Method for using TLE system and TLE system

Abstract

The invention relates to a method of using a thermal laser evaporation (TLE) system (10), the TLE system (10) comprising: a reaction chamber (12) fillable with a reaction atmosphere (14); a substrate (16) arranged in the reaction chamber (12); one or more sources (40) arranged in the reaction chamber (12), each source (40) comprising a source component (50) consisting of a source material (52); and a laser source (20) for providing a heating laser beam (22) that irradiates an upper surface (60) of the source assembly (50) with a heating spot (24) to vaporize or sublimate the source material (52) from an active area (62) on the upper surface (60) of the source assembly (50) to provide a flux (54) of the vaporized or sublimated source material (52) for deposition onto the substrate (16). Further, the invention relates to a thermal laser evaporation (TLE) system (10), the TLE system (10) comprising: a reaction chamber (12) fillable with a reaction atmosphere (14); a substrate (16) arranged in the reaction chamber (12); one or more sources (40) arranged in the reaction chamber (12), each source (40) comprising a source component (50) consisting of a source material (52); and a laser source (20) for providing a heating laser beam (22) that irradiates an upper surface (60) of the source assembly (50) with a heating spot (24) to vaporize or sublimate the source material (52) from an active area (62) on the upper surface (60) of the source assembly (50) to provide a flux (54) of the vaporized or sublimated source material (52) for deposition onto the substrate (16).

Description

Technical Field

[0001] The present invention relates to a method using a thermal laser evaporation (TLE) system, the TLE system comprising: a reaction chamber that can be filled with a reaction atmosphere; a substrate disposed in the reaction chamber; one or more sources disposed in the reaction chamber, each source comprising a source element composed of a source material; and a laser source for providing a heating laser beam that irradiates the upper surface of the source element with a heating spot, thereby evaporating or sublimating the source material from an active area on the upper surface of the source element to provide a flux of the evaporated or sublimated source material for deposition onto the substrate. Further, the present invention relates to a corresponding TLE system, the TLE system comprising: a reaction chamber that can be filled with a reaction atmosphere; a substrate disposed in the reaction chamber; one or more sources disposed in the reaction chamber, each source comprising a source element composed of a source material; and a laser source for providing a heating laser beam that irradiates the upper surface of the source element with a heating spot, thereby evaporating or sublimating the source material from an active area on the upper surface of the source element to provide a flux of the evaporated or sublimated source material for deposition onto the substrate. Background Art

[0002] In thermal laser evaporation (TLE), the source material is evaporated and / or sublimated by laser heating in a controlled environment (especially in a reaction chamber filled with a reaction atmosphere), typically for coating a substrate also disposed in the reaction chamber.

[0003] In most cases, a uniform substrate coating is required. Generally, this requires at least a time-constant directional intensity distribution of the flux from the evaporated or sublimated source material. However, such a directional intensity distribution strongly depends on the three-dimensional shape of the upper surface of the source element, which is the origin of the evaporated and / or sublimated material.

[0004] Unfortunately, as the source material is evaporated and / or sublimated locally depleting the source element, the three-dimensional shape of the upper surface changes over time. This is in Figure 1is depicted, with sub - figure A on the left depicting the evaporation of the source material 52 of the source component 50 at an earlier stage, and sub - figure B on the right depicting the evaporation at a later stage. During both stages, the heating laser beam 22 irradiates the upper surface 60 of the source component 50 composed of the source material 52. The source material 52 sublimes from the active region 62, forming a flux 54 of the sublimed source material 52. It can be clearly seen that at the beginning, when the upper surface 60 and thus the active region 62 are flat (sub - figure A), the direction - intensity distribution of the flux 54 indicated by the arrows is significantly different from the corresponding direction distribution of the flux 54 at a later stage when the source material 52 is depleted and the active region 62 forms a recessed portion of the upper surface 60 (sub - figure B). This change in the direction - intensity distribution of the flux ultimately leads to a change in the deposition of the sublimed source material 52 on the substrate 16 (see Figure 8 ). Thereby, the quality of the deposited and thus coated substrate 16 may be significantly reduced. SUMMARY OF THE INVENTION

[0005] In view of the above, an object of the present invention is to provide an improved method of using a thermal laser evaporation system and an improved thermal laser evaporation system that do not have the aforementioned disadvantages of the prior art. In particular, an object of the present invention is to provide an improved method of using a thermal laser evaporation system and an improved thermal laser evaporation system that allow for the stable deposition of evaporated and / or sublimed source material onto a substrate, especially where a selected direction - intensity distribution of the flux of the evaporated or sublimed source material can be provided over an extended period of time, preferably continuously.

[0006] This object is achieved by the corresponding independent patent claims. Specifically, the object is achieved by a method of using a thermal laser evaporation system according to independent claim 1 and by a thermal laser evaporation system according to independent claim 28. The dependent claims describe preferred embodiments of the present invention. Details and advantages described with respect to the method according to the first aspect of the present invention also relate to the thermal laser evaporation system according to the second aspect of the present invention, and vice versa, if of technical significance.

[0007] According to a first aspect of the present invention, this object is achieved by a method of using a thermal laser evaporation (TLE) system, the TLE comprising: a reaction chamber that can be filled with a reaction atmosphere; a substrate arranged in the reaction chamber; one or more sources arranged in the reaction chamber, each source comprising a source component composed of a source material; and a laser source for providing a heating laser beam that irradiates the upper surface of the source component with a heating spot to evaporate or sublime the source material from an active region on the upper surface of the source component to provide a flux of the evaporated or sublimed source material for deposition onto the substrate, wherein the method comprises the step of providing a selected direction - intensity distribution of the flux of the evaporated or sublimed source material by actively adjusting the three - dimensional shape of the active region.

[0008] The method according to the first aspect of the present invention is intended to use a thermal laser evaporation system, or not to use a TLE system. Specifically, the scope of the present invention is a TLE system in which a laser is used to evaporate or sublime a source material. Such systems are well known. The heating laser beam provided by the laser source is used to evaporate or sublime the source material, and in most cases, to deposit the evaporated or sublimed source material onto a substrate provided as a target. The source material is provided as a source component in a source arranged in a reaction chamber, where one or more sources are possible, especially to provide different source materials. The heating laser beam irradiates the upper surface of the source component at a heating position, and the heating laser beam irradiates a heating spot on the said upper surface. The actual evaporation or sublimation occurs at the active area on the upper surface, where the active area is connected to the heating spot and may even be the same as the heating spot. From the active area, a flux of the evaporated or sublimed source material is provided, which includes a directional intensity distribution of the flux depending on the three-dimensional shape of the active area.

[0009] This source is arranged in a reaction chamber, which can be sealed relative to the ambient atmosphere and filled with a reaction atmosphere. The reaction atmosphere can be a vacuum, especially as low as 10 -12 hPa or even lower, or contain a reaction gas with a pressure suitable for the material to be deposited, for example, a reaction gas providing oxygen to deposit an oxide of the evaporated and / or sublimed elemental or compound source material. So far, the maximum value tested at a working distance of 60 mm is up to 10 -2 hPa. There may be even higher values, because deposition may be possible at 10 -2 hPa.

