A synergistic polishing technology by mixed abrasives with photocatalysis and fenton reaction

In this work, we propose a novel polishing method to improve the surface quality and polishing efficiency of GaN wafers. The proposed polishing technique was for use on GaN wafers using TiO2/ZrO2 soft and hard mixed abrasives combined with photocatalytic assistance and the Fenton reaction. The polishing effect obtained via this methodology was compared with that obtained using other methods; the effects of different parameters on the polishing of GaN were explored, including the illumination method, pH value of the polishing liquid, H2O2 concentration, and Fe2+ concentration; the effects of different mechanical conditions on the polishing of GaN were also investigated, including the polishing pressure, polishing disk rotation speed, polishing liquid flow rate, and polishing time. The parameters describing the polishing technique developed here are optimized. It is found that both the mechanical and chemical processes have a significant impact on the material removal rate (MRR) and the surface roughness of the polished GaN. After optimizing the process parameters via orthogonal tests, the MRR of GaN is found to be 178.63 nm/h, and the surface roughness (Ra) is reduced to 0.244 nm. The combination of soft and hard mixed abrasives combined with photocatalytic assistance and the Fenton reaction is found to realize a high-efficiency and low-damage single-crystal polishing process for use on GaN.