WO2021013328A1

WO2021013328A1 - Evaporation source for depositing an evaporated material on a substrate, vacuum deposition system, and method therefor

Info

Publication number: WO2021013328A1
Application number: PCT/EP2019/069591
Authority: WO
Inventors: Matthias HEYMANNS; Michael Long
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 closure that can be placed in the vapor passage and has a variable radial dimension.

Description

EVAPORATION SOURCE FOR DEPOSITING AN EVAPORATED MATERIAL ON A SUBSTRATE, VACUUM DEPOSITION SYSTEM, AND

METHOD THEREFOR

TECHNICAL FIELD [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, 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] Continuously providing a suitable deposition rate with an evaporation source is challenging. For example, pressure changes inside the evaporation source may lead to a varying deposition rate that may negatively affect the deposition quality. Further, it is challenging to quickly start or stop the deposition process, e.g. for testing, calibration, maintenance, or substrate exchange, and to quickly continue with the deposition process after a stop. For example, the evaporation source may need a considerable time for stabilizing, which may reduce the up-time of the deposition system. [0005] Accordingly, there is a continuing demand for providing improved evaporation sources, vacuum deposition systems 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.

SUMMARY

[0006] In light of the above, an evaporation source, a vacuum deposition system 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 closure that can be placed in the vapor passage and has a variable radial dimension.

[0008] According to another 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 first vapor passage between the evaporation crucible and the vapor distribution assembly. The valve assembly includes a closure that is switchable between a first closure position, in which the first vapor passage is open, and a second closure position, in which the closure is placed in the first vapor passage for closing the first vapor passage and a second vapor passage is open.

[0009] In particular, the closure can be switched between the first closure position in which the evaporated material can propagate along the first vapor passage into the vapor distribution assembly, and a second closure position in which the evaporated material can propagate along a second vapor passage, particularly into a vapor receiving assembly. In some embodiments, the second vapor passage is closed or closable when the closure is in the first closure position. Alternatively or additionally, the first vapor passage is closed or closable when the closure is in the second closure position. Hence, the evaporation source of embodiments described herein is switchable between a deposition state (first closure position) in which the evaporated material is directed along a first vapor passage into the vapor distribution assembly for being deposited on a substrate, and an idle state (second closure position), in which the evaporated material is directed along a second vapor passage into a vapor receiving assembly, which may be a material collection manifold. In the idle state, the first vapor passage can be closed such that no evaporated material can enter the distribution assembly.

[0010] According to yet 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 a further 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 a first vapor passage into a vapor distribution assembly, and closing the first vapor passage and guiding the evaporated material through a second vapor passage into a vapor receiving assembly.

[0012] In some embodiments, closing the vapor passage includes changing a radial dimension of a closure that is placed in the vapor passage.

[0013] 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

[0014] 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-8C show schematic cross-sectional side views of valve assemblies of evaporation sources according to embodiments described herein;

Fig. 9 shows a schematic cross-sectional side view of an evaporation source according to embodiments described herein; Figs. 10A-B show schematic cross-sectional side views of a valve assembly of an evaporation source according to embodiments described herein;

Fig. 11 shows a schematic cross-sectional side view of a valve assembly of an evaporation source according to embodiments described herein;

Figs. 12A-13B show schematic cross-sectional side views of a valve assembly of an evaporation source according to embodiments described herein; and

Fig. 14 shows a flow chart illustrating a method of depositing an evaporated material on a substrate according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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 gas by at least one of evaporation and sublimation of the material. 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, the reservoir 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.

[0020] 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.

[0021] 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.

[0022] 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 (also referred to herein as a“first” 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. [0023] 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.

[0024] 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 (R).

[0025] 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.

[0026] 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 closure 150 that can be placed in the vapor passage 145, wherein the closure 150 has a variable radial dimension.

