How to use the TLE system and the TLE system

Abstract

The present invention relates to a method of using a thermal laser deposition (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 having a source element (50) comprising a source material (52); and a laser light source (20) providing laser light (22) that impinges with a heat spot (24) on top surfaces (60) of the source elements (50) to deposit a flux (54) of evaporated or sublimated source material (52) onto the substrate (16), thereby evaporating or sublimating the source material (52) from an active area (62) of the top surface (60) of the source element (50).

Description

[Technical Field]

[0001] The present invention relates to a method of using a thermal laser deposition (TLE) system comprising: a reaction chamber capable of being filled with a reactive atmosphere; a substrate disposed in the reaction chamber; one or more sources disposed in the reaction chamber, each having a source element made of a raw material; and a laser light source providing laser light that impinges on heated spots on upper surfaces of the source elements to deposit a flux of evaporated or sublimated raw material onto the substrate, thereby evaporating or sublimating the raw material from active areas on the upper surfaces of the source elements. Further, the present invention relates to a TLE system comprising: a reaction chamber capable of being filled with a reactive atmosphere; a substrate disposed in the reaction chamber; one or more sources disposed in the reaction chamber, each having a source element made of a raw material; and a laser light source providing laser light that impinges on heated spots on upper surfaces of the source elements to deposit a flux of evaporated or sublimated raw material onto the substrate, thereby evaporating or sublimating the raw material from active areas on the upper surfaces of the source elements. [Background technology]

[0002] In thermal laser deposition (TLE), source materials are evaporated and / or sublimated by laser heating in a controlled environment, typically in a reaction chamber filled with a reactive atmosphere, with the intention of coating a substrate also located in the reaction chamber.

[0003] In most cases, it is desirable to coat the substrate uniformly. This typically requires that at least the directional intensity distribution of the flux of evaporated or sublimated raw material be constant in time. However, such directional intensity distribution is highly dependent on the three-dimensional shape of the top surface of the source element from which evaporated and / or sublimated material originates. Summary of the Invention [Problem to be solved by the invention]

[0004] Unfortunately, the three-dimensional shape of the top surface changes over time as the source element is partially consumed by evaporation and / or sublimation of source material. This is illustrated in FIG. 1. FIG. 1A (left) shows an early-stage evaporation of source material 52 from source element 50, while FIG. 1B (right) shows a later-stage evaporation. In both stages, heating laser light 22 impinges on top surface 60 of source element 50, which consists of source material 52. Source material 52 sublimes from active area 62 to form a flux 54 of sublimated source material 52. It is clear that the directional intensity distribution of flux 54, represented by the arrows, is significantly different from the directional intensity distribution of flux 54 in the early stage (FIG. 1A), when top surface 60 and active area 62 are flat, to that of flux 54 in the later stage (FIG. 1B), when source material 52 is consumed and active area 62 forms a recessed portion of top surface 60. This change in the directional intensity distribution of the flux ultimately alters the deposition of sublimated source material 52 on substrate 16 (see FIG. 8). This can significantly reduce the quality of the deposition and, therefore, the quality of the coated substrate 16 .

[0005] It is an object of the present invention to provide an improved method of using a thermal laser deposition system and an improved thermal laser deposition system that do not have the above-mentioned drawbacks of the prior art. In particular, it is an object of the present invention to provide an improved method of using a thermal laser deposition system and an improved thermal laser deposition system that provide stable deposition of evaporated and / or sublimated raw material onto a substrate, and in particular that can provide a selected directional intensity distribution of the flux of evaporated or sublimated raw material over an extended period of time, preferably continuously. [Means for solving the problem]

[0006] The object of the present invention is achieved by the respective independent patent claims. In particular, the object of the present invention is achieved by a method for using a thermal laser deposition system according to independent claim 1 and by a thermal laser deposition system according to independent claim 28. The dependent claims describe preferred embodiments of the invention. Details and advantages stated with respect to the method according to the first aspect of the invention also refer to the thermal laser deposition system according to the second aspect of the invention, and vice versa, wherever this has technical significance.

[0007] According to a first aspect of the present invention, the above object is achieved by a method of using a thermal laser deposition (TLE) system, comprising: a reaction chamber capable of being filled with a reaction atmosphere; a substrate disposed in the reaction chamber; one or more sources disposed in the reaction chamber, each having a source element made of a raw material; and a laser light source providing laser light that impinges on heated spots on top surfaces of the source elements to deposit a flux of evaporated or sublimated raw material onto the substrate, thereby evaporating or sublimating the raw material from active areas on the top surfaces of the source elements. The method includes the step of actively adjusting a three-dimensional shape of the active area to provide a selected directional intensity distribution of the flux of evaporated or sublimated raw material.

[0008] The method according to a first aspect of the present invention is intended to use a thermal laser deposition system (TLE system for short). In particular, the scope of the present invention is TLE systems that use a laser to evaporate or sublimate raw materials. Such systems are generally known. A heating laser beam from a laser source is used to evaporate or sublimate the raw materials, and the evaporated or sublimated raw materials are often deposited on a target substrate. The raw materials are provided as source elements arranged in a source within the reaction chamber. One or more raw materials, particularly different raw materials, may be provided in the reaction chamber. The heating laser beam impinges on a heating position on the top surface of the source element, and the heating laser beam irradiates a heating spot on the top surface. The actual evaporation or sublimation occurs in an active area on the top surface, which is linked to, and may even be identical to, the heating spot. The flux of evaporated or sublimated raw materials arising from the active area is provided with a directional intensity distribution of the flux that depends on the three-dimensional shape of the active area.

[0009] The source is located in a reaction chamber that can be sealed to prevent ingress of ambient atmosphere and that can be filled with a reaction atmosphere. The reaction atmosphere can be a vacuum or can contain a reaction gas at a pressure suitable for the material to be deposited. The vacuum can be, in particular, 10 -12 The maximum pressure measured so far with a working distance of 60 mm is 10 -2 hPa. 10 -2 Since deposition at 1000 kPa was not problematic, it is speculated that even higher values ​​are possible.

[0010] In most cases, at least the main part of the laser source is located outside the reaction chamber, and the heating laser light is coupled into the reaction chamber via a coupling means, which may be, for example, a simple window in the chamber wall of the reaction chamber. However, the coupling means according to the present invention may also comprise adaptive optics for shaping the heating laser light that impinges on the top surface of the source element.