[0010] In most cases, at least the main part of the laser source is arranged outside the reaction chamber, and the heating laser beam is coupled into the reaction chamber via a coupling device. The coupling device can be, for example, a simple window in the chamber wall of the reaction chamber. However, the coupling device according to the present invention can also include an adaptive optics component for forming the heating laser beam irradiating the upper surface of the source component.

[0011] In the method according to the first aspect of the present invention, the three-dimensional shape of the active area is actively adjusted. Active adjustment in the sense of the present invention encompasses all ways of influencing the three-dimensional shape before and especially during the evaporation or sublimation process. Adjustment of the active area can also be provided by active adjustment of the upper surface, because the active area is an inherent part of the upper surface.

[0012] There are many different types and ways to adjust the three-dimensional shape, for example, by correspondingly selecting the dimensions of the source component and the dimensions of the heating laser beam, and / or compensating for the material consumption caused by ongoing evaporation or sublimation. The above-mentioned ways of adjusting the three-dimensional shape can be implemented individually or in combination. Moreover, the ways and measures suitable for the evaporation process can be different from those suitable for the sublimation process. Generally speaking, by adjusting the three-dimensional shape, a selected three-dimensional shape of the active area can be provided. Active adjustment allows the provision of the three-dimensional shape also during the evaporation or sublimation process, preferably at all times during the process.

[0013] As mentioned above, the directional intensity distribution of the flux depends on, in particular strongly depends on, the three-dimensional shape of the active area. In summary, by actively adjusting the three-dimensional shape of the active area, a selected directional intensity distribution of the flux of the source material for evaporation or sublimation can be provided during the operation of the TLE system. Thereby, a stable deposition of the source material for evaporation and / or sublimation onto the substrate can be provided.

[0014] Furthermore, the method according to the present invention may include adjusting the three-dimensional shape of the active area by actively selecting and / or changing the following items: – the size of the heating spot relative to the size of the upper surface and / or the size of the active area, and / or – the position of the heating spot on the upper surface, and / or – the spatial intensity distribution of the heating laser beam, and / or – the temporal structure of the heating laser beam intensity.

[0015] This list is not complete and can be extended by further appropriate ways and measures to actively adjust the three-dimensional shape of the active area.

[0016] In addition, the method according to the present invention is characterized in that the adjustment of the three-dimensional shape of the active area is performed repeatedly, specifically continuously. In the sense of the present invention, repetition covers a repetition rate of 100 mHz or lower, up to 10 MHz or higher. In other words, during the evaporation or sublimation process, an active adjustment is provided with repeated or even continuous execution. Thereby, also during the evaporation or sublimation process, the provision of the selected three-dimensional shape of the active area can be ensured repeatedly, preferably continuously. Thereby, the directional flux of the source material for evaporation or sublimation can also be provided repeatedly or even continuously with its selected characteristics.

[0017] Additionally, the method according to the present invention may include that the intensity distribution of the selected direction of the flux includes a constant time-dependence or at least a periodic time-dependence. In particular, if averaged over one or more cycle lengths, a flux having a periodic time-dependence may also be considered constant. A flux having a constant or at least time-periodic direction intensity distribution allows for very precise deposition of material onto a substrate. In particular, the thickness of the source material deposited at a specific location on the substrate mainly depends on the constant flux irradiating the material at that location and the duration of deposition. The overall time-dependence of the source material flux can be avoided. Thus, the stable deposition of the evaporated and / or sublimated source material onto the substrate can be enhanced.

[0018] According to a first alternative of an embodiment of the method according to the present invention, the method may include providing a flux by sublimating from a solid state with a heating laser beam, and wherein the size of the heating spot is adjusted to be equal to or greater than the size of the upper surface to provide the entire upper surface as the active area for the sublimated source material. Thereby, the lateral dimension of the upper surface and thus the lateral dimension of the active area are both limited by and simultaneously defined by the boundaries of the source assembly. During sublimation, a steady state is established, which is defined by controllable boundary conditions, such as the parameters of the heating laser beam, the size of the upper surface, and the temperature distribution thus self-established in the source assembly. Therefore, the flux of the sublimated source material can be provided constantly over time, enabling a stable deposition of the sublimated source material onto the substrate.

[0019] Additionally, this method can be enhanced by: the source includes an actuator for moving the source assembly, and thereby moving the source assembly to keep the spatial position of the active area constant relative to the heating laser beam and the substrate to compensate for the material loss due to the sublimated source material. During sublimation, the source material is slowly removed from the active area and the upper surface respectively, and thus from the source assembly. Therefore, the spatial position of the active area relative to the irradiating heating laser beam and the substrate changes slightly over time. For example, the distance between the active area and the substrate increases. By using the actuator of the source to move the source assembly, the said material loss can be compensated, and the relative spatial position of the active area relative to the heating laser beam and the substrate can be kept constant over time. In the foregoing example, the source assembly moves towards the substrate at a pace correspondingly selected according to the sublimation rate of the source material. Thereby, changes in the direction intensity distribution of the flux of the evaporated source material due to material loss can be avoided.

[0020] Alternatively or additionally, the heating laser beam itself can also be moved to keep the spatial position of the active region constant relative to the heating laser beam and the substrate, to compensate for the material loss due to the sublimated source material. For example, optical components such as mirrors and / or lenses can be used to move the position of the heating laser beam. Generally speaking, all the advantages described above regarding the actuator for moving the source component can also be provided by the corresponding optical components for moving the heating laser beam.

[0021] In a second alternative embodiment, the method according to the invention is characterized in that the heating laser beam melts the source material for forming the active region as a pool of molten source material and evaporates the source material from the pool, thereby providing a flux of the source material, and wherein the size of the heating spot is adjusted to be smaller than the size of the upper surface to form a pool and thus form an active region having a selected size and a selected curvature. The curvature of such a pool of molten source material contained by the remaining and still solid source material of the source component is given, for example, by the surface tension of the molten source material, the density of the molten source material and the gravity acting on the molten source material, as well as by the temperature gradient applied by the heating laser beam and formed within the material, which has the possibility of driving convection, and the convection itself will affect the shape of the surface.

[0022] The surface curvature of the pool and thus the curvature of the active region are reproducibly dependent on these parameters on the diameter and shape of the surface boundary line between the liquid and the solid and the contact angle at this boundary. In most cases, for a given source material and the intensity of the heating laser beam to achieve a given deposition rate, the size of the pool of molten source material is fixed, and thus, the curvature of the active region (i.e., the surface of the pool) can be easily controlled, and thereby the directional density distribution of the flux of the evaporated source material can be easily controlled. In short, also in this embodiment of the method according to the invention, the directional intensity distribution of the flux of the evaporated source material can be provided in a selected manner, so that a stable deposition of the evaporated source material on the substrate can be provided.

