Method for controlling radial profiles of the surface temperature of elements in the process chamber of a CVD reactor

Abstract

The invention relates to a method and a device for depositing a layer on a substrate in a process chamber of a CVD reactor, comprising a gas inlet element for feeding various process gases into the process chamber, wherein the process gas, which contains at least a first and a second gas, is fed into at least one gas distribution volume, wherein the gas distribution volume is flow-connected to gas outlet openings arranged in a gas outlet surface, through which gas outlet openings the process gas flows into the process chamber, wherein the process gas is fed into the gas distribution volume at at least two different feed points with different mixing ratios of the first gas to the second gas, such that the gas flows exiting the gas outlet openings in the radial direction with respect to a centre of the gas outlet surface have different concentrations of the first and second gas, wherein the first and second gas have different heat-conducting properties from one another. By varying the mixing ratio of the first to second gas at the different feed points, predefined radial profiles of the surface temperature of elements arranged in a heat transport zone between a heating element and a cooling element are set.

Description

Description Method for controlling radial surface temperature profiles of elements in the process chamber of a CVD reactor field of technology

[0001] The invention relates to a method for depositing a layer on a substrate in a process chamber of a CVD reactor, comprising a gas inlet device for feeding various process gases into the process chamber, wherein a process gas containing at least a first and a second gas is fed into at least one gas distribution volume, wherein the gas distribution volume is connected to gas outlet openings arranged in a gas outlet surface, through which the process gas flows into the process chamber, wherein the process gas is fed into the gas distribution volume at at least two different injection points with a different mixing ratio of the first gas to the second gas, such that the gas flows exiting the gas outlet openings exhibit differing concentrations of the first and second gases in the radial direction with respect to a center of the gas outlet surface.where the first and second gases have different thermal conductivity properties. State of the art

[0002] German patent DE 102011056589 discloses a process chamber of a CVD reactor, which is bounded below by a heated susceptor and above by a cooled gas inlet housing wall of a gas inlet device. A heat transfer zone extends between the heated susceptor and the cooled gas inlet housing wall. Within this heat transfer zone, a shield plate, thermally decoupled from the gas inlet housing wall, is arranged and is heated by conduction or radiation from the susceptor. 31382PCT drg / drag Ai Ltd 2024-02tor is heated. The temperature of the shielding plate can be varied by vertically repositioning the shielding plate within the process chamber. The temperature of the shielding plate influences the layer growth on one or more substrates arranged below the shielding plate on the susceptor. In practice, the radial profile of the surface temperature of the shielding plate is not constant, resulting in radial inhomogeneities within the layers deposited on the substrates.

[0003] German patent DE 102020123076 discloses a method for depositing a layer onto a substrate, wherein gases or gas mixtures with different compositions are fed into a gas distribution volume of a gas inlet element of a CVD reactor at several radially offset injection points. The gas distribution volume is connected to a gas outlet surface through which the gases flow from the gas distribution volume into a process chamber of the CVD reactor. The concentration of the gases injected at the various injection points is varied such that the gas flows exiting the gas outlet openings of the gas outlet surface of the gas inlet element exhibit different concentrations of the reactive gas within the area of ​​the gas outlet surface.

[0004] US Patent 10,526,705 B2 discloses a process chamber of a CVD reactor, bounded at the bottom by a heated susceptor. A gap is arranged between the heating device used to heat the susceptor and the susceptor itself, into which a purge gas is introduced through several radially offset injection points. The heat transfer from the heating device to the susceptor is varied by selecting a purge gas that is either conduction-dominant or radiation-dominant. 31382PCT drg / drag Ai Ltd 2024-02This is done by injecting a gas with a high or low thermal conductivity. Summary of the invention

[0005] The invention is based on the objective of providing a method by which the radial temperature profile of elements arranged within a heat transport zone in a process chamber of a CVD reactor, in particular a screen plate arranged between the gas inlet device and the susceptor, can be adjusted, especially without significantly affecting the layer growth on substrates supported by the susceptor in a parasitic manner, as well as a device for carrying out the method.

