Imaging device and electronic device
An imaging device which has a stacked-layer structure and can be manufactured easily is provided. The imaging device includes a signal processing circuit, a memory device, and an image sensor. The imaging device has a stacked-layer structure in which the memory device is provided above the signal processing circuit, and the image sensor is provided above the memory device. The signal processing circuit includes a transistor formed on a first semiconductor substrate, the memory device includes a transistor including a metal oxide in a channel formation region, and the image sensor includes a transistor formed on a second semiconductor substrate.
1. An imaging device comprising:
a first layer;
a second layer above the first layer; and
a third layer above the second layer,
wherein the first layer comprises a signal processing circuit,
wherein the second layer comprises a memory device,
wherein the third layer comprises an image sensor,
wherein the signal processing circuit comprises a first transistor formed on a first semiconductor substrate,
wherein the memory device comprises a second transistor comprising a metal oxide in a channel formation region,
wherein the image sensor comprises a plurality of pixels each comprising a third transistor and a photodiode,
wherein a semiconductor region of the third transistor comprises a first region of a second semiconductor substrate, and
wherein a semiconductor region of the photodiode comprises a second region of the second semiconductor substrate.
2. The imaging device according to claim 1 ,
wherein the signal processing circuit is configured to control operation of the memory device and the image sensor.
3. The imaging device according to claim 1 ,
wherein at least one of the signal processing circuit and the image sensor comprises an analog-digital conversion circuit, and
wherein the analog-digital conversion circuit is configured to convert image data generated by the image sensor to a digital signal.
4. The imaging device according to claim 3 ,
wherein the memory device is configured to retain the digital signal.
5. An imaging device comprising:
a first layer;
a second layer above the first layer; and
a third layer above the second layer,
wherein the first layer comprises a signal processing circuit,
wherein the second layer comprises a memory device,
wherein the third layer comprises an image sensor,
wherein the signal processing circuit comprises a first transistor formed on a first semiconductor substrate,
wherein the memory device comprises a plurality of memory cells,
wherein each of the plurality of the memory cells comprises a second transistor and a capacitor,
wherein one of a source and a drain of the second transistor is electrically connected to a first electrode of the capacitor,
wherein the second transistor comprises a metal oxide in a channel formation region,
wherein the image sensor comprises a plurality of pixels each comprising a third transistor and a photodiode formed on a second semiconductor substrate, and
wherein the third transistor is stacked over the second transistor and the capacitor.
6. The imaging device according to claim 5 ,
wherein the signal processing circuit is configured to control operation of the memory device and the image sensor.
7. The imaging device according to claim 5 ,
wherein at least one of the signal processing circuit and the image sensor comprises an analog-digital conversion circuit, and
wherein the analog-digital conversion circuit is configured to convert image data generated by the image sensor to a digital signal.
8. The imaging device according to claim 7 ,
wherein the memory device is configured to retain the digital signal.