Evaporation source, deposition system and method for depositing a material

Abstract

The present invention relates to an evaporation source for depositing a material on a substrate, comprising an evaporation crucible to evaporate the material; a distribution pipe comprising a wall that defines a vapor propagation volume for receiving evaporated material from the evaporation crucible; and a plurality of nozzles for directing the evaporated material onto the substrate; and a heating assembly for the distribution pipe, comprising a heating element arranged at least partially in the distribution pipe and configured to radiate heat, the heating assembly configured to accelerate electrons from the heating element towards at least a portion of the wall.

Description

AMAT#44023862WO01 - 1 - 34882 P-WOEVAPORATION SOURCE, DEPOSITION SYSTEM AND METHOD FOR DEPOSITING A MATERIALTECHNICAL FIELD OF THE INVENTION

[0001] Embodiments of the present disclosure relate to evaporation of materials and heating of a distribution pipe of an evaporation source. For example, embodiments relate to evaporation at high temperatures, e.g. for deposition of metallic and non-metallic materials on substrates. Embodiments relate to evaporation for, e.g., OLED manufacturing. In particular, the present disclosure relates to an evaporation source for depositing a material on a substrate, a deposition system and a method for depositing a material on a substrate.BACKGROUND OF THE INVENTION

[0002] Material deposition may be provided for various applications, for example for OLED manufacturing or for depositing material onto large area substrates.

[0003] An organic light-emitting diode (OLED) is a light-emitting diode in which an electroluminescent layer is a film of organic compounds that emits light in response to an electric current. Organic light emitting diodes (OLEDs) are used in the manufacture of television screens, computer monitors, mobile phones, other handheld devices, etc., for displaying information. OLEDs can also be used for general space illumination. An OLED display, for example, may include layers of organic material situated between two electrodes that are deposited on a substrate in a manner so as to form a matrix display panel having individually energizable pixels.

[0004] For OLED manufacturing, organic materials and metallic materials are deposited on a substrate in vacuum processing chambers. Metallic and non-metallic materials are employed as, for example, electrode materials or electron injection layer (EIL) materials.AMAT#44023862WO01 - 2 - 34882 P-WO

[0005] Materials to be deposited (e.g., for OLED manufacturing) may be evaporated using an evaporation source of an evaporation system. Firstly, a material within a crucible may be heated to evaporate the material. Subsequently, the evaporated material may be guided through a distribution pipe of the evaporation source and may be directed onto a substrate through nozzles for coating the substrate with the material. The evaporated material may be further heated within the evaporation source, particularly within the distribution pipe, to prevent the evaporated material from condensing within the evaporation source. In some evaporation sources, e.g., for metal deposition, extremely high temperatures above 1 ,000°C, or above 1 ,500°C, may be provided, e.g., for evaporating metals and keeping the metal in a vapor state within the evaporation source.

[0006] W02017008838A1 relates to an evaporation source for a metal or a metal alloy. The evaporation source includes an evaporation crucible, wherein the evaporation crucible is configured to evaporate the metal or metal alloy, a distribution pipe with one or more outlets provided along the length of the distribution pipe, wherein the distribution pipe further comprises an outer tube and an inner tube, and wherein the distribution pipe and the evaporation crucible are provided as one single piece.

[0007] Providing the temperatures within the evaporation source suitable for evaporating the material and maintaining the evaporated material in a vapor state is generally challenging. In particular, it is generally not sufficient to provide a crucible heater for heating the crucible, and also other parts of the evaporation source, including the distribution pipe, may be heated. Due to the high temperatures for the evaporation and deposition process and due to the size and design of the evaporation source, providing a reliable and durable heating system is difficult.

[0008] Accordingly, it would be beneficial to provide an improved evaporation source for material deposition on substrates, particularly an evaporation source with an improved heating.AMAT#44023862WO01 - 3 - 34882 P-WOSUMMARY OF THE INVENTION

[0009] In light of the above, an evaporation source for depositing a material on a substrate, a deposition system, and a method for depositing a material on a substrate are provided. Further advantages, features, aspects and details are evident from the dependent claims, the description and the drawings.

[0010] A first aspect relates to an evaporation source for depositing a material on a substrate, comprising: an evaporation crucible to evaporate the material, a distribution pipe, and a heating assembly for the distribution pipe. The distribution pipe includes a wall that defines a vapor propagation volume for receiving evaporated material from the evaporation crucible, and a plurality of nozzles for directing the evaporated material onto the substrate. The heating assembly for the distribution pipe includes a heating element arranged at least partially in the distribution pipe and configured to radiate heat, the heating assembly configured to accelerate electrons from the heating element towards at least a portion of the wall.

[0011] A second aspect relates to a method for depositing a material on a substrate, the method comprising: evaporating the material in an evaporation crucible; guiding the evaporated material into a vapor propagation volume of a distribution pipe defined by a wall; heating the distribution pipe, wherein the heating includes: radiating heat from a heating element that is at least partially arranged in the distribution pipe; and accelerating electrons released from the heating element towards at least a portion of the wall; and directing the evaporated material from the vapor propagation volume onto a substrate with a plurality of nozzles of the distribution pipe.

[0012] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method step. The method steps may be performed byway of hardware components, a computer programmed by appropriate software, by any combination of the two, or in any other manner. Furthermore, embodiments according to the present disclosure are also directed at methods by which the described apparatus operates.AMAT#44023862WO01 - 4 - 34882 P-WOBRIEF DESCRIPTION OF THE DRAWINGS

[0013] So that the manner in which the above recited features of the present invention can be understood in detail, a more particular description of the invention, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the invention and are described in the following:

[0014] FIG. 1 shows a schematic sectional view of an evaporation source according to embodiments described herein;

[0015] FIG. 2 shows a schematic heating concept of an evaporation source according to embodiments described herein;

[0016] FIG. 3 shows a schematic view of a heater for use in an evaporation source according to embodiments of the present disclosure;

[0017] FIG. 4 shows an electrical equivalent circuit diagram of the heater according to embodiments of the present disclosure;

[0018] FIG. 5 shows a schematic cross-sectional view of a heater for use in an evaporation source according to embodiments described herein;

[0019] FIG. 6 shows a schematic view of a deposition system with an evaporation source according to embodiments of the present disclosure; and

[0020] FIG. 7 shows a flowchart illustrating a method of depositing a material according to embodiments of the present disclosure.DETAILED DESCRIPTION OF EMBODIMENTS

[0021] Reference will now be made in detail to the various embodiments of the invention, one or more examples of which are illustrated in the figures. Within the following description of the drawings, the same reference numbers refer to same components. Generally, only the differences with respect to individual embodimentsAMAT#44023862WO01 - 5 - 34882 P-WO are described. Each example is provided by way of explanation of the invention and is not meant as a limitation of the invention. Further, features illustrated or described as part of one embodiment can be used on or in conjunction with other embodiments to yield yet a further embodiment. It is intended that such modifications and variations are included.

