WO2018149510A1

WO2018149510A1 - Deposition apparatus for coating a flexible substrate and method of coating a flexible substrate

Info

Publication number: WO2018149510A1
Application number: PCT/EP2017/053790
Authority: WO
Inventors: Valerius Mett; Thomas Deppisch; Stefan Hein; Jürgen Ulrich; Christof Kurthen
Original assignee: Applied Materials, Inc.
Priority date: 2017-02-20
Filing date: 2017-02-20
Publication date: 2018-08-23

Abstract

A deposition apparatus (100) for coating a flexible substrate (10) with at least one layer is described. The deposition apparatus comprises: a first spool chamber (110) configured for housing a storage spool for providing the flexible substrate; a first deposition chamber (120) arranged downstream from the first spool chamber and comprising a first coating drum (122) configured for guiding the flexible substrate past a first plurality of deposition units (121); a second deposition chamber (140) arranged downstream from the first deposition chamber (120) and comprising a second coating drum (142) configured for guiding the flexible substrate past a second plurality of deposition units (141); a second spool chamber arranged downstream from the second deposition chamber (140) and configured for housing a wind-up spool for winding the flexible substrate thereon after deposition; and a roller assembly configured to transport the flexible substrate (10) along a partially convex and partially concave substrate transportation path from the first spool chamber to the second spool chamber. Further, a method of coating a flexible substrate, particularly with the described deposition apparatus, is described.

Description

DEPOSITION APPARATUS FOR COATING A FLEXIBLE SUBSTRATE AND METHOD OF COATING A FLEXIBLE

SUBSTRATE FIELD

[0001] The present disclosure relates to thin-film deposition apparatuses and methods, particularly to apparatuses and methods for coating flexible substrates with a stack of at least one thin layer, particularly in roll-to-roll (R2R) deposition systems. BACKGROUND

[0002] Processing of flexible substrates, such as plastic films or foils, is in high demand in the packaging industry, semiconductor industries and other industries. Processing may consist of coating of a flexible substrate with a material, such as a metal, a semiconductor and a dielectric material, etching and other processing actions conducted on a substrate for the respective applications. Systems performing this task generally include a coating drum, e.g. a cylindrical roller, coupled to a processing system with a roller assembly for transporting the substrate, and on which at least a portion of the substrate is coated. Roll-to-roll (R2R) coating systems can provide a high throughput. [0003] Therein, a coating process such as a CVD process or a PVD process, particularly a sputter process, can be utilized for depositing thin layers onto flexible substrates. Roll-to-roll deposition systems are understood in that a flexible substrate of a considerable length, such as one kilometre or more, is uncoiled from a storage spool, coated with a stack of thin layer(s), and recoiled again on a wind-up spool. In the manufacture of thin film batteries as well as in the display industry and the photovoltaic (PV) industry, the demand for roll-to- roll deposition systems is also increasing. For example, touch panel elements, flexible displays, and flexible PV modules result in an increasing demand for depositing suitable layers in R2R-coaters. - -

[0004] A challenge is posed by the coating of layers which are sensitive directly after the coating process, e.g. may easily be scratched or are prone to accretion of small particles, which is partly known under the term "winding defects". One known aspect out of several for approaching these issues is to use cleaning rollers in the substrate transportation path, over which the provided coated substrate is guided. However, such cleaning rollers themselves may contribute, at least slightly, to a worsening of the state of the coated substrate.

[0005] In view of the above and for other reasons, there is a need for the present invention.

SUMMARY

[0006] In light of the above, a deposition apparatus for coating a flexible substrate, and a method of coating a flexible substrate are provided. Further aspects, advantages, and features are apparent from the dependent claims, the description, and the accompanying drawings.

