Optimization of the plasma oxidation and abrasive polishing processes in plasma-assisted polishing for highly effective planarization of 4H-SiC

For the finishing of difficult-to-machine materials, plasma-assisted polishing (PAP), which combines modification by water vapor plasma and polishing by a soft abrasive, was proposed. Optimization of plasma oxidation and abrasive polishing was conducted to increase the material removal rate of PAP, which was applied to 4H-SiC (0 0 0 1). It was found that with a low concentration of water vapor in helium gas, the plasma oxidation rate was greatly increased. Also, because of the different oxidation rates of the four types of terrace that appear alternately in 4H-SiC, a high removal rate of the oxide was necessary to obtain a uniform step-terrace structure with atomic order. (C) 2014 CIRP.