Novel Self-aligned Passivation Process for Oxide TFTs utilizing Amorphous Gallium Oxide

Passivation of active layer plays a crucial role of improving the bias stabilities in amorphous oxide semiconductor thin-film transistors (TFTs), where several processing steps are necessary to form contact hole for drain and source (D/S). In this work, we propose a novel method of self-aligned D/S contact process utilizing amorphous gallium oxide (a-GaO
x
) layer as a passivation layer, which can be etched selectively by developers that enable self-alignment passivation. The TFTs show a high mobility exceeding 50 cm
²
V
^-1
s
^-1
, and threshold voltage shifts for NBS and PBS are −0.09Vand 0.15 V, respectively. It is concluded that the utilization of a-GaO
x
in oxide TFTs not only simplifies the TFT fabrication process but also improves the bias stabilities.