The impact of SiNx gate insulators on amorphous indium-gallium-zinc oxide thin film transistors under bias-temperature-illumination stress

Abstract

The threshold voltage instability $\left({\text{V}}_{\text{th}}\right)$ in indium-gallium-zinc oxide thin film transistor was investigated with disparate ${\text{SiN}}_{\text{x}}$ gate insulators under bias-temperature-illumination stress. As ${\text{SiN}}_{\text{x}}$ film stress became more tensile, the negative shift in ${\text{V}}_{\text{th}}$ decreased significantly from −14.34 to −6.37 V. The compressive films exhibit a nitrogen-rich phase, higher hydrogen contents, and higher N–H bonds than tensile films. This suggests that the higher N–H related traps may play a dominant role in the degradation of the devices, which may provide and/or generate charge trapping sites in interfaces and/or ${\text{SiN}}_{\text{x}}$ insulators. It is anticipated that the appropriate optimization of gate insulator properties will help to improve device reliability.