[0007] According to a first aspect, a deposition apparatus for coating a flexible substrate is provided. The deposition apparatus includes: a spool chamber, configured for housing a storage spool for providing the flexible substrate, and for housing a wind-up spool for receiving the coated substrate; a first deposition chamber arranged adjacent to the spool chamber and comprising a first coating drum configured for guiding the flexible substrate past a first plurality of deposition units; and a roller assembly configured to transport the flexible substrate along a first substrate transport path from the storage spool in the spool chamber to the first deposition chamber and subsequently along a second substrate transport path from the first deposition chamber to the wind-up spool in the spool chamber, and wherein one of the first transport path and the second transport path provides a contact of the roller assembly on both sides of the flexible substrate, and the other one of the first transport path and the second transport path provides a contact of the roller assembly only on the back surface of the flexible substrate. [0008] According to a further aspect, a method of coating a flexible substrate with at least one layer, particularly with a deposition apparatus according to the first aspect, is provided. The method comprises unwinding the flexible substrate from a storage spool provided in the spool chamber; depositing at least one first layer on a main surface of the flexible substrate, while the flexible substrate is guided by a first coating drum provided in a first deposition chamber; and winding the flexible substrate on a wind-up spool provided in the spool chamber after deposition. Thereby, the flexible substrate is guided along a substrate first transportation path from the storage spool in the spool chamber to the deposition chamber, and subsequently along a second substrate transport path from the deposition chamber to the wind-up spool in the spool chamber, wherein one of the first transportation path and the second transportation path provides a contact of the roller assembly on both sides of the flexible substrate, and the other one of the first transportation path and the second transportation path provides a contact of the roller assembly only on the back side of the flexible substrate.

[0009] Embodiments are also directed to apparatuses for carrying out each of the disclosed methods and including apparatus parts for performing each described method feature. The method features 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 are also directed to methods which the described apparatus operates with or which the described apparatus is manufactured by. The method includes method features for carrying out functions of the apparatus or manufacturing parts of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Some of the above indicated and other more detailed aspects of embodiments will be described in the following description and partially illustrated with reference to the figures. - -

Fig. 1 shows a sectional schematic view of a deposition apparatus according to embodiments described herein;

Fig. 2 shows a sectional schematic view of a deposition apparatus according to embodiments described herein; Fig. 3 shows a sectional schematic view of a deposition apparatus according to embodiments described herein.

Fig. 4 shows a schematic diagram of a method according to embodiments.

DETAILED DESCRIPTION OF EMBODIMENTS

[0011] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that the description includes such modifications and variations. [0012] It is noted that a flexible substrate as used within the embodiments described herein is typically bendable. The term "flexible substrate" or "substrate" may be synonymously used with the term "foil" or the term "web". In particular, it is to be understood that embodiments of the deposition apparatus described herein can be utilized for coating any kind of flexible substrate, e.g. for manufacturing flat coatings with a uniform thickness, or for manufacturing coating patterns or coating structures in a predetermined shape on the flexible substrate or on top of an underlying coating structure. For example, electronic devices may be formed on the flexible substrate by masking, etching and/or depositing. For example, a flexible substrate as described herein may include materials like PET, HC-PET, PE, PI, PU, TaC, OPP, CPP, one or more metals, paper, combinations thereof, and already coated substrates like Hard Coated PET (e.g. HC-PET, HC-TaC) and the like. In some embodiments, the flexible substrate is a COP substrate provided with an index matched (IM) layer on both sides thereof.

[0013] Embodiments described herein generally relate to apparatuses and methods for coating a flexible substrate with a stack of layers. A "stack of layers" as used herein may be understood as two, three or more layers deposited on top of each other, wherein the two, three or more layers may be composed of the same material or of two, three or more different materials. For example, the stack of layers may include one or more conductive layers, e.g. a metal layer, and/or one or more isolating layers, e. g. a dielectric layer. In some embodiments, the stack of layers may include one or more transparent layers, e.g. a Si0₂ layer or an ITO layer. In some embodiments, at least one layer of the stack of layers may be a conductive transparent layer, e.g. an ITO layer. In some embodiments, one or more layers may be patterned. In some embodiments, one or more Si0₂ layers may be deposited on a first main surface of the substrate, followed by one or more ITO layers, optionally followed by one or more metal layers, e.g. copper layers. In some implementations, also the second main surface of the substrate may be coated, e.g. with the same stack of layers or with a different stack of layers in a deposition apparatus according to embodiments described herein.

[0014] According to some embodiments, which can be combined with other embodiments described herein, the deposition apparatus may be configured for a substrate length of 500 m or more, 1000 m or more, or several kilometres. The substrate width can be 300 mm or more, 500 mm or more, 1 m or more, particularly about 1.4 m. The substrate width can be 3 m or less, particularly 2 m or less. Typically, the substrate thickness can be 20 μιη or more and 1 mm or less, particularly from 50 μιη to 200 μιη. [0015] According to some embodiments, some chambers or all chambers of the deposition apparatus may be configured as vacuum chambers that can be - - evacuated. For instance, the deposition apparatus may include components and equipment allowing for the generation of or maintenance of a vacuum in at least a part of the processing system, such as in the spool chamber and in the deposition chamber(s). The deposition apparatus may include vacuum pumps, evacuation ducts, vacuum seals and the like for generating or maintaining a vacuum at least in parts of the deposition apparatus. For instance, each chamber may have individual corresponding vacuum pumps or pumping stations for evacuating the respective chamber. In some embodiments, two or more turbo-vacuum pumps may be connected to at least one vacuum chamber, particularly to each vacuum chamber of the deposition apparatus.

[0016] According to some embodiments, the vacuum chambers of the deposition apparatus being adapted for operating under vacuum conditions form a vacuum tight enclosure, i.e. can be evacuated to a vacuum with the pressure of 10 mbar or less, particularly 1 mbar or less, or even to a pressure between lxl 0 ⁴ and lxl 0 ² mbar or less during deposition. Different pressure ranges are to be considered specifically for PVD processes such as sputtering, which may be conducted in the 10^~3-mbar range, and CVD processes, which are typically conducted in the mbar-range. Further, the vacuum chambers can be evacuated to a background vacuum with a pressure of lxl 0 ⁶ mbar or less. Background pressure means the pressure which is reached by evacuation of a chamber without any inlet of any gases.

[0017] FIG. 1 illustratively shows a deposition apparatus 100 according to embodiments, for coating a flexible substrate 10 with a stack of thin layers. The deposition apparatus 100 includes a plurality of vacuum chambers that can be evacuated to a pressure below atmospheric pressure. The deposition apparatus 100 depicted in FIG. 1 includes a spool chamber 110 and a first deposition chamber 120 arranged downstream from the spool chamber 110. The spool chamber 110 may be considered as a vacuum chamber configured for housing a storage spool 112 with a flexible substrate 10 wound thereon, and for housing a wind-up spool 152 for winding the coated flexible substrate 10 thereon after the deposition in the first deposition chamber 120. - -

[0018] The deposition apparatus 100 may be configured such that the flexible substrate 10 can be guided from the first spool chamber 110 to the first deposition chamber 120 along a first substrate transportation path 101, and then back from the deposition chamber 120 to the spool chamber 110 via a second transportation path 102. The flexible substrate can be coated with the stack of layers in the first deposition chamber back surface 120. A roller assembly comprising a plurality of rolls or rollers 113 can be provided for transporting the substrate along the first substrate transportation path 101, wherein two or more rollers 113, five or more rollers, or ten or more rollers 113 of the roller assembly may be arranged between the storage spool and the wind-up spool.

[0019] According to embodiments herein, the substrate transportation path may be partially convex and partially concave. In other words, the substrate transportation path is partially curved to the right and partially curved to the left such that some guiding rollers contact a first main surface of the flexible substrate and some guiding roller contact a back surface of the flexible substrate opposite to the first main surface.

[0020] In embodiments such as depicted in FIG. 1, in the first transport path 101, the roller assembly is in contact with both sides, main surface and back surface, of the flexible substrate 10. Different thereto, the second transport path 102 provides a contact of the roller assembly only on the back surface of the flexible substrate 10. That is, the flexible substrate 10 can be guided from the storage spool 112 located in the first spool chamber 110 to the first deposition chamber 120 along a first substrate transportation path 101, and is in contact with rollers at both of its main surface and the back surface. After deposition in the deposition chamber 120, the coated flexible substrate is then guided back from the deposition chamber 120 via the second transport path 102 to the wind-up spool 152 in the spool chamber 110. During the guiding back, the flexible substrate 10 will be in contact with rollers only with its back surface, on which no coating was provided. That is, with such a configuration, a type of coating or layer which would be prone to damage due to contact with - - a roller directly after the deposition may be effectively protected due to the absence of any contact with a roller on the main surface.

[0021] The terms "upstream from" and "downstream from" as used herein may refer to the position of the respective chamber or of the respective component with respect to another chamber or component along the substrate transportation path. For example (not corresponding to FIG. 1, see FIG. 3), during operation, the substrate may be guided through a first deposition chamber 120 and subsequently guided through a further, second deposition chamber 140 along the substrate transportation path via a roller assembly. Accordingly, the second deposition chamber 140 is arranged downstream from the first deposition chamber 120, and the first deposition chamber 120 is arranged upstream from the second deposition chamber 140. When, during operation, the substrate is first guided by or transported past a first roller or a first component and subsequently guided by or transported past a second roller or a second component, the second roller or second component is arranged downstream from the first roller or first component.

[0022] The first spool chamber 110 is configured to accommodate a storage spool 112, wherein the storage spool 112 may be provided with the flexible substrate 10 wound thereon. During operation, the flexible substrate 10 can be unwound from the storage spool 112 and transported along the first substrate transportation path 101 from the spool chamber 110 toward the first deposition chamber 120. The term "storage spool" as used herein may be understood as a roll on which a flexible substrate to be coated is stored. Accordingly, the term "wind-up spool" as used herein may be understood as a roll adapted for receiving the coated flexible substrate. The term "storage spool" may also be referred to as a "supply roll" herein, and the term "wind-up spool" may also be referred to as a "take-up roll" herein. In embodiments such as described below, the function of the storage spool and the wind-up spool may be temporarily interchanged, though without departing from their dedicated names. - -

[0023] In embodiments depicted in FIG. 1, the configuration allows for a reversal of the transport direction of the flexible substrate and a subsequent second deposition process. After, for example, the entire substrate length initially provided on the storage spool 112 has been rolled off and was coated in the deposition chamber 120, the flexible substrate 10 is entirely wound on wind-up spool 152, with a deposited coating or stack on its main surface. When the transport direction is reversed, the flexible substrate 10 is then guided for a second deposition process through the deposition chamber 120. The former wind-up spool 152 becomes a supply spool, and the former storage spool 112 becomes the wind-up spool. For reasons of consistency, the wind-up spool 152 and the supply-spool 112 are however named identically throughout this disclosure, and their respective function, which may vary as just described, becomes apparent from the respective context.

[0024] The above described method of operating the deposition apparatus as shown in FIG. 1 in both transport directions of the flexible substrate has effects which may be useful depending on the particulars of the produced coated substrate. For example, when two coatings, or two stacks, with significantly different robustness with respect to contact to a roller shall be deposited on a main surface of the substrate, the following may be applied. For example, when the stack first to be deposited on the main surface is sensitive to a subsequent contact with a roller after the deposition, and when at the same time the second stack is inherently stable when in contact with a roller, it may be chosen to begin with the substrate being supplied from the storage spool 112. [0025] The entire substrate supply from storage spool 112 is then coated in the deposition chamber 120 and is wound on wind-up spool 152. Thereby, the coating or stack on the main surface of the flexible substrate 10 does not come into contact with any roller. After the complete substrate supply has been coated, the transport direction is reversed. Subsequently, the coated flexible substrate is again guided through the deposition chamber 120 and coated with the second coating or stack, which is deposited on top of the first coating or - - stack which was applied in the first (or previous) deposition step. As the second coating is stable against contact to a roller after the deposition, it is not critical that the coated flexible substrate 10 is in contact to at least one roller with its coated main surface. [0026] A similar process as just described may be applied when the first coating or stack to be deposited is stable against contact with a roller, but the second coating or stack is inherently prone to damage due to contact with a roller. In this case, it may be started with the substrate supply being provided on wind-up spool 152. After the first deposition step, during which the substrate is temporarily in contact with a roller with its coated main surface, the transport direction is reversed and the substrate is then guided from storage spool 112.

