] According to embodiments, which may be combined with other embodiments described herein, determining an alignment of the carrier levitation system may include at least one of: determining a relative alignment of two or more magnetic units of the plurality of magnetic units 170; determining a relative alignment of the first magnetic unit 312 with respect to the second magnetic unit 314; determining a relative alignment of the first magnetic unit 312 with respect to a further magnetic unit of the plurality of magnetic units 170; determining a relative alignment of the second magnetic unit 314 with respect to a further magnetic unit of the plurality of magnetic units 170; determining an alignment of the first magnetic unit 312, the second magnetic unit 314, or any further magnetic unit of the plurality of magnetic units 170, with respect to one or more reference positions; and comparing the first distance 322, the second distance 324 and/or any further distance from a magnetic unit to the carrier 110 to a reference distance.

[0063] According to embodiments, which may be combined with other embodiments described herein, determining an alignment of the carrier levitation system may include calculating, from at least the first distance 322 and the second distance 324, a reference value for a distance from the carrier 110 to a magnetic unit of the plurality of magnetic units 170. The reference value may be calculated by an averaging operation. The reference value may be calculated by averaging over two or more measured distances from the plurality of magnetic units to the carrier. For example, the reference value may be calculated by averaging over at least the first distance and the second distance.

[0064] According to embodiments, which may be combined with other embodiments described herein, determining an alignment of the carrier levitation system may include comparing the first distance 322, the second distance 324, and optionally a third distance and/or any further measured distance to the calculated reference value. By comparing the measured distances to the calculated reference value, it can be determined whether the magnetic units are well aligned and, in the case of a potential misalignment, how large the respective deviations are.

[0065] A misalignment of the carrier levitation system may be corrected in several possible ways. For example, the position of the first magnetic unit 312 and/or the second magnetic unit 314 can be mechanically adjusted for aligning the plurality of magnetic units 170. According to embodiments, which can be combined with other embodiments described herein, the method may include performing an alignment operation to the carrier levitation system and/or to the magnetic drive structure. An alignment operation may be a mechanical alignment operation. An alignment operation to the carrier levitation system may include adjusting, at least in part based on the determined alignment, a position of at least one magnetic unit of the plurality of magnetic units of the carrier levitation system. An alignment operation to the magnetic drive structure may include adjusting, at least in part based on the determined alignment, a position of at least one magnetic unit of the plurality of magnetic units of the magnetic drive structure.

[0066] For example, the positions of one or more magnetic units may be adjusted so that, after adjustment, the magnetic units are aligned with the first reference line 212 or the second reference line 222, respectively, as shown in Fig. 2a.

[0067] In an alternative example, the positions of the magnetic units may not be changed. The control of the carrier levitation system in a subsequent contactless levitation or transportation of a carrier, e.g. in a coating process taking place after the first distance 322 and the second distance 324 have been measured, may take the measured values for the first distance 322 and the second distance 324 into account to compensate for a detected misalignment. For example, depending on the measured values for the first distance 322 and the second distance 324, a control unit may individually control the distances from the respective magnetic units to a levitated carrier in a subsequent levitation process to compensate for the detected misalignment.

[0068] According to other embodiments, which can be combined with further embodiments described herein, the method may include contactlessly levitating the carrier or a further carrier by the plurality of magnetic units. The method may include controlling, at least in part based on the determined alignment, a first levitation distance and a second levitation distance. The first levitation distance may be a distance from the first magnetic unit to the contactlessly levitated carrier, e.g. the carrier 110 or a further carrier. The second levitation distance may be a distance from the second magnetic unit to the contactlessly levitated carrier. The controlling may include individually controlling the first levitation distance and the second levitation distance. The controlling may include setting a first target value for the first levitation distance and setting a second target distance for the second levitation distance. The first target value may be different from the second target value.

[0069] Individually controlling the distances from the magnetic units to the carrier during contactless levitation to compensate for a detected misalignment provides the advantage that, e.g., saturation effects in the control of the magnetic levitation process can be reduced or even prevented, allowing for a larger bandwidth. A more accurate levitation process can be provided.

[0070] Fig. 4 illustrates a method for determining an alignment of a carrier levitation system according to embodiments described herein.

