Chemical Preparation And Polishing Property Of Cerium Oxide Powders

With the development of precision optical technology and electronic products, materialssuch as optical glass, optical mask and silicon substrate are required to have super-smoothsurface. At present, we often use the chemical mechanical polishing technology (CMP) tocomplete the surface polishing. Using as polishing materials, cerium oxide has many featuressuch as high polishing rate, long service life, easy to clean. And cerium oxide is the mostimportant material in chemical mechanical polishing technique. So the research of preparationmethods and polishing properties of cerium oxide has great significance.The objective of this paper was to prepare a kind of cerium oxide powder which wassuitable for the polishing of optical glass. Firstly, CeO2powders were prepared byprecipitation and hydrothermal method, and the influence of these two methods on the CeO2powders was investigated. Then, based on the cerium oxide powder, the preparationconditions of CeO2slurry were studied by adding pH adjusting agent, dispersing agent, andother additives. Finally, the mechanism of chemical mechanical polishing was explored.With CeCl3as cerium source and Na2CO3as precipitant, CeO2precursor was prepared byprecipitation method, and CeO2powders were obtained after calcinations of the precursor. Theeffects of precipitation conditions, roasting conditions on the property of CeO2powders werestudied. Polished performance of CeO2powders was tested. The optimal reaction conditionswere determined: reaction temperature was45℃, the concentration of the precipitating agentwas0.5mol/L, the aging time was4h, calcination temperature was950℃, and calcinationtime was2h.With the assistant of surfactant, and taking cerium nitrate and urea as ingredient,spherical CeO2powders were prepared through hydrothermal method. The effects ofhydrothermal conditions, roasting conditions on the property of CeO2powders were studied.Polished performance of CeO2powders was tested. The optimal reaction conditions weredetermined: the reaction temperature was180℃, the reaction time was24h, the surfactantfor spherical CeO2powders was citric acid, calcination temperature for the precursor was800℃, spherical CeO2powders prepared by the hydrothermal method were suitable for theprecise polishing of soft glass. Next, the cerium oxide powders were prepared as alkaline slurry, and the dispersion andpolishing properties influenced by pH adjusting agent, dispersant agent, and additivies werestudied. The optimal reaction conditions were determined by polishing test: diethanolaminewas chosen as pH adjusting agent, and the optimum pH value was8-9; PAA and PEG400were chosen as dispersant agent, and the mass ratio of PAA and PEG400was2:1, and theoptimum concentration was0.5wt%; additivies chose NH4Cl, and the optimum concentrationwas1.0wt%.Finally, the chemical mechanical polishing mechanism was simulated through theadsorption experiments on CeO2suspension and SiO2-3. We concluded that the main chemicalreaction during chemical mechanical polishing process was the chemical adsorption betweenCeO-2and SiO23, and there was Ce-O-Si chemical bond formed between CeO2particles and thesurface of glass. SiO(OH)-3was the mainly intermediates.