[0027] As is schematically depicted in Fig. 1, the closure dimension can be set to a large radial dimension in which an outer radial edge of the closure is radially pressed onto and/or in radial contact with a valve surface for closing the vapor passage. Further, the closure dimension can be set to a small radial dimension in which a slit, which may surround the closure, is open, such that evaporated material can stream through the slit. An actuator may be provided in some embodiments for changing the radial dimension of the closure 150. A valve assembly with a closure configured to radially close a vapor passage is beneficial as compared to an axially closing valve, because radial sealing forces or respective counter forces act on the closure itself, such that a strain on a bearing of the closure or on an actuator of the valve assembly can be reduced. Furthermore, a vapor passage configured to be radially closed can be provided more easily with a rigidity sufficient to withstand sealing forces without a deformation of the vapor passage. Further, a small radial movement or variation of the closure may already be sufficient for closing the vapor passage, such that the evaporation source can quickly and reliably be switched between a deposition state and an idle state in which the vapor passage is sealed or blocked by the closure.

[0028] According to embodiments described herein, the radial dimension of the closure is variable. For example, a diameter of the closure can be varied or adjusted, e.g. by expanding the closure in the radial direction (R), such that the closure can be brought into contact with an inner surface of the vapor passage. Particularly, an outer radial edge of the closure may face toward an inner surface of the vapor passage and be configured for a sealing cooperation or sealing engagement with the inner surface. [0029] For example, the closure 150 can be configured for a radially expanded state or a radially retracted state. In the radially expanded state, the radial dimension of the closure 150 is expanded such that the closure can occlude or radially fill the vapor passage 145. In the radially retracted state, the radial dimension of the closure 150 is smaller than the vapor passage 145, particularly smaller than the dimension of the vapor passage 145 in a sectional plane perpendicular to the axis (A) of the vapor passage 145.

[0030] In some embodiments, which can be combined with other embodiments described herein, the closure 150 can be configured to be switchable between a first closure position and a second closure position. In the first closure position, the closure 150 can be positioned outside the vapor passage 145. In the second closure position, the closure 150 can be positioned in the vapor passage 145. If the closure 150 is switched to the first closure position, the valve assembly 140 is in an open state. In the open state, evaporated material 130 can pass through the vapor passage 145, particularly from the evaporation crucible 110 to the vapor distribution assembly 120 and more particularly further through distribution outlets 125 of the vapor distribution assembly 120.

[0031] If the closure 150 is switched to the second closure position and the closure 150 is in a radially retracted state, the valve assembly 140 may be in a partially closed state. In the partially closed state, the vapor passage 145 can be partially occluded. If the closure 150 is switched to the second closure position and the closure 150 is in a radially expanded state, the valve assembly 140 is in a closed state. In the closed state, the vapor passage 145 is sealed. In particular, a flow of evaporated material 130 through the vapor passage 145 can be stopped.

[0032] The evaporation source 100 can stop a flow of evaporated material 130 through the vapor passage 145 by switching the valve assembly 140 from the open state first to the partially closed state and then to the closed state. To switch the valve assembly 140, the closure 150 can first be switched from the first closure position to the second closure position. In the partially closed state, evaporated material 130 may still pass through a partially occluded vapor passage 145. Then, the closure 150 can be expanded to a radially expanded state. In the radially expanded state, the closure 150 can seal the vapor passage 145 and the valve assembly 140 switches to the closed state.

[0033] If the valve assembly is switched from the open state to the closed state during the operation of an 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 a vapor passage, a closure does not have to be axially moved or axially pressed against a force resulting from the pressure difference. Instead, a closure according to embodiments described herein may be positioned, in particular in an axial direction, before closing or sealing the vapor passage by changing a radial dimension of the closure. Without requiring high axial forces for closing the vapor passage, 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. Furthermore, closing a vapor passage using a closure with variable radial dimension according to embodiments described herein may provide a tighter sealing than closures which are axially pressed onto a valve surface surrounding a vapor passage.

