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.
1 Citation
17 Claims
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1. (canceled)
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2. A semiconductor device comprising:
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a first oxide semiconductor layer including a channel formation region; a second oxide semiconductor layer in contact with the first oxide semiconductor layer; a gate electrode overlapping with the channel formation region; a gate insulating layer between the gate electrode and the first oxide semiconductor layer; a source electrode in contact with a first region of the first oxide semiconductor layer; a drain electrode in contact with a second region of the first 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)
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10. A semiconductor device comprising:
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a first oxide semiconductor layer including a channel formation region; a second oxide semiconductor layer in contact with the first oxide semiconductor layer; a gate electrode overlapping with the channel formation region; a gate insulating layer between the gate electrode and the first oxide semiconductor layer; a source electrode in contact with a first region of the first oxide semiconductor layer; a drain electrode in contact with a second region of the first oxide semiconductor layer, wherein an electrical conductivity of the first region is higher than an electrical conductivity of the channel formation region, wherein an electrical conductivity of the second region is higher than an electrical conductivity of the channel formation region, wherein a concentration of oxygen contained in the first region is lower than a concentration of oxygen contained in the channel formation region, and wherein a concentration of oxygen contained in the second region is lower than a concentration of oxygen contained in the channel formation region. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification