Mechanisms of Directed Self-Assembly in Cylindrical Hole Confinements

• Published in: Macromolecules Vol. 51; no. 7; pp. 2418 - 2427
• Main Authors: Bezik, Cody T, Garner, Grant P, de Pablo, Juan J
• Format: Journal Article
• Language: English
• Published: United States American Chemical Society 10-04-2018
• Subjects: ENGINEERING; MATERIALS SCIENCE
• ISSN: 0024-9297; 1520-5835
• DOI: 10.1021/acs.macromol.7b02639

The directed self-assembly of block copolymers in cylindrical holes is a promising technology for lithographic patterning, particularly in the context of vertical interconnect accesses. While the hole-shrink process for single cylinders has been extensively explored, the proliferation of morphological defects remains a significant technological barrier. We use a coarse-grained model to explore morphologies that form within cylindrical confinements for combinations of template surface energies. We identify metastable defect morphologies, in addition to the desired cylindrical morphology, in majority-wetting sidewall templates. We use our coarse-grained model and the string method to identify transition pathways between defective morphologies and the cylindrical morphology to elucidate the mechanism of defect annihilation within the confinements; the transition pathway from a disordered state is also identified. This work demonstrates that the minimum free energy path for the formation of a cylinder goes through defective morphologies and that designing confinements can eliminate these undesirable transition states.