Abstract

An apparatus is provided for controlling the flow of gaseous reactants in a CVD reactor through the use of a body having interior and exterior regions, in which the body defines at least one flow path between the interior and exterior regions so as to create a pressure drop from the interior to the exterior of the body within the chamber. The body is disposed in a reaction chamber with a first area proximate a gaseous reactant inlet and a second area proximate a substrate support such that the substrate is positioned in proximity to the interior of the body. As such, gaseous reactants introduced into the interior of said chamber through the inlet create a pressure drop between the interior and the exterior of the body. In a preferred embodiment, the body is cylindrically shaped and contains perforations providing the flow paths. Preferably, the perforations are either more numerous or larger in the second area than the first area to create a pressure gradient in the interior of the body. Alternatively, the perforations may be uniform in size and uniformly distributed over the body or the perforations can be configured to create a desired pressure differential in the body to support a plasma created in the body and control its location.