New models for the simulation of polysilicon impurity diffusion sources for a wide range of process conditions

New physical models of polysilicon impurity diffusion sources that are applicable for a wide range of process conditions are proposed for bipolar process simulations. These models address the specific dependencies of polysilicon impurity redistribution on process conditions. The models are described by simple phenomenological equations, including impurity segregation at the grain boundaries, grain growth, and impurity diffusion both at the grain boundaries and within the grains. The parameter values used in these equations are determined by comparison between the experimental results and theoretical calculations, which are independent of the process conditions. The authors have simulated impurity diffusion in polycrystalline Si for a wide range of process conditions, and good agreement was achieved with experimental results