[0023] In addition, the method according to the invention can also adjust the size of the heating spot by correspondingly adjusting the intensity distribution of the heating laser beam, especially regarding the overall intensity and / or spatial distribution and / or size and / or position and / or shape of the intensity distribution of the heating laser beam. This list is not complete and can be extended by further suitable ways and measures for actively adjusting the intensity distribution of the heating laser beam. In other words, the size of the heating spot can be actively selected by providing a heating laser beam whose intensity distribution includes correspondingly adjusted characteristics.

[0024] In a first implementation of the third and alternative embodiment of the method according to the present invention, the heating laser beam melts the source material for forming the active region into a pool of molten source material, and evaporates the source material from the pool, thereby providing a flux of the source material, and wherein the size of the heating spot is adjusted to be equal to or larger than the size of the upper surface to form a pool of molten source material on the entire upper surface as the active region, and wherein the intensity of the heating laser beam is adjusted to form the pool, thereby forming an active region having a selected curvature. Contrary to the embodiment described in the previous paragraph, the size of the heating spot is now selected such that the entire upper surface of the source assembly is not only illuminated by the heating laser beam but also melted.

[0025] In a second implementation of the third embodiment of the method according to the present invention, the heating laser beam melts the source material for forming the active region into a pool of molten source material, and evaporates the source material from the pool, thereby providing a flux of the source material, and wherein the intensity of the heating laser beam is adjusted to form a pool of molten source material on the entire upper surface as the active region, and wherein the intensity of the heating laser beam is further adjusted to form the pool, thereby forming an active region having a selected curvature. Similar to the first implementation of the third embodiment, in the second implementation of the third embodiment of the method according to the present invention, a pool of molten source material is formed on the entire upper surface as the active region. Compared with the first implementation, the melting of the entire upper surface is provided by sufficiently increasing the intensity of the laser beam, thereby ensuring that the source assembly absorbs sufficient laser energy for the melting of the entire upper surface.

[0026] In other words, in both implementations of the third embodiment of the method according to the present invention, the pool of molten source material extends over the entire upper surface, and the active region is the same as the upper surface. Once the edge of the pool of molten source metal reaches the edge of the source assembly and thus the outer edge of the surface, the surface of the pool typically becomes convex, and in extreme cases, a suspension droplet with a contact angle exceeding 90° is formed. However, the size of the droplet can be easily controlled by appropriately selecting the intensity of the heating laser beam. Thus, by correspondingly setting the intensity of the heating laser beam, different curvatures of the active region can be easily selected and adjusted. In other words, since the directional intensity distribution of the flux of the evaporated source material strongly depends on the curvature of the emission surface, the directional intensity distribution can also be provided in a selected and chosen manner, thereby allowing the evaporated source material to be stably deposited on the substrate.

[0027] Furthermore, the method according to the invention can be enhanced by the pool comprising a flat mean curvature. Preferably, this condition can be provided by providing a source assembly having a flat upper end and by setting the intensity of the heating laser beam such that only a thin film of molten source material is present at the upper end of the source assembly, which thin film covers the upper surface and simultaneously forms the active area. Thus, the surface shape of the active area mostly follows the flat shape of the upper end of the source assembly, and only high curvature values occur at the edges. Generally speaking, by providing a pool of molten source material having a flat mean curvature, the directional intensity distribution of the flux of the evaporated source material can also be provided with an extended area of constant flux. Thereby, a stable and particularly uniform deposition of the evaporated source material on the substrate can be provided.

[0028] Additionally, the method according to the invention can be enhanced again by the source comprising an actuator for moving the source assembly, and thereby moving the source assembly to keep the spatial position of the active area constant relative to the heating laser beam and the substrate, to compensate for the material loss due to the evaporated source material. And, during the evaporation process, the source material is removed from the active area and the upper surface respectively, and thus from the source assembly. Similar to the corresponding description regarding the sublimation process above, the spatial position of the active area relative to the irradiated heating laser beam and the substrate also changes over time. By using the actuator of the source to move the source assembly, the said material loss can be compensated, and the relative spatial position of the active area relative to the heating laser beam and the substrate can be kept constant over time. Thereby, a change in the directional intensity distribution of the flux of the evaporated source material due to the material loss can be avoided.

[0029] In an alternative fourth embodiment of the method according to the invention, the method is characterized in that the source comprises a crucible and the source assembly is arranged in the crucible, and wherein the heating laser beam completely melts the source material in the crucible to form an active area as a pool of molten source material at the entire upper surface, and evaporates the source material from the pool, thereby providing a flux of the source material, and wherein the crucible material of the crucible is selected relative to the source material for forming the pool, so as to form an active area having a selected curvature.

[0030] The molten source material in the crucible forms a contact angle with the crucible material. The contact angle in the sense of the present invention, also called the wetting angle, is measured in a plane locally perpendicular to the contact line at the contact line inside the source material. In particular, a small contact angle will generally result in a concave surface of the molten source material and thus a concave surface of the active area, while a large contact angle will result in a convex surface of the active area. In other words, the contact angle has a great influence on the curvature of the active area.

[0031] The contact angle depends to a large extent on the source material and the crucible material, respectively. For a metal source material within an oxide crucible, such as gallium within a sapphire crucible, this contact angle is typically large. A metal or semiconductor as a source material within a crucible made of a metal crucible material, such as germanium within a tantalum crucible, typically has a small contact angle. Thus, for a source material for which there are different suitable crucible materials, this mechanism can be utilized to control the contact angle and thus the curvature. In summary, by correspondingly selecting the crucible material, the curvature of the active region can be actively selected, and thus the directional intensity distribution of the flux of the evaporated source material can be actively selected.

[0032] Furthermore, the method according to the invention can include correspondingly selecting the three-dimensional shape of the crucible to provide the selected curvature. As described above, the contact angle is measured at the contact line within the source material. The contact line is defined as the line at which the molten source material separates from the crucible. In other words, one leg of the contact angle extends along the exposed surface of the molten source material, and the other leg extends along the crucible wall surrounding the molten source material. Thus, by correspondingly selecting the three-dimensional shape of the crucible, the contact angle can be directly affected. Thereby, the curvature of the active region can be actively selected, and thus the directional intensity distribution of the flux of the evaporated source material can be actively selected.

[0033] Additionally, the method according to the invention can be further enhanced by the crucible being completely filled or overfilled due to its surface tension with the source material. In other words, the contact line that defines the contact angle and thus the curvature coincides with the upper edge of the crucible, and is thus geometrically fixed to and anchored to the said edge of the crucible. Furthermore, a variety of source materials include a large surface tension in their respective molten states, allowing for a strong overfilling of the crucible. Since the contact line is geometrically held fixed to the edge of the crucible, this results in a change in the overall convex curvature of the active region, especially selectable by the amount of overfilling of the crucible.

[0034] Alternatively or additionally, the method according to the invention can also be enhanced by the heating spot being smaller than the upper surface and the active region, respectively, and wherein the heating position of the heating spot at the active region is selected relative to the local curvature of the active region at the said heating position.

[0035] For a large amount of source material within a large-diameter crucible, gravity typically overcomes the surface tension and produces a melt with an upper surface that is very close to planar and horizontal at its center. This is also typically the preferred position of the heating spot of the heating laser beam for forming the active region at this highly symmetric point. This results in a directional intensity distribution of the flux of the evaporated source material with high spatial uniformity.

