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Enhancing the Directed Self-assembly Kinetics of Block Copolymers Using Binary Solvent Mixtures

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journal contribution
posted on 25.11.2015, 00:00 by Woon Ik Park, Young Joong Choi, Je Moon Yun, Suck Won Hong, Yeon Sik Jung, Kwang Ho Kim
The rapid pattern formation of well-ordered block copolymer (BCP) nanostructures is practical for next-generation nanolithography applications. However, there remain critical hurdles to achieve the rapid self-assembly of BCPs with a high Flory–Huggins interaction parameter (χ), owing to their slow kinetics. In this article, we report that a binary solvent vapor annealing methodology can significantly accelerate the self-assembly kinetics of poly­(dimethylsiloxane-b-styrene) (PDMS-b-PS) BCPs with a high-χ. In particular, we systemically analyzed the effects of the mixing ratio of a binary solvent composed of a PDMS-selective solvent (heptane) and a PS-selective solvent (toluene), showing an ultrafast self-assembly time (≤1 min) to obtain a well-ordered nanostructure. Moreover, we successfully accomplished extremely fast generation of sub-20 nm dot patterns within an annealing time of 10 s in a 300 nm-wide trench by means of binary solvent annealing. We believe that these results are also applicable to other solvent-based annealing systems of BCPs and that they will contribute to the realization of next-generation ultrafine lithography applications.