Synthesis And Chemical Mechanical Polishing Performance Of Sub-Micron Cerium Oxide

Chemical mechanical polishing(CMP) is one of the most effective planarization technologies in the high precision optics devices and ultra large scale integration circuits manufacturing industry. As the development of advanced technology, there is higher requirement for the precision of the workpiece surface and the size and morphology of the polishing material. In this paper, sub-micron ceria particles with various size and morphology have been synthesized via different method. Their material removal rate(MRR) for K9 glass polishing and the surface quality(Ra) were evaluated. The relationship between the polishing performance and the physicochemical parameters of as-prepared ceria(such as size distribution, zeta potential, dispersion stability) has been discussed.Spherical ceria with various particle size has been synthesized via hydrothermal method by using Ce(NO3)3.6H2 O and PVP as raw material. The phase structure, morphology, particle size distribution and zeta potential of the as-prepared products have been analyzed by X-ray diffraction(XRD), scanning eletron microscope(SEM), transmission eletron microscope(TEM), laser particle size analyzer and zeta potential analyzer. The effect of calcination temperature, calcinations atmosphere and dispersant on the particle size and the polishing performance towards K9 glass were investigated. The results indicated that sub-micron spherical ceria with various particle size could be synthesized by adjusting the p H, temperature and reaction time during hydrothermal synthesis, Cubic-fluorite-structured spherical ceria of 0.3μm aggregated from primary particle of about 8nm has been sythesized at hydrothermal condition of 180℃, 24 h and p H=5. As the calcination temperature increasing, the crystallinity of the product increased. The product calcinated at 1050℃ exhibited the best polishing performance.Sub-micron ceria was also prepared through salt-assisted mechanical chemical method by using cerium hydroxycarbonate as raw material. Uniform particle of 100 nm with narrow particle size distribution and non-aggregation has been obtained by milling the calcination products in alcohol. Their polishing behavior to K9 glass indicated the material removal rate(MRR) increased firstly and then decreased with increasing calcination temperature and the optimal calcination temperature was found to be 1000℃.As the strict demand of magnetorheological polishing fluid, we investigated the effect of different dispersants and inorganic salt on the stability of Ce O2 suspension. The polishing performance of the as-prepared magnetorheological polishing fluid towords K9 glass has been evaluated. The results showed that the anionic and inorganic-salt-typed dispersant can improved the stability of Ce O2 suspension. The quality of K9 glass surface enhanced with increasing magnetic rheological polishing time.