PROBLEM TO BE SOLVED: To provide a material which can be purified up to an electron grade and is usable to form a dielectric layer reduced in thickness while holding desired electric characteristics.SOLUTION: A dielectric layer is formed by using a liquid composition comprising molecular glass, a crosslinking agent and a catalyst. As the molecular glass being an amorphous molecular material, an ester molecule containing -OH or -NH2, a spiro compound, a bisphenol A compound, a tetrahedral aryl silane compound, an adamantane compound, a cyclic compound, a condensation cyclic compound, a triaryl amine compound, a benzene compound, a hexaphenyl benzene compound, a triphenyl benzene compound, a naphthalene compound, an anthracene compound, a phenanthrene compound and a pyrene compound are used. Further, the molecular glass may contain a compound which is irradiated with light to produce an acid, i.e. inorganic particles such as nanoparticles, metal nanoparticles, metal oxide nanoparticles, and other inorganic nanoparticles.