RETRACTED ARTICLE: Sub-10 nm Thin Film Feature Sizes of Chemically Tailored Poly(styrene-block-methyl methacrylate) with Randomly Distributed Fluorine Units

In all reported block copolymer (BCP) materials for the lithographical application, poly(styrene-block-methyl methacrylate) (PS- b -PMMA) is the most widely studied BCP due to its ability to form perpendicularly oriented features when simply heated on an energetically non-preferential substrate. However, the desired smallest attainable pattern size prepared from PS- b -PMMA is limited to a full pitch of 24 nm, because of the relatively weak segregation between segments. To address the problem, precisely controlled amounts of randomly polymerized glycidyl methacrylate are first incorporated into the PMMA block in PS- b -PMMA. Subsequently, 2,2,2-trifluoroethanethiol is quantitatively introduced into the randomly distributed preset reactive sites in PMMA-based block via thiol-epoxy reaction. By merely introducing 20% molar percentages of 2,2,2-trifluoroethanethiol into the PMMA-based block, the effective χ parameter is significantly increased by 60%, resulting in BCPs capable of forming sub-15 nm domains. The existed neutralized interfacial conditions for inducing perpendicularly oriented PS- b -PMMA domains are compatible with the newly synthesized poly(styrene-block-(2-hydroxy-3-(2,2,2-trifluoroethylsulfanyl)propylmethacrylate-random-methyl methacrylate)) (PS- b -(PHFMA- r -PMMA)), and long-ranged ordered 15 nm-lamellae with 7.5 nm feature size (half pitch) can be vertically oriented in the thin film with short-time thermal annealing.