WO2021013326A1

WO2021013326A1 - Evaporation source, vacuum deposition system, valve assembly, and method therefor

Info

Publication number: WO2021013326A1
Application number: PCT/EP2019/069587
Authority: WO
Inventors: Michael Long; Matthias HEYMANNS
Original assignee: Applied Materials, Inc.
Priority date: 2019-07-19
Filing date: 2019-07-19
Publication date: 2021-01-28

Abstract

An evaporation source for depositing an evaporated material on a substrate is described. The evaporation source comprises an evaporation crucible, a vapor distribution assembly, and a valve assembly configured for closing a vapor passage between the evaporation crucible and the vapor distribution assembly, the valve assembly comprising a temperature control device configured for cooling a valve surface.

Description

EVAPORATION SOURCE, VACUUM DEPOSITION SYSTEM, VAEVE ASSEMBEY, AND METHOD THEREFOR

TECHNICAE FIEED

[0001 ] Embodiments of the present disclosure relate to deposition apparatuses for depositing one or more layers, particularly layers including organic materials therein, on a substrate. In particular, embodiments of the present disclosure relate to evaporation sources for depositing evaporated material on a substrate, particularly in vacuum deposition systems, and methods therefor, particularly for OLED manufacturing. Specifically, embodiments described herein relate to evaporation sources, vacuum deposition systems, valve assemblies, and methods of depositing an evaporated material on a substrate.

BACKGROUND

[0002] Evaporation sources are a tool for the production of organic light-emitting diodes (OLED) and other electronic or optic devices including a stack of deposited materials. OLEDs are a special type of light-emitting diode in which the emissive layer comprises a thin-film of certain organic compounds. Organic light emitting diodes (OLEDs) are used in the manufacture of television screens, computer monitors, mobile phones, other hand-held devices, etc., for displaying information. OLEDs can also be used for general space illumination. The range of colors, brightness, and viewing angles possible with OLED displays is greater than that of traditional LCD displays because OLED pixels directly emit light and do not involve a back light. Therefore, the energy consumption of OLED displays is considerably less than that of traditional LCD displays. Further, the fact that OLEDs can be manufactured onto flexible substrates results in further applications. Evaporation sources can also be used for the deposition of other material layers, e.g. metal layers, on substrates, such as on glass substrates or semiconductor wafers. [0003] Evaporation sources typically include an evaporation crucible that is configured to evaporate a source material by heating the source material to a temperature at or above the evaporation temperature of the source material. The evaporated material may be guided into a vapor distribution assembly that is configured for directing the evaporated material onto a substrate.

[0004] Under various circumstances, it may be necessary to stop the evaporation. In particular, it can be challenging to quickly or reliably start or stop the deposition process, e.g. for testing, calibration, maintenance, or substrate exchange. More specifically, it can be challenging to provide a gastight sealing between an evaporation source and a vapor distribution assembly, particularly without shutting down the evaporation crucible.

[0005] Accordingly, there is a continuing demand for providing improved evaporation sources, vacuum deposition systems, valve assemblies and methods therefor. Specifically, it would be desirable to increase the up-time of evaporation sources and vacuum deposition systems, and to provide an evaporation source that can quickly stop an evaporation process and stably continue with the evaporation process after a stop.

SUMMARY

[0006] In light of the above, an evaporation source, a vacuum deposition system, a valve assembly, and a method for depositing a material on a substrate according to the independent claims are provided. Further aspects, benefits, and features of the present disclosure are apparent from the claims, the description, and the accompanying drawings.

[0007] According to an aspect of the present disclosure, an evaporation source for depositing an evaporated material on a substrate is provided. The evaporation source includes an evaporation crucible, a vapor distribution assembly and a valve assembly configured for closing a vapor passage between the evaporation crucible and the vapor distribution assembly. The valve assembly includes a temperature control device configured for cooling a valve surface.

[0008] In particular, the valve assembly is configured to condense evaporated material in the vapor passage on the valve surface for closing the vapor passage.

[0009] The evaporation source of embodiments described herein may be switchable between a deposition state, in which the evaporated material is directed along the vapor passage into the vapor distribution assembly for being deposited on a substrate, and an idle state, in which the vapor passage is closed. In the idle state, the vapor passage can be clogged by evaporated material condensed on the valve surface such that no evaporated material can enter the distribution assembly. [0010] According to another aspect of the present disclosure, a vacuum deposition system is provided. The vacuum deposition system includes a vacuum deposition chamber, an evaporation source according to any of the embodiments described herein in the vacuum deposition chamber, and a substrate support configured for supporting a substrate during material deposition. [0011] According to another aspect of the present disclosure, a valve assembly is provided. The valve assembly is configured to close a vapor passage of an evaporation source by condensing evaporated material in the vapor passage.

[0012] In particular, the valve assembly includes a valve surface adjacent to the vapor passage, and a temperature control device configured to cool the valve surface, such that the evaporated material condenses thereon and closes the vapor passage.

