Effects of Back‐Side Oxidation of Si Substrates on Sb Diffusion at Front Side

Abstract

The effect of back‐side oxidation of Si wafers on the diffusion of Sb in the front of wafers is investigated with back‐side selective oxidation (BSO) at 1100°C in dry ambients. It is found that the diffusion of Sb in the front of the wafers is retarded by BSO only for FZ Si substrates under directly formed films, and that Sb diffusion in CZ Si substrates and under double‐layered films in both FZ and CZ substrates is not affected by BSO. The effective range over which BSO affects Sb diffusion is found to increase with oxidation time. The range and extent of oxidation retarded diffusion (ORD) for Sb are shown to agree with those of oxidation enhanced diffusion (OED) for B and P. These results are explained with a proposed model: (i) there is a thermal equilibrium between vacancies and interstitials, and (ii) the interface provides sinks and generation centers for point defects in Si, though the interface does not react with point defects.