WO2021190758A1

WO2021190758A1 - Evaporation source, deposition apparatus having an evaporation source, and methods therefor

Info

Publication number: WO2021190758A1
Application number: PCT/EP2020/058601
Authority: WO
Inventors: Frank Schnappenberger
Original assignee: Applied Materials, Inc.
Priority date: 2020-03-26
Filing date: 2020-03-26
Publication date: 2021-09-30
Also published as: EP4127260A1; TW202140818A; CN115279935A

Abstract

In the present disclosure, an evaporation source (100) for depositing a material on a substrate (S) in a processing chamber (510) is provided. The evaporation source (100) includes a wall (110) separating an inner region (101) and an outer region (102), an evaporator tube (120) extending from the wall (110) into the inner region (101), the evaporator tube (120) having a plurality of openings (122), an inner tube (160) extending through the wall (110) into the evaporator tube (120), the inner tube surrounding a heating element (140), and a sealable housing (130) extending from the wall (110) into the outer region (102), wherein the sealable housing (130) and the inner tube (160) form a maintenance chamber (150) which is isolated from the inner region (101). Further aspects include a deposition apparatus (500) having said evaporation source (100), a method for replacing a heating element (140) in said evaporation source (100), a method for filling said evaporation source (100), and a method for deactivating said evaporation source (100).

Description

EVAPORATION SOURCE, DEPOSITION APPARATUS HAVING AN EVAPORATION SOURCE, AND METHODS THEREFOR

TECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to evaporation sources, particularly evaporation sources for metal or metal alloys, and deposition apparatuses for depositing one or more layers on a substrate, particularly a flexible substrate. In particular, embodiments of the present disclosure relate to apparatuses for coating a substrate with one or more layers, e.g. for thin-film solar cell production, flexible display production or thin-film battery production. More particularly, embodiments of the present disclosure relate to apparatuses and methods for coating a flexible substrate in a roll-to-roll (R2R) process. Specifically, embodiments of the present disclosure relate to a deposition apparatus having an evaporation source which is easy to maintain and operate. Further, embodiments of the present disclosure relate to methods of operating a deposition apparatus having an evaporation source, particularly for maintaining the evaporation source and operating the evaporation source in a failure state.

BACKGROUND

[0002] Depositing thin layers on a flexible substrate is a production process for many applications. The flexible substrates are coated in one or more chambers of a flexible substrate coating apparatus. The flexible substrates, such as foils made of plastics or pre-coated papers, are guided on rolls or drums and pass in this way the source of deposition material. Possible applications of the coated substrate range from providing coated foils for the packaging industry to depositing thin films for flexible electronics and advanced technology applications, such as smartphones, flat screen TVs and solar panels.

[0003] The operational uptime of deposition apparatus having evaporation sources, particularly flexible substrate coating apparatus, are aimed to be maximized. However, downtime can occur due to the need to refill or maintain evaporation sources, or in situations where a failure state occurs and an evaporation source must be deactivated or repaired. Accordingly, there is a demand for improved evaporation sources and operations in which uptime of a deposition apparatus can be maximized.

[0004] One particular challenge to be faced when performing maintenance on evaporation sources is the environment of the processing chamber. In many applications, the processing chamber may be a vacuum chamber, or may contain an atmosphere having a processing gas. One aim while refilling, maintaining or repairing an evaporation source is to do so without disrupting the environment within the processing chamber. Another challenge to be faced is the interaction of the evaporation source with other evaporation sources in the same processing chamber. If uptime is to be maximized, any influencing of the deposition of a nearby evaporation source is aimed to be avoided. A yet further challenge concerns the reliability of the evaporation source, particularly the reliability of the heating element provided in the evaporation source. The electrical connections of the heating element may be damaged by deposition contamination, by operating in a processing gas, or by operating in an otherwise unsuitable environment.

[0005] In view of the above, improvements in evaporation sources are sought in order to improve refilling, maintenance, repair and failure state handling, so as to maximize uptime of a deposition apparatus having said evaporation source.

SUMMARY

[0006] In light of the above, an evaporation source, a deposition system, and methods for operating the evaporation source are provided.

[0007] According to an aspect of the present disclosure, an evaporation source for depositing a material on a substrate in a processing chamber is provided. The evaporation source includes a wall separating an inner region from an outer region, wherein the inner region is inside the processing chamber and the outer region is outside the processing chamber, an evaporator tube extending from the wall into the inner region, the evaporator tube having a plurality of openings, an inner tube extending through the wall into the evaporator tube, the inner tube surrounding a heating element, and a sealable housing extending from the wall into the outer region, wherein the sealable housing and the inner tube form a maintenance chamber which is isolated from the inner region.

