Controlled self-assembly of block copolymers for device applications

Abstract

Block copolymer (BCP) self-assembly, which is driven by the microphase-separation of two mutually incompatible blocks, is garnering increasingly wide attention as a solution for future nanofabrication due to its excellent resolution, manufacturability, and cost-effectiveness. The self-assembly of a BCP can create sub-20 nm periodic patterns with diverse geometries such as dots, lines, holes, and rings, furthermore the self-assembled patterns can be easily transferred into different functional materials. However, the BCP self-assembly still has remaining challenges to be solved, for example, long annealing time, restricted morpholo-gies, and a narrow range of applications, thus limiting the extent of its utility. Therefore, the solutions for last-ing challenges in the BCP self-assembly were presented in this thesis, extending to the route for widespread coverage of BCP self-assembly.

To generate well-registered patterns within guiding templates by accelerating chain movements, ther-mal annealing or solvent annealing is typically used. Thermal annealing increases the temperature of BCPs over their glass transition temperatures, and is widely employed due to simplicities in processing for BCP with low Flory-Huggins interaction parameter (χ). For high-χ BCPs, solvent annealing, which can provide better chain flexibility compared to thermal annealing, has been more commonly used, with the aim of realizing good ordering of BCP microdomains. However, the self-assembled pattern generation takes a few to tens of hours, thus detrimentally affecting the throughput of directed self-assembly (DSA). Hence, a systematic study on the effects of simple low-temperature thermal assistance for solvent vapor treatment on BCPs with a large χ parameter was conducted, leading to well-ordered sub-10 nm half-pitch patterns were obtained via short annealing for 1 minute. Furthermore, it is investigated that the solvothermal annealing process is widely effective for realizing various mo...