Heater for an evaporation source; evaporation source, evaporation source array, evaporation system and method of manufactrung a layer stack

Abstract

A heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source is described. The heater includes a heating rod having a first electrical connector configured to be coupled to a power source; a plurality of outer rods distributed around the heating rod, at least a first outer rod of the plurality of outer rods having a second electrical connector configured to be coupled to the power source; and a first connection plate providing a series circuit of the heating rod and the at least first outer rod. Further described is an evaporation source with such a heater, as well as an evaporation source array, an evaporation system, and an evaporation method.

Description

AMAT#44024237 - 1 - 34883P-WOHEATER FOR AN EVAPORATION SOURCE; EVAPORATION SOURCE, EVAPORATION SOURCE ARRAY, EVAPORATION SYSTEM AND METHOD OF MAN U FACTRUNG A LAYER STACKTECHNICAL FIELD OF THE INVENTION

[0001] Embodiments of the present disclosure relate to evaporation of materials and heating of a distribution pipe of an evaporator. For example, embodiments relate to evaporation at high temperatures, e.g. for deposition of metallic and non- metallic materials. Embodiments relate to evaporation for, e.g., OLED manufacturing. In particular, some embodiments relate to evaporation of metals and metal alloys. Specifically, embodiments relate to a heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source, an evaporation source, an evaporation source array, an evaporation system, and a method of manufacturing a layer stack for a device.BACKGROUND OF THE INVENTION

[0002] 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. Since OLEDs emit light directly without involving backlight and color filters, the color gamut and viewing angles possible with OLED displays are greater than those of traditional LCD displays. Furthermore, OLEDs can be manufactured on flexible substrates, and accordingly, they can be utilized in a variety of applications. 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.AMAT#44024237 - 2 - 34883P-WO

[0003] Organic materials and metallic materials are deposited on a substrate in vacuum processing chambers for OLED manufacturing. Metallic and non-metallic materials are employed as, for example, electrode materials or electron injection layer (EIL) materials. The materials to be deposited are evaporated using an evaporation source arrangement, and the evaporated materials are deposited onto a substrate through nozzles. Metallic materials are typically evaporated in an evaporation source at a temperature of 500°C or above, or of 1 ,500°C or above. Organic materials are typically evaporated in an evaporation source arrangement at temperatures between 250°C and 500°C.

[0004] Metallic and organic evaporators can be used for the production of organic light-emitting diodes (OLED). Also, other applications utilize evaporators for depositing metal or organic layers, for example, onto large area substrates. For example, co-evaporation of two or more metals or metal alloys can be provided. An OLED display, for example, may include a plurality of layers of organic material situated between two electrodes that are deposited onto a substrate. One of the electrodes can include a transparent conductive layer such as indium tin oxide (ITO) or other transparent conductive oxide materials (TOO). The second electrode can include a metal or a metal alloy.

[0005] Metallic evaporators are tools used for the production of organic lightemitting diodes (OLED). In light of the high temperature of a metal evaporation, thermal load on the substrates and / or other components during manufacturing can be high. Further, reduced power consumption and / or reduced risk of failure of fragile materials is beneficial, particularly, when upscaling to larger substrate generations for display manufacturing, one or more of the considerations like robustness and reliability, lifetime, handling, risk of breakage, costs, etc. provide increasing challenges.

[0006] Accordingly, an improved heater, an improved evaporation source, an improved evaporation source array, an improved evaporation system, and an improved method of manufacturing a layer stack are beneficial.AMAT#44024237 - 3 - 34883P-WOSUMMARY OF THE INVENTION

[0007] In light of the above, a heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source, an evaporation source, an evaporation source array, an evaporation system, and a method of manufacturing a layer stack for a device are provided. Further advantages, features, aspects and details are evident from the dependent claims, the description and the drawings.

[0008] The invention is set forth in the appended set of claims.

[0009] According to a first aspect, a heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source is provided. The heater includes a heating rod having a first electrical connector configured to be coupled to a power source; a plurality of outer rods distributed around the heating rod, at least a first outer rod of the plurality of outer rods having a second electrical connector configured to be coupled to the power source; and a first connection plate providing a series circuit of the heating rod and the at least first outer rod.

[0010] According to a second aspect, an evaporation source is provided, including: a distribution pipe with one or more outlets provided along a length of the distribution pipe, the distribution pipe including an opening configured to be in fluid communication with an evaporation crucible. The distribution pipe includes an inner tube providing a first enclosure, and an outer tube providing a second enclosure between the outer tube and the inner tube. The evaporation source further includes a heater according to any of the embodiments described herein provided in the first enclosure.

[0011] According to a third aspect, an evaporation source array, particularly for metals or metal alloys, is provided, including a first evaporation source according to any of the embodiments described herein and at least a second evaporation source according to any of the embodiments described herein. At least a first outlet of the one or more outlets of the first evaporation source and at least a second outlet of the one or more outlets of the second evaporation source have a distance of 200 mm or less.AMAT#44024237 - 4 - 34883P-WO

[0012] According to a fourth aspect, an evaporation system is provided, including: one or more vacuum chambers; a substrate transport assembly configured to transport a substrate through the one or more vacuum chambers; and one or more evaporation source arrays as described herein or one or more evaporation sources as described herein, wherein the substrate is transported past the one or more evaporation source arrays or the one or more evaporation sources for deposition materials on the substrate.

