High-pressure Gas Activation for Amorphous Indium-Gallium-Zinc-Oxide Thin-Film Transistors at 100 degrees C

Abstract

We investigated the use of high-pressure gases as an activation energy source for amorphous indiumgallium- zinc-oxide (a-IGZO) thin film transistors (TFTs). High-pressure annealing (HPA) in nitrogen (N-2) and oxygen (O-2) gases was applied to activate a-IGZO TFTs at 100 degrees C at pressures in the range from 0.5 to 4 MPa. Activation of the a-IGZO TFTs during HPA is attributed to the effect of the high-pressure environment, so that the activation energy is supplied from the kinetic energy of the gas molecules. We reduced the activation temperature from 300 degrees C to 100 degrees C via the use of HPA. The electrical characteristics of a-IGZO TFTs annealed in O-2 at 2 MPa were superior to those annealed in N-2 at 4 MPa, despite the lower pressure. For O-2 HPA under 2 MPa at 100 degrees C, the field effect mobility and the threshold voltage shift under positive bias stress were improved by 9.00 to 10.58 cm(2)/V.s and 3.89 to 2.64 V, respectively. This is attributed to not only the effects of the pressurizing effect but also the metal-oxide construction effect which assists to facilitate the formation of channel layer and reduces oxygen vacancies, served as electron trap sites.