Vapor source, nozzle for vapor source, vacuum deposition system and method for depositing evaporated material

Abstract

Embodiments described herein relate to a vapor source (100) for depositing an evaporation material onto a substrate (10) in a vacuum chamber. The vapor source (100) includes a vapor distribution conduit (110) having a plurality of nozzles for directing the evaporation 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) having a heat shield portion (131) centrally disposed within the nozzle channel (121) to reduce heat radiation from the nozzle channel through the orifice (123). A nozzle for directing the evaporation material onto a substrate, a vacuum deposition system (200), and a method for depositing the evaporation material onto a substrate are also described.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to an apparatus and method 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 having a plurality of nozzles for directing an evaporated material, such as an organic material, toward a substrate to deposit the material on the substrate. Additional embodiments relate to a nozzle for a vapor source, a vacuum deposition system having a vapor source, and a method for depositing an evaporated material on a substrate in a vacuum chamber. Embodiments particularly relate to the deposition of pixel patterns on a substrate, particularly deposition through a fine metal mask, and to deposition sources and systems used in the manufacture of organic light emitting diode (OLED) devices. Background Art

[0002] Techniques for depositing layers on substrates include, for example, thermal evaporation, physical vapor deposition (PVD), and chemical vapor deposition (CWD). The coated substrates can be used in a number of applications and in a number of technical fields. For example, the coated substrates can 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 handheld devices, etc. to display information. OLED devices, such as OLED displays, can include one or more layers of organic material located between two electrodes, both deposited on a substrate.

[0003] During deposition, substrate can be supported on a carrier that holds the substrate and is aligned with the mask. Steam from a steam source is directed to the substrate, through the mask to produce a patterned film on the substrate. One or more materials can be deposited onto the substrate through one or more masks to produce individually addressable small pixels to produce functional devices (such as full-color displays). Producing clearly defined pixels is beneficial to display quality, and the clearly defined pixels have almost vertical walls and have uniform thickness over the entire area of ​​the pixel. In order to achieve this result, the steam molecules should advantageously not undercut the mask or be blocked by the edge portions of the mask, which would cause deposition in the space between pixels or cause the pixel to have a rounded edge. In practice, this means that the steam molecule trajectory perpendicular to the substrate plane or a small angle deviation from the normal (such as 30 ° or less from the normal) is beneficial.

[0004] To reduce or avoid misalignment between the mask and substrate, the heat load from the vapor source to the deposition area should be as low as possible. Specifically, excessive heat radiation from the vapor source to the mask can cause 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 the area between the vapor source and the mask to reduce thermally induced misalignment between the substrate and the mask.

[0005] Reducing the heat load entering the deposition area is difficult because the temperatures inside the vapor source and vapor nozzle are higher than the evaporation temperature of the material being deposited. Cooling baffles located between the vapor nozzle and the mask cause material to condense on the baffles, thereby reducing material utilization and increasing costs, as a significant portion of the vapor generated in the source may collect as condensate on the cooling plate rather than being deposited on the substrate.

[0006] In view of the foregoing, improved apparatus and methods for depositing materials on substrates would be beneficial. Embodiments of the present disclosure are directed to providing systems, apparatus, arrangements, and methods for depositing materials that overcome at least some of the aforementioned problems. Specifically, the heat load from the vapor source to the deposition area should be reduced, and a well-defined pattern of material should be accurately deposited on the substrate. Summary of the Invention

[0007] In view of the above, a vapor source for depositing an evaporation material on a substrate, a nozzle for the vapor source, a vacuum deposition system, and a method for depositing an evaporation material on a substrate are provided.

[0008] According to one aspect of the present disclosure, a vapor source is provided. The vapor source includes a vapor distribution conduit having a plurality of nozzles for directing a vapor deposition material toward a substrate. At least one 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 also includes a nozzle insert having a heat shield centrally disposed within the nozzle channel to reduce heat radiation from the nozzle channel through the orifice.

[0009] In particular, the heat shield portion may be arranged in a central region of the nozzle channel such that a substantially annular vapor flow path extends around the heat shield portion in the direction of the nozzle axis between the heat shield portion and an inner wall of the nozzle channel. Since the heat shield portion is arranged within the nozzle channel, thermal radiation from the inner wall of the nozzle channel through the orifice is at least partially blocked or reflected by the heat shield portion, thereby reducing the heat load on the mask from the at least one nozzle.

[0010] The heat shield portion may also be referred to as a "low-emissivity heat shield portion" because it reduces the effective thermal emissivity of the nozzle compared to a nozzle having a corresponding shape but without the heat shield portion. Specifically, the heat shield portion may be made of or include a material having low thermal emissivity and may shield at least a portion of the thermal radiation radiated from the inner channel wall of the nozzle, thereby reducing the heat load from the nozzle on the mask and the substrate.

[0011] According to one aspect of the present disclosure, a nozzle for a vapor source, particularly a vapor source according to any of the embodiments described herein, is provided. 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 also includes a nozzle insert having a heat shield portion centrally disposed within the nozzle channel to reduce heat radiation from the nozzle channel through the orifice.

[0012] According to another 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, the vapor source disposed within the vacuum chamber. Furthermore, at least one of a first actuator for moving the vapor source along a source transport path within the vacuum chamber and a second actuator for rotating a distribution conduit of the vapor source is provided.

[0013] According to another 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 through a plurality of nozzles, at least one 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 using a heat shield portion of a nozzle insert centrally disposed within the nozzle channel.

