Semiconductor device
First Claim
1. A semiconductor device comprising:
- a first oxide semiconductor film; and
a second oxide semiconductor film over the first oxide semiconductor film,wherein the first oxide semiconductor film and the second oxide semiconductor film each comprises indium, gallium, and zinc,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, andwherein the second oxide semiconductor film comprises a crystal portion having a c-axis aligned in a direction parallel to a normal vector of a surface where the second oxide semiconductor film is formed.
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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.
168 Citations
13 Claims
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1. A semiconductor device comprising:
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a first oxide semiconductor film; and a second oxide semiconductor film over the first oxide semiconductor film, wherein the first oxide semiconductor film and the second oxide semiconductor film each comprises indium, gallium, and zinc, 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, and wherein the second oxide semiconductor film comprises a crystal portion having a c-axis aligned in a direction parallel to a normal vector of a surface where the second oxide semiconductor film is formed. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A semiconductor device comprising:
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a first oxide semiconductor film over an oxide 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, 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, and wherein the second oxide semiconductor film comprises a crystal portion having a c-axis aligned in a direction parallel to a normal vector of a surface where the second oxide semiconductor film is formed. - View Dependent Claims (8, 9, 10, 11, 12, 13)
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Specification