Method of coating a substrate and evaporation source arrangement

Abstract

A method of coating a substrate (10) in a vacuum chamber is described. The substrate has a structure formed thereon comprising a first sidewall (11) adjacent to a pixel region (13) and a first overhang (12) projecting from the first sidewall (11) partially over the pixel region (13). The method includes arranging a first evaporation source (101) in a first deposition position, the first evaporation source having a first vapor distribution pipe (110) with a first row of nozzles (111) that have a first main evaporation direction (M1); and transporting the substrate (10) past the first evaporation source (101) while directing a first material toward the substrate from the first row of nozzles (111). In the first deposition position, the first main evaporation direction (M1) is tilted relative to a surface normal (SN) of the substrate by a first tilt angle (α1) to either increase or decrease a deposition of the first material under the first overhang (12). Material layers of an OLED layer stack can be deposited on the substrate.

Description

METHOD OF COATING A SUBSTRATE AND EVAPORATION SOURCE ARRANGEMENTTECHNICAL FIELD

[0001] Embodiments of the present disclosure relate to methods and apparatuses for coating substrates with a stack of layers. More particularly, embodiments of the present disclosure relate to evaporation source arrangements and vacuum deposition systems for depositing materials of an OLED layer stack on a substrate, in particular without the use of a fine metal mask (FMM) with pixel holes. Metal layer(s) and / or organic layer(s) of an OLED layer stack can be deposited on a substrate, e.g., subsequently and / or synchronously by co-deposition. Embodiments of the present disclosure specifically relate to evaporation source arrangements and vacuum deposition systems as well as to methods of OLED display manufacturing by thermal evaporation.BACKGROUND

[0002] An organic light-emitting diode (OLED) is a light-emitting diode in which an electroluminescent layer is a film of organic compounds that emits light in response to an electric current. Since OLEDs emit light directly without involving backlight and color filters, the color gamut and viewing angles possible with OLED displays are greater than those of traditional LCD displays. Furthermore, OLEDs can be manufactured on flexible substrates, and accordingly, they can be utilized in a variety of applications. Organic light emitting diodes (OLEDs) are used in the manufacture of television screens, computer monitors, mobile phones, other hand-held devices, etc., for displaying information. OLEDs can also be used for general space illumination. An OLED display, for example, may include layers of organic material situated betweentwo electrodes that are deposited on a substrate in a manner so as to form a matrix display panel having individually energizable pixels.

[0003] Organic materials and metallic materials are deposited on a substrate in a vacuum processing chamber for OLED manufacturing. Metallic materials are employed as, for example, electrode materials or electron injection layer (EIL) materials. The materials to be deposited are evaporated using an evaporation source arrangement, and the evaporated materials are deposited onto a substrate through nozzles. Metallic materials are typically evaporated in an evaporation source at a temperature of 1 ,000°C or above, or of 1 ,500°C or above. Organic materials are typically evaporated in an evaporation source arrangement at temperatures between 250°C and 500°C.

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

[0005] OLED pixels can be deposited onto a substrate through fine metal masks FMMs (also referred to as pixel masks) that have a plurality of small pixel holes that define individual pixel areas on the substrate. A precise alignment between the FMM and the substrate is necessary for the pixel deposition, which is challenging since each of the small pixels includes a plurality of organic layers that are to be deposited on top of each other on a respective anode.

[0006] Another technique for forming OLED pixels on a substrate uses photo lithography to pattern pixels instead of using fine metal masks (FMMs). Here, a structure that acts as a masking layer is formed directly on the substrate before the actual pixel deposition. Alignment issues can be reduced. However, quickly and reliably coating a substrate with an OLED layer stack without FMMs requires complex equipment and is also challenging.

[0007] In view of the above, it would be beneficial to provide methods of quickly and reliably coating a substrate with an OLED layer stack, particularly without a use of fine metal masks (FMMs). Furthermore, improved evaporation source arrangements, vacuum deposition systems, and device manufacturing methods adapted for OLED manufacturing would be beneficial.SUMMARY

[0008] In light of the above, methods of coating a substrate in a vacuum chamber, and evaporation source arrangements for depositing two or more materials onto a substrate according to the independent claims are provided. Further aspects, benefits, and features of the present disclosure are apparent from the claims, the description, and the accompanying drawings.

[0009] According to an embodiment, a method of coating a substrate in a vacuum chamber is provided. The substrate has a structure formed thereon comprising a first sidewall adjacent to a pixel region and a first overhang projecting from the first sidewall. The coating is carried out by an evaporation source arrangement with a first evaporation source that includes a first vapor distribution pipe with a first row of nozzles that have a first main evaporation direction. The evaporation source can optionally have further vapor distribution pipes, wherein each vapor distribution pipe has a respective row of nozzles that have a respective main evaporation direction. The first vapor evaporation pipe, and particularly all the vapor evaporation pipes of the evaporation source, may have one single row of nozzles.

[0010] The method includes: arranging the first evaporation source in a first deposition position, and transporting the substrate past the first evaporation source arranged in the first deposition position, while directing a first material toward the substrate from the first row of nozzles. In the first deposition position, the first main evaporation direction is tilted relative to a surface normal of the substrate by a first tilt angle to either increase or decrease a deposition of the first material under the first overhang.

[0011] In one embodiment, the first main evaporation direction is inclined relativeto the surface normal of the substrate by a first tilt angle of 10° or more, particularly 30° or more, to increase a material deposition under the first overhang. In other words, the first row of nozzles is tilted “toward” the region under the first overhang such as to increase the deposition under the first overhang and particularly to coat the substrate with a material layer that contacts the first sidewall.

[0012] In another embodiment, the first main evaporation direction is inclined relative to the surface normal of the substrate by a first tilt angle of 10° or more, particularly 30° or more, to decrease a material deposition under the first overhang. In other words, the first row of nozzles is tilted “away from” the region under the first overhang so as to decrease the deposition under the first overhang and particularly to coat the substrate with a material layer while ensuring that the material layer does not contact the first sidewall.

[0013] The first distribution pipe may include one single row of nozzles, and the one single row of nozzles may be tilted relative to the surface normal of the substrate so that more vapor material enters the region below the overhang as compared to a position of the first distribution pipe in which the first main evaporation direction is perpendicular to the substrate surface. The first vapor distribution pipe may be essentially vertical, and the nozzles of the first row may extend along a length direction of the first vapor distribution pipe, i.e., in an essentially vertical direction to provide a vertical line source.

[0014] The structure formed on the substrate may include adjacent pixel-defining layer (PDL) structures that define (sub-)pixel regions of the device. Sidewalls and inorganic overhangs that project from the sidewalls at least partially over the (sub-)pixel regions may be disposed on an upper surface of the PDL structures and may act as a “mask” that is directly formed on the substrate.

[0015] The first evaporation source may optionally be rotatable, e.g., using a rotation drive, so that the first evaporation source can be rotated to the first deposition position, in which nozzles are tilted.

[0016] According to another aspect described herein, an evaporation source arrangement for depositing two or more materials onto a substrate that has a structurewith an overhang formed thereon is provided. The evaporation source arrangement includes a first evaporation source including a first vapor distribution pipe with a first row of nozzles that have a first main evaporation direction for depositing a first material onto the substrate and a second vapor distribution pipe with a second row of nozzles that have a second main evaporation direction for depositing a second material onto the substrate. The evaporation source arrangement further includes a rotation drive for rotating the first evaporation source around a rotation axis, and a controller configured to cause a rotation of the first evaporation source to a first deposition position prior to a transport of the substrate past the first evaporation source. In the first deposition position, the first main evaporation direction is tilted relative to a surface normal of the substrate by a first tilt angle to either increase or decrease a deposition of the first material under the overhang.

[0017] According to another aspect described herein, an evaporation source arrangement for depositing two or more materials onto a substrate is provided. The evaporation source arrangement includes a first evaporation source with two or more vapor distribution pipes including a first vapor distribution pipe with a first row of nozzles for depositing a first material onto the substrate. The two or more vapor distribution pipes define a front side of the first evaporation source directed toward a substrate transport path and arranged opposite to a rear side of the first evaporation source. In a first deposition position of the first evaporation source, the front side of the first evaporation source is tilted relative to the substrate transportation path by a first subangle, and a front surface of the first vapor distribution pipe that is provided with the first row of nozzles is tilted relative to the front side of the first evaporation source by a second sub-angle, wherein a sum of the first sub-angle and the second sub-angle defines a first tilt angle of the first main evaporation direction relative to a surface normal of the substrate.

