Understanding the thermal annealing process on metallic thin films

Thermal annealing is an usual process used for intrinsic stress liberation, structural improving, and surface roughness control in materials. In a qualitative way, annealing modifies the surface morphology of materials with temperature and time. In this work, a methodology to explain the surface modification of thin films when they are submitted to an annealing process is discussed. Two thermally evaporated Au films with 200 nm-thicknesses were post-annealed in a vacuum chamber at 100 °C with an argon atmosphere, and annealing times from 0 to 1000 minutes. Each Au film grown at different rate deposition was cyclical annealed and imaged under different annealing times. Data obtained from high quality AFM images after different annealing times of Au samples were used to calculate surface parameters such as roughness, grain size, and slope at the border, also the respective exponents as a function of the annealing time. The experimental results allow understanding the temporal evolution of the annealing process, as a rearrangement of the surface protrusions.