THE INTERACTION OF ATOMIC OXYGEN WITH THIN COPPER-FILMS

A source of thermal, ground-state atomic oxygen has been used to expose thin copper films at a flux of 1.4 x 10(17) atoms/cm2 s for times up to 50 min for each of five temperatures between 140 and 200-degrees-C. Rutherford backscattering spectroscopy was used to characterize the oxide formed during exposure. The observations are consistent with the oxide phase Cu2O. The time dependence and the temperature dependence of the oxide layer thickness can be described using oxide film growth theory based on rate limitation by diffusion. Within the time and temperature ranges of this study, the growth of the oxide layers is well described by the equation L(T,t) = 3.6 x 10(8) exp(- 1.1/2k(B)T)t1/2, where L, T, and t are measured in angstroms, degrees Kelvin, and minutes, respectively. The deduced activation energy is 1.10 +/- 0.15 eV, with the attendant oxidation rate being greater than that for the corresponding reaction in molecular oxygen.