STRUCTURE OF POLY-SI FILMS OBTAINED BY LASER ANNEALING

We investigated the structural characteristics of polycrystalline sili con films formed by: (a) single-step laser annealing and (b) two-step furnace at 600 degrees C and laser annealing of amorphous silicon laye rs. The structure of poly-Si films of these two groups was studied by cross-section and plane-view transmission electron microscopy observat ions. In the first group and for constant substrate temperature, cryst allite size was found to increase with increasing laser beam energy. H owever, in this case the grain size never exceeded 300 nm. In the seco nd group large crystallites are formed during the furnace annealing ha ving a high density of in-grain defects. As laser energy increases the in-grain defect density decreases, but the grain size remains constan t. Above a certain critical energy however, grain size is drastically reduced whereas the defect density within the grains remains low. (C) 1997 Elsevier Science S.A.