The interdependence of the diffusion behavior and grain microstructure in amorphous polysilicon - on - monocrystal systems was studied with regard to the rapid thermal and furnace annealing of P implants. It was found that changes in microstructure during annealing played a major role in determining the diffusion profiles in the substrate as well as in the polysilicon layer. Drive-in diffusion resulted in a much larger grain

microstructure for as-deposited amorphous Si than for as-deposited polysilicon. This led to the formation of shallower junctions in the substrate for the first case. The P junctions which formed in the substrate were found to be very uniform laterally, in spite of expected doping inhomogeneities that were caused by polysilicon grain boundaries, for both as-deposited amorphous Si diffusion sources and for as-deposited polysilicon diffusion sources.

K.Park, S.Batra, S.Banerjee, G.Lux: Journal of Electronic Materials, 1991, 20[3], 261-5