The manufacturing process of SiC semiconductor devices involves multiple steps, including crystal growth, slicing, polishing, cleaning, oxidation, etching, and packaging. Among these, crystal growth and wafer slicing are the most critical processes, as they significantly impact the substrate quality, subsequent processing efficiency, and final device performance.
Slurry wire sawing is a free-abrasive wire sawing method. A metal wire is fed from a pay-off unit through wire guides and tension control units into guide rollers. Multiple metal wires on the guide rollers form a wire web, which moves at a certain linear speed driven by the rotation of the guide rollers. Simultaneously, a single-crystal SiC ingot is fed toward the wire web at a certain feed rate by a feeding unit. As the ingot moves, slurry carrying abrasive grains is sprayed onto the wire web through nozzles. The metal wire drives the slurry, bringing the abrasives to the processing zone while applying pressure to the abrasives. The abrasives perform cutting in the solid–liquid mixing region between the ingot and the metal wire. In slurry wire sawing, the slurry acts as a carrier for the abrasives, providing stable dispersion of suspended particles, and therefore requires a certain viscosity. At the same time, the slurry must exhibit good fluidity to drive the abrasives along with the wire saw. To prevent excessive temperature rise in the cutting zone, the slurry also needs good thermal conductivity. In practice, polyethylene glycol is commonly used as the dispersant for abrasives. Slurry wire sawing, with its notable advantages such as narrow kerf width and uniform slicing thickness, dominates the slicing of 4H-SiC materials and is a key technology for achieving high-precision cutting. However, this technique has several clear drawbacks: first, relatively low processing efficiency due to limited slurry fluidity and abrasive utilization, resulting in slow cutting speeds; second, significant waste of abrasives during cutting, leading to low abrasive utilization and increased processing costs; moreover, the use of slurry generates pollution, restricting its application scope.
In recent years, diamond wire sawing technology has attracted widespread attention due to its advantages of high processing efficiency, low wire consumption cost, and environmental friendliness. Diamond wire sawing removes material by using diamond abrasives fixed on the wire saw as fixed cutting points that scratch the crystal surface. The diamond wire is typically a stainless steel wire coated with a nickel-based alloy or resin layer. Micro-sized hard particles are embedded as abrasives in the nickel-based alloy or resin layer through electroplating, bonding, or welding techniques. During cutting, the abrasives directly contact the ingot surface and remove crystal material in the kerf via two-body wear. In silicon wafer slicing, silicon carbide (SiC) particles are often used as the hard abrasive. For 4H-SiC wafer slicing, diamond particles are used as abrasives. Unlike slurry wire sawing, this technique typically uses a water-based coolant and is therefore more environmentally friendly. Traditional wire sawing of SiC suffers from large material loss and long processing times. The contact-based machining method also introduces defect damage and residual stress, leading to poor product quality in some cases and high manufacturing costs. As wafer sizes continue to increase, how to effectively suppress slicing-induced defects and warpage while ensuring slicing efficiency and material utilization has become a key bottleneck for further cost reduction and efficiency improvement in the SiC industry.
Laser lift-off technology, with its notable advantages of non-contact processing, high precision, and low loss, has emerged as a key direction to break through the bottlenecks in SiC substrate fabrication. This technology combines vertical laser modification and controlled crystal delamination. Its core lies in precise energy control to form a cleavage interface at a predetermined depth inside the crystal, thereby achieving high-precision, high-efficiency wafer separation. Traditional laser processing methods mainly rely on ablation effects or parallel modification techniques, typically suitable only for cutting along the laser incidence direction. In contrast, laser lift-off technology uses precision mechanical structures or surface stress layers to induce the crystal to crack along a predetermined cleavage plane, achieving complete delamination of a thin layer. This technology offers significant advantages in precision control, material damage reduction, and broad material applicability, better meeting the needs of low-loss, high-efficiency, large-scale industrial production. Laser processing methods effectively improve the manufacturing efficiency of hard and brittle materials, but the processing quality depends on precise control of process parameters, whose optimization directly affects the final outcome.
In summary, unlike traditional wire sawing methods, the non-contact laser lift-off technology effectively avoids issues such as cutting tool wear and SiC wafer failure caused by mechanical stress, thereby achieving high-quality and high-precision delamination. Laser lift-off technology significantly improves the processing efficiency and quality of SiC wafers while reducing the preparation cost of SiC substrates, offering outstanding advantages of high production efficiency and low material loss.