Lateral Grain Growth of Poly-Si Films with a Specific Orientation by an Excimer Laser Annealing Method

Abstract

Dramatic lateral grain growth of nondoped poly-Si films (maximum grain size: ∼4.5 µm, film thickness: 500 Å) with strong crystallographic (111) orientation on glass substrates has been achieved using an excimer laser annealing method, namely at low temperature below 400°C and in a processing time shorter than a second, for the first time. The surface morphology of these poly-Si films was very smooth and the crystallinity was excellent with minimal internal defects. These poly-Si films have monomodally distributed grain sizes, with an average grain size of around 1.5 µm. As a result of experimental study, we speculate that the basic driving force behind this lateral grain growth was surface free energy anisotropy, as the same mechanism was observed in high-temperature furnace annealing of doped poly-Si thin films.