High-chi block copolymers with tunable glass transition temperatures for directed self-assembly

摘要

Directed self-assembly (DSA) using block copolymers (BCPs) is emerging as a viable alternative to photolithography for creating features 10 nm and smaller. Block copolymers with balanced surface energy between the polymer blocks, tunable χ, and tunable glass transition temperatures (T_g) have been formulated. The block copolymers can achieve perpendicular orientation by simple thermal annealing due to the surface energy balance between the polymer blocks, which allows avoiding solvent annealing or top-coat. The χ value can be tuned up to achieve L₀ as low as 12 nm for lamellar-structured BCPs and hole/pillar size as small as 6 nm for cylinder-structured BCPs. The Tg of the BCPs can also be tuned to lower than those of PS-b-PMMA standards. The enhanced polymer chain mobility resulting from the decreased Tg of the block copolymer may help with improving the kinetics of BCP self-assembly during the thermal annealing.