[0071] As illustrated in Fig. 4, the first distance 322 from the first magnetic unit 312 to the carrier 110 may be measured while the carrier 110 is in a first position 532. The second distance 324 from the second magnetic unit 314 to the carrier 110 may be measured while the carrier 110 is in the first position 532. The first distance 322 and the second distance 324 may be measured while the carrier 110 is in a same position.

[0072] According to embodiments, which can be combined with further embodiments described herein, the first magnetic unit 312 and/or the second magnetic unit 314 may face the carrier 110 in the first position. The first position may be a position in a processing chamber. The carrier 110 may be held in the first position in a mechanically supported state. The carrier 110 in the first position may be mechanically supported by a mechanical support 140 according to embodiments described herein. [0073] Alternatively or additionally, the carrier 110 may be held in the first position in a magnetically levitated state. The carrier 110 in the first position may be contactlessly levitated by at least one magnetic unit of the plurality of magnetic units 170. The number of magnetic units used to magnetically levitate the carrier 110 in the first position may depend on several factors, e.g. the size, dimensions and weight of the carrier.

[0074] Figs. 5a-b illustrate a method for determining an alignment of a carrier levitation system according to embodiments described herein.

[0075] According to other embodiments, and as illustrated in Figs. 5a-b, the first distance 322 and the second distance 324 can be measured at different positions of the carrier 110. Fig. 5a illustrates measuring the first distance 322 while the carrier 110 is in a first position 532. While the first distance 322 is measured, the carrier 110 in the first position 532 may be magnetically levitated or mechanically supported according to embodiments described herein. For example, the carrier in the first position 532 may be magnetically levitated by the first magnetic unit 312. After measuring the first distance 322, the carrier 110 may be moved from the first position 532 shown in Fig. 5a to a second position 534 shown in Fig. 5b.

[0076] Fig. 5b illustrates measuring the second distance 324 while the carrier 110 is in a second position 534. While the second distance 324 is measured, the carrier 110 in the second position 534 may be magnetically levitated or mechanically supported according to embodiments described herein. For example, the carrier in the second position 534 may be magnetically levitated by the second magnetic unit 314.

[0077] According to embodiments, which can be combined with other embodiments described herein, the first distance 322 from the first magnetic unit 312 to the carrier 110 may be measured while the carrier 110 is in a first position 532. The second distance 324 from the second magnetic unit 314 to the carrier 110 may be measured while the carrier 110 is in a second position 534.

[0078] The carrier 110 may be moved from the first position 532 to the second position 534, e.g. after measuring the first distance. The movement from the first position 532 to the second position 534 may be a movement in the first direction 192. The movement from the first position 532 to the second position 534 may be a translational movement. The movement from the first position 532 to the second position 534 may be provided by and/or guided by a magnetic drive structure. Alternatively or additionally, the movement from the first position 532 to the second position 534 may be provided by and/or guided by a mechanical support.

[0079] The first magnetic unit 312 and/or the second magnetic unit 314 may face the carrier in the second position 534. The second position 534 may be a position in a processing chamber. The carrier 110 in the second position may be mechanically supported by a mechanical support. Alternatively or additionally, the carrier 110 in the second position 534 may be contactlessly levitated by the carrier levitation system.

[0080] For example, while the carrier 110 is in the first position 532, one, two, three or more magnetic units of the plurality of magnetic units 170 may face the carrier 110. The number of magnetic units facing the carrier 110 may depend, e.g., on the spacing between the magnetic units and the length of the carrier 110. The method may include measuring the distance from each magnetic unit facing the carrier in the first position to the carrier in the first position.

[0081] For example, while the carrier 110 is in the second position 534, two, three or more magnetic units of the plurality of magnetic units may face the carrier 110. The method may include measuring the distance from each magnetic unit facing the carrier 110 in the second position 534 to the carrier 110 in the second position 534.

[0082] Figs. 6a-c show an apparatus 500 including a plurality of magnetic units 170 according to embodiments described herein. In the exemplary embodiment, the plurality of magnetic units 170 includes magnetic units 512, 514, 516 and 518. The apparatus 500 includes a processing chamber 550.

[0083] Fig. 6a shows a carrier 110 in a first position 532. Two magnetic units 512 and 514 face the carrier 110 in the first position 532. The distance 521 from magnetic unit 512 to the carrier 110 in the first position 532 is measured. The distance 522 from magnetic unit 514 to the carrier 110 in the first position 532 is measured. After the distances 521 and 522 are measured, the carrier 110 is moved from the first position 532 shown in Fig. 6a to a second position 534 as shown in Fig. 6b.

