The present technology includes improved gas distribution designs for forming uniform plasmas during semiconductor processing operations or for treating the interior of semiconductor processing chambers. While conventional gas distribution assemblies may receive a specific reactant or reactant ratio which is then distributed into the plasma region, the presently described technology allows for improved control of the reactant input distribution. The technology allows for separate flows of reactants to different regions of the plasma to offset any irregularities observed in process uniformity. A first precursor may be delivered to the center of the plasma above the center of the substrate/pedestal while a second precursor may be delivered to an outer portion of the plasma above an outer portion of the substrate/pedestal. In so doing, a substrate residing on the pedestal may experience a more uniform etch or deposition profile across the entire surface.