Intrinsic stress effects on the growth of planar SiO2 films

We report here on the results of a numerical study on the effects of intrin sic stress on the growth of SiO2 thin films. In accordance with a widely ac cepted model of stress effects upon silicon oxidation, we assume that the i ntrinsic stress affects only the oxidant diffusion rate. We examine several different models of stress-assisted diffusion. In the first of these model s, the diffusivity is taken to be an exponential function of the stress, wh ereas in the second, the stress gradient appears as an additional term in t he standard diffusion equation. Intrinsic stress effects result in deviatio ns of up to 18% in expected layer thickness, depending upon the mode of oxi dation and the diffusion model adopted. The implications of these results f or the measurement of diffusion coefficients in SiO2 films are discussed.