Patent ID: 6893726

Claim:
A substrate coated with a silica-containing film with a low-dielectric constant, which is a low-density film formed by: (a) applying onto a substrate the coating liquid for forming a silica-containing film with a low-dielectric constant comprising a polymer composition consisting essentially of (i) a polysiloxane and (ii) a readily decomposable resin, said polysiloxane being a reaction product between fine particles of silica and a hydrolyzate of at least one alkoxysilane represented by the following formula (I): X n Si(OR) 4-n (I), wherein X represents a hydrogen atom, a fluorine atom, an unfluorinated or fluorinated alkyl group of 1 to 8 carbon atoms, an aryl group or a vinyl group; R represents a hydrogen atom, an alkyl group of 1 to 8 carbon atoms, an aryl group or a vinyl group; and n is an integer of 0 to 3; (b) heating the thus-coated film; and then (c) decomposing or vaporizing the readily decomposable resin contained in the film by a heat treatment at a temperature of not higher than 500° C. or by irradiation with ultraviolet radiation, infrared radiation, electron beam, X-ray or oxygen plasma, wherein the average diameter of pores or voids present in the low density silica film is not more than 10 nm.