Preparation of a novel catalyst (SoFeIII) and its catalytic performance towards the removal rate of sapphire substrate during CMP process

Chemical mechanical polishing of sapphire with a novel catalyst (SoFeIII)-based colloidal silicon dioxide has been studied with high resolution transmission electron microscopy and X-ray diffraction. It has been found that a polytype of aluminun trihydroxide is formed on the polished crystal surface when SoFeIII-80 °C catalyst is used, while aluminum silicate hydrate layer is found on the polished sapphire surface when burnished with catalyst-free slurry. And the novel catalyst plays effective performance towards improving the removal rate of sapphire, and its removal rate is 7.21 μm/h, 1.66 times than the material removal rate obtained with catalyst-free slurry. Additionally, the optimum CMP removal by SoFeIII-80 °C yielded an ultra-smooth wafer surface with an average roughness of 0.0543 nm.