APPARATUS

TECHNICAL FIELD

[1] The present disclosure generally relates to evaporation sources, the deposition of source materials and to systems, apparatuses and methods for depositing materials, e.g. organic materials. Embodiments of the present disclosure relate to an apparatus for generating a vapor stream and particularly an organic material vapor stream suitable for creating OLED devices in a vacuum deposition system. In particular, the present disclosure relates to evaporation sources for the evaporation of organic materials, e.g. for use in deposition systems for manufacturing devices, particularly devices including organic materials therein.

BACKGROUND

[2] Techniques for layer deposition on a substrate include, for example, thermal evaporation, physical vapor deposition (PVD), and chemical vapor deposition (CVD). Coated substrates may be used in several applications and in several technical fields. For instance, coated substrates may be used in the field of organic light emitting diode (OLED) devices. OLEDs can be used in the manufacture of television screens, computer monitors, mobile phones, other hand-held devices, and the like for displaying information. Organic evaporators are a tool for the production of organic light-emitting diodes (OLEDs). OLEDs are a special type of light-emitting diode in which the emissive layer comprises a thin film of certain organic compounds. 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.

[3] An OLED device, such as an OLED display, may include one or more layers of an organic material situated between two electrodes that are deposited on a substrate. An OLED display, for example, may include layers 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.

[4] There are many challenges encountered in the manufacture of OLED display devices. OLED displays or OLED lighting applications include a stack of several materials, which are for example evaporated in a vacuumed system. The organic materials are typically deposited in a predetermined pattern that is defined by a mask. For the fabrication of OLEDs 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.

[5] For evaporation of the material to be deposited, crucibles may be used. The crucibles are provided with thermal energy to heat the material in the crucible and to evaporate the material which may be provided in a solid form, e.g. powder. However, the use of crucibles includes several drawbacks. For example, it is difficult to ensure proper evaporation of the organic material, particularly for a long term period.

[6] During processing, the substrate can be supported on a carrier configured to hold the substrate in alignment with a mask. The vapor from a vapor generator or source is directed toward the substrate through the mask to create a patterned film on the substrate. One or more materials may be deposited onto the substrate through one or more masks to create barely visible pixels that can be addressed individually to create functional devices such as full color displays.

[7] In light of the above, an improved evaporation of the material to be deposited would be beneficial to ensure high quality deposition of evaporated materials, particularly in the manufacture of OLED devices.

SUMMARY

[8] According to an aspect, an evaporation apparatus for evaporating a material is provided. The evaporation apparatus includes a container for the material, and a heating assembly. The heating assembly includes an outer heating unit at least partially provided around the container, and a mesh structure within the container. The outer heating unit is configured to provide a temperature gradient within the container.

[9] According to an aspect, an evaporation apparatus for evaporating a material is provided. The evaporation apparatus includes a container and a heating assembly. The heating assembly includes an outer heating unit at least partially provided around the container and a mesh structure within the container. The evaporation apparatus may further include a force unit coupled to the mesh structure.

According to an aspect, an evaporation apparatus for evaporating a material is provided. The evaporation apparatus includes a container for storing solid material to be evaporated and a mesh structure within the container arranged to be below the solid material, and a vapor guiding conduit below the mesh structure.

[10] According to an aspect, a deposition apparatus to deposit material on a substrate in a vacuum chamber is provided. The deposition apparatus includes a vacuum chamber, an evaporation apparatus according to embodiments described herein being provided in the vacuum chamber, and a distribution assembly in fluid communication with the evaporation apparatus to guide evaporated material towards the substrate.

[11] According to an aspect, a method for evaporating a material with an evaporation apparatus is provided. The method includes providing a temperature gradient within a container comprising a heating assembly at least partially provided around the container, the heating assembly comprising an outer heating unit and a mesh structure within the container.

[12] According to an aspect, a method for evaporating a material with an evaporation apparatus is provided. The method includes heating material to be evaporated with a mesh structure within a container and providing a force between the mesh structure and the material with respect to each other.

[13] Embodiments are also directed at apparatuses for carrying out the disclosed methods and include apparatus parts for performing each described method aspect. These method aspects may be performed by way of hardware components, a computer programmed by appropriate software, by any combination of the two or in any other manner. Furthermore, embodiments according to the disclosure are also directed at methods for operating the described apparatus. It includes method aspects for carrying out every function of the apparatus.

BRIEF DESCRIPTION OF THE DRAWINGS [14] So that the manner in which the above recited features of the present disclosure can be understood in detail, a more particular description of the disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the disclosure and are described in the following:

FIG. 1 shows an evaporation apparatus according to embodiments described herein;

FIG. 2 shows an enlarged view of a part of the evaporation apparatus according to embodiments described herein;

FIG. 3 shows an evaporation apparatus according to embodiments described herein; FIG. 4 shows a deposition assembly according to embodiments described herein; FIG. 5 shows a deposition apparatus according to embodiments described herein; FIG. 6 shows a flow diagram of a method according to embodiments described herein; and

FIG. 7 shows a deposition apparatus according to embodiments described herein.

