TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to apparatuses and methods for transportation of carriers, particularly carriers used for carrying large area substrates. More specifically, embodiments of the present disclosure relate to apparatuses and methods for transportation of carriers employable in processing apparatuses for vertical substrate processing, e.g. material deposition on large area substrates for display production. In particular, embodiments of the present disclosure relate to carrier transport systems, vacuum processing apparatuses, and methods of transporting a carrier in a vacuum chamber.

BACKGROUND

[0002] In order to process a substrate, an in-line arrangement of processing modules can be used. An in-line processing system includes a plurality of subsequent processing modules, such as deposition modules and optionally further processing modules, e.g., cleaning modules and/or etching modules, wherein processing aspects are subsequently conducted in the processing modules, such that a plurality of substrates can continuously or quasi-continuously be processed in the in-line processing system.

[0003] The substrate is typically carried by a carrier, i.e. a carrying device for carrying the substrate. The carrier is typically transported through a vacuum system using a carrier transport system. The carrier transport system may be configured for conveying the carrier carrying the substrate along one or more transport paths.

[0004] For obtaining high quality devices, technical challenges with respect to the processing of substrates need to be mastered. In particular, an accurate and smooth transportation of the carriers through the vacuum system is challenging. For instance, particle generation due to wear of moving parts can cause a deterioration in the manufacturing process. Accordingly, there is a demand for the transportation of carriers in vacuum deposition systems with reduced or minimized particle generation. Further challenges are, for example, to provide robust, simple and compact carrier transport systems for high temperature vacuum environments at low costs.

[0005] Typically, the carriers may be guided by rollers, and the stronger the load on the rollers, the larger the risk of particle generation, and the shorter the lifetime of the rollers. Fully contactless floating carrier transportation systems are complicated and expensive. Magnetic levitation systems with permanent magnets are difficult to realize. At least one degree of freedom has to be stabilized mechanically or with guide elements to overcome Earnshaw’s theorem.

[0006] A carrier typically includes a first rail for contacting the upper surfaces of the rollers in the majority of conditions. A lower rail is also provided for contacting the lower surfaces of the rollers in occasional conditions. Some situations may occur in which the carrier switches between contacting the upper surfaces of the rollers to contacting the lower surfaces of the rollers, causing a reversal of one or more rollers. This roller reversal may induce a shock or vibration to the carrier and/or rollers, and may generate particles through friction between the rails of the carrier and the one or more rollers undergoing reversal. Such situations may occur if the carrier undergoes a pitching motion either through acceleration/deceleration or during a gap transition, or if the carrier undergoes an overcompensation or undercompensation event where the magnetic compensation of the carrier is changed.

[0007] Accordingly, an apparatus and method for guiding a carrier, particularly a vertically oriented carrier, to prevent a roller reversal would be beneficial. Preventing roller reversals can reduce generation of particles during carrier transportation and the lifetime of the mechanical elements can be improved. SUMMARY

[0008] In light of the above, carrier transport systems for transporting a carrier in a vacuum chamber, an apparatus for vacuum processing, as well as methods of transporting a carrier in a vacuum chamber according to the independent claims are provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0009] According to one aspect of the present disclosure, a carrier transport system for transporting a carrier within a vacuum chamber is provided. The carrier transport system includes a track assembly extending in a transport direction, the track assembly including at least one passive magnetic unit extending in the transport direction configured to counteract a partial weight of the carrier, a roller transport track including a plurality of rollers configured to support a total roller weight of the carrier, a drive assembly including a plurality of active magnetic drive units having a first active magnetic drive unit configured for generating a first carrier drive force having a first vector with a first angle relative to the transport direction, and a controller configured for active vector control of the first active magnetic drive unit to control the first angle.

[0010] According to a further aspect of the present disclosure, an apparatus for vacuum processing of a substrate is provided. The apparatus includes at least one vacuum chamber, a carrier transport system according to embodiments of the present disclosure, and a carrier for supporting the substrate, the carrier including at least one passive magnetic unit, a first rail configured to be in top contact with a plurality of rollers, a second rail configured to be in bottom contact with the plurality of rollers and a magnetic drive element configured to be driven by the drive assembly.

[0011] According to a yet further aspect of the present disclosure, a method for transportation of a carrier along a track assembly within an apparatus for vacuum processing of a substrate is provided. The method includes counteracting a partial weight of the carrier using at least one passive magnetic unit of the track assembly and at least one passive magnetic unit of the carrier, supporting a total roller weight of the carrier using at least one of a plurality of rollers of the track assembly, transporting the carrier along the track assembly in a transport direction by generating a first carrier drive force having a first vector with a first angle relative to the transport direction by operating a first active magnetic drive unit of a plurality of active magnetic drive units, and controlling the first active magnetic drive unit with active vector control to control the first angle.

[0012] The aspects and embodiments of the present disclosure allow for avoiding a roller reversal caused by the carrier switching between contact with an upper surface of the rollers and contact with the lower surfaces of the rollers. Particularly, a pitching of the carrier during acceleration/decel eration of the carrier or when the carrier traverses a gap transition, which may lead to a roller reversal, may be suppressed. Further, the loads applied to the rollers during transport of a carrier may be minimized. It follows that the carrier transport system allows for reduced particle generation in the vacuum processing system and improved lifetime of the mechanical components of the carrier transport system.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

FIG. 1 shows a schematic end view of a carrier transport system according to embodiments of the present disclosure;

FIG. 2 shows a schematic side view of a carrier transport system;

FIG. 3 shows a schematic side view of a carrier transport system according to the present disclosure; FIG. 4 shows a plot of driving force in the transport direction and attraction force in the vertical direction for a carrier transport system according to embodiments of the present disclosure;

FIG. 5 shows a schematic side view of a carrier transport system; and

FIG. 6 shows a schematic side view of a carrier transport system according to the present disclosure.

DETAILED DESCRIPTION OF EMBODIMENTS

[0014] Reference will now be made in detail to the various embodiments of the disclosure, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations.

[0015] A carrier transport system is configured for transporting a carrier in a vacuum environment, particularly in a vacuum chamber or in a vacuum system including a plurality of vacuum chambers arranged next to each other, e.g. in a linear array. The carrier transport system may provide one, two or more transport paths _x wherein the carrier can be moved or conveyed along the one or more transport paths in a transport direction.

