Semiconductor Device and Method for Manufacturing a Semiconductor Device

Abstract

A method for fabricating a semiconductor device (1) comprises depositing a getter layer (3) over a sapphire substrate (2). The getter layer (3) is formed from a compound semiconductor material comprising Al, N and a transition metal X. Subsequently, the getter layer (3) is heated to a high temperature at a temperature greater than 1400°C and less than 2400°C.

Description

The present disclosure relates to a semiconductor device and a method for manufacturing such a semiconductor device. In particular, the present disclosure relates to the use of a getter layer made of a compound semiconductor material containing aluminum, nitrogen, and a transition metal on a sapphire substrate. Such semiconductor devices are suitable as a substrate or template for the epitaxial growth of layers containing, for example, (Al)GaN or InGaN. Due to their large band gap, semiconductor devices with GaN or InGaN layers are used in numerous applications, including optoelectronic devices. One purpose of the present disclosure is to provide an improved manufacturing process and improved semiconductor devices. According to embodiments, the problem is solved by the subject matter of the independent claims. Advantageous further developments are defined in the dependent claims. The problem is solved in particular by a method for manufacturing a semiconductor device, which includes the deposition of a getter layer over a sapphire substrate. This getter layer is formed from a compound semiconductor material comprising aluminum (Al), nitrogen (N), and a transition metal X. Subsequently, the sapphire substrate with the getter layer is heated to a high temperature between 1400°C and 2400°C. A compound semiconductor material is a semiconductor material composed of two or more elements. In this case, the compound semiconductor material includes aluminum, nitrogen, and a transition metal X. The transition metal X could be, for example, scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf). A getter layer has the effect of binding unwanted impurities, such as oxygen, thereby improving the purity and quality of the layers above it. As a result, a subsequent process for removing the impurities, for example in a later epitaxy procedure, can be omitted. Thanks to the introduction of a getter layer containing Al, N, and X, the formation of so-called AlON volcanoes—that is, AlON accumulations that grow from the sapphire / AlN interface to the surface—can be prevented. This allows the high-temperature heating process to be carried out at higher temperatures, resulting in a lower dislocation density. A lower dislocation density is advantageous because it increases the internal quantum efficiency in optoelectronic devices such as UV LEDs. The function of the getter layer also includes effectively preventing or reducing oxygen diffusion by introducing a transition metal X, thereby preventing or at least reducing the formation of AlON contamination on the surface. This simplifies the downstream epitaxy process and improves the crystal quality of subsequent layers. Furthermore, by using X and controlling the concentration of X in an AlXN layer, lattice matching can be achieved, which advantageously reduces relaxations and thus allows for better performance characteristics of the components. In the context of this disclosure, high-temperature heating is a process in which the material is heated to very high temperatures. It is therefore a heating of the semiconductor device or the layer sequence, which takes place at very high temperatures in the range of 1400°C to 2400°C. It can also be referred to as high-temperature annealing or simply annealing. High-temperature heating can be carried out in a furnace. Advantageously, it serves to improve the crystal structure of the material and reduce defects. High-temperature heating is performed, for example, at a temperature higher than that at which a downstream sputtering or epitaxial deposition process is carried out. One advantage of this process is therefore improved crystal quality in the fabricated semiconductor device. Another advantage is the potential for lattice matching to subsequent layers, such as AlGaN, which can improve the performance of the semiconductor device. According to one embodiment, the thickness of the getter layer is in the range of 20 nm to 400 nm, for example in a range of 50 nm to 300 nm. In one embodiment of the method, high-temperature heating takes place at a temperature of 1400°C to 1800°C. This temperature range is advantageous because it offers a good balance between minimizing defects and maintaining the structural integrity of the sapphire substrate and the getter layer applied to it. According to one embodiment, after high-temperature heating of the sapphire substrate with the getter layer, a semiconductor body is epitaxially grown over the getter layer, which has an InxAlyGa1-x-yN layer, where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1. The InxAlyGa1-x-yN layer is a compound semiconductor layer consisting of the elements indium (In), aluminum (Al), gallium (Ga), and nitrogen (N). The variables x and y determine the specific composition of the layer, which in turn influences the optoelectronic properties such as band gap and emission wavelength. The term "epitactical" refers to the controlled growth of a crystalline layer on a substrate, where the crystalline structure of the layer is influenced by the structure of the underlying substrate. In particular, at least one crystallographic orientation of the growing