DETAILED DESCRIPTION OF EMBODIMENTS

[15] 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. 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.

[16] Evaporation apparatuses can be provided as evaporation crucibles. Conventional evaporation crucibles include means for heating which are arranged at the outside of the evaporation crucible and provide a high temperature to the evaporation crucible and the material contained in the crucible. These evaporation crucibles allow only for poor conduction of the thermal energy necessary to commence and maintain evaporation of (solid) material particles. If material particles are not adjacent to the heated walls, incomplete evaporation may be a consequence.

[17] To ensure high quality and especially a long lifetime of the substrate to be coated i.e. of the e.g. OLED devices being manufactured, it is beneficial that the deposited organic layers are free of contaminants and free of thermal decomposition products. Decomposition products are produced when the organic material to be evaporated is exposed to excessive temperatures or is exposed for an extended time to otherwise acceptable temperatures.

[18] To approach this objective, conventional vapor generation systems have utilized crucibles having a sufficiently low volume of organic material designed such that the organic material is consumed before significant thermal decomposition has occurred. However, in practice frequent interruption of the deposition process to exchange crucibles is conducted, resulting in a subsequent loss in productivity and increase in operating costs.

[19] Accordingly, it is beneficial to provide a vapor generation system where the organic material is exposed to lower temperatures in the vapor generating apparatus and to high temperatures for shorter periods of time compared to conventional vapor generation systems; the reduced thermal exposure resulting in less thermal decomposition of sensitive organic materials and enabling the fabrication of OLED devices with enhanced efficiency and especially enhanced lifetime. Further, it is beneficial to provide a vapor generation system allowing continuous operation of the vapor generating apparatus even as organic material is being replenished.

[20] According to embodiments described herein, an evaporation apparatus for evaporating a material is provided. The evaporation apparatus includes a container for the material and a heating assembly. The heating assembly includes an outer heating unit at least partially provided around the container and a mesh structure within the container. The outer heating unit is configured to provide a temperature gradient within the container.

[21] According to embodiments described herein, an evaporation apparatus for evaporating material to be used in a deposition process is provided. A heating assembly is provided with the container to evaporate the material. The heating assembly includes an outer heating unit to provide a temperature gradient to the container. The heating unit includes a mesh structure, the mesh structure being provided within the container. The mesh structure may include a first surface and a second free surface. The mesh structure i.e. the first surface of the mesh structure may be in direct contact with a surface of the material to be deposited. The mesh structure may be heated to a temperature that allows for evaporation of the material adjacent to the mesh structure.

[22] According to embodiments described herein, an evaporation apparatus for evaporating a material is provided. The evaporation apparatus includes a container and a heating assembly. The heating assembly includes an outer heating unit at least partially provided around the container and a mesh structure within the container. The evaporation apparatus may include a force unit coupled to the mesh structure. The force unit may be coupled to the mesh structure. The force unit may provide a force to the mesh structure, allowing the mesh structure to be located at a surface of the material within the container.

[23] FIG. 1 shows an evaporation apparatus according to embodiments described herein. The evaporation apparatus 100 includes a container 105 and a heating assembly 110. The heating assembly includes an outer heating unit 115 and a mesh structure 120. The mesh structure 120 may be provided within the container 105. A force unit 125 may be coupled to the mesh structure 120. A material to be evaporated may be provided within the container 105. The container 105 may be a crucible-like arrangement. The heating assembly 110 i.e. the outer heating unit 115 may provide a temperature to the container. Particularly, a temperature gradient may be provided by the outer heating unit 115. The temperature range of the temperature gradient provided by the outer heating unit may be below an evaporation temperature T _E of the material to be deposited.

[24] According to embodiments described herein, the outer heating unit may provide a temperature gradient. The term“temperature gradient” as used throughout the disclosure, may be understood as a temperature progression established within the container of the evaporation apparatus. For example, the temperature at a bottom of the container may be lower than a temperature at a top of the container. The differences in temperature of the temperature gradient may include temperature differences in a range of 20°C to 300°C from the heating mesh position to the bottom of the container. For example, the outer heating unit may include several heaters being at least partially provided around the container and being arranged from bottom to top or vice versa of the container in a substantially vertical direction of the container. The maximum temperature difference of the temperature gradient provided by the outer heating unit may be lower than an evaporation temperature T _E of the material to be evaporated and/or deposited, for example at least 50 °C lower.

[25] Advantageously, the temperatures provided by the outer heating unit may be lower than the evaporation temperature of the material to be evaporated. Thus, thermal decomposition of bulk material in the container may be prevented. The material in the container remains free from thermally decomposed material. Thus, the formation of contaminants in the evaporated material being deposited on a substrate is prevented or reduced.

