The picosecond laser ablation mechanism of monocrystalline silicon by coupling two-temperature model (TTM)-Molecular dynamic (MD)

Abstract

Monocrystalline silicon is the most widely used material in microchips, microsensors and photovoltaic systems, where ultrashort pulse laser has been applied in grooving and holing. This paper investigates the ablation mechanism of monocrystalline silicon by picosecond laser, where a TTM-MD (Two-temperature model-Molecular dynamics) model was established based on the interaction theory between ultrashort pulse laser and Si. The effects of plasma shielding and surface reflectivity on the laser irradiation energy are investigated to analyze the variation of carrier temperature, lattice temperature and carrier density on the monocrystalline silicon surface. The occurrence of material melting, bubble nucleation and phase explosion are simulated to explore the material removal mechanism and the effect of laser fluence on the ablation behavior. The simulation model was finally verified by the ablation threshold experiments where a high-speed camera was applied to monitor the ablation process.