Fabrication of silica mesh patterns via self-assembly of block copolymers

In this study, we developed a simple way to fabricate well-ordered nanoporous structures in square arrays, or mesh patterns. Inorganic silica mesh patterns in nanometer scale were generated by using self-assembly of block copolymers (BCPs). Polystyrene-block-poly(2-vinylpyridine) copolymers (S2VP) were deposited on a silicon wafer by the spin-coating method. Well-ordered cylindrical microdomains with parallel orientation to the surface were obtained after solvent-annealing in tetrahydrofuran (THF) vapor. Immersion of thin films into ethanol induced the reconstruction of their surface and caused trenches, which were porous structures. Polydimethylsiloxane (PDMS) was coated on the film and then exposed to UV-ozone to generate silica stripes from PDMS. As the previous steps were repeated, it was found by scanning probe microscopy (SPM) measurements that cylindrical microdomains were preferentially directed orthogonal to the ridge of Si stripes due to the wetting behavior of (BCPs). Finally, silica mesh patterns were fabricated from this distinct orientation of cylindrical microdomains on underlying Si stripes.