High χ P2PFBEMA-b-P2VP Block Copolymers Forming 6-8 nm Domains for Semiconductor Lithography.

We leveraged the potential of high χ-low N block copolymer (BCP), namely, poly[2-(perfluorobutyl) ethyl methacrylate]-block-poly(2-vinylpyridine) (P2PFBEMA-b-P2VP), and demonstrated its utility in next-generation nanomanufacturing. By combining molecular dynamics simulations with experiments, the χ value was calculated to be as high as 0.4 (at 150 °C), surpassing similar structures. Highly ordered features suitable for application were observed, ranging in periods from 19.0 nm down to 12.1 nm, with feature sizes as small as 6 nm. Transmission electron microscopy images of the BCP solutions indicated that preformed micelles in the solution facilitated the self-assembly process of the thin film. In addition, the vertical or parallel orientation of the cylindrical structure was determined by manipulating the solvent, substrate, and annealing conditions. Finally, guided by a wide topographical template, nearly defect-free directed self-assembly (DSA) lines with a resolution of 8 nm were achieved, highlighting its potential practical application in DSA lithography technology.

Sequential Brush Grafting for Chemically and Dimensionally Tolerant Directed Self-Assembly of Block Copolymers.

We report a method for the directed self-assembly (DSA) of block copolymers (BCPs) in which a first BCP film deploys homopolymer brushes, or "inks", that sequentially graft onto the substrate's surface via the interpenetration of polymer molecules during the thermal annealing of the polymer film on top of existing polymer brushes. By selecting polymer "inks" with the desired chemistry and appropriate relative molecular weights, it is possible to use brush interpenetration as a powerful technique to generate self-registered chemical contrast patterns at the same frequency as that of the domains of the BCP. The result is a process with a higher tolerance to dimensional and chemical imperfections in the guiding patterns, which we showcase by implementing DSA using homopolymer brushes for the guiding features as opposed to more robust cross-linkable mats. We find that the use of "inks" does not compromise the line width roughness, and the quality of the DSA as a lithographic mask is verified by implementing a robust "dry lift-off" pattern transfer.

Self-Registered Self-Assembly of Block Copolymers.

Directed self-assembly (DSA) of block copolymer (BCP) thin films, especially with density multiplication, is one of the most promising options for further improving resolution and throughput in nanolithography. However, controlling defect density has been one of the major hurdles for many DSA applications. Both thermodynamically and kinetically, defect-free patterns favor the use of low density multiplication factors and thinner films, which undermine the promise of enhanced resolution and the formation of robust masks for pattern transfer. Here, we demonstrate a self-registered self-assembly method to enable nearly perfect DSA on loosely defined chemical patterns with high density multiplication factor. Self-registered self-assembly involves two DSA steps. In the first step, an ultrathin BCP blend film is used to obtain vanishingly low defect densities. Concurrently as the film is annealed, preloaded chemical markers separate into the different polymer blocks and graft to the substrate locking in a new chemical contrast pattern with 1:1 feature registration. After thorough removal of the blend film, the remaining self-registered chemical pattern can establish defect-free DSA of thick BCP films.