[0008] According to a further aspect of the present disclosure, a deposition apparatus for depositing evaporated material onto a substrate is provided. The deposition apparatus includes a processing chamber enclosing a processing environment, and at least one evaporation source according to aspects of the present disclosure mounted to the processing chamber.

[0009] According to a yet further aspect of the present disclosure, a method for replacing a heating element in an evaporator source according to aspects of the present disclosure is provided. The method includes venting the maintenance chamber, opening the sealable housing, replacing the heating element, closing the sealable housing and evacuating the maintenance chamber.

[0010] According to a yet further aspect of the present disclosure, a method for filling an evaporator source according to aspects of the present disclosure is provided. The method includes venting the maintenance chamber, opening the sealable housing and the filling port, filling the evaporator tube with material through the filling port, closing the filling port and the sealable housing, and evacuating the maintenance chamber.

[0011] According to a yet further aspect of the present disclosure, a method for deactivating an evaporator source according to aspects of the present disclosure is provided. The method includes moving the evaporator cover from the first position to the second position, purging the evaporator cover with a protective gas, and deactivating the evaporator source. [0012] The aspects of the present disclosure provide an evaporator source having improved ease of maintenance and improved ease of refilling. Further aspects of the present disclosure provide an evaporator source which may be maintained, refilled and deactivated without affecting the processing environment or the deposition of nearby sources in the processing chamber. The evaporator source of the present disclosure also exhibits improved reliability, particularly of the heating element, as well as improved ease of replacement of the heating element in order to maximized uptime. 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 top view of an evaporation source according to embodiments described herein;

FIG. 2 shows cross-sectional side view through section A-A of an evaporation source according to embodiments described herein; FIG. 3 shows a cross-sectional end view through section B-B of an evaporation source according to embodiments described herein;

FIG. 4 shows a schematic end-view of an evaporation source according to embodiments described herein;

FIG. 5 shows schematic top view of an evaporation source having an evaporator cover according to embodiments described herein; and FIG. 6 shows a schematic side view of a deposition apparatus embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS [0014] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0015] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can apply to a corresponding part or aspect in another embodiment as well.

[0016] Aspects of the present disclosure relate to evaporation sources for depositing evaporated material on substrates. Referring firstly to FIG. 1, which shows a schematic top view of an evaporation source according to aspects of the present disclosure, the evaporation source 100 may be mounted to a wall of a processing chamber 510, and includes an evaporator tube 120 which extends into the processing chamber 510. Evaporator tube 120 further includes a plurality of openings 122 which may be arranged along the length of the evaporator tube 120. Material inside the evaporator tube 120 is heated such that the material is evaporated and expelled out of openings 122, for example, towards a substrate to be coated. Evaporator tube 120 may extend to at least the width of a substrate being coated, such that the substrate may be coated across its entire width by a single evaporator source 100. [0017] The evaporation source 100 shown exemplarily in FIG. 1 is oriented such that the evaporator tube extends horizontally into the processing chamber 510. The openings 122 are accordingly oriented in a linear arrangement such that a linear pattern of evaporated material is expelled from the evaporation source 100. However, a horizontal orientation is not the only possible orientation for an evaporation source, and the present disclosure is not limited thereto. For example, the evaporator tube 120 may extend in a vertical direction, e.g. extending downwards from a roof portion of the processing chamber 510. Further, the arrangement of openings 122 is not limited to a linear arrangement. For example, the openings 122 may be provided in an arrangement around the circumference of evaporator tube 120, or may be provided in an end portion of evaporator tube 120 in a shower head arrangement.

[0018] The evaporation source 100 is configured for depositing evaporated material on a substrate in a processing chamber 510. The processing chamber 510 may include a processing chamber which houses an entire deposition system, or may be a smaller sub-chamber which may house a portion of a deposition system. For example, the processing chamber 510 may further include valves or locks designed for moving substrates into or out of the processing chamber to be deposited. The evaporation source 100 is exemplarily shown to be mounted to a side wall of processing chamber 510, however the present disclosure is not limited thereto. For example, the evaporation source 100 may be mounted to a roof portion of the processing chamber 510, or to a floor portion of the processing chamber 510. Generally, the evaporation source 100 is mounted to the processing chamber 510 in such a way as to provide access to a rear portion of the evaporation source 100, while the evaporator tube 120 extends into the processing chamber 510.

[0019] Processing chamber 510 is provided to enclose a processing environment in which deposition of a substrate occurs. The processing environment may include a processing gas, which may be provided as a reactant in the deposition process, or may be provided as a non-reactant in the deposition process. The processing gas may be provided at the same pressure as an ambient pressure outside the processing chamber, or may be provided at a pressure which is different to an ambient pressure outside the processing chamber. In some processes, the processing environment may be a complete or partial vacuum.

