Method for controlling flux distribution of evaporated source material, detector for measuring electromagnetic radiation reflected from a source surface, and system for thermal evaporation using electromagnetic radiation

Abstract

The present invention relates to a method for controlling the flux distribution (30) of evaporated source material (20) in a system (10) for thermal evaporation using electromagnetic radiation (120). The system (10) comprises an electromagnetic radiation source (110) for providing the electromagnetic radiation (120), a vacuum chamber (12) containing a reaction atmosphere (16), and a detector (40) for measuring the electromagnetic radiation (120). The source material (20) and a target material (18) to be coated are disposed within the vacuum chamber (12), the radiation source is positioned such that its electromagnetic radiation (120) is incident on a source surface (22) of the source material (20) at a preferred angle of 45 degrees for thermal evaporation and / or sublimation of the source material (20) below the plasma threshold, and the detector (40) for measuring the electromagnetic radiation (120) is positioned such that the electromagnetic radiation (120) reflected from the source surface (22) reaches the detector (40). Furthermore, the present invention relates to a detector (40) for measuring electromagnetic radiation (120), preferably suitable for the method according to the present invention, and also to a system (10) for thermal evaporation using electromagnetic radiation (120), preferably suitable for the method according to the present invention.

Description

[Technical Field]

[0001] The present invention relates to a method for controlling the flux distribution of evaporated source material in a system for thermal evaporation using electromagnetic radiation. The system includes an electromagnetic radiation source for providing electromagnetic radiation, a vacuum chamber containing a reaction atmosphere, and a detector for measuring the electromagnetic radiation. The source material and a target material to be coated are disposed within the vacuum chamber, and the radiation source is positioned such that the electromagnetic radiation is incident on a source surface of the source material at an angle of preferably 45 degrees for thermal evaporation and / or sublimation of the source material below the plasma threshold. The detector for measuring the electromagnetic radiation is positioned such that the electromagnetic radiation reflected from the source surface reaches the detector.

[0002] The present invention further relates to a detector for measuring electromagnetic radiation reflected from a source surface, the detector comprising a sensor element with an absorber, the absorber comprising an absorbing surface for at least partially absorbing the electromagnetic radiation, the sensor element further comprising a thermal sensing element for measuring the temperature of the absorber to detect absolute temperature and / or temperature changes induced in the absorber by the absorbed electromagnetic radiation.

[0003] The present invention further relates to a system for thermal evaporation using electromagnetic radiation. The system includes an electromagnetic radiation source for providing electromagnetic radiation, a vacuum chamber containing a reaction atmosphere, and a detector for measuring the electromagnetic radiation. A source material and a target material to be coated are disposed within the vacuum chamber, and the electromagnetic radiation source is positioned such that the electromagnetic radiation is incident on a source surface of the source material at a preferably 45-degree angle for thermal evaporation and / or sublimation of the source material below the plasma threshold. The detector for measuring the electromagnetic radiation is positioned such that the electromagnetic radiation reflected from the source surface reaches a primary detector. [Background technology]

[0004] The use of electromagnetic radiation, particularly laser light with wavelengths in the visible, infrared, or ultraviolet ranges, to vaporize source materials is widely known. Such laser vaporization systems allow for the deposition of thin material films at low pressure by heating the center of a block of source material from the front side with a continuous-wave laser. For example, silicon melts at the temperature required to achieve the desired flux of evaporated material, forming a molten pool inside a solid portion of the same source material. Thus, the solid silicon forms a crucible for liquid silicon, allowing for extremely high heating and cooling rates due to the absence of a thermal expansion mismatch between the source material and the crucible. At the same time, contamination of the source material with different crucible materials is avoided. Alternatively, a crucible made of a material different from the material to be evaporated can be used.

[0005] However, as the source material is depleted by the incident electromagnetic radiation, the shape of the source surface changes, e.g., the melt pool develops a concave morphology and / or deeper and deeper sublimation spots form within the source material. The shape of the source surface directly affects the flux distribution and evaporation rate of the evaporated material, which are inherently unstable.

[0006] In general, two main cases can be distinguished. In the case of locally concave sublimation or evaporation, a spot, i.e., a concave depression, is formed directly beneath the electromagnetic radiation. This occurs because the sublimation or evaporation rate is greatest at the center of this spot due to the radial intensity decay of the electromagnetic radiation within the beam and the temperature gradient from the intensity maximum. Outside the deepest point of this depression, the surface elements tilt inward toward the source symmetry axis, thus contributing more to the center of the flux distribution. This focusing of the flux distribution can be beneficial, especially when coating small samples at relatively large distances. However, once the source surface depression becomes too deep, evaporation or sublimation from its sidewall surface elements becomes too steep, and the flux distribution becomes defocused again. Furthermore, steep sidewalls can shadow part of the mole to be coated, resulting in large thickness nonuniformities.

[0007] The second main case is a locally convex sublimation or evaporation surface. In this case, surface elements away from the source's axis of symmetry are tilted outward, leading to a more diffuse flux distribution, which directs more material away from the sample than would be the case with a flat surface. Such a defocused flux distribution leads to a reduced growth rate on the target substrate, with a larger amount of sublimated or evaporated source material not hitting the target compared to a flat source surface.

[0008] Generally, a known approach to overcoming this problem is to move the electromagnetic radiation spot on the source material to provide a more uniformly distributed energy deposition and therefore a more uniform flux distribution of the evaporated source material. However, to achieve true active control of the flux distribution, it is necessary to reliably detect the surface curvature directly beneath the electromagnetic radiation spot. Direct observation of the source surface using a camera is hindered by the rapid coating of the window facing the source surface and, therefore, the evaporation or sublimation flux.

[0009] In view of the above, it is an object of the present invention to provide an improved method for controlling the flux distribution of evaporated source material, an improved detector for measuring electromagnetic radiation reflected from a source surface, and an improved system for thermal evaporation using electromagnetic radiation, which do not suffer from the above-mentioned drawbacks of the prior art. In particular, it is an object of the present invention to provide a method, a detector, and a system that allow for control of the flux distribution of evaporated source material in a system for thermal evaporation using electromagnetic radiation in a particularly easy and cost-effective manner. Preferably, the flux distribution can be adjusted for spatial variations in shape, size, and direction, especially in closed-loop control.

[0010] This object is met by the respective independent claims. In particular, this object is met by a method according to claim 1, a detector according to claim 11 and a system according to claim 29. The dependent claims describe preferred embodiments of the invention. Also, details and advantages stated with respect to the method according to the first aspect of the invention may also apply, possibly in a technical sense, to the detector according to the second aspect of the invention and to the system according to the third aspect of the invention, and vice versa. Summary of the Invention

[0011] According to a first aspect of the present invention, this object is met by a method for controlling the flux distribution of evaporated source material in a system for thermal evaporation using electromagnetic radiation. The system comprises an electromagnetic radiation source for providing electromagnetic radiation, a vacuum chamber containing a reaction atmosphere, and a detector for measuring the electromagnetic radiation. The source material and the target material to be coated are disposed within the vacuum chamber, the radiation source is positioned such that its electromagnetic radiation is incident on a source surface of the source material at an angle of preferably 45 degrees for thermal evaporation and / or sublimation of the source material below the plasma threshold, and the detector for measuring the electromagnetic radiation is positioned such that electromagnetic radiation reflected from the source surface reaches the detector.