[0022] As described herein, evaporation sources can be used for various applications. For example, evaporation sources can be used for OLED manufacturing and / or for depositing materials on large area substrates, e.g. metallic or non-metallic materials, such as organic materials. However, the present disclosure is not limited to said types of applications and may be applied to other deposition processes, including material deposition on semiconductor substrates.

[0023] Materials can be deposited on substrates using an evaporation source, the evaporation source including a distribution pipe for guiding evaporated material to a plurality of nozzles that are configured to direct the material onto the substrate. Such a material deposition process may also include heating the evaporated material within the distribution pipe (e.g., to avoid condensation of the evaporated material within the distribution pipe). For such a material deposition process comparatively high temperatures may be provided. For example, metallic materials are typically evaporated in an evaporation source at a temperature of 500°C or above, 1 ,000°C or above, or even 1 ,500°C or above. Organic materials are typically evaporated in an evaporation source at temperatures between 250°C and 500°C.

[0024] To enable the temperature ranges for the deposition process, a heater having an electrical heating element may be used. The heating element can reside within the distribution pipe. The heating element may be configured for radiating heat, e.g., based on resistive heating (also termed Joule heating). An electrical current may be applied to the heating element which causes radiation of heat to achieve the temperatures for the deposition process. The heat provided by the heating element may depend on the electrical current flowing through the heating element. A higher current may lead to an increased heat radiation and an increased temperature, so that - for obtaining higher temperatures - higher voltages can be applied across the heating element. Particularly for deposition of metallic materialsAMAT#44023862WO01 - 6 - 34882 P-WO with a high evaporation temperature, such as silver, high temperatures are typically provided for evaporating the metal, so that a comparatively high electrical current may flow through the heating element.

[0025] The present disclosure is based on the insight that heaters configured to provide high temperatures in evaporation sources can be problematic, for example because high electric currents through a heating element can more easily lead to undesired electrical discharges and / or electrical connections between the heating element and another component. Electric discharges with high currents can cause harm to the evaporation system, or even cause damage to components of the system. For example, undesired electrical shorts or discharges may have a more significant effect when a higher current is flowing through the heating emitter which may be provided by a higher voltage applied across the heating emitter.

[0026] The embodiments of the present disclosure may alleviate unbeneficial effects stemming from (especially) high electrical currents flowing through heating elements while still enabling a reliable heating and evaporation of the deposition materials by achieving the appropriate temperature ranges, also within the distribution pipe.

[0027] According to the present disclosure, besides a radiation heating of the distribution pipe, a further heating mechanism, an electron bombardment heating is provided. The electron bombardment heating is configured to accelerate electrons from the heating element onto parts of the distribution pipe to cause a further heating of the distribution pipe. Due to this further heating mechanism by the electron bombardment heating, electrical current flowing through the heating emitter of the heating element can be accordingly reduced. This may reduce the herein described harmful effects of an undesired electrical discharge and / or of an electrical connection between the heating emitter and another component at least in part.

[0028] FIG. 1 shows a schematic sectional view of an evaporation source according to embodiments described herein.

[0029] Particularly, FIG. 1 shows an evaporation source 100 for depositing a material 111 on a substrate, comprising: an evaporation crucible 110 to evaporateAMAT#44023862WO01 - 7 - 34882 P-WO the material 111 ; a distribution pipe 120 comprising: a wall 121 defining a vapor propagation volume 122 for receiving evaporated material from the evaporation crucible 110; and a plurality of nozzles 123 for directing the evaporated material onto the substrate. A heating assembly 132 for the distribution pipe 120 is provided. The heating assembly includes a heating element 133 arranged at least partially in the distribution pipe 120 and configured to radiate heat. According to the embodiments described herein, the heating assembly is configured to accelerate electrons 135 from the heating element towards at least a portion 12T of the wall 121 to heat the wall 121 and / or the vapor propagation volume 122 that is enclosed by the wall 121 .

[0030] The wall 121 of the distribution pipe 120 may define and enclose the vapor propagation volume 122 which receives the vapor from the evaporation crucible 110. In particular, the wall 121 may surround the vapor propagation volume, so that vapor can enter the vapor propagation volume from the evaporation crucible and exit the vapor propagation volume through the plurality of nozzles. In some embodiments, the vapor propagation volume 122 has a generally annular shape being formed between a radially inner tubular wall part and a radially outer tubular wall part of the distribution pipe, as is schematically depicted in FIG. 1. “Tube” or “tubular” as used herein is not restricted to round or circular, but can refer to an arbitrary sectional shape of the tube, including generally triangular, polygonal, etc.

[0031] During a deposition process, the material 111 residing within the evaporation crucible 110 may be heated to evaporate the material 111. The gaseous evaporated material may then be guided to the vapor propagation volume 122 of the distribution pipe 120 for further distribution. Subsequently, the evaporated material may be guided out of the distribution pipe 120 via the plurality of nozzles 123 onto a substrate, such that the material 111 can be deposited onto the substrate. Typically, the evaporated material can be maintained at a high temperature in the distribution pipe 120, e.g., to avoid condensation of the material 111 within the distribution pipe 120. The temperature within the distribution pipe 120 may beneficially be higher than the temperature in the evaporation crucible 110 for evaporating the material, e.g., since a major part of the material inside the crucible is typically still in a solid or liquid state (see FIG. 1 ). A temperature at or slightlyAMAT#44023862WO01 - 8 - 34882 P-WO above the material’s evaporation temperature may beneficially be provided in (at least parts of) the crucible, whereas a temperature substantially above the evaporation temperature may be beneficial in the vapor propagation volume 122 of the distribution pipe.

[0032] According to the present disclosure, the evaporation source 100 includes a heating assembly 132 for the distribution pipe 120, particularly for heating the evaporated material within the vapor propagation volume 122 of the distribution pipe 120. As can be seen in FIG. 1 , the heating assembly 132 can be configured for two types of heating for the distribution pipe 120.

[0033] A first type of heating can be provided by the radiation heating 130 of the heating assembly. The radiation heating 130 may be based on a resistive heating mechanism, as described herein.

