Preparation of Substituted N-Methacryloxy Phthalimides for E-Beam Lithography

Abstract

Poly (methyl methacrylate) (PMMA) is a very good option for electron-beam resists, but suffers from poor radiation sensitivity and poor plasma etch resistance. These problems can be offset, at least in part, by functionalizing the PMMA with photo-labile, plasma etch-resistance groups. Toward this end, a series of N-methacryloxy phthalimides with different substitutuents (methyl, nitro, tetrahydrogen and dichloro) were synthesized as possible useful radiation-sensitive resists. The work discussed here focuses on the cycloimido group, which can be easily attached to methacrylic acid to form a radiation-sensitive resist material for use in electron beam lithography. The labile N–O bond of the cycloimido group, upon exposure to radiation, cleaves and forms a radical on the main chain of the polymer, which leads to polymer degradation. Cursory evaluations showed that these new materials are deserving of further study.