The flexible control
of nanopatterns by a bottom-up process at
the nanometer scale is essential for nanofabrication with a finer
pitch. We have previously reported that for the fabrication of linear
nanopatterns with sub-5 nm periodicity on Si substrates the outermost
surfaces of assembled micelles facing the substrates can be replicated
with soluble silicate species generated from the Si substrates under
basic conditions. In this study, concentrically arranged nanogrooves
with a sub-5 nm periodicity were prepared on Si substrates by replicating
the outermost surfaces of bent micelles guided by silica particles.
The Si substrates, where silica particles and surfactants films were
deposited, were exposed to an NH3–water vapor mixture.
During the vapor treatment, cylindrical micelles became arranged in
concentric patterns centered on the silica particles, and their outermost
surfaces facing the substrates were replicated by soluble silicate
species on the Si substrates. The thinness of the surfactant film
on the substrate is crucial for the formation of concentric silica
nanogrooves because the out-of-plane orientations of the micelles
are suppressed at the interface. Surprisingly, the domains of the
concentric silica nanogrooves spread to much larger areas than the
maximum cross-sectional areas of the particles, and the size of the
domains increased linearly with the radii of the particles. The extension
of concentric nanogrooves is discussed on the basis of the orientational
elastic energies of the micelles around one silica particle. This
study of the formation of bent nanogrooves guided by the outlines
of readily deposited nanoscale objects provides a new nanostructure-guiding
process.