FOR DEPOSITING ORGANIC MATERIAL

TECHNICAL FIELD [0001] Embodiments of the present disclosure relate to deposition of organic material, a system for depositing materials, e.g. organic materials, a source for organic material and deposition apparatuses for organic material. Embodiments of the present disclosure particularly relate to evaporation sources for organic material, e.g. for evaporation apparatuses and/or manufacturing systems for manufacturing devices, particularly devices including organic materials therein.

BACKGROUND

[0002] Organic evaporators are a tool for the production of organic light-emitting diodes (OLED). OLEDs are a special type of light-emitting diodes in which the emissive layer includes a thin-film of certain organic compounds. Organic light emitting diodes (OLEDs) are used in the manufacture of television screens, computer monitors, mobile phones and other hand-held devices for displaying information. OLEDs can also be used for general space illumination. The range of colors, brightness, and viewing angles possible with OLED displays is greater than that of traditional LCD displays, because OLED pixels directly emit light and do not need a back light. Therefore, the energy consumption of OLED displays is considerably less than that of traditional LCD displays. Further, the fact that OLEDs can be manufactured onto flexible substrates results in further applications. A typical OLED display, for example, may include layers of organic material situated between two electrodes that are all deposited on a substrate in a manner to form a matrix display panel having individually energizable pixels. The OLED is generally placed between two glass panels, and the edges of the glass panels are sealed to encapsulate the OLED therein.

[0003] There are many challenges encountered in the manufacture of such display devices. OLED displays or OLED lighting applications include a stack of several organic materials, which are for example evaporated in a vacuum. The organic materials are deposited in a subsequent manner through shadow masks. For the fabrication of OLED stacks with high efficiency, the co-deposition or co-evaporation of two or more materials, e.g. host and dopant, leading to mixed/doped layers is beneficial. Further, it has to be considered that there are several process conditions for the evaporation of the very sensitive organic materials.

[0004] For depositing the material on a substrate, the material is heated until the material evaporates. Pipes guide the evaporated material to the substrates through nozzles. In the past years, the precision of the deposition process has been increased, e.g. for being able to provide smaller and smaller pixel sizes. In some processes, masks are used for defining the pixels when the evaporated material passes through the mask openings. However, shadowing effects of a mask, the spread of the evaporated material and the like make it difficult to further increase the precision and the predictability of the evaporation process.

[0005] In view of the above, it is beneficial to increase the precision and predictability of evaporation processes for manufacturing devices having a high quality and precision. SUMMARY

[0006] In view of the above, an evaporation source, a deposition apparatus and a method of depositing an evaporated material onto a substrate according to the independent claims are provided. Further advantages, features, aspects and details are apparent from the dependent claims, the description and drawings. [0007] According to one aspect of the present disclosure, an evaporation source for depositing material on a substrate is provided. The evaporation source includes an evaporation crucible, wherein the evaporation crucible is configured to evaporate the material; a distribution unit with one or more outlets, wherein the distribution unit is in fluid communication with the evaporation crucible, and wherein the one or more outlets are configured for providing the material to the substrate in a deposition direction; a first cooling shield arrangement provided including one or more openings; a heated shield arrangement provided at a distance from the first cooling shield arrangement, wherein the heated shield arrangement includes one or more apertures, wherein the first cooling shield arrangement is arranged between the distribution unit and the heated shield arrangement, wherein the evaporation source is configured to define a path for the material in the deposition direction from the one or more outlets through the one or more openings and the one or more apertures to the substrate.

[0008] According to another aspect of the present disclosure, a deposition apparatus including one or more evaporation sources according to embodiments described herein is provided.

[0009] According to another aspect of the present disclosure, a deposition apparatus including one or more evaporation sources according to embodiments described herein is provided. The evaporation source includes an evaporation crucible, wherein the evaporation crucible is configured to evaporate the material; a distribution unit with one or more outlets, wherein the distribution unit is in fluid communication with the evaporation crucible, and wherein the one or more outlets are configured for providing the material to the substrate in a deposition direction; a first cooling shield arrangement provided including one or more openings; a heated shield arrangement provided at a distance from the first cooling shield arrangement, wherein the heated shield arrangement includes one or more apertures, wherein the first cooling shield arrangement is arranged between the distribution unit and the heated shield arrangement, wherein the evaporation source is configured to define a path for the material in the deposition direction from the one or more outlets through the one or more openings and the one or more apertures to the substrate. [0010] According to a further aspect of the present disclosure, a method of depositing material on a substrate is provided. The method includes evaporating the material and applying the evaporated material to the substrate, wherein applying the evaporated material to the substrate includes: providing the evaporated material through one or more outlets of a distribution unit in a deposition direction and passing the evaporated material through one or more openings of a first cooling arrangement and through one or more apertures of a heated shield arrangement.

[0011] The disclosure is also directed to an apparatus for carrying out the disclosed methods including apparatus parts for performing the methods. The method 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, the disclosure is also directed to operating methods of the described apparatus. It includes a method for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS

[0012] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

[0013] FIG. 1 shows a schematic view of an evaporation source according to embodiments herein; [0014] FIG. 2 shows a schematic view of an evaporation source according to further embodiments herein;

[0015] FIGS. 3A and 3B show schematic views of portions of an evaporation source according to embodiments described herein;

[0016] FIG. 3C shows a schematic view of another evaporation source according to embodiments described herein;

[0017] FIGS. 4 A and 4B shows a schematic side view of an evaporation source according to embodiments herein;

[0018] FIG. 5 shows a schematic top view of an evaporation source according to further embodiments herein; [0019] FIG. 6 shows a schematic top view of an evaporation source according to yet further embodiments herein;

[0020] FIG. 7 shows a schematic top view of a deposition apparatus for depositing a source material in a vacuum chamber according to embodiments described herein;

[0021] FIGS. 8 A and 8B show schematic block diagrams illustrating a method of depositing a source material on a substrate according to embodiments described herein; DETAILED DESCRIPTION OF EMBODIMENTS

[0022] Reference will now be made in detail to the various embodiments of the disclosure, 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. In the following, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation of the disclosure and is not meant as a limitation of the disclosure. 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 the description includes such modifications and variations. [0023] In the present disclosure, the term "source material" may be apprehended as a material that is evaporated and deposited on a surface of a substrate. For example, in embodiments described herein, an evaporated material that is deposited on a surface of a substrate may be an organic source material. Non-limiting examples of organic materials include one or more of the following: ITO, NPD, Alq ₃ , Quinacridone, Mg/AG, starburst materials, and the like.