[26] The terms“material” or“material to be evaporated” or“material to be deposited” as used throughout the disclosure, may be understood as a material that is suitable for being deposited on a substrate in a deposition process. The material may be provided as a solid material and/or a liquid material. For example, the material may be provided in a powder form. The powder form may include material particles including a surface area. According to embodiments, the material may be directly transitioned from a solid phase into a gaseous phase, for example, the material may sublimate at a certain temperature depending on the material used. Additionally or alternatively, the material may be a material that is transitioned from a solid phase to a liquid phase and then to a gaseous phase, for example, the material may liquefy at a certain temperature and then may evaporate at another higher temperature.

[27] According to embodiments described herein, the heating assembly 110 may include a mesh structure 120. The mesh structure 120 may be provided within the container 105. A temperature of the mesh structure may be regulated. Particularly, the mesh structure is heated. A portion of the mesh structure may be in direct thermal contact with the material to be evaporated. The portion being in direct contact may heat the material to be evaporated to the same temperature as the mesh structure due to the large surface area of interaction, the infiltration of the material to be evaporated within at least a portion of the mesh structure and the very short thermal path between the heated elements of the mesh structure through the material to be evaporated. For example, the mesh structure may be heated to a temperature that is sufficient to allow for evaporation of the material to be evaporated in the container. For example, the temperature of the mesh structure may be varied depending on the evaporation temperature of the material in the container and/or a predetermined deposition rate. Particularly, the mesh structure may be provided at a surface of the material in the container.

[28] The term“a surface of the material” as used herein, may be understood as the uppermost area of the material particles in the container that is free from contact with other material particles. Additionally or alternatively, the “surface of the material” may be understood as the material particle layer that is in contact with an inner space of the container that is free from material and facing the desired vapor transport direction. The uppermost material particle layer may include a layer thickness of 2 to 3 mm.

[29] Accordingly, only a small portion of the material provided in the container is heated to high temperatures, i.e. temperatures close or at an evaporation temperature. Accordingly, high temperatures are provided for a comparable short time period and decomposition of material can be reduced or avoided.

[30] According to embodiments described herein, the mesh structure 120 may be oriented substantially horizontally with respect to the orientation of the container 105. The mesh structure 120 may be a porous mesh. The mesh structure 120 may be coupled to a force unit 125. The force unit 125 may be configured to maintain the mesh structure at a position i.e. at the surface of the material. Additionally or alternatively, the mesh structure may be movable. The force unit may exert a force to the mesh structure. For example, the force unit 125 may push the mesh structure 120 towards the bottom of the container i.e. towards the surface of the material. The force unit may be a spring.

[31] Alternately, as exemplarily shown in FIG. 7, the orientation of the mesh structure 120 and the material 720 to be evaporated may be inverted. In this configuration, the material to be evaporated may be maintained in contact with or may exert a force on the mesh structure due to gravity, with or without the assistance of a force unit. According to some embodiments, which can be combined with other embodiments described herein, the material can be provided in a container 105 above the mesh structure 120. The weight of the material provides the force of the mesh structure and the material relative to each other. The evaporated material may be guided through one or more conduits to a distribution assembly. [32] The material to be evaporated may be prevented from falling through the mesh structure by the small pore size of the mesh structure, which, despite being larger than the average particle size of the material to be evaporated, still may prevent the powder from passing through. Vapor on the other hand will freely pass through the mesh structure. Materials which liquify before becoming gaseous i.e. before subliming will advantageously be drawn into the mesh structure by capillary force.

[33] According to some embodiments, which can be combined with other embodiments described herein, other aspects, features and details of evaporation apparatuses described herein, for example with respect to FIGS 1 to 3 and in the independent and dependent claims may be combined with an arrangement as shown in FIG. 7.

[34] The terms“substantially horizontal direction” or“substantially horizontal” may be understood as an extension in an x-direction of a Cartesian coordinate system. In other words, these terms may be understood as an extension in a 90° angle ± 10° from a perpendicular direction. The terms“substantially vertical direction” or“substantially vertical” may be understood as an extension in a y-direction of a Cartesian coordinate system. In other words, these terms may be understood as an extension in a 90° angle ± 10° from a horizontal direction.

[35] According to embodiments, the mesh structure 120 may be provided within the container by a magnetic holding arrangement. The magnetic holding arrangement may be located at an outside of the container with a magnetic force directed to the inside of the container and to the mesh structure. The position of the mesh structure within the container may be varied according to a fill height of material in the container.

