SEMICONDUCTOR DEVICE AND SEMICONDUCTOR MEMORY DEVICE

Provided is a semiconductor device of the embodiment including: an oxide semiconductor layer; a gate electrode; a first electrode electrically connected to one portion of the oxide semiconductor layer, the first electrode including a first region, second region, a third region, and a fourth region, the first region disposed between the first portion and the second region, the first region disposed between the third region and the fourth region, the first region containing at least one element of In, Zn, Sn or Cd, and oxygen, the second region containing at least one metal element of Ti, Ta, W, or Ru, the third region and the fourth region containing the at least one metal element and oxygen, the third region and the fourth region having an atomic concentration of oxygen higher than that of the second region; and a second electrode electrically connected to another portion of the oxide semiconductor layer.