Patent Application
20220195581
The present invention relates to a source arrangement for a deposition apparatus with a direct surface heater for applying a heating power onto a source surface of a source element, comprising a holding structure with a support and at least one source element arranged at the support, the source element comprising a source surface and a second surface opposite of the source surface, wherein source material can be vaporized and/or sublimated from a source area on the source surface when heated by the surface heater of the deposition apparatus. Further, the present invention relates to a deposition apparatus comprising a source arrangement with a source element, a target arrangement with a target element, a reaction chamber comprising a wall and containing a reaction atmosphere, an atmosphere controller configured to control the reaction atmosphere and a surface heater configured to heat a source area on the source surface of the source element, whereby the source arrangement and the target arrangement are positioned within the reaction atmosphere in the reaction chamber such that the source material can be deposited on the target element in a controlled way by heating the source area by usage of the surface heater by applying a heating power onto a heating spot on the source surface. Additionally, the present invention relates to a method for depositing source material on a target material in a deposition apparatus, the deposition apparatus comprising a surface heater and a source arrangement.
Deposition of a source material to a target material is a technique widely used in modern technology, for instance in the production of specialized semiconductors for electronic elements. A highly controlled environment, in particular with respect to a pressure and/or a composition of a reaction atmosphere, is essential to provide a deposition of the source material onto the taught material in high and/or highest quality. Even a deposition of a single atomic layer of the source material can be achieved.
In the deposition apparatus, the source material can be vaporized and/or sublimated from a source area using a direct surface heater. To achieve a deposition of the source material with high quality, it is necessary to control not only the reaction atmosphere but also the rate with which the source material is deposited onto the target material.
To control the aforementioned deposition rate, it is known in the state of the art to measure an energy consumption of the direct surface heater, for instance an electron beam source, and to calculate based on this measurement the amount of energy deposited onto the surface area of the source material. By that a deposition rate of the source material can be calculated at least in an indirect way and by adjusting the energy consumed by the direct surface heater an at least indirect control of the deposition rate can be achieved.
Unfortunately, this method according to the state of the art comprises several sources for inaccuracy and errors. For instance, a dissipation of the energy provided by the direct surface heater into the reaction atmosphere can lead to a reduction in the deposition rate. Also, misalignments of the direct surface heater lead to a decrease in energy deposited onto the surface material and therefore also in a reduction of the deposition rate. In summary, the high-quality standards necessary to achieve excellent deposition results can frequently not be provided.
In view of the above, it is an object of the present invention to provide an improved source arrangement for a deposition apparatus, a deposition apparatus and a method for depositing source material on a target material in a deposition apparatus which do not have the aforementioned drawbacks of the state of the art. In particular it is an object of the present invention to provide a source arrangement, a deposition apparatus and a method which allow a simple and pure evaporation and/or sublimation of a source material with minimal contamination, and additionally a control of a deposition rate with high accuracy, in an especially easy and cost-efficient way.
This object is satisfied by the patent claims. In particular, this object is satisfied by a source arrangement for a deposition apparatus according to claim 1, by a deposition apparatus according to claim 20 and by a method for depositing source material on a target material in a deposition apparatus according to claim 27. The dependent claims describe preferred embodiments of the invention. Details and advantages described with respect to a source arrangement according to the first aspect of the invention also refer to a deposition apparatus according to the second aspect of the invention and to a method for depositing source material on a target material according to the third aspect of the invention and vice versa, if of technical sense.
According to a first aspect of the invention, the object is satisfied by a source arrangement for a deposition apparatus with a direct surface heater for applying a heating power onto a source surface of a source element, comprising a holding structure with a support and at least one source element arranged at the support, the source element comprising the source surface and a second surface opposite of the source surface, wherein source material can be vaporized and/or sublimated by a source area on the source surface when heated by the surface heater of the deposition apparatus, wherein the source element consists of a source material and is arranged self-supporting at the support.
A source arrangement according to the first aspect of the invention is intended for a usage in a deposition apparatus with a direct surface heater. In other words, the source arrangement can be positioned within a reaction chamber of the deposition apparatus and a source material provided by the source arrangement according to the first aspect of the invention can be vaporized and/or sublimated with the direct surface heater of the deposition apparatus. For this purpose, the source arrangement comprises a holding structure with a support and at least one source element consisting of a source material. The source element is arranged self-supporting at the support, preferably directly arranged at the support. In other words, except of the support of the holding structure, no further support elements are needed to arrange, hold and fix the source element in the source arrangement according to the invention. This allows a simple and pure evaporation and/or sublimation, as the source material is the only material present in the source element. In addition, the surfaces of the source element not used for evaporation and/or sublimation are preferably not covered by additional elements and can therefore be used for instance for radiation cooling. This is especially advantageous for source materials with low vapor pressures as for instance molybdenum, tantalum or tungsten.