[0036] However, by using a geometry of the heating laser beam that is asymmetric with respect to the crucible center, the highest temperature point and thus the active region can also be shifted to other regions of the upper surface. This allows another way to control the directional intensity distribution of the flux through the curvature of the upper surface, since the upper surface includes a position-dependent curvature and the position of the active region within the upper surface can be actively selected by correspondingly positioning the heating location of the heating spot.

[0037] According to an alternative fifth embodiment, the method according to the invention may comprise the step of providing a selected directional intensity distribution of a flux of evaporating source material, the step comprising a preparation step and a subsequent evaporation step, wherein in the preparation step, a three-dimensional shape of the entire upper surface is formed, thereby providing a three-dimensional shape of the active region that is part of the upper surface with respect to the selected directional intensity distribution of the flux, and in the evaporation step, the heating laser beam evaporates and / or sublimates the source material from the active region.

[0038] As described above, the three-dimensional shape of the active region significantly affects the directional intensity distribution of the flux of evaporating source material originating from the active region. Thus, by actively forming the three-dimensional shape of the upper surface and thus also automatically forming the three-dimensional shape of the active region that is an inherent part of the upper surface, a flux of evaporating and / or sublimating source material including a selected directional intensity distribution can be provided.

[0039] In the preparation step, the shaping of the upper surface is provided. The shaping process may include any process capable of changing the three-dimensional shape, such as machining, ablation, sintering, and also includes melting and subsequent controlled solidification. In particular, the most suitable shaping process can be selected for each respective source, for example, taking into account the size of the source material and / or the source assembly as a whole, the size of the upper surface, and / or the size of the active region.

[0040] In the subsequent evaporation step, the laser beam is irradiated onto the upper surface of the source assembly such that the source material is evaporated and / or sublimated at the intended active region. Since the active region prepared in the preparation step includes a specific three-dimensional shape adapted to the expected and selected directional intensity distribution of the flux of evaporating and / or sublimating source material, the directional intensity distribution can be automatically provided for the flux. Thus, also by this embodiment of the method according to the invention, a stable deposition of the evaporating and / or sublimating source material onto the substrate can be provided.

[0041] Furthermore, the method according to the present invention can be enhanced in the following way: In the preparation step, a shaping laser beam that irradiates the upper surface of the source component with a shaped light spot is used to adjust the three-dimensional shape of the upper surface, where the shaping laser beam is used to melt the source material and / or to provide a controlled solidification of the molten source material. During melting by the shaping laser, in particular, the source component arranged in the crucible can be completely or only partially melted. For a source without a crucible and thus having a self-supporting source component, only the source material of the upper surface or even only a part of the upper surface (such as the active area and / or its surroundings) is melted to a certain depth into the source component. The shaped light spot of the shaping laser can thus cover the entire upper surface or only a part of the upper surface, such as in particular the active area.

[0042] Controlled solidification in the sense of the present invention encompasses any measure that allows influencing the three-dimensional shape of the upper surface during solidification. By using a shaping laser during the solidification process, the time sequence of solidification can be influenced. In other words, some light spots on the upper surface solidify prior to other light spots, especially in the case where the shaping laser irradiates subsequent light spots to prevent premature solidification. Furthermore, the difference in density between the molten state and the solid state of the source material can be utilized here to influence the desired three-dimensional shape of the resulting upper surface. In summary, by using a shaping laser for the preparation step, various possible three-dimensional shapes of the upper surface can be provided.

[0043] For a further improvement of the method according to the present invention, the shape of the shaped light spot and / or the position of the shaped light spot on the upper surface are correspondingly adjusted to provide a controlled solidification of the molten source material. The shape in the sense of the present invention not only encompasses, for example, a shaped light spot with a circular or elliptical shape, but also a shaped light spot that is divided into two or more separate sub spots and / or a shaped light spot that includes a local intensity minimum within the shaped light spot (such as an annular shaped light spot). And the movement of the shaped light spot of the shaping laser that effectively forms the time-averaged area where the shaping laser acts on the source material is a shaped light spot in the sense of the present invention. Thus, during controlled solidification, the time sequence of solidification can be particularly easily influenced, especially in combination with the above-mentioned utilization of the difference in density changes between the molten source material and the solid source material.

[0044] For example, if the source material in the solid state has a higher density compared to its molten state, at the beginning of the solidification process, the shaping laser irradiates a single shaped light spot, effectively forming a mound-like or tip-like three-dimensional shape of the upper surface, including a local convex curvature. Conversely, at the beginning of the solidification process, the shaping laser irradiates an annular shaped light spot, effectively forming an annular mound, resulting in a depression in the middle of the three-dimensional shape of the upper surface, including a local concave curvature.

[0045] Furthermore, the method according to the invention is characterized in that the heating laser beam used for evaporating and / or sublimating the source material from the active area of the source component in the evaporation step is used as the shaping laser beam in the preparation step. In other words, the laser beam provided by the laser source can be used as the heating laser beam and the shaping laser beam, respectively. The parameters of each laser beam, such as the overall intensity, beam direction, intensity distribution, temporal structure, and / or repetition rate, can be the same or different during their respective use as the heating laser beam and the shaping laser beam. In summary, by using the same laser beam for heating and shaping, respectively, the overall setup of the TLE system configured to perform the method according to the invention can be simplified.

[0046] In addition, the method according to the invention can include alternately and repeatedly performing the preparation step and the subsequent evaporation step. As described above, since material loss occurs during the evaporation process, the actual three-dimensional shape of the active area may change over time. By stopping the evaporation step and re-performing the preparation step, this change in the three-dimensional shape of the active area can be controlled and reversed. Thus, in particular, after the evaporation step is restarted subsequently, the advantages of evaporation from the actively selected three-dimensional active area can be provided over an extended period of time, thereby providing a selected directional intensity distribution of the flux of the evaporated source material.

[0047] The method according to the invention can be further enhanced by keeping the reaction chamber closed and filled with a reaction atmosphere during the repeated execution of the preparation step and the subsequent evaporation step. As described above, during the implementation of the method according to the invention, the reaction chamber of the TLE system is filled with a reaction atmosphere. Providing the reaction atmosphere can be quite complex in terms of both cost and time and / or the work expended. In particular, the reaction atmosphere is typically provided as a flowing equilibrium, in which the gaseous components of the reaction atmosphere are supplied to the reaction chamber and pumped out of the reaction chamber simultaneously and are adapted to each other. This allows the reaction atmosphere to be provided at a selected pressure. By keeping the reaction chamber closed during the repeated execution of the preparation step and the subsequent evaporation step, gas permeation (aeration) of the reaction chamber by the ambient atmosphere can be avoided. The reaction atmosphere already present in the reaction chamber remains enclosed in the reaction chamber. In other words, it is possible to avoid providing the reaction atmosphere again after each repetition.

