The effects of laser annealing ambient and the number of laser shots on the morphology of poly-Si films

We have examined the effects of the laser annealing ambient and the number of laser shots on the morphology and the grain size of excimer laser-annealed poly-Si films. In the case of a high oxygen partial pressure (> 10e(-3) Torr), the surface roughness increases with the number of laser shots. However, the surface roughness decreases as the number of laser shots increases at a low oxygen partial pressure(< 10e(-3) Torr). The grain size of poly-Si decreases as the oxygen partial pressure decreases. A thin surface oxide film formed by laser irradiation is the cause of these phenomena. There is no saturation point regarding the surface roughness, even at an oxygen partial pressure of 10e(-5) Torr, so that it is important to control the oxygen in the laser annealing ambient and on silicon film surfaces in order to control poly-Si TFT performance. (C) 2003 Wiley Periodicals, Inc.