[0014] Embodiments also relate to apparatus for performing the disclosed methods and include apparatus portions for performing each described method aspect. These method aspects can be performed using hardware components, a computer programmed with appropriate software, any combination of the two, or in any other manner. In addition, embodiments according to the present disclosure also relate to methods for manufacturing the described apparatus and products, as well as methods for operating the described apparatus. Additional embodiments relate to substrates, such as display devices, coated according to any of the methods or using any of the vapor sources described herein. The described embodiments include method aspects for performing each function of the described apparatus. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order that the above-recited features of the present disclosure may be understood in detail, a more particular description of the present disclosure, briefly summarized above, may be obtained by reference to the embodiments. The accompanying drawings relate to the embodiments of the present disclosure and are described as follows:

[0016] Figure 1A shows a schematic cross-sectional view of a portion of a vapor source according to embodiments described herein;

[0017] Figure 1B Show Figure 1A A schematic front view of a vapor source;

[0018] Figure 2 shows a schematic cross-sectional view of a vacuum deposition system having a vapor source including a plurality of nozzles according to embodiments described herein;

[0019] Figure 3A shows a schematic cross-sectional view of a portion of a vapor source according to embodiments described herein;

[0020] Figure 3B Show Figure 3A A schematic front view of a vapor source;

[0021] Figures 4A to 4C shows successive stages of a method for depositing an evaporated material on a substrate using a vacuum deposition system according to embodiments described herein;

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

[0023] Figure 6 is a graph showing the effective thermal emissivity of the nozzle cavity according to the length of the nozzle channel. DETAILED DESCRIPTION

[0024] Reference will now be made in detail to various embodiments of the present disclosure, one or more examples of which are shown in the drawings. In the following description of the drawings, like reference numerals refer to like parts. Generally speaking, only the differences with respect to individual embodiments are described. Each example is provided by way of illustration and is not intended to be limiting of the present disclosure. Features shown or described as part of one embodiment may be used on or in conjunction with other embodiments to produce yet another embodiment. The specification is intended to include such modifications and variations.

[0025] As used herein, the term "evaporation material" may be understood as a material that is evaporated and deposited on the surface of a substrate. For example, the evaporation 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, for example, 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 evaporation materials include one or more of: 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 that provides an evaporation material to be deposited on a substrate. In particular, the vapor source may be configured to guide the evaporation material to be deposited on the substrate into a deposition area in a vacuum chamber. The evaporation material may be directed toward the substrate via a plurality of nozzles of the vapor source. The nozzles may each have a nozzle outlet (also referred to herein as an "orifice") that may be directed toward the deposition area, in particular toward the substrate to be coated, wherein the mask is arranged in front of the substrate.

[0027] The vapor source may include an evaporator (or "crucible") that evaporates the material to be deposited on the substrate and a vapor distribution conduit fluidly connected to the crucible and configured to direct the evaporated material to a plurality of nozzles to release plumes of the evaporated material into a deposition area in the vacuum chamber.

[0028] In some embodiments, the steam source comprises two or more distribution pipes, wherein each distribution pipe comprises a plurality of nozzles. For example, each distribution pipe comprises two or more nozzles, particularly ten or more nozzles, and more particularly thirty or more nozzles. The nozzles of the steam distribution pipes can be arranged in a linear array or row to provide a line source. In some embodiments, the steam source comprises two or more steam distribution pipes arranged adjacent to each other, wherein each of the two or more steam distribution pipes comprises ten or more nozzles arranged in a row.

[0029] This disclosure generally describes details and features of "at least one nozzle" of a plurality of nozzles of a steam distribution conduit. However, it should be understood that two, three, five, ten, or all of the plurality of nozzles may be constructed and configured in a corresponding manner and may have corresponding features. Specifically, all of the nozzles of the steam distribution conduit may be configured according to the at least one nozzle described herein.

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

[0031] In some embodiments, the vapor source may include two or three vapor distribution conduits, each extending in a substantially vertical direction (V). Each distribution conduit may be fluidly connected to a corresponding crucible, such that different materials can be co-deposited on the substrate. The nozzle of a first vapor distribution conduit and the nozzle of an adjacent second vapor distribution conduit may be arranged close to each other, for example, at a distance of 5 cm or less, to enable uniform co-deposition of two or more materials on the substrate.

[0032] Figure 1A is a cross-sectional view of a vapor source 100 for depositing an evaporation material on a substrate 10 according to embodiments described herein. Figure 1B is a front view of the vapor source 100 .

[0033] The steam source 100 comprises a steam distribution conduit 110 which may extend in a substantially vertical direction V. Alternatively, the distribution conduit may extend in another direction, such as a substantially horizontal direction. Figure 1A In the depicted embodiment, the vapor distribution conduit 110 provides a substantially vertical line source. A vapor distribution conduit 110 extending substantially vertically may be beneficial because the system footprint 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 conduits, which are supported on a source support that may be movable. The two or more vapor distribution conduits may extend in a substantially vertical direction. As used herein, "substantially vertical" refers to a direction corresponding to the direction of gravity or a direction with 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 vapor deposition material to the substrate 10. Specifically, the plurality of nozzles allows the vapor deposition material to be directed from the interior space of the vapor distribution pipe 110 to the deposition area 50 in the vacuum chamber where the substrate 10 is disposed. In some embodiments, 10 or more nozzles, particularly 30 or more nozzles, may be provided at the vapor distribution pipe 110. The plurality of nozzles may be arranged in a linear arrangement along the longitudinal direction of the vapor distribution pipe 110 (see FIG. 1 ). Figure 2 ).

[0035] Figure 1A One of the plurality of nozzles is shown in detail in a cross-sectional view. The other nozzles may be configured in a similar or corresponding manner. At least one nozzle 120 includes a nozzle channel 121 extending along a nozzle axis A from a nozzle inlet 122 to an orifice 123. Evaporation material from the vapor distribution conduit 110 may enter the nozzle channel 121 at the nozzle inlet 122, through which the evaporation material may flow toward the orifice 123, and through which the evaporation material may exit the nozzle channel 121. The orifice 123 is configured to emit a vapor plume 15 of the evaporation material through the deposition area 50 toward the substrate 10.