crystal corresponds to an orientation of the crystalline substrate. In one embodiment, during the fabrication of a semiconductor device, the amount of transition metal X contained in the getter layer is selected according to the lattice constant of the semiconductor body. This means that the concentration of transition metal X in the getter layer is specifically adjusted so that the resulting crystal structure of the getter layer optimally matches the lattice constant of the subsequently deposited semiconductor body. By adjusting the amount of X in the getter layer, the lattice matching between the getter layer and the semiconductor body can be improved, leading to a reduction in lattice mismatches and associated defects. Furthermore, the targeted selection of the amount of X can also help to inhibit oxygen diffusion from the sapphire substrate by having the transition metal act as an oxygen getter. This prevents the formation of unwanted AlON contamination, which could negatively affect surface quality and subsequent epitaxial growth processes. Advantageously, this can lead to improved quantum efficiency and quality of the produced semiconductor devices, which is of particular importance for applications in optoelectronics and power electronics. According to one embodiment, a method for manufacturing a semiconductor device is described in which a transition metal X is selected from a group comprising scandium (Sc), yttrium (Y), titanium (Ti) and hafnium (Hf). The specific selection of X from Sc, Y, Ti, and Hf offers several advantages. Due to their high electronegativity, these transition metals help to inhibit oxygen diffusion from the sapphire substrate into the getter layer and subsequently into the layers above. This is particularly important to prevent the formation of AlON contamination, which could impair the crystal quality of the subsequent layers. Furthermore, the inclusion of these transition metals enables better lattice matching of the getter layer to subsequent layers, especially to AlGaN layers typically used in UV LEDs. This lattice matching is crucial for minimizing voltage relaxations and defect formation caused by lattice mismatches. The selection of Sc, Y, Ti and Hf as the transition metal X in the getter layer advantageously leads to improved control over oxygen diffusion, better lattice matching and a reduction in dislocation density, which supports a higher quality of the manufactured semiconductor device. In one embodiment, an AlN layer is applied to the sapphire substrate before the getter layer is applied. This AlN layer can be applied to the sapphire substrate by various methods, such as sputtering. An AlN layer is a semiconductor layer made of aluminum (Al) and nitrogen (N). According to one embodiment, the method comprises an initial high-temperature heating of the sapphire substrate with the AlN layer at a temperature greater than 1400°C and less than 2400°C, for example at a temperature in a range between 1400°C and 1800°C, before the getter layer is applied. Heating stabilizes the AlN layer and reduces potential stresses that could arise from lattice mismatch between the sapphire substrate and the AlN layer. This leads to improved crystal quality of the AlN layer, which in turn forms the basis for the subsequent getter layer. The getter layer, consisting of a compound semiconductor with aluminum, nitrogen, and a transition metal X, is then deposited onto the already heat-treated AlN layer. This advantageously results in improved quality of the semiconductor device. In the context of this disclosure, an initial high-temperature heating is a heating process performed prior to the high-temperature heating of the getter layer. It can be carried out at the same temperatures as the subsequent high-temperature heating of the getter layer. For example, the initial high-temperature heating is performed at a temperature higher than that at which a downstream sputtering or epitaxial process is carried out. Alternatively, the sapphire substrate with the AlN layer is not initially heated to a high temperature. The AlN layer is heated to a high temperature together with the getter layer, for example. According to embodiments, in a method for manufacturing a semiconductor device, an additional layer of aluminium nitride (AlN) is applied after a getter layer has been applied to a sapphire substrate, but before the sapphire substrate with the getter layer is subjected to high-temperature heating. If an initial high-temperature heating process is also carried out, the application of an AlN layer as well as the application of the getter layer takes place after the initial high-temperature heating. According to possible embodiments, after the application of the getter layer and before the high-temperature heating of the sapphire substrate with the getter layer, an AlN layer and immediately afterwards a lattice matching layer comprising Al, N and a transition metal X are applied. This involves applying a layer sequence of AlXN / AlN / AlXN. According to embodiments, a layer sequence of AlXN / ALN / ALXN is applied to, for example, a previously annealed AlN layer, i.e., an AlN layer that has already been subjected to initial high-temperature heating. The use of an AlXN / ALN / ALXN layer sequence, consisting of a getter layer, an AlN layer, and a lattice-matching layer, allows for the suppression of oxygen diffusion, particularly through the getter layer, as well as achieving a particularly precise lattice match with subsequent AlGaN or InGaN layers, especially through the lattice-matching layer. The composition of the two AlXN