[0016] The carrier transport system described herein can be a part of a vacuum processing system, particularly a vacuum deposition system configured for depositing a material on a substrate carried by a carrier. The carrier transport system may be configured to displace or transfer the carrier.

[0017] The carrier transport system may be configured to transfer the carrier by counteracting the weight of the carrier, particularly up to 100% of the weight of the carrier, with magnetic levitation. The magnetic levitation is furthermore configured to guide or stabilize the carrier in the transverse direction Z. The transverse direction Z can be understood as the direction perpendicular to the vertical direction Y and perpendicular to the transport direction X.

[0018] Reference will firstly be made to FIG. 1 , which shows a schematic end view of a carrier transport system and a carrier 100 for a vacuum processing apparatus. The carrier transport system is provided with a track assembly including a roller transport track 200 having a plurality of rollers 210, and a carrier 100 for being transported by the carrier transport system in transport direction X. Roller transport track 200 may be arranged at the bottom of carrier 100, and carrier 100 may be oriented in a vertical or near-vertical orientation.

[0019] Some embodiments described herein involve the notion of carrier 100 being transported in a “vertical or near- vertical orientation”. A vertical orientation of carrier 100 in the context of the present disclosure refers to carrier 100 being aligned to extend in a direction substantially parallel to the direction of the force of gravity, i.e. substantially parallel to vertical direction Y. A near- vertical orientation may be defined as an orientation which deviates from exact verticality (the latter being defined by the gravitational force) by an angle of up to 15 degrees. In a vertical or near-vertical orientation, carrier 100 may support a substrate S in a vertically standing or near- vertically standing orientation.

[0020] In the context of the present disclosure, and as shown in the figures, carrier 100 is configured for supporting a substrate S, however the present disclosure is not limited thereto. Alternatively, carrier 100 may be configured for supporting a mask. According to some embodiments, which may be combined with other embodiments described herein, carrier 100 may be configured for supporting a substrate or a mask in a vacuum processing apparatus.

[0021] Carrier 100 has a carrier body 110, and is provided with a first rail 120 and a second rail 122, such that the first and second rails 120, 122 are configured to contact a plurality of rollers 210 of roller transport track 200. In a typical operation, first rail 120 makes contact with the upper surfaces of the plurality of rollers 210, or is supported on top of the plurality of rollers 210, while second rail 122 does not make contact with the plurality of rollers 210. In the context of the present disclosure, this condition is referred to as “top contact”. However, in certain situations, carrier 100 may undergo a lifting or pitching motion, in which second rail 122 makes contact with at least one lower surface of one of the plurality of rollers 210. In the context of the present disclosure, this condition is referred to as “bottom contact”. Note however that these two conditions are not mutually exclusive. For example, a pitching motion of carrier 100 may occur in which a roller 210 at one end of carrier 100 is in top contact with the first rail 120, while a roller 210 at the other end of carrier 100 is in bottom contact with the second rail 122.

[0022] First and second rails 120, 122 may be flat contact surfaces for contacting a cylindrical roller. A cylindrical roller offers low friction, low wear and low cost. However, a cylindrical roller does not provide for guiding the carrier 100 in the transverse direction Z. An additional assembly for guiding the carrier 100 in the transverse direction Z may be implemented.

[0023] Roller transport track 200, particularly the plurality of rollers 210, are provided for supporting a portion of the weight W of carrier 100, referred to herein as the “total roller weight” R. Particularly, the total roller weight R corresponds to the portion of the weight W of carrier 100 which is distributed among the plurality of rollers 210 on which carrier 100 is supported. It is advantageous to minimize the total roller weight R being supported by the plurality of rollers 210 so as to improve the lifetime of the mechanical components of the carrier support system. Minimizing the total roller weight R is achieved by counteracting at least a partial weight A, B of the weight W of carrier 100 with at least one passive magnetic unit 410, 610. For example, the total roller weight R may be at most 10% of the weight W of carrier 100, at most 5% of the weight W of carrier 100, or at most 1% of the weight W of carrier 100.

[0024] The carrier transport system may further include an upper guiding track 400 arranged at the top of carrier 100 configured for maintaining carrier 100 in the vertical or near-vertical orientation. Upper guiding track 400 includes a first passive magnetic unit 410 as part of the track assembly, and a first passive magnetic unit 130 as part of the carrier 100. The polarity of the first passive magnetic unit 410 of the track assembly is arranged opposite to the polarity of the first passive magnetic unit 130 of the carrier 100, such that magnetic attractive forces contactlessly guide carrier 100 in transverse direction Z.

[0025] The carrier transport system may further include a lower guiding track 600 arranged at the bottom of carrier 100. Similar to upper guiding track 400, lower guiding track 600 may be configured for guiding carrier 100 in transverse direction Z. Lower guiding track 600 may include a second passive magnetic unit 610 as part of the track assembly and a second passive magnetic unit 140 as part of the carrier 100. The polarity of the second passive magnetic unit 610 of the track assembly is arranged opposite to the polarity of the second passive magnetic unit 140 of the carrier 100, such that magnetic attractive forces contactlessly guide carrier 100 in transverse direction Z.

[0026] As exemplarily shown in the figures, upper guiding track 400 and lower guiding track 600 are shown as having a transverse magnetization. In other words, the opposite polarities of each of the first passive magnetic units 410, 130 and each of the second passive magnetic units 610, 140 are arranged in the transverse direction Z, and the respective passive magnetic units are arranged to face each other in the vertical direction Y. However, the present disclosure is not limited thereto, and at least one of the upper guiding track 400 and the lower guiding track 600 may be arranged in a vertical magnetization. In other words, the opposite polarities of each of the first passive magnetic units 410, 130 and each of the second passive magnetic units 610, 140 may alternatively be arranged in the vertical direction Y, and the respective passive magnetic units are arranged to face each other in the vertical direction Y.

