ENERGY DEPOSITION AND NON-THERMAL ABLATION IN FEMTOSECOND LASER GROOVING OF SILICON

Abstract

Ultra-short pulsed laser ablation of crystalline silicon is characterized by a complicated heat diffusion and material removal process. In this research, a computational investigation is undertaken to understand the temperature distribution and heat effect in femtosecond laser grooving of silicon. Energy accumulation and threshold fluence of silicon ablation by femtosecond lasers are estimated through solving coupled energy balance equations. Thermal and optical properties of the material are considered in the calculations. The possible non-thermal ablation process and ablation geometry are analyzed for the case of succession of laser pulses. Thermal-mechanical response induced by temperature gradient is discussed around the laser ablation region. The agreement between the model calculations and experimental results show that this research provides an efficient thermal analysis method of the explosive laser-silicon interaction process, and a feasible way to optimize process parameters with minimum thermal damages.

Keywords:

• femtosecond lasers
• grooving
• material ablation
• silicon
• temperature distribution
• thermal effect

ACKNOWLEDGMENTS

This project was supported by the Australian Research Council (ARC), the Natural Science Foundation Project of CQ CSTC (No. 2008BB3190) and Doctoral Fund of Ministry of Education of China (No. 20090191120009).

Additional information

Notes on contributors

D. P. Wan

D. P. Wan is a UNSW Visiting Fellow from the State Key Laboratory of Mechanical Transmission, Chongqing University, Chongqing 400044, China.