WO2022058014A1

WO2022058014A1 - Cathode assembly, deposition apparatus and method for sputter deposition

Info

Publication number: WO2022058014A1
Application number: PCT/EP2020/075990
Authority: WO
Inventors: Reiner Hinterschuster; Anke Hellmich
Original assignee: Applied Materials Inc
Current assignee: Applied Materials Inc
Priority date: 2020-09-17
Filing date: 2020-09-17
Publication date: 2022-03-24
Anticipated expiration: 2023-03-17

Abstract

A cathode assembly (110) for sputter deposition is provided. The cathode assembly includes a first cathode drive unit (113) configured to rotate a first rotatable cathode (111), a second cathode drive unit (114) adjacent to the first cathode drive unit configured to rotate a second rotatable cathode (112), and a connecting element (120) configured to connect the first rotatable cathode and the second rotatable cathode at a side of the cathode assembly opposite the first cathode drive unit and to provide a cantilevered cathode assembly.

Description

CATHODE ASSEMBLY, DEPOSITION APPARATUS AND METHOD FOR SPUTTER DEPOSITION

FIELD OF INVENTION

[0001] Embodiments described herein relate to layer deposition by sputtering from a target. Particularly, embodiments of the present disclosure may relate to a cathode assembly and an apparatus for sputter deposition. Some embodiments particularly relate to a cathode assembly for vertical sputter deposition in a vacuum environment, and particularly to a rotatable cathode assembly.

BACKGROUND

[0002] In many applications, it is necessary to deposit thin layers on a substrate. The substrates can be coated in one or more chambers of a coating apparatus. The substrates may be coated in a vacuum, using a vapor deposition technique.

[0003] Several methods are known for depositing a material on a substrate. For instance, substrates may be coated by a physical vapor deposition (PVD) process, a chemical vapor deposition (CVD) process or a plasma enhanced chemical vapor deposition (PECVD) process etc. The process is performed in a process apparatus or process chamber where the substrate to be coated is located. A deposition material is provided in the apparatus. A plurality of materials, and also oxides, nitrides or carbides thereof, may be used for deposition on a substrate. Coated materials may be used in several applications and in several technical fields. For instance, substrates for displays are often coated by a physical vapor deposition (PVD) process. Further applications include insulating panels, organic light emitting diode (OLED) panels, substrates with thin film transistors (TFT), color filters or the like.

[0004] For a PVD process, the deposition material can be present in the solid phase as a target. By bombarding the target with energetic particles, atoms of the target material, i.e. the material to be deposited, are ejected from the target. The atoms of the target material are deposited on the substrate to be coated. In a PVD process, the sputter material, i.e. the material to be deposited on the substrate, may be arranged in different ways. For instance, the target may be made from the material to be deposited or may have a backing element on which the material to be deposited is fixed. The target including the material to be deposited is supported or fixed in a predefined position in a deposition chamber.

[0005] Segmented or monolithic targets, for example planar or rotatable targets may be used for sputtering. Due to the geometry and design of the cathodes, rotatable targets typically have a higher utilization and an increased operation time than planar ones. The use of rotatable targets may prolong service life and reduces costs.

[0006] The cathode assemblies include drive units for rotating the cathode and/or targets which are subject to maintenance. Accordingly, it is beneficial to provide an improved arrangement and set-up of the cathode assembly for providing the target material in the deposition process.

SUMMARY

[0007] In light of the above, a cathode assembly for sputter deposition is provided. The cathode assembly includes a first cathode drive unit configured to rotate a first rotatable cathode, a second cathode drive unit adjacent to the first cathode drive unit configured to rotate a second rotatable cathode, and a connecting element configured to connect the first rotatable cathode and the second rotatable cathode at a side of the cathode assembly opposite the first cathode drive unit and to provide a cantilevered cathode assembly.

[0008] According to an aspect, a deposition apparatus for depositing a material onto a substrate is provided. The apparatus includes a vacuum chamber and a cathode assembly according to embodiments described herein. According to a further optional aspect, the first cathode drive unit and the second cathode drive unit of the cathode assembly are arranged outside the vacuum chamber.

[0009] According to a further aspect, a method for sputter deposition is provided. The method includes providing a cathode assembly according to embodiments described herein in a vacuum chamber and depositing a material with the cathode assembly onto a substrate. [0010] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the present disclosure are also directed at methods for operating the described apparatus. It includes method aspects for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] 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 front view of a deposition apparatus according to embodiments described herein;

Fig. 2 shows a schematic view of a connecting element according to embodiments described herein;

Figs. 3 A and 3B show a schematic side view of a deposition apparatus according to embodiments described herein; and

Fig. 4 shows a flow diagram of a method according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0012] 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. Generally, 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.

[0013] Generally, sputtering can be undertaken as diode sputtering or as magnetron sputtering. Magnetron sputtering is particularly advantageous in that the deposition rates are rather high. By arranging the magnet assembly or magnetron behind the sputter material of the cathode or sputter target, in order to trap the free electrons within the magnetic field, which is generated in the direct vicinity of the target surface, these electrons are forced to move within the magnetic field and cannot escape. This enhances the probability of ionizing the gas molecules typically by several orders of magnitude. This, in turn, increases the deposition rate substantially. For example, in the event of a rotatable sputter target, which may have an essentially cylindrical form, the magnet assembly can be positioned inside the rotatable cathode or sputter target.

[0014] Furthermore, sputtering may also be utilized when depositing a material onto a sensitive substrate, e.g. a substrate that has previously been processed. Accordingly, sputtering, and in particular magnetron sputtering can be used as a kind of finishing process to further process the already processed substrate differently. To achieve processing of the sensitive substrate, e.g. a substrate including OLED layers, several adaptations can be made to the sputtering process, e.g. the position of the rotatable sputtering cathodes, i.e. the arrangement and/or orientation of the magnet assemblies of the cathode assembly, can be adapted such that low energy spray coating occurs towards the sensitive substrate.

[0015] As an example, deposition may include sputtering of a transparent conductive oxide film. Deposition may include sputtering of materials like ITO, IZO, IGZO or MoN. Further, deposition may include sputtering of silver (Ag), Ag alloys and/or magnesium (Mg). Further exemplarily, deposition may include sputtering of metallic material. Thus, sputtering may be utilized for the deposition of electrodes, particularly transparent electrodes in displays, particularly OLED displays, liquid crystal displays, and touchscreens. Further, sputtering may be utilized for the deposition of electrodes, particularly transparent electrodes in thin film solar cells, photodiodes, and smart or switchable glass. [0016] The term “magnet assembly” as used herein may refer to a unit capable of generating a magnetic field. Typically, the magnet assembly may consist of a permanent magnet. This permanent magnet may be arranged within the cathode or sputter target such that charged particles can be trapped within the generated magnetic field, e.g. in an area above the sputter target. In some embodiments, the magnet assembly includes a magnet yoke.

[0017] The substrate can be continuously moved during coating past the cathode assembly (“dynamic coating”), or the substrate may rest essentially at a constant position during coating (“static coating”). Further, also substrate sweeping or substrate wobbling may be possible. The embodiments described in the present disclosure relate to both dynamic coating and static coating processes.

[0018] According to some examples, a large area substrate can be GEN 4.5, which corresponds to about 0.67 m² substrates (0.73x0.92m), GEN 5, which corresponds to about 1.4 m² substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m² substrates (1.95 m x 2.2 m), GEN 8, which corresponds to about 5.3m² substrates (2.16 m x 2.46 m), or even GEN 10, which corresponds to about 9.0 m² substrates (2.88 m x 3.13 m). Even larger generations such as GEN 11, GEN 12 and/or corresponding substrate areas can similarly be implemented. A deposition apparatus according to embodiments described herein may be configured for deposition on large area substrates.

[0019] The term “substrate” as used herein shall particularly embrace inflexible substrates, e.g., glass plates. The present disclosure is not limited thereto, and the term “substrate” may also embrace flexible substrates such as a web or a foil. Further, also a sensitive substrate may be included.

[0020] The term “coating” and the term “depositing” are used synonymously herein. The coating or deposition process used in embodiments described herein is sputtering, particularly PVD sputtering.

[0021] According to embodiments that can be combined with other embodiments described herein, a deposition apparatus for depositing a material onto a substrate is provided. Fig. 1 exemplarily shows a front view of a deposition apparatus 100 for depositing a material onto a substrate employing a cathode assembly 110 according to embodiments described herein. [0022] According to embodiments, the deposition apparatus 100 as exemplarily shown in Fig. 1 includes a vacuum chamber 105. The vacuum chamber may include a top wall 106 and a bottom wall 107. The apparatus 100 further includes a cathode assembly 110. The cathode assembly includes a first cathode drive unit 113 configured to rotate a first rotatable cathode 111. Further, the cathode assembly includes a second cathode drive unit 114 adjacent to the first cathode drive unit 113 configured to rotate a second rotatable cathode 112. The cathode assembly 110, i.e. the first rotatable cathode 111 and the second rotatable cathode 112, may include the first rotatable target and the second rotatable target.

[0023] According to embodiments that can be combined with any other embodiment described herein, the first cathode drive unit 113 and the second cathode drive unit 114 may be arranged outside the vacuum chamber. Accordingly, the first cathode drive unit 113 and the second cathode drive unit 114 may extend through the chamber wall. Accordingly, the first and second cathode drive units may be detachably connected to the first rotatable cathode 111 and the second rotatable cathode 112 inside the vacuum chamber, respectively. Additionally or alternatively, the first cathode drive unit 113 and the second cathode drive unit 114 may be arranged inside the vacuum chamber. The first cathode drive unit and the second cathode drive unit may be provided at the top wall 106 and/or at the bottom wall 107 of the vacuum chamber i.e. the first cathode drive unit and the second cathode drive unit may be provided at the top wall 106 and/or at the bottom wall 107 inside and/or outside the vacuum chamber. The first and second drive units may extend through the top wall 106 and/or the bottom wall 107 of the vacuum chamber for being connected to the first and second rotatable cathode, respectively. The first cathode drive unit 113 and the second cathode drive unit 114 may each include a bearing for allowing a rotational movement of the driven first and/or second rotatable cathodes.

[0024] According to embodiments that can be combined with any other embodiment described herein, the cathode assembly may be oriented substantially vertically in the vacuum chamber. Alternatively, the cathode assembly may be oriented substantially horizontally in the vacuum chamber. The first and second rotatable cathodes may be arranged substantially vertically or substantially horizontally in the vacuum chamber i.e. the first rotatable cathode and the second rotatable cathode may extend from the top of the vacuum chamber towards the bottom of the vacuum chamber or vice versa or from a side wall of the vacuum chamber to another side wall of the vacuum chamber. The terms “substantially vertically” or “substantially horizontally” may include cathode assemblies which are arranged at a small deviation from exact verticality or horizontality, e.g. an angle of up to 10° or even 15° may exist between the cathode assembly and the exact vertical or exact horizontal direction. Furthermore, the apparatus according to embodiments described herein may be configured for deposition on substantially vertically oriented substrates.

[0025] According to embodiments that can be combined with any other embodiment described herein, the first cathode drive unit and the second cathode drive unit may be configured for providing a rotational movement to the first and second rotatable cathode. The first and second drive unit may include mechanical, electrical and/or magnetic drive units for rotating the first and second rotatable cathodes. As an example, the first drive unit and the second drive unit may include electrical motors, particularly each including at least one drive belt for transferring energy to the first and second rotatable cathodes, e.g. for transferring energy to a first and a second shaft to which the first and second rotatable cathodes may be connected to provide for a rotational movement of the first and second cathodes. Further, power supplies, coolant supplies and respective sealings may be provided at the first and second drive unit. The first and second drive unit may be arranged outside the vacuum chamber, i.e. under atmospheric pressure conditions. To allow for a connection of the first and second drive unit with the first and second rotatable cathode, the first and second drive unit may extend through a chamber wall of the vacuum chamber. Alternatively, the first and second cathode may extend through the chamber wall and may be detachably connected to the first and second drive unit outside the vacuum chamber. At the chamber wall, vacuum-tight sealings may be provided, e.g. sealings configured to allow for a rotational movement and/or sealings configured for static sealing. The first and second drive unit each may further include a bearing to allow for a rotational movement of the first and second rotatable cathode, respectively.

[0026] According to embodiments that can be combined with any other embodiment described herein, the first cathode drive unit 113 and the second drive unit 114 may be configured for rotating the first rotatable cathode and the second rotatable cathode, respectively. The first and second cathode may be rotated in the same direction or in different directions. For example, the first rotatable cathode 111 may be rotated clockwise and the second rotatable cathode 112 may be rotated anticlockwise or vice versa. Accordingly, the first cathode drive unit 113 may induce a rotation of the first rotatable cathode in a direction and the second cathode drive unit 114 may induce a rotation of the second rotatable cathode in a direction different from the direction induced by the first cathode drive unit. The first rotatable cathode may be rotated around a first axis Al and the second rotatable cathode may be rotated around a second axis A2.

[0027] According to embodiments that can be combined with any other embodiment described herein, a magnet assembly may be arranged in a cathode i.e. in the first and/or second rotatable cathode or cathode assembly. A magnet assembly may be surrounded by a target material. Each of the first and second cathodes may include a magnet assembly. Each of the magnet assemblies may be surrounded by a different target material or the same target material. A magnet assembly may be arranged so that the target material sputtered by the cathode assembly is sputtered towards a substrate or towards the remaining cathode i.e. the target material may be sputtered from one cathode in the direction of the other cathode and vice versa. A magnet assembly may generate a magnetic field. The magnetic field may cause one or more plasma regions to be formed near the magnetic field during a sputter deposition process. The position of the magnet assembly within a cathode assembly affects the direction in which target material is sputtered away from or towards the cathode assembly during a sputter deposition process. The magnet assembly can confine the plasma during sputtering. An improved sputtering process can be provided with the magnet assembly.

[0028] According to some embodiments, which can be combined with other embodiments described herein, the magnet assembly can be moved within the cathode or the target, respectively. Accordingly, the first rotatable cathode 111 and the second rotatable cathode 112 or the targets, respectively may each rotate around an axis, i.e. the first rotatable cathode may rotate around the axis Al and the second rotatable cathode may rotate around the axis A2. Accordingly, the magnet assembly can be provided at various angular coordinates relative to the axes. A movement of the magnet assembly, for example, a movement by an angle, can result in an adjustable deposition direction of the sputtering cathode. Accordingly, the amount of material reaching the substrate can be adjusted and specifically regulated. For example, one or more magnet assemblies can be movable, for example, to determine a beneficial magnet position. According to some embodiments, in the event of a predetermined magnet position, the magnet assemblies may be fixed. Yet further, the magnet positions between different pairs of cathodes may vary, i.e. a first cathode pair may have first magnet assembly positions and a second pair of cathodes may have second cathode assembly positions different from the first magnet assembly position. Accordingly, the deposition apparatus may include an even number of cathodes, i.e. the cathodes may be arranged in cathode pairs.

[0029] According to embodiments that can be combined with any other embodiment described herein, the deposition apparatus may include an odd number of cathodes.

[0030] According to some embodiments, sputtering at least a material, e.g. one first material, from a first rotary target with a first magnet assembly and from a second rotary target, also providing the one first material, with a second magnet assembly can be provided. The first magnet assembly can be disposed within the first rotary target providing a first plasma confinement in a first direction facing towards the second rotary target. The second magnet assembly can be disposed within the second rotary target providing a second plasma confinement in a second direction facing towards the first rotary target. For example, plasma confinement of the first rotary target facing the second target and the plasma confinement of the second rotary target facing the first target may have the advantage that a soft deposition is achieved. For example, bombardment of the substrate with high energy particles may be reduced. Damage to the substrate, particularly to a coating on the substrate, may be mitigated. The above described magnet position may be utilized to adapt the process to result in a compromise between a low energy deposition, particularly for generating an initial layer or seed layer, and a deposition rate which is increased as compared to low energy deposition particularly after an initial layer or seed layer has been deposited on a substrate, more particularly wherein the initial layer or layer portion protects the substrate or layers on a substrate from particles with higher energies.

