Morphological evolution of 4H-SiC substrates in Stealth Dicing by using picosecond laser

In the paper, the morphological evolution of 4H-SiC substrates during Stealth Dicing was investigated by using a picosecond laser. The results show that the pulse energy is a critical factor to determine the dimensions of the modified structure, with high pulse energy inducing a high aspect ratio laser self-focusing morphology inside the material.

Microstructural analysis reveals three types of modified structures: clustered, filamentous, and block-like structures, which are primarily influenced by the pulse energy and repetition frequency. Cracks in the modified structure propagate from the interior of the material toward the cleavage direction, range of which along with the degre of modification are affected by the scanning times. By optimizing the scanning distance, the SiC sample is successfully separated under an applied force of 20 N without chipping.