​Directed self-assembly (DSA) is a type of directed assembly which utilizes block copolymer morphology to create lines, space and hole patterns, facilitating for a more accurate control of the feature shapes. Block copolymers (BCPs) comprise two or more chemically dissimilar homopolymer subunits that can form distinct phases when appropriately treated. The extent of phase separation at equilibrium for BCPs is determined by the Flory-Huggins interaction parameter (χ) and the overall number-average degree of polymerisation (N). Symmetrical BCPs (f = 0.5) can form regular repeating lamellar morphologies and are typically desired for line/spacing patterning due to their advantages in pattern transfer. To achieve the perpendicular lamellar structures, a so-called “neutral” surface, in which the interface energy between the substrate and the two blocks of the BCPs are equal, is necessary. Due to the great potential of DSA, it is widely regarded as one of the most promising candidate technologies for next-generation lithography. This project will develop new BCPs for this important application.

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