[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 includes all methods that influence the three-dimensional shape before and during, in particular during, the evaporation or sublimation process. Since the active area is an essential part of the top surface, adjustment of the active area can also be provided by active adjustment of the top surface.

[0012] There are many different types and methods for adjusting the three-dimensional shape, such as by appropriately selecting the size of the source element and the size of the heating laser beam, and / or by compensating for material loss due to ongoing evaporation or sublimation. These three-dimensional shape adjustment methods can be performed alone or in combination. Also, methods and configurations suitable for evaporation processes may differ from methods and configurations suitable for sublimation processes. In general, adjusting the three-dimensional shape can provide a selected three-dimensional shape of the active area. Active adjustment allows the three-dimensional shape to be provided during the evaporation or sublimation process, preferably at any time during the process.

[0013] As mentioned above, the directional intensity distribution of the flux is particularly strongly dependent on the three-dimensional shape of the active area. In short, by actively adjusting the three-dimensional shape of the active area, a selected directional intensity distribution of evaporated or sublimated raw material can be provided during operation of the TLE system, thereby providing stable deposition of evaporated and / or sublimated raw material onto the substrate.

[0014] Furthermore, the method of the present invention can include the following: the three-dimensional shape of the active area is the size of the heating spot relative to the size of the top surface and / or the size of the active area, and / or the location of the heating spot on the upper surface, and / or the spatial intensity distribution of the heating laser beam, and / or the time structure of the intensity of the heating laser light; is adjusted by actively selecting and / or modifying This list is not exhaustive and further suitable methods and configurations for actively adjusting the three-dimensional shape of the active area may be added.

[0015] Furthermore, the method according to the invention can be characterized in that the adjustment of the three-dimensional shape of the active area is carried out repeatedly, in particular continuously. Repeated in the sense of the invention includes repetition rates of less than 100 mHz to more than 10 MHz. In other words, the active adjustment is carried out repeatedly or continuously during the evaporation and / or sublimation process. This ensures that the selected three-dimensional shape of the active area is also provided repeatedly, preferably continuously, during the evaporation or sublimation process. This allows the directional flux of evaporated or sublimated raw material with its selected properties to also be provided repeatedly or continuously.

[0016] Furthermore, the method according to the present invention can include the following: the selected directional intensity distribution of the flux has a constant time dependence or at least a periodic time dependence. In particular, a flux having a periodic time dependence can also be considered constant if it is considered to be averaged over the length of one or more periods. A flux having a time-constant or at least a periodic directional intensity distribution enables highly accurate deposition of material onto the substrate. In particular, the thickness of the deposition of raw material at a specific location on the substrate depends primarily on the constant flux of material impinging on said location and the duration of deposition. The overall time dependence of the raw material flux can be avoided, thereby improving the stable deposition of evaporated and / or sublimated raw material onto the substrate.

[0017] According to a first alternative embodiment of the method according to the invention, the method may include the following: the flux is provided by sublimation from a solid state by the heating laser beam, and the size of the heating spot is adjusted to be equal to or greater than the size of the top surface in order to provide the entire top surface as an active area for sublimating the raw material. The lateral size of the top surface, and therefore the lateral size of the active area, is thereby limited and simultaneously defined by the boundaries of the source element. During the sublimation process, a steady state is established, defined by controllable boundary conditions such as the parameters of the heating laser beam, the size of the top surface, and the self-established temperature profile of the source element. This allows the flux of the sublimation raw material to be provided constantly over time, thereby enabling stable deposition of the sublimation raw material on the substrate.

[0018] The method can also be improved by: the source having an actuator for moving the source element, the source element being moved to keep the spatial position of the active area relative to the heating laser light and the substrate constant and to compensate for material loss due to the sublimation raw material. During the sublimation process, raw material is slowly removed from the active area on the top surface and thus slowly removed from the source element. As a result, the spatial position of the active area relative to the impinging heating laser light and the substrate changes over time. For example, the distance between the active area and the substrate increases. By using the source actuator, the material loss can be compensated for and the relative spatial position of the active area relative to the heating laser light and the substrate can be kept constant over time. In the above example, the source element moves toward the substrate at a pace appropriately selected according to the sublimation rate of the raw material. This avoids changes in the directional intensity distribution of the flux of evaporated raw material due to material loss.

[0019] Alternatively or additionally, the heating laser beam itself can be moved to keep the spatial position of the active area relative to the heating laser beam and the substrate constant and to compensate for material loss due to the sublimated raw material. For example, optical elements such as mirrors and / or lenses can be used to move the position of the heating laser beam. In general, all of the advantages discussed above regarding actuators that move the source element are also obtained by the optical elements that move the heating laser beam.

[0020] According to a second embodiment, the method according to the invention can be characterized in that the heating laser beam melts the raw material to form the active area as a pool of molten raw material and evaporates the raw material from the pool, thereby providing the flux of raw material, and the size of the heating spot is adjusted to be less than the size of the top surface so as to form the pool, i.e., the active area, having a selected size and a selected curvature. The curvature of such a pool of molten raw material, which is contained in the remaining raw material still in a solid state of the source element, is given, for example, by the surface tension of the molten raw material, its density and the gravity acting thereon, and temperature gradients caused by the heating laser beam that may drive convection currents that develop in the material and affect the shape of the surface.

[0021] The curvature of the pool, i.e., the curvature of the surface of the active area, depends reproducibly on the diameter and shape of the boundary between the liquid and solid surfaces and the contact angle at this boundary. In most cases, the size of the molten raw material pool is fixed for a given source material and the intensity of the heating laser light to achieve a given deposition rate. Therefore, the curvature of the active area, i.e., the curvature of the pool surface and the directional density distribution of the evaporated raw material flux can be easily controlled. In short, this embodiment of the method according to the present invention also allows for a selected directional intensity distribution of the evaporated raw material flux, thereby providing stable deposition of the evaporated raw material on the substrate.

[0022] Furthermore, the method according to the present invention can be further improved by adjusting the size of the heating spot by appropriately adjusting the intensity distribution of the heating laser beam, in particular 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 exhaustive, and further suitable methods and configurations for actively adjusting the intensity distribution of the heating laser beam can be added. In other words, the size of the heating spot can be actively selected by providing a heating laser beam having an appropriately adjusted intensity distribution.

