Interaction Between Triblock Copolymer Surfactant and Low- κ Dielectric Surfaces Relevant to CMP

Abstract

We examine the effects of the nonionic triblock copolymer surfactant Pluronic P103 on three surfaces of different wettability relevant to chemical mechanical planarization (CMP). Two of the surfaces are low-k organosilicate glass (OSG) films, Coral and Black Diamond; the third is a silica surface. Atomic force microscopy (AFM) force curves were used to probe the forces over each surface in solutions of P103. Each surface was also examined in potassium sulfate solutions to investigate the effect of ionic strengths. The AFM force curves show that both P103 and potassium sulfate eliminate adhesive forces at sufficiently high concentrations. DLVO theory was used to fit the AFM approach curves in order to calculate estimated surface potentials. Interestingly, the force curves suggest that molecular orientation of the P103 is different on surfaces of different wettability. The P103 was found to adopt a flat conformation on the hydrophilic silica surface while more extended structures formed on the more hydrophobic Coral and Black Diamond surfaces. These results provide a molecular-level understanding to aid the development of CMP formulations that will provide greater control on dielectric removal rate and reduce the overall non-uniformity in film thickness across the wafer.