A new thermal oxidation model based on a rate equation approach with concentration dependent diffusion coefficient is proposed for ultrathin SiO2 for thicknesses of the order of 100 Å. The oxidation reaction of silicon is assumed to be dependent on the concentrations of unreacted silicon and oxygen. The results of oxide thickness versus oxidation time for various growth conditions and activation energies for diffusion coefficients are in agreement with various experimental data for O2 ambient