[0006] The problem is solved by the method or device specified in the claims. The dependent claims not only represent advantageous further developments of the technical teachings specified in the dependent claims, but are also independent solutions to the problem.

[0007] First and essentially, it is proposed that a gas mixture of at least two gases with different thermal conductivity properties and different mixing ratios be fed into a gas distribution volume of a gas inlet device at various radially offset injection points. This is achieved in such a way that the gas mixtures flowing in through the different injection points do not mix homogeneously within the gas distribution volume, but rather form radial zones with different mixing ratios, arranged radially offset from each other according to the injection points. Consequently, these radial zones with different mixing ratios can be used to... 31382PCT drg / drag Ai Ltd 2024-02 Gas flows with different mixing ratios enter a process chamber of a CVD reactor at radially assigned gas outlet openings. In the process chamber, the gas flows can pass through a heat transport zone extending between a heating element, for example, a heated susceptor, and a cooling element, for example, a cooled gas outlet surface forming the gas outlet openings. A change in the mixing ratio within a radial zone can thus also lead to a change in heat transport in the region of the heat transport zone located within the respective radial zone. By means of the method according to the invention, the heat transport properties within the heat transport zone can be controlled by varying the mixing ratio of the at least two gases at the radially offset injection points.

[0008] Elements located within the heat transfer zone, such as a shielding plate positioned between the gas outlet surface and the susceptor, are heated by thermal radiation from the heating device and / or by conduction via the gases fed into the process chamber. Heat dissipation occurs primarily via conduction through the gas in a gap between the shielding plate and a cooled gas outlet surface of the gas inlet. By changing the mixing ratio of the gases, which have different thermal conductivity properties, the thermal conductivity within the radial zones can be specifically altered. For example, by varying the mixing ratio of the gases within a radial zone, the surface temperature of the surface section of the shielding plate located within that radial zone can be precisely controlled.The surface temperature of the shielding plate can influence layer growth on substrates located below the shielding plate on the susceptor. 31382PCT drg / drag Ai Ltd 2024-02

[0009] The at least two gases, here exemplified as a first and a second gas, can differ, in particular, from the precursor gases actively used for layer deposition in the process chamber. The first and second gases can each contain a carrier gas and / or an inert gas; for example, one of the two gases can be hydrogen and the other nitrogen. Preferably, both gases are injected at the injection points, but in different mixing ratios. For example, a gas mixture consisting of hydrogen and nitrogen is injected at each injection point, but with a different mixing ratio each time. Preferably, more hydrogen than nitrogen is injected.

[0010] Alternatively, only one of the two gases can be fed into the gas distribution chamber at the injection points, but with a different mass flow rate. The mass flow rate of one gas or the mixing ratio of both gases can be varied at the different injection points in such a way that a predetermined radial profile of the surface temperature of the shielding plate located in the heat transfer zone through which the gases flow can be set. Radial profiles of the surface temperatures of other elements located within the heat transfer zone can also be set.

[0011] The first and / or second gas, together with precursor gases, can actively participate in the coating process, i.e., be incorporated into the layer or fed into the process chamber. The inventive method or device is particularly suitable for depositing III-V, IV-IV, or II-VI layers on large-area substrates. Substrates with an area only slightly smaller than the gas outlet area are preferably used. Preferably, the gas outlet area extends over the entire surface of the substrate. 31382PCT drg / drag Ai Ltd 2024-02 The cross-sectional area of ​​the gas distribution volume can extend over the entire gas outlet area. The elements arranged in the heat transfer zone can preferably extend over the entire cross-sectional area of ​​the gas distribution volume.

[0012] The invention thus relates to a method and a device with which a gas mixture consisting of at least two gases with different thermal conductivity properties, but each with a different mixing ratio, is fed into the same gas distribution volume at various radially offset injection points, so that radial zones with different mixing ratios of the gases form within the gas distribution volume, whereby predetermined radial surface temperature profiles of elements, in particular the shielding plate, arranged in the heat transfer zone between the heating element and the cooling element, are set by varying the mixing ratios. The shielding plate can define the upper boundary of the process chamber and be arranged to be vertically displaceable within the process chamber.