[0034] For example, the heating assembly 132 may comprise a heating element 133 configured for resistive heating such that the heating element 133 will radiate heat. The heating element 133 may include a high-temperature emitter configured to provide temperatures above 500°C, above 1 ,000°C, above 1 ,200°C, or even above 1 ,500°C. The heating element 133 may include one or more electrical conductors which radiate heat when an electrical current is applied through the one or more electrical conductors.

[0035] In an embodiment, which may be combined with other embodiments described herein, the heating element 133 may include a high-temperature infrared emitter as a heating element 133, particularly a carbon-containing heat emitter, such as a graphite heat emitter, a tungsten heat emitter, or a refractory metal heat emitter.

[0036] In an embodiment, the heating element 133 may comprise one or more electrical conductors comprising a carbon-containing material, e.g., graphite, or tungsten, and / or a refractory metal different from tungsten (e.g., Mo, Ta, Nb).

[0037] Via the heating element 133, the vapor propagation volume 122 of the distribution pipe can be heated, for example, by controlling the amount of resistive heating of the heating element 133. The evaporated material within the vaporAMAT#44023862WO01 - 9 - 34882 P-WO propagation volume 122 may thus be accordingly heated, as the heating element 133 functions as a heat source.

[0038] A second type of heating can be provided by the electron bombardment heating 140 of the heating assembly 132 as described herein. The electron bombardment heating 140 may be configured to accelerate electrons from the heating element 133 towards at least a portion of the wall 121 that defines the vapor propagation volume. The electron bombardment heating 140 may be regarded as an electron acceleration configuration integrated into the evaporation source 100. At least a portion 12T of the wall 121 may function as an anode (receiving electrons) of the electron acceleration configuration. In some embodiment, an inner tube part of the wall 121 may function as the anode onto which the electrons are accelerated.

[0039] The electrons may be released from the heating element 133 due to the radiation of heat by the heating element 133. Typically, electrons 135 may be released from the heating element 133 due to the effect of thermionic emission. Due to the acceleration of the electrons by the electron bombardment heating 140, the electrons 135 may travel from the heating element 133 to impinge onto a portion 12T of the wall 121 . As described herein, the electrons 135 may be accelerated due to an electrical potential difference between the portion of the wall 121 and the heating element 133 which exerts an accelerating force onto the electrons. When the accelerated electrons 135 impinge onto the portion of the wall 121 , the wall 121 is heated. The heated wall 121 can provide a heating of the vapor propagation volume 122, particularly a heating of the evaporated material residing within the vapor propagation volume 122. Accordingly, the wall 121 is heated by two heating mechanisms: Heat radiation from the heating element 133, and electron bombardment caused by electrons released from the heating element 133 and impinging the wall.

[0040] In an embodiment, which may be combined with other embodiments described herein, the heating assembly may be configured to provide the heating by the radiation heating 130 and the heating by the electron bombardment heating 140 simultaneously for heating the vapor propagation volume 122. The heating of the vapor propagation volume 122 may thus be achieved via the radiation heatingAMAT#44023862WO01 - I Q - 34882 P-WO130 and the electron bombardment heating 140. The total heat provided to the vapor propagation volume 122 may thus comprise a first heat generated by the radiation heating 130 and a second heat generated by the electron bombardment heating 140. This may enable to reduce the current flowing through the heating element 133 since the heat generated with the electron bombardment heating 140 can be chosen such that the total heat provided by the heating assembly is sufficient for the evaporated material residing within the vapor propagation volume 122. Accordingly, the current flowing through the heating element 133 and / or the voltage applied between the terminals of the heating element 133 can be reduced as compared to a heating assembly without the electron bombardment heating.

[0041] For example, a total heat of Qomay be appropriately provided to the vapor propagation volume 122, e.g., to ensure that the evaporated material residing within the vapor propagation volume 122 will not condensate. Without the electron bombardment heating 140, the radiation heat provided by the heating element 133 of the radiation heating 130 alone would have to provide the total heat of Qo. The embodiments of the present disclosure may avoid exclusive heating by heat radiation from the heating element 133 provided by the radiation heating. In accordance with the present disclosure, a first heat Qi > 0 may be provided by the radiation heating 130 and a second heat Q2> 0 may be provided by the electron bombardment heating 140 wherein the first heat Q-, and the second heat Q2combined may equal at least the total heat of Qo.

[0042] According to the present disclosure, the current flowing through the heating element may thus be reduced since the electron bombardment heating 140 may add an additional heat via the heating contribution caused by electrons impinging on the portion of the wall 121. Accordingly, a smaller amount of electrical current flowing through the heating element 133 may be provided (and / or a respective smaller voltage may be applied across the heating element 133). The negative effects of electrical discharges of the heating element 133 with respect to other components may thus be reduced at least in part (e.g., due to the lower currents flowing through the heating element 133).AMAT#44023862WO01 - 11 - 34882 P-WO

[0043] In an embodiment, which may be combined with other embodiments described herein, the wall 121 may comprise an inner tube part 151 and an outer tube part 152, the vapor propagation volume 122 being at least partially formed between the inner tube part 151 and the outer tube part 152. The heating element 133 may be at least partially surrounded by the inner tube part 151 .

[0044] In an example, with the heating element 133 being at least partially surrounded by the inner tube part 151 , the heating element 133 may at least partially be surrounded by the vapor propagation volume 122, with the inner tube part 151 forming a border such that a gaseous environment of the vapor propagation volume 122 may not come into contact with the heating element 133. The heating element 133 may thus be protected by the inner tube part 151 from the evaporated material residing within the vapor propagation volume 122.

[0045] For example, the inner tube part 151 may form and surround an inner tube volume 153. The inner tube volume 153 may be surrounded at least partially by the vapor propagation volume 122. The heating element 133 may be positioned within the inner tube volume 153. The inner tube volume 153 may form a different volume than the vapor propagation volume 122. The inner tube volume 153 may have no contact to the material residing within the vapor propagation volume 122, with the inner tube part 151 forming a border between the inner tube volume 153 and the vapor propagation volume 122.

[0046] In an embodiment, which may be combined with other embodiments described herein, the inner tube part 151 and the outer tube part 152 of the wall 121 may be electrically coupled to each other. For example, the inner tube part 151 may comprise an electrically conducting material and the outer tube part 152 may comprise an electrically conducting material in contact with the electrically conducting material of the inner tube part. Accordingly, the inner tube part 151 and the outer tube part 152, particularly the entire wall that defines and surrounds the vapor propagation volume 122, may be on the same electric potential. If an electrical potential is applied to the outer tube part 152, the inner tube part 151 may be set on the same electrical potential (or substantially the same electrical potential), or viceAMAT#44023862WO01 - 12 - 34882 P-WO versa, due to the electrical coupling between the inner tube part 151 and the outer tube part 152.

