Crackless femtosecond laser percussion drilling of SiC by suppressing shock wave magnitude

Femtosecond lasers have attracted attention as tools for the microfabrication of various materials, such as semiconductors, insulators, and metals. When hard and brittle materials are processed by femtosecond lasers, shock waves that propagate during processing generate cracks around the processed area, making precision processing difficult. In this study, we propose and demonstrate multi-step drilling where, after drilling a pilot hole with a small pulse energy, the hole is expanded by increasing the pulse energy in a stepwise manner without generating strong shock waves. The proposed method suppresses cracks in silicon carbide by approximately 70% and could be an important option for femtosecond laser microdrilling.