Block Copolymer with an Extremely High Block-to-Block Interaction for a Significant Reduction of Line-Edge Fluctuations in Self-Assembled Patterns

Directed self-assembly (DSA) of block copolymers (BCPs) with a high Flory–Huggins interaction parameter (χ) provides advantages of pattern size reduction below 10 nm and improved pattern quality. Despite theoretical predictions, however, the questions of whether BCPs with a much higher χ than conventional high-χ BCPs can further improve the line edge roughness (LER) and how to overcome their extremely slow self-assembly kinetics remain unanswered. Here, we report the synthesis and assembly of poly­(4vinylpyridine-b-dimethylsiloxane) BCP with an extremely high χ-parameter (estimated to be approximately 7 times higher compared to that of poly­(styrene-b-dimethylsiloxane) – a conventional high-χ BCP) and achieve a markedly low 3σ line edge roughness of 0.98 nm, corresponding to 6% of its line width. Moreover, we demonstrate the successful application of an ethanol-based 60 °C warm solvent annealing treatment to address the extremely slow assembly kinetics of the extremely high-χ BCP, considerably reducing the self-assembly time from several hours to a few minutes. This study suggests that the use of BCPs with an even larger χ could be beneficial for further improvement of self-assembled BCP pattern quality.