Improvement on Polishing Performance for Silicon Wafer of Nano-sized Ceria Abrasives by Tianium-doping

Titanium-doped ceria Ce_1-x Ti_xO₂(x=0,0. 1,0. 2,0. 3) powders were prepared via a co-precipitation method,using ethylene glycol (EG)/water as reaction mixed solvent and with precursor treatment of butanol azeotropic distillation. Moreover,the crystalline phase structure,morphology,zeta potential were characterized by X-ray diffraction(XRD),Transmission electron microscopy(TEM) and zeta potential analysis respectively. The polishing performance of the as-synthesized Ti-doped ceria abrasives for Silicon wafer was evaluated by the material removal rate (MRR) and atomic force microscopy (AFM). The results show that the ceria powder and Ti-doped ceria synthesized at 900℃ possesses nano-sized spheroidal morphology with a diameter of 40~50nm. A maximum MRR value of 139 nm·min^-1 was obtained by using Ce_0.8Ti_0.2O₂ nano-sized abrasives as a polishing powder for silicon wafer, and the surface roughness R_a in a 1. 0μm×1. 0μm area were found to be of 0.254 nm. This MRR value is ca. 2. 0 times of that obtained from by using pure ceria nanoparticles (that is,67nm·min^-1). However,MRR value of Ce_0.9Ti_0.1O₂ and Ce_0.7Ti_0.3O₂ abrasives are 112nm·min^-1 and 89nm·min^-1,respectively. The facts indicate that the polishing performance for silicon wafer of nano-sized ceria abrasives is significantly improved by Titanium-doping,which closely related to the increase of the zeta potential of Ti-doped ceria and the formation of CeTi₂O₆.