Reactive magnetron sputtering of copper, silver, and gold

Copper, silver, and gold targets were sputtered in various reactive gas mixtures (Ar-N2, Ar-O2, and Ar-CH4) to compare the reactivity of noble metal atoms during the sputtering process. The evolution of the film's growth rate and the variation of the reactive gas partial pressure vs. the reactive gas flow rate were investigated for each kind of metal. The structure of the deposited films was characterised by X-ray diffraction. Electrical resistivity of the coatings was determined at room temperature. The optical band gap of oxides and nitrides films were deduced from UV-visible transmission measurements. The reactive sputtering of copper target leads to the synthesis of Cu3N, Cu2O, Cu4O3, or CuO films. No copper carbide films were deposited. Depending on the methane flow rate, Cu/C films were either nanocomposite coatings (nc-Cu/a-C:H) or amorphous. Silver oxide (Ag2O) films were formed by reactive sputtering of a silver target in Ar-O2 mixtures. On the other hand, the reactive sputtering method did not allow the synthesis of silver nitride nor gold oxide films.