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-NW) down to similar to 20 nm. The device with 100 nm channel length (L-CH) and similar to 25 nm W-NW achieves a decent subthreshold swing (SS) of 80 mV/dec as well as high peak extrinsic transconductance (G(m,ext)) of 612 mu S/mu m at a drain-source voltage (V-DS) = 2 V (456 mu S/mu m at V-DS = 1 V). The good electrical properties are enabled by using an ultrascaled 5 nm high-k HfO2 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 BCl3-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 similar to 1.5 nm/cycle. The scaling effects on device performance have been analyzed as well. It shows that the downscaling of W-NW improves the SS notably without sacrificing ON-state performance, and the shrinking of L-CH boosts the Gm, ext. The ultrascaled alpha-IGZO NW-FETs could play an important role in applications where high performance and high density are highly desired.