In situ micro-Raman analysis and X-ray diffraction of nickel silicide thin films on silicon

This article reports on the in situ analysis of nickel silicide (NiSi) thin films formed by thermal processing of nickel thin films deposited on silicon substrates. The in situ techniques employed for this study include micro-Raman spectroscopy (μRS) and X-ray diffraction (XRD); in both cases the variations for temperatures up to 350 °C has been studied. Nickel silicide thin films formed by vacuum annealing of nickel on silicon were used as a reference for these measurements. In situ analysis was carried out on nickel thin films on silicon, while the samples were heated from room temperature to 350 °C. Data was gathered at regular temperature intervals and other specific points of interest (such as 250 °C, where the reaction between nickel and silicon to form Ni2Si is expected). The transformations from the metallic state, through the intermediate reaction states, until the desired metal–silicon reaction product is attained, are discussed. The evolution of nickel silicide from the nickel film can be observed from both the μRS and XRD in situ studies. Variations in the evolution of silicide from metal for different silicon substrates are discussed, and these include (1 0 0) n-type, (1 0 0) p-type, and (1 1 0) p-type silicon substrates.