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

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.

Lithographically Defined Cross-Linkable Top Coats for Nanomanufacturing with High-χ Block Copolymers.

The directed self-assembly (DSA) of block copolymers (BCPs) is a powerful method for the manufacture of high-resolution features. Critical issues remain to be addressed for successful implementation of DSA, such as dewetting and controlled orientation of BCP domains through physicochemical manipulations at the BCP interfaces, and the spatial positioning and registration of the BCP features. Here, we introduce novel top-coat (TC) materials designed to undergo cross-linking reactions triggered by thermal or photoactivation processes. The cross-linked TC layer with adjusted composition induces a mechanical confinement of the BCP layer, suppressing its dewetting while promoting perpendicular orientation of BCP domains. The selection of areas of interest with perpendicular features is performed directly on the patternable TC layer via a lithography step and leverages attractive integration pathways for the generation of locally controlled BCP patterns and nanostructured BCP multilayers.

Pulsed transfer etching of PS-PDMS block copolymers self-assembled in 193 nm lithography stacks.

This work presents the graphoepitaxy of high-χ block copolymers (BCP) in standard industry-like lithography stacks and their transfer into the silicon substrate The process includes conventional 193 nm photolithography, directed self-assembly of polystyrene-block-polydimethylsiloxane (PS-b-PDMS) and pulsed plasma etching to transfer the obtained features into the substrate. PS-b-PDMS has a high Flory-Huggins interaction parameter (high-χ) and is capable of achieving sub-10 nm feature sizes. The photolithography stack is fabricated on 300 mm diameter silicon wafers and is composed of three layers: spin-on-carbon (SoC), silicon-containing anti-reflective coating (SiARC) and 193 nm photolithography resist. Sixty-nanometer-deep trenches are first patterned by plasma etching in the SiARC/SoC stack using the resist mask. The PS-b-PDMS is then spread on the substrate surface. Directed self-assembly (DSA) of the BCP is induced by a solvent vapor annealing process and PDMS cylinders parallel to the substrate surface are obtained. The surface chemistry based on SoC permits an efficient etching process into the underlying silicon substrate. The etching process is performed under dedicated pulsed plasma etching conditions. Fifteen nanometer half-pitch dense line/space features are obtained with a height up to 90 nm.