Semiconductor device and method for manufacturing the same

摘要

An object is to increase field effect mobility of a thin film transistor including an oxide semiconductor. Another object is to stabilize electrical characteristics of the thin film transistor. In a thin film transistor including an oxide semiconductor layer, a semiconductor layer or a conductive layer having higher electrical conductivity than the oxide semiconductor is formed over the oxide semiconductor layer, whereby field effect mobility of the thin film transistor can be increased. Further, by forming a semiconductor layer or a conductive layer having higher electrical conductivity than the oxide semiconductor between the oxide semiconductor layer and a protective insulating layer of the thin film transistor, change in composition or deterioration in film quality of the oxide semiconductor layer is prevented, so that electrical characteristics of the thin film transistor can be stabilized.

主权项

1. A semiconductor device comprising:
a first non-single crystalline oxide semiconductor layer comprising indium on an insulating surface, the first non-single crystalline oxide semiconductor layer having a first conductivity; a second non-single crystalline oxide semiconductor layer comprising indium over the first non-single crystalline oxide semiconductor layer, the second non-single crystalline oxide semiconductor layer having a second conductivity higher than the first conductivity; a gate electrode, wherein the gate electrode is overlapped with the first non-single crystalline oxide semiconductor layer and the second non-single crystalline oxide semiconductor layer; and an insulating film on the second non-single crystalline oxide semiconductor layer, wherein a concentration of sodium in the first non-single crystalline oxide semiconductor layer is 5×1019/cm3 or lower.