Study of Cluster Magnetorheological-Chemical Mechanical Polishing Technology for the Atomic Scale Ultra-Smooth Surface Planarization of SiC

The growth of epitaxial layer of SiC wafer requires the surface of SiC substrate to reach an atomic scale accuracy. To solve the problems of low machining efficiency and low surface accuracy in the polishing process of SiC wafer, a novel ultra-precision machining method based on the synergistic effect of chemical reaction and flexible mechanical removal of the magnetorheological (MR) effect, the MR-chemical mechanical polishing (MRCMP) is proposed. In this technique, magnetic particles, abrasives and chemical additives are used as MR-chemical polishing fluid to form a cluster MR-effect flexible polishing platen under an applied magnetic field, and it is expected to realize an atomic scale ultra-smooth surface planarization with good controllability and high material removal rate by using the flexible polishing platen. Polishing experimental results of C surface of 6H-SiC crystal substrate indicate that an atomic scale zero-defect surface can be obtained. The surface roughness of C surface of SiC wafer decreased from 50.86nm to 0.42nm and the material removal rate was 98nm/min when SiC wafer was polished for 60 minutes.