Method for manufacturing semiconductor device
First Claim
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1. A method for manufacturing a semiconductor device, comprising the steps of:
- forming a gate electrode;
forming a gate insulating film over the gate electrode;
forming a semiconductor film which is over the gate insulating film; and
forming a pair of electrodes over the gate insulating film so that the pair of electrodes does not overlap with the gate electrode and is in contact with the semiconductor film,wherein a thickness of the gate electrode is selected so that a channel length is three times or more as long as an apparent channel length which is a distance between the pair of electrodes when seen from above.
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Abstract
A method for forming a U-shaped vertically long groove in a region where a channel portion of a transistor is formed to make a channel length longer than an apparent channel length additionally requires a photolithography process for forming a groove; therefore, it has a problem in terms of costs and yield. By forming a three-dimensional channel region with the use of a gate electrode or a structure having an insulating surface, a channel length is made three times or more, preferably five times or more, further preferably ten times or more as long as a channel length when seen from the above.
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Citations
15 Claims
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1. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a gate electrode; forming a gate insulating film over the gate electrode; forming a semiconductor film which is over the gate insulating film; and forming a pair of electrodes over the gate insulating film so that the pair of electrodes does not overlap with the gate electrode and is in contact with the semiconductor film, wherein a thickness of the gate electrode is selected so that a channel length is three times or more as long as an apparent channel length which is a distance between the pair of electrodes when seen from above. - View Dependent Claims (2, 3, 4, 5)
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6. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a first gate electrode; forming a second gate electrode over the first gate electrode so that a top surface of the second gate electrode is smaller than a top surface of the first gate electrode; forming a gate insulating film over the second gate electrode; forming a semiconductor film which is over the gate insulating film; and forming a pair of electrodes over the gate insulating film so that the pair of electrodes does not overlap with the second gate electrode and is in contact with the semiconductor film, wherein a thickness of the first gate electrode is selected so that a channel length is three times or more as long as an apparent channel length which is a distance between the pair of electrodes when seen from above. - View Dependent Claims (7, 8, 9, 10)
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11. A method for manufacturing a semiconductor device, comprising the steps of:
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forming a structure comprising an insulating surface; forming a semiconductor film over the structure; forming a pair of electrodes over the insulating surface so that the pair of electrodes does not overlap with a gate electrode and is in contact with the semiconductor film; forming a gate insulating film over the structure; and forming the gate electrode over the gate insulating film, wherein a thickness of the structure is selected so that a channel length is three times or more as long as an apparent channel length which is a distance between the pair of electrodes when seen from above. - View Dependent Claims (12, 13, 14, 15)
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Specification