Selective Area Control of Self-Assembled Pattern Architecture Using a Lithographically Patternable Block Copolymer

Abstract

We leverage distinctive chemical properties of the diblock copolymer poly(α-methylstyrene)-block-poly(4-hydroxystyrene) to create for the first time high-resolution selective-area regions of two different block copolymer phase morphologies. Exposure of thin films of poly(α-methylstyrene)-block-poly(4-hydroxystyrene) to nonselective or block-selective solvent vapors results in polymer phase separation and self-assembly of patterns of cylindrical-phase or kinetically trapped spherical-phases, respectively. Poly(4-hydroxystyrene) acts as a high-resolution negative-tone photoresist in the presence of small amounts of a photoacid generator and cross-linker, undergoing radiation-induced cross-linking upon exposure to ultraviolet light or an electron beam. We use lithographic exposure to lock one self-assembled phase morphology in specific sample areas as small as 100 nm in width prior to film exposure to a subsequent solvent vapor to form a second self-assembled morphology in unexposed wafer areas.