[36] According to embodiments described herein, the container 105 may include a wall providing an inner area and an outer area of the container. The outer heating unit 115 may be provided at the outer area. The outer heating unit 115 is configured to heat the container for facilitating providing a temperature gradient for the material to be deposited. For example, the temperature gradient may result in higher temperatures at a position close to the mesh as compared to a position further away from the mesh. According to some embodiments, the outer heating unit 115 may be in contact with the wall of the container 105. According to some embodiments, which can be combined with other embodiments described herein, a shield arrangement 112 may be provided. The outer heating unit 115 may be adjacent to or arranged at the shield arrangement 112. The shield arrangement may include one or more, for example, two or more shields. The shield arrangement 112 is configured to reduce heat radiation of the container and the outer heating unit, for example, towards the outer area surrounding the container. According to embodiments described herein, the container may be at least partially surrounded by a radiation shield 118. For example, the radiation shield 118 may be arranged around the shield arrangement.

[37] According to embodiments that can be combined with any other embodiment described herein, a vacuum may be applied to the evaporation apparatus. For example, the evaporation apparatus may be provided in a vacuum chamber. A vacuum generation module, e.g. one or more vacuum pumps, may be provided with the vacuum chamber to generate vacuum conditions in the vacuum chamber. The vacuum conditions may be adjusted depending on the process that is carried out.

[38] Advantageously, the evaporation apparatus as provided herein allows for an improved evaporation of material to be deposited. In particular, the evaporation of the material may be provided at the surface of the material in the container. Having the evaporated material at the surface of the bulk material facilitates the escape of vapor towards a distribution assembly. Further advantageously, a decomposition of the material provided inside the container may be prevented due to excessive temperature exposure or due to a prolonged time of temperature exposure. Thus, the overall demand of material is decreased while the efficiency of the evaporation of the material is increased. Thus, process costs are reduced as well as the energy for evaporation.

[39] FIG. 2 shows an enlarged view of a part of the evaporation apparatus according to embodiments described herein. According to embodiments described herein, the mesh structure 120 may be thermally conductive. For example, the mesh structure may be made of a thermally conductive material. The mesh structure 120 may be made of a material including a low thermal mass. For example, the mesh structure 120 may be made of carbon, more particularly of glassy carbon. Additionally or alternatively, the mesh structure 120 may include a coated surface. The coated surface may be a silicon carbide coating. The coating thickness may range between 1 pm and 30 pm, particularly from 5 pm to 20 pm, more particularly from 10 pm to 15 pm. Providing a low thermal mass of the material of the mesh structure enables fast heating and fast cooling of the mesh structure.

[40] According to embodiments described herein, the mesh structure may be porous. In other words, the mesh structure may include openings to allow for the escape of evaporated material. The open area of the mesh structure may be in the range of 50% to 99%, particularly in the range of 70% to 99%, more particularly in a range of 90% to 99%. The term“open area“ as used herein, may be understood as the porous area of the mesh structure. For example, the mesh structure may include an open area of 97%.

[41] According to embodiments, the evaporation apparatus may include a cooling mesh 122. In particular, the container 105 may include the cooling mesh 122. The cooling mesh 122 may be arranged adjacent to the mesh structure 120. The cooling mesh may be made particularly of a material having a thermal conductivity of > 20 W/m °K. Particularly, the evaporation apparatus may include the cooling mesh when a material is evaporated that liquefies before evaporation. The cooling mesh may be substantially horizontally arranged adjacent to the mesh structure 120 in the container 105. For example, the cooling mesh may be provided between the mesh structure 120 and a bottom of the container 105. Particularly, the cooling mesh may be spaced apart from the mesh structure 120 in a range of about 0.1 mm to 10 cm, particularly in a range of about 1 mm to 5 cm, more particularly in a range of about 2 mm to 1 cm.

[42] The evaporation apparatus may include a temperature measurement unit e.g. a temperature sensor for measuring the temperature of the material to be evaporated at the mesh structure 120 and/or at the cooling mesh 122.

[43] Advantageously, the temperature measurement unit allows for an accurate temperature measurement of the material being evaporated at the mesh structure providing close thermal contact to the surface of the material such that the material is rapidly heated. Additionally, the mesh structure allows for continuously delivering a latent heat of evaporation energy necessary to sustain evaporation to overcome the very low thermal conductivity of the material to be evaporated in vacuum.

[44] Vapor molecule trajectories directed into the container or liquefied material may be prevented from the condensing on the cooling mesh structure since the evaporated material and/or the liquefied material may solidify in the cooled material situated between the mesh and the cooling mesh. The cooled solidified material between the cooling mesh and the mesh structure may thus act as a consumable shield for the cooling mesh, so that condensate never collects on the cooling mesh. [45] According to embodiments, the mesh structure and the cooling mesh may provide conditions where only a thin section of organic material at the free surface of the mesh structure is exposed to temperatures sufficient for evaporation. Advantageously, an expanded surface area of interaction between the material and the mesh arrangement is created. When the mesh structure is made of a glassy carbon foam, for example, there can be 65 cm ² of surface area per cubic centimeter of foam volume. The thin section of organic material may at least partially infiltrate the open mesh structure, particularly when the organic material liquifies before sublimating and may be transported by capillary action into the foam structure. The surface area of interaction between the heated mesh structure and the organic material is thereby far greater than the apparent free surface area of the organic material. The enlarged surface area of interaction in combination with a >90% open area of the mesh structure may optimize the evaporation rate for a given temperature of the mesh structure and may allow the free escape of most generated vapor molecules towards a distribution assembly. Thus, the evaporated material may have a relatively unimpeded escape path through a thin material depth at the free surface of the organic material and through the mesh structure.

