GaN晶片芬顿反应化学机械抛光液组分优化

针对芬顿反应CMP抛光GaN晶片的抛光液，开展以表面质量为评价指标的参数优化试验，找出抛光液组分的最优配比。结果表明:当H₂O₂质量分数为7.5%时，GaN晶片加工表面效果最优，表面粗糙度达到3.2 nm；催化剂能有效调节芬顿反应的速率，对比液体催化剂FeSO₄溶液和固体催化剂Fe₃O₄粉末，固体催化剂Fe₃O₄粉末能在溶液中持续电离Fe2+，使芬顿反应能在整个加工过程中持续作用。当Fe₃O₄粉末粒径为20 nm时，抛光效果最佳，表面粗糙度达到3.0 nm；对比氧化铝、氧化铈、硅溶胶磨料，硅溶胶磨料抛光的表面效果最佳，晶片表面粗糙度达到3.3 nm；当硅溶胶磨料质量分数为20.0%，磨料粒径为60 nm时，抛光后晶片表面粗糙度达到1.5 nm。抛光液组分优化后，采用最优的抛光液组分参数抛光GaN晶片，其能获得表面粗糙度为0.9 nm的光滑表面。 

Fenton reaction chemical mechanical polishing liquid composition optimization of polishing GaN wafer

Aiming at the polishing liquid used for polishing GaN wafers by Fenton reaction CMP, a parameter optimization experiment was carried out with the surface quality as the evaluation index, and the optimal ratio of the polishing liquid components was found out. The results show that when the mass fraction of H₂O₂ is 7.5%, the surface of GaN wafer processing is the best, and the surface roughness reaches 3.2 nm; the catalyst can effectively adjust the rate of the Fenton reaction. Compared with the liquid catalyst FeSO₄ solution and the solid catalyst Fe₃O₄ powder, the solid catalyst Fe₃O₄ powder can continuously ionize Fe2+ in the solution, so that the Fenton reaction can continue to work throughout the process. When the particle size of Fe₃O₄ powder is 20 nm, the polishing surface is the best, and the surface roughness reaches 3.0 nm; compared with alumina, cerium oxide, and silica sol abrasives, the best surface polishing effect can be achieved while using the silica sol abrasives, and the surface roughness reaches 3.3 nm; when the mass fraction of silica sol abrasive is 20.0% and the abrasive particle size is 60 nm for polishing, the surface roughness reaches 1.5 nm. After optimizing the composition of the polishing liquid, the GaN wafer was polished with the optimal composition parameters of the polishing liquid, and a smooth surface with a surface roughness of 0.9 nm could be obtained.