Top-Gate Short Channel Amorphous Indium-Gallium-Zinc-Oxide Thin Film Transistors with Sub-1.2 nm Equivalent Oxide Thickness

We report high performance top-gate amorphous Indium-Gallium-Zinc-Oxide thin film transistors (alpha-IGZO TFTs) featuring the smallest equivalent oxide thickness (EOT) of sub-1.2 nm among all IGZO-channel TFTs, achieving the highest extrinsic peak transconductance (G(m,ext)) of 62 mu S/mu m at a drain to source voltage (V-DS) = 2 V (33.4 mu S/mu m at V-DS = 1 V) and excellent drain induced barrier lowering (DIBL) of 17.6 mV/V, for a device with a channel length (L-CH) of 160 nm. The best long channel device has a subthreshold swing (SS) of 67.5 mV/decade. This was enabled by using an ultra-scaled 5 nm high-k HfO2 as the gate dielectric. In addition, temperature study was also performed on alpha-IGZO TFTs. Field effect mobility (mu(eff)) show negligible degradation at high temperature, indicating the great potential of alpha-IGZO TFTs for various emerging applications.