[0023] According to a first implementation of the third embodiment of the method according to the invention, the heating laser light melts the raw material to form the active area as a pool of molten raw material and evaporates the raw material from the pool, thereby providing the flux of raw material, and to form a pool of molten raw material as an active area over the entire top surface, the size of the heating spot is adjusted to be equal to or greater than the size of the top surface, and the intensity of the heating laser light is adjusted to form the pool, i.e., the active area, with a selected curvature. In contrast to the above embodiment, the size of the heating spot is selected so that the entire top surface of the source element is not only irradiated but also melted by the heating laser light.

[0024] According to a second implementation of the third embodiment of the method of the present invention, the heating laser beam melts the raw material to form the active area as a pool of molten raw material and evaporates the raw material from the pool, thereby providing the flux of raw material; the intensity of the heating laser beam is adjusted to form a pool of molten raw material as the active area across the entire top surface; and the intensity of the heating laser beam is further adjusted to form the pool, i.e., the active area, having a selected curvature. Similar to the first implementation of the third embodiment, according to the second implementation of the third embodiment of the method of the present invention, a pool of molten raw material is formed as the active area across the entire top surface. In contrast to the first implementation, melting of the entire top surface is provided by increasing the intensity of the laser beam sufficiently to ensure that sufficient laser energy is absorbed by the source element for melting the entire top surface.

[0025] In other words, in both implementations of the third embodiment of the method according to the present invention, the pool of molten raw material spreads over the entire top surface, and the active area is flush with the top surface. When the pool of molten raw material reaches the upper edge of the source element, i.e., the outer upper edge of the surface, the surface of the pool becomes convex and, in extreme cases, forms a floating drop with a contact angle exceeding 90 degrees. However, the size of the drop can be easily controlled by appropriately selecting the intensity of the heating laser beam. Thus, different curvatures of the active area can be easily selected and adjusted by appropriately setting the intensity of the heating laser beam. In other words, since the directional intensity distribution of the flux of evaporated raw material strongly depends on the curvature of the emission surface, it is possible to select a method for providing this directional intensity distribution, thereby providing stable deposition of evaporated raw material on the substrate.

[0026] The method according to the invention can be further improved by configuring the pool so that it has a flat average curvature. This condition is preferably achieved by providing a source element with a flat upper end and setting the intensity of the heating laser light so that only a thin film of molten raw material is present at the flat upper end of the source element, covering the upper surface and simultaneously forming the active area. The surface shape of the active area thus largely follows the flat shape of the upper end of the source element, with high curvature values ​​occurring only at the upper edge. Generally, providing a pool of molten raw material with a flat surface with a flat average curvature also results in a region of constant flux in the directional intensity distribution of the evaporated raw material flux. This allows for stable and particularly uniform deposition of the evaporated raw material onto the substrate.

[0027] The method according to the present invention can also be improved by: the source has an actuator for moving the source element, and the source element is moved to keep the spatial position of the active area relative to the heating laser light and the substrate constant and to compensate for material loss due to the evaporated raw material. Furthermore, during the evaporation process, raw material is removed from the active area on the top surface, i.e., from the source element. Similar to the description of the sublimation process above, the spatial position of the active area relative to the impinging heating laser light and the substrate changes over time. By using the source actuator, the material loss is compensated for and the relative spatial position of the active area relative to the heating laser light and the substrate can be kept constant over time. This avoids changes in the directional intensity distribution of the flux of evaporated raw material due to material loss.

[0028] According to a fourth embodiment of the method according to the invention, the method can be characterized in that the source has a crucible, the source element is provided in the crucible, the heating laser light melts the raw material to form the active area as a pool of molten raw material over the entire top surface, and evaporates raw material from the pool, thereby providing the flux of raw material, and a crucible material of the crucible is selected for the raw material to form the pool, i.e. the active area, with a selected curvature.

[0029] The molten raw material in the crucible forms a contact angle with the crucible material. The contact angle in the sense of the present invention is also known as the wetting angle and is measured at the contact line in the raw material in a plane locally perpendicular to the contact line. In particular, for small contact angles, the molten raw material, i.e., the active area, is usually concave, while for large contact angles, the active area is convex. In other words, the contact angle has a significant effect on the curvature of the active area.

[0030] The contact angle is highly dependent on both the raw material and the crucible material. Metal raw materials in oxide crucibles (e.g., gallium in a sapphire crucible) typically have a large contact angle. Metal or semiconductor raw materials in crucibles made of metal crucible materials typically have a small contact angle. Therefore, for raw materials with several different suitable crucible materials, this mechanism can be used to control the contact angle and adjust the curvature. In short, by selecting the appropriate crucible material, the curvature of the active area and the directional intensity distribution of the evaporated raw material flux can be actively selected.

[0031] The method according to the present invention can further include the following: the three-dimensional shape of the crucible is appropriately selected to provide the selected curvature. As described above, the contact angle is measured at the contact line within the raw material. The contact line is defined as the line at which the molten raw material leaves the crucible. In other words, one leg of the contact angle extends along the exposed surface of the molten raw material, and the other leg extends along the crucible wall surrounding the molten raw material. This allows the contact angle to be directly influenced by appropriately selecting the three-dimensional shape of the crucible. This allows the curvature of the active area, and thus the directional intensity distribution of the flux of evaporated raw material, to be actively selected.

[0032] The method according to the invention can be further improved by providing that the crucible is either completely filled with the raw material or overfilled by surface tension. In other words, the contact line, which defines the contact angle and curvature, coincides with the upper edge of the crucible and is thus geometrically fixed to the upper edge of the crucible. Furthermore, various raw materials have a large surface tension in their respective molten states, which allows the crucible to be overfilled. Since the contact line is geometrically fixed to the upper edge of the crucible, the overall convex curvature of the active area can be varied, in particular allowing the amount of overfilling of the crucible to be selected.

[0033] Alternatively or additionally, the method according to the invention may be improved by the fact that the heating spot is smaller than both the top surface and the active area, and the heating position of the heating spot on the active area is selected relative to the local curvature of the active area at the heating position.

[0034] When a large diameter crucible contains a large amount of raw material, gravity usually overcomes surface tension, producing a melt with a nearly flat, horizontal top surface in the center. This is usually the preferred location for the heating spot, since the laser light can form the active area at this highly symmetrical point. This provides a directional intensity distribution of the evaporated raw material flux with high spatial uniformity.

[0035] Nevertheless, by using a heating laser beam geometry that is asymmetric with respect to the center of the crucible, the hottest point, and thus the active area, can be shifted to another area of ​​the top surface, which allows another way of controlling the directional intensity distribution of the flux via the curvature of the top surface, since the curvature of the top surface is position dependent and the position of the active area within the top surface can be actively selected by appropriately positioning the heating spot.

