SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
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Abstract
It is an object to provide a highly reliable semiconductor device including a thin film transistor with stable electric characteristics. In a semiconductor device including an inverted staggered thin film transistor whose semiconductor layer is an oxide semiconductor layer, a buffer layer is provided over the oxide semiconductor layer. The buffer layer is in contact with a channel formation region of the semiconductor layer and source and drain electrode layers. A film of the buffer layer has resistance distribution. A region provided over the channel formation region of the semiconductor layer has lower electrical conductivity than the channel formation region of the semiconductor layer, and a region in contact with the source and drain electrode layers has higher electrical conductivity than the channel formation region of the semiconductor layer.
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Citations
21 Claims
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1. (canceled)
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2. A semiconductor device comprising:
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an oxide semiconductor layer including a channel formation region, a first region, and a second region; a layer including a metal oxide over and in contact with the oxide semiconductor layer; a source electrode over and in contact with the first region including a first top surface of the oxide semiconductor layer; and a drain electrode over and in contact with the second region including a second top surface of the oxide semiconductor layer, wherein an electrical conductivity of the first region is higher than an electrical conductivity of the channel formation region, and wherein an electrical conductivity of the second region is higher than an electrical conductivity of the channel formation region. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A semiconductor device comprising:
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a gate electrode; a gate insulating layer over the gate electrode; an oxide semiconductor layer over the gate insulating layer, wherein the oxide semiconductor layer includes a channel formation region, a first region, and a second region; a layer including a metal oxide over and in contact with the oxide semiconductor layer; a source electrode over and in contact with the first region including a first top surface of the oxide semiconductor layer; and a drain electrode over and in contact with the second region including a second top surface of the oxide semiconductor layer, wherein an electrical conductivity of the first region is higher than an electrical conductivity of the channel formation region, and wherein an electrical conductivity of the second region is higher than an electrical conductivity of the channel formation region. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification