CW laser-assisted splitting of SiC wafer based on modified layer by picosecond laser

Abstract

Silicon carbide (SiC), the third-generation semiconductor material, is important in developing electronic power devices. Compared to wire sawing technology, Laser splitting SiC is an efficient way to produce SiC wafers with reduced material loss. In this work, we propose a new method of continuous wave (CW) laser-assisted splitting of SiC wafer based on modified layer by picosecond laser. For the process of CW laser irradiation on the modified layer, thermal–mechanical numerical simulations were performed to calculate the temperature and stress fields during laser loading. The mechanism of CW laser-assisted SiC wafer splitting was analyzed to guide the selection of CW laser parameters. The microstructure, element distribution, and stress state of the split SiC wafer surface were investigated and analyzed. The results showed that laser processing did not affect the crystal structure and carrier concentration of SiC. Compressive stress was generated on the splitting surface. Polycrystalline carbon and single crystalline silicon appeared on the splitting surface with a 50-250 nm thickness. The layer with compressive stress and polycrystalline microstructures can be removed after grinding and polishing.