Patent ID: 9209256
Filing Date: 2015-12-08
Classification: G02F,H01L

Abstract:
1. A semiconductor device comprising: an insulating film over a conductive film; and an oxide semiconductor film over the insulating film, wherein the oxide semiconductor film includes a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer, wherein an energy level of a bottom of a conduction band of the second oxide semiconductor layer is lower than an energy level of a bottom of a conduction band of the first oxide semiconductor layer and an energy level of a bottom of a conduction band of the third oxide semiconductor layer, and wherein an end portion of the second oxide semiconductor layer is positioned on an inner side than an end portion of the first oxide semiconductor layer and a distance between the end portion of the second oxide semiconductor layer and the end portion of the first oxide semiconductor layer is longer than or equal to the sum of thicknesses of the second oxide semiconductor layer and the third oxide semiconductor layer.