[0013] The injection points can preferably be arranged radially offset from a geometric center of the gas inlet element. The gas inlet element can preferably extend like a showerhead over substantially the entire cross-sectional area of ​​the process chamber. The gas inlet element can also have more than one gas distribution chamber. The gas distribution chambers can preferably be arranged vertically one above the other within the gas inlet element. The gases can be injected, for example, via supply lines opening into a ceiling that bounds the gas distribution volume from above. The supply lines can open into gas inlet openings arranged in the ceiling. The gas inlet openings can serve as the injection points. 31382PCT drg / drag Ai Ltd 2024-02

[0014] The gases can also be fed into annular zones spaced from the geometric center of the gas inlet element. These annular zones can have a ring-shaped or horseshoe-shaped gas distribution element, as known, for example, from DE 102020123076 Al. Preferably, several such concentrically arranged annular zones can be provided, into each of which the gas mixtures with different mixing ratios are fed by means of a gas distribution element or by means of supply lines opening into the zone.

[0015] Alternatively, annular grooves can be arranged in the ceiling that forms the upper boundary of the process chamber. Flow-connected supply lines to the gas sources can open into these grooves, allowing the gases to be fed into them. The grooves can have a multitude of gas outlet openings in their base, which faces the process chamber. These outlet openings allow the gases fed into the grooves to flow into the process chamber. Several grooves can be arranged concentrically.

[0016] The first and second gases can be supplied from a common gas source. Each gas can be fed from a gas mixing system to the CVD reactor via a separate supply line. This supply line can branch into several branches, each leading directly into the gas distribution volume or into a gas distribution element located within the gas distribution volume. Each supply line branch can be equipped with a mass flow controller to adjust the mixing ratio of the two gases. The mass flow controllers can be controlled by a control unit using predefined surface temperature profiles of elements located in the heat transfer zone or by measured values ​​provided by a temperature measuring device. 31382PCT drg / drag Ai Ltd 2024-02Temperature measuring device can, for example, measure the surface temperature within the different radial zones. Brief description of the drawings

[0017] Exemplary embodiments of the invention are explained below with reference to the accompanying drawings. These show: Fig. 1 shows a first embodiment of the invention based on a schematic longitudinal section through a CVD reactor 3, Fig. 2 shows a cross-section along line II-II in Figure 1, Fig. 3 shows a representation according to Figure 1 of a second embodiment, Fig. 4 shows a section along line IV-IV in Figure 3. Description of the embodiments

[0018] Figures 1 to 4 show a CVD reactor 3 with a gas-tight housing 32, the housing wall of which surrounds an evacuable process chamber 2. The process chamber 2 is bounded below by a susceptor 13, which can be heated by a heating device 15, and above by a shielding plate 14. A gas inlet device 4 is provided to introduce different gases into the process chamber 2. The gas inlet device 4 is connected to a gas mixing system 37, which comprises several gas sources 16, 17, 18, each providing different gases. Two of the gas sources 16, 17 are designated as carrier gas sources, providing hydrogen and nitrogen, respectively. Another gas source 18 can, for example, provide a precursor gas, which is in particular a reactive gas. 31382PCT drg / drag Ai Ltd 2024-02

[0019] The gas inlet element 4, which in the exemplary embodiments is arranged above the shielding plate 14 at a distance from it, is formed by a hollow body that has at least one gas distribution volume 5, 6. In the exemplary embodiments shown in Figures 1 to 4, the gas inlet element 4 has two vertically arranged gas distribution chambers 5, 6. A coolant chamber 31, through which a coolant flows, adjoins the lower gas distribution chamber 6. Each of the two gas distribution chambers 5, 6 is flow-connected to a cooled gas outlet surface 7 via tubes 35, 36, so that gases fed into the gas distribution chambers 5, 6 exit the gas outlet surface 7 in a uniform flow distribution. The gas distribution volumes 5, 6 each extend over the entire circular gas outlet surface 7.The gas outlet openings 8, 9 and the associated tubes 35, 36 are evenly distributed over the entire gas outlet area 7. Supply lines 39, 40, 41 open into the gas distribution volume 5 at several radially offset injection points 10, 11, 12, allowing the gases supplied by the gas sources 16, 17, 18 to be fed into the gas distribution volume 5.

