Study on picosecond laser stealth dicing of 4H-SiC along [[formula omitted]] and [[formula omitted]] crystal orientations on Si-face and C-face

Abstract

Stealth dicing of semi-insulating 4H-SiC along [112¯0] and [11¯00] crystal orientations on Si-face and C-face was conducted by using infrared picosecond laser in combination with three-point bending split. It was demonstrated that the laser ablation points inside 4H-SiC samples, the critical fracture load, and the dicing quality of 4H-SiC samples were closely related to the crystal orientation. The critical fracture load of 4H-SiC along [112¯0] orientation is smaller than that along [11¯00] orientation. The longitudinal lengths of the laser ablation points increase with the increase of laser incident distance. For the same laser-modified layer, as laser was incident from C-face and processed along [112¯0] orientation, the laser ablation points have larger longitudinal length. The reasons for the impact of crystal orientation on laser-modified points were analyzed. The fractured 4H-SiC samples have chipping width less than 3 μm and section roughness less than 500 nm. Moreover, the dicing quality along [112¯0] orientation is better than that along [11¯00] orientation. This research can provide technical support for precision dicing of SiC wafers in semiconductor industry.