| abstract |
A semiconductor device comprising a first oxide semiconductor film, a second oxide semiconductor film on the first oxide semiconductor film, a source electrode in contact with the second oxide semiconductor film, a drain electrode in contact with the second oxide semiconductor film, A source electrode, and a metal oxide film on the drain electrode, a gate insulating film on the metal oxide film, and a gate electrode on the gate insulating film. The metal oxide film contains M ( M represents Ti, Ga, Y, Zr, La, Ce, Nd or Hf) and Zn. The metal oxide film includes a portion where x / ( x + y ) is greater than 0.67 and not greater than 0.99 when the atomic ratio of the target is M : Zn = x : y . |