[0018] Optionally, the evaporation source arrangement may further include a rotation drive for rotating the first evaporation source around a rotation axis, and a controller configured to cause a rotation of the first evaporation source to the first deposition position prior to a transport of the substrate past the first evaporation source.

[0019] According to another embodiment, a vacuum deposition system is provided.The vacuum deposition system includes a vacuum chamber; an evaporation source arrangement according to any of the embodiments described herein and in the vacuum chamber, and a substrate transport system for transporting substrate past the first evaporation source along the substrate transportation path for coating the substrate with one or more layers.

[0020] According to a further aspect described herein, an evaporation source arrangement for depositing two or more materials onto a substrate that has a structure with an overhang formed thereon is provided. The evaporation source arrangement includes a first evaporation source including a first vapor distribution pipe with a first row of nozzles that have a first main evaporation direction for depositing a first material onto the substrate and a second vapor distribution pipe with a second row of nozzles that have a second main evaporation direction for depositing a second material onto the substrate. The evaporation source arrangement includes a shaper shield arranged in front of the first row of nozzles to limit an opening angle of vapor plumes emitted by the first row of nozzles. The shaper shield is configured to shape the vapor plumes emitted by the first row of nozzles to be asymmetrical relative to the first main evaporation direction. In particular, the shaper shield shapes the vapor plumes to be asymmetrical relative to the first main evaporation direction, so that, in horizontal sectional planes, a first half-angle of the vapor plumes on a first side of the main evaporation direction facing toward the first overhang is larger than a second half-angle of the vapor plumes on a second side of the main evaporation direction facing away from the first overhang. A material deposition on the second side of the first main evaporation direction facing away from the first overhang (i.e. , a material deposition on an uncovered substrate region) can be decreased in relation to a material deposition on the first side of the first main evaporation direction facing toward the region under the overhang (i.e., a material deposition in a region under the overhang). The aspect of “asymmetrical shaping of vapor plumes” can be combined with any of the other aspects described herein, particularly with the tilting of the first main evaporation direction relative to the surface normal. Specifically, the substrate can be coated with a tilted and / or asymmetrically shaped vapor plume for increasing a deposition in a region under the overhang in relation to a deposition of uncovered surface regions.

[0021] Embodiments are also directed at apparatuses for carrying out the disclosedmethods and include apparatus parts for performing each described method aspect. The 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 are also directed at methods for operating the described apparatus. The methods for operating the described apparatuses include method aspects for carrying out every function of the apparatus. Embodiments are also directed at methods of manufacturing processed substrates, particularly coated substrates, in a vacuum deposition system described herein and substrates manufactured in accordance with the methods and / or using the systems described herein, such as OLED substrates, particularly OLED displays. It is also possible for other devices than OLED displays to be manufactured using the apparatuses and methods described herein.BRIEF DESCRIPTION OF THE DRAWINGS

[0022] 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:

[0023] FIG. 1 shows a schematic view of a vacuum deposition system with an evaporation source arrangement according to embodiments of the present disclosure;

[0024] FIG. 2 shows a schematic view of an evaporation source arrangement according to embodiments of the present disclosure in a vertical sectional plane;

[0025] FIG. 3 shows a schematic view of an evaporation source arrangement according to embodiments of the present disclosure in a horizontal sectional plane;

[0026] FIGS. 4A and 4B illustrate two subsequent stages of a method of coating a substrate according to embodiments;

[0027] FIGS. 5A and 5B illustrate two subsequent stages of a method of coating a substrate according to embodiments;

[0028] FIGS. 6A and 6B illustrate two subsequent stages of a method of coating a substrate according to embodiments;

[0029] FIG. 7 shows an evaporation source arrangement in an idle position; and

[0030] FIG. 8 shows a schematic sectional view of a substrate with an OLED layer stack manufactured according to methods of the present disclosure.DETAILED DESCRIPTION

[0031] Reference will now be made in detail to the various embodiments, one or more examples of which are illustrated in each figure. Each example is provided by way of explanation and is not meant as a limitation. For example, features illustrated or described as part of one embodiment can be used on or in conjunction with any other embodiment to yield yet a further embodiment. It is intended that the present disclosure includes such modifications and variations.

[0032] Within the following description of the drawings, the same reference numbers refer to the same or to similar components. Generally, only the differences with respect to the individual embodiments are described. Unless specified otherwise, the description of a part or aspect in one embodiment can also apply to a corresponding part or aspect in another embodiment.

[0033] OLED pixels can be formed on a substrate using photo lithography and patterning, particularly without a fine metal mask (FMM). An FMM has a plurality of pixel holes and is positioned in front of the substrate and aligned relative to the substrate before the material deposition. OLED pixel patterning without FMMs is based on a structure that acts as a “mask” and is formed directly on the substrate before coating the substrate with a plurality of materials in a vacuum deposition system. The structure that is formed on the substrate may include sidewalls adjacent to pixel regions, particularly sidewalls surrounding the pixel regions, and overhang structures projecting from the sidewalls at least partially over the pixel regions, as is depicted exemplarily in FIG. 8.

[0034] FIG. 8 is a schematic sectional view showing a part of an OLED layer stack760 on a substrate 10 manufactured with OLED pixel patterning techniques. Adjacent pixel-defining layer (PDL) structures 715 are formed on an upper surface of the substrate 10 that define pixel regions, and overhang structures 720 are disposed on an upper surface of the PDL structures 715. The overhang structures 720 include a lower portion 720B with a sidewall and an upper portion 720A with an overhang protruding from the lower portion 720B partially over the pixel region 13. In FIG. 8, a first sidewall 11 adjacent to a pixel region 13 is schematically depicted, and a first overhang 12 projects from the first sidewall 11 partially over the pixel region 13. As will be appreciated, the pixel region 13 may be surrounded by two or more sidewalls, and overhangs may be formed on the two or more sidewalls and project over the pixel region from different sides.

[0035] By depositing various materials on the pixel regions to defined positions under the overhangs, in combination with subsequent etching / patterning, individually switchable pixels can be formed on the substrate. The deposition of metals and organic layers in predetermined regions, particularly under the overhangs, is challenging.

[0036] The lower portion 720B with the first sidewall 11 may be made of a conductive material that is intended to be in contact with a cathode layer 711 of the OLED layer stack 760 and allows a connection of the cathode layer 711 with a cathode potential. Alternatively or additionally, at least a part of the first sidewall 11 may include an assistant cathode 716 that is intended to be in contact with a cathode layer 711 of the OLED layer stack. The upper portion 720A with the overhang 12 may be made of a non-conductive inorganic material or alternatively of a conductive inorganic material.

[0037] The OLED layer stack 760 generally includes an anode layer 714, an optional hole injection layer H IL 718, at least one organic layer 713 (made of one or more optically active organic materials), an optional electron injection layer EIL 712, the cathode layer 711 , and at least one encapsulation layer 710.

[0038] As is shown in FIG. 8, the at least one organic layer 713 does not contact the first sidewall 11 , but the cathode layer 711 does contact the first sidewall 11 under the first overhang 12. For ensuring that the at least one organic layer 713 does not substantively contact the first sidewall 11 under the first overhang, the at least one organic layer 713 may be deposited with an organic vapor plume 732 having a smallopening angle. For ensuring that the cathode layer 711 reliably contacts the first sidewall 11 under the overhang, the cathode layer may be deposited with a metal vapor plume 731 having a large opening angle. However, vapor plumes with large opening angles may not always be beneficial, for example, because a vapor plume with a large opening angle causes a substantial shadowing effect that leads to stray coating of regions of the deposition system and of the substrate that should not be coated.

[0039] In view of the above, according to embodiments described herein, methods and apparatuses are described that allow a reliable deposition of OLED layer stacks on substrates, particularly on substrates with overhang structures formed thereon. For example, methods described herein may ensure or improve an electrical contact of a cathode layer with a conductive sidewall under an overhang, and / or may reduce or prevent a contact of an organic layer with a conductive sidewall under an overhang. A contact between the organic layer and the conductive sidewall degrades the contact and increases the contact resistance between the cathode layer (that is deposited above the organic layer) and the conductive sidewall. A low contact resistance between the cathode layer and the conductive sidewall is beneficial, e.g., in order to reduce or prevent an influence on the l-V-curve of the manufactured OLED device.

