Substrate-Independent Lamellar Orientation in High-Molecular-Weight Polystyrene-b-poly(methyl methacrylate) Films: Neutral Solvent Vapor and Thermal Annealing Effect

Abstract

Lamellar microdomain orientation in polystyrene-b-poly(methyl methacrylate) (PS-b-PMMA) films was controlled by a solvent vapor annealing process, where the high-molecular-weight block copolymer (BCP) was used to self-assemble in a large period of 105 nm. A neutral solvent annealing with tetrahydrofuran vapor screened the difference in the surface energy between the two blocks and the interfacial interactions of the substrate with each block, leading to the substrate-independent perpendicular orientation of lamellar microdomains. Together with thermal annealing of the solvent-annealed BCP film, we demonstrate that highly ordered line arrays of perpendicularly oriented lamellae were well guided in topographic line and disk photoresist patterns composed of the PS-attractive cross-linked copolymer, where the interlamellar d-spacing compliant to the patterns was dependent on the confinement types.