[0020] Reference will now be made to FIG. 3, which shows a cross-sectional end view of the evaporation source 100 taken through the section B-B indicated on FIG. 1. The cross-sectional view of FIG. 3 is taken through the evaporator tube 120 of the evaporation source 100. Evaporator tube 120 provides a lower portion which is filled with the material 200 to be evaporated and deposited on the substrate. Further provided within the evaporator tube 120 is an inner tube 160, which separates a region of the evaporator tube 120 from the region in which material evaporation occurs. A heating element 140 is provided inside the inner tube 160. Operation of the heating element 140 increases the temperature of the inside region of the evaporator tube 120, which in turn causes the material 200 to be heated. Material 200 then changes phase into vapor 201, which is then ejected out of openings 122 to produce a vapor stream 202. Vapor stream 202 may be directed towards a substrate in order to deposit material from the vapor stream 202 onto the surface of the substrate. The vapor stream 202 deposited on the substrate then cools and solidifies, forming a coating of the material on the surface of the substrate.

[0021] Evaporator tube 120 and inner tube 160 are exemplarily shown in FIG. 3 as having a circular cross-section. However, the present disclosure is not limited thereto, and either one of evaporator tube 120 and inner tube 160 may have a different cross section, for example, a triangular cross-section or a square cross- section.

[0022] The material 200 to be evaporated and deposited on the substrate may include any material typically used in a typical evaporation source. A non- exhaustive list of typical materials which may be used may include aluminium, cadmium, cobalt, copper, gallium, germanium, gold, indium, lithium, magnesium, nickel, platinum, silicon, silver, sodium, tin, tungsten, zinc or zirconium, and alloys thereof. A preferred application for the evaporation source 100 of the present disclosure is for depositing lithium and lithium alloys, however the present disclosure is not limited thereto.

[0023] In typical designs for evaporation sources, even in the case where the heating element is provided inside an inner tube as in the evaporation source 100 of the present disclosure, challenges are faced with respect to reliability of the heating element. In typical designs, portions of the heating element may be subjected to deposition of evaporated material, or may be subjected to processing gases in the processing environment. In particular, the reliability of connectors where power and control wires may be attached to the heating element can be reduced if evaporated material is allowed to deposit thereon. Further, the lifetime of the carbon material which is typically used for the heating elements can be reduced if the heating elements are operated in processing environments, and may also be reduced when operated in ambient air.

[0024] Further challenges arise with respect to maintenance and filling of a typical evaporation source, due to the processing environment being present inside the processing chamber. In order to refill the evaporation source, access to the inner region of the evaporator tube must be provided so that material can be refilled. However, in certain deposition processes, the processing environment may be at a higher or lower pressure than the ambient pressure, and providing access to the evaporator tube to refill material causes the processing environment to escape from the processing chamber. Further, some deposition processes use a reactant gas as a processing gas, which may be unsafe if present during refilling.

[0025] Reference will now be made to FIG. 2, which shows a cross-sectional side view of the evaporation source 100 taken through the section A- A indicated on FIG. 1. According an aspect of the present disclosure, an evaporation source 100 for depositing a material on a substrate in a processing chamber 510 is provided. The evaporation source 100 includes a wall 110 separating an inner region 101 and an outer region 102, an evaporator tube 120 extending from the wall 110 into the inner region 101, the evaporation tube 120 having a plurality of openings 122, an inner tube 160 extending through the wall 110 into the evaporator tube 120, the inner tube 160 surrounding a heating element 140, and a sealable housing 130 extending from the wall 110 into the outer region 102, wherein the sealable housing 130 and the inner tube 160 form a maintenance chamber 150 which is isolated from the inner region 101.

[0026] Wall 110 is provided to delimit two regions, wherein an inner region 101 is the region on an inner side of wall 110 and an outer region 102 is the region on an outer side of wall 110. Typically, the evaporation source 100 is mounted to a wall of a processing chamber 510, such that the inner region 101 may correspond to a region inside the processing chamber 510, and the outer region 102 may correspond to a region outside the processing chamber 510. Particularly, the inner region 101 may be a region in which a processing environment is present, for example, a processing environment including a processing gas, while the outer region 102 may be a region which is isolated from the processing environment, for example, an ambient environment separate from the processing environment.

[0027] Evaporation source 100 may further include a mounting flange which provides a mounting surface which interfaces with a corresponding mounting surface of a wall of the processing chamber 510. The mounting flange may further include a sealing means, such that a mounting hole in a wall of the processing chamber 510 is covered and sealed by the mounting flange. As exemplarily shown in FIG. 2, wall 110 is provided in a position approximately corresponding to a wall of the processing chamber 510, such that wall 110 is also provided as a mounting flange. However, the present disclosure is not limited thereto, and the wall 110 may be provided at a position offset from the wall of the processing chamber 510, and the mounting flange may be a separate element from wall 110. For example, a mounting flange may be provided on a portion of the evaporator tube 120, or on the sealable housing 130.