[0013] According to a fifth aspect, a method of manufacturing a layer stack or a layer for a device is provided. The method includes: evaporating a deposition material in an evaporation crucible; guiding the deposition material from the evaporation crucible into a distribution pipe; heating the distribution pipe with a heater having a heating rod and a plurality of outer rods by providing a current through the heating rod and at least a first outer rod of the plurality of outer rods; and guiding the deposition material through one or more outlets onto a substrate of the device to deposit a layer of the deposition material.

[0014] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method step. These method steps 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 present disclosure are also directed at methods by which the described apparatus operates. It includes method steps for carrying out functions of the apparatus.BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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:AMAT#44024237 - 5 - 34883P-WO

[0016] FIGS. 1A and 1 B show schematic views of an evaporation source according to embodiments described herein and being configured for a heater according to embodiments of the present disclosure;

[0017] FIG. 2 shows a schematic view of a heater according to embodiments of the present disclosure;

[0018] FIG. 3 shows an electrical equivalent circuit diagram of the heater according to embodiments of the present disclosure;

[0019] FIG. 4 shows a schematic cross-sectional view of a heater according to embodiments described herein;

[0020] FIG. 5 shows a schematic cross-sectional view of a further heater according to embodiments described herein;

[0021] FIG. 6 shows a schematic view of a heater according to embodiments of the present disclosure and including an electron bombardment mechanism;

[0022] FIG. 7 shows a flowchart illustrating a method of manufacturing a layer stack according to embodiments of the present disclosure;

[0023] FIG. 8 shows a schematic view of a vacuum deposition system with an evaporation source arrangement according to embodiments of the present disclosure; and

[0024] FIG. 9 illustrates a substrate coating method according to embodiments.DETAILED DESCRIPTION OF EMBODIMENTS

[0025] 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 embodiments are described. Each example is provided by way of explanation of the invention andAMAT#44024237 - 6 - 34883P-WO 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.

[0026] Embodiments of the present disclosure relate to a heater configured for an evaporation source, and particularly to an inner heater. An inner heater provided within a volume to be heated utilizes more of the heat energy as compared to outer heaters, because all of the heat radiation is utilized. Particularly for high temperature evaporation, such as for metal materials or metal alloy materials, heating to temperatures above 1000°C is challenging. According to some embodiments, heaters for an evaporation source for organic materials may also benefit, since an improved heater can provide better temperature stability. For high temperature evaporation, slitted graphite heaters can be used. However, the brittle graphite material can be sensitive to heat up breakage, and particularly at operation powers of above, for example, 10 kW, severe damage may occur.

[0027] Embodiments of the present disclosure provide an improved heater concept. An inner heater with higher robustness can be provided. This can be particularly advantageous for scaling up to larger substrate generations, i.e. larger display substrate generations.

[0028] According to an embodiment, a heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source is provided. The heater includes a heating rod having a first electrical connector configured to be coupled to a power source and a plurality of outer rods distributed around the heating rod, wherein at least a first outer rod of the plurality of outer rods having a second electrical connector configured to be coupled to the power source. The heater further includes a first connection plate providing a series circuit of the heating rod and the at least first outer rod. According to some embodiments, which can be combined with other embodiments described herein, the plurality of outer rods surround the heating rod such that the plurality of outer rods are configured to provide a protection cage for the heating rod. Accordingly, a heater according to embodiments of the present disclosure is less sensitive to heater breakage.AMAT#44024237 - 7 - 34883P-WO

[0029] FIG. 1A shows a schematic view an evaporation source according to embodiments described herein. FIG. 1 B shows a schematic view of another evaporation source, wherein portions of an outer tube are omitted to see inside the evaporation source. An evaporation source can include a distribution pipe 130 and an evaporation crucible 140. The evaporation crucible 140 can be fixed to a first end of the distribution pipe (see, e.g. FIG. 1A). Alternatively, the crucible can be coupled to the distribution pipe along the length of the distribution pipe, e.g. close to the center or in the center of the distribution pipe (see, e.g. FIG. 1 B).

[0030] At the second end of the distribution pipe 130 opposing the first end, a closure plate 133 can be fixed, e.g. in a non-detachable manner e.g. by welding. For embodiments as shown in FIG. 1 B, a closure plate may also be provided at the first end. One or more outlets 134 direct the evaporated material, e.g. metal vapor or metal alloy vapor to a substrate. According to embodiments, which can be combined with other embodiments described herein, an enclosure, i.e. a hollow space or volume, in which the deposition material vapor can be provided, is arranged between an outer tube of the distribution pipe and an inner tube within the distribution pipe.

[0031] According to an embodiment, the distribution pipe 130, i.e. the vapor distribution pipe, can be an elongated pipe with an inner tube 136 and an outer tube 138 (as, e.g. partially shown in FIG. 1 B). The inner tube 136 can be formed as a cylinder. The cylinder can have one closed end and one open end. The inner tube 136, the outer tube 138, and the closure plate 133 can, for example, be welded to form one single piece. A heater 120 according to embodiments of the present disclosure, can be provided within the inner tube as indicated by the arrow in FIG. 1A.

[0032] According to embodiments, which can be combined with other embodiments described herein, the distribution pipe 130 comprises an outer tube 138 and an inner tube 136. The outer tube and the inner tube of the distribution pipe may be joined together in a non-detachable way e.g. by welding or any other appropriate means to form one single piece without slits or gaps. Further, the heater 120 is arranged inside the inner tube 136, i.e. a first enclosure inside the inner tube.AMAT#44024237 - 8 - 34883P-WOA second enclosure, e.g. a portion of the hollow space, closed housing or a volume of the evaporation source is formed between the walls of the outer tube and the inner tube. Accordingly, the heating element is not within the second enclosure, in which the material for layer deposition is provided. The heater is within the outer tube and the inner tube.

