Semiconductor device and method for manufacturing the same
First Claim
1. A semiconductor device comprising:
- a gate electrode layer;
a gate insulating layer over the gate electrode layer;
a source electrode layer and a drain electrode layer over the gate insulating layer;
an oxide semiconductor layer over the gate insulating layer; and
a semiconductor layer over the oxide semiconductor layer,wherein the oxide semiconductor layer is in contact with the gate insulating layer and side face portions of the source and drain electrode layers,wherein electrical conductivity of the semiconductor layer is higher than electrical conductivity of the oxide semiconductor layer, andwherein the semiconductor layer includes a crystal.
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Abstract
An object is to increase field effect mobility of a thin film transistor including an oxide semiconductor. Another object is to stabilize electrical characteristics of the thin film transistor. In a thin film transistor including an oxide semiconductor layer, a semiconductor layer or a conductive layer having higher electrical conductivity than the oxide semiconductor is formed over the oxide semiconductor layer, whereby field effect mobility of the thin film transistor can be increased. Further, by forming a semiconductor layer or a conductive layer having higher electrical conductivity than the oxide semiconductor between the oxide semiconductor layer and a protective insulating layer of the thin film transistor, change in composition or deterioration in film quality of the oxide semiconductor layer is prevented, so that electrical characteristics of the thin film transistor can be stabilized.
129 Citations
22 Claims
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1. A semiconductor device comprising:
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a gate electrode layer; a gate insulating layer over the gate electrode layer; a source electrode layer and a drain electrode layer over the gate insulating layer; an oxide semiconductor layer over the gate insulating layer; and a semiconductor layer over the oxide semiconductor layer, wherein the oxide semiconductor layer is in contact with the gate insulating layer and side face portions of the source and drain electrode layers, wherein electrical conductivity of the semiconductor layer is higher than electrical conductivity of the oxide semiconductor layer, and wherein the semiconductor layer includes a crystal. - View Dependent Claims (2, 3, 4, 5, 20)
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6. A semiconductor device comprising:
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a gate electrode layer; a gate insulating layer over the gate electrode layer; a source electrode layer and a drain electrode layer over the gate insulating layer; a first oxide semiconductor layer over the gate insulating layer; and a second oxide semiconductor layer over the first oxide semiconductor layer, wherein the first oxide semiconductor layer is in contact with the gate insulating layer and side face portions of the source and drain electrode layers, wherein electrical conductivity of the second oxide semiconductor layer is higher than electrical conductivity of the first oxide semiconductor layer, and wherein the second oxide semiconductor layer includes a crystal. - View Dependent Claims (7, 8, 9, 10, 21)
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11. A semiconductor device comprising:
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a gate electrode layer; a gate insulating layer over the gate electrode layer; a source electrode layer and a drain electrode layer over the gate insulating layer; a first oxide semiconductor layer over the gate insulating layer; a second oxide semiconductor layer over the first oxide semiconductor layer; and a conductive layer over the second oxide semiconductor layer, wherein the first oxide semiconductor layer is in contact with the gate insulating layer and side face portions of the source and drain electrode layers, wherein electrical conductivity of the second oxide semiconductor layer is higher than electrical conductivity of the first oxide semiconductor layer, and wherein the second oxide semiconductor layer includes a crystal. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 22)
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Specification