Synthesis and Self-assembly of Silicon-containing Block Copolymers for Sub 5 nm Nanolithography

Ever-shrinking pattern features present challenges for the semiconductor industry. Directed self-assembly (DSA) of block copolymers (BCP) has been demonstrated as one high throughput and low cost manufacturing candidate for the next-generation of nanolithography. The thermodynamically immiscible polymer blocks selfassemble into the ordered nanostructures with varied morphologies, and the feature size is dependent on the FloryHuggins interaction parameter (chi) and the molecular weight (N) of BCP according to the self-consistent mean field theory. Design, synthesis, and self-assembly of novel high chi low N BCP is the long-term target for the community of polymer chemistry and materials science with the aim to achieve small size microphase separation domains. This review focuses on self-assembly of silicon-containing block copolymers for sub 5 nm nanolithography. Siliconcontaining block copolymers not only exhibit high. but also improve etch contrast property, which are considered as the promising materials for nanolithography. After a brief introduction of DSA, the main body is divided into three sections according to the chemical structures, including poly(dimethylsioxane)-based BCP, poly (silicon containing styrene)-based BCP, and poly(hedraloligomeric silsesquioxane)-based BCP. Each section covers self-assembly of bulk polymer and/or thin film, from historic initial study (>5 nm) to the recent progress (<5 nm). Synthesis, characterizations,., assembly conditions, feature sizes are discussed in detail. Finally, the challenges and opportunities are proposed. We hope this review would provide insights into polymer science and nanolithography technology.