A silicon-containing film is formed from a heat curable composition comprising (A-1) a silicon-containing compound obtained through hydrolytic condensation of a hydrolyzable silicon compound in the presence of an acid catalyst, (A-2) a silicon-containing compound obtained through hydrolytic condensation of a hydrolyzable silicon compound in the presence of a base catalyst, (B) a hydroxide or organic acid salt of Li, Na, K, Rb or Ce, or a sulfonium, iodonium or ammonium compound, (C) an organic acid, (D) a cyclic ether-substituted alcohol, and (E) an organic solvent. The silicon-containing film ensures effective pattern formation, effective transfer of a photoresist pattern, and accurate processing of a substrate.