Nanostructuring by ultrathin diblock copolymer/titanium composite films

Abstract The usability of ultrathin diblock copolymer films providing a heterogeneous chemical surface in a new nanolithographic technique is described. This technique allows the parallel preparation of periodic point pattern in an inorganic substrate. Diblock copolymers of polystyrene (PS) and poly-2-vinylpyridine (P2VP) are adsorbed from a nonselective solvent like chloroform on an ionic, high surface energy substrate (mica). Under these conditions formation of a regular, chemically heterogeneous nm-sized surface structure is observed consisting of isolated PS clusters which dewet the substrate covered by a 1nm thick film of adsorbed P2VP. Vapour deposition of titanium on the heterogeneous surface occurs preferentially on the less polar polystyrene islands. This way Ti films with regular thickness variations are formed corresponding to the pattern of the laterally segregated PS-b-P2VP film. The films are employed as lithographic masks allowing the transfer of the initial polymer pattern into the inorganic substrate with high aspect ratios.