| abstract |
To provide a semiconductor device in which desorption of oxygen from side surfaces of an oxide semiconductor layer is prevented, defects (oxygen deficiency) in the oxide semiconductor layer are sufficiently reduced, and leakage current between a source and a drain is suppressed. The semiconductor device is manufactured through the following steps: after first heat treatment is performed on an oxide semiconductor film, the oxide semiconductor film is processed to form an oxide semiconductor layer; immediately after that, side walls of the oxide semiconductor layer are covered with an insulating oxide; and in second heat treatment, the side surfaces of the oxide semiconductor layer are prevented from being exposed to a vacuum and defects (oxygen deficiency) in the oxide semiconductor layer are reduced. Side walls of the oxide semiconductor layer are covered with sidewall insulating layers. The semiconductor device has a TGBC structure. |