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) comprising a reaction chamber (12) that can be filled with a reaction atmosphere (14), a substrate (16) disposed in the reaction chamber, one or more sources (40) disposed in the reaction chamber, each having a source element (42) comprising a source material (44), and a laser light source (20) that provides laser light (22) that irradiates the source elements to deposit a flux (70, 72) of evaporated or sublimated source material onto the substrate, thereby evaporating or sublimating the source material.

Description

[Technical Field]

[0001] The present invention relates to a method of using a thermal laser deposition (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 having a source element consisting of a raw material, and a laser light source that irradiates the source elements with laser light that evaporates or sublimes the raw material to deposit a flux of evaporated or sublimated raw material on the substrate. Further, the present invention relates to a 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 having a source element consisting of a raw material, and a laser light source that irradiates the source elements with laser light that evaporates or sublimes the raw material to deposit a flux of evaporated or sublimated raw material on the substrate. [Background technology]

[0002] In thermal laser deposition (TLE), in a controlled environment, in particular in a reaction chamber filled with a reactive atmosphere, source materials are evaporated and / or sublimated by laser heating, usually with the intention of coating a substrate also placed in the reaction chamber, in other words by depositing a flux of evaporated and / or sublimated source materials onto the surface of said substrate.

[0003] 1, it is known in prior art TLE systems 10 to actively block and open a deposition flux 74 using a mechanically operated shutter 80 to regulate the coating of a substrate 16. Raw material 44 in source elements 42 of a source 40 is evaporated and / or sublimated by laser light 22 directed at the source elements 42, which in the illustrated embodiment is further limited by an aperture 18. Because the shutter 80 does not block the laser light 22, a constant deposition flux 74 of evaporated and / or sublimated raw material 44 is established. Summary of the Invention [Problem to be solved by the invention]

[0004] However, shutters are additional components within the reaction chamber and are exposed to a variety of reaction atmospheres, including ultra-high vacuum and corrosive gases. In particular, in TLE systems, the short working distance between the source and the substrate often exposes the shutter to extremely high temperatures, exceeding 3500°C. Similarly, the short working distance can lead to interactions between the shutter material and the evaporated and / or sublimated raw materials, potentially resulting in impurities in the coating and / or shutter failure. When two or more sources, i.e., two or more raw materials, are present in the reaction chamber, cross-source contamination can also occur when evaporated and / or sublimated raw materials from one source are reflected off the shutter and directed toward another source.

[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 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 can provide a controlled, arbitrarily adjustable, in particular switchable on and off, flux of evaporated and / or sublimated raw material, and in particular to provide an improved method of using a thermal laser deposition system and an improved thermal laser deposition system that can increase the flux to a desired flux level instantly or at least in a short time, and / or decrease the flux to a desired flux level instantly or at least in a short time. [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 22. 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] Hereinafter, the terms "power" and "intensity" of laser light will be used synonymously, since intensity refers to power per area, and in this application, at least, the area illuminated by the incident laser light is not of significant importance.

[0008] According to a first aspect of the present invention, the above object is achieved by a method using a thermal laser deposition (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 having a source element comprising a raw material, and a laser light source that provides laser light that is irradiated onto the source elements to deposit a flux of evaporated or sublimated raw material onto the substrate, thereby evaporating or sublimating the raw material.

[0009] The method according to the present invention comprises the following steps: a) determining a desired flux of raw material vaporized and / or sublimated by said laser light; b) determining a reference thermal energy stored in said source element corresponding to said desired flux; c) determining a reference intensity of the laser light corresponding to the desired flux when the source element stores the reference thermal energy; d) determining the actual heat energy stored in said source element; e) determining the working intensity of the laser light in response to a deviation of the actual thermal energy from the reference thermal energy; - if the actual heat energy is less than the reference heat energy, the working intensity is greater than the reference intensity; - if the actual heat energy is higher than the reference heat energy, the work intensity is less than the reference intensity; and f) providing said laser light with said working intensity;

[0010] The method according to the 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 a TLE system that uses a laser to evaporate or sublimate raw material. Such systems are generally known. Laser light provided by a laser source is used to evaporate or sublimate the raw material, and in many cases, the evaporated and / or sublimated raw material is deposited on a substrate as a target. The raw material is provided as a source element arranged in a source within the reaction chamber; there can be one or more sources, which in particular provide the same and / or different raw material. The laser light is irradiated onto a surface (often the top surface) of the source element, providing a flux of evaporated and / or sublimated raw material.

[0011] 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 particularly suitable for 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.

[0012] In most cases, at least the main part of the laser source is located outside the reaction chamber and the 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 laser light to illuminate the surface of the source element.

[0013] The method of the present invention allows for the flux of evaporated and / or sublimated raw material to be controlled and turned on and off in any desired manner. Prior art TLE systems, even with laser sources providing laser light with powers of 1-10 kW or more, can be turned on and off with microsecond rise times for the laser light provided by the laser source, and thus with virtually instantaneous time-of-flight for the evaporated and / or sublimated particles. Such rapid changes in laser light power during operation can also be achieved.

[0014] Furthermore, it has been found that the actual delivered flux is strongly dependent on the laser power. Experimental data show an approximately Arrhenius-type dependence of flux on laser power. In other words, the flux decreases exponentially as the laser power is inverted. For example, in the case of Al, increasing the laser power tenfold, e.g., from 200 W to 2000 W, changes the flux by approximately three orders of magnitude (1000-fold), representing an increase from a few angstroms to several thousand angstroms. The method of the present invention utilizes and is based on these findings.

[0015] In the first step a) of the method according to the invention, the main purpose of using the TLE system, i.e. the desired flux of evaporated and / or sublimated raw materials to be provided, is defined. The desired flux is, for example, the flux of evaporated and / or sublimated raw materials required for a specific coating of a substrate also placed in the reaction chamber. In other words, the desired flux needs to be provided in each TLE system.

[0016] For a given vapor pressure of the raw material, the flux of evaporated and / or sublimated raw material depends approximately exponentially on the temperature of the source element, more precisely on the surface temperature of the source element. Thus, there is a correlation between the surface temperature and the flux of evaporated and / or sublimated raw material emitted from the surface. The applied laser light can be used to change the temperature and thus effectively change the flux of evaporated and / or sublimated raw material provided.

