High-speed observation of pulse energy and pulse width dependences of damage generation in SiC during ultrashort pulse laser drilling

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Ultrashort pulse laser processing is a potential method for microfabricating silicon carbide (SiC). However, it is difficult to precisely process SiC using this method because numerous damages are generated around the processed region. Although various studies have investigated the optimal processing conditions, the effects of the conditions on the high-speed phenomena during processing and the effects of these phenomena on the processed shapes and generated damages remain largely unclear. In this study, we combine a high-speed camera with ultrashort laser probe pulses to visualize the phenomena driven by each pulse irradiation and investigate the pulse energy (50, 100, 200 μJ) and pulse width (180 fs, 1 ps, 10 ps) dependencies. The results clarify that for larger pulse energy, stronger stress waves propagate inside SiC, causing greater damages. In addition, we find that for a pulse width of 10 ps, thermal damage occurs near the hole entrance. The clarified effects of the processing conditions on the stress wave propagation, damage generation, and processed shapes will contribute significantly to developing methods for precision processing of SiC.