[0028] Evaporator tube 120 is arranged to extend from the wall 110 into the inner region 101. In other words, the evaporator tube 120 extends from the wall 110 into the processing chamber 510. Evaporator tube 120 may include a length of tube or pipe having a cross-section such that an evaporation region is provided within the evaporator tube 120. A first end of evaporator tube 120 is attached to wall 110 such that wall 110 closes the first end of evaporator tube 120. For example, evaporator tube 120 may be bonded or welded to wall 110. A second end of evaporator tube 120 is closed, for example, with an end plate 121. End plate 121 is shown as a flat plate bonded or welded to the second end of evaporator tube 120. However, the end plate 121 could instead include a dome shape, a cup shape or a box shape, and may be attached to second end of evaporator tube 120 in ways other than welding, for example, using a threaded connection.

[0029] In a bottom portion of the inner region of evaporator tube 120, material 200 is provided. For example, a pool of molten material 200 is provided in the bottom of evaporator tube 120. A plurality of openings 122 are provided in an upper surface of evaporator tube 120 so that material 200, which is heated to generate vapor 201, is expelled as a vapor stream 202 to be coated on a substrate.

[0030] Evaporation source 100 is provided with an inner tube 160 extending through the wall 110 into the evaporator tube 120. In other words, an opening in wall 110 is provided, through which inner tube 160 passes, such that inner tube 160 extends into the inner region 101, while also allowing an inner region of inner tube 160 to be in fluid communication with outer region 102. A first end of inner tube 160 is open to the outer region 102, while a second end of inner tube 160 is closed to the inner region 101. As exemplarily shown, inner tube 160 extends into the inner region 101 and into evaporator tube 120 up to the end of evaporator tube 120, i.e. end plate 121, such that the end of evaporator tube 120 closes the second end of inner tube 160. However, the present disclosure is not limited thereto, and the second end of inner tube 160 may not extend to the end of evaporator tube 120, and may instead be closed with a separate end plate. Inner tube 160 is configured to be in fluid communication with the outer region 102, but in fluid isolation from inner region 101 and the inner region of evaporator tube 120.

[0031] Inner tube 160 is provided for housing a heating element 140. Heating element 140 is provided for heating material 200 such that material 200 evaporates into vapor 201. Heating element 140 may be any heating element which provides sufficient heat to evaporate material 200. Particularly, heating element 140 may be a carbon heating element.

[0032] By providing heating element 140 inside inner tube 160, heating element 140 is protected from material being deposited thereon, while also allowing the heat generated by heating element 140 to heat inner tube 160, and consequently to heat evaporator tube 120 and material 200. As discussed above, inner tube 160 is arranged to be in fluid isolation with inner region 101, in other words, the inner tube 160 is in fluid isolation with the processing environment, and any processing gases present therein. It follows that heating element 140 is protected from being subjected to processing gases, which prevents corrosion and improves the lifetime of the heating element 140. Further, inner tube 160 is open to the outer region 102, which allows for the connectors 141 and wiring 142, which provide power and control signals to heating element 140, to also be protected from material deposition and processing gases. The evaporation source 100 of the present disclosure therefore improves the reliability of the heating element by offering protection to the heating element from material deposition and processing gases.

[0033] Evaporation source 100 further includes a sealable housing 130 extending from wall 110 into the outer region 102. Sealable housing 130 and inner tube 160 form a maintenance chamber 150 which is isolated from the inner region 101. Sealable housing 130 may include a plurality of walls forming a chamber, such that the open end of inner tube 160 is in fluid communication with said chamber. For example, sealable housing 130 may include a plurality of walls protruding from wall 110 which surround the open end of inner tube 160, and a further wall closing the plurality of walls such that the volume enclosed therein is sealed from the environment surrounding the volume.

[0034] The volume formed by sealable housing 130 and inner tube 160 forms a maintenance chamber 150 which is isolated from the inner region 101. Maintenance chamber 150 may enclose an environment which is different from the processing environment inside processing chamber 510, and also different to the ambient environment. The preferred embodiment of the present disclosure provides a maintenance chamber 150 which encloses a vacuum. Heating element 140, as well as connectors 141 and wiring 142 connected thereto, being provided within maintenance chamber 150, would then be provided in a vacuum environment. When positioned to operate in a vacuum, heating element 140, particularly a carbon heating element, has improved lifetime due to the absence of a gas or air which may cause corrosion of the heating element 140. It follows that the reliability of an evaporation source 100 according to the present disclosure would be improved, and that uptime of the evaporation source 100 may be maximized.

