Trap-Limited Vacancy Diffusion in Silicon at High Temperatures

摘要

A high-temperature vacancy diffusivity (D-V) in silicon crystals is high and consistent with the extrapolated low-temperature diffusivity by Watkins. On the other hand, the apparent vacancy diffusivity in silicon wafers is significantly smaller than D-V. In particular, this has become more evident by recently reported vacancy-related donor profiles in high-resistivity wafers subjected to rapid thermal annealing (RTA). The reported donor depth profiles are complicated and strongly dependent on the RTA conditions. Yet, they are well reproduced, assuming that wafers (in contrast to the crystals) contain an appreciable amount of some impurity that acts as an efficient trap for vacancies even in a high-temperature range of RTA. The true vacancy diffusivity and the equilibrium ratio of the vacancy and self-interstitial concentrations are deduced from these data.