[0036] According to embodiments described herein, at least one nozzle 120 includes a nozzle insert 130 disposed within a nozzle channel 121. The nozzle insert 130 includes a heat shield portion 131 centrally disposed within the nozzle channel 121 and configured to reduce heat radiation from the nozzle channel 121 through the orifice 123 to 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 installed in the nozzle channel and includes a heat shield portion 131 for reducing heat radiation from at least one nozzle into the deposition area 50. The nozzle insert 130 can be fixed in the nozzle channel in a form-fitting manner and / or in a force-fitting manner (e.g., by press-fitting). For example, the nozzle insert 130 can be inserted into the nozzle channel in a cooled and contracted state, so that the nozzle insert 130 expands during heating and is press-fitted to the channel wall of the nozzle channel.

[0038] The heat shield 131 can be centrally arranged in the nozzle channel. In other words, the heat shield 131 can be arranged in a central region of the nozzle channel at or near the nozzle axis A (not necessarily exactly at the nozzle axis), thereby leaving a steam flow path that can surround the heat shield in the radial edge region of the nozzle channel. In order to still allow steam flow through the nozzle channel 121 toward the orifice 123, a gap can be provided between the heat shield 131 and the inner wall of the nozzle channel, in particular a radial gap that surrounds the heat shield 131 in the circumferential direction. In particular, the heat shield 131 can be maintained at a distance from the inner wall of the nozzle channel 121. In particular, a substantially annular steam flow path 111 extending along the nozzle channel 121 can surround the heat shield 131.

[0039] In some embodiments, a substantially annular vapor flow path 111 can be provided between the heat shield portion 131 and the inner wall of the nozzle channel 121 for directing the evaporated material through the nozzle insert in the direction of the nozzle axis. Alternatively or additionally, the heat shield portion 131 can have one or more openings or through-holes extending substantially in the direction of the nozzle axis and providing a vapor flow path through the nozzle channel toward the orifice.

[0040] "Centrally arranged" does not refer to the center of the heat shield portion in the axial direction. Instead, the heat shield portion 131 is typically arranged closer to the orifice 123 in the axial direction than the nozzle inlet 122 to increase the shielding effect provided by the heat shield portion 131. In some embodiments, the axial distance L2 between the heat shield portion 131 and the orifice 123 is less than 50% of the total length L1 of the nozzle passage 121, that is, the heat shield portion 131 is arranged closer to the nozzle outlet than to the nozzle inlet. For example, the distance L2 between the 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 L1 of the nozzle passage. In other words, the heat shield portion 131 can be arranged close to the orifice 123 while still within the nozzle passage. Placing the heat shield portion 131 close to the orifice 123 is advantageous because a large portion of the thermal radiation from the inner wall surface of the nozzle passage can be shielded by the heat shield portion arranged close to the nozzle outlet.

[0041] In some embodiments, the total length L1 of the nozzle passage 121 can be 15 mm or more and 30 mm or less, particularly 20 mm or more and 25 mm or less, for example, about 22 mm. The distance L2 between the downstream end of the heat shield portion 131 and the orifice 123 can be 2 mm or more and 8 mm or less, particularly 3 mm or more and 5 mm or less. Thus, the heat shield portion 131 shields the section of the nozzle passage arranged behind the heat shield portion (which is the main section of the nozzle passage because L2 / L1 is generally less than 0.5) from thermal radiation, thereby significantly reducing the heat emitted through the orifice.

[0042] In some embodiments that may be combined with other embodiments described herein, at least one nozzle 120 has a substantially annular vapor flow path 111 that surrounds the heat shield 131 and extends between the heat shield 131 and the inner wall of the nozzle channel in the direction of the nozzle axis. Specifically, a circumferential gap around the centrally arranged heat shield 131 constitutes the vapor flow path 111 along which the evaporated material flows through the nozzle channel.

[0043] Providing a nozzle insert 130 having a heat shield portion 131 centrally disposed in the nozzle passage 121 is beneficial for the following reasons:

[0044] The interior of the vapor nozzle is hot, so thermal radiation is directed toward the substrate through the nozzle's orifice. A smaller nozzle diameter (i.e., a smaller nozzle orifice diameter) reduces the heat load from the nozzle. However, nozzles with a small nozzle diameter have reduced conductivity and, therefore, a lower deposition rate, making it not always possible to reduce the nozzle diameter to reduce the heat load.

[0045] Furthermore, the thermal emissivity ε of a nozzle with a given nozzle diameter increases with nozzle depth L (i.e., with the total length of the nozzle channel). Simply put, deep nozzles generally radiate more heat than short nozzles because deep nozzles with long nozzle channels have larger internal channel surfaces, particularly larger internal channel walls, which contribute to the heat load provided by the nozzle into the deposition area. However, the directionality and shape of the vapor plume provided by the nozzle generally improve with increasing nozzle depth L, making it not always possible to simply reduce the nozzle channel length to reduce the heat load.

[0046] Figure 66 is a graph showing the thermal emissivity ε of a conventional cylindrical steam nozzle as a function of 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. It can be seen that the thermal emissivity ε of the nozzle increases with increasing nozzle depth L. Curve 620 shows the theoretical calculation of thermal emissivity as a function of nozzle depth L, and value 610 is the measured emissivity value of a nozzle having diffuse reflectivity for exemplary nozzle depths between 0 and 10 mm.

