Method for depositing thick layers, in particular of gan, on silicon or sapphire

Abstract

The invention relates to a method for depositing a layer (13) on a substrate (12), wherein the material of the layer (13) has a different coefficient of thermal expansion and / or a different lattice constant than the substrate (12), wherein the substrate (12) is heated to an elevated temperature in a process chamber (6) of a CVD reactor (1) and, at the elevated temperature, process gases provided by a gas mixing system (18) are fed into the process chamber (6) through a gas inlet element (2), wherein the process gases in the process chamber (6) or on the surface of the substrate (12) decompose into decomposition products which form the layer (13), wherein the substrate (12) has a central portion (7) and a radially outer edge portion (8). In order to reduce the curvature of the substrate (12), the edge portion (8) is heated to a higher temperature than the central portion (7). The invention also relates to a CVD reactor having a heating device which has an outer heating zone (10) by means of which the edge portion (8) can be heated to the higher temperature.

Description

Description Methods for depositing thick layers, especially of GaN, onto silicon or sapphire field of technology

[0001] The invention relates to a method for depositing a layer onto a substrate, wherein the layer material has a different coefficient of thermal expansion and / or a different lattice constant than the substrate, the substrate being heated to an elevated temperature above 700°C or 1000°C in a process chamber of a CVD reactor, and a process gas supplied by a gas mixing system being fed into the process chamber through a gas inlet device. The process gas has at least one component, but preferably two components, which thermally decompose in the process chamber or on the surface of the substrate. The decomposition products form the layer. State of the art

[0002] WO 2022 / 049182 A2 describes a CVD reactor with a gas inlet device designed as a "showerhead" through which a multi-component process gas can be fed into a process chamber located below the gas inlet device. The bottom of the process chamber is formed by a susceptor, which can be heated to an elevated temperature by a heating device located below it. At this elevated temperature, process gases fed into the process chamber, such as ammonia and triethylgallium or trimethylgallium, decompose into decomposition products. A gallium nitride layer grows on the substrate, which consists of crystalline silicon or crystalline sapphire. The gas inlet device has a gas distribution chamber into which gases with different compositions are introduced at different points. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03Settings can be fed in, so that a different gas composition can flow into the process chamber from gas outlet openings of an edge area of ​​a gas outlet surface of the gas inlet device than in a middle area of ​​the gas outlet surface.

[0003] German patent DE 102006018514 discloses a substrate holder supported by gas cushions, wherein the gas cushion consists of several gases with different thermal conductivities. The thermal conductivity of the gas is altered by the gas composition, depending on a measured substrate temperature. By varying the gas composition, the heat transfer can differ between the center and the edge. A deviation of the substrate's edge temperature from the center temperature can lead to warping of the substrate. This warping can be compensated for by locally adjusting the heat input to the substrate, thereby reducing the temperature deviation of the edge temperature from the center temperature.

[0004] US patent 2018 / 0145052 Al discloses the deposition of GaN on a silicon substrate with a diameter of 300 mm.

[0005] EP 102011053498 Al discloses methods with which a deformation of a heated substrate can be determined.

[0006] DE 69927966 T2 discloses a CVD reactor with multiple heating zones.

[0007] DE 102012104475 Al discloses a CVD reactor with storage places for substrates arranged around a center. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0008] German patent DE 202016103834 Ul describes a heating device for a CVD reactor for heating a susceptor. The heating device has an inner heating zone and a radially surrounding outer heating zone, with which different radial sections of the susceptor can be heated to different temperatures.

[0009] US Patent 2018 / 0358221 A1 addresses the problem of large-area substrates warping when layers with a different lattice constant than the substrate are deposited on them. Such warping can be attributed to the thermal expansion of the deposited layer differing from that of the substrate. If the layer has a higher coefficient of thermal expansion than the substrate, the substrate warps convexly during deposition, with the central portion of the substrate warping upwards. If the layer has a lower coefficient of thermal expansion than the substrate, the central portion of the substrate warps downwards. For substrates heated from below and located in a process chamber with a cooled ceiling, the substrate warps concavely upon heating because the underside of the substrate is hotter than its top side.

[0010] US patents 10,714,338 B2 and 6,561,796 Bl address the problem of avoiding or reducing such curvature when depositing GaN layers on silicon or sapphire.

[0011] A warped surface on a coated substrate is disadvantageous because it complicates further processing of the substrate supporting a layer system. Ideally, a coated substrate should be flat. Warping can occur due to differing coefficients of thermal expansion between the layer and the substrate during layer deposition. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03, has the disadvantage that the deposition of thick layers is not possible. The cause of the warping is a difference in lateral forces in the layer and in the substrate. The thicker the layer, the greater the lateral force it causes and thus also the deflection or warping of the substrate. Above a certain radius of curvature, plastic deformation or fracture of the substrate occurs. The maximum layer thickness may therefore only reach values ​​that are below a critical curvature, which, for example, is 1201 / km for a 775 mm thick silicon substrate. Summary of the invention

[0012] The invention is based on the objective of providing methods for depositing non-lattice-adapted layers on substrates with large diameters, in particular with a nominal diameter of 300 mm and a standard material thickness of, for example, 775 mm. The objective is, in particular, to deposit the thickest possible buffer layer, for example made of GaN or Al, on such silicon substrates. x Gai_ x The goal is to deposit nitrogen to increase the high-voltage strength of semiconductor devices that have such a buffer layer. Another objective is to improve the layer homogeneity, even of thin films.

[0013] The problem is solved by the invention specified in the claims. The dependent claims not only represent advantageous developments of the technical teaching specified in the main claim, but also independent solutions to the problem.

[0014] First and essentially, it is proposed to design a heating device and a control device for the heating device in such a way that 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 The substrate has a mean temperature in a central region and a marginal temperature exceeding the mean temperature in a marginal region, and this horizontal or lateral temperature gradient within the substrate causes the substrate to stretch in a radial outward direction, and a layer or sequence of layers is deposited onto this prestressed substrate. It is sufficient if the prestressing of the substrate occurs only at a time when an uppermost region of the layer or sequence of layers is being deposited, i.e., in a final stage of the deposition of the layer or sequence.

