The chemical mechanical planarization (CMP) has been one of the major manufacturing process to provide global and local surface planarizations in integrated circuits (IC) fabrications. Defects such as micro-scratches generated during CMP can lead to severe circuit failure, which affects yield. In the present work, ethoxylated decylalchohol (EDA) was used as dispersant agent to prevent the particles agglomeration to reduce scratches. Firstly, the effect of EDA on particle size distribution (PSD) of the slurry was investigated by dynamic light scattering (DLS) method. Then the effect of EDA on large particle counts (LPC) was studied through a dual sensor single particle optical sensing (SPOS) analysis method. The wetting ability of slurries as a function of EDA concentration was also studied. Finally, the defect scan tool and scanning electron microscope (SEM) reviewer were used to identify the scratch defects. The results show that the addition of EDA into the slurry can enhance the dispersity of colloidal silica abrasives and significantly reduce the number of large particles in the slurry, the SEM review results show that the scratch counts remarkably decreases with EDA concentration increasing. It can be demonstrated that the EDA can effectively reduce the scratch counts.