WO2022028675A1

WO2022028675A1 - Vapor source, nozzle for a vapor source, vacuum deposition system, and method for depositing an evaporated material

Info

Publication number: WO2022028675A1
Application number: PCT/EP2020/071880
Authority: WO
Inventors: Michael Long
Original assignee: Applied Materials, Inc.
Priority date: 2020-08-04
Filing date: 2020-08-04
Publication date: 2022-02-10
Also published as: KR20230047440A; CN116171336A

Abstract

Embodiments described herein relate to a vapor source (100) for depositing an evaporated material on a substrate (10) in a vacuum chamber. The vapor source (100) includes a vapor distribution pipe (110) with a plurality of nozzles for directing the evaporated material toward the substrate, wherein at least one nozzle (120) of the plurality of nozzles includes a nozzle channel (121) extending along a nozzle axis (A) from a nozzle inlet (122) to an orifice (123), and a nozzle insert (130) with a heat shield portion (131) arranged centrally inside the nozzle channel (121) for reducing heat radiation from the nozzle channel through the orifice (123). Further described are a nozzle for directing the evaporated material toward the substrate, a vacuum deposition system (200), and a method for depositing an evaporated material on a substrate.

Description

VAPOR SOURCE, NOZZLE FOR A VAPOR SOURCE, VACUUM DEPOSITION SYSTEM, AND METHOD FOR DEPOSITING AN EVAPORATED MATERIAL

TECHNICAL FIELD

[0001 ] Embodiments of the present disclosure relate to apparatuses and methods for directing an evaporated material toward a substrate in a vacuum chamber of a vacuum deposition system. Specifically, embodiments of the present disclosure relate to a vapor source with a plurality of nozzles for directing the evaporated material, e.g. an organic material, toward a substrate for depositing the material on the substrate. Further embodiments relate to nozzles for a vapor source, to vacuum deposition systems with a vapor source, and to methods for depositing an evaporated material on a substrate in a vacuum chamber. Embodiments particularly relate to the deposition of a pixel pattern on a substrate, particularly through a fine metal mask, and to deposition sources and systems used in the manufacture of organic light-emitting diode (OLED) devices.

BACKGROUND

[0002] 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. An OLED device, such as an OLED display, may include one or more layers of an organic material situated between two electrodes that are all deposited on a substrate.

[0003] During deposition, the substrate can be supported on a carrier that holds the substrate in alignment with a mask. The vapor from a vapor 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 small pixels that can be addressed individually to create functional devices such as full color displays. It is beneficial for the display quality to create clearly defined pixels having nearly vertical walls and a uniform thickness over the full area of the pixel. To achieve this result, vapor molecules should beneficially not undercut the mask or be partially obstructed by the edges of the mask, causing deposition in the space between pixels or resulting in pixels having rounded edges. In practice this means that a vapor molecule trajectory which is normal to the plane of the substrate or lies within a small angular deviation, such as 30° or less from normal, is beneficial.

[0004] In order to reduce or avoid a misalignment between the mask and the substrate, the heat load from the vapor source toward the deposition area should be as low as possible. Specifically, an excessive heat radiation from the vapor source toward the mask may lead to a thermally induced movement or tension of the mask relative to the substrate. Known deposition systems use cooling plates, cooling shields or other cooling arrangements in an area between the vapor source and the mask in order to reduce a thermally induced misalignment between the substrate and the mask.

[0005] Reducing the heat load into the deposition area is difficult since the temperature inside the vapor source and inside the vapor nozzles is above the evaporation temperature of the evaporated material. Cooled baffle plates located between the vapor nozzles and the mask lead to a material condensation on the baffle plates and therefore to a reduced material utilization and increased costs, because a considerable portion of the vapor generated in the source may be collected as condensate on the cooled plates instead of being deposited on the substrate.

[0006] In light of the above, improved apparatuses and methods for material deposition on a substrate would be beneficial. Embodiments of the present disclosure aim at providing systems, apparatuses, arrangements and methods for material deposition that overcome at least some of the problems mentioned above. Specifically, the heat load from the vapor source into the deposition area should be reduced and an accurate deposition of a clearly defined material pattern on the substrate should be allowed.

SUMMARY

[0007] In light of the above, a vapor source for depositing an evaporated material on a substrate, a nozzle for a vapor source, a vacuum deposition system, as well as a method for depositing an evaporated material on a substrate are provided.

[0008] According to an aspect of the present disclosure, a vapor source is provided. The vapor source includes a vapor distribution pipe with a plurality of nozzles for directing an evaporated material toward a substrate. At least one nozzle of the plurality of nozzles includes a nozzle channel extending along a nozzle axis from a nozzle inlet to an orifice. The at least one nozzle further includes a nozzle insert with a heat shield portion arranged centrally inside the nozzle channel for reducing heat radiation from the nozzle channel through the orifice.

[0009] In particular, the heat shield portion may be provided in a center area of the nozzle channel in such a way that an essentially annular vapor flow path extends around the heat shield portion between the heat shield portion and an inner wall of the nozzle channel in the direction of the nozzle axis. Since the heat shield portion is provided inside the nozzle channel, heat radiation from the inner wall of the nozzle channel through the orifice is at least partially blocked or reflected by the heat shield portion, such that the heat load on the mask from the at least one nozzle is reduced.

[0010] The heat shield portion may also be referred to as a “low thermal emissivity heat shield portion” because the heat shield portion reduces the effective thermal emissivity of the nozzle as compared to a nozzle having a corresponding shape but no heat shield portion. Specifically, the heat shield portion may be made of or include a material having a low thermal emissivity and may shield at least a portion of the thermal radiation radiated from the inner channel wall of the nozzle, reducing the heat load from the nozzle on the mask and on the substrate.

[0011] According to an aspect of the present disclosure, a nozzle for a vapor source is provided, particularly for a vapor source according to any of the embodiments described herein. The nozzle includes a nozzle channel extending along a nozzle axis from a nozzle inlet to an orifice for releasing evaporated material into a vacuum chamber toward a substrate. The nozzle further includes a nozzle insert with a heat shield portion arranged centrally inside the nozzle channel for reducing heat radiation from the nozzle channel through the orifice.

