Radiation-Induced Reactions of Chloromethylstyrene-Based Resist Materials Analyzed from Radiolysis of Low Molecular Model Compounds

The radiation-induced reactions of chloromethylstyrene-based resist materials are studied by low temperature ESR and gas chromatography-mass spectrometry (GC-MS) analyses using low molecular model compounds. Low temperature ESR analyses indicate that main radiation-induced active species in the initial stage of the reaction are benzyl radicals formed through chlorine removal from chloromethylstyrene units and simultaneously produced active chlorines. The amount of the a radicals formed through α-hydrogen cleavage is less than one-tenth that of the benzyl radicals. GC-MS analyses indicate that large amounts of a radicals are produced through the subsequently occurring hydrogen abstractions by radiation-induced active chlorines. The susceptibilities of individual constituents to hydrogen abstractions are determind as 6.2 for a methylstyrene unit, 2.6 for a styrene unit, and 1 for a chloromethylstyrene unit.