[0034] Figs. 2A-C show schematic cross-sectional side views of a valve assembly 200 of an evaporation source 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.

[0035] The valve assembly 200 is positioned at a vapor passage 215, which extends along an axis 201. In Fig. 2A-C, the valve assembly 200 includes a valve housing 205 with an inlet 210 extending from an evaporation crucible, and the vapor passage 215 leading to a vapor distribution assembly. The closure 220 may be pivotable between a first closure position shown in Fig. 2A and a second closure position shown in Fig. 2B and Fig. 2C. In particular, the closure 220 can be arranged on a pivot arm 230 being pivotable around a pivot point 235. [0036] In Fig. 2A, the closure 220 is shown in a radially retracted state and in the first closure position. The valve assembly 200 is in an open state. In Fig. 2B, the closure 220 is switched to the second closure position. The closure 220 in the radially retracted state does not seal the vapor passage 215, leaving a residual opening 240 in the vapor passage 215. In the partially closed state of the valve assembly 200, at least some evaporated material may flow through the residual opening 240. In Fig. 2B, the residual opening 240 is exemplarily shown as an annular slit opening. In Fig. 2C, the closure 220 is shown in a radially expanded state. The closure 220 seals the vapor passage 215. The valve assembly 200 in Fig. 2C is in the closed state and a flow of evaporated material can be blocked or stopped.

[0037] Fig. 3A-C show schematic cross-sectional side views of a valve assembly 300 of an evaporation source according to embodiments described herein. The evaporation source may include any of the features of the previously described evaporation sources, such that reference can be made to the above explanations, which are not repeated here.

[0038] The valve assembly 300 includes a closure 220, wherein the closure 220 includes a deformable element 325. In some embodiments, the deformable element 325 is provided as a bellows. The deformable element 325 may be hollow or gas-filled. As shown in Fig. 3C, the deformable element 325 may be deformed by changing the strength of an axial force applied to the deformable element 325.

[0039] An axial force may be applied by an actuator, particularly by an electrically driven actuator, e. g. by an electric motor, or by a pneumatic actuator. In particular, the deformable element 325 may be disposed between two closure pieces 350 of the closure 220, wherein at least one of the two closure pieces 350 can be moved, particularly by an actuator, in an axial direction relative to the other one of the two closure pieces 350.

[0040] In some embodiments, the deformable element 325 of Fig. 3 A-3B can be gas-filled and pneumatically connected to a pressure source, e. g. via a tube along a pivot arm 230. The pressure source may change a pressure in the deformable element 325 of the closure 220 to deform the deformable element 325. Changing a pressure in the closure 220 may switch the closure 220 between a radially retracted state and a radially expanded state. In particular, the deformable element 325 may be positioned axially between two closure pieces 350 of a closure 220. The two closure pieces 350 can be static relative to each other. Positioning of the deformable element 325 between the two closure pieces 350 may reduce deformation of the deformable element 325 in an axial direction or increase deformation in a radial direction.

[0041] Figs. 4A-B and Figs. 5A-B each show a valve assembly with a closure 220 comprising different deformable elements, while other features correspond to the valve assembly 300 of Figs. 3A-C. In Figs. 4A-B, a deformable element 425 of valve assembly 400 is provided as a deformable ring, particularly as a hollow deformable ring. In Figs. 5A-B, a deformable element 525 of a valve assembly 500 is provided as a bellows with at least two folds extending in a radial direction. A bellows with at least two folds can provide the advantage that, in a radially expanded state, the deformable element 525 can seal the vapor passage 215 at two or more sealing positions along an axial direction. The sealing properties can be further improved.

[0042] Figs. 6A-B show schematic cross-sectional side views of a valve assembly 600 of an evaporation source according to embodiments described herein. The evaporation source may include any of the features of the previously described evaporation sources, such that reference can be made to the above explanations, which are not repeated here.

