Tailoring the surface properties of cerium oxide nanoabrasives through morphology control for glass CMP

Abstract

Nanosized cerium oxide (CeO₂) particles possessing different morphologies like nanorods, nanocubes and nanospheres have been successfully synthesized by a simple one step, surfactant free, precipitation technique and by hydrothermal methods. The diverse morphology motifs were further utilized for the planarization of silicate glass with an initial surface roughness of ∼40 nm and we observed a strong morphology dependence of the abrasive in glass polishing. Polishing efficiency of the nanoabrasives in terms of the mass removal and surface roughness was investigated using a table top lapping machine. Surface roughness analysis by atomic force microscopy reveals that the ceria nanostructure with a mixed morphology of rods and cubes could produce a surface finish of ∼3 Å. The surface properties of the abrasive were found to play a key role in polishing as evidenced by X-ray photoelectron spectroscopy and Raman spectral analysis. The powder contact angle/hydrophilicity of the nanopowders followed the same trend as that of the dipolar (200) plane and [Ce³⁺]. This work has shown promise in polishing efficiency with nano CeO₂ slurry to achieve nanolevel planarity on glass substrates, which is desirable for the global planarization of complex device topography.