[0017] However, a significant amount of the irradiated laser light is stored as thermal energy in the source element. This occurs as long as the entire source element reaches thermal equilibrium, a state in which the input energy provided by the laser light is equal to the loss of all output energy, including evaporated and / or sublimated raw materials as well as radiation losses. In other words, unless this equilibrium state is reached, the bulk temperature of the source element will increase, and the surface temperature of the source element will also increase. As described above, since the surface temperature and the flux of evaporated and / or sublimated raw materials provided are correlated, the flux also increases until the thermal equilibrium is reached.

[0018] In most cases, even in the steady state of thermal equilibrium, the temperature in the bulk or surface of the source element is not uniform. Due to efficient heat loss via radiation, there are always very strong temperature gradients along the surface and within the bulk. However, in the steady state, these gradients are time-invariant; that is, they have strong spatial variations but no change over time.

[0019] In a subsequent step b) of the method according to the invention, a reference thermal energy stored in the source element is determined, said reference thermal energy corresponding to said desired flux. In the context of the invention, the thermal energy "corresponding to said desired flux" means the thermal energy stored in the source element when said thermal equilibrium is reached.

[0020] Therefore, when the reference thermal energy is stored in the source element, the temperature of the surface remains substantially constant, and the desired flux can be stably provided simply by providing laser light of appropriate intensity.

[0021] The intensity of the laser light required after reaching the thermal equilibrium is determined in a subsequent step c) of the method according to the invention as a reference intensity of the laser light, in other words, when the source element stores the reference thermal energy, laser light irradiated at the source element with the reference intensity will result in the desired flux of evaporated and / or sublimated material.

[0022] However, the thermal equilibrium is not always established when a source element is being evaporated and / or sublimated in a TLE system. In particular after a change in the desired flux, and especially at the beginning of the evaporation and / or sublimation process, the equilibrium is far from being reached and the thermal energy actually stored in the source element differs from the reference thermal energy. The thermal energy actually stored in the source element is determined as the actual thermal energy in step d) of the method according to the invention. In other words, after performing step d) of the method according to the invention, knowledge of the actual value of the thermal energy stored in the source element during the evaporation and / or sublimation process is obtained.

[0023] All of the information determined in steps a) to d) of the method according to the invention is used in the subsequent step e) to determine the working intensity of the laser light, which is determined depending on the deviation between the actual thermal energy and the reference thermal energy, in other words, whether and, if so, how much the actual thermal energy differs from the reference thermal energy.

[0024] If the actual thermal energy is less than the reference thermal energy, the thermal equilibrium has not yet been reached. In other words, the median temperature of the bulk of the source element is lower than the surface temperature of the source element required for evaporation and / or sublimation of the raw material to achieve the desired flux. In particular, the working intensity is determined according to the difference between the actual thermal energy and the reference thermal energy, taking into account how much laser energy is used to heat the bulk of the source element rather than actually evaporating and / or sublimating the source element. Therefore, the working intensity is determined to be higher than the reference intensity by an amount that at least partially compensates for the laser energy used to heat the bulk of the source element. In essence, this results in a surface temperature of the source element that is higher than the temperature of the bulk of the source element, thereby achieving an actual flux of evaporated and / or sublimated raw material that is at least close to, and preferably substantially equal to, the desired flux.

[0025] Conversely, if the actual thermal energy is higher than the reference thermal energy, the bulk temperature of the source element, and therefore often the surface temperature of the source element, will be higher than necessary for the desired flux of evaporated and / or sublimated raw material, resulting in a higher actual flux than the desired flux. Therefore, consideration is given to how low the working intensity can be set relative to the reference intensity in order to both re-achieve thermal equilibrium as quickly as possible and ensure evaporation and / or sublimation of the source element at the desired intensity. The thermal energy of the source element can be reduced, for example, by radiative cooling. Although the source element often experiences high temperatures, particularly in TLE systems, radiative cooling is an effective cooling method because radiative cooling is proportional to the fourth power of the actual temperature.

[0026] In the final step f) of the method of the present invention, the working intensity determined in step e) is applied to the laser beam. The working intensity of the laser beam is determined so that changes in the desired flux, both increases and decreases, are quickly and efficiently taken into account. In particular, increases in the desired flux, even from zero, can be provided by the method of the present invention more quickly than simply turning on the laser source at a constant laser power. Furthermore, changes between non-zero values ​​of the desired flux, both increases and decreases, can be provided by the method of the present invention more quickly and reliably, in particular faster than simply gradually increasing the laser source to the next desired intensity. Thus, the flux of evaporated and / or sublimated raw material can be adjusted in a controlled and arbitrary manner. In particular, the flux of evaporated and / or sublimated raw material is provided to increase to the desired flux level instantly or at least quickly, and / or decrease to the desired flux level instantly or at least quickly.

[0027] Furthermore, the method according to the present invention can include the following: in step a), a desired flux temperature on the surface of the source element corresponding to the desired flux is determined; and in step e), if the actual thermal energy is smaller than the reference thermal energy, the work intensity is set to a value higher than the reference intensity so that the surface of the source element reaches the desired flux temperature. As described above, the actual flux of the raw material evaporated and / or sublimated from the surface of the source element by the irradiated laser depends on the actual temperature of the surface of the source element. In other words, if the reference thermal energy is stored in the source element, the desired flux temperature corresponds to the bulk temperature, particularly the surface temperature of the source element. If the actual thermal energy is smaller than the reference thermal energy, the desired flux temperature is higher than the temperature corresponding to the actual thermal energy. By determining the work intensity so that the surface of the source element has the desired flux temperature determined in step a), the actual flux of the evaporated and / or sublimated raw material also reliably matches the desired flux. This allows the heating of the source element to have a very non-uniform character, with local temperatures at the surface of the source element being several orders of magnitude higher, both in time and space, than in the rest of the source element, especially the bulk.