[0040] FIG. 1 shows a vacuum deposition system 1000 with evaporation source arrangements 100 according to embodiments described herein in a schematic top view. The vacuum deposition system 1000 includes a first vacuum chamber 1001 that houses a first evaporation source 101 , and optionally one or more further vacuum chambers that may house one or more further evaporation sources, e.g., a second evaporation source 102 and / or a third evaporation source 103. The evaporation sources may be configured to coat vertically or essentially vertically oriented substrates that are transported past the evaporation sources on a substrate transportation track 1013. A plurality of materials, that may include one or more metals and one or more organic materials, can be deposited in succession onto the substrate in order to provide a layer stack on the substrate, e.g., an OLED layer stack. For example, the vacuum deposition system 1000 may include 10 or more evaporation sources for coating the substrate with a plurality of layers.

[0041] In the present disclosure, a "vacuum deposition system" is to be understoodas a system or arrangement configured for vacuum deposition of materials on a substrate. A "vacuum chamber" or “vacuum processing chamber” is to be understood as a chamber configured for vacuum deposition. The term "vacuum", as used herein, can be understood in the sense of a technical vacuum having a vacuum pressure of less than, for example, 10 mbar. Typically, the pressure in a vacuum chamber as described herein may be between 10-5 mbar and approximately 10-8 mbar, particularly between 10-5 mbar and 10-7 mbar.

[0042] The vacuum deposition system 1000 may include a substrate transportation track 1013 configured to move a substrate 10 along a substrate transport path T past the first evaporation source 101 and past the optional further evaporation sources. The substrate transportation track 1013 may extend at least partially through the first vacuum chamber 1001 and through the optional further vacuum chambers and may include a substrate transportation system configured for substrate transport, e.g., a roller transportation system, one or more linear motors and / or a magnetic levitation system suitable for moving the substrate relative to and past the evaporation sources. The substrate may be carried by a substrate carrier 1020 during the transport and / or deposition.

[0043] The vacuum deposition system 1000 may further include a shield transportation track 1012 extending between the substrate transportation track 1013 and the first evaporation source 101 in the first vacuum chamber 1001. The shield transportation track 1012 is configured to move a movable shield 1030 in front of the substrate 10 for shielding one or more edge regions of the substrate 10 and / or for shielding at least parts of a substrate carrier 1020 that carries the substrate 10. The movable shield 1030 may be a movable edge exclusion shield with a shielding frame for covering one or more edge regions of the substrate. The shield transportation track 1012 may be located between the substrate transportation track 1013 and the first evaporation source 101 in the first vacuum chamber 1001 and may include a shield transportation system, e.g., a roller transportation system, one or more linear motors and / or a magnetic levitation system suitable to move the movable shield 1030 in front of the substrate 10, such that one or more edge regions of the substrate are covered during coating with the first evaporation source 101 , as is schematically depicted in FIG. 1.

[0044] The movable shield 1030 may be movable back and forth on the shield transportation track 1012, as is schematically indicated by respective arrows in FIG. 1 , such that subsequent substrates moved along the substrate transport path T can be shielded by the movable shield 1030 during coating with the first evaporation source 101 . Each evaporation source may have an associated movable shield that is movable back and forth on a respective shield transportation track for shielding an edge region of the substrate from being coated when the substrate is moved past the respective evaporation source.

[0045] Accordingly, an in-line system is provided that allows the deposition of a plurality of layers on a substrate in succession, while the substrate is moved past a plurality of evaporation sources through the vacuum deposition system 1000.

[0046] Embodiments described herein particularly relate to deposition of materials, e.g. for display manufacturing on large area substrates. According to some embodiments, large area substrates or substrate carriers supporting one or more substrates may have a size of 0.5 m2or larger, particularly of 1 m2or larger. For instance, the deposition system may be adapted for processing large area substrates, such as substrates of GEN 4.5, which corresponds to about 0.67 m2of substrate (0.73 m x 0.92 m), GEN 5, which corresponds to approximately 1 .4 m2(1 .1 m x 1 .3 m), GEN 6, which corresponds to approximately 2.7 m2(1.5 m x about 1.8 m), GEN 7.5, which corresponds to approximately 4.29 m2(1.95 m x 2.2 m), GEN 8.5, which corresponds to approximately 5.7 m2(2.2 m x 2.5 m), or even GEN 10, which corresponds to approximately 8.7 m2(2.85 m x 3.05 m). Even larger generations such as GEN 11 and GEN 12 and corresponding substrate areas can be implemented. According to yet further implementations, half sizes of the above-mentioned substrate generations can be processed. Alternatively or additionally, semiconductor wafers may be processed and coated in deposition systems according to the present disclosure.

[0047] FIG. 2 shows an evaporation source arrangement 100 according to embodiments described herein in further detail in a vertical sectional plane. In the present disclosure, an "evaporation source arrangement" is to be understood as an arrangement configured for material deposition by evaporation on a substrate. The evaporation source arrangement 100 may have one or more crucibles 112 configuredto evaporate a source material to be deposited and one or more vapor distribution pipes 110 configured for directing the evaporated material towards the substrate through a plurality of nozzles. For instance, a vapor distribution tube or vapor distribution pipe may provide a line source with a plurality of nozzles that are arranged in a row (or “line array”) one above the other along a longitudinal direction of the vapor distribution pipe. The row of nozzles may be provided along a longitudinal direction (typically an essentially vertical direction) of the vapor distribution pipe to provide an essentially vertical line source. Each vapor distribution pipe generally has one single row of nozzles, particularly one single vertical nozzle row suitable to coat substrates in an essentially vertical orientation. An “essentially vertical direction” as used herein relates to a direction that corresponds to the direction of gravity or deviates from the direction of gravity by less than 10°.

[0048] For instance, the source material to be deposited may be an inorganic material, particularly a metallic material for use as an electrode material or an electron transport layer material in an OLED layer stack, or the source material may be an organic material for organic light emitting diode (OLED) production.

[0049] As is schematically depicted in FIG. 2, the evaporation source arrangement 100 includes a first evaporation source 101 with at least a first vapor distribution pipe 110. Further vapor distribution pipes of the first evaporation source are not shown in FIG. 2, but may be present (see, e.g., FIG. 3, showing an evaporation source with three vapor distribution pipes). The first vapor distribution pipe 110 has a row of nozzles 111 that may be arranged along the longitudinal direction of the first vapor distribution pipe 110, e.g., above one another in an essentially vertical line array. The first evaporation source may, for example, be a line source for substrate coating in an essentially vertical orientation. The first evaporation source 101 may be configured to deposit one or more materials onto the substrate with one or more vapor distribution pipes arranged adjacent to each other, and the further evaporation sources may be configured to deposit one or more materials onto the substrate.

[0050] The first row of nozzles 111 includes a plurality of nozzles, particularly twenty or more nozzles. Each nozzle has a main evaporation direction. A “main evaporation direction” of a nozzle can be understood as a direction that is defined bythe nozzle channel and the nozzle opening of the nozzle (typically corresponding to a longitudinal direction of the nozzle channel). Generally, a generally cone-shaped vapor plume emitted by a nozzle is centered around the main evaporation direction of the nozzles, e.g., with a maximum of vapor particles of the plume propagating along the main evaporation direction. Specifically, a vapor plume emitted by a nozzle is defined by a main evaporation direction and by an opening angle of the plume.

[0051] A vapor plume can be rotationally symmetrical with respect to the main evaporation direction, and / or a vapor plume can be shaped with one or more shaper shields 201 to be symmetrical or to be asymmetrical relative to the main evaporation direction (= relative to the nozzle axis). A shaping of the vapor plumes emitted by the first row of nozzles 111 with a shaper shield 201 to be asymmetrical relative to the first main evaporation direction (in horizontal sectional planes) is schematically illustrated in FIG. 3.

[0052] If the nozzle channels of the nozzles of the first row are essentially parallel to each other, the nozzles of the first row have a corresponding first main evaporation direction relative to the substrate surface. Parallel vapor plumes propagating in the first main evaporation direction M1 are schematically depicted in FIG. 2. Accordingly, the first row of nozzles is characterized by a (common) main evaporation direction of the nozzles. For example, the first row of nozzles 111 of FIG. 2 has the first main evaporation direction M1. Other rows of nozzles described herein are defined by a respective main evaporation direction that is common among the nozzles of the respective row. Each vapor evaporation pipe generally has one single row of nozzles.

[0053] Depending on the opening angles of the emitted vapor plumes, some of the vapor material propagates into regions below an overhang. However, depending on the overhang size, it may be difficult to provide a reliable contact between the evaporation material and the first sidewall under the overhang. Furthermore, vapor plumes with large opening angles may be difficult to handle due to a lack of directionality and a shadowing effect in various directions.

