Numerical simulation and simple approximation of the impurity gettering kinetics by polysilicon based passivating contacts

Abstract

This paper presents 1D and 3D numerical simulations of the diffusion-limited gettering process for iron in silicon by the polysilicon/oxide passivating contact structures. Simulation results reveal that a 1D model is sufficient to simulate the gettering kinetics, as iron diffusion through the oxide interlayer can take place via both direct diffusion and diffusion through pinholes, where either of these two are mainly 1D. In addition, we provide a simple exponential approximation to describe the gettering kinetics, which can be used to extract the blocking effect of the oxide interlayer in the cases where the Fe transport factor in oxide is less than 1×10-5.