Preparation of Cu-doped colloidal SiO_2 abrasives and their chemical mechanical polishing behavior on sapphire substrates

摘要

Cu-doped colloidal SiO_2 composite abrasives were synthesized by seed-induced growth method. Time of flight secondary ion mass spectroscopy and scanning electron microscopy analyses show that element copper has been doped into colloidal SiO_2, and the prepared Cu-doped colloidal SiO_2 composite abrasives are all ideal spherical and have good dispersibility. Chemical mechanical polishing (CMP) performances of Cu-doped colloidal SiO_2 composite abrasives on sapphire substrates were investigated using UNIPOL-1502 CMP equipment. Experimental results show that, the surface of sapphire polished by Cu-doped colloidal SiO_2 composite abrasive exhibit lower surface roughness (Ra) and higher material removal rate (MRR) than that of pure colloidal SiO_2 abrasive under the same testing conditions. Furthermore, the acting mechanism of Cu-doped colloidal SiO_2 composite abrasive in sapphire CMP was analyzed by X-ray photoelectron spectroscopy, and analytical results show that element Cu in composite abrasives can react with sapphire substrates to form dialuminium copper tetraoxide (Al_2CuO_4) during CMP, which promotes the chemical effect in CMP and leads to the improvement of MRR.