The self-diffusion coefficient of Si in thermal oxides (SiO2) formed on semiconductor Si wafers was determined with isotope heterostructures, natSiO2/28SiO2, as a function of the partial pressure of O mixed into Ar annealing ambient. The natSiO2 layers contain 3.1% of 30Si stable isotopes while the 28SiO2 layers were depleted of 30Si stable isotopes down to 0.003%, and the diffusion depth profiles of 30Si isotopes from the natSiO2 to 28SiO2 layers after thermal annealing were determined by secondary ion mass spectrometry. The Si self-diffusivity was found not to depend upon the partial pressure of O within an experimental error of about ±33%.

The Effect of Partial Pressure of Oxygen on Self-Diffusion of Si in SiO2. S.Fukatsu, T.Takahashi, K.M.Itoh, M.Uematsu, A.Fujiwara, H.Kageshima, Y.Takahashi, K.Shiraishi: Japanese Journal of Applied Physics–2, 2003, 42[12B], L1492-4

Figure 37

Diffusivity of Implanted Si in SiO2