Annealed thin films of Cu/Mg/SiO2are studied as possible conductors for microelectronics. Rutherford backscattering and sheet resistance measurements show that vacuum annealing at 350-400°C results in transport of Mg from the buried layer to the surface of the copper where it reacts with impurities to form a thin surface layer of MgO. Such films are then exceedingly resistant to further oxidation. These films have a resistivity of 2·μω-cm and are adherent to the SiO2substrate. However, at temperatures 450-500°C there is a reaction between Mg and the SiO2substrate releasing free Si into the copper.