[0013] According to yet another aspect of the present disclosure, a method of depositing an evaporated material on a substrate is provided. The method includes evaporating a material, guiding the evaporated material through the vapor passage into a vapor distribution assembly, and closing the vapor passage by condensing the evaporated material in the vapor passage.

[0014] 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 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

[0015] 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 cross-sectional side view of an evaporation source according to embodiments described herein; Figs. 2A-3B show schematic cross-sectional side views of valve assemblies according to embodiments described herein;

Figs. 4A-6B show detailed schematic cross-sectional side views of closures positioned in vapor passages of valve assemblies according to embodiments described herein; Fig. 7 shows a flow chart illustrating a method of depositing an evaporated material on a substrate according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0016] 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.

[0017] 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.

[0018] Before various embodiments of the present disclosure are described in more detail, some aspects with respect to some terms and expressions used herein are explained.

[0019] In the present disclosure, an“evaporation source” can be understood as a device or assembly configured for providing an evaporated material to be deposited on a substrate. In particular, an“evaporation source” may be a device or assembly having an evaporation crucible configured to evaporate the material to be deposited and a vapor distribution assembly configured for providing the evaporated material to the substrate. A vapor distribution assembly can be configured for directing the evaporated material toward the substrate, particularly for guiding the evaporated material in a deposition direction, exemplarily indicated in Fig. 1 by arrows, through a plurality of distribution outlets that can be directed toward a substrate. Accordingly, the evaporated material, for example an organic material, is guided within the vapor distribution assembly and exits the vapor distribution assembly through one or more distribution outlets.

[0020] In the present disclosure, an“evaporation crucible” can be understood as a device configured for evaporating a source material, particularly by heating the source material to a temperature at or above an evaporation temperature. In some embodiments, an evaporation crucible may include a material reservoir that can be heated to vaporize the material into a vapor by at least one of evaporation and sublimation of the material. In some embodiments, an evaporation crucible may include a heatable porous structure, e.g. a foam structure, configured for evaporating the material that comes into contact with the heatable porous structure. The evaporated material may propagate through the heatable porous structure toward the distribution assembly.

[0021] Typically, the evaporation crucible includes a heater to vaporize the material in the evaporation crucible to an evaporated material. For instance, initially the material to be evaporated can be in the form of a powder. In some embodiments, a material reservoir of the evaporation crucible can have an inner volume for receiving the material to be evaporated, e.g. an organic material. In some embodiments, the evaporation crucible may include a heating unit configured for heating the material provided in the inner volume of the evaporation crucible up to a temperature at which the material evaporates. For instance, the evaporation crucible may be an evaporation crucible for evaporating organic materials, e.g. organic materials having an evaporation temperature in a range between 200°C and 400°C.

[0022] In the present disclosure, a “vapor distribution assembly” can be understood as an assembly configured for directing evaporated material, particularly one or more plumes of evaporated material, toward the substrate. For example, the vapor distribution assembly may include a distribution pipe which can be an elongated tube. For instance, a distribution pipe as described herein may provide a line source with a plurality of distribution outlets, e.g. openings or nozzles, which are arranged in at least one line along the length of the distribution pipe.

[0023] In some embodiments, the vapor distribution assembly can be a linear distribution showerhead, for example, having a plurality of distribution outlets, e.g. openings or nozzles disposed therein. The linear distribution showerhead may extend in an essentially vertical direction, such that an essentially vertically oriented substrate can be coated by the evaporation source. A showerhead can have an enclosure, hollow space, or pipe, in which the evaporated material can be guided, for example from the evaporation crucible to the substrate. [0024] Embodiments described herein relate to an evaporation source including an evaporation crucible for providing evaporated material and a vapor distribution assembly for directing the evaporated material toward the substrate. A vapor passage extends between the evaporation crucible and the vapor distribution assembly for guiding the evaporated material from the evaporation crucible into the vapor distribution assembly to be deposited on the substrate. The vapor passage may be a vapor conduit or vapor channel extending from the evaporation crucible to the vapor distribution assembly. Accordingly, when the vapor passage is open, evaporated material can flow from the evaporation crucible into the vapor distribution assembly to be directed toward the substrate, such that the evaporation source is in a deposition state. When the vapor passage is closed, the vapor path between the evaporation crucible and the vapor distribution assembly is blocked, such that no evaporated material can flow from the evaporation crucible into the vapor distribution pipe. The evaporation source is then in an idle state, in which no deposition on the substrate takes place.

[0025] The evaporation sources described herein include a valve assembly configured to close and open the vapor passage between the evaporation crucible and the vapor distribution assembly. Accordingly, the evaporation source can switch between a deposition state in which the valve assembly opens the vapor passage and an idle state in which the valve assembly seals or blocks the vapor passage, e.g. for temporarily stopping the deposition, e.g. for calibration, maintenance, cleaning and/or substrate exchange.

