A study of surface defects of GaN during CMP process

The influence of mechanical action and chemistry function during CMP process on the pits, presented to the surface of GaN after polished, was discussed respectively. The relationship between the surface characterization after chemical mechanical polishing (CMP) and the concentration of the silica (SiO2) abrasive used for CMP of gallium nitride (GaN) substrates was investigated in detail. We yielded an ultra smooth surface with the average roughness (Ra) 0.0507 nm in 5×5 μm² and the processed surface had an atomic step-terrace structure which contained an extremely small number of tiny and shallow pits by CMP with the slurry included SiO₂ abrasive and effective oxidizer. Furthermore, we also got a high material removal rate (MRR) of 220nm/h.