Stability enhancement of top-gate self-aligned tin-doped indium gallium oxide thin film transistor by low temperature annealing

Top-gate self-aligned IGTO TFTs were used as an example to study the contradiction of uniformity and PBTS stability when developing TFT with high mobility. High intrinsic carrier concentration restricted the tuning of SiO2 deposition. To ensure the uniformity, relatively higher power was employed for GI deposition to reduce donor-type oxygen vacancies. Deep electron traps formed by excess oxygen lead to poor PBTS stability. The PBTS stability was improved without deterioration of uniformity by introducing low temperature (200 °C) annealing, to control hydrogen diffusion from ILD layer which would passivate the electron traps.