Photoresist materials for 157-nm photolithography

Mass spectroscopy of certain candidate photoresistive materials for 157-nm photolithography indicates that total bond breaking and dissociation of the parent molecule is taking place even at low laser energy. Materials respond differently to photon excitation at 193 and 157 nm due to the high density of pre-dissociative excited electronic states at 157 nm (7.8 eV). Several materials have been studied for absorption and dissociation below 200 nm. Results for the absorbance in the VUV of (meth)acrylate polymers including a copolymer of four different monomers (acrylic acid, hydroxyethyl methacrylate, cycloexyl methacrylate, norbonyl methacrylate) and of polyvinyl acetate (partially hydrolyzed and non-hydrolyzed) are reported.