| 摘要 |
The electric characteristics of a semiconductor device including an oxide semiconductor change by irradiation with visible light or ultraviolet light. In view of the above problem, one object is to provide a semiconductor device including an oxide semiconductor film, which has stable electric characteristics and high reliability. Over an oxide insulating layer, a first oxide semiconductor layer is formed to a thickness greater than or equal to 1 nm and less than or equal to 10 nm and crystallized by heat treatment, so that a first crystalline oxide semiconductor layer is formed. A second crystalline oxide semiconductor layer with a greater thickness than the first crystalline oxide semiconductor layer is formed thereover.
|
