Simultaneous diffusion of Si and B in thermally grown SiO2 was modelled by taking into account the effect of SiO molecules generated at the Si/SiO2 interface and diffusing into SiO2 to enhance both Si and B diffusion. Based upon the model, experimental profiles of co-implanted 30Si and B in 28SiO2, which exhibited increasing diffusivities with decreasing distance from the interface, were simulated. The simulation results showed that the SiO diffusion was so slow that the SiO concentration in the near-surface region depended critically upon the distance from the interface. The simulation explained that the diffusivities of Si and B increased with longer annealing time because more SiO molecules arrived from the interface. The effect of high-concentration B upon the diffusivities of Si and B in SiO2 was examined. Both diffusivities increased with higher B concentration. The experimental results were simulated; assuming that the diffusivity of SiO, which enhanced the diffusivities of Si and B, increased with higher B concentration. The present results indicated that Si and B diffusion in SiO2 was correlated via SiO molecules. That is, the enhancement of SiO diffusion at high B concentrations also caused enhanced diffusion of both Si and B.

Simulation of Correlated Diffusion of Si and B in Thermally Grown SiO2. M.Uematsu, H.Kageshima, Y.Takahashi, S.Fukatsu, K.M.Itoh, K.Shiraishi: Journal of Applied Physics, 2004, 96[10], 5513-9