Electro-chemical mechanical polishing of single-crystal SiC using CeO2 slurry

• Ceria slurry was used as an electrolyte for anodic oxidation as well as a polishing medium to remove the oxide layer.
• As a result of anodic oxidation, the surface hardness of SiC decreased from 34.5 GPa to 1.9 GPa.
• After 30 min of ECMP, a scratch-free and smooth surface with a root mean square roughness of 0.23 nm was obtained.

Electro-chemical mechanical polishing (ECMP), which combines anodic oxidation and soft abrasive polishing, was applied to single-crystal SiC. Ceria (CeO2) slurry was used as an electrolyte for anodic oxidation as well as a polishing medium to remove the oxide layer. As a result of anodic oxidation, the surface hardness decreased from 34.5 GPa to 1.9 GPa, which made it possible to polish the oxidized SiC surface using a very soft abrasive such as CeO2. It was found that the material removal rate (MRR) of ECMP for a diamond-abrasive-polished surface was 3.62 μm/h. ECMP using CeO2 slurry was conducted for 30 min on a diamond-abrasive-polished surface. All the scratches were completely removed and a smooth surface with a root mean square (RMS) roughness of 0.23 nm was obtained.