OXIDATION-RESISTANT HIGH-CONDUCTIVITY COPPER-FILMS

The properties of thin films of Cu-doped with different percentages of Mg were investigated. It was found that as-deposited films of Cu (2 at. % Mg) oxidize orders of magnitude more slowly than do those of pure Cu. More importantly, when Cu(2 at. % Mg) films are annealed in Ar at 400-degrees-C for 30 min, a thin protective layer of magnesium oxide forms on the surface and completely stops further oxidation. This annealing step also reduces the resistivity of films to the value essentially the same as that of pure sputtered copper films. Films of Cu (2 at. % Mg) also adhere to SiO2 much better than do films of pure copper. Furthermore, annealing studies show that this material remains microscopically smooth and shows no diffusion into SiO2 at temperatures up to 700-degrees-C.