The improvement in the reliability of a channel-etched fieldeffect transistor (FET) using a buried channel effect was achieved by stacking In-Ga-Zn-O (IGZO) films with different compositions.In addition, a liquid crystal display panel using an IGZO multilayer c-axis-aligned crystal FET for a backplane was fabricated.

A 13.3‐inch 8k4k OLED display using an oxide semiconductor with high‐mobility IGZO material was fabricated. It was found that the use of a higher mobility material can decrease the size and power consumption of a gate driver. Furthermore, a stack of such oxide semiconductor layers can increase process stability.

For unstable In-Ga-Zn-O (IGZO) thin films, electron-beam irradiation during transmission electron microscopy or heat treatment is reported to change the film structure and enhance its crystallization. Using IGZO films formed under two conditions, we study how the physical properties of IGZO films correlate with the electron-beam irradiation dose or heat-treatment temperature. IGZO films deposited under high deposition pressure contain many voids, have a relatively high impurity concentration, and are crystallized by electron-beam irradiation or heat treatment. In contrast, IGZO films formed under low deposition pressure are dense and the crystal size in the film does not change under electron-beam irradiation or heat treatment. In addition, heat treatment further increases the density of an originally dense film and reduces the defect density.

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