[0048] Furthermore, the method according to the invention is characterized in that the source comprises a refeeding device for refeeding additional source material into the pool to at least compensate for the material loss due to the evaporated source material. As described above, the evaporation process causes a material loss of the source assembly and thus a shift in the position of the upper surface relative to the heating laser beam and the substrate. Additionally, or as an alternative to providing an actuator for moving the source assembly, refeeding additional source material into the pool can also be used to at least time-averagely maintain the upper surface at a fixed position within the reaction chamber.

[0049] The refeeding device is used to place additional source material into the pool, where the additional source material is subsequently melted by the heating laser beam and thus replaces the evaporated source material. In this way, the level of the pool can be kept constant, at least time-averagely constant. Moreover, the material loss can also be overcompensated (preferably slightly overcompensated). In summary, a directional intensity distribution of the flux of the evaporated source material can be provided, and thus a stable deposition of the evaporated source material onto the substrate can be provided.

[0050] Additionally, the method according to the invention can be enhanced by periodically refeeding additional source material into the pool by the refeeding device. In other words, after a certain time period, additional source material is fed into the pool to refill the pool. This results in a periodic directional intensity distribution of the flux of the evaporated source material, fluctuating around a time-averaged mean value. Preferably, the time period is appropriately selected such that the time-averaged mean value is the selected directional intensity distribution, for example by slightly overcompensating for the aforementioned material loss. Furthermore, it is also preferably appropriately selected such that the absolute flux value fluctuates little relative to the mean value, the fluctuation of the time period length relative to the total time required for the expected deposition process is also small, or the time period length corresponds to an essentially exact integer fraction of the deposition time.

[0051] Alternatively, the method is further characterized in that the refeeding device continuously refeeds additional source material into the pool. By continuously refeeding additional source material into the pool, a constant position of the upper surface provided by the surface of the pool relative to the heating laser beam and the substrate can be continuously provided. Therefore, a flux of the evaporated source material with a constant selected directional intensity distribution can be provided.

[0052] Additionally, the method according to the invention can include providing the additional source material as a wire, especially where the reaction chamber includes a differential pumping feedthrough for feeding the wire into the refeeding device. Since the wire can provide a long extension, the time period during which evaporation treatment can be provided in the TLE system can be extended by providing the additional source material in the form of a wire. In particular, if the wire is additionally provided from outside the reaction chamber through the differential pumping feedthrough, the time period is substantially unrestricted.

[0053] Moreover, the method according to the present invention can be enhanced by re-feeding additional source material into the pool at the maximum intensity of the heating spot of the heating laser beam and / or at the edge of the pool. The maximum of the evaporation process is located at the maximum intensity of the heating spot of the laser beam away from the edge of the pool. Therefore, the directional intensity distribution of the flux of the evaporated source material is dominated by the source material evaporated from the said region of the active area. By re-feeding additional source material at the said maximum intensity of the heating spot of the heating laser beam and / or at the edge of the pool, the influence of the re-feeding process on the evaporation process can be minimized.

[0054] According to a second aspect of the present invention, this object is achieved by a thermal laser evaporation (TLE) system, which comprises: a reaction chamber that can be filled with a reaction atmosphere; a substrate disposed in the reaction chamber; one or more sources disposed in the reaction chamber, each source comprising a source assembly composed of a source material; and a laser source for providing a heating laser beam that irradiates the upper surface of the source assembly with a heating spot, so as to evaporate or sublime the source material from the active area on the upper surface of the source assembly to provide a flux of the evaporated or sublimed source material for deposition onto the substrate. The TLE system according to the present invention is constructed to perform the method according to any one of the preceding claims. Thus, the thermal laser evaporation system according to the second aspect of the present invention provides all the features and advantages described above with respect to the method according to the first aspect of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] The present invention will be described in detail below by way of examples with reference to the accompanying drawings. The method according to the present invention allows for the stable deposition of the evaporated and / or sublimed source material onto the substrate. This is provided by ensuring that the flux of the evaporated or sublimed source material preferably includes a selected directional intensity distribution over an extended period of time, especially continuously. Below, possible embodiments and enhancements of the said method according to the present invention will be described based on the schematic visualizations in Figures 2 to 7 The TLE system constructed to perform the method according to the present invention is shown in Figure 8 Specifically, the drawings show:

[0056] is a schematic diagram of the directional intensity distribution of the flux of the evaporated source material according to the prior art,

[0057] Figure 1 is a first embodiment of the method according to the present invention,

[0058] Figure 2 is a second embodiment of the method according to the present invention,

[0059] Figure 3 is a third embodiment of the method according to the present invention,

[0060] Figure 4 is a third embodiment of the method according to the present invention,

[0061] Figure 5 is the fourth embodiment of the method according to the present invention,

[0062] Figure 6 is the fifth embodiment of the method according to the present invention,

[0063] Figure 7 is an enhancement of the method according to the present invention, and

[0064] Figure 8 is a schematic view of a thermal laser evaporation system according to the present invention. Detailed Description of the Invention

[0065] Generally speaking, the different embodiments of the method according to the present invention described below are presented at fixed time points. However, in order to provide a stable deposition of the source material 52 for evaporation and / or sublimation, it is advantageous to perform the corresponding measures of the method according to the present invention continuously or at least repeatedly.

[0066] In Figure 2 , the sublimation of the source material 52 from the self-supporting source element 50 serving as the source 40 is shown. In subfigure A, the start of the sublimation process is depicted. The heating laser beam 22 provided by the laser source 20 (see Figure 8 ) irradiates the upper surface 60 of the source element 50. The size of the heating laser beam 22 is selected such that the heating spot 24 of the heating laser beam 22 on the source element 50 surrounds the entire upper surface 60. Therefore, the actual heating position 26 is secondary.

[0067] Subfigure B shows an intermediate state of the sublimation process. Some of the source material 52 has sublimated, forming a dip in the upper surface 60. However, when the heating spot 24 (see subfigure A) surrounds the entire upper surface 60, further sublimation of the source material 52 will deepen and widen the dip respectively until the source material 52 sublimates from the entire upper surface 60.

[0068] This stage is depicted in subfigure C. The entire upper surface 60 is used for the sublimation of the source material 52. In other words, the entire upper surface 60 forms the active area 62. For the depicted embodiment of the method according to the present invention, it is decisive that once this stage is reached, the three-dimensional shape of the upper surface 60 and thus the three-dimensional shape of the active area 62 also persist, because the size of the upper surface 60 is limited by the boundaries of the source element 50. Therefore, a selected direction intensity distribution of the flux 54 of the sublimated source material 52 (see Figure 8 ) can be provided over an extended period of time, which depends on the three-dimensional shape of the active area 62.

[0069] However, after sublimating a sufficiently large amount of the source material 52, the relative position of the upper surface 60 with respect to the heating laser beam 22 begins to change, as depicted in an exaggerated manner in subfigure D. To overcome this problem, the source 40 preferably includes an actuator for correspondingly moving the source assembly 50. Thereby, the above-described change in the relative position of the upper surface 60 with respect to the irradiated heating laser beam 22 due to the material loss caused by sublimating the source material 52 can be offset. Preferably, the movement of the source assembly 52 (depicted as an arrow next to the actuator 46 in subfigure D) is set such that the material loss is precisely compensated. To this end, the movement of the source assembly 50 provided by the actuator 46 can preferably be continuous or at least periodic.

