The phase transition from Ni2Si to NiSi transrotational structures was studied in terms of incubation (t0) and characteristic (τ) times, i.e. the time required to trigger the transformation and the time after which the volume fraction occupied by the NiSi phase (χ) increases by 60%. The authors combined the effective medium approximation and the Avrami-Johnson-Mehl models to relate the measured sheet resistance Rs versus time to χ(t) in the temperature range between 230 and 320°C With this method, the nucleation barrier and the activation energies for NiSi growth were obtained, 0.5 and 0.93eV, respectively, with the density of nucleation sites higher in thicker layers.