[0031] Embodiments of the present disclosure can reduce displacement of targets, which may be caused by interaction of magnet assemblies in neighboring targets, particularly for magnet assemblies facing each other.

[0032] According to embodiments that can be combined with any other embodiment described herein, the first rotatable cathode i.e. a first magnet assembly of the first rotatable cathode may provide a first plasma confinement in a first direction facing towards the second rotatable cathode i.e. a second magnet assembly of the second rotatable cathode. The second magnet assembly within the second rotatable cathode may provide a second plasma confinement in a second direction facing towards the first rotatable cathode or first magnet assembly. The apparatus may be configured such that the first direction and the second direction deviate from being parallel to a substrate plane by an angle of less than 90°, e.g. less than 45° or less than 40°, for example 0°. In the context of the present disclosure, the “substrate plane” particularly refers to a plane of the substrate whereupon the material is deposited. In particular, the first and the second direction may deviate from being parallel to the substrate plane by an angle of for example less than 90°, 50°, 30°, 20° or 10°.

[0033] According to embodiments that can be combined with any other embodiment described herein, the cathode assembly 110 further includes a connecting element 120. The connecting element 120 is configured to connect the first rotatable cathode 111 and the second rotatable cathode 112 at a side of the cathode assembly opposite the first cathode drive unit 113 and to provide a cantilevered cathode assembly. In other words, the connecting element may be configured to allow a distant mutual support of the first cathode drive unit and the second cathode drive unit. The connecting element may connect the first rotatable cathode and the second rotatable cathode such that the first and second cathodes mutually support each other. Further, the connecting element 120 may stabilize the cathode assembly in a free space of the vacuum chamber.

[0034] The term “cantilevered” as used herein may be understood as one end of the cathode assembly being arranged freely in a space. The free space may be the chamber, e.g. vacuum chamber, in which the cathode assembly may be arranged. One end of the cathode assembly i.e. the free ends of the first and second cathode being connected to the connecting element, may thus be free of contact with respect to other components of the deposition apparatus, like e.g. the chamber walls, chamber doors and the like. A weight of the cathode assembly may be carried solely by the vacuum chamber, i.e. the chamber walls (top or bottom) and/or the cathode drive units, respectively.

[0035] According to embodiments that can be combined with any other embodiment described herein, the connecting element may include one or more pins 122 for connecting the connecting element to the first rotatable cathode and the second rotatable cathode. For example, the one or more pins may be partially inserted into an end of the first cathode and the second cathode. The one or more pins may extend from the connecting element in a substantially perpendicular direction with respect to a base portion 124 of the connecting element. Particularly, the connecting element may include two pins, i.e. one pin for being connected to the first rotatable cathode 111 and one pin for being connected with the second rotatable cathode 112. Accordingly, each of the two pins may be configured to be connected i.e. to be at least partially inserted into one of the first rotatable cathode and the second rotatable cathode. Further, the two pins may be rotatable with the first rotatable cathode and the second rotatable cathode. Accordingly, the connecting element may connect cathodes pairwise.

[0036] Additionally, if the cathode assembly includes more than two cathodes, e.g. four cathodes, six cathodes or ten cathodes, the connecting element may include as many pins as cathodes are provided. Accordingly, the one or more pins may be configured to provide a connection between the connecting element and the cathodes. Accordingly, more than two cathodes may be connected with the connecting element.

[0037] Advantageously, the one or more pins, in particular the two pins, for connecting the first rotatable cathode and the second rotatable cathode may elongate the cathodes such that a rotatable connection of the cathodes and the connecting element may be allowed.

[0038] According to embodiments that can be combined with any other embodiment described herein, the connecting element may include i.e. may be made of a vacuum-stable material, particularly a material selected from the group of stainless steel and alumina. Typically, the material of the connecting element may be vacuum-resistant, i.e. a material may be chosen that may not be susceptible to outgassing effects.

