Directed Self-Assembly of Poly(4-chlorostyrene- <i>b</i> -methyl acrylate) Block Copolymers for Sub-10 nm Features via Thermal Annealing

Directed self-assembly (DSA) of block copolymers (BCPs) has shown great potential for creating sub-10 nm patterns for advanced semiconductor manufacturing. It is necessary to develop block copolymers with high Flory–Huggins interaction parameters (χ) and similar surface energies (γ) between constituent blocks. Herein, this work presents the synthesis of lamellae-forming poly(4-chlorostyrene-b-methyl acrylate) (P4ClS-b-PMA) and investigates the DSA behavior of P4ClS-b-PMA. P4ClS-b-PMA has a higher χ than poly(styrene-b-methyl methacrylate) (PS-b-PMMA) and poly(styrene-b-methyl acrylate) (PS-b-PMA), resulting in the smallest achievable period (L0) to 14.1 nm. Notably, the P4ClS and PMA blocks possess similar γ values, which facilitates the formation of perpendicularly orientated domains in P4ClS-b-PMA films on neutral, substrate-modified silicon wafers under thermal annealing. 7× density multiplication DSA of P4ClS-b-PMA is successfully demonstrated in films on chemical patterns fabricated by 193 immersion (193i) lithography, with a feature size of about 7.5 nm. These findings confirm that P4ClS-b-PMA could be a potential candidate for DSA lithography.