[0027] Due to the magnetic attractive forces being applied to carrier 100, upper guiding track 400 and lower guiding track 600 may be further configured for supporting at least a portion of a weight W of carrier 100. While the primary function of upper and lower guiding track 400, 600 may be to provide guidance in the transverse direction Z, the magnetic forces may be used to offset some of weight W of carrier 100 so that the supported weight W of carrier 100 being borne by the roller transport track 200 may be reduced, leading to a reduction in roller loads and roller wear. [0028] The carrier transport system further includes a drive assembly 500. As exemplarily shown, drive assembly 500 may include a linear motor having a plurality of active magnetic drive units 510, and carrier 100 may include at least a magnetic drive element 150. The plurality of active magnetic drive units 510 are configured to induce a controllable magnetic force in magnetic drive element 150, such that carrier 100 is driven along the carrier transport system in transport direction X. Active magnetic drive units 510 may include a number of coils, for example, active magnetic drive units 510 may be three-phase drive units including three coils. The embodiment exemplarily shown has drive assembly 500 arranged at a bottom end of carrier 100. However, drive assembly 500 may alternatively be arranged at atop end of carrier 100. Similar to the magnetic, contactless guiding provided by upper and lower guiding tracks 400, 600, a contactless, magnetic drive assembly 500 is advantageous in a vacuum processing apparatus as the generation of particles is avoided.

[0029] According to a preferred architecture, and as exemplarily shown in the figures, the carrier transport system includes a track assembly having a first passive magnetic unit 410 provided at a first vertical coordinate Yi and extending in the transport direction X, wherein the first passive magnetic unit 410 is configured to counteract a first partial weight A of the carrier 100, and a second passive magnetic unit 610 provided at a second vertical coordinate Y2 and extending in the transport direction X, wherein the second passive magnetic unit 610 is configured to counteract a second partial weight B of the carrier 100. The roller transport track 200 may be provided at a third vertical coordinate Y3, and the drive assembly 500 may be provided at a fourth vertical coordinate Y4. The first vertical coordinate Yi is at a top of the carrier 100, the fourth vertical coordinate Y4 is at a bottom of the carrier 100, and the second and third vertical coordinates Y2, Y3 are between the first vertical coordinate Yi and the fourth vertical coordinate Y4.

[0030] According to a further preferred architecture, and as exemplarily shown in the figures, the carrier transport system includes a track assembly extending in a transport direction X, the track assembly comprising a first passive magnetic unit 410 provided at a first vertical coordinate Y 1 and extending in the transport direction X, a second passive magnetic unit 610 provided at a second vertical coordinate Y2 and extending in the transport direction X, a roller transport track 200 provided at a third vertical coordinate Y3 and a drive assembly 500 provided at a fourth vertical coordinate Y4, wherein a first vertical distance between the first vertical coordinate Yi and the second vertical coordinate Y2 is larger than a second vertical distance between the second vertical coordinate Y2 and the third vertical coordinate Y3. In such a preferred architecture, the second partial weight B counteracted by second passive magnetic unit 610 is configured to be significantly more than the first partial weight A counteracted by the first passive magnetic unit 410. Such an arrangement is advantageous, as thermal expansion and contraction of carrier 100 has a considerably larger effect on the first vertical distance than the second vertical distance. By reducing the amount of compensation of the first passive magnetic unit 410, any thermal expansion or contraction which causes the distance between first passive magnetic units 410, 130 to change results in a smaller effect on the distribution of compensation as compared with the second passive magnetic unit 610.

[0031] According to the present disclosure, a carrier 100, particularly for a substrate S to be processed in an apparatus for vacuum processing of the substrate S, is provided. The carrier 100 is configured to be transported by the carrier transport system according to embodiments of the present disclosure. The carrier 100 includes at least one passive magnetic unit 130, 140, a first rail 120 configured to be in top contact with a plurality of rollers 210, 210a, 210b, a second rail 122 configured to be bottom contact with the plurality of rollers 210, 210a, 210b, and a magnetic drive element 150 configured to be driven by a drive assembly 500 including at least one active magnetic drive unit 510.

[0032] In a preferred embodiment, carrier 100 may include a first passive magnetic unit 130 provided at a first vertical coordinate Yi and a second passive magnetic unit 140 provided at a second vertical coordinate Y2. A first rail 120 and a second rail 122 is provided for contacting at least one roller 210 of a roller transport track 200 at a third vertical coordinate Y3, wherein a first vertical distance between the first vertical coordinate Yi and the second vertical coordinate Y2 is larger than a second distance between the second vertical coordinate Y2 and the third vertical coordinate Y3. [0033] Reference will now be made to FIG. 2, which shows the carrier transport system of FIG. 1 in a schematic side view, where carrier 100 is being accelerated with an acceleration a _x in the transport direction X. The weight W of the carrier 100 is supported and/or counteracted by the components of the carrier transport system. A first partial weight A of the carrier 100 may be counteracted by first passive magnetic unit 410 of the track assembly by acting on the corresponding first passive magnetic unit 130 of the carrier 100. A second partial weight B of the carrier 100 may be counteracted by second passive magnetic unit 610 of the track assembly by acting on the corresponding second passive magnetic unit 140 of the carrier 100. Finally, the plurality of rollers 210 with which carrier 100 makes contact supports a total roller weight R.

[0034] Each one of the plurality of active magnetic drive units 510 is controlled to apply a carrier driving force F to the magnetic drive element 150 of carrier 100 so as to accelerate carrier 100 along the track assembly in the transport direction X. The carrier driving force F has a vector with an angle a relative to the transport direction X. Each one of the plurality of active magnetic drive units 510 shown in the example of FIG. 2 are configured to generate substantially equal carrier driving forces F having vectors at substantially equal angles a relative to the transport direction X.

[0035] The carrier driving force F applied by each of the active magnetic drive units 510 includes a carrier drive component Fx in the transport direction X and also, due to the magnetic nature of the active magnetic drive units 510, a carrier attraction component Fy in the vertical direction Y. In this case, the total carrier attraction component Fy is compensated by either one or both of the first passive magnetic units 410, 130 and the second passive magnetic units 610, 140, such that the remaining forces acting on each of the plurality of rollers 210 is minimized.

[0036] As an example, for carrier 100 having weight W being transported at steady state and with a total carrier attraction component Fx equivalent to a portion of the weight W of carrier 100, for example, 40% of the weight W of carrier 100, equilibrium may be achieved by compensating the same portion of the weight W of the carrier 100 by first passive magnetic units 410, 130, and further compensating at least 90% of the weight W of the carrier 100 by second passive magnetic units 610, 140, leaving 10% or less of the weight W to be distributed to each one of the plurality of rollers 210 in contact with carrier 100.

