Dry-Etching Processes for High-Aspect-Ratio Features with Sub-10 nm Resolution High‑χ Block Copolymers

• Published in: ACS applied materials & interfaces 2021-10, Vol.13 (41), p.49184-49193
• Main Authors: Pound-Lana, Gwenaelle, Bézard, Philippe, Petit-Etienne, Camille, Cavalaglio, Sébastien, Cunge, Gilles, Cabannes-Boué, Benjamin, Fleury, Guillaume, Chevalier, Xavier, Zelsmann, Marc
• Format: Article
• Language: English
• Subjects: Condensed Matter; Engineering Sciences; Functional Nanostructured Materials (including low-D carbon); Physics; Plasmas; Soft Condensed Matter
• ISSN: 1944-8244; 1944-8252
• DOI: 10.1021/acsami.1c13503

Directed self-assembly of block copolymers (BCP) is a very attractive technique for the realization of functional nanostructures at high resolution. In this work, we developed full dry-etching strategies for BCP nanolithography using an 18 nm pitch lamellar silicon-containing block copolymer. Both an oxidizing Ar/O2 plasma and a nonoxidizing H2/N2 plasma are used to remove the topcoat material of our BCP stack and reveal the perpendicular lamellae. Under Ar/O2 plasma, an interfacial layer stops the etch process at the topcoat/BCP interface, which provides an etch-stop but also requires an additional CF4-based breakthrough plasma for further etching. This interfacial layer is not present in H2/N2. Increasing the H2/N2 ratio leads to more profound modifications of the silicon-containing lamellae, for which a chemistry in He/N2/O2 rather than Ar/O2 plasma produces a smoother and more regular lithographic mask. Finally, these features are successfully transferred into silicon, silicon-on-insulator, and silicon nitride substrates. This work highlights the performance of a silicon-containing block copolymer at 18 nm pitch to pattern relevant hard-mask materials for various applications, including microelectronics.