Hierarchical Directed Self-Assembly of Diblock Copolymers for Modifi ed Pattern Symmetry

Abstract

Block copolymer lithography exploiting diblock copolymer thin films is promising for scalable manufacture of device-oriented nanostructures. Nonetheless, its intrinsic limitation in the degree of freedom for pattern symmetry within hexagonal dot or parallel line array greatly diminishes the potential application fields. Here, we report multi-level hierarchical self-assembled nano patterning of diblock copolymers for modified pattern symmetry. Sequential hierarchical integration of two layers of diblock copolymer films with judiciously chosen molecular weights and chemical composition creates nanopatterned morphology with modified pattern symmetry, including sparse linear cylinder or lamellar arrays. Internal structure of the hierarchically patterned morphology is characterized by grazing-incidence small-angle X-ray scattering throughout the film thickness. Pattern transfer of the modified nano pattern generates linear metal nanodot array with uniform size and regular spacing as a typical example of functional nanopatterned structures.