[0033] The distribution pipe further comprises one or more outlets 134 which may be formed as nozzles. The one or more outlets or nozzles extend along an evaporation direction. The evaporation direction can be essentially horizontal. The distribution pipe can be a vapor distribution showerhead having one or more outlets. 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 one or more outlets of the evaporation source have a distance of 25 mm or less. Further, the opening of the one or more outlets or nozzles of the evaporation source have a cross-section of 1 mm to 6 mm in diameter, for example between 1 mm to 3 mm.

[0034] According to some embodiments, which can be combined with other embodiments described herein, the length of the distribution pipe can be 1 m or above, for example 1.5 m or above. According to one configuration, as shown in FIG. 1 B, the evaporation crucible 140 can be provided between a first end of the distribution pipe, e.g. a lower end of the distribution pipe and a second end opposing the first end. A deposition material, such as a metallic material is evaporated in the evaporation crucible 140. The vapor of material enters the distribution pipe 130 and is guided essentially sideways through the plurality of outlets 134 in the distribution pipe, e.g. towards an essentially vertical substrate.

[0035] FIG. 2 shows a heater 120. FIG. 2 illustrates embodiments of the heater according to the present disclosure. The heater 120 includes the heating rod 210. The heating rod 210 has the first electrical connector 212, which can be coupled to a power source 230. The plurality of outer rods 220 are provided. At least one outer rod of the plurality of outer rods has a second electrical connector 222, which can be coupled to the power source 230. The first connection plate 240 provides an electrical connection between the heating rod 210 and the at least one outer rodAMAT#44024237 - 9 - 34883P-WO220. Accordingly, a series circuit of the heating rod and at least one outer rod 220 is provided. As shown in FIG. 2, the 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 heater 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.

[0036] FIG. 3 shows an electrical equivalent circuit diagram corresponding to the heater of FIG. 2. The power source 230 is 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.

[0037] According to some embodiments, which can be combined with other embodiments described herein, a first resistance of the heating rod is at least two times a second resistance of the plurality of outer rods. For example, the first resistance of the heating rod is at least 9 times the second resistance of the plurality of outer rods. Particularly a ratio between the first resistance of the heating rod and the second resistance of the plurality of outer rods can be from about 90: 10 to about 99:1 . For example, the ratio between the first resistance of the heating rod and the second resistance of the plurality of outer rods can be about 98:2. The resistances, and particularly the ratio of the first resistance and the second resistance can be adjusted by the design of the heater. According to some embodiments, a majority of the heat energy can be provided by the heating rod. Yet, a contribution of the outer rods for providing heat energy can be varied by varying the resistance ratio. According to some embodiments, which can be combined with other embodiments described herein, the outer rods can have a heat contribution of 5% or less, i.e. can be a “cold” back contact for the heating rod. Providing a back contact also eliminates the need for slitting a graphite rod or the like to provide a front contact and a back contact at the graphite rod.AMAT#44024237 - 10 - 34883P-WO

[0038] As described above, a heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source is provided. The heater includes a heating rod having a first electrical connector configured to be coupled to a power source and a plurality of outer rods distributed around the heating rod, wherein at least a first outer rod of the plurality of outer rods having a second electrical connector configured to be coupled to the power source. The heater further includes a first connection plate providing a series circuit of the heating rod and the at least first outer rod.

[0039] According to some embodiments, which can be combined with other embodiments described herein, the heater can further include a first insulator adjacent the connection plate; and a second insulator essentially at an opposite side of the plurality of outer rods than the first insulator. Additionally or alternatively, one or more enforcement rings can be coupled to the plurality of outer rods. For example, the one or more enforcement rings can be distributed along a length of the plurality of outer rods.

[0040] FIG. 2 shows a first insulator 262. The first insulator can electrically insulate the heater from the inner tube of the distribution pipe. Further, the first insulator can be shaped to position the heater within the innertube 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 the ceramic material or can include a ceramic material. Particularly, the 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 Bom Nitride (SBN) or combinations thereof.

[0041] According to some embodiments, which can be combined with other embodiments described herein, the second insulator 264 can center the heating rod 210 with respect to the heater 120 and / or with respect to the inner tube of theAMAT#44024237 - 11 - 34883P-WO evaporation source. Further, the second insulator can guide the heater such that the thermal expansions of materials can be compensated for, e.g. such that the materials for the heating rod and outer rods can be different. According to some embodiments, which can be combined with other embodiments described herein, an electrical insulator at the bottom of the heater, e.g. the first insulator 262 shown in FIG. 2, may be avoided if the outer rods are grounded, i.e. connected to ground potential. For example, the outer rods may be connected to ground potential via a current-limiting resistor (such as 1 kOhm to 20 kOhm) to avoid overly high currents. The inner tube of the evaporation source may be connected directly to ground or also via a current-limiting resistor. Thus a short-cut prevention to the inner tube of the evaporation source can be avoided.

[0042] FIG. 2 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 in active. The inner heater, i.e. the heating rod 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.

