Silicide formation in co-deposited TiSix layers: The effect of deposition temperature and Mo

The silicide reaction in co-deposited TiSi_x layers on single crystal and pre-amorphized Si has been studied in detail. Both the co-deposition ratio and the co-deposition temperature were found to have a strong effect on the formation of the C54-TiSi₂ phase in these films. An unusual dependence of the sheet resistance on the co-deposition ratio was observed for films deposited at room temperature and those deposited at 400°C: the C54-TiSi₂ phase forms more easily for layers deposited at 400°C in the co-deposition ranges x∼0 and x>1.5, while it forms more easily for layers deposited at room temperature in the co-deposition ratio range of x∼0.2–1.5. These dependencies are explained by the formation of crystalline silicide phase(s) with composition close to the co-deposition ratio. With a Si rich ratio, the C49-TiSi₂ phase forms at 400°C with very small grain size, which facilitates the C54-TiSi₂ phase formation. The initial reaction of Ti-rich layer deposited at 400°C involves the formation of metal rich silicide, which impedes the formation of the C54-TiSi₂ phase. An ultra-thin MoSi_2.0 layer (<0.5 nm) was found to promote the formation of the C54-TiSi₂ phase in layers co-deposited at room temperature, but it showed little effect on layers co-deposited on pre-amorphized substrates at elevated temperature.