Crystalline Oxide Semiconductor Using CAAC-IGZO and its Application

It is revealed that c-axis aligned crystal In-Ga-Zn oxide(CAAC-IGZO) and nanocrystalline IGZO films are suitable for practical use due to their high-density crystalline morphologies and stability under electron beam irradiation in transmission electron microscope observation. We attempted to reproduce an amorphous IGZO film with no ordering. However, we found nanocrystals in the film and this film has low density and is soft, so that it is an unstable material in which crystals grow when subjected to electron beam irradiation in TEM observation. We fabricated field-effect transistors using CAAC-IGZO and examined their switching characteristics. As a result of microfabrication scaling, cutoff frequencies of 2 GHz and 1.5 GHz were obtained when the channel lengths were 60 nm and 100 nm, respectively. This opens new possibilities for oxide semiconductor large-scale integration.