Enhanced Si and B diffusion in semiconductor-grade SiO2 and the effect of strain on diffusion

We present experimental and simulation results of Si self-diffusion and B diffusion in SiO2 formed directly on Si substrates by thermal oxidation. We show that both Si and B diffusion in SiO2 are enhanced by SiO generated at the Si/SiO2 interface and diffusing into SiO2. We also show that the existence of high-concentration B in SiO2 enhances SiO diffusion, which enhances both Si self-diffusion and B diffusion. This correlated diffusion of Si and B in SiO2 is consistent with the first-principles calculation results, which show that B diffuses via a complex of BSiO with frequent bond exchanges in the SiO2 network. Furthermore, based on the results, the enhancement of Si self-diffusion and B diffusion in SiO2 by compressive strain and their retardation by tensile strain are suggested.