[0015] An edge section of the substrate, adjacent to the preferably circular edge, is heated to a higher temperature than the central section of the substrate surrounded by the edge section. As a result, the substrate expands more in the edge section than in the central section. This leads to radially outward-directed lateral forces within the substrate. These forces counteract stresses that arise from layers deposited on the substrate with different lattice constants (lattice mismatch). Differences in the coefficients of thermal expansion of the substrate and the layers also result in a deforming force. The substrate is, in effect, stretched by the temperature difference.The higher temperature in the edge region leads to a slight increase in the substrate's diameter and thus to a radially outward stress in the central region. The substrate is preferably a single-crystal substrate. The layer is preferably a single-crystal layer.

[0016] A CVD reactor is used to carry out the process. The CVD reactor can have a housing containing a 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Process chamber. The process chamber can have a base formed by a susceptor. The susceptor can be circular disk-shaped and have a diameter greater than 300 mm. The substrate to be coated, which can have a diameter of 300 mm, but preferably at least a nominal or actual diameter of 250 mm, can be placed on this susceptor. Above the susceptor is a gas inlet element, which can be configured as a showerhead. The gas inlet element has a gas outlet surface facing the process chamber with a plurality of gas outlet openings evenly spaced across the gas outlet surface. A process gas consisting of one or more components can be fed into the process chamber through these gas outlet openings. In the exemplary embodiment, the substrate consists of silicon or sapphire.The process gas can consist of a mixture of a gallium compound and a nitrogen compound. Preferably, the process gas has a first component, for example TMGa or TEGa, which is fed into the process chamber through a first set of gas outlet openings. A second component, for example ammonia, can be fed into the process chamber through a second set of gas outlet openings. In the process chamber, the two components, which are preferably fed in separately, mix. The components decompose, so that a GaN layer is deposited on the substrate. The layer is generally a III-V layer, wherein the III component can consist in particular of Ga, Al, or In. The V component is preferably N. However, P or As is also suitable as the V component.

[0017] Below the susceptor is a heating element. This element can consist of an internal and an external resistance heater, or it can consist of an internal and an external inductive heating coil. By energizing the heating coil with an RF alternating current, [the following occurs] in the susceptor. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Eddy currents are generated that heat the susceptor. The heating device can also have several radially configured heating zones. A radially outer heating zone is essential, as it allows the susceptor to be heated to a higher temperature in a peripheral region than would be possible with a central heating zone in a central region. This enables the generation of the elevated peripheral temperature discussed above. A control device is provided that can regulate a gas mixing system, which supplies the components of the process gas, each of which is fed into the process chamber together with an inert gas, such as a noble gas, nitrogen, or hydrogen. Furthermore, the control device is capable of regulating the heating device so that the substrate receives the desired temperature profile.Sensors can be provided to measure the substrate temperature in both the edge and middle regions, or the temperature of the susceptor surface in both the edge and middle regions. One or more sensors can also be provided to detect substrate deflection. The control unit can, in particular, acquire in-situ measured data, especially regarding temperature, curvature, and reflectance. Specifically, the control unit may be able to appropriately control the temperature of the heating zones based on the in-situ data. It is also possible that the temperature on the substrate surface is not measured directly, but the heating zones are controlled based on other in-situ measured parameters. Alternatively, the control unit may have pre-determined reference data that it uses to control the heating zones.The substrate temperature and, if applicable, a susceptor temperature can be measured with a pyrometer, whereby an optical path extends from the surface of the substrate facing the process chamber through an opening in the process chamber ceiling, for example a showerhead, to an optical measuring device. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0018] The growth temperature not only influences the growth rate of the layer, particularly the GaN layer, but also its composition, for example, when the layer is doped by introducing an additional component into the process chamber. To achieve the highest possible lateral homogeneity of the layer deposited on the substrate, a different process gas mixture can be introduced through a peripheral region of the gas outlet surface of the gas inlet device than through a central region of the gas outlet surface. A suitable device for this purpose can be designed, for example, according to the aforementioned WO 2022 / 049182 A2. The different process gas composition can compensate for the aforementioned effects of the increased temperature on the layer composition and / or growth rate.

[0019] The substrate can have a material thickness of 700 to 800 µm. However, the substrate can also be considerably thicker. Silicon substrates with a thickness of 1.9 mm or sapphire substrates with a thickness of up to 2.5 mm are also suitable. The substrates can thus have a material thickness between 500 µm and 3000 µm. The material thickness can also be greater. The temperature difference between the edge section and the middle section of the substrate can be in the range of 5 K to 20 K. It is particularly intended that the temperature difference be between 2 K and 20 K, for example between 2 K and 10 K or between 5 K and 10 K. The edge temperature can be at least 5 K or 10 K higher than the middle temperature. The layer deposited on the substrate can have a layer thickness of at least 3.5 µm, preferably at least 4 µm, or also at least 4.5 µm or 5 µm.Thicker layers up to 6 g / m can be deposited on substrates with a material thickness of more than 1 mm. It is therefore specifically intended that the layer thickness be at least 4.5 g / m, 5.0 g / m, 5.5 g / m, or 6.0 g / m. The radial extent. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 The width of the edge area can be between 2 cm and 3 cm if the substrate has a nominal diameter of 300 mm. Generally, the width of the edge area can be between 10% and 20% of the radius of the substrate. However, it is also possible for the width of the edge area to be less than 10% of the radius. The width of the edge area can be between 3% and 10% of the radius.

[0020] The invention further relates to a coated substrate, wherein the substrate consists of silicon or sapphire and the layer is an aluminum alloy. x Gai- xThe substrate is a GaN layer or a GaN layer that is at least 3.5 gm, 4 gm, 4.5 gm, 5 gm, or 6 gm thick, wherein the substrate has a nominal diameter of 300 mm and a material thickness in the range of 700 gm and 800 gm. The layer is preferably deposited using the previously described method in a previously described apparatus, wherein a layer thickness of at least 4 gm may be sufficient for power electronics applications up to 650 V. Greater layer thicknesses, for example, layer thicknesses above 6 pm, increase the dielectric strength to values ​​above 1200 V.

