Gas distributor with pre-chambers disposed in planes

Gas distributor in a CVD or OVPD reactor with two or more (as volumes, (1, 2), into each of which a supply line (3, 4) for a process gas opens out, each gas volume (1, 2) being connected to a multiplicity of outlet openings (6, 7) for a respective one of the process gases, which open out in a bottom (5) of the gas distributor, the process gases respectively being first distributed in a radial direction in a first plane, remote from the bottom (5), and then distributed in a circumferential direction in a second plane, adjacent the bottom (5), and flowing through connecting channels (14, 15), which are located tin a third plane (16) disposed between the first plane and the second plane, a multiplicity of gas distributing chambers (12, 13) that are respectively associated with the gas volumes (1, 2) and are connected to the outlet openings (6, 7) being provided in the second plane (9), characterized in that the gas volumes (1, 2) have pre-chambers (10, 10′, 11) lying in a common first plane (8), the pre-chambers (10, 10′, 11) of the two gas volumes (1, 2) forming continuations like prongs of a comb that extend in a radial direction and engage in one another in the manner of prongs of a comb, the comb-like continuations that lie next to one another in a circumferential direction being separated from one another by a wall (17).