Synthesis of Photoacid Generator-Containing Patternable Diblock Copolymers by Reversible Addition-Fragmentation Transfer Polymerization

摘要

Patternable block copolymers have received considerable attention, as they provide two levels of control over nanostructures by combining the self-assembling and lithographic characteristics. Some of these systems are based on the widely used polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) where the PS block crosslinks and the PMMA block degrades upon exposure to UV or electron beam. Some of the other block copolymer systems include poly(4-hydroxystyrene)-b-poly(α-methylstyrene) by Ober et al.and poly(t-butyl (meth)acrylate)-based block copolymers by Gabor and La et al., where suitable additives such as a photo-acid generator (PAG) and/or a multifunctional cross-linker can be selectively incorporated into the chemically sensitive block to induce the deprotection or cross-linking reaction by light. The spatial control over the nanostructures in these self-assembled block copolymer resist films is afforded by a top-down lithographic process.