[0035] According to an embodiment, which may be combined with other embodiments described herein, sealable housing 130 may further include an evacuation port 132 configured for evacuating the maintenance chamber 150. Evacuation port 132 may be provided such that a vacuum pump may be attached, so that a vacuum environment inside the maintenance chamber 150 can be maintained. Evacuation port 132 may be a two-way port through which the maintenance chamber 150 is evacuated and vented. Alternatively, sealable housing 130 may further include a separate venting port. By providing an evacuation port 132 and optional venting port, the maintenance chamber 150 can be evacuated to generate a vacuum environment in which the heating element 140 may be operated, and the maintenance chamber 150 may be vented to generate an environment similar to the ambient environment in which the sealable housing 130 can be opened, allowing access to the maintenance chamber 150 in order to carry out maintenance tasks.

[0036] When referring to the term “sealable housing”, the housing is thought of as being an enclosure surrounding a volume which may be sealed and unsealed. A “sealable housing” may include at least one opening, wherein the opening may be sealed with another element which may be removed and mounted as required. In the context of the present disclosure, a “sealable housing” provides access, e.g. for maintenance, to the volume being enclosed by the “sealable housing”, while also allowing the volume being enclosed to be resealed when access is no longer required.

[0037] According to an embodiment, which may be combined with other embodiments described herein, the sealable housing 130 may include an openable door 131. As exemplarily shown in FIG. 2, the openable door 131 is provided as a wall of sealable housing 130, however openable door 131 may be provided to sealably cover an opening provided in a wall of sealable housing 130. Openable door 131 may be provided with a fixing means which allows openable door 131 to be mounted to and removed from sealable housing 130, for example, a plurality of threaded bolts or a clamping means. The present disclosure is not limited to a door, and openable door 131 may alternatively be any means for providing access to the maintenance chamber 150, for example, a threaded cap, a threaded plug, etc. Openable door 131 is provided to allow for access to maintenance chamber 150 so that maintenance tasks can be carried out therein. Openable door 131 may be restricted to being openable only when the environment inside maintenance chamber 150 has previously been vented.

[0038] Reference will now be made to FIG. 4, which shows an end view of an exemplary evaporation source 100 according to embodiments described herein. FIG. 4 shows the sealable housing with the openable door 131 removed so as to provide access to maintenance chamber 150. The open end of inner tube 160 can be seen, with heating element 140 provided therein. In order for openable door 131 to provide a sealable access to maintenance chamber 150, while also allowing maintenance chamber 150 to contain a vacuum environment, sealable housing 130 may further include a sealing means 133, for example, a groove with an O-ring which forms a seal with openable door 131.

[0039] According to an embodiment, which may be combined with other embodiments described herein, wall 110 may further include thermal isolation features 115 to thermally isolate the evaporator tube 120 from the wall 110. Evaporator tube 120 is heated to a high temperature so that material 200 is evaporated. Thermal isolation features 115 may be provided in order to provide a favorable temperature gradient from the evaporator tube 120 to wall 110, such that wall 110 and other components attached thereto are subjected to reduced thermal effects such as thermal expansion and contraction. By minimizing thermal effects on the wall 110 and other components, the various seals and closures provided between components, for example between evaporation source 100 and processing chamber 510, can be prevented from being thermally compromised.

[0040] As shown in FIGS. 2 and 4, thermal isolation features 115 may include a plurality of concentric protrusions which surround the portion in which evaporator tube 120 is attached to wall 110. Thermal isolation features 115 may be provided on wall 110 on at least one of a surface facing the inner region 101 and a surface facing the outer region 102. Exemplarily shown are concentric protrusions provided outside the evaporator tube 120, inside the evaporator tube 120, and on both sides of wall 110. However, any number of features may be provided. Further, the present disclosure is not limited thereto, and the thermal isolation features 115 may instead include concentric grooves, alternating concentric grooves and protrusions, or any other feature which allows for controlling a temperature gradient.

[0041] According to an embodiment, which may be combined with other embodiments described herein, wall 110 may further include a filling port 170 connecting the evaporator tube 120 to the maintenance chamber 150. The filling port 170 may be configured to be sealable. Filling port 170 can be seen in FIGS. 2 and 4, and allows for an inner region of the evaporator tube 120 to be accessed from the maintenance chamber 150.