[46] Further advantageously, the mass of the container and the mass of the material are decoupled from the heat generation and evaporation components of the apparatus. This decoupling allows evaporation to be initiated and interrupted in seconds by delivering or interrupting energy delivery to the mesh structure. The mass of the container and the mass of a majority of the material is not at a high temperature, i.e. evaporation temperatures. An interruption of the evaporation is not delimited by reducing the temperature of the container and the powder in the container. Due to the comparably small mass of the mesh evaporating the material, the temperature of the mesh can be reduced comparably fast below a temperature for evaporation. This results in the advantage that material utilization efficiency is improved, and the time needed for cleaning and replacement of components of the evaporation apparatus is reduced.

[47] According to embodiments described herein, the evaporation apparatus may include a transition area to connect the container 105 with a distribution assembly 260. The transition area or the distribution assembly may include an inner radiation shield 152. The distribution assembly may be heated to a temperature above the evaporation temperature to prevent condensation of the evaporated material at walls of the distribution assembly. For example, the temperature of the distribution assembly may be higher than the temperature of the container. The inner radiation shield may be configured to minimize heat radiation from the distribution assembly to the inside of the container or the material provided inside the container, i.e. the material inside the evaporation apparatus.

[48] Advantageously, the inner radiation shield 152 prevents the heat generated by the distribution assembly from entering the evaporation apparatus. As such, an increase in temperature above the evaporation temperature for a long time span is prevented. Accordingly, decomposition of the material to be evaporated may be efficiently prevented or avoided.

[49] FIG. 3 shows an evaporation apparatus according to embodiments described herein. The evaporation apparatus may include a container 105 and a heating assembly 110. The heating assembly may include an outer heating unit 115 and a mesh structure 120. The evaporation apparatus may include a force unit 125. The evaporation apparatus may be connected to a distribution assembly 260. The distribution assembly may include an inner radiation shield 152. The evaporation apparatus may include a material feeding system 130.

[50] According to embodiments, the material feeding system may cooperate with the container 105 to maintain an essentially constant fill height in the container. Thus, the material fill height in the container may be maintained constantly to maintain a constant container geometry. Advantageously, this may lead to more stable process conditions. According to embodiments, the material feeding device 136 may include a constant force loading element. The constant force loading element may be configured to keep the mesh structure 120 in contact with the material surface under a constant force. The material feeding device may be connected to the container at a material feed outlet. Further, the material feeding system may allow for increased evaporation times between maintenance.

[51] The material feeding system, in particular the material feeding device may provide a material feeding rate of the material from the material reservoir to the container. For example, the material feeding device promotes the material by acting on the material with a force directed towards the container resulting in a feed rate or feed velocity. The feed rate or feed velocity may be adapted according to the fill height of material in the container. For example, a controller may regulate the feed velocity.

[52] According to embodiments, the cross-sectional area of the material feed outlet of the material feeding device 136 may be smaller than a cross-sectional area of the container 105. This may be beneficial to compensate variations in the feed rate or feed velocity. Further advantageously, variations in the material fill height may be minimized even when there are variations in the material feed rate. The material feed outlet can be referred to as the outlet from the conduit of the material feeding system, the conduit being connected to the container.

[53] According to embodiments, the material feeding system 130 may continuously provide material to the container. The material feeding system 130 may include a material reservoir 132 and a material feeding device 136. The material feeding system 130, e.g. the material feeding device 136, may be connected to the container 105. For example, the material feeding device 136 may connect the material reservoir 132 to the container 105. The material feeding system 130 may provide material to be evaporated to the container 105. The material feeding system may be provided in the vacuum chamber together with the container 105 or outside the vacuum chamber.

[54] Advantageously, a portion of the material feeding system located outside the vacuum chamber allows for easy refilling of the material reservoir. The material in the material feeding system may remain under vacuum conditions and the refill procedure may be completed without interrupting the evaporation in the container or deposition process.

[55] According to embodiments described herein, the evaporation apparatus may be a continuous system. A“continuous system” as used herein may be understood as a system where the provision of material may be ensured continuously, meaning that the material may be fed to the container where evaporation of the material takes place. Further, it may be understood that a continuous system may also include the refilling of the material feeding system. Additionally or alternatively, a“continuous system” may be understood as a system where evaporation of material e.g. for being deposited on a substrate is performed over an extended period of time without being interrupted.

