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 interio rs as well as in grain boundaries. The grain growth model is coupled w ith the diffusion coefficient of the dopants and the process temperatu re based on thermodynamic concepts, For high dose implantation cases t he trapping/emission mechanism between grain interiors and grain bound aries and the grain growth are the major effects during thermal treatm ent processes, The polysilicon grains itself are assumed to be tiny sq uares, growing from initial size. In order to handle nonplanar semicon ductor structures, we use a transformation method for the simulation a rea as well as for the PDE's.