Triethoxyfluorosilane-based (TEFS) xerogel films have been reacted with silylation agents and characterized. TEFS films have been employed because they form robust silica networks and exhibit low dielectric constants. However, these films readily absorb moisture. Employing silylation reactions enhances film hydrophobicity and permits possible introduction of this film as an interlayer dielectric material. Fourier transform infrared spectroscopy was used to verify the presence of methyl groups and extent of silylation in the silica films. Thicknesses anti refractive indices of the subject films were determined by ellipsometry studies, and porosity was determined by the refractive index, Hydrophobicity of the silica films was measured by the sessile-drop goniometric contact angle technique. (C) 2004 Elsevier B.V. All rights reserved.