layers, i.e., the getter layer and the lattice-matching layer, can differ. They can therefore contain different amounts of X. This enables largely lattice-matched growth of the AlGaN layers or the InxAlyGa1-x-yN layers, where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1, in the subsequent structure. Another aspect of the invention relates to a semiconductor device comprising a sapphire substrate, an AlN layer adjacent to the sapphire substrate, and a getter layer arranged on the side of the AlN layer facing away from the sapphire substrate. This getter layer contains aluminum (Al), nitrogen (N), and a transition metal X. An advantage of this structure is the inhibition of oxygen diffusion from the sapphire substrate, which can prevent the formation of AlON contamination and thus improve the crystal quality of subsequent layers. Another advantage is the potential for the getter layer to adapt the lattice structure to subsequent AlGaN layers or InxAlyGa1-x-yN layers, where 0 ≤ x ≤ 1 and 0 ≤ y ≤ 1, which can improve the performance of the semiconductor device. The concentration of the transition metal X can be varied to make specific adjustments to the requirements of the subsequent layers.A semiconductor device according to this aspect can be used as a lattice-adapted substrate for subsequent epitaxy processes for growing LED structures. According to one embodiment, the thickness of the getter layer is in the range of 20 nm to 400 nm, for example in a range of 50 nm to 300 nm. The transition metal X can be selected from the elements scandium (Sc), yttrium (Y), titanium (Ti), and hafnium (Hf). The advantages of these elements described herein can lead to an improvement in the overall performance and reliability of the semiconductor device. Firstly, the use of a transition metal with high electronegativity ensures oxygen trapping, and secondly, the lattice structure can be adapted to subsequent layers by using a certain concentration of X. This advantageously reduces defects and improves the performance of the components. According to one embodiment, the semiconductor device has a getter layer with a dislocation density of less than 5 × 10⁸ cm⁻². If further semiconductor layers are epitaxially grown above the getter layer, a high quality of these semiconductor layers can be achieved at such low dislocation densities. According to one embodiment, the semiconductor device comprises a semiconductor body having an epitaxially grown compound semiconductor layer of InxAlyGa1-x-yN with 0 ≤ x and 0 ≤ y, which is of the n type. The InxAlyGa1-x-yN compound semiconductor layer offers flexibility in adjusting the band gap and material properties by varying the indium (In), aluminum (Al), and gallium (Ga) content, for example, AlGaN or InGaN. Furthermore, the semiconductor body includes a photoactive zone for absorbing or emitting electromagnetic radiation. In the context of this disclosure, a photoactive zone can be composed of several sublayers and, for example, form a multiple quantum well (MQW) structure. The photoactive zone, in the context of this disclosure, is capable of emitting or absorbing electromagnetic radiation, for example, converting electrical energy into the emission of electromagnetic radiation. Additionally, the semiconductor body comprises a p-type semiconductor layer. The layers in the semiconductor body are arranged, for example, in such a way that the epitaxially grown n-type compound semiconductor layer is located between the photoactive zone and the sapphire substrate. Another aspect of the invention relates to a semiconductor device comprising a sapphire substrate and a getter layer adjacent to this sapphire substrate. This getter layer contains the elements nitrogen (N), aluminum (Al), and a transition metal X. In an enrichment region of the getter layer adjacent to the sapphire substrate, oxygen is enriched such that AlOXN is formed. Thus, an enrichment region is formed in the getter layer, in an area adjacent to the sapphire substrate, which exhibits an oxygen enrichment, leading to the formation of AlOXN. An enrichment region in which AlOXN is formed exists, for example, when the oxygen concentration in this region is at least 20%. This oxygen concentration can be detected, for example, using a TEM (transmission electron microscope), EDA (energy-dispersive X-ray analysis), or SIMS (secondary ion mass spectrometry) method. One advantage of this structure is the improved crystal quality of the subsequent layers, which can lead to higher efficiency of the semiconductor device. Another advantage is the ability to improve the lattice matching to subsequent layers, such as AlGaN, by selecting the appropriate amount of transition metal X in the getter layer. This can enhance the performance of optoelectronic devices, such as LEDs. The enrichment area of ​​the getter layer can have a layer thickness of a maximum of 400 nm, for example in a range of 50 nm to 400 nm. According to embodiments of the semiconductor device, an AlN layer is arranged adjacent to the getter layer on the side of the getter layer facing away from the sapphire substrate. According to embodiments, the AlN layer can act as a buffer layer for LED growth. According to embodiments, the semiconductor device comprises a compound semiconductor layer of InxAlyGa1-x-yN, where 0 ≤ x and 0 ≤ y. This compound semiconductor layer is arranged on the side of the getter layer facing away from the substrate. Advantageously, the lattice configuration can be chosen such that both an AlGaN and an InGaN compound semiconductor layer are possible. The crystal structure can