Calculations of the free energy of dislocation defects in lamellae forming diblock copolymers using thermodynamic integration

Andrew J. Peters; Richard A. Lawson; Benjamin D. Nation; Peter J. Ludovice; Clifford L. Henderson

doi:10.1117/1.JMM.15.2.023505

10 May 2016 Calculations of the free energy of dislocation defects in lamellae forming diblock copolymers using thermodynamic integration

Andrew J. Peters, Richard A. Lawson, Benjamin D. Nation, Peter J. Ludovice, Clifford L. Henderson

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Journal of Micro/Nanolithography, MEMS, and MOEMS, Vol. 15, Issue 2, 023505 (May 2016). https://doi.org/10.1117/1.JMM.15.2.023505

Abstract

State-of-the-art directed self-assembly (DSA) of block copolymer (BCP) methods still yield defect densities orders of magnitude higher than is necessary in semiconductor fabrication. The defect free energy of a dislocation pair or jog defect, one of the most common defects found in BCP-DSA, is calculated via thermodynamic integration using a coarse-grained molecular dynamics model as a function of χ and the degree of polymerization (N). It is found that χN is not the best predictor of defect free energy and that a single χN value can yield vastly different free energies when χ and N are different. Defect free energy was highly dependent on defect location relative to the underlayer, and free energy differences ∼100 kT were found among the three possible defect locations on a 1:3 guiding pattern. It was found that increasing molar mass dispersity (Ð) significantly reduced defect free energy. Extrapolating from Ð up to 1.5 suggests that the defect will occur in equal proportions to the defect free state at a Ð of around 1.6 for this system. It was found that long chains tended to concentrate near the defect and stabilize the defect.

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Andrew J. Peters, Richard A. Lawson, Benjamin D. Nation, Peter J. Ludovice, and Clifford L. Henderson "Calculations of the free energy of dislocation defects in lamellae forming diblock copolymers using thermodynamic integration," Journal of Micro/Nanolithography, MEMS, and MOEMS 15(2), 023505 (10 May 2016). https://doi.org/10.1117/1.JMM.15.2.023505

Published: 10 May 2016

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