Laser-Power Dependence of Poly-Silicon Crystallization Using 355-nm Nanosecond Laser Annealing

We report the laser-power dependence of a poly-silicon thin film fabricated using a 355-nm nanosecond laser annealing. The temperature distribution in the annealed thin film was investigated using thermal simulations as the laser power was varied to obtain the optimum laser conditions for crystalizing an amorphous silicon film. Based on the simulation results, laser annealing experiments were conducted for a 100-nm-thick amorphous silicon film deposited on a SiO₂/Si wafer by using a Q-switched 355-nm nanosecond diode-pumped solid-state laser. The characteristics of the annealed silicon film were investigated using Raman spectroscopy and atomic force microscopy, which showed that both the crystal quality and the roughness of the annealed film increased as the laser was power increased. The experimentally obtained optimum laser power condition was found to be consistent with the simulation results. The demonstrated 355-nm nanosecond laser annealing is expected to provide a versatile solution for low-temperature poly-silicon processes.