Negative-tone block copolymer lithography by in situ surface chemical modification

Abstract

Negative-tone block copolymer (BCP) lithography based on in situ surface chemical modification is introduced as a highly efficient, versatile self-assembled nanopatterning. BCP blends films consisting of end-functionalized low molecular weight poly(styrene-ran-methyl methacrylate) and polystyrene-block-Poly(methyl methacylate) can produce surface vertical BCP nanodomains on various substrates without prior surface chemical treatment. Simple oxygen plasma treatment is employed to activate surface functional group formation at various substrates, where the end-functionalized polymers can be covalently bonded during the thermal annealing of BCP thin films. The covalently bonded brush layer mediates neutral interfacial condition for vertical BCP nanodomain alignment. This straightforward approach for high aspect ratio, vertical self-assembled nanodomain formation facilitates single step, site-specific BCP nanopatterning widely useful for various substrates. Moreover, this approach is compatible with directed self-assembly approaches to produce device oriented laterally ordered nanopatterns.

Keywords: block copolymers; imprint; lithography; self-assembly.