[0043] The closure 220 of the valve assembly 600 includes another deformable element, while other features may correspond to the valve assembly 300 of Figs. 3A-3C. In Figs. 6A-B, a deformable element 625 is provided as a bistable membrane. In particular, the bistable membrane may be switched from a radially retracted state, as shown e. g. in Fig. 6A, to a radially expanded state, as shown for instance in Fig. 6B, by applying an axial force to the bistable membrane. Similar to embodiments described in conjunction with Figs. 3A-C, an axial force may be applied to the deformable element 625 by moving at least one of the two closure pieces 350 relative to the other one of the two closure pieces 350.

[0044] As Figs. 6A-B, Figs. 7A-B show a valve assembly 700 with a bistable membrane as a deformable element 725 of the closure 220. In Fig. 7B, an axial force is applied to the deformable element 725 by axially pushing the deformable element 725 against a ledge 760 extending in a radial direction in a vapor passage 215. Axially pushing the deformable element 725 against the ledge 760 can trigger the bistable membrane to transition from the radially retracted state as shown in Fig. 7A to the radially expanded state as shown in Fig. 7B. In another embodiment, the deformable element 725 may be pushed against a surface surrounding a vapor passage 215, particularly against a surface transverse or essentially perpendicular to the axis 201.

[0045] In some embodiments, the closure 220 may include more than one of the deformable elements 325, 425, 525, 625, 725, e. g. a bellows and a deformable ring. Embodiments with more than one deformable element can provide a higher redundancy of sealing or a tighter sealing of a vapor passage.

[0046] According to some embodiments, which can be combined with any other embodiment described herein, a valve assembly may include a coolable valve surface, wherein a closure placed in a vapor passage is configured to receive evaporated material condensed at the coolable valve surface for closing the vapor passage. Fig. 8 A shows a valve assembly 800, wherein the vapor passage 215 is surrounded by a coolable valve surface 850. In particular, the coolable valve surface 850 may be cooled via a cooling pipe 855. In Fig. 8B, a closure 220 is placed in the vapor passage 215. In Fig. 8C, the coolable valve surface 850 is cooled, resulting in the condensation of evaporated material on the coolable valve surface 850. The radial dimension of the closure 220 can be changed by receiving the condensed evaporated material 845 on an outer radial edge thereof. The condensed evaporated material 845 received by the closure 220 can close the residual opening 240 shown in Fig. 8B and seal the vapor passage 215 by clogging.

[0047] In another embodiment, a coolable valve surface may be provided on a closure 220, e. g. by providing a cooling fluid to the closure 220, particularly via a tube along a pivot arm 230. In yet another embodiment, a closure 220 may comprise a deformable element of other embodiments described herein.

[0048] Heating of the coolable valve surface 850 may lead to an evaporation of the condensed evaporated material, such that the radial dimension of the closure reduces and the vapor passage is unblocked. Alternatively or additionally, the clogged vapor passage can be opened by simply pivoting the closure from the second closure position depicted in Fig. 8c to the first closure position depicted in Fig. 8A.

[0049] Fig. 9 shows a schematic cross-sectional side view of an evaporation source 900 according to embodiments, which can be combined with other embodiments described herein. A valve assembly 940 is arranged at a vapor passage (also referred to herein as a first vapor passage 945) and at a second vapor passage 955. The first vapor passage 945 fluidly connects an evaporation crucible 910 and a vapor distribution assembly 920. The second vapor passage 955 may fluidly connect the evaporation crucible 910 with a vapor receiving assembly 960. The evaporation crucible 910 may be configured to evaporate a material 915, which may flow as evaporated material 930 through the first vapor passage 945 to the vapor distribution assembly 920 or through the second vapor passage 955 to a vapor receiving assembly 960.

