In situ study of thin film growth by internal stress measurement under ultrahigh vacuum conditions: Silver and copper under the influence of oxygen

The internal stress of thin silver and copper films was determined during and after evaporation under ultrahigh vacuum conditions. In contrast with silver the residual stress of copper films was strongly affected by the partial oxygen pressure during the metal deposition. We therefore used copper films, dosed with oxygen either during or after deposition, as substrate films for the deposition of a second copper film to study the influence of the physical and chemical properties of the substrate on the internal stress of copper. It was demonstrated in this study that internal stress measurements can make an extremely valuable contribution towards the characterization of thin film growth if combined with a model for the origin of this internal stress. Furthermore, it was demonstrated that this technique can also be used to study the effect of gas adsorption on the internal stress of thin films.