X-ray diffraction study of residual stresses and microstructure in tungsten thin films sputter deposited on polyimide

Structural and mechanical properties of metal/polymer systems are of great interest for technological applications since they strongly influence the quality and lifetime of these systems. The phase composition, microstructure, and residual stresses of tungsten films sputter deposited on polyimide substrates have been analyzed by x-ray diffraction. The influence of several deposition parameters is studied. In 200 nm thick films, the tungsten β phase is observed when oxygen incorporation is high. As the film thickness increases, a thermally activated β→α phase transition occurs and only the α phase exists in the 600 nm films. High compressive residual stresses are evidenced in both phases.