[0050] In particular, depending on the state of the valve assembly 940, the evaporated material may either be guided from the evaporation crucible 910 along the first vapor passage 945 into the vapor distribution assembly 920 to be deposited on a substrate, or from the evaporation crucible 910 along the second vapor passage 955 into the vapor receiving assembly 960, which may be a material collection manifold, e.g. a material container. Accordingly, the evaporation source can switch between a deposition state, in which evaporated material is allowed to propagate through the first vapor passage 945 into the vapor distribution assembly 920, wherein the second vapor passage 955 may be closed, and an idle position, in which the evaporated material is allowed to propagate through the second vapor passage 955 into the material collection manifold, wherein the first vapor passage 945 may be closed in the idle position.

[0051] In Fig. 9, the valve assembly 940 includes a closure 950, which is switchable between a first closure position and a second closure position. In the first closure position, the first vapor passage 945 is open. Evaporated material 930 may flow through the first vapor passage 945 to the vapor distribution assembly 920 and in particular through distribution outlet 925 to a vacuum chamber or a substrate. In the first closure position, the closure 950 may be placed in the second vapor passage 955, particularly for closing the second vapor passage 955.

[0052] In the second closure position, the closure 950 is placed in the first vapor passage 945 for closing the first vapor passage 945 and the second vapor passage 955 is open. Evaporated material 930 may flow through the second vapor passage 955 to the vapor receiving assembly 960. The vapor receiving assembly 960 can include a housing or container, particularly a housing or container with a temperature-controlled surface. In particular, the temperature-controlled surface of the vapor receiving assembly can be a coolable surface for condensing the evaporated material 930 on the surface, and/or a heatable surface, in particular for re-evaporating condensed evaporated material. Thus, when the first vapor passage 945 is closed, i.e. when the evaporation source is in an idle state, evaporated material 930 may flow from the evaporation crucible 910 through the second vapor passage 955, particularly into a material collection manifold. Accordingly, uniform and essentially constant pressure conditions can be maintained in an inner volume of the evaporation source in the idle state of the evaporation source, since a flow of evaporated material from the evaporation crucible can be maintained even in the idle state of the evaporation source by directing the evaporated material through the second vapor passage into the vapor receiving assembly 960.

[0053] In some embodiments, a first fluid conductance of a first vapor path from the evaporation crucible 910 to the vapor distribution assembly 920 (with the closure 950 in the first closure position) may essentially equal a second fluid conductance of a second vapor path from the evaporation crucible 910 to the vapor receiving assembly 960 (with the closure 950 in the second closure position). For example, the valve assembly 940 may include a pressure sensor or a flow rate sensor for measuring a pressure or a flow of evaporated material in a respective valve position and/or a control device for controlling a pressure or a flow of evaporated material, e. g. by changing a temperature of a temperature- controlled surface of the vapor receiving assembly 960 to maintain a predetermined (e.g., a constant) pressure or flow of the evaporated material.

[0054] Embodiments described herein can advantageously provide a valve assembly, which can close a (first) vapor passage and avoid or reduce a build-up of pressure between an evaporation crucible and the closed vapor passage. In particular, embodiments described herein can provide the advantage that a pressure between an evaporation crucible and the (first) vapor passage, particularly in a valve assembly, can be held essentially constant, while the (first) vapor passage is closed. This is enabled by providing a valve assembly configured for directing the evaporated material through a second vapor passage into a vapor receiving assembly, when the first vapor passage is closed, such that a material flow from the evaporation crucible to the valve assembly can be maintained without a pressure build-up, even if the first vapor passage is closed. Providing a constant pressure or a reduced pressure build-up can further facilitate pausing, stopping or starting a flow of evaporated material through the vapor passage to the distribution assembly for depositing evaporated material on a substrate.

