To produce structures with long range order or with designed aperiodicities, we use topographical templates on the substrate, such as shallow trenches or small posts made by top-down lithography. These guide the self-assembly to give a desirable pattern. Non-bulk structures such as rectangular meshes can be made this way. This technique offers the promise of making useful structures for microelectronic devices, and DSA (directed self-assembly) is now part of the semiconductor roadmap to address future lithography needs.
Templating is combined with solvent annealing and other alignment techniques such as electric field application to give useful microdomain arrangements and realize 3D nanostructure fabrication. Modeling is critical in these studies, and we use self consistent field theory modeling to predict equilibrium microdomain structures. We developed an inverse algorithm which starts with the desired block copolymer pattern, and predicts the template that will generate it.
Examples of block copolymer patterns templated by posts