Synthesis and self-assembly of block copolymers with precisely controlled flory-huggins interaction parameter

Abstract

Directed self-assembly (DSA) of block copolymers (BCP) has garnered much attention due to its well-defined periodic nanostructures of spherical, cylindrical, and lamellar morphologies with a period of 5 - 50 nm. In particular, DSA can provide multiple advantages of high resolution, scalability, and cost-effectiveness, thus it considered as a practical approach to manufacture various semiconductor devices and next-generation information storage media. However, there exist only few BCPs with a high Flory-Huggins interaction parameter ($\chi$) can provide sub-10 nm resolution, high pattern quality, and sufficient etch selectivity. The high-$\chi$ BCPs can generate the high resolution patterns with a low line edge roughness, however, the slow chain diffusion of BCPs results in a prolonged assembly time. Therefore, the $\chi$ of BCP is a main factor to determine the characteristics of self-assembly. To generate well-aligned nano structures within 10 nm dimeter, we synthesize BCPs with a precisely controlled $\chi$ value by diverse organic chemistry and polymer synthesis methods. The BCPs consist of poly(dimethylsiloxane) as one block and poly(2-vinylpyridne), poly(4-vinylpyridne) and poly(isoprene) as other blocks. The $\chi$ value of synthesized BCPs is calculated by small angle X-ray scattering (SAXS) measurement and Libler’s mean field theory. Furthermore, we study that the effect of $\chi$ value on self-assembled pattern quality via the synthesized BCPs. We expect that these diverse BCPs would enable to open the possibility of DSA for future applications.