[0054] The evaporation source arrangement 100 may further include a rotation drive 113 for rotating the first evaporation source 101 around a rotation axis, and a controller 114 for controlling the rotational movement of the first evaporation source101.

[0055] FIG. 3 shows a schematic view of an evaporation source arrangement 100 with a first evaporation source 101 according to embodiments described herein in a horizontal sectional plane. The first evaporation source 101 includes the first vapor distribution pipe 110 with the first row of nozzles 111 that have the first main evaporation direction M1. The vapor plumes of the first row of nozzles may be essentially parallel to each other, e.g., one above the other.

[0056] The first evaporation source 101 is arranged in a first deposition position, particularly by rotating the first evaporation source 101 around the rotation axis R1 to the first deposition position using the rotation drive. In the first deposition position, the first main evaporation direction M1 of the nozzles of the first row of nozzles 111 is tilted relative to a surface normal SN of the substrate by a first tilt angle a1 to either increase or decrease a deposition of the first material under the first overhang 12. The nozzle channels of the first row are not perpendicular to the substrate surface in some implementations. The substrate 10 is transported past the first evaporation source 101 in the first deposition position, while a first material is directed toward the substrate from the first row of nozzles 111.

[0057] In some embodiments, the first tilt angle a1 is 15° or more, particularly 30° or more, or even 45° or more, relative to the surface normal.

[0058] In some embodiments, the first main evaporation direction M1 is tilted “toward” the first overhang 12 to increase a deposition of the first material in a region under the first overhang 12 as compared to a main evaporation direction that is perpendicular to the substrate surface. Specifically, the first material may be a metal, particularly silver, and, in the first deposition position, the first main evaporation direction M1 is inclined to increase a contact area between the metal and the first sidewall under the first overhang. Using the first vapor distribution pipe 110, a cathode layer can be deposited that has an improved electrical contact with the first sidewall 11.

[0059] In some implementations, a first opening angle (a) of first vapor plumes emitted by the first row of nozzles may be 40° or more and 120° or less. A large openingangle (a) of the vapor plumes in combination with the first tilt angle (a1 ) leads to an increased material deposition below the overhang and can reliably ensure an electrical contact between the deposited first material and the first sidewall 11 . In view of the first tilt angle (a1 ) of the first main evaporation direction relative to the surface normal as described herein, a large first opening angle (a) that would lead to a substantial shadowing effect in all directions may not be necessary. For example, in some embodiments, the first tilt angle (a1 ) may be 25° or more and the first opening angle (a) may be between 40° and 80°, ensuring a material deposition under the overhang with an inclination angle of the outermost vapor particles of the vapor plumes of, e.g., 65° relative to the surface normal.

[0060] In various embodiments described herein that can be combined with other embodiments described herein, a shaper shield 201 is arranged in front of the first row of nozzles 111 for limiting the opening angle of the vapor plumes emitted by the first row of nozzles. The shaper shield 201 may limit the opening angle of the vapor plumes on (only) one side of the first main evaporation direction M1 or on two opposite sides of the first main evaporation direction M1 , as is schematically depicted in FIG. 3. For example, the shaper shield 201 may include an essentially vertical slit opening adapted to limit the vapor plumes on two opposite horizontal sides of the first main evaporation direction M1.

[0061] In some embodiments, the shaper shield 201 is configured to shape the vapor plumes to be asymmetrical relative to the first main evaporation direction M1 . In other words, a first sub-angle of the opening angle of the vapor plumes on a first side of the main evaporation direction M1 may be larger than a second sub-angle of the opening angle on a second side of the main evaporation direction M1 , as is schematically depicted in FIG. 3. Thereby, the deposition under the first overhang can be increased relative to the deposition in regions where the substrate is uncovered. More specifically, a ratio between a first deposition amount in a region under the first overhang and a second deposition amount on uncovered regions of the substrate can be increased. Or expressed differently: A thickness of the deposited material under the first overhang relative to a thickness of the deposited material on an uncovered substrate region can be increased by asymmetrically shaping the vapor plumes with the shaper shield. Further, vapor plumes having a better focus and / or a betterdirectionality can be provided. In particular, the shaper shield 201 as described herein can ensure that the opening angle of the vapor plumes emitted by the first row of nozzles is adapted to provide a suitable ratio between the thicknesses of the deposited layer in a region below the first overhang and in uncovered regions of the substrate. Optionally, a shaper shield as described herein with respect to the first row of nozzles can also be arranged in front of the second and / or third rows of nozzles.

[0062] In some embodiments, the first main evaporation direction M1 is tilted “away from” the first overhang 12 to decrease a deposition of the first material under the first overhang 12 as compared to a main evaporation direction that is perpendicular to the surface normal SN (see FIG. 6A). Specifically, the first material may be an organic material, and, in the first deposition position, the first main evaporation direction M1 is inclined to reduce or prevent a contact between the organic material and the first sidewall under the first overhang. Alternatively or additionally, a shaper shield 201 may be arranged in front of the first row of nozzles and may be configured to limit the vapor plumes emitted by the first row of nozzles to decrease or limit a deposition of organic material under the first overhang. In particular, the organic vapor plumes may be symmetrically or asymmetrically shaped by the shaper shield 201 to limit a deposition of the organic material under the first overhang to a first extent. The first extent may be smaller than a second extent to which a subsequently deposited metal layer reaches under the first overhang. Using the first vapor distribution pipe 110, an organic layer can be deposited that hardly reaches into the region below the overhang. A thin organic layer in a region below the overhang may facilitate an electrical contact between an overlying cathode layer and the sidewall, because there is more space below the overhang for the vaporized metal to reach the sidewall if an underlying organic layer is thin or not present under the overhang.

[0063] An evaporation source arrangement 100 as described herein includes a first evaporation source 101 with two or more vapor distribution pipes. A first vapor distribution pipe 110 has a first row of nozzles 111 that have a first main evaporation direction M1 for depositing a first material on the substrate, and a second vapor distribution pipe 120 has a second row of nozzles 121 that have a second main evaporation direction for depositing a second material on the substrate.

[0064] The evaporation source arrangement 100 may further include a rotation drive 113 for rotating the first evaporation source around a rotation axis R1 , and a controller 114 configured to cause a rotation of the first evaporation source to the first deposition position prior to a transport of the substrate 10 past the first evaporation source. In the first deposition position, the first main evaporation direction is tilted relative to a surface normal of the substrate by the first tilt angle (a1 ) to either increase or decrease a deposition of the first material under the overhang.

[0065] The controller 114 may be configured to arrange the first evaporation source in the first deposition position and to maintain the first evaporation source in the first deposition position during the transport of the substrate 10 past the first evaporation source for depositing one or more layers on the substrate. After transporting the substrate past the first evaporation source, the controller may cause a movement, e.g., a rotation, of the first evaporation source to another position, e.g. to an idle position that is shown in FIG. 7.

[0066] The angled deposition of one or more materials on the substrate, when the first evaporation source is arranged in the first deposition position, ensures an increased or decreased material deposition in a region below the overhang, as may be beneficial for the deposition of an OLED layer stack. Particularly, a cathode layer can be deposited by angled deposition under the overhang, ensuring a good electrical contact between the cathode material and the first sidewall 11 . In addition, an organic layer can be deposited via angled deposition so as to reduce or prevent a contact between the organic layer and the first sidewall 11 under the overhang.

[0067] As is illustrated in FIG. 3, the two or more vapor distribution pipes of the first evaporation source define a front side 60 of the first evaporation source. The front side of an evaporation source refers to the side of the evaporation source that includes the rows of nozzles and is arranged opposite to a rear side 61 of the evaporation source. During the material deposition on the substrate, the front side 60 faces toward the substrate. If the evaporation source is rotatable (see FIG. 3), the front side 60 of the first evaporation source can, for example, be defined as a line that intersects the first row of nozzles 111 and extends along a tangent to a rotational trajectory of the first row of nozzles 111. Alternatively, the front side 60 of the evaporation source can bedefined as extending along a connection line that connects geometric centers of two or more vapor distribution pipes of the evaporation source in a horizontal sectional plane.

[0068] According to an aspect described herein, in the first deposition position, the front side 60 of the first evaporation source is tilted relative to the substrate transportation path T by a first sub-angle x1 , and a front surface of the first vapor distribution pipe 110 that is provided with the first row of nozzles 111 is tilted relative to the front side 60 of the first evaporation source by a second sub-angle x2, wherein a sum of the first sub-angle x1 and the second sub-angle x2 defines a first tilt angle a1 of the first main evaporation direction M1 relative to a surface normal SN of the substrate.