[0021] According to a further development of the invention, the surface temperature of the substrate, which can be measured from the process chamber ceiling using a pyrometer, increases continuously from the center to the edge section and preferably also within the edge section. The temperature gradient (K / cm) in the radial direction is preferably always greater than 0. Several temperature measuring devices, particularly optical ones, can be provided with which the temperature of the surface of the substrate facing the process chamber or of the layer deposited on the substrate is measured. In a preferred embodiment, the surface temperature is measured at several radially offset locations. One of these temperatures can be used to control the heating device. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 to control such that this temperature, or an averaged temperature of several temperatures measured on the surface of the substrate, is maintained at a constant value. The different measuring points at which the surface temperature is measured may have a radially outermost measuring point located within an outermost boundary zone, the radial width of which is approximately 6% of the radius of the substrate, wherein the substrate preferably has a nominal diameter of 300 mm, i.e., a radius of 150 mm. This boundary zone then preferably has a width of no more than 9 mm.

[0022] The temperature difference between the temperature at the hottest point of the substrate and the temperature at the outermost edge of the substrate is smaller than the temperature difference between the temperature at the hottest point of the substrate and the average temperature. The ratio of these two temperature differences is less than 0.2 or 0.1, or preferably less than 0.05.

[0023] The heating element is preferably arranged below a susceptor, which may have a circular disk shape. On its upper surface, the susceptor has a bearing area for preferably a single substrate, which is also circular disk-shaped. The susceptor and substrate are arranged coaxially to each other, such that the edge of the substrate is spaced substantially equally from the edge of the susceptor around its entire circumference. The inner heating zone of the heating element heats the area surrounding the center of the susceptor. An outer heating zone heats the edge of the susceptor. The outer heating zone is arranged coaxially to the inner heating zone.

[0024] The heating device or the control system of the heating device can be set up in such a way that the surface temperature of the substrate 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 in a peripheral zone whose radial width is less than 3% of the radius, sloping down from a hottest point. The hottest point of the substrate can therefore be located away from the substrate's edge. However, it should lie within an annular area whose width is at least 6% of the radius.

[0025] The process is preferably carried out in a process chamber with a height of less than 30 mm, 20 mm, or 15 mm; the process chamber height can be approximately 11 mm. The process chamber height is the distance between a downward-bounding surface, such as a susceptor, and a surface bounding the process chamber upwards, such as a shielding plate or the gas outlet surface of a showerhead. However, the process can also be carried out in a process chamber with a significantly greater height. In the first case, it can be advantageous if the gas phase composition in the process chamber differs at various radial positions. This makes it possible to locally influence the layer growth with respect to a growth rate and / or layer composition by selectively introducing one of the reactive gases at a location radially offset from the center.

[0026] The gas inlet of a CVD reactor used to carry out the process has a showerhead gas outlet surface that extends essentially across the entire surface of the substrate. Typically, gas streams with the same composition exit into the process chamber through gas outlet openings evenly distributed across this surface. However, it is also possible to introduce different gas mixtures into the process chamber at different radial positions, so that the supply of reactive gases, which influence the growth rate or the layer composition, changes in the radial direction. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0027] The latter proves particularly advantageous if the deposited layer or one of several deposited layers of a layer sequence is a ternary or quaternary compound, or if one of the layers is doped with a dopant.

[0028] In a preferred embodiment, the susceptor, which supports the substrate, may further be provided with a diameter only slightly larger than that of the substrate, such that the center of the substrate coincides with the center of the circular susceptor and the center of the multiple heating zones. It may also be provided that the edge of the substrate rests on a support structure, allowing the central section of the substrate to float freely above a surface of the susceptor. The support structure may consist of several individual projections arranged along a circular arc around the center of the susceptor or a bearing area. Alternatively, the support structure may be formed by a single annular projection. In this case, the center of the substrate can curve not only upwards, towards a cooled process chamber ceiling, but also downwards towards the heating element or the susceptor.

[0029] It is possible to influence layer growth or composition solely through a horizontal temperature gradient within the substrate, thereby increasing the growth rate or layer composition and achieving greater horizontal homogeneity. For this purpose, the substrate is stretched only to the point where a residual warp remains, but this warp is insufficient to cause substrate fracture. Instead, areas of the substrate remain that have a reduced distance to the cooled process chamber ceiling or a increased distance to the outer susceptor, resulting in slightly lower temperatures during deposition. Alternatively, or 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Additionally, as previously explained, the composition of the gas phase can be influenced, thus increasing the growth rate in the marginal area.

[0030] The invention further relates to a CVD reactor for carrying out the process, wherein the CVD reactor has a circular disk-shaped susceptor whose diameter is only slightly larger than the diameter of the substrate, which has a nominal diameter of 300 mm. The susceptor has a circular disk-shaped storage area for the substrate, the diameter of which is only slightly larger than the diameter of the substrate and only slightly smaller than the diameter of the susceptor. Above the susceptor is a process chamber, the ceiling of which is formed by a gas outlet surface of a gas inlet device. A plurality of gas outlet openings are arranged in the gas outlet surface, through which the various components of the process gas can preferably be fed separately into the process chamber.Preferably, the gas outlet surface has gas outlet openings in a radially outer region through which a process gas can be introduced, the composition of which differs from the process gas that can be introduced into the process chamber through gas outlet openings located in a central region of the gas outlet surface. The heating device has at least two radially nested heating zones. An inner heating zone can be used to heat a central region of the susceptor. A peripheral heating zone can be used to heat a peripheral region of the susceptor to a slightly elevated temperature. A control device regulates the heating elements for heating the heating zones. An intermediate zone can be arranged between the radially outer heating zone and the central heating zone, which can be controlled separately by the control device.The control unit is also capable of controlling the valves and mass flow regulators of the gas mixing system. This allows for the adjustment of the various process gas compositions. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Control unit is set up / programmed to carry out the procedure described above, in particular according to a recipe.

