Semiconductor device
AssigneeSemiconductor Energy Laboratory Co., Ltd.
InventorShunpei YAMAZAKI
Life of this patent
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Abstract
Disclosed is a semiconductor device capable of functioning as a memory device. The memory device comprises a plurality of memory cells, and each of the memory cells contains a first transistor and a second transistor. The first transistor is provided over a substrate containing a semiconductor material and has a channel formation region in the substrate. The second transistor has an oxide semiconductor layer. The gate electrode of the first transistor and one of the source and drain electrodes of the second transistor are electrically connected to each other. The extremely low off current of the second transistor allows the data stored in the memory cell to be retained for a significantly long time even in the absence of supply of electric power.
Claims21
(canceled)
A semiconductor device comprising:
- a first transistor comprising a first gate electrode;
- and
- a second transistor comprising a second source electrode and a second drain electrode,
- wherein the second transistor includes an oxide semiconductor layer, the oxide semiconductor layer including a channel formation region, the channel formation region of the second transistor being intrinsic or substantially intrinsic,
- wherein the first gate electrode and one of the second source electrode and the second drain electrode are electrically connected to each other, and
- wherein an off current of the second transistor is 1×10−20 A or less.
A semiconductor device comprising:
- a first transistor comprising a first gate electrode;
- an insulating layer over the first transistor;
- and
- a second transistor comprising:
- an oxide semiconductor layer over the insulating layer;
- a gate insulating layer adjacent to the oxide semiconductor layer;
- and
- a second gate electrode adjacent to the oxide semiconductor layer with the gate insulating layer therebetween;
- wherein the first gate electrode and one of a source and a drain of the second transistor are electrically connected to each other,
- wherein the oxide semiconductor layer includes a channel formation region, and
- wherein the oxide semiconductor layer contains hydrogen at a concentration 5×1019 atoms/cm3 or less.
A semiconductor device comprising:
- a first transistor comprising a first gate electrode;
- and
- a second transistor comprising a second gate electrode, a second source electrode and a second drain electrode,
- a first signal line electrically connected to one of the second source electrode and the second drain electrode;
- a second signal line electrically connected to the second gate electrode,
- wherein the second transistor includes an oxide semiconductor layer, the oxide semiconductor layer including a channel formation region,
- wherein the first gate electrode and the other one of the second source electrode and the second drain electrode are electrically connected to each other, and
- wherein an off current of the second transistor is 1×10−20 A or less.
Dependencies are inferred from the claim text.