Semiconductor device and method for manufacturing the same
First Claim
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1. A semiconductor device comprising:
- a thin film transistor, the thin film transistor comprising;
a source electrode layer and a drain electrode layer;
a buffer layer having n-type conductivity over the source electrode layer and the drain electrode layer;
a semiconductor layer over the buffer layer;
a gate insulating layer over the semiconductor layer; and
a gate electrode layer over the gate insulating layer,wherein the semiconductor layer and the buffer layer are oxide semiconductor layers,wherein a carrier concentration of the buffer layer is higher than a carrier concentration of the semiconductor layer, andwherein each of the source electrode layer and the drain electrode layer is electrically connected to the semiconductor layer with the buffer layer interposed between the source electrode layer or the drain electrode layer and the semiconductor layer.
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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. The buffer layer having higher carrier concentration than the semiconductor layer is provided intentionally between the source and drain electrode layers and the semiconductor layer, whereby an ohmic contact is formed.
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14 Claims
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1. A semiconductor device comprising:
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a thin film transistor, the thin film transistor comprising; a source electrode layer and a drain electrode layer; a buffer layer having n-type conductivity over the source electrode layer and the drain electrode layer; a semiconductor layer over the buffer layer; a gate insulating layer over the semiconductor layer; and a gate electrode layer over the gate insulating layer, wherein the semiconductor layer and the buffer layer are oxide semiconductor layers, wherein a carrier concentration of the buffer layer is higher than a carrier concentration of the semiconductor layer, and wherein each of the source electrode layer and the drain electrode layer is electrically connected to the semiconductor layer with the buffer layer interposed between the source electrode layer or the drain electrode layer and the semiconductor layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device comprising:
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a thin film transistor, the thin film transistor comprising; a source electrode layer and a drain electrode layer; a buffer layer having n-type conductivity over the source electrode layer and the drain electrode layer; a semiconductor layer over the buffer layer; a gate insulating layer over the semiconductor layer; and a gate electrode layer over the gate insulating layer, wherein the semiconductor layer and the buffer layer are oxide semiconductor layers, wherein the gate electrode layer does not overlap with the source electrode layer and the drain electrode layer at a channel formation region of the semiconductor layer interposed between the source electrode layer and the drain electrode layer, wherein a carrier concentration of the buffer layer is higher than a carrier concentration of the semiconductor layer, and wherein each of the source electrode layer and the drain electrode layer is electrically connected to the semiconductor layer with the buffer layer interposed between the source electrode layer or the drain electrode layer and the semiconductor layer. - View Dependent Claims (9, 10, 11, 12, 13, 14)
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Specification