[0031] The heating element is preferably located below the circular susceptor, on which a circular substrate rests coaxially with the center of the susceptor. The substrate thus forms the floor of the process chamber. The ceiling of the process chamber is formed by the gas outlet surface of a showerhead or a shielding plate arranged below it, which has gas passage openings. Since the gas outlet surface is cooled, a vertical temperature gradient forms within the process chamber.

[0032] Radial stress within the substrate can improve layer deposition not only in heteroepitaxy, where the substrate and the layer(s) consist of different materials, but also in homoepitaxy, where the substrate and layer(s) consist of the same material. This method is particularly advantageous for depositing GaN layers with a thickness greater than 6 g / m on a Si substrate with a material thickness of 775 g / m and a diameter of 300 mm. By superheating the substrate at its edges, any warping of the substrate can be reduced to a minimal residual warping, allowing different areas of the substrate to be selectively positioned at varying distances from the susceptor. The growth rate or layer composition can also be influenced by a vertical temperature gradient in the process chamber above the substrate.The temperature difference between the center temperature and the edge temperature can be between 10 K and 15 K. This method is therefore also advantageous for the deposition of thin films, as it allows for a higher degree of homogeneity in the film composition. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0033] The invention further relates to a method for determining the temperature difference. For this purpose, test layers with different thicknesses and different temperature differences between the edge section and the middle section of the substrate are deposited on different substrates in preliminary tests. The deflection of the substrate is measured in each case using a sensor. This allows an optimum temperature difference between the edge section and the middle section of the substrate to be determined.

[0034] The invention further relates to an electronic component that is deposited on a substrate, wherein the substrate is preferably a silicon substrate with a (111) surface. A buffer layer, for example an aluminum oxide layer, is deposited on the substrate. x Gai_ xAn N-layer or a GaN layer is deposited, the thickness of which is at least 3.5 gm, 4 gm, 4.5 gm, 5 gm, 5.5 gm, or at least 6.0 gm and which can also consist of several sublayers, i.e., a layer sequence. An active layer or an active layer sequence with a thickness, for example, between 10 and 30 nm, and in particular of approximately 20 nm, is deposited on this. The active layer is preferably an AlGaN layer and forms a transistor with a HEMT geometry. A source contact, a gate contact, and a drain contact are applied to the active layer. The gate length is approximately 1 gm. The gate width is approximately 50 gm. However, the gate width can also be significantly larger, ranging from 1 to 2 mm. The source-drain distance is less than 5 m. Such a high-performance GaN application has a voltage withstand capability of over 650 V, up to 800 V, or over 1200 V.The component in question is a transistor, which may be housed in its own package or be part of an integrated circuit. Alternatively, the component may be part of a component array mounted on a printed circuit board. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Brief description of the drawings

[0035] An embodiment of the invention is explained below with reference to the accompanying drawings. These show: Fig. 1 schematically shows a CVD reactor according to the invention, Fig. 2 schematically shows the concave curvature of a substrate 12 when the substrate 12 is heated in a process chamber 6 of the CVD reactor 1, Fig. 3 shows the course of a substrate temperature by a line drawn through the center of the substrate during the execution of the method according to the invention. Fig. 4 shows a substrate 12 resting on a susceptor 11 with a layer 13 deposited on it. Fig. 5 enlarges the section V in Figure 4 to illustrate the force directions 14, 15 within the layer 13 and the substrate 12 during the deposition of the layer 13. Fig. 6 shows a substrate that convexly curves during the deposition of layer 13, Fig. 7 shows a top view of a substrate 12 to illustrate the radially outward directed forces 16, Fig. 8 schematically shows the course of a bulge in a substrate according to the prior art (dashed line) and according to the 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Invention (solid line) during heating of the substrate (phase A), during deposition of a layer (phase B) and during cooling (phase C), Fig. 9 shows a representation according to Figure 3 of a further embodiment, Fig. 10 shows a representation according to Figure 3 of a further embodiment, Fig. 11 shows a representation similar to Figure 2 of another embodiment, Fig. 12 schematically shows the cross-section of a semiconductor device in the form of a normally open field-effect transistor, Fig. 13 schematically shows the cross-section of a semiconductor device in the form of a normally closed field-effect transistor. Description of the embodiments

[0036] The CVD reactor 1, schematically depicted in Figure 1, has a gas-tight housing, for example made of stainless steel. Inside the housing is a circular disk-shaped susceptor 11, for example made of graphite or coated graphite. Below the susceptor 11 is a heating device, which in this embodiment is a resistance heater. However, the use of an RF heater is also possible. The heating device has several radially nested heating zones. A central heating zone 9 is formed by a first spiral heating coil, which is controlled by a control unit 17. A second heating element extends around the central heating zone 9. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 An intermediate heating zone 10' is formed by an annular heating coil. An outer heating zone 10 extends around the intermediate heating zone 10' and is located below the edge of the susceptor 11. The radial area with which the outer heating zone 10 can heat the susceptor 11 has an extent of 2 cm to 3 cm. The diameter of the susceptor is slightly greater than 300 mm.

[0037] The upper surface of the susceptor 11 forms a support for a disk-shaped substrate 12. The rim 12' of the substrate 12 runs above a rim 11' of the susceptor 11.

[0038] A process chamber 6 extends above the susceptor 11. The process chamber 6 is bounded at the top by a gas outlet surface 20 of a gas inlet device 2. A number of gas outlet openings 3 are located in the gas outlet surface 20. Process gas from gas distribution chambers 4, 5 of the gas inlet device 2 can flow into the process chamber 6 through the gas outlet openings 3. The gas inlet device 2 has a cooling device (not shown) with which the gas outlet surface 20 can be cooled, so that a vertical temperature gradient can form between the susceptor 11 and the gas outlet surface.

[0039] In the exemplary embodiment, several gas distribution chambers 4, 5 are schematically shown, through which different process gases can flow into the process chamber 6. Not shown is a further subdivision of the gas distribution chambers 4, 5, so that two different components of the process gas can be fed separately into the process chamber 6. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0040] The process gases are supplied by a gas mixing system 18 (not shown), which includes valves and mass flow controllers controlled by a control program from the control unit 17. The control program also controls the heating zones 9, 10, 10' of the heating unit.

