Photoresist compositions containing copolymers having acid-labile groups and recurring units derived from either N-(hydroxymethyl)maleimide or N-(acetoxymethyl)maleimide or both

A radiation-sensitive composition useful as a positive photoresist comprising

• a) at least one compound which forms an acid on exposure to actinic radiation;
• and
• b) at least one polymer which comprises recurring structural units selected from the group consisting of at least one structural unit of formulae (Ia) and (Ib):
• ##STR39## and, in addition to these structural units, recurring structural units of the formula (II) ##STR40## 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 ##STR41## in which [T] is a C.sub.1 -C.sub.6 alkylene group or an arylene group having 6 to 14 ring carbon atoms,
• R is a tert-alkyl radical having 4 to 19 carbon atoms or a group of the formula ##STR42## and p is the number 2, 3 or 4;
• or
• A together with R.sub.2 is a group of the formula ##STR43## 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;
• R.sub.5 and
• R.sub.6, 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, and
• R.sub.7 is selected from the group consisting of ##STR44## R.sub.11 and R.sub.12, independently of one another, are each a hydrogen atom, a C.sub.1 -C.sub.6 alkyl group, a cycloalkyl group having 3 to 6 ring carbon atoms or an aryl group having 6 to 10 ring carbon atoms, where aryl groups are either unsubstituted or have one or more substituents selected from halogen atoms, C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.4 alkoxy groups and --CN and --NO.sub.2 ;
• R.sub.13 is a C.sub.1 -C.sub.6 alkyl group, a cycloalkyl group having 3 to 6 ring carbon atoms or an aryl group having 6 to 10 ring carbon atoms, where aryl groups are either unsubstituted or have one or more substituents selected from halogen atoms, C.sub.1 -C.sub.4 alkyl and C.sub.1 -C.sub.4 alkoxy groups and --CN and --NO.sub.2 ;
• and
• R.sub.17 is a hydrogen atom or a C.sub.1 -C.sub.4 alkyl group;
• R.sub.18 is a C.sub.1 -C.sub.6 alkyl group or a C.sub.3 -C.sub.6 cycloalkyl group, and
• R.sub.19 is an aryl group having 6 to 14 ring carbon atoms.