[0069] In particular, the first sub-angle x1 may be 10° or more, particularly 15° or more, and the second sub-angle x2 may be 15° or more, particularly 25° or more. Hence, the first tilt angle a1 of the first main evaporation direction M1 relative to the surface normal may be 25° or more, particularly 40° or more.

[0070] In other words, the first tilt angle a1 of the first main evaporation direction M1 relative to the surface normal may be based on two contributing factors: (1 ) An inclination of the first row of nozzles 111 relative to the front side 60 (i.e. , the nozzle channels are not perpendicular to the front side 60), and (2) an inclination of the front side 60 of the whole evaporation source with respect to a frontal deposition position, in which the front side 60 is parallel to the substrate transport path T. The second contributing factor can, e.g., be obtained and adapted by rotating the first evaporation source around the rotation axis to a tilted position, and the first contributing factor can, e.g., be obtained and adapted by a specific geometric shape and / or arrangement of the front surface of the first vapor distribution pipe and / or the first row of nozzles, such that the nozzle channels of the first nozzle row are tilted (i.e., not perpendicular) relative to the front side 60.

[0071] The above two contributing factors to the first tilt angle a1 can increase the overall inclination of the first main evaporation direction M1 relative to the surface normal SN to further increase or decrease the deposition under the overhang, as may be appropriate depending on the material or layer to be deposited. Furthermore, themain evaporation directions of several nozzle rows can be tilted in unison (e.g., via the source rotation) as well as relative to each other (e.g., by tilting the nozzles of a row relative to the front side 60 of the evaporation source), which increases the flexibility and allows a deposition of specific layers onto a substrate using one evaporation source. The deposition speed and the deposition flexibility can be improved.

[0072] In some embodiments, which can be combined with other embodiments described herein, the first evaporation source 101 has a second vapor distribution pipe 120 with a second row of nozzles 121 that have a second main evaporation direction M2. The second main evaporation direction M2 and the first main evaporation direction M1 may be tilted toward each other for enabling a co-deposition of a mixed material layer on the substrate in the first deposition position. In particular, the first row of nozzles 111 and the second row of nozzles 121 may be mounted such that the first and second main evaporation directions approach each other, as is illustrated in FIG. 3. Specifically, first vapor plumes emitted by the first row of nozzles and second vapor plumes emitted by the second row of nozzles may overlap during propagation to enable a co-deposition of two materials for forming a mixed material layer on the substrate.

[0073] In some implementations, a mixed material layer, particularly a mixed metal layer or another mixed inorganic layer, is co-deposited onto the substrate with the first and second vapor distribution pipes during the transport of the substrate 10 past the first evaporation source 101. Alternatively, a mixed organic layer that comprises at least two different organic materials is co-deposited onto the substrate with the first row of nozzles and the second row of nozzles being tilted toward each other.

[0074] The mixed metal layer may be a cathode layer of an OLED layer stack, particularly a cathode layer comprising co-deposited silver and magnesium.

[0075] In the first deposition position, the second main evaporation direction M2 may be tilted relative to the surface normal of the substrate by a second tilt angle, having a smaller (absolute) value than the first tilt angle a1 , the first and second tilt angles having the same sign relative to the surface normal in order to increase a material deposition under the first overhang. In particular, both the first and the second main evaporation directions may be tilted “toward” the first overhang 12, such that also the second material is deposited via tilted deposition under the first overhang 12. Thefirst main evaporation direction M1 may be tilted more strongly than the second evaporation direction (see FIG. 4A in this respect). Accordingly, an increased deposition under the first overhang 12 and a co-deposition of a mixed material layer are simultaneously possible by using two rows of nozzles that are tilted both relative to each other as well as relative to the substrate normal. In some embodiments, the first material may be silver and / or the second material may be another metal, such as magnesium, that are co-deposited to provide a mixed cathode layer. A good electric contact between the silver material of the cathode layer and the first sidewall 11 is particularly beneficial.

[0076] In some embodiments, which can be combined with other embodiments described herein, the first evaporation source 101 has a third vapor distribution pipe 130 with a third row of nozzles that have a third main evaporation direction. Optionally, the third main evaporation direction and the first main evaporation direction are tilted away from each other in order to enable a sequential deposition of two layers on top of each other on the substrate in the first deposition position. In other words, the first and third rows of nozzles may be configured such that first vapor plumes emitted by the first row of nozzles and third vapor plumes emitted by the third row of nozzles do not overlap during propagation toward the substrate, such that separate layers can be deposited on top of each other with the first (and optionally the second) and the third vapor distribution pipes.

[0077] In particular, during the transport of the substrate past the first evaporation source, an electron injection layer EIL can be deposited onto the substrate with the third vapor distribution pipe 130 and a cathode layer can be deposited over the electron injection layer with at least the first vapor distribution pipe 110, particularly with the first and second vapor distribution pipes by co-deposition. In particular, a co-deposited cathode layer can be deposited on top of the electron injection layer, wherein the codeposited cathode layer is deposited with the first and second vapor distribution pipes, and the electron injection layer is deposited with the third vapor distribution pipe.

[0078] In another embodiment, the third main evaporation direction of the third row of nozzles may be tilted toward the first and the second main evaporation directions to enable a co-deposition of a mixed layer that includes at least three different materials(as illustrated in FIG. 6A).

[0079] In some embodiments, which can be combined with other embodiments described herein, the first evaporation source is rotatable to an idle position in which the first row of nozzles of the first vapor distribution pipe is directed toward an idle shield 202. In the idle position, optional second and third rows of nozzles are also directed toward the idle shield 202. The first evaporation source 101 can be rotated between the idle shield 202 (shown in FIG. 7) and the first deposition position (shown in FIG. 3). The first evaporation source 101 can be arranged in the idle position when no substrate is being transported past the first evaporation source along the substrate transport path T. When a substrate is transported past the first evaporation source, the first evaporation source can be rotated from the idle position to a deposition position, e.g., to the first deposition position shown in FIG. 3 or to a second deposition position shown in FIG. 5B.

[0080] In some embodiments, the idle shield 202 partially surrounds the first evaporation source, e.g., by an angle of 90° or more and 270° or less, e.g., in a cylinder-like manner. In the idle position (shown in FIG. 7), the front side 60 of the evaporation source faces toward the idle shield 202.

[0081] FIGS. 4A and 4B illustrate two subsequent stages of a method of coating a substrate with evaporation source arrangements according to embodiments described herein. FIG. 4A shows the first evaporation source 101 of FIG. 3 in the first deposition position during material deposition onto the substrate 10. The first main evaporation M1 is tilted relative to the surface normal SN of the substrate by the first tilt angle to increase a deposition of the first material under the first overhang 12. A metal layer, particularly a cathode layer, can be deposited onto the pixel region 13, ensuring that the metal layer has a good electrical contact with the first sidewall 11 under the first overhang 12. The first evaporation source of FIG. 4A can include some features or all features of the first evaporation source of FIG. 3, such that reference can be made to the above explanations, which are not repeated here.

[0082] In some embodiments, the structure formed on the substrate 10 further includes a second sidewall 1 T adjacent to the pixel region 13 on another side of the pixel region 13 than the first sidewall 11 , and a second overhang 12’ on the secondsidewall 1 T projecting from the second sidewall partially over the pixel region 13. The first overhang 12 and the second overhang 12’ may protrude partially over the pixel region 13 from opposite directions.

[0083] In some embodiments, it is sufficient to ensure a reliable electrical contact between the cathode layer and the first sidewall 11 on (at least) one side of the pixel region 13. Accordingly, the cathode layer can be deposited via angled deposition, as described herein, ensuring an improved contact region between the cathode layer and the first sidewall 11 on (at least) a first side of the pixel region 13. The contact between the cathode layer and a second sidewall 1 T on an opposite side of the pixel region 13 may be worse, or there may even be no contact, because the first main evaporation direction M1 is tilted “away from” the region under the second overhang 12’ during the material deposition when the first main evaporation direction M1 is tilted “toward” the region under the first overhang 12 (see FIG. 4A). A good cathode contact on a first side of the pixel region may, however, be acceptable for some applications.