[0042] Upon gaining access to maintenance chamber 150, the filling port 170 may be opened, providing access to the inner region of evaporator tube 120 in order to allow for material 200 to be replenished. Filling port 170 thereby allows, via openings 122 in evaporator tube 120, for fluid communication between the inner region 101 and the outer region 102. Filling port 170 may include a sealing element allowing for opening and re-sealing filling port 170. For example, a threaded plug may be provided to seal filling port 170. Alternatively, a port cover with a high- temperature sealing material may be provided to seal filling port 170. However, the present disclosure is not limited thereto, and any suitable high-temperature sealing means may be used. [0043] Depending on the deposition process being carried out, the filling port 170 may be removed and the material 200 refilled while deposition is still being carried out by other evaporation sources. For example, for deposition processes in which the processing environment is at the same pressure as an ambient environment, the filling port 170 may be opened to allow for filling with minimal loss of processing gas. Further, for deposition processes in which the processing environment is at a higher pressure than the ambient environment, a loss of some processing gas while refilling is performed may be allowed to occur without the processing environment being adversely affected by ambient air. In deposition processes such as these, deposition from other evaporation sources may continue while the material of one evaporation source is being replenished, which leads to improved uptime.

[0044] However for deposition processes in which the processing environment is at a considerably higher pressure or a considerably lower pressure than the ambient environment, it may not be possible to open filling port 170 to replenish material 200 without affecting the processing environment, for example, without preventing a loss of processing gas or a compromise of the processing gas in the processing environment. According to embodiments, which may be combined with other embodiments described herein, in order to isolate evaporation source 100 from the processing environment, evaporation source 100 may further include an evaporator cover 300 which is movable from a first position in which the evaporation source 100 is not isolated from the processing environment of the processing chamber 510 to a second position in which the evaporation source 100 is isolated from the processing environment of the processing chamber 510.

[0045] Evaporator cover 300 is exemplarily shown in FIG. 5. Evaporator cover 300 is shown as a cylindrical cover which is moveable along an axis. For example, evaporator cover 300 may be a top-hat shape, however the present disclosure is not limited thereto.

[0046] Evaporator cover 300 is shown in a first position, in which the evaporation source 100 is not isolated from the processing environment, and the evaporation source 100 is free to be used for depositing evaporated material. Evaporator cover 300 may then be moved along an axis into a second position, such that evaporator cover 300 covers evaporation source 100. In this second position, evaporation source 100 is isolated from the processing environment. Evaporator cover 300 may be provided with a supporting rail, upon which evaporator cover 300 may slide along an axis in order to move from a first position to a second position. Such a supporting rail may be mounted to the processing chamber, or to evaporation source 100.

[0047] By isolating evaporation source 100 from the processing environment, the filling port 170 of evaporation source 100 may be opened so that material 200 may be replenished, without allowing the processing gas in the processing environment to be compromised or lost.

[0048] Evaporator cover 300 exhibits further advantageous effects, which lead to further improvements in uptime and ease of maintenance. For example, in the case where one of a number of evaporation sources 100 enters a failure mode in which the evaporation source 100 is not functioning correctly, the malfunctioning evaporation source 100 can be isolated from the deposition process by moving evaporator cover 300 from the first position to the second position, allowing the deposition process to continue. Evaporator cover 300 also allows for evaporation source 100 to be safely deactivated without affecting nearby evaporation sources.

[0049] According to an embodiment, which may be combined with other embodiments described herein, evaporator cover 300 may include a purge port 340 configured for purging the evaporator cover 300 or evacuating the evaporator cover 300. Purge port 340 may be attached to a gas source. For example, a processing gas source which is the same as the processing gas in the processing chamber 510, or a purge gas which is different to the processing gas in the processing chamber 510. Alternatively, purge port 340 may be attached to a vacuum pump so that the interior of evaporator cover 300 may be evacuated. [0050] Particularly, purge port 340 may be configured for providing a non reactive purge gas into evaporator cover 300 to replace a reactive processing gas. In the case where an evaporation source 100 is deactivated or malfunctioning, but still contains an amount of material therein, it would be advantageous to replace a reactive processing gas with a non-reactive purge gas to prevent further reaction of material 200. Evaporator cover 300 allows for the replacement of a reactive processing gas with a non-reactive purge gas for a deactivated or malfunctioning evaporation source 100, while also allowing the processing environment in the processing chamber 510 to be maintained. This allows for the deposition process to continue to be carried out using other evaporation sources, while the deactivated or malfunctioning evaporation source is provided with a safe, non-reactive environment, further improving uptime.

[0051] According to an embodiment, which may be combined with other embodiments described herein, evaporator cover 300 may further include a first sealing surface 320 configured to interface with a second sealing surface 330. Particularly, the second sealing surface 330 may be a surface of the processing chamber 510. Alternatively, the second sealing surface 330 may be a surface of the evaporation source 100. First and second sealing surfaces 320, 330 are configured to interface with each other and form a seal when the evaporator cover 300 is in the second position, wherein the evaporation source 100 is isolated from the processing environment. First and second sealing surfaces 320, 330 may include an O-ring seal or a gasket seal, for example, which allows for an airtight seal between the first and second sealing surfaces 320, 330 to form an airtight seal.