Further, a source arrangement according to the invention can comprise that the holder and the source element are constructed crucible-free. As described above, the source element consists of the source material and is arranged self-supporting at the support. Hence, the source element directly touches the support. Especially, no crucible is present or even needed, in which the source material is inserted. In other words, crucibles containing the source material can be avoided. A contamination of the vaporized and/or sublimated source material by material of the crucible or a reaction of the source material with the material of such crucible can be avoided.
It is a further embodiment of the source arrangement according to the invention, wherein the at least one source element is supported by the support at three or more, preferably at three, support positions, wherein the contact areas between the support and the source element at the support positions are point-like or at least essentially point-like contact areas. In other words, in this preferred embodiment the source element is as a self-supporting structure with an integral body element made out of source material in minimal physical contact with the support. Basically, also a single or a pair of support positions are possible, but these solutions are associated with balancing issues for the stability of the source element with respect to the support.
In this connection point or point like may mean that the support has a needle-like portion, i.e. a portion that tapers to a tip, and the source element is positioned at these tips of the support.
As contact areas between the source element and the support of the holding structure are always source for contamination, these contact areas preferably are minimized. This can be achieved in this preferred embodiment by providing point-like or at least essentially point-like contact areas. Three of these contact areas is the minimum number to provide a secure and stable positioning and support for the source element. Therefore, by providing three support positions with point-like contact areas, a risk of contamination of the source material by the material of the holding structure is minimized without sacrificing a stable and secure support of the source element within the holding structure.
Apart from avoiding contamination of the source material, a reduced contact area and especially a reduced temperature at these contact areas also help avoiding possible chemical reactions between a source material and a support material. In particular, an alloying, e.g by forming a eutectic mixture that has a lower melting point than both the support material and the source material, can be avoided. Especially with metallic materials used both for the support and the source element, such a forming of a eutectic mixture may lead to melting and failure of the support at temperatures below the individual melting points of the source material or the support material.
In addition, by locating a temperature sensor and the contact areas between the support and the source element in essentially orthogonal directions from the source area heated by the surface heater, the temperature offset and heat flow from the source area to the temperature sensor and to the support can be independently optimized. For example, in an essentially disc shaped source element with the source area located at the center of the source surface, the respective temperature sensor can be located at the center of the second surface and the contact areas between the support and the source element located at the radial rim of the disc, essentially the thickness of the disc in the axial direction determines the temperature offset between the source surface, in particular the source area, and a second surface that may be used for the temperature measurement with the temperature sensor, while the diameter of the disc determines the temperature offset between the source surface, in particular the source area, and the support. As particular dimensions of the thickness and of the diameter are orthogonal to each other, they can be independently chosen. Hence, the temperature drop both from the source area to the second surface, for instance used for a temperature measurement by a temperature sensor and the support, respectively, can independently be optimized.
The goal to be achieved by this optimization is to keep the overall surface of the body of the source element as small as possible to be able to achieve the highest possible temperature at the source area with minimum heating power, and to keep the volume of the source element large to be able to evaporate large amounts of material, while at the same time avoiding chemical reactions or alloy/eutectic formation at the contact areas to the temperature sensor and the support, both of which temperatures are, at least for pure elements, usually well-known from established phase diagrams.
As typically the source material is a homogeneous, ultrapure single chemical element, the geometry of the body of the source element is well determined, e.g. preferably rotationally symmetric, the emitting surfaces are dean, at least at low pressures, and heat dissipation is strongly dominated by radiation at high temperatures, this optimization can be done reliably through numerical computations, in particular finite element numerical simulations, for each source material. This saves time and effort, as each source material has different bulk thermal conductivity and surface emissivity values and therefore needs to be shaped differently and optimized separately to reach the optimization goal. Doing this entirely through test experiments would require a significant effort.
