Research on Diamond Nano-Grinding of 4H-SiC Crystals and Wear of Abrasives with Different Sharpness

Single-crystal 4H-SiC, as a wide-bandgap semiconductor material, has become a key substrate for high-power electronics and radio frequency devices due to its outstanding characteristics such as high-voltage tolerance, high-temperature stability, high-frequency efficiency and low loss. However, its inherent properties of high hardness and low fracture toughness also pose severe challenges to the ultra-precision processing of wafer substrates. In this study, through molecular dynamics methods, the influence of diamond abrasive grains with different sharpness on the processing of 4H-SiC at different grinding speeds was simulated, with a focus on analyzing its surface morphology, material removal behavior and subsurface damage characteristics. The structural evolution of 4H-SiC workpieces and diamond abrasive grains was identified through the radial distribution function, and the dynamic changes in temperature and stress during processing were further investigated to clarify the mechanism of abrasive wear and graphitization phenomena. The results show that regular octahedral abrasive grains with higher sharpness have better material removal efficiency, but they also cause more significant subsurface damage. Increasing the grinding speed helps to reduce the depth of subsurface damage. In addition, high temperature and high stress are the key factors leading to the transformation of diamond into graphite. Even under low-speed grinding conditions, the edges of the abrasive grains may still undergo graphitization due to stress concentration. The above findings have theoretical significance for an in-depth understanding of the material removal mechanism of 4H-SiC nano-grinding, and can also provide an important reference for the development of high-performance grinding wheels for SiC grinding.