[0024] In the present disclosure, the term "fluid communication" may be understood in that two elements being in fluid communication can exchange fluid via a connection, allowing fluid to flow between the two elements. In one example, the elements being in fluid communication may include a hollow structure through which the fluid may flow. According to some embodiments, at least one of the elements being in fluid communication may be a pipe-like element.

[0025] In the present disclosure, the term "evaporation source" may be understood as an arrangement providing a source material to be deposited on a substrate. In particular, the evaporation source may be configured for providing a source material to be deposited on a substrate in a vacuum chamber, such as a vacuum deposition chamber of a deposition apparatus. According to some embodiments described herein, the evaporation source may be configured to evaporate the source material to be deposited on the substrate. For instance, the evaporation source may include an evaporator or a crucible, which evaporates the source material to be deposited on the substrate, and a distribution unit, which, in particular, releases the evaporated source material in a direction towards the substrate, e.g. through one or more outlets.

[0026] In the present disclosure, the term "crucible" may be understood as a device or a reservoir providing or containing the source material to be deposited. Typically, the crucible may be heated for evaporating the source material to be deposited on the substrate. According to embodiments herein, the crucible may be in fluid communication with the distribution unit to which the source material being evaporated by the crucible may be delivered.

[0027] The "distribution unit" or "distribution pipe" can be a unit for providing evaporated source material. In particular, the distribution unit may be configured for providing evaporated source material from a crucible through one or more outlets to a substrate. The "distribution unit" or "distribution pipe" can include one or more outlets. The "distribution unit" or "distribution pipe" can be an elongated tube, e.g. such that an outlet is distant or not directly adjacent to the crucible.

[0028] In the present disclosure, the term "cooling shield arrangement" may be understood as a shield arrangement which is configured to be actively cooled. In particular, a cooling shield arrangement as described herein may be configured to be cooled to a condensation temperature of a source material to be deposited on a substrate, as described herein. For example, a cooling shield arrangement as described herein may be configured to be cooled to a temperature of below 50°C, particularly below 40 °C, more particularly below 30 °C, e.g. approximately 20°C.

[0029] In the present disclosure, the term "heated shield arrangement" may be understood as a shield arrangement which is configured to be actively heated. In particular, a heated shield arrangement as described herein may be configured to be actively heated to a temperature which corresponds to the evaporation temperature of a source material to be deposited on a substrate, as described herein. It is to be understood that the heated shield arrangement as described herein may also be configured to be actively heated to a temperature which is above the evaporation temperature of a source material to be deposited on a substrate.

[0030] In the present disclosure, the term "deposition direction" may be understood as a main emission direction of evaporated source material provided through one or more outlets of a distribution unit as described herein. In particular, a deposition direction as described herein may be understood as a direction which is +/- 20° with respect to a horizontal.

[0031] FIG. 1 shows a schematic view of an evaporation source 100 according to embodiments herein. In particular, as exemplarily shown in FIG. 1, the evaporation source 100 includes an evaporation crucible 104 which is configured to evaporate the source material. Further, the evaporation source 100 includes a distribution unit 130 with one or more outlets 212. The distribution unit 130 is in fluid communication with the evaporation crucible 104. The one or more outlets 212 of the distribution unit 130 are configured for providing the source material to the substrate 10 in a deposition direction 101. Additionally, the evaporation source 100 includes a first cooling shield arrangement 201 including one or more openings 221. As exemplarily shown in FIG. l, the evaporation source 100 further includes a heated shield arrangement 202 which is provided at a distance from the first cooling shield arrangement 201. The heated shield arrangement 202 includes one or more apertures 222. The first cooling shield arrangement 201 is arranged between the distribution unit 130 and the heated shield arrangement 202. Further, according to embodiments herein as exemplary shown in FIG. 1, the evaporation source 100 is configured to define a path for the source material in the deposition direction 101 from the one or more outlets 212 through the one or more openings 221 and the one or more apertures 222 to the substrate 10.

[0032] Accordingly, by providing an evaporation source according to embodiments described herein, a predetermined emission angle behind the heated shield arrangement in deposition direction can be provided such that the angle of incidence of evaporated source material provided to a substrate, e.g. through a mask, can be limited in order to reduce shadowing effects of the mask. Accordingly, an improved resolution of deposited source material on a substrate can be achieved. Further, beneficially an evaporation source according to embodiments described herein provides for preventing or even avoiding clogging of the one or more apertures of the heated shield arrangement and the one or more outlets of the distribution unit, such that stable deposition process conditions can be maintained over a long time. This is because the evaporated source material which does not pass the one or more apertures of the heated shield arrangement is back scattered to the first cooling shield arrangement at which the evaporated source material condensates, such that the back scattered source material can be collected on the first cooling shield arrangement. Accordingly, the one or more apertures of the heated shield arrangement and the one or more outlets of the distribution unit remain clean throughout the deposition process.