[0012] The method according to the invention comprises the following steps:

[0013] a) defining a desired distribution of the flux of evaporated source material from a source surface and an incident distribution of electromagnetic radiation required for the desired distribution; b) determining an expected distribution of electromagnetic radiation reflected at the source surface based on the desired distribution of step a) and the incident distribution; c) providing, by an electromagnetic radiation source, electromagnetic radiation having the required incident distribution defined in step a); d) measuring, by a detector, the electromagnetic radiation reflected from the source surface; e) determining a measured distribution of electromagnetic radiation reflected at the source surface based on the measurement data of step d); f) determining the difference between the expected distribution determined in step b) and the measured distribution determined in step e); g) redetermining the required incident distribution of electromagnetic radiation provided by the electromagnetic radiation source so as to minimize the difference determined in step f); h) providing, by an electromagnetic radiation source, electromagnetic radiation having the required incident distribution redetermined in step g).

[0014] The method according to the present invention can be used in and by a system for thermal evaporation of a source material using electromagnetic radiation. Hereinafter, the term evaporation also includes any sublimation process, even if not explicitly mentioned. The evaporated source material can preferably be used to coat a target material, for example in the form of a thin film. The source material and the target material are placed in a vacuum chamber of the system. The vacuum chamber contains a reaction atmosphere suitable for the desired coating of the target material. For example, the reaction atmosphere can be provided as a vacuum or can contain the required reaction gases, such as oxygen and / or nitrogen.

[0015] For the evaporation process, an electromagnetic radiation source provides electromagnetic radiation that is directed into the vacuum chamber and incident on the source surface of the source material. The energy deposition of the electromagnetic radiation causes the source material to evaporate or sublimate. The energy deposition is selected so as not to reach the plasma threshold of the source material, thereby providing, among other things, purely thermal evaporation of the source material without forming a plasma. A preferred 45-degree angle of incidence avoids collisions between the path of the electromagnetic radiation within the vacuum chamber and other structures within the vacuum chamber, such as source and / or target holding elements.

[0016] Only a portion of the electromagnetic radiation incident on the source surface is absorbed by the source material and used in the evaporation process. The remaining portion of the electromagnetic radiation is reflected by the source surface. In other words, the absorbed and reflected portions of the electromagnetic radiation are directly related to each other. Specifically, for example, flat, concave, and convex portions of a surface reflect the incident electromagnetic radiation differently, so that the reflected portion of the electromagnetic radiation conveys information about the shape and morphology of the surface. This impresses the shape and morphology of the surface in the reflected electromagnetic radiation. Therefore, by detecting the electromagnetic radiation reflected by the source surface, the actual shape and morphology of the source surface can be inferred. To detect the reflected electromagnetic radiation, the method according to the present invention uses a detector appropriately positioned in the path of the reflected electromagnetic radiation within the vacuum chamber.

[0017] As described above, the actual shape and morphology of the source surface can be inferred from the measured reflected electromagnetic radiation. Therefore, the actual distribution of the flux of evaporated or sublimated source material can also be determined. Since the desired flux distribution is known, it can be determined how the incident electromagnetic radiation should be shaped to produce the desired flux distribution when incident on the actual, current source surface.

[0018] In the following, the individual steps of the method according to the invention will be described in detail.

[0019] In the first step a) of the method according to the invention, a desired distribution of the flux of the source material evaporated from the source surface is defined. In most cases, the desired flux distribution is such that a uniform coating of the target can be achieved. However, desired flux distributions other than those described above, particularly spatially dependent ones, are also possible in order to provide a coating with a position-dependent thickness on the target.

[0020] Furthermore, step a) also includes defining an incident distribution of electromagnetic radiation, which is defined so as to provide a desired distribution of the flux of evaporated source material. In addition to the desired flux distribution, the initial shape and morphology of the source surface, which is preferably flat and / or circular in most cases, can also be taken into account when defining the incident distribution of electromagnetic radiation.

[0021] The next step b) of the method according to the present invention is to determine an expected distribution of the electromagnetic radiation reflected from the source surface based on the results of step a). Specifically, the expected distribution is determined using the desired distribution and the incident distribution. As in step a), the initial shape and morphology of the source surface can also be taken into account when determining the expected distribution of the electromagnetic radiation.

[0022] In the next step c) of the method according to the invention, the electromagnetic radiation is provided with the required incident profile defined in step a) by an electromagnetic radiation source. The electromagnetic radiation source can be attached directly to the vacuum chamber. Alternatively, the electromagnetic radiation source can be positioned remotely from the vacuum chamber, possibly in a different room or building, and the electromagnetic radiation can be guided into the vacuum chamber by a suitable guide element, for example an optical fiber. As a result, the electromagnetic radiation is incident on the source surface of the source material with the required incident profile, causing the source material to thermally evaporate or sublimate below the plasma threshold.

[0023] At the same time, the part of the electromagnetic radiation that is not absorbed by the source material is reflected by the source surface. In a next step d) of the method according to the invention, this reflected electromagnetic radiation is measured by a detector of the system. For this purpose, the detector is suitably positioned in the vacuum chamber.

[0024] The measurement data acquired in step d) of the method according to the invention is analyzed in a next step e), in particular determining a measured distribution of electromagnetic radiation based on the measurement data of step d).

[0025] The information about the measured distribution obtained in step e) is used in a next step f) to determine the difference between the expected distribution determined in step b) and the measured distribution determined in step e). In other words, after performing step f), information is generated as to whether the expected distribution matches the actual measured distribution. The greater the discrepancy between these two distributions, the greater the difference between the actual flux distribution of the evaporated source material and the desired distribution defined in step a) according to the present invention.

[0026] Based on the result of step f), the next step g) of the method according to the invention is to redetermine the required incident distribution. In particular, the measured distribution and the difference between this measured distribution and the expected distribution provide information about the actual shape and morphology of the source surface. This then allows an improved determination of the required incident distribution of electromagnetic radiation so as to achieve the desired distribution of the flux of evaporated source material. This should automatically minimize the difference determined in step f).

[0027] In the final step h) of the method according to the invention, the electromagnetic radiation source provides electromagnetic radiation with the required incident distribution redetermined in step g), so that the electromagnetic radiation is incident on the source surface of the source material with the required incident distribution redetermined, causing the source material to thermally evaporate or sublimate below the plasma threshold. Taking into account the actual shape and morphology of the source surface, an improved match between the desired distribution and the actual current distribution of the evaporated source material flux is achieved.

[0028] In summary, the method according to the present invention described above allows for active adjustment of the flux distribution of evaporated or sublimated source material during operation of each evaporation system based on actual measurements, thus allowing control of the flux distribution, which can result in improved coating of the target material.

[0029] Furthermore, the method according to the present invention may include a time dependency of the desired distribution defined in step a). Time dependency in the present invention may apply, for example, to the spatial shape and / or orientation of the desired distribution. Alternatively or additionally, the intensity of the desired distribution may vary over time. As a result, the coating of the target can be controlled in a very unique way, including, for example, spatial thickness variations of the coating of the target material. Preferably, the desired distribution is time-dependent, so that the remaining steps of the method according to the present invention are adapted accordingly. That is, for example, the measuring, comparing, and redetermining in steps d), f), and g) are performed iteratively so that the required and expected distributions also include an adjusted time dependency and follow this time dependency.

[0030] Furthermore, the method according to the invention can be characterized in that the expected distribution in step b) is determined by calculating the expected distribution and / or by experimentally measuring the expected distribution and / or by empirically estimating the expected distribution. This list is not exclusive, and different methods of determining the expected distribution are applicable, especially when possible and in a technical sense. The calculation of the expected distribution is based on all available information, such as the desired and required distribution. The empirical estimation is based on general assumptions, such as the expected morphology and shape of the source surface. Preferably, a combination of calculation and estimation is used. Experimentally measuring the expected distribution can provide a very accurate expected distribution. The disadvantage of this method is the time and effort required for additional experimental measurements.

