This study proposes a collaborative patterning technique that combines directional self-assembly lithography (DSA) and sequential infiltration synthesis (SIS) to fabricate silicon nanowires with small critical dimensions, high aspect ratios, and high density on silicon insulator (SOI) substrates. By optimizing the PS-b-PMMA guiding template and the SIS cycle, the polymer template is in situ converted into an aluminum oxide (AlO23) hard mask with high etching selectivity. Combined with a single-layer silicon dioxide (SiO2) intermediate mask strategy, this method significantly simplifies the device manufacturing process while utilizing the flexibility of SiO2 etching to achieve the progressive expansion of silicon nanowires. Focused ion beam transmission electron microscopy (FIB-TEM) characterization confirmed that the top width of the nanowires is approximately 6.6 nanometers, the bottom width is approximately 14.9 nanometers, the spacing is approximately 28 nanometers, and the height is approximately 53.5 nanometers. These wire materials are widely used in various applications. The exposed 10-nanometer silicon nanowire channels exhibit ultra-sensitive gas sensing capabilities, with a response rate of 49.83% for 2.5 ppm ammonia (NH), significantly superior to traditional NH3 sensors. The silicon nanowires are further combined with high k/metal gate processes, demonstrating their application in fin-shaped field-effect transistors (FinFETs). The device shows a switch ratio exceeding 10^7, an off-state swing as low as 69.59 mV/dec, and demonstrates the excellent electrostatic control of the Fin channel fabricated by the DSA-SIS process. This work not only provides a cost-effective manufacturing solution for high-density silicon nanowires but also demonstrates the potential of the DSA-SIS technology in sensing and integrated circuits with nanostructures. This research was published in ACS Nano under the title "High-Density Sub-10 nm Silicon Nanowires Fabricated via Directed Self-Assembly and Sequential Infiltration Synthesis Synergistic Patterning for Multiple Applications".
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DOI: 10.1021/acsnano.5c16910