Indium-Gallium-Zinc-Oxide (IGZO) Nanowire Transistors

Abstract

We report high-performance amorphous Indium-Gallium-Zinc-Oxide nanowire field-effect transistors ( $\alpha $ -IGZO NW-FETs) featuring an ultrascaled nanowire width ( ${W}_{{\mathrm {NW}}}$ ) down to ~20 nm. The device with 100 nm channel length ( ${L}_{{\mathrm {CH}}}$ ) and ~25 nm ${W}_{{\mathrm {NW}}}$ achieves a decent subthreshold swing (SS) of 80 mV/dec as well as high peak extrinsic transconductance ( ${G}_{m,{\mathrm {ext}}}$ ) of $612~\mu S/\mu \text{m}$ at a drain–source voltage ( ${V}_{{\mathrm {DS}}}$ ) = 2 V ( $456~\mu S/\mu \text{m}$ at ${V}_{{\mathrm {DS}}}$ = 1 V). The good electrical properties are enabled by using an ultrascaled 5 nm high- ${k}$ HfO ₂ as the gate dielectric, a water-free ozone-based atomic layer deposition (ALD) process, and a novel digital etch (DE) technique developed for indium-gallium-zinc-oxide (IGZO) material. By using low-power BCl ₃ -based plasma treatment and isopropyl alcohol (IPA) rinse in an alternating way, the DE process is able to realize a cycle-by-cycle etch with an etching rate of ~1.5 nm/cycle. The scaling effects on device performance have been analyzed as well. It shows that the downscaling of ${W}_{{\mathrm {NW}}}$ improves the SS notably without sacrificing ON-state performance, and the shrinking of ${L}_{{\mathrm {CH}}}$ boosts the ${G}_{m,{\mathrm {ext}}}$ . The ultrascaled $\alpha $ -IGZO NW-FETs could play an important role in applications where high performance and high density are highly desired.