Crystal anisotropy-modulated laser modification for high-efficiency and low-loss exfoliation of 4H-SiC ingots

• Crystal anisotropy regulates laser-induced crack propagation kinetics. • A physical loop linking crack period, roughness, and force is revealed. • Orthogonal scanning strategy (180°+270°) decouples force and roughness. • Synergistic regulation achieves low roughness and low force. • High-efficiency and low-loss exfoliation of 6- to 8-inch SiC ingots was achieved. Laser internal modification slicing has emerged as a key technique for minimizing kerf loss and fabrication costs of 4H-SiC substrates. However, the pronounced anisotropy of single-crystal 4H-SiC significantly dictates micro-crack propagation and slicing quality, yet the underlying regulatory mechanisms remain elusive. Here, we systematically investigate the coupling mechanism between nanosecond laser scanning direction and crystallographic orientation, specifically focusing on the cleavage steps induced by the 4° off-axis angle. It is revealed that scanning relative to atomic-scale steps modulates crack dynamics: “up-step” scanning induces a positive feedback defocusing effect, generating long-period cracks with low exfoliation force but high roughness. Conversely, “down-step” scanning triggers a negative feedback suppression effect, yielding short-period cracks with low roughness but high exfoliation force. Linking crack periodicity, exfoliation force, and roughness, we propose a “cleavability-prioritized” orthogonal scanning strategy (180°+270°). This resolves the exfoliation-quality trade-off by utilizing an initial pass to construct primary cleavage planes, followed by an orthogonal pass to refine the crack network. Implementing this enabled high-efficiency slicing of 6-inch and 8-inch SiC ingots in 20 and 30 min, with material losses of ∼ 80 μm and ∼ 100 μm, respectively, providing a foundation for cost-effective manufacturing.