Effects of the Solid Concentration of Ceria Slurry on the Removal Rate and Selectivity of Si Wafer during Chemical Mechanical Polishing

Shallow trench isolation via chemical mechanical polishing (CMP-STI) tests of Si wafers using CeO 2 slurry were studied. The impact of CeO 2 slurry's solid concentration on the SiO 2 removal rate and the selectivity ratio The effects of the solid concentration of CeO 2 slurry on the removal rate of SiO 2 and selectivity (SiO 2 /Si 3 N 4 ) were investigated. The CeO 2 abrasive was well matched to the XRD standard pattern, confirming that it had a cubic phase and the absence of any impurities. The SEM image showed that CeO 2 primary particles had a spherical-like shape with a size within 30-60 nm. Additionally, the prepared CeO 2 slurry showed a relatively high dispersion level. The wettability degree of the CeO 2 slurry on top of the Si wafer surface was also sufficient. Furthermore, results from polishing tests indicated that both the SiO 2 removal rate and the selectivity increased linearly with a rise in CeO 2 solid concentration.