Structure-stress-resistivity relationship in WTi alloy ultra-thin and thin films prepared by magnetron sputtering

WTi thin films were prepared from an alloyed target (W:Ti similar to 70:30 at. %) by magnetron sputtering. Body-centered cubic WxTi1-x solid solutions with a {110} fiber texture and columnar grains have been produced with 0.75 < x < 0.81. The sub-stoichiometry of Ti is shown to result from atom transport and, to a lesser extent, from resputtering. The stress-free lattice parameter values of the films are shown to be close to the bulk lattice parameter of alpha-W. The electrical resistivity of the produced WTi thin films is about 60 - 200 mu Omega cm, depending on the film thickness and microstructure (sputtering conditions). For both ultra-thin (9.5 nm) and thin (180 nm) films, a stress transition from compressive to tensile is observed as the working pressure increases. The process-structure-property relations of the WTi ultra-thin and thin films are discussed in relation with the state of the art. (C) 2013 AIP Publishing LLC.