Effect of grain structure on the onset of diffusion-controlled stress relaxation in Pt thin films

The thermomechanical behavior of Pt thin films was studied using the substrate curvature technique. Films of identical thickness but different grain size were prepared by sputtering directly onto a thermally grown SiO2 layer on a (100) Si wafer. Predictions from a thin-film version of the deformation mechanism map model and the diffusional wedge are compared to the experimental results. The diffusional wedge model most accurately predicts the onset of diffusion-controlled stress relaxation in columnar Pt films. The use of an effective film thickness equal to the grain size improves the match to noncolumnar microstructures. (C) 2003 American Institute of Physics.