Fig. 1. Schematic illustration of the femtosecond laser micromachining system

Fig. 2. Schematic illustration of femtosecond laser processing for 4H-SiC sensitive diaphragm

Fig. 3. Schematic illustration of the profile and light intensity distribution of a Gaussian beam

Fig. 4. Energy distribution of the femtosecond laser

Fig. 5. SEM images of 4H-SiC processed by femtosecond laser for single-line scanning

Fig. 6. SEM images of 4H-SiC with different number of processing laps or ∆H

Fig. 7. Schematic illustration of the superposition of light intensity in different cross-sections with the ∆d of 20 μm

Fig. 8. SEM images for the ablated surface of 4H-SiC with different number of processing laps

Fig. 9. SEM images of 4H-SiC samples processed with different scanning directions

Fig. 10. The dependence of the ablation depth for one lap，light intensity，RMS roughness of the ablated surface，the superposition of light intensity，and RMS roughness per unit ablation depth on laser single pulse energy

Fig. 11. The dependence of the ablation depth for one lap，light intensity，RMS roughness of the ablated surface，the superposition of light intensity，and surface morphology on scanning line interval

Fig. 12. SEM images of 4H-SiC samples processed with different material removal methods