Spontaneous self-assembly of diblock copolymers in nanoconfined geometries by dissipative particle dynamics

Abstract

We performed dissipative particle dynamics (DPD) simulations to reproduce phase separation morphologies of diblock copolymers for directed self-assembly (DSA) lithography. DSA is a promising technique to overcome the current photolithography resolution limit. The Flory–Huggins χ parameter estimated from a small-angle X-ray scattering experiment was used for the DPD simulations owing to the multiple degrees of coarse-graining. The degree of coarse-graining and the bond parameter for the spring force were optimised to represent the experimental result of the number of lamellar layers formed in a trench guide. The DPD simulations using these parameters can also represent the diameter of the central cylinder domain that is formed by phase separation in the cylindrical hole. It was found that the bond parameter considering the spreading of polymer segments in a coarse-grained particle gives good quantitative agreement between the results of the simulations and the experimental data.

Keywords::

• directed self-assembly
• dissipative particle dynamics simulation
• phase separation

Acknowledgements

We would like to thank Katsumi Ohmori, Taku Hirayama, Ken Miyagi, Tasuku Matsumiya, Daijyu Shiono of Tokyo Ohka Kogyo Co., Ltd for providing the experimental data to support this work and fruitful discussions. We are also grateful to Professor Y. Tamai for helpful discussions.