[0047] According to the embodiments described herein, a nozzle 120 is provided that simultaneously provides a well-shaped vapor plume with good directionality and reduced heat load into the deposition area. The nozzle 120 has a nozzle channel extending along a nozzle axis A, and the nozzle channel has a length and diameter suitable for providing a predetermined conductivity and a well-defined vapor plume in the main emission direction of the nozzle. The nozzle insert 130 has a heat shield portion 131 that effectively reduces the nozzle depth and thus reduces heat radiation from the nozzle through the orifice. When viewed from the front of the nozzle (see Figure 1B ), heat shield 131, centrally located within the nozzle channel, appears to constitute the nozzle base and, therefore, defines the nozzle depth. The heat shield effectively reduces the nozzle depth, thereby "moving" the nozzle base toward the orifice. The effective nozzle depth is less than the total length L1 of the nozzle channel and corresponds to the axial distance L2 between the heat shield and the orifice. Consequently, heat radiation from the nozzle channel through the orifice is reduced, with a significant portion of the heat emitted by the nozzle channel's inner wall being shielded by heat shield 131.

[0048] According to some embodiments, which may be combined with any other embodiments described herein, the distance L2 between the heat shield 131 and the orifice 123 is less than the orifice diameter D1, particularly less than 50% of the orifice diameter D1, more particularly less than 30% of the orifice diameter D1, or even less than 20% of the orifice diameter D1. Specifically, the ratio L2 / D1 (i.e., the ratio between the "effective nozzle depth" and the orifice diameter) can be 1 or less, particularly 0.5 or less, or even 0.3 or 0.2 or less. For example, the ratio L2 / D1 can range from 0.35 to 0.5. A ratio L2 / D1 within a specific range (obtained by reducing the effective nozzle depth by inserting a nozzle insert into the nozzle channel) significantly reduces the effective emissivity and, therefore, significantly reduces the heat radiated from the nozzle. On the other hand, in some embodiments, the ratio L2 / D1 can be greater than 0.1. If the ratio is selected to be too small, the shape of the resulting vapor plume may be negatively affected.

[0049] According to some embodiments, which can be combined with other embodiments described herein, the front surface 132 of the heat shield portion 131 directed toward the orifice 123 is made of metal, in particular of polished metal. Polished metal has a low intrinsic thermal emissivity, for example a thermal emissivity ε of 0.3 or less. S , in particular 0.2 or less, or even 0.1 or less. For example, the thermal emissivity of polished metal is 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 (e.g., ε S =0.3 or less, in particular 0.2 or less). Therefore, since most of the specular radiation and diffuse radiation from the inner channel wall is shielded by the heat shield portion 131 with low intrinsic thermal emissivity, the thermal radiation through the orifice 123 can be further reduced. In some embodiments, the wall of the nozzle channel can also be made of metal, in particular, a polished metal with a thermal emissivity of 0.3 or less, in particular 0.2 or less.

[0050] In some embodiments that may be combined with other embodiments described herein, when viewing the nozzle channel from the front of the nozzle, 80% or more, and in particular 90% or more, of the inner wall surface of the nozzle channel 121 is hidden behind at least one of the heat shield portion 131 and the inwardly protruding front wall 129 of at least one nozzle. Since the inwardly protruding front wall 129 shields a portion of the inner nozzle cavity, heat radiation entering the deposition area 50 through the orifice 123 is further reduced.

[0051] Figure 1B Shown Figure 1A A front view of the vapor source 100 is shown, i.e., the nozzle channel of at least one nozzle 120 is viewed from the perspective of the substrate. Figure 1B As shown, the inner wall surface of the nozzle passage can be almost completely hidden behind the front surface 132 of the heat shield portion 131 (which appears to be the nozzle base) and / or behind the radially inwardly protruding front wall 129 of the nozzle. Because the front surface 132 of the heat shield portion 131 can have a low thermal emissivity, the thermal radiation generated by the orifice 123 is low.

[0052] In particular, the ratio between the diameter D1 of the orifice (also referred to herein as orifice diameter D1) and the diameter D2 of the heat shield portion may be between 0.8 and 1.2, in particular about 1. In other words, the diameter of the heat shield portion 131 may substantially correspond to the diameter of the nozzle outlet, so that when viewed from the front of the nozzle, the heat shield portion centrally arranged in the nozzle channel may substantially or completely cover the nozzle channel arranged behind the heat shield portion, and the nozzle channel arranged behind the heat shield portion may correspond to more than 75% of the nozzle channel length.

[0053] For example, the orifice diameter D1, i.e., the radial dimension of the orifice opening, can be 8 mm or more and 15 mm or less, in particular, about 10 mm. The heat shield diameter D2, i.e., the radial dimension of the heat shield portion 131 of the nozzle insert, can be 8 mm or more and 15 mm or less, in particular, about 10 mm. In particular, the orifice diameter D1 and the heat shield diameter D2 can be substantially the same.

[0054] In some embodiments, which may be combined with other embodiments described herein, the profile and / or size of the orifice 123 substantially corresponds to the profile and / or size of the heat shield portion 131 as viewed from the front of the nozzle. For example, the orifice 123 may be rounded or circular, and the heat shield portion 131 may also be rounded or circular, such as Figure 1B As schematically depicted. The orifice 123 may provide a circular vapor release opening having a diameter between 0.8 mm and 1.2 mm, and the heat shield portion 131 may have a circular front surface 132 having 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 Figure 3A ), a central opening may be provided in the circular front surface 132, but except for the central opening, the circular front surface 132 may be flat and smooth.

[0055] In some embodiments, heat shield portion 131 is a front portion of the nozzle insert that protrudes toward the orifice and leaves an annular gap between the outer edge of the heat shield portion and the inner channel wall. The channel diameter D3 at heat shield portion 131 is larger than the orifice diameter D1, so that given that orifice diameter D1 is smaller than the diameter of annular steam flow path 111, the steam flow from annular steam flow path 111 toward orifice 123 can have a flow component directed radially inward.

