Apparatus and method for injecting and modifying gas concentration of a meta-stable or atomic species in a downstream plasma reactor

Abstract

An apparatus and method for injecting gas within a plasma reactor and tailoring the distribution of an active species generated by the remote plasma source over the substrate or wafer. The distribution may be uniform, wafer-edge concentrated, or wafer-center concentrated. A contoured plate or profiler modifies the distribution. The profiler is an axially symmetric plate, having a narrow top end and a wider bottom end, shaped to redistribute the gas flow incident upon it. The method for tailoring the distribution of the active species over the substrate includes predetermining the profiler diameter and adjusting the profiler height over the substrate. A coaxial injector tube, for the concurrent injection of activated and non-activated gas species, allows gases to be delivered in an axially symmetric manner whereby one gas can be excited in a high density RF plasma, while the other gas can be prevented from excitation and/or dissociation caused by exposure to the plasma or heated surfaces in the source apparatus. The profiler is used in conjunction with the coaxial injector tube for redistributing the excited gases emerging from the injector tube, while allowing the non-excited gases to pass through its center.