[0033] As exemplarily shown in FIG. 1, the one or more apertures 222 of the heated shield arrangement 202 may confine an emission angle (Θ) of the evaporated source material provided through the one or more outlets 212 of the distribution unit 130. Accordingly, it is to be understood that according to embodiments described herein, the heated shield arrangement 202 may be configured for delimiting a distribution cone or plume 318 of evaporated source material distributed towards the substrate 10. In particular, the heated shield arrangement 202 may be configured to block at least a portion of the evaporated source material, as exemplarily indicated in FIG. 1 by the dotted arrows which are reflected from the heated shield arrangement 202. Typically, the one or more apertures 222 of the heated shield arrangement 202 may be arranged to be aligned in the deposition direction 101 with the one or more outlets 212 of the distribution unit 130. In particular, the one or more apertures 222 of the heated shield arrangement 202 are configured and arranged such that behind the heated shield arrangement 202, i.e. when the evaporated source material has passed the one or more apertures 222, a predetermined emission angle (Θ) can be provided. In other words, the heated shield arrangement 202 may be adapted to block evaporated source material having a predetermined emission angle (Θ) greater than 30°, in particular greater than 40°, e.g. greater than 45°, from a main emission direction (also referred to as deposition direction herein) of the evaporated source material provided from any of the one or more outlets 212 of the distribution unit 130. Accordingly, by providing an evaporation source according to embodiments described herein, shadowing effects caused by a mask provided before the substrate may be reduced such that an improved resolution of deposited source material on a substrate can be achieved. [0034] According to embodiments which can be combined with any other embodiments described herein, the heated shield arrangement 202 is configured to be heated to a first temperature. In particular, the first temperature to which the heated shield arrangement 202 may be heated may correspond to the evaporation temperature of the source material to be deposited. For example, the heated shield arrangement 202 may include heating elements. The heating elements may be mounted or attached to the heated shield arrangement. Additionally or alternatively, heating elements may be arranged within the heated shield arrangement. For example the heating elements may be thermoelectric heating devices. Accordingly, by providing a heated shield arrangement which is heated to or above the evaporation temperature of the source material to be deposited, molecules of the evaporated source material leaving the one or more outlets, e.g. nozzles, under a large angle hit the wall around the one or more apertures of the heated shield arrangement but cannot stick to the heated shield arrangement. As a result, the one or more apertures of the heated shield arrangement remain clean throughout the deposition process and clogging of the one or more apertures of the heated shield arrangement can be avoided.

[0035] According to embodiments described herein, the heated shield arrangement may be configured to be heated to an evaporation temperature of about 100°C to about 600°C, particularly to an evaporation temperature of about 150°C to about 450°C. In some embodiments, the heated shield arrangement may include a material being chemically inert to, for instance, evaporated organic material. According to some embodiments, the heated shield arrangement may include at least one material selected from the group consisting of: stainless steel, quartz crystal glass, Ta, Ti, Nb, DLC, and graphite or may include a coating with at least one of the named materials. Accordingly, accumulation of evaporated source material on the heated shield arrangement can be prevented.

[0036] As exemplarily shown in FIG. 1, according to embodiments which can be combined with any other embodiments described herein, the first cooling shield arrangement 201 may be configured to laterally surround the one or more outlets 212 of the distribution unit 130. In particular, the first cooling shield arrangement 201 can be configured to be actively cooled to a condensation temperature of the source material to be deposited. Accordingly, the first cooling shield arrangement is configured to collect evaporated source material which is back scattered from the heated shield arrangement. Further, beneficially the one or more outlets of the distribution unit remain clean throughout the deposition process and clogging of the one or more outlets of the distribution unit can be avoided such that stable deposition process conditions can be maintained for a long time.

[0037] According to some embodiments, which can be combined with other embodiments described herein, the first cooling shield arrangement 201 can be provided by one or more metal plates having conduits for cooling fluid, such as air, nitrogen, water or other appropriate cooling fluids. For example, the conduits for cooling fluid may be attached to the first cooling shield arrangement or provided within the first cooling shield arrangement. Additionally, or alternatively, the first cooling shield arrangement may include a thermoelectric cooling device or any other cooling device suitable for the first cooling shield arrangement. According to some embodiments, the first cooling shield arrangement may include at least one material selected from the group consisting of: Cu (e.g. covered with a Ni-plating), Ta, Ti, Nb, DLC, and graphite or may include a coating with at least one of the named materials.

[0038] According to embodiments which can be combined with any other embodiments described herein, the one or more outlets 212 of the distribution unit 130 may be provided in a heated wall 135 of the distribution unit, as exemplarily shown in FIG. 1. For example, heated wall 135 may include heating elements. The heating elements may be mounted or attached to the heated wall 135. Additionally or alternatively, the heating elements may be arranged within the heated wall 135 of the distribution unit. For example, the heating elements may be thermoelectric heating devices. In particular, the heated wall 135 is configured to be heated to a second temperature which substantially corresponds to the first temperature to which the heated shield arrangement is heated. Accordingly, the heated wall and the heated shield arrangement may be configured to have a substantially identical thermal expansion, such that the one or more outlets of the distribution unit which can be connected to the heated wall remain aligned with respect to the one or more apertures of the heated shield arrangement throughout the deposition process.

[0039] According to some embodiments which can be combined with any other embodiments described herein, the heated shield arrangement 202 and the heated wall 135 of the distribution unit 130 are configured to exhibit a substantially identical thermal expansion. For example, the heated shield arrangement 202 and the heated wall 135 of the distribution unit 130 may be made of the same material. Additionally or alternatively, as described above, the heated shield arrangement 202 and/or the heated wall 135 of the distribution unit 130 may include heating elements which are heated such that the thermal expansion of the heated shield arrangement 202 and the thermal expansion of the heated wall 135 are identical. For example, in the case that the heated shield arrangement 202 is made of a material having a higher thermal expansion than the material of which the heated wall 135 is made of, the heated wall 135 of the distribution unit 130 may be heated to a higher temperature than the heated shield arrangement 202 in order to provide for an identical thermal expansion. Accordingly, beneficially the position of the one or more outlets of the distribution unit, which can be connected to the heated wall, remain aligned with respect to the position of the one or more apertures of the heated shield arrangement throughout the deposition process.

[0040] With exemplarily reference to FIG. 2, according to embodiments which can be combined with any other embodiments described herein, the heated shield arrangement 202 of the evaporation source 100 may be connected via a connection element 232 with the heated wall 135 of the distribution unit 130. Accordingly, the alignment of the position of the one or more outlets of the distribution unit with the position of the one or more apertures of the heated shield arrangement can be improved.

