SEMICONDUCTOR DEVICE
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Accused Products
Abstract
At least one of a plurality of transistors which are highly integrated in an element is provided with a back gate without increasing the number of manufacturing steps. In an element including a plurality of transistors which are longitudinally stacked, at least a transistor in an upper portion includes a metal oxide having semiconductor characteristics, a same layer as a gate electrode of a transistor in a lower portion is provided to overlap with a channel formation region of the transistor in an upper portion, and part of the same layer as the gate electrode functions as a back gate of the transistor in an upper portion. The transistor in a lower portion which is covered with an insulating layer is subjected to planarization treatment, whereby the gate electrode is exposed and connected to a layer functioning as source and drain electrodes of the transistor in an upper portion.
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Citations
25 Claims
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1. (canceled)
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2. A semiconductor device comprising a circuit, the circuit comprising:
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a first transistor comprising a first semiconductor layer and a first gate electrode; an insulating layer over at least a part of the first transistor; and a second transistor comprising a back gate electrode, a second semiconductor layer over the back gate electrode and a second gate electrode over the second semiconductor layer, wherein the first transistor is electrically connected to the second transistor, wherein the back gate electrode is configured to control a threshold voltage of the second transistor, wherein the second semiconductor layer includes an oxide semiconductor layer, and wherein the first semiconductor layer includes a silicon layer. - View Dependent Claims (3, 4, 5, 6, 7, 8, 9)
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10. A semiconductor device comprising a circuit, the circuit comprising:
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a first transistor comprising a first semiconductor layer and a first gate electrode; an insulating layer over at least a part of the first transistor; and a second transistor comprising a back gate electrode, a second semiconductor layer over the back gate electrode and a second gate electrode over the second semiconductor layer, wherein the back gate electrode is configured to control a threshold voltage of the second transistor, wherein the insulating layer is interposed between the second semiconductor layer and the back gate electrode, wherein the second semiconductor layer includes an oxide semiconductor layer, wherein the back gate electrode is formed from a same layer as the first gate electrode, and wherein the first semiconductor layer includes a silicon layer. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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18. A semiconductor device comprising a circuit, the circuit comprising:
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a first transistor comprising a first semiconductor layer, a first gate electrode and a first back gate electrode; an insulating layer over at least a part of the first transistor; and a second transistor comprising a second back gate electrode, a second semiconductor layer over the second back gate electrode and a second gate electrode over the second semiconductor layer, wherein the second back gate electrode is configured to control a threshold voltage of the second transistor, wherein the insulating layer is interposed between the second semiconductor layer and the second back gate electrode, wherein the second semiconductor layer includes an oxide semiconductor layer, wherein the second back gate electrode is formed from a same layer as the first gate electrode, and wherein the first semiconductor layer includes a silicon layer. - View Dependent Claims (19, 20, 21, 22, 23, 24, 25)
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Specification