Micromachining of 4H-SiC using femtosecond laser

As a new type of semiconductor material, silicon carbide has received more and more attention on its groove processing. Femtosecond laser grooving process was proposed to implement near damage-free and high efficient micromachining of silicon carbide. The size prediction models of groove depth and width are established and the experimental verification is carried out. The verification results indicate the modified models can perform predictions with acceptable errors. An experimental study is carried out to characterize the femtosecond laser grooving process for silicon carbide. The effects of laser parameters, including laser power, scan speed, pulse repetition rate and scan repetitions, on the characteristics of grooves, the size of the heat affected zone and surface roughness are discussed. The phase change and composition change of the material is analyzed by electron scanning microscope and Raman scattering spectrum, and some suggestions are proposed to get better surface quality. It can significantly reduce or even eliminate thermal damages such as the surface roughness (within 0.05 µm) and the re-solidified substance by scan repetitions. In order to reduce the introduction of oxygen, oxygen-free environment can be recommended.