Three-dimensional (3-D) structures at the nanoscale
are important in modern devices, although their fabrication with
traditional top-down approaches is complex and expensive. Block
copolymers (BCPs) that are analogous to atomic lattices can
spontaneously form a rich variety of 3-D nanostructures to
substantially simplify 3-D nanofabrication. In a new report on
Science Advances, Jiaxing Ren and a research team in molecular
engineering, chemical engineering and materials science at the
University of Chicago, Technion-Israel Institute of Technology and
the Argonne National Laboratory in the U.S. and Israel formed a 3-D
superlattice using BCP micelles. They controlled the process using
lithographically defined 2-D templates that matched a
crystallographic plane in the 3-D superlattice. Using scanning
transmission electron microscopy tomography, the team demonstrated
precise control across the lattice symmetry and orientation. They
achieved excellent ordering and substrate registration through
284-nanometer-thick films. To mediate lattice stability, the
scientists tapped into molecular packing frustration of the
superlattice and observed surface-induced lattice reconstruction,
which led to form a unique honeycomb lattice.
