Dual-stage temporal laser stealth dicing of silicon carbide wafers with continuous crack propagation

Abstract

To address the difficulty of simultaneously regulating surface chipping damage and surface heat accumulation damage in laser stealth cutting (LSD) of silicon carbide (SiC) wafers, a novel dual-stage temporal laser stealth dicing (DLSD) method is proposed in this work. This method employs a two-stage laser process: first, a low-power modifying laser generates pre-modified SiC layers, followed by a high-power-inducing laser that promotes continuous crack propagation. Compared with traditional LSD methods, the DLSD method can achieve continuous propagation of induced cracks, thereby reducing surface chipping damage, without causing thermal accumulation damage on the surface, further improving wafer cutting quality. The mechanism of continuous crack propagation induced by the DLSD method is analyzed in detail. The pre-modified layer of amorphous SiC generated by the modifying laser enhances the absorption of the inducing laser, resulting in an increase in the length of the modified layer and promoting continuous crack propagation. The influence of inducing laser power and scanning speed on cutting quality is also thoroughly investigated. Results show that increasing the inducing laser power and scanning speed improves the length of the modified layer and induces continuous crack propagation. Specifically, when the modified laser power is 0.14 W, the induced laser power is 0.18 W, and the scanning speed is 800 mm/s, the maximum chipping width and sidewall surface roughness reach their minimum values of 6.0 μm and 1.15 μm, respectively.