Nb Doped TiO2 Protected Back-Channel-Etched Amorphous InGaZnO Thin Film Transistors

A new back-channel-etched process for the fabrication of amorphous InGaZnO (a-IGZO) thin film transistors (TFTs) is demonstrated, in which a conductive Nb doped TiO
₂
(TNO) thin film is used to serve as protective layer for the a-IGZO active layer. It is shown that the TNO film provides the active layer with excellent protection even when the thickness is only 1 nm. With treatment by N
₂
O plasma +200°C annealing, the conductive TNO can be converted into an insulator to serve as an in situ passivation layer. Besides, by the introduction of the TNO layer, the source-drain parasitic resistance of the BCE process fabricated TFTs is significantly reduced and the positive bias stress stability is improved as well.