Control of Grain Boundary Microstructures in Sputtered Gold Thin Films by Surface Energy-Driven Grain Growth

The evolution of grain boundary microstructures in gold thin films during annealing was investigated in order to find a clue to the development of high performance thin films by grain boundary engineering. The {111} oriented grains with the lowest surface energy were preferentially grown by surface energy-driven grain growth during annealing. The sharp {111} texture was developed by annealing at the temperature more than 873K. The remarkably high fraction of low-Σ coincidence site lattice (CSL) boundaries occurred when the area fraction of {111} texture increased to more than 95%. In particular, the fraction of some low-Σ CSL boundaries (Σ1,Σ3,Σ7) for the most sharply {111} textured specimen was found to be one order higher than those predicted for a random polycrystal. The utility of grain boundary engineering is discussed for controlling the performance degradation caused by the percolation phenomena of grain boundary diffusion in gold thin films.