[0047] In an embodiment, which may be combined with other embodiments described herein, the inner tube part 151 and the outer tube part 152 may be both set to a ground potential.

[0048] Subsequently, the heating assembly, particularly the electron bombardment heating 140, is described in more detail.

[0049] In an embodiment, which may be combined with other embodiments described herein, the heating assembly may be configured to set the heating element 133 on a first electrical potential and / or to set the portion 12T of the wall 121 , particularly the inner tube part 151 , on a second electrical potential to accelerate electrons towards the portion 12T of the wall 121.

[0050] The first electrical potential may be more negative than the electrical potential of the portion of the wall 121 in order to allow an acceleration of the negatively charged electrons from the heating element 133 towards the portion of the wall 121 .

[0051] The second electrical potential may be more positive than the electrical potential of the heating element 133 in order to allow an acceleration of the negatively charged electrons released by the heating element 133 towards the portion of the wall 121.

[0052] The electrons to be accelerated onto the portion of the wall may be released from the heating element 133. As described herein, electrons may be released from the heating element 133 due to the heating of the heating element 133 (e.g., based on a thermionic effect).

[0053] In an embodiment, which may be combined with other embodiments described herein, the portion 12T of the wall may include at least a portion of the inner tube part 151 . In such an embodiment, the electrons may thus be accelerated from the heating element 133 towards the inner tube part 151. For example, due to the radiation heating provided by the heating element 133 (e.g., via resistiveAMAT#44023862WO01 - 13 - 34882 P-WO heating) electrons may be released from the heating element 133. The electrons may thus be released into the volume between the heating element 133 and the inner tube part (e.g., into the inner tube volume 153).

[0054] The heating element 133 may be set on the first electrical potential, and / or the inner tube part 151 or a portion thereof may bet set on the second electrical potential to accelerate electrons towards the inner tube part 151. The accelerated electrons may impinge onto the inner tube part 151 causing a heating of the inner tube part 151. The heating of the inner tube part 151 may cause a heating of the vapor propagation volume 122. Hence, a first heating contribution may be applied to the vapor propagation volume 122 by the radiation heating contribution of the heating element 133, and a second heating contribution may be applied to the vapor propagation volume 122 by accelerating the electrons onto the inner tube part 151.

[0055] In an embodiment, which may be combined with other embodiments described herein, the portion of the wall the electrons are accelerated to may include at least a portion of the inner tube part 151 and may not include the outer tube part 152.

[0056] In an example, the wall 121 may include one or more parts comprising an electrically conducting material (e.g. a metallic material). The second electrical potential may be applied to at least one of the one or more parts to accelerate the electrons towards the portion of the wall 121 , particularly toward the inner tube part 151 of the wall 121. In particular, the wall 121 may be connected to a ground potential. The inner tube part 151 provided on the ground potential may function as an anode, onto which the electrons are accelerated.

[0057] In an embodiment, which may be combined with other embodiments described herein, the electron bombardment heating 140 may comprise one or more separate anodes, e.g., anodes that are not a part of the wall 121. In such an example, the electron bombardment heating 140 may be configured to set the heating element 133 on the first electrical potential and / or to set the one or more anodes on the second electrical potential to accelerate electrons towards the portion of the wall 121. The one or more anodes may be configured such that the portion ofAMAT#44023862WO01 - 14 - 34882 P-WO the wall 121 (e.g., the inner tube part 151 ) receives at least a portion of the accelerated electrons.

[0058] In an embodiment, which may be combined with other embodiments described herein, the electron bombardment heating 140 may be configured to apply an electrical potential difference between the heating element 133 and the portion of the wall 121 (e.g., a portion of the inner tube part 151 ) to accelerate the electrons towards the portion of the wall 121 (e.g., a portion of the inner tube part 151 ). The electric potential difference between the heating element 133 and the portion of the wall 121 may correspond to the electrical potential difference between the first electrical potential at the heating element 133 and the second electrical potential of the portion of the wall 121 .

[0059] The electron bombardment heating 140 may thus be configured to control the heating via the electrical potential difference between the heating element 133 and the portion of the wall 121. Typically, the heating of the electron bombardment heating 140 may be proportionate to the applied electrical potential difference between the heating element 133 and the wall 121 . For example, if a higher heating by the electron bombardment heating 140 is to be provided, the electrical potential difference between the heating element 133 and the wall 121 may be increased. If a lower heating by the electron bombardment heating 140 is to be provided, the electrical potential difference between the heating element 133 and the wall 121 may be decreased.

[0060] In an embodiment, which may be combined with other embodiments described herein, the heating assembly may comprise a voltage source 141 , particularly a high voltage source, electrically coupled to the heating element 133 and to the wall 121 , wherein the voltage source 141 may be configured to apply an electrical potential difference between the heating element 133 and the portion of the wall 121 (e.g. between the heating element 133 and the inner tube part 151 ).

[0061] The voltage source 141 may be a voltage source capable of providing voltages between 500 V and 10 kV, particularly voltages between 1 kV and 5 kV. The voltages source 141 may be a DC power supply, particularly a DC power supplyAMAT#44023862WO01 - 15 - 34882 P-WO capable of providing absolute values of DC voltages between 500 V and 10 kV. The voltages source 141 may be a DC high voltage source.

[0062] For example, the distribution pipe 120 may comprise a port 143 where the voltage source 141 may be physically coupled to. For example, an electrical connector may be connected to the port 143 and the voltage source 141 such that the voltage source 141 may set the portion of the wall 121 onto a desired electrical potential for the electron bombardment heating (as described herein).

[0063] In some embodiments, the wall 121 of the distribution pipe may be set on a ground potential at the port 143, and a high-voltage terminal of the voltage source 141 may be directly or indirectly electrically connected to the heating element 133 for setting the heating element 133 on a negative voltage relative to the ground voltage of the wall 112.

[0064] In an embodiment, the port 143 may be provided at the inner tube part 151 of the wall 121. In other embodiments, the port 143 may be integrated at the outer tube part 152 of the wall 121 , e.g., when the inner and outer tube parts are electrically connected.

[0065] In an embodiment, the heating assembly may comprise a power source 131 , the power source 131 being electrically coupled to the heating element 133 such that an electrical current can be applied to the heating element 133 for causing the radiation heating by the heating element 133 (as described herein). The electrical coupling between the power source 131 and the heating element may also comprise an indirect coupling via one or more other electrical components which may transfer the power of the power source to the heating element 133.