[0028] According to another improved embodiment of the method of the present invention, the actual temperature of the surface of the source element is measured, and in step e) the actual temperature is compared with the desired flux temperature, preferably in a closed-loop control. Because of the correlation between surface temperature and the flux of evaporated and / or sublimated raw material, measuring the actual temperature of the surface of the source element is an effective way of monitoring the actual flux of evaporated and / or sublimated raw material. The measurement is provided by a suitable temperature sensor, such as a pyrometer. By comparing the measured actual temperature with the desired flux temperature, deviations of the actual flux from the desired flux can be identified. If the measured temperature is lower than the desired flux temperature, the application intensity determined in step e) is increased, and vice versa. The closed-loop control comparison ensures a stable flux of evaporated and / or sublimated raw material that achieves the desired flux, particularly over long periods of time.

[0029] The method according to the present invention can also be characterized in that in step d), - initial thermal energy stored in said source element; - the mass of said source element; - the heat capacity of said raw material; - the thermal conductivity of said raw material; the total amount of laser energy already applied to the source element; One or more, preferably all, of the above characteristics are taken into consideration to determine the actual heat energy. This list is not exhaustive, and additional characteristics can be added that affect the actual thermal energy stored in the source element. The initial thermal energy provides a starting point for calculations. The total amount of laser energy already irradiated on the source element can be used to estimate the amount of thermal energy already absorbed by the source element. By taking into account the mass, heat capacity, and / or thermal conductivity of the source element, the response of the source element to the energy provided and absorbed by the laser light can be estimated.

[0030] Alternatively or additionally, the method according to the invention may comprise the step d) of determining the actual heat energy by comparison with experimental and / or simulated data, which may be prepared in advance, for example provided as a look-up table, preferably electronically accessible, such that computationally intensive and complex calculations have been performed in advance, making the implementation of the method according to the invention less computationally intensive and complex.

[0031] Furthermore, the method according to the present invention can be characterized in that at least steps d) to f), preferably steps a) to f), are repeatedly performed, preferably in a closed-loop control. Repeating in the sense of the present invention includes a repetition rate of less than 100 mHz to more than 10 MHz. In other words, during the evaporation and / or sublimation process, the actual thermal energy is determined, in particular repeatedly or continuously (step d)), and the application intensity is determined thereon (step e)). This allows for quick consideration of changes in the actual thermal energy stored in the source element. This makes it possible to provide the laser light with an updated, if necessary, adjusted application intensity (step f). This allows for repeatedly adjusting the desired flux of the evaporated and / or sublimated raw material. The repeated execution of the closed-loop control, in particular based on the actual thermal energy stored in the source element, allows for a stable flux of the evaporated and / or sublimated raw material as the desired flux, in particular over a long period of time.

[0032] The method according to the present invention may also include the following: In step e), the work intensity is determined such that the difference between the work intensity and the reference intensity depends on the difference between the actual thermal energy and the reference thermal energy, or the ratio between the work intensity and the reference intensity depends on the ratio between the actual thermal energy and the reference thermal energy. If the reference thermal energy is higher than the actual thermal energy, the greater the deviation of the actual thermal energy stored in the source element from the reference thermal energy, the more energy of the irradiated laser light is spent to heat the bulk of the source element. Also, if the actual thermal energy is higher than the reference thermal energy, the energy of the laser light irradiated to the source element prevents the actual thermal energy from decreasing. Both the difference and the ratio are variables that represent the amount of deviation, allowing the correlation to be taken into consideration. Therefore, as the deviation between the actual thermal energy and the reference thermal energy increases or decreases, the deviation between the work intensity and the reference intensity increases or decreases. This allows the thermal equilibrium to be reached more quickly.

[0033] For example, at the beginning of the evaporation and / or sublimation process, immediately after turning on the laser, the deviation between the actual thermal energy and the reference thermal energy is greatest, and the deviation between the determined working intensity and the reference intensity is also greatest. After a while, the bulk of the source element absorbs some of the laser energy and heats up, causing the actual thermal energy to increase, thus reducing the deviation from the reference thermal energy. Consequently, the deviation between the working intensity and the reference intensity also reduces. Ultimately, ideally, the working intensity will converge to the reference intensity for a given desired flux.

[0034] The method according to the present invention can also be improved by: if the actual thermal energy is smaller than the reference thermal energy and the deviation exceeds a first threshold, the working intensity is set to the maximum intensity of the laser light, and / or if the actual thermal energy is higher than the reference thermal energy and the deviation exceeds a second threshold, the working intensity is set to the minimum intensity of the laser light, preferably zero. The laser light source cannot provide laser light with an intensity higher than the maximum intensity, and similarly cannot provide laser light with an intensity lower than the minimum intensity or zero.

[0035] In particular, the dependence of the working intensity on the deviation may lead to an excessively large deviation leading to an excessively large or small working intensity determined in step e) of the method according to the invention, which is too high or too low for the laser light source to provide. Preferably, the first and second thresholds are selected in such a way that excessively large deviations are identified and at least partially addressed by providing the laser light with the maximum or minimum intensity. Thus, even for excessively large deviations between the actual thermal energy and the reference thermal energy, the execution of the method according to the invention is guaranteed, without setting the working intensity to a value that cannot be provided, which would jeopardize the structural integrity of the laser light source.

[0036] According to another improved embodiment of the method of the present invention, the difference between the work intensity and the reference intensity is proportional to the difference between the actual thermal energy and the reference thermal energy, or the ratio between the work intensity and the reference intensity is proportional to the ratio between the actual thermal energy and the reference thermal energy. Proportionality is a very simple mathematical relationship between two values, and exists for the difference or ratio between the actual thermal energy and the reference thermal energy, and the difference or ratio between the work intensity and the reference intensity, respectively. Furthermore, a proportional relationship can be easily implemented in a control algorithm. Therefore, the proportionality of the relationship allows for a simplification of the method of the present invention.

[0037] Furthermore, the method according to the invention can comprise: in step e) determining a deviation of the actual thermal energy from the reference thermal energy if the actual thermal energy differs from the reference thermal energy by more than 10%, in particular by more than 1%, preferably by more than 0.1%. In other words, according to this embodiment, the existence of the deviation is determined only if the actual thermal energy has a value outside a predetermined range centered on the reference thermal energy.