[0031] Preferably, the method according to the present invention may comprise repeatedly performing steps d) to h). The repetition rate may be constant, for example, 10 Hz or higher, up to continuous repetition of steps d) to h). An adapted repetition rate is also possible, whereby each repetition can be manually triggered, and / or when a system parameter, such as energy deposition in the detector due to electromagnetic radiation reflected from the source surface, exceeds or falls below a threshold. The repetition of steps d) to h) offers the possibility of ensuring the provision of a desired profile over a long period of time. In particular, the repetition allows for closed-loop control to provide a flux of evaporated or sublimated source material having a desired profile.

[0032] Furthermore, the method according to the present invention may include using light, particularly laser light having a wavelength of 100 nm to 1400 nm, as the electromagnetic radiation. Light, particularly laser light, is easy to provide and, in particular, can be easily directed into the vacuum chamber from a source remote from the vacuum chamber. In particular, light can be provided over a wide range of energy densities, thus facilitating the provision of electromagnetic radiation to vaporize below the plasma threshold of a particular source material.

[0033] According to another embodiment, the method according to the invention can be characterized in that in step e) and / or step f) the response function of the detector is taken into account. The response function of the detector has a direct influence on the measurement of the reflected electromagnetic radiation. For example, the solid angle covered by the detector limits the measured signal. Also, the dead time of the detector and, for example, the energy dependence of the detector sensitivity can influence the actual measurement. Therefore, by taking the response function into account in step e) and / or step f), the influence of the detector setup on the measured distribution can be taken into account at least partially, preferably completely.

[0034] Additionally or alternatively, the method according to the present invention may comprise, in step f), using the size and / or shape of the expected and measured distributions to determine the difference. As mentioned above, changes in the shape and / or morphology of the source surface affect the distribution of the reflected electromagnetic radiation. In particular, concave and convex portions of the source surface both reflect incident electromagnetic radiation differently, and in particular scatter the incoming electromagnetic radiation. This causes the shape and morphology of the surface to be reflected in the shape and morphology of the reflected electromagnetic radiation. Therefore, by detecting the size and / or shape of the electromagnetic radiation reflected at the source, information about the shape and morphology of the source surface reflected in the reflected electromagnetic radiation can be particularly easily detected.

[0035] Furthermore, the method according to the present invention can be characterized in that the electromagnetic radiation source includes two or more emitter sections, and in steps c) and h), each emitter section provides electromagnetic radiation incident on the source surface, and the system includes two or more detectors, each detector being arranged to measure the electromagnetic radiation provided by one of the emitter sections and reflected by the source surface. In other words, according to this embodiment, the source surface is illuminated by two separate beams of electromagnetic radiation, each beam being monitored by a separate dedicated detector. Each pair of emitter section and its assigned detector can implement the emission and measurement components of the method according to the present invention. In short, a more uniform distribution of electromagnetic radiation incident on the source surface can be provided, and active control of this distribution can be performed, as described above for an electromagnetic radiation source with a single emitter. This also improves the smoothness of the desired distribution that can be provided.

[0036] Furthermore, the method according to the present invention can be improved by providing two or more emitter sections with radially symmetric incidence on the source surface for the respective electromagnetic radiation provided by the emitter sections. In other words, the emitter sections are uniformly distributed around the source surface. As a result, if the incidence distributions of two or more emitter sections are equal, their combined incidence distribution will also be rotationally symmetric. In particular, this can prevent effects such as tilting and / or tilting of the molten source material in the direction of the incident electromagnetic radiation.

[0037] Yet another improved embodiment of the method according to the present invention can be characterized in that two or more emitter sections provide electromagnetic radiation with adjustable power density and / or shape and / or size. As already mentioned, in some cases it may be advantageous to provide a required distribution, including a spatial distribution, on the source surface. This can be easily achieved by providing two or more emitter sections, each emitting electromagnetic radiation and allowing the power density, shape, and / or size of the electromagnetic radiation to be individually varied. Briefly, this allows a desired distribution of the source material flux evaporated from the source material as a function of position on the source surface.

[0038] According to a second aspect of the invention, the object is met by a detector for measuring electromagnetic radiation reflected from a source surface, the detector comprising a sensor element with an absorber, the absorber comprising an absorbing surface for at least partially absorbing the electromagnetic radiation, the sensor element further comprising a thermal sensing element for measuring the temperature of the absorber to detect the absolute temperature and / or temperature change caused in the absorber by the absorbed electromagnetic radiation, the thermal sensing element comprising a temperature sensor, in particular a thermocouple element, arranged in a hole in the absorber, the hole terminating within the absorber, preferably close to the absorbing surface.

[0039] A detector according to the present invention can be used in a system for thermal evaporation using electromagnetic radiation. In particular, such a detector can be used to measure electromagnetic radiation, such as electromagnetic radiation reflected from a source surface of a source material.

[0040] The electromagnetic radiation to be measured is incident on the absorber, specifically on the absorbing surface, and is at least partially absorbed by the absorbing surface. In other words, at least a portion of the energy of the electromagnetic radiation is deposited in the absorber. Therefore, measuring and monitoring the temperature of the absorber makes it possible to determine the energy deposited in the absorber, and thereby the amount of electromagnetic radiation incident on the absorbing surface.

[0041] The absorbing surface faces at least partially toward the source surface, and is therefore coated with evaporated or sublimated source material, so that after a long enough deposition the detector has the same (and thus implied constant) absorptance and reflectance as the source.

[0042] The absorbing surface can be aligned, for example, perpendicular to the assumed incident direction of the electromagnetic radiation to be measured. Since only a portion of the incident electromagnetic radiation is absorbed, the remaining portion is reflected back in the same direction. In a system for thermal evaporation that uses a detector according to the present invention to measure electromagnetic radiation reflected from a source surface, the electromagnetic radiation reflected from such an absorbing surface can be directed back to the source surface and used twice for thermal evaporation.

[0043] However, a subsequent second reflection from the source surface can direct the electromagnetic radiation toward the electromagnetic radiation source, causing a disturbance. In one embodiment of an absorbing surface with two flat sections, these sections are adjacent to each other and positioned at an angle slightly less than 90 degrees, e.g., 89 degrees, to solve this problem. The electromagnetic radiation may still be reflected back toward the source surface, but not in exactly the same direction, and therefore will not strike the electromagnetic radiation source. Furthermore, when electromagnetic radiation incident on a two-element absorbing surface is reflected twice, the absorption of the incident electromagnetic radiation by the absorbing surface is also doubled. This can increase the energy deposition within the absorber, thereby improving the accuracy of the measurement.

[0044] In order to measure and / or monitor the amount of energy deposited into the absorber by the incident electromagnetic radiation, the absolute temperature and / or temperature changes of the absorber can be measured and / or monitored. In a detector according to the invention, this is done by using a temperature sensor located in a hole in the absorber close to the absorbing surface.

[0045] The hole allows a temperature sensor to be placed closer to the absorber surface, thus improving the accuracy of the temperature measurement. A temperature sensor inside the absorber allows direct measurement of the actual temperature of the absorber and / or changes in this temperature. Thus, the absolute value of the energy deposition caused by the electromagnetic radiation absorbed in the absorber can be determined. In particular, based on the measurement of the electromagnetic radiation reflected at the source surface, e.g., by a detector according to the invention, the match between the actual distribution of evaporated source material and the desired distribution of evaporated source material can be inferred and then controlled.

[0046] Preferably, a detector according to the present invention may include a detector that can be used in a method according to the first aspect of the invention, and therefore all the features and advantages detailed in relation to the method according to the first aspect of the invention may also be provided by a detector according to the second aspect of the invention used to carry out the method according to the first aspect of the invention.

