Texture evolution and mechanical properties of ion-irradiated Au thin films

Microstructure control of thin films is of particular importance for improving the reliability of microdevices in terms of electromigration, fatigue damage and hillocking. High-energy ion bombardment has turned out to be an appropriate modification instrument as it leads to selective grain growth, resulting in single-crystal-like structures. The current work addresses the effect of 7 MeV Au+ and 1.5 MeV N+ irradiation at high fluences (up to 45 × 1016 ions cm−2) on the microstructure and the mechanical properties of 500 nm Au thin films of small initial grain size (70–90 nm). The following microstructure changes were observed: selective grain growth, texture changes, sputtering, interfacial degradation, formation of geometrically necessary dislocations, and defect clusters. Hardening behavior was found to be a consequence of grain growth (Hall–Petch effect) and the formation of ion-induced defects.