Preparation of Nano-SnO2 Abrasives and Their Application in Chemical Mechanical Polish of Ruthenium

SnO2 abrasives were prepared by solid-state reaction and the effect of the preparation conditions on the average particle size of SnO2 suspension was investigated. The result manifests that the suspension prepared from SnO2 powder obtained by calcining at 500 °C for 4 h has good dispersion and good stability. CMP (chemical mechanical polish) experiments were performed on high purity Ru by home-made slurry. The MRR (material removed rate) and the roughness of the surface decrease compared with SiO2 slurry. The results reveal that MRR can reach 6.8 nm/min under the following conditions: the main constituents in slurry are 1 wt% SnO2, 1 wt% (NH4)2S2O8, 1 wt% tartaric acid and 3 mmol/L imidazole, the pH value is 8.0, the down force is 17.24 kPa; the roughness Ra is 4.8 nm under these conditions.