[0084] In other embodiments, a reliable electric contact between the cathode layer and sidewalls under overhangs is provided on different sides of the pixel region 13, particularly on two opposite sides. Specifically, after transporting the substrate past the first evaporation source 101 (illustrated in FIG. 4A), the substrate may be transported past a second evaporation source 102 (illustrated in FIG. 4B) for depositing a second part of a cathode layer on the substrate that electrically contacts the second sidewall 1 T under the second overhang 12’. For example, the second evaporation source 102 may be arranged downstream of the first evaporation source 101 along the substrate transport path T, as illustrated in FIG. 1.

[0085] The second evaporation source 102 is arranged in a second deposition position and has a further first vapor distribution pipe 110’ with a further first row of nozzles 11 T that have a further first main evaporation direction MT. For example, the second evaporation source 102 may be rotated around a rotation axis with a rotation drive to the second deposition position, before the substrate 10 is transported past the second evaporation source 102 along the substrate transport path T. During the substrate transport past the second evaporation source 102, the first material (in particular, a metal of a cathode layer, more particularly silver) is directed toward thesubstrate from the further first row of nozzles 11 T. In the second deposition position, the further first main evaporation direction MT of the further first row of nozzles 11 is tilted by a further first tilt angle aT relative to the surface normal of the substrate, the first tilt angle a1 and the further first tilt angle aT having opposite signs relative to the surface normal. In other words, the first main evaporation direction and the further first main evaporation direction are inclined in opposite directions relative to the surface normal of the substrate. When the nozzle channels of the further first row of nozzles 11 T are tilted relative to the surface normal of the substrate to increase a deposition under the second overhang 12’, a good electrical contact between the deposited layer and the second sidewall 11 ’ can also be ensured on an opposite side of the pixel region 13.

[0086] Accordingly, the first tilt angle a1 of the first row of nozzles increases the deposition of the first material under the first overhang 12, and the further first tilt angle aT of the further first row of nozzles increases a deposition of the first material under the second overhang 12’. If the first material is a metal of a cathode layer, a good electrical contact between the cathode layer and the sidewalls surrounding the pixel region can be ensured on two opposite sides of the pixel region 13. In particular, the first evaporation source 101 may coat the substrate with a first sublayer of a cathode layer and the second evaporation source 102 may coat the substrate with a second sublayer of the cathode layer, particularly wherein the first sublayer and the second sublayer include corresponding materials, particularly metals.

[0087] In some embodiments, the (absolute value of the) first tilt angle a1 of the first row of nozzles 111 may essentially correspond to the (absolute value of the) further first tilt angle aT of the further first row of nozzles 11 T. Accordingly, an equally large contact area and / or an equally good electrical contact between the cathode layer and the sidewalls can be ensured on opposite sides of the pixel region 13. For example, the tilt angles a1 and aT may be 10° or more, particularly 30° or more, and opening angles a of the respective vapor plumes may be 40° or more, particularly 60° or more.

[0088] In some embodiments, the first evaporation source 101 coats the substrate with a mixed material layer via co-deposition from the first and second vapor distribution pipes, and / or the second evaporation source 102 coats the substrate witha mixed material layer by co-deposition from the further first vapor distribution pipe 110’ and a further second vapor distribution pipe 120’ of the second evaporation source 102. The mixed material layer may be a mixed-metal layer, particularly a mixed-metal cathode layer of an OLED layer stack, more particularly a mixed-metal cathode layer comprising silver and magnesium. The nozzles for silver deposition may be more strongly tilted relative to the surface normal than the nozzles for magnesium deposition, ensuring a reliable contact between the silver material and different sidewalls that surround the pixel region 13.

[0089] The deposited materials may include one or more organic materials or one or more inorganic materials, particularly one or more metals. For example, a first evaporation source as described herein may coat the substrate with one or more organic or inorganic materials and a subsequent or preceding evaporation source as described herein may coat the substrate with one or more inorganic materials, particularly metals.

[0090] Optionally, the first evaporation source 101 may include a third vapor distribution pipe 130 configured to deposit a further layer on the substrate before the deposition of the cathode layer. The further layer may be an electron injection layer and / or the further layer may include a metal, particularly ytterbium.

[0091] In some embodiments, which can be combined with other embodiments described herein, a shaper shield 201 is provided for reducing or preventing an overlap of vapor plumes emitted from the first row of nozzles 111 of the first vapor distribution pipe 110 and vapor plumes emitted from a third row of nozzles 131 of the third vapor distribution pipe 130 in the first deposition position. The shaper shield 201 can be mounted at the first evaporation source so as to be rotatable together with the first evaporation source. Alternatively, the shaper shield 201 can be provided as a part of a (stationary) shield arrangement that includes the shaper shield 201 and the idle shield 202. The shield arrangement including the shaper shield 201 and the idle shield 202 partially surrounds the first evaporation source 101 . The shield arrangement may be stationary relative to a rotational movement of the first evaporation source. In other words, the evaporation source can be rotatable using the rotation drive around a rotation axis relative to the shield arrangement (see FIG. 7).

[0092] FIGS. 5A and 5B illustrate two subsequent stages of an alternative method of coating a substrate using an evaporation source arrangement according to embodiments described herein. The first stage that is shown in FIG. 5A corresponds to the stage shown in FIG. 4A, such that reference can be made to the above explanations, which are not repeated here. An area below the first overhang 12 is coated by angled deposition as described herein, particularly with a cathode layer of an OLED layer stack to improve a contact between the cathode layer and a sidewall under an overhang.

[0093] Instead of using a second evaporation source 102 for depositing a second sub-layer of the cathode layer as in FIG. 4B, the first evaporation source 101 can also be used for depositing a second sub-layer of the cathode layer, while ensuring a good electrical contact between the cathode layer and a second sidewall 1 T on an opposite side of the pixel region 13 as the first sidewall 11 .

[0094] In the second stage shown in FIG. 5B, the first evaporation source 101 is rotated to a second deposition position in which the first main evaporation direction M1 of the first row of nozzles 111 is tilted relative to the surface normal of the substrate by a modified first tilt angle a1” relative to the surface normal of the substrate, the first tilt angle and the modified first tilt angle having opposite signs relative to the surface normal of the substrate. The substrate is moved again past the first evaporation source, particularly in a return direction R, while directing the first material toward the substrate from the first row of nozzles. Specifically, the substrate may be transported twice past the first evaporation source, e.g., in opposite directions, wherein the first row of nozzles is first tilted toward a region under the first overhang 12 and then tilted toward a region under the second overhang 12’.

[0095] The first tilt angle a1 may be adapted to increase a deposition of the first material under the first overhang 12, and the modified first tilt angle a1” may be adapted to increase a deposition of the first material under the second overhang 12’. In particular, the first tilt angle a1 and the modified first tilt angle a1 ” may have opposite signs relative to the surface normal of the substrate, but the absolute value of the first tilt angle a1 in the first deposition position may optionally essentially correspond to the absolute value of the modified first tilt angle a1” in the second deposition position.Accordingly, an equally large contact area between the cathode layer and the sidewalls can be ensured on opposite sides of the pixel region 13. Similar to the method illustrated in figures 4A and 4B, a layer can be deposited on the substrate that is in contact with sidewalls on opposite sides of a pixel region, particularly a cathode layer, by moving the substrate twice past the first evaporation source arranged in different deposition positions.

[0096] In some embodiments, the first evaporation source 101 coats the substrate with a first sub-layer of a mixed material layer from the first and second vapor distribution pipes in the first deposition position, and / or the first evaporation source 101 coats the substrate with a second sub-layer of the mixed material layer from the first and second vapor distribution pipes in the second deposition position. The mixed material layer may be a mixed-metal layer, particularly a mixed-metal cathode layer of an OLED layer stack, more particularly a mixed-metal cathode layer comprising silver and magnesium.

[0097] The coating method illustrated in figures 5A and 5B uses only one evaporation source for depositing a layer that reliably reaches under overhangs on opposite sides of a pixel region. However, the movement of the substrate past the first evaporation source twice in opposite directions makes the substrate transport sequence more complex and reduces the deposition flexibility of the vacuum deposition system in comparison with the method illustrated in figures 4A and 4B. On the other hand, the coating method illustrated in figures 4A and 4B uses two evaporation sources for depositing a layer that reliably reaches under overhangs on opposite sides of a pixel region. The substrate can be moved past the two evaporation sources in succession, facilitating a less complex substrate transport.

