Zeta potential-tunable silica abrasives and fluorinated surfactants in chemical mechanical polishing slurries

Abstract

Chemical mechanical planarization (CMP) is a vital process for smoothing and polishing the surfaces of various material layers in the semiconductor device fabrication. CMP slurries, chiefly composed of abrasives and various chemicals, play a key role in the planarization performance owing to the synergistic effects. Wafer quality must be investigated simultaneously with the planarization performance, because mechanical and chemical defects on wafer surfaces inevitably occur during the CMP process and should be avoided for yield enhancement. In this study, the planarization performance of dielectric layers (SiO2) was considerably improved while maintaining low wafer defect density, avoiding the trade-off between planarization performance and wafer defect density. The balanced performance was achieved via the combination of the tailoring of the zeta potential of colloidal silica nanoparticles (CSNs) and the decrease of defect concentration using fluorinated surfactant (FS)-induced intermolecular repulsion between the wafer surfaces and the additives. High-quality wafer surfaces with rare defect, low surface roughness, and no contamination (fungus and bacteria) were thus achieved. The combination of aminosilane treatment and FS effects investigated in this study can enhance the planarization performance while maintaining low defect/contaminant density not only for CMP slurries but also for various other polishing/abrasion applications.