Internal Nonthermal Melting of 4H-SiC Induced by Femtosecond Laser Pulses

As a third-generation semiconductor substrate for high-power electronics, silicon carbide (4H-SiC) faces severe processing challenges, with conventional slicing technologies exhibiting high loss and poor quality. The innovative application of femtosecond laser slicing technology is dedicated to improving the utilization efficiency of 4H-SiC single crystals, significantly reducing damage defects, greatly enhancing the cutting accuracy, and ultimately reducing the loss of 4H-SiC wafers during the slicing process. In this study, femtosecond laser manufacturing technology is used to generate a modified layer inside the 4H-SiC wafer for slicing. The formation mechanism of the modified layers under various laser energy densities is investigated by analyzing the morphology of the cross section. Real-time density functional theory simulations indicate that the laser induced the cleavage of the Si–C bond within 4H-SiC, leading to nonthermal melting and consequent weakening of the binding force within the modified layer. Effective separation of the 4H-SiC wafer was achieved with a tensile stress of only 15 N (∼1.6 MPa) under optimal processing parameters. These results hold a notable importance for large-scale semiconductor processing, offering promising prospects in the semiconductor industry.