Remarkable Bias-Stress Stability of Ultrathin Atomic-Layer-Deposited Indium Oxide Thin-Film Transistors Enabled by Plasma Fluorination

A low-thermal-budget fabrication approach is developed to realize high-performance fluorine-doped indium oxide (In2O3:F) thin-film transistors (TFTs) with remarkable bias-stress stability. The ultrathin transistor channel layer is prepared by a re-developed atomic layer deposition (ALD) process of using cyclopentadienyl indium(I) (InCp) and O-2 plasma to deposit a crystalline In2O3 film, followed by a new fluorine doping strategy to use CF4 plasma to afford the In2O3:F layer. As revealed by the density functional theory (DFT) analysis, the fluorine doping can stabilize the lattice oxygen and electrically passivate the problematic V-O defects in In2O3 by forming the FOFi spectator defects. Therefore, the fabricated In2O3:F TFTs show simultaneously excellent electrical performance and remarkable bias-stress stability, with high mu (FE) of 35.9 cm(2) V-1 s(-1), positive V-th of 0.36 V, steep SS of 94.3 mV dec(-1), small hysteresis of 33 mV, and small Delta V-th of -111 and 49 mV under NBS and PBS, respectively. This work demonstrates the high promise of the fluorinated ALD In2O3:F TFTs for the CMOS back-end-of-line (BEOL) compatible technologies toward advanced monolithic 3D integration.