Synthesis and self-assembly of polystyrene block polyacrylic acid for sub 10 nm feature size

Abstract

To promote lithography in the semiconductor industry, self-assembling block copolymers are the most feasible and cost-effective option. To address the challenges of the semiconductor industry, including predesigned engineering plans and reduction of defects, the best way is to use the advantages of block copolymers. These advantages are pattern density multiplication, feature size uniformity improvement, reducing line edge roughness, cost reduction, reaching 10 nm resolution, and more. The research presented here shows that polystyrene block polyacrylic acid (PS-b-PAA) would be a good candidate for direct assembly to achieve below 10 nm and fewer defect patterns. Polystyrene block polymethyl acrylate copolymers were synthesized using ATRP. Hydrolysis resulted in di-block copolymers of PS-b-PAA with polydispersity indices (PDI) of less than 1.3. Samples were characterized by various techniques, including FT-IR, H-NMR, GPC, DSC, and rheometer. By applying the temperature sweep test, the order-disorder transition temperature of a sample was observed to be 157 °C in the Temperature Sweep Test of rheometer analysis. The samples were then self-assembled on wafer silicones, and the patterns were subjected to a variety of thermal treatments, including solvent annealing, microwave irradiation, and solvothermal annealing. AFM, TEM, and SAXS analyses were performed on samples. Microwave-assisted self-assembly annealing is known as a rapid way to reduce defects, while AFM images of solvothermal annealed samples reveal close competition between the two types of treatment. Self-assembled lamellae structures below 10 nm in diameter were studied.