Semiconductor device and manufacturing method thereof

摘要

A semiconductor device including a thin film transistor which includes an oxide semiconductor layer and has high electric characteristics and reliability. Film deposition is performed using an oxide semiconductor target containing an insulator (an insulating oxide, an insulating nitride, silicon oxynitride, aluminum oxynitride, or the like), typically SiO2, so that the semiconductor device in which the Si-element concentration in the thickness direction of the oxide semiconductor layer has a gradient which increases in accordance with an increase in a distance from a gate electrode is realized.

主权项

1. A semiconductor device comprising:
a gate electrode over an insulating surface; an insulating layer over the gate electrode; a first oxide semiconductor layer over the insulating layer, the first oxide semiconductor layer containing indium and zinc; a second oxide semiconductor layer over the first oxide semiconductor layer, the second oxide semiconductor layer containing indium, zinc, and silicon; a channel protective layer over and in contact with the second oxide semiconductor layer; and a source electrode and a drain electrode over the channel protective layer, the source electrode and the drain electrode being electrically connected to the second oxide semiconductor layer, wherein a concentration of silicon in the second oxide semiconductor layer is larger than a concentration of silicon in the first oxide semiconductor layer, and wherein crystallinity of the first oxide semiconductor layer is higher than crystallinity of the second oxide semiconductor layer.