Research Highlight | Materials Science

Molecular pathways for defect-annihilation in copolymer directed self-assembly
In a study published in ACS Nano, researchers demonstrate that annihilation pathways depend strongly on both the separation between dislocations and their relative position with respect to the substrate guiding stripes used to direct the assembly.
Molecular pathways for defect-annihilation in copolymer directed self-assembly image
Converged free energy vs reaction coordinate profiles shown in red and blue for two different initial strings. The top-down views of structures corresponding to the free energy maxima along the two curves are labeled as t-blue and t-red. The initial and final structures are also included in the figure.

Scientific Achievement

Molecular mechanism of defect annihilation in directed self-assembly of block copolymers on patterned substrates.

Significance and Impact

Directed self-assembly of block copolymers provides a promising route towards the fabrication of devices with characteristic dimensions on the scale of 5 to 20 nm. Understanding the pathways for removal of low-density defects will enable deployment of DSA based technologies for applications ranging from microelectronics to quantum information sciences.

Research Details

  • Detailed molecular models of block copolymer directed self-assembly permit calculation of the probability of forming rare defects.
  • Advanced sampling techniques enables calculation of the minimum-free-energy pathway (including free energy barriers) for annihilation of such defects under experimentally relevant conditions.
  • High-precision experimental measurements of defect density and defect annealing confirm the predictions of simulations.

Work was performed at Argonne National Laboratory.

DOI: 10.1021/acsnano.8b04202

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