Semiconductor device and manufacturing method thereof

摘要

In a semiconductor device, a region where a channel is formed is protected. In a semiconductor device, a region protecting a region where a channel is formed is provided in a semiconductor layer. In a semiconductor device, a layer protecting a region where a channel is formed is provided. In a semiconductor device, a region and/or a layer protecting a region where a channel is formed have/has a low density of defect states. In a semiconductor device, a region where a channel is formed has a low density of defect states.

主权项

1. A semiconductor device comprising:
an oxide semiconductor layer including 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; a gate insulating film in contact with the oxide semiconductor layer; and a gate electrode overlapping with the oxide semiconductor layer with the gate insulating film provided between the gate electrode and the oxide semiconductor layer, wherein a first energy gap of the first oxide semiconductor layer is greater than or equal to 2.7 eV and less than or equal to 4.9 eV, wherein a third energy gap of the third oxide semiconductor layer is larger than a second energy gap of the second oxide semiconductor layer and an energy is continuously changed in a vicinity of an interface between the second oxide semiconductor layer and the third oxide semiconductor layer in a band structure, and wherein the third oxide semiconductor layer has a thickness of less than 5 nm.