A Route to Addressable Terabit/in2 Arrays Using Block Copolymers
University of Massachusetts, Amherst, MA, US
block copolymers, self-assembly, addressable terabit/in2 arrays
The self-assembly of materials is emerging as a key element in the fabrication of functional nanostructured materials. However, self-assembly alone, in many cases, is not sufficient to guarantee the generation of defect-free structures. Rather, directed self-assembly, where external fields are used to bias the ordering, are required. Block copolymers, composed of two dissimilar polymer chains linked together at one end, represent a versatile class of materials that form arrays of nanostructures commensurate with the size of the polymer chain, on nanometer to tens of nanometer size scale. Of particular interest are diblock copolymers that microphase separate into arrays of hexagonally close-packed nanoscopic cylindrical domains where the segmental interactions are strongly non-favorable. A simple, robust means is demonstrated to produce thin films containing arrays of highly-oriented, closed-packed, nanoscopic cylindrical domains that span the entire film thickness and have an exceptionally high degree of long-range lateral order. By using solvent casting or spin coating methods, an ordering of the copolymer is initiated at the surface of the films and, as solvent evaporates in a controlled manner, the ordering of the copolymer propagates through the film, templating onto the already ordered copolymer. However, the solvent imparts a high degree of mobility that allows the lateral ordering of the copolymer to perfect by removing defects rapidly. This process represents a simple route towards achieving addressable arrays of nanoscopic elements in a highly-controlled manner.
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Nanotech 2006 Conference Program Abstract