[0039] Fig. 2 shows a schematic view of a connecting element 120 according to embodiments that can be combined with any other embodiment described herein. The connecting element 120 may include one or more pins 122 and a base portion 124. The connecting element 120 may include at least one first bearing 126 adjacent to the first rotatable cathode 111 and at least one second bearing 128 adjacent to the second rotatable cathode 112. The at least one first bearing 126 and the at least one second bearing 128 may be configured to allow for a rotational movement of the one or more pins. For example, the at least one first bearing and the at least one second bearing are arranged with the one or more pins. Further exemplarily, the at least one first bearing may be arranged adjacent to one pin of the one or more pins, i.e. the at least one first bearing may enable rotation of the pin around axis Al (seen in Fig. 1) and the at least one second bearing may be arranged adjacent to another pin of the one or more pins i.e. the at least one second bearing may enable rotation of the another pin around axis A2 (seen in Fig. 1). [0040] According to embodiments that can be combined with any other embodiment described herein, the at least one first bearing and the at least one second bearing may be rotation bearings or slide bearings. For example, a rotational movement of the one or more pins may be allowed. In particular, the rotation bearing may be a roller bearing, more particularly a ball bearing. Such bearings may be used under vacuum conditions while being robust and dimensionally scalable.

[0041] According to embodiments that can be combined with any other embodiment described herein, the connecting element may include two pins for being connected to the first and the second rotatable cathode. Adjacent to each of the two pins, two bearings, particularly ball bearings may be arranged to allow for a rotational movement of the two pins; i.e., two first bearings may be arranged adjacent to the pin connected to the first rotatable cathode and two second bearings may be arranged adjacent to the pin connected to the second rotatable cathode. Thus, the rotational movement of the two pins may be allowed. The rotational movement of the two pins may be synchronous with the respective rotation of the first and second rotatable cathode.

[0042] Advantageously, the connecting element provides support to the cathode assembly. Further, the connecting element ensures the rotational movement of the cathodes while supporting the cathodes in a free space. By connecting the first cathode drive unit and the second cathode drive unit by connecting the ends of the first rotatable cathode and the second rotatable cathode, the cathode assembly is stabilized without the ends of the cathodes being attached to further rigid elements of the deposition apparatus e.g. the vacuum chamber walls, chamber doors and the like. Further advantageously, the transmission of forces from other elements of the deposition apparatus towards the cathode assembly, e.g. vibrations, thermal expansion forces and/or other deformation forces is effectively prevented or avoided. Therefore, especially the cathode drive unit i.e. the first and the second cathode drive unit can be effectively protected and the lifetime of the drive units can be prolonged.

[0043] Further advantageously, other forces like vibrations, thermal deformations and the like resulting from e.g. pressure differences are effectively absorbed such that the cathode drive units, i.e. the first and the second cathode drive unit, are protected against damage and (material) wear. Particularly, the bearings of the drive units are protected. Accordingly, the lifetime of the drive unit bearings and other components of the cathode assembly can be prolonged and maintenance of the cathode assembly and the components like bearings or the drive unit may occur less frequently. Thus, costs can be saved, the process can be more efficient and a yield loss of processed substrates can be avoided.

[0044] Further, the other forces may be kept away from the drive units to ensure accurate function of the drive units. In particular, the arrangement and/or orientation of the magnetic assemblies within the rotatable cathodes to allow for low energy coating may result in magnetic forces acting on the cathodes as attracting and/or repulsing forces. Vibrations and deformations of the cathodes may be reduced. The connecting element may avoid or prevent excessive vibrations and deformations of the cathodes by stabilizing the cantilevered cathode assembly.

[0045] Figs. 3 A and 3B show a schematic side view of a deposition apparatus 300, 300’ according to embodiments described herein. The deposition apparatus includes a cathode assembly according to any of the embodiments described herein, the first cathode drive unit and the second cathode drive unit being arranged outside the vacuum chamber. For example, the first cathode drive unit and the second cathode drive unit may be arranged at an outer top or outer bottom wall or an outer side wall of the vacuum chamber. The first and second drive units may extend through the respective wall for being detachably connected to a first rotatable cathode and a second rotatable cathode inside the vacuum chamber. The first and second drive unit may be drive units according to embodiments described herein.

