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

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.