Low-dielectric, nanoporous organosilicate films prepared via inorganic/organic polymer hybrid templates

Dielectric insulator materials containing nanometer-scale closed-cell pores with low dielectric constants (k < 2.2), good mechanical properties, and h igh dielectric breakdown strengths are required for future semiconductor de vices. In this paper we present a novel method for preparing nanoporous pol yorganosilicate films, which promise to satisfy the key requirements, via i norganic/organic polymer hybrid templating. The nanometer-scale inorganic/o rganic polymer hybrids are generated in situ upon heating mixtures of methy lsilsesquioxane (MSSQ) prepolymer with star-shaped hydroxy-terminated poly( epsilon-caprolactone) (PCL) to similar to 250 degrees C, causing chain exte nsion and cross-linking of MSSQ. Subsequent heating to 430 degrees C result s in the thermal decomposition and volatilization of PCL components from th e vitrified poly(methylsilsesquioxane) (PMSSQ) matrix;, leaving behind poro us PMSSQ films with pores with the size and shape of the original hybrid mo rphology. A dielectric constant as low as 2.1 has been achieved for closed- cell nanoporous PMSSQ films with hydrophobic surfaces and excellent breakdo wn strengths close to that of SiO2. Moreover, conductance measurements on i norganic/organic polymer hybrids offer insight into the development of inte rconnected PCL domains as the PCL content is increased above similar to 25% .