[0041] Figure 2 schematically shows the tendency of a substrate 12, which is heated in the process chamber 2. Due to the aforementioned temperature gradient, the underside of the substrate 12 heats up to a higher temperature than the top side. As a result, the substrate 12 warps concavely during the heating phase. This is shown in Figure 8 as phase A.

[0042] If a layer 13 is deposited onto the substrate 12, and this layer has a different lattice constant than the substrate 12, or a different coefficient of thermal expansion, a lateral force arises, as illustrated in Figure 5 for a system consisting of a silicon substrate 12 and a GaN layer 13. At the deposition temperature, the layer 13 has a different lattice constant than the substrate 12, resulting in a lateral force 14 acting radially outward in the layer 13. This force can also be influenced by the different coefficients of thermal expansion of the layer and the substrate.

[0043] A force direction 15 forms in the substrate in the opposite direction. This leads to a torque that causes a convex curvature of the substrate 12.

[0044] Figure 8 shows how, in phase B, this torque causes the initially concave curvature to reverse, and the substrate 12 subsequently curves convexly. This is indicated by a dashed line. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Curvature behavior of a substrate in a prior art process is shown, in which the substrate is heated to a homogeneous lateral temperature. At point E', the curvature reaches a limit, which may, for example, be above 1201 / km. Here, the substrate can plastically deform or break.

[0045] In the method according to the invention, the edge region 8 of the substrate 12 is heated to a higher temperature than the central region 7 of the substrate 12. As a result, a radial force field forms within the substrate 12. The force directions are shown by arrows 16 in Figure 7.

[0046] As a result, the substrate 12 receives an additional radial stress acting in the same direction as the force direction 14 within the layer 13. This leads to a reduction in the convex curvature of the substrate, as shown in Figure 6. Consequently, at the end of phase B, during which the layer 13 is deposited, the layer does not reach point E', but rather point E with a smaller convex curvature. It is therefore possible to deposit a layer with a greater thickness without reaching the critical curvature. According to the invention, it is thus possible to deposit a gallium nitride layer 13 on a silicon substrate 12, which has a thickness of at least 3.5 g / m, preferably even more than 4.0 g / m, 4.5 g / m, 5.0 g / m, 5.5 g / m, or 6.0 g / m.

[0047] In phase C, the substrate is cooled, with the layer exhibiting a higher coefficient of thermal expansion than the substrate itself. This causes the convex curvature to decrease to a minimum or even to a slight concave curvature. The substrate is optimally flat when room temperature is reached (point F). 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0048] The temperature of the substrate 12 in the edge region 8, which increases by 5 K to 20 K, preferably by about 10 K, alters the growth rate of the layer and / or the layer composition. To counteract this effect, a process gas can be fed into the process chamber 6 from the gas outlet openings 3 located above the edge section 8 of the substrate 12 or slightly radially offset from it. This process gas differs in composition from the process gas fed into the region of the process chamber 6 located above the central section 7. This compensates for the effects caused by the higher temperature.

[0049] The change in the material composition of the layer or in the growth rate caused by the increased edge temperature of the substrate 12 cannot only be compensated by feeding process gases with different concentrations of a reactive gas into radially offset gas distribution chambers 4, 5.

[0050] The reference number 8' represents an intermediate section extending between the central section 7 and the outer section 8. A further heating zone 10' may extend below this intermediate section 8'.

[0051] Figure 9 shows the influence of a differently controlled or designed heating device with heating zones 10, 10'. Here, the substrate temperature rises continuously from a central temperature TM with a temperature gradient greater than 0 from the center to the edge, where the substrate temperature reaches an edge temperature TR, which forms the hottest point H. Accordingly, a uniform internal stress acting radially builds up within the substrate 12. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0052] Figure 10 shows the effect of a differently controlled or designed heating device. Here, too, the substrate temperature rises steadily from a central temperature TM towards the edge. However, here the hottest point H, i.e., the position where the substrate surface temperature reaches the edge temperature TR, is located somewhat away from the edge of the substrate 12 towards the center. Radially outside the hottest point, the surface temperature decreases slightly.

[0053] Figure 11 shows another embodiment. Here, the susceptor 11 has a support structure 21 in the region of its edge. The susceptor 11 can be circular in shape. The support structure 21 can be formed by many projections arranged along a circular arc. However, the support structure 21 can also be a continuous ring. The outermost edge of the substrate 12 rests on the support structure 21. The radially enclosed portion of the substrate 12 within the support structure 21 is, in effect, suspended above the upper surface 22 of the susceptor 11. In this embodiment, the substrate 12 can curve downwards without the central section 7 touching the upper surface 22. Even in the curved state, the edge section 8 of the substrate remains in contact with the support structure 21.The ring can also form a bearing surface for the substrate 12, at least partially surrounded by a supporting shoulder, on which only the edge 12' of the substrate rests. This edge 12' is then surrounded by the supporting shoulder, which centers the substrate on the susceptor 11.

[0054] A CVD reactor 1, in which the previously described process is carried out, has a susceptor 11 which is heated, in particular from below, by a heating device 10, 10'. The susceptor 11 is a heat source. Heat is transferred from the susceptor to a cooled ceiling of the process chamber 6. The CVD reactor 1 according to the invention is designed to produce exactly one 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Substrate 12 is to be coated simultaneously. The substrate 12 covers more than 80% or 90% of the surface of the susceptor 11 and thus forms, in a sense, the floor of the process chamber 6. A vertical temperature gradient forms between the surface of the substrate 11 and the cooled ceiling of the process chamber, which, in the embodiment shown in Figure 1, is formed by a gas outlet surface of a showerhead. The showerhead has one or more gas distribution chambers, which are connected via tubes with openings in a gas outlet surface. The tubes cross a cooling chamber through which a cooling fluid flows, and which is directly adjacent to a base plate that forms the gas outlet surface. The temperature decreases from the top of the susceptor 11 or the top of the substrate 12 with increasing distance from the susceptor 11.This means that in the embodiment shown in Figure 2 - assuming that the top of the susceptor 11 has the same temperature everywhere - the edge 12' of the substrate 12 has a lower temperature than the middle section 7, which is curved downwards.