[56] According to embodiments described herein, the evaporation apparatus may be a continuous and refillable vapor generation system where only a thin cross section of organic material powder at the free surface of the mesh structure is exposed to vaporization energy while the bulk of the powder is maintained at a temperature far below the effective vaporization temperature.

[57] In light of the above, a combination of the evaporation apparatus with a mesh structure raising the temperature of the material to evaporation temperatures only shortly before evaporation and/or having material at comparably low temperatures in the container and of the material feeding system allows for evaporation over a long period of time. Material can be fed into the system and the material in the system is provided with reduced decomposition due to the lower temperatures.

[58] According to embodiments described herein, the material reservoir 132 may include a material feed inlet 134 for constantly providing the material from the material reservoir to the material feeding device. The material reservoir 132 may be separated from the material feed inlet 134 by a sieving element 137. The material feed inlet 134 may be connected to the material feeding device 136. The material feed inlet 134 may be a funnel-shaped part of the material reservoir 132. The funnel-shape is beneficial to facilitate provision of the material to the material feeding device.

[59] According to embodiments described herein, the sieving element 137 may be a sieve with a pore size that allows for the material in the material reservoir to pass the sieving element 137. In particular, the sieving element 137 may be used in conjunction with solid material, more particularly, with solid material particles. The sieving element may be configured to allow for a constant fill height of material at the material feed inlet. Advantageously, the sieving element 137 may regulate the amount of material passing from the material reservoir to the material feed inlet of the material reservoir. The sieving element may enable a controlled feeding of material that is then transported to the container 105 via the material feeding device 136. Further advantageously, the processes of feeding and refilling the material feeding system are decoupled from each other. This allows for refilling and storing the material independent from feeding the material. Further advantageously, the sieving element may keep the process conditions essentially constant, even when a refill rate of the material reservoir does not exactly match the evaporation rate in the container on a short term and/or a longer-term basis.

[60] According to embodiments, the material feeding system may include a refill section 138. The refill section 138 may be connected to the material reservoir 132. The material feeding system may include a containment valve 140. The containment valve may be operable between a refill configuration and a storing configuration. The containment valve 140 may connect the refill section 138 and the material reservoir 132.

[61] According to embodiments described herein, the containment valve 140 may be a split butterfly valve. The containment valve may include a first section and a second section. The first section may be arranged with the material reservoir. The second section of the containment valve may be movable. The first section may include a first part of a sealing unit and the second section may include a second part of the sealing unit within the containment valve. The containment valve may be in an open position when the first section and the second section are in contact with each other. In particular, the containment valve may be in an open position when the first part and the second part of the sealing unit are joined together and rotated around an axis of the sealing unit. The containment valve may be in a closed position when the first section and the second section are spaced apart from each other or when the first part and the second part of the sealing unit are spaced apart from each other.

[62] According to embodiments described herein and during refilling of the material reservoir, material may be provided to the refill section 138. The containment valve may be in a closed position. The material may reach the first section of the containment valve. The refill section may be closed after providing the material. The refill section may be vacuumed. The first section of the containment valve may be moved towards the second section of the containment valve and may be brought together with the second section of the containment valve. This allows for the first part and the second part of the sealing unit of the containment valve to be joined. The sealing unit may be moved around an axis. The axis of the sealing unit may be perpendicular to a symmetry axis of the containment valve. For example, the sealing unit is rotated around the axis in a range of 1 to 90°, particularly in a range of 45 to 90°. When the sealing unit is rotated, the material provided in the refill section may be transitioned to the material reservoir, i.e. the storage part of the material reservoir.

[63] Advantageously, such a containment valve allows for refilling the material feeding system without the need for disrupting the vacuum of the material feeding system. Further advantageously, the material feeding system being independent from the container but allowing for a continuous feed of material to the container, allows for refilling the material reservoir without interrupting the deposition process.

[64] Further advantageously, the evaporation apparatus as provided herein allows for a continuous deposition process where a stopping of the process e.g. for maintenance is redundant, since the evaporation and the provision of material are decoupled from each other. Even if the process has to be stopped, the evaporation apparatus provided herein includes the advantage of stopping the evaporation within seconds while reducing or preventing loss of material. Since only the mesh structure is heated to a temperature allowing for evaporation of the material, the evaporation process may be interrupted by solely downregulating the temperature of the mesh structure to a temperature that is not sufficient for evaporation of the material.

[65] FIG. 4 shows a deposition assembly according to embodiments described herein. The deposition assembly 200 may include an evaporation apparatus 100, particularly an evaporation apparatus as described with respect to FIGs. 1 to 3. The evaporation apparatus is configured to evaporate a material to be deposited on a substrate. Further, the deposition assembly 200 includes a distribution assembly 260 which can be an elongated tube. The distribution assembly may include one or more outlets. For instance, the one or more outlets may be nozzles. Typically, the nozzles are configured for directing a plume of evaporated material towards a substrate. The distribution assembly 260 may be in fluid communication with the evaporation apparatus 100. The distribution assembly may include three side walls.

