Silicon carbide (SiC), as a third-generation semiconductor material, has important applications in high-power electronic devices due to its exceptional physicochemical properties. However, conventional diamond wire sawing techniques suffer from high material loss (kerf width exceeding 200 μm), low efficiency, and environmental pollution. To achieve high-quality and low-stress cutting of SiC wafers, this study proposed a peeling technique combining nanosecond laser internal modification with mechanical stretching, aiming to achieve high-quality and low-stress peeling of 350 μm-thick 4H-SiC wafers. The influence of process parameters on modified layer structures and peeling quality was systematically investigated, while the physical mechanisms of nanosecond laser-induced SiC modification and crack propagation were elucidated, providing theoretical foundations for industrial applications of laser peeling technology.

A fiber laser with a wavelength of 1064 nm and pulse width of 14 ns was utilized for internal modification of SiC wafers, followed by mechanical peeling via a universal tensile testing machine. The morphology, elemental distribution, and phase structure of modified layers were characterized using optical microscopy, confocal 3-D microscopy, scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), and Raman spectroscopy. Single-factor experiments were conducted to evaluate the effects of pulse energy (normalized range: 0~1), nominal focal depth (100 μm～250 μm), scanning interval (100 μm～200 μm), and scanning direction (1 −1 0 0 vs. 1 1 −2 0 crystallographic orientations) on modified layer morphology, transverse crack propagation, and peeling quality. The mechanisms of nanosecond laser-induced crystalline-to-amorphous phase transformation and transverse crack propagation were analyzed based on photothermal effects, multiphoton excitation, and thermal stress theory.

Laser pulse energy was identified as the most critical parameter influencing internal modification. Increased pulse energy enhanced laser energy density, significantly improving transverse crack propagation length while widening modified channels (Figure 3 and Figure 4). Elevated focal depth reduced energy density, suppressing crack propagation and narrowing modified channels (Figure 6). Excessive energy density at shallow focal depths was likely to induce surface ablation and crack damage. At a nominal focal depth of 175 μm, uniform crack gaps were achieved without surface damage (Figure 7). Scanning direction exhibited a pronounced impact on peeling force due to differences in crack morphology, while scanning interval showed minimal influence. Peeling force variations among 100 μm, 150 μm, and 200 μm intervals were less than 0.05 MPa, but larger intervals improved processing efficiency. Scanning along the 1 −1 0 0 orientation produced regular "peak-valley" morphologies on peeled surfaces with an average tensile force of 2.36 MPa, as transverse cracks propagated along the 4° inclination angle of crystal planes (Figure 8). In contrast, scanning along 1 1 −2 0 generated disordered "terrace-like" morphologies with an average tensile force of 2.77 MPa (Figure 11). The average surface roughness (S_a=4.404 μm) of 1 −1 0 0-oriented peeling surfaces was significantly lower than that of 1 1 −2 0-oriented surfaces (S_a=5.565 μm), with unilateral material loss reduced by over 50% (Figure 11). SEM and Raman spectroscopy confirmed that nanosecond laser irradiation induced localized melting via multiphoton excitation and avalanche ionization, while thermal stress and high-pressure silicon vapor promoted crack propagation. Phase transformation from crystalline to amorphous SiC (evidenced by broadening and weakening of the 777 cm⁻¹ Raman peak) and chemical decomposition into amorphous Si (443 cm⁻¹～491 cm⁻¹ broad band) and amorphous C (G-band at 1338 cm⁻¹, D-band at 1516 cm⁻¹) were observed in modified regions (Figure 12). EDS analysis revealed a near 1:1 Si/C atomic ratio in transverse crack regions (retaining crystallinity), whereas Si enrichment was detected in modified regions (Table 3).

This study validates that nanosecond laser peeling technology effectively addresses the material loss and efficiency challenges in SiC wafer slicing. Optimized process parameters (pulse energy: 0.6, focal depth: 175 μm, scanning interval: 200 μm, 1 −1 0 0 orientation) enabled high-quality slicing with peeled surface roughness <5 μm, unilateral material loss <40 μm, and tensile force <2.4 MPa. Nanosecond lasers induced crystalline-to-amorphous phase transformation and chemical decomposition in SiC through photothermal effects, while transverse crack propagation was synergistically regulated by laser energy density and thermal stress. Scanning direction determined peeling quality by controlling crack morphology. These findings provide theoretical and practical guidance for efficient and low-damage slicing of SiC wafers, advancing the application of laser peeling technology in next-generation semiconductor material processing.