Semiconductor device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsShunpei YAMAZAKI, Takayuki ABE, Hideaki SHISHIDO
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Abstract
The threshold voltage is shifted in a negative or positive direction in some cases by an unspecified factor in a manufacturing process of the thin film transistor. If the amount of shift from 0 V is large, driving voltage is increased, which results in an increase in power consumption of a semiconductor device. Thus, a resin layer having good flatness is formed as a first protective insulating film covering the oxide semiconductor layer, and then a second protective insulating film is formed by a sputtering method or a plasma CVD method under a low power condition over the resin layer. Further, in order to adjust the threshold voltage to a desired value, gate electrodes are provided over and below an oxide semiconductor layer.
Claims30
A semiconductor device comprising:
- a first gate electrode over an insulating surface;
- a first insulating layer over the first gate electrode;
- an oxide semiconductor layer over the first insulating layer;
- a source electrode layer and a drain electrode layer over the oxide semiconductor layer;
- a resin layer which covers the source electrode layer and the drain electrode layer;
- and
- a second gate electrode over the resin layer,
- wherein the oxide semiconductor layer includes a region with a small thickness compared to a region of the oxide semiconductor layer which overlaps with the source electrode layer or the drain electrode layer, and
- wherein the resin layer is in contact with the region with the small thickness of the oxide semiconductor layer.
A semiconductor device comprising:
- a first gate electrode over an insulating surface;
- a first insulating layer over the first gate electrode;
- a source electrode layer and a drain electrode layer over the first insulating layer;
- an oxide semiconductor layer over the source electrode layer and the drain electrode layer;
- a resin layer which covers the oxide semiconductor layer;
- and
- a second gate electrode over the resin layer,
- wherein the oxide semiconductor layer is formed over the first insulating layer and overlaps with the first gate electrode,
- wherein at least a part of the oxide semiconductor layer is located between the source electrode layer and the drain electrode layer, and
- wherein the second gate electrode overlaps with the oxide semiconductor layer and the first gate electrode.
A semiconductor device comprising:
- a first gate electrode over an insulating surface;
- a first insulating layer over the first gate electrode;
- an oxide semiconductor layer over the first insulating layer;
- a channel protective layer over and in contact with the oxide semiconductor layer;
- a source electrode layer and a drain electrode layer over the oxide semiconductor layer;
- a resin layer which covers the source electrode layer and the drain electrode layer;
- a second gate electrode over the resin layer;
- and
- a second insulating layer over the resin layer,
- wherein the resin layer is in contact with the channel protective layer.
Dependencies are inferred from the claim text.