The hole shrink problem: Theoretical studies of directed self-assembly in cylindrical confinement

We use self-consistent field theory (SCFT) to study the self-assembly of cylinder-forming diblock copolymers confined in a cylindrical prepattern. This situation arises in contact holes -the hole shrink problem-where the goal is to produce a cylindrical hole with reduced dimensions relative to a guiding prepattern. In this study, we focus on systems with a critical dimension (CD) ranging from 50nm to 100nm and which consequently lead to the formation of a single cylinder in the middle of the hole. We found that different morphologies arise from the self-assembly process and are strongly governed by the prepattern dimensions, wetting conditions as well as the polymer molecular weight. We also considered blends of diblock copolymers and homopolymers and determined optimal blending configurations that not only favor the formation of the desired cylindrical morphology but also extend the processing window relative to the pure diblock case.