[0037] When at rest or travelling at a constant speed, first rail 120 of carrier 100 makes top contact with the plurality of rollers 210 such that the remaining roller force is evenly distributed across the plurality of rollers 210. However, since carrier 100 is being accelerated with an acceleration a _x in the transport direction X, carrier 100 undergoes a pitching motion. This pitching motion of carrier 100 causes a number of effects. Firstly, the top contact between first rail 120 and the upper surfaces of the plurality of rollers 210 changes, such that first rail 120 makes top contact with only the rearmost roller 210a, inducing a higher roller force Ra on the rearmost roller 210a. Secondly, second rail 122 makes bottom contact with the lower surface of a frontmost roller 210b, causing a reversal of the rotation direction of the frontmost roller 210b, and inducing a roller force Rb. In the present disclosure, a situation in which the direction of rotation of a roller is switched or reversed due to second rail 122 making bottom contact with at least one of the plurality of rollers 210 may be referred to as a “rotation reversal” of a roller, or may be referred to as a “roller reversal”. Note that the term “rotational reversal” or “roller reversal” does not refer to the case where the transport direction X of the carrier 100 is simply reversed so that the plurality of rollers 210 is rotated in the opposite direction. Rather, the event of a “roller reversal” refers to a change from a top contact to a bottom contact between the first and second rails 120, 122 of carrier 100, causing the direction of rotation of at least one roller to switch.

[0038] Finally, the pitching motion changes the respective distances between first passive magnetic units 410, 130 and second passive magnetic units 610, 140, which changes the distribution of magnetic compensation between a front of the carrier 100 and a rear of the carrier 100. A larger distance between first passive magnetic units 410, 130 at a rear of the carrier 100 results in a lower compensation force Aa, while a smaller distance between first passive magnetic units 410, 130 at a front of carrier 100 results in a higher compensation force Ab. Similarly, a lower compensation force Ba at a rear of carrier 100 and a higher compensation force Bb at a front of carrier 100 are also generated by second passive magnetic units 610, 140. The resulting change in distribution of compensation causes the carrier to be “overcompensated” at a front of carrier 100, and “undercompensated” at a rear of carrier 100.

[0039] In the context of the present disclosure, the terms “overcompensation” of a carrier and “undercompensation” of a carrier may be understood as referring to the situations where the weight W of carrier 100 is either excessively compensated by the carrier transport system or inadequately compensated by the carrier transport system, respectively.

[0040] In the case of a carrier being “overcompensated”, the combined compensation provided by first passive magnetic units 410, 130 and second passive magnetic units 610, 140 is higher than the compensation for counteracting the weight W of the carrier 100 and the total carrier attraction component Fy of the active magnetic drive units 510. As a result, the carrier 100 is lifted such that first rail 120 is no longer in top contact with the upper surfaces of the plurality of rollers 210, but rather second rail 122 is in bottom contact with the lower surfaces of the plurality of rollers 210. This would cause a reversal of one or more rollers 210 and corresponding friction therebetween, potentially causing the generation of particles through increasing wear of the plurality of rollers 210 and first and second rail 120, 122.

[0041] In the case of a carrier being “undercompensated”, the combined compensation provided by first passive magnetic units 410, 130 and second passive magnetic units 610, 140 is lower than the compensation for counteracting the weight W of the carrier 100 and the total carrier attraction component Fy of the active magnetic drive units 510. As a result, the third partial weight of the carrier 100 being supported by the plurality of rollers 210, or potentially only one roller 210, is excessive, potentially causing the generation of particles through increasing wear of the plurality of rollers 210.

[0042] Many factors may change the distribution of compensation provided, and hence the portions of weight W of the carrier 100 supported, by each of the first passive magnetic units 410, 130, second passive magnetic units 610, 140 and the plurality of rollers 210. For example, a carrier 100 may be configured for carrying substrates having different weights, for example, different size substrates or substrates which have been deposited with different amounts of material, resulting in the carrier 100 supporting a substrate S potentially having a different combined weight. A carrier 100 supporting a lighter substrate S may be overcompensated by the carrier transport system, while a carrier 100 supporting a heavier substrate S may be undercompensated by the carrier transport system.

[0043] Another factor which may change the distribution of compensation is when the carrier 100 is subjected to a temperature change, resulting in thermal expansion or contraction of carrier 100. A gap between first passive magnetic units 410, 130 may increase or decrease, resulting in a different amount of compensation provided by first passive magnetic units 410, 130. A carrier 100 being subjected to thermal expansion may by overcompensated by the carrier transport system, while a carrier 100 being subjected to thermal contraction may be undercompensated by the carrier transport system.

[0044] A further situation in which the distribution of compensation may be changed is when a carrier traverses a gap. In a typical vacuum processing apparatus, a carrier 100 may be transported from a first vacuum chamber to a second chamber. Problems arise when carrier 100 is transported across a gap transition, particularly a gap transition between vacuum chambers of the vacuum processing apparatus, as either a pitching motion may occur, or the lack of passive and/or active magnetic units in the gap transition may cause the distribution of compensation to be changed, reduced or compromised.

[0045] In the situations described above, additional compensation may be provided by the apparatus and methods of the present disclosure to overcome these changes in the distribution of compensation, and to overcome the problem of overcompensation or undercompensation of the carrier 100. Particularly, the apparatus and methods of the present disclosure allow for a reduction in roller loading, and an avoidance of roller reversal, leading to reduced particle generation and improved lifetime of mechanical components.

[0046] Referring now to FIG. 3, the carrier transport system is once again shown accelerating carrier 100 with an acceleration a _x in the transport direction X. However, in comparison to FIG. 2, the carrier transport system is configured for active vector control of the carrier drive force F generated by the at least one magnetic drive unit 510. According to an aspect of the present disclosure, a carrier transport system for transporting a carrier 100 within a vacuum chamber is provided. The carrier transport system includes a track assembly extending in the transport direction X, the track assembly including at least one passive magnetic unit 410, 610 extending in the transport direction X configured to counteract a partial weight A, B of the carrier 100, a roller transport track 200 including a plurality of rollers 210, 210a, 210b configured to support a total roller weight R of the carrier 100, a drive assembly 500 comprising a plurality of active magnetic drive units 510, 510a, 510b having a first active magnetic drive unit 510a configured for generating a first carrier drive force F having a first vector with a first angle a _a relative to the transport direction X, and a controller configured for active vector control of the first active magnetic drive unit 510a to control the first angle a _a .

