Solvent-Assisted Laser Drilling of Silicon Carbide

Laser drilling of single crystalline silicon carbide (SiC) wafer in air, under water, and under methanol with a 355 nm wavelength laser is investigated and compared. Among these different media, laser drilling of SiC under a solvent, methanol, is found to produce holes with a relatively cleaner and smoother surface. Ablated particle redeposition at the entrance and exit of the holes is minimized. Minimum oxide (i.e., silicon dioxide) or heat-affected zones are observed and the surface finish inside the holes is much smoother and more uniform as compared with those drilled in air and under water. The improvement of drilling quality can be attributed to the relatively lower boiling temperature and better wettability of the solvents, which enhance the effects of cooling (thermal damage free) and ablated particle cleaning during laser drilling. It is found that the quality of laser drilling of SiC varied with the thickness of solvent layer, that is, water and methanol. A solvent layer of 500 mu m is suggested to be used for the enhancement of laser ablation rate and quality.