THE EFFECT OF DIFFERENT ISOELECTRIC POINT OF CERIA DISPERSION ON CHEMICAL MECHANICAL POLISHING FOR SHALLOW TRENCH ISOLATION

Abstract

The effect of different isoelectric point (pHiep) of ceria slurry on chemical mechanical polishing (CMP) for shallow trench isolation (STI) was investigated. The present study focused on the properties of ceria slurry with and without surface modification by analyzing dispersion stability and chemical mechanical polishing field evaluation. As varying pHiep of ceria slurry with anionic polymer, the modified CeO2 slurries showed different behavior. Among the three slurries having different isoelectric point, pHiep 2.5 slurry showed higher oxide-to-nitride selectivity (1:50), these effects tend to improve the silica removal rate and lower the silicon nitride removal rate. From these results we concluded that modified ceria slurry increases the oxide-to-nitride selectivity