[0047] In the context of the present disclosure, the term “active vector control” may refer to any system, method or technique which may be used to control the driving force of an AC synchronous motor. Otherwise known as field-oriented control, active vector control is commonly used in rotational AC synchronous motor applications for optimizing performance of the motor over a full range of speeds. Typically, the active vector control may include identifying stator currents of a three-phase AC electric motor as two orthogonal components which may be visualized as a vector. A first component defines the magnetic flux of the motor, and a second component defines the torque of the motor. Active vector control allows for a stronger magnetic flux component at lower motor speeds for improved low-speed torque, while also allowing for a weakening of the magnetic flux component at high motor speeds.

[0048] The same principles may be applied to linear synchronous motors, wherein the stator currents of a three-phase AC linear synchronous motor may be identified as two orthogonal components - a first component defining the magnetic flux of the motor, and a second component defining the driving force of the motor. The magnetic flux component is equivalent to an attraction force between the stator and the rotor, and by using active vector control, this attraction force can be controlled. [0049] One method for implementing active vector control is to define a current vector for the current to be applied to each coil of the three-phase AC linear synchronous motor in a respective d-q coordinate system. The d-q coordinate system includes a direct axis d and a quadrature axis q, such that the d-current corresponds to a field flux linkage current component of the respective current vector, and the q- current corresponds to a driving force current component of the respective current vector. By controlling the phase angle between the respective d-currents, the magnitude of the attraction force between the stator and the rotor may be controlled. Similarly, by controlling the phase angle between the respective q-currents, the magnitude of the driving force in a transport direction may be controlled.

[0050] A simulation of the driving force and attraction force for a linear synchronous motor being controlled with active vector control is exemplarily shown in FIG. 4. The plot exemplarily shows the magnitude of a transient driving force 10 and the magnitude of a transient attraction force 20 where the phase angles between the respective d-current and q-current is adjusted. The transient driving force is oriented in the transport direction X, while the transient attraction force is oriented in the vertical direction Y. Further, the plot exemplarily shows a static attraction force 30, equivalent to the typical attraction force between the linear synchronous motor to the stator without active vector control.

[0051] The driving force 10 may be adjusted by controlling the q-current phase angle. For example, by setting the q-current phase angle at +90°, the maximum positive driving force 11 in the transport direction may be achieved. Conversely, by setting the q-current phase angle at -90°, the maximum negative driving force 12 may be achieved. Particularly, a positive driving force acts to drive a carrier 100 of the present disclosure in a forward transport direction, while a negative driving force acts to drive a carrier 100 of the present disclosure in a reverse transport direction.

[0052] The attraction force 20 may be adjusted by controlling the d-current phase angle. For example, by setting the q-current phase angle at +90°, the maximum attraction force 21 in the vertical direction may be achieved. Conversely, by setting the q-current phase angle at -90°, the minimum attraction force 22 may be achieved. As exemplarily shown in the figure, the attraction force can be controlled across a large range, allowing for a wide range of control of the distribution of a weight W of carrier 100 across the plurality of rollers 210, as well as providing sufficient headroom for the carrier transport system to maintain top contact between carrier 100 and the plurality of rollers 210.

[0053] According to embodiments, which may be combined with other embodiments described herein, the plurality of active magnetic drive units 510, 510a, 510b may further include a second active magnetic drive unit 510b configured for generating a second carrier drive force Fb having a second vector with a second angle a.b relative to the transport direction X, and the controller is further configured for active vector control of the second active magnetic drive unit 510b to control the second angle ab, wherein the second angle ab is different to the first angle a _a .

[0054] In order to overcome the problems discussed above with respect to pitching of the carrier, excessive or uneven loading of the rollers 210 and undercompensation and overcompensation of the carrier 100, embodiments of the present disclosure allow for active vector control of the carrier drive force F. As exemplarily shown in FIG. 3, a first active magnetic drive unit 510a at a rear end of the carrier 100 is controlled with active vector control to change the angle a _a and/or magnitude of a first carrier drive force Fa, and a second active magnetic drive unit 510b at a front end of the carrier 100 is controlled with active vector control to change the angle ab and/or magnitude of a second carrier drive force Fb. By controlling the respective first and second carrier drive forces Fa, Fb, particularly by controlling at least one of first angle a _a and second angle ab, a pitching motion of the carrier 100 caused by an acceleration a _x can be suppressed, avoiding the disadvantageous effects discussed above.

[0055] Particularly, by suppressing the pitching motion of carrier 100, first rail 120 may be maintained in top contact with the plurality of rollers 210, avoiding a roller reversal situation. Further, maintaining top contact between first rail 120 and the plurality of rollers allows for the total roller weight R to be evenly distributed between all of the rollers 210 in top contact with first rail 120, significantly reducing the loading on any one roller 210. Still further, by suppressing the pitching motion of carrier 100, the distance between the at least one passive magnetic units 410, 610, 130, 140, particularly the distance between first passive magnetic units 410, 130 and the distance between second passive magnetic units 610, 140, can be maintained at a consistent distance across the length of carrier 100, preventing carrier 100 from being overcompensated at a front end of carrier 100 and undercompensated at a rear end of carrier 100.

[0056] According to an embodiment, which may be combined with other embodiments described herein, the carrier drive force F, Fa, Fb includes a carrier drive component Fx, Fxa, Fxb in the transport direction X and a carrier attraction component Fy, Fya, Fyb in the vertical direction Y, and the carrier attraction component Fy, Fya, Fyb is controlled by the active vector control.

[0057] As shown exemplarily in FIG. 3, the first and second carrier drive forces Fa, Fb each have respective carrier drive components Fxa, Fxb and respective carrier attraction components Fya, Fyb. The respective carrier drive components Fxa, Fxb and respective carrier attraction components Fya, Fyb are related to the respective first and second angles a _a , a.b. Accordingly, to accelerate carrier 100 in the transport direction X with acceleration a _x while also suppressing a pitching motion of carrier 100, first active magnetic drive unit 510a is controlled with active vector control to reduce first angle a _a , i.e. to have a reduced carrier attraction component Fya, while second active magnetic drive unit 510b is controlled with active vector control to have an increased angle ab, i.e. to have an increased carrier attraction component Fyb. More generally, the active vector control is used to control the first angle a _a and the second angle ab, wherein the second angle ab is different to the first angle a _a .

[0058] However, both first and second active magnetic drive units 510a, 510b may be controlled so as to have respective carrier drive components Fxa, Fxb having the same magnitude. The active vector control allows for independent control of the carrier drive component Fx for transporting carrier 100 in the transport direction and the carrier attraction component Fy for controlling the magnetic equilibrium of carrier 100.