[0043] FIG. 4 shows a cross-sectional top view of a heater 120 according to some embodiments of the present disclosure. The heating rod 410 and a plurality of outer rods 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 can include, or can consist of, graphite. 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 is provided by the first connection plate (not shown in FIG. 4).AMAT#44024237 - 12 - 34883P-WO

[0044] The resistance of graphite at a temperature of about 1500°C to about 2000°C is about 20 times higher as compared to the resistance of a metal like tungsten, molybdenum, niobium or tantalum. Accordingly, the diameter of the heating rod can be larger than the diameter of an outer rod. For example, the diameter of the heating rod can be about 50% larger to about 150% larger than the diameter of one outer rod. The ratio of the resistance of the heating rod and the plurality of outer rods can be varied by the diameters and the number of outer rods. According to some embodiments, which can be combined with other embodiments described herein, three outer rods to eight outer rods may be exemplarily provided. FIG. 4 shows 5 outer rods providing a protection cage for the brittle heating rod made of graphite. As described above, the heating rod can provide a majority of heat energy. For example, a ratio between the first resistance of the heating rod and the second resistance of the plurality of outer rods (provided in a parallel circuit) is from about 90: 10 to about 99: 1 .

[0045] A gap 401 can be provided between the graphite 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 heater. According to some embodiments, which can be combined with other embodiments described herein, the diameter of the heater, i.e. the maximum diameter of the heater, 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 heater 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 element (the heating rod) allows for reduction of the diameter of the heater.

[0046] FIG. 5 shows a cross-sectional top view of a heater 120 according to some embodiments of the present disclosure. The heating rod 510 and a plurality of outer rods 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 and the plurality of outer rods can include, or can consist of, a material selected from the group of molybdenum,AMAT#44024237 - 13 - 34883P-WO tungsten, tantalum, niobium or an alloy of molybdenum, tungsten, niobium or tantalum. An electrical series connection is provided by the first connection plate (not shown in FIG. 5). According to some embodiments, which can be combined with other embodiments described herein, the heating rod and the outer rods can be provided of the same material. Improved electrical connection, particularly at high temperatures, and similar thermal expansion can be provided more easily.

[0047] In order to have the resistance ratio between the resistance of the heating rod and the outer rods, wherein the heating rod provides a majority of heat energy, the heating rod 510 having, for example the same material as the outer rods, has a smaller diameter as compared to the outer rods. For example, the diameter of the heating rod can be about 20% to about 50% of the diameter of one outer rod. The ratio of the resistance of the heating rod and the plurality of outer rods can be varied by the diameters and the number of outer rods. According to some embodiments, which can be combined with other embodiments described herein, three outer rods to eight outer rods may be exemplarily provided. FIG. 5 shows 5 outer rods providing a protection cage for the thin heating rod. As described above, the heating rod can provide a majority of heat energy. For example, a ratio between the first resistance of the heating rod and the second resistance of the plurality of outer rods (provided in a parallel circuit) is from about 90:10 to about 99:1. A full metal heater can be provided, i.e. a heater without a graphite heating rod and for evaporation of metallic materials, e.g. at a temperature of 500°C or above, 1000°C or above, or even 1400°C or more (e.g., for Ag evaporation).

[0048] According to some embodiments, which can be combined with other embodiments described herein, the heating rod can include or can consist of tungsten. Particularly, in light of the smaller emission surface of the thinner heating rod, the heating rod providing the majority of heat energy is operated at a higher temperature. Thus, tungsten can be a beneficial material for a heater 120 having a non-graphite heating rod 510.

[0049] Embodiments of the present disclosure can provide a heater for an evaporation source, and particularly an inner heater of an evaporation source, wherein a heating rod of a sensitive material, such as graphite, or a heating rodAMAT#44024237 - 14 - 34883P-WO beam thin can be protected. Outer rods, which additionally serve for providing power to the heating rod, provide an outer and robust cage. The ration between resistances of the heating rod and the outer rods can be adjusted. For example, the heating rod can provide a majority of the heat energy and the outer rods, i.e. the cage, may serve as a “cold” back contact. The protection results in reduced risk for heater breakage during heater handling.

[0050] A thinner heating rod of the same material as the outer rods may also be protected by the cage, wherein the heating rod and the outer rods have a similar or the same thermal expansion. Further, an electrical connection can be provided more easily as compared to embodiments with different materials, for which, particularly at high temperatures, thermal reactions between components of different materials may occur.

[0051] In some embodiments, which can be combined with other embodiments described herein, an electron bombardment heating mechanism may further be provided for heating the distribution pipe. Specifically, the heater may be configured to radiate heat for heating the distribution pipe and may in addition be configured to release electrons by thermionic emission, also referred to as “thermions”. A mechanism may be provided for accelerating the electrons released from the heater toward at least a portion of the wall of the distribution pipe, particularly toward the inner tube of the distribution pipe. The electrons impinging on the wall of the distribution pipe may facilitate the heat-up of the distribution pipe by electron bombardment. In particular, a voltage source (e.g., a high voltage DC source) may be provided in some embodiments for applying a potential difference between the heater and at least a part of the wall of the distribution pipe for accelerating the electrons onto the wall, particularly onto the inner tube.

