Thermodynamic and Kinetic Tuning of Block Copolymer Based on Random Copolymerization for High-Quality Sub-6 nm Pattern Formation

Abstract

The precisely controllable self-assembly phenomenon of block copolymers (BCPs) has garnered much attention because it yields well-defined periodic nanostructures with a periodicity of 5-50 nm. However, from both thermodynamic and kinetic viewpoints, it still remains a challenge to develop a BCP material that can provide sub-10 nm resolution, high pattern quality, fast pattern formation, and sufficient etch selectivity. To address these challenges, this study reports a BCP system containing a random-copolymerized block (poly(2-vinylpyridine-co-4-vinylpyridne)-b-poly(dimethylsiloxane) (P(2VP-co-4VP)-b-PDMS)) that can provide sub-6 nm resolution, 3 sigma line edge roughness of 0.89 nm, sub-1-min assembly time, and a high etch selectivity over 10. Calculation of the Flory-Huggins interaction parameter (chi) based on Leibler's mean-field theory and small-angle X-ray scattering measurement data confirms the gradual tunability of chi with the controlled addition of 4VP fraction in the P(2VP-co-4VP) block. While guaranteeing kinetically fast self-assembly within one minute using microwave annealing, the best pattern quality resulting from the thermodynamic suppression of line edge fluctuation is achieved with a 4VP weight fraction of 33% in the random-copolymerized block. This approach enables systematical control of sub-6 nm scale BCP self-assembly and will provide a practical patterning solution for diverse nanostructures and devices.