The Effects of a Thermal Recovery Process in In-Ga-Zn-O (IGZO) Thin Films Transistor

Abstract

In this paper, we demonstrated the effect of titanium (Ti) diffusion and modulation of interface traps by carrying out an annealing process on In-Ga-Zn-O (IGZO). The effect of diffused Ti atoms from the source/drain (S/D) electrodes was systematically investigated through secondary ion mass spectroscopy, X-ray photoelectron spectroscopy, HSC chemistry simulation, and electrical measurements. Higher concentrations of Ti and oxygen vacancies were observed with increasing annealing temperature. In addition, we demonstrated that the electrical stability of the IGZO thin films transistors (TFTs) was enhanced by a second thermal annealing process performed at temperature 50 degrees C lower than the first annealing step to diffuse Ti atoms in the lateral direction with minimal effects on the channel conductivity. As a result, we obtained a threshold voltage shift (Delta V-TH) of only 2.9 V after the first annealing step at 300 degrees C for 1 hour and a second annealing step at 250 degrees C for 3 hours with a channel length of 4 mu m.