With the increasing of the size and the high definition of the Liquid Crystal Display, LCD the thin film transistor, TFT with a larger electron mobility has been emerging and show great market prospect. Currently, the Indium Gallium Zinc Oxide, IGZO has been adapted to form amorphous oxide semiconductor, AOS layer of the TFT, also known as IGZO semiconductor pattern layer or channel. Since IGZO is a material extremely sensitive to water and oxygen, the water molecules and oxygen molecules in the LCD working environment can easily affect its electrical properties, so in order to improve the electrical stability of the TFT channel, a protective layer is needed to form on the channel.
The conventional material of the protective layer is typically of silicon oxide SiO2, silicon nitride Si3N4, and usually formed by plasma enhanced chemical vapor deposition (PECVD), atomic layer epitaxy (ALD and magnetron sputtering, etc. in the system. However, the chemical vapor deposition method is easy to incorporate impurity hydrogen atom into the channel, the channel will not only be damaged, but also affect the electrical properties of the channel; the quality of the protective layer prepared by magnetron sputtering is poor and the stability of the channel protection is poor; the process of the atomic layer epitaxy is complex, time-consuming, and therefore not conducive to industrialization.