Surrounding Gate Vertical-Channel FET with Gate Length of 40 nm using BEOL Compatible High-Thermal-Tolerance In-Al-Zn Oxide Channel

We have demonstrated, for the first time, a surrounding gate vertical-channel FET with gate length of 40 nm by introducing back-end-of-line (BEOL) process compatible novel oxide semiconductor (OS) In-Al-Zn-O as a channel material. Fabricated FETs exhibited high scalability by excellent thermal stability (~420°C) compared to conventional In-Ga-Zn-O-channel FETs, with high mobility (12.7 cm ² /Vs) characteristics. Furthermore, the vertical-channel FET also exhibited excellent reliability and stable operation without floating body effect. Endurance of over 1011 cycles was also demonstrated. Our work opens a pathway to realization of high-performance BEOL transistor for 3D-LSI applications.