SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
First Claim
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1. A semiconductor device including a thin film transistor, the thin film transistor comprising:
- a first metal oxide layer having n-type conductivity over a source electrode layer;
a second metal oxide layer having n-type conductivity over a drain electrode layer;
an oxide semiconductor layer over the first metal oxide layer and the second metal oxide layer;
a gate insulating layer over the oxide semiconductor layer; and
a gate electrode layer over the gate insulating layer,wherein a carrier concentration of the first metal oxide layer and the second metal oxide layer is higher than a carrier concentration of the oxide semiconductor layer,wherein the oxide semiconductor layer and the source electrode layer are electrically connected to each other with the first metal oxide layer interposed therebetween, andwherein the oxide semiconductor layer and the drain electrode layer are electrically connected to each other with the second metal oxide layer interposed therebetween.
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Abstract
An embodiment is to include a staggered (top gate structure) thin film transistor in which an oxide semiconductor film containing In, Ga, and Zn is used as a semiconductor layer and a buffer layer is provided between the semiconductor layer and a source and drain electrode layers. A metal oxide layer having higher carrier concentration than the semiconductor layer is provided intentionally as the buffer layer between the source and drain electrode layers and the semiconductor layer, whereby an ohmic contact is formed.
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Citations
28 Claims
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1. A semiconductor device including a thin film transistor, the thin film transistor comprising:
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a first metal oxide layer having n-type conductivity over a source electrode layer; a second metal oxide layer having n-type conductivity over a drain electrode layer; an oxide semiconductor layer over the first metal oxide layer and the second metal oxide layer; a gate insulating layer over the oxide semiconductor layer; and a gate electrode layer over the gate insulating layer, wherein a carrier concentration of the first metal oxide layer and the second metal oxide layer is higher than a carrier concentration of the oxide semiconductor layer, wherein the oxide semiconductor layer and the source electrode layer are electrically connected to each other with the first metal oxide layer interposed therebetween, and wherein the oxide semiconductor layer and the drain electrode layer are electrically connected to each other with the second metal oxide layer interposed therebetween. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A semiconductor device including a thin film transistor, the thin film transistor comprising:
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a first metal oxide layer having n-type conductivity over a source electrode layer; a second metal oxide layer having n-type conductivity over a drain electrode layer; an oxide semiconductor layer over the first metal oxide layer and the second metal oxide layer; a gate insulating layer over the oxide semiconductor layer; and a gate electrode layer over the gate insulating layer, wherein each of the first metal oxide layer and the second metal oxide layer extends over the source electrode layer and the drain electrode layer beyond an edge of the oxide semiconductor layer, respectively, wherein a carrier concentration of the first metal oxide layer and the second metal oxide layer is higher than a carrier concentration of the oxide semiconductor layer, and wherein the oxide semiconductor layer and the source electrode layer are electrically connected to each other with the first metal oxide layer interposed therebetween, and wherein the oxide semiconductor layer and the drain electrode layer are electrically connected to each other with the second metal oxide layer interposed therebetween. - View Dependent Claims (10, 11, 12, 13, 14, 15, 16)
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17. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a source electrode layer and a drain electrode layer over a substrate; forming a first metal oxide layer having n-type conductivity over the source electrode layer; forming a second metal oxide layer having n-type conductivity over the drain electrode layer; forming an oxide semiconductor layer over the first metal oxide layer and the second metal oxide layer; forming a gate insulating layer over the oxide semiconductor layer; and forming a gate electrode layer over the gate insulating layer, wherein a carrier concentration of each of the first metal oxide layer and the second metal oxide layer is higher than a carrier concentration of the oxide semiconductor layer, wherein the oxide semiconductor layer and the source electrode layer are electrically connected to each other with the first metal oxide layer interposed therebetween, and wherein the oxide semiconductor layer and the drain electrode layer are electrically connected to each other with the second metal oxide layer interposed therebetween. - View Dependent Claims (18, 19, 20, 21, 22)
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23. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a source electrode layer and a drain electrode layer over a substrate; forming a first metal oxide layer having n-type conductivity over the source electrode layer; forming a second metal oxide layer having n-type conductivity over the drain electrode layer; forming an oxide semiconductor layer over the first metal oxide layer and the second metal oxide layer; forming a gate insulating layer over the oxide semiconductor layer; and forming a gate electrode layer over the gate insulating layer, wherein a carrier concentration of each of the first metal oxide layer and the second metal oxide layer is higher than a carrier concentration of the oxide semiconductor layer, wherein the oxide semiconductor layer and the source electrode layer are electrically connected to each other with the first metal oxide layer interposed therebetween, wherein the oxide semiconductor layer and the drain electrode layer are electrically connected to each other with the second metal oxide layer interposed therebetween, and wherein the oxide semiconductor layer, the gate insulating layer, and the gate electrode layer are successively formed without exposure to air. - View Dependent Claims (24, 25, 26, 27, 28)
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Specification