Changes in composition and deposition rates in the reactive sputtering of copper, titanium, and yttrium exposed to oxygen

Copper, titanium, and yttrium oxide films were prepared by reactive dc magnetron sputtering in an Ar-O2 plasma and the deposition rates and compositional changes were measured as a function of dc power. The deposition rates of Cu increased monotonically with increasing dc power, while those of Ti and Y increased abruptly by more than one order of magnitude at a critical dc power (Pc). Abrupt compositional changes of metal and oxygen in the thin films were also observed for Ti and Y at Pc. The compositional change curve for Cu had a plateau in dc power dependence. These results correlate with the differences of heat of oxide formation among Cu, Ti, and Y.