[0020] The gases exit through the gas outlet surface 7 of the gas inlet element 4 and flow through the gap arranged between the gas outlet surface 7 and the shielding plate 14. The gases then flow into the process chamber 2 through gas passage channels 28, 29 arranged in the shielding plate 14. The gases flow through the process chamber 2 in a radial direction towards a gas outlet element 30, which surrounds the process chamber 2 in an annular manner and is connected to a gas outlet 38 via a gas disposal system (not shown).

[0021] Different reactive gases, each together with a carrier gas, can be fed into the two gas distribution chambers 5, 6. 31382PCT drg / drag Ai Ltd 2024-02Through the tubes 35, 36 the reactive gases pass via gas outlet openings 8, 9 arranged in the gas outlet surface 7 into the space between the gas outlet surface 7 and the screen plate 14 and flow through the gas passage channels 28, 29 of the screen plate 14 into the process chamber, where they decompose and react with each other, so that a layer consisting of reaction products of the reactive gases is deposited on the surface of a substrate 1 located on the susceptor 13.

[0022] The shielding plate 14 is arranged in a heat transfer zone between the susceptor 13, heated by the heating device 15, and the cooled gas outlet surface 7 of the gas inlet element 4. The shielding plate 14 is in contact with the gas outlet surface 7. In Figures 1 and 3, the shielding plate 14 is shown, by way of example, as being spaced apart from the gas outlet surface 7, since in practice, for example, due to surface roughness, tolerances, and / or warping, the shielding plate 14 may only be in contact with the gas outlet surface 7 in certain areas, i.e., not across its entire surface. The shielding plate 14 is heated primarily by thermal radiation or conduction from the heated susceptor 13.The composition of the gases flowing through the heat transport zone between the heated susceptor 13 and the cooled gas outlet surface 7 thus influences the heat transport to the shielding plate 14 or the heat dissipation to the cooled gas outlet surface 7 and therefore the surface temperature of the shielding plate 14.

[0023] In the gas distribution chamber 5 located at the top, a reactive gas supplied by a precursor gas source 18 is fed into the process chamber 2, together with a first carrier gas supplied by a first carrier gas source 16 (here, for example, hydrogen) and a second carrier gas supplied by a second carrier gas source 17 (here, for example, nitrogen). The reactive gas could be, for example, 31382PCT drg / drag Ai Ltd 2024-02 is a metal-organic compound of an element of group 11, 13, or 14. The mixing ratio of the carrier gases influences the heat conduction from the heating device 15 to the cooled gas outlet surface 7 and thus the temperature of the shielding plate 14 arranged within this heat transfer zone.

[0024] According to the invention, the reactive gas, together with the two carrier gases, which have different heat transfer properties, is fed into the gas distribution chamber 5 at the various radially offset injection points 10, 11, 12, wherein the mixing ratios of the two carrier gases differ at the various injection points 10, 11, 12. The mixing ratio at the various injection points 10, 11, 12 is individually adjusted by means of mass flow controllers 19, 20, 21, 22, 23, 24. It is provided that each of the injection points 10, 11, 12 is assigned to a radial zone that is in flow communication with the other radial zones. By changing the mixing ratio at the various injection points 10, 11, 12, predetermined radial profiles of the surface temperature of the shielding plate 14 arranged in the heat transfer zone are set. The surface temperature of the screen plate 14 can therefore be localized, i.e.within the radial zones assigned to the feed points 10, 11, 12.

