Pattern Transfer of Sub-10 nm Features via Tin-Containing Block Copolymers

Tin-containing block copolymers were investigated as materials for nanolithographic applications. Poly(4-trimethylstannylstyrene-block-styrene) (PSnS-PS) and poly(4-trimethylstannylstyrene-block-4-methoxystyrene) (PSnS-PMOST) synthesized by reversible addition-fragmentation chain transfer polymerization form lamellar domains with periodicities ranging from 18 to 34 nm. Thin film orientation control was achieved by thermal annealing between a neutral surface treatment and a top coat. Incorporation of tin into one block facilitates pattern transfer into SiO₂ via a two-step etch process utilizing oxidative and fluorine-based etch chemistries.