The influence of As+ion implantation on the oxidation of TiSi2films was investigated. It is shown that implantation of As leads to a greatly increased rate of oxidation in a dry O2ambient. Oxidation of a silicide implanted with inert Ar+ions showed that the effect is not solely due to ion‐induced damage but depends on the presence of As in the film. The microstructure of these films, before and after oxidation, was studied using high‐resolution transmission electron microscopy and Rutherford backscattering. Also, the morphology of As+‐implanted films after rapid thermal annealing will be discussed. Under certain conditions, the morphology is substantially affected by the implant.