[0012] According to a further aspect of the present disclosure, a vacuum deposition system is provided. The vacuum deposition system includes a vacuum chamber and a vapor source according to any of the embodiments described herein provided in the vacuum chamber. Further, at least one of a first drive for moving the vapor source in the vacuum chamber along a source transportation path and a second drive for rotating the distribution pipe of the vapor source is provided. [0013] According to a further aspect of the present disclosure, a method for depositing an evaporated material on a substrate in a vacuum chamber is provided. The method includes directing the evaporated material toward the substrate by a plurality of nozzles, at least one nozzle of the plurality of nozzles including a nozzle channel extending along a nozzle axis from a nozzle inlet to an orifice. The method further includes reducing heat radiation from the nozzle channel through the orifice with a heat shield portion of a nozzle insert that is centrally arranged inside the nozzle channel.

[0014] 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 present disclosure are also directed at methods for manufacturing the described apparatuses and products, and methods of operating the described apparatus. Further embodiments are directed to substrates, e.g. display devices, coated according to any of the methods or using any of the vapor sources described herein. Described embodiments include method aspects for carrying out every function of the described apparatuses.

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] 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 present disclosure, briefly summarized above, may be had by reference to embodiments. The accompanying drawings relate to embodiments of the present disclosure and are described in the following:

[0016] FIG. 1A shows a schematic sectional view of a part of a vapor source according to embodiments described herein;

[0017] FIG. IB shows a schematic front view of the vapor source of FIG. 1 A;

[0018] FIG. 2 shows a schematic sectional view of a vacuum deposition system with a vapor source having a plurality of nozzles according to embodiments described herein;

[0019] FIG. 3 A shows a schematic sectional view of a part of a vapor source according to embodiments described herein;

[0020] FIG. 3B shows a schematic front view of the vapor source of FIG. 3 A; [0021] FIGS. 4A-C show subsequent stages of a method for depositing an evaporated material on a substrate with a vacuum deposition system according to embodiments described herein;

[0022] FIG. 5 is a flow diagram illustrating a method for depositing an evaporated material on a substrate according to embodiments described herein; and

[0023] FIG. 6 is a graph illustrating the effective thermal emissivity of a nozzle cavity depending on a length of the nozzle channel.

DETAILED DESCRIPTION OF EMBODIMENTS

[0024] Reference will now be made in detail to the various embodiments of the present 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 the same components. Generally, only the differences with respect to individual embodiments are described. Each example is provided by way of explanation and is not meant as a limitation of the present disclosure. 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.

[0025] As used herein, the term “evaporated material” may be understood as a material that is evaporated and deposited on a surface of a substrate. For example, the evaporated material may be an organic material that is deposited on a substrate to form an optically active layer of an OLED device. The material may be deposited in a predetermined pattern, e.g. by using a mask such as a fine metal mask having a plurality of openings. A plurality of pixels may be deposited on the substrate. Other examples of evaporated material include one or more of the following: ITO, NPD, Alq3, and metals such as silver or magnesium.

[0026] As used herein, the term “vapor source” or “evaporation source” may be understood as an arrangement providing the evaporated material to be deposited on a substrate. In particular, the vapor source may be configured to direct an evaporated material to be deposited on a substrate into a deposition area in a vacuum chamber. The evaporated material may be directed toward the substrate via a plurality of nozzles of the vapor source. The nozzles may have nozzle outlets (also referred to as “orifices” herein), respectively, which may be directed toward the deposition area, particularly toward the substrate to be coated, wherein a mask is arranged in front of the substrate.

[0027] The vapor source may include an evaporator (or “crucible”) which evaporates the material to be deposited on the substrate, and a vapor distribution pipe, which is in fluid connection with the crucible and which is configured to guide the evaporated material to the plurality of nozzles for releasing plumes of evaporated material into the deposition area in a vacuum chamber.

[0028] In some embodiments, the vapor source includes two or more distribution pipes, wherein each distribution pipe includes a plurality of nozzles. For example, each distribution pipe includes two or more nozzles, particularly ten or more nozzles, more particularly thirty or more nozzles. The nozzles of a vapor distribution pipe may be arranged in a linear array or row, such that a line source is provided. In some embodiments, the vapor source includes two or more vapor distribution pipes arranged next to each other, wherein each of the two or more vapor distribution pipes includes ten or more nozzles arranged in a row.

[0029] The present disclosure generally describes details and features of “at least one nozzle” of the plurality of nozzles of a vapor distribution pipe. However, it is to be understood that two, three, five, ten, or all the nozzles of the plurality of nozzles may be built and structured in a corresponding way and may have corresponding features. Specifically, all the nozzles of the vapor distribution pipe may be configured in accordance with the at least one nozzle described herein.

[0030] The term “vapor distribution pipe” may be understood as a tube or pipe for guiding and distributing the evaporated material. In particular, the distribution pipe may guide the evaporated material from a crucible to the plurality of nozzles which may extend through a side wall of the distribution pipe. For example, the plurality of nozzles may be mounted at openings in the vapor distribution pipe, e.g. screwed into the openings via threads. Each nozzle may include an orifice for releasing the evaporated material into a vacuum chamber toward the substrate along a main emission direction which may correspond to a nozzle axis (A) which is essentially normal to the surface of the substrate. According to embodiments described herein, the vapor distribution pipe may be a linear distribution pipe extending in a longitudinal direction, particularly in an essentially vertical direction (V). In some embodiments, the vapor distribution pipe may include a pipe having a sectional shape of a cylinder. The cylinder may have a circular bottom shape or another suitable bottom shape, e.g. an essentially triangular bottom shape. In particular, the vapor distribution pipe may have an essentially triangular sectional shape.

[0031] In some embodiments, the vapor source may include two or three vapor distribution pipes which extend in an essentially vertical direction (V), respectively. Each distribution pipe may be in fluid connection with a respective crucible such that different materials can be codeposited on the substrate. Nozzles of a first vapor distribution pipe and nozzles of an adjacent second vapor distribution pipe may be arranged close to each other, e.g. at a distance of 5 cm or less, enabling a uniform co-deposition of two or more materials on the substrate.

[0032] FIG. 1A is a schematic sectional view of a vapor source 100 for depositing an evaporated material on a substrate 10 according to embodiments described herein. FIG. IB is a front view of the vapor source 100.

