Eliminating the Trade‐Off between the Throughput and Pattern Quality of Sub‐15 nm Directed Self‐Assembly via Warm Solvent Annealing

Abstract

The directed self-assembly (DSA) of block copolymers (BCPs) has been suggested as a promising nanofabrication solution. However, further improvements of both the pattern quality and manufacturability remain as critical challenges. Although the use of BCPs with a high Flory-Huggins interaction parameter ( χ ) has been suggested as a potential solution, this practical self-assembly route has yet to be developed due to their extremely slow selfassembly kinetics. In this study, it is reported that warm solvent annealing (WSA) in a controlled environment can markedly improve both the selfassembly kinetics and pattern quality. A means of avoiding the undesirable trade-off between the quality and formation throughput of the self-assembled patterns, which is a dilemma which arises when using the conventional solvent vapor treatment, is suggested. As a demonstration, the formation of well-defi ned 13-nm-wide self-assembled patterns (3σ line edge roughness of ≈2.50 nm) in treatment times of 0.5 min (for 360-nm-wide templates) is shown. Self-consistent fi eld theory (SCFT) simulation results are provided to elucidate the mechanism of the pattern quality improvement realized by WSA.

In Situ Tracking of Composition and Morphology of a Diblock Copolymer Film with GISAXS during Exchange of Solvent Vapors at Elevated Temperatures

“…Solvent vapor annealing (SVA) is a widely used method to obtain highly ordered nanostructured BCP thin films, which also has been applied to modify the BCP thin film morphology . In recent years, the efficiency of this approach was improved by the so‐called warm or solvothermal vapor annealing (STVA) . In some of these studies, liquid solvent is present in the sample chamber, which is heated, whereas in other studies, the sample is heated while being exposed to solvent vapor from a bubbler, or the preheated sample is placed in solvent vapor .…”

“…In recent years, the efficiency of this approach was improved by the so‐called warm or solvothermal vapor annealing (STVA) . In some of these studies, liquid solvent is present in the sample chamber, which is heated, whereas in other studies, the sample is heated while being exposed to solvent vapor from a bubbler, or the preheated sample is placed in solvent vapor . When using bubblers, the choice of the sample temperature and the vapor temperature are of importance for the kinetics of film swelling: increasing the sample temperature has been found to reduce the swelling ratio, whereas increasing the temperature of the bubbler results in an increased vapor pressure, which leads to an increase of the swelling ratio.…”

In Situ Nanolithography with Sub‐10 nm Resolution Realized by Thermally Assisted Spin‐Casting of a Self‐Assembling Polymer

“…One more trend seen in Figure d is that the LER and LWR values were lowest when T WSC = 45 °C. At a low T WSC region, the lower pattern quality can be explained through the insufficient thermal assistance (low T WSC ) and the stress field from the stretching caused by the incommensurability, as demonstrated in a previous study on warm solvent annealing of high‐ χ BCP . Thus, a slight increase in the spin‐casting temperature enhances the thermal activation effect, and the appropriate size matching between the BCP and guide trench can relax the polymer chain, which subsequently achieves the best pattern quality.…”

“…Recently, a synergic combination of thermal and solvent annealing has been reported to markedly facilitate the self‐assembly kinetics of high‐ χ or high N (= degree of polymerization) BCPs . We have also reported the fast self‐assembly of a high‐ χ BCP (PS‐ b ‐PDMS) via thermally assisted solvent annealing, which has multifariously advantageous from the perspectives of both pattern quality and throughput . However, if the post‐spin‐coating annealing process can be removed from DSA, the overall processing time and process complexity can be reduced significantly.…”

Technological strategies for self-assembly of PS-b-PDMS in cylindrical sub-10 nm nanostructures for lithographic applications

“…The high χ AB N of silicon-containing DBCs, such as PS-b-PDMS, is expected to cause an extremely slow self-assembly and lateral ordering kinetic [75]. In principle, thermal treatments in furnace at high temperatures could speed up the ordering kinetics.…”