Modeling of stress effects in silicon oxidation

A new set of models for the stress effects in silicon oxidation is proposed. The most essential feature is the nonlinear shear-stress-dependent oxide viscosity which models a high-stress relaxation phenomenon similar to plastic deformation. The models are shown to agree well with the most comprehensive and quantitative experimental data available-the thickness of oxide grown on both convex and concave cylindrical silicon structures. The model parameters are extracted by fitting the simulation of two-dimensional growth rates to the experimental values. The extracted values for the linear viscosity of wet oxide are shown to be close to independent data for the equilibrium viscosity of silica. Furthermore, the proposed oxide viscosity model with the extracted model parameters can successfully explain both the occurrence and the magnitude of the intrinsic stress in planar silicon oxidation.