The measurement of anisotropic stress in obliquely-deposited thin films by fast Fourier transform and Gaussian filter

We present an efficient method for the measurement of anisotropic stress in obliquely-deposited thin films based on fast Fourier transform (FFT) associated with a Gaussian filter. The method not only measures isotropic residual stress but also anisotropic stress in a thin film. The measurement of film stress anisotropy was performed by a Tyman-Green interferometer combined with the MATLAB program to analysis the captured interferograms. The surface topography of thin films was obtained by the fringe pattern analysis program based on FFT method. The surface profile of thin films was filtered by the Gaussian filter after the phase change was converted to surface height distribution. The results show that obliquely-deposited TiO2 thin films exhibit different anisotropic stresses.