Argon addition to remote plasma oxidation

Methods for conformal radical oxidation of structures are provided. In one implementation, the method comprises flowing hydrogen into a processing chamber at a first flow rate, wherein the processing chamber has a substrate positioned therein. The method further comprises flowing oxygen into a precursor activator at a second flow rate. The method further comprises flowing argon into the precursor activator at a third flow rate. The method further comprises generating a plasma in the precursor activator from the oxygen and argon. The method further comprises flowing the plasma into the processing chamber, wherein the plasma mixes with the hydrogen gas to create an activated processing gas. The method further comprises exposing the substrate to the activated gas to form an oxide film on the substrate. A growth rate of the oxide film is controlled by adjusting the third flow rate.