[0052] In the case where the second sealing surface 330 is a surface of the processing chamber 510, the evaporator cover 300 provides an airtight isolation of the region in which the evaporation source 100 is positioned and the region of the processing environment. In this state, the evaporation source 100 may be demounted and completely removed from the processing chamber 510 while maintaining the processing environment within the processing chamber 510. This allows for a complete in-situ replacement of a defective evaporation source 100 while a deposition process is still ongoing.

[0053] Referring now to FIG. 6, according to a further aspect of the present disclosure, a deposition apparatus 500 for depositing evaporated material on a substrate S is provided. The deposition apparatus 500 includes a processing chamber 510 enclosing a processing environment and at least one evaporation source according to embodiments of the present disclosure mounted to the processing chamber 510.

[0054] According to embodiments described herein, deposition apparatus 500 may be configured for processing flexible substrates S, wherein the deposition apparatus 500 includes a reel-to-reel substrate transport. The reel-to-reel substrate transport includes a feed reel 520 and a take-up reel 530. Flexible substrate S is transported from the feed reel 520 to the take-up reel 530 past at least one evaporation source 100a, 100b, 100c. In the example shown in FIG. 6, the deposition apparatus 500 includes three evaporation sources 100a, 100b, 100c, however any number of evaporation sources 100 may be provided.

[0055] The deposition apparatus shown in FIG. 6 is configured for processing flexible substrates, however the present disclosure is not limited thereto. The deposition apparatus 500 of the present disclosure may be alternatively configured for processing other substrates such as rigid substrates or wafers, wherein the substrates are stationary within the processing chamber 510, or are transported past evaporation sources 100.

[0056] According to a further aspect of the present disclosure, a method for replacing a heating element 140 in an evaporation source 100 according to embodiments of the present disclosure is provided. The method includes venting the maintenance chamber 150, opening the sealable housing 130, replacing the heating element 140, closing the sealable housing 130, and evacuating the maintenance chamber 150. Despite the improvements to reliability of the heating element 140 afforded by the evaporation source 100 of the present disclosure, the lifetime of heating element 140 is finite. However, the evaporation source 100 of the present disclosure allows for ease of replacement of the heating element in the event of a heating element 140 failing. Due to the maintenance chamber 150 being isolated from the processing environment inside the processing chamber, the method for replacing a heating element 140 may be carried out without stopping a deposition process, i.e. by allowing deposition from other evaporation sources 100 to continue while the heating element 140 is replaced.

[0057] According to a further aspect of the present disclosure, a method for filling an evaporation source 100 according to embodiments of the present disclosure is provided. The method includes venting the maintenance chamber 150, opening the sealable housing 130 and the filling port 170, filling the evaporator tube 120 with material through the filling port 170, closing the filling port 170 and the sealable housing 130, and evacuating the maintenance chamber 150. As described above, for deposition processes in which the processing environment is at a similar pressure as an ambient pressure, or for deposition process in which the processing environment is at a higher pressure than the ambient pressure, the filling port 170 may be opened to replenish material 200 without compromising the processing environment contained in the processing chamber 510.

[0058] In the case of deposition processes where the processing environment is at a lower pressure than the ambient pressure, or at a much higher pressure than the ambient pressure, or where the processing environment is a vacuum, the above method can be improved by operating the evaporator cover 300. According to an embodiment, which may be combined with other embodiments described herein, the method for filling an evaporation source 100 may further include, before opening the filling port 170, moving the evaporator cover 300 from the first position to the second position, and after closing the filling port 170, moving the evaporator cover from the second position to the first position. By operating the evaporator cover 300 prior to opening the filling port 170, the region around the evaporation source 100 is isolated from the processing environment, allowing for the filling port 170 to be opened without compromising the processing gas within the processing environment. [0059] The method for filling an evaporation source 100 may be further improved by, after moving the evaporator cover 300 from the first position to the second position, purging the evaporator cover 300 with a protective gas. The protective gas may be different to the processing gas, particularly the protective gas may be a non-reactive gas which is different to a reactive processing gas. After the filling port 170 is closed again, the method may further include purging the evaporator cover 300 with a processing gas, particularly the same processing gas as in the processing chamber 510. Such an improved method allows for the material 200 to be replenished safely in an environment in which the material 200 will not react with a processing gas.