[0066] In an embodiment, the voltage source 141 may be electrically connected to the power source 131 . The voltage source 141 may provide an electrical potential to the power source 131 such that the power source 131 can set the heating element 133 onto the electrical potential provided by the voltage source 141. In such a configuration, the electrical potential difference between the heating element 133 and the portion of the wall 121 for electron bombardment heating can be provided.AMAT#44023862WO01 - 16 - 34882P-WO

[0067] In an embodiment, the heating element 133 may comprise connectors for connecting to the power source 131. In some embodiments, the voltage source 141 may be electrically connected to one of the connectors. The voltage source 141 may thus provide an electrical potential to the heating element 133. In such a configuration, the electrical potential difference between the heating element 133 and the wall 121 for electron bombardment heating can be provided.

[0068] In an embodiment, which may be combined with other embodiments described herein, the portion of the wall 121 may be on a reference potential 142, particularly on ground, and the voltage source 141 may be configured to set the heating element 133 onto a negative voltage offset with respect to the reference potential, particularly a negative voltage offset of 1000 V or more. Typically, it is beneficial to keep electrically passive components on a ground potential to avoid electrical discharge between components or electrical noise. According to the embodiment, the heating element 133 may be set onto a negative voltage offset with respect to the reference potential, while keeping the portion of the wall 121 on the established reference potential (e.g., on the established ground potential). This may ensure that a voltage difference between the heating element 133 and the wall 121 can be set for electron acceleration onto the portion of the wall 121 .

[0069] For example, the voltage source 141 may be configured to set the heating element 133 onto a negative voltage offset with respect to the reference potential, particularly a negative voltage offset of 1000 V or more.

[0070] In an embodiment, which may be combined with other embodiments described herein, the heating element 133 may comprise a first electrical connector 138 and a second electrical connector 139, the first electrical connector 138 and second electrical connector 139 configured to be connected to output terminals of the power source 131. The first and second electrical connectors may be provided at a same longitudinal end of the distribution pipe 120.

[0071] In an embodiment, which may be combined with other embodiments described herein, the heating assembly may comprise the power source 131 connected to the heating element 133 for sending a high current through the heatingAMAT#44023862WO01 - 17 - 34882 P-WO element, particularly a current of 100 A or more. For example, the power source 131 may comprise a high current source. In an example, the current may be in the range between 100 A and 300 A, e.g., if a graphite heat emitter is used as the heating element. In some embodiments, the high current source may be configured to provide a current of 300 A or more, 400 A or more, or even 500 A or more, that flows through the heat emitter.

[0072] In an embodiment, which may be combined with other embodiments described herein, the heating element 133 may extend inside the distribution pipe 120 along a length direction of the distribution pipe, particularly over at least 50% or at least 80% of a length of the distribution pipe. The extension of the heating element 133 within the distribution pipe 120 may enable a degree of shaping the heat profile within the vapor propagation volume 122 to adapt the heating of the evaporated material for deposition.

[0073] In an embodiment, which may be combined with other embodiments described herein, the heating assembly may be configured to heat the vapor propagation volume 122 to a temperature of at least 500°C, at least 1000°C, particularly 1200°C or 1500°C or more.

[0074] In an embodiment, which may be combined with other embodiments described herein, the evaporation source 100 may be a metal evaporation source configured to deposit a metal on the substrate, particularly a silver evaporation source, or a magnesium or aluminum evaporation source.

[0075] FIG. 2 shows a schematic heating concept of an evaporation source according to embodiments described herein. Particularly, FIG. 2 shows the electron bombardment heating 140 of the heating assembly. The voltage source 141 of the electron bombardment heating 140 may be coupled to the portion of the wall 121 (e.g., a portion of the inner tube part 151 ) and to the heating element 133.

[0076] During radiation heating, electrons 135 may be released from the heating element 133, e.g., due to thermionic emission. The voltage source 141 may be configured to set an electrical potential difference (i.e. a voltage difference) between the heating element 133 and the portion of the wall 121 such that electrons 135 areAMAT#44023862WO01 - 18 - 34882 P-WO accelerated from the heating element 133 towards the portion of the wall 121. In some examples, the electrons 135 may be accelerated through an inner tube volume 153 that is formed within the inner tube part. The electrons may impinge on the inner tube part to heat the inner tube part via electron bombardment.

[0077] As described, the distribution pipe 120 comprises a plurality of nozzles 123. The nozzles may extend along an evaporation direction. The evaporation direction can be essentially horizontal. The distribution pipe can be a vapor distribution showerhead having a plurality of nozzles, particularly one or more rows of nozzles. In particular, the vapor distribution showerhead can be a linear vapor distribution showerhead providing a linear source for e.g. metallic vapor. According to an embodiment, the adjacent nozzles of the row of nozzles may have a distance to each other of 50 mm or less, or 25 mm or less. Further, the opening of a nozzle can have a cross-section of 1 mm to 6 mm in diameter.

[0078] According to some embodiments, which can be combined with other embodiments described herein, the length of the distribution pipe 120 can be 1 m or above, for example 1 .5 m or above.

[0079] Embodiments described herein particularly relate to deposition of materials, e.g. for display manufacturing on large area substrates. According to some embodiments, large area substrates or substrate carriers supporting one or more substrates may have a size of 0.5 m2or larger, particularly of 1 m2or larger. For instance, the deposition system may be adapted for processing large area substrates, such as substrates of GEN 4.5, which corresponds to about 0.67 m2of substrate (0.73 m x 0.92 m), GEN 5, which corresponds to approximately 1.4 m2 (1.1 m x 1 .3 m), GEN 6, which corresponds to approximately 2.7 m2 (1 .5 m x about 1.8 m), GEN 7.5, which corresponds to approximately 4.29 m2 (1.95 m x 2.2 m), GEN 8.5, which corresponds to approximately 5.7 m2 (2.2 m x 2.5 m), or even GEN 10, which corresponds to approximately 8.7 m2 (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can be implemented. According to yet further implementations, half sizes of the above- mentioned substrate generations can be processed. Alternatively or additionally,AMAT#44023862WO01 - 19 - 34882 P-WO semiconductor wafers may be processed and coated in deposition systems according to the present disclosure.

[0080] In an embodiment, which may be combined with other embodiments described herein, the heating element 133 may comprise a rod assembly heating element 300. The rod assembly heating element 300 may include a heating rod and a plurality of outer rods distributed around the heating rod and electrically connected to the heating rod. The rod assembly heating element 300 may form the heating element 133 of the heating assembly as described herein. In some embodiments, the rod assembly heating element 300 may be arranged in an inner tube part of the distribution pipe, as described herein, to protect the rod assembly heating element 300 from the environment of the vapor propagation volume 122, particularly of the evaporated material in the vapor propagation volume 122. A protective cage for the heating rod can be provided by the outer rods.