[0038] If the range is not defined, any deviation, no matter how small, would result in a change to the determined application intensity. This could lead to undesired oscillations of the determined application intensity around the reference intensity, and therefore of the actually provided flux of evaporated and / or sublimated raw material around the desired flux, particularly at a later stage of the evaporation and / or sublimation process, when at least the thermal equilibrium of the source element has been reached and the application intensity is therefore at least close to the reference intensity. By applying the range, no deviations are determined within the range, and therefore such undesired oscillations can be avoided.

[0039] The method can be characterized in that the desired flux is determined over a period of time and / or has a time dependency. In other words, the desired flux can have a time start point and a time end point. This allows, for example, to set an integral value of the provided flux of evaporated and / or sublimated raw material. The period of time can also be fragmented, in other words, the desired flux can be determined with several active periods separated by rest periods. Additionally or alternatively, the time dependency of the determined desired flux in the sense of the present invention includes possible changes in the value of the flux itself during the active periods, for example, an increase and / or decrease of the flux. This allows a wide variety of desired fluxes to be determined.

[0040] According to an improved embodiment of the method, the desired flux determined in step a) has one or more constant intervals. A constant flux of evaporated and / or sublimated raw material is often required in coating processes, in particular for purity reasons and to support a uniform growth of the coating layer. By carrying out the method according to the invention, which provides a desired flux having one or more constant intervals, the constant flux is also provided.

[0041] The method according to the present invention can be further improved by: That is, the desired flux comprises at least two intervals with a constant desired flux, the desired fluxes differing from each other by a factor of at least two, in particular by a factor of at least ten, and preferably by a factor of at least one hundred, and the two intervals are preferably adjoining and / or following intervals. As described above, the actual provided flux of evaporated and / or sublimated raw material strongly depends on the laser power, i.e., on the desired intensity and the working intensity, respectively. In particular, by changing the intensity of the provided laser light, the flux can be varied over a wide range in a short period of time. The abundance of evaporated and / or sublimated raw material arriving at the substrate affects the surface mobility on the substrate, which can be used, for example, to control the growth rate. Adjoining and / or following intervals within the meaning of the present invention generally encompass intervals immediately following each other. However, intervals following each other with a short passing interval are also considered adjoining and / or following intervals if the intervals are negligible with respect to the duration of the two intervals with the constant desired flux.

[0042] According to a further improved embodiment, the method according to the invention comprises the following: the desired flux determined in step a) has one or more increasing and / or decreasing sections, in particular linear increasing and / or decreasing sections. In some applications, it may be desirable to have an increasing and / or decreasing flux of evaporated and / or sublimated raw material. According to the invention, different fluxes are provided by different application intensities, which can be achieved in a very short time, on the order of microseconds or even faster. Since steps a) to f) are preferably performed continuously, this applies not only to transitions from section to section with different values ​​of constant desired flux, but also to sections where the desired flux increases and / or decreases, in particular sections where the desired flux increases and / or decreases linearly.

[0043] According to a further improved embodiment of the method of the present invention, the desired flux determined in step a) has a continuous pattern of a period during which the desired flux is constant throughout a first period, followed by a period during which the desired flux is not present throughout a second period, the first and second periods being selected so that the reference thermal energy is not reached during evaporation and / or sublimation of the raw material. Providing evaporated and / or sublimated raw material with a continuous desired flux results in a source element that stores the reference thermal energy over time. Therefore, the source element, particularly its surface, continuously maintains the desired flux temperature corresponding to the reference thermal energy. However, parasitic heating of the surroundings of the source element, such as due to radiative cooling of the source element, inevitably occurs. This is often not negligible and is harmful to other elements of the TLE system, particularly the substrate. As described above, determining the desired flux as a continuous pattern can dramatically reduce harmful parasitic heating of the environment caused by the source element.

[0044] An advantage of the method of the present invention is that during the first period, the constant desired flux can be provided almost instantaneously at the beginning of each period. However, the bulk of the source element remains at a lower temperature because the source element provides only the surface with the desired flux temperature corresponding to the desired flux. During the second period, without heating by the laser light, the temperature of the source element equalizes and remains significantly lower than the desired flux temperature. This procedure is then repeated. In other words, the average temperature of the source element continues to remain significantly lower than the desired flux temperature. In this way, the overall effect of parasitic heating can be reduced by taking the time necessary to provide the appropriate total amount of evaporated and / or sublimated raw material flux.

[0045] Furthermore, the method according to the invention can also be improved by: during the first period of time, the average of the actual thermal energy is less than 0.5 times the reference thermal energy, in particular less than 0.25 times the reference thermal energy; the average thermal energy directly defines the average temperature of the source element, in particular of the surface of the source element; since the radiative cooling scales with the fourth power of the temperature, reducing the average of the actual thermal energy to half or a quarter of the reference thermal energy allows for a more rapid reduction in the effects of parasitic heating.

[0046] The method according to the present invention can also be characterized as follows: the source has cooling means, and the method includes actively cooling the source element by the cooling means during evaporation and / or sublimation of the raw material. The cooling means may, for example, have cooling ducts in a cooling body thermally attached to the source element, through which a coolant fluid, such as water or liquid nitrogen, flows. As described above, if the actual thermal energy is higher than the reference thermal energy, the temperature of the bulk of the source element is higher than the temperature corresponding to the desired flux. Therefore, it is necessary to cool the source element to remove at least a portion of the stored thermal energy. By providing cooling means, cooling is improved and accelerated, especially compared to radiative cooling alone.

[0047] According to an improved embodiment of the method according to the invention, the source element is continuously and actively cooled by the cooling means, in other words the cooling means operates continuously and in particular is not repeatedly switched on and off, which allows to simplify the implementation of the method according to the invention, and in particular a TLE system adapted to implement the method according to the invention.

[0048] Furthermore, the method according to the invention can be improved by taking into account active cooling of the source element by the cooling means when determining the reference intensity in step c). Active cooling of the source element by the cooling means takes away thermal energy ultimately provided by the laser light, especially if the cooling is provided continuously. "Taking active cooling into account" in the sense of the invention means determining the working intensity in such a way that an extra intensity is added to compensate for the active cooling. In this way, the positive effect of the cooling, in particular a faster response of the actual flux to a decrease in the desired flux, can be achieved simultaneously with the overall advantage of the method according to the invention, namely a fast, in particular almost instantaneous, response to an increase in the desired flux, especially when the evaporation and / or sublimation process is turned on.