[0084] Fig. 6b shows two magnetic units 514 and 516 facing the carrier 110 in the second position 534. The distance 523 from magnetic unit 514 to the carrier 110 in the second position 534 is measured. The distance 524 from magnetic unit 516 to the carrier 110 in the second position 534 is measured. After the distances 523 and 524 are measured, the carrier 110 may be moved from the second position 534 shown in Fig. 6b to a third position 536 as shown in Fig. 6c.

[0085] Fig. 6c shows two magnetic units 516 and 518 facing the carrier 110 in the third position 536. The distance 525 from magnetic unit 516 to the carrier 110 in the third position 536 is measured. The distance 526 from magnetic unit 518 to the carrier 110 in the third position 536 is measured.

[0086] The distances 521, 522, 523, 524, 525 and 526 may be measured while the carrier 110 is contactlessly levitated by the carrier levitation system or while the carrier 110 is mechanically supported by a mechanical support. The measured distances 521, 522, 523, 524, 525 and 526 may be collected in a table. The measured distances 521, 522, 523, 524, 525 and 526, or any combination thereof, may be used for determining the alignment of the carrier levitation system and/or of the mechanical support according to embodiments described herein.

[0087] According to embodiments, which may be combined with other embodiments described herein, the method may include providing the carrier 110 in a processing chamber, e.g. processing chamber 550 shown in Figs. 6a-c.

[0088] The carrier levitation system, the first magnetic unit 312, the second magnetic unit 314, and/or the plurality of magnetic units 170 may be in the processing chamber. The mechanical support 140 may be in the processing chamber. The first distance sensor 732, the second distance sensor 734 and/or any further distance sensor according to embodiments described herein may be in the processing chamber.

[0089] The method may include measuring the first distance 322 from the first magnetic unit 312 to the carrier 110, the second distance 324 from the second magnetic unit 314 to the carrier 110, and/or any other distance from a magnetic unit to the carrier 110, while the carrier 110 is in a processing chamber.

[0090] A processing chamber may be a vacuum chamber. A processing chamber may be a vacuum deposition chamber. A processing chamber may include one or more deposition sources for coating a substrate in the processing chamber.

[0091] According to embodiments, which can be combined with other embodiments described herein, the method may include measuring a third distance from the plurality of magnetic units 170 to the carrier 110. The third distance may be a distance from the first magnetic unit 312 to the carrier 110, a distance from the second magnetic unit 314 to the carrier 110, or a distance from a third magnetic unit of the plurality of magnetic units 170 to the carrier 110. The method may include determining, from at least the first distance, the second distance and the third distance, an alignment of the carrier levitation system and/or of the mechanical support.

[0092] According to embodiments, which can be combined with other embodiments described herein, the method may include measuring a plurality of distances from the plurality of magnetic units 170 to the carrier 110. Each distance of the plurality of distances may be a distance from a magnetic unit of the plurality of magnetic units 170 to the carrier 110. The plurality of distances may include the first distance 322, the second distance 324, a third distance, a fourth distance, a fifth distance and even further distances. The plurality of distances may include two, three, four, five or more distances, e.g. up to 20 or even more distances. The method may include determining, from the plurality of distances, an alignment of the carrier levitation system and/or of the mechanical support. The method may include determining an alignment of the carrier levitation system and/or of the mechanical support from at least two or more distances, at least three or more distances, at least four or more distances or at least five or more distances of the plurality of distances.

[0093] According to embodiments, which can be combined with other embodiments described herein, a plurality of magnetic units 170 may include a third magnetic unit. The method may include measuring a third distance from the third magnetic unit to the carrier. The third distance may be measured while the carrier in the first position 532 or in the second position 534 according to embodiments described herein. An alignment of the carrier levitation system and/or of the mechanical support may be determined from at least the first distance, the second distance and the third distance, or a combination thereof.

[0094] According to embodiments, which can be combined with other embodiments described herein, a plurality of magnetic units 170 may include 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12 or more, e.g. up to 24 or more, magnetic units. The plurality of magnetic units 170 may include two rows of magnetic units, e.g. two rows of up to 12 or more magnetic units.

