Semiconductor device
First Claim
1. A semiconductor device comprising:
- a first oxide semiconductor film;
a second oxide semiconductor film over the first oxide semiconductor film, andan insulating film over the second oxide semiconductor film, wherein a hydrogen concentration in the insulating film is less than 7.2×
1020 atoms/cm3,wherein the first oxide semiconductor film and the second oxide semiconductor film each comprises indium, gallium, and zinc, andwherein the first oxide semiconductor film has a lower content percentage of indium and a higher content percentage of gallium than the second oxide semiconductor film.
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Accused Products
Abstract
Provided is a transistor which includes an oxide semiconductor film and has stable electrical characteristics. In the transistor, over an oxide film which can release oxygen by being heated, a first oxide semiconductor film which can suppress oxygen release at least from the oxide film is formed. Over the first oxide semiconductor film, a second oxide semiconductor film is formed. With such a structure in which the oxide semiconductor films are stacked, the oxygen release from the oxide film can be suppressed at the time of the formation of the second oxide semiconductor film, and oxygen can be released from the oxide film in later-performed heat treatment. Thus, oxygen can pass through the first oxide semiconductor film to be favorably supplied to the second oxide semiconductor film. Oxygen supplied to the second oxide semiconductor film can suppress the generation of oxygen deficiency, resulting in stable electrical characteristics.
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Citations
34 Claims
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1. A semiconductor device comprising:
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a first oxide semiconductor film; a second oxide semiconductor film over the first oxide semiconductor film, and an insulating film over the second oxide semiconductor film, wherein a hydrogen concentration in the insulating film is less than 7.2×
1020 atoms/cm3,wherein the first oxide semiconductor film and the second oxide semiconductor film each comprises indium, gallium, and zinc, and wherein the first oxide semiconductor film has a lower content percentage of indium and a higher content percentage of gallium than the second oxide semiconductor film. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13)
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14. A semiconductor device comprising:
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a first transistor, wherein a channel formation region of the first transistor comprises a semiconductor material; an insulating film over the first transistor; and a second transistor over the insulating film, the second transistor comprising; a first oxide semiconductor film; a second oxide semiconductor film over the first oxide semiconductor film; a gate insulating film over the second oxide semiconductor film; and a gate electrode over the second oxide semiconductor film with the gate insulating film interposed therebetween, wherein the first oxide semiconductor film and the second oxide semiconductor film each comprises indium, gallium, and zinc, and wherein the first oxide semiconductor film has a lower content percentage of indium and a higher content percentage of gallium than the second oxide semiconductor film. - View Dependent Claims (15, 16, 17, 18, 19, 20, 21)
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22. A semiconductor device comprising:
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a first oxide semiconductor film; a second oxide semiconductor film, wherein the first oxide semiconductor film and the second oxide semiconductor film overlap each other; and an insulating film adjacent to the second oxide semiconductor film, wherein a hydrogen concentration in the insulating film is less than 7.2×
1020 atoms/cm3,wherein the first oxide semiconductor film and the second oxide semiconductor film each comprises indium, gallium, and zinc, and wherein the first oxide semiconductor film has a lower content percentage of indium and a higher content percentage of gallium than the second oxide semiconductor film. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34)
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Specification