Stress-development process during Ni-silicide film formation

The silicidation-induced stress that arises during Ni-silicide formation is discussed experimentally. The Ni-silicide films are formed by annealing of Ni films deposited on Si substrates. For this study, the silicidation process was observed using a scanning electron microscope, and film stress was determined by detecting curvature of the substrate surface. The residual stress in the films at room temperature increased after silicide formation, which occurs at high temperatures (above 300°C). The stress-increase process is discussed based on measurments both the changes in residual stress at a temperature of interest and thermal stress of Ni, Ni²Si, and NiSi films. Silicidation-induced stress is defined as the discrepancy between the residual stress measured at a temperature of interest and the thermal stress predicted without silicidation. The silicidation-induced stresses in our experiments were determined to be about 340 MPa (Ni-NiSi) and about 400 MPa (Ni²Si - NiSi).