[0025] Figures 1 and 2 show a first embodiment of the invention in which a gas distribution element 42 extends within the gas distribution volume 5. The gas distribution element 42 comprises three tubes, each bent into a ring, as known, for example, from DE 102020123076 A1. More or fewer than three tubes can also be provided. The tubes are symmetrically positioned with respect to the geometric center of the gas distribution volume 5. 31382PCT drg / drag Ai Ltd 2024-02 is arranged in a linear fashion. Each of these three tubes is assigned a feed point 10, 11, 12, to which one of the supply lines 39, 40, 41 opens, through which a precursor gas is fed together with a carrier gas mixture. Openings 34 are located in the wall of the tubes, which feed the gases fed into the respective feed point 10, 11, 12 into an annular zone around the geometric center of the gas distribution volume 5. The mixing ratio of the carrier gases can be adjusted by means of the mass flow controllers 19, 20, 21, 22, 23, 24, so that different mixing ratios are established within the annular zones in the gas distribution volume 5. This results in gas flows with different carrier gas mixture ratios being fed into process chamber 2 through the gas outlet openings 8, 9.For example, a carrier gas mixture with a higher hydrogen-to-nitrogen ratio can be introduced through a radially outer ring zone than through a radially inner ring zone. Due to the higher thermal conductivity of hydrogen compared to nitrogen, this results in a temperature difference between the outer and inner ring zones, as the heat transfer properties differ due to the different gas compositions in these regions. In this way, the radial profile of the surface temperature of the screen plate 14 can be influenced.

[0026] A control device 33 is provided which, using measured values ​​supplied by a temperature measuring device (not shown), controls the mass flow controllers 19, 20, 21, 22, 23, 24 such that predetermined radial profiles of the surface temperature of the screen plate 14 are set. The temperature measuring device can, for example, supply measured values ​​of the surface temperature of the screen plate 14 and / or the surface of the susceptor 13 or the surface of the substrate 1 resting on the susceptor 13. If, for example, 31382PCT drg / drag Ai Ltd 2024-02 if radial inhomogeneities of the surface temperature of the screen plate 14 are detected based on the measured values ​​supplied by the temperature measuring device, the inhomogeneities can be compensated for by changing the mixing ratio of the carrier gases at the corresponding injection points 10, 11, 12.

[0027] Figures 3 and 4 show a second embodiment of the invention, in which further injection points 11, 12 are provided around a central injection point 10 located in the geometric center of the gas distribution volume 5, arranged in a uniform circumferential distribution. Each of the injection points 10, 11, 12 is associated with a gas inlet opening located in the ceiling 43 that bounds the gas distribution chamber 5 upwards, into which a supply line connected to the gas sources 16, 17, 18 (not shown here) opens. As in the first embodiment, the mixing ratios of the carrier gases can be individually changed at each injection point 10, 11, 12 in order to adjust the radial distribution of the surface temperature of the shielding plate 14.Each of the different radially offset feed points 10, 11, 12 is assigned a zone in which the composition of the gas flow flowing through the zone can be adjusted by means of mass flow controllers 19, 20, 21, 22, 23, 24.

[0028] Furthermore, the invention comprises various methods that can be carried out using the devices shown in Figures 1 to 4. A mixture of a reactive gas and two carrier gases is injected at each of the various radially offset injection points 10, 11, 12. The reactive gas can be a metal-organic compound of an element from Group 11, 12, or 14. The carrier gas can be, for example, hydrogen and nitrogen. 31382PCT drg / drag Ai Ltd 2024-02

[0029] In a first step, the mixing ratio and type of gases are kept constant at the various radially offset injection points 10, 11, 12. This ensures that the radial distribution of the surface temperature of the shielding plate 14 is not affected.

[0030] In a further method according to the invention, only the concentration of the reactive gas at the radially offset injection points 10, 11, 12 is varied, for example by injecting different amounts of hydrogen. The ratio of the carrier gases, i.e., for example the N₂ / Eb ratio, remains unchanged. Therefore, in this method, the radial temperature profile of the shielding plate 14 is not affected.

[0031] In a further method of the invention, the concentration of the reactive gas at the various injection points 10, 11, 12 is kept constant, and only the mixing ratio of the carrier gases is varied. This influences the radial temperature profile of the shielding plate 14 without affecting the concentration of the reactive gas at the various injection points 10, 11, 12.

