Semiconductor device and manufacturing method thereof
First Claim
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1. A semiconductor device comprising:
- an oxide semiconductor stacked layer comprising a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer;
wherein energy at a bottom of a conduction band of the second oxide semiconductor layer is lower than energy at a bottom of a conduction band of the first oxide semiconductor layer and energy at a bottom of a conduction band of the third oxide semiconductor layer,wherein the second oxide semiconductor layer comprises a crystal including a region, andwherein a c-axis of the region of the crystal is aligned in a direction perpendicular to a surface of the second oxide semiconductor layer.
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Abstract
Provided are a transistor which has electrical characteristics requisite for its purpose and uses an oxide semiconductor layer and a semiconductor device including the transistor. In the bottom-gate transistor in which at least a gate electrode layer, a gate insulating film, and the semiconductor layer are stacked in this order, an oxide semiconductor stacked layer including at least two oxide semiconductor layers whose energy gaps are different from each other is used as the semiconductor layer. Oxygen and/or a dopant may be added to the oxide semiconductor stacked layer.
162 Citations
28 Claims
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1. A semiconductor device comprising:
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an oxide semiconductor stacked layer comprising a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer; wherein energy at a bottom of a conduction band of the second oxide semiconductor layer is lower than energy at a bottom of a conduction band of the first oxide semiconductor layer and energy at a bottom of a conduction band of the third oxide semiconductor layer, wherein the second oxide semiconductor layer comprises a crystal including a region, and wherein a c-axis of the region of the crystal is aligned in a direction perpendicular to a surface of the second oxide semiconductor layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A semiconductor device comprising:
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an oxide semiconductor stacked layer comprising a first oxide semiconductor layer, a second oxide semiconductor layer over the first oxide semiconductor layer, and a third oxide semiconductor layer over the second oxide semiconductor layer; wherein energy at a bottom of a conduction band of the second oxide semiconductor layer is lower than energy at a bottom of a conduction band of the first oxide semiconductor layer and energy at a bottom of a conduction band of the third oxide semiconductor layer, wherein the second oxide semiconductor layer comprises a crystal including a region, and wherein a c-axis of the region of the crystal is aligned so that an angle formed between the c-axis and a surface of the second oxide semiconductor layer is greater than or equal to 85° and
less than or equal to 95°
. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A semiconductor device comprising:
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a first oxide semiconductor layer; a second oxide semiconductor layer on the first oxide semiconductor layer; a third oxide semiconductor layer on the second oxide semiconductor layer, wherein the third oxide semiconductor layer covers side surfaces of the second oxide semiconductor layer; a source electrode on and in contact with the third oxide semiconductor layer; a drain electrode on and in contact with the third oxide semiconductor layer; a gate electrode layer comprising a region overlapping with the first oxide semiconductor layer, the second oxide semiconductor layer and the third oxide semiconductor layer; wherein energy at a bottom of a conduction band of the second oxide semiconductor layer is lower than energy at a bottom of a conduction band of the first oxide semiconductor layer and energy at a bottom of a conduction band of the third oxide semiconductor layer, wherein the second oxide semiconductor layer comprises a crystal including a region, and wherein a c-axis of the region of the crystal is aligned in a direction perpendicular to a surface of the second oxide semiconductor layer. - View Dependent Claims (18, 19, 20)
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21. A semiconductor device comprising:
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a first oxide layer comprising In, Ga, and Zn; an oxide semiconductor layer over the first oxide layer; and a second oxide layer comprising In, Ga, and Zn over the oxide semiconductor layer; wherein energy at a bottom of a conduction band of the oxide semiconductor layer is lower than energy at a bottom of a conduction band of the first oxide layer and energy at a bottom of a conduction band of the second oxide layer, wherein the oxide semiconductor layer comprises a crystal including a region, and wherein a c-axis of the region of the crystal is aligned in a direction perpendicular to a surface of the oxide semiconductor layer. - View Dependent Claims (22, 23, 24)
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25. A semiconductor device comprising:
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a first oxide layer comprising In, Ga, and Zn; an oxide semiconductor layer over the first oxide layer; and a second oxide layer comprising In, Ga, and Zn over the oxide semiconductor layer; wherein energy at a bottom of a conduction band of the oxide semiconductor layer is lower than energy at a bottom of a conduction band of the first oxide layer and energy at a bottom of a conduction band of the second oxide layer, wherein the oxide semiconductor layer comprises a crystal including a region, and wherein a c-axis of the region of the crystal is aligned so that an angle formed between the c-axis and a surface of the oxide semiconductor layer is greater than or equal to 85° and
less than or equal to 95°
. - View Dependent Claims (26, 27, 28)
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Specification