Semiconductor device with oxide semiconductor layer

摘要

An object is to provide a transistor including an oxide layer which includes Zn and does not include a rare metal such as In or Ga. Another object is to reduce an off current and stabilize electric characteristics in the transistor including an oxide layer which includes Zn. A transistor including an oxide layer including Zn is formed by stacking an oxide semiconductor layer including insulating oxide over an oxide layer so that the oxide layer is in contact with a source electrode layer or a drain electrode layer with the oxide semiconductor layer including insulating oxide interposed therebetween, whereby variation in the threshold voltage of the transistor can be reduced and electric characteristics can be stabilized.

主权项

1. A semiconductor device comprising:
a gate electrode layer; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer over the gate insulating layer; a source electrode layer and a drain electrode layer over the oxide semiconductor layer; and a layer comprising insulating oxide over the source electrode layer, the drain electrode layer and the oxide semiconductor layer, wherein the oxide semiconductor layer and the layer comprise Zn, wherein the layer is in contact with the oxide semiconductor layer at a portion between the source electrode layer and the drain electrode layer, and wherein the oxide semiconductor layer includes a region which is provided between the source electrode layer and the drain electrode layer and whose thickness is smaller than that of a region overlapping with the source electrode layer or the drain electrode layer.