Effect of ion bombardment on stress in thin metal films

Ion-beam-irradiation-induced changes in the stresses operating in thin films are correlated with the thermodynamic phases of the films and the evolution in the film microstructures and morphologies. We investigate using a combination of experiments and molecular dynamics computer simulations the mechanisms that lead to residual stress changes in amorphous, nanocrystalline, columnar polycrystalline and single-crystal thin films. While local viscous relaxation within thermal spikes underlies all stress changes, i.e., a liquidlike region along the collision cascade, it can lead to very different states of stress in the different metallic films.