[0026] In the present disclosure, the terms“axial” and“radial” can be understood with respect to a main flow direction of the vapor along a vapor passage, i.e. with respect to an axis (A) defined by the vapor passage. In particular, the axis may be directed centrally along the vapor passage. The term“axial” can be understood as parallel or along the axis (A). The term“radial” can be understood as radial with respect to the axis, i.e. perpendicular to the axis in a radial direction.

[0027] According to some embodiments described herein, the valve assembly may be arranged at the vapor passage. The valve assembly can be configured for an open state and a closed state. In the open state, the vapor passage is open, particularly allowing for the flow of evaporated material through the vapor passage. In the closed state, the vapor passage is closed or sealed. In particular, in the closed state, a flow of evaporated material through the vapor passage is stopped.

[0028] The valve assembly of evaporation sources described herein includes a temperature control device configured for cooling a valve surface of the valve assembly. In particular, the temperature control device may be configured for cooling the valve surface to a temperature at which evaporated material condenses on the valve surface during the operation of the evaporation source. Optionally, the temperature control device may be configured for cooling and heating the valve surface. The terms“cooling” or“heating” as used herein may refer to cooling or heating relative to an operating temperature of the evaporation source, more specifically relative to an operating temperature of the evaporation source at or in the valve assembly.

[0029] In exemplary embodiments, the temperature control device may be configured to regulate a temperature of the valve surface to at least a first temperature, at which evaporated material condenses on the valve surface of the valve assembly during the operation of the evaporation source. The condensed evaporated material may close the vapor passage. In some embodiments, the temperature control device may be further configured to regulate the temperature of the valve surface to at least a second temperature, at which the condensed evaporated material re-evaporates from the valve surface. The closed vapor passage can be re-opened again by re-evaporation.

[0030] In other words, the valve assembly of the evaporation source described herein is configured to close a vapor passage of an evaporation source by condensing evaporated material in the vapor passage, and to re-open the vapor passage by re-evaporating the condensed material. The valve assembly may include a valve surface that is coolable during the operation of the evaporation source to a first temperature at which evaporated material condenses at the valve surface for closing the vapor passage. The valve surface may optionally be (actively or passively) heatable during the operation of the evaporation source to a second temperature at which the condensed material re-evaporates from the valve surface for opening the vapor passage.

[0031] Fig. 1 shows a schematic cross-sectional side view of an evaporation source 100 for depositing an evaporated material 130 on a substrate according to embodiments described herein. The evaporation source 100 includes an evaporation crucible 110, a valve assembly 140, and a vapor distribution assembly 120. The evaporation crucible 110 can be configured to evaporate a material 115. The valve assembly 140 is positioned at a vapor passage 145 between the evaporation crucible 110 and the vapor distribution assembly 120. The valve assembly 140 is configured for closing the vapor passage 145. The valve assembly 140 includes a temperature control device 150 configured for cooling a valve surface 155. The vapor distribution assembly may include a plurality of vapor outlets or nozzles 125 for directing the evaporated material toward a substrate.

[0032] In some embodiments, the valve assembly 140 can be configured for condensing the evaporated material 130, for example an evaporated organic material, on the valve surface 155. In particular, the temperature control device 150 may cool down the valve surface 155 that is arranged adjacent to the vapor passage 145 to a temperature suitable for material condensation during the operation of the evaporation source. Condensing the evaporated material 130 may close the vapor passage 145. In particular, the vapor passage 145 can be closed by clogging the vapor passage 145 with condensed evaporated material.

[0033] For example, in a deposition state of the evaporation source, the valve surface may have a temperature of 250°C or more, for example between 300°C and 400°C, e.g. due to heat from the evaporated material passing past the valve surface (also referred to herein as“operation temperature” of the valve surface). The temperature control device may be configured to cool down the valve surface from the operation temperature to a temperature of, e.g., 20°C or more below the operation temperature (for example, to a temperature of 230°C or less, depending on the material properties of the evaporated material and on the pressure conditions inside the evaporation source) that is suitable for a material condensation on the valve surface during the operation of the evaporation source.

[0034] In some embodiments, the temperature control device 150 may further be configured for heating the valve surface 155. In such embodiments, the valve assembly 140 can be configured for quickly re-evaporating the condensed evaporated material, for example an organic material, from the valve surface 155. Re-evaporating the condensed material may re-open the vapor passage 145, particularly by unclogging the vapor passage 145.

[0035] In exemplary embodiments which can be combined with other embodiments described herein, the temperature control device is configured for regulating a temperature of the valve surface to a temperature at which the evaporated material condenses on the valve surface, i.e. a temperature below the (material- and pressure-dependent) evaporation temperature of the material. In an exemplary embodiment, the temperature control device is configured for reducing the temperature of the valve surface from an operation temperature (e.g. 250°C or more, or 300°C or more) to a second temperature which may be 20°C, 50°C or more below the operation temperature (e.g., to a temperature of 230° or less, or 200°C or less). Yet, it is to be noted that the temperature at which the evaporated material transitions from a vapor state to a fluid or solid state depends on the material as well as on the local pressure, and the above temperature values are to be understood as examples.