[0027] In some embodiments, which may be combined with other embodiments described herein, a storage spool drive (not shown) may be provided for rotating the storage spool 112 for unwinding the flexible substrate therefrom. In other words, the storage spool 112 may be an actively driven roller.

[0028] The first deposition chamber 120 may be arranged directly downstream from the spool chamber 110, as is schematically depicted in FIG. 1. Alternatively, one or more further vacuum chambers, e.g. a cleaning chamber, may be arranged between the first spool chamber 110 and the first deposition chamber 120. In the embodiment shown in FIG. 1, the flexible substrate exiting the first spool chamber 110 through a small passage such as a slit may directly enter the first deposition chamber 120. [0029] The spool chamber 110 may be configured as a load- lock chamber. In other words, the first spool chamber 110 may be flooded, e.g. for exchanging the storage spool in the spool chamber with a new storage spool, without impairing the vacuum in the remaining vacuum chambers. A passage or opening in the wall between the first spool chamber 110 and the vacuum chamber arranged downstream from the first spool chamber can be sealed. - -

Accordingly, other vacuum chambers of the deposition apparatus 100, and particularly the deposition chamber or chambers, can be maintained in an evacuated state during an exchange of a storage spool in the first spool chamber, e.g. when the flexible substrate has been unwound from the storage spool.

[0030] According to embodiments as shown in FIG. 1, the first deposition chamber 120 includes a flange 119. In FIG. 1, the flange is tightly closed with a lid. The flange 119 provides flexibility in a way that while the deposition apparatus of FIG. 1 has only one deposition chamber 120, a second deposition chamber 140 may be added to the deposition apparatus, such as described further below with respect to FIG. 3. Hence, the deposition apparatus 100 may be adapted in a modular way to account for varying production needs, for example.

[0031] According to embodiments such as shown in FIG. 2, the deposition apparatus 100 may comprise a connection chamber 130, which is provided and arranged between the spool chamber 110 and the first deposition chamber 120.

The connection chamber 130 may comprise at least one roller 113 which is part of the roller assembly and serves for guiding the flexible substrate 10. In FIG.

2, the roller 113 in the connection chamber supports the flexible substrate 10 from its back surface, as part of the second transport path 102.

[0032] In some embodiments, which may be combined with other embodiments described herein, the flexible substrate 10 may be guided through openings, e.g. slits, in the walls separating the vacuum chambers from each other, respectively. For example, a slit in the wall between two vacuum chambers may be adapted for guiding the substrate from one vacuum chamber to another vacuum chamber, respectively. In some embodiments, the opening may be provided with a sealing device in order to separate, at least substantially, the pressure conditions of the two vacuum chambers linked by the opening. For instance, if the chambers being linked by the opening provide different pressure conditions, the opening in the wall may be designed so as to maintain the respective pressure in the chambers. - -

[0033] According to embodiments described herein, at least one gap sluice or load- lock valve may be provided for separating two adjacent vacuum chambers from each other, e.g. for separating the first spool chamber from the vacuum chamber arranged downstream therefrom. The at least one gap sluice may be configured such that the flexible substrate can move therethrough and the gap sluice can be opened and closed for providing a vacuum seal. Thus, for instance, the spool chamber 110 can be vented while the first deposition chamber 120 can be maintained under technical vacuum.

[0034] For example, a sealing device 105 arranged between the spool chamber and the first deposition chamber 120 is schematically indicated in FIG. 1. However, it is to be understood that further sealing devices providing a corresponding functionality may be provided between other adjacent vacuum chambers, e.g. between a first deposition chamber 120 and a second deposition chamber . [0035] The sealing device 105 may include an inflatable seal configured to press the substrate against a flat sealing surface. Accordingly, the opening in the wall between the spool chamber 110 and the first deposition chamber 120 can be sealed, even when the flexible substrate may be present in the opening. Removal of the flexible substrate may not be necessary for closing or opening the sealing device.

