Semiconductor device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorsAtsuo ISOBE, Toshinari SASAKI
Life of this patent
Estimating the term…
Abstract
To provide a highly reliable semiconductor device. To provide a semiconductor device which prevents a defect and achieves miniaturization. An oxide semiconductor layer in which the thickness of a region serving as a source region or a drain region is larger than the thickness of a region serving as a channel formation region is formed in contact with an insulating layer including a trench. In a transistor including the oxide semiconductor layer, variation in threshold voltage, degradation of electric characteristics, and shift to normally on can be suppressed and source resistance or drain resistance can be reduced, so that the transistor can have high reliability.
Claims16
A semiconductor device comprising:
- a trench in an insulating layer;
- a wide-gap semiconductor layer in contact with an uppermost surface of the insulating layer and an inner wall surface and a bottom surface of the trench;
- a source electrode and a drain electrode electrically connected to the wide-gap semiconductor layer;
- a gate insulating layer over the wide-gap semiconductor layer;
- and
- a gate electrode over the gate insulating layer,
- wherein each of a first thickness of the wide-gap semiconductor layer in contact with the inner wall surface and a second thickness of the wide-gap semiconductor layer in contact with the bottom surface is smaller than a third thickness of the wide-gap semiconductor layer in contact with the uppermost surface of the insulating layer, and
- wherein the trench is filled with the gate electrode.
A semiconductor device comprising:
- a first transistor;
- and
- a second transistor, the second transistor comprising:
- a trench in an insulating layer;
- a wide-gap semiconductor layer in contact with an uppermost surface of the insulating layer and an inner wall surface and a bottom surface of the trench;
- a source electrode and a drain electrode electrically connected to the wide-gap semiconductor layer;
- a gate insulating layer over the wide-gap semiconductor layer;
- and
- a gate electrode over the gate insulating layer,
- wherein the first transistor overlaps with at least a part of the second transistor,
- wherein each of a first thickness of the wide-gap semiconductor layer in contact with the inner wall surface and a second thickness of the wide-gap semiconductor layer in contact with the bottom surface is smaller than a third thickness of the wide-gap semiconductor layer in contact with the uppermost surface of the insulating layer, and
- wherein the trench is filled with the gate electrode.
A method for manufacturing a semiconductor device, comprising the steps of:
- forming an insulating layer over a substrate;
- forming a trench in the insulating layer;
- forming a wide-gap semiconductor layer so as to be in contact with an uppermost surface of the insulating layer and an inner wall surface and a bottom surface of the trench;
- forming a source electrode and a drain electrode over the wide-gap semiconductor layer;
- forming a gate insulating layer over the wide-gap semiconductor layer, the source electrode, and the drain electrode;
- and
- forming a gate electrode over the insulating layer so that the trench is filled with the gate electrode,
- wherein each of a first thickness of the wide-gap semiconductor layer in contact with the inner wall surface and a second thickness of the wide-gap semiconductor layer in contact with the bottom surface is smaller than a third thickness of the wide-gap semiconductor layer in contact with the uppermost surface of the insulating layer.
A method for manufacturing a semiconductor device, comprising the steps of:
- forming a first transistor with using a substrate comprising a semiconductor material;
- and
- forming a second transistor, the method for forming the second transistor comprising the steps of:
- forming an insulating layer over the transistor;
- forming a trench in the insulating layer;
- forming a wide-gap semiconductor layer so as to be in contact with an uppermost surface of the insulating layer and an inner wall surface and a bottom surface of the trench;
- forming a source electrode and a drain electrode over the wide-gap semiconductor layer;
- forming a gate insulating layer over the wide-gap semiconductor layer, the source electrode, and the drain electrode;
- and
- forming a gate electrode over the insulating layer so that the trench filled with the gate electrode;
- wherein the first transistor overlaps with at least a part of the second transistor, and
- wherein each of a first thickness of the wide-gap semiconductor layer in contact with the inner wall surface and a second thickness of the wide-gap semiconductor layer in contact with the bottom surface is smaller than a third thickness of the wide-gap semiconductor layer in contact with the uppermost surface of the insulating layer.
Dependencies are inferred from the claim text.