[0036] It is to be noted that, in the deposition state of the evaporation source, the temperature of the valve surface is typically at or above the evaporation temperature of the evaporated material, e.g. 250°C or more, because evaporated material passes past the valve surface and heats up the valve surface in the deposition state. The temperature control device is configured to switch from the deposition state to the idle state in which the vapor passage is closed by cooling down the valve surface from the operation temperature to a temperature below the operation temperature, e.g. a temperature more than 20°C or more than 50°C below the operation temperature, at which the evaporated material condenses on the valve surface. [0037] Additionally, the temperature control device may be configured for regulating the temperature of the valve surface to a temperature higher than the evaporation temperature, e.g. to a temperature corresponding to or higher than the operation temperature. For example, the temperature control device may be configured for regulating the temperature of the valve surface to a temperature higher than 250°C, more particularly higher than 300°C or even higher than 400°C. For example, instead of simply switching off the cooling of the temperature control device and waiting until the condensed material re-evaporates and re-opens the vapor passage, the temperature control device may be configured for an active heating of the valve surface. Re-evaporation of the condensed material can be accelerated, such that a quick closing and opening of the valve passage can be enabled.

[0038] Alternatively, the temperature control device can be configured purely as a cooling device, e.g. a Peltier cooling device and/or cooling channels for a cooling fluid. For closing the vapor passage, the cooling device may be activated for cooling down the valve surface to a temperature below the evaporation temperature of the evaporated material. For re-opening the vapor passage, the cooling device can simply be switched off, whereupon the condensed material re-evaporates due to heat from the environment inside the evaporation source.

[0039] As is schematically depicted in Fig. 1, the vapor passage 145 can be a slit opening between the evaporation crucible 110 and the vapor distribution assembly 120. For example, a maximum slit width of the slit opening may be 25 mm or less, particularly 10 mm or less, more particularly or 6 mm or less, or even 1 mm or less. A small maximum slit width is beneficial with respect to a quick sealing of the slit by condensation, whereas a large slit with is beneficial with respect a high flow conductance in an open state of the slit. A slit width between 2 mm and 10 mm, e.g. 6 mm, provides a reasonable compromise in the event that no displaceable closure is provided in the vapor passage.

[0040] In some embodiments, the vapor passage may include a wider opening, e.g. a round opening of a tube. A vapor passage with a wider opening may be beneficial for enabling a larger vapor flow into the vapor distribution assembly in the deposition state of the evaporation source. For switching from the deposition state to the idle state of the evaporation source, the vapor passage may first be reduced to a slit opening, e.g., by placing a closure in the vapor passage. After reducing the vapor passage to the slit opening, the vapor passage may be closed or clogged by condensing evaporated material on the valve surface of the valve assembly. In particular, a temperature control device may cool the valve surface to a temperature at which the evaporated material can condense at the valve surface and clog or seal the vapor passage. According to embodiments of the present disclosure, a temperature control device may be configured for cooling, particularly for cooling and heating a valve surface. The valve surface may include at least a part of a passage surface enclosing the vapor passage and/or at least a part of a closure surface of the closure.

[0041] If a valve assembly is switched from an open state to a closed state during the operation of the evaporation source, a pressure difference may build up between the evaporation crucible and the vapor distribution assembly, e.g. a pressure difference of the order of 100 Pa. Embodiments described herein can provide the advantage that for closing the vapor passage, a closure does not have to be pressed against a passage surface of a vapor passage. In particular, a closure does not have to be pressed against a passage surface and act against a force resulting from the pressure difference between the evaporation crucible and the vapor distribution assembly. Instead, a valve assembly according to embodiments described herein may be configured such that a vapor passage can be closed without pressing a closure against a passage surface of a vapor passage. In embodiments including a closure, the closure may be positioned, in particular in an axial direction, before closing or sealing the vapor passage by cooling the valve surface of the valve assembly to condense evaporated material on the valve surface. Without requiring high forces for closing the vapor passage, for example high axial forces, evaporation sources according to embodiments described herein can be provided with reduced size or cost, particularly with a valve assembly of reduced size or cost. Additionally, a deformation of a vapor passage or of a closure due to high forces may be avoided. Furthermore, closing a vapor passage using a temperature control device according to embodiments described herein may reliably provide a gastight sealing between an evaporation crucible and a vapor distribution assembly.

[0042] Figs. 2A-C show schematic cross-sectional side views of a valve assembly 200 according to embodiments described herein. The valve assembly 200 may include any of the features of the valve assembly 140 of Fig. 1, such that reference can be made to the above explanations, which are not repeated here.

[0043] The valve assembly 200 may be a part of any of the evaporation sources described herein. In particular, the valve assembly 200 may be arranged at a vapor passage between an evaporation crucible and a vapor distribution assembly for closing and/or opening the vapor passage. Alternatively or additionally, the valve assembly 200 may be placed at another position of the evaporation source.

