Preparation of Cu-doped colloidal SiO2 abrasives and their chemical mechanical polishing behavior on sapphire substrates

Abstract

Cu-doped colloidal SiO2 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 SiO2, and the prepared Cu-doped colloidal SiO2 composite abrasives are all ideal spherical and have good dispersibility. Chemical mechanical polishing (CMP) performances of Cu-doped colloidal SiO2 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 SiO2 composite abrasive exhibit lower surface roughness (Ra) and higher material removal rate (MRR) than that of pure colloidal SiO2 abrasive under the same testing conditions. Furthermore, the acting mechanism of Cu-doped colloidal SiO2 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 (Al2CuO4) during CMP, which promotes the chemical effect in CMP and leads to the improvement of MRR.