[0049] Furthermore, the method of the present invention can include the following: the TLE system has two or more sources, each having a source element consisting of a raw material, and steps a) to f) are performed for each of the raw materials to evaporate and / or sublimate the raw material. In other words, in the TLE system, two or more raw materials are evaporated and / or sublimated, and the evaporation and / or sublimation processes are performed using the method of the present invention. The evaporation and / or sublimation processes of different raw materials can be performed simultaneously or separately. Therefore, for each raw material, the flux of the evaporated and / or sublimated raw material can be adjusted in any controlled manner. In particular, the provided flux of the evaporated and / or sublimated raw material can be increased to a desired flux level instantly, or at least in a short time, and / or decreased to a desired flux level instantly, or at least in a short time.

[0050] The method of the present invention can also be improved by: the desired flux determined in step a) for the first raw material is higher than the desired flux determined in step a) for the second raw material, and each step e) is performed simultaneously for both raw materials. By performing this embodiment of the method of the present invention, the first raw material is present at the surface of the substrate to be coated in greater abundance than the second raw material. This can be used, for example, to ensure a specific stoichiometric ratio of two raw materials on the substrate surface.

[0051] The improved form of the method described in the above paragraph is not limited to two raw materials, but can be analogously implemented for three or more raw materials. In particular, the method according to the present invention can include performing step a) for three or more raw materials to determine a respective desired flux for each of the three or more raw materials, and performing each step e) simultaneously for all of the three or more raw materials. Thus, a desired specific stoichiometric ratio of three or more raw materials on the substrate surface can also be provided.

[0052] The embodiments described in the preceding paragraphs are not limited to two feedstocks, but can be implemented with three or more feedstocks evaporated and / or sublimated simultaneously and / or sequentially in the same TLE system.

[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 comprising a raw material; and a laser light source providing laser light that is irradiated onto the source elements to deposit a flux of evaporated or sublimated raw material onto the substrate, thereby evaporating or sublimating the raw material. The TLE system according to the second aspect of the present invention is configured to carry out the method according to the first aspect of the present invention. The thermal laser deposition system according to the second aspect of the present invention thereby provides all of the features and advantages described with respect to the method according to the first aspect of the present invention.

[0054] The present invention will be described in detail below by way of embodiments with reference to the drawings. The drawings show the following: [Brief explanation of the drawings]

[0055] [Figure 1] FIG. 1 is a schematic diagram of a prior art TLE system with a shutter. [Figure 2] 1 shows the power, flux and source temperature versus time in a preparatory step and in a first embodiment of the method according to the invention; FIG. [Figure 3] 4 shows the cooling means and the power, flux and source temperature versus time in a second embodiment of the method according to the invention; FIG. [Figure 4] FIG. 10 shows the relationship between power, flux and source temperature and time in a third embodiment of the method according to the invention. [Figure 5] FIG. 10 shows the relationship between power, flux and source temperature and time in a fourth embodiment of the method according to the invention. [Figure 6] FIG. 2 shows the relationship between flux and substrate temperature versus time for two different embodiments of the method according to the invention. [Figure 7] 1 is a schematic diagram of a thermal laser deposition system according to the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0056] 2 to 5 include several diagrams that show schematically the relationship between the laser power (denoted P), i.e., the laser intensity 30, 32, the desired flux 70 and the actual flux 72 of evaporated and / or sublimated raw material 44 (denoted F), and the source temperature 60, 62 (denoted T), in particular the source temperature 62, and time (denoted t).

[0057] 2-5, the fluxes 70, 72 and temperatures 60, 62 are depicted by the same line for simplicity of plotting. In fact, the depicted lines are plots of the fluxes 70, 72. Because the fluxes 70, 72 exhibit an Arrhenius-type dependence on the temperatures 60, 62, particularly the surface temperature 62, the plots of the temperatures 60, 62 show slightly different curves without any significant changes. In particular, due to the Arrhenius-type dependence, there is no general proportionality between the fluxes 70, 72 and the temperatures 60, 62.

[0058] 2-5 and 6 are depicted with respect to a single source element 42 (see FIG. 7 for each TLE system 10 and its elements), however, embodiments describing the method of the present invention may also be applied to a TLE system 10 having two or more sources 42, where evaporation and / or sublimation processes for the two or more sources 42 may be performed simultaneously and / or sequentially, with each process implementing the method of the present invention as appropriate for the particular evaporation and / or sublimation process.

[0059] For elements of the TLE system 10 referred to in the following description that are not depicted in FIGS. 2-6, please refer to FIG.

[0060] 2A shows a preparatory diagram, and FIG. 2B shows a diagram of an actual embodiment of the method according to the present invention. Both diagrams show an evaporation and / or sublimation process using a desired flux 70, the supply of which begins at a first point in time t1 and ends at a second point in time t2. The desired flux 70 corresponds to a desired flux temperature 60 with a typical Arrhenius-type dependence of vapor pressure.

[0061] In the warm-up stage shown in FIG. 2A, the laser source 20 provides a constant working intensity 32 corresponding to the reference intensity 30 and is simply turned on at t1 and turned off at t2. This is indicated by the rectangles representing the reference intensity 30 and the working intensity 32, respectively. However, at t1, the bulk of the source element 42 has a temperature much lower than the desired flux temperature 60. Therefore, a non-negligible amount of the energy of the applied laser light 22 is used to heat the source element 42. Therefore, as shown in FIG. 2A, the actual temperature 62, and therefore the actual provided flux 72, follows a slowly rising curve.

[0062] In contrast, Figure 2B is a similar diagram illustrating the evaporation and / or sublimation process of a first embodiment of the method according to the invention. As in Figure 2A, a desired flux 70, represented by a desired flux temperature 60, is set in the first step a) of the method according to the invention and is to be joined by an actual flux 72. Note that after t2, the desired flux temperature 60 drops to zero. As shown, the desired flux 70 includes or consists of a section of constant value.

[0063] Also, in a next step b), a reference thermal energy corresponding to a desired flux 70 is determined so that the source element 42 stores said reference thermal energy when the average temperature of the source element 42 is at the desired flux temperature 60.