[0033] The vapor source 100 includes a vapor distribution pipe 110 which may extend in an essentially vertical direction V. Alternatively, the distribution pipe may extend in another direction, e.g. an essentially horizontal direction. In the embodiment depicted in FIG. 1A, the vapor distribution pipe 110 provides an essentially vertical line source. An essentially vertically extending vapor distribution pipe 110 may be beneficial because the footprint of the system can be reduced, and a compact and space-saving deposition system can be provided. In some embodiments, the vapor source 100 includes two or more vapor distribution pipes which are supported on a source support which may be movable. The two or more vapor distribution pipes may extend in an essentially vertical direction. “Essentially vertical” as used herein refers to a direction corresponding to the direction of gravity or having a deviation angle of 15° or less from the direction of gravity.

[0034] The vapor distribution pipe 110 includes a plurality of nozzles for directing the evaporated material toward the substrate 10. Specifically, the plurality of nozzles allows the evaporated material to be directed from an interior space of the vapor distribution pipe 110 into a deposition area 50 in a vacuum chamber where the substrate 10 is arranged. In some embodiments, ten or more nozzles, particularly thirty or more nozzles may be provided at the vapor distribution pipe 110. The plurality of nozzles may be arranged along the longitudinal direction of the vapor distribution pipe 110 in a line setup (see FIG. 2). [0035] FIG. 1A shows one of the nozzles of the plurality of nozzles in detail in a sectional view. The other nozzles may be configured in a similar or in a corresponding way. The at least one nozzle 120 includes a nozzle channel 121 extending along the nozzle axis A from a nozzle inlet 122 to an orifice 123. Evaporated material from the vapor distribution pipe 110 can enter the nozzle channel 121 at the nozzle inlet 122, the evaporated material can stream through the nozzle channel 121 toward the orifice 123, and the evaporated material can exit the nozzle channel 121 through the orifice 123 that is configured to emit a vapor plume 15 of evaporated material toward the substrate 10 through the deposition area 50.

[0036] According to embodiments described herein, the at least one nozzle 120 includes a nozzle insert 130 that is arranged inside the nozzle channel 121. The nozzle insert 130 includes a heat shield portion 131 arranged centrally inside the nozzle channel 121 and configured to reduce the heat radiation from the nozzle channel 121 through the orifice 123 toward the substrate 10. The heat shield portion is a low emissivity heat shield portion that reduces the emissivity of the nozzle.

[0037] The nozzle insert 130 is a component that is mounted in the nozzle channel and includes the heat shield portion 131 for reducing the heat radiation from the at least one nozzle into the deposition area 50. The nozzle insert 130 may be fixed in the nozzle channel in a formfitting manner and/or in a force-fitting manner, e.g. by a press-fit. For example, the nozzle insert 130 may be inserted into the nozzle channel in a cooled and shrunk state, such that the nozzle insert 130 expands during heating and is press-fitted to the channel wall of the nozzle channel.

[0038] The heat shield portion 131 may be arranged centrally in the nozzle channel. In other words, the heat shield portion 131 may be arranged in a central area of the nozzle channel at or in vicinity of the nozzle axis A (not necessarily exactly at the nozzle axis), leaving a vapor flow passage in a radial edge area of the nozzle channel that may surround the heat shield portion. In order to still allow for a vapor stream through the nozzle channel 121 toward the orifice 123, a gap may be provided between the heat shield portion 131 and the inner wall of the nozzle channel, particularly a radial gap that surrounds the heat shield portion 131 in a circumferential direction. Specifically, the heat shield portion 131 may be held at a distance from the inner wall of the nozzle channel 121. In particular, an essentially annularly shaped vapor flow path 111 that extends along the nozzle channel 121 may surround the heat shield portion 131. [0039] In some embodiments, an essentially annular vapor flow path 111 located between the heat shield portion 131 and the inner wall of the nozzle channel 121 may be provided for guiding the evaporated material in the direction of the nozzle axis past the nozzle insert. Alternatively or additionally, the heat shield portion 131 may have one or more openings or through holes that extend essentially in the direction of the nozzle axis and provide vapor flow paths through the nozzle channel toward the orifice.

[0040] “Arranged centrally” does not refer to the center of the heat shield portion in the axial direction. Rather, the heat shield portion 131 is typically arranged closer to the orifice 123 than to the nozzle inlet 122 in the axial direction in order to increase the shielding effect provided by the heat shield portion 131. In some embodiments, an axial distance L2 between the heat shield portion 131 and the orifice 123 is less than 50% of a total length LI of the nozzle channel 121, i.e. the heat shield portion 131 is arranged closer to the nozzle outlet than to the nozzle inlet. For example, the distance L2 between a downstream end of the heat shield portion 131 and the orifice 123 may be less than 30% or even less than 20% of the total length LI of the nozzle channel. In other words, the heat shield portion 131 may be arranged close to the orifice 123 but still inside the nozzle channel. Arranging the heat shield portion 131 close to the orifice 123 is beneficial because a major part of the heat radiation from the inner wall surfaces of the nozzle channel can be shielded by the heat shield portion arranged close to the nozzle outlet.

[0041] In some embodiments, the total length LI of the nozzle channel 121 may be 15 mm or more and 30 mm or less, particularly 20 mm or more and 25 mm or less, e.g. about 22 mm. The distance L2 between the downstream end of the heat shield portion 131 and the orifice 123 may be 2 mm or more and 8 mm or less, particularly 3 mm or more and 5 mm or less. Accordingly, the heat shield portion 131 shields heat radiation from a section of the nozzle channel arranged behind the heat shield portion (which is a major section of the nozzle channel since L2/L1 is typically smaller than 0.5), such that heat emitted through the orifice is considerably reduced.

[0042] In some embodiments, which can be combined with other embodiments described herein, the at least one nozzle 120 has an essentially annular vapor flow path 111 that surrounds the heat shield portion 131 and extends between the heat shield portion 131 and the inner wall of the nozzle channel in the direction of the nozzle axis. Specifically, a circumferential gap surrounding the centrally arranged heat shield portion 131 constitutes a vapor flow path 111 along which the evaporated material streams through the nozzle channel. [0043] Providing the nozzle insert 130 with the heat shield portion 131 that is arranged centrally in the nozzle channel 121 is beneficial for the following reasons:

[0044] The interior of a vapor nozzle is hot and, therefore, heat radiation is directed through the orifice of the nozzle toward the substrate. A small nozzle diameter (i.e., a small diameter of the nozzle orifice) decreases the heat load from the nozzle. However, a nozzle with a small nozzle diameter has a reduced conductance and therefore a decreased deposition rate, such that a reduction of the nozzle diameter for reducing the heat load is not always possible.

