Formation of ordered nanocluster arrays by self-assembly on nanopatterned Si(100) surfaces

Abstract

A precisely ordered and precisely located array of 5 nm diameter nanoclusters has been fabricated by first etching into the substrate an array of holes with diameters comparable with the size of nanoclusters sought and then depositing adatoms on the substrate. The severely restricted diffusion field defined by the holes dominates nucleation and growth to produce a single nanocluster in each etched hole. Using low energy electron enhanced etching in a DC hydrogen plasma, we transferred an hexagonal array of 18 nm diameter holes with a 22 nm lattice constant from a biologically derived mask into Si(100). After etching, the mask was removed, and the patterned surface was intentionally oxidized in an oxygen plasma. Deposition of 1.2 nm of Ti on the oxidized surface produced an ordered array of 5 nm diameter metal nanoclusters positioned at the etched hole sites. Our methods achieved massively parallel processing at the key fabrication steps of pattern generation, pattern transfer, and nanocluster formation. Therefore, our methods enable rapid fabrication of arrays for fundamental studies and provide a route to manufacturability of nanostructure arrays for technological purposes.