[0055] Specifically, according to a second aspect described herein, an evaporation source including an evaporation crucible, a vapor distribution assembly for directing evaporated material to a substrate, and a valve assembly configured to open and close a first vapor passage between the evaporation crucible and the vapor distribution assembly is provided. The evaporation source is switchable between a deposition state, in which the first vapor passage is open, and an idle state, in which the first vapor passage is closed or sealed, such that the deposition process can be stopped. In the idle state, the valve assembly allows the evaporated material to flow through a second vapor passage into a vapor receiving assembly. In other words, the valve assembly of embodiments described herein may be configured as a“three-way valve” that is configured to direct evaporated material from the evaporation crucible into one of a distribution assembly and a vapor receiving assembly. Due to more stable pressure conditions inside the evaporation source, the evaporation source can switch between the deposition state and the idle state more quickly. The up-time of the evaporation source can be increased.

[0056] Figs. 10A-B show a schematic cross-sectional side view of a valve assembly 1000 of an evaporation source according to embodiments described herein. The valve assembly 1000 is arranged at a first vapor passage 1015 extending along an axis 1001 and at a second vapor passage 1025 extending along a second axis 1003. An inlet 1010 extends from an evaporation crucible and fluidly connects the evaporation crucible with a housing 1005 of the valve assembly. A closure 1020 can be arranged in the housing 1005, in particular on a pivot arm 1030, which can be pivotable around a pivot point 1035.

[0057] In Fig. 10A, the closure 1020 is shown in the first closure position, with the closure being placed in the second vapor passage 1025. The first vapor passage 1015 is open. In Fig. 10B, the closure 1020 is shown in the second closure position. The closure 1020 is placed in the first vapor passage 1015. In the second closure position, the closure 1020 can seal the first vapor passage 1015. The second vapor passage 1025 is open. Evaporated material may flow through the second vapor passage 1025, particularly to a vapor receiving assembly. In other words, the valve assembly may include one closure that is suitable for closing either one of the first vapor passage and the second vapor passage. In some embodiments, the valve assembly may include a first closure configured to close the first vapor passage in the second closure position and a second closure configured to close the second vapor passage in the first closure position. The first closure and the second closure may be arranged on one or more pivot arms, wherein the first closure is configured for closing the first vapor passage and the second closure is configured for closing the second vapor passage.

[0058] Fig. 11 shows a valve assembly 1100 with a closure 1020 shown in the second closure position, allowing for evaporated material to flow through the second vapor passage 1025 to a vapor receiving assembly 1150. The vapor receiving assembly 1150 of Fig. 11 includes a temperature-controlled surface 1155 for condensing evaporated material thereon and/or for re-evaporating condensed evaporated material therefrom. Condensed evaporated material 1160 may be collected in the vapor receiving assembly 1150, particularly on the temperature-controlled surface 1155. In particular, condensed evaporated material 1160 may be collected for disposal or for recycling. Furthermore, condensing evaporated material in a vapor receiving assembly can advantageously facilitate controlling a pressure in an evaporation source. [0059] In some embodiments, the closure 1020 may be switched to a third closure position in which the first vapor passage 1015 and the second vapor passage 1025 are open. In particular, in the third closure position, condensed evaporated material 1160 on the temperature-controlled surface 1155 may be re evaporated, particularly by heating the temperature-controlled surface 1155. Re- evaporated material may then pass from the vapor receiving assembly 1150 through the second vapor passage 1025 and through the first vapor passage 1015, e. g. into the vapor distribution assembly.

[0060] Figs. 12A-C show a valve assembly 1200 of an evaporation source according to embodiments described herein. The evaporation source corresponds to any of the previously described evaporation sources, such that reference can be made to the above explanations, which are not repeated here.

[0061] The valve assembly 1200 includes a closure 1020, which has a variable radial dimension. Fig. 12A shows the closure 1020 in a first closure position and in a radially retracted state. The first vapor passage 1015 is open. In Fig. 12A, the second vapor passage 1025 is closed by a second closure 1230. In particular, the second vapor passage 1025 can be closed by pressing the second closure 1230 axially, particularly axially relative to a second axis 1003 along the second vapor passage 1025, onto a surface surrounding the second vapor passage 1025. [0062] Fig. 12B shows the closure 1020 in the second closure position and in a radially retracted state, particularly radially retracted relative to an axis 1001 of the first vapor passage 1015. The first vapor passage 1015 is partially closed. In particular, the first vapor passage 1015 may include a residual opening 1240, which can allow for evaporated material to pass through the partially closed first vapor passage 1015. The second vapor passage 1025 is open.