[0044] The valve assembly 200 shown in Figs. 2A-C includes a temperature control device 225 arranged at a vapor passage 215, wherein the vapor passage 215 may extend along an axis (A). The valve assembly 200 of Figs. 2A-C can include a valve housing 205 with an inlet 210 extending, e.g., from an evaporation crucible, and the vapor passage 215 leading to, e.g., a vapor distribution assembly. The valve assembly 200 includes a closure 220.

[0045] In some embodiments, which can be combined with other embodiments described herein, the closure 220 can be configured to be switchable between a first position, as illustrated for example in Fig. 2A, and a second position, as exemplarily shown in Fig. 2B. In the second position, the closure 220 can be placed in the vapor passage 215. In the first position, the closure 220 may be positioned outside the vapor passage 215. If the closure 220 is placed in the first position, the valve assembly 200 is in an open state. In the open state, evaporated material can pass through the vapor passage 215, particularly from an evaporation crucible to a vapor distribution assembly, and further through distribution outlets of the vapor distribution assembly. Accordingly, when the closure is in the first position, the evaporation source may be in a deposition state in which a substrate is coated with evaporated material.

[0046] If the closure 220 is switched to the second position, the valve assembly 200 may be in a partially closed state. In the partially closed state, the vapor passage 215 can be partially occluded. In the partially closed state, some evaporated material may still pass through the vapor passage, for example through a slit opening 250 that may surround the closure. Fig. 2B exemplarily illustrates the valve assembly 200 in the partially closed state.

[0047] If the closure 220 is switched to the second position, a temperature control device 225 may cool down a valve surface 230 from an operation temperature to a lower temperature suitable for material condensation, such that the vapor passage 215 is clogged by condensed evaporated material 255. Accordingly, the valve assembly 200 can be switched to the closed state that may correspond to the idle state of the deposition source in which the deposition on a substrate is halted. In the closed state, the condensed evaporated material 255 may be condensed between the closure 220 and a passage surface 235 of the vapor passage 215, particularly filling a slit opening 250 between a closure surface of the closure 220 and the passage surface 235 of the vapor passage 215. In the closed state, the vapor passage 215 can be sealed. In particular, a flow of evaporated material through the vapor passage 215 can be stopped. Fig. 2C exemplarily illustrates the valve assembly 200 in the closed state.

[0048] An evaporation source can stop a flow of evaporated material through the vapor passage 215 by switching a valve assembly 200 from an open state first to a partially closed state and then to a closed state. For switching the valve assembly 200 from the open state to the partially closed state, a closure 220 can be switched from the first position to the second position. In the partially closed state, evaporated material may still pass through a partially occluded vapor passage 215, in particular through a slit opening 250. In the partially closed state, a temperature control device 225 can cool a valve surface 230 such that evaporated material condenses on the valve surface 230. Once a slit opening 250 between the closure 220 and the passage surface 235 of the vapor passage 215 is clogged with condensed evaporated material 255, the vapor passage 215 is closed and the valve assembly 200 is placed in the closed state.

[0049] In some embodiments, a closure can be arranged on a pivot arm. For example, Figs. 2A-C show a closure 220 arranged on pivot arm 240 pivotable around a pivot arm 245. In further embodiments, a closure can be arranged on a linear actuator.

[0050] Figs. 3A-C show schematic cross-sectional side views of a valve assembly 300 of an evaporation source according to embodiments described herein. The valve assembly 300 may include any of the features of the previously described valve assemblies, such that reference can be made to the above explanations, which are not repeated here. In particular, the valve assembly 300 may include a closure 220 that is switchable between a first position (Fig. 3A) in which a vapor passage 215 inside the evaporation source is open and a second position (Fig. 3B) in which the closure 220 is placed in the vapor passage 215, and the valve assembly is switched to a partially closed state. In the partially closed state, a temperature control device 225 of the valve assembly 300 may cool a valve surface 230 adjacent to the vapor passage such that condensed evaporated material 255 clogs the vapor passage 215 (Fig. 3C).

[0051] In Figs. 3A-C, the closure 220 is arranged on a linear actuator 340. The linear actuator 340 can move or switch the closure 220 between the first position, as shown in Fig. 3 A, and the second position, as shown in Fig. 3B. In some embodiments, the linear actuator 340 may include an actuator bellows 345, for example to shield the linear actuator 340, a shaft of the linear actuator 340 or a bearing of the linear actuator 340 against evaporated material. [0052] In some embodiments, which can be combined with other embodiments described herein, the vapor passage 215 is enclosed by a passage surface 235, and the valve surface 230 includes at least a part of the passage surface 235. The temperature control device 225 can be configured for cooling, particularly for cooling and heating, the valve surface 230. In particular, the vapor passage 215 may be fully enclosed, for example fully enclosed along a circumference of the vapor passage 215, by the valve surface 230. For example, Figs. 2A-3C each show a valve assembly 200, 300 with a coolable valve surface including at least a part of a passage surface 235. [0053] According to some embodiments, the closure 220 can be positioned in the vapor passage 215 at an axial closure position, and the coolable valve surface encloses the vapor passage 215 at the axial closure position. Accordingly, when the closure is positioned at the axial closure position, the vapor passage 215 can be closed by condensing evaporated material between the coolable valve surface and the closure.

