US Patent 7632624 Photoresist undercoat-forming material and patterning process

A material comprising a specific bisphenol compound of formula (1) is useful in forming a photoresist undercoat wherein R1 and R2 are H, alkyl, aryl or alkenyl, R3 and R4 are H, alkyl, alkenyl, aryl, acetal, acyl or glycidyl, R5 and R6 are alkyl having a ring structure, or R5 and R6 bond together to form a ring. The undercoat-forming material has an extinction 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.