[0041] According to some implementations, the connection element 232 may be configured for adjusting a distance between the heated wall 135 of the distribution unit 130 and the heated shield arrangement 202. For example, connection element 232 may be configured to move the heated shield arrangement 202 with respect to the heated wall 135. Accordingly, it is to be understood that by adjusting the distance between the heated wall 135 of the distribution unit 130 and the heated shield arrangement 202, the emission angle (Θ) of evaporated source material behind the heated shield arrangement can be adjusted. For example, by increasing the distance between the heated wall 135 of the distribution unit 130 and the heated shield arrangement 202, the emission angle (Θ) of evaporated source material behind the heated shield arrangement can be decreased. Accordingly, shadowing effects of a mask provided between the heated shield arrangement and the substrate can be reduced, resulting in an improved resolution of deposited source material on a substrate.

[0042] According to embodiments which can be combined with any other embodiments described herein, the evaporation source 100 includes second cooling shield arrangement 203, as exemplarily shown in FIG. 2. In particular, the second cooling shield arrangement 203 may be arranged in the deposition direction 101 behind the heated shield arrangement 202. As exemplarily shown in FIG. 2, the second cooling shield arrangement 203 includes one or more openings 223 which are arranged to be aligned in the deposition direction 101 with the one or more apertures 222 of the heated shield arrangement 202. Accordingly, by providing a second cooling shield arrangement which is arranged in deposition direction behind the heated shield arrangement, the heat load at the mask 20 and/or the substrate 10 can be decreased, which may be beneficial for achieving an improved resolution of deposited source material on the substrate. [0043] According to embodiments which can be combined with any other embodiments described herein, the one or more outlets 212 of the distribution unit 130 are one or more nozzles 125, as exemplarily shown in FIG. 2. In particular, the one or more nozzles 125 may be arranged and configured to extend along the deposition direction 101. More particularly, the one or more nozzles 125 may be arranged and configured to protrude from the one or more openings 221 of the first cooling shield arrangement 201. For example, the one or more nozzles 125 may protrude from the one or more openings 221 of the first cooling shield arrangement 201 in a direction towards the substrate, e.g. the deposition direction 101, by a distance of 2 mm or more, particularly 4 mm or more, more particularly 5 mm or more. Accordingly, the one or more outlets of the distribution unit can be prevented or even eliminated such that stable deposition process conditions can be maintained over a long time.

[0044] FIG. 3A to FIG. 3C show portions of an evaporation source according to embodiments described herein. As shown in FIG. 3A, the evaporation source can include a distribution unit 130 or a distribution pipe 106, and an evaporation crucible 104. For example, the distribution unit 130 or the distribution pipe 106, can be an elongated tube with a heating unit 215. The evaporation crucible can be a reservoir for a source material, such as an organic material to be evaporated by a crucible heating element 225.

[0045] According to embodiments, which can be combined with other embodiments described herein, a plurality of openings and/or outlets, such as nozzles, may be arranged along a length direction of the evaporation source. In particular, the plurality of openings and/or outlets may be arranged along a length direction of the distribution unit or distribution pipe. According to an alternative embodiment, one elongated opening extending along the length direction of the evaporation source and/or the length of the distribution unit, e.g. the distribution pipe, can be provided. For example, the elongated opening can be a slit. [0046] According to some embodiments, which can be combined with other embodiments described herein, the distribution unit, e.g. the distribution pipe, extends essentially vertically in a length direction. For example, the length of the distribution unit or the distribution pipe, corresponds at least to the height of the substrate to be deposited in the deposition apparatus. In many cases, the length of the distribution unit, particularly the distribution pipe, will be longer than the height of the substrate to be deposited, at least by 10% or even 20%>, which allows a uniform deposition at the upper end of the substrate and/or the lower end of the substrate.

[0047] According to some embodiments, which can be combined with other embodiments described herein, the length of the distribution unit, particularly the distribution pipe, can be 1.3 m or above, for example 2.5 m or above. According to one configuration, as shown in FIG. 3 A, the evaporation crucible 104 is provided at the lower end of the distribution unit 130 or the distribution pipe 106. Typically, the source material is evaporated in the evaporation crucible 104. The evaporated source material enters at the bottom of the distribution pipe and is guided essentially sideways through the plurality of openings in the distribution pipe, e.g. towards an essentially vertical oriented substrate.

[0048] According to some embodiments, which can be combined with other embodiments described herein, the plurality of outlets, e.g. the one or more outlets of the distribution unit, are arranged to have a main emission direction to be horizontal +/- 20°. According to some specific embodiments, the main emission direction can be oriented slightly upward, e.g. to be in a range from horizontal to 15° upward, such as 3° to 7° upward. Similarly, the substrate can be slightly inclined to be substantially perpendicular to the evaporation direction, which may reduce the generation of undesired particles.

[0049] FIG. 3B shows an enlarged schematic view of a portion of the evaporation source, in particular of the distribution unit 130, e.g. the distribution pipe 106, connected to the evaporation crucible 104. A flange unit 233 may be provided, which is configured to provide a connection between the evaporation crucible 104 and the distribution pipe 106. For example, the evaporation crucible and the distribution unit are provided as separate units, which can be separated and connected or assembled at the flange unit, e.g. for operation of the evaporation source. [0050] According to some embodiments, which can be combined with other embodiments described herein, the distribution unit 130, e.g. the distribution pipe 106, has an inner hollow space 210. Further, a heating unit 215 can be provided to heat the distribution unit 130, particularly the distribution pipe 106. The distribution unit 130 can be heated to a temperature such that the evaporated source material provided by the evaporation crucible 104 does not condense at an inner portion of the wall of the distribution unit 130, e.g. the distribution pipe 106. As exemplarily shown in FIG. 3B, two or more heat shields 217 can be provided around the tube of the distribution unit 130. The heat shields are configured to reflect heat energy provided by the heating unit 215 back towards the inner hollow space 210. Accordingly, the energy to heat the distribution unit 130, e.g. the distribution pipe 106, i.e. the energy provided to the heating unit 215, can be reduced because the heat shields 217 beneficially reduce heat losses. Heat transfer to other distribution units and/or to the mask or substrate can be reduced. According to some embodiments, which can be combined with other embodiments described herein, the heat shields 217 can include two or more heat shield layers, e.g. five or more heat shield layers, such as ten heat shield layers. [0051] Typically, as shown in FIG. 3B, the heat shields 217 include openings at positions of the outlets 212 in the distribution unit 130, e.g. the distribution pipe 106. The enlarged view of the evaporation source shown in FIG. 3B shows four outlets. The outlets 212 can be provided along a length direction of the distribution unit 130 or the distribution pipe 106. As described herein, the distribution unit 130 or the distribution pipe 106, can be provided as a linear distribution unit, particularly as a linear distribution pipe, having a plurality of openings (also referred to as one or more outlets herein) disposed therein. For instance, the distribution pipe may have one outlet. For instance, the distribution pipe may have more than 30 outlets, such as 40, 50 or 54 outlets arranged along a length direction of the distribution unit. According to embodiments herein, the outlets may be spaced apart from each other. For instance, the outlets may be spaced apart by a distance of 1 cm or more, for example, by a distance from 1 cm to 3 cm, like for example, by a distance of 2 cm.