[0036] Yet, also other means for selectively opening and closing a gap sluice can be utilized, wherein opening and closing, i.e. having an open substrate path and a vacuum seal, can be conducted while the substrate is inserted. The gap sluice for closing the vacuum seal while the substrate is inserted allows for particularly easy exchange of the substrate, as the substrate from the new roll can be attached to the substrate from the previous roll.

[0037] Although the sealing devices, slits, openings or gap sluices are described with respect to guiding the flexible substrate from the first spool chamber to the following vacuum chamber, the sealing devices, slits, openings - - or gap sluices as described herein may also be used between other chambers or parts of the deposition apparatus.

[0038] The first deposition chamber 120 may include a first coating drum 122 configured for guiding the flexible substrate 10 past a first plurality of deposition units 121. The first coating drum 122 may be rotatable around a rotation axis A. The coating drum may include a curved substrate support surface, e.g. an outer surface of the first coating drum 122, on which the flexible surface can be guided past the first plurality of deposition units 121. While guiding the flexible substrate past the first plurality of deposition units 121, the flexible substrate may be in direct contact with the substrate support surface of the first coating drum, which may be cooled. The temperature of the flexible substrate may be reduced during deposition, when the flexible substrate is in direct thermal contact with the first coating drum.

[0039] The flexible substrate 10 may be coated with one or more thin layers by the first plurality of deposition units 121. For example, the deposition units of the first plurality of deposition units 121 may be arranged in a circumferential direction around the first coating drum 122, as is schematically depicted in FIG. 1. The first deposition chamber 120 may include two or more deposition units arranged next to each other along the substrate transportation path. A first main surface of the flexible substrate may be coated, while a second main surface of the flexible substrate opposite to the first main surface, i.e. the rear surface of the flexible substrate, may be in contact with the curved substrate support surface of the first coating drum.

[0040] As the first coating drum 122 rotates, the flexible substrate is guided past the deposition units which face toward the curved substrate support surface of the first coating drum so that the first main surface of the flexible substrate can be coated while being moved past the deposition units at a predetermined speed.

[0041] In some embodiments, one or more rollers 113, e.g. guiding rollers, of the roller assembly may be arranged between the storage spool 112 and the - - first coating drum 122 and/or downstream from the first coating drum 122. For example, in the embodiment shown in FIG. 1, three guiding rollers 113 are provided between the storage spool 112 and the first coating drum 122, wherein at least one guiding roller 113 may be arranged in the spool chamber 110 and at least one guiding roller 113 may be arranged in the deposition chamber upstream from the first coating drum 122. In some embodiments, three, four, five or more, particularly eight or more guiding rollers 113 are provided between the storage spool 112 and the first coating drum 122. The guiding rollers may be active or passive rollers. [0042] An "active" roller or roll as used herein may be understood as a roller that is provided with a drive or a motor for actively moving or rotating the respective roller. For example, an active roller may be adjusted to provide a predetermined torque or a predetermined rotational speed. Typically, the storage spool 112 and the wind-up spool 152 may be provided as active rollers. In some embodiments, the coating drum 122 may be configured as an active roller. Further, active rollers can be configured as substrate tensioning rollers configured for tensioning the substrate with a predetermined tensioning force during operation. A "passive" roller as used herein may be understood as a roller or roll that is not provided with a drive for actively moving or rotating the passive roller. The passive roller may be rotated by the frictional force of the flexible substrate that may be in direct contact with an outer roller surface during operation.

