Semiconductor device and manufacturing method thereof
First Claim
1. A semiconductor device comprising:
- a substrate;
a gate electrode layer over the substrate;
a gate insulating layer in contact with the gate electrode layer;
an oxide semiconductor layer in contact with the gate insulating layer; and
an insulating layer in contact with the oxide semiconductor layer,wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer.
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Abstract
An object is to provide a transistor in which the state of an interface between an oxide semiconductor layer and an insulating film (gate insulating layer) in contact with the oxide semiconductor layer is favorable; and a method for manufacturing the transistor. In order to obtain the transistor, nitrogen is added to a region of the oxide semiconductor layer in the vicinity of the interface with the gate insulating layer. Specifically, a concentration gradient of nitrogen is formed in the oxide semiconductor layer, and a region containing much nitrogen is provided at the interface with the gate insulating layer. By the addition of nitrogen, a region with high crystallinity can be formed in the region of the oxide semiconductor layer in the vicinity of the interface with the gate insulating layer, so that a stable interface state can be obtained.
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Citations
20 Claims
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1. A semiconductor device comprising:
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a substrate; a gate electrode layer over the substrate; a gate insulating layer in contact with the gate electrode layer; an oxide semiconductor layer in contact with the gate insulating layer; and an insulating layer in contact with the oxide semiconductor layer, wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer. - View Dependent Claims (2, 3, 4, 5)
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6. A semiconductor device comprising:
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a substrate; a gate electrode layer over the substrate; a gate insulating layer in contact with the gate electrode layer; an oxide semiconductor layer in contact with the gate insulating layer; and an insulating layer in contact with the oxide semiconductor layer, wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer, and wherein the stepwise concentration gradient of oxygen becomes highest at an interface with the insulating layer. - View Dependent Claims (7, 8, 9, 10)
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11. A semiconductor device comprising:
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a substrate; a gate electrode layer over the substrate; a gate insulating layer in contact with the gate electrode layer; an oxide semiconductor layer in contact with the gate insulating layer; and an insulating layer in contact with the oxide semiconductor layer, wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer, and wherein the oxide semiconductor layer has a stepwise concentration gradient of nitrogen, which becomes highest at an interface with the gate insulating layer. - View Dependent Claims (12, 13, 14, 15)
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16. A semiconductor device comprising:
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a substrate; a gate electrode layer over the substrate; a gate insulating layer in contact with the gate electrode layer; an oxide semiconductor layer in contact with the gate insulating layer; and an insulating layer in contact with the oxide semiconductor layer, wherein the oxide semiconductor layer has a stepwise concentration gradient of oxygen, which becomes higher at a closer region to the insulating layer, wherein the oxide semiconductor layer has a stepwise concentration gradient of nitrogen, which becomes highest at an interface with the gate insulating layer, and wherein the stepwise concentration gradient of oxygen becomes highest at an interface with the insulating layer. - View Dependent Claims (17, 18, 19, 20)
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Specification