[0047] Furthermore, a detector according to the present invention can be characterized in that the absorbing surface absorbs light, in particular laser light with a wavelength of 100 nm to 1400 nm. As described above with respect to the method according to the first aspect of the present invention, light, in particular laser light, is suitable for evaporation and / or sublimation of a wide range of source materials that may be used. By providing an absorbing surface capable of absorbing light, a detector according to the present invention can be adapted to this particular electromagnetic radiation. Adaptation can include, for example, selecting an appropriate material for the absorber on which the absorbing surface is disposed. Additionally or alternatively, adaptively selected coatings of the absorbing surface can also be used to increase light absorption.

[0048] According to another embodiment of the detector according to the present invention, the absorber includes a cooling system for active cooling of the absorber, the cooling system including at least one cooling duct within the absorber through which a coolant, preferably water, flows. The cooling duct of the cooling system passes through the absorber, allowing the coolant to flow within the absorber. The coolant may be a fluid, and water is preferably used as the coolant. By flowing through the absorber, the coolant cools the absorber. Preferably, the cooling system maintains the absorber at a constant temperature. Thus, the absorber does not change temperature, thereby maintaining its detection capability for incident electromagnetic radiation. Furthermore, the coolant flowing through the cooling duct within the absorber preferably absorbs energy deposited in the absorber by the incident electromagnetic radiation. Therefore, the temperature of the coolant changes depending on the amount of absorbed energy.

[0049] Therefore, the detector according to the present invention can be further improved by including a flow sensor for measuring the flow of the coolant through the cooling duct in the absorber and a temperature sensor for measuring the absolute temperature and / or temperature change of the coolant induced by flowing through the cooling duct in the absorber. To measure the temperature and / or temperature change of the coolant, and thereby the temperature and / or temperature change of the absorber, the detector element according to the present invention comprises two different types of sensors: a flow sensor and a temperature sensor. In particular, the flow sensor measures the flow rate of the coolant flowing through the cooling duct. The temperature sensor measures the temperature of the coolant. In particular, the temperature of the coolant is measured at least at the outlet of the cooling duct, and preferably also at the inlet of the cooling duct. Assuming that the coolant is provided to the inlet at a constant temperature, the outlet temperature allows for the detection of temperature changes over time. Furthermore, measuring the inlet temperature of the coolant can enhance this measurement of the relative temperature change. In particular, by combining the temperature measurement with the above-mentioned flow measurement, the absolute value of the energy deposition caused by the electromagnetic radiation absorbed in the absorber can be determined.

[0050] This additionally measured temperature value can be used to check the measurements of the temperature sensor placed in the hole and / or to improve the overall accuracy of the temperature measurement. Furthermore, if the temperature measurement based on the temperature sensor in the hole fails or is completely lost, it is still possible to measure the temperature of the absorber and therefore the energy deposited in the absorber by the electromagnetic radiation.

[0051] Furthermore, the detector according to the present invention may preferably include an absorber that includes, and in particular consists of, a metal, such as copper or aluminum. Using a metal as the absorber material offers several advantages. First, metals, especially copper or aluminum, have high thermal conductivity. The detector according to the present invention is designed as a bolometer. A bolometer includes a sensor element that absorbs incident electromagnetic radiation and measures the temperature and / or temperature changes resulting from this absorption. Materials with high thermal conductivity are particularly suitable for such bolometers. Furthermore, metals are suitable for use under ultra-high vacuum conditions. Therefore, contamination of such ultra-high vacuum as a reaction atmosphere by the detector according to the present invention and vice versa can be avoided.

[0052] According to yet another preferred embodiment of the detector according to the present invention, the absorber surrounds a hollow absorbing volume at one end, the inner sidewall of which forms an absorbing surface, and the absorbing volume includes an absorbing orifice, which can be aligned with the expected and / or determined direction of incidence of the electromagnetic radiation to be measured. As mentioned above, in most cases, the absorbing surface absorbs only a portion of the incident electromagnetic radiation, at least that which is directly incident on the detector. In this preferred embodiment of the detector according to the present invention, the absorbing surface is provided as the inner sidewall of the hollow absorbing volume. The electromagnetic radiation incident on the detector enters the absorbing volume through the absorbing orifice. Within the absorbing volume, the electromagnetic radiation is incident on the absorbing surface and is partially absorbed and partially reflected. This reflection occurs within an absorbing volume that is preferably large relative to the absorbing orifice, so that the reflected electromagnetic radiation is likely to miss the absorbing orifice and strike another section of the inner sidewall of the absorbing volume, i.e., the absorbing surface, again. In an ideal case, this procedure is repeated until the incident electromagnetic radiation is completely or at least substantially completely absorbed by the absorber. In this case, the energy deposition in the absorber represents the total energy of the incident electromagnetic radiation, which, among other things, makes coating the absorbing surface with evaporated source material ineffective.

[0053] Yet another improved embodiment of the detector according to the present invention may include a configuration in which the absorbing surface is partially conical within the absorbing volume, with the cone of the conical absorbing surface facing the absorbing orifice. The cone can be shaped both as a protrusion and as a depression. In the protrusion embodiment, the tip of the cone faces the absorbing orifice, while in the depression embodiment, the base of the cone faces the absorbing orifice. In other words, incident electromagnetic radiation that crosses the absorbing orifice first strikes the cone-shaped portion of the absorbing surface. Because the cone faces the absorbing orifice, electromagnetic radiation reflected by the side of the cone is directed somewhere within the absorbing volume and definitely does not hit the absorbing orifice. Therefore, the above-mentioned ideal case in which incident electromagnetic radiation is completely absorbed within the absorbing volume can be more easily achieved.

[0054] Furthermore, the detector according to the invention can be improved in that the part of the absorbing volume that forms the edge of the absorbing orifice is inclined inwards relative to the absorbing volume. Similar to the aforementioned cone facing the absorbing orifice, the inwardly inclined edge around the absorbing orifice also serves to ensure that the electromagnetic radiation is reflected into the absorbing volume. This therefore makes it easier to achieve the above-mentioned ideal case of complete absorption of the incident electromagnetic radiation in the absorbing volume also in this embodiment of the detector according to the invention.

[0055] Preferably, a detector according to the invention includes both a conical section facing the absorption orifice and a beveled edge surrounding the absorption orifice.

[0056] Another embodiment of a detector according to the present invention can be characterized in that the detector includes an aperture having an aperture opening, the aperture being arranged upstream relative to the sensor element along the assumed and / or determined direction of incidence of the electromagnetic radiation to be measured. Such an aperture can help define a solid angle that can be investigated by the detector according to the present invention. To improve the definition of the solid angle, two or more apertures aligned upstream along the assumed and / or determined direction of incidence can also be used. Preferably, the aperture is sized and arranged so that, for example, a source surface illuminated by the electromagnetic radiation source is visible from the detector's perspective, thus allowing electromagnetic radiation reflected from the source surface to reach the detector. Furthermore, electromagnetic radiation emanating from other locations within the vacuum chamber is blocked by the aperture, thereby improving the overall accuracy of measurements by the detector according to the present invention.

[0057] According to yet another improved embodiment of the detector according to the invention, the size of the aperture opening is adapted to the absorber, in particular the absorbing orifice, so that electromagnetic radiation passing through the aperture opening is incident on the absorbing surface of the absorber, in particular through the absorbing orifice. In this embodiment, the aforementioned field of view restriction of the detector is further improved. Since the aperture opening and the absorber, in particular the absorbing orifice, are constructed to be adapted to each other, all electromagnetic radiation entering through the aperture orifice can be reliably registered by the detector. This makes it possible to avoid or at least minimize loss of information.

