Abstract A MHz burst-mode femtosecond laser was employed to examine how burst sub-pulse number influences internal modification and wafer dicing in thin n-type 4 H-SiC. Single-pass line scanning was first used to evaluate the roles of laser power, scanning speed, and sub-pulse number in determining the morphology of the modified region. The results indicated that burst conditions with two sub-pulses tended to promote lateral crack formation, whereas increasing the sub-pulse number to 3–5 suppressed lateral cracking and produced a more confined modified structure. Based on these observations, multi-layer internal modification was further applied for dicing. A continuous diced section was obtained, and the resulting cross-section exhibited a surface roughness of Sa = 0.8 μm. The findings demonstrate that the sub-pulse number is a key parameter governing crack formation, modified-layer geometry, and the feasibility of burst-mode femtosecond laser dicing of 4 H-SiC wafers.
Wang et al. (Mon,) studied this question.