BEOL Three-Dimensional\nStackable Oxide Semiconductor\nCMOS Inverter with a High Voltage Gain of 233 at Cryogenic Temperatures

Targeting high-performance computing at cryogenic temperatures,\nwe report back-end-of-line (BEOL)-compatible p-type Te-TeO<sub><i>x</i></sub> field effect transistors (FETs) deposited using\na sputtering method that is cost-effective, large-scale manufacturable,\nand highly controllable. Combined with the indium tin oxide channel\nn-FETs employing a common gate and HfO<sub>2</sub> gate dielectric,\nBEOL three-dimensional stackable oxide semiconductor complementary\nmetal oxide semiconductor (CMOS) inverters were further realized,\ndemonstrating excellent threshold voltage matching, with a high voltage\ngain of 132 with a 2 V supply voltage (<i>V</i><sub>DD</sub>) at room temperature. At cryogenic temperatures, the CMOS inverter\nexhibits significantly enhanced performance, achieving a voltage gain\nof 233 at a <i>V</i><sub>DD</sub> of 2 V with a wide noise\nmargin of 86%. Even at an ultralow <i>V</i><sub>DD</sub> of 0.5 V, the CMOS inverter maintains solid performance with an\nexceptionally low power consumption of <60 pW.