[0036] According to a fifth embodiment, the method of the present invention can include the following: the step of providing a selected directional intensity distribution of a flux of the evaporation raw material comprises a preparation step followed by an evaporation step, in which a three-dimensional shape of the top surface is formed, in which a three-dimensional shape of the active area, which is a part of the top surface, is provided for the selected directional intensity distribution of the flux, and in which the heating laser light evaporates and / or sublimes the raw material from the active area.

[0037] As noted above, the three-dimensional shape of the active area has a strong influence on the directional intensity distribution of the flux of evaporated raw material emerging from the active area. Thus, by actively shaping the three-dimensional shape of the top surface, and thus automatically shaping the three-dimensional shape of the active area as an intrinsic part of the top surface, it is possible to provide a flux of evaporated and / or sublimated raw material with a selected directional intensity distribution.

[0038] In the preparation step, the top surface is formed. The forming process can include processes capable of changing the three-dimensional shape, such as machining, ablation, sintering, melting, and subsequent controlled solidification. In particular, the most suitable forming process for each source can be selected, taking into account, for example, the raw material and / or size of the entire source element, the top surface, and / or the active area.

[0039] In a subsequent evaporation step, the laser light impinges on the top surface of the source element so that the source material is evaporated and / or sublimated in the intended active area. Since the active area prepared in the preparation step has a specific three-dimensional shape adapted to a purposefully selected directional intensity distribution of the flux of evaporated and / or sublimated source material, the flux automatically has said directional intensity distribution. Furthermore, this embodiment of the method according to the present invention can provide a stable deposition of evaporated and / or sublimated source material onto a substrate.

[0040] The method according to the invention can also be improved by the following: in the preparation step, a shaped laser beam impinging on a shaped spot on the top surface of the source element is used to adjust the three-dimensional shape of the top surface, and the shaped laser beam is used to melt the raw material and / or provide controlled solidification of the molten raw material. During the melting by the shaped laser, a source element, in particular one arranged in a crucible, can be melted completely or only partially. In the case of a source without a crucible, i.e. a freestanding source element, only the raw material on the top surface or only a part of the top surface, such as the active area and / or its surroundings, can be melted up to a specific depth of the source element. The shaped spot of the shaped laser beam can cover the entire top surface or only a part of the top surface, in particular the active area.

[0041] Controlled solidification in the sense of the present invention includes all configurations that allow the three-dimensional shape of the upper surface to be influenced during solidification. By using the shaped laser light during solidification, the time sequence of solidification can be influenced. In other words, some spots on the upper surface solidify quickly and others slowly, and the shaped laser light impinges on the latter spots in order to prevent premature solidification in particular. In addition, the difference in density between the molten and solid states of the raw material can be used to influence the resulting three-dimensional shape of the upper surface as desired. In short, the use of a shaped laser in the preparation step allows for a wide variety of possible three-dimensional shapes of the upper surface.

[0042] According to a further refinement of the method according to the invention, the shape of the shaping spot and / or its position on the upper surface can be appropriately adjusted to provide a controlled solidification of the molten raw material. Shapes within the meaning of the invention include, for example, circular or elliptical shapes of the shaping spot, as well as shaping spots fragmented into two or more individual sub-spots and / or shaping spots with local intensity minima within the shaping spot, for example, annular. Furthermore, a movement of the shaping spot of the shaping laser light, which effectively forms a time-averaged area in which the shaping laser acts on the raw material, is also a shaping spot within the meaning of the invention. Therefore, during the controlled solidification, the time sequence of the solidification can be easily influenced, in combination with utilizing the difference in density between the molten and solid states of the raw material.

[0043] For example, if the raw material in its solid state is denser than its molten state, impinging a shaping laser on a single shaping spot during the initial stages of the solidification process will effectively form a mound-like or peak-like three-dimensional shape with a locally convex curvature on the top surface. Conversely, impinging a shaping laser on an annular shaping spot during the initial stages of the solidification process will effectively form a circular mound with a locally concave curvature on the top surface, i.e., a central depression in the three-dimensional shape.

[0044] Furthermore, the method according to the present invention is characterized in that the heating laser light that evaporates and / or sublimes the raw material from the active region of the source element in the evaporation step is used as shaped laser light in the preparation step. In other words, the laser light source provides laser light that can be used both as heating laser light and shaped laser light. Parameters of each laser light, such as overall intensity, light direction, intensity distribution, time structure, and / or repetition rate, may be the same or different when used as heating laser light and shaped laser light. In short, using the same laser light as both heating laser light and shaped laser light can simplify the overall configuration of a TLE system configured to perform the method according to the present invention.

[0045] The method according to the present invention can also include the following: the preparation step and the subsequent evaporation step are alternately and repeatedly performed. As mentioned above, the evaporation process causes material loss, and the actual three-dimensional shape of the active area changes over time. By stopping the evaporation step and re-performing the preparation step, the three-dimensional shape of the active area can be controlled and reversed. Therefore, by taking advantage of the evaporation resulting from an actively selected three-dimensional shape, and especially the subsequent evaporation after resuming the evaporation step, a selected directional intensity distribution of the flux of evaporated raw material can be provided over a long period of time.

[0046] The method of the present invention can be further improved by: The reaction chamber remains closed and filled with the reaction atmosphere while the preparation step and the subsequent evaporation step are repeatedly performed. As described above, the reaction chamber of a TLE system is filled with the reaction atmosphere during the method of the present invention. The cost, time, and / or effort required to provide the reaction atmosphere can be quite complex. In particular, the reaction atmosphere is often provided as a flow balance in which the gaseous components of the reaction atmosphere are simultaneously supplied into the reaction chamber and evacuated from the reaction chamber, thereby providing the reaction atmosphere at a selected pressure. By keeping the reaction chamber closed during the preparation step and the subsequent evaporation step, aeration of the reaction chamber by the ambient atmosphere can be avoided. The reaction atmosphere already present in the reaction chamber remains intact. In other words, it is not necessary to provide the reaction atmosphere for each iteration.

[0047] Furthermore, the method according to the invention can be characterized in that the source comprises a resupply means for resupplying additional raw material into the pool to compensate for at least the material loss caused by the evaporated raw material. As mentioned above, the evaporation process causes a material loss of the raw material, which in turn causes a shift in the position of the top surface relative to the heating laser beam and the substrate. In addition to or as an alternative to providing an actuator for moving the source element, the resupply of additional raw material into the pool can be used to maintain at least the top surface at a time-averaged fixed position within the reaction chamber.