[0064] Further, in a next step c), a reference intensity 30 corresponding to the desired flux 70 and the reference thermal energy is determined. In particular, the reference intensity 30 is the particular intensity of the laser light 22 required to provide the desired flux 70 when the source element 42 stores the reference thermal energy.

[0065] The next two steps d) and e) are significant departures from simply turning on laser light 22 as shown in Figure 2A. First, in step d), the actual heat energy stored in source element 42 is determined. In other words, after step d), information is available that indicates how much source element 42 is being heated in the ongoing evaporation and / or sublimation process.

[0066] This information is used in the subsequent step e) to compare the actual thermal energy with the reference thermal energy, thereby determining the deviation between these values.

[0067] If the reference thermal energy is greater than the actual thermal energy, at least part of the energy of the laser light 22 is used to heat the bulk of the source element 42 and not to evaporate and / or sublimate the source element 42, and vice versa. Based on this knowledge, in the former case, a working intensity 32 higher than the reference intensity 30 is determined, and in the latter case, a working intensity 32 lower than the reference intensity 30 is determined. In order to avoid undesired oscillations of the determined working intensity 32, it is predicted that the deviation between the actual thermal energy and the reference thermal energy is determined only if their values ​​differ by more than 10%, in particular by more than 1%, and preferably by more than 0.1%.

[0068] In the final step f) of the method according to the invention, the laser light 22 is provided with the working intensity 32 determined in the previous step e).

[0069] As a result, as long as the actual thermal energy stored in the source element 42 is less than the reference thermal energy, the work intensity 32 is determined to be high enough to compensate for the energy loss due to heating of the source element 42. Thus, the actual temperature 62 at the emitting surface 46 of the source element 42 can be decoupled from the actual thermal energy. Because the actual flux 72 emanating from the source element 42 is strongly related to the actual temperature 62 at the emitting surface 46, it is possible to provide an actual flux 72 corresponding to the desired flux 70 approximately immediately after time t1 without the need for a shutter 80, as shown in FIG. 2B.

[0070] After time t2, the desired flux 70 is set to zero. Therefore, the actual thermal energy stored in the source element 42 rapidly becomes greater than the reference thermal energy determined in step b) of the method according to the present invention. Therefore, the work intensity 32 is also determined to the lowest possible value, i.e., also zero. Thus, the actual thermal energy stored in the source element 42 also decreases in the embodiment of FIG. 2 , primarily due to radiative cooling. This is an effective cooling method, especially for the high temperatures often encountered by the source element 42 in the TLE system 10, because the radiative cooling is proportional to the fourth power of the actual temperature 62 at the surface 46 of the source element 42. Therefore, the actual temperature 62 at the surface 46 also decreases rapidly, and the actual flux 72 quickly reaches the desired flux 70 and then stops.

[0071] Preferably, the desired flux temperature 60 is determined together with the desired flux 70. As already mentioned, the actual flux 72 resulting from the source element 42 is strongly related to the actual temperature 62 of the emitting surface 46 of the source element 42. Therefore, the work intensity 32 is preferably determined in step e) so that said surface 46 reaches said desired flux temperature 60. In practical control, in particular in closed-loop control, said actual temperature 62 can be measured by a suitable temperature sensor 66, making it possible to take into account the measured actual temperature 62 compared with said desired flux temperature 60 when determining the work intensity 32 in step e) of the method according to the invention.

[0072] Overall, it is advantageous to repeatedly perform steps a) to f) or at least steps d) to f) of the method according to the invention. In addition to or as an alternative to the closed-loop control based on the temperatures 60, 62, a closed-loop control based on the thermal energy stored in the source element 42 is possible. In particular, the actual thermal energy stored in the bulk of the source element 42 can be determined by calculation, taking into account the characteristics of the source element 42 at the corresponding setting, and / or by comparison with experimental and / or simulation data.

[0073] In order to reach the reference heat energy as quickly as possible, it is preferable to take into account the deviation between the reference heat energy and the actual heat energy when determining the work intensity 32. Generally, the greater the deviation in heat energy, the greater the deviation of the work intensity 32 from the reference heat energy 30. To take the deviation into account, for example, the difference or ratio between the actual heat energy and the reference heat energy can be used as a criterion for determining the difference or ratio between the work intensity 32 and the reference heat energy 30. For example, the difference or ratio can be proportionally related.

[0074] An example of this procedure is clearly shown in FIG. 2B. At time t1, the thermal energy stored in the source element 42 is minimal, so the deviation between the actual thermal energy and the reference thermal energy is large. Therefore, the deviation between the determined working intensity 32 and the reference intensity 30 also reaches a maximum value at the beginning of the evaporation and / or sublimation process. If this deviation exceeds a threshold, the maximum intensity that the laser source 20 can provide can be set as the working intensity 32 that will not damage the laser source 20. As time approaches t2, the temperature of the source element 42 increases, so that the actual thermal energy stored in the source element 42 approaches the reference thermal energy. This behavior is also transmitted to the determined working intensity 32, which converges toward the reference intensity 30.

[0075] As discussed with respect to Figure 2B, when the desired flux 70 drops sharply to zero, the actual heat energy stored in the source elements 42 must be removed. Figure 3 shows a preferred refinement in which the source elements 42 are cooled not only by radiative cooling but also by dedicated cooling means 50.

[0076] 3A in FIG. 3 is a schematic diagram of a source 40 having a source element 42 and the cooling means 50. The bulk of the source element 42, consisting of raw material 44, is thermally coupled to a body 52 of the cooling means 50. Inside the body 52, a cooling duct 54 is arranged for the flow of a coolant fluid 56, such as water or liquid nitrogen. The cooling means 50 preferably operates continuously; in other words, the source element 42 is preferably cooled at all times.

[0077] FIG. 3B shows a diagram of an evaporation and / or sublimation process similar to FIG. 2B. The difference is that the source 40 used in the illustrated evaporation and / or sublimation process is equipped with cooling means 50. The cooling means 50 preferably continuously cools the source element 42. Since the additional energy loss caused by this cooling must be compensated for, this cooling is preferably taken into account when determining the work intensity 32. This occurs approximately immediately after time t1 in FIG. 3, when the actual flux 72 again reaches the desired flux 70. Again, the desired flux 70 corresponds to the desired flux temperature 60. For the remaining general features of the method according to the present invention shown in FIG. 3B, please refer to the description above regarding FIG. 2B.