[0052] FIG. 6 shows a schematic sectional view of an evaporation source that includes such an “electron bombardment heating mechanism”, which is optionally provided in some embodiments described herein for improving the heating. In particular, by providing the electron bombardment heating mechanism, the heating efficiency can be improved so that a smaller current flowing through the heater can already provide a sufficient heating.AMAT#44024237 - 15 - 34883P-WO

[0053] FIG. 6 shows an evaporation source 600 for depositing a material 611 on a substrate, comprising: an evaporation crucible 610 to evaporate the material 611 ; a distribution pipe 620 comprising: a wall 621 defining a vapor propagation volume 622 for receiving evaporated material from the evaporation crucible 610; and a plurality of nozzles 623 for directing the evaporated material onto the substrate. A heating assembly 632 for the distribution pipe 620 is provided. The heating assembly includes a heater 633 as described herein arranged at least partially in the distribution pipe 620 and configured to radiate heat, particularly in the inner tube 651 of the distribution pipe. According to some embodiments described herein, the heating assembly 632 is configured to accelerate electrons 635 from the heater 633 towards at least a portion 62T of the wall 621 to heat the wall 621 and / or the vapor propagation volume 622 that is enclosed by the wall 621 .

[0054] As is only schematically depicted in FIG. 6, the heater 633 may be configured as described herein, including a heating rod having a first electrical connector configured to be coupled to a power source 631 ; and a plurality of outer rods distributed around the heating rod, at least a first outer rod of the plurality of outer rods having a second electrical connector configured to be coupled to the power source 631 . A connection plate may provide a series circuit of the heating rod and the at least first outer rod.

[0055] In FIG. 6, the wall 621 of the distribution pipe 620 defines and encloses the vapor propagation volume 622 which receives the vapor from the evaporation crucible 610. In particular, the wall 621 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 622 has a generally annular shape being formed between a radially inner tubular wall (= inner tube) and a radially outer tubular wall (= outer tube) of the distribution pipe, as is schematically depicted in FIG. 6. “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.AMAT#44024237 - 16 - 34883P-WO

[0056] During a deposition process, the material 611 residing within the evaporation crucible 610 is heated to evaporate the material 611. The evaporated material may then be guided to the vapor propagation volume 622 of the distribution pipe 620 for further distribution. Subsequently, the evaporated material may be guided out of the distribution pipe 620 via the plurality of nozzles 623 onto a substrate, such that the material 611 can be deposited onto the substrate. Typically, the evaporated material can be maintained at a high temperature in the distribution pipe 620, e.g., to avoid condensation of the material 611 within the distribution pipe 620.

[0057] A first type of heating can be provided by the radiation heating of the heater 633. The radiation heating may be based on a resistive heating mechanism, as described herein. Specifically, the heater 633 is configured for resistive heating such that the heater 633 radiates heat. The heater 633 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 heater 633 may include one or more electrical conductors which radiate heat when an electrical current is applied through the one or more electrical conductors by power source 631 .

[0058] A second type of heating can be provided by an electron bombardment heating mechanism of the heating assembly 632. The electron bombardment heating may be configured to accelerate electrons from the heater 633 towards at least a portion of the wall 621 that defines the vapor propagation volume. The electron bombardment heating may be regarded as an electron acceleration configuration integrated into the evaporation source 600. At least a portion 62T of the wall 621 may function as an anode (receiving electrons) of the electron acceleration configuration. In some embodiment, the inner tube 651 may function as the anode onto which the electrons are accelerated.

[0059] The electrons may be released from the heater 633 due to the radiation of heat. Typically, electrons 635 may be released from the heater 633 due to the effect of thermionic emission. Due to the acceleration of the electrons by the electron bombardment heating, the electrons 635 may travel from the heater 633 to impinge onto a portion 62T of the wall 621 , particularly on the inner tube 651 . As describedAMAT#44024237 - 17 - 34883P-WO herein, the electrons 635 may be accelerated due to an electrical potential difference between the inner tube 651 and the heater 633 which exerts an accelerating force onto the electrons. When the accelerated electrons 635 impinge onto the inner tube 651 , the inner tube is heated. The heated wall 621 can provide a heating of the vapor propagation volume 622, particularly a heating of the evaporated material residing within the vapor propagation volume 622. Accordingly, the wall 621 is heated by two heating mechanisms: Heat radiation from the heater 633, and electron bombardment caused by electrons released from the heater 633 and impinging the wall.

[0060] 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 and the heating by the electron bombardment heating simultaneously for heating the vapor propagation volume 622. The total heat provided to the vapor propagation volume 622 may thus comprise a first heat generated by the radiation heating and a second heat generated by the electron bombardment heating. This may enable to reduce the current flowing through the heater 633.

[0061] The wall 621 of the distribution pipe as described herein may include the inner tube 651 and the outer tube 652, the vapor propagation volume 622 being at least partially formed between the inner tube and the outer tube. The heating assembly 632 may be configured to accelerate electrons 635 from the heater 633 towards at least a portion of the inner tube 651 . In an example, the heating assembly 632 is configured to set the heater on a first electrical potential and / or to set the wall 621 of the distribution pipe on a second electrical potential to accelerate electrons towards the wall 621 .

[0062] In some embodiments, the heating assembly 632 may comprise a voltage source 641 , particularly a high voltage source (e.g., a DC high voltage source), electrically coupled to the heater 633 and to the wall 621 and configured to apply the electrical potential difference between the heater 633 and the wall 621 .AMAT#44024237 - 18 - 34883P-WO

[0063] In an example, the wall 621 of the distribution pipe is on a reference potential 642, particularly on ground, and the voltage source 641 is configured to set the heater 633 onto a negative voltage offset with respect to the reference potential, particularly a voltage offset of 1000 V or more. Specifically, the voltage source 641 may be provided for applying a potential difference between the heater and the wall of the distribution pipe, and a power source 631 configured for high currents may be provided for sending a high current through the heater 633.

