A ${c}$ -Axis-Aligned Crystalline In-Ga-Zn Oxide FET With a Gate Length of 21 nm Suitable for Memory Applications

We fabricated a field-effect transistor (FET) with a gate length of 21 nm whose channel material is a ${c}$ -axis-aligned crystalline In-Ga-Zn oxide (CAAC-IGZO). A CAAC-IGZO FET with a gate length of 21 nm has an extremely low off-state leakage current, a practical driving capability, and tolerance against high temperatures. CAAC-IGZO FETs enable low-power integrated circuits, such as logic and memory in high-temperature environments. Performance estimation of a memory cell using the CAAC-IGZO FET with a gate length of 21 nm revealed that a write time of less than 1 ns and a data retention time of more than 1 h would be possible at 85 °C.