Impurity Diffusion in Silicon Based on the Pair Diffusion Model and Decrease in Quasi-Vacancy Formation Energy. Part Two: Arsenic

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Abstract
One of the experimental characteristics of As diffusion in Si is that the As diffusion coefficient is independent of its surface concentration but increases approximately linearly with electrically active As concentration. From the viewpoint of the pair diffusion model (PDM), this means that the excess vacancies are not generated and vacancies are in the thermal equilibrium state. Arsenic diffusion is studied on the basis of PDM, taking account of the decrease in quasi-vacancy formation energy. With the decrease in quasi-vacancy formation energy, the binding energy between an As atom and a vacancy also decreases. Fermi level obtained from the Boltzmann statistics is used. Using the literature data for the self-diffusion coefficient of vacancy mechanism and the As diffusion coefficient, the experimental arsenic concentration profile can be well explained.