[0043] In the present disclosure, a "roll" or "roller" may be understood as a device, which provides a surface, with which the flexible substrate or part of the flexible substrate may come in contact during transport of the flexible substrate along the substrate transportation path in the deposition apparatus. At least a part of the roller as referred to herein may include a circular-like shape for contacting the flexible substrate 10 before or after deposition. The substantially cylindrical shape may be formed about a straight longitudinal axis. According to some embodiments, a roller may be a guiding roller adapted to guide a substrate while the substrate is transported, e.g. during a deposition - - process or while the substrate is present in the deposition apparatus. The roller may be configured as a spreader roller, i.e. an active roller adapted for providing a defined tension for the flexible substrate, a processing roller, e.g. a coating drum, for supporting the flexible substrate while being coated, a deflecting roller for deflecting the substrate along the curved substrate transportation path, an adjusting roller, a storage spool, a wind-up spool etc.

[0044] According to some implementations, the rollers as described herein may be mounted to low friction roller bearings, particularly with a dual bearing roller architecture. Accordingly, roller parallelism of the transportation arrangement as described herein can be achieved and a transverse substrate "wandering" during substrate transport may be eliminated.

[0045] As shown in FIG. 3, in embodiments, a second deposition chamber 140 may be arranged downstream from the first deposition chamber 120. Accordingly, the flexible substrate 10 may enter the second deposition chamber 140, after the flexible substrate 10 has been guided by the first coating drum 122 past the first plurality of deposition units 121. In some embodiments, the second deposition chamber 140 may be arranged directly downstream from the first deposition chamber 120. In other embodiments (not shown), one or more further vacuum chambers, e.g. a connection chamber 130, may be arranged between the first deposition chamber 120 and the second deposition chamber 140.

[0046] The second deposition chamber 140 includes a second coating drum 142 configured for guiding the flexible substrate past a second plurality of deposition units 141. The flexible substrate 10 may be coated with one or more thin layers by the second plurality of deposition units 141 in the second deposition chamber 140. For example, the deposition units of the second plurality of deposition units 141 may be arranged in a circumferential direction around the second coating drum 142, as is schematically depicted in FIG. 3. The second deposition chamber 140 may include two or more deposition units arranged next to each other along the substrate transportation path. The flexible substrate may be coated, while the rear surface of the flexible substrate is in - - direct contact with a curved substrate support surface of the second coating drum 142.

[0047] As the second coating drum 142 rotates, the flexible substrate is guided past the deposition units of the second plurality of deposition units which face toward the curved substrate support surface of the second coating drum 142 so that the flexible substrate can be coated while being moved past the second plurality of deposition units at a predetermined speed.

[0048] During the deposition, the first deposition chamber 120 and/or the second deposition chamber 140 may be under medium vacuum or under high vacuum, e.g. at a pressure between lxlO ² mbar and lxl0^~4 mbar, e.g. when sputter sources are used. The pressure inside the deposition units may be higher than the pressure in a main volume of the deposition chambers, e.g. by an order of magnitude. For example, the pressure inside the sputter deposition units during sputter deposition may be about 5x10^~3 mbar. The pressure in the first spool chamber 110 and in the second spool chamber 150 may be higher than the pressure in the deposition chambers during deposition, e.g. by one or two orders of magnitude. For example, the background pressure in the first spool chamber and/or in the second spool chamber may be between 10 ¹ mbar and lO ³ mbar. One or more vacuum control units may be provided, e.g. in at least one vacuum chamber and/or in at least one deposition unit.

[0049] In some embodiments, the roller axes of the guiding rollers may have a length along the rotation axis of 1 m or more and 2 m or less, particularly about 1.5 m. The deposition apparatus may have more than more than 20 guiding rollers and less than 60 guiding rollers, for example about 30 guiding rollers which may be aligned with respect to the reference roller, respectively, in order to be essentially parallel with the reference roller and, thus, with each other.

[0050] While the foregoing is directed to embodiments, other and further embodiments may be devised without departing from the basic scope, and the scope is determined by the claims that follow.