[0070] Starting from Figure 3 beginning, an embodiment of the method according to the present invention is shown, in which the source material 52 is evaporated by the irradiated heating laser beam 22. In Figures 3 to 6 all corresponding embodiments shown, the heating laser beam 22 is used to at least partially melt the source material 52 to form a pool 64 of the molten source material 52, and subsequently evaporate the source material 52 from the pool 64. In other words, the upper surface of the pool 64 forms the active region 62.

[0071] In Figure 3 it shows the influence of the corresponding size of the pool 64 on the curvature of the active region 62. Subfigure A shows the source assembly 50 of the source 40 when starting to illuminate with the heating laser beam 22. The heating laser beam 22 irradiates onto the upper surface 60 of the source assembly 50 at the heating position 26, covering the heating spot 24. The size of the heating spot 24 and / or the power density of the laser beam 22 define the size of the pool 64 of the molten source material 52, whereby the size of the pool 64 can be the same as the size of the heating spot 24. The size of the pool 64 can also be different from the size of the heating spot 24, for example due to the thermal conductivity of the source material 52 and / or the convection in the molten source material 52 of the pool 64. In Figure 3 it, the size of the heating spot 24 is selected such that the resulting size of the pool 64 is smaller than the entire upper surface 60. Thus, the pool 64 is limited by the source material 52 of the source assembly 50.

[0072] This is shown in subfigures B and C. In both subfigures, it is assumed that the same absolute amount of the source material 52 has been evaporated in both cases, and the density of the source material 52 in its solid state is the same as its density in its molten state. It can be clearly seen that in both cases, the curvature is concave, and the curvature of the pool 64 with a smaller size (subfigure B) is higher than the corresponding curvature of the pool 64 with a larger size (subfigure C). Therefore, by actively selecting the size of the heating spot 24 and thereby respectively defining the sizes of the pool 64 and the active region 62, the curvature of the active region 62 can be actively selected.

[0073] Since the directional intensity distribution of the flux 54 of the evaporating source material 52 (see Figure 8 ) strongly depends on the curvature which is the three-dimensional shape of the active region 62, the flux 54 can also have an actively selected directional intensity distribution. To enhance the method according to the invention and offset the material loss caused by the evaporation of the molten source material 52 from the pool 64, additional source material 52 can be re-fed as described in detail below with reference to Figure 7 .

[0074] Similarly Figure 3 , Figure 4 also shows the formation of a pool 64 of the molten source material 52 by the illumination of the heating laser beam 22. Contrary to the embodiment described with reference to Figure 3 , the size of the heating spot 24 is now adjusted such that it at least encloses the entire upper surface 60. Thus, similar to Figure 2 , the actual heating position 26 is secondary.

[0075] Specifically, the enclosure of the entire upper surface 60 by the heating spot 24 results in the formation of a pool 64 of the molten source material 52 that also covers the entire upper surface 64, see subfigures B, C. This can also be achieved by selecting the power density of the laser beam 22 with a smaller heating spot 24 to be high enough, but this is not shown in Figure 4 .

[0076] Again, subfigure A depicts the start of the evaporation process where the heating laser beam 22 irradiates the upper surface 60 of the source assembly 50 of the source, but the pool 64 of the molten source material 52 has not yet been formed.

[0077] Subfigures B, C depict two different possible ways of forming the pool 64. In subfigure B, the intensity of the heating laser beam 22 is adjusted, especially including the spatial intensity distribution of the heating laser beam 22, such that the heating laser beam 22 just melts enough source material 52 to cover the upper surface 60. Thus, the generally flat surface of the pool 64 can provide the active region 62.

[0078] In contrast thereto, in the manner shown in subfigure C, the heating laser beam 22 has a higher intensity. Therefore, more source material 52 melts and a floating droplet is formed as the pool 64 at the upper end of the source assembly 50. As can be clearly seen, the active region 62 provided by the droplet in subfigure C includes a curvature that is completely different from, especially convex, compared to the corresponding active region 62 connected to the flat surface of the pool 64 in subfigure B. Again, the directional intensity distribution of the flux 54 of the evaporating source material 52 (see Figure 8 ) strongly depends on the curvature, and thus an actively selected directional intensity distribution can also be provided for the flux 54.

[0079] In comparison with Figure 2Similar to the embodiment shown, Figure 4 In the embodiment of the present invention, an actuator 46 may also be provided to compensate for material loss due to evaporation of the source material 52. Thus, the relative spatial position of the upper surface 60 and thus the active area 62 with respect to the heating laser beam 22 may be kept constant.

[0080] Figure 5 Another possibility is shown for actively adjusting the curvature of the active area 62. In contrast to all previously discussed embodiments, the source 40 now comprises a crucible 42 for providing the source assembly 50. The heating laser beam 22 is used to completely melt the source assembly 50 into a pool 64 of molten source material 52, while the crucible 42 is used to confine said pool 64.

[0081] The use of a crucible provides a number of ways to actively adjust the curvature of the upper surface 62 provided by the accessible surface of the pool 64. Firstly, the material 44 of the crucible 42 can be selected relative to the source material 52 such that a certain contact angle is established at the edge of the pool 64. By means of said contact angle and the dimensions of the pool 64, the curvature of the upper surface 60 can therefore also be actively selected. By selecting the crucible material 44 accordingly, for certain source materials 52, not only the significance of said curvature can be selected, but even whether the established curvature is convex or concave, see for example sub-figures A, B.

[0082] Furthermore, filling the crucible 42 up to its edge with molten source material 52 can also be used to influence the curvature of the resulting upper surface 60. Due to the spatial limitations of the edge defining the boundary between the crucible 42 and the molten source material 52, even overfilling the crucible 42 with molten source material 52 is possible, thereby extending the achievable curvature values, see sub-figure C.

[0083] Since the source material 52 is preferably completely melted, the heating position 26 of the heating spot 24 is also actively adjusted to define the local curvature of the active area 62 (the corresponding flux 54 of the evaporated source material 52 (see Figure 8 ) originates from the active region 62), as shown in sub-figure B. In said sub-figure B, two different heating positions 26 at regions of different curvatures of the active region 62 are exemplarily shown. Since the energy deposited into the pool 64 of the molten source material 52 by the heating laser beam 22 is highest at the corresponding heating position 26, the evaporation of the source material also reaches a peak at said heating position 26. Thus, a desired directional intensity distribution of the flux 54 of the evaporated source material 52 can be selected.

[0084] In summary, the use of crucible 42 to provide source assembly 50 provides several unique possibilities for actively adjusting the curvature of active region 62, with all of the corresponding advantages that have been described above.

[0085] similar Figure 3, please refer to Figure 7 and the corresponding description below to enhance the method according to the present invention by re-feeding additional source material 52 to offset the material loss caused by the evaporation of the molten source material 52 from the pool 64.

