Self-assembly of Linear Block Copolymers and Bottlebrush Block Copolymers in Thin Films

Semiconductor device fabrication has been developing rapidly in recent years. It's been harder to keep up with Moore's law since top-down photolithography is approaching the diffraction limit. Self-assembly of block copolymers is a promising solution for its highly reproducible self-assembly, great diversity of morphology, good etching contrast, economic efficiency and recipes compatible for industrialization. Well-aligned self-assembled patterns with sub-10 nm feature size and good etching contrast in thin films have been achieved in recent years. However, poor solubility, microdomain orientation and high energy barrier for defect annihilation remain from their application. We developed a series of linear block copolymers and bottlebrush block copolymers containing ketal groups as side chains for low-χ to high-χ conversion in the solid state. Self-assembled lamellar and cylindrical morphologies, with a 5.4 nm full pitch have been obtained in the bulk and 9.4 nm full pitch in thin films, which is among the smallest domains obtained so far.