Simulation study on defect annihilation dynamics in directed self-assembly lithography

The authors have investigated the defect annihilation dynamics of the grid defects, which are one of the characteristic pattern defects in directed self-assembly lithography, using a simulation method based on self-consistent field theory (SCFT) and dissipative particle dynamics (DPD). First, the mesoscopic morphologies of metastable grid defects using SCFT were calculated. Then, the SCFT simulation result was transformed into the particle representation using the node density biased Monte Carlo method. Next the authors monitored the chronological change of the conformation of the diblock copolymer (BCP) chains during the defect annihilation process using DPD. By DPD simulation, the characteristic changes of the chain conformations of BCP immediately above the bottom neutral layer have been observed. Polymer chains immediately above the bottom were found to be (1) partially vertical to the bottom in the initial defective state conditions, (2) randomly oriented in the intermediate transient state, and (3) parallel to the bottom in the equilibrium lamellar state. (C) 2015 American Vacuum Society.