| abstract |
In a transistor including an oxide semiconductor, reliability is improved by suppressing variation in electrical characteristics. A semiconductor device including a transistor includes a first oxide semiconductor film over a first insulating film, a gate insulating film over the first oxide semiconductor film, and a gate insulating film. A second oxide semiconductor film, a first oxide semiconductor film, and a second insulating film over the second oxide semiconductor film. The first oxide semiconductor film includes a gate insulating film. A channel region in contact with the film, a source region in contact with the second insulating film, and a drain region in contact with the second insulating film, The second oxide semiconductor film has a carrier density higher than that of the first oxide semiconductor film. [Selection] Figure 1 |