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 inert atmosphere at a temperature equal to or higher than 450°
C., whereby a carrier concentration in the oxide semiconductor layer is equal to or higher than 1×
1018 cm−
3; and
forming an oxide insulating layer over and in contact with a part of the oxide semiconductor layer, whereby a carrier concentration in the part of the oxide semiconductor layer is lower than 1×
1018 cm−
3,wherein a hydrogen concentration in the oxide semiconductor layer is lower than 3×
1020 cm−
3.
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Accused Products
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.
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Citations
28 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 inert atmosphere at a temperature equal to or higher than 450°
C., whereby a carrier concentration in the oxide semiconductor layer is equal to or higher than 1×
1018 cm−
3; andforming an oxide insulating layer over and in contact with a part of the oxide semiconductor layer, whereby a carrier concentration in the part of the oxide semiconductor layer is lower than 1×
1018 cm−
3,wherein a hydrogen concentration in the oxide semiconductor layer is lower than 3×
1020 cm−
3. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for manufacturing a semiconductor device comprising the steps of:
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forming an oxide semiconductor layer over an insulating layer; performing dehydration or dehydrogenation on the oxide semiconductor layer, whereby the oxide semiconductor layer comprises an oxide semiconductor in an oxygen-deficiency state; and forming an oxide insulating layer over and in contact with a part of the oxide semiconductor layer, whereby the oxide semiconductor layer comprises an oxide semiconductor in an oxygen-excess state, wherein a hydrogen concentration in the oxide semiconductor layer is lower than 3×
1020 cm−
3. - View Dependent Claims (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 over an insulating layer; performing dehydration or dehydrogenation on the oxide semiconductor layer, whereby the oxide semiconductor layer comprises an n-type oxide semiconductor; and forming an oxide insulating layer over and in contact with the oxide semiconductor layer, whereby the oxide semiconductor layer comprises an i-type oxide semiconductor, wherein a hydrogen concentration in the oxide semiconductor layer is lower than 3×
1020 cm−
3. - View Dependent Claims (21, 22, 23, 24, 25, 26, 27, 28)
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Specification