[0054] Figs. 4A-6B show detailed schematic cross-sectional side views of closures positioned in vapor passages of valve assemblies according to embodiments described herein. It should be understood that the details of the valve assemblies shown in Figs. 4A-6B may be combined with other embodiments described herein. In particular, the closures may be arranged on a pivot arm or on a linear actuator as described herein. The closures may be switched between a first position and a second position.

[0055] According to embodiments described herein, a closure can include a closure surface, and the valve surface can form at least a part of the closure surface. A temperature control device can be configured for cooling, or for cooling and (actively) heating, the valve surface forming at least a part of the closure surface. In an exemplary embodiment, the temperature control device may cool the valve surface using a cooling fluid such as clean dry air, in particular by guiding the cooling fluid through a channel next to the valve surface. [0056] As illustrated exemplarily in Figs. 4A-B, a closure 420 of a valve assembly

400 may include at least a part of the valve surface 430 that is coolable via the temperature control device 425. The temperature control device 425 may be configured for cooling, or for cooling and heating, the valve surface 430 that includes at least a part of a closure surface 435 of the closure 420. The valve surface 430 may be cooled by the temperature control device 425 for condensing evaporated material on the valve surface 430, such that condensed evaporated material 455 clogs a slit opening 250 between the closure surface and a passage surface of the vapor passage 215. [0057] In further embodiments, a temperature control device may be configured for cooling, or for cooling and heating, a valve surface including at least a part of a passage surface of a vapor passage and at least a part of a closure surface of a closure. In particular, both the closure and a wall of the vapor passage may be at least partially coolable. In such embodiments, a speed of switching of a valve assembly might be advantageously increased.

[0058] According to embodiments described herein, a temperature control device may include a channel for regulating a temperature of a valve surface, e.g. a cooling channel for a cooling fluid. In particular, the temperature control device may be configured for pumping a fluid through the channel to cool, or to cool and heat, the valve surface. For example, the fluid may be clean dry air. In exemplary embodiments, the channel may be positioned next to the valve surface. The valve surface may include one or both of a closure surface and a passage surface. For example, Figs. 5A-5B illustrate a valve assembly 500 including a vapor passage 215 and a closure 220 positioned in the vapor passage 215. A temperature control device 225 includes a channel 560, wherein the temperature control device 225 can be configured for cooling a valve surface 230 such that condensed evaporated material 255 can clog the vapor passage 215.

[0059] In some embodiments, the temperature control device may include a heating device, for example an electric heating device, configured for heating the valve surface. The temperature control device can be configured to heat the valve surface such that condensed evaporated material may be re-evaporated from the valve surface for quickly re-opening the vapor passage. Alternatively or additionally, a clogged vapor passage may be re-opened by pivoting or moving the closure from the second position to the first position. [0060] According to some embodiments of the present disclosure, a valve surface may be oriented at least substantially parallel to an axis (A) of the vapor passage, as illustrated exemplarily in Figs. 2A-5B.

[0061] In further embodiments, which can be combined with other embodiments described herein, the valve surface may be oriented in a direction other than parallel to the axis (A) of a vapor passage. The exemplary embodiment of a valve assembly 600 illustrated in Figs. 6A-6B, which may include any of the features of the previously described valve assemblies, includes a valve surface 630 oriented substantially perpendicular to the axis (A) of vapor passage 615. A closure 620 can be positioned in a second position at a passage surface 635 such that the vapor passage 615 is reduced to a slit opening 650. A temperature control device 625 may cool the valve surface 630 to clog the vapor passage 615 with condensed evaporated material 655 (Fig. 6B).

[0062] According to another aspect, a vacuum deposition system including an evaporation source according to any of the embodiments described herein is provided. In particular, the vacuum deposition system can include more than one evaporation source, particularly two evaporation sources or three evaporation sources. An evaporation source may be used to evaporate more than one material, particularly more than one organic material, or an organic material and one or more dopants, or to deposit more than one material on a substrate. The evaporation source is positioned in the vacuum deposition chamber. A substrate support configured for supporting a substrate during material deposition may be arranged in the vacuum deposition chamber.

[0063] In some embodiments, a first drive for moving the evaporation source in the vacuum deposition chamber along a source track, e.g. past the substrate, may be provided. The source track may be a linear track, such that the evaporation source can be linearly moved past the substrate. Alternatively or additionally, a second drive for changing an evaporation direction of the evaporation source, e.g. by rotating the vapor distribution assembly of the evaporation source, may be provided. For example, the vapor distribution assembly may be rotated between a first substrate support configured to support a first substrate on a first side of the evaporation source and a second substrate support configured to support a second substrate on a second side of the evaporation source.