[0056] In some embodiments, which may be combined with other embodiments described herein, the inner dimension of the nozzle passage 121 decreases continuously or gradually from the passage diameter D3 at the location where the nozzle insert 130 is installed to the orifice diameter D1 at the orifice 123, particularly by 20% or more, or even by 30% or more. For example, at least one nozzle 120 may have an inwardly protruding front wall 129 that reduces the diameter D1 at the orifice 123 compared to the passage diameter D3 at the location where the nozzle insert is installed and / or upstream of the nozzle insert.

[0057] For example, the channel diameter D3 where the nozzle insert is mounted may be 12 mm or more and 20 mm or less, in particular between 14 mm and 15 mm.The orifice diameter D1 may be 8 mm or more and 11 mm or less, for example about 10 mm.

[0058] Because the nozzle passage diameter decreases at the orifice, heat radiation through the orifice is reduced. Specifically, nozzles with smaller orifice diameters reduce the heat load entering the deposition area. Reducing the orifice diameter may also reduce the nozzle's conductivity. To maintain a desired conductivity, the nozzle length can be slightly reduced.

[0059] The reduced diameter of the nozzle channel at the orifice can provide a further advantage: the directionality of the evaporated material relative to the nozzle axis A can be improved. "Improved directionality" can be understood to mean that more vapor molecules leave the nozzle at angles less than a predetermined maximum cone angle relative to the nozzle axis A (i.e., within the cone angle α) compared to a situation where the nozzle channel at the orifice is cylindrical and does not have a reduced diameter.

[0060] In particular, the geometry of the nozzle channel can be adjusted so that the vapor molecule trajectories are shaped and aligned, and the nozzle is used to concentrate a high percentage of the vapor flux exiting the nozzle into a well-defined, controllable, and / or typical narrow cone angle relative to the nozzle axis A. For example, the nozzle channel can have an internal shape such that greater than 80% or greater than 90% of the plume (i.e., the plume of vapor molecules) exits the nozzle at an angle of ±25° or less relative to the nozzle axis A. In this case, the cone angle α of the vapor cone exiting the nozzle is 50°.

[0061] The reduced channel diameter at the orifice has the following effect: vapor molecules propagating toward the orifice at a large angle relative to the nozzle axis A may not be able to leave the nozzle channel, but may instead move from one side surface of the nozzle channel to another, until escaping the nozzle primarily when the high-probability trajectory corresponds to the maximum allowable escape cone angle. As a result, the directionality of the vapor plume can be improved and the shadowing effect of the mask that would cause pixel walls to tilt can be reduced.

[0062] In some embodiments, which may be combined with other embodiments described herein, the nozzle insert 130 includes a heat shield portion 131 and a retaining portion 133, the retaining portion being configured to retain the heat shield portion 131 centrally within the nozzle channel, particularly at a distance from the inner channel wall. In some embodiments, the retaining portion provides one or more vapor flow paths 134 to allow a flow of evaporated material to flow through the heat shield portion 131 along the nozzle channel. For example, the retaining portion 133 may include a plurality of support rods 135 extending radially outward toward the inner wall of the nozzle channel. The plurality of support rods 135 may provide vapor flow paths therebetween.

[0063] exist Figure 1A and Figure 1BIn the illustrated embodiment, the retaining portion 133 includes, for example, four support rods 135 extending radially outwardly at a first retaining position and arranged at equal angular intervals, with the vapor flow path 134 being provided between the four support rods. Alternatively, only two or three support rods or more than four support rods may be provided, which may or may not be provided at equal angular intervals. Optionally, the retaining portion 133 may include further support rods 135 extending radially outwardly at a second retaining position axially spaced from the first retaining position. The angular position of the support rods in the first retaining position may correspond to the angular position of the support rods in the second retaining position so as to provide a straight vapor flow path 134 extending through the heat shield portion. As Figure 1A and Figure 1B As shown schematically, four support rods may be provided at a first holding position, and four support rods may be provided at a second holding position axially spaced from the first holding position, each support rod extending radially outward from the heat shield toward the passage wall. The support rods are configured to securely hold the heat shield centered within the nozzle passage and to serve as a heat conduction path to ensure that the heat shield is maintained at a temperature exceeding the condensation temperature of vapor passing through the nozzle.

[0064] A plurality of support rods 135 may extend radially between the heat shield portion 131 and the annular section of the retaining portion, which may be press-fitted into the nozzle passage. Thus, the nozzle insert 130 may be fixedly mounted in the nozzle passage, such that the heat shield portion 131 is centrally retained therein, and the nozzle insert 130 may provide a plurality of vapor flow passages 134 that allow vapor to flow through the nozzle passage, specifically through passages provided in the nozzle insert, which is shaped as an annular section. This reduces heat radiation through the orifice, and maintains good conductivity and plume shape.

[0065] In some embodiments, which may be combined with other embodiments described herein, the heat shield portion 131 protrudes from the retaining portion 133 along the nozzle axis toward the orifice 123 and includes a rounded or rounded front surface 132 facing the orifice 123. Thus, the front surface 132 of the nozzle insert can be positioned close to the orifice, thereby increasing the heat shielding effect provided by the nozzle insert while maintaining high conductance of the nozzle and a desired shape of the vapor plume emitted by the nozzle.

[0066] The distance L2 between the front surface 132 and the orifice 123 can be adjusted appropriately, for example, within a range between 3 mm and 6 mm. A smaller distance increases the heat shielding effect of the nozzle insert, but may negatively impact conductivity and / or plume shape. A larger distance reduces the heat shielding effect, but may positively impact conductivity and / or plume shape. In this regard, a distance L2 between 3.5 mm and 5 mm has proven beneficial.