[0058] Multiple successive apertures may be used to further constrain and optimize the field of view, which is particularly useful when, for example, sources are placed close to each other and measurements need to be made at long distances from the sources.

[0059] Furthermore, the detector according to the invention can be improved by the fact that the detector includes a shielding element that extends between the aperture and the absorber along the expected direction of incidence of the electromagnetic radiation to be measured. The shielding element, together with the aperture, forms a volume in front of the detector that is accessible only to electromagnetic radiation that enters through the aperture orifice. Scattered electromagnetic radiation that is completely outside the aperture but strikes the absorber is blocked by the shielding element. This allows the field of view of the detector to be defined with increased precision.

[0060] Furthermore, in another improved embodiment of the detector according to the invention, the shielding element extends further along the absorber along the assumed direction of incidence of the electromagnetic radiation. Electromagnetic radiation incident on the absorber at a distance from the absorbing surface may still deposit energy in the absorber and distort the results measured by the detector. The shielding element extending further along the absorber covers the absorber and blocks all incoming electromagnetic radiation. This makes it possible to avoid, or at least minimize, distortions in the detector measurements.

[0061] In another preferred embodiment, a detector according to the present invention can be characterized in that the detector includes two or more sensor elements, which are adjacent to and thermally separated from each other. As mentioned above, the spatial shape of the source surface can change during evaporation. In particular, the source surface can become convex or concave. This spatial shape of the source surface affects the detector's measurement results because some of the reflected electromagnetic radiation simply misses the main detector and / or other portions are focused toward the detector. By providing a detector with two or more sensor elements, a more precise measurement of the reflected electromagnetic radiation distribution can be obtained. In particular, changes in the spatial shape and / or morphology of the source surface can be detected because they result in detectable differences in the reflected electromagnetic radiation distribution measured by the two or more sensor elements. By providing these two or more thermally separated sensor elements, independent measurements can be performed for each sensor element. Positioning the sensor elements adjacent to each other ensures that gaps between the sensor elements, through which reflected electromagnetic radiation can escape from the detector, are minimized.

[0062] Furthermore, the detector according to the present invention can be improved by arranging two or more sensor elements in a rotationally symmetrical pattern, a column, or a matrix in a plane perpendicular or at least substantially perpendicular to the assumed and / or determined direction of incidence of the electromagnetic radiation to be measured. Different patterns allow the detector to be adapted to different measurement purposes. For example, a rotationally symmetrical pattern makes it possible to identify focusing problems with the electromagnetic radiation provided by the electromagnetic radiation source. A row arrangement is particularly useful for detecting misalignments between this electromagnetic radiation and the source surface. A matrix allows for a more detailed measurement of the distribution of the electromagnetic radiation reflected at the source surface, especially when multiple sensor elements are used.

[0063] A further improved embodiment of the detector according to the invention is characterized in that in a plane perpendicular or at least substantially perpendicular to the assumed and / or determined direction of incidence of the electromagnetic radiation to be measured, two or more sensor elements: Rectangle, square, circle, ring, part of ring The shape may include one of the following:

[0064] This list is not exhaustive and can be extended with other suitable shapes. In particular, in the above-mentioned arrangement patterns of two or more sensor elements, the shape of each sensor element, adaptively selected for the current pattern being applied, allows a compact and continuous arrangement of each sensor element without unavoidable gaps between the separate sensor elements.

[0065] Furthermore, the detector according to the invention can be characterized in that it includes a placement element for placing the absorber in the vacuum feedthrough. This particularly preferred embodiment of the detector according to the invention allows the detector to be placed directly in and / or on the vacuum feedthrough of the vacuum chamber. All connections, including, for example, the inlet and outlet ports of the cooling channels and the electrical connections of the sensor element, are accessible from the outside of the vacuum chamber. Essentially, only the absorber is placed in the vacuum chamber, along with any apertures and / or shielding elements present. These elements can be provided in an embodiment that allows for ultra-high vacuum. Mutual damage between the detector components and the reaction atmosphere in the vacuum chamber can thus be avoided.

[0066] According to yet another improved embodiment of the detector according to the invention, the positioning element comprises a positioning element for changing the position of the absorber relative to the vacuum feedthrough. The possibility of changing the position of the absorber in the vacuum chamber can be used, for example, when exchanging source and / or target materials, thereby avoiding interference of the detector, and in particular of the absorber, with such procedures. In particular, after completion of the procedures, the absorber can be repositioned near the source element to enhance the measurement capabilities of the detector according to the invention by increasing the covered solid angle.

[0067] According to a third aspect of the present invention, the object is met by a system for thermal evaporation using electromagnetic radiation. The system comprises an electromagnetic radiation source for providing electromagnetic radiation, a vacuum chamber containing a reaction atmosphere, and a primary detector for measuring the electromagnetic radiation. A source material and a target material to be coated are disposed within the vacuum chamber. The radiation source is arranged so that its electromagnetic radiation is incident on a source surface of the source material at an angle of preferably 45 degrees for thermal evaporation and / or sublimation of the source material below the plasma threshold. The primary detector for measuring the electromagnetic radiation is arranged so that electromagnetic radiation reflected from the source surface reaches the primary detector. The system according to the third aspect of the present invention is adapted to perform the method according to the first aspect of the present invention. Accordingly, all the features and advantages described in relation to the method according to the first aspect of the present invention can also be provided by a system according to the third aspect of the present invention adapted to perform the method according to the first aspect of the present invention.

[0068] Preferably, the system according to the invention may be improved in that at least the main detector, and preferably all detectors for electromagnetic radiation, are constructed in accordance with the second aspect of the invention. In this particular embodiment, all the features and advantages detailed in relation to the detector according to the second aspect of the invention may also be provided by a system according to the third aspect of the invention comprising at least one detector according to the second aspect of the invention.

[0069] The invention will be further explained below with reference to exemplary embodiments shown in the accompanying drawings. [Brief explanation of the drawings]

[0070] [Figure 1] 1 is a system according to the present invention. [Figure 2] 1 is a first possible embodiment of a detector according to the invention; [Figure 3] It is an absorbent body with an absorption volume. [Figure 4] 1 is an embodiment of a detector according to the invention, comprising two sensor elements; [Figure 5] 1 is an arrangement pattern of sensor elements. [Figure 6] It is the flux of source material evaporated from the flat source surface. [Figure 7] It is the flux of source material evaporated from the concave source surface. [Figure 8] It is the flux of source material evaporated from the convex source surface. [Figure 9] A tilt of the molten droplet of source material. [Figure 10] The behavior of molten droplets under two incident electromagnetic radiations. [Figure 11] A possible arrangement of three radiation emitters. [Figure 12] The target is swept by adjusting two incident electromagnetic radiation beams. DETAILED DESCRIPTION OF THE INVENTION

[0071] 1 shows the main components of a system 10 for thermal evaporation of a source material 20 using electromagnetic radiation 120 in accordance with the present invention. The source material 20 is disposed within a vacuum chamber 12, which contains a reaction atmosphere 16. The vacuum chamber 12 itself is simply shown next to a vacuum feedthrough 14. Located on one side of the vacuum feedthrough 14 is an electromagnetic radiation source 110, and on the other side is a detector 40 in accordance with the present invention.

[0072] During operation of system 10, electromagnetic radiation source 110 provides electromagnetic radiation 120 that is directed toward and incident on source surface 22 of source material 20. Source material 20 absorbs a portion of electromagnetic radiation 120, causing a portion of source material 20 to evaporate or sublimate, as indicated by the dashed circle in FIG. 1. Target material 18 is positioned opposite source material 20. Vaporized source material 20 reaches target material 18 and forms a coating on the surface of target material 18.