[0063] In Fig. 12C, the closure 1020 in the second closure position is switched to a radially expanded state. The first vapor passage 1015 is closed and the second vapor passage 1025 is open. In particular, the closure 1020 may be provided by any of the closures described in conjunction with Figs. 1-8C. More particularly, the closure 1020 may comprise a deformable element as described in conjunction with Figs. 3A-7B or the closure 1020 may receive condensed evaporated material to change a radial dimension of the closure 1020 according to embodiments described in conjunction with Figs. 8A-8C.

[0064] In yet another embodiment, a second closure that is configured for closing the second vapor passage 1025 can have a variable radial dimension. In the first closure position, the second closure may seal the second vapor passage by switching from a radially retracted state to a radially expanded state.

[0065] Figs. 13A-B show schematic cross-sectional side views of a valve assembly 1300 of an evaporation source according to embodiments described herein. The evaporation source may include any of the features of the previously described evaporation sources, such that reference can be made to the above explanations, which are not repeated here. In particular, the valve assembly 1300 may include a closure 1320 that is switchable between a first closure position (FIG. 13 A) in which a first vapor passage 1315 between an evaporation crucible and a vapor distribution assembly is open and a second closure position (FIG. 13B) in which a second vapor passage 1325 between the evaporation crucible and a vapor receiving assembly is open.

[0066] In Figs. 13A-B, the closure 1320 is arranged on a linear actuator 1330. The linear actuator 1330 can move or switch the closure 1320 between the first closure position, as shown in Fig. 13 A, and the second closure position, as shown in Fig. 13B. In the first closure position, the closure 1320 can be positioned within the second vapor passage 1325, such that the first vapor passage 1315 is open, whereas the second vapor passage 1325 may be closed. In the second closure position, the closure is placed within the first vapor passage 1315, such that the second vapor passage 1325 is open, whereas the first vapor passage 1315 may be closed. In some embodiments, the linear actuator 1330 may include an actuator bellows 1335, for example to shield the linear actuator 1330, a shaft of the linear actuator 1330 or a bearing of the linear actuator 1330 against evaporated material.

[0067] In the embodiment depicted in Figs. 13A-B, the closure 1320 may have a variable radial dimension. More particularly, the closure 1320 may be provided by any of the closures described in conjunction with Figs. 1-8C. The closure 1320 may comprise a deformable element as described in conjunction with Figs. 3A-7B or the closure 1320 may receive condensed evaporated material to change a radial dimension of the closure 1320 according to embodiments described in conjunction with Figs. 8A-8C.

[0068] 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. More than one 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.

[0069] 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.

[0070] According to one aspect described herein, a method of depositing an evaporated material on a substrate is described. Fig. 14 shows a flow chart of an exemplary method 1400 according to embodiments described herein. The method 1400 includes evaporating (see block 1410) a material. In particular, the material can be evaporated in an evaporation crucible according to embodiments described herein. The method 1400 further includes guiding (see block 1420) the evaporated material through a first vapor passage into a vapor distribution assembly. In block 1420, 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 1400 includes closing (see block 1430) the first vapor passage and guiding the evaporated material through a second vapor passage into a vapor receiving assembly. In particular, closing (block 1430) can include changing a radial dimension of a closure placed in the vapor passage. In some embodiments, the method 1400 can further include condensing the evaporated material in the vapor receiving assembly, e.g. by cooling a wall surface of the vapor receiving assembly. In block 1430, the evaporation source is in an idle state, in which the deposition process is halted or interrupted.

[0071] In the idle state and in the deposition state, a flow of evaporated material from the evaporation crucible and, therefore, the pressure conditions inside the evaporation crucible, can be kept essentially unchanged, such that a reduced switching time between the deposition state and the idle state can be provided.

