Patent ID: 9190525
Filing Date: 2015-11-17
Classification: H01L

Abstract:
1. A semiconductor device comprising: a first insulating layer over an insulating surface; a first oxide semiconductor layer over the first insulating layer; a second oxide semiconductor layer over the first oxide semiconductor layer; a third oxide semiconductor layer over the second oxide semiconductor layer; a first electrode layer and a second electrode layer over the third oxide semiconductor layer; and a second insulating layer over the third oxide semiconductor layer, wherein the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer comprise same constituent elements, wherein a composition of the second oxide semiconductor layer is different from a composition of the first oxide semiconductor layer and a composition of the third oxide semiconductor layer, and wherein an energy level of a bottom of a conductive band of the first oxide semiconductor layer is continuously changed to an energy level of a bottom of a conductive band of the second oxide semiconductor layer at an interface between the second oxide semiconductor layer and the first oxide semiconductor layer.