High Energy Photon Induced Defect Engineering in Ultra‐Thin Indium Oxide Transistors for BEOL‐Compatible Logic Circuits

As oxide semiconductors are increasingly considered for BEOL (Back‐End‐of‐Line)‐Compatible logic applications, aggressive channel scaling is required to improve electrostatic control and mitigate short‐channel effects. However, realizing ultrathin oxide channels with high uniformity and controllable electrical characteristics remains challenging, particularly under a limited thermal budget. In this work, we fabricated 1‐nm‐thick In 2 O 3 thin‐film transistors using atomic layer deposition at 150°C and subsequently tuned their electrical properties by xenon flash lamp annealing (XFLA). The XFLA treatment systematically shifted the threshold voltage in the negative direction while improving switching stability and device uniformity. Optimized devices exhibited reduced hysteresis from 1.5 to 0.76 V and improved positive‐bias‐stress stability, with the threshold‐voltage shift decreasing from 4.4 to 2.1 V after 3600 s. X‐ray photoelectron spectroscopy revealed an increase in the oxygen‐vacancy‐related component from 28.4% to 33.8% after XFLA, indicating that high‐energy photon irradiation effectively modulates defect states in the ultrathin In 2 O 3 channel. Finally, by combining pristine and XFLA‐treated transistors, we demonstrated NMOS inverter operation at both 5 and 40 V, achieving a maximum voltage gain of 30. These results suggest that high‐energy‐photon‐induced defect engineering provides an effective route for threshold‐voltage control and circuit implementation in ultrathin oxide transistors for BEOL‐Compatible logic applications.