Microstructure and resistivity characterization of CuAu I superlattice formed in Cu∕Au thin films

Stoichiometric AuCu alloy has been well studied in bulk form, but the resistivity of very thin films has rarely been reported. In fact, thin copper and gold films show a strong deviation from bulk resistivity due to the size effect, which motivates us to study CuAu I thin films and understand the properties of nanoscale metallization in more details. Very thin films of ordered CuAu I phase were formed by interdiffusion of Cu∕Au bilayers, in which the intermetallic phase formation was characterized by glancing angle x-ray diffraction and transmission electron microscopy. It was found that Kirkendall voids were created during the interdiffusion. Also, as it turned out, the resistivity of such thin CuAu I films changed only slightly with decreasing film thickness, which was different from pure copper and gold thin films.