Generation and relaxation of residual and recovery stress for sputtered TiNi films

TiNi films with different Ti/Ni ratios were prepared by co-sputtering Ti50Ni50 (at%) target with Ti target at temperature of 723 K. The stress values in the deposited films changed significantly with Ti contents and postannealing temperatures due to the differences in phase transformation behaviors and intrinsic stress. Post-annealing of thèse films at 923 K for 1 hour could modify the intrinsic stress and martensite transformation behavior thus cause the significant decrease in residual stress. For all three types of film annealed at 1023 K for 1 hour, the large stress in the thin films could damage the shape memory effect or result in the peeling-off of film from Si substrate.