Semiconductor device, display device, and electronic appliance
First Claim
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 first oxide insulating layer in contact with part of the oxide semiconductor layer; and
a source electrode layer and a drain electrode layer in contact with part of the oxide semiconductor layer,wherein a region of the oxide semiconductor layer located directly underneath a gap between the source electrode and the first oxide insulating layer, and a region of the oxide semiconductor layer located directly underneath a gap between the drain electrode and the first oxide insulating layer, each has a thickness less than a region overlapping with the source electrode layer, a region overlapping with the first oxide insulating layer, and a region overlapping with the drain electrode layer.
1 Assignment
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Accused Products
Abstract
In a channel protected thin film transistor in which a channel formation region is formed using an oxide semiconductor, an oxide semiconductor layer which is dehydrated or dehydrogenated by a heat treatment is used as an active layer, a crystal region including nanocrystals is included in a superficial portion in the channel formation region, and the rest portion is amorphous or is formed of a mixture of amorphousness/non-crystals and microcrystals, where an amorphous region is dotted with microcrystals. By using an oxide semiconductor layer having such a structure, a change to an n-type caused by entry of moisture or elimination of oxygen to or from the superficial portion and generation of a parasitic channel can be prevented and a contact resistance with a source and drain electrodes can be reduced.
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Citations
22 Claims
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1. A semiconductor device comprising:
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a gate electrode layer; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer over the gate insulating layer; a first oxide insulating layer in contact with part of the oxide semiconductor layer; and a source electrode layer and a drain electrode layer in contact with part of the oxide semiconductor layer, wherein a region of the oxide semiconductor layer located directly underneath a gap between the source electrode and the first oxide insulating layer, and a region of the oxide semiconductor layer located directly underneath a gap between the drain electrode and the first oxide insulating layer, each has a thickness less than a region overlapping with the source electrode layer, a region overlapping with the first oxide insulating layer, and a region overlapping with the drain electrode layer. - View Dependent Claims (2, 3, 4, 5)
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6. A semiconductor device comprising:
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a gate electrode layer; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer over the gate insulating layer; a first oxide insulating layer in contact with part of the oxide semiconductor layer; and a source electrode layer and a drain electrode layer in contact with part of the oxide semiconductor layer, wherein a region of the oxide semiconductor layer located directly underneath a gap between the source electrode and the first oxide insulating layer, and a region of the oxide semiconductor layer located directly underneath a gap between the drain electrode and the first oxide insulating layer, each has a thickness less than a region overlapping with the source electrode layer, a region overlapping with the first oxide insulating layer, and a region overlapping with the drain electrode layer, and wherein a portion of the oxide semiconductor layer which is in contact with the first oxide insulating layer has a crystal region. - View Dependent Claims (7, 8, 9, 10, 11)
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12. A display device comprising:
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a pixel portion and a driver circuit portion over a substrate, the pixel portion and the driver circuit portion each including a thin film transistor, wherein the thin film transistor comprises; a gate electrode layer; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer over the gate insulating layer; a first oxide insulating layer in contact with part of the oxide semiconductor layer; and a source electrode layer and a drain electrode layer in contact with part of the oxide semiconductor layer, wherein a region of the oxide semiconductor layer located directly underneath a gap between the source electrode and the first oxide insulating layer, and a region of the oxide semiconductor layer located directly underneath a gap between the drain electrode and the first oxide insulating layer, each has a thickness less than a region overlapping with the source electrode layer, a region overlapping with the first oxide insulating layer, and a region overlapping with the drain electrode layer. - View Dependent Claims (13, 14, 15, 16)
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17. A display device comprising:
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a pixel portion and a driver circuit portion over a substrate, the pixel portion and the driver circuit portion each including a thin film transistor, wherein the thin film transistor comprises; a gate electrode layer; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer over the gate insulating layer; a first oxide insulating layer in contact with part of the oxide semiconductor layer; and a source electrode layer and a drain electrode layer in contact with part of the oxide semiconductor layer, wherein a region of the oxide semiconductor layer located directly underneath a gap between the source electrode and the first oxide insulating layer, and a region of the oxide semiconductor layer located directly underneath a gap between the drain electrode and the first oxide insulating layer, each has a thickness less than a region overlapping with the source electrode layer, a region overlapping with the first oxide insulating layer, and a region overlapping with the drain electrode layer, and wherein a portion of the oxide semiconductor layer which is in contact with the first oxide insulating layer has a crystal region. - View Dependent Claims (18, 19, 20, 21, 22)
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Specification