Effect of Surfactant and Solvent on the Pore Structure of Organosilica Glass Film

Abstract

In this work, the effects of solvent type and surfactant (porogen) on the properties of porous methyl-modified spin-on films were investigated. A qualitative assessment of the defectivity of the formed films was carried out. The refractive index, dielectric permittivity, and porosimetric properties of the films were analyzed using the method of spectral ellipsometry, frequency dependence of capacitance analysis, and porosimetry. It was found that the film properties depend more strongly on the surfactant type than on the solvent type. The highest porosity value is obtained with the use of nonionic surfactant Brij^® 76, which has a higher molecular weight. At the same time, at lower molecular weight, the ionic surfactant CTAB provides comparable porosity. Despite the high porosity, samples from film-forming solutions containing CTAB do not exhibit a lower dielectric constant, which is presumably due to their hydrophilicity or porogen residue. The lowest value of the dielectric constant k ≈ 2.1 is typical for films made from film-forming solutions containing Brij^® 76. The application of other porogens allows us to obtain a k value ~2.3–2.4.