The Effect of Partial Pressure of Oxygen on Self-Diffusion of Si in SiO₂

The self-diffusion coefficient of Si in thermal oxides (SiO₂) formed on semiconductor silicon wafers has been determined with isotope heterostructures, ^natSiO₂/²⁸SiO₂, as a function of the partial pressure of oxygen mixed into argon annealing ambient. The ^natSiO₂ layers contain 3.1% of ³⁰Si stable isotopes while the ²⁸SiO₂ layers are 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 have been determined by secondary ion mass spectrometry (SIMS). The Si self-diffusivity is found not to depend on the partial pressure of oxygen within our experimental error of about ±33%.