Correlated diffusion of silicon and boron in thermally grown SiO2

Si self-diffusion and B diffusion in SiO2 were simultaneously investigated in thermally grown Si28O2 co-implanted with Si30 and B. The B diffusivity increases with decreasing distance between the implanted B and Si∕SiO2 interface, in the same way as Si self-diffusivity. This result together with a numerical simulation shows that SiO molecules, which are generated at the Si∕SiO2 interface and diffusing into SiO2, enhance not only Si self-diffusion, but also B diffusion. In addition, we found that the diffusivities of both Si and B increase with higher B concentration in SiO2. The experimental results can be quantitatively explained by a numerical simulation assuming that the diffusivity of SiO, which enhances the diffusivities of Si and B, increases with higher B concentration.