[0081] FIG. 3 shows a schematic view of a rod assembly heating element 300 according to embodiments of the present disclosure. The rod assembly heating element 300 includes a heating rod 210 that acts as a heat emitter. The heating rod 210 may have first electrical connector 212, which can be coupled to the power source 131 . A plurality of outer rods 220 are provided. At least one outer rod of the plurality of outer rods may have a second electrical connector 222, which can be coupled to the power source 131. In some embodiments, a first connection plate 240 provides an electrical connection between the heating rod 210 and the at least one outer rod. Accordingly, a series circuit of the heating rod and at least one outer rod is provided.

[0082] As shown in FIG. 3, a second connection plate 242 can be provided, particularly at a side of the plurality of outer rods 220, which is opposite the side of the first connection plate 240. The first connection plate and the second connection plate can provide an electrical parallel circuit of the outer rods. According to some embodiments, which can be combined with other embodiments described herein, a rod assembly heating element 300 can include a second connection plate, wherein the first connection plate and the second connection plate provide a parallel electrical circuit for the plurality of outer rods.AMAT#44023862WO01 - 20 - 34882 P-WO

[0083] FIG. 4 shows an electrical equivalent circuit diagram of a rod assembly heating element 300 as shown in FIG. 3. The power source 131 may be connected with two resistors in a series circuit. The first resistor 310 corresponds to the heating rod and the second resistor 320 corresponds to one or more of the outer rods, particularly to outer rods connected in parallel. For example, all outer rods can be connected in parallel. The outer rods can be connected in series with the heating rod 210.

[0084] Coming back to FIG. 3, the rod assembly heating element 300 may comprise a first insulator 262. The first insulator can electrically insulate the heater from the inner tube part of the distribution pipe. Further, the first insulator can be shaped to position the heater within the inner tube part of the distribution pipe. The first insulator 262 is adjacent the first connection plate 240 and can be coupled to the first connection plate. A second insulator 264 can be provided at or adjacent an opposite end of the heater. For example, the second insulator can be provided adjacent the second connection plate 242 and can be coupled to the second connection plate. The first insulator and the second insulator can be made of ceramic material or can include a ceramic material. Particularly, high temperature ceramic material can be provided. For example, the ceramic material can be Pyrolytic Boron Nitride (PBN). The ceramic material may be selected from a group comprising, PBN, Shapal (AIN), AI2O3, Sintered Born Nitride (SBN) or combinations thereof.

[0085] FIG. 3 shows enforcement rings 250. The enforcement rings 250 can be coupled to the outer rods 220. The enforcement rings are configured to securely position the outer rods 220. A protective cage can be provided by the outer rods. The enforcement rings can be distributed along the length of the outer rods. Since the electrical potential of the outer rods is similar or identical along positions of enforcement rings along the length direction, there is essentially no current flowing over the enforcement rings, i.e. the enforcement rings are electrically inactive. The heating rod 210 can be protected by an outer, robust cage, the cage being, for example, provided by the outer rods and the enforcement rings. Embodiments of the present disclosure reduce or eliminate the risk of breakage of the heating rod, e.g. during heater handling, such as assembling the heater in the distribution pipe.AMAT#44023862WO01 - 21 - 34882 P-WO

[0086] FIG. 5 shows a schematic cross-sectional view of a heating element according to embodiments described herein, particularly of a rod assembly heating element 300 as shown in FIG. 3.

[0087] For the rod assembly heating element 300 of Fig. 5, the heating rod 410 and a plurality of outer rods 220 are provided above the first insulator 262. One enforcement ring 250 is exemplarily shown. According to some embodiments, which can be combined with other embodiments described herein, the heating rod 410 can include carbon, or can consist of graphite. The heating rod may be provided as a graphite heater. The plurality of outer rods can include, or can consist of, a material selected from the group of molybdenum, tungsten, tantalum, niobium or an alloy of molybdenum, tungsten, niobium or tantalum. An electrical series connection between the heating rod and the outer rods can be provided by the first connection plate (not shown in FIG. 5), so that the current can flow back to the power source.

[0088] A gap 401 can be provided between the heating rod and the outer rods. For example, the gap can be several millimeters, such as 2 mm to 10 mm. The gap allows for a distance to prevent arcing when power is provided to the heating element. According to some embodiments, which can be combined with other embodiments described herein, the diameter of the heating element, i.e. the maximum diameter of the heating element, such as the diameter of the first insulator or the second insulator can be from about 20 mm to about 70 mm. Particularly, since an electrical circuit is provided by the heating rod and the outer rods (non-slitted graphite), the diameter of the heating element and, thus, an inner diameter of the innertube of evaporation source can be reduced to be about 20 mm to 40 mm. Further, the protection by the outer rods, i.e. the protection of the heating rod allows for reduction of the diameter of the heater.

[0089] The herein described embodiments and examples of the rod assembly heating element 300 may be combined with other embodiments and examples of the herein described heating element 133.

[0090] FIG. 6 shows a schematic view of a deposition system with an evaporation source according to embodiments of the present disclosure.AMAT#44023862WO01 - 22 - 34882 P-WO

[0091] The deposition system 6000 comprises a deposition chamber 6001 ; an evaporation source 601 according to an embodiment of the herein described evaporation source, the evaporation source 601 being in the deposition chamber; a substrate transportation system 6013 configured for moving the substrate 60 and the evaporation source 601 relative to each other for coating the substrate with the material.

[0092] Particularly, FIG. 6 shows a deposition system 6000 for coating substrates with a layer stack according to embodiments. The deposition system 6000 includes a deposition chamber 6001 that houses an evaporation source 100, and optionally one or more further vacuum chambers that may house one or more further evaporation sources, e.g., a second evaporation source 602 and / or a third evaporation source 603. The evaporation source 100 may comprise the evaporation source 100 according to the present disclosure. The evaporation sources may be configured to coat vertically or essentially vertically oriented substrates that are transported past the evaporation sources along a substrate transportation track T1 . However, the present disclosure is not limited to vertically oriented substrates. A plurality of materials, that may include one or more metals and / or one or more organic materials, can be deposited in succession onto the substrate in order to provide a layer stack on the substrate, e.g., an OLED layer stack. For example, the deposition system 6000 may include five, ten or more evaporation sources for coating the substrate with a plurality of layers. An in-line deposition system may be provided.

