Study on the affecting factors of material removal mechanism and damage behavior of shear rheological polishing of single crystal silicon carbide

摘要

Single-crystal silicon carbide (4H-SiC) suffers from low material removal rate (MRR) and poor surface quality during the polishing process due to its high hardness and chemical inertness. In this study, shear rheological polishing (SRP) was innovatively introduced for 4H-SiC surface polishing, and the effects of factors such as inclination angle, polishing speed, diamond abrasive concentration, and abrasive size on the MRR and surface quality were systematically investigated. In addition, characterization tools such as white light interferometry (WLI), atomic force microscopy (AFM), and scanning electron microscopy (SEM) were used to reveal the material removal mechanism and surface quality of shear rheological polishing. The processing damage behavior was also investigated by positron annihilation technique and transmission electron microscopy (TEM). Microstructural characterizations indicated that the inclination angle had the greatest influence on the polishing efficiency and surface quality of 4H-SiC. At a suitably controlled inclination angle (7 degrees), the surface roughness of 4H-SiC dramatically reduced from 13.50 nm to 0.30 nm Ra after polishing for 15 min, and the corresponding optimum MRR of 12.12 mu m/h was obtained. In addition, results of the TEM and positron annihilation showed that the subsurface damage of the SiC samples could be effectively removed after SRP process. The study demonstrated that this novel shear rheological polishing could be employed for high efficiency, high quality, and low damage polishing of single crystal 4H-SiC wafer for semiconductor industrial applications.

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