Orientation-controlled self-assembled nanolithography using a polystyrene-polydimethylsiloxane block copolymer

Templated self-assembly of a cylinder-forming poly(styrene-b-dimethylsiloxane) (PS-PDMS) diblock copolymer has been investigated for nanolithography applications. The large chi-parameter of the blocks and the use of a PDMS-brush substrate surface treatment are especially advantageous for achieving long-range ordering and minimizing defect densities, and the high Si content in PDMS leaves a robust oxide etch mask after two-step reactive ion etching. By adjusting mesa width and solvent-annealing vapor pressure and time, the cylinders can be intentionally oriented parallel or perpendicular to the trench walls. Pattern transfer into thin silica is also demonstrated. This block copolymer system has excellent characteristics for self-assembled nanolithography applications.