therefore be adapted to subsequent AlGaN or InGaN layers, depending on the application. According to embodiments, the semiconductor device comprises a photoactive zone for absorbing or emitting electromagnetic radiation and a p-type semiconductor layer. According to embodiments, the semiconductor device is designed as an optoelectronic semiconductor device, such as a light-emitting diode (LED), or as a power semiconductor device. Furthermore, the use of AlXN allows the fabrication of grid-matched substrates on AlGaN or other compound semiconductors. This reduces relaxation at defects and enables improved performance of semiconductor devices, such as LEDs. EXAMPLES OF EXECUTION The accompanying drawings serve to illustrate exemplary embodiments of the invention. The drawings depict these embodiments and, together with the description, explain them. Further exemplary embodiments and many of the intended advantages will become apparent from the detailed description below. The elements and structures shown in the drawings are not necessarily drawn to scale. Identical reference numerals refer to identical or corresponding elements and structures. The figures show: Fig. 1: a semiconductor device produced by the method described herein, in which a getter layer is arranged on a sapphire substrate; Fig. 2: a semiconductor device with an AlN layer on the getter layer; Fig. 3: a semiconductor device with two AlN layers, between which the getter layer is arranged; Fig. 4: a semiconductor device with an AlN layer adjacent to the substrate; Fig. 5: a semiconductor device with an AlN layer that has already undergone initial high-temperature heating and a further AlN layer; Fig. 6: a semiconductor device with an AlN layer that has already undergone initial high-temperature heating, a further AlN layer, and a separate grating matching layer; Fig. 7A: a semiconductor device with an AlN layer, wherein the semiconductor device is designed as an optoelectronic semiconductor device.Fig. 7B: a semiconductor device with an AlN layer, wherein the semiconductor device is configured as a power semiconductor device; Fig. 8A: a semiconductor device with an enrichment layer, wherein the semiconductor device is configured as an optoelectronic semiconductor device; Fig. 8B: a semiconductor device with an enrichment layer, wherein the semiconductor device is configured as a power semiconductor device; Fig. 9: a method for producing a semiconductor device in which high-temperature heating is performed; Fig. 10: a method for producing a semiconductor device in which an AlN layer is applied prior to high-temperature heating; Fig. 11: a method for producing a semiconductor device in which initial high-temperature heating is performed prior to high-temperature heating of the getter layer. The following detailed description refers to the accompanying drawings, which form part of the disclosure and show specific embodiments for illustrative purposes. In this context, directional terminology such as "top," "bottom," "front," "back," "over," "on," "in front," "behind," "front," "back," etc., refers to the orientation of the figures just described. Since the components of the embodiments can be positioned in different orientations, the directional terminology serves only for explanation and is in no way restrictive. The description of the embodiments is not limiting, as other embodiments exist and structural or logical modifications can be made without deviating from the scope defined by the claims. In particular, elements of the embodiments described below can be combined with elements of other described embodiments, unless the context indicates otherwise. The terms "wafer" or "semiconductor substrate" used in the following description can encompass any semiconductor-based structure that has a semiconductor surface. Wafer and structure are to be understood as including doped and undoped semiconductors, epitaxial semiconductor layers, optionally supported by a substrate, and other semiconductor structures. For example, a layer of a first semiconductor material may be grown on a growth substrate of a second semiconductor material, such as a GaAs, GaN, or Si substrate, or of an insulating material, such as on a sapphire substrate. Depending on the intended use, the semiconductor can be based on a direct or an indirect semiconductor material. Examples of semiconductor materials particularly suitable for generating electromagnetic radiation include nitride semiconductor compounds, which can produce, for example, ultraviolet, blue, or longer-wavelength light, such as GaN, InGaN, AlN, AlGaN, AlGaInN, and AlGaInBN. The stoichiometric ratio of the compound semiconductor materials can vary. The term "substrate" generally includes insulating, conductive, or semiconductor substrates. In the context of the present revelation, a “sapphire substrate” is a substrate which contains sapphire, i.e., Al2O3. Fig. 1 shows a cross-sectional view of a semiconductor device 1 according to embodiments, comprising a sapphire substrate 2 and a getter layer 3 arranged thereon. The getter layer 3 consists of a compound semiconductor material containing aluminum (Al), nitrogen (N), and a transition metal (X). The getter layer material can, for example, have the composition Al1-zXzN. The transition metal (X) can, for example, be scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf). In getter layer 3, z can be greater than 0 and less than 0.2. The getter layer 3 used can be very thin, with a thickness in the range of 20 nm to 400 nm, for example, in the range of 50 nm to 300 nm. The getter layer 3 serves to