[0067] Figure 2 is a schematic cross-sectional view of a vacuum deposition system 200 having a vapor source 100 according to an embodiment described herein. The vapor source 100 has a plurality of nozzles. At least one nozzle 120 of the plurality of nozzles can be configured according to any of the embodiments described herein. In particular, two, five, or more nozzles disposed in the vapor distribution conduit 110 of the vapor source 100 can be configured according to the embodiments described herein.

[0068] The plurality of nozzles may each have a nozzle channel extending along a nozzle axis A of the corresponding nozzle toward the deposition area 50 and defining a main evaporation direction of the corresponding nozzle. In some embodiments, the nozzle axis may extend in a substantially horizontal direction toward the substrate 10. A plurality of evaporation material plumes may be directed from the interior space of the vapor distribution conduit 110 toward the substrate 10 through the plurality of nozzles.

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

[0070] According to embodiments described herein, at least one nozzle 120 has a nozzle channel 121 extending from a nozzle inlet to an orifice along a nozzle axis A and a nozzle insert 130 having a heat shield portion centrally disposed within the nozzle channel 121 to reduce heat radiation from the nozzle channel through the orifice. Each nozzle in the plurality of nozzles may have a corresponding configuration, i.e., including a nozzle insert having a heat shield portion as described herein. In some embodiments, the vapor source may include two, three, or more vapor distribution conduits disposed adjacent to each other on a common source support.

[0071] In addition, each nozzle may include a nozzle channel with a reduced nozzle diameter at the orifice. This further reduces the heat emitted by the nozzle and allows for limiting the spread of the vapor plume emitted by the nozzle, thereby reducing shadowing effects on the mask and improving pixel quality. For example, the shadow of the pixel edge of a deposited pixel may have a size of 3 μm, particularly 2.5 μm or less. Furthermore, a relatively high material utilization rate can be achieved because, due to the high nozzle temperature within the nozzle channel, which is higher than the evaporation temperature of the evaporated material, material does not condense on at least one nozzle.

[0072] like Figure 2As shown, the vapor source 100 may include a source support 105, a crucible 102, and a vapor distribution conduit 110 supported on the source support 105. The source support 105 may be movable along a source transport path during evaporation. Alternatively, the vapor source may be a stationary source configured for coating a moving substrate.

[0073] Figure 3A is a schematic cross-sectional view of a portion of a vapor source 100 ′ according to embodiments described herein. Figure 3B Shown Figure 3A Schematic front view of a vapor source 100'. Figure 3A and Figure 3B The vapor source 100' corresponds substantially to Figure 1A and Figure 1B The steam source 100 can be referred to the above description and will not be repeated here.

[0074] The at least one nozzle 120′ of the steam source 100′ substantially corresponds to the nozzle 120 of the steam source 100. Unlike the nozzle 120, the centrally disposed heat shield portion 131 of the nozzle insert 130 includes a central opening 140 extending along the nozzle axis A, which provides a central steam flow path extending along the nozzle axis A. Specifically, a hole or channel extending through the center of the nozzle insert 130 along the nozzle axis A may be provided so that, in addition to the annular steam flow path 111 surrounding the heat shield portion 131, steam may also propagate along the central steam flow path through the heat shield portion 131.

[0075] Central opening 140 promotes the formation of a well-shaped vapor plume having a small cone angle relative to nozzle axis A. The overall plume profile emitted by the nozzle is the superposition of the plume profiles of vapor molecules that have propagated through central opening 140 and vapor molecules that have propagated along annular vapor flow path 111. Because the vapor molecules that have propagated through central opening 140 have formed a well-defined vapor cone having a small cone angle upon exiting the nozzle, the overall plume profile is improved by central opening 140, even though central opening 140 is small and only a small portion of vapor molecules propagate therethrough.

[0076] For example, the diameter of the central opening 140 may be 3 mm or less, in particular 2 mm or less. The diameter of the central opening 140 may be smaller at the emitting end of the central opening 140 than at the rest of the central opening, e.g. Figure 3B As schematically depicted. For example, the diameter of the central opening at the emitting end can be 2 mm or less, particularly 1 mm or less. The small diameter of the central opening, particularly the small diameter at the emitting end of the central opening, reduces the additional heat radiation through the aperture 123 caused by the central opening 140.

[0077] Figure 4AA schematic top view of a vacuum deposition system 200 including a vapor source 100 according to any of the embodiments described herein is shown. The vacuum deposition system 200 includes a vacuum chamber 101 in which the vapor source 100 is disposed. According to some embodiments, which may be combined with other embodiments described herein, the vapor source 100 is configured for translational movement through a deposition area 50 in which a substrate 10 to be coated is disposed. Alternatively or additionally, the vapor source 100 can be configured to rotate about an axis of rotation. In particular, the vapor source 100 can be configured for translational movement in a horizontal direction H along a source transport path.

[0078] In some embodiments, the vacuum deposition system 200 may include at least one of a first driver 401 for moving the vapor source 100 along the source transport path in the vacuum chamber 101 and a second driver 403 for rotating the vapor distribution conduit 110 of the vapor source 100. The vapor distribution conduit 110 may be rotated from a deposition area 50 where the substrate 10 and the 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 may be arranged.

[0079] The steam source 100 can be configured according to any of the embodiments described herein, so reference can be made to the above description and no further description is given here. In addition, the steam source 100 can include a steam distribution pipe 110 having a nozzle according to any of the embodiments described herein, so reference can be made to the above description and no further description is given here.

[0080] Depending on the embodiment, the vapor source 100 may have a crucible 102 or two or more crucibles, and a vapor distribution conduit 110 or two or more vapor distribution conduits. For example, Figure 4A The vapor source 100 shown includes two crucibles and two distribution pipes arranged adjacent to each other. Figure 4A As further shown, the substrate 10 and the second substrate 20 may be provided in the vacuum chamber 101 to receive the evaporated material.

