Self-assembly of block copolymers by graphoepitaxy

In the fabrication of a desired block copolymer (BCP) nanostructure for a particular application, a key challenge is the control of the BCP microdomain assembly. Graphoepitaxy is a solution to this challenge. Graphoepitaxy provides multifaceted mechanisms to order and direct ­microdomains and to fabricate complicated single-layer or multilayer structures over large areas. Topographical templates can be fabricated using different top-down lithography or self-forming methods. These templates direct the self-assembly through key mechanisms such as commensurability, lateral ordering, and confinement effects. Hence, many different morphologies, either equilibrium or nonequilibrium, can be controlled to produce desired nanopatterns. To date, BCP graphoepitaxy has been employed in many applications, from nanoelectronics to medical filters and from memory storage to biological substrates.