Anisotropy of chemical mechanical polishing in silicon carbide substrates

The chemical mechanical polishing (CMP) of the Si face (0 0 0 1), the C face ( 0   0   0   1 ¯ ), the a face ( 1   1   2 ¯   0 ) and the m face ( 1   1 ¯   0   0 ) of silicon carbide (SiC) wafers was investigated. It was found that the removal rate and surface quality varied greatly with the different crystal face orientations during the CMP. Surface quality was characterized with atomic force microscopy (AFM) in terms of root mean square (RMS) roughness and high-resolution X-ray diffractometry (HRXRD). The optimum CMP process yielded a superior Si face finish with 0.096 nm RMS roughness, while no polishing action was observed on the C face. Results were explained in light of the atomic structure. CMP mechanisms of four faces were analyzed based on different polishing results.