| abstract |
Gas flow control assemblies and methods are provided that are configured to deliver gas to process chamber zones at the required flow rates. In some embodiments, the assemblies include one or more MFCs and a back pressure controller (BPC). The assemblies include a controller, a process gas supply, a distribution manifold, a pressure sensor coupled to the distribution manifold and configured to sense the back pressure of the distribution manifold, a process chamber, a gas flow control valve between the distribution manifold and the process chamber One or more mass flow controllers coupled between the distribution manifold and the process chamber, and a back pressure controller provided in fluid parallel relationship to the one or more mass flow controllers, wherein precise flow rate control is achieved. Alternative embodiments include an upstream pressure controller configured to control the flow of carrier gas to control backpressure. Additional methods and assemblies for controlling regional gas flow rates are described in other aspects. |