[0055] In the embodiment shown in Figure 6, the central section 7 has a higher temperature than the outer section 8 because the central section 7 is curved upwards. The vertical temperature gradient is greater in the central section 7 than in the outer section 8. The growth rate, or layer composition, is directly related to the temperature gradient. The greater the temperature gradient, the greater the growth rate. To achieve a growth rate that is as independent of position as possible—a prerequisite for the layer deposited on the substrate to have the same thickness at every point—the outer section 8 can be heated more than is necessary to clamp the substrate 11, for example, to a temperature of 15 K instead of 10 K. Preliminary tests can determine by how many degrees the outer temperature TR must be higher than the central temperature TM to achieve this. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 The growth rate of the layer is approximately the same at every point on the substrate. The target parameter is therefore a uniform growth rate or layer composition across the entire surface of the substrate.

[0056] Alternatively, the mass flow of the reactive gas flowing into the process chamber through the gas outlet openings can also increase radially away from the center in order to locally increase the growth rate.

[0057] Figures 12 and 13 schematically show a cross-section through a component produced by the inventive method. In the method, a large-area substrate 12 is first placed in a process chamber 6 of a CVD reactor. The substrate consists of silicon and preferably has a nominal diameter of 300 mm and a thickness of 775 mm. The substrate is first heated. The heating zones 9, 10, 10' are controlled by a control device 17 such that the edge temperature TR of the substrate is 1210 K to 15 K higher than the center temperature TM, or in other embodiments, at least 3 K higher. A buffer layer 31 or layer sequence of GaN is deposited onto the substrate 12. In a further process step, an active layer 32 or layer sequence of AlxGai-xN is deposited onto this buffer layer 31.

[0058] The coated substrate is removed from the process chamber 6. Before or after the substrate 12 is divided into individual elements, from which the semiconductor devices 30 are later manufactured, the top surface of the active layer 32 is provided with a source contact 34, a gate contact 35, and a drain contact 36. A dielectric passivation layer 37, for example made of SiN, can also be present between the contacts 34 to 36. The deposition of the passivation layer 37 can be carried out in the same 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 Process chamber in which the other layers 31, 32 have been deposited. The passivation layer 37 is then subsequently structured. The active layer 32 has a thickness of, for example, 20 nm such that a two-dimensional electron gas 33 forms under the gate electrode 35 near the interface with the active layer 32 in the buffer layer 31, so that this transistor is normally conducting. The buffer layer 31 preferably has a thickness of at least 6 µm. The length of the gate electrode can be less than 1 gm. The width of the gate electrode can be between 50 gm and several millimeters. The distance between the source electrode 34 and the drain electrode 36 is typically less than 5 m.

[0059] The embodiment shown in Figure 13 differs from the embodiment shown in Figure 12 essentially only by the additional p-doped layer of GaN 38 between the gate electrode 35 and the active layer 32. As a result of this structure, the transistor shown in Figure 13 is normally closed. Only a two-dimensional electron gas 33 forms under the gate electrode 35 when a voltage is applied to the gate electrode 35.

[0060] The component shown in Figures 12 or 13 can be arranged in a housing. It can be part of an integrated circuit. However, the component can also be part of an electronic circuit that includes a printed circuit board with other components mounted on it.

[0061] The invention therefore also relates to a component that has a housing or an integrated circuit or a printed circuit board.

[0062] The foregoing statements serve to explain the inventions covered by the application as a whole, which represent the state of the art. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 at least through the following combinations of features, each of which can also be further developed independently, whereby two, several or all of these combinations of features can also be combined, namely:

[0063] A method characterized in that the substrate 12 is stretched in a radial outward direction in a final phase of the deposition of the layer 13 or the layer sequence by an edge temperature TR exceeding the mean temperature TM and the layer 13 or at least an uppermost region of the layer 13 or the layer sequence is deposited onto the substrate 12 thus stretched.

[0064] A method characterized in that the material of layer 13 has a different coefficient of thermal expansion and / or a different lattice constant than the substrate 12.

[0065] A method characterized in that the substrate 12 rests on a susceptor 11 which is heated by a heating device having an inner heating zone 9 and an outer heating zone 10, wherein the heating zones 9, 10 are controlled by a control device 17.

[0066] A method characterized in that the disk-shaped substrate 12 rests on a disk-shaped susceptor 11 in a coaxial arrangement such that the edge 12' of the substrate extends substantially equidistant from the edge 11' of the susceptor 11 over its entire circumference, wherein the susceptor 11 is heated by a heating device controlled by a control device 17, the heating device having an inner heating zone 9 with which a central region of the susceptor 11 extending around its center is heated, and an outer 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 has heating zone 10 extending along the edge 11' of susceptor 10.

[0067] A method characterized in that the gas inlet element 2 has gas outlet openings 3 which open into the process chamber 6 above the substrate 12, through which the process gas is fed into the process chamber 6, wherein the control device 17 is configured to control the gas mixing system 18 such that a process gas with a different gas composition flows into the process chamber 6 from gas outlet openings 3 arranged above the middle section 7 than from gas outlet openings 3 arranged above the edge section 8, wherein the gas compositions are selected such that a different growth rate or layer composition in the edge section 8 compared to the middle section 7 caused by the higher temperature of the edge section 8 is compensated.

[0068] A method characterized in that the substrate consists of sapphire or silicon, has a diameter of at least 250 mm, and the layer is made of Al x Ga y N exists, where x + y = 1 and x + y can each have values ​​from 0 to 1, where the layer thickness of the layer is at least 3.5 |im, 4.0 |im, 4.5 pm, 5.0 pm, 5.5 pm or 6.0 gm or that the layer is an AlInGaN layer.

