Self-diffusion coefficients of Si in thermally grown SiO2 on a semiconductor-grade Si wafer were determined between 1150 and 1300C (figure 38) under equilibrium conditions by using isotope heterostructures (natSiO2/28SiO2). The self-diffusion of Si was induced by appropriate heat treatment, and the diffusion depth profiles of 30Si isotope from natSiO2 to 28SiO2 layers were determined by secondary ion mass spectrometry. The diffusion coefficients found here for 1150 to 1300C were more than 2 orders of magnitude smaller than the values measured in semiconductor-grade SiO2 in the presence of excess Si, i.e., under non-equilibrium conditions, and agreed very well with previously reported values of Si self-diffusion in fused silica under equilibrium conditions.

Self-Diffusion of Si in Thermally Grown SiO2 under Equilibrium Conditions. T.Takahashi, S.Fukatsu, K.M.Itoh, M.Uematsu, A.Fujiwara, H.Kageshima, Y.Takahashi, K.Shiraishi: Journal of Applied Physics, 2003, 93[6], 3674-6