[0093] A "vacuum chamber" or “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 approximately 10-8 mbar, particularly between 10-5 mbar and 10-7 mbar.

[0094] The deposition system 6000 includes a substrate transportation track T1 configured to move a substrate 60 along a substrate transport path in a transport direction T, past the evaporation source 100 and past the optional furtherAMAT#44023862WO01 - 23 - 34882 P-WO evaporation sources. The substrate transportation track T1 may extend at least partially through the deposition chamber 6001 and through the optional further deposition chambers and may include a substrate transportation system 6013 configured for substrate transport, e.g., a roller transportation system, one or more linear motors and / or a magnetic levitation system suitable for moving a plurality of substrates relative to, and past, the evaporation sources. The substrate 60 may be carried by a substrate carrier 6020 during the transport and / or deposition in the deposition system.

[0095] A substrate carrier 6020 is a carrying device configured to carry one or more substrates through the deposition system 6000. For example, a substrate carrier 6020 may comprise a holding section for holding the substrate, e.g., in an essentially vertical orientation, particularly a chucking device, such as an electrostatic chuck. The substrate carrier 6020 may further be configured to interact with the substrate transportation track T1 for moving the substrate past the evaporation source(s). For example, the substrate carrier may include one or more magnetic sections configured to interact with a magnetic levitation system and / or a linear motor of the substrate transportation track T 1 .

[0096] Accordingly, an in-line system is provided that allows the deposition of a plurality of layers on a substrate in succession, while the substrate is moved past a plurality of evaporation sources through the deposition system 6000.

[0097] One or more evaporation sources of the deposition system can be configured as evaporation sources with a heating assembly for heating the distribution pipe, as described herein. In particular, evaporation sources for metal deposition may be provided with a heating assembly as described herein, in order to ensure high temperatures for metal evaporation and deposition. In some embodiments, the evaporation source may be a metal source configured to deposit a silver layer or a silver-containing layer on the substrate, or alternatively to deposit a magnesium-containing or aluminum-containing layer on the substrate.

[0098] FIG. 7 shows a flowchart illustrating a method of depositing a material according to embodiments of the present disclosure.AMAT#44023862WO01 - 24 - 34882 P-WO

[0099] The method is a method for depositing a material on a substrate, the method comprising: evaporating 701 the material in an evaporation crucible; guiding 702 the evaporated material into a vapor propagation volume of a distribution pipe defined by a wall; heating 703 the distribution pipe, comprising: radiating heat from a heating element that is at least partially arranged in the distribution pipe; and accelerating electrons released from the heating element towards at least a portion of the wall; and directing 704 the evaporated material from the vapor propagation volume onto a substrate with a plurality of nozzles of the distribution pipe.

[0100] Even if not explicitly expressed as method operations, the herein described embodiments and examples regarding the evaporation source may accordingly be applied to the herein described method (and vice versa).

[0101] In an embodiment, which may be combined with other embodiments described herein, the method may be performed with the evaporation source and / or with a deposition system as described herein.

[0102] In an embodiment, the wall may comprise an inner tube part 151 and an outer tube part 152, the vapor propagation volume 122 being at least partially formed between the inner tube part and the outer tube part. The heating element 133 can be at least partially surrounded by the inner tube part or provided inside the inner tube part. In particular, the heating element may be provided in an inner volume of the inner tube part, the inner volume being separated by the vapor propagation volume by the inner tube part of the wall 121 .

[0103] In an embodiment, the wall of the distribution pipe surrounding the vapor propagation volume may be conductive. In particular, the inner tube part 151 and / or the outer tube part 152 of the wall may be conductive. The inner tube part and the outer tube part may be electrically connected.

[0104] In an embodiment, which can be combined with other embodiments described herein, the method may further comprise: setting the heating element 133 onto a first electrical potential and / or setting the portion of the wall 121 onto a second electrical potential such that electrons released from the heating element areAMAT#44023862WO01 - 25 - 34882 P-WO accelerated toward the portion of the wall 121 (e.g., towards the inner tube part 151 of the wall 121 ). The impinging electrons contribute to the heating of the wall.

[0105] In an embodiment, the method may comprise: setting a voltage difference between the heating element 133 and the portion of the wall 121 such that electrons are accelerated onto the portion of the wall 121 (e.g., towards the inner tube part 151 of the wall 121 ).

[0106] In an embodiment, the method may further comprise: setting the heating element onto a voltage offset to set a voltage difference between the heating element 133 and the portion of the wall 121 such that the electrons released from the heating element are accelerated onto the portion of the wall.

[0107] In an embodiment, the method may comprise setting a voltage difference between the heating element 133 and the portion of the wall 121 of at least 1000 V to accelerate the electrons onto the portion of the wall 121 .

[0108] In an embodiment, which can be combined with other embodiments described herein, the method may further comprise: setting the portion of the wall on a reference potential, particularly on ground; and setting the heating element 133 on a negative voltage offset with respect to the reference potential of 1000 V or more.

[0109] In an embodiment, which can be combined with other embodiments described herein, the method may further comprise: sending a current of 100 A or more, particularly 200 A or more, through a heat emitter (e.g., a high-temperature infrared emitter, as described herein) of the heating element.

[0110] The heat emitter of the heating element may be a carbon-containing heat emitter or may comprise a carbon-containing heat emitter, such as a graphite heater. The heat emitter of the heating element may comprise another material, such as tantalum or tungsten.

[0111] In an embodiment, which can be combined with other embodiments described herein, the heating element may be operated to provide a first heating power via heat radiation and a second heating power via electron bombardment onAMAT#44023862WO01 - 26 - 34882 P-WO the wall portion (by applying an appropriate electron acceleration voltage), with the first heating power and the second heating power resulting in a total heating power, wherein the second heating power corresponds to at least 10 % of the total heating power, particularly to at least 20% or more, 30% or more, or even about 50% of the total heating power.

[0112] For example, the radiating of the heat (e.g., by heat radiation from the heating element) may be operated to provide the first heating power P1 , and the accelerating of the electrons (e.g., by the electron bombardment heating 140) may be operated to provide the second heating power P2. The total heating power P0 may be represented as the first heating power P1 added to the second heating power P2 (i.e.: P0 = P1 + P2). In this example, the second heating power P2 may correspond to at least 10 % of the total heating power P0 (i.e.: P2 > 0.1 ■ P0).

[0113] As described herein, due to the heating by accelerating the electrons onto the wall 121 (e.g., towards the inner tube part 151 ), the heating via the radiation heating may be reduced, which may reduce electrical discharging effects or the effect of electrical shorts (as described herein).

