Surface roughening and growth mode transition of polycrystalline thin films

Abstract

Surface roughening of Cu and Ta polycrystalline thin films deposited by magnetron sputtering at different homologous temperature Ts/Tm (Ts and Tm are the substrate temperature and the material melting point, respectively) have been studied using atomic force microscopy. With increasing Ts/Tm, the surface roughness of the films increased and growth exponent first increased and then decreased. The observed temperature dependence of growth exponent indicates a transition of growth modes from random growth at lower Ts/Tm through surface diffusion-dominated growth at intermediate Ts/Tm to anomalous scaling growth at higher Ts/Tm. We also found that the surface roughening of the films reflects the anomalous scaling behavior when the value of Ts/Tm is lower than 0.41, which implies that the boundary diffusion mechanism plays an important role in the scaling behavior of surface roughening.