[0046] Fig. 3A schematically depicts a side view of a deposition apparatus 300 where the drive unit, i.e. the first cathode drive unit 113 and the second cathode drive unit 114, may be arranged at a top wall 106 of the vacuum chamber 105. The connecting element 120 may be arranged below the cathode assembly 110 i.e. the first rotatable cathode and the second rotatable cathode may hang from the top wall 106 of the vacuum chamber 105 into the free space of the vacuum chamber. In other words, the cathode assembly may be arranged substantially vertically from the top towards the bottom of the vacuum chamber. Accordingly, the connecting element 120 may provide support to the cathode assembly at a bottom side of the cathode assembly.

[0047] Fig. 3B schematically depicts a side view of a deposition apparatus 300’ where the drive unit, i.e. the first cathode drive unit 113 and the second cathode drive unit 114, may be arranged at abottom wall 107 ofthe vacuum chamber 105. The connecting element 120 may be arranged above the cathode assembly 110 i.e. the first rotatable cathode and the second rotatable cathode may extend from the bottom wall 107 of the vacuum chamber 105 into the free space of the vacuum chamber. Accordingly, the connecting element 120 may provide support to the cathode assembly at a top side of the cathode assembly.

[0048] According to embodiments that can be combined with any other embodiment described herein, the deposition apparatus may include a transport system 340. The transport system 340 may be configured to transport a substrate 10 through the deposition apparatus in a transport direction parallel to the cathode assembly, i.e. parallel to a plane in which the first and second cathodes may be arranged. The transport system may be a mechanical transport system, a magnetic levitation system or a combination thereof.

[0049] According to embodiments that can be combined with any other embodiment described herein, the deposition apparatus may be configured for dynamic coating or static coating. For example, the substrate 10 may be continuously transported during deposition, i.e. the substrate may be transported past the cathode assembly during deposition. Alternatively, the substrate may be transported to the cathode assembly, stopped in front of the cathode assembly, and may be transported away from the cathode assembly after deposition has taken place.

[0050] According to embodiments that can be combined with any other embodiment described herein, the deposition apparatus may be configured for processing large area substrates. The deposition apparatus may include a plurality of cathodes. For example, four or more, such as six or more or even 10 or more cathodes may be provided. The plurality of cathodes may be connected by the connecting element, i.e. the connecting element may include as many pins of the one or more pins as cathodes are provided. Alternatively, two of the plurality of cathodes may be connected with one connecting element. The deposition apparatus may include half the number of connecting elements compared to the number of cathodes.

[0051] Fig. 4 shows a flow diagram of a method for sputter deposition according to embodiments described herein. The method 400 includes providing a cathode assembly according to any of the embodiments described herein in a vacuum chamber (exemplarily indicated by box 460) and depositing a material with the cathode assembly onto a substrate (exemplarily indicated by box 470). [0052] According to embodiments that can be combined with any other embodiment described herein, the cathode assembly may be provided substantially vertically in the vacuum chamber. Thus, deposition may occur towards a substrate being oriented or arranged substantially vertically in the vacuum chamber. In other words, the cathode assembly may be arranged in a plane and the substrate may be arranged in another plane substantially parallel to the plane in which the substrate may be arranged.

[0053] According to embodiments that can be combined with any other embodiment described herein, the cathode assembly, i.e. the first and second rotatable cathodes may include magnet assemblies. The magnet assemblies may be oriented such that the sputter material may be directed towards the respective other cathode. Accordingly, when the cathodes are rotating, every turn of a cathode may lead to the deposition of material on the respective other cathode of the cathode assembly. Accordingly, a plasma associated with the sputter deposition may be trapped between the first and the second rotatable cathodes and spray deposition may occur towards the substrate.

[0054] This may lead to a low energy sputter deposition in the direction of a substrate being arranged in front of the cathode assembly. The low energy sputter deposition or low energy stray coating may reach the substrate at a deposition angle of less than 90°. In particular, a deposition direction may deviate from being parallel to a substrate plane by an angle of less than 90°, e.g. less than 45° or less than 40°, for example 0°. The plane in which the substrate may be arranged, i.e. the substrate plane, may be substantially parallel to a plane of the cathode assembly, i.e. the plane in which the first and second rotatable cathodes are arranged side by side.

