Modeling of Poly-Silicon Carrier Transport with Explicit Treatment of Grains and Grain Boundaries

Explicit treatment of grains and grain boundaries is necessary to model the carrier transport in poly-silicon devices whose feature size is comparable to the grain size. The grain boundaries were modeled by interface traps, and comparison was made between thermionic and diffusion transport across the grain boundaries. It was found that the numerical model for diffusion transport with total trap conservation in grain boundary areas is not physically convergent and shows a strong grid sensitivity. Effects of the critical doping level and the lattice temperature are demonstrated on poly-silicon resistors with 1-D bamboo-type and 2-D realistic microstructures.