Nano-confinement of block copolymers in high accuracy topographical guiding patterns: modelling the emergence of defectivity due to incommensurability

Extreme ultraviolet interference lithography (EUV-IL) is used to manufacture topographical guiding patterns to direct the self-assembly of block copolymers. High-accuracy silicon oxide-like patterns with trenches ranging from 68 nm to 117 nm width are fabricated by exposing a hydrogen silsesquioxane (HSQ) resist layer using EUV-IL. We investigate how the accuracy, the low line width roughness and the low line edge roughness of the resulting patterns allow achieving DSA line/space patterns of a PS- b -PMMA (polystyrene- block -poly methyl methacrylate) block copolymer of 11 nm half-pitch with low defectivity. We conduct an in-depth study of the dependence of the DSA pattern morphology on the trench width and on how the neutral brush covers the guiding pattern. We identify the relation between trench width and the emergence of defects with nanometer precision. Based on these studies, we develop a model that extends available free energy models, which allows us to predict the patterning process window. Nanometer accurate fabrication of topographical guiding patterns via EUV-IL helps to improve exisiting energy modelling of confined block copolymers.