Directed self-assembly of block copolymer thin film with vertical lamellae by applying filtered plasma and repeated shear stress

Directed self-assembly (DSA) of block copolymer (BCP) is a promising technology for nanolithography for semiconductors and nanodevices. Although defect-free BCP lamellar structure with vertical orientation nanopattern is necessary for the wide range of applications of BCP self-assembly, the formation of defect-free BCP lamellar nanostructures with vertical orientation in a large area is still a difficult challenge. In this study, we proposed a new approach of filtered plasma treatment and repeated shear stress on BCP film for directionally aligned and perpendicularly oriented lamellar BCP nanostructure. Shear induced ordering of BCP nanopatterns has been restricted to BCP with spherical and cylindrical nanopatterns because of the interfacial energy difference at surfaces. We introduced filtered plasma on the surface of the BCP thin film to produce crosslinked layer having neutral surface energy, and elastomer film was placed on the surface and subjected to shear stress to create a vertically oriented lamellae. To improve the quality of the alignment of BCP structures, the shear stress was repeatedly applied and defects of the nanopatterns were greatly reduced. Various types of BCP can be aligned with this strategy, and it suggests the potential for application in nanolithography.