Circular nanopatterns over large areas from the self-assembly of block copolymers guided by shallow trenches.

We report the fabrication of ultradense circular nanolines of block copolymer (BCP) microdomains over macroscopic areas. These lines were generated by the directed self-assembly (DSA) of BCPs on the topographically patterned substrates, where the trenches with circular shape are patterned on a flat substrate. The width of the trench and the distance between trenches are varied for commensurability issues, and difference BCPs are used to demonstrate the generality of this strategy. When a commensurability condition is satisfied, BCPs on the topographically patterned substrates undergo a DSA with solvent annealing, resulting in a flat film with an areal density amplification of the circular patterns over large areas. The methodology described here may provide an easy approach to high densities of circularly shaped nanopatterns for data storage device manufacturing.