US Patent 7303855 Photoresist undercoat-forming material and patterning process

An undercoat-forming material comprising a novolak resin having a fluorene or tetrahydrospirobiindene structure, 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 CF4/CHF3 and Cl2. BCl3 gases for substrate processing.