Abstract: An apparatus for depositing materials on a substrate includes a manifold having a plurality of inlet valves located equidistantly from the manifold outlet. Preferably the inlet valves are mounted in radial configuration to minimize any "dead space" between the valves and the manifold outlet. The manifold connects a plurality of gas sources through its inlets to a process chamber at its outlet. The valves within the manifold switch continuous reactive gas flows from the sources back and forth between the process chamber and a vent chamber during the deposition process. A purging gas flow is also provided at each valve to purge the "dead space" within the manifold of reactive gases that can linger once the reactive gas flow has been switched to the vent. The method employed by the apparatus maintains a predetermined constant gas flow through the process chamber to produce uniform deposition on the substrate.

Abstract: Apparatus for producing a constant flow, constant pressure chemical vapor deposition includes a manifold having inlet valves for simultaneously switching equal flows of reactive and nonreactive gas between a process chamber and a vent chamber. A constant flow through the process chamber during a deposition is maintained by replacing each reactive gas flow with the equal nonreactive gas flow. Substantially equal pressures within each chamber are maintained by the substantially equal flows of gases. Any "dead space" within the manifold downstream of the inlet valves is minimized by use of a radial manifold. The nonreactive gas flows also purge the "dead space" of reactive gas that may linger after its flow is switched to the vent chamber.