LOW REFRACTIVE INDEX POLYMERS AS UNDERLAYERS FOR SILICON-CONTAINING PHOTORESISTS

摘要

A new underlayer composition that exhibits high etch resistance and improved optical properties is disclosed. The underlayer composition comprises a vinyl or acrylate polymer, such as a methacrylate polymer, the polymer comprising at least one substituted or unsubstituted naphthalene or naphthol moiety, including mixtures thereof. Examples of the polymer of this invention include: formula (I), (II), (III), (IV), where each R<SUB>1 </SUB>is independently selected from an organic moiety or a halogen; each A is independently a single bond or an organic moietry; R<SUB>2</SUB> is hydrogen or a methyl group; and each X, Y and Z is an integer of 0 to 7, and Y+Z is / or less. The organic moiety mentioned above may be a substituted or unsubtituted hydrocarbon selected from the group consisting of a linear or branched alkyl, halogenated linear or branched alkyl, aryl, halogenated aryl, cyclic alkyl, and halogenated cyclic alkyl, and any combination thereof. The compositions are suitable for use as planarizing underlayer in a multilayer lithographic process, including a trilayer lothographic process.