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, the second oxide semiconductor film comprising a channel region and a pair of low-resistance regions in contact with the channel region;
a gate insulating film over the second oxide semiconductor film; and
a gate electrode over the channel region with the gate insulating film interposed therebetween,wherein the pair of low-resistance regions is selectively doped by using the gate electrode as a mask,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.
178 Citations
43 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, the second oxide semiconductor film comprising a channel region and a pair of low-resistance regions in contact with the channel region; a gate insulating film over the second oxide semiconductor film; and a gate electrode over the channel region with the gate insulating film interposed therebetween, wherein the pair of low-resistance regions is selectively doped by using the gate electrode as a mask, 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)
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8. 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, the second oxide semiconductor film comprising a channel region and a pair of low-resistance regions in contact with the channel region; 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 pair of low-resistance regions is selectively doped by using the gate electrode as a mask, 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 (9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23)
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24. 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; a gate electrode over the second oxide semiconductor film with the gate insulating film interposed therebetween; an insulating film over the gate electrode; a sidewall insulating film along a side surface of the gate electrode and a side surface of the insulating film; a source electrode and a drain electrode which are on the sidewall insulating film and electrically connected to the second oxide semiconductor film; and a protective insulating film and an interlayer insulating film which are over the source electrode and the drain electrode, 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 (25, 26, 27, 28, 29, 30, 31, 32)
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33. 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 source electrode and a drain electrode on a top surface of 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 second oxide semiconductor film is between the source electrode and the drain electrode, and electrically connected to the source electrode and the drain electrode, 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 (34, 35, 36, 37, 38, 39, 40, 41, 42, 43)
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Specification