Directed Self‐Assembly of Polystyrene‐Block‐Polyhedral Oligomeric Silsesquioxane Monolayer by Nano‐Trench for Nanopatterning

Abstract This work pioneers to combine fast self‐assembly of polyhedral oligomeric silsesquioxanes (POSS) nanocage‐based giant surfactants with high etching contrast and directed self‐assembly for reliable long‐range lateral order to create well‐aligned sub‐10 nm line nanopatterns via reactive ion etching (RIE). Polystyrene‐block‐oligo(dimethylsiloxane) substituted POSS (PS‐b‐oDMS₇POSS) with seven oligo(dimethylsiloxane) at the corners of the POSS nanocage and one polystyrene (PS) tail is designed and synthesized as a giant surfactant with self‐assembly behaviors like block copolymer (BCP). In contrast to BCP, oDMS₇POSS gives a volume‐persistent “nanoatom” particle with higher mobility for fast self‐assembly and higher segregation strength with PS for smaller feature size. By taking advantage of directed self‐assembly using nano‐trench fabricated by electron beam lithography, well‐ordered nanostructured monolayer with well‐aligned parallel oDMS₇POSS cylinders can be formed by confined self‐assembly within the nano‐trench. With the optimization of the RIE treatment using O₂ as an etchant, the high etching contrast from the oDMS₇POSS and PS gives the formation of well‐defined line nanopatterns with sub‐10 nm critical dimension that can serve as a mask for pattern transfer in lithography. These results demonstrate a cost‐effective approach for nanopatterning by utilizing a creatively designed giant surfactant with sub‐10 nm feature size and excellent etching contrast for modern lithographic applications.