[0048] Using a resupply means, additional raw material is fed into the pool, where it is melted by the heating laser beam and replaces the evaporated raw material. This keeps the pool level constant, at least on average over time. It also makes it possible to compensate for material loss, preferably slightly more. In short, it provides a directional intensity distribution of the flux of evaporated raw material, allowing the evaporated raw material to be stably deposited on the substrate.

[0049] The method according to the invention can also be improved by the following: the resupply means periodically resupply the additional raw material into the pool. In other words, after a certain period of time, additional raw material is supplied into the pool to replenish it. This provides a periodic directional intensity distribution of the flux of evaporated raw material, which fluctuates around a time-averaged mean value. Preferably, the period is selected so that the mean value of the time average is the selected directional intensity distribution, for example by slightly overcompensating for the material losses. Furthermore, the period is preferably selected so that the fluctuations are small both in absolute value of the flux relative to the mean value and in length relative to the time required for the intended deposition process or corresponding to an integer fraction of a substantially exact deposition time.

[0050] Alternatively, the method can be characterized in that the resupply means continuously resupplies the additional raw material into the pool. By continuously resupplying the additional raw material into the pool, a constant position of the upper surface provided by the surface of the pool relative to the heating laser light and the substrate can be continuously provided. Thus, a flux of evaporated raw material having a constant selected directional intensity distribution can be provided.

[0051] The method according to the present invention may also include the following: the additional raw material is provided as a wire, and the reaction chamber has a differentially pumped feedthrough that supplies the wire to the resupply means. Since wires can be extended to a very long length, providing the additional raw material in the form of a wire can lengthen the duration during which the evaporation process is provided in the TLE system. In particular, if the wire is additionally provided from outside the reaction chamber via a differentially pumped feedthrough, the duration is essentially unlimited.

[0052] The method according to the present invention can also be improved by: resupplying the additional raw material at a position in the pool away from the maximum intensity of the heating spot of the heating laser light and / or at the upper edge of the pool. The evaporation process maximum is located at the maximum intensity of the heating spot of the laser light, away from the upper edge of the pool. Therefore, the directional intensity distribution of the flux of evaporated raw material is dominated by the raw material evaporated from this region of the active area. By resupplying the additional raw material at a position away from the maximum intensity of the heating spot of the heating laser light and / or at the upper edge of the pool, the influence of the resupply process on the evaporation process can be minimized.

[0053] According to a second aspect of the present invention, the above object is achieved by a thermal laser deposition (TLE) system comprising a reaction chamber capable of being filled with a reaction atmosphere, a substrate disposed in the reaction chamber, one or more sources disposed in the reaction chamber, each having a source element consisting of a raw material, and a laser light source providing laser light that impinges on upper surfaces of the source elements with a heated spot to deposit a flux of evaporated or sublimated raw material onto the substrate, thereby evaporating or sublimating the raw material from active areas on the upper surfaces of the source elements. The TLE system according to the second aspect of the present invention is configured to perform a method according to any of the preceding claims. The thermal laser deposition system according to the second aspect of the present invention thereby provides all the features and advantages described with respect to the method according to the first aspect of the present invention.

[0054] The present invention will now be described in more detail by way of embodiments and with reference to the drawings. The method according to the present invention allows for a stable deposition of evaporated and / or sublimated raw material on a substrate. This is provided by ensuring that the flux of evaporated or sublimated raw material has a selected directional intensity distribution, preferably over a long period of time, in particular continuously. Possible embodiments and improvements of the method according to the present invention will now be described with reference to the schematic diagrams of Figures 2 to 7. Figure 8 shows a TLE system configured to carry out the method according to the present invention. [Brief explanation of the drawings]

[0055] In particular, the drawings show: [Figure 1] FIG. 1 is a schematic diagram of the directional intensity distribution of the flux of the evaporated raw material according to the prior art. [Figure 2] 1 shows a first embodiment of the method according to the invention; [Figure 3] FIG. 2 illustrates a second embodiment of the method according to the invention. [Figure 4] FIG. 3 illustrates a third embodiment of the method according to the invention. [Figure 5] FIG. 4 shows a fourth embodiment of the method according to the invention. [Figure 6] FIG. 5 shows a fifth embodiment of the method according to the invention. [Figure 7] 1 shows an improved version of the method according to the invention; [Figure 8] 1 is a schematic diagram of a thermal laser deposition system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0056] Generally, the different embodiments of the method according to the present invention described below are presented at fixed points in time, however, it may be beneficial to perform each of the described aspects of the method according to the present invention sequentially or at least repeatedly to provide a stable deposition of evaporated and / or sublimated source material 52.

[0057] Figure 2 shows the sublimation of raw material 52 from a free-standing source element 50 used as source 40. Figure 2A shows the beginning of the sublimation process. A heating laser beam 22 provided by a laser source 20 (see Figure 8) impinges on a top surface 60 of source element 50. The size of heating laser beam 22 is selected so that a heating spot 24 of heating laser beam 22 on source element 50 encompasses the entire top surface 60. Thus, the actual heating location 26 is of secondary relevance.

[0058] 2B shows an intermediate stage of the sublimation process: some of the source material 52 has already sublimated, creating a depression on the top surface 60. However, because the heated spot 24 (see FIG. 2A) encompasses the entire top surface 60, as more source material 52 is sublimated, the depression becomes deeper and wider, until eventually source material 52 has sublimed from the entire top surface 60.

[0059] This aspect is illustrated in Figure 2C. The entire upper surface 60 is used for the sublimation of source material 52. In other words, the entire upper surface 60 forms the active area 62. What is crucial for the illustrated embodiment of the method according to the invention is that, once this stage is reached, the three-dimensional shape of this upper surface 60, and therefore of the active area 62, persists, since the size of the upper surface 60 is limited by the boundaries of the source element 50. Thus, a selected directional intensity distribution of the flux 54 (see Figure 8) of sublimated source material 52, which depends on the three-dimensional shape of the active area 62, is provided over a long period of time.

