Catalytic mechanism of tribochemical mechanical polishing on (0001) C-face of single crystal 6H-SiC substrate

Aiming at these problems of low efficiency, high cost, and environmental pollution in the chemical mechanical polishing (CMP) process of single crystal SiC substrates, a dry-type tribochemical mechanical polishing (DTCMP) method was proposed, and catalysts were added to enhance its efficiency, and the mechanism of catalyst action was investigated. In this study, different contents of nanocatalysts Fe2O3 and Fe3O4 were added to the DTCMP experiments on 6H-SiC substrates, and the material removal characteristics of SiC substrates were investigated under different polishing pressures and rotational speeds with different types of catalysts. Surface morphology, hardness change, surface elements, and crystalline structure of SiC before and after the polishing were analyzed using white light interferometer, nanoindenter, scanning electron microscopes, and X-ray diffractometer. The results show that the catalytic performance of the Fe3O4 catalyst was superior to that of the Fe2O3 catalyst and that the Fe3O4 catalyst can catalyze the production of more center dot OH from Na2CO3-1.5H(2)O(2) during the assisted polishing process. The material removal rate (MRR) was higher with the addition of catalyst than without, with MRR as high as 709.2 nm/h and surface roughness as low as 2.257 nm. Based on previous research results, this DTCMP achieves higher MRR compared with traditional CMP. In addition, the catalyst can promote the oxidation reaction on the SiC surface, accelerate the generation of surface oxide films, and thus reduce the surface hardness. Catalyst-assisted DTCMP exhibits superior performance in terms of efficiency, cost-effectiveness, and environmental sustainability, which can be an efficient method for preparing ultra-smooth SiC semiconductor materials and may inspire new ideas for their high-efficiency production.