Patent ID: 8704219

Claim:
A semiconductor device comprising: a gate electrode; a gate insulating film which covers the gate electrode; a semiconductor film comprising an oxide semiconductor, wherein a region of the semiconductor film overlaps with the gate electrode; a source electrode and a drain electrode which are in contact with the semiconductor film; a metal oxide film which is in contact with the semiconductor film and covers the source electrode and the drain electrode; an insulating film which covers the metal oxide film; a conductive film over the insulating film, wherein the conductive film overlaps with the region of the semiconductor film; a liquid crystal element comprising a pixel electrode, wherein the pixel electrode is electrically connected to one of the source electrode and the drain electrode; and a storage capacitor, wherein a hydrogen concentration of the semiconductor film is less than or equal to 5×10 18 atoms/cm 3 , and wherein a thickness of the metal oxide film is larger than a thickness of the semiconductor film, and wherein a capacitance of the storage capacitor is equal to or less than one third of a capacitance of the liquid crystal element.