prevent oxygen diffusion from the sapphire substrate 2. Furthermore, it enables lattice matching to subsequently epitaxially grown layers. The getter layer 3 can be applied, for example, by sputtering. The concentration of X can vary locally and, for example, decrease or increase from bottom to top, or assume different discrete values, for example 0-100% relative to the maximum X content z, in different areas, for example with different thicknesses. After applying the getter layer 3, high-temperature heating can be carried out, for example at a temperature greater than 1400°C and less than 2400°C. As a result, an enrichment region 8 can form between the sapphire substrate 2 and the getter layer 3. This enrichment region 8 contains not only the elements Al, N, and a transition metal X, but also an enrichment with oxygen, so that AlOXN is formed. This enrichment region 8 has a thickness 9 of a maximum of 400 nm, for example, a maximum of 300 nm. Fig. 2 shows a cross-sectional view of a semiconductor device 1 according to further embodiments, in which an additional AlN layer 4 is deposited on the getter layer 3. Here too, the getter layer 3 consists of a compound semiconductor containing aluminum (Al), nitrogen (N), and a transition metal (X). The transition metal X can be, for example, scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf). The concentration of X in getter layer 3 can be up to 20%. The getter layer 3 used can be very thin, with a thickness in the range of 20 nm to 400 nm, for example, in the range of 50 nm to 300 nm. The AlN layer 4 is located on the side of the getter layer 3 facing away from the sapphire substrate 2. The AlN layer 4 can be deposited by sputtering. The AlN layer 4 can, for example, have a thickness of 200 nm to 400 nm. After applying the getter layer 3 and the AlN layer 4, high-temperature heating can be carried out, for example at a temperature greater than 1400°C and less than 2400°C. As a result, an enrichment region 8 can form between the sapphire substrate 2 and the getter layer 3. This enrichment region 8 contains not only the elements Al, N, and a transition metal X, but also an enrichment with oxygen, so that AlOXN is formed. This enrichment region 8 has a thickness 9 of a maximum of 400 nm, for example, a maximum of 300 nm. Due to the presence of getter layer 3, oxygen diffusion from the sapphire substrate 2 into the AlN layer 4 can be suppressed. As a result, the formation of AlON contamination on the surface of the AlN layer 4 can be reduced or suppressed. Fig. 3 shows a semiconductor device 1 comprising a sapphire substrate 2 on which a layered structure is deposited. This structure includes a lower AlN layer 4, a middle getter layer 3, and an upper AlN layer 4. The getter layer 3 contains aluminum (Al), nitrogen (N), and a transition metal X and is embedded between the two AlN layers 4. The getter layer 3 can be very thin, with a thickness in the range of 20 nm to 400 nm, for example, in the range of 50 nm to 300 nm. For example, the lower AlN layer 4, the middle getter layer 3, and the upper AlN layer 4 can be deposited by sputtering. The choice of transition metal X can vary depending on specific requirements; for example, yttrium or scandium are possible, but other metals such as titanium or hafnium can also be chosen. The concentration of X in the getter layer can be up to 20%. After applying the layer structure over the sapphire substrate 2, high-temperature heating is carried out, for example at a temperature greater than 1400°C and less than 2400°C. This arrangement serves to prevent oxygen diffusion by having getter layer 3 act as an oxygen getter, thus preventing or at least reducing the formation of AlON contamination. The composition of getter layer 3, made of AlXN, can vary to ensure optimal lattice fit and crystal quality. The advantage of arranging the two AlN layers 4 with the intervening getter layer 3 is that it enables good crystal quality for the entire semiconductor device 1. As a result, semiconductor layers with a lower dislocation density can subsequently be grown epitaxially. Fig. 4 shows a semiconductor device 1 in which an AlN layer 4 is deposited on the sapphire substrate 2, which can be applied by sputtering. The AlN layer can, for example, have a thickness of 200 nm to 400 nm. The getter layer 3 follows directly on this AlN layer 4. The getter layer 3 contains aluminum (Al), nitrogen (N), and a transition metal X and serves to prevent or at least reduce oxygen diffusion and to improve the crystal quality of subsequently grown semiconductor layers. The choice of transition metal X can vary depending on specific requirements; for example, yttrium or scandium can be chosen, but other metals such as titanium or hafnium are also possible. The getter layer 3 can be very thin, with a thickness in the range of 20 nm to 400 nm, for example, 50 nm to 300 nm. After applying the layer structure over the sapphire substrate 2, high-temperature heating is carried out, for example at a temperature greater than 1400°C and less than 2400°C. The arrangement shown in Fig. 4 offers a simple structure that nevertheless effectively controls oxygen diffusion and allows for lattice matching to subsequent AlGaN layers or other epitaxially grown layers. This embodiment can be particularly advantageous when lower layer complexity is desired without compromising functionality. As a result, subsequent semiconductor layers with a lower dislocation density can be epitaxially grown. Fig. 5 shows a semiconductor device comprising a sapphire substrate 2, an AlN layer 4, a getter layer 3, and another