Enhanced grain growth of phosphorus-doped polycrystalline silicon by titanium silicide formation

Abstract

The influence of silicide reaction on the grain growth behavior of phosphorus-doped polycrystalline silicon has been studied. Intrinsic and phosphorus-doped polycrystalline silicon, with and without evaporated titanium overlayer, were prepared by low pressure chemical vapor deposition on thermally grown SiO2 on silicon wafer. These samples were then annealed in He ambient at 700°C for various time. The Rutherford backscattering spectrum showed that TiSi2 formed completely after 30 min anneal. Cross-sectional transmission electron microscopy showed that Kirkendall voids exist at the interface between TiSi2 and polycrystalline silicon, indicating that silicon is the predominant diffusing species. Enhanced grain growth as a result of silicide reaction was observed in phosphorus-doped polycrystalline silicon. The enhanced grain growth of polycrystalline silicon is suggested to be due to the redistribution of dopant, analogous to the alloying and dealloying processes in diffusion induced grain boundary migration.