An undercoat-forming material comprising a copolymer derived from an indene and a compound having a hydroxyl or epoxy group and a double bond, an organic solvent, an acid generator, and a crosslinker, optionally combined with an intermediate layer having an antireflective effect, has an absorptivity coefficient sufficient to provide an antireflective effect at a thickness of at least 200 nm and a high etching resistance as demonstrated by slow etching rates with CF.sub.4/CHF.sub.3 and Cl.sub.2/BCl.sub.3 gases for substrate processing.