Stress evolution in Co/Ti/Si system

The total force per unit width (F/W) in the film during isochronal annealing of the Co/Si and Co/Ti/Si systems were measured using a laser scanning method for substrate curvature measurements. During isochronal annealing of the sample at a ramp rate of 5 °C min−1, several abrupt changes of F/W were observed. The correlation between the phase transformation of cobalt silicides and the abrupt changes of F/W was found. For these two systems, formation of Co2Si and transition of Co2Si to CoSi induce compressive changes in F/W, while transformation of CoSi to CoSi2 induces tensile changes in F/W. With Ti interlayer increasing from 0 to 9 nm, the CoSi2 formation temperature is raised from 509 to 673 °C and the magnitude of the maximum change in F/W is reduced from 160 to 80 N m−1.