Microstructure and physical properties of sputter-deposited Cu-Mo thin films

Within this work, monolithic Cu-Mo alloy films were grown by d.c. magnetron sputter co-deposition at room temperature and 473 K on Si (100) substrates. The Cu-Mo system was studied within the complete concentration range between pure Cu and pure Mo with steps of ~10 at.%. Depending on growth conditions and composition, metastable Cu-rich or Mo-rich solid solutions in single-phase films rich in either Cu or Mo, respectively, or dual-phase films consisting of both phases for intermediate compositions are formed. The physical properties in terms of residual stress, hardness, elastic modulus and electrical resistivity are correlated with the chemical composition and the microstructure of the films. The formation of either Cu-rich or Mo-rich solid solutions stabilizes the film structure and stress state, while the dual-phase films exhibit a pronounced self-annealing behavior resulting in residual stress release with time.