Plasma-assisted polishing of gallium nitride to obtain a pit-free and atomically flat surface

Plasma-assisted polishing (PAP), which combines plasma modification and soft abrasive polishing, was used to flatten GaN. After the irradiation of CF4 plasma, GaN was modified to GaF3, greatly decreasing its surface hardness. The modified layer was removed by polishing using a CeO2 grindstone for surface flattening. It was revealed that while many pits were generated in conventional CMP using SiO2 or CeO2 slurry, which deteriorated the surface integrity and roughness of GaN, a pit-free and atomically flat GaN surface with a Sq roughness of 0.1 nm order was obtained by the application of PAP, which is a dry polishing process. (C) 2015 CIRP.