[0045] Further, the thermal emissivity a of a nozzle with a given nozzle diameter increases with the nozzle depth L (i.e., with the total length of the nozzle channel). In simple words, a deep nozzle typically radiates more heat than a short nozzle, the reason being that a deep nozzle with a long nozzle channel has large internal channel surfaces, particularly a large inner channel wall, that contribute to the heat load into the deposition area provided by the nozzle. However, the directionality and shape of the vapor plume provided by a nozzle typically improves with the nozzle depth L, such that it is not always possible to simply reduce the length of the nozzle channel for reducing the heat load.

[0046] FIG. 6 is a graph that illustrates the thermal emissivity a of a conventional cylindrical vapor nozzle as a function of the nozzle depth L in mm. The conventional nozzle is made of stainless steel and has a simple cylindrical cavity with a diameter of 3 mm. As can be seen, the thermal emissivity a of the nozzle increases with the nozzle depth L. The curve 620 shows a theoretical calculation of the thermal emissivity depending on the nozzle depth L, and the values 610 are measured emissivity values for nozzles with diffuse reflectivity for exemplary nozzle depths between 0 and 10 mm.

[0047] According to embodiments described herein, a nozzle 120 is provided that provides at the same time a well-shaped vapor plume with a good directionality and a reduced heat load into the deposition area. The nozzle 120 has a nozzle channel extending along the nozzle axis A and having a length and a diameter adapted to provide a predetermined conductance and a well-defined vapor plume in a main emission direction of the nozzle. The nozzle insert 130 has a heat shield portion 131 that effectively reduces the nozzle depth and, hence, reduces the heat radiation from the nozzle through the orifice. When viewed from a front side of the nozzle (see FIG. IB), it seems that the heat shield portion 131 that is arranged centrally in the nozzle channel constitutes a nozzle base and therefore defines the nozzle depth, such that the heat shield portion effectively reduces the nozzle depth, “shifting” the nozzle base toward the orifice. The effective nozzle depth is smaller than the total length LI of the nozzle channel and corresponds to the axial distance L2 between the heat shield portion and the orifice. Hence, the heat radiation from the nozzle channel through the orifice is reduced, and a considerable portion of the heat emitted by the inner wall of the nozzle channel is shielded by the heat shield portion 131.

[0048] According to some embodiments, which can be combined with any other embodiment described herein, the distance L2 between the heat shield portion 131 and the orifice 123 is less than the diameter DI of the orifice, particularly less than 50% of the diameter DI of the orifice, more particularly less than 30% of the diameter DI of the orifice, or even less than 20% of the diameter DI of the orifice. Specifically, the ratio L2/D1 (i.e., the ratio between an “effective nozzle depth” and the orifice diameter) may be 1 or less, particularly 0.5 or less, or even 0.3 or 0.2 or less. For example, the ratio L2/D1 may be in the range from 0.35 to 0.5. The ratio L2/D1 in the specified range, that is obtained by the reduction of the effective depth of the nozzle by the insertion of the nozzle insert in the nozzle channel, greatly reduces the effective emissivity and hence the heat radiated from the nozzle. On the other hand, in some embodiments, the ratio L2/D 1 may be above 0.1. If the ratio is chosen too small, the shape of the generated vapor plume may be negatively affected.

[0049] According to some embodiments, which can be combined with other embodiments described herein, a front surface 132 of the heat shield portion 131 that is directed toward the orifice 123 is made of metal, particularly of polished metal. Polished metal has a low intrinsic thermal emissivity, for example a thermal emissivity as of 0.3 or less, particularly 0.2 or less, or even 0.1 or less. For example, the polished metal has a thermal emissivity from 0.05 to 0.3. The front surface of the heat shield portion 131 may be made of a material having a low thermal emissivity of, e.g., as=0.3 or less, particularly 0.2 or less. Accordingly, the heat radiation through the orifice 123 can be further decreased because a major part of both the specular and diffuse radiation from the inner channel walls is shielded by the heat shield portion 131 that has a low intrinsic thermal emissivity. In some embodiments, also the wall of the nozzle channel may be made of metal, particularly of polished metal having, e.g., a thermal emissivity of 0.3 or less, particularly 0.2 or less.

[0050] In some embodiments, which can be combined with other embodiments described herein, 80% or more, particularly 90% or more, of an inner wall surface of the nozzle channel 121 is hidden behind at least one of the heat shield portion 131 and an inwardly protruding front wall 129 of the at least one nozzle, when looking into the nozzle channel from a front side of the nozzle. The heat radiation through the orifice 123 into the deposition area 50 is further reduced because the inwardly protruding front wall 129 shields a part of the inner nozzle cavity.

[0051] FIG. IB shows a front view of the vapor source 100 of FIG. 1A, i.e., a look into the nozzle channel of the at least one nozzle 120 from the perspective of the substrate. As is depicted in FIG. IB, the inner wall surface of the nozzle channel may be almost completely hidden behind the front surface 132 of the heat shield portion 131 (that appears to be a nozzle base) and/or behind the front wall 129 of the nozzle that protrudes radially inwardly. Since the front surface 132 of the heat shield portion 131 may have a low thermal emissivity, the resulting heat radiation through the orifice 123 is low.

[0052] In particular, a ratio between the diameter DI of the orifice (also referred to herein as the orifice diameter DI) and a heat shield portion diameter D2 may be between 0.8 and 1.2, particularly about 1. In other words, the diameter of the heat shield portion 131 may essentially correspond to the diameter of the nozzle outlet, such that, when viewed from the front side of the nozzle, the heat shield portion that is arranged centrally in the nozzle channel may essentially or completely cover the nozzle channel that is arranged behind the heat shield portion and which may correspond to more than 75% of the nozzle channel length.