[0072] The method 1400 may be performed using embodiments of an evaporation source as described herein, particularly using embodiments described in conjunction with Figs. 9-13B. In particular, a valve assembly according to embodiments described herein may be arranged at the first vapor passage and the second vapor passage. For guiding (block 1420) the evaporated material through the first vapor passage, a closure of a valve assembly can be placed in a first closure position according to embodiments described herein. For closing (block 1430) the first vapor passage and guiding the evaporated material through a second vapor passage into the vapor receiving assembly, the closure of the valve assembly can be placed in the second closure position. In particular, the closure may have a variable radial dimension.

[0073] In view of the embodiments described herein, it is to be understood that an improved evaporation source, an improved vacuum deposition system 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 guide or stop a flow of evaporated material from the evaporation crucible to the distribution assembly and to a vapor receiving assembly, respectively. This can particularly be beneficial during the start of the deposition process, 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.

[0074] 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.

[0075] 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.

[0076] 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 (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m² of substrate (1.95 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.

[0077] 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.

[0078] 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.

[0079] 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.

[0080] 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 closure that can be placed in the vapor passage and that has a variable radial dimension.

2. The evaporation source according to claim 1, wherein the closure is switchable between a first closure position, in which the vapor passage is open, and a second closure position, in which the closure is placed in the vapor passage for closing the vapor passage and a second vapor passage is open.

3. The evaporation source according to claim 2, wherein the closure is switchable between the first closure position and the second closure position by pivoting the closure, particularly wherein the closure is arranged on a pivot arm, or by linearly moving the closure, particularly wherein the closure is movable by a linear actuator.

4. The evaporation source according to any of claims 2 to 3, further comprising a vapor receiving assembly connected to the second vapor passage.

5. The evaporation source according to claim 4, wherein the vapor receiving assembly comprises a temperature-controlled surface for condensing evaporated material and/or for re-evaporating condensed evaporated material.

6. The evaporation source according to any of claims 2 to 5, wherein, in the first closure position, the closure or a second closure seals the second vapor passage.

7. The evaporation source according to claim 6, wherein, in the first closure position, the closure or the second closure is axially pressed onto a surface surrounding the second vapor passage.

8. The evaporation source according to any of claims 1 to 7, wherein the radial dimension of the closure is variable by deforming the closure, particularly wherein the closure is deformable to a radially expanded state and/or to a radially retracted state.

9. The evaporation source according to any of claims 1 to 8, wherein the valve assembly comprises a pressure source configured for changing a pressure in the closure for deforming the closure and/or wherein the valve assembly comprises an actuator configured for providing a force, particularly an axial force, on the closure for deforming the closure.

10. The evaporation source according to any of claims 1 to 9, wherein the valve assembly comprises a coolable valve surface, in particular a coolable valve surface surrounding the vapor passage and/or a coolable valve surface on the closure, and wherein the closure placed in the vapor passage is configured to receive evaporated material condensed at the coolable valve surface for closing the vapor passage.

11. The evaporation source according to any of claims 1 to 10, wherein the closure comprises a deformable element, in particular a bistable membrane, a multistable membrane, a bellows and/or a deformable ring.

12. 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 first vapor passage between the evaporation crucible and the vapor distribution assembly, the valve assembly comprising a closure that is switchable between a first closure position, in which the first vapor passage is open, and a second closure position, in which the closure is placed in the first vapor passage for closing the first vapor passage and a second vapor passage is open.

13. A vacuum deposition system, comprising:

- a vacuum deposition chamber;

- an evaporation source according to any of claims 1 to 12 in the vacuum deposition chamber; and

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

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

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

closing the first vapor passage and guiding the evaporated material through a second vapor passage into a vapor receiving assembly.

15. The method according to claim 14, wherein closing the vapor passage

includes changing a radial dimension of a closure placed in the vapor passage.