[0069] A method characterized in that the radial extent of the edge section 8 is between 2 cm and 3 cm and / or that the radial extent of the edge section 8 is in the range between 10% and 20% of the radius of the substrate 12 or is less than 10% of the radius and / or that the hottest spot (H) of the substrate surface is located in an edge section (8) whose width is between 3% and 10% of the radius of the substrate (12). 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0070] A method characterized in that the elevated temperature is at least 700°C and the edge section 8 is heated to a temperature that is between 2 K and 20 K or 2 K and 10 K or 5 K and 10 K or 5 K and 20 K higher than the temperature of the middle section 7.

[0071] A method characterized in that the heating device has an intermediate heating zone 10' arranged between the inner heating zone 9 and the outer heating zone 10.

[0072] A method characterized in that the temperature difference between the temperature of the middle section 7 and the edge section 8 is varied during the heating of the substrate 12 to the increased temperature and / or during the deposition of the layer 13.

[0073] A method characterized in that a deflection of the substrate 12 is determined by means of a sensor 19 during the heating of the substrate 12 to the increased temperature and / or during the deposition of the layer 13.

[0074] A method characterized in that the temperature of the substrate 12 decreases from a hottest point H, which is located in an outermost edge section 8 of the substrate 12, which is at most 3% of the radius of the substrate 12, in a radially outward direction to the edge of the substrate 12.

[0075] A method characterized in that the temperature of the substrate 12 increases from a lowest value T in the middle of the substrate 12 with a slope that is greater than OK / cm at every point along a path from the center to the hottest point H. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

[0076] A method for manufacturing a component, wherein a silicon substrate 12 with a diameter of 300 mm and a material thickness of 775 mm is first coated with a GaN layer 31 or layer sequence having a layer thickness of at least 6 gm according to a method according to claims 1 to 13, wherein an active layer 32 or layer sequence of AlxGai-xN is deposited onto a GaN layer 31 or layer sequence, having a thickness between 10 nm and 30 nm and preferably 20 nm, wherein a source contact 34, a gate contact 35 and a drain contact 36 is applied to the active layer 32 or layer sequence, wherein the coated substrate is cut before or after the application of the contacts 34, 35, 36, 37 and the parts are arranged in a housing, on a printed circuit board or in an integrated circuit.

[0077] A method characterized in that in preliminary tests one or more layers 13 are deposited on a substrate 12 and the temperature difference between the temperature in the middle section 7 and in the edge section 8 assumes different values.

[0078] A substrate characterized in that the diameter of the substrate 12 is at least 250 mm or 300 mm and the layer 13 is at least 3.5 gm, 4 mm, 4.5 gm, 5.0 gm, 5.5 gm or 6.0 gm thick.

[0079] A CVD reactor characterized in that the control device 17 is configured such that during the deposition of a layer 13 on the substrate 12 the edge 11' of the susceptor 11 is heated to a higher temperature than a central region of the susceptor 11.

[0080] A CVD reactor characterized in that the control device 17 is configured through the gas outlet openings 3, which are located in a 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 radially arranged outer area of ​​the gas outlet surface 20, to feed a process gas into the process chamber 6 which has a different composition than that which flows through gas outlet openings 3 which are arranged in the middle area of ​​the substantially circular gas outlet surface 20.

[0081] All disclosed features are essential to the invention (individually, but also in combination with one another). The disclosure of this application hereby incorporates in full the disclosure content of the associated / attached priority documents (copy of the earlier application), also for the purpose of including features of these documents in the claims of the present application. The dependent claims, even without the features of a referenced claim, characterize independent inventive developments of the prior art, in particular for the purpose of filing divisional applications based on these claims. The invention specified in each claim may additionally include one or more of the features described above, in particular those identified by reference numerals and / or listed in the reference numeral list.The invention also relates to design forms in which individual features mentioned in the preceding description are not realized, in particular insofar as they are recognizably unnecessary for the respective purpose or can be replaced by other technically equivalent means. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03 List of reference marks 1 CVD reactor 22 Top side 2 Gas inlet 30 Semiconductor component 3 Gas outlet 31 GaN buffer layer 4 Gas distribution chamber 32 active layer Al x G x -iN 5 Gas distribution chamber 33 two-dimensional electrical 6 process chamber nengas 7 middle section 34 source contact 8 edge section 35 gate contact 8' Intermediate section 36 Drain contact 9 inner heating zone 37 dielectrode, passivation 10 outer heating zone layer 10' heating zone 38 p-layer 11 Susceptor 11' Rand 11" middle area H hottest spot 12 Substrate TM center temperature 12' Edge TR Edge temperature 12" medium range 13 layers 14 Direction of force 15 Direction of force 16 Direction of force 17 Control unit 18 Gas mixing system 19 Sensor 20 Gas outlet area 21 Support structure 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

Claims

32 / 38 Claims 1. Method for depositing a layer (13) or sequence of layers on a substrate (12), wherein the substrate (12) is heated to an elevated temperature in a process chamber (6) of a CVD reactor (1) and process gases supplied by a gas mixing system (18) at the elevated temperature are fed into the process chamber (6) through a gas inlet device (2), wherein the process gases decompose in the process chamber (6) or on the surface of the substrate (12) into decomposition products which form the layer (13) or layer sequence, wherein the substrate (12) has a central section (7) which is heated to a central temperature (TM) and a radially outer edge section (8) which is heated to an edge temperature (TR), characterized in thatthat the substrate (12) is stretched in a radial outward direction in a final phase of the deposition of the layer (13) or the layer sequence by an edge temperature (TR) exceeding the mean temperature (TM) and the layer (13) or at least an uppermost region of the layer (13) or the layer sequence is deposited onto the substrate (12) thus stretched.

2. Method according to claim 1, characterized in that the material of the layer (13) has a different coefficient of thermal expansion and / or a different lattice constant than the substrate (12).

3. Method according to claim 1 or 2, characterized in that the substrate (12) rests on a susceptor (11) which is heated by a heating device having an inner heating zone (9) and an outer heating zone (10), wherein the heating zones (9, 10) are controlled by a control device (17). 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-034. Method according to one of the preceding claims, characterized in that the circular disk-shaped substrate (12) rests in a coaxial arrangement on a circular disk-shaped susceptor (11) such that the edge (12') of the substrate extends substantially equidistant from the edge (11') of the susceptor (11) over its entire circumference, wherein the susceptor (11) is heated by a heating device controlled by a control device (17), wherein the heating device has an inner heating zone (9) with which a central region of the susceptor (11) extending around the center of the susceptor (11) is heated, and has an outer heating zone (10) extending along the edge (11') of the susceptor (10).