Preferably, a source arrangement according to the invention is improved by that the at least one source element and/or the support comprise conical protrusions for providing the point-like or at least essentially point-like contact areas between the support and the at least one source element. Cones provide a basis and a point-like tip. By the usage of conical protrusions these features of cones can be used to provide point-like or at least essentially point-like contact areas. As the conical protrusions are provided by the source element and/or the support, no further elements to provide the point-like or at least essentially point-like contact areas are necessary.
According to a further embodiment of a source arrangement according to the invention, the at least one source element comprises at least one reduction opening extending in the source element from the source surface to the second surface for a reduction of the thermal conductivity within the at least one source element. The direct surface heater of the deposition apparatus deposits heating power onto and/or into the source area on the source surface of the source element. Heat dissipation within the source element distributes this heating power within the source element. Especially in source materials with high thermal conductivity, this can lead, on the one hand, to unnecessary high energy consumption, as the heating power of the surface heater is distributed in the source element as a whole. On the other hand this can lead to a loss in localization of the source area. Reducing openings in the source element that extend through the source element from the source surface to the second surface can provide avoiding these problems. These reducing openings extend through the whole source element perpendicular to a radial direction starting at the source area and therefore perpendicular to the heat flow emanating from the source area. In other words, an effective cross section of the source element for this heat flow can be reduced, resulting in a better localization of the source area and simultaneously in a lower temperature at the contact areas. If necessary, the reducing openings can cover a whole circumference at a certain radial distance to the source area, except for one or more, preferably narrow, bridge section to provide structural integrity of the source element. Thermal dissipation in this radial direction in the source element is therefore interrupted and reduced. Therefore, the dissipation of the heating power of the direct surface heater stays localized at the source area. An improvement in control of the dissipated heating power and therefore in the deposition rate achievable with a source arrangement according to the invention can therefore be provided.
In a further embodiment of the source arrangement according to the invention, the at least one source element is divided in a first part and at least one second part separate to the first part, wherein the first part comprises the source surface and wherein the first part and at least one second part are stacked to form the source element, whereby the first part is supported by the at least one second part at three or more, preferably at three, support positions, wherein the contact area between the first part and the at least one second part at the support positions are point-like or at least essentially point-like contact areas, in particular wherein the first part and/or at least one second part comprise conical protrusions for providing the point-like or at least essentially point-like contact areas between the first part and the at least one second part. In other words, these stacked first and at least one second part provide a separation of different parts of the source element similar to the aforementioned reducing opening, but not only in radial direction but throughout the whole source element. For instance, if the first part and at least one second part are planar elements, the separation is perpendicular to the aforementioned radial direction.
In another embodiment, the first part and the at least one second part are shaped as a spherical half-shell, a spherically radial separation of the different parts can be provided. The usage of point-like or at least essentially point-like contact areas provide the same advantage as aforementioned with respect to the connection areas between the support and the source material. Especially, temperature conductivity by the physical contact at these point-like or at least essentially point-like areas can be minimized. In summary, a temperature gradient within the source element can therefore be optimized. Especially, a heat disposition through the source element as a whole can be lowered, providing especially low temperatures at locations of the source element in contact to the support, independent of the temperatures reached at the source area.
In a further embodiment of a source arrangement according to the invention, the at least one source element comprises at least one emission section for an emission of thermal energy, wherein the at least one emission section is provided by an emission region arranged radially in the source element with respect to the source area and/or is shaped as a protrusion protruding from the second surface, in particular wherein the at least one emission section is shaped as a protrusion protruding from the second surface, whereby the protrusion is shaped like a prism, in particular an oblique prism and/or like a cone and/or like an intersection of at least two of these shapes.
One of the sources of contamination, chemical reaction or alloy formation, as already mentioned above, are contact areas between the source element and the support of the holding structure. A severity of these contaminations, chemical reactions, or alloy formations depends especially on the temperature of the source element at these contact areas. An emission section arranged radially in the source element with respect to the source area can help to reduce the temperature of the source element at the contact areas, as these contact areas in most of the cases essentially are located at and/or near an outer rim of the source element. Thermal energy is radiated away from the source element in the emission region and therefore the temperature at the contact areas is lower, in particular low enough that no or at least less contamination, chemical reaction, or alloy formation result. To achieve the best results, the emission region preferably surrounds the source area. Additionally, the emission region can comprise a small thickness perpendicular to the radial direction, thereby further reducing temperature conductivity in the radial direction. Thereby a temperature at the contact areas can be lowered further.
