Patent ID: 6946161

Claim:
In a method for forming a porous silica film using a hydrolyzable alkoxysilane compound, water, an alcohol and a surfactant and acidic or alkaline catalyst, the method for forming a porous silica film, comprising: acid hydrolysis or alkaline hydrolysis of the hydrolysable alkoxysilane compound, utilizing one or more kinds of nonionic surfactant(s) having a 0.1 weight % concentration according to the Du Nouy method expression and a surface tension of 45 mN/m or larger at 25° C. as the surfactant, coating a mixed solution obtained by mixing the nonionic surfactant, the alkoxysilane compound, water and the alcohol on a substrate, and decomposing or burning out the surfactant in the mixed solution, and wherein said hydrolyzable alkoxysilane compound is from 0.05 to 0.5 mole of a dimethyldialkoxysilane compound represented by Si(CH 3 ) 2 (OR) 2 where a substituent R denotes a methyl group or an ethyl group.