| abstract |
Novel copolymers having a weight average molecular weight of 500 to 5,000,000 and comprising 1 to 99% by weight of a recurring unit represented by the formula (I), 1 to 99% by weight of a recurring unit represented by the formula (II) and 0 to 98% by weight of a recurring unit represented by the formula (III): <IMAGE> wherein R1 is a hydrogen atom or a methyl group; X is a hydrogen atom, a methyl group or a phenyl group; Y is a hydrogen atom, a halogen atom, a methyl group, a phenyl group or a cyano group; and Z is a phenyl group, a phenyl group substituted by at least one alkyl group having 1 to 8 carbon atoms, a polycyclic aromatic hydrocarbon group having 10 to 20 carbon atoms, a cyano group, -COOR2 (in which R2 is an alkyl group having 1 to 20 carbon atoms or an aromatic hydrocarbon group having 6 to 14 carbon atoms), -COR3 (in which R3 is an alkyl group having 1 to 12 carbon atoms or an aromatic hydrocarbon group having 6 to 14 carbon atoms), a nitro group, a pyridyl group, <IMAGE> (in which R3 has the same meaning as defined above), or a halogen atom. The above-mentioned copolymers are useful as resist materials which are sensitive to high-energy radiations. |