[0052] A distribution unit, e.g. a distribution pipe, as understood herein has an enclosure, hollow space, or pipe, in which the material can be provided or guided, for example from the evaporation crucible. The distribution unit can have a plurality of openings (or an elongated slit) such that the pressure within the distribution unit is higher than outside the distribution unit. For example, the pressure within the showerhead can be at least one order of magnitude higher than that outside the distribution unit.

[0053] During operation, the distribution unit 130, e.g. the distribution pipe 106, is connected to the evaporation crucible 104 at the flange unit 233. The evaporation crucible 104 is configured to receive the source material to be evaporated and to evaporate the source material. FIG. 3B shows a cross-section through the housing of the evaporation crucible 104. As exemplarily shown in FIG. 3B, a refill opening can be provided, for example, at an upper portion of the evaporation crucible, which can be closed using a plug 252, a lid, a cover or the like for closing the enclosure of evaporation crucible 104.

[0054] With exemplary reference to FIG. 3B, an outer crucible heating element 225 can be provided within the enclosure of the evaporation crucible 104. The outer crucible heating element 225 can extend at least along a portion of the wall of the evaporation crucible 104. According to some embodiments, which can be combined with other embodiments described herein, additionally or alternatively one or more central heating elements can be provided. FIG. 3B shows two central heating elements. The first central heating element 226 and the second central heating element 228 can respectively include a first conductor 229 and a second conductor 230 for providing electrical power to the central heating elements.

[0055] According to some embodiments, which have been described herein, heat shields such as heat shield 217 and heat shield 227 can be provided for the evaporation source. The heat shields can reduce energy loss from the evaporation source, which also reduces the overall energy consumed by the evaporation source to evaporate a source material. However, as a further aspect, particularly for deposition of organic materials, heat radiation originating from the evaporation source, especially heat radiation towards the mask and the substrate during deposition can be reduced. Particularly for the deposition of organic materials on masked substrates, and even more for display manufacturing, the temperature of the substrate and the mask needs to be precisely controlled. Heat radiation originating from the evaporation source can be reduced or avoided by heat shields such as, for instance, heat shield 217 and heat shield 227.

[0056] These shields can include several shielding layers to reduce the heat radiation to the outside of the evaporation source. As a further option, the heat shields may include shielding layers, which are actively cooled by a fluid, such as air, nitrogen, water or other appropriate cooling fluids. According to yet further embodiments described herein, the one or more heat shields can include sheet metals surrounding respective portions of the evaporation source, for instance, surrounding the distribution pipe 106 and/or the evaporation crucible 104. According to embodiments herein, the sheet metals can have thicknesses of 0.1 mm to 3 mm, can be selected from at least one material selected from the group consisting of ferrous metals (SS) and non-ferrous metals (Cu, Ti, Al), and/or can be spaced with respect to each other, for example, by a gap of 0.1 mm or more.

[0057] According to some embodiments described herein and as exemplarily shown with respect to FIG. 3 A and FIG. 3B, the evaporation crucible 104 is provided at a lower side of the distribution unit 130. According to yet further embodiments, which can be combined with other embodiments described herein, a vapor conduit 242 may be provided at the central portion of the distribution unit 130 or at another position between the lower end of the distribution unit and the upper end of the distribution unit.

[0058] FIG. 3C illustrates an example of the evaporation source having a distribution pipe 106 and a vapor conduit 242 provided at a central portion of the distribution pipe. Evaporated source material generated in the evaporation crucible 104 is guided through the vapor conduit 242 to the central portion of the distribution pipes 106. The evaporated source material exits the distribution pipe 106 through a plurality of outlets 212. The distribution pipe 106 is supported by a support 102 as described with respect to other embodiments described herein. According to yet further embodiments herein, two or more vapor conduits 242 may be provided at different positions along the length of the distribution pipe 106. The vapor conduits 242 can either be connected to one evaporation crucible or to several evaporation crucibles. For example, each vapor conduit 242 can have a corresponding evaporation crucible 104. Alternatively, the evaporation crucible 104 can be in fluid communication with two or more vapor conduits 242, which are connected to the distribution pipe 106.

[0059] As used herein, the term "distribution pipe" may be understood as a pipe for guiding and distributing evaporated source material. In particular, the distribution pipe may guide evaporated source material from a crucible to a plurality of outlets (such as openings) in the distribution pipe. As used herein, the term "a plurality of outlets" typically includes at least two or more outlets. According to embodiments herein, the distribution pipe may be a linear distribution pipe extending in a first, particularly in a longitudinal direction. In embodiments described herein, the longitudinal direction may typically refer to the length direction of the distribution pipe. In some embodiments, the distribution pipe may include a pipe having the shape of a cylinder. The cylinder may have a circular bottom shape or any other suitable bottom shape, e.g. a triangular shape. [0060] For example, the distribution pipe can be a hollow cylinder. The term "cylinder" can be understood as commonly accepted as having a circular bottom shape and a circular upper shape and a curved surface area or shell connecting the upper circle and the lower circle. According to further additional or alternative embodiments, which can be combined with other embodiments described herein, the term cylinder can further be understood in the mathematical sense as having an arbitrary bottom shape and an identical upper shape and a curved surface area or shell connecting the upper shape and the lower shape. The cylinder does not necessarily need to have a circular cross-section.

