Patent ID: 7678529

Claim:
A silicon-containing film forming composition used for multilayer resist process comprising the steps of forming in sequence an undercoat film, an intermediate silicon-containing film, and a photoresist film on a patternable substrate, and effecting etching in multiple stages, said silicon-containing film forming composition for use in forming the intermediate silicon-containing film serving as an etching mask, comprising a silicon-containing polymer, an acid generator, and a crosslinker, said silicon-containing polymer is obtained through hydrolytic condensation of a mixture of hydrolysable silanes comprising: at least one silicon-silicon bond-containing silane compound having the general formula (1); R (6-m) Si 2 X m (1) wherein each R is independently a substituted or unsubstituted monovalent hydrocarbon group of 1 to 12 carbon atoms, each X is independently an alkoxy group, alkanoyloxy group or halogen atom, and m is a number from 3 to 6, and a hydrolysable silane compound having the general formula (2): A a SiB (4-a) (2) wherein each A is independently hydrogen or a substituted or unsubstituted monovalent hydrocarbon group of 1 to 12 carbon atoms, each B is independently an alkoxy group, alkanoyloxy group or halogen atom, and a is 0 or 1, the compound of formula (1) wherein m is equal to 4 or 3 accounting for at least 40% by weight of the entire silane compounds, and the silane compound of formula (1) wherein m is 4 and the silane compound of formula (1) wherein m is 3 being in a molar ratio between 3:7 and 7:3.