Directed Self-Assembly of Diblock Copolymer Thin Films on Chemically-Patterned Substrates for Defect-Free Nano-Patterning

We demonstrate that polystyrene-block-poly(methylmethacrylate) (PS-b-PMMA) can self-assemble in a well-aligned, long-range ordered nanopattern over arbitrarily large areas, commensurate with chemically prepatterned templates prepared by electron beam (EB) lithography. The epitaxially grown cylindrical microdomain formed a defect-free hexagonal lattice although the Chemically-Patterned substrate had some defects in its pattern and errors in pattern position. Furthermore, we demonstrated that the self-assembly process can interpolate points in between the EB generated pattern, thus multiplying the pattern density. The result suggests that the self-assembly of PS-b-PMMA can repair the defects of the patterned substrate, while the patterned substrate can align the domain structures of block copolymer into a long-range ordered single array. The developed process, which combines EB lithography and self-assembly of diblock copolymer provides a promising fabrication method for extension of top down-type lithographic capabilities to very high densities.