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

[0082] If the mask is used to deposit material on a substrate, such as in an OLED production system, the mask can be a pixel mask having a pixel opening of about 50 μm × 50 μm or less. In one example, the pixel mask can have a thickness of about 40 μm. During evaporation, the mask 11 and the substrate 10 are generally in contact. However, given the thickness of the mask and the size of the pixel opening, a shadow effect may occur, in which the walls surrounding the pixel opening cast a shadow on the outer portion of the pixel opening. The nozzle described herein can limit the maximum impact angle of the evaporated material on the mask and the substrate and reduce the shadow effect.

[0083] According to some embodiments described herein, the substrate can be coated with material in a substantially vertical orientation. Typically, the distribution conduit is configured as a line source extending substantially vertically. In the embodiments described herein that can be combined with other embodiments described herein, in particular when it comes to the orientation of the substrate or the extension direction of the distribution conduit, the term "vertically" is understood to allow deviations from the vertical direction of 15° or less, for example, 10° or less. Deviations from the direction of gravity can be provided because substrates arranged with some deviations from the vertical orientation may result in a more stable deposition process. The surface of the substrate is coated by a line source extending in one direction corresponding to the size of one substrate and by providing a translational movement of the vapor source along another direction corresponding to the size of another substrate.

[0084] In some embodiments, the vapor source 100 can be disposed on a track within the vacuum chamber 101 of the vacuum deposition system 200. The track is configured for translational movement of the vapor source 100. According to embodiments that can be combined with other embodiments described herein, a first actuator 401 for translational movement of the vapor source 100 can be provided on the track or on the source support 105. Thus, during deposition, the vapor source can be moved across the surface of the substrate to be coated, particularly along a linear path. This can improve the uniformity of the deposited material on the substrate.

[0085] like Figure 4B As schematically depicted, the evaporation source can be moved along a source transport path past the substrate to be coated, in particular in a horizontal direction H. Figure 4A The source position of the depicted Figure 4B During the depicted movement of the source position, a thin pattern of material can be evaporated onto the substrate.The expansion of the plume of evaporated material can be limited in the vertical and / or horizontal directions by the geometry of the nozzle disposed in the distribution conduit.

[0086] like Figure 4CAs schematically depicted in FIG, the distribution pipe of the vapor source 100 can be rotated about a vertical rotation axis (eg, a rotation angle of about 180°) to point to the second deposition area 51 where the second substrate 20 is arranged. The coating can be performed by moving the vapor source back along the source transport path. Figure 4A The depicted source positions continue on the second substrate 20 in the second deposition zone 51 of the vacuum chamber 101 .

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

[0088] The vacuum deposition system 200 can be used in various applications, including applications for OLED device manufacturing (including processing methods), in which two or more source materials, such as, for example, two or more organic materials, are simultaneously evaporated. The embodiments described herein are particularly related to the deposition of organic materials, such as for example, for OLED display manufacturing on large area substrates. According to some embodiments, the large area substrate or the carrier supporting one or more substrates may have a thickness of 0.5 μm. 2 or larger, especially 1m 2 For example, the deposition system may be adapted to process large area substrates, such as Generation 5 (which corresponds to approximately 1.4 m 2 Substrate (1.1m×1.3m)), 7.5th generation (which corresponds to about 4.29m 2 substrate (1.95m×2.2m)), 8.5th generation (which corresponds to about 5.7m 2 substrate (2.2m x 2.5m)) or even the 10th generation (which corresponds to about 8.7m 2 Even higher generations (such as Gen 11 and Gen 12) and corresponding substrate areas can be similarly realized.

[0089] Figure 5 is a block diagram illustrating a method of operating a vapor source to deposit an evaporation 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 the crucible, and the evaporated material may be propagated into a deposition area via a vapor distribution conduit through a plurality of nozzles disposed in the vapor distribution conduit.

[0091] In block 510, a plurality of nozzles are used to direct 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 defining a vapor release opening.

[0092] In block 520 , heat radiation from the nozzle passage through the orifice is reduced with a heat shield portion of the nozzle inlet centrally disposed within the nozzle passage.

[0093] The vapor deposition material can flow within the nozzle passage along a substantially annular vapor flow path that surrounds the heat shield and extends between the heat shield and the inner wall of the nozzle passage. Optionally, a portion of the vapor deposition material can flow through a central opening disposed in the nozzle insert along the nozzle axis. The central opening of the nozzle insert defines a central vapor flow path that improves the directionality and shape of the vapor plume emitted by the orifice.

[0094] In some embodiments that may be combined with other embodiments described herein, at least one nozzle is heated so that the inner wall of the nozzle channel has a temperature higher than the evaporation temperature of the evaporation material. This can prevent condensation of the evaporation material inside the nozzle and improve material utilization.

[0095] The embodiments described herein particularly relate to the evaporation of materials onto large-area substrates, such as those used in display manufacturing. For example, the substrate may be a glass substrate. The embodiments described herein may also relate to semiconductor processing, for example, for depositing materials, such as metals or OLED materials, onto semiconductor wafers. The semiconductor wafers may be positioned horizontally or vertically during evaporation.

[0096] This written description uses examples to disclose the present 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. Although various specific embodiments have been disclosed in the foregoing, non-mutually exclusive features of the embodiments described above may be combined with each other. The scope of patent protection is defined by the claims, and it is contemplated that other examples are within the scope of the claims so long as they have structural elements that do not differ from the literal language of the claims, or so long as they include equivalent structural elements with insubstantial differences from the literal language of the claims.

