| abstract |
A transistor including an oxide semiconductor film having normally-off electrical characteristics and high on-state current is provided. In addition, a semiconductor device capable of high-speed operation using the transistor is provided. A base insulating film, an oxide semiconductor film provided over the base insulating film, a gate insulating film provided over the oxide semiconductor film, and the oxide semiconductor film overlap with each other with the gate insulating film interposed therebetween. A gate electrode provided to cover at least the gate electrode, an interlayer insulating film having an opening, and a wiring provided over the interlayer insulating film and in contact with the oxide semiconductor film through the opening. The semiconductor device includes a buffer layer provided on the insulating film and the insulating film between the base insulating film and the oxide semiconductor film at least in a region where the oxide semiconductor film and the wiring are in contact with each other. [Selection] Figure 1 |