AlN layer 4. An AlN layer 4, which can be deposited by sputtering and has a thickness of, for example, 200 nm to 400 nm, is deposited on the sapphire substrate 2. The AlN layer 4 can be deposited directly on the sapphire substrate 2. The getter layer 3, deposited on the AlN layer 4, consists of a compound semiconductor containing aluminum (Al), nitrogen (N), and a transition metal (X). The transition metal X can be scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf). The getter layer 3 can have a thickness of 20 nm to 400 nm, for example, 50 nm to 300 nm, and the concentration of X can be up to 20%. Above the getter layer 3 is another AlN layer 4, which can also be applied by sputtering. In the fabrication of the semiconductor device 1 shown in Fig. 5, after the application of the AlN layer 4 and before the application of the getter layer 3 and the further AlN layer 4, a high-temperature heating process is carried out, for example at a temperature greater than 1400°C and less than 2400°C. This high-temperature heating is also referred to as initial high-temperature heating within the scope of this disclosure. Subsequently, the getter layer 3 and the further AlN layer 4 are deposited. The entire semiconductor device 1 shown is then heated to a high temperature again. This results in layers 5 that have been heated to a high temperature once and layers 6 that have been heated to a high temperature twice. The layers 6 that have been heated to a high temperature twice consist of the sapphire substrate 2 and the directly adjacent AlN layer 4, which have already undergone an initial high-temperature heating. The further AlN layer 4, which is deposited after the getter layer 3, can have a greater thickness than the first AlN layer 4. As a result of the two high-temperature heating processes, the semiconductor device 1 can exhibit improved crystal quality, which in turn improves the quality of subsequently deposited semiconductor layers. Fig. 6 shows a semiconductor device 1 comprising a sapphire substrate 2, an AlN layer 4, a getter layer 3 and a lattice matching layer 7. A first AlN layer 4, which can be deposited by sputtering and has a thickness of 200 nm to 400 nm, is arranged on the sapphire substrate 2. This layer was subjected to initial high-temperature heating before the getter layer 3 and the further AlN layer 4 were deposited. A getter layer 3, consisting of a compound semiconductor containing aluminum (Al), nitrogen (N), and a transition metal (X), is arranged on the first AlN layer 4. The transition metal X can be scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf). The getter layer 3 can have a thickness of 20 nm to 400 nm, for example, 50 nm to 300 nm, and the concentration of X can be up to 20%. Above the getter layer 3 is another AlN layer 4, which can also be applied by sputtering. Above the AlN layer 4, a lattice-matching layer 7 can be arranged, which, like the getter layer 3, can consist of a compound semiconductor containing aluminum (Al), nitrogen (N), and a transition metal (X) (Al1-zXzN). The concentration z of the transition metal X, which can be selected independently of the transition metal chosen in the getter layer (from scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf)), can, for example, be a maximum of 20%. The concentration can be selected to achieve lattice matching with subsequent layers. The concentration of the transition metal in the lattice-matching layer 7 can differ from the concentration of the transition metal in the getter layer 3. In the production of the semiconductor device 1 shown in Fig. 6, after the application of the AlN layer 4 and before the application of the getter layer 3 and the further AlN layer 4 as well as the lattice matching layer 7, high-temperature heating is carried out, for example at a temperature greater than 1400°C and less than 2400°C. After this initial high-temperature heating, a getter layer 3, another AlN layer 4, and a lattice-matching layer 7 are deposited. The entire semiconductor device 1 shown can then be heated to a high temperature again. This results in layers 5 that have been heated to a high temperature only once and layers 6 that have been heated to a high temperature twice. The layers 6 that have been heated to a high temperature twice can include the sapphire substrate 2 and the directly adjacent AlN layer 4, which have already undergone initial high-temperature heating. The layers 5 that have been heated to a high temperature only once can include the getter layer 3, the AlN layer 4, and the lattice-matching layer 7. As a result of the two high-temperature heating processes, the semiconductor device 1 exhibits improved crystal quality, which in turn enhances the quality of subsequently deposited semiconductor layers. Furthermore, the presence of the lattice-matching layer 7 enables largely lattice-matched growth of the subsequent AlGaN layers. Fig. 7A shows a semiconductor device 1 which, in addition to the layers shown in Fig. 6, has further epitaxially grown semiconductor layers 10, 11, 12. For example, a first semiconductor layer 10 of a first conductivity type, for example n-type, a photoactive zone 11, and a second semiconductor layer 12 of a second conductivity type, for example p-type, can be arranged over the once high-temperature heated layers 5. The semiconductor layers can be compound semiconductor layers. For example, the first and / or the second semiconductor layer 10, 12 can be configured as an InxAlyGa1-x-yN layer with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, for example made of AlGaN or InGaN. The photoactive