[0060] However, when a sufficiently large amount of raw material 52 is sublimated, the relative position of upper surface 60 with respect to heating laser beam 22 changes, as shown in an exaggerated manner in FIG. 2D . In response, source 40 preferably includes an actuator that appropriately moves source element 50 accordingly. This allows for the change in the relative position of upper surface 60 with respect to impinging heating laser beam 22, which is caused by material loss due to sublimating raw material 52. The movement of source element 52, indicated by the arrow next to actuator 46 in FIG. 2D , is preferably provided so that this material loss is fully compensated for. To this end, the movement of source element 50 provided by actuator 46 is preferably continuous, or at least intermittent.

[0061] 3 onward, source material 52 is vaporized by the impinging heating laser light 22. In each of the embodiments shown in Figures 3-6, heating laser light 22 at least partially melts source material 52 to form a pool 64 of molten source material 52, and then vaporizes source material 52 from pool 64. In other words, the top surface of pool 64 forms active area 62.

[0062] FIG. 3 illustrates the effect of pool 64 size on the curvature of the active area 62. FIG. 3A shows the source element 50 of the source 40 at the start of irradiation with the heating laser beam 22. The heating laser beam 22 impinges on the top surface 60 of the source element 50 at a heating location 26 that covers the heating spot 24. The size of the heating spot 24 and / or the power density of the heating laser beam 22 define the size of the pool 64 of molten raw material 52, and the pool 64 may be the same size as the heating spot 24. The size of the pool 64 may also differ from the size of the heating spot 24 due to factors such as the thermal conductivity of the raw material 52 and / or convection of the already-molten raw material 52 in the pool 64. In FIG. 3, the size of the heating spot 24 is selected so that the resulting size of the pool 64 is smaller than the entire top surface 60. This confines the pool 64 to the raw material 52 of the source element 50.

[0063] This is shown in Figures 3B and 3C. The following assumptions are made in these figures: the exact same amount of raw material 52 has already been evaporated in both figures, and the density of raw material 52 in its solid state is the same as its molten state. In both figures, it can be seen that the curvature is concave, with the smaller pools 64 (Figure 3B) having a higher curvature than the larger pools 64 (Figure 3C). Therefore, by actively selecting the size of the heated spots 24, and thus defining the size of the pools 64 and active areas 62, one can actively select the curvature of the active areas 62.

[0064] Since the directional intensity distribution of the flux 54 (see FIG. 8) of evaporated raw material 52 strongly depends on the curvature of the three-dimensional shape of the active area 62, it is possible to provide an actively selected directional intensity distribution for the flux 54. In a refinement of the method according to the invention to counteract the loss of material due to evaporation from the pool 64 of molten raw material 52, additional raw material 52 is resupplied, as will be described in more detail below with reference to FIG.

[0065] 4, like Figure 3, also shows the formation of a pool 64 of molten raw material 52 by application of heating laser light 22. In contrast to the embodiment shown in Figure 3, the size of the heating spot 24 is adjusted to include at least the entire upper surface 60. Thus, like Figure 2, the actual heating location 26 is of secondary relevance.

[0066] In particular, the heating spot 24 includes the entire upper surface 60, so that a pool 64 of molten raw material 52 is formed to cover the entire upper surface 60. See Figures 4B and 4C. This can also be achieved by selecting a sufficiently high power density of the heating laser light 22 that corresponds to the small heating spot 24, but this is not shown in Figure 4.

[0067] Again, FIG. 4A shows the beginning of the evaporation process, with the heating laser light 22 impinging on the top surface 60 of the source element 50 of the source, but the pool 64 of molten raw material 52 not yet formed.

[0068] 4B and 4C show two different methods for forming the pool 64. In Fig. 4B, the intensity of the heating laser beam 22, particularly the intensity including the spatial intensity distribution of the heating laser beam 22, is adjusted so that the heating laser beam 22 melts enough of the raw material 52 to cover the upper surface 60. This allows a generally flat surface of the pool 64 to be provided as the active area 62.

[0069] In contrast, in the method shown in FIG. 4C, the heating laser beam 22 has a higher intensity. Consequently, more raw material 52 melts and forms a floating drop 64 on the upper end of the source element 50. Clearly, the active area 62 provided by the drop in FIG. 4C has a distinctly convex curvature, quite different from the individual active areas 62 linked to the flat surface of the pool 64 shown in FIG. 4B. Here too, the directional intensity distribution of the flux 54 (see FIG. 8) of evaporated raw material 52 strongly depends on this curvature, making it possible to provide the flux 54 with an actively selected directional intensity distribution.

[0070] 2, the embodiment shown in Fig. 4 also includes an actuator 46 to compensate for material loss due to evaporation of the source material 52. This allows the relative spatial position of the top surface 60, and therefore the active area 62, to remain constant relative to the heating laser beam 22.

[0071] Another possible way to actively adjust the curvature of the active area 62 is shown in Figure 5. In contrast to all previously described embodiments, the source 40 has a crucible 42 for providing the source element 50. The heating laser light 22 is used to completely melt the source element 50 into a pool 64 of molten raw material 52, and the crucible 42 is used to confine said pool 64.

[0072] The use of a crucible offers several ways to actively adjust the curvature of the top surface 62, which is also the accessible surface of the pool 64. In one method, the material 44 of the crucible 42 is selected to correspond to the source material 52 so that a predetermined contact angle is established at the edge of the pool 64. Depending on the contact angle and the size of the pool 64, the curvature of the top surface 60 can also be actively selected. By appropriately selecting the crucible material 44 accordingly, for some source material 52, it is possible not only to establish the curvature, but even to determine whether the established curvature is concave or convex. See, for example, Figures 5A and 5B.

[0073] Additionally, filling the crucible 42 up to its upper edge with molten raw material 52 also influences the resulting curvature of the upper surface 60. The upper edge defines a spatial limit at the interface between the crucible 42 and the molten raw material 52, and it is possible to overfill the crucible 42 with molten raw material 52, thereby expanding the accessible curvature. See Figure 5C.

[0074] Since it is preferable for the source material 52 to be completely melted, the heating location 26 of the heating spot 24 may be actively adjusted to define the local curvature of the active area 62 from which each flux 54 of evaporated source material 52 (see FIG. 8) is generated, as shown in FIG. 5B. In FIG. 5B, two different heating locations 26 are shown in regions of the active area 62 with different curvatures. The energy deposition into the pool 64 of molten source material 52 by the heating laser beam 22 is highest at each heating location 26, and the evaporation of the source material also peaks at said heating location 26. This allows for the selection of a desired directional intensity distribution of the flux 54 of evaporated source material 52.