[0095] According to embodiments, which can be combined with other embodiments described herein, the method may include measuring a plurality of distances. A distance from each magnetic unit of the plurality of magnetic units to the carrier may be measured. The method may include determining, from the plurality of measured distances, an alignment of the carrier levitation system and/or of the mechanical support.

[0096] According to embodiments, which can be combined with other embodiments described herein, the first distance from the first magnetic unit to the carrier and the second distance from the second magnetic unit to the carrier may be measured while the carrier is in the first position 532. The method may include measuring a third distance from the second magnetic unit to the carrier while the carrier is in a second position 534. For example, the first magnetic unit and the first distance according to embodiments described herein may correspond to the magnetic unit 512 and the distance 521, respectively, shown in Figs. 6a. The second magnetic unit, the second distance and the third distance according to embodiments described herein may correspond to the magnetic unit 514, the distance 522 and the distance 523, respectively, shown in Figs. 6a-b. The method may include determining, from at least the first distance, the second distance and the third distance, or a combination thereof, the alignment of the carrier levitation system and/or of the mechanical support.

[0097] According to embodiments, which can be combined with other embodiments described herein, the first distance from the first magnetic unit to the carrier, e.g. distance 521 shown in Fig. 6a, and/or the second distance from the second magnetic unit to the carrier, e.g. distance 522, may be measured while the second magnetic unit is in the first position. The plurality of magnetic units may include a third magnetic unit, e.g. magnetic unit 516 shown in Figs. 6a-c. The method may include measuring a third distance from the third magnetic unit to the carrier, e.g. distance 524 shown in Fig. 6b, while the carrier is in a second position 534. The method may include measuring a fourth distance from the second magnetic unit to the carrier, e.g. distance 523 shown in Fig. 6b, while the carrier is in the second position. The method may include determining, from at least the first distance, the second distance, the third distance, and the fourth distance, or a combination thereof, the alignment of the carrier levitation system and/or of the mechanical support.

[0098] By measuring several distances from a same magnetic unit to the carrier for different positions of the carrier, more information regarding the alignment of the magnetic units can be obtained as compared to a method in which, e.g., only one distance is measured for each magnetic unit. Accordingly, the alignment or potential misalignment can be determined more accurately. [0099] According to embodiments, which can be combined with other embodiments described herein, the carrier 110 used in the method described herein is a carrier configured, e.g. specifically configured, for measuring the distances from the plurality of magnetic units to the carrier. The carrier 110 used in the method described herein may be a measurement carrier. A measurement carrier may be a carrier of a different type as compared to a process carrier, i.e. a carrier levitated by the carrier levitation system in a process, e.g. a deposition process. For example, a measurement carrier 110 may be more accurately manufactured as compared to a process carrier. A measurement carrier may have different dimensions, e.g. height and/or length, as compared to a process carrier. A measurement carrier may be longer or shorter than a process carrier. A measurement carrier may have an adjustable size, e.g. an adjustable length and/or height.

[00100] According to embodiments, which can be combined with other embodiments described herein, the method described herein may be repeated several times using different carriers.

[00101] For example, in a first round, a carrier, e.g. a measurement carrier, of a relatively small size can be used. Particularly, the height of the carrier may be relatively small as compared to a process carrier, so that the distance from the carrier to the carrier levitation system is larger than for a process carrier. This may ensure that the carrier, when moving through the system, does not touch or collide with the magnetic units or other components of the system, particularly in the case of a plurality of magnetic units which have a relatively large degree of misalignment. For such carriers, the distances from the magnetic units to the carrier may be measured and the alignment may be determined according to embodiments described herein. After determining the alignment of the magnetic units based on the distances measured in the first round, a mechanical alignment operation may be applied to the carrier levitation system. For example, the positions of some of the magnetic units may be adjusted to align the carrier levitation system. After the alignment operation, a second round of the method may be performed. In a second round, for example, a second carrier having a relatively larger size can be used. The carrier with the larger size may not collide with the magnetic units, since the latter have already undergone a first round of alignment. For such second carriers, distances from the magnetic units to the carrier may also be measured as described herein. The alignment may be determined a second time based on these distances. By repeating the method several times, in each round of the method the alignment of the carrier levitation system and/or the mechanical support can be further improved. [00102] According to embodiments, which can be combined with other embodiments described herein, the carrier 110 is a first carrier. The method may include measuring a third distance from the first magnetic unit to a second carrier, the second carrier having a different size than the first carrier. The method may include measuring a fourth distance from the second magnetic unit to the second carrier. The method may include determining, from at least the third distance and the fourth distance, an alignment of the carrier levitation system and/or of the mechanical support.

