Method for manufacturing semiconductor device
First Claim
1. A method for manufacturing a semiconductor device comprising the steps of:
- forming an insulating layer over a substrate,forming a first oxide semiconductor layer over the insulating layer;
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;
after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen;
forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment;
etching the conductive film to form a source electrode layer and a drain electrode layer; and
forming an oxide insulating film in contact with part of 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.
160 Citations
35 Claims
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1. A method for manufacturing a semiconductor device comprising the steps of:
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forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; 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; after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; and forming an oxide insulating film in contact with part of 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 an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; 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; after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; forming an oxide insulating film in contact with part of the second oxide semiconductor layer; and performing a second heat treatment after the oxide insulating film is formed, wherein the first heat treatment is performed at a first temperature higher or equal to 400°
C. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A method for manufacturing a semiconductor device comprising the steps of:
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forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; forming a second oxide semiconductor layer including crystals over the first oxide semiconductor layer; performing a first heat treatment on the first oxide semiconductor layer and the second oxide semiconductor layer; after the first heat treatment, cooling the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; and forming an oxide insulating film in contact with part of the second oxide semiconductor layer. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25, 26)
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27. A method for manufacturing a semiconductor device comprising the steps of:
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forming an insulating layer over a substrate, forming a first oxide semiconductor layer over the insulating layer; 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; after the first heat treatment, supplying oxygen to the first oxide semiconductor layer and the second oxide semiconductor layer in an atmosphere containing oxygen; forming a conductive film over the first oxide semiconductor layer and the second oxide semiconductor layer after the first heat treatment; etching the conductive film to form a source electrode layer and a drain electrode layer; and forming an oxide insulating film in contact with part of the second oxide semiconductor layer. - View Dependent Claims (28, 29, 30, 31, 32, 33, 34, 35)
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