高密度サブ10nmシリコンナノワイヤの、複数の用途に向けた指向性自己組織化および逐次浸潤合成の相乗的パターニングによる作製

This study presents a synergistic patterning technique integrating directed self-assembly lithography (DSA) and sequential infiltration synthesis (SIS) to fabricate silicon nanowires with small critical dimension, high aspect ratios, and high density on silicon-on-insulator (SOI) substrates. Through optimization of polystyrene-block-poly(methyl methacrylate) (PS-b-PMMA) guiding templates and SIS cycles, polymer templates were in situ converted into aluminum oxide (Al₂O₃) hard masks with high etching selectivity. Coupled with a single-layer silicon dioxide (SiO₂) intermediate mask strategy, this approach significantly simplifies the device fabrication workflow while leveraging the flexibility of SiO₂ etching to achieve progressive scaling of silicon nanowires. Focused ion beam-transmission electron microscopy (FIB-TEM) characterization confirmed nanowire profiles with a top width of ∼6.6 nm, bottom width of ∼14.9 nm, pitch of 28 nm, and height of ∼53.5 nm, which are further used in multiple applications. The exposed sub-10 nm silicon nanowire channels exhibited ultrasensitive gas-sensing capabilities, demonstrating a 49.8% response to 2.5 ppm ammonia (NH₃), significantly outperforming conventional NH₃ sensors. The silicon nanowire was further combined with a high-k/metal gate process to demonstrate its application in fin field-effect transistors (FinFETs). The device shows a switching ratio exceeding 10⁷ and a subthreshold swing as low as 69.59 mV/dec, demonstrating exceptional electrostatic control of the Fin channel fabricated by the DSA-SIS process. This work not only provides a cost-effective manufacturing solution of high-density silicon nanowires but also demonstrates the application potential of DSA-SIS technology in semiconductor devices with a nanostructure for both sensing and integrated circuit operations.