US Patent 7192486 Clog-resistant gas delivery system

Processing gases reactive with each other are provided in parallel to a processing chamber through separate delivery lines including mass flow controllers devoted to each line. The parallel delivery lines meet in a mixing manifold located proximate to the processing chamber and relatively far downstream from the mass flow controllers and other flow-constricting components of the gas delivery system. The continuous high flow of gas provided by the devoted mass flow controllers may maintain a sufficiently high pressures on the delivery lines to prevent partial clogging from leading to a further drop in pressure and complete obstruction of the delivery line.