Simple and facile synthesis of single-crystal CeO2 abrasives and its highly efficient removal mechanism on SiO2 film

Abstract

CeO2 nanoparticles are one of the key abrasives for chemical mechanical polishing (CMP) in advanced integrated circuits. However, synthesizing highly chemically reactive CeO2 often involves ion doping, high-temperature calcination or reduction, which increase cleaning challenges and risk scratching wafers. We developed a simple and facile method for synthesizing single-crystal CeO2. It exhibits superior polishing performance compared to commercial CeO2, with the material removal rate (MRR) increasing to 4141.45 from 3649.99 Å/min and the surface roughness (Sa) decreasing to 0.533 from 0.647 nm. The CeO2 abrasives were characterized by X-ray Diffraction (XRD), advanced microscopy techniques (SEM, TEM), X-ray Photoelectron Spectroscopy (XPS), and Hydrogen Temperature-Programmed Reduction (H2-TPR). It revealed that the synthesized CeO2 has a particle size of approximately 60 nm and its surface was covered with a uniform amorphous layer of ∼ 1 nm. XPS and H2-TPR revealed its high Ce3+ concentration and enhanced oxygen exchange capability. The polishing mechanism was investigated by XPS and High-Resolution TEM (HR-TEM). Under pressure, the CeO2 established Ce-O-Si bonds with the SiO2 surface. Ce3+ provided electrons to the antibonding orbitals of Si-O bonds, effectively breaking stable Si-O bonds and removed SiO2 film in the form of lump SiO2 through mechanical action.