Enhancement Mechanism of Chemical Mechanical Polishing for GaN Based on Electro-Fenton Reaction

In order to obtain a high material removal rate (MRR) with good surface quality, the electro-Fenton reaction was used to assist the chemical mechanical polishing (CMP) for the gallium nitride (GaN) substrate. The fluorospectrophotometry, potentiodynamic polarization method and X-ray photoelectron spectroscopy (XPS) were applied to analyze the enhancement mechanism of the CMP of GaN assisted by electro-Fenton reaction. The results revealed that the hydroxyl radical (·OH) concentration in the electro-Fenton solution increased by 41.75%, and the corrosion potential decreased by 24.67% compared with the Fenton solution, which proved that the electro-Fenton solution had strong corrosion characteristics and the gallium oxide (Ga 2 O 3 ) formation rate on the wafer surface was accelerated. A high MRR of 274.45 nm h −1 with surface roughness (Ra) of 0.88 nm was obtained by electro-Fenton solution. The reduction reaction of the electric field increased the conversion rate of ferrous ions (Fe 2+ ) and ferric ions (Fe 3+ ) effectively and promoted the decomposition of the H 2 O 2 solution. Meanwhile, the oxidation reaction on the GaN wafer surface was enhanced, and high processing efficiency was achieved. Furthermore, the electric field generated a small amount of H 2 O 2 , which increased the ·OH concentration and improved the oxidation characteristics of the solution.