Effect Of Fluorine In A Gate Insulator On The Reliability Of Indium-Gallium-Zinc Oxide Thin-Film Transistors

Reliability improvement mechanism using a fluorinated silicon nitride (SiNx:F) gate insulator (GI) was investigated. X-ray photoelectron spectroscopy analysis was performed focusing on bonding state of metals (In, Ga, Zn), in order to reveal the effect of fluorine in SiNx:F on bonding state at the interface between SiNx:F and a-InGaZnO. Our analysis clarified that the In-F-x and In-OF bonding states were formed at the a-InGaZnO/GI interface, leading to reducing the number of tail states near conduction band minimum. The behavior of time evolution of threshold voltage shift under positive-bias current stress (PBCS) was described by stretched-exponential equation. The result of PBCS assumed us that the a-InGaZnO TFTs with SiNx:F GI has fewer negatively charged deep trap and form more ordered interface with few tail state which originated in In was formed, leading to highly reliable a-InGaZnO TFT. (C) 2016 The Electrochemical Society. All rights reserved.