Research on Ultrasonic-Assistance Microarc Plasma Polishing Method for 4H-SiC

Silicon carbide (SiC) is widely used in high-power, high-frequency, and high-temperature electronic devices due to its excellent physical and chemical properties. However, its high hardness and chemical inertness make it difficult to achieve efficient and damage-free ultra-smooth surface processing with traditional polishing methods. This paper proposes a novel ultrasonic-assistance microarc plasma polishing (UMPP) method for high-quality and high-efficiency polishing of 4H-SiC. This study introduces a novel Ultrasonic-assisted Microarc Plasma Polishing (UMPP) method for achieving high-efficiency, high-quality surface finishing of 4H-SiC. The technique innovatively combines ultrasonic vibration with microarc plasma oxidation in a neutral NaCl electrolyte to overcome the limitations of conventional polishing methods. The UMPP process first generates a soft, porous oxide layer (primarily SiO2) on the SiC surface through plasma discharge, which is then gently removed using soft CeO2 abrasives. The key finding is that ultrasonic assistance synergistically enhances the oxidation process, leading to a thicker and more porous oxide layer that is more easily removed. Experimental results demonstrate that UMPP achieves a remarkably high material removal rate (MRR) of 21.7 μm/h while simultaneously delivering an ultra-smooth surface with a roughness (Ra) of 0.54 nm. Compared to the process without ultrasonic assistance, UMPP provides a 21.9% increase in MRR and a 28% reduction in Ra. This work establishes UMPP as a highly promising and efficient polishing strategy for hard and inert materials like SiC, offering a superior combination of speed and surface quality that is difficult to achieve with existing techniques.