[0053] For example, the orifice diameter DI, i.e. the dimension of the orifice opening in the radial direction, may be 8 mm or more and 15 mm or less, particularly about 10 mm. The heat shield portion diameter D2, i.e. the dimension of the heat shield portion 131 of the nozzle insert in the radial direction, may be 8 mm or more and 15 mm or less, particularly about 10 mm. Specifically, the orifice diameter DI and the heat shield portion diameter D2 may essentially be the same.

[0054] In some embodiments, which can be combined with other embodiments described herein, a contour and/or a size of the orifice 123 essentially correspond to a contour and/or size of the heat shield portion 131 as viewed from a front side of the nozzle. For example, the orifice 123 may be round or circular, and the heat shield portion 131 may also be round or circular, as is schematically depicted in FIG. IB. The orifice 123 may provide a circular vapor release opening with a diameter between 0.8 mm and 1.2 mm, and the heat shield portion 131 may have circular front surface 132 with a diameter between 0.8 mm and 1.2 mm. In some embodiments, the circular front surface 132 of the heat shield portion 131 is flat and smooth, i.e. without any irregularities. In other embodiments (see FIG. 3 A), one central opening may be provided in the circular front surface 132, but apart from the central opening the circular front surface 132 may be flat and smooth.

[0055] In some embodiments, the heat shield portion 131 is a front portion of the nozzle insert that protrudes toward the orifice and leaves an annular gap between an outer edge of the heat shield portion and the inner channel wall. The channel diameter D3 at the position of the heat shield portion 131 is larger than the orifice diameter DI, such that the vapor flow from the annular vapor flow path 111 toward the orifice 123 may have a radial inwardly directed flow component, considering that the orifice diameter DI is smaller than the diameter of the annular vapor flow path 111.

[0056] In some embodiments, which can be combined with other embodiments described herein, an inner dimension of the nozzle channel 121 continuously or gradually decreases from the channel diameter D3 at a position where the nozzle insert 130 is mounted to the orifice diameter DI at the orifice 123, particularly by 20% or more, or even by 30% or more. For example, the at least one nozzle 120 may have an inwardly protruding front wall 129 that decreases the diameter DI at the orifice 123 as compared to the channel diameter D3 at the position where the nozzle insert is mounted and/or at a position upstream of the nozzle insert.

[0057] For example, the channel diameter D3 at the position where the nozzle insert is mounted may be 12 mm or more and 20 mm or less, particularly between 14 mm and 15 mm. The orifice diameter DI may be 8 mm or more and 11 mm or less, e.g. about 10 mm.

[0058] Since the diameter of the nozzle channel decreases at the orifice, the heat radiation through the orifice is reduced. Specifically, a nozzle with a smaller orifice diameter provides a reduced heat load into the deposition area. Reducing the orifice diameter may also reduce the conductance of the nozzle. In order to maintain a predetermined conductance, the nozzle length can be slightly reduced.

[0059] A decreasing diameter of the nozzle channel at the orifice may provide further advantages: The directionality of the evaporated material with respect to the nozzle axis A can be improved. “Improving the directionality” may be understood to mean that more vapor molecules exit the nozzle at an angle smaller than a predefined maximum cone angle with respect to the nozzle axis A, i.e., within a cone angle a, as compared to a situation in which the nozzle channel is cylindrical at the orifice and does not have a decreasing diameter.

[0060] In particular, the geometry of the nozzle channel may be adapted such that the vapor molecule trajectories are shaped and aligned, and the nozzle acts to concentrate a high percentage of the vapor flux exiting the nozzle into a well-defined, controllable and/or typically narrow cone angle with respect to the nozzle axis A. For example, the nozzle channel may have an inner shape such that more than 80% or more than 90% of a plume flux (i.e., of the vapor molecules) exits the nozzle at an angle of ±25° or less with respect to the nozzle axis A. In this case, the cone angle a of the vapor cone exiting the nozzle is 50°.

[0061] A decreasing channel diameter at the orifice has the effect that vapor molecules propagating toward the orifice at a large angle relative to the nozzle axis A may not be able to exit the nozzle channel but may rather move from one side surface of the nozzle channel to another side surface of the nozzle channel until escaping the nozzle predominantly when a high probability trajectory corresponds to an allowable maximum escape cone angle. Accordingly, the directionality of the vapor plume can be improved and a shadowing effect of the mask that would lead to tilted pixel walls can be reduced.

[0062] In some embodiments, which can be combined with other embodiments described herein, the nozzle insert 130 includes the heat shield portion 131 and a holding portion 133 configured for holding the heat shield portion 131 centrally in the nozzle channel, particularly at a distance from the inner channel wall. In some implementations, the holding portion provides one or more vapor flow passages 134 allowing a flow of the evaporated material therethrough past the heat shield portion 131 along the nozzle channel. For example, the holding portion 133 may include a plurality of support bars 135 extending radially outward toward the inner wall of the nozzle channel. The plurality of support bars 135 may provide the vapor flow passages therebetween.

[0063] In the embodiment depicted in FIG. 1 A and FIG. IB, the holding portion 133 includes, e.g., four support bars 135 extending radially outwardly at a first holding position and arranged at equal angular spacings, wherein the vapor flow passages 134 are provided between the four support bars. Alternatively, only two or three support bars or more than four support bars may be provided that may or may not be provided at equal angular spacings. Optionally, the holding portion 133 may include further support bars 135 extending radially outwardly at a second holding position that is axially spaced from the first holding position. The angular positions of the support bars at the first holding position may correspond to the angular positions of the support bars at the second holding position, in order to provide straight vapor flow passages 134 extending past the heat shield portion. As is schematically depicted in FIGS. 1A and IB, four support bars may be provided at a first holding position, and four support bars may be provided at a second holding position that is axially spaced from the first holding position, each support bar extending radially outwardly from the heat shield portion toward the channel wall. The support bars are configured for reliably holding the heat shield portion centrally in the nozzle channel and act as heat conduction paths to ensure that the heat shield portion remains at a temperature in excess of the condensation temperature of the vapor passing through the nozzle.