zone 11 can, for example, be configured to generate or absorb electromagnetic radiation. The semiconductor device 1 can further comprise a first contact element 21 for electrically contacting the first semiconductor layer 10.The semiconductor device 1 can further comprise a second contact element 22 for electrically contacting the second semiconductor layer 12. When a suitable voltage is applied between the first contact element 21 and the second contact element 22, holes and electrons, for example, can recombine in the region of the photoactive zone 11, emitting electromagnetic radiation 26. The generated electromagnetic radiation 26 can be emitted, for example, from a surface of the second or the first semiconductor layer 12, 10. The semiconductor device 1 shown in Fig. 7A can be an optoelectronic semiconductor component 19 and can be configured to emit or receive electromagnetic radiation 26. The semiconductor device 1 shown in Fig. 7B can have an additional semiconductor layer 13 besides the layers shown in Fig. 6. The semiconductor layer 13 can be configured as an InxAlyGa1-xA-yN layer with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, for example made of AlGaN or InGaN. Any circuit elements 25, for example transistors or others, can be configured in the semiconductor layer 13. For example, the transistors can be power transistors. For example, the semiconductor device 1 shown in Fig. 7B can be a power semiconductor device 20. This can be designed for applications in power electronics and be characterized by a capability to handle high currents and high voltages. Fig. 8A shows a semiconductor device 1 according to further embodiments, in which, in addition to the layers shown in Fig. 2, further epitaxially grown semiconductor layers, for example a first semiconductor layer 10, a photoactive zone 11 and a second semiconductor layer 12, are arranged, each fulfilling specific functions within the semiconductor device 1. The photoactive zone 11 can, for example, be configured to generate or absorb electromagnetic radiation. Analogous to the semiconductor device 1 shown in Fig. 7A, the semiconductor device 1 can further comprise a first contact element 21 and a second contact element 22. The semiconductor device 1 shown in Fig. 8A can be an optoelectronic semiconductor component 19 and can be configured to emit or receive electromagnetic radiation 26. The semiconductor device 1 shown in Fig. 8B can have an additional semiconductor layer 13 besides the layers shown in Fig. 2. The semiconductor layer 13 can be configured as an InxAlyGa1-x-yN layer with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1, for example made of AlGaN or InGaN. Any circuit elements 25, for example transistors or others, can be configured in the semiconductor layer 13. For example, the transistors can be power transistors. For example, the semiconductor device 1 shown in Fig. 7B can be a power semiconductor device 20. This can be designed for applications in power electronics and be characterized by a capability to handle high currents and high voltages. Fig. 9 shows a method for fabricating a semiconductor device, which is divided into three main steps. First, a getter layer 3 is deposited directly onto a substrate (S13). This getter layer consists of a compound semiconductor containing aluminum (Al), nitrogen (N), and a transition metal (X). The transition metal X can be scandium (Sc), yttrium (Y), titanium (Ti), or hafnium (Hf). After the getter layer is deposited, the layer is heated to a high temperature (S14) to between 1400°C and 2400°C, for example, between 1400°C and 1700°C. Then, a compound semiconductor layer is epitaxially deposited (S15), growing an InxAlyGa1-x-yN layer with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 on the getter layer. This layer can contain, for example, indium (In), aluminum (Al), gallium (Ga) and nitrogen (N) and can be applied epitaxially. Fig. 10 shows a similar process for fabricating a semiconductor device as in Fig. 9, but with an additional step. Before the getter layer S13 is applied, an AlN layer S16 is deposited onto the substrate. After the AlN layer is applied, the getter layer S13 is applied, followed by high-temperature heating S14 at a temperature greater than 1400°C and less than 2400°C. Subsequently, an epitaxial compound semiconductor layer S15 can be applied, which can be deposited onto the high-temperature heated getter layer. The additional AlN layer can further improve the crystal quality of subsequent layers and optimize the performance of the semiconductor device. Fig. 11 shows a detailed flowchart of a process for manufacturing a semiconductor device. The process begins with the deposition (S16) of an AlN layer onto a substrate. This is followed by initial temperature heating (S17) at high temperatures in the range between 1400°C and 2400°C. After initial heating to temperature, a getter layer (S13) is applied. The getter layer can consist of a compound semiconductor containing aluminum, nitrogen, and a transition metal (X). An AlN layer (S16) can then be applied. Subsequently, a lattice-fitting layer (S18) can be applied. The lattice-fitting layer contains aluminum, nitrogen, and a transition metal (X). The concentration of X in the lattice-fitting layer can differ from the concentration of X in the getter layer. X can be selected independently from scandium, yttrium, titanium, or hafnium in the getter layer and the lattice-fitting layer. High-temperature heating (14) then takes place at a temperature between 1400 °C and 2400 °C. This high-temperature heating (14) can improve the