[0059] According to an embodiment, which may be combined with other embodiments described herein, the plurality of active magnetic drive units 510, 510a, 510b may be configured to maintain top contact between the carrier 100 and the plurality of rollers 210, 210a, 210b. More particularly, the plurality of active magnetic drive units 510, 510a, 510b may be configured to maintain top contact between first rail 120 and the plurality of rollers 210, 210a, 210b. By maintaining top contact, it may be assured that the carrier 100, particularly first rail 120, makes contact with multiple rollers 210 across the length of carrier 100 such that the total roller weight R to be supported by the plurality of rollers 210 is distributed evenly between the rollers 210, reducing the load applied to any one roller 210.

[0060] In other words, the plurality of active magnetic drive units 510, 510a, 510b may be configured to prevent a rotation reversal of at least one of the plurality of rollers 210, 210a, 210b. Particularly, the plurality of active magnetic drive units 510, 510a, 510b may be configured to prevent the second rail 122 from making bottom contact with at least one of the plurality of rollers 210, 210a, 210b, thus preventing the second rail 122 from reversing the rotation direction of the at least one roller 210.

[0061] Other situations may arise in which the distribution of magnetic compensation is changed, reduced or compromised, or in which the carrier 100 undergoes a pitching motion. One such situation is when a carrier is transported across a gap transition. Referring now to FIG. 5, the carrier transport system is shown transporting carrier 100 in the transport direction X across a gap transition 300. In the region of the gap transition 300, there is an absence of one or more elements of the carrier transport system. Particularly, roller transport track 200 has an absence of rollers 210 in the region of the gap transition 300. Similarly, first and second passive magnetic units 410, 610 are divided into respective first and second passive magnetic units 410a, 610a on the first side of the gap transition 300 and respective first and second passive magnetic units 410b, 610b on the second side of the gap transition 300. As a result, the magnetic compensation provided by first and second passive magnetic units 410, 610 changes across the gap transition 300. Further, carrier 100 is cantilevered some distance past the last roller 210 of roller transport track 200 on the first side of the gap transition 300, and has not yet made top contact with the first roller 210 of roller transport track 200 on the second side of the gap transition 300.

[0062] As a result, the carrier 100 becomes undercompensated. In other words, the total roller weight R to be supported by the roller transport track 200, particularly the last roller 210 on the first side of the gap transition 300, is considerably increased. The undercompensation of carrier 100 in the gap transition 300 may cause carrier 100 to undergo a pitching motion leading to a roller reversal, or may lead to an uneven distribution of total roller weight R on each of the rollers 210.

[0063] In the context of the present disclosure, the term “gap transition” may be defined as a portion of the carrier transport system with an absence of some or all magnetic elements. The term “gap transition” may further include a portion of the carrier transport system with an absence of some or all transport track components, however the present disclosure is not limited thereto. It leads that the term “traversing a gap transition” does not necessarily define that a complete absence of all elements in the transport track is passed over, but rather that the carrier transits a region in which some or all magnetic elements are absent, and a subsequent reduced, changed or compromised magnetic compensation of the weight W of the carrier 100 occurs.

[0064] Referring to FIG. 6, the carrier transport system is now provided with active vector control of at least one of the plurality of active magnetic drive units 510, 510a, 510b. Similar to FIG. 3 discussed previously, FIG. 6 exemplarily shows a first active magnetic drive unit 510a at a rear end of carrier 100 and a second active magnetic drive unit 510b at a front end of carrier 100. In this case, second active magnetic drive unit 510b is provided next to gap transition 300. The uneven distribution of roller weight R between the plurality of rollers 210 may be avoided by using active vector control to provide an increased carrier attraction force Fya from first active magnetic drive unit 510a and to provide a decreased carrier attraction force Fyb from second active magnetic drive unit 510b. The high roller load being subjected to the last roller 210 in particular can therefore be reduced, and the total roller weight R may be evenly distributed among the plurality of rollers 210.

[0065] A further situation which may arise in which the distribution of magnetic compensation is changed, reduced or compromised may be in the case of different weights of substrates S being carried by carrier 100. A heavier substrate S would be supported by an increased magnetic compensation in order to maintain the desired total roller weight R being supported by the plurality of rollers 210. In this case, the carrier transport system according to embodiments described herein may be implemented, wherein the plurality of active magnetic drive units 510, 510a, 510b may be controlled with active vector control to change the total amount of carrier attraction force Fy to compensate for a heavier or lighter substrate S being supported by carrier 100.

[0066] Yet a further situation which may arise in which the distribution of compensation is changed, reduced or compromised may be in the case of carrier 100 being subjected to thermal expansion or contraction. A rise in temperature may cause carrier 100 to thermally expand, closing the distance between first passive magnetic units 410, 130 and/or second passive magnetic units 610, 140. When the distance between the passive magnetic units is decreased, the amount of magnetic compensation provided by the passive magnetic units increases, causing the distribution of compensation to change. Similarly, a temperature drop may cause carrier 100 to thermally contract, increasing the distance between first passive magnetic units 410, 130 and/or second passive magnetic units 610, 140, decreasing the amount of magnetic compensation provided by the passive magnetic units. In this case, the carrier transport system according to embodiments described herein may be implemented, wherein the plurality of active magnetic drive units 510, 510a, 510b may be controlled with active vector control to change the total amount of carrier attraction force Fy to compensate for a thermal expansion or contraction of the carrier 100.

[0067] The active vector control of the plurality of active magnetic drive units 510, 510a, 510b may be implemented on a controller. The controller may be connected to each one of the plurality of active magnetic drive units 510, 510a, 510b such that the controller may control one or more carrier drive forces F. Particularly, the controller may be connected to each one of the plurality of active magnetic drive units 510, 510a, 510b, such that the controller may control one or more angles a of the respective vectors of the one or more carrier drive forces F.

