Femtosecond laser burst mode processing for modified layer fabrication in 4H-SiC wafers

The femtosecond laser (fs-laser) slicing technique is anticipated to supplant wire sawing as the predominant method for slicing single-crystal silicon carbide (SiC). However, when 4H-SiC is exposed to strong infrared light, it distorts the energy transfer at the focal point due to nonlinear effects (e.g., plasma generation), causing fundamental limitations in material processing. This study employs burst-mode irradiation to redistribute single-pulse energy into temporally spaced sub-pulses, enabling precise control over both the material's energy absorption and localized electron dynamics. In experiments, etching efficiency peaks at the optimal delay window, attributed to resonant coupling between sequential sub-pulses and lattice relaxation dynamics. Spatial precision is maximized under equal-energy sub-pulses (1:1), reducing heat-affected zone area through suppressed electron diffusion prior to the critical carrier density threshold.