Improving Reliability of a-InGaZnO TFTs With Optimal Location of Al2O3 Passivation in Moist Environment

In this study, the influence of amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) with different passivation (PV) layers under positive bias stress (PBS) in a moist environment and hot-carrier stress (HCS) is investigated. The Al2O3-passivated device can effectively suppress H2O molecule absorption, but the HCS reliability is inferior. The degradation behavior is attributed to the high permittivity of Al2O3, which lacks oxygen, and the oxygen from the etch stop layer (ESL) diffuses into the Al2O3 film during the process, causing the generation of oxygen vacancies in the ESL. Therefore, an optimal outer Al2O3-passivated device is proposed, in which the Al2O3 film is deposited away from the ESL. With this optimal PV structure, both the results under PBS in a moist environment and HCS can achieve good stability in the outer Al2O3-passivated device.

Automated summary

This study investigates the influence of different passivation layers on amorphous indium-gallium-zinc oxide (a-IGZO) thin-film transistors (TFTs) under positive bias stress (PBS) in a moist environment and hot-carrier stress (HCS). It is found that the Al2O3-passivated device effectively suppresses water absorption but has inferior HCS reliability. This degradation behavior is attributed to the high permittivity of Al2O3 and the diffusion of oxygen from the etch stop layer (ESL), which results in the generation of oxygen vacancies in the Al2O3 film.