Claims

1. A vapor source (100), comprising a vapor distribution conduit (110), the vapor distribution conduit having a plurality of nozzles for directing a vapor deposition material toward a substrate (10), wherein at least one nozzle (120) of the plurality of nozzles comprises: a nozzle passage (121) extending along the nozzle axis (A) from the nozzle inlet (122) to the orifice (123); as well as A nozzle insert (130) having a heat shielding portion (131) arranged centrally inside the nozzle channel (121), wherein the heat shielding portion (131) has a front surface (132) pointing towards the orifice (123) and the heat shielding portion (131) is arranged in the nozzle channel for reducing heat radiation from a section of the nozzle channel arranged behind the heat shielding portion (131) through the orifice (123), and wherein a flow path is provided around the nozzle insert, the flow path extending between the heat shielding portion (131) and the inner wall of the nozzle channel (121) in the direction of the nozzle axis (A).

2. The vapor source of claim 1, wherein the nozzle insert (130) is fixedly mounted in the nozzle passage.

3. The vapor source according to claim 1, wherein the front surface (132) of the heat shielding portion (131) is made of polished metal or has a polished metal coating or is made of or coated with a material having an emissivity value of less than 0.

2.

4. The vapor source of claim 1, wherein the flow path (11) is a substantially annular vapor flow path (11).

5. The vapor source of claim 1, wherein a distance (L2) between the heat shield portion (131) and the orifice (123) is less than 50% of a diameter (D1) of the orifice.

6. The steam source according to any one of claims 1 to 5, wherein the distance (L2) between the heat shield portion (131) and the orifice (123) is less than 50% of the total length (L1) of the nozzle channel.

7. The vapor source of claim 6, wherein a distance (L2) between the heat shield portion (131) and the orifice (123) is less than 20% of a total length (L1) of the nozzle passage.

8. A steam source as described in any one of claims 1 to 5, wherein 90% or more of the inner wall surface of the nozzle channel (121) is hidden behind at least one of the heat shielding portion (131) and the inwardly protruding front wall (129) of the at least one nozzle when viewed from the front of the at least one nozzle.

9. The vapor source according to any one of claims 1 to 5, wherein the ratio between the diameter of the orifice (D1) and the diameter of the heat shield (D2) is between 0.8 and 1.

2.

10. A steam source as claimed in any one of claims 1 to 5, wherein, viewed from the front of the at least one nozzle (120), at least one of the contour and size of the orifice (123) substantially corresponds to the contour and / or the at least one of the sizes of the heat shielding portion (131).

11. The vapor source of claim 10, wherein both the orifice (123) and the heat shield portion (131) are circular and have a diameter between 8 mm and 12 mm.

12. The steam source of any one of claims 1 to 5, wherein the diameter of the nozzle passage (121) decreases by 20% or more from the passage diameter (D3) at the location where the nozzle insert (130) is installed to the diameter (D1) of the orifice at the orifice (123).

13. A vapor source as described in any one of claims 1 to 5, wherein the nozzle insert (130) includes a retaining portion (133) for retaining the heat shielding portion (131) centrally in the nozzle channel, and the retaining portion (133) provides one or more vapor flow paths (134) to allow the flow of the evaporation material to pass through the heat shielding portion (131) along the nozzle channel (121).

14. The vapor source of claim 13, wherein the retaining portion (133) includes support rods (135) extending radially outward toward an inner wall of the nozzle passage and providing the one or more vapor flow passages (134) therebetween.

15. The steam source of claim 13, wherein the heat shield portion (131) protrudes from the retaining portion (133) toward the orifice along the nozzle axis (A) and includes a rounded or circular front surface (132) facing the orifice (123).

16. The vapor source of any one of claims 1 to 5, wherein the nozzle insert (130) includes a central opening (140) providing a central vapor flow path extending along the nozzle axis (A).

17. A nozzle (120) for a steam source, comprising a nozzle channel (121) extending along a nozzle axis (A) from a nozzle inlet (122) to an orifice (123) for releasing the evaporated material into the vacuum chamber toward the substrate (10); and A nozzle insert (130) having a heat shielding portion (131) arranged centrally inside the nozzle channel (121), wherein the heat shielding portion (131) has a front surface (132) pointing towards the orifice (123) and the heat shielding portion (131) is arranged in the nozzle channel for reducing heat radiation from a section of the nozzle channel (121) arranged behind the heat shielding portion (131) through the orifice (123), and wherein a flow path is provided around the nozzle insert, the flow path extending between the heat shielding portion (131) and the inner wall of the nozzle channel (121) in the direction of the nozzle axis (A).

18. A vacuum deposition system (200), comprising: a vacuum chamber (101); The vapor source (100) according to any one of claims 1 to 5, wherein the vapor source is arranged in the vacuum chamber; as well as At least one of a first drive for moving the vapor source along a source transport path in the vacuum chamber and a second drive for rotating the vapor distribution conduit (110) of the vapor source.

19. A method for depositing an evaporation material on a substrate (10) in a vacuum chamber (101), the method comprising: directing the evaporated material toward the substrate through a plurality of nozzles, at least one nozzle (120) of the plurality of nozzles comprising a nozzle channel (121) extending from a nozzle inlet (122) to an orifice (123) along a nozzle axis (A); and Heat radiation from a section of the nozzle channel (121) through the orifice (123) is reduced by a heat shielding portion (131) of a nozzle insert (130) centrally arranged inside the nozzle channel (121), wherein the heat shielding portion (131) has a front surface (132) pointing towards the orifice (123) and the section of the nozzle channel (121) is arranged behind the heat shielding portion (131), and wherein the evaporation material flows in the nozzle channel along a vapor flow path, which surrounds the nozzle insert (130) and extends between the heat shielding portion (131) and the inner wall of the nozzle channel (121) in the direction of the nozzle axis (A).

20. The method of claim 19, wherein the vapor flow path is a substantially annular vapor flow path and the evaporation material flows through a central opening (140) in the nozzle insert (130) extending along the nozzle axis (A) and providing a central vapor flow passage.

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