abstract |
(57) [PROBLEMS] To improve TFT characteristics in a thin film transistor having a transparent semiconductor film. A gate insulating film including a first insulating film and a second insulating film is formed on a gate electrode. The semiconductor layer 5 using ZnO or the like is formed on the insulating film 4b. The first insulating film 4a is formed of SiN x or the like having high insulating properties, while the second insulating film 4b is formed of an oxide (for example, SiO 2). 2 ) formed by With this structure, the second insulating film 4 It is possible to improve the crystallinity of the semiconductor layer 5 forming an interface with b and to reduce the defect level at the interface between the semiconductor layer and the second insulating film. In addition, when the second insulating film is formed using an oxide, it is possible to prevent oxygen from being deprived of the semiconductor layer by the material of the second insulating film. Therefore, the crystallinity near the interface between the semiconductor layer and the second insulating film is favorably maintained. As a result, it is possible to realize a thin film transistor having a low leakage current level in an off region and a high mobility and good switching characteristics. |