Crystallization of Amorphous Silicon by Excimer Laser Annealing with a Line Shape Beam Having a Gaussian Profile

Amorphous silicon films of 50 mm×50 mm have been crystallized by 1-dimensionally scanning a line shape excimer laser beam with a Gaussian profile in the scanning direction, which basically reduces the nonuniformity of the 2-dimensional scanning method. The laser energy density and substrate temperature were varied. Grains as large as 100 nm with smooth surfaces were obtained with a laser energy density of 300 mJ/cm2with substrate heating of 400°C, where the conductivity was measured to be 9.6×10-6S/cm. Higher energy density increased the grain size and crystallinity but the conductivity decreased due to the separation of grain clusters. Substrate heating was found to considerably increase the grain size and crystallinity.