Method for manufacturing semiconductor device
First Claim
1. A method for manufacturing a semiconductor device comprising the steps of:
- forming a first oxide semiconductor layer over a substrate;
forming a second oxide semiconductor layer over the first oxide semiconductor layer;
performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer in an inert atmosphere or under a reduced pressure in a chamber;
after the first heat treatment, introducing oxygen into the chamber; and
forming an insulating film containing oxygen in contact with the second oxide semiconductor layer.
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Abstract
It is an object to provide a highly reliable semiconductor device which includes a thin film transistor having stable electric characteristics. It is another object to manufacture a highly reliable semiconductor device at lower cost with high productivity. In a method for manufacturing a semiconductor device which includes a thin film transistor where a semiconductor layer having a channel formation region, a source region, and a drain region are formed using an oxide semiconductor layer, heat treatment (heat treatment for dehydration or dehydrogenation) is performed so as to improve the purity of the oxide semiconductor layer and reduce impurities such as moisture. Moreover, the oxide semiconductor layer subjected to the heat treatment is slowly cooled under an oxygen atmosphere.
184 Citations
28 Claims
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1. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first oxide semiconductor layer over a substrate; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer in an inert atmosphere or under a reduced pressure in a chamber; after the first heat treatment, introducing oxygen into the chamber; and forming an insulating film containing oxygen in contact with the second 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 oxide semiconductor layer over a substrate; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer in an inert atmosphere or under a reduced pressure in a chamber; after the first heat treatment, introducing oxygen into the chamber; and forming an insulating film containing oxygen in contact with the second oxide semiconductor layer, wherein the second oxide semiconductor layer includes nanocrystals. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for manufacturing a semiconductor device comprising the steps of:
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forming a gate electrode over a substrate; forming a gate insulating film over the gate electrode; forming a first oxide semiconductor layer over the gate insulating film; forming a second oxide semiconductor layer over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer in an inert atmosphere or under a reduced pressure in a chamber; after the first heat treatment, introducing oxygen into the chamber; forming a drain electrode and a source electrode electrically connected to the second oxide semiconductor layer; and forming a first insulating film containing oxygen in contact with the second oxide semiconductor layer. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification