Semiconductor interlayer-insulating film forming composition, preparation method thereof, film forming method, and semiconductor device

A method for preparing a composition for forming a porous film, comprising the steps of:

• obtaining a polysiloxane compound by performing hydrolysis and condensation reactions, in the presence of an acid catalyst, of a hydrolyzable silane compound containing at least one tetrafunctional alkoxysilane compound represented by the following formula (1):
• Si(OR1)4 (1)
• wherein, R1s may be the same or different and each independently represents a linear or branched C1-4 alkyl group and/or at least one alkoxysilane compound represented by the following formula (2):
• R2nSi(OR3)4-n (2)
• wherein, R2(s) may be the same or different when there are plural R2s and each independently represents a linear or branched C1-8 alkyl group, R3(s) may be the same or different when there are plural R3s and each independently represents a linear or branched C1-4 alkyl group, and n is an integer from 1 to 3 in the reaction mixture containing water in an amount sufficient for hydrating a silanol group generated during the reaction to control the condensation reaction and suppress gelation;
• extracting the polysiloxane compound in an organic solvent;
• and
• mixing the polysiloxane compound thus extracted and silicon-oxide-based fine particles.