[0114] To illustrate an example according to the present disclosure, a total heating power of 14 kW may be provided (P0 = 14 kW) by the heating assembly. The first heating power P1 may be chosen to amount to about 50 % of the total heating power (P1 = 7 kW), wherein the second heating power P2 may be chosen to amount to 50 % of the total heating power (P2 = 7 kW).

[0115] In an embodiment, which can be combined with other embodiments described herein, the total heating power may be in the range between 10 kW to 20 kW, particularly between 10 kW to 15 kW. In some embodiments, the total heating power may be in the range between 15 kW and 20 kW.

[0116] In an embodiment, which can be combined with other embodiments described herein, a first heating power of 5 kW or more and 10 kW or less may be provided by heat radiation from the heat element, and / or a second heating power of 5 kW or more and 10 kW or less may be provided by electron impingement on the wall portion by the electron bombardment heating.AMAT#44023862WO01 - 27 - 34882 P-WO

[0117] In an embodiment, which can be combined with other embodiments described herein, the vapor propagation volume may be heated to a temperature of at least 1000°C. However, other temperatures may also be possible (e.g., a temperature of at least 500°C or a temperature of at least 1500° C).

[0118] In an embodiment, which can be combined with other embodiments described herein, the material is a metal, particularly silver, and a metal layer is deposited on the substrate, particularly a cathode layer of an OLED layer stack.

[0119] While the foregoing is directed to embodiments of the invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

Claims

AMAT#44023862WO01 - 28 - 34882 P-WOWhat is claimed1. An evaporation source (100) for depositing a material on a substrate, comprising: an evaporation crucible (110) to evaporate the material; a distribution pipe (120) comprising: a wall (121 ) that defines a vapor propagation volume (122) for receiving evaporated material from the evaporation crucible (110); and a plurality of nozzles (123) for directing the evaporated material onto the substrate; and a heating assembly for the distribution pipe (120), comprising a heating element (133) arranged at least partially in the distribution pipe (120) and configured to radiate heat, the heating assembly configured to accelerate electrons (135) from the heating element towards at least a portion of the wall (121 ).

2. The evaporation source of claim 1 , wherein: the wall comprises an inner tube part (151 ) and an outer tube part (152), the vapor propagation volume (122) being at least partially formed between the inner tube part and the outer tube part.

3. The evaporation source of claim 2, wherein the heating assembly is configured to accelerate electrons (135) from the heating element (133) towards at least a portion of the inner tube part (151 ) of the wall (121 ).

4. The evaporation source of any of claims 1 to 3, the heating assembly configured to set the heating element on a first electrical potential and / or to set the portion of the wall (121 ) on a second electrical potential to accelerate electrons towards the portion of the wall (121 ).

5. The evaporation source of any of claims 1 to 4, the heating assembly comprising a voltage source (141 ), particularly a high voltage source, electrically coupled toAMAT#44023862WO01 - 29 - 34882 P-WO the heating element and to the portion of the wall (121 ) and configured to apply an electrical potential difference between the heating element (133) and the portion of the wall.

6. The evaporation source of claim 5, wherein the portion of the wall (121 ) is on a reference potential (142), particularly on ground, and the voltage source (141 ) is configured to set the heating element (133) onto a negative voltage offset with respect to the reference potential, particularly a voltage offset of 1000 V or more.

7. The evaporation source of any of claims 1 to 6, wherein the heating element (133) comprises a high-temperature infrared emitter, particularly a graphite heat emitter or a tungsten heat emitter.

8. The evaporation source of any of claims 1 to 7, wherein the heating element (133) comprises a first electrical connector (138) and a second electrical connector (139) configured to be connected to output terminals of a power source (131 ), the first and second electrical connectors being at a same longitudinal end of the distribution pipe.

9. The evaporation source of any of claims 1 to 8, wherein the heating assembly further comprises a power source (131 ) connected to the heating element (133) for sending a high current through the heating element, particularly a current of 100 A or more.

10. The evaporation source of any of claims 1 to 9, wherein the heating assembly is configured to heat the vapor propagation volume (122) to a temperature of at least 1000°C.11 . The evaporation source of any of claims 1 to 10, wherein the evaporation source (100) is a metal evaporation source configured to deposit a metal on the substrate, particularly a silver evaporation source.

12. The evaporation source of any of claims 1 to 11 , wherein the heating element (133) comprises a heating rod and a plurality of outer rods distributed around the heating rod and electrically connected to the heating rod.AMAT#44023862WO01 - 30 - 34882 P-WO13. A deposition system (6000), comprising: a deposition chamber (6001 ); an evaporation source (601 ) according to any of claims 1 to 12 in the deposition chamber (6001 ); and a substrate transportation system (6013) configured for moving the substrate (60) and the evaporation source (601 ) relative to each other for coating the substrate with the material.

14. A method (700) for depositing a material on a substrate, the method comprising: evaporating (701 ) the material in an evaporation crucible; guiding (702) the evaporated material into a vapor propagation volume of a distribution pipe defined by a wall; heating (703) the distribution pipe, comprising: radiating heat from a heating element (133) that is at least partially arranged in the distribution pipe; and accelerating electrons (135) released from the heating element (133) towards at least a portion of the wall (121 ); and directing (704) the evaporated material from the vapor propagation volume onto a substrate with a plurality of nozzles of the distribution pipe.

15. The method of claim 14, further comprising: setting the heating element (133) onto a first electrical potential and / or setting the portion of the wall onto a second electrical potential such that electrons released from the heating element are accelerated towards the portion of the wall.

16. The method of claim 15, further comprising:AMAT#44023862WO01 - 31 - 34882 P-WO setting the portion of the wall on a reference potential, particularly on ground; and setting the heating element on a negative voltage offset with respect to the reference potential of 1000 V or more.

17. The method of any of claims 14 to 16, further comprising: sending a current of 50 A or more, particularly 200 A or more, through the heating element, particularly wherein the heating element comprises a carbon- containing heat emitter.

18. The method of any of claim 14 to 17, wherein the radiating of heat from the heating element is operated to provide a first heating power, and the accelerating of electrons is operated to provide a second heating power, with the first heating power and the second heating power resulting in a total heating power, wherein the second heating power corresponds to at least 10 % of the total heating power.

19. The method of any of claims 14 to 18, wherein the vapor propagation volume is heated to a temperature of at least 1000°C.

20. The method of any of claims 14 to 19, wherein the material is a metal, and the metal layer is deposited onto the substrate, particularly to form a layer of an OLED layer stack.

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