crystal structure and reduce defects. Subsequently, an epitaxial application of a compound semiconductor layer S15 can take place. Although specific embodiments have been illustrated and described herein, those skilled in the art will recognize that the specific embodiments shown and described can be replaced by a multitude of alternative and / or equivalent embodiments without departing from the scope of protection of the invention. The application is intended to cover any adaptations or variations of the specific embodiments discussed herein. Therefore, the invention is limited only by the claims and their equivalents. REFERENCE MARK LIST 1 Semiconductor device 2 Sapphire substrate 3 Getter layer 4 AlN layer 5 Single high-temperature heated layers 6 Double high-temperature heated layers 7 Lattice matching layer 8 Enrichment area 9 Thickness 10 First semiconductor layer 11 Photoactive zone 12 Second semiconductor layer 13 Semiconductor layer 19 Optoelectronic semiconductor device 20 Power semiconductor device 21 First contact element 22 Second contact element 25 Circuit element 26 Electromagnetic radiation S13 Deposition of a getter layer S14 High-temperature heating S15 Epitaxial deposition of a compound semiconductor layer S16 Deposition of an AlN layer S17 Initial temperature heating S18 Deposition of a lattice matching layer

Claims

Method for manufacturing a semiconductor device (1) comprising: depositing (S13) a getter layer (3) over a sapphire substrate (2) which is formed from a compound semiconductor material comprising Al, N and a transition metal X, and subsequently high-temperature heating (S14) of the getter layer (3) at a temperature greater than 1400°C and less than 2400°C. Method according to claim 1, wherein the high-temperature heating (S14) takes place at a temperature of 1400°C to 1800°C. Method according to claim 1 or 2, wherein after high-temperature heating (S14) a semiconductor body having an InxAlyGa1-x-yN layer with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1 is epitaxially grown over the getter layer (3) (S15). Method according to claim 3, wherein a quantity of X contained in the getter layer (3) is selected according to the lattice constant of the semiconductor body. Method according to any one of claims 1 to 4, wherein X is selected from Sc, Y, Ti and Hf. Method according to one of claims 1 to 5, wherein prior to the application (S13) of the getter layer (3) an AlN layer (4) is applied to the sapphire substrate (2). Method according to claim 6, wherein prior to the application (S13) of the getter layer (3) an initial high-temperature heating (S17) of the AlN layer (4) is carried out at a temperature greater than 1400°C and less than 2400°C. Method according to one of claims 1 to 7, wherein after the application (S13) of the getter layer (3) and before the high-temperature heating (14) of the getter layer (3) an application (S16) of an AlN layer (4) takes place. Method according to one of claims 1 to 8, wherein after the application (S13) of the getter layer (3) and before the high-temperature heating (S14) of the getter layer (3) an application (S16) of an AlN layer (4) and subsequently an application (S18) of a lattice matching layer (7) comprising Al, N and a transition metal X is carried out. Semiconductor device (1) comprising a sapphire substrate (2), an AlN layer (4) adjacent to the sapphire substrate (2) and a getter layer (3) arranged on a side of the AlN layer (4) facing away from the sapphire substrate (2), comprising Al, N, and a transition metal X. Semiconductor device (1) according to claim 10, wherein X is selected from Sc, Y, Ti and Hf. Semiconductor device (1) according to claim 10 or 11, wherein the getter layer (3) has a dislocation density of less than 5·108cm-2. Semiconductor device (1) according to one of claims 10 to 12, further comprising a semiconductor body, comprising an epitaxially grown first compound semiconductor layer (10) of InxAlyGa1-x-yN with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1. Semiconductor device (1) according to claim 13, wherein the first compound semiconductor layer (10) is of a first conductivity type, further comprising: a photoactive zone (11) for absorbing or emitting electromagnetic radiation and a second semiconductor layer (12) of a second conductivity type. Semiconductor device (1) comprising a sapphire substrate (2), a getter layer (3) adjacent to the sapphire substrate (2) comprising N, Al and a transition metal X, wherein in an enrichment region (8) of the getter layer (3) adjacent to the sapphire substrate (2) an enrichment with oxygen is formed such that AlOXN is formed. Semiconductor device (1) according to claim 15, wherein the enrichment area (8) has a thickness (9) of a maximum of 400 nm. Semiconductor device (1) according to claim 15 or 16, wherein an AlN layer (4) is arranged adjacent to the getter layer (3) on the side of the getter layer (3) facing away from the sapphire substrate (2). Semiconductor device (1) according to one of claims 15 to 17, further comprising an epitaxially grown first compound semiconductor layer (10) of InxAlyGa1-x-yN with 0 ≤ x ≤ 1, 0 ≤ y ≤ 1. Semiconductor device (1) according to one of claims 15 to 18, further comprising a photoactive zone (11) for absorbing or emitting electromagnetic radiation and a second semiconductor layer (12) of a second conductivity type. Semiconductor device (1) according to any one of claims 10 to 19, wherein the semiconductor device (1) is an optoelectronic semiconductor device or a power semiconductor device (20).

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