[0064] According to one aspect described herein, a valve assembly configured to close a vapor passage of an evaporation source is provided. The valve assembly is configured to close the vapor passage by condensing evaporated material in the vapor passage. The valve assembly may include any of the features of the valve assemblies described herein, such that reference can be made to the above explanations, which are not repeated here. In particular, the valve assembly may include a valve surface arranged adjacent to a vapor passage, and a temperature control device, particularly a cooling device, configured for cooling the valve surface for condensing the evaporation material thereon. Accordingly, the vapor passage can be sealed with condensed evaporated material for switching from a deposition state to an idle state of the evaporation source.

[0065] According to one aspect described herein, a method of depositing an evaporated material on a substrate is described. Fig. 7 shows a flow chart of a method 700 according to embodiments described herein. The method 700 includes evaporating (see block 710) a material. In particular, the material can be evaporated in an evaporation crucible according to embodiments described herein. The method 700 further includes guiding (see block 720) the evaporated material through a vapor passage into a vapor distribution assembly. In block 720, the evaporation source is in a deposition state, in which the evaporated material is directed toward a substrate for coating the substrate. Additionally, the method 700 includes closing (see block 730) the vapor passage by condensing the evaporated material in the vapor passage. The evaporated material may be condensed in the vapor passage by cooling a valve surface at the vapor passage.

[0066] In particular, closing the vapor passage may include reducing a temperature of a valve surface of a valve assembly adjacent to the vapor passage to a temperature below an evaporation temperature of the evaporated material such that the evaporated material condenses on the valve surface. In particular, the temperature of the valve surface is reduced by 20°C or more. The temperature of the valve surface may be set to a temperature lower than the condensation temperature of the organic material, such that the organic material condenses on the valve surface. [0067] In particular, the valve surface may form at least a part of at least one of a passage surface of the vapor passage and a closure surface of a closure placed in the vapor passage. Condensed evaporated material may clog the vapor passage and close the vapor passage. After closing (see block 730) the vapor passage, the evaporation source is in an idle state, in which the deposition process is halted or interrupted.

[0068] According to some embodiments, closing (see block 730) may include placing a closure in the vapor passage before condensing the evaporated material. For example, the closure may be placed in the vapor passage by switching the closure from a first position, wherein the closure is positioned outside the vapor passage, to a second position, wherein the closure is positioned in the vapor passage.

Placing the closure in the vapor passage may reduce the vapor passage to an opening slit, e.g. an annular slit.

[0069] The method 700 may further include opening (see block 740) the vapor passage by re-evaporating condensed evaporated material in the vapor passage. In particular, opening (see block 740) may include heating the valve surface for re evaporating the condensed evaporated material. In some embodiments, opening (see block 740) may include switching a closure from a second position in the vapor passage to a first position outside the vapor passage, in particular after re evaporating the condensed evaporated material, to fully open the vapor passage. [0070] In some embodiments of the method 700, the evaporated material is an organic evaporated material.

[0071 ] In view of the embodiments described herein, it is to be understood that an improved evaporation source, an improved vacuum deposition system, an improved valve assembly, and an improved method for depositing an evaporated material on a substrate are provided, particularly for OLED manufacturing. In particular, a valve assembly positioned in the evaporative path of an evaporation source, e.g. between an evaporation crucible and a distribution assembly, can provide for the possibility to stop a flow of evaporated material from an evaporation crucible to a distribution assembly. In particular, embodiments of the present disclosure may provide a gastight sealing. This can particularly be beneficial, for instance for adjusting a preselected deposition rate in an initial test deposition process or during a calibration of more than one evaporation source according to embodiments described herein. Furthermore, a gastight sealing may be provided without requiring actuators to press a closure against a passage surface of a vapor passage with high forces.

[0072] Embodiments of the evaporation source as described herein are configured to reduce the cost of ownership, since wastage of material, particularly expensive organic material, can be reduced, e.g. during calibration of an evaporation source or during maintenance. In contrast, conventional deposition systems may not be capable of quickly and reliably shutting off a material flow from a crucible to a distribution assembly and/or of quickly and reliably establishing a material flow from a crucible to a distribution assembly when starting a deposition process. In particular, in conventional systems, stopping evaporated organic material from passing to the outlets of a distribution assembly may be time-consuming and may lead to extended idle times of the evaporation source.

[0073] The term“substrate” as used herein may particularly embrace substantially inflexible substrates, e.g., a wafer, slices of transparent crystal such as sapphire or the like, or a glass plate. However, the present disclosure is not limited thereto, and the term“substrate” may also embrace flexible substrates such as a web or a foil. The term“substantially inflexible” is understood to distinguish over“flexible”. According to embodiments described herein, the substrate may be made of any material suitable for material deposition. For instance, the substrate may be made of a material selected from the group consisting of glass (for instance soda-lime glass, borosilicate glass etc.), metal, semiconductor, polymer, ceramic, compound materials, carbon fiber materials or any other material or combination of materials which can be coated by a deposition process.