[66] As exemplarily shown in FIG. 4, the distribution assembly 260 may be designed in a triangular shape. A triangular shape of the distribution assembly can be beneficial in the case that two or more distribution assemblies are arranged next to each other. In particular, a triangular shape of the distribution assembly 260 makes it possible to bring the outlets of neighboring distribution assemblies as close as possible to each other. This allows for achieving an improved mixture of different materials from different distribution assemblies, e.g. for the case of the co-evaporation of two, three or even more different materials. According to embodiments, the distribution assembly may have another shape such as a round shape, an oval shape or another polygon shape.

[67] According to embodiments, a heating unit 263 may be provided for heating the distribution assembly. The heating unit may be mounted or attached to all or only some of the three side walls of the distribution assembly. The heating unit 263 may be similar to the outer heating unit 115 described with respect to the evaporation apparatus. The heating unit may provide a constant temperature to the distribution assembly 260 that is higher than the highest temperature provided to the evaporation apparatus 100.

[68] Accordingly, the distribution assembly 260 can be heated to a temperature such that the evaporated material, which is provided by the evaporation apparatus, does not condense at an inner portion of the wall of the distribution assembly 260. According to embodiments, the deposition assembly 200, in particular the distribution assembly 260 may include an inner radiation shield as described with respect to FIGs. 2 and 3. [69] As exemplarily shown in FIG. 4, the deposition assembly 200 may include a shielding device 266, particularly a shaper shielding device, to delimit the distribution cone of evaporated material provided to a substrate. In particular, the shielding device may be configured to reduce the heat radiation towards the deposition area. Further, the shielding device may be cooled by a cooling arrangement 267. For example, the cooling element 267 may be mounted to a back side of the shielding device 266 and may include one or more cooling channels or a conduit for providing a cooling fluid.

[70] Accordingly, the distribution assembly can be a linear distribution showerhead, for example, having a plurality of openings (or an elongated slit) disposed therein. Further, typically the distribution assembly can have an enclosure, hollow space, or pipe, in which the evaporated material can be provided or guided, for example from the evaporation crucible to the substrate. According to embodiments which can be combined with any other embodiments described herein, the length of the distribution assembly may correspond at least to the height of the substrate to be deposited. In particular, the length of the distribution assembly may be longer than the height of the substrate to be deposited, at least by 10% or even 20%. For example, the length of the distribution assembly can be 1.3 m or above, for example 2.5 m or above. Accordingly, a uniform deposition at the upper end of the substrate and/or the lower end of the substrate can be provided. According to an alternative configuration, the distribution assembly may include one or more point sources which can be arranged along a vertical axis.

[71] According to embodiments described herein, a plurality of deposition assemblies may be combined. For example, two or more deposition assemblies may be combined. The plurality of deposition assemblies may include a plurality of evaporation apparatuses described according to any of the embodiments herein. For instance, the plurality of deposition assemblies may include two, three, four or more evaporation apparatuses, each of which may be connected to a distribution assembly. For example, three aligned evaporation apparatuses may be connected to three distribution assemblies.

[72] FIG. 5 shows a deposition apparatus according to embodiments described herein. The deposition apparatus 500 may be configured to deposit an evaporated material on a substrate 10. The deposition apparatus 500 includes a deposition chamber 570, particularly a vacuum deposition chamber. In the embodiment of the deposition apparatus 500 as shown in FIG. 5, the deposition apparatus 500 includes a deposition or deposition assembly 200 according to any of the embodiments described herein in the vacuum deposition chamber and a distribution assembly 220 to deposit the evaporated deposition material. Additionally, the deposition assembly may include an evaporation apparatus 100 and the distribution assembly 220 as described in embodiments herein. The distribution assembly 220 may further comprise a heating unit.

[73] 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 0.5 m ² or more, particularly 1 m ² or more. For instance, the deposition apparatus 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. For example, for OLED display manufacturing, half sizes of the above mentioned substrate generations, including GEN 6, can be coated by evaporation of an apparatus for evaporating material. The half sizes of the substrate generation may result from some processes running on a full substrate size, and subsequent processes running on half of a substrate previously processed.

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

[75] According to embodiments described herein, the material may be deposited in a predetermined pattern on the substrate, e.g. by using a mask such as a fine metal mask (FMM) having a plurality of openings. A plurality of pixels may be deposited on the substrate. Other examples of evaporated materials include one or more of the following: ITO, NPD, Alq3, Quinacridone, and metals such as silver or magnesium.

