This invention provides 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 made more or less uniform, 
wafer-edge concentrated, or 
wafer-center concentrated. A 
contoured plate or profiler is provided for modifying 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 profiler is situated below an input port within the 
plasma reactor chamber and above the wafer. 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 (or gas mixtures) 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 gas admixture that is not to be excited or dissociated prior to contact with the wafer surface is shielded from 
direct exposure to the 
RF field surrounding the 
plasma confinement tube. The tube walls are also shielded from the 
infrared energy emitted from the plasma. 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.