In situ and ex situ diagnostics on melting and resolidification dynamics of amorphous and polycrystalline silicon thin films during excimer laser annealing

The liquid/solid interface motion and the temperature history of Si films d uring excimer laser annealing are observed by in situ experiments combining time-resolved (similar to 1 ns) electrical conductance, optical reflectivi ty/transmissivity at visible and near-infra-red wavelength, and thermal emi ssion measurements. The existence of partial and complete melting regimes a re detected. Ln the partial melting regime, the maximum temperature remains close to the melting point of amorphous Si (a-Si), since the laser energy is consumed by the latent heat of phase-change. In the complete melting reg ime, substantial supercooling, followed by spontaneous nucleation is observ ed. These phase transformations are consistent with the recrystallized poly -Si morphologies. It is also found that phase change temperature of poly-Si films is about 140 K higher than that of the a-Si films. (C) 2000 Elsevier Science B.V. All rights reserved.