| abstract |
An object is to provide a semiconductor device having a novel structure or a manufacturing method thereof. For example, an object is to improve the reliability of a transistor driven by a high voltage or a large current. In order to improve the reliability of a transistor, a buffer layer for reducing electric field concentration is provided between a drain electrode layer (or a source electrode layer) and an oxide semiconductor layer, and an end of the buffer layer is formed at a drain electrode. It has a cross-sectional shape protruding from the side surface of the layer (or source electrode layer). The buffer layer is formed of a single layer or a stack of a plurality of layers, and includes, for example, In-Ga-Zn containing nitrogen. An —O film, an In—Sn—O film containing nitrogen, an In—Sn—O film containing SiOx, or the like is used. [Selection diagram] Fig. 1 |