[76] According to some embodiments, which can be combined with any other embodiments described herein, the deposition chamber may be a vacuum deposition chamber. In the present disclosure, a“vacuum deposition chamber” can be understood as a chamber configured for vacuum deposition. The term“vacuum”, as used herein, can be understood in the sense of a technical vacuum having a vacuum pressure of less than, for example, 10 mbar. Typically, the pressure in a vacuum chamber as described herein may be between 10 ⁵ mbar and about 10 ⁸ mbar, more typically between 10 ⁵ mbar and 10 ⁷ mbar, and even more typically between about 10 ⁶ mbar and about 10 ⁷ mbar.

[77] According to some embodiments, the pressure in the vacuum chamber may be considered to be either the partial pressure of the evaporated material within the vacuum chamber or the total pressure (which may approximately be the same when only the evaporated material is present as a component to be deposited in the vacuum chamber). In some embodiments, the total pressure in the vacuum chamber may range from about 10 ⁴ mbar to about 10 ⁷ mbar, especially in the case that a second component besides the evaporated material is present in the vacuum chamber (such as a gas or the like).

[78] As exemplarily shown in FIG. 5, the deposition assembly 200 can be provided on a track or linear guide 564. The linear guide 564 may be configured for the translational movement of the deposition assembly 200. Further, a drive for providing a translational movement of the deposition assembly 200 can be provided. In particular, a transportation apparatus for contactless transportation of the material deposition arrangement source may be provided in the vacuum deposition chamber.

[79] As exemplarily shown in FIG. 5, the deposition chamber 570 may have gate valves 565 via which the vacuum deposition chamber can be connected to an adjacent routing module or an adjacent service module. Typically, the routing module is configured to transport a substrate to a further vacuum deposition apparatus for further processing and the service module is configured for maintenance of the deposition source. In particular, the gate valves allow for a vacuum seal to an adjacent vacuum chamber, e.g. of the adjacent routing module or the adjacent service module, and can be opened and closed for moving a substrate and/or a mask into or out of the vacuum deposition apparatus. [80] According to embodiments which can be combined with any other embodiments described herein, a substrate may be processed in the deposition apparatus. Particularly, two substrates, e.g. a first substrate and a second substrate, can be supported on respective transportation tracks within the deposition chamber 570. Further, two tracks for providing masks 563 thereon can be provided. In particular, the tracks for transportation of a substrate carrier and/or a mask carrier may be provided with a further transportation apparatus for contactless transportation of the carriers.

[81] Typically, depositing the material on the substrates may include masking the substrates by respective masks, e.g. by an edge exclusion mask or by a shadow mask. According to typical embodiments, the masks, e.g. a first mask corresponding to a first substrate and a second mask corresponding to a second substrate, are provided in a mask frame to hold the respective mask in a predetermined position.

[82] As shown in FIG. 5, the linear guide 564 provides a direction of the translational movement of the deposition assembly 200. On both sides of the deposition assembly 200, a mask 563, e.g. a first mask for masking the first substrate and second mask for masking the second substrate, can be provided. The masks can extend essentially parallel to the direction of the translational movement of the deposition assembly 200. Further, the substrates at the opposing sides of the deposition source can also extend essentially parallel to the direction of the translational movement.

[83] With exemplary reference to FIG. 5, an assembly support 561 configured for the translational movement of the deposition assembly 200 along the linear guide 564 may be provided. Typically, the assembly support 561 supports the evaporation apparatus 100 and the distribution assembly 220 provided over the crucible assembly, as schematically shown in FIG. 5. Accordingly, the evaporated material generated in the evaporation apparatus can move upwardly and out of the one or more outlets of the distribution assembly. Accordingly, as described herein, the distribution assembly is configured for providing evaporated material, particularly a plume of evaporated organic material, from the distribution assembly 220 to the substrate 10.

[84] FIG. 6 shows a flow diagram of a method 600 for evaporating a material with an evaporation apparatus according to embodiments described herein. Box 610 includes providing a temperature gradient within a container 105. The container includes a heating assembly 110 at least partially provided around the container. The heating assembly 110 includes an outer heating unit 115 and a mesh structure 120 within the container 105. The container 105, the heating assembly 110, the heating unit 115 and the mesh structure 120 may be provided according to any embodiment described herein.

[85] According to embodiments, the container may provide a material to be deposited on a substrate. The material may be stored in the container and evaporated at the mesh structure within the container. The mesh structure may be heated to an evaporation temperature T _E of the material to be deposited. The heating unit may provide a temperature gradient that includes a temperature range that is below the evaporation temperature T _E of the material to be deposited. This allows for storing and evaporating material in parallel.

[86] Box 620 may include feeding the material via a material feeding device 136 being coupled to a material feeding system 130. The material feeding system may be provided according to embodiments described herein.

[87] According to embodiments, the material feeding system may provide fresh material to the container for evaporating the material at the mesh structure. The material feeding system may be configured to store the material while simultaneously feeding the material to the container. Additionally, the material feeding system may allow an easy refilling without disturbing the feeding and/or the deposition process.

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

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