[0074] The term“substrate” as used herein encompasses large area substrates. For instance, a“large area substrate” can have a main surface with an area of 0.5 m² or larger, particularly of 1 m² or larger. In some embodiments, a large area substrate can be GEN 4.5, which corresponds to about 0.67 m² of substrate (0.73m x 0.92m), GEN 5, which corresponds to about 1.4 m² of substrate (El m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m² of substrate (E95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7 m² of substrate (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m² of substrate (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can similarly be implemented.

[0075] In the present disclosure, a “vacuum deposition chamber” is to be understood as a chamber configured for vacuum deposition. The term“vacuum”, as used herein, can be understood in the sense of a technical vacuum having a vacuum pressure of less than, for example, 10 mbar. Typically, the pressure in a vacuum chamber as described herein may be between 10 ⁵ mbar and about 10 ⁸ mbar, more typically between 10 ⁵ mbar and 10 ⁷ mbar, and even more typically between about 10 ⁶ mbar and about 10 ⁷ mbar. According to some embodiments, the pressure in the vacuum chamber may be considered to be either the partial pressure of the evaporated material within the vacuum chamber or the total pressure (which may approximately be the same when only the evaporated material is present as a component to be deposited in the vacuum chamber). In some embodiments, the total pressure in the vacuum chamber may range from about 10 ⁴ mbar to about 10 ⁷ mbar.

[0076] A“vapor distribution assembly” as described herein may be configured to provide a line source extending essentially vertically. In the present disclosure, the term “essentially vertically” is understood particularly when referring to the substrate orientation, to allow for a deviation from the vertical direction of 10° or below. This deviation can be provided because a substrate support with some deviation from the vertical orientation might result in a more stable substrate position. Yet, the substrate orientation during deposition of the organic material is considered essentially vertical. The surface of the substrates can be coated by a line source extending in one direction corresponding to one substrate dimension and a translational movement along the other direction corresponding to the other substrate dimension.

[0077] 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.

[0078] 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 for depositing an evaporated material on a substrate, comprising:

an evaporation crucible;

a vapor distribution assembly; and

a valve assembly configured for closing a vapor passage between the evaporation crucible and the vapor distribution assembly, the valve assembly comprising a temperature control device configured for cooling a valve surface.

2. The evaporation source according to claim 1, wherein the valve assembly is configured for condensing the evaporated material on the valve surface for closing the vapor passage.

3. The evaporation source according to any of claims 1 to 2, wherein the temperature control device is further configured for heating the valve surface for re-evaporating a condensed evaporated material from the valve surface.

4. The evaporation source according to any of claims 1 to 3, further comprising a closure that is switchable between a first position and a second position, wherein in the second position the closure is placed in the vapor passage.

5. The evaporation source according to any of claims 1 to 4, wherein the closure is arranged on a pivot arm or on a linear actuator.

6. The evaporation source according to any of claims 1 to 5, wherein the valve surface comprises at least a part of a passage surface enclosing the vapor passage.

7. The evaporation source according to any of claims 4 to 6, wherein the valve surface comprises at least a part of a closure surface of the closure.

8. The evaporation source according to any of claims 4 to 7, wherein, in the second position, the closure is positioned in the vapor passage at an axial closure position; and wherein the valve surface encloses the vapor passage at the axial closure position.

9. The evaporation source according to any of claims 1 to 8, wherein the temperature control device comprises a cooling channel for a cooling fluid.

10. A vacuum deposition system, comprising:

a vacuum deposition chamber;

an evaporation source according to any of claims 1 to 9 in the vacuum deposition chamber; and

a substrate support configured for supporting a substrate during material deposition.

11. A valve assembly configured to close a vapor passage of an evaporation source by condensing evaporated material in the vapor passage.

12. The valve assembly of claim 11, comprising:

a valve surface adjacent to the vapor passage; and

a temperature control device configured for cooling the valve surface for condensing the evaporated material thereon.

13. A method of depositing an evaporated material on a substrate, comprising: evaporating a material;

guiding the evaporated material through a vapor passage into a vapor distribution assembly; and

closing the vapor passage by condensing the evaporated material in the vapor passage.

14. The method according to claim 13, wherein closing the vapor passage comprises reducing a temperature of a valve surface adjacent to the vapor passage below an evaporation temperature of the material, particularly wherein the temperature of the valve surface is reduced by 20°C or more.

15. The method according to claim 13 or 14, wherein closing the vapor passage comprises placing a closure in the vapor passage before condensing the evaporated material.

16. The method according to any of claims 13 to 15, further comprising:

opening the vapor passage by re-evaporating condensed evaporated material in the vapor passage.

17. The method according to any of claims 13 to 16, wherein the evaporated material is an organic material.