[0075] In summary, using crucible 42 to provide source element 50 allows for several unique configurations for actively adjusting the curvature of active region 62 with the advantages discussed above.

[0076] See FIG. 7 as well as FIG. 3 and the following description for an improvement of the method of the present invention by resupplying additional raw material 52 to counteract material loss due to evaporation of molten raw material 52 from pool 64.

[0077] 6 shows other possible ways to actively adjust the curvature of the active area 62, with FIGS. 6A and 6B showing a first variant of the method and FIGS. 6C and 6D showing a second variant. In general, before the evaporation step (FIGS. 6B, 6D) in which the source material 52 is evaporated from a pool 64 of molten source material 52 by the heating laser light 22, a preparatory step is performed (FIGS. 6A, 6C) to actively provide a selected curvature of the top surface 60 of the source element 50.

[0078] A separate shaped laser beam 30 can be used in the preparation step. However, preferably, a heating laser beam 22 is used in the preparation step instead of the shaped laser beam 30 (not shown in FIG. 6 ). A portion of the raw material 52 (closely shaded area) is melted by the shaped laser beam 30. See FIGS. 6A and 6C. As shown, the molten raw material 52 is confined within the still-solid raw material 52 (widely shaded area). However, a crucible 42 (not shown in FIG. 6 ) can also be used. The shaped laser beam 30 is then preferably used for controlled solidification of the previously melted raw material 52. Depending on the shape of the shaped laser beam 30 and the shaping spot 32 of the source element 50 on which the shaped laser beam 30 impinges, different three-dimensional shapes are provided on the upper surface 60 of the source element 50, including, for example, a convex hump ( FIG. 6A ) or a concave depression ( FIG. 6C ).

[0079] In the evaporation step that follows the preparation step, the heating location 26 and the size of the heating spot 24 of the heating laser light 22 are actively selected to select the desired curvature on the top surface 60 and establish pools 64 on the surface that define active areas 62. In the example shown in Figure 6, evaporation from a convex active area 62 (Figure 6B) or a concave active area 62 (Figure 6D) is actively selected.

[0080] Also, in this embodiment, the selected curvature is slowly destroyed by material loss due to evaporation of the raw material 52, so that the selected directional intensity distribution of the flux of evaporated raw material 52 can no longer be provided. In a refinement of the method according to the invention, which will be described below with reference to Figure 7, the preparation step and the subsequent evaporation step can be repeated, in addition to resupplying additional raw material 52. To avoid the time-consuming, expensive and laborious process of filling the reaction chamber 12 (see Figure 8) with the reaction atmosphere 14, the reaction chamber 12 is preferably kept closed while the steps are repeated.

[0081] As noted above, material loss due to evaporation of source material 52 slowly destroys the actively adjusted relative position of top surface 60 of source element 50 with respect to heating laser beam 22 and substrate 16 to be coated (see FIG. 8). This stage of the evaporation process is shown in FIG. 7A. Pool 64 of molten source material 52 is confined to the still-solid portion of source element 50. However, the surface of pool 64 has formed a deep depression in top surface 60, which is particularly undesirable due to curvature.

[0082] However, an improvement of the method according to the invention provides for the re-feeding of additional raw material 52 into pool 64, thereby at least compensating for the loss of material from pool 64 due to evaporation of molten raw material 52. For this purpose, source 40 comprises re-feeding means 48 for re-feeding additional raw material 52 into pool 64, see Figure 7B. As the figure shows, this can be done during an interruption in evaporation.

[0083] After the additional raw material 52 is resupplied, the heating laser light 22 is turned on again to melt all of the additional raw material 52, thereby re-forming the active area 62 with the actively selected curvature (see FIG. 7C). As shown, by carefully selecting the amount of resupplied raw material 52, the curvature of the active area 62 can also be reversed. This procedure can be repeated periodically.

[0084] Alternatively, as shown in Figure 7D, the additional raw material 52 is continuously provided by the resupply means 48, for example as a wire 70. This provides for a continuous resupply of the additional raw material 52 and for compensation for material loss. Preferably, the wire 70 is fed into the reaction chamber 12 (see Figure 8) and to the resupply means 48 via a differentially pumped feedthrough. This essentially eliminates the constraints imposed by the evaporation raw material 52 on the duration over which the evaporation process can be performed uninterrupted.

[0085] 7D, the location where the additional raw material 52 is resupplied is preferably at the upper edge of the pool 64, i.e., away from the heated spot 24 of the heating position 26. This minimizes any undesirable effects of the resupply process on the evaporation process.

[0086] 8 is a simplified schematic longitudinal side view of a thermal laser deposition (TLE) system 10 according to the present invention. The TLE system 10 is configured to perform the method according to the present invention. A source 40 providing a source element 50 having a source material 52 and a substrate 16 are disposed within a reaction chamber 12. The reaction chamber 12 is filled with a reaction atmosphere 14, such as a vacuum or a suitable reaction gas.

[0087] Heating laser light 22 provided by laser light source 20 is coupled into reaction chamber 10 to impinge on top surface 60 of source element 50 at heating location 26 having heating spot 24. By practicing the method according to the present invention, for example, in one of the embodiments described with reference to Figures 2-7, a flux 54 of evaporated and / or sublimated raw material 52 can be provided with a selected directional intensity distribution in a controlled and arbitrary manner, thereby dramatically improving the quality of the coating on substrate 16. [Explanation of symbols]

[0088] 10 TLE systems 12 Reaction Chamber 14 Reaction atmosphere 16 boards 20 Laser light source 22 Heating laser light 24 Heat Spot 26 heating position 30 Shaped laser light 32 Molding Spot 40 sauces 42 Crucible 44 Crucible material 46 Actuator 48 Resupply means 50 source elements 52 Raw Materials 54 Flux 60 Top 62 Active Area 64 Pool 70 wire

Claims

1. A method of using a thermal laser deposition (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 having a source element (50) comprising a source material (52); and a laser light source (20) providing laser light (22) that impinges with a heat spot (24) on an upper surface (60) of the source element (50) to deposit a flux (54) of evaporated or sublimated source material (52) onto the substrate (16), thereby evaporating or sublimating the source material (52) from an active area (62) of the upper surface (60) of the source element (50); The method includes actively adjusting a three-dimensional shape of an active area (62) to provide a selected directional intensity distribution of the flux (54) of evaporated or sublimated source material (52).