[0061] FIG. 4A shows a schematic side view of a portion of an evaporation source according to embodiments herein, which can be combined with any other embodiments described herein. As shown in FIG. 4A, one or more outlets 212 of the distribution unit 130 are configured for providing a source material in the deposition direction 101 to the substrate 10, e.g. through a mask 20. Additionally, a first cooling shield arrangement 201 including one or more openings 221 is provided for collecting evaporated source material blocked by the heated shield arrangement 202 which is provided at a distance from the first cooling shield arrangement 201. The heated shield arrangement 202 includes one or more apertures 222 for confining an emission angle (Θ) of the evaporated source material provided through the one or more outlets 212. Further, a second cooling shield arrangement 203 is provided which is arranged in the deposition direction 101 behind the heated shield arrangement 202. The second cooling shield arrangement 203 can be provided by one or more metal plates having conduits for cooling fluid, such as air, nitrogen, water or other appropriate cooling fluids. For example, the conduits for cooling fluid may be attached to the second cooling shield arrangement or provided within the second cooling shield arrangement. Additionally, or alternatively, the second cooling shield arrangement may include a thermoelectric cooling device or any other cooling device suitable for first cooling shield arrangement. As exemplarily shown in FIG. 4 A, the second cooling shield arrangement 203 includes one or more openings 223 which are arranged to be aligned in the deposition direction 101 with the one or more apertures 222 of the heated shield arrangement 202. Accordingly, as shown in FIG. 4A, the evaporation source 100 is configured to define a path for the source material in the deposition direction 101 from the one or more outlets 212 through the one or more openings 221 and the one or more apertures 222 to the substrate, wherein a portion of evaporated source material provided from the one or more outlets 212 is blocked by the heated shield arrangement 202 such that a predetermined emission angle (Θ) behind the heated shield arrangement 202 can be provided.

[0062] With exemplary reference to FIG. 4B, according to some embodiments which can be combined with other embodiments described herein, at least one outlet of the one or more outlets 212, particularly each of the one or more outlets, may be provided with an individual heated shield arrangement 202 and/or an individual second cooling shield arrangement 203. For example, the one or more outlet(s) 212 may be one or more nozzle(s) for which an individual heated shield arrangement 202 and/or an individual second cooling shield arrangement 203 may be provided according to embodiments described herein. For example, in FIG. 5 an exemplary embodiment is shown in which one outlet 212 is provided with an individual heated shield arrangement 202 and an individual second cooling shield arrangement 203.

[0063] FIG. 5 shows a schematic top view of an evaporation source according to further embodiments herein which can be combined with any other embodiments described herein. In order to avoid unnecessary repetitions, only the differences with respect to the embodiments shown in FIGS. 1, 2 and 4 are described. The evaporation source shown in FIG. 5 includes a distribution unit 130, such as a distribution pipe 106, having a lateral cross section of triangular shape. The walls of the distribution unit may be heated by heating elements 380, which are mounted or attached to the walls. For reducing the heat radiation from the interior of the distribution unit to the exterior of the distribution unit, an outer shield 302 may be provided, which surrounds the distribution unit. Typically, the outer shield 302 may be cooled. For example, the outer shield can be provided by metal plates having conduits for cooling fluid, such as water, attached to the outer shield or provided within the outer shield. Additionally, or alternatively, an thermoelectric cooling device or another cooling device can be provided to cool the outer shield.

[0064] With exemplary reference to FIG. 5, according to some embodiments which can be combined with other embodiments described herein, a further cooling shield arrangement 211 may be provided. In particular, the further cooling shield arrangement 211 may be provided at a lateral distance around an outlet of the one or more outlets. In particular, the further cooling shield arrangement 211 may at least partially extends in the deposition direction 101, as exemplarily shown in FIG. 5. For example, the further cooling shield arrangement 211 may be L-shaped having a main portion extending in the deposition direction. Similarly to the first cooling shield arrangement the further cooling shield arrangement 211 may be configured to be cooled to a condensation temperature of a source material to be deposited on a substrate, as described herein. Accordingly it is to be understood, that evaporated source material which does not pass the apertures of the heated shield arrangement is back scattered to the further cooling shield arrangement 211 and/or to the first cooling shield arrangement 201 at which the evaporated source material condensates, such that the back scattered source material can be collected on the further cooling shield arrangement and/or on the first cooling shield arrangement. [0065] In some embodiments described herein, a substrate may be treated with evaporated source material that is deposited on the substrate 10 through a mask 20, for example, a shadow mask, as exemplarily shown in FIG. 5. For a deposition at high resolution of, for example, more than 800 pixels per inch, each pixel of evaporated source material formed at the surface of the substrate is typically formed by the evaporated source material emitted from more than one of the outlets of the evaporation source. For example, the evaporated source material from ten of the one or more outlets of the evaporation source may partake in the formation of each of the pixels formed at the surface of the substrate. It is to be understood that embodiments as described herein are particularly beneficial for the production of high resolution displays. In particular, by providing an evaporation source which is configured to block evaporated source material depending on the emission angle of the plume of evaporated source material provided from the one or more outlets in order to confine the emission angle (Θ) of the evaporated source material at a mask, shadowing effects of the mask can be reduced, resulting in an improved resolution of deposited source material on a substrate.

[0066] In embodiments described herein, the term "angle of the plume of evaporated source material from the one or more outlets" should be understood by the skilled person as including the angle of the plume of evaporated material from each of any number of outlets of the evaporation source.

