Transport considerations in the plasma-assisted oxidation of copper films

The oxidation of copper films in a helical resonator oxygen discharge was performed over the temperature range of 150 to 300degreesC. Significant increases in the oxidation rate relative to thermal oxidation are observed. Oxidation rates followed a parabolic rate expression, with a rate constant of 6.74 X 10(3) nm(2)/min at 250degreesC, and an effective activation energy over the temperature range studied of 0.58 eV. Marker experiments using either gold or molybdenum as the marker layer indicated that both oxygen and copper species transported during oxidation. The location of the copper/copper-oxide interface relative to the marker position demonstrated that copper is the primary transporting species responsible for oxidation, analogous to results reported for the thermal oxidation of copper at higher temperatures. (C) 2003 The Electrochemical Society.