Stresses and silicon interstitials during the oxidation of a silicon substrate

Abstract

Models of viscoelastic flow in SiO₂, layers grown on silicon substrates are introduced to explain various phenomena. Experimental data are first presented: stresses in the layer and substrate, measured during the growth at about 1000°C or at room temperature (20°C); density of the oxides grown at a temperature less than 1000°C; and values of the viscosity of the oxide. Models of stress distribution inside the oxide layer are then discussed, as a function of temperature and oxide growth rate, and related to stresses at the steps, jogs and nuclei of the Si-SiO₂, interface, which are able to break Si-Si bonds in silicon. This explains the value of the interface stresses in the oxide. Values of the interstitial and vacancy concentrations in silicon during oxidation are then reviewed, and related to the oxidation stacking fault length and to the change in the diffusivity of dopants. Hu's model of the interstitial and vacancy generation at the interface is then discussed.