Semiconductor device and manufacturing method thereof
First Claim
1. A method for manufacturing a semiconductor device comprising the steps of:
- forming a first insulating film over a substrate;
forming a first oxide semiconductor film over the first insulating film;
forming a depression in the first insulating film and forming a second oxide semiconductor film by selectively etching the first insulating film and the first oxide semiconductor film;
forming a second insulating film over the first insulating film and the second oxide semiconductor film;
forming a third insulating film over the second insulating film;
forming a fourth insulating film in contact with side surfaces of the depression and the second oxide semiconductor film, and a fifth insulating film in contact with a side surface of the fourth insulating film by polishing the second insulating film and the third insulating film so that the fourth insulating film and the fifth insulating film are provided in the depression;
forming a source electrode and a drain electrode over the second oxide semiconductor film;
forming a sixth insulating film over the second oxide semiconductor film, the source electrode, and the drain electrode; and
forming a gate electrode over the sixth insulating film.
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Accused Products
Abstract
A base insulating film is formed over a substrate. A first oxide semiconductor film is formed over the base insulating film, and then first heat treatment is performed to form a second oxide semiconductor film. Then, selective etching is performed to form a third oxide semiconductor film. An insulating film is formed over the first insulating film and the third oxide semiconductor film. A surface of the insulating film is polished to expose a surface of the third oxide semiconductor film, so that a sidewall insulating film is formed in contact with at least a side surface of the third oxide semiconductor film. Then, a source electrode and a drain electrode are formed over the sidewall insulating film and the third oxide semiconductor film. A gate insulating film and a gate electrode are formed.
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Citations
29 Claims
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1. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first insulating film over a substrate; forming a first oxide semiconductor film over the first insulating film; forming a depression in the first insulating film and forming a second oxide semiconductor film by selectively etching the first insulating film and the first oxide semiconductor film; forming a second insulating film over the first insulating film and the second oxide semiconductor film; forming a third insulating film over the second insulating film; forming a fourth insulating film in contact with side surfaces of the depression and the second oxide semiconductor film, and a fifth insulating film in contact with a side surface of the fourth insulating film by polishing the second insulating film and the third insulating film so that the fourth insulating film and the fifth insulating film are provided in the depression; forming a source electrode and a drain electrode over the second oxide semiconductor film; forming a sixth insulating film over the second oxide semiconductor film, the source electrode, and the drain electrode; and forming a gate electrode over the sixth insulating film. - 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 a first insulating film over a substrate; forming a first oxide semiconductor film over the first insulating film; forming a second oxide semiconductor film by selectively etching the first oxide semiconductor film; forming a second insulating film over the first insulating film and the second oxide semiconductor film; forming a third insulating film over the second insulating film; forming a fourth insulating film by polishing a surface of the third insulating film so that the second insulating film is exposed; forming a fifth insulating film by etching the second insulating film so that the second oxide semiconductor film is exposed; forming a source electrode and a drain electrode over the second oxide semiconductor film; forming a sixth insulating film over the second oxide semiconductor film, the source electrode, and the drain electrode; and forming a gate electrode overlapping with the second oxide semiconductor film, over the sixth insulating film. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for manufacturing a semiconductor device comprising the steps of:
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forming a first insulating film over a substrate; forming a first oxide semiconductor film over the first insulating film; forming a second oxide semiconductor film by selectively etching the first oxide semiconductor film; forming a second insulating film over the first insulating film and the second oxide semiconductor film; forming a third insulating film by polishing a surface of the second insulating film so that the second oxide semiconductor film is exposed; forming a first conductive film over the third insulating film and the second oxide semiconductor film; forming a first resist mask over the first conductive film; forming a pair of second conductive films by selectively etching the first conductive film with use of the first resist mask; forming a second resist mask and exposing at least part of regions which are in the pair of second conductive films and overlap with the second oxide semiconductor film by shrinking the first resist mask; forming a source electrode and a drain electrode which each comprise a region having a first thickness and a region having a second thickness that is smaller than the first thickness by etching part of the pair of second conductive films with use of the second resist mask; forming a fourth insulating film over the second oxide semiconductor film, the source electrode, and the drain electrode; forming a gate electrode overlapping with the second oxide semiconductor film, over the fourth insulating film; forming a first oxide semiconductor region overlapping with the gate electrode, a pair of second oxide semiconductor regions between which the first oxide semiconductor region is sandwiched, a pair of third oxide semiconductor regions overlapping with at least the regions having the first thickness, and a pair of fourth oxide semiconductor regions overlapping with the regions having the second thickness by adding a dopant to the second oxide semiconductor film. - View Dependent Claims (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 a first insulating film over a substrate; forming a first oxide semiconductor film over the first insulating film; forming a depression in the first insulating film and forming a second oxide semiconductor film by selectively etching the first insulating film and the first oxide semiconductor film; forming a second insulating film over the first insulating film and the second oxide semiconductor film; forming a third insulating film over the second insulating film; forming a fourth insulating film in contact with side surfaces of the depression and the second oxide semiconductor film, and a fifth insulating film in contact with a side surface of the fourth insulating film by polishing the second insulating film and the third insulating film so that the fourth insulating film and the fifth insulating film are provided in the depression; forming a source electrode and a drain electrode over the second oxide semiconductor film; forming a sixth insulating film over the second oxide semiconductor film, the source electrode, and the drain electrode; and forming a gate electrode over the sixth insulating film, wherein the fourth insulating film contains oxygen at a ratio exceeding a ratio of oxygen in a stoichiometric composition of the fourth insulating film. - View Dependent Claims (28, 29)
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Specification