A method forms a hydrocarbon-containing polymer film on a semiconductor substrate by a capacitively-coupled plasma CVD apparatus. The method includes the steps of: vaporizing a hydrocarbon-containing liquid monomer (C.sub..alpha.H.sub..beta.X.sub..gamma., wherein .alpha. and .beta. are natural numbers of 5 or more; .gamma. is an integer including zero; X is O, N or F) having a boiling point of about 20.degree. C. to about 350.degree. C.; introducing the vaporized gas into a CVD reaction chamber inside which a substrate is placed; and forming a hydrocarbon-containing polymer film on the substrate by plasma polymerization of the gas.