Polarization dependences of the laser in 4H-SiC wafer slicing

This study focuses on the influence of the polarization of incident light in the laser slicing of 4H-SiC wafers. The structure of longitudinal damage within the material after laser modification was measured and analyzed. The impact of laser pulse energy on this structure was studied. Differences in longitudinal damage under different polarization states were compared. In addition, the effects of laser polarization on the modification of line width and lateral crack propagation were investigated. A vector diffraction model was established to analyze the propagation characteristics of beams with different polarization states during focusing. The results indicate that a linearly polarized beam perpendicular to the scanning direction offers superior modification efficacy compared to other directions of linear polarization and circular polarization. Azimuthally and radially polarized beams substantially decrease the length of longitudinal damage and reduce the difficulty of delamination. Compared to the linearly polarized beam perpendicular to the scanning direction, the azimuthally polarized beam reduces the longitudinal damage length by 49.3% and the delamination stress by 47.0%. In comparison, the radially polarized beam reduces the longitudinal damage length by 39.4% and the delamination stress by 53.8%.