[00103] A measured distance from a magnetic unit to the carrier according to embodiments described herein may be a distance in a vertical direction, e.g. second direction 194. For example, the first distance 322 and/or the second distance 324 may be a distance in the second direction 194. The first distance 322, the second distance 324, or any further distance from a magnetic unit to a carrier may be a distance in a direction perpendicular or substantially perpendicular to the first direction 192.

[00104] A measured distance from a magnetic unit to the carrier may be a distance from the magnetic unit to an outer portion of the carrier, e.g. an upper edge portion of the carrier.

[00105] The first distance, the second distance, and/or any further distance from a magnetic unit to the carrier 110 measured according to embodiments described herein, may be measured while the carrier is held in a vertical orientation.

[00106] The first distance 322, the second distance 324, or any other distance from a magnetic unit to a carrier 110 measured according to embodiments described herein may be from 1 to 8 mm, more particularly from 1 to 4 mm, e.g. from 2 to 3 mm.

[00107] The first distance 322 may be measured by a first distance sensor, e.g. first distance sensor 732 shown in Fig. 7. While the first distance 322 is measured, the first distance sensor may be above the carrier 110 and/or face the carrier 110. The first distance sensor may be connected to, mounted to and/or part of the first magnetic unit 312. The second distance 324 may be measured by a second distance sensor, e.g. second distance sensor 734 shown in Fig. 7. While the second distance 324 is measured, the second distance sensor 734 may be above the carrier 110 and/or face the carrier 110. The second distance sensor 734 may be connected to, mounted to and/or part of the second magnetic unit 314.

[00108] According to embodiments, which can be combined with other embodiments described herein, the method may include measuring a plurality of distances, particularly a plurality of vertical distances, from the magnetic drive structure 180 to the carrier 110. A plurality of distance sensors may be provided at or mounted to the magnetic drive structure 180 for measuring the plurality of distances from the magnetic drive structure 180 to the carrier 110. The plurality of distance sensors may be arranged below the carrier 110, e.g. while the carrier 110 is levitated and/or while the carrier 110 is supported by the mechanical support 140. The plurality of distance sensors may be spaced apart from each other in the first direction 192. The method may include determining, from at least the first distance 322, the second distance 324 and the plurality of distances from the magnetic drive structure 180 to the carrier, an alignment of the mechanical support 140.

[00109] According to a further embodiment, and as illustrated in Fig. 7, an apparatus 500 is provided. The apparatus 500 includes a carrier levitation system including a plurality of magnetic units 170, the plurality of magnetic units 170 being adapted for contactlessly levitating a carrier 110. The plurality of magnetic units 170 includes a first magnetic unit 312 and a second magnetic unit 314. The apparatus 500 includes a first distance sensor 732. The first distance sensor 732 may be adapted for measuring a first distance 322 from the first magnetic unit 312 to the carrier 110. The apparatus 500 includes a second distance sensor 734. The second distance sensor 734 may be adapted for measuring a second distance 324 from the second magnetic unit 314 to the carrier 110. The apparatus 500 includes a control unit 750 connected to the first distance sensor 732 and to the second distance sensor 734. The control unit 750 is configured for determining, from at least the first distance 322 and the second distance 324, an alignment of the carrier levitation system.

[00110] The first distance 322 and the second distance 324 shown in Fig. 7 may be measured while the carrier 110 is contactlessly levitated by the carrier levitation system or mechanically supported by a mechanical support included in the apparatus 500.

[00111] Embodiments of the apparatus described herein are adapted for performing any of the method features of embodiments of the method described herein, particularly any of the features described in the dependent method claims. A control unit as described herein may be adapted for performing any of the method features of embodiments of the methods described herein, particularly any of the features described in the dependent method claims. For example, the control unit 750 may be configured for performing the method feature of determining alignment of the carrier levitation system and/or of the mechanical support according to any of the embodiments described herein. [00112] According to embodiments, which can be combined with other embodiments described herein, the first magnetic unit 312, the second magnetic unit 314 and/or any magnetic unit of the plurality of magnetic units 170 may be an active magnetic unit.