Similar advantages can be achieved by emission sections shaped as protrusions protruding from the second surface. These protrusions enlarge the total area of the second surface and thereby the possibility of emitting thermal energy by thermal radiation. Prism-shaped protrusions and/or cone-shaped protrusions are preferable embodiments of these protrusions, in particular as these shapes can be provided in an axially symmetric way.
In another embodiment, a source arrangement according to the invention can be characterized in that the source arrangement comprises an actuator for altering the relative position of the source element within the source arrangement for a variation of the location of the source area on the source surface when heated by the surface heater of the deposition apparatus. In other words, this actuator can move the source element with respect to the source arrangement as a whole and hence with respect to the reaction chamber and the heating spot of the surface heater, respectively.
In particular, the actuator is part of the holding structure and/or the support. Preferably, the actuator can even be positioned outside of the reaction chamber of the respective deposition apparatus, and only a mechanical linkage is provided through a sealed opening in the wall into the reaction chamber. By changing the relative position of the source material within the source arrangement as a whole also the location of the heating spot, the impact point of the thermal energy of the direct surface heater is changed on the source surface. Hence, also the positioning of the source area on the source surface is changed. A better distribution of the heating power onto the source surface of the source element and hence of the removal of source material by evaporation or sublimation from the source surface can therefore be provided. An especially even source surface of the source material of the source element can therefore be maintained. This is important for a constant and reproducible deposition rate of source material on the target, as the deposition rate depends on the relative orientation of source surface, especially the source area, and target surface during deposition.
For example in a preferred embodiment, the body of the source element is essentially rotationally symmetric, a temperature sensor for a temperature measurement can be located on the symmetry axis at the second surface, the source area is shaped as an ideally circular heating spot and is located at a fixed radial distance away from the symmetry axis on the source surface. Simultaneously, the source element is movable by the actuator around its symmetry axis. This moves the source area around the symmetry axis on a circular path. During this movement, the heat distribution in the source element rotates around the symmetry axis, but essentially does not change its shape in this rotating reference frame. In particular, the distance between source area and temperature sensor and therefore the temperature difference between source area and the temperature sensor does not change. With constant temperature at the temperature sensor, the evaporation rate does not change despite the rotating movement, allowing reliable control of the evaporation rate. If laser radiation is used by the surface heater, this radiation may be strongly focused to achieve large temperature differences to the temperature sensor and the support, respectively. Still, a larger area of the source surface is evenly removed, allowing the evaporation of larger amounts of source material without strongly affecting the local inclination of the source area with respect to the target and thereby the deposition rate on the target.
Further, a source arrangement according to the invention can be characterized in that the source arrangement according to the invention comprises a temperature sensor for a temperature measurement at the source element. In other words, the temperature sensor of the source arrangement can provide a direct temperature measurement of the source material of the source element. This allows to base an adjustment of the heating power of the direct surface heater on the temperature of the source element, and actively to establish a feedback mechanism, whereby the temperature of the source element can be used as input variable and the heating power of the direct surface heater can accordingly be adjusted. Especially, a closed loop control for the heating power of the direct surface heater can be established based on the measured temperatures of the source element. In summary, as the rate with which source material is vaporized and/or sublimated from a source area on the source surface of the source element is directly dependent on a temperature of the source element, a deposition rate of the vaporized and/or sublimated source material onto a target material in the deposition apparatus can be provided with high accuracy and constancy.
In particular, the temperature sensor is arranged at the second surface of the source element, in particular wherein the temperature sensor is arranged at a symmetric center of the second surface, or at a symmetric center of the source element, or at a common symmetric center of the second surface and the source element. Such an arrangement of the temperature sensor at the second surface of the source element, with the second surface being located opposite to the source surface, can be easily provided as the source element preferably is directly supported by the support of the holding structure without any further support elements as for instance crucibles. In other words, additionally to the source surface also the second surface of the source element is at least partly directly accessible. Further, the second surface is not heated by the direct surface heater and therefore a contamination of the temperature sensor by vaporized and/or sublimated source material can be avoided. Then again, as the source element might comprise a small thickness between the source surface and the second surface, a temperature measurement of the source element, with which a sufficiently exact temperature distribution of the whole source element can be achieved, can be provided by arranging the temperature sensor at the second surface of the source element.
