Overcoming the mobility–reliability trade-off in BEOL-compatible In2O3-based FETs through synergistic doping and prolonged annealing

Oxide semiconductors field-effect transistors (OS FETs) capable of simultaneously delivering high mobility and excellent reliability are a key platform for high-performance circuits and memory modules in monolithic three-dimensional integrated circuits (M3D ICs). In this work, we propose a synergistic strategy combining Zn doping and prolonged thermal annealing (PTA) to address the mobility–reliability trade-off in InZnOX FETs. The Zn doping ratio was controlled by adjusting the precursor-cycle ratio during atomic layer deposition. Zn incorporation suppresses channel crystallization during PTA, allowing the InZnOX channel to retain its amorphous structure. The results indicate that Zn doping effectively suppresses the hydrogen-related negative threshold-voltage shift (ΔVTH) and improves device reliability, while PTA mitigates the mobility degradation induced by doping and further enhances bias-stress stability. In particular, all PTA-treated InZnOX FETs exhibit mobilities exceeding 80 cm2 V−1 s−1, outperforming the InZnOX FETs without PTA. For PTA-treated devices with an In:Zn ratio of 22:1, a |ΔVTH| of only 11 mV after 1000 s of stress is achieved at 360 K under a gate-overdrive voltage of 4 V. These results demonstrate a feasible approach for realizing OS FETs with enhanced performance, robust reliability, and back-end-of-line-compatible processing for future applications in M3D ICs.