(797e) Free Energy of Block Copolymer Systems Via Thermodynamic Integration of a Mesoscale Block-Copolymer Model

Directed self-assembly (DSA) of block copolymers (BCPs) is a promising  technique for producing sub-30 nm pitch regular patterns, and the  development of these DSA techniques could benefit greatly from  computer simulation of such methods. Unlike other models, molecular  dynamics (MD) combined with realistic potentials for polymer behavior can potentially provide more accurate simulations of the inherent polymer  behavior, dynamics, and equilibrium states without a need to guess  modes of molecular movement and without oversimplifying interatomic interactions.

Through the use of thermodynamic integration, this model allows us to calculate free energy differences between various states, provided a reversible path can be envisioned between them. Using this technique, various equilibrium and metastable states can be compared. Defect free energies and subsequently defect densities can be calculated as functions of polymer and underlayer properties. Defectivity is the primary hurdle for implementation of BCP-DSA into semiconductor fabrication and defect free energies are critical to guide defectivity reduction techniques and patterning techniques. Free energy maps as a function of system properties like pitch, and polymer parameters can also be calculated. These calculations can provide insight into ideal and practical best case scenarios for both polymer properties and system guiding properties, whereas vast number of experiments would have to be run to achieve the same conclusions.