[0073] The remaining portion of the electromagnetic radiation 120 is reflected by the source surface 20. Because the emission direction of the electromagnetic radiation source 110 and the location and general orientation of the source surface 22 are known, the detector 40 can be positioned in an assumed and / or determined direction of incidence 122 of the reflected electromagnetic radiation 120. Similar to what was described above for the electromagnetic radiation source 110, the detector, and specifically its absorber 52, can be positioned in the vacuum feedthrough 14 of the vacuum chamber 12.

[0074] Detector 40 according to the present invention functions as a bolometer. Electromagnetic radiation 120 is incident on absorbing surface 60 of absorber 52 and is at least partially absorbed. As shown, absorbing surface 60 faces source surface 22 and is therefore coated with evaporated source material 20 as shown in FIG. 1. Thus, after a short accumulation time, absorbing surface 60 contains absorption and reflection properties that are identical to, or at least similar to, source surface 22.

[0075] The aforementioned energy deposition within the absorber 52 results in a temperature change, or at least an increased cooling requirement, of the absorber 52. By measuring the temperature or changing behavior, the evaporation rate and / or flux distribution of the source material 20 evaporated or sublimated by the incident electromagnetic radiation 120 can be determined.

[0076] FIG. 2 shows a cross section of a possible embodiment of a detector 40 according to the present invention. The detector 40 includes a single sensor element 50 with an absorber 52, preferably made of a highly thermally conductive metal such as copper or aluminum. The positioning element 40 allows the absorber 52 to be positioned in the vacuum feedthrough 14 of the vacuum chamber 12 of the system 10 according to the present invention. Specifically, the positioning element 42 includes a positioning element 44 for changing the actual position of the absorber 52 within the reaction atmosphere 16 of the vacuum chamber 12. Thus, other elements of the system 10, such as the source material 20 (see FIG. 1), located within the vacuum chamber 12, can be moved without being hindered by the detector 40.

[0077] The detector 40 according to the invention is based on the bolometer principle: electromagnetic radiation 120 is incident on the absorbing surface 60 of the absorber 52 and is at least partially absorbed. This energy deposition can be measured by measuring the absolute temperature or temperature change of the absorber 52.

[0078] Thus, the illustrated detector 40 according to the present invention implements two different measurement methods and respective sensing elements 70. Each method can be used separately to measure temperature or temperature changes. However, improved accuracy can be achieved by combining the two methods described below.

[0079] In the first method, a temperature sensor 74, preferably a thermocouple element 76, is placed within the hole 54 of the absorber 52, particularly near the absorbing surface 60. As mentioned above, energy deposited by electromagnetic radiation 120 incident on the absorbing surface 60 causes a temperature rise in the absorber 52. A thermocouple 76 positioned within the absorber 52 near the absorbing surface 60 can measure this as an absolute temperature or as a temperature change. This measurement method therefore also allows for the amount of energy deposited within the absorber 52 to be precisely determined.

[0080] In the second method, the absorber 52 includes a cooling system 80 for active cooling. A coolant 84 flows through cooling ducts 82 within the absorber 52, capturing energy deposited within the absorber 80 by incident electromagnetic radiation 120. As shown in Figure 2, flow sensors 72 measure the flow rate of the coolant 84 and temperature sensors 74 measure the temperature of the coolant 84 at both the inlet and outlet of the cooling ducts 82. Briefly, by combining these measurements, it is possible to precisely determine the amount of energy deposited within the absorber 52.

[0081] FIG. 3 shows a cross section of a rotationally symmetric preferred embodiment of a detector 40 according to the present invention, in particular its absorbing surface 60. According to this embodiment, the absorber 52 of the illustrated sensor element 50 includes a hollow absorbing volume 56 at its end facing the incident direction 122 of the electromagnetic radiation 120 to be measured. This absorbing volume 56 includes a single opening, or absorbing orifice 62, that allows the incident electromagnetic radiation 120 to enter the absorbing volume 56. The inner sidewall 58 of the absorbing volume 56 forms the absorbing surface 60. That is, the electromagnetic radiation 120 enters the absorbing volume 120 and is reflected multiple times within the absorbing volume 56, as indicated by the arrows in FIG. 3, with each reflection absorbing a portion of the energy of the incident electromagnetic radiation 120. Ideally, the electromagnetic radiation 120 is trapped within the absorbing volume 56 and is thus completely absorbed by the absorbing surface 60. To increase the likelihood of this ideal case, the sidewall portion that forms the edge 64 surrounding the absorbing orifice 62 is inclined inwardly relative to the absorbing volume 56. The inwardly sloping surfaces provide the additional benefit of preventing electromagnetic radiation incident on these surfaces from being reflected back in the direction of incidence. Furthermore, the portion of the absorbing surface 60 positioned opposite the absorbing orifice 62 is conical in shape, with the tip of the cone pointing towards the absorbing orifice 62.

[0082] 4 shows a detector 40 with two sensor elements 50. The sensor elements 50 are positioned adjacent to and thermally isolated from one another. Each sensor element 50 includes a respective absorber 52 and absorbing surface 60. The remainder of the sensor elements 50 are not shown. Briefly, providing more than one sensor element 50 can provide more detailed information about the absorbed electromagnetic radiation 120, for example, to determine the evaporation rate and / or flux distribution of the evaporated source material 20 (not shown).

[0083] Furthermore, two overlapping and aligned apertures 90 are arranged upstream of each sensor element 50. Aperture openings 92 limit the solid angle of acceptance of each sensor element 50. Crosstalk between the sensor elements 50, indicated by dashed lines, can be avoided. Furthermore, shielding elements 94 are arranged between the apertures 90 and the absorber 52 and along each aperture body 52. ​​On the one hand, these shielding elements 94 further reduce the above-mentioned crosstalk. On the other hand, they block electromagnetic radiation 120 incident on the side of the absorber 52, making it impossible for it to distort the measurement results.

[0084] As discussed with respect to Figure 4, a detector 40 according to the present invention can include two or more sensor elements 50. Figure 5 shows some example shapes and arrangement patterns of the sensor elements 50 and their absorbing surfaces 60. Obviously, other arrangements are possible, one limitation being a high-resolution pixel array similar to that of an electronic camera. Briefly, in relation to the measurement purpose of the detector 40, for example, to determine the evaporation rate and / or flux distribution of the evaporated source material 20, the most appropriate of various arrangement patterns can be selected.

[0085] At the top left of Figure 5, a standard geometry is shown with a simple circular active area.

[0086] In the four quadrants shown at the top right, movement in the incident direction 122 of electromagnetic radiation 120 can be detected, where the sensor elements 50 are rectangularly shaped and arranged to detect horizontal and vertical movement primarily along their diagonals, while keeping the number of sensor elements 50 small.

[0087] 5, a third arrangement is shown with sensor elements 50 forming a rotationally symmetric pattern of circular rings. This pattern is most sensitive to focusing or defocusing of the electromagnetic radiation 120 provided by the electromagnetic radiation source 110.

[0088] A stripe arrangement of rectangular sensor elements 50, such as that shown in the lower right-hand portion of Figure 5, can detect both position and defocus, although in this case only in the vertical direction. This arrangement can be beneficial because electromagnetic radiation 120 reflected from the source surface 22 at an incidence direction 122 of approximately 45 degrees will be affected more in the plane containing the incident and reflected beams than at right angles.

[0089] The following three figures, Figures 6, 7, and 8, illustrate the effect of the shape and morphology of the source surface 22 of the source material on both the flux distribution 30 of the evaporated source material 20 and the distribution of the electromagnetic radiation 120 reflected from the source surface 22 in the measured distribution 134 on the detector 40. Figures 6, 7, and 8 will be discussed together below to highlight the differences between these figures. Furthermore, a method according to the present invention will be described.

