A study on H-2 plasma treatment effect on a-IGZO thin film transistor

Abstract

We report the effect of H-2 plasma treatment on amorphous indium-gallium-zinc-oxide (a-IGZO) thin-film transistor (TFT). The changes in electrical characteristics and stability of the a-IGZO TFT treated by H-2 plasma were evaluated under thermal stress. Each device exhibited a change in the subthreshold swing, turn on voltage shift, and hysteresis depending on the amount of hydrogen atom. It was found that there occurred a decrease of oxygen deficiency and an increase of hydrogen content in channel layer and channel/dielectric interface with increasing treatment time. The proper hydrogen dose well passivated the oxygen vacancies; however, more hydrogen dose acted as excessive donors. The change of oxygen vacancy and total trap charge were explained by the activation energy from Arrhenius plot. Through this study, we found that the optimized H-2 plasma treatment brings device stability by affecting oxygen vacancy and trap content in channel bulk and channel/dielectric interface.