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Abstract

The invention relates to novel maleimide copolymers which, in addition to structural units derived from certain maleimide derivatives defined more precisely in the present patent application, comprises recurring structural units selected from the structural units of the formulae (Ia) and (Ib) ##STR1## where A is a direct single bond or a divalent group of the formula --O--; R.sub.0 and R.sub.1, independently of one another, are each a hydrogen atom, a C.sub.1 -C.sub.6 alkyl group or an aryl group having 6 to 14 ring carbon atoms; R.sub.2 is a radical of the formula ##STR2## in which R is a tert-alkyl radical having 4 to 19 carbon atoms, [T] is a C.sub.1 -C.sub.6 alkylene group or an arylene group having 6 to 14 ring carbon atoms, and p is the number 2, 3 or 4; or A together with R.sub.2 is a group of the formula ##STR3## and where, furthermore, R.sub.3 and R.sub.4, independently of one another, are each a hydrogen atom, a halogen atom, a C.sub.1 -C.sub.6 alkyl group or a C.sub.1 -C.sub.6 alkoxy group, and the other radicals have specific meanings defined more precisely in the present application. The polymers can form the basis of chemically amplified positive photoresists which exhibit, inter alia, excellent contrast behavior, a low shrinkage tendency in the irradiated areas and insignificant delay time effects.

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First Claim