Semiconductor device and manufacturing method thereof

摘要

An object is to provide a transistor in which the state of an interface between an oxide semiconductor layer and an insulating film (gate insulating layer) in contact with the oxide semiconductor layer is favorable; and a method for manufacturing the transistor. In order to obtain the transistor, nitrogen is added to a region of the oxide semiconductor layer in the vicinity of the interface with the gate insulating layer. Specifically, a concentration gradient of nitrogen is formed in the oxide semiconductor layer, and a region containing much nitrogen is provided at the interface with the gate insulating layer. By the addition of nitrogen, a region with high crystallinity can be formed in the region of the oxide semiconductor layer in the vicinity of the interface with the gate insulating layer, so that a stable interface state can be obtained.

主权项

1. A semiconductor device comprising:
a substrate; a base insulating layer over the substrate; an oxide semiconductor layer over the base insulating layer; a gate insulating layer over the oxide semiconductor layer; and a gate electrode layer over the gate insulating layer; wherein the oxide semiconductor layer has a concentration gradient of nitrogen, which becomes higher as closer to the gate insulating layer, and has a concentration gradient of oxygen, which becomes higher as closer to the base insulating layer.