[0064] FIG. 7 shows a flowchart illustrating methods of manufacturing a layer stack or layer for a device. Deposition material is evaporated. As shown by operation 702, the deposition material, i.e. the evaporated deposition material, is guided in a distribution pipe of an evaporation source. For example, the deposition material can be evaporated in an evaporation crucible. The deposition material can be guided in an enclosure formed between an inner tube of distribution pipe and an outer tube of the distribution pipe. The enclosure can be the second enclosure described with respect to FIG. 1 . The distribution pipe is heated by a heater that has a heating rod and a plurality of outer rods (see operation 704). Particularly, a current for heating the heating rod can be provided through the heating rod and at least the first outer rod of the plurality of outer rods. By adapting the ratio of resistances between the heating rod and the outer rods, a majority of heat radiation or a majority of heat energy can be provided by the heating rod. The evaporated deposition material distributes in the distribution pipe and can be guided through one or more outlets in the distribution pipe, particularly the outer tube of the distribution pipe, onto a substrate of the device (see operation 706). A layer of deposition material is provided on the substrate.

[0065] According to an embodiment, a method of manufacturing a layer stack for a device is provided. The method includes evaporating a deposition material in an evaporation crucible and guiding the evaporation material from the evaporation crucible into a distribution pipe. The distribution pipe is heated with a heater including a heating rod and a plurality of outer rods, by providing a current through the heating rod and at least a first outer rod of the plurality of rods. The method further includes guiding the deposition material through one or more outlets onto a substrate of the device. According to some embodiments, which can be combinedAMAT#44024237 - 19 - 34883P-WO with other embodiments described herein, the heater can be a heater according to any of the embodiments of the present disclosure.

[0066] FIG. 8 shows a vacuum deposition system 800 with evaporation source arrangements 810, evaporation source arrays, or evaporation sources 100 according to embodiments described herein in a schematic top view. The vacuum deposition system 800 includes a first vacuum chamber 801 that houses a first 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 802 and / or a third evaporation source 803. The evaporation sources may be configured to coat vertically, or essentially vertically oriented substrates that are transported past the evaporation sources on a substrate transportation track 813. A plurality of materials, that may include one or more metals and 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 vacuum deposition system 800 may include 10 or more evaporation sources for coating the substrate with a plurality of layers.

[0067] In the present disclosure, a "vacuum deposition system" or “evaporation system” is to be understood as a system or arrangement configured for vacuum deposition of materials on a substrate. A "vacuum chamber" or “vacuum processing 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 with 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.

[0068] The vacuum deposition system 800 may include a substrate transportation track 813 configured to move a substrate 10 along a substrate transport path T past the first evaporation source 100 and past the optional further evaporation sources. The substrate transportation track 813 may extend at least partially through the first vacuum chamber 801 and through the optional further vacuum chambers, and may include a substrate transportation system configured for substrate transport, e.g., a roller transportation system, one or more linear motors and / or a magnetic levitationAMAT#44024237 - 20 - 34883P-WO system suitable for moving the substrate relative, to and past, the evaporation sources. The substrate may be carried by a substrate carrier 820 during the transport and / or deposition.

[0069] The vacuum deposition system 800 may further include a shield transportation track 812 extending between the substrate transportation track 813 and the first evaporation source 100 in the first vacuum chamber 801. The shield transportation track 812 is configured to move a movable shield 830 in front of the substrate 10 for shielding one or more edge regions of the substrate 10 and / or for shielding at least parts of a substrate carrier 820 that carries the substrate 10. The movable shield 830 may be a movable edge exclusion shield with a shielding frame for covering one or more edge regions of the substrate. The shield transportation track 812 may be located between the substrate transportation track 813 and the first evaporation source 100 in the first vacuum chamber 801 and may include a shield transportation system, e.g., a roller transportation system, one or more linear motors and / or a magnetic levitation system suitable to move the movable shield 830 in front of the substrate 10, such that one or more edge regions of the substrate are covered during coating with the first evaporation source 100, as is schematically depicted in FIG. 8.

[0070] The movable shield 830 may be movable back and forth on the shield transportation track 812, as is schematically indicated by respective arrows in FIG. 8, such that subsequent substrates moved along the substrate transport path T can be shielded by the movable shield 830 during coating with the first evaporation source 100. Each evaporation source may have an associated movable shield that is movable back and forth on a respective shield transportation track for shielding an edge region of the substrate from being coated when the substrate is moved past the respective evaporation source.

[0071] 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 vacuum deposition system 800.AMAT#44024237 - 21 - 34883P-WO

[0072] 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, semiconductor wafers may be processed and coated in deposition systems according to the present disclosure.

[0073] In some implementations, a mixed material layer, particularly a mixed metal layer or another mixed inorganic layer, is co-deposited onto the substrate with an evaporation source array during the transport of the substrate 10 past the first evaporation source 100. Alternatively, a mixed organic layer that comprises at least two different organic materials is co-deposited onto the substrate with the first row of nozzles and the second row of nozzles being tilted toward each other. The mixed metal layer may be a cathode layer of an OLED layer stack, particularly a cathode layer comprising co-deposited silver and magnesium.

[0074] FIG. 9 shows an evaporation source array 900. The evaporation source array may include 3 evaporation sources, wherein one or more of the evaporation sources for each of the evaporation sources can include a heater according to embodiments of the present disclosure.