[0078] A significant advantage of providing the cooling means 50 can be seen after time t2, when the desired flux 70 decreases again to zero. In particular, because the cooling means 50 starts cooling from a lower actual temperature 62 and cools the source element 42 more efficiently than radiative cooling alone, the actual thermal energy reaches the reference thermal energy more quickly, and the actual temperature 62 of the surface 46 also decreases more quickly to the desired flux temperature 60. As a result, the provided actual flux 72 can be turned off almost instantaneously, without the need for a shutter 80.

[0079] 2 and 3, the desired flux 70 may have a section with a constant value of the desired flux 70. However, since the response time of commonly used laser sources 20 is on the order of microseconds, the method according to the present invention is not limited to the constant desired flux 70.

[0080] 4, intervals in which the value determined as desired flux 70 increases and / or decreases in a particularly linear manner are possible, i.e., linearly increasing between t1 and t2 and linearly decreasing between t2 and t3, so that the reference intensity 30, and in particular also the working intensity 32, is determined during the execution of the method according to the invention, so that the actual temperature 62 and the actual flux 72 almost instantly follow the desired flux temperature 60 and the desired flux 70, respectively. Here too, the desired flux 70 corresponds to the desired flux temperature 60.

[0081] 5 illustrates a more complex evaporation and / or sublimation process, where a first interval between t1 and t2 during which the desired flux 70 is constant is followed by a second interval between t2 and t3 during which the desired flux 70 is constant at a lower value. Again, the desired flux 70 corresponds to the desired flux temperature 60.

[0082] The determined work intensity 32 compensates for the deviation between the actual thermal energy stored in the source element 42 and the reference thermal energy determined during the execution of the method of the present invention. At the start time t1, the source element 42 is relatively cold and needs to be heated. As a result, the determined work intensity 32 starts at a maximum value and converges towards the first value of the reference intensity 30 towards t2.

[0083] After time t2, the desired flux 70 decreases to a new, lower value. Therefore, the actual thermal energy stored in the source element 42 is higher than the reference thermal energy. As a result, the value of the work intensity 32 is determined to be zero, and the temperature of the source element 42 decreases. Shortly thereafter, when the surface 46 of the source element 42 reaches the actual temperature 62, the determined value of the work intensity 32 begins to increase again, converging toward the new value of the reference intensity 30. After time t3, the desired flux 70 decreases to zero, thereby determining the work intensity 32 to be zero. Because the cooling of the source element 42 is not complete, the actual decrease in the actual temperature 62, and therefore the actual flux 72, is somewhat delayed.

[0084] It should be noted that the two different values ​​of constant actual flux 72 shown in the figure are merely exemplary: by carrying out the method according to the invention, the values ​​of said actual flux 72 can differ by a factor of more than two, in particular by a factor of more than ten, preferably by a factor of more than 100.

[0085] Figure 6 illustrates another beneficial use of the method of the present invention, in particular to avoid parasitic heating of the substrate 16. Figures 6A and 6B in Figure 6 show the fluxes 70, 72 and the substrate temperature 64 versus time. The actual flux 72, and in particular its rapid convergence to the desired flux 70, is provided using the method of the present invention as described above.

[0086] 6A, desired flux 70 and actual flux 72 are provided as continuous fluxes 70, 72 having constant values. Thus, the source element is heated (temperatures 60, 62 of source element 42 are not shown) until it stores a reference thermal energy and actual temperature 62 equals desired flux temperature 60. However, because source element 42 is constantly radiatively cooled, substrate 16 heats up slowly, as seen by the rise in substrate temperature 64. Unfortunately, a high substrate temperature 64 can be detrimental not only to the coating process, but also, in worst cases, to the structural integrity of substrate 16.

[0087] FIG. 6B illustrates a possible solution to the parasitic heating problem, provided by the method of the present invention. As described above, by implementing the method of the present invention, the actual flux 72 of evaporated and / or sublimated raw material 44 can be turned on and off almost instantaneously, particularly without a shutter 80. Thus, in this case, the desired flux 70, and thus at least substantially the actual flux 72, has a continuous pattern of intervals of constant flux 70, 72 and no flux 70. The time period of these intervals is selected so that the actual thermal energy never reaches the reference thermal energy. In fact, the average actual thermal energy is preferably less than 0.5 times the reference thermal energy, particularly less than 0.25 times the reference thermal energy. Nevertheless, the desired flux 70 can be provided by appropriately determining the work intensity 32 (not shown). As FIG. 6B shows, although some parasitic heating of the substrate 16 still remains, the substrate temperature 64 oscillates around a significantly lower value. This avoids the detrimental effects of the parasitic heating.

[0088] 8 shows 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 carry out the method according to the present invention. A source 40 providing a source element 42 with a raw material 44 and a substrate 16 are arranged within a reaction chamber 12. Cooling means 50 are also provided for actively cooling the source element 42. A temperature sensor 66 is used to measure the actual temperature 62 (see FIGS. 2 to 5) of the source element 42. The reaction chamber 12 is either vacuum or filled with a reaction atmosphere 14, such as a suitable reaction gas.

