Method for manufacturing semiconductor device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsYuta Endo, Kosei Noda
Life of this patent
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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.
Claims15
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.
A method for manufacturing a semiconductor device, comprising the steps of:
- 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.
A method for manufacturing a semiconductor device, comprising the steps of:
- 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.
Dependencies are inferred from the claim text.