Self-diffusion and impurity diffusion in silicon dioxide

Abstract

We present experimental and simulation results of silicon (Si) self-diffusion and boron (B) diffusion in silicon dioxide (SiO2), and examine the effect of nitrogen (N) on diffusion in SiO2. To elucidate the point defect that mainly governs the diffusion in SiO2, the diffusion of implanted 30Si in thermally grown 28SiO2 is investigated. The experimental results show that Si self-diffusivity increases with decreasing distance between the 30Si and Si-SiO2 interface. We propose a model in which SiO molecules generated at the interface and diffusing into SiO2 enhance Si self-diffusion, and the simulation results fit the experimental results. The B diffusivity also increases with decreasing the distance, which indicates that B diffusion is enhanced by SiO. In addition, we investigate the effects of B and N on SiO diffusion in SiO2. We show that the existence of B increases SiO diffusivity and hence decreases the viscosity of SiO2. On the other hand, the incorporation of N decreases SiO diffusivity, which reduces B diffusion in SiO2 and increases the viscosity.