An advanced model for dopant diffusion in polysilicon

A two-dimensional simulation model for dopant diffusion in polysilicon has been developed, which includes dopant clustering in grain interiors as well as in grain boundaries. The grain growth model is coupled with the diffusion coefficient of the dopants and the process temperature based on thermodynamic concepts. For high dose implantation cases the trapping/emission mechanism between grain interiors and grain boundaries and the grain growth are the major effects during thermal treatment processes. The polysilicon grains itself are assumed to be tiny squares, growing from initial size. In order to handle nonplanar semiconductor structures, we use a transformation method for the simulation area as well as for the PDEs.