[0075] In some embodiments, which can be combined with other embodiments described herein, the evaporation source array has a first vapor distribution pipe 130, with a first row of nozzles (one or more outlets 134) that have a first mainAMAT#44024237 - 22 - 34883P-WO evaporation direction M1 , has a second vapor distribution pipe 130, with a second row of nozzles (one or more outlets 134) that have a second main evaporation direction, and has a third vapor distribution pipe 130, with a third row of nozzles (one or more outlets 134) that have a third main evaporation direction M3.

[0076] The first main evaporation direction and the second main evaporation direction are tilted towards each other in order to enable a co-deposition of two materials on the substrate. In other words, the first and second rows of nozzles may be configured such that first vapor plumes emitted by the first row of nozzles and third vapor plumes emitted by the third row of nozzles overlap during propagation toward the substrate, such that a mixed layer can be deposited.

[0077] Optionally, the third main evaporation direction and the first main evaporation direction are tilted away from each other in order to enable a sequential deposition of two layers on top of each other on the substrate in the first deposition position. In other words, the first and third rows of nozzles may be configured such that the first vapor plumes emitted by the first row of nozzles and the third vapor plumes emitted by the third row of nozzles do not overlap during propagation toward the substrate, such that separate layers can be deposited on top of each other with the first (and optionally the second) and the third vapor distribution pipes.

[0078] In particular, during the transport of the substrate past the first evaporation source, an electron injection layer (EIL) can be deposited onto the substrate with the third vapor distribution pipe 130 and a cathode layer can be deposited over the electron injection layer with at least the first vapor distribution pipe 130, particularly with the first and second vapor distribution pipes by co-deposition. In particular, a co-deposited cathode layer can be deposited on top of the electron injection layer, wherein the co-deposited cathode layer is deposited with the first and second vapor distribution pipes, and the electron injection layer is deposited with the third vapor distribution pipe. In another embodiment, the third main evaporation direction of the third row of nozzles may be tilted toward the first and the second main evaporation directions to enable a co-deposition of a mixed layer, that includes at least three different materials.AMAT#44024237 - 23 - 34883P-WO

[0079] According to some embodiments, which can be combined with other embodiments described herein, the outlets (e.g. nozzles) are arranged to have a main evaporation direction to be horizontal ± 20° deviating from horizontal (irrespective of the rotation along a vertical axis). According to some specific embodiments, the evaporation direction can be oriented slightly upward, e.g. to be in a range from horizontal to 15° upward, such as 3° to 7° upward. Correspondingly, the substrate can be slightly inclined to be substantially perpendicular to the evaporation direction. The slightly inclined orientation of evaporation direction and substrate can reduce undesired particle generation.

[0080] According to an embodiment, an evaporation source is provided. The evaporation source includes a distribution pipe with one or more outlets provided along the length of the distribution pipe, the distribution pipe having an opening configured to be in fluid communication with an evaporation crucible. The distribution pipe includes an inner tube providing a first enclosure and an outer tube providing a second enclosure between the outer tube and the inner tube. The evaporation source further includes a heater according to any of the embodiments of the present disclosure provided in the first enclosure. For example, the inner tube and the outer tube can be provided as a single piece. According to some embodiments, which can be combined with other embodiments described herein, the distribution pipe can be made of, or include, a material selected from the group of: molybdenum, tungsten, tantalum, niobium or an alloy of molybdenum, tungsten, niobium or tantalum. The evaporation source may further include an evaporation crucible, wherein the evaporation crucible is configured to evaporate a deposition material, the evaporation crucible being in fluid communication with the opening. The one or more outlets can be nozzles extending along an evaporation direction.

[0081] According to some embodiments, which can be combined with other embodiments described herein, the distribution pipe can be a vapor distribution showerhead including the one or more outlets, particularly wherein the vapor distribution showerhead is a linear vapor distribution showerhead providing a linear source for vapor of e.g. a metal or metal alloy. A showerhead can be understood herein as including an enclosure having openings such that the pressure in theAMAT#44024237 - 24 - 34883P-WO showerhead is higher than that outside of the showerhead, for example by at least one order of magnitude higher.

[0082] According to an embodiment, an evaporation source array, e.g. for metals or metal alloys is provided. The evaporation source array includes a first evaporation source according to any of the embodiments described herein; and at least a second evaporation source according to any of the embodiments described herein. The example of an evaporation source array is shown in FIG. 9. At least a first outlet of the one or more outlets of the first evaporation source and at least a second outlet of the one or more outlets of the second evaporation source have a distance of 200 mm or less.

[0083] A first and a second evaporation source can form an array. An array of evaporation sources can be used to yield an increased evaporation rate of one metal or metal alloy. Further, an array of evaporation sources can be used for coevaporation of two different metals or metal alloys. Further, an array of evaporation sources can be used for subsequent evaporation of two different metals or metal alloys. According to an embodiment, which can be combined with other embodiments described herein, the array of evaporation sources can be arranged such that the evaporation direction of the one or more outlets of each evaporation source is inclined to a symmetrical plane provided along the length of the distribution pipe. For example, the inclination angle of the distribution source, e.g. the angle at which the main evaporation direction of the evaporation source emits the material relative to the surface orthogonal of the substrate surface can be 20° or below, for example between 3° and 10°. The orientation of the one or more outlets or nozzles provides the possibility to realize a shorter distance between the array of evaporation sources and the substrate.