[0068] The controller comprises a central processing unit (CPU), a memory and, for example, support circuits. To facilitate control of the plurality of active magnetic drive units 510, 510a, 510b, the CPU may be one of any form of general purpose computer processor that can be used in an industrial setting for controlling aspects of the carrier transport system. The memory is coupled to the CPU. The memory, or a computer readable medium, may be one or more readily available memory devices such as random access memory, read only memory, floppy disk, hard disk, or any other form of digital storage either local or remote. The support circuits may be coupled to the CPU for supporting the processor in a conventional manner. These circuits include cache, power supplies, clock circuits, input/output circuitry and related subsystems, and the like. Carrier transport instructions, particularly active magnetic drive unit control instructions, are generally stored in the memory as a software routine typically known as a recipe. The software routine may also be stored and/or executed by a second CPU that is remotely located from the hardware being controlled by the CPU. The software routine, when executed by the CPU, transforms the general purpose computer into a specific purpose computer (controller) that controls the apparatus operation such as that for controlling the plurality of active magnetic drive units 510, 510a, 510b during the carrier transport process. Although the method and/or process of the present disclosure may be implemented as a software routine, parts of the methods disclosed herein may be performed in hardware as well as by the software controller. As such, the methods of the present disclosure may be implemented in software as executed upon a computer system, in hardware as an application specific integrated circuit or other type of hardware implementation, or a combination of software and hardware.

[0069] According to an embodiment, which may be combined with other embodiments described herein, the carrier transport system may further include at least one sensor configured for measuring at least one signal, wherein the active vector control is dependent on the at least one signal. Various sensors may be included in order to provide more accurate control of the carrier drive force F based on various parameters. The at least one sensor may be connected to the controller such that the at least one signal measured by the at least one sensor may be received by the controller.

[0070] The at least one sensor may include a carrier position sensor which provides the controller with a signal corresponding to the current position of carrier 100 with respect to the at least one active magnetic drive units 510, 510a, 510b. For example, when a carrier 100 is being accelerated in the transport direction X, the active vector control may be configured to receive a current position of carrier 100 and to control the carrier drive force F such that the magnitude of carrier attraction component Fy is higher when the front of carrier 100 passes the active magnetic drive unit 510 and gradually decreases as carrier 100 passes by, decreasing to a lower magnitude of carrier attraction component Fy when the rear of carrier 100 passes the active magnetic drive unit 510. The carrier position sensor may include at least one hall effect sensor for contactlessly measuring the position of carrier 100. However, the present disclosure is not limited thereto, and any sensor capable of providing a signal corresponding to the position of carrier 100 may be used.

[0071] The at least one sensor may include at least one roller weight sensor. The at least one roller weight sensor may be configured to measure a weight, particularly a loading force, being applied to a roller of the plurality of rollers 210. For example, the at least one roller weight sensor may include at least one strain gauge installed on the shaft of at least one roller of the plurality of rollers. The roller weight sensor may provide the controller with a measurement of the roller weight being applied to said roller. The controller may be configured to control, through active vector control, at least one angle a of at least one carrier drive force F so as to decrease the carrier attraction component Fy so that the total roller weight R is reduced, or to increase the carrier attraction component Fy so that carrier 100 is returned to making top contact with said roller of the plurality of rollers 210.

[0072] Alternatively, the at least one roller weight sensor may instead be a simple roller contact sensor which indicates whether said roller of the plurality of rollers is making contact with carrier 100, particularly one of first rail 120 and second rail 122. For example, for a metallic roller and a metallic second rail 122, an electrical circuit may be provided such that when second rail 122 and said metallic roller make bottom contact, the circuit is closed and a signal is provided to the controller that said roller is making bottom contact with second rail 122.

[0073] The at least one sensor may include at least one roller speed sensor. The at least one roller speed sensor may be configured to measure a rotational direction and rotational speed of a roller of the plurality of rollers 210. By providing the controller with a signal corresponding to at least a roller rotational direction, and optionally a roller rotational speed, it can be determined whether an abnormal roller reversal has occurred due to the carrier 100, particularly second rail 122, making bottom contact with said roller.

[0074] The active vector control may be configured to be performed as an openloop system, i.e. a feed forward system, which may have an advantage of low complexity and low computational overhead. Alternatively, the active vector control may be configured to be performed as a closed-loop system, i.e. a feedback system. For example, the controller on which the active vector control is performed may include a PI controller or a PID controller configured for carrying out the active vector control in a closed loop with feedback control. Further, a combination of feed forward control and feedback control may be used.

[0075] The controller may execute or perform a method or parts of a method for transporting a carrier 100 along a track assembly within an apparatus for vacuum processing of a substrate S according to aspects and embodiments of the present disclosure, and as exemplarily described herein.

[0076] According to a further aspect of the present disclosure, a method for transportation of a carrier 100 along a track assembly within an apparatus for vacuum processing of a substrate S is provided. The method includes counteracting a partial weight A, B of the carrier 100 using at least one passive magnetic unit 410, 610 of the track assembly and at least one passive magnetic unit 130, 140 of the carrier 100, supporting a total roller weight R of the carrier 100 using at least one of a plurality of rollers 210, 210a, 210b of the track assembly, transporting the carrier 100 along the track assembly in a transport direction X by generating a first carrier drive force Fa having a first vector with a first angle a _a relative to the transport direction X by operating a first active magnetic drive unit 510a of a plurality of active magnetic drive units 510, 510a, 510b, and controlling the first active magnetic drive unit 510a with active vector control to control the first angle a _a .

[0077] Parts of the method according to the above aspect may be carried out by the controller of the carrier transport system, e.g. performed as either a software routine or performed in hardware as described above. In particular, the controller may be provided to implement a software or hardware routine to carry out the operating of the first active magnetic drive unit 510a and the controlling of the first active magnetic drive unit 510a with active vector control to control the first angle a _a .

[0078] According to an embodiment, which may be combined with other embodiments described herein, the first carrier drive force Fa comprises a first carrier drive component Fxa in the transport direction X and a first carrier attraction component Fya in the vertical direction Y, and the controlling includes controlling the first angle a _a to adjust the magnitude of the carrier attraction component Fy. Optionally, the controlling may further include controlling the first angle a _a and a magnitude of the first carrier drive force Fa to adjust the magnitude of the first carrier attraction component Fya while simultaneously maintaining a magnitude of the first carrier drive component Fxa.

[0079] According to an embodiment, which may be combined with other embodiments described herein, the transporting may further include generating a second carrier drive force Fb having a second vector with a second angle a.b relative to the transport direction X by operating a second active magnetic drive unit 510b of the plurality of active magnetic drive units 510, 510a, 510b. The controlling may further include controlling the second active magnetic drive unit 510b with active vector control to control the second angle ab, wherein the second angle a.b is different to the first angle a _a . By controlling both a first carrier drive force Fa and a second carrier drive force Fb using active vector control, i.e. by controlling the respective vector angles a _a , ab of first and second carrier drive force Fa, Fb, the magnitude of the respective carrier attraction forces Fya, Fyb may be adjusted to be different along the length of carrier 100.

