Effects of slurry formulations on chemical-mechanical polishing of low dielectric constant polysiloxanes: hydrido-organo siloxane and methyl silsesquioxane

In this study, the film properties and chemical-mechanical polishing (CMP) characteristics of the low dielectric constant polymers hydrido-organo siloxane and methyl silsesquioxane are presented. The molecular structure and film properties of both polymers were characterized by their Fourier transform infrared spectra, refractive indices, dielectric constants, and atomic force microscopy diagrams. The CMP characteristics were studied by using different kinds of slurries and surfactants. The investigated slurries included SiO2 based slurry (SS-25), ZrO2 based slurry (Al), and Al2O3 based slurry (8104/H2O). Three kinds of surfactants were used to increase the contact area between the abrasive and polymer surface and thus polishing results were affected, which included nonionic Triton X-100, anionic dodecylsulfate sodium salt, and cationic tetramethylammonium hydroxide. The experimental results suggest that the organic content, the hardness and charge status of the abrasive, the polarity and charge status of the surfactant significantly affect the polishing results. The present study demonstrates that the CMP characteristics of low dielectric constant polysiloxanes can be controlled both chemically and mechanically. (C) 2000 American Vacuum Society. [S0734-211X(00)03201-7].