2. The three-dimensional shape of the active area (62) is the size of the heating spot (24) relative to the size of the top surface (60) and / or the size of the active area (62), and / or the position of said heating spots (24) on said upper surface (60), and / or the spatial intensity distribution of the heating laser light (22), and / or the time structure of the intensity of the heating laser light (22), The method of claim 1 , wherein the temperature is adjusted by actively selecting and / or modifying

3. 3. The method according to claim 1 or 2, wherein the adjustment of the three-dimensional shape of the active area (62) is carried out repeatedly, in particular continuously.

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

5. 5. The method according to claim 1, wherein the flux (54) is provided by sublimation from a solid state by the heating laser light (22), and the size of the heating spot (24) is adjusted to be equal to or larger than the size of the upper surface (60) to provide the entire upper surface (60) as an active area (62) for sublimating the raw material (52).

6. 6. The method of claim 5, wherein the source (40) has an actuator (46) that moves the source element (50), and the source element (50) is moved to keep the spatial position of the active area (62) constant relative to the heating laser light (22) and the substrate (16) and to compensate for material loss due to the sublimated raw material (52).

7. 5. The method of claim 1, wherein the heating laser light melts the raw material (52) to form the active area (62) as a pool (64) of molten raw material (52) and evaporates the raw material (52) from the pool (64), thereby providing the flux (54) of raw material (52), and the size of the heating spot (24) is adjusted to be less than the size of the upper surface (60) to form the pool (64) or active area (62) having a selected size and a selected curvature.

8. 8. The method according to claim 7, wherein the size of the heating spot (24) is adjusted by appropriately adjusting the intensity distribution of the heating laser light (22), in particular 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 light (22).

9. 5. The method of claim 1, wherein the heating laser beam melts the raw material to form the active area as a pool of molten raw material and vaporizes the raw material from the pool, thereby providing the flux of raw material; the size of the heating spot is adjusted to be equal to or greater than the size of the top surface to form a pool of molten raw material as an active area over the entire top surface; and the intensity of the heating laser beam is adjusted to form the pool, i.e., the active area, having a selected curvature.

10. 5. The method of claim 1, wherein the heating laser beam melts the raw material to form the active area as a pool of molten raw material and vaporizes the raw material from the pool, thereby providing a flux of the raw material; the intensity of the heating laser beam is adjusted to form the pool of molten raw material as the active area over the entire top surface; and the intensity of the heating laser beam is further adjusted to form the pool, i.e., the active area, having a selected curvature.

11. 11. The method of claim 9 or 10, wherein the pool (64) has a flat surface with an average curvature of zero.

12. 12. The method according to any one of claims 9 to 11, wherein the source (40) has an actuator (46) that moves the source element (50), and the source element (50) is moved to keep the spatial position of the active area (62) constant relative to the heating laser light (22) and the substrate (16) and to compensate for material loss due to the evaporated raw material (52).

13. 5. The method of claim 1, wherein the source (40) comprises a crucible (42), the source element (50) is provided within the crucible (42), the heating laser light (22) melts the raw material (52) to form the active area (62) as a pool (64) of molten raw material (52) on the entire top surface (60), and evaporates the raw material (52) from the pool (64), thereby providing a flux (54) of the raw material (52), and a crucible material of the crucible (42) is selected relative to the raw material (52) to form the pool (64) or the active area (62) having a selected curvature.

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

15. 15. The method of claim 13 or 14, wherein the crucible (42) is completely filled or overfilled by surface tension with the raw material (52).

16. 16. The method of claim 13, wherein the heating spot (24) is smaller than both the top surface (60) and the active area (62), and the heating location (24) of the heating spot (24) in the active area (62) is selected relative to the local curvature of the active area (62) at the heating location (24).

17. The step of providing a selected directional intensity distribution of a flux (54) of the evaporated raw material (52) comprises a preparation step followed by an evaporation step, wherein the preparation step forms a three-dimensional shape of the upper surface (60), and the three-dimensional shape of the active area (62), which is a part of the upper surface (60), is provided for the selected directional intensity distribution of the flux (54); 5. The method according to claim 1, wherein in the evaporation step, the heating laser light (22) evaporates and / or sublimes the source material (52) from the active area (62).

18. 18. The method of claim 17, wherein in the preparation step, a shaped laser beam (30) impinging on a shaped spot (32) on the top surface (60) of the source element (50) is used to adjust the three-dimensional shape of the top surface (60), and the shaped laser beam (30) is used to melt the raw material (52) and / or provide controlled solidification of the molten raw material (52).

19. 20. The method of claim 18, wherein the shape of the molding spot (32) and / or the position of the molding spot (32) on the upper surface (60) are appropriately adjusted to provide controlled solidification of the molten raw material (52).

20. 20. The method according to claim 18 or 19, wherein the heating laser light (22) that evaporates and / or sublimes the raw material (52) from the active area (62) of the source element (50) in the evaporation step is used as a shaped laser light (30) in the preparation step.

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

22. 22. The method of claim 21, wherein the reaction chamber (12) remains closed and filled with the reaction atmosphere (14) while the preparation step and the subsequent evaporation step are repeatedly performed.

23. 23. The method of any of claims 7 to 22, wherein the source (40) comprises a resupply means (48) for resupplying additional raw material (52) into the pool (64) to compensate for material loss due to at least the evaporated raw material (52).

24. 24. The method of claim 23, wherein the resupply means (48) periodically resupplies the additional raw material (52) into the pool (64).

25. 24. The method of claim 23, wherein the resupply means (48) continuously resupplies the additional raw material (52) into the pool (64).

26. 26. The method of any of claims 23 to 25, wherein the additional raw material (52) is provided as a wire (70), and the reaction chamber (12) has a differentially pumped feedthrough that supplies the wire (70) to the resupply means (48).

27. 27. The method according to any one of claims 23 to 26, wherein the additional raw material (52) is resupplied to a position in the pool (64) away from a maximum intensity of the heating spot (24) of the heating laser light (22) and / or to an upper edge of the pool (64).

28. a thermal laser deposition (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 having a source element (50) comprising a source material (52); and a laser light source (20) providing laser light (22) that impinges with a heat spot (24) on an upper surface (60) of the source element (50) to deposit a flux (54) of evaporated or sublimated source material (52) onto the substrate (16), thereby evaporating or sublimating the source material (52) from an active area (62) of the upper surface (60) of the source element (50); A TLE system (10) configured to perform the method of any of claims 1 to 17.

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