Spectroscopic analysis of plasma during rf magnetron sputtering of a YBCO target: Evidence for oxidation on the surface of the cathode

In this article, we present spectroscopic analysis of plasma during reactive rf magnetron sputtering of a YBa2Cu3O7 target. Particular attention is paid to the influence of oxygen pressure on the emission lines of cationic species. From the optical response of barium and copper resonance lines, we have deduced that the oxidation of barium into barium oxide BaO (or BaO2) is complete for an oxygen content up to 10% whereas the oxidation of copper into copper oxide CuO needs an oxygen content of up to 30% which corresponds to the value of the gas composition generally used by different groups. We have shown that these oxidation reactions are represented by a mass law in the vapor phase. These results are confirmed by x‐ray photon spectroscopy analysis and give the experimental process for mixed valence copper oxide sputtering deposition.