Semiconductor device and method for manufacturing semiconductor device having oxide semiconductor layer
First Claim
1. A semiconductor device comprising:
- a base insulating layer over a substrate;
a transistor over the base insulating layer, the transistor comprising;
an oxide semiconductor layer over the base insulating layer, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen;
a source electrode and a drain electrode in contact with the oxide semiconductor layer;
a first gate insulating layer over and in contact with the oxide semiconductor layer;
a second gate insulating layer over the first gate insulating layer; and
a gate electrode overlapping with the oxide semiconductor layer over the second gate insulating layer; and
a capacitor comprising;
a first electrode;
a portion of the oxide semiconductor layer over the first electrode;
a dielectric layer over the portion of the oxide semiconductor layer over the first electrode;
a second electrode over the dielectric layer, wherein the first electrode and the second electrode overlap each other with the dielectric layer and the portion of the oxide semiconductor layer interposed therebetween,wherein the second gate insulating layer has higher relative permittivity than the first gate insulating layer.
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Abstract
In a miniaturized transistor, a gate insulating layer is required to reduce its thickness; however, in the case where the gate insulating layer is a single layer of a silicon oxide film, a physical limit on thinning of the gate insulating layer might occur due to an increase in tunneling current, i.e. gate leakage current. With the use of a high-k film whose relative permittivity is higher than or equal to 10 is used for the gate insulating layer, gate leakage current of the miniaturized transistor is reduced. With the use of the high-k film as a first insulating layer whose relative permittivity is higher than that of a second insulating layer in contact with an oxide semiconductor layer, the thickness of the gate insulating layer can be thinner than a thickness of a gate insulating layer considered in terms of a silicon oxide film.
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Citations
32 Claims
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1. A semiconductor device comprising:
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a base insulating layer over a substrate; a transistor over the base insulating layer, the transistor comprising; an oxide semiconductor layer over the base insulating layer, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen; a source electrode and a drain electrode in contact with the oxide semiconductor layer; a first gate insulating layer over and in contact with the oxide semiconductor layer; a second gate insulating layer over the first gate insulating layer; and a gate electrode overlapping with the oxide semiconductor layer over the second gate insulating layer; and a capacitor comprising; a first electrode; a portion of the oxide semiconductor layer over the first electrode; a dielectric layer over the portion of the oxide semiconductor layer over the first electrode; a second electrode over the dielectric layer, wherein the first electrode and the second electrode overlap each other with the dielectric layer and the portion of the oxide semiconductor layer interposed therebetween, wherein the second gate insulating layer has higher relative permittivity than the first gate insulating layer. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device comprising:
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a transistor comprising; a gate electrode over a substrate; a first gate insulating layer over the gate electrode; a second gate insulating layer over the first gate insulating layer; an oxide semiconductor layer over and in contact with the second gate insulating layer, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen; and a source electrode and a drain electrode in contact with the oxide semiconductor layer; and an insulating layer over and in contact with the oxide semiconductor layer, wherein the first gate insulating layer has higher relative permittivity than the second gate insulating layer. - View Dependent Claims (9, 10, 11, 12, 13)
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14. A semiconductor device comprising:
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a transistor comprising; a first gate electrode over a substrate; a first gate insulating layer provided so as to be over and in contact with the first gate electrode; a second gate insulating layer provided so as to be over and in contact with the first gate insulating layer; an oxide semiconductor layer provided so as to be over and in contact with the second gate insulating layer, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen; a source electrode and a drain electrode in contact with the oxide semiconductor layer; a third gate insulating layer provided so as to be over and in contact with the oxide semiconductor layer; a fourth gate insulating layer provided so as to be over and in contact with the third gate insulating layer; and a second gate electrode overlapping with the first gate electrode and over and in contact with the fourth gate insulating layer, wherein the first gate insulating layer has higher relative permittivity than the second gate insulating layer, and wherein the fourth gate insulating layer has higher relative permittivity than the third gate insulating layer. - View Dependent Claims (15, 16, 17, 18)
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19. A method for manufacturing a semiconductor device comprising a transistor, the method comprising the steps of:
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forming a gate electrode over a substrate; forming a first gate insulating layer over the gate electrode; forming a second gate insulating layer over the first gate insulating layer; forming an oxide semiconductor layer over and in contact with the second gate insulating layer, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen; and forming a source electrode and a drain electrode in contact with the oxide semiconductor layer; wherein the first gate insulating layer has higher relative permittivity than the second gate insulating layer, and wherein the transistor comprises the gate electrode over the substrate, the first gate insulating layer over the gate electrode, the second gate insulating layer over the first gate insulating layer, the oxide semiconductor layer over and in contact with the second gate insulating layer, and the source electrode and the drain electrode in contact with the oxide semiconductor layer. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26)
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27. A method for manufacturing a semiconductor device comprising a transistor, the method comprising the steps of:
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forming a source electrode and a drain electrode over a substrate; forming an oxide semiconductor layer of the transistor over and in electrical contact with the source electrode and the drain electrode, the oxide semiconductor layer comprising a channel formation region, wherein the channel formation region comprises indium and oxygen; forming a first gate insulating layer of the transistor over and in contact with the oxide semiconductor layer; forming a second gate insulating layer of the transistor over the first gate insulating layer; forming a gate electrode of the transistor over the second gate insulating layer; and forming an electrode over the second gate insulating layer to form a capacitor between the electrode and a portion of one of the source electrode and the drain electrode with the oxide semiconductor layer, the first gate insulating layer and the second gate insulating layer interposed therebetween; wherein the second gate insulating layer has higher relative permittivity than the first gate insulating layer. - View Dependent Claims (28, 29, 30, 31, 32)
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Specification