The present invention is generally directed to a novel gas delivery system for various deposition processes, and various methods of using same. In one illustrative embodiment, a deposition tool comprises a process chamber, a wafer stage adapted for holding a wafer positioned therein, and a gas delivery system positioned in the chamber above a position where a plasma will be generated in the chamber, wherein substantially all of a reactant gas is delivered into the chamber via the gas delivery system. In another illustrative embodiment, the reactant gas exiting the gas delivery system is directed so as to cover substantially all of an area defined by an upper surface of the wafer. In one illustrative embodiment, the method comprises positioning a wafer in a process chamber of a deposition tool, generating a plasma within the process chamber above the wafer, and forming a layer of material above the wafer by introducing substantially all of a reactant gas used to form the layer of material into the process chamber above the plasma via a gas delivery system positioned above the plasma. In another illustrative embodiment, the reactant gas exiting the gas delivery system is directed to cover substantially all of an area defined by an upper surface of the wafer.