An arrangement of the temperature sensor at and/or near to a symmetric center of the second surface and/or the source element as a whole is of an advantage as in most of the cases also the source area, where the vaporization and/or sublimation of the source material takes place, is also arranged at and/or near a symmetric center of the source element, but on the source surface. A distance of the position of the temperature sensor to the source area, the hottest part of the source element, can thereby be minimized and an accuracy of the temperature measurement can be enhanced.
In this connection it should be noted that the symmetric center is the geometric center, i.e. the point at the center of a circle, the center of a line between the two foci of an ellipse.
Further, a source arrangement according to the invention can be improved by that the second surface comprises an inlet guide section for guiding the temperature center into its position, in particular an at least partially conical and/or cylindrical inlet guide section, arranged at the source element at a symmetric center of the second surface and/or the source element, preferably extending inward into the source element. Such an inlet guide section can be used to mechanically guide the temperature sensor at its designated position. In particular, even after removing the temperature sensor, at the next positioning the inlet guide section ensures an identical placement of the temperature sensor. An at least partially conical and/or cylindrical inlet guide section is preferred as these are rotationally symmetric and therefore no radial direction is preferred and/or deprived. An arrangement of the inlet guide section at the source element at the symmetric center of the second surface and/or the source element as a whole allows an especially easy way for positioning the temperature sensor at this symmetric center. Preferably, the inlet guide section can be integrated and/or be part of the above mentioned protrusions used as an emission section.
Additionally, the inlet guide section can extend inwardly into the source element and therefore reducing the distance between the temperature sensor and the surface area on the source surface, whereby at this source area the vaporization and/or sublimation of the first material takes place. As mentioned above, a temperature measurement at such a position within the source element which is located at an especially small distance to the source area helps to improve the accuracy of the temperature measurement and the corresponding control of the heating power of the direct surface heater.
In addition, a source arrangement according to the invention can be characterized in that the temperature sensor is arranged in direct contact with the second surface, wherein in particular the temperature sensor comprises a thermocouple element. A temperature sensor arranged in direct contact with the second surface is a preferred embodiment in all situations, in which the expected temperature of the source element is lower than a temperature bearable by the temperature sensor. This includes limits set by possible reactions such as, e.g. the formation of a eutectic between the source element and the temperature sensor. Thermocouple elements are preferred temperature sensors for these cases.
As an alternative, a source arrangement according to the invention can be characterized in that the temperature sensor is arranged spaced to the second surface, wherein in particular the temperature sensor comprises a pyrometer element. In cases, where the expected maximum temperature of the source material is higher than a temperature bearable by the temperature sensor, for instance if a source material with an extremely high melting point such as tungsten is used, a direct contact between the temperature sensor and the source element has to be avoided. Otherwise, the temperature sensor might be damaged and/or destroyed. For these cases, an arrangement of the temperature sensor spaced to the second surface of the source element is of an advantage. Pyrometers are preferred embodiments of temperature sensors for these cases.
According to a second aspect of the invention the object is satisfied by a deposition apparatus, comprising a source arrangement with a source element, target arrangement with a target element, a reaction chamber comprising a wall and containing a reaction atmosphere, an atmosphere controller configured to control the reaction atmosphere and a surface heater configured to heat a source area on a source surface of the source element, whereby the source arrangement and the target arrangement are positioned with the reaction atmosphere within the reaction chamber such that the source material can be deposited on the target element in a controlled way by heating the source area by usage of the surface heater by applying a heating power onto a heating spot on the source surface, wherein the source arrangement is constructed according to the first aspect of the invention. The deposition apparatus according to the second aspect of the invention comprises a source arrangement according to the first aspect of the invention. Therefore, all advantages described above with respect to a source arrangement according to the first aspect of the invention can also be achieved by a deposition apparatus according to the second aspect of the invention.
Additionally, a deposition apparatus according to the invention can comprise a controller for controlling the temperature of the target. This controller can comprise both temperature sensors to measure the temperature of the target material and a target heater to adjust the temperature of the target material, Especially a dosed loop control for the target temperature can be established. The temperature sensors can be contact sensors, as for example thermocouples, or contact-free sensors, as for example pyrometers. The target heater can preferably use a suitable laser beam for heating the target material,
Preferably, a deposition apparatus according to the invention can be characterized in that the surface heater comprises a laser light source for emitting laser light into the reaction chamber and/or an aperture in the wall of the reaction chamber for coupling laser light into the reaction chamber, whereby the laser light is directed onto the surface area on the source surface of the source element, and in particular wherein the laser light is a UV laser light and/or a visible laser light and/or an IR laser light, and/or wherein the reaction chamber comprises a cooler for cooling of the reaction chamber and/or the reaction atmosphere, in particular an active cooler, wherein the cooler is preferably arranged at and/or in the wall of the reaction chamber, and/or wherein the atmosphere controller comprises a vacuum pump for providing a reaction atmosphere with a pressure between 10−11 mbar and 1 mbar.