[0060] According to a further aspect of the present disclosure, a method for deactivating an evaporation source 100 according to embodiments of the present disclosure is provided. The method includes moving the evaporator cover 300 from the first position to the second position, purging the evaporator cover 300 with a protective gas, and deactivating the evaporation source 100. Such a method may be used in a situation in which a specific evaporation source 100, which may be one of a plurality of evaporation sources 100 in a processing chamber 510, is malfunctioning or defective. Particularly, the evaporation source 100 to be deactivated may contain an amount of material 200 which has not yet been evaporated. The evaporator cover 300 allows for the specific evaporation source 100 to be isolated from the processing environment, and thus prevented from affecting the processing environment or the deposition of other evaporation sources in the processing chamber 510. By purging the evaporator cover 300 with a protective gas, the amount of material 200 remaining in evaporation source 100 is prevented from reacting further, allowing the evaporation source 100 to be maintained safely.

[0061] 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. [0062] In particular, this written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any devices or systems and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if the claims have structural elements that do not differ from the literal language of the claims, or if the claims include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. An evaporation source (100) for depositing a material on a substrate (S) in a processing chamber (510), comprising: a wall (110) separating an inner region (101) and an outer region (102); an evaporator tube (120) extending from the wall (110) into the inner region (101), the evaporator tube (120) having a plurality of openings (122); an inner tube (160) extending through the wall (110) into the evaporator tube (120), the inner tube (160) surrounding a heating element (140); and a sealable housing (130) extending from the wall (110) into the outer region (102), wherein the sealable housing (130) and the inner tube (160) form a maintenance chamber (150) which is isolated from the inner region (101).

2. The evaporation source (100) according to claim 1, wherein the sealable housing (130) comprises at least one evacuation port (132) configured for evacuating the maintenance chamber (150). 3. The evaporation source (100) according to any one of claims 1 or 2, wherein the sealable housing (130) includes an openable door (131).

4. The evaporation source (100) according to claim 3, wherein the wall (110) further comprises a filling port (170) connecting the evaporator tube (120) to the maintenance chamber (150), wherein the filling port (170) is configured to be sealable.

5. The evaporation source (100) according to any one of claims 1 to 4, further comprising an evaporator cover (300) which is movable from a first position in which the evaporation source (100) is not isolated from a processing environment of the processing chamber (510) to a second position in which the evaporation source (100) is isolated from the processing environment of the processing chamber (510).

6. The evaporation source (100) according to claim 5, wherein the evaporator cover (300) comprises a purge port (340) configured for purging the evaporator cover (300) or evacuating the evaporator cover (300). 7. The evaporation source (100) according to one of claims 5 or 6, wherein the evaporator cover (300) comprises a first sealing surface (320) configured to interface with a second sealing surface (330), particularly wherein the second sealing surface (330) is a surface of the processing chamber (510). 8. The evaporation source (100) according to any one of claims 1 to 7, wherein the wall (110) further comprises thermal isolation features (115) to thermally isolate the evaporator tube (120) from the wall (110).

9. The evaporation source (100) according to claim 8, wherein the thermal isolation features (115) comprise a plurality of concentric grooves or protrusions provided on at least one of a surface facing the inner region (101) and a surface facing the outer region (102), wherein the plurality of concentric grooves or protrusions surround the portion where the evaporator tube (120) joins the wall (110).

10. A deposition apparatus (500) for depositing evaporated material onto a substrate (S), comprising: a processing chamber (510) enclosing a processing environment; and at least one evaporation source (100, lOOa-c) according to any of claims 1 to 9 mounted to the processing chamber (510).

11. The deposition apparatus (500) according to claim 10, wherein the substrate (S) is a flexible substrate, and the deposition apparatus comprises a reel-to-reel substrate transport.

12 Method for replacing a heating element (140) in an evaporator source (100) according to any one of claims 1 to 9, the method comprising: venting the maintenance chamber (150); opening the sealable housing (130); replacing the heating element (140); closing the sealable housing (130); and evacuating the maintenance chamber (150).

13. Method for filling an evaporator source (100) according to any one of claims 5 to 7, the method comprising: venting the maintenance chamber (150); opening the sealable housing (130) and the filling port (170); filling the evaporator tube (120) with material through the filling port

(170); closing the filling port (170) and the sealable housing (130); and evacuating the maintenance chamber (150). 14. The method according to claim 13, further comprising: before opening the filling port (170), moving the evaporator cover (300) from the first position to the second position; and after closing the filling port (170), moving the evaporator cover (300) from the second position to the first position.

15. Method for deactivating an evaporator source (100) in a processing chamber (510) according to any one of claims 5 to 7, the method comprising: moving the evaporator cover (300) from the first position to the second position; purging the evaporator cover (300) with a protective gas; and deactivating the evaporator source (100).