[0098] Optionally, when the first evaporation source 101 is arranged in the first deposition position shown in FIG. 5A, a further material layer can be deposited on the substrate with a third vapor deposition pipe 130 of the first evaporation source 101 below the mixed material layer that is deposited with the first and second vapor distribution pipes. The further material layer may be an electron injection layer, and / or the mixed material layer may be a first sub-layer of a cathode layer. In the second deposition position shown in FIG. 5B, the third row of nozzles of the third vapordistribution pipe 130 may be directed toward a shutter, such that only a mixed material layer is deposited onto the substrate in the second deposition position with the first and second vapor distribution pipes. The mixed material layer may be a second sub-layer of a cathode layer. For example, as is shown in FIG. 5B, the third row of nozzles of the third vapor distribution pipe 130 may be directed toward an idle shield 202 in the second deposition position, such that the vapor material emitted by the third row or nozzles impinges on and accumulates on the idle shield 202 acting as a shutter.

[0099] In some embodiments, which can be combined with other embodiments described herein, the vapor evaporation pipes are fixedly mounted on a body of the evaporation source so as to be rotatable in unison around the rotation axis when the evaporation source rotates. If the evaporation source includes three vapor distribution pipes, the first vapor distribution pipe may be arranged between the second vapor distribution pipe and the third vapor distribution pipe at the front side of the evaporation source.

[0100] FIGS. 6A and 6B illustrate two subsequent stages of another method of coating a substrate with an evaporation source arrangement according to embodiments described herein. The second stage shown in FIG. 6B corresponds to the stage shown in FIG. 4A, such that reference can be made to the above explanations, which are not repeated here. An area below the first overhang 12 is coated via angled deposition as described herein, particularly with a cathode layer of an OLED layer stack. A reliable electric contact and a low contact resistance between the cathode layer and the first sidewall 11 can be ensured. In the first stage shown in FIG. 6A, a layer is deposited below the cathode layer, particularly an organic layer.

[0101] FIG. 6A shows the deposition of an organic layer on the substrate, using a third evaporation source 103, underneath the cathode layer prior to the deposition of the cathode layer in FIG. 6B. For example, the third evaporation source 103 may be an organic material source and / or may be arranged upstream of the first evaporation source 101 along a substrate transport path, as is schematically depicted in the vacuum deposition system of FIG. 1. The first evaporation source 101 may be a metal source.

[0102] The third evaporation source 103 may have one, two or more vapordistribution pipes, e.g., a first vapor distribution pipe 610 for depositing a first material, a second vapor distribution pipe 620 for depositing a second material, and a third vapor distribution pipe 630 for depositing a third material. Each vapor distribution pipe may have a (single) row of nozzles. The first, second, and third materials may be organic materials, and the third evaporation source 103 may be an organic source, i.e., an evaporation source for coating the substrate with one or more organic layers. Two or more materials may be co-deposited to provide a mixed organic layer on the substrate. Alternatively or additionally, two organic layers may be deposited on top of each other.

[0103] The third evaporation source 103 is arranged in a first deposition position for material deposition onto the substrate. In particular, the third evaporation source is rotated to the first deposition position around a rotation axis. In the first deposition position that is shown in FIG. 6A, a first main evaporation direction of the first row of nozzles of the first vapor distribution pipe 610 is tilted relative to a surface normal of the substrate by a first tilt angle to decrease a deposition of the first material under the first overhang 12. In particular, a contact between the deposited layer and the first sidewall 11 can be reduced or prevented by a first main evaporation direction being tilted “away from” the region under the overhang. The second and third rows of nozzles of the second and third vapor distribution pipes may also be tilted relative to the surface normal so as to decrease a material deposition under the first overhang 12.

[0104] In some embodiments, the first material is an organic material, and the first tilt angle is adapted to decrease a deposition of the organic material under the first overhang. In particular, the front side 60 of the third evaporation source 103 may be tilted relative to the substrate transport path T, e.g., by an angle of 10° or more, or 15° or more, to decrease a material deposition under the first overhang 12. In particular, the nozzle channels of all the nozzles of the third evaporation source 103 may be tilted relative to the surface normal of the substrate away from the region below the overhang 12.

[0105] As the organic material is only thinly deposited under the first overhang or is not at all deposited under the first overhang, a contact between a subsequently deposited metal layer and the first sidewall 11 can be improved (see FIG. 6B). Particularly, in case of more thinly deposited underlying layers, the metal vapor canmore easily enter the region below the overhang at a subsequent coating stage and an improved contact area between the metal layer and the first sidewall 11 can be ensured.

[0106] In FIG. 6B, which shows a subsequent coating stage, a metal layer, particularly a cathode layer, is deposited over the organic material deposited in FIG. 6A, wherein the metal is deposited via angled deposition under the first overhang as described herein to provide an improved contact between the metal layer and the first sidewall 11. Reference is made to the embodiments described above (e.g., in FIG. 4A+B and 5A+B).

[0107] In some embodiments, which can be combined with other embodiments described herein, the first evaporation source includes the first vapor distribution pipe and at least one further vapor distribution pipe, each vapor distribution pipe comprising one single row of nozzles, the nozzles of the row being provided above one another in an essentially vertical array. In some implementations, each row of nozzles has twenty or more nozzles, particularly 30 or more nozzles.

[0108] In some embodiments, which can be combined with other embodiments described herein, a shaper shield 201 is arranged in front of the first row of nozzles for shaping vapor plumes emitted by the first row of nozzles to be asymmetrical relative to the first main evaporation direction M1 , e.g., for decreasing a material deposition on a side of the first main evaporation direction facing away from the first overhang as compared to the opposite side of the first main evaporation direction. In particular, the shaper shield 201 is arranged to shape the vapor plumes to be asymmetrical relative to the first main evaporation direction to increase a ratio between a first deposition amount of the first material in a region under the first overhang and a second deposition amount of the first material on an uncovered region of the substrate, i.e. to increase a thickness of the deposited first material under the first overhang relative to a thickness of the deposited first material on uncovered substrate regions. The aspect of “asymmetrical plume shaping” with a shaper shield 201 as described herein is considered as a separate aspect that can be used independently or in combination with the aspect to a “tilted main evaporation direction” described herein.

[0109] In particular, an evaporation source may be characterized by a shapershield arranged in front of (at least) the first row of nozzles and configured to asymmetrically limit an opening angle of vapor plumes emitted by the first row of nozzles. The shaper shield is configured to shape the vapor plumes emitted by the first row of nozzles to be asymmetrical relative to the first main evaporation direction, so that the opening angle of the vapor plumes is different on opposite sides of the main evaporation direction. A material deposition on a side of the first main evaporation direction facing away from the first overhang can be more strongly limited than a material deposition on a side of the main evaporation direction facing toward the first overhang. In particular, a first half-angle of the vapor plumes on a first side of the main evaporation direction facing toward the region under the first overhang may be shaped to be larger than a second half-angle of the vapor plumes on a second side of the main evaporation direction facing away from the region under the first overhang. A ratio between a first thickness of the deposited first material under the first overhang and a second thickness of the deposited first material on uncovered regions of the substrate can be increased. The shaper shield can include a shield body with an essentially vertically extending slit that is aligned with the first row of nozzles to asymmetrically shape the vapor plumes emitted by the first row of nozzles.

[0110] Thus, in view of the embodiments described herein, improved evaporation source arrangements and improved coating methods are provided, particularly for “maskless” OLED pixel deposition that does not use fine metal masks, but rather uses angled deposition under overhangs. “Angled deposition” as used herein refers to a tilted main evaporation direction or tilted nozzle channels of the nozzles of one or more nozzle rows relative to the surface normal of the substrate for increasing (or decreasing) the deposition below the overhangs.

[0111] While the foregoing is directed to embodiments of the disclosure, other and further embodiments of the disclosure may be devised without departing from the basic scope thereof, and the scope thereof is determined by the claims that follow.

[0112] 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 specificembodiments have been disclosed in the foregoing, mutually non-exclusive features of the embodiments described above may be combined with each other. The patentable scope is defined by the claims, and other examples are intended to be within the scope of the claims if the claims have structural elements that do not differ from the literal language of the claims, or if the claims include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

WHAT IS CLAIMED1 . A method of coating a substrate (10) in a vacuum chamber, the substrate having a structure formed thereon comprising a first sidewall (11 ) adjacent to a pixel region (13) and a first overhang (12) projecting from the first sidewall (11 ), the method comprising: arranging a first evaporation source (101 ) in a first deposition position, the first evaporation source having a first vapor distribution pipe (110) with a first row of nozzles (111 ) that have a first main evaporation direction (M1 ); and transporting the substrate (10) past the first evaporation source (101 ) while directing a first material toward the substrate from the first row of nozzles (111 ), wherein, in the first deposition position, the first main evaporation direction (M1 ) is tilted relative to a surface normal of the substrate by a first tilt angle (a1 ) to either increase or decrease a deposition of the first material under the first overhang (12).

2. The method of claim 1 , wherein the first tilt angle (a1 ) is 15° or more, particularly 30° or more.

3. The method of claim 1 or 2, wherein the first material is a metal and, in the first deposition position, the first main evaporation direction (M1 ) is tilted to increase a contact area between the metal and the first sidewall under the first overhang.

4. The method of claim 3, wherein a shaper shield (201 ) is arranged in front of the first row of nozzles (111 ) for shaping vapor plumes emitted by the first row of nozzles to be asymmetrical relative to the first main evaporation direction (M1 ).

5. The method of any of claims 1 to 4, wherein the first evaporation source has a second vapor distribution pipe (120) with a second row of nozzles (121 ) that have a second main evaporation direction (M2), wherein the second main evaporation direction (M2) and the first main evaporation direction (M1 ) are tilted toward each other for enabling a co-deposition of a mixed material layer on the substrate in the first deposition position.

6. The method of claim 5, wherein a mixed metal layer is co-deposited onto the substrate with the first and second vapor distribution pipes during the transporting of the substrate (10) past the first evaporation source (101 ).

7. The method of claim 6, wherein the mixed metal layer is a cathode layer of an OLED layer stack.

8. The method of any of claims 5 to 7, wherein, in the first deposition position, the second main evaporation direction is tilted relative to the surface normal of the substrate by a second tilt angle smaller than the first tilt angle (a1 ), the first and second tilt angles having the same sign relative to the surface normal to increase a material deposition under the first overhang.

9. The method of any of claims 1 to 8, wherein the first evaporation source has a third vapor distribution pipe (130) with a third row of nozzles that have a third main evaporation direction, the first row of nozzles and the third row of nozzles configured to deposit two layers on top of each other onto the substrate in the first deposition position during transport of the substrate past the first evaporation source, particularly wherein the third main evaporation direction (M3) and the first main evaporation direction (M1 ) are tilted away from each other to enable a deposition of the two layers on top of each other .

10. The method of claim 9, wherein, during transport of the substrate past the first evaporation source, an electron injection layer is deposited onto the substrate with the third vapor distribution pipe (130) and a cathode layer is deposited over the electron injection layer with at least the first vapor distribution pipe (110) or co-deposited over the electron injection layer with the first vapor distribution pipe and a second vapor distribution pipe (120).

11. The method of claim 9 or 10, wherein a shaper shield (201 ) is provided for reducing or preventing an overlap of vapor plumes emitted from the first row of nozzles of the first vapor distribution pipe and vapor plumes emitted from the third row of nozzles of the third vapor distribution pipe in the first deposition position.

12. The method of any of claims 1 to 11 , wherein the first evaporation source is rotatable to an idle position in which the first row of nozzles of the first vapor distribution pipe is directed toward an idle shield (202).

13. The method of any of claims 1 to 12, further comprising: arranging a second evaporation source (102) in a second deposition position, the second evaporation source having a further first vapor distribution pipe (110’) with a further first row of nozzles (11 T) that have a further first main evaporation direction (MT); and transporting the substrate (10) past the second evaporation source (102) while directing the first material toward the substrate from the further first row of nozzles (111’), wherein, in the second deposition position, the further first main evaporation direction (MT) of the further first row of nozzles (11 T) is tilted by a further first tilt angle (aT) relative to the surface normal of the substrate, the first tilt angle (a1 ) and the further first tilt angle (aT) having opposite signs relative to the surface normal.

14. The method of claim 13, wherein the structure formed on the substrate comprises a second sidewall (1 T) adjacent to the pixel region (13) on another side of the pixel region as the first sidewall (11 ) and a second overhang (12’) projecting from the second sidewall (11 ’) partially over the pixel region, and the first tilt angle (a1 ) of the first row of nozzles increases the deposition of the first material under the first overhang (12), and the further first tilt angle (aT) of the further first row of nozzles increase a deposition of the first material under the second overhang (12’).

15. The method of claim 13 or 14, wherein the first evaporation source (101 ) coats the substrate with a first sublayer of a cathode layer comprising co-deposited metals, and the second evaporation source (102) coats the substrate with a second sublayer of the cathode layer comprising the co-deposited metals.

16. The method of any of claims 1 to 12, further comprising:rotating the first evaporation source (101 ) to a second deposition position, in which the first main evaporation direction (M1 ) of the first row of nozzles (111 ) is tilted relative to the surface normal of the substrate by a modified first tilt angle relative to the surface normal of the substrate, the first tilt angle and the modified first tilt angle having opposite signs relative to the surface normal; and transporting the substrate (10) past the first evaporation source while directing the first material toward the substrate from the first row of nozzles.

17. The method of claim 16, wherein the structure formed on the substrate comprises a second sidewall (1 T) adjacent to the pixel region (13) on another side of the pixel region as the first sidewall (11 ) and a second overhang (12’) projecting from the second sidewall partially over the pixel region, and the first tilt angle is adapted to increase a deposition of the first material under the first overhang, and the modified first tilt angle is adapted to increase a deposition of the first material under the second overhang.

18. The method of any of claims 1 to 17, wherein the first material is an organic material, and the first tilt angle is adapted to decrease or avoid a deposition of the organic material under the first overhang, particularly to reduce or prevent a contact between the organic material and the first sidewall.

19. The method of claim 18, further comprising a deposition of a metal over the organic material, wherein the metal is deposited via angled deposition under the first overhang to provide a contact area between the metal and the first sidewall.

20. The method of any of claims 1 to 19, wherein the first evaporation source (101 ) includes the first vapor distribution pipe (110) and at least one further vapor distribution pipe, each vapor distribution pipe comprising one single row of nozzles extending in an essentially vertical direction and having twenty or more nozzles.

21. The method of any of claims 1 to 20, wherein the first evaporation source is rotatable around a rotation axis, and the first evaporation source is arranged in the first deposition position by rotating the first evaporation source around the rotation axis to the first deposition position.

22. An evaporation source arrangement (100) for depositing two or more materials on a substrate having a structure with an overhang formed thereon, comprising: a first evaporation source (101 ), comprising: a first vapor distribution pipe (110) with a first row of nozzles (111 ) that have a first main evaporation direction (M1 ) for depositing a first material on the substrate; and a second vapor distribution pipe (120) with a second row of nozzles (121 ) that have a second main evaporation direction (M2) for depositing a second material on the substrate; a rotation drive (113) for rotating the first evaporation source around a rotation axis; and a controller (114) configured to cause a rotation of the first evaporation source to a first deposition position prior to a transport of the substrate past the first evaporation source, wherein, in the first deposition position, the first main evaporation direction (M1 ) is tilted relative to a surface normal (SN) of the substrate by a first tilt angle (a1 ) to either increase or decrease a deposition of the first material under the overhang.

23. An evaporation source arrangement (100) for depositing two or more materials on a substrate, comprising: a first evaporation source (101 ), comprising: two or more vapor distribution pipes including a first vapor distribution pipe (110) with a first row of nozzles (111 ) that have a first main evaporation direction for depositing a first material on the substrate, wherein the two or more vapor distribution pipes define a front side (60) of the first evaporation source directed toward a substrate transport path (T) and arranged opposite to a rear side (61 ) of the first evaporation source; wherein the front side (60) of the first evaporation source is tilted relative to the substrate transportation path (T) by a first sub-angle (x1 ), and a front surface of the first vapor distribution pipe (110) that is provided with the first row of nozzles (111 ) is tilted relative to the front side (60) of the first evaporation source by a second sub-angle (x2), wherein a sum of the first sub-angle (x1 ) and the second sub-angle (x2) defines a first tilt angle (a1 ) of the first main evaporation direction (M1 ) relative to a surface normal (SN) of the substrate.

24. The evaporation source arrangement of claim 23, further comprising: a rotation drive (113) for rotating the first evaporation source around a rotation axis; and a controller (114) configured to cause a rotation of the first evaporation source to a first deposition position prior to a transport of the substrate past the first evaporation source, wherein, in the first deposition position, the front side (60) of the first evaporation source is tilted relative to the substrate transportation path (T) by the first sub-angle (x1 ).

25. The evaporation source arrangement (100) of claim 23 or 24, wherein the first sub-angle (x1 ) is 10° or more and the second sub-angle (x2) is 15° or more.

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