Ultra-fine grooving technology for 4H-SiC substrate using poly-crystalline diamond (PCD) blade

A unique poly-crystalline diamond (PCD) blade with three-dimensional high density cutting edges was developed to machine ultra-fine grooves on a silicon carbide (SiC) substrate with a mirror-like finish. Focusing on the working surface of the high-density three-dimensional cutting edge of the PCD blade, we aligned the tips of the individual micro-cutting edges on the same plane to enable individual and independent machining in the transverse direction of the working surface of the blade. As a result of machining a groove on the SiC substrate using the PCD blade, an extremely narrow groove of 15.29 µm in average width and 89.04 µm in average depth could be formed. The cross-sectional shape of the groove bottom was also sharply machined with an extremely small corner R on the order of 1 µm. The cross-sectional shape of the blade was accurately transferred to a groove shape with sharp edges. In addition, the surface roughness of the groove bottom in the blade traveling direction had a mirror-like state with less that Ra1 nm. Although only one linear crack remained, it is possible to eliminate the crack generation by removing the protruding cutting edges.