Nickel films on Si(001) substrates were annealed in vacuum at a ramp rate of 5 degrees C/min. The total force per unit width (F/W) in the film during isochronal annealing was determined using a laser scanning method for substrate curvature measurements. During heat treatment, several abrupt changes of F/W in the film were observed. PI clear correlation between the evolution of FIN and the phase formation sequence was found. X-ray diffraction and sheet resistance measurements revealed that these changes of F/W coincide with the formation sequence of Ni,Si, NiSi, and NiSi2.