The Stability of Nano Fumed Silica Particles and Its Influence on Chemical Mechanical Planarization for Interlayer Dielectrics

The effects of water-soluble polymer adsorption on the stability of silica particles and its influence on chemical mechanical planarization (CMP) for interlayer dielectrics (ILD) were investigated. This study was focused on the properties of silica slurry with and without surface modification by analyzing dispersion stability and chemical mechanical planarization field evaluation. As a silica slurry for interlayer dielectric chemical mechanical planarization was prepared in the alkaline region to accelerate the chemical corrosion process of plasma enhanced tetraethlyorthosilicate (PETEOS) film, Si ions dissolved the point where it would adversely affect the colloidal stability of the silica particles. As the silica surface was modified with poly vinyl pyrrolidone (PVP) polymer, the decrease of surface potential above pH 9.0 disappears and thus resulted in an increase of the stability of silica particles dispersed in the alkaline region. Modification of the slurry with PVP reduced micro-scratches and remaining silica particles on the wafers with favorable removal rate and better uniformity.