Using a direct surface heater based on laser light comprises several advantages. First of all, the amount of electric components within the reaction chamber, for instance as needed for a surface heating with an electron beam source, can be drastically reduced. Limitations with respect to the reaction atmosphere, for instance with respect to corroding gases as reaction atmosphere and/or upper limits on the pressure of the reaction atmosphere, can therefore be avoided. Additionally, laser light can be provided over a wide range of energies, preferably starting with IR light up to UV light. In particular, for different source materials, an accordingly adapted laser light can be chosen. Further, in contrast to electron beam heating, a conductivity of the source material is not necessary and additionally evaporated or sublimated vapor is not ionized by electron impact.
Cooling the reaction chamber allows to further improve the quality of the reaction atmosphere. On the one hand, impurities in the reaction atmosphere can freeze out on these coolers and therefore the lower limits for a pressure of the reaction atmosphere can be lowered. Active coolers are preferred, as the thermal energy absorbed in the cooler is purged and no pile-up effect of absorbed energy arises. On the other hand, a cooler can also be positioned such that reflected laser light is directed at these coolers and therefore an undesired heating of the reaction chamber and damage caused by reflected laser light can be avoided. An arrangement at and/or in the wall of the reaction chamber has been proven to be especially effective for this purpose.
Providing a vacuum pump by means of which pressures down to 10−11 mbar are possible in the reaction chamber, making available a wide range of reaction atmosphere pressures can be provided.
Essentially, all of the preferred embodiments mentioned above broaden the possible field of application of a deposition apparatus according to the invention.
In a third aspect of the invention the object is solved by a method for depositing source material on a target material in a deposition apparatus, the deposition apparatus comprising a surface heater and a source arrangement according to the first aspect of the invention, in particular in a deposition apparatus according to the second aspect of the invention, comprising the following steps:
A method according to the invention can thus be carried out using a source arrangement according to the first aspect of the invention, in particular in a deposition apparatus according to the second aspect of the invention. All advantages described above with respect to a source arrangement according to the first aspect of the invention and/or with respect to a deposition apparatus according to the second aspect of the invention, can therefore also be achieved by a method for depositing source material according to the third aspect of the invention.
In a first step a) of the method according to the invention the source arrangement is arranged in the reaction chamber. The source arrangement according to the first aspect of the invention comprises a source element made out of source material. After step a) therefore there is a source element made out of source material arranged within the reaction chamber. Additionally, the source arrangement according to the first aspect of the invention also comprises a temperature sensor. Hence, no additional elements for providing a temperature measurement of the source element are necessary.
The next step b) comprises heating of the source area on the source surface of the source element by the surface heater. This can be provided by applying a heating onto a heating spot on the source surface by the surface heater, in particular using laser light. A vaporization and/or sublimation of the source material can therefore be provided.
In particular, in step c) a temperature of the source element is measured by the temperature sensor of the source arrangement. Therefore, after step c) information about the status of the source element, represented by the measured temperature, can be provided.
This information can be used in the next step d) for an adjustment of heating of the source area by the surface heater based on the temperature measured in step c). Especially a dosed loop control can be established. A highly controllable deposition rate of source material onto a target material in the deposition apparatus can therefore be provided.
A method according to the invention can be improved in that step d) comprises an adjustment of the heating power provided by the surface heater onto the source area, in particular, wherein the adjustment of the heating power comprises a pulsed operation of the surface heater in at least one alternating on-phase and off-phase, whereby the heating power is adjusted by choosing suitable durations of the at least one on-phase and off-phase, in particular by choosing a suitable ratio of the durations of the at least one on-phase and off-phase.
A first possibility of adjusting the heating of the source area by the surface heater can be provided by directly adjusting the heating power provided by the surface heater at the source area. When laser light is used to provide the heating power onto the source area, this adjustment can be done by adjusting the output power of the laser via an electric control interface. Also accordingly used covers, slits and/or other light shade elements are possible.
