| abstract |
A semiconductor device includes a transistor which includes a first gate electrode, a first insulating film, an oxide semiconductor film, source and drain electrodes, a second insulating film, and a second gate electrode. The oxide semiconductor film includes a first oxide semiconductor film in contact with the first insulating film, a second oxide semiconductor film in contact with the first oxide semiconductor film, and a third oxide semiconductor film in contact with the second oxide semiconductor film. The first to third oxide semiconductor films each contain In, Zn, and M (M represents Al, Ga, Y, or Sn). The third oxide semiconductor film includes a region in contact with a side surface of the second oxide semiconductor film and a region in contact with the second insulating film. The third oxide semiconductor film includes a region where the content of M is greater than or equal to that of In. |