[0032] Furthermore, another method according to the invention is provided in which both the mixing ratio of the carrier gases and the concentration of the reactive gas are varied at the various injection points 10, 11, 12. This simultaneously influences the radial temperature profile of the shielding plate 14 and the concentration of the reactive gas. 31382PCT drg / drag Ai Ltd 2024-02

[0033] The foregoing statements serve to explain the inventions covered by the application as a whole, which each independently further develop the prior art at least through the following combinations of features, whereby two, several or all of these combinations of features may also be combined, namely:

[0034] A method characterized in that, by varying the mixing ratio of the first and second gas at the various injection points 10, 11, 12, predetermined radial profiles of the surface temperature of elements 7, 13, 14 arranged in a heat transfer zone between a heating element 15 and a cooling element 31 are set.

[0035] A method characterized in that the elements 7, 13, 14 comprise a susceptor 13 bounding the process chamber 2 below and / or a shielding plate 14 arranged between the gas outlet surface 7 of the gas inlet device 4 and the susceptor 13 and / or the gas outlet surface 7.

[0036] A process characterized in that the first and second gases are different from the precursor gases actively used for the deposition of the layer on the substrate.

[0037] A process characterized in that the first gas and second gas each contain a carrier gas and / or an inert gas and / or one of the two gases contains hydrogen and the other gas contains nitrogen.

[0038] A process characterized in that the first gas and the second gas are fed into the process chamber 2 with at least one precursor gas. 31382PCT drg / drag Ai Ltd 2024-02

[0039] A method characterized in that only the first gas or only the second gas is injected at the various injection points 10, 11, 12 with different mass flows.

[0040] A method characterized in that the shielding plate 14 is arranged at a distance from the gas outlet surface 7.

[0041] A device characterized in that the control unit 33 is programmed to carry out the method according to one of the preceding claims.

[0042] A device characterized in that each of the feed points is assigned a first mass flow controller 19, 20, 21 regulating the mass flow of the first gas and a second mass flow controller 22, 23, 24 regulating the mass flow of the second gas.

[0043] 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 characterize, even without the features of a referenced claim, independent inventive developments of the prior art, in particular for the purpose of filing divisional applications on the basis of 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- 31382PCT drg / drag Ai Ltd 2024-02dung also applies to designs in which some of the features mentioned in the above description are not realized, in particular where they are recognizably unnecessary for the respective purpose or can be replaced by other technically equivalent means. 31382PCT drg / drag Ai Ltd 2024-02List of reference marks 1 substrate, 36 tubes 2 Process chamber 37 Gas mixing system 3 CVD reactor 38 Gas outlet 4 Gas inlet 39 Supply line 5 Gas distribution volume 40 Supply line 6 Gas distribution volume 41 Supply line 7 Gas outlet area 42 Gas distribution element 8 Gas outlet openings 43 Ceiling 9 gas outlet openings 10 feed-in point 12 feed-in point 13 Susceptor 14 Shield plate 15 Heating system 16 Gas source, carrier gas 17 Gas source, carrier gas 18 Gas source, reactive gas 19-27 Mass flow controller 28 Gas passage channel 29 Gas passage channel 30 Gas outlet device 31 Coolant chamber 32 cases 33 Control unit 34 Opening 35 tubes 31382PCT drg / drag Ai Ltd 2024-02

Claims

Claims 1. Method for depositing a layer on a substrate (1) in a process chamber (2) of a CVD reactor (3), with a gas inlet device (4) for feeding various process gases into the process chamber (2), wherein a process gas containing at least a first and a second gas, is fed into at least one gas distribution volume (5, 6), wherein the gas distribution volume (5, 6) is connected by flow to gas outlet openings (8, 9) arranged in a gas outlet surface (7), through which the process gas flows into the process chamber (2), wherein the process gas is fed into the gas distribution volume (5) at at least two different injection points (10, 11, 12) with a different mixing ratio of the first gas to the second gas, so that the gas flows exiting the gas outlet openings (8, 9) have different concentrations of the first and second gases in the radial direction with reference to a center of the gas outlet surface (7), where the first and second gases have different thermal conductivity properties, characterized in that by varying the mixing ratio of the first and second gases, each containing a carrier gas and / or an inert gas, predetermined radial profiles of the surface temperature of elements (7, 13, 14) arranged in a heat transport zone between a heating element (15) and a cooling element (31) are set at the various injection points (10, 11, 12).