Claims

1. A deposition apparatus (100) for coating a main surface of a flexible substrate (10), comprising: a spool chamber (110), configured for housing a storage spool (112) for providing the flexible substrate (10), and for housing a wind-up spool (152) for receiving the coated substrate; a first deposition chamber (120) arranged adjacent to the spool chamber (110) and comprising a first coating drum (122) configured for guiding the flexible substrate past a first plurality of deposition units (121); a roller assembly comprising a plurality of rollers (113) configured to transport the flexible substrate (10) along a first substrate transport path (101) from the storage spool (112) in the spool chamber (110) to the first deposition chamber (120), and subsequently along a second substrate transport path (102) from a deposition chamber to the wind-up spool (152) in the spool chamber, and wherein one of the first transport path (101) and the second transport path (102) provides a contact of the roller assembly to a main surface and to a back surface of the flexible substrate (10), and the other one of the first transport path (101) and the second transport path (102) provides a contact of the roller assembly only to the back surface of the flexible substrate (10).

2. The deposition apparatus (100) of claim 1, being configured such that the direction of movement of the flexible substrate (10) may be reversed, such that after a coating process, the functions of the wind-up spool (152) and the storage spool (112) are exchanged with each other for subsequently providing a further coating on the main surface of the flexible substrate (10).

3. The deposition apparatus (100) of claims 1 or 2, wherein the deposition chamber has a flange (119) on one of its sides which is opposite to the spool chamber (110), for mounting a further vacuum chamber.

4. The deposition apparatus (100) of any preceding claim, further comprising a second deposition chamber (140) mounted to or adjacent to the first deposition chamber (120).

5. The deposition apparatus (100) of any preceding claim, further comprising a connection chamber (130) arranged between the spool chamber (110) and the first deposition chamber (120).

6. The deposition apparatus (100) of claim 5, wherein the connection chamber (130) comprises at least one roller (113), being a part of the roller assembly, for guiding the flexible substrate (10).

7. The deposition apparatus (100) of any preceding claim, wherein the deposition chamber (120) comprises a coating drum (122) and a plurality of deposition units (121).

8. The deposition apparatus (100) of claim 7, wherein the deposition units (121) are provided substantially in the lower hemisphere of the deposition drum (122).

9. The deposition apparatus (100) of any preceding claim, further comprising a sealing device (105) between the spool chamber (110) and the first deposition chamber (120).

10. The deposition apparatus of claim 9, wherein the sealing device (105) is an inflatable seal.

11. A method (900) of coating a flexible substrate (10) with at least one layer, particularly with a deposition apparatus (100) of any of the preceding claims, wherein the flexible substrate is transported along a first transportation path (101) from a spool chamber (110) to the first deposition chamber (120), the method comprising: unwinding (910) the flexible substrate (10) from a storage spool (112) provided in the spool chamber (110); depositing (920) at least one first layer on a main surface of the flexible substrate (10), while the flexible substrate is guided by a first coating drum (122) provided in a first deposition chamber (120); and winding (930) the flexible substrate (10) on a wind-up spool (152) provided in the spool chamber (150), after a deposition, wherein the flexible substrate is guided along a first substrate transportation path (101) from the storage spool (112) in the spool chamber (110) to the deposition chamber (120), and subsequently along a second substrate transport path (102) from a first deposition chamber (120) or optionally from a subsequent second deposition chamber (140) to the wind-up spool (152) in the spool chamber (110), wherein one of the first transportation path (101) and the second transportation path (102) provides a contact of the roller assembly to a main surface and to a back surface of the flexible substrate (10), and the other one of the first transportation path (101) and the second transportation path (102) provides a contact of the roller assembly only to the back surface of the flexible substrate.

12. The method (900) of coating a flexible substrate (10) of claim 11, including reversing the direction of movement after at least a part of the length of the flexible substrate is deposited (930) with at least the first layer, and exchanging the functions of the wind-up spool (152) and the storage spool (112) with each other, for subsequently providing a further coating on the main surface of the flexible substrate (10).

13. The method (900) of claims 11 or 12, wherein, while at least a first layer is deposited on a main surface of the flexible substrate (10), the main surface does not have contact with a roller (113) before being wound up.

14. The method (900) of claim 13, wherein the flexible substrate (10) is wound up on the wind-up spool (152) in the spool chamber (110).