High-Integrity Finishing of 4H-SiC (0001) by Plasma-Assisted Polishing

A novel machining method combined with the irradiation of atmospheric pressure plasma was proposed for the finishing of difficult-to-machine materials. The irradiation of helium-based water vapor plasma efficiently oxidized the surface of single-crystal 4H-SiC (0001), and a ball-on-disc test using an alumina ceramic ball revealed that the wear rate of SiC, the surface of which was modified by the irradiation of water vapor plasma, is 20-fold higher than that of the surface without plasma irradiation. Plasma-assisted polishing using CeO2 abrasives enabled us to improve the surface roughness of SiC without introducing crystallographical subsurface damage, and a scratch-free surface with a roughness of less than 0.3 nm rms was obtained.