Strain-induced anisotropy measurement in oxide films grown on silicon

A multiangle single-wavelength ellipsometric method has been applied to the evaluation of anisotropy and stress in SiO(2) films grown on silicon substrate. The method is nondestructive, and it does not require a priori knowledge of the dielectric functions of the oxide layer. A novel theoretical anisotropic multiple-layer program is used to calculate the Fresnel reflection coefficients at various angles of incidence; and an iterative least-squares algorithm compares the theoretical calculations to the experimental data. The data-fitting process yields the index, the thickness, and the anisotropy of the oxide layer and also the index and thickness of the SiO(x) transition layer.