Microstructural evolution of nanoindented Ag/Si thin-film under different annealing temperatures

The microstructural evolution of Ag/Si thin-film system via nanoindentation and annealing is investigated. Ag films with a thickness of 500 nm are deposited on (100) silicon substrates. Nanoindentation is performed to a maximum depth of 800 nm, and the indented specimens are then annealed at temperatures of 600°C, 700°C and 800°C, respectively. In the as-deposited specimen, the indentation process results in a phase transformation from a diamond cubic structure to amorphous phase within the indented zone. Following annealing at 600°C, the microstructure of the indented zone changes from a fully-amorphous state to a mixed amorphous/nanocrystalline state. The diffusion ability of the Ag atoms into the silicon substrate is enhanced as the annealing temperature is increased. Consequently, the microstructures of the indentation zones in the specimens annealed at 700°C and 800°C, respectively, contain a mixture of amorphous phase, nanocrystalline structures and Ag ₂Si silicide phase. Overall, the results presented in this study confirm that the annealing temperature has a significant effect on the formation of Ag₂Si silicide phase in nanoindented Ag/Si thin-film systems.