Effects of ultrasonic vibration direction and amplitude on SiC wafer thinning via chemical-assisted laser ablation

Silicon carbide (SiC) wafers for vertical power devices require thinning to 100 μm or less. Traditional laser ablation has low material removal rate (MRR) and poor surface quality. Combining laser ablation with ultrasonic vibration-assisted chemical etching is effective, yet the roles of vibration direction and amplitude are underexplored. Bidirectional vibration delivers larger thinning depth than single-direction vibration, while vertical vibration produces the smoothest surface. Larger vibration amplitude boosts MRR and reduces surface roughness, oxygen content, and remelted-layer thickness via enhanced cavitation, acoustic streaming, and ion transfer. Under optimized parameters, a 2 in. SiC wafer is successfully thinned to 100 μm with fine surface quality. This study identifies vibration direction and amplitude as key factors for efficient, high-quality SiC wafer thinning.