Directed Self-Assembly of Fluorine-Containing High-<i>χ</i> Block Copolymers using Top Coat and Electric Field

Directed self-assembly (DSA) of block copolymers (BCPs) have been attractive for “bottom-up” approach lithographical applications. BCPs can form nanoscale structures spontaneously in long-range alignment with small feature down to 5 nm. In this study, we report a newly designed fluorine containing BCPs (polystyrene-b-poly(2,2,2-trifluoroethyl acrylate)) which the Flory-Huggins interaction parameter (χ) was above 0.2. Film experiments were demonstrated on a neutralized substrate where a sub-10 nm perpendicular lamellar morphology was observed with simple thermal annealing using the top coat strategies. The neutral conditions of the top coats for the BCP top surface was tuned by the same monomer of the BCP and the orientation was confirmed by AFM and GISAXS. Electric field was applied for the DSA, observing a long-range alignments without neither chemoepitaxy nor graphoepitaxy.