As the demand for advanced device performance, feature density, and processing speed increases, the modern semiconductor industry is now relying on 193 nm immersion lithography, often augmented with multiple patterning techniques, to reduce the critical dimension of nanopatterns in integrated circuits. However, continued technological progress is challenged by high implementation costs and the intrinsic limitations of conventional top-down photolithography. Thus, alternative bottom-up lithographic techniques utilizing molecular self-assembly, including block copolymer (BCP) thin film lithography, have garnered substantial attention. BCPs can spontaneously assemble into nanometer scale periodic morphologies in thin films, which can later be used as an etch mask for transferring the pattern into underlying materials. Recently, a great deal of effort has been focused on the self-assembly of Si-containing blocks paired with more polar adjoining blocks to drive a large interaction parameter (Ï). When paired with more polar blocks, the added Si promotes microphase separation at low molecular weights into sub-10 nm domains. Incorporation of Si also imparts high etch selectivity to ensure effective pattern transfer into other materials.
In this work, poly(pentamethyldisilyl styrene)-block-poly(ethyl glycolide) (PDSS-PEGL) BCPs were used to fabricate perpendicular lamellar nanostructures with sub-10 nm linewidth. The top and the substrate interfacial interactions for the PDSS-PEGL thin films were precisely tuned to control the orientation of nanostructures across the entire substrate. The film was then treated with reactive ion etching protocols to remove the PEGL block and produce perpendicular line-space patterns with feature sizes of about 6 nm over a large area. The PDSS-PEGL BCP system is a promising candidate for sub-10 nm patterning processes in future lithographic applications.