[0064] The plurality of support bars 135 may extend radially between the heat shield portion 131 and a ring section of the holding portion that may be press-fitted into the nozzle channel. Accordingly, the nozzle insert 130 can be fixedly mounted in the nozzle channel such that the heat shield portion 131 is centrally held in the nozzle channel, and the nozzle insert 130 may provide a plurality of vapor flow passages 134 that allow a flow of vapor through the nozzle channel past the nozzle insert, and specifically through passages provided in the nozzle insert being shaped as ring sections. Heat radiation through the orifice can be reduced and a good conductance and plume shape can be maintained.

[0065] In some embodiments, which can be combined with other embodiments described herein, the heat shield portion 131 protrudes from the holding portion 133 along the nozzle axis toward the orifice 123 and includes a round or circular front surface 132 facing toward the orifice 123. Accordingly, the front surface 132 of the nozzle insert can be provided close to the orifice, increasing the heat shielding effect provided by the nozzle insert, while a high conductance of the nozzle and an intended shape of the vapor plume emitted by the nozzle can be maintained.

[0066] The distance L2 between the front surface 132 and the orifice 123 can be adapted as appropriate, e.g. in a range between 3 mm and 6 mm. A small distance increases the heat shielding effect of the nozzle insert but may negatively affect the conductance and/or plume shape. A large distance decreases the heat shielding effect but may positively affect the conductance and/or plume shape. A distance L2 in a range between 3.5 mm and 5 mm has turned out to be beneficial in this respect. [0067] FIG. 2 is a schematic sectional view of a vacuum deposition system 200 with a vapor source 100 according to embodiments described herein. The vapor source 100 has a plurality of nozzles. At least one nozzle 120 of the plurality of nozzles may be configured in accordance with any of the embodiments described herein. In particular, two, five or more nozzles provided in a vapor distribution pipe 110 of the vapor source 100 may be configured in accordance with embodiments described herein.

[0068] The plurality of nozzles may have a nozzle channel, respectively, which extends along a nozzle axis A of the respective nozzle toward a deposition area 50 and defines the main evaporation direction of the respective nozzle. In some embodiments, the nozzle axis may extend in an essentially horizontal direction toward the substrate 10. A plurality of plumes of evaporated material can be directed from the interior space of the vapor distribution pipe 110 through the plurality of nozzles toward the substrate 10.

[0069] In implementations, a mask (not depicted) may be arranged between the vapor source 100 and the substrate 10, wherein the mask may be an FMM with an opening pattern which defines a pixel pattern to be deposited on the substrate. For example, the mask may have 100,000 openings or more, particularly 1,000,000 openings or more.

[0070] According to embodiments described herein, the at least one nozzle 120 has a nozzle channel 121 extending along the nozzle axis A from the nozzle inlet to the orifice and a nozzle insert 130 with a heat shield portion arranged centrally inside the nozzle channel 121 for reducing heat radiation from the nozzle channel through the orifice. Each nozzle of the plurality of nozzles may have a corresponding setup, i.e. includes a nozzle insert with a heat shield portion as described herein. In some embodiments, the vapor source may include two, three or more vapor distribution pipes arranged next to each other on a common source support.

[0071] Further, each nozzle may include a nozzle channel with a decreasing nozzle diameter at the orifice. This further reduces the heat emitted by the nozzles and allows a limitation of the spread of the vapor plumes emitted by the nozzles, reducing the shadowing effect of the mask and increasing the pixel quality. For example, the shadow of a pixel edge of a deposited pixel may have a dimension of 3 pm, particularly 2.5 pm or less. Yet, a comparatively high utilization of material can be achieved, since the material does not condense on the at least one nozzle due to a high nozzle temperature inside the nozzle channel that is above the evaporation temperature of the evaporated material. [0072] As is depicted in FIG. 2, the vapor source 100 may include a source support 105, a crucible 102 and the vapor distribution pipe 110 being supported on the source support 105. The source support 105 may be movable along a source transportation path during evaporation. Alternatively, the vapor source may be a stationary source configured for coating a moving substrate.

[0073] FIG. 3A is a schematic sectional view of a part of a vapor source 100’ according to embodiments described herein. FIG. 3B shows a schematic front view of the vapor source 100’ of FIG. 3 A. The vapor source 100’ of FIGS. 3 A and 3B essentially corresponds to the vapor source 100 of FIGS. 1A and IB, such that reference can be made to the above explanations, which are not repeated herein.

[0074] The at least one nozzle 120’ of the vapor source 100’ essentially corresponds to the nozzle 120 of the vapor source 100. Different from the nozzle 120, the centrally arranged heat shield portion 131 of the nozzle insert 130 includes a central opening 140 extending along the nozzle axis A that provides a central vapor flow passage extending along the nozzle axis A. Specifically, a hole or passage may be provided that extends through the center of the nozzle insert 130 along the nozzle axis A, such that vapor can propagate along the central vapor flow passage through the heat shield portion 131 in addition to the annular vapor flow path 111 that surrounds the heat shield portion 131.

[0075] The central opening 140 may facilitate the formation of a well-shaped vapor plume having a small cone angle with respect to the nozzle axis A. The overall plume profile emitted by the nozzle is a superposition of the plume profiles of the vapor molecules having propagated through the central opening 140 and the vapor molecules having propagated along the annular vapor flow path 111. Since the vapor molecules having propagated through the central opening 140 already form a well-defined vapor cone with a small cone angle when exiting the nozzle, the overall plume profile is improved by the central opening 140, even if the central opening 140 is small and only a small part of vapor molecules propagates therethrough.

[0076] For example, a diameter of the central opening 140 may be 3 mm or less, particularly 2 mm or less. The diameter of the central opening 140 may be smaller at the emission end of the central opening 140 as compared to a remaining part of the central opening, as is schematically depicted in FIG. 3B. For example, the diameter of the central opening at the emission end may be 2 mm or less, particularly 1 mm or less. A small diameter of the central opening, particularly a small diameter of the emission end of the central opening, reduces the additional heat radiation through the orifice 123 that is caused by the central opening 140.

[0077] FIG. 4A shows a schematic top view of a vacuum deposition system 200 including a vapor source 100 according to any of the embodiments described herein. The vacuum deposition system 200 includes a vacuum chamber 101 in which the vapor source 100 is provided. According to some embodiments, which can be combined with other embodiments described herein, the vapor source 100 is configured for a translational movement past the deposition area 50 where the substrate 10 to be coated is arranged. Alternatively or additionally, the vapor source 100 may be configured for a rotation around a rotation axis. In particular, the vapor source 100 may be configured for a translational movement in a horizontal direction H along a source transportation path.

