Designing buried-gate InGaZnO transistors for high-yield and reliable switching characteristics

Abstract

The indium–gallium–zinc-oxide (IGZO) transistor has consistently encountered reliability issues and has intrinsic material limitations that limit its electrical performance. In this study, we demonstrate a device concept containing a buried back gate in the IGZO transistor that offers a practical solution, enhancing device reliability and significantly improving transistor performance. Buried-gate transistors that apply a uniform gating field effect to the effective channel region outperform control-gate transistor devices with respect to the on-current, hysteresis window, subthreshold swing, and μ_FE. The device yield is also substantially increased (∼81% even higher than ∼54% of the control device) by mitigating the non-uniform gating field effect arising from the protruding gate structure of the control device. Furthermore, the reduced series resistance and decreased interface trap density of the buried-gate transistor substantiate the geometrical optimization of the original transistor device with intrinsically bending stacked-layers (IGZO/A₂O₃). These results provide a feasible approach for enhancing the reliability and electrical properties of oxide thin film transistors, potentially paving a way toward the development of a highly reliable transistor for commercial gadgets.