Directing Block Copolymer Self-Assembly on Patterned Substrates.

Self-assembling block copolymer films provide access to a variety of different nanostructured patterns in one, two, and three dimensions. However, in the absence of any templating, these nanostructures suffer from defects, often limiting utility. Directed block copolymer self-assembly uses patterned substrates that effectively suppress defect formation and allow the creation of desired patterns. The two main directed self-assembly techniques, chemoepitaxy and graphoepitaxy, employ chemically and topographically patterned substrates, respectively, to direct the block copolymer assembly in thin films. Their successful application in generating defect-free patterns in films of block copolymers exhibiting particular morphologies is summarized in this concept article. The possible role of directed self-assembly in extending nanostructured patterning from two to three dimensions is also discussed.