[00113] According to embodiments, which can be combined with other embodiments described herein, an active magnetic unit may be configured for generating a magnetic field for providing a magnetic levitation force extending in a vertical direction, e.g. second direction 194 shown in the figures. An active magnetic unit can be controlled to provide an adjustable magnetic field. The adjustable magnetic field may be a static or a dynamic magnetic field. An active magnetic unit may be or include an element selected from the group consisting of: an electromagnetic device; a solenoid; a coil; a superconducting magnet; or any combination thereof.

[00114] The terminology of an "active" magnetic unit is used herein to distinguish from the notion of a "passive" magnetic unit. A passive magnetic unit may refer to an element with magnetic properties, which are not subject to active control or adjustment, at least not during operation of the apparatus. For example, the magnetic properties of a passive magnetic unit, e.g. the first passive magnetic unit 150 or the second passive magnetic unit 160 shown in Fig. 1, may not be subject to active control during movement of the carrier through the apparatus. A passive magnetic unit may be a magnetic material, such as a ferromagnetic material, a permanent magnet or may have permanent magnetic properties.

[00115] As compared to a passive magnetic unit, an active magnetic unit offers more flexibility and precision in light of the adjustability and controllability of the magnetic field generated by the active magnetic unit.

[00116] Fig. 8 shows an apparatus 500 according to embodiments described herein. The apparatus 500 includes a carrier levitation system including a plurality of magnetic units 170. The plurality of magnetic units 170 includes a first magnetic unit 312, a second magnetic unit 314, a third magnetic unit 816 and a fourth magnetic unit 818. The apparatus 500 includes a first distance sensor 732, a second distance sensor 734, a third distance sensor 836 and a fourth distance sensor 838. The apparatus 500 includes a control unit 750. The apparatus 500 includes a mechanical support 140. The apparatus includes a magnetic drive structure 180.

[00117] According to embodiments, which may be combined with other embodiments described herein, the first distance sensor 732 may be connected to the first magnetic unit 312. The second distance sensor 734 may be connected to the second magnetic unit 314. The third distance sensor 836 may be connected to the third magnetic unit 816. The fourth distance sensor 838 may be connected to the fourth magnetic unit 818.

[00118] The control unit 750 may be connected to the first distance sensor 732, the second distance sensor 734, the third distance sensor 836 and/or the fourth distance sensor 838. The control unit 750 may be configured for determining, from two or more distances from the magnetic units to the carrier measured by the distance sensors of the apparatus 500, an alignment of the carrier levitation system and/or of the mechanical support 140.

[00119] In the exemplary embodiment shown in Fig. 8, the first distance 322 and the second distance 324 are measured while the carrier 110 is supported by the mechanical support 140. The same apparatus 500 may also be used for measuring the first distance and the second distance, and any other distance from a magnetic unit to the carrier according to embodiments described herein, while the carrier 110 is contactlessly levitated.

[00120] According to embodiments, which may be combined with other embodiments described herein, the apparatus 500 may include a magnetic drive structure 180 for driving the carrier in a carrier transport direction 192. The magnetic drive structure 180 may include a plurality of magnetic units, e.g. active magnetic units 185 shown in Fig. 8. According to embodiments, which can be combined with embodiments described herein, an active magnetic unit may be configured for providing a magnetic driving force extending in the first direction 192.

[00121] According to embodiments, which may be combined with other embodiments described herein, the apparatus 500 may include a mechanical support 140. A mechanical support 140 may be adapted for mechanically supporting the carrier 110. A mechanical support 140 may be arranged below the first magnetic unit 312, below the second magnetic unit 314 and/or below the plurality of magnetic units 170. A contactlessly levitated carrier and/or a mechanically supported carrier may be above the mechanical support and/or below the plurality of magnetic units.

[00122] According to embodiments, which can be combined with other embodiments described herein, a mechanical support 140 may include one or more, e.g. a plurality, of support elements 142. A mechanical support 140 may include a plurality of rollers or bearings adapted for supporting the carrier 110. The plurality of rollers or bearings may be arranged in a plane, e.g. a horizontal plane. Each roller or bearing may have a rotation axis. The rotation axis may extend in a horizontal direction. The rotation axis may extend in a direction perpendicular or substantially perpendicular to the first direction 192.

