Improved Ordering Quality in Shear Aligned Block Copolymer Thin Films via Solvent Vapor Exposure

Block copolymers (BCPs) have the ability to create various nanoscale structures through microphase separation, but defects formed during the ordering process often interfere a successful lithographic application of BCPs. Furthermore, defect control in large area has been challenged at the application level. In this study, we introduce a facile method for the large-area defect control using solvent vapor annealing (SVA) in shear-aligned BCP thin films. Cylinder forming polystyrene-b-poly(2-vinylpyridine) (PS-b-P2VP) was firstly shear-aligned and then exposed to the various solvent vapor. Grazing incidence small-angle X-ray scattering and SEM image analysis were used for quantitative characterization of SVA effects. Through the proper SVA process, it was confirmed that the correlation length of BCP film can be increased and the defect areal density and line edge roughness can be reduced, leading to a highly aligned line pattern in a large area.