Semiconductor device and method for manufacturing the same
First Claim
1. A method for manufacturing a semiconductor device comprising the steps of:
- forming an oxide semiconductor layer over an insulating layer;
heating the oxide semiconductor layer under an atmosphere comprising nitrogen at a temperature equal to or higher than 400°
C. to increase a carrier concentration in the oxide semiconductor layer;
after heating the oxide semiconductor layer, forming an oxide insulating layer over and in contact with a part of the oxide semiconductor layer; and
after forming the oxide insulating layer, heating the oxide insulating layer to reduce the carrier concentration in the oxide semiconductor layer.
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Abstract
An object is to provide a high reliable semiconductor device including a thin film transistor having stable electric characteristics. In a method for manufacturing a semiconductor device including a thin film transistor in which an oxide semiconductor film is used for a semiconductor layer including a channel formation region, heat treatment (which is for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor film and reduce impurities such as moisture. Besides impurities such as moisture existing in the oxide semiconductor film, heat treatment causes reduction of impurities such as moisture existing in the gate insulating layer and those in interfaces between the oxide semiconductor film and films which are provided over and below the oxide semiconductor film and are in contact with the oxide semiconductor film.
164 Citations
27 Claims
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1. A method for manufacturing a semiconductor device comprising the steps of:
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forming an oxide semiconductor layer over an insulating layer; heating the oxide semiconductor layer under an atmosphere comprising nitrogen at a temperature equal to or higher than 400°
C. to increase a carrier concentration in the oxide semiconductor layer;after heating the oxide semiconductor layer, forming an oxide insulating layer over and in contact with a part of the oxide semiconductor layer; and after forming the oxide insulating layer, heating the oxide insulating layer to reduce the carrier concentration in the oxide semiconductor layer. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first conductive layer; forming an oxide semiconductor layer over the conductive layer; heating the oxide semiconductor layer under an atmosphere comprising nitrogen at a temperature equal to or higher than 400°
C. to increase a carrier concentration in the oxide semiconductor layer;after heating the oxide semiconductor layer, forming an oxide insulating layer over and in contact with a part of the oxide semiconductor layer; after forming the oxide insulating layer, heating the oxide insulating layer to reduce the carrier concentration in the oxide semiconductor layer; and forming a second conductive layer over the oxide insulating layer, wherein the second conductive layer overlaps the first conductive layer and the oxide semiconductor layer. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18, 19)
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20. A method for manufacturing a semiconductor device comprising the steps of:
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forming an oxide semiconductor layer; performing a first heat treatment on the oxide semiconductor layer under an atmosphere comprising nitrogen at a temperature not lower than 300°
C. to reduce oxygen in the oxide semiconductor layer;forming an oxide insulating layer over and in contact with a region in the oxide semiconductor layer; and performing a second heat treatment on the oxide insulating layer under an atmosphere comprising nitrogen to increase oxygen in the oxide semiconductor layer. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27)
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Specification