Electrical bias-temperature stress measurements were performed on copper oxide/SiO2/Si metal-oxide-semiconductor capacitors to measure the O partial pressure dependence of the Cu-ion transport rates through the SiO2 layer. Both Cu2O and CuO were investigated, and the copper oxide film stoichiometry was characterized by glancing incidence X-ray diffraction and X-ray photoelectron spectroscopy. At relatively high O pressures, Cu-ion transport was observed for both Cu2O/SiO2/Si and CuO/SiO2/Si, and the activation energies were comparable. Under reduced O pressures and vacuum, the Cu ion flux was reduced for both copper oxides. In vacuum, the activation energy for Cu transport from CuO layers was reduced by approximately 0.7eV compared to the apparent activation barrier at high O pressures, and the Cu transport signals for Cu2O were below the detection limit of the experiment. A study of Cu transport rates for both CuO and Cu2O electrode layers showed that the Cu-ion flux increased with increasing O pressure, with an O pressure dependence close to pO2½ .

Oxygen Pressure Dependence of Copper Ion Transport in SiO2 Dielectrics. L.P.Shepherd, A.Mathew, B.E.McCandless, B.G.Willis: Journal of Vacuum Science and Technology B, 2006, 24[3], 1297-302