[0067] FIG. 6 shows a schematic top view of an evaporation source according to yet further embodiments herein which can be combined with any other embodiments described herein. In order to avoid unnecessary repetitions, only the differences with respect to the embodiment shown in FIG. 5 are described. FIG. 6 shows an embodiment having three distribution units, e.g. three distribution pipes, which are provided over an evaporator control housing 402 adjacent to the distribution units and connected thereto via a thermal insulator 479. The evaporator control housing is configured to maintain an atmospheric pressure within the evaporator control housing and is configured to house at least one element selected from the group consisting of: a switch, a valve, a controller, a cooling unit, a cooling control unit, a heating control unit, a power supply, and a measurement device. In embodiments herein, a component for operating the evaporation source can be provided under atmospheric pressure close to the evaporation crucible and the distribution unit and can be moved through the deposition apparatus together with the evaporation source. [0068] In embodiments herein, a one or more outlets may be distributed along the length of each of the distribution units, e.g. distribution pipes 106, 107, 108, which may be configured as distribution pipes. Each distribution unit is in fluid communication with an evaporation crucible (not shown in FIG. 6). Each of the plurality of openings of each distribution unit, e.g. distribution pipes 106, 107, 108 has a main emission direction 101A, 101B, 101C for the evaporated source material. Due to the essentially triangular shape of the distribution units, the evaporation cones or plumes originating from the three distribution units are in close proximity to each other, such that mixing of the source materials from the different distribution units and outlets can be improved. It is to be understood that the heated shield arrangement 202 of the exemplary embodiment shown in FIG. 6 delimits the distribution cone or plume of evaporated source material distributed towards the substrate 10 and/or mask 20 from each of the distribution pipes, e.g. distribution pipes 106, 107, 108, in a similar manner as described with respect to FIGS. 1, 2, 4 and 5 above.

[0069] In view of the above, it is to be understood that embodiments of the evaporation source as described herein are configured to limit the angle of incidence of evaporated source material provided to a substrate, e.g. through a mask. In particular, by providing a heated shield arrangement which is heated to or above an evaporation temperature of the source material to be deposited and which is adapted to block evaporated source material having a predetermined emission angle (Θ) greater than 30°, in particular greater than 40°, e.g. greater than 45°, from a main emission direction, the angle of incidence of evaporated source material provided to a substrate, e.g. through a mask, can be limited in order to reduce shadowing effects of the mask. Accordingly, an improved resolution of deposited source material on a substrate can be provided. Further, by providing a first cooling shield arrangement which is configured to be cooled to a condensation temperature of the source material to be deposited and which is arranged around and behind the one or more outlets of the distribution unit, evaporated source material back scattered from the heated shield arrangement can be collected such that clogging of the one or more outlets of the distribution unit can be prevented. In view of that, molecules of evaporated source material leaving the nozzle at a small angle will get through the aperture. Molecules leaving the one or more outlets, e.g. nozzles, at a large angle will hit the wall around the one or more apertures of the heated shield arrangement but will not stick to the heated shield arrangement, since the heated shield arrangement is heated to or above the evaporation temperature of the source material to be deposited. Instead, the molecules will be back scattered and will hit the first cooling shield arrangement placed around the nozzles. Accordingly, the evaporated source material, e.g. evaporated source material used for OLED production, will condensate at the first cooling shield arrangement. As a result, the back scattered evaporated source material is collected on the first cooling shield such that the one or more apertures of the heated shield arrangement and the one or more outlets of the distribution unit remain clean, such that clogging can be prevented or even eliminated. Accordingly, embodiments as described herein provide for stable process conditions over a long time.

[0070] FIG. 7 shows a schematic top view of a deposition apparatus 150 for depositing a source material in a vacuum chamber 110, including an evaporation source 100 according to any embodiments described herein. According to some embodiments, which can be combined with other embodiments described herein, the evaporation source is configured for a translational movement and a rotation around an axis. According to typical embodiments herein, the evaporation source may have one or more evaporation crucibles and one or more distribution units, e.g. one or more distribution pipes. For instance, the evaporation source shown in FIG. 7 includes two evaporation crucibles 104 and two distribution units 130. As is shown in FIG. 7, a first substrate 121 and a second substrate 122 are provided in the vacuum chamber 110 for receiving evaporated source material.

[0071] According to embodiments herein, a mask assembly for masking a substrate can be provided between the substrate and the evaporation source. The mask assembly may include a mask and a mask frame to hold the mask in a predetermined position. In embodiments herein, one or more additional tracks may be provided for supporting and displacing the mask assembly. For instance, the embodiment shown in FIG. 7 has a first mask 133 supported by a first mask frame 131 arranged between the evaporation source 100 and the first substrate 121 and a second mask 134 supported by a second mask frame 132 arranged between the evaporation source 100 and the second substrate 122. The first substrate 121 and the second substrate 122 may be supported on respective transportation tracks (not shown in the figures) within the vacuum chamber 110.

[0072] FIG. 7 further shows a heated shield arrangement 202 according to embodiments herein, which is provided to block evaporated source material depending on the emission angle of the plume of evaporated source material provided from the one or more outlets in order to confine the emission angle (Θ) of the evaporated source material behind the heated shield arrangement in deposition direction, as described herein. In embodiments herein, if masks are used for depositing material on a substrate, such as in an OLED production system, the mask may be a pixel mask with pixel openings having the size of about 50 μιη x 50 μιη, or even below, such as a pixel opening with a dimension of the cross section (e.g. the minimum dimension of a cross section) of about 30 μιη or less, or about 20 μιη. In one example, the pixel mask may have a thickness of about 40 μιη. Considering the thickness of the mask and the size of the pixel openings, a shadowing effect may appear where the walls of the pixel openings in the mask shadow the pixel opening. It is to be understood that by providing an evaporation source as described herein, the shadowing effect may be reduced. Accordingly, an improved resolution of deposited source material on a substrate can be achieved. [0073] According to embodiments described herein, the substrates may be coated with a source material in an essentially vertical position. Typically, the distribution unit provides a line source extending essentially vertically. In embodiments described herein, which can be combined with other embodiments described herein, the term "essentially vertically" is understood, particularly when referring to the substrate orientation, to allow for a deviation from the vertical direction of 20° or below, e.g. of 10° or below. For example, this deviation can be provided because a substrate support with some deviation from the vertical orientation might result in a more stable substrate position. Yet, an essentially vertical substrate orientation during deposition of the source material is considered different from a horizontal substrate orientation. Particularly, the surface of the substrate is coated by a line source extending in one direction corresponding to one substrate dimension and a translational movement along the other direction corresponding to the other substrate dimension. [0074] The evaporation source 100 shown in FIG. 7 may be provided in the vacuum chamber 110 of the deposition apparatus 150 on a track, e.g. a looped track (not shown in the figures) or linear guide 120. The track or linear guide 120 is configured for the translational movement of the evaporation source 100. According to different embodiments, which can be combined with other embodiments described herein, a drive for the translational movement can be provided in the evaporation source 100, at the track or linear guide 120, within the vacuum chamber 110 or a combination thereof.