[0078] In some embodiments, the vacuum deposition system 200 may include at least one of a first drive 401 for moving the vapor source 100 in the vacuum chamber 101 along a source transportation path and a second drive 403 for rotating the vapor distribution pipe 110 of the vapor source 100. The vapor distribution pipe 110 may be rotated from the deposition area 50 where a substrate 10 and a mask 11 are arranged to a second deposition area 51 on an opposite side of the vapor source 100 where a second substrate 20 and a second mask 21 can be arranged.

[0079] The vapor source 100 may be configured in accordance with any of the embodiments described herein, such that reference can be made to the above explanations, which are not repeated here. Further, the vapor source 100 may include a vapor distribution pipe 110 with nozzles in accordance with any of the embodiments described herein, such that reference can be made to the above explanations, which are not repeated here.

[0080] According to embodiments, the vapor source 100 may have a crucible 102 or two or more crucibles, and a vapor distribution pipe 110 or two or more vapor distribution pipes. For instance, the vapor source 100 shown in FIG. 4A includes two crucibles and two distribution pipes arranged next to each other. As is further shown in FIG. 4A, a substrate 10 and a second substrate 20 may be provided in the vacuum chamber 101 for receiving the evaporated material.

[0081] According to some embodiments, a mask 11 for masking the substrate 10 can be provided between the substrate 10 and the vapor source 100. The mask 11 may be held by a mask frame in a predetermined orientation, particularly in an essentially vertical orientation. In some embodiments, one or more tracks may be provided for supporting and displacing the mask 11. For instance, the embodiment shown in FIG. 4 A has a mask 11 supported by a mask frame arranged between the vapor source 100 and the substrate 10 and a second mask 21 supported by a second mask frame arranged between the vapor source 100 and the second substrate 20. The substrate 10 and the second substrate 20 may be supported on respective transportation tracks in the vacuum chamber 101.

[0082] If masks are used for depositing material on a substrate, such as in an OLED production system, the mask may be a pixel mask with pixel openings having the size of about 50 pm x 50 pm, or less. In one example, the pixel mask may have a thickness of about 40 pm. During the evaporation, the mask 11 and the substrate 10 are typically in contact. Yet, considering the thickness of the mask and the size of the pixel openings, a shadowing effect may appear where the walls surrounding the pixel openings shadow an outer part of the pixel openings. The nozzles as described herein may limit the maximum angle of impact of the evaporated material on the masks and on the substrates and reduce the shadowing effect.

[0083] According to some embodiments described herein, the substrate may be coated with a material in an essentially vertical orientation. Typically, the distribution pipes are configured as line sources extending essentially vertically. In embodiments described herein, which can be combined with other embodiments described herein, the term “vertically” is understood, particularly when referring to the substrate orientation or the extension direction of the distribution pipe, to allow for a deviation from the vertical direction of 15° or less, e.g. of 10° or less. A deviation from the direction of gravity can be provided because a substrate arranged with some deviation from a vertical orientation might result in a more stable deposition process. The surface of the substrate is coated by a line source extending in one direction corresponding to one substrate dimension and by providing a translational movement of the vapor source along another direction corresponding to the other substrate dimension.

[0084] In some embodiments, the vapor source 100 may be provided in the vacuum chamber 101 of the vacuum deposition system 200 on a track. The track is configured for the translational movement of the vapor source 100. According to embodiments, which can be combined with other embodiments described herein, a first drive 401 for the translational movement of the vapor source 100 may be provided at the track or at the source support 105. Accordingly, the vapor source can be moved past the surface of the substrate to be coated during deposition, particularly along a linear path. Uniformity of the deposited material on the substrate can be improved.

[0085] As is schematically depicted in FIG. 4B, the evaporation source may move along the source transportation path past the substrate to be coated, particularly in the horizontal direction H. A thin pattern of material can be evaporated on the substrate during the movement of the source from the source position depicted in FIG. 4 A to the source position depicted in FIG. 4B. The expansions of the plumes of evaporated material may be limited in the vertical direction and/or in the horizontal direction by the geometry of the nozzles that are provided in the distribution pipes.

[0086] As is schematically depicted in FIG. 4C, the distribution pipes of the vapor source 100 may rotate, e.g. by a rotation angle of about 180°, around a vertical rotation axis, to be directed toward the second deposition area 51 where the second substrate 20 is arranged. Coating may continue on the second substrate 20 in the second deposition area 51 of the vacuum chamber 101 by moving the vapor source along the source transportation path back to the source position depicted in FIG. 4A.

[0087] During the deposition, the heat emission from the vapor source 100 toward the mask 11 and toward the second mask 21 can be reduced, since one or more of the plurality of nozzles of the vapor source include a nozzle insert with a heat shield portion as described herein. Due to the reduced heat load, an alignment of the mask relative to the respective substrate is improved and a more accurate material pattern can be deposited on the substrate.

[0088] The vacuum deposition system 200 may be used for various applications, including applications for OLED device manufacturing including processing methods, wherein two or more source materials such as, for instance, two or more organic materials are evaporated simultaneously. 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 m² or more, particularly 1 m² or more. For instance, the deposition system may be adapted for processing large area substrates, such as substrates of GEN 5, which corresponds to about 1.4 m² substrates (1.1 m x 1.3 m), GEN 7.5, which corresponds to about 4.29 m² substrates (1.95 m x 2.2 m), GEN 8.5, which corresponds to about 5.7 m² substrates (2.2 m x 2.5 m), or even GEN 10, which corresponds to about 8.7 m² 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.

[0089] FIG. 5 is a block diagram illustrating a method of operating a vapor source for depositing an evaporated material on a substrate in a vacuum chamber. The vapor source may be a vapor source according to any of the embodiments described herein.

[0090] The material may be heated and evaporated in a crucible, and the evaporated material may propagate via a vapor distribution pipe into a deposition area through a plurality of nozzles provided in the vapor distribution pipe.

[0091] In box 510, evaporated material is directed toward the substrate by the plurality of nozzles. At least one nozzle of the plurality of nozzles includes a nozzle channel extending along a nozzle axis from a nozzle inlet to an orifice that constitutes a vapor release opening.

