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

Abstract

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 (Ga2O3) 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 (Fe2+) and ferric ions (Fe3+) effectively and promoted the decomposition of the H2O2 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 H2O2, which increased the ·OH concentration and improved the oxidation characteristics of the solution.