[0080] In a preferred embodiment, methods of the present disclosure are implemented to maintain top contact with the plurality of rollers 210, 210a, 210b by controlling the plurality of active magnetic drive units 510, 510a, 510b. Particularly, the first angle a _a and optionally the second angle ab are controlled, and in turn the magnitude of a first carrier attraction force Fya and optionally the magnitude of a second carrier attraction force Fyb are controlled, such that the carrier 100 maintains top contact with the plurality of rollers 210, 210a, 210b. [0081] More particularly, the plurality of active magnetic drive units 510, 510a, 510b may be controlled so that the total roller weight R is at most 10% of a weight W of carrier 100, preferably at most 5% of the weight W of carrier 100, more preferably at most 1% of the weight W of carrier 100.

[0082] According to an embodiment, which may be combined with other embodiments described herein, the method may further include measuring at least one signal and controlling the plurality of active magnetic drive units 510, 510a, 510b depending on the at least one signal. The at least one signal may include a carrier position signal, at least one roller weight signal, at least one roller speed signal and/or at least one roller contact signal. The method of this embodiment may be implemented as an open-loop (feed-forward) system or as a closed-loop (feedback) system.

[0083] According to an embodiment, which may be combined with other embodiments described herein, the active vector control includes defining a first current, a second current and a third current to be applied to a respective first, second and third coil of the first active magnetic drive unit 510a, defining a d-q coordinate system having a direct axis d and a quadrature axis q for each of the first, second and third currents, such that a d-current corresponding to a field flux linkage current component of each respective first, second and third currents is aligned along the direct axis, and a q-current corresponding to a driving force current component of each respective first, second and third currents is aligned along the quadrature axis. Controlling the phase angle between the respective d-currents may be performed to control a magnitude of the first carrier attraction component Fya, and controlling the phase angle between the respective q-currents may be performed to control a magnitude of the first carrier drive component Fxa.

[0084] According to an aspect of the present disclosure, an apparatus for vacuum processing of a substrate S is provided. The apparatus includes at least one vacuum chamber, a carrier transport system according to embodiments described herein, and a carrier 100 for supporting the substrate. The carrier 100 includes at least one passive magnetic unit 130, 140, a first rail 120 configured to be in top contact with a plurality of rollers 210, 210a, 210b, a second rail 122 configured to be in bottom contact with the plurality of rollers 210, 210a, 210b and a magnetic drive element 150 configured to be driven by the drive assembly 500. The carrier transport system is configured for transporting carrier 100 into or out of the at least one vacuum chamber. Particularly, the carrier transport system is configured for transporting carrier 100 over a gap transition, for example, at an input/ output valve of the at least one vacuum chamber.

[0085] In a preferred embodiment, which may be combined with other embodiments described herein, the first passive magnetic unit 410 of the track assembly is configured to be at a top of the carrier 100 to be coupled with the first passive magnetic unit 130 of the carrier 100, and the second passive magnetic unit 610 of the track assembly is configured to be at a side of the carrier 100 to be coupled with the second passive magnetic unit 140 of the carrier. The drive assembly is configured to be at a bottom of the carrier 100 to be coupled with the magnetic drive element 150 of the carrier 100.

[0086] According to an embodiment, which may be combined with other embodiments described herein, the plurality of active magnetic drive units 510, 510a, 510b may be configured to interact with the magnetic drive element 150 of the carrier 100 to maintain top contact between the first rail 120 of the carrier 100 and the plurality of rollers 210, 210a, 210b.

[0087] The apparatus for vacuum processing of a substrate S may further include a processing device. In particular, typically the processing device is arranged in the at least one vacuum chamber and the processing device may be selected from the group consisting of a deposition source, an evaporation source, and a sputter source.

[0088] The term “vacuum” can be understood in the sense of a technical vacuum having a vacuum pressure of less than, for example, 10 mbar. Typically, the pressure in the at least one vacuum chamber as described herein may be between 10' ⁵ mbar and about 10' ⁸ mbar, more typically between 10' ⁵ mbar and 10' ⁷ mbar, and even more typically between about 10' ⁶ mbar and about 10' ⁷ mbar. The pressure in the at least one vacuum chamber may be considered to be either the partial pressure of the evaporated material within the at least one vacuum chamber or the total pressure (which may approximately be the same when only the evaporated material is present as a component to be deposited in the at least one vacuum chamber). The total pressure in the at least one vacuum chamber may range from about 10' ⁴ mbar to about 10' ⁷ mbar, especially in the case that a second component besides the evaporated material is present in the at least one vacuum chamber (such as a processing gas or the like). Accordingly, the at least one vacuum chamber can be a “vacuum deposition chamber”, i.e. a vacuum chamber configured for vacuum deposition.

[0089] For transporting carrier 100 into and out of the at least one vacuum chamber, the apparatus for vacuum processing of a substrate S may further include at least one valve. In the context of the present disclosure, the valve may be considered to be equivalent to a gap transition 300 across which carrier 100 is to be transported. The valve may include, for example, a sealable sliding door configured for isolating the environment inside one vacuum chamber from the environment of an adjacent vacuum chamber. The valve may be included in a load lock chamber configured for loading carrier 100 and/or substrate S into the apparatus.

[0090] The vacuum chamber may include at least one carrier transport system according to embodiments described herein. The at least one carrier transport system may be configured for operating in two directions, i.e. a two-way transport of carrier 100 in both a forward transport direction and a reverse transport direction. Alternatively, a second carrier transport system may be provided, wherein the first carrier transport system is configured for operating in one direction, and the other carrier transport system is configured for operating in the other direction.

[0091] Embodiments described herein can be used for transporting carriers carrying at least one of large-area substrates, glass substrates, wafers, semiconductor substrates, masks, shields, and other objects. The carriers can carry one single object, e.g., a large-area substrate with a size of 1 m ² or more, particularly 5 m ² or 10 m ² or more, or a plurality of objects having a smaller size, e.g. a plurality of semiconductor wafers. The carrier may include a holding device configured to hold the object at the carrier, e.g. a magnetic chuck, an electrostatic chuck, or a mechanical chucking device.

[0092] The carrier may have an essentially vertical orientation during transport (e.g., vertical +/- 10°). Specifically, the vacuum processing system may be configured for vertical substrate processing. [0093] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.