[0086] Figure 6 Another possible way to depict actively adjusting the curvature of the active region 62, where subgraphs A and B show the first variant of the way, and subgraphs C and D show the second variant of the way. Generally, before evaporating the source material 52 from the pool 64 of the molten source material 52 by the heating laser beam 22 in the evaporation step (subgraphs B and D), a preparation step is performed to actively provide a selected curvature of the upper surface 60 of the source assembly 50 (subgraphs A and C).

[0087] For the preparation step, different shaping laser beams 30 can be used. However, preferably, the heating laser beam 22 (not shown in Figure 6 ) can also be used as the shaping laser beam 30 in the preparation step. A portion of the source material 52 (densely hatched) is melted by the shaping laser 30, see subgraphs A and C. As shown, the molten source material 52 can be confined within the still solid source material 52 (broadly hatched). However, a crucible 42 (not shown in Figure 6 ) can also be used. Then, the shaping laser beam 30 is preferably used for the controlled solidification of the previously molten source material 52. Depending on the shape of the shaping laser beam 30 and the shaping spot 32 on which the shaping laser beam 30 impinges on the source assembly 50, different three-dimensional shapes of the upper surface 60 of the source assembly 50 can be provided, such as including a convex bulge (subgraph A) or a concave depression (subgraph C).

[0088] In the evaporation step after the preparation step, the heating position 26 of the heating laser beam 22 and the size of the heating spot 24 are actively selected to select the desired curvature on the upper surface 60 to establish the pool 64, the surface of which defines the active region 62. In the Figure 6 example shown, active selection of evaporation can be provided from a convex active region 62 (subgraph B) or from a concave active region 62 (subgraph D).

[0089] Also in this embodiment, the material loss caused by the evaporation of the source material 52 slowly destroys the selected curvature and thus it is no longer possible to provide the selected directional intensity distribution of the flux of the evaporated source material 52. In addition to enhancing the method according to the present invention by re-feeding additional source material 52 as described below with reference to Figure 7 , the preparation step and the subsequent evaporation step can also be repeated. Preferably, the reaction chamber 12 (see Figure 8)For the repetition, keep it closed to avoid the time, cost, and work consumption process of refilling the reaction chamber 12 with the reaction atmosphere 14.

[0090] As described above, the material loss due to the evaporation of the source material 52 slowly disrupts the relative position of the upper surface 60 of the source assembly 50 relative to the heating laser beam 22 and also relative to the substrate 16 to be coated (see Figure 8 ). Figure 7 Sub - figure A of depicts this stage of the evaporation process. The pool 64 of the molten source material 52 is confined within the still - solid portion of the source assembly 50 of the source, however, the surface of the pool 64 forms a deep depression with a particularly undesirable curvature in the upper surface 60.

[0091] However, as an enhancement of the method according to the invention, an additional source material 52 is provided to be refed into the pool 64. Thus, at least compensation can be provided for the material loss caused by the evaporation of the molten source material 52 from the pool 64. For this purpose, the source 40 includes a refed device 48 for refeding the additional source material 52 into the pool 64, see sub - figure B. As shown, this can be done during an evaporation interruption.

[0092] After refeding the additional source material 52, the heating laser 22 is reopened and all the refed additional source material 52 is also melted, again forming an active region 62 with an actively selected curvature (see sub - figure C). As shown, by carefully selecting the amount of the refed source material 52, this even allows the curvature of the active region 62 to be reversed. This process can be repeated periodically.

[0093] Alternatively, as shown in sub - figure D, the additional source material 52 can also be continuously provided by the refed device 48 (e.g., as a wire 70). Thereby, it is also possible to separately provide continuous refeding of the additional source material 52 and compensation for material loss. Preferably, the wire 70 is fed into the reaction chamber 12 through a differentially pumped feedthrough (see Figure 8 ) and reaches the refed device 48. Thereby, the time period for the evaporation process for the evaporated source material 52 can be provided without interruption and is basically unrestricted.

[0094] In addition, also as shown in sub - figure D, the preferred position for refeding the additional source material 52 is at the edge of the pool 64, thus particularly far from the heating spot 24 at the heating position 26. Thereby, the undesirable influence from the refed process to the evaporation process can be minimized.

[0095] Figure 8Shows a schematic and simplified cross-sectional side view of a thermal laser evaporation (TLE) system 10 according to the present invention. The TLE system 10 is constructed to perform the method according to the present invention. Inside the reaction chamber 12, a source 40 providing a source assembly 50 and a substrate 16 are arranged, and the source assembly 50 includes a source material 52. The reaction chamber 12 is filled with a reaction atmosphere 14, such as a vacuum or a suitable reaction gas.

[0096] A heating laser beam 22 provided by a laser source 20 is coupled into the reaction chamber 10 for irradiating onto the upper surface 60 of the source assembly 50 at a heating position 26 having a heating spot 24. By implementing the method according to the present invention, for example, in one of the embodiments described above with reference to Figures 2 to 7 one of the embodiments described, the flux 54 of the evaporated and / or sublimated source material 52 can have a selected directional intensity distribution. Thereby, the quality of the coating on the substrate 16 can be significantly improved. List of reference numerals 10 TLE system 12 Reaction chamber 14 Reaction atmosphere 16 Substrate 20 Laser source 22 Heating laser beam 24 Heating spot 26 Heating position 30 Shaping laser beam 32 Shaping spot 40 Source 42 Crucible 44 Crucible material 46 Actuator 48 Refeed device 50 Source assembly 52 Source material 54 Flux 60 Upper surface 62 Active area 64 Pool 70 Wire

Claims

1. A method (10) using a Thermal Laser Evaporation (TLE) system (10), the TLE system (10) comprising: A reaction chamber (12) capable of being filled with a reaction atmosphere (14); A substrate (16) disposed in the reaction chamber (12); One or more sources (40) disposed in the reaction chamber (12), each source (40) including a source assembly (50) composed of a source material (52); and a laser source (20) for providing a heating laser beam (22), the heating laser beam (22) irradiating the upper surface (60) of the source assembly (50) with a heating spot (24), so as to evaporate or sublime the source material (52) from an active region (62) on the upper surface (60) of the source assembly (50), to provide a flux (54) of the evaporated or sublimed source material (52) for deposition onto the substrate (16), Wherein the method includes the step of providing a selected directional intensity distribution of the flux (54) of the evaporated or sublimed source material (52) by actively adjusting the three-dimensional shape of the active region (62).

2. The method according to claim 1, wherein the three-dimensional shape of the active region (62) is adjusted by actively selecting and / or changing the following items: - The size of the heating spot (24) relative to the size of the upper surface (60) and / or the size of the active region (62), and / or - The position of the heating spot (24) on the upper surface (60), and / or - The spatial intensity distribution of the heating laser beam (22), and / or - The temporal profile of the intensity of the heating laser beam (22).

3. The method according to claim 1 or 2, wherein The three-dimensional shape of the active region (62) is adjusted repeatedly, specifically continuously.

4. The method according to any one of claims 1 to 3, wherein The selected directional intensity distribution of the flux (54) includes a constant time dependence or at least a periodic time dependence.