5. A method according to one of the preceding claims, characterized in that the gas inlet element (2) has gas outlet openings (3) which open into the process chamber (6) above the substrate (12), through which the process gas is fed into the process chamber (6), wherein the control device (17) is configured to control the gas mixing system (18) such that a process gas with a different gas composition flows into the process chamber (6) from gas outlet openings (3) arranged above the middle section (7) than from gas outlet openings (3) arranged above the edge section (8), wherein the gas compositions are selected such that a different growth rate or layer composition in the edge section (8) compared to the middle section (7) caused by the higher temperature of the edge section (8) is compensated.

6. Method according to one of the preceding claims, characterized in that the substrate consists of sapphire or silicon, has a diameter of at least 250 mm, in particular a diameter of 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03300 mm and the layer made of Al x Ga y N exists, where x + y = 1 and x + y can each have values ​​from 0 to 1, where the layer thickness of the layer is at least 3.5 |im, 4.0 |im, 4.5 |im, 5.0 |im, 5.5 |im or 6.0 |im or that the layer is an AlInGaN layer.

7. Method according to claim 6, characterized in that the radial extent of the edge section (8) is between 2 cm and 3 cm and / or that the radial extent of the edge section (8) is in the range between 10% and 20% of the radius of the substrate (12) or is less than 10% of the radius and / or that the hottest spot (H) of the substrate surface is located in an edge section (8) whose width is between 3% and 10% of the radius of the substrate (12).

8. Method according to one of the preceding claims, characterized in that the increased temperature is at least 700°C and the edge section (8) is heated to a temperature that is between 2 K and 20 K or 2 K and 10 K or 5 K and 10 K or 5 K and 20 K higher than the temperature of the middle section (7).

9. Method according to one of claims 3 to 8, characterized in that the heating device has an intermediate heating zone (10') arranged between the inner heating zone (9) and the outer heating zone (10).

10. Method according to one of the preceding claims, characterized in that the temperature difference between the temperature of the middle section (7) and the edge section (8) is varied during heating of the substrate (12) to the increased temperature and / or during deposition of the layer (13). 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-0311. Method according to one of the preceding claims, characterized in that a deflection of the substrate (12) is determined by means of a sensor (19) during the heating of the substrate (12) to the increased temperature and / or during the deposition of the layer (13).

12. Method according to one of the preceding claims, characterized in that the temperature of the substrate (12) decreases from a hottest point (H) located in an outermost edge section (8) of the substrate (12) which is at most 3% of the radius of the substrate (12) in a radially outward direction to the edge of the substrate (12).

13. Method according to one of the preceding claims, characterized in that the temperature of the substrate (12) increases from a lowest value (T) in the middle of the substrate (12) with a slope that is greater than OK / cm at every point along a line from the center to the hottest point (H) towards the edge.

14. Method for manufacturing a component, wherein a silicon substrate (12) with a diameter of 300 mm and a material thickness of 775 µm is first coated with a GaN layer (31) or layer sequence having a layer thickness of at least 4 µm, 4.5 gm, 5 gm, 5.5 gm or 6 gm according to a method according to claims 1 to 13, wherein an active layer (32) or layer sequence of AlxGai-xN is deposited onto a GaN layer (31) or layer sequence, having a thickness between 10 nm and 30 nm and preferably 20 nm, wherein a source contact (34), a gate contact (35) and a drain contact (36) are applied to the active layer (32) or layer sequence, wherein the coated substrate is coated before or after the application of the contacts (34, 35, 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-0336 / 38 36, 37) is divided and the parts are arranged in a housing, on a printed circuit board or in an integrated circuit.

15. Method for determining values ​​for the temperature difference between the outer edge section (8) and the middle section (7) for carrying out a method according to one of the preceding claims, characterized in that in preliminary tests one or more layers (13) are deposited on a substrate (12) and the temperature difference between the temperature in the middle section (7) and in the edge section (8) assumes different values.

16. Substrate (12) with a layer (13) deposited thereon, wherein the layer (13) consists of GaN, AlGaN or AUnGaN and the substrate (12) consists of silicon or sapphire, characterized in that the diameter of the substrate (12) is at least 250 mm or 300 mm and the layer (13) is at least 3.5 gm, 4 gm, 4.5 gm, 5.0 gm, 5.5 mm or 6.0 gm thick.

17. CVD reactor with a susceptor (11) which can be heated from below by a heating device, wherein the heating device has at least one inner heating zone (9) and one outer heating zone (10) which can be controlled by a control device (17), wherein the susceptor (11) has a storage space for a substrate (12) such that an edge (12') of the substrate (12) extending along a circular arc line lies on an edge (11') of the susceptor (11), wherein the outer heating zone (10) essentially heats only the edge (11') of the susceptor (11) and the inner heating zone (9) essentially heats only a central region of the susceptor, with a gas inlet device (2) having a gas outlet surface (20) which 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-0337 / 38 a plurality of gas outlet openings (3) through which a process gas consisting of several components can be fed into a process chamber (6) arranged between the gas outlet surface and the susceptor (11), characterized in that the control device (17) is set up such that during the deposition of a layer (13) on the substrate (12) the edge (11') of the susceptor (11) is heated to a higher temperature than a central region of the susceptor (11).

18. CVD reactor according to claim 17, characterized in that the control device (17) is configured to feed a process gas into the process chamber (6) through the gas outlet openings (3) arranged in a radially outer region of the gas outlet surface (20), the process gas having a different composition than that flowing through gas outlet openings (3) arranged in the central region of the substantially circular gas outlet surface (20).

19. Method, substrate or CVD reactor, characterized by one or more of the characterizing features of one of the preceding claims. 31430N1PCT drg / g 17, February 2026 Ai Ltd 2025-03

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