[0055] Advantageously, the low energy stray coating may allow for deposition of material onto sensitive substrates, e.g. substrates that already have been processed in a different process. Thus, finishing treatments of the substrate, e.g. a substrate including OLED layers, can be carried out particularly carefully and gently without unnecessarily damaging the processed substrate.

[0056] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

1. A cathode assembly (110) for sputter deposition, the cathode assembly comprising: a first cathode drive unit (113) configured to rotate a first rotatable cathode (111); a second cathode drive unit (114) adjacent to the first cathode drive unit configured to rotate a second rotatable cathode (112); and a connecting element (120) configured to connect the first rotatable cathode and the second rotatable cathode at a side of the cathode assembly opposite the first cathode drive unit and to provide a cantilevered cathode assembly.

2. The cathode assembly according to claim 1, wherein the connecting element comprises one or more pins for connecting the connecting element to the first rotatable target and the second rotatable target.

3. The cathode assembly (110) according to claim 2, wherein the one or more pins are rotatable with the first rotatable cathode and the second rotatable cathode.

4. The cathode assembly (110) according to any of claims 1 to 3, wherein the connecting element comprises two pins, each of the two pins being configured to be connected to one of the first rotatable cathode and the second rotatable cathode, the two pins being rotatable with the first rotatable cathode and the second rotatable cathode.

5. The cathode assembly (110) according to any of claims 2 to 4, wherein the connecting element comprises at least one first bearing adjacent to the first rotatable cathode and at least one second bearing adjacent to the second rotatable cathode.

6. The cathode assembly (110) according to claim 5, wherein the at least one first bearing and the at least one second bearing are rotation bearings, more particularly roller bearings or slide bearings, even more particularly ball bearings.

7. The cathode assembly (110) according to any of claims 5 to 6, wherein the at least one first bearing and the at least one second bearing are arranged with the one or more pins for allowing a rotation of the one or more pins.

8. The cathode assembly (110) according to any of claims 1 to 7, wherein the connecting element comprises a vacuum-stable material, particularly a material selected from the group comprising stainless steel and alumina.

9. The cathode assembly (110) according to any of the preceding claims, wherein the cathode assembly comprises the first rotatable cathode and the second rotatable cathode, each of the first rotatable cathode and the second rotatable cathode comprising a magnet assembly.

10. The cathode assembly (110) according to any of the preceding claims, wherein the first rotatable cathode comprises a first rotatable target and the second rotatable cathode comprises a second rotatable target.

11. A deposition apparatus (100) for depositing a material onto a substrate (10), the deposition apparatus comprising: a vacuum chamber (105); and a cathode assembly (110) according to any of claims 1 to 10, particularly wherein the first cathode drive unit (113) and the second cathode drive unit (114) of the cathode assembly are arranged outside the vacuum chamber.

12. The deposition apparatus (100) according to claim 11, wherein the vacuum chamber comprises a chamber wall, the first cathode drive unit (113) and the second cathode drive unit (114) extending through the chamber wall for being detachably connected to the first rotatable cathode and the second rotatable cathode inside the vacuum chamber.

13. The deposition apparatus (100) according to any of claims 11 or 12, wherein the vacuum chamber (105) comprises a top wall (106) and a bottom wall (107), the first cathode drive unit and the second cathode drive unit being provided at the top wall or the bottom wall.

14. The deposition apparatus (100) according to any of claims 11 to 13, wherein the deposition apparatus further comprises a transport system (340) for transporting a substrate (10) through the deposition apparatus and along the cathode assembly (110).

15. A method (400) for sputter deposition, the method comprising: providing (460) a cathode assembly according to any of claims 1 to 10 in a vacuum chamber; and depositing (470) a material with the cathode assembly onto a substrate.

16. The method according to claim 15, wherein the substrate (10) is arranged in a plane and depositing a material comprises regulating the first cathode drive unit (113) and the second cathode drive unit (114) to allow the material to reach the substrate (10) in a deposition angle, particularly a deposition angle of less than 90° with respect to the plane of the substrate.

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