Intrinsic stress of Co35Pd65 alloy films

Abstract

Co 35 Pd 65 alloy films were made by the vapor deposition method in a vacuum with the base pressure, p, ranging from 3×10−7 to 9×10−5 Torr. The thickness, t, of these films was varied from 500 to 2500 Å. The substrate temperature, TS, was set equal to 50 or 180 °C. Some of the as-deposited films were annealed at an anneal temperature TA from 180 to 350 °C in vacuum. We employed a strain gauge to measure the deflection, Δy, of the free end of a cantilevered substrate. The stress, S, of the film was determined while removing the film from the substrate. In general, the stress S of the as-deposited Co35Pd65 film is tensile and of the order of 109–1010 dyn/cm2. In terms of t dependence, S has a maximum near t=1000 Å. The thermal stress has a small contribution, i.e., S is mainly due to the intrinsic stress formed during film growth. The stress data are found to be closely associated with the grain structure in these polycrystalline films. Following the same method, we analyzed how S is varied as a function of TA. Finally, the effect of the base pressure on S is studied briefly.