Transistor comprising an oxide semiconductor
First Claim
1. A transistor comprising:
- a gate electrode layer;
a gate insulating layer;
an oxide semiconductor layer comprising a region overlapping with the gate electrode layer with the gate insulating layer provided therebetween;
a first insulating layer over the oxide semiconductor layer;
a second insulating layer over the first insulating layer; and
a source electrode layer and a drain electrode layer,wherein the oxide semiconductor layer comprises indium, gallium, and zinc,wherein a side surface of the oxide semiconductor layer is in contact with a side surface of the source electrode layer or a side surface of the drain electrode layer,wherein the source electrode layer and the drain electrode layer overlap with the gate electrode layer,wherein the oxide semiconductor layer comprises a crystal region including a nanocrystal with a particle size greater than or equal to 1 nm and less than or equal to 20 nm,wherein an end portion of the oxide semiconductor layer has a tapered shape, andwherein c-axes of crystal grains in the crystal region are oriented in a direction substantially perpendicular to a surface of the oxide semiconductor layer.
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Abstract
An object of an embodiment of the present invention is to manufacture a semiconductor device with high display quality and high reliability, which includes a pixel portion and a driver circuit portion capable of high-speed operation over one substrate, using transistors having favorable electric characteristics and high reliability as switching elements. Two kinds of transistors, in each of which an oxide semiconductor layer including a crystalline region on one surface side is used as an active layer, are formed in a driver circuit portion and a pixel portion. Electric characteristics of the transistors can be selected by choosing the position of the gate electrode layer which determines the position of the channel. Thus, a semiconductor device including a driver circuit portion capable of high-speed operation and a pixel portion over one substrate can be manufactured.
275 Citations
18 Claims
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1. A transistor comprising:
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a gate electrode layer; a gate insulating layer; an oxide semiconductor layer comprising a region overlapping with the gate electrode layer with the gate insulating layer provided therebetween; a first insulating layer over the oxide semiconductor layer; a second insulating layer over the first insulating layer; and a source electrode layer and a drain electrode layer, wherein the oxide semiconductor layer comprises indium, gallium, and zinc, wherein a side surface of the oxide semiconductor layer is in contact with a side surface of the source electrode layer or a side surface of the drain electrode layer, wherein the source electrode layer and the drain electrode layer overlap with the gate electrode layer, wherein the oxide semiconductor layer comprises a crystal region including a nanocrystal with a particle size greater than or equal to 1 nm and less than or equal to 20 nm, wherein an end portion of the oxide semiconductor layer has a tapered shape, and wherein c-axes of crystal grains in the crystal region are oriented in a direction substantially perpendicular to a surface of the oxide semiconductor layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A transistor comprising:
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a gate electrode layer; a gate insulating layer; an oxide semiconductor layer comprising a first region overlapping with the gate electrode layer with the gate insulating layer provided therebetween and a second region whose resistance is lower than the resistance of the first region; a first insulating layer over the oxide semiconductor layer; a second insulating layer over the first insulating layer; and a source electrode layer and a drain electrode layer, wherein the oxide semiconductor layer comprises indium, gallium, and zinc, wherein a side surface of the oxide semiconductor layer is in contact with a side surface of the source electrode layer or a side surface of the drain electrode layer, wherein the source electrode layer and the drain electrode layer overlap with the gate electrode layer, wherein the oxide semiconductor layer comprises a crystal region including a nanocrystal with a particle size greater than or equal to 1 nm and less than or equal to 20 nm, wherein an end portion of the oxide semiconductor layer has a tapered shape, and wherein c-axes of crystal grains in the crystal region are oriented in a direction substantially perpendicular to a surface of the oxide semiconductor layer. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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Specification