Defect motion and annihilation in block copolymers*

Directed self-assembly (DSA) of block copolymers for microelectronic device fabrication requires excessively small defect densities. Whereas the excess free energy of a defect in a perfect lamellar structure exceeds by far the thermal energy scale kT, and the equilibrium defect density is vanishingly small, defects are observed in experiments and simulations. Thus, defects occur in the course of the kinetics of structure formation. Using simulations of a soft, coarse-grained model, SCFT calculation and continuum models we study the kinetics of structure formation, defect motion and annihilation, as well as the underlying free-energy landscape. The study identifies optimal conditions for defect free self-assembly and discusses how the guiding structures influence the interaction between defects. The ability of continuum models to describe these phenomena is also critically evaluated.