Fabrication and characterization of magnetron sputtered SAC305 thin films

Abstract

This study investigates the surface morphology, mechanical properties including the strain rate sensitivity of the hardness in indentation creep, and electrical resistivity of SAC05 (96.5 %Sn-3 %Ag-0.5 %Cu) thin films sputtered onto Si and SiO2 substrates using RF and DC magnetron. Various deposition parameters, including DC and RF powers and pressures, were optimized for a continuous and robust film. Among the 16 samples analyzed, the optimal surface was obtained at RF 200 W and 0.32 Pa pressure, as confirmed by FE-SEM. Before polishing, the film exhibited a rough surface with an average grain size of ∼1 µm a thickness of ∼2 µm. Post-polishing, the film displayed a uniform 1.5 µm thickness and a mean surface roughness (Ra) of 14.9 nm. The electrical resistivity of SAC305 on the SiO2 substrate was 19.6 µΩ.cm, while the strain rate sensitivity, m, for SAC305 on the Si substrate was 0.12 ± 0.02.