2. Method for depositing a layer on a substrate (1) in a process chamber (2) of a CVD reactor (3), 31382PCT drg / drag Ai Ltd 2024-02 with a gas inlet device (4) for feeding various process gases into the process chamber (2), wherein a first and a second gas are fed into at least one gas distribution volume (5, 6), wherein the gas distribution volume (5, 6) is connected by flow to gas outlet openings (8, 9) arranged in a gas outlet surface (7), through which the gases flow into the process chamber (2), wherein the gas outlet openings (8, 9) are arranged offset from each other in the radial direction with respect to a center of the gas outlet surface (7), wherein the first and second gas have different thermal conductivity properties, characterized in that only the first gas or only the second gas is fed into the different feed points (10, 11, 12) with different mass flows, wherein the mass flow of the gases at the different feed points (10, 11, 12) is varied in such a way that predetermined radial profiles of the surface temperature of elements (7, 13, 14) arranged in a heat transfer zone between a heating element (15) and a cooling element (31) can be set.

3. Method according to claim 1 or 2, characterized in that the elements (7, 13, 14) comprise a susceptor (13) bounding the process chamber (2) below and / or a shielding plate (14) arranged between the gas outlet surface (7) of the gas inlet device (4) and the susceptor (13) and / or the gas outlet surface (7).

4. Method according to claim 1 or 2, characterized in that the first and the second gas are different from the precursor gases actively used for the deposition of the layer on the substrate. 31382PCT drg / drag Ai Ltd 2024-025. Method according to one of the preceding claims, characterized in that one of the two gases contains hydrogen and the other gas contains nitrogen.

6. Method according to one of the preceding claims, characterized in that the first gas and the second gas are fed into the process chamber (2) with at least one precursor gas.

7. Method according to one of the preceding claims, characterized in that the shielding plate (14) is arranged at a distance from the gas outlet surface (7) or at least partially abuts the gas outlet surface (7).

8. Device for depositing a layer on a substrate (1), comprising a process chamber (2) of a CVD reactor (3), which is bounded downwards by a process chamber floor (13) and upwards by a screen plate (14), in particular height-adjustable, with passage channels (28, 29), with a heating device (15) for heating the process chamber floor (13), with a gas inlet device (4) which has a gas outlet surface (7) pointing towards a process chamber (2), in which gas outlet openings (8, 9) are arranged, through which different gases can be introduced into the process chamber (2), with a cooling element (31) for cooling the gas inlet device (4), and with a control device (33) for controlling the heating device (4), the cooling element (31), mass flow controllers (19-27) and valves for feeding the gases into the process chamber (2) and for distributing- 31382PCT drg / drag Ai Ltd 2024-02rung of the screen plate (14), characterized in that the control device (33) is programmed to carry out the method according to one of the preceding claims.

9. Device for depositing a layer on a substrate (1) in a process chamber (2) of a CVD reactor (3), comprising a gas inlet element (4) having a gas outlet surface (7) facing the process chamber (2), wherein the gas outlet surface (7) has a plurality of gas outlet openings (8, 9) flow-connected to at least one gas distribution volume (5, 6), through which the process gas can be fed into the process chamber (2), wherein the process gas comprises at least a first gas and a second gas, wherein the process gas can be fed into the gas distribution volume (5) at at least two different feed points (10, 11, 12) arranged radially offset from one another with a different mixing ratio of the first to the second gas, wherein the mixing ratio is adjustable by means of mass flow controllers (19, 20, 21, 22, 23, 24), characterized in that each of the feed points (10, 11,12) each is assigned a first mass flow controller (19, 20, 21) regulating the mass flow of the first gas and a second mass flow controller (22, 23, 24) regulating the mass flow of the second gas. 31382PCT drg / drag Ai Ltd 2024-02

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