Effect of dispersant addition during ceria abrasive milling process on light point defect (LPD) formation after shallow trench isolation chemical mechanical polishing (STI-CMP)

We examined both the dispersant mixing time during ceria slurry synthesis and a method for reducing the quantity of agglomerated large particles, which influence the number of light point defects (LPDs) formed after chemical mechanical polishing (CMP). We quantified the dispersion stability of slurries with the abrasive particle size by examining with and without ultra-sonic treatment. Without the addition of dispersant before mechanical milling, the dispersion stability was worse than the case with dispersant addition before milling. A lower pH of cerium carbonate improved both the dispersion stability and reduced the number of LPDs formed on an oxide film after CMP.