Ultrathin Atomic-Layer-Deposited In2O3 Radio-Frequency Transistors with Record High fT of 36 GHz and BEOL Compatibility

In this work, we report back-end-of-line (BEOL) compatible In
2
O
3
RF transistors with cut-off frequencies (f
T
) up to 36GHz, which is the highest among all metal oxide semiconductor channel RF transistors to date. Due to the outstanding transport properties and high scalability of In
2
O
3
, record-high f
T
value can be achieved with V
DS
at $0.8 \mathrm{~V}$ and V
GS
at −0.8 V on 2-nm thick, 40 nm-long channel devices. This work demonstrates the first ever BEOL oxide RF transistor with mm-Wave band operation frequency. In addition to improve the performance at Si CMOS clock frequencies for 3D integrated circuits (IC), it also offers the possibility for potential applications in future energy-efficient 6 G wireless communication devices.