Large-area, highly oriented lamellar block copolymer nanopatterning directed by graphoepitaxially assembled cylinder nanopatterns

We present a large-area, highly aligned lamellar block copolymer self-assembly directed by graphoepitaxially aligned cylinder block copolymer self-assembly. Asymmetric block copolymer thin films were graphoepitaxially assembled within 1 μm wide parallel photoresist trenches to generate surface-parallel nanocylinder arrays. After the graphoepitaxial morphology was frozen by a radiative treatment, a thin film of symmetric block copolymer was deposited over the nanocylinder array, where the lamellar period was consistent with the period of the underlying cylinder array. Subsequent thermal annealing generated highly aligned lamellar morphology over a large area without any trace of an underlying photoresist pattern. Our method employing surface-parallel cylinder self-assembly as a structure-directing chemical pattern for epitaxial self-assembly does not require any substrate surface pretreatment and is, thus, highly efficient for nanopatterning various substrates.