[0084] According to an embodiment, the evaporated material of a first evaporation source can be silver (Ag) and the evaporated material of a second evaporation source can be magnesium (Mg). The first and second evaporated material can be evaporated in a ratio between 1 :2 < Ag : Mg < 15:1 , particularly between 5:1 < Ag : Mg < 10:1.AMAT#44024237 - 25 - 34883P-WO

[0085] As described above with respect to FIG. 8, an evaporation system can be provided. According to an embodiment, an evaporation system includes one or more vacuum chambers and a substrate transport assembly configured to transport a substrate through the one or more vacuum chambers. The evaporation system includes: one or more evaporation source arrays according to any of the embodiments of the present disclosure, or one or more evaporation sources according to any of the embodiments of the present disclosure, wherein the substrate is transported past the one or more evaporation source arrays or the one or more evaporation sources for deposition materials on the substrate.

[0086] 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#44024237 - 26 - 34883P-WOCLAIMSWhat is claimed is:1 . A heater configured to be arranged in an inner tube of a distribution pipe of an evaporation source, comprising: a heating rod having a first electrical connector configured to be coupled to a power source; a plurality of outer rods distributed around the heating rod, at least a first outer rod of the plurality of outer rods having a second electrical connector configured to be coupled to the power source; and a first connection plate providing a series circuit of the heating rod and the at least first outer rod.

2. The heater of claim 1 , wherein the plurality of outer rods surround the heating rod such that the plurality of outer rods are configured to provide a protection cage for the heating rod.

3. The heater of any of claims 1 to 2, wherein a first resistance of the heating rod is at least two times a second resistance of the plurality of outer rods.

4. The heater of claim 3, wherein the first resistance of the heating rod is at least 9 times the second resistance of the plurality of outer rods, particularly wherein a ratio between the first resistance of the heating rod and the second resistance of the plurality of outer rods is from about 90:10 to about 99:1 .

5. The heater of any of claims 1 to 4, further comprising: a first insulator adjacent the first connection plate; and a second insulator essentially at an opposite side of the plurality of outer rods than the first insulator.AMAT#44024237 - 27 - 34883P-WO6. The heater of any of claims 1 to 5, further comprising: one or more enforcement rings coupled to the plurality of outer rods.

7. The heater of any of claims 1 to 6, further comprising: 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.

8. The heater of any of claims 1 to 7, wherein the heating rod comprises or consists of graphite and wherein the plurality of outer rods comprise or consist of a material selected from a group of: molybdenum, tungsten, niobium, tantalum, or an alloy of molybdenum, tungsten, niobium or tantalum.

9. The heater of any of claims 1 to 8, wherein the heating rod and the plurality of outer rods comprise or consist of a material selected from a group of: molybdenum, tungsten, niobium, tantalum, or an alloy of molybdenum, tungsten, niobium or tantalum.

10. An evaporation source, comprising: a distribution pipe with one or more outlets provided along a length of the distribution pipe, the distribution pipe comprising an opening configured to be in fluid communication with an evaporation crucible, the distribution pipe comprises: an inner tube providing a first enclosure; and an outer tube providing a second enclosure between the outer tube and the inner tube; the evaporation source further comprising: a heater according to any of claims 1 to 9 provided in the first enclosure.AMAT#44024237 - 28 - 34883P-WO11 . The evaporation source of claim 10, wherein the inner tube and the outer tube are provided as a single piece.

12. The evaporation source of any of claims 10 to 11 , further comprising: an evaporation crucible, wherein the evaporation crucible is configured to evaporate a deposition material, the evaporation crucible being in fluid communication with the opening.

13. The evaporation source according to any of claims 10 to 12, wherein the distribution pipe is made of or comprises a material selected from a group of: molybdenum, tungsten, niobium, tantalum, or an alloy of molybdenum, tungsten, niobium or tantalum.

14. The evaporation source according to any of claims 10 to 13, wherein the one or more outlets are nozzles extending along an evaporation direction.

15. The evaporation source according to any of claims 10 to 14, wherein the distribution pipe is a vapor distribution showerhead including the one or more outlets, particularly wherein the vapor distribution showerhead is a linear vapor distribution showerhead providing a linear source for vapor of a metal, metal alloy or a non-metal.

16. The evaporation source according to any of claims 10 to 15, further comprising: a heating assembly configured to accelerate electrons (635) from the heater (633) towards a wall (621 ) of the distribution pipe, particularly onto the inner tube (651 ).

17. An evaporation source array for metals or metal alloys, comprising: a first evaporation source according to any of claims 10 to 16; and at least a second evaporation source according to any of claims 10 to16,AMAT#44024237 - 29 - 34883P-WO wherein at least a first outlet of the one or more outlets of the first evaporation source and at least a second outlet of the one or more outlets of the second evaporation source have a distance of 200 mm or less.

18. An evaporation system comprising: one or more vacuum chambers; a substrate transport assembly configured to transport a substrate through the one or more vacuum chambers; and one or more evaporation source arrays according to claim 17 or one or more evaporation sources according to any of claims 10 to 16, wherein the substrate is transported past the one or more evaporation source arrays or the one or more evaporation sources for deposition materials on the substrate.

19. A method of manufacturing a layer stack or a layer for a device, comprising: evaporating a deposition material in an evaporation crucible; guiding the deposition material from the evaporation crucible into a distribution pipe; heating the distribution pipe with a heater having a heating rod and a plurality of outer rods by providing a current through the heating rod and at least a first outer rod of the plurality of outer rods; and guiding the deposition material through one or more outlets onto a substrate of the device to deposit a layer of the deposition material.

20. The method of claim 19, wherein the heater is a heater according to any of claims 1 to 9.

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