The oxidation of vacuum deposited films of copper

Abstract

A study of the oxygen uptake vs. temperature behaviour of vacuum deposited copper films in the range 50 to 400°C under 70 mm Hg oxygen pressure showed the existence of the phases CuO_0.67 and CuO. Isothermal oxidation studies show the CuO_0.67 phase to be stable at the lower temperatures (150-200°C) and the CuO at the higher temperatures (>300°C). In the intermediate range (~210-290°C) the product is also intermediate between the two. The low-temperature data show that a direct logarithmic rate law is obeyed and the activation energy is 5.58 kcal/mole. At 250°C, it is logarithmic as well as inverse logarithmic. At higher temperatures (>300°C) the behaviour is inverse logarithmic, the activation energy corresponding to 5.90 kcal/mole. The reason for the formation of CuO_0.67 and CuO has been explained qualitatively.