5. The method according to any one of claims 1 to 4, wherein, The flux (54) is provided by sublimating from a solid state by the heating laser beam (22), and wherein the size of the heating spot (24) is adjusted to be equal to or larger than the size of the upper surface (60) for providing the entire upper surface (60) as the active region (62) of the sublimed source material (52).

6. The method according to claim 5, wherein, The source (40) includes an actuator (46) for moving the source assembly (50), and thereby, moving the source assembly (50) to keep the spatial position of the active region (62) relative to the heating laser beam (22) and the substrate (16) constant to compensate for the material loss caused by the sublimed source material (52).

7. The method according to any one of claims 1 to 4, wherein, The heating laser beam (22) melts the source material (52) to form a pool (64) of the molten source material (52) as the active region (62), and evaporates the source material (52) from the pool (64), thereby providing the flux (54) of the source material (52), and wherein the size of the heating spot (24) is adjusted to be smaller than the size of the upper surface (60) to form the pool (64), thereby forming the active region (62) having a selected size and a selected curvature.

8. The method according to claim 7, wherein, The size of the heating spot (24) is adjusted by correspondingly adjusting the intensity distribution of the heating laser beam (22), specifically with respect to the overall intensity and / or spatial distribution and / or size and / or position and / or shape of the intensity distribution of the heating laser beam (22).

9. The method according to any one of claims 1 to 4, wherein, The heating laser beam (22) melts the source material (52) to form the active region (62) as a pool (64) of molten source material (52), and evaporates the source material (52) from the pool (64) to provide the flux (54) of the source material (52), and wherein the size of the heating spot (24) is adjusted to be equal to or greater than the size of the upper surface (60) to form a pool (64) of molten source material (52) as the active region (62) over the entire upper surface (60), and wherein the intensity of the heating laser beam (22) is adjusted to form the pool (64) so as to form the active region (62) having a selected curvature.

10. The method according to any one of claims 1 to 4, wherein, The heating laser beam (22) melts the source material (52) to form the active region (62) as a pool (64) of molten source material (52), and evaporates the source material (52) from the pool (64) to provide the flux (54) of the source material (52), and wherein the intensity of the heating laser beam (22) is adjusted to form a pool (64) of molten source material (52) as the active region (62) over the entire upper surface (60), and wherein the intensity of the heating laser beam (22) is further adjusted to form the pool (64) so as to form the active region (62) having a selected curvature.

11. The method according to claim 9 or 10, wherein, The pool (64) includes a flat mean curvature.

12. The method according to any one of claims 9 to 11, wherein The source (40) includes an actuator (46) for moving the source assembly (50), and thereby, the source assembly (50) is moved to keep the spatial position of the active region (62) relative to the heating laser beam (22) and the substrate (16) constant to compensate for the material loss caused by the evaporated source material (52).

13. The method according to any one of claims 1 to 4, wherein, The source (40) includes a crucible (42) and the source assembly (50) is disposed in the crucible (42), and wherein the heating laser beam (22) completely melts the source material (52) in the crucible (42) to form the active region (62) as a pool (64) of molten source material (52) at the entire upper surface (60), and evaporates the source material (52) from the pool (64) to provide the flux (54) of the source material (52), and wherein the crucible material (44) of the crucible (42) is selected relative to the source material (52) to form the pool (64) so as to form the active region (62) having a selected curvature.

14. The method according to claim 13, wherein, The three-dimensional shape of the crucible (42) is correspondingly selected to provide the selected curvature.

15. The method according to claim 13 or 14, wherein The crucible (42) is completely filled or overfilled due to its surface tension with the source material (52).

16. The method according to any one of claims 13 to 15, wherein, The heating spot (24) is respectively smaller than the upper surface (60) and the active region (62), and wherein the heating position (24) of the heating spot (24) at the active region (62) is selected relative to the local curvature of the active region (62) at the heating position (24).

17. The method according to any one of claims 1 to 4, wherein, The step of providing a selected directional intensity distribution of the flux (54) of the evaporation source material (52) includes a preparation step and a subsequent evaporation step, wherein in the preparation step, the three-dimensional shape of the entire upper surface (60) is formed, whereby, relative to the selected directional intensity distribution of the flux (54), the three-dimensional shape of the active region (62) as a part of the upper surface (60) is provided, and in the evaporation step, the heating laser beam (22) evaporates and / or sublimes the source material (52) from the active region (62).

18. The method according to claim 17, wherein, In the preparation step, the shaping laser beam (30) irradiates the upper surface (60) of the source assembly (50) with a shaping spot (32) for adjusting the three-dimensional shape of the upper surface (60), wherein the shaping laser beam (30) is used to melt the source material (52) and / or to provide a controlled solidification of the molten source material (52).

19. The method according to claim 18, wherein, The shape of the shaping spot (32) and / or the position of the shaping spot (32) on the upper surface (60) are correspondingly adjusted to provide a controlled solidification of the molten source material (52).

20. The method according to claim 18 or 19, wherein, The heating laser beam (22) for evaporating and / or subliming the source material (52) from the active region (62) of the source assembly (50) in the evaporation step is used as the shaping laser beam (30) in the preparation step.

21. The method according to any one of claims 18 to 20, wherein The preparation step and the subsequent evaporation step are alternately repeated.

22. The method according to claim 21, wherein, During the repeated execution of the preparation step and the subsequent evaporation step, the reaction chamber (12) remains closed and filled with the reaction atmosphere (14).

23. The method according to any one of claims 7 to 22, wherein, The source (40) includes a refeeding device (48) for refeeding additional source material (52) into the pool (64) to at least compensate for the material loss caused by the evaporated source material (52).

24. The method according to claim 23, wherein, The refeeding device (48) periodically refeeds the additional source material (52) into the pool (64).

25. The method according to claim 23, wherein, The refeeding device (48) continuously refeeds the additional source material (52) into the pool (64).

26. The method according to any one of claims 23 to 25, wherein, The additional source material (52) is provided as a wire (70), specifically, wherein the reaction chamber (12) includes a differential pumping feedthrough for feeding the wire (70) to the refeeding device (48).

27. The method according to any one of claims 23 to 26, wherein At the maximum intensity of the heating spot (24) of the heating laser beam (22) and / or at the edge of the pool (64), the additional source material (52) is re-fed into the pool (64).

28. A thermal laser evaporation (TLE) system (10), the TLE system (10) comprising: A reaction chamber (12) capable of being filled with a reaction atmosphere (14); A substrate (16) disposed in the reaction chamber (12); One or more sources (40) disposed in the reaction chamber (12), each source (40) including a source assembly (50) composed of a source material (52); and a laser source (20) for providing a heating laser beam (22), the heating laser beam (22) irradiating an upper surface (60) of the source assembly (50) with a heating spot (24), thereby evaporating or sublimating the source material (52) from an active region (62) on the upper surface (60) of the source assembly (50) to provide a flux (54) of the evaporated or sublimated source material (52) for deposition onto the substrate (16), wherein the TLE system (10) is configured to perform the method as described in any one of the preceding claims.

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