[0090] Electromagnetic radiation source 110 provides electromagnetic radiation 120 having an incident distribution 130. Providing this electromagnetic radiation 120 is performed in step c) of the method according to the invention. According to step a), incident distribution 130 is defined such that a flux distribution 30 of evaporated source material 20 from source surface 22 corresponds to the desired distribution 32 defined in step a) of evaporated and / or sublimated source material 20. This condition can be easily met, particularly in the situation shown in FIG. 6 with a flat source surface 22. A target material 18, positioned opposite source material 20 in reaction atmosphere 16, can be predictably coated with evaporated source material 20.

[0091] To enable control of this coating process, detector 40 is arranged to measure the electromagnetic radiation 120 reflected by source surface 22 in incident direction 122, in particular in step d) of the method according to the invention. Detector 40 thereby provides a measured distribution 134 of measured electromagnetic radiation 120, preferably taking into account the response function of detector 40. This measured distribution 134 can be used to detect deviations from the assumed ideal case, since any changes in the morphology and / or shape of source surface 22 will be reflected in reflected electromagnetic radiation 120.

[0092] For this reason, in a second step b) of the method according to the invention, an expected distribution 132 of the reflected electromagnetic radiation 120 is determined, which may for example be calculated, empirically estimated or experimentally determined. In step f) of the method according to the invention, the measured distribution 134 of the electromagnetic radiation 120 reflected by the source surface 22 is compared with the expected distribution 132, so that the difference between these two distributions 132, 134 can be determined.

[0093] Based on the differences determined in step f) of the method according to the invention, step g) comprises redetermining the incident distribution 130 in order to eliminate these differences. Finally, in a final step h), the electromagnetic radiation source 110 provides electromagnetic radiation 120, e.g. laser light with a wavelength between 100 nm and 1400 nm, with the newly redetermined incident distribution 130. This allows for actual control of the flux distribution 30 of the evaporated source material 20.

[0094] In particular, at least steps d) to h) of the method according to the invention can be repeatedly performed to provide an active closed-loop control of evaporation. Alternatively or additionally, in step a), the desired distribution 32 can already be defined in terms of its time dependence.

[0095] As mentioned above, Figure 6 shows a source material 20 with a flat source surface 22. This is an ideal case and is easy to calculate: the actual flux distribution 30 is equal to the desired distribution 32.

[0096] After some irradiation by electromagnetic radiation 120, the source surface 22 may develop concave portions due to, for example, actual evaporation of the source material 20. This causes both the flux distribution 30 and the reflected electromagnetic radiation distribution, respectively, to change. The flux distribution 30 is no longer equal to the desired distribution 32 (not shown). This situation is identified by comparing a newly measured distribution 134 with the expected distribution 132 and resolved by redetermining the incident distribution 130 accordingly.

[0097] Figure 8 shows a similar situation to Figure 7. The only difference is that the shape of the source surface 22 is convex instead of concave. All descriptions regarding the distributions 30, 130, 132, 143 and the solutions presented above are the same as those described and mentioned with respect to Figure 7.

[0098] 9 illustrates the particular behavior of a particular source material 20. The illustrated source material 20 is provided as a free-standing rod, with a source surface 22 located at the top end of the rod. Illuminating the source surface 22 with incident electromagnetic radiation 120 results in the formation of droplets of molten source material 20 at this top end of the rod of source material 20. Because the electromagnetic radiation 120 is incident at an angle of, for example, 45 degrees, the side of the rod closer to the electromagnetic radiation 120 absorbs more energy. This therefore results in the droplets of molten source material 20 tilting and / or tilting toward the electromagnetic radiation 120. Notably, the flux distribution 30 also follows this spatial orientation.

[0099] 10 shows a possible solution to this problem. In accordance with the method of the present invention, a second beam of electromagnetic radiation 120 can be used to balance the energy deposition in the source material 20. The flux distribution 30 is not distorted and is again equal to the desired distribution 32.

[0100] The number of beams of electromagnetic radiation 120 is not limited to two. FIG. 11 shows an embodiment of a system 10 according to the invention, in which an electromagnetic radiation source 110 comprises three emitter sections 112. The emitter sections 112 are arranged rotationally symmetrically around the source surface 22 of the source material 20. A dedicated detector 40 is provided for each beam of electromagnetic radiation 120. Thus, the above-described method according to the invention can be performed with each pair of emitter section 112 and detector 40 individually. In particular, the emitter sections 112 can provide electromagnetic radiation 120 with adjustable power density and / or shape and / or size. Thus, the actual incident distribution 130, and thus the flux distribution 30, and the desired distribution 32, can be subject to spatial variations at the source surface 22.

[0101] This situation is illustrated in FIG. 12 . Two incident beams of electromagnetic radiation 120 are shown, with different incident distributions 130, as suggested by the different thicknesses of the illustrated arrows. This difference is caused, for example, by different power densities of the provided beams of electromagnetic radiation 120, resulting in a slight distortion of the flux 30 of the source material 20 evaporated from the source surface 22. In this case, this is intentional; the flux distribution 30 is equal to the desired distribution 32. It is clearly visible that the target material 18 is not evenly coated by this flux distribution 30, because the flux distribution 30 is directed to one side of the target material 18. By varying the individual incident distributions 130 of the beams of electromagnetic radiation 120, the direction of the flux distribution 30 can be changed. As a result, a desired deposition thickness or thickness variation on the target material 18, or a time-dependent sweep of the desired distribution 32, can be achieved and tracked by the actual flux distribution 30. [Explanation of symbols]

[0102] 10 Systems 12 Vacuum chamber 14 Vacuum Feedthrough 16 Reaction atmosphere 18 Target Materials 20 Sauce Ingredients 22 Sauce surface 30 Flux Distribution 32 Desired Distribution 40 detectors 42 Placement Elements 44 Positioning Elements 50 sensor elements 52 Absorbent 54 holes 56 Absorption Volume 58 Side wall 60 Absorbent Surface 62 Absorption orifice 64 En 70 Heat Sensing Element 72 Flow sensor 74 Temperature Sensor 76 Thermocouple Elements 80 Cooling System 82 Cooling duct 84 Coolant 90 aperture 92 Aperture opening 94 Shielding Elements 110 Electromagnetic radiation sources 112 Emitter Section 120 Electromagnetic Radiation 122 Incident direction 130 Incident distribution 132 Expected Distribution 134 Measurement distribution

Claims

1. 1. A method for controlling the flux distribution (30) of evaporated source material (20) in a system (10) for thermal evaporation using electromagnetic radiation (120), comprising: The system (10) comprises an electromagnetic radiation source (110) for providing electromagnetic radiation (120), a vacuum chamber (12) containing a reaction atmosphere (16), and a detector (40) for measuring the electromagnetic radiation (120); A source material (20) and a target material (18) to be coated are disposed within the vacuum chamber (12); the electromagnetic radiation source (110) is positioned such that its electromagnetic radiation (120) is incident on a source surface (22) of the source material (20) at an angle of preferably 45 degrees for thermal evaporation and / or sublimation of the source material (20) below a plasma threshold; The detector (40) for measuring electromagnetic radiation (120) is positioned so that the electromagnetic radiation (120) reflected from the source surface (22) reaches the detector (40); The method comprises: a) defining a desired distribution (32) of the flux of evaporated source material (20) from the source surface (22) and an incident distribution (130) of electromagnetic radiation (120) required for said desired distribution (32); b) determining an expected distribution (132) of electromagnetic radiation (120) reflected from the source surface (22) based on the desired distribution (32) of step a) and the incident distribution (130); c) providing, by said electromagnetic radiation source (110), electromagnetic radiation (120) having said required incident distribution (130) defined in step a); d) measuring, by said detector (40), the electromagnetic radiation (120) reflected from said source surface (22); e) determining a measured distribution (134) of electromagnetic radiation (120) reflected from the source surface (22) based on the electromagnetic radiation (120) measured in step d); f) determining the difference between the expected distribution (132) determined in step b) and the measured distribution (134) determined in step e); g) redetermining the required incident distribution (130) of electromagnetic radiation (120) provided by the electromagnetic radiation source (110) so as to minimize the difference determined in step f); h) providing, by said electromagnetic radiation source (110), electromagnetic radiation (120) having said required incident distribution (130) redetermined in step g); A method comprising:

2. The method of claim 1 , wherein the desired distribution (32) defined in step a) includes a time dependency.

3. 3. The method of claim 1, wherein the expected distribution (132) in step b) is determined by calculating the expected distribution (132) and / or by experimentally measuring the expected distribution (132) and / or by empirically estimating the expected distribution (132).

4. 4. The method according to claim 1, wherein steps d) to h) are carried out iteratively.

5. 5. The method according to claim 1, wherein light, in particular laser light with a wavelength between 100 nm and 1400 nm, is used as the electromagnetic radiation (120).

6. The method according to any one of the preceding claims, wherein in step e) and / or step f) the response function of the detector (40) is taken into account.

7. The method according to any one of the preceding claims, wherein in step f) the size and / or shape of the expected distribution (132) and the measured distribution (134) are used to determine the difference.

8. The electromagnetic radiation source (110) includes two or more emitter sections (112); In steps c) and h), each emitter section (112) provides electromagnetic radiation (120) incident on said source surface (22); The system (10) includes two or more detectors (40); 8. The method of claim 1, wherein each detector (40) is arranged to measure electromagnetic radiation (120) provided by one of the emitter sections (112) and reflected by the source surface (22).

9. 9. The method of claim 8, wherein the electromagnetic radiation (120) provided by each of the two or more emitter sections (112) is incident radially symmetrically on the source surface (22).

10. 10. The method of claim 8 or 9, wherein the two or more emitter sections (112) provide electromagnetic radiation (120) with adjustable power density and / or shape and / or size.

11. A detector (40) usable in the method of any one of claims 1 to 10 for measuring electromagnetic radiation (120) reflected from a source surface (22), comprising: a sensor element (50) having an absorber (52); the absorber (52) includes an absorbing surface (60) for at least partially absorbing the electromagnetic radiation (120); the sensor element (50) further comprises a thermal sensing element (70) for measuring the temperature of the absorber (52) to detect absolute temperature and / or temperature changes induced in the absorber (52) by the absorbed electromagnetic radiation (120); The thermal sensing element (70) comprises a temperature sensor (74), in particular a thermocouple element (76), disposed in a hole (54) in the absorber (52); The hole (54) terminates within the absorber (52), preferably near the absorbing surface (60).

12. Detector (40) according to claim 11, wherein the absorbing surface (60) absorbs light, in particular laser light with wavelengths between 100 nm and 1400 nm.

13. The absorber (52) includes a cooling system (80) for active cooling of the absorber (52), 13. The detector (40) of claim 11 or 12, wherein the cooling system (80) comprises at least one cooling duct in the absorber (52) for a coolant (84), preferably water, to flow within the absorber (52).

14. 14. The detector (40) of claim 13, wherein the thermal sensing element (70) comprises a flow sensor (72) for measuring the flow of the coolant (84) through the cooling ducts in the absorber (52), and a temperature sensor (74) for measuring the absolute temperature of the coolant (84) and / or a temperature change of the coolant (84) induced by flowing through the cooling ducts in the absorber (52).

15. Detector (40) according to any one of claims 11 to 14, wherein the absorber (52) comprises, in particular consists of, a metal, in particular copper or aluminium.

16. The absorbent body (52) encloses at one end a hollow absorbent volume (56); the interior sidewall (58) of the absorbent volume (56) forms the absorbent surface (60); The absorption volume (56) includes an absorption orifice (62); A detector (40) according to any one of claims 11 to 15, wherein the absorbing orifice (62) can be aligned with an assumed and / or determined direction of incidence (122) of the electromagnetic radiation (120) to be measured.

17. the absorbent surface (60) is partly conical in shape within the absorbent volume (56); 17. The detector (40) of claim 16, wherein the cone of the conically shaped absorbing surface (60) faces the absorbing orifice (62).

18. 18. The detector (40) of claim 17, wherein the portion of the absorbing volume (56) forming the edge (64) of the absorbing orifice (62) is inclined inwardly relative to the absorbing volume (56).

19. The detector (40) includes an aperture (90) having an aperture opening (92); 19. A detector (40) according to any one of claims 11 to 18, wherein the aperture (90) is arranged upstream of the sensor element (50) and along an assumed and / or determined direction of incidence (122) of the electromagnetic radiation (120) to be measured.

20. 20. A detector (40) according to claim 19, wherein the size of the aperture opening (92) is adapted to the absorber (52), in particular to the absorbing orifice (62), so that the electromagnetic radiation (120) passing through the aperture opening (92) is incident on the absorbing surface (60) of the absorber (52), in particular through the absorbing orifice (62).

21. The detector (40) includes a shielding element (94); 21. A detector (40) as claimed in claim 19 or 20, wherein the shielding element (94) extends between the aperture (90) and the absorber (52) along an assumed and / or determined direction of incidence (122) of the electromagnetic radiation (120) to be measured.

22. 22. The detector (40) of claim 21, wherein the shielding element (94) extends further along the absorber (52) along the assumed direction of incidence (122) of the electromagnetic radiation (120).

23. The detector (40) includes two or more sensor elements (50); Detector (40) according to any one of claims 11 to 22, wherein the two or more sensor elements (50) are adjacent to and thermally isolated from one another.

24. 24. A detector (40) as described in claim 23, wherein the two or more sensor elements (50) are arranged in a rotationally symmetric pattern, a row, or a matrix in a plane perpendicular or at least substantially perpendicular to an assumed and / or determined direction of incidence (122) of the electromagnetic radiation (120) to be measured.

25. In a plane perpendicular or at least substantially perpendicular to an assumed and / or determined direction of incidence (122) of the electromagnetic radiation (120) to be measured, the two or more sensor elements (50) Rectangle, square, circle, ring, part of ring, 25. A detector (40) according to claim 23 or 24, comprising one of the following shapes:

26. The detector (40) according to any one of claims 11 to 25, wherein the detector (40) comprises a positioning element (42) for positioning the absorber (52) in a vacuum feedthrough (14).

27. 27. The detector (40) of claim 26, wherein the placement element (42) includes a positioning element for varying the position of the absorber (52) relative to the vacuum feedthrough (14).

28. A system (10) for thermal evaporation using electromagnetic radiation (120), comprising: an electromagnetic radiation source (110) for providing electromagnetic radiation (120), a vacuum chamber (12) containing a reaction atmosphere (16), and a detector (40) for measuring the electromagnetic radiation (120); A source material (20) and a target material (18) to be coated are disposed within the vacuum chamber (12); the electromagnetic radiation source (110) is positioned such that its electromagnetic radiation (120) is incident on the source surface (22) of the source material (20) at an angle of preferably 45 degrees for thermal evaporation and / or sublimation of the source material (20) below a plasma threshold; The detector (40) for measuring electromagnetic radiation (120) is positioned so that the electromagnetic radiation (120) reflected from the source surface (22) reaches the detector (40); The system (10) is adapted to carry out the method according to any one of claims 1 to 10, A system (10) wherein the detector (40) is constructed according to any one of claims 11 to 27.

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