[0075] FIG. 7 further shows a valve 105, for example, a gate valve. The valve 105 allows for a vacuum seal to an adjacent vacuum chamber (not shown in the figures). According to embodiments herein, the valve 105 can be opened for the transport of a substrate or a mask into and/or out of the vacuum chamber 110.

[0076] According to some embodiments, which can be combined with other embodiments described herein, a further vacuum chamber, such as maintenance vacuum chamber 111 is provided adjacent to the vacuum chamber 110. The vacuum chamber 110 and the maintenance vacuum chamber 111 are connected by a valve 109. The valve 109 is configured for opening and closing a vacuum seal between the vacuum chamber 110 and the maintenance vacuum chamber 111. According to embodiments herein, the evaporation source 100 can be transferred to the maintenance vacuum chamber 111 while the valve 109 is in an open state. Thereafter, the valve can be closed to provide a vacuum seal between the vacuum chamber 110 and the maintenance vacuum chamber 111. If the valve 109 is closed, the maintenance vacuum chamber 111 can be vented and opened for maintenance of the evaporation source 100 without breaking the vacuum in the vacuum chamber 110.

[0077] The described material deposition arrangement may be used for various applications, including applications for OLED device manufacturing including processing methods, wherein two or more source materials such as, for instance, two or more organic materials are evaporated simultaneously. In the example shown in FIG. 7, two or more distribution units and corresponding evaporation crucibles are provided next to each other.

[0078] Although the embodiment shown in FIG. 7 provides a deposition apparatus with a movable evaporation source, the skilled person may understand that the above described embodiments may also be applied to deposition systems in which the substrate is moved during processing. For instance, the substrates to be coated may be guided and driven along stationary material deposition arrangements.

[0079] Embodiments described herein particularly relate to deposition of organic materials, e.g. for OLED display manufacturing on large area substrates. According to some embodiments, large area substrates or carriers supporting one or more substrates may have a size of at least 0.174 m ² . For instance, the deposition system may be adapted for processing large area substrates, such as substrates of GEN 5, which corresponds to about 1.4 m ² substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m ² substrates (1.95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7 m ² substrates (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m ² substrates (2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can similarly be implemented.

[0080] According to embodiments herein, which can be combined with other embodiments described herein, the substrate thickness can be from 0.1 to 1.8 mm and the holding arrangement for the substrate can be adapted for such substrate thicknesses. However, particularly the substrate thickness can be about 0.9 mm or below, such as 0.5 mm or 0.3 mm, and the holding arrangements are adapted for such substrate thicknesses. Typically, the substrate may be made of any material suitable for material deposition. For instance, the substrate may be made of a material selected from the group consisting of glass (for instance soda-lime glass or borosilicate glass), metal, polymer, ceramic, compound materials, carbon fiber materials or any other material or combination of materials which can be coated by a deposition process.

[0081] FIG. 8 A shows a schematic block diagram illustrating a method 800 of depositing a source material on a substrate according to embodiments described herein. The method includes evaporating 810 the source material and applying 820 the evaporated source material to the substrate. Further, applying 820 the evaporated source material to the substrate may include providing 821 the evaporated source material through one or more outlets of a distribution unit in a deposition direction and passing 822 the evaporated source material through one or more openings of a first cooling shield arrangement and through one or more apertures of a heated shield arrangement. In particular, embodiments of the method of depositing a source material as described herein are conducted by employing an evaporation source according to embodiments described herein.

[0082] According to embodiments herein, which can be combined with other embodiments described herein, the method of depositing a source material on a substrate may include heating the heated shield arrangement to or above the evaporation temperature of the source material to be deposited. Accordingly, accumulation of evaporated source material on the heated shield arrangement can be prevented. In particular, clogging of the one or more apertures of a heated shield arrangement can be prevented or even be eliminated.

[0083] With exemplary reference to FIG. 8B, according to further embodiments which can be combined with any other embodiments described herein, the method may include collecting 830 a portion of evaporated source material which has been blocked by the heated shield arrangement on the first cooling arrangement. Accordingly, the one or more outlets of the distribution unit remain clean throughout the deposition process and clogging of the one or more outlets of the distribution unit can be avoided or even be eliminated such that stable deposition process conditions can be maintained for a long time.

[0084] Accordingly, in view of the above, it is to be understood that embodiments of the method of depositing a source material on a substrate as described herein provide for preventing or even eliminating clogging of the one or more apertures of the heated shield arrangement and the one or more outlets of the distribution unit such that stable process conditions over a long time can be achieved. Further, embodiments of the method of depositing a source material on a substrate as described herein provide for reducing shadowing effects and improved resolution of deposited source material on a substrate, e.g. for high resolution display production, particularly high resolution OLED displays.

[0085] This written description uses examples to disclose the disclosure, including the best mode, and also to enable any person skilled in the art to practice the described subject-matter, including making and using any devices or systems and performing any incorporated methods. While various specific embodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if the claims have structural elements that do not differ from the literal language of the claims, or if the claims include equivalent structural elements with insubstantial differences from the literal language of the claims.