Gas inlet element of a CVD reactor with two infeed points

A device for depositing a layer on at least one substrate (4), the device comprising:

• a process chamber (8);
• a gas inlet element (10) comprising a first gas distribution volume (11), a second gas distribution volume (13), and a gas outlet surface (6′) facing the process chamber (8), the gas outlet surface (6′) having a plurality of gas outlet openings (16) fluidically connected to the first gas distribution volume (11) and the second gas distribution volume (13);
• a susceptor (3) with a support side facing the process chamber (8) for supporting the at least one substrate (4);
• a gas mixing system;
• mass flow controllers (32, 33, 34, 37);
• at least one reactive gas source (30) for supplying a first reactive gas and a second reactive gas;
• a carrier gas source (31) for supplying a carrier gas;
• a first feed line (35) with at least one first gas inlet opening (39) for feeding a first gas flow, which includes the first reactive gas, into the first gas distribution volume (11);
• a second feed line (36, 38) with at least one second gas inlet opening (25, 28) for feeding a second gas flow, which includes the second reactive gas, into one or more of the first gas distribution volume (11) or the second gas distribution volume (13), wherein either the first and second reactive gases are different from one another, or if the first reactive gas is identical to the second reactive gas, the mass flow controllers (32, 33, 34, 37) are configured to control a concentration of the first reactive gas in the first gas flow to be different from a concentration of the second reactive gas in the second gas flow, wherein the at least one first gas inlet opening (39) is disposed adjacent to a center of the gas outlet surface (6′) or at respective radial distances from the center of the gas outlet surface (6′) and the plurality of the second gas inlet openings (25, 28) are disposed at a larger radial distance than that of the at least one first gas inlet opening (39);
• a measuring device (41) for determining a degree of deflection of the substrate (4);
• and
• a control device (42) configured to, in response to the degree of deflection of the substrate (4), adjust the first and second gas flows such that, with respect to the center of the gas outlet surface (6′), gas flows emerging from the gas outlet openings (16) exhibit (i) a substantially constant concentration of at least the first or second reactive gas along circumferential paths about the center of the gas outlet surface (6′) and (ii) a concentration that varies as a function of radial distance from the center of the gas outlet surface (6′), wherein, responsive to a curvature of the at least one substrate (4), the adjustment yields a higher or lower partial pressure of the first reactive gas at locations nearer to the center of the gas outlet surface (6′) than at locations farther from the center of the gas outlet surface (6′), thereby causing a growth rate at locations of the surface of the at least one substrate (4) having smaller radial distance from the center of the gas outlet surface (6′) to be greater or smaller than a growth rate at locations having larger radial distance.