SEMICONDUCTOR DEVICE AND METHOD FOR MANUFACTURING THE SAME
First Claim
1. A semiconductor device comprising:
- a gate electrode layer over a substrate having an insulating surface;
a gate insulating layer over the gate electrode layer;
an oxide semiconductor layer including a channel formation region over the gate insulating layer;
a buffer layer over the oxide semiconductor layer; and
source and drain electrode layers over the buffer layer,wherein in the buffer layer, a first region which is in contact with the source and drain electrode layers has higher electrical conductivity than a second region which is in contact with the channel formation region of the oxide semiconductor layer.
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Accused Products
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
10 Claims
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1. A semiconductor device comprising:
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a gate electrode layer over a substrate having an insulating surface; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer including a channel formation region over the gate insulating layer; a buffer layer over the oxide semiconductor layer; and source and drain electrode layers over the buffer layer, wherein in the buffer layer, a first region which is in contact with the source and drain electrode layers has higher electrical conductivity than a second region which is in contact with the channel formation region of the oxide semiconductor layer.
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2. A semiconductor device comprising:
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a gate electrode layer over a substrate having an insulating surface; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer including a channel formation region over the gate insulating layer; a buffer layer over the oxide semiconductor layer; and source and drain electrode layers over the buffer layer, wherein the buffer layer is an oxide semiconductor layer including a metal selected from group consisting of titanium, molybdenum, manganese and combination thereof, and wherein in the buffer layer, a first region which is in contact with the source and drain electrode layers has higher electrical conductivity than a second region which is in contact with the channel formation region of the oxide semiconductor layer. - View Dependent Claims (3, 4)
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5. A semiconductor device comprising:
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a gate electrode layer over a substrate having an insulating surface; a gate insulating layer over the gate electrode layer; an oxide semiconductor layer including a channel formation region over the gate insulating layer; a buffer layer over the oxide semiconductor layer; and source and drain electrode layers over the buffer layer, wherein in the buffer layer, a first region which is in contact with the source and drain electrode layers is a metal region and a second region which is in contact with the channel formation region of the oxide semiconductor layer is a metal oxide region, and wherein the metal oxide region has lower electrical conductivity than the channel formation region of the oxide semiconductor layer.
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6. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a gate electrode layer over a substrate having an insulating surface; forming a gate insulating layer over the gate electrode layer; forming a first oxide semiconductor layer including a channel formation region over the gate insulating layer; forming a second oxide semiconductor layer including a metal selected from group consisting of titanium, molybdenum, manganese and a combination thereof over the first oxide semiconductor layer; and forming source and drain electrode layers over the second oxide semiconductor layer, wherein heat treatment is performed on the second oxide semiconductor layer including a metal selected from group consisting of titanium, molybdenum, manganese and a combination thereof and the source and drain electrode layers, so that in the second oxide semiconductor layer, a first region which is in contact with the source and drain electrode layers has higher electrical conductivity than a second region which is in contact with the channel formation region of the first oxide semiconductor layer. - View Dependent Claims (7, 8)
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9. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a gate electrode over a substrate having an insulating surface; forming a gate insulating layer over the gate electrode layer; forming an oxide semiconductor layer including a channel formation region over the gate insulating layer; forming a metal film over the oxide semiconductor layer; and forming source and drain electrode layers over a first region of the metal film, wherein in the metal film, oxidation treatment is performed on a second region which is in contact with the channel formation region of the oxide semiconductor layer, so that a metal oxidation region is formed. - View Dependent Claims (10)
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Specification