[0092] In box 520, heat radiation from the nozzle channel through the orifice is reduced with a heat shield portion of a nozzle inlet that is centrally arranged inside the nozzle channel.

[0093] The evaporated material can flow in the nozzle channel along an essentially annular vapor flow path that surrounds the heat shield portion and extends between the heat shield portion and an inner wall of the nozzle channel. Optionally, a portion of the evaporated material may flow through a central opening that is provided in the nozzle insert along the nozzle axis. The central opening of the nozzle insert constitutes a central vapor flow path that improves the directionality and shape of the vapor plume that is emitted by the orifice.

[0094] In some embodiments, which may be combined with other embodiments described herein, the at least one nozzle is heated such that an inner wall of the nozzle channel has a temperature above the evaporation temperature of the evaporated material. A condensation of evaporated material inside the nozzle can be avoided. The material utilization can be increased.

[0095] Embodiments described herein particularly relate to the evaporation of materials on large-area substrates, e.g. for display manufacturing. For example, the substrates may be glass substrates. Embodiments described herein may also relate to semiconductor processing, e.g. for the deposition of materials, such as metals or OLED materials, on semiconductor wafers. The semiconductor wafers may be horizontally or vertically arranged during evaporation. [0096] 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 they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

- 23 -CLAIMS

1. A vapor source (100), comprising a vapor distribution pipe (110) with a plurality of nozzles for directing an evaporated material toward a substrate (10), wherein at least one nozzle (120) of the plurality of nozzles comprises: a nozzle channel (121) extending along a nozzle axis (A) from a nozzle inlet (122) to an orifice (123); and a nozzle insert (130) with a heat shield portion (131) arranged centrally inside the nozzle channel (121) for reducing heat radiation from the nozzle channel through the orifice (123).

2. The vapor source of claim 1, wherein a front surface (132) of the heat shield portion (131) directed toward the orifice (123) is made of polished metal or has a polished metal coating or is made of or coated with a material having an emissivity value less than 0.2, particularly less than 0.1.

3. The vapor source of claim 1 or 2, wherein the at least one nozzle (120) provides an essentially annular vapor flow path (11) that surrounds the nozzle insert (130) and extends between the heat shield portion (131) and an inner wall of the nozzle channel (121) in a direction of the nozzle axis (A).

4. The vapor source of any of claims 1 to 3, wherein a distance (L2) between the heat shield portion (131) and the orifice (123) is less than 50% of the diameter (DI) of the orifice, particularly less than 20% of the diameter (DI) of the orifice.

5. The vapor source of any of claims 1 to 4, wherein a distance (L2) between the heat shield portion (131) and the orifice (123) is less than 50% of a total length (LI) of the nozzle channel, particularly less than 20% of the total length (LI) of the nozzle channel.

6. The vapor source of any of claims 1 to 5, wherein, when viewed from a front side of the at least one nozzle, 90% or more of an inner wall surface of the nozzle channel (121) are hidden behind at least one of the heat shield portion (131) and an inwardly protruding front wall (129) of the at least one nozzle.

7. The vapor source of any of claims 1 to 6, wherein a ratio between the diameter (DI) of the orifice and a heat shield portion diameter (D2) is between 0.8 and 1.2, particularly about 1.

8. The vapor source of any of claims 1 to 7, wherein a contour and/or a size of the orifice (123) essentially correspond to a contour and/or size of the heat shield portion (131) as viewed from a front side of the at least one nozzle (120), particularly wherein both the orifice (123) and the heat shield portion (131) are circular and have a diameter between 8 mm and 12 mm.

9. The vapor source of any of claims 1 to 8, wherein a diameter of the nozzle channel (121) decreases from a channel diameter (D3) at a position where the nozzle insert (130) is mounted to the diameter (DI) of the orifice at the orifice (123), particularly by 20% or more.

10. The vapor source of any of claims 1 to 9, wherein the nozzle insert (130) comprises a holding portion (133) for holding the heat shield portion (131) centrally in the nozzle channel, and the holding portion (133) provides one or more vapor flow passages (134) allowing a flow of the evaporated material past the heat shield portion (131) along the nozzle channel (121).

11. The vapor source of claim 10, wherein the holding portion (133) comprises support bars (135) extending radially outwardly toward an inner wall of the nozzle channel and providing the one or more vapor flow passages (134) therebetween.

12. The vapor source of claim 10 or 11, wherein the heat shield portion (131) protrudes along the nozzle axis (A) from the holding portion (133) toward the orifice and comprises a round or circular front surface (132) facing toward the orifice (123).

13. The vapor source of any of claims 1 to 12, wherein the nozzle insert (130) comprises a central opening (140) providing a central vapor flow passage extending along the nozzle axis (A).

14. A nozzle (120) for a vapor source, comprising a nozzle channel (121) extending along a nozzle axis (A) from a nozzle inlet (122) to an orifice (123) for releasing evaporated material into a vacuum chamber toward a substrate (10); and a nozzle insert (130) with a heat shield portion (131) arranged centrally inside the nozzle channel (121) for reducing heat radiation from the nozzle channel (121) through the orifice (123).

15. A vacuum deposition system (200), comprising: a vacuum chamber (101); the vapor source (100) according to any of claims 1 to 13 provided in the vacuum chamber; and at least one of a first drive for moving the vapor source in the vacuum chamber along a source transportation path and a second drive for rotating the vapor distribution pipe (110) of the vapor source.

16. A method for depositing an evaporated material on a substrate (10) in a vacuum chamber (101), the method comprising: directing the evaporated material toward the substrate by a plurality of nozzles, at least one nozzle (120) of the plurality of nozzles comprising a nozzle channel (121) extending along a nozzle axis (A) from a nozzle inlet (122) to an orifice (123); and reducing heat radiation from the nozzle channel (121) through the orifice (123) with a heat shield portion (131) of a nozzle insert (130) that is centrally arranged inside the nozzle channel (121).

17. The method of claim 16, wherein the evaporated material flows in the nozzle channel along an essentially annular vapor flow path that surrounds the nozzle insert (130) and extends between the heat shield portion (131) and an inner wall of the nozzle channel (121), and optionally through a central opening (140) in the nozzle insert (130) extending along the nozzle axis (A) and providing a central vapor flow passage.