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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a gate electrode layer; a gate insulating layer; a first oxide semiconductor layer having an island shape; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode over the second oxide semiconductor layer; and a drain electrode over the second oxide semiconductor layer, wherein the first oxide semiconductor layer and the gate electrode layer overlap with each other with the gate insulating layer interposed therebetween, and wherein the second oxide semiconductor layer covers a side surface of the first oxide semiconductor layer. - 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 layer; a gate insulating layer; a first oxide semiconductor layer having an island shape; a second oxide semiconductor layer over the first oxide semiconductor layer; a source electrode is electrically connected to the second oxide semiconductor layer; and a drain electrode is electrically connected to the second oxide semiconductor layer, wherein the first oxide semiconductor layer and the gate electrode layer overlap with each other with the gate insulating layer interposed therebetween, and wherein the second oxide semiconductor layer covers a side surface of the first oxide semiconductor layer. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21)
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Specification