Intrinsic stress effects on the growth of planar SiO2 films

We report here on the results of a numerical study on the effects of intrinsic stress on the growth of SiO2 thin films. In accordance with a widely accepted model of stress effects upon silicon oxidation, we assume that the intrinsic stress affects only the oxidant diffusion rate. We examine several different models of stress-assisted diffusion. In the first of these models, the diffusivity is taken to be an exponential function of the stress, whereas in the second, the stress gradient appears as an additional term in the standard diffusion equation. Intrinsic stress effects result in deviations of up to 18% in expected layer thickness, depending upon the mode of oxidation and the diffusion model adopted. The implications of these results for the measurement of diffusion coefficients in SiO2 films are discussed.