[0089] Laser light 22 provided by laser source 20 is coupled into reaction chamber 10 to irradiate surface 46 of source element 42. By performing a method according to the present invention, for example in one of the embodiments described with reference to Figures 2-6, the actual flux 72 of evaporated and / or sublimated raw material 44 can be adjusted in any controlled manner. In particular, the provided actual flux 72 of evaporated and / or sublimated raw material 44 can be increased to the value of desired flux 70 instantaneously, or at least in a short time, and / or decreased to the value of desired flux 70 instantaneously, or at least in a short time. [Explanation of symbols]

[0090] 10 TLE systems 12 Reaction Chamber 14 Reaction atmosphere 16 boards 18 aperture 20 Laser light source 22 Laser light 30 Reference Intensity 32 Work Intensity 40 sauces 42 Source Elements 44 raw materials 46 Surface 50 Cooling means 52 Main Unit 54 Cooling duct 56 Coolant Fluid 60 Desired flux temperature 62 Actual Temperature 64 Substrate temperature 66 Temperature Sensor 70 Desired Flux 72 Actual Flux 74 Evaporation Flux 80 Shutter

Claims

1. 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 (42) comprising a source material (44); and a laser light source (20) providing laser light (22) that irradiates the source elements (42) to deposit a flux (70, 72) of evaporated or sublimated source material (44) onto the substrate (16), thereby evaporating or sublimating the source material (44); a) determining a desired flux (70) of raw material (44) vaporized and / or sublimated by said laser light (22); b) determining a reference thermal energy stored in said source element (42) corresponding to said desired flux (70); c) determining a reference intensity (30) of the laser light (22) corresponding to the desired flux (70) when the source element (42) stores the reference thermal energy; d) determining the actual heat energy stored in said source element (42); e) determining the working intensity (32) of the laser light (22) in response to the deviation of the actual thermal energy from the reference thermal energy; - if the actual heat energy is less than the reference heat energy, the working intensity (32) is greater than the reference intensity (30); - if the actual heat energy is higher than the reference heat energy, the working intensity (32) is less than the reference intensity (30); and f) providing said laser light (22) with said working intensity (32); A method comprising the above steps.

2. In step a), a desired flux temperature (60) on the surface (46) of the source element (42) corresponding to the desired flux (70) is determined; 2. The method of claim 1, wherein in step e), if the actual thermal energy is less than the reference thermal energy, the working intensity is set to a value higher than the reference intensity so that the surface of the source element reaches the desired flux temperature.

3. 3. The method of claim 2, wherein an actual temperature (62) of the surface (46) of the source element (42) is measured, and in step e) the actual temperature (62) and the desired flux temperature (60) are compared, preferably in a closed-loop control.

4. In step d), - initial thermal energy stored in said source element (42); the mass of said source element (42); - the heat capacity of said raw material (44); - the thermal conductivity of said raw material (44); - the total amount of laser energy already delivered to said source element (42); 4. A method according to any of claims 1 to 3, wherein the actual heat energy is determined taking into account one or more, preferably all, of the above characteristics.

5. 5. The method according to claim 1, wherein in step d) the actual thermal energy is determined by comparison with experimental and / or simulation data.

6. 6. The method according to any one of claims 1 to 5, wherein at least steps d) to f), preferably steps a) to f), are carried out repeatedly, preferably with closed-loop control.

7. In step e), the difference between said working intensity (32) and said reference intensity (30) depends on the difference between said actual heat energy and said reference heat energy, or so that the ratio of said working intensity (32) to said reference intensity (30) depends on the ratio of said actual heat energy to said reference heat energy; The method according to any one of claims 1 to 6, wherein the work intensity (32) is determined.

8. If the actual thermal energy is less than the reference thermal energy and the deviation exceeds a first threshold, the working intensity (32) is set to a maximum intensity of the laser light (22); and / or 8. The method of claim 7, wherein if the actual thermal energy is higher than the reference thermal energy and the deviation exceeds a second threshold, the working intensity (32) is set to a minimum intensity of the laser light (22), preferably zero.

9. the difference between the working intensity (32) and the reference intensity (30) is proportional to the difference between the actual heat energy and the reference heat energy, or 8. The method of claim 7, wherein the ratio of the work intensity (32) to the reference intensity (30) is proportional to the ratio of the actual heat energy to the reference heat energy.

10. 10. The method according to claim 1, wherein in step e) a deviation of the actual thermal energy from the reference thermal energy is determined if the actual thermal energy differs from the reference thermal energy by more than 10%, in particular by more than 1%, preferably by more than 0.1%.

11. The method of any of claims 1 to 10, wherein the desired flux (70) is determined over a period of time and / or has a time dependency.

12. The method of claim 11, wherein the desired flux (70) determined in step a) has one or more constant intervals.

13. 13. The method according to claim 12, wherein the desired flux (70) has at least two sections with a constant desired flux (70), the desired fluxes (70) differing from each other by a factor of at least two, in particular by a factor of at least ten, preferably by a factor of at least one hundred, the two sections being preferably adjacent and / or subsequent sections.

14. 14. The method according to any of claims 11 to 13, wherein the desired flux (70) determined in step a) has one or more increasing and / or decreasing sections, in particular linear increasing and / or decreasing sections.

15. 15. The method of claim 11, wherein the desired flux (70) determined in step a) has a continuous pattern of intervals with a constant desired flux (70) during a first time period followed by intervals without the desired flux (70) during a second time period, the first time period and the second time period being selected such that the reference thermal energy is not reached while the raw material (44) is being evaporated and / or sublimated.

16. 16. The method according to claim 15, wherein during the first period of time, the average actual heat energy is less than 0.5 times the reference heat energy, in particular less than 0.25 times the reference heat energy.

17. 17. The method according to any one of claims 1 to 16, wherein the source (40) comprises cooling means (50), and the method comprises actively cooling the source element (42) by the cooling means (50) during evaporation and / or sublimation of the raw material (44).

18. 18. The method of claim 17, wherein the source element (42) is continuously and actively cooled by the cooling means (50).

19. 19. The method according to claim 17 or 18, wherein active cooling of the source element (42) by the cooling means (50) is taken into account when determining the reference intensity (30) in step c).

20. 20. The method of any of claims 1 to 19, wherein the TLE system (10) has two or more sources (40), each source (40) having a source element (42) comprising a source material (44), and steps a) to f) are performed for each of the source materials (44) for evaporation and / or sublimation of the source material (44).

21. 21. The method of claim 20, wherein the desired flux (70) determined in step a) for the first feedstock (44) is higher than the desired flux (70) determined in step a) for the second feedstock (44), and each step f) is performed simultaneously for both feedstocks (44).

22. a reaction chamber (12) that can be 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 (42) comprising a raw material (44); a laser light source (20) for providing laser light (22) that is irradiated onto the source element (42) to deposit a flux (70, 72) of evaporated or sublimated raw material (44) onto the substrate (16), thereby evaporating or sublimating the raw material (44); A thermal laser deposition (TLE) system (10) comprising: A TLE system (10) configured to perform the method of any of claims 1 to 21.

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