Creating perpendicular alignment in lamellar
block copolymer (BCP) systems has considerable industrial
and commercial significance, most importantly for generating
nanowire structures in electronic devices. In general,
these lamellar systems require careful interface engineering
to obtain vertical orientation of the blocks. To avoid the
strong preferential adsorption of one block to either the
substrate or the polymer/air interface, the surface must be
‘‘neutralized’’ by chemical brushes or external forces, for
example, solvent fields. Reported here is a stepwise
thermo/solvent annealing process allowing the formation of
perpendicular domains of polystyrene-b-polyethylene oxide lamellar structures while avoiding brush or other surface
modifications. This BCP has a relatively small minimum
feature size and can be used to generate substrate patterns
for use in fabrication of nanowire electronic device structures.