Excimer Laser Crystallization of Amorphous Silicon Films for Poly-Si TFT Fabrication

Abstract

ABSTRACTExcimer laser crystallized silicon films have been studied as a function of the number of laser shots, and the influence of the use of such polycrystalline films in thin film transistors (TFTs) has also been investigated. It is found that electron Mobility, one of the most important of all TFT characteristics, increases monotonically with the number of irradiations, with maximum mobility being obtained at about 20 shots. This result is not due to grain size, since transmission electron microscopy indicates that the number of laser shots does not affect grain size in polycrystalline silicon films. Raman studies and TFT carrier transport analysis, on the other hand, suggest that this increase in electron mobility may be explained by the decrease in grain boundary defects and defects inside grains.