Semiconductor device and method for manufacturing the same

摘要

A transistor in which the state of an interface between an oxide semiconductor layer and an insulating film in contact with the oxide semiconductor layer is favorable and a method for manufacturing the transistor are provided. Nitrogen is added to the vicinity of the interface between the oxide semiconductor layer and the insulating film (gate insulating layer) in contact with the oxide semiconductor layer so that the state of the interface of the oxide semiconductor layer becomes favorable. Specifically, the oxide semiconductor layer has a concentration gradient of nitrogen, and a region containing much nitrogen is provided at the interface with the gate insulating layer. A region having high crystallinity can be formed in the vicinity of the interface with the oxide semiconductor layer by addition of nitrogen, whereby the interface state can be stable.

主权项

1. A semiconductor device comprising:
an oxide semiconductor layer over an insulating layer; a source electrode layer and a drain electrode layer over and in contact with the oxide semiconductor layer; a gate insulating layer over and in contact with the oxide semiconductor layer and over the source electrode layer and the drain electrode layer; a gate electrode layer over the gate insulating layer; wherein the oxide semiconductor layer has a peak of a nitrogen concentration at an interface with the gate insulating layer, and wherein the gate insulating layer contains nitrogen and has a peak of a nitrogen concentration at an interface with the oxide semiconductor layer.