Synergistic effect of PVA and FMEE on improving post-CMP surface uniformity for polysilicon and its mechanism

Polysilicon (Poly-Si) is crucial for gate electrodes and interconnects in integrated circuits. Surface uniformity after Chemical Mechanical Polishing (CMP) critically impacts device performance, especially with stringent photolithography requirements at scaled dimensions. Optimizing slurry formulation enhances uniformity, but the synergy between polymer (e.g., Polyvinyl Alcohol, PVA) and nonionic surfactant (e.g., Fatty Methyl Ester Ethoxylates, FMEE) and its effect on Poly-Si CMP uniformity remain unclear. This study introduced PVA and FMEE into an alkaline slurry. Post-CMP uniformity (Site Front Quotient Range, SFQR; Within-wafer Nonuniformity, WIWNU) and roughness (Local Root Mean Square Roughness, Sq) were evaluated using wafer geometry testing and Atomic Force Microscopy (AFM). Adsorption behavior and polishing effects were investigated via X-ray Photoelectron Spectroscopy (XPS), Attenuated Total Reflection Fourier Transform Infrared spectroscopy (ATR-FTIR), Molecular Dynamics (MD) simulation, and friction testing. Compared to control (Blank), PVA/FMEE slurry significantly improved uniformity: SFQR reduced by 0.05 μm, edge WIWNU decreased to 2.97 %, and Sq optimized to 0.55 nm. PVA and FMEE synergistically form a dense composite adsorption layer via hydrogen bonding, selectively modulating local removal rates through lubrication and interfacial protection. Synergizing with enhanced abrasive dispersion stability, this mechanism improves Poly-Si CMP surface uniformity. The findings provide insights for developing high-precision Poly-Si CMP slurries.