[00123] In the figures, the mechanical support 140 is shown as a plurality of separate support elements. Embodiments described herein are not limited to such mechanical supports. For example, a mechanical support may include a plurality of support elements linked to each other.

[00124] According to embodiments, which can be combined with other embodiments described herein, a mechanical support 140 may include a plurality of retainer bearings or emergency bearings. A mechanical support 140 may be adapted for catching the carrier 110 in the case of a failure of the carrier levitation system during a contactless levitating or transportation of the carrier. For example, in a coating process or other process, the carrier may be contactlessly levitated by the plurality of magnetic units 170. In the case that the contactless levitation of the carrier is suddenly interrupted, e.g. due to a loss of power, the carrier 110 can in the worst case cease to be magnetically levitated and fall down. According to embodiments described herein, the carrier can land on the mechanical support, particularly on the retainer bearings or emergency bearings. The mechanical support 140 can catch the carrier and prevent damage to the carrier or other parts of the system.

[00125] The first distance sensor 732, the second distance sensor 734, the third distance sensor and/or the fourth distance sensor may be arranged above the mechanical support 140.

[00126] According to embodiments, which can be combined with other embodiments described herein, a mechanical support 140 may be fixed to the magnetic drive structure 180. The mechanical support 140 may include, be mechanically connected to or mounted to the magnetic drive structure 180 in a manner such that an alignment of the mechanical support 140 may influence and/or determine an alignment of the magnetic drive structure 180. According to embodiments, which can be combined with other embodiments described herein, the mechanical support includes or is mechanically connected to the magnetic drive structure 180 in a manner such that determining the alignment of the mechanical support 140 allows determining an alignment of the magnetic drive structure 180.

[00127] Embodiments described herein provide the advantage that the alignment of the magnetic units of the magnetic drive structure can be determined and corrected. [00128] According to embodiments, which can be combined with other embodiments described herein, an apparatus 500 may include a processing chamber 550. The plurality of magnetic units 170, the carrier 110, the mechanical support 140 and/or the magnetic drive structure 180 may be in the processing chamber 550. The carrier 110 shown in Fig. 8 may be moved in the processing chamber 550, e.g. in the first direction 192, so that further distances from the third magnetic unit 816 and from the fourth magnetic unit 818 to the carrier 110 can be measured.

[00129] Fig. 9 shows an apparatus 500 according to embodiments described herein. According to embodiments, which may be combined with other embodiments described herein, the control unit 750 may be connected to the magnetic drive structure 180. The control unit 750 may be configured for, based on a determined alignment of the mechanical support and/or of the magnetic drive structure, aligning the magnetic drive structure. Aligning the magnetic drive structure may be an automatic alignment. Aligning the magnetic drive structure may include adjusting a position of one or more magnetic units of the magnetic drive structure. The control unit 750 may be configured for, based on a determined alignment of the carrier levitation system, aligning the carrier levitation system. Aligning the carrier levitation system may be an automatic alignment. Aligning the carrier levitation system may include adjusting a position of one or more magnetic units of the carrier levitation system.

[00130] In the apparatus 500 shown in Figs. 7, 8 and 9, any component of the apparatus 100 shown in Fig. 1 may be included, and vice versa.

[00131] According to embodiments, which can be combined with other embodiments described herein, a plurality of magnetic units 170 may be arranged in a first direction 192. The plurality of magnetic units 170 may be a linear array of magnetic units extending in the first direction 192. A carrier contactlessly levitated or transported by the plurality of magnetic units 170 may extend in the first direction 192.

[00132] According to embodiments, which can be combined with other embodiments described herein, a mechanical support 140 may have a length extending in the first direction 192. A mechanical support 140 may be adapted for guiding a carrier in the first direction 192. A mechanical support 140 may extend in the first direction 192 at least along a length of the carrier levitation system in the first direction. Each magnetic unit of the plurality of magnetic units 170 may face the mechanical support 140. [00133] According to embodiments, which can be combined with other embodiments described herein, a magnetic drive structure 180 may be adapted for driving a carrier in the first direction 192. The first direction 192 may be a carrier transport direction 192. The first direction 192 may be a horizontal direction.

[00134] While the foregoing is directed to embodiments of the disclosure, other and further embodiments may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.