Research on ultraviolet femtosecond pulsed laser cutting 4H-SiC

As the most popular semiconductor material, silicon carbide has received extensive attention from the industry. In this study, a UV laser with a center wavelength of 343𝑛𝑚, a pulse width of 500𝑓𝑠, a maximum average power of 12𝑊, and an adjustable repetition rate of 400~500𝑘𝐻𝑧 was used to conduct cutting process experiments on 4H-SiC. A 3D color scanning electron microscope (SEM) and a metallographic microscope are used to observe the cutting section and surface. The effects of laser repetition rate, laser average power, scanning speed and other process parameters on the cutting quality were studied. The ablation threshold of the silicon carbide was obtained to be 44.62𝑚𝐽/𝑐𝑚2. The best cutting result we made is at the condition with the laser average power 2𝑊, the scanning speed 150mm/s, the repetition rate 500kHz, and the scanning number 22 𝑡𝑖𝑚𝑒𝑠. Using a metallurgical microscope, it was observed that the cutting surface was neat, without chipping or cracking, and the thermal effect was negligible. The 3D color SEM image are shown that the taper of the slit was 5.75° and the roughness of the cut section was less than 2.69μm.