Method for manufacturing semiconductor device
First Claim
1. A semiconductor device comprising:
- a first conductive film over a substrate;
a first insulating film over the first conductive film;
a first oxide semiconductor film over the first insulating film;
a second oxide semiconductor film over the first oxide semiconductor film;
a second conductive film and a third conductive film over the first oxide semiconductor film and the second oxide semiconductor film;
an oxide insulating film over the second conductive film and the third conductive film; and
a fourth conductive film over the oxide insulating film,wherein the oxide insulating film is in contact with part of the first oxide semiconductor film and part of the second oxide semiconductor film,wherein the fourth conductive film overlaps the first conductive film, the first oxide semiconductor film and the second oxide semiconductor film, andwherein the first conductive film and the fourth conductive film are configured to be supplied with a same potential.
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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.
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Citations
13 Claims
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1. A semiconductor device comprising:
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a first conductive film over a substrate; a first insulating film over the first conductive film; a first oxide semiconductor film over the first insulating film; a second oxide semiconductor film over the first oxide semiconductor film; a second conductive film and a third conductive film over the first oxide semiconductor film and the second oxide semiconductor film; an oxide insulating film over the second conductive film and the third conductive film; and a fourth conductive film over the oxide insulating film, wherein the oxide insulating film is in contact with part of the first oxide semiconductor film and part of the second oxide semiconductor film, wherein the fourth conductive film overlaps the first conductive film, the first oxide semiconductor film and the second oxide semiconductor film, and wherein the first conductive film and the fourth conductive film are configured to be supplied with a same potential. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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Specification