Preferably, the adjustment of the heating power comprises a pulsed operation of the surface heater, in particular the laser source. By providing alternating on-phases and off-phases, a time averaged heating power can be provided. Adjusting the durations of on-phases and off-phases, especially adjusting a suitable ratio of the durations of the on-phases and off-phases, is an especially suitable way of providing a controlled adjustment of the heating power.
Additionally or alternatively, a method according to the invention can be characterized in that step d) comprises a spatial variation of a position of the source area at the source surface of the source element, in particular wherein the spatial variation of the position of the source area is brought about by altering a position of the heating spot of the surface heater relative to the surface element and/or by altering the position of the surface element relative to the position of the heating spot, in particular provided by the actuator of the source arrangement. In contrast to the aforementioned embodiment of a method according to the invention, in which a temporal averaging is used to adjust the average heating power, in this embodiment a spatial averaging is used to achieve the same advantages, namely a temporally or spatially peaked power distribution for high surface temperature in the peak, combined with a low average power. By varying a position of the source area at the source surface of the source element, the actual position at the source surface where the sublimation and/or vaporization takes place, changes. A distribution of the heating power onto the source surface and hence of the vaporization and/or sublimation of source material of the source element can therefore be provided.
This spatial variation of the position of the source area can be provided for instance by altering a position of the heating spot of the surface heater relative to the surface element. In other words, the source element stays spatially fixed and the position of the heating spot is altered.
In contrast to this also the spatial position of the heating spot can stay fixed and the position of the surface element relative to the position of the heating spot is altered, in particular provided by the actuator of the source arrangement. Also in this embodiment a distribution of the total provided heating power and hence of the vaporization and/or sublimation at the source surface of the source element can be provided.
Also a combination of the aforementioned two embodiments, a variation of the position of the heating spot and additionally a variation of the relative position of the surface element relative to the position of the heating spot, can be provided to further enhance the averaging an homogenization of the evaporation flux on the target.
The present invention is further described hereinafter with reference to illustrated embodiments shown in the accompanying drawings. There is shown:
According to a method according to the invention in a first step a) the source arrangement 10 is arranged within the reaction chamber 70. The next step b) comprises a heating of the source area 30 by applying a heating power 82 onto a heating spot 66 on the source element 20. In particular, in the next step c) a temperature of the source element 20 is measured by the temperature sensor 18 of the source arrangement 10 according to the invention. In the last step d) of a method according to the invention, this permits an adjustment of the heating of the source area 30 by the surface heater 62 based on the temperature measured by the temperature sensor 18 in step c). In other words, this allows establishing a closed loop control of the heating power 82 based on the measured temperatures of the source element 20.
Additionally, the deposition apparatus 60 shown in
The left embodiment shown in
The embodiment shown on the right side of
The embodiment shown on the left side of
The embodiment shown on the right side of
As shown on the left side in
As shown on the right side of
The next two
In the embodiment shown on the left side of
On the right side of
Opposite to that, in other cases, thermal energy should be contained at the source area 30.
In
The upper left embodiment shown in
The upper right embodiment is similar, but in this case the movement of the heating spot 66 is a spiral one.
For rectangular source elements 20, a meander-like path of the heating spot 66 on the source surface 28 of the source element can be advantageous, as shown in the lower part of
In all of the embodiments the heating power 82 is sequentially distributed over a larger area on the source surface 28 of the source element 20. Therefore a more distributed vaporization and sublimation of the source material 42 can easily be provided.
10 source arrangement
12 holding structure
14 support
16 actuator
18 temperature sensor
20 source element
22 first part
24 second part
26 symmetrical center
28 source surface
30 source area
32 second surface
34 inlet guide section
36 reducing opening
38 emission section
40 emission region
42 source material
44 vapour
50 support position
52 contact area
60 deposition apparatus
62 surface heater
64 laser light
66 heating spot
68 target arrangement
70 reaction chamber
72 wall
74 cooler
76 reaction atmosphere
78 atmosphere controller
80 target
82 heating power
84 spatial variation
86 surface temperature
87 temperature controller
88 temperature sensor
89 target heater
90 on-phase
92 off-phase
94 duration
| Number | Date | Country | Kind |
|---|---|---|---|
| 19169438.9 | Apr 2019 | EP | regional |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2020/060550 | 4/15/2020 | WO | 00 |
