Nanostructuring by ultrathin diblock copolymer/titanium composite films

The usability of ultrathin diblock copolymer films providing a heterogeneou s chemical surface in a new nanolithographic technique is described. This t echnique allows the parallel preparation of periodic point pattern in an in organic substrate. Diblock copolymers of polystyrene (PS) and poly-2-vinylp yridine (P2VP) are adsorbed from a nonselective solvent like chloroform on an ionic, high surface energy substrate (mica). Under these conditions form ation of a regular, chemically heterogeneous nm-sized surface structure is observed consisting of isolated PS clusters which dewet the substrate cover ed by a 1nm thick film of adsorbed P2VP. Vapour deposition of titanium on t he heterogeneous surface occurs preferentially on the less polar polystyren e islands. This way Ti films with regular thickness variations are formed c orresponding to the pattern of the laterally segregated PS-b-P2VP film. The films are employed as lithographic masks allowing the transfer of the init ial polymer pattern into the inorganic substrate with high aspect ratios. ( C) 1999 Acta Metallurgica Inc.