Thermal oxidation of reactively sputtered amorphous W80N20 films

The oxidation behavior of reactively sputtered amorphous tungsten nitride of composition W80N20 was investigated in dry and wet oxidizing ambient in the temperature range of 450 degree C--575 degree C. A single WO3 oxide phase is observed. The growth of the oxide follows a parabolic time dependence which is attributed to a process controlled by the diffusivity of the oxidant in the oxide. The oxidation process is thermally activated with an activation energy of 2.5±0.05 eV for dry ambient and 2.35±0.05 eV for wet ambient. The pre-exponential factor of the reaction constant for dry ambient is 1.1x1021 A2/min; that for wet ambient is only about 10 times less and is equal to 1.3x1020 A2/min