Image sensor and image-capturing apparatus

1. An image sensor comprising:

a plurality of pixels each having a photoelectric conversion unit that converts light into an electric charge, the light being incident from one side of a substrate, and an output unit that outputs at least one of a signal caused by the electric charge and a noise signal, the plurality of pixels being provided in a first direction and a second direction intersecting the first direction;

a holding unit provided on a side of the substrate opposite to the one side of the substrate, the holding unit including a signal holding unit that holds the signal caused by the electric charge and a noise holding unit that holds the noise signal; and

a first wiring which is provided between the signal holding unit and the noise holding unit and to which a predetermined potential is applied.

2. The image sensor according to claim 1 , further comprising:

a signal line which is provided on the opposite side of the substrate and to which the at least one signal is output from the plurality of pixels provided in the first direction, wherein:

the holding unit holds the at least one signal output to the signal line.

3. The image sensor according to claim 1 , wherein:

the plurality of pixels are provided in a semiconductor substrate;

the light is incident from a first surface of the semiconductor substrate; and

the output unit is provided on a second surface of the semiconductor substrate opposite to the first surface.

4. The image sensor according to claim 1 , wherein:

the holding unit is connected to the plurality of pixels.

5. The image sensor according to claim 1 , further comprising:

a second wiring which is provided between the output unit and the holding unit and to which the predetermined potential is applied; and

a third wiring which is provided via the holding unit and an insulating film and to which the predetermined potential is applied.

6. The image sensor according to claim 1 , wherein:

the holding unit includes a first holding unit connected to a first plurality of the plurality of pixels provided in the first direction, and a second holding unit connected to a second plurality of the plurality of pixels that are provided in the first direction and that are different from the plurality of pixels connected to the first holding unit, the second plurality of pixels being different from the first plurality of pixels; and

a plurality of first holding units each corresponding to the first holding unit and a plurality of second holding units each corresponding to the second holding unit are provided side by side in the second direction.

7. The image sensor according to claim 1 , wherein:

the holding unit includes a first holding unit connected to a partial plurality of pixels among the plurality of pixels provided in the first direction, and a second holding unit connected to another partial plurality of pixels among the plurality of pixels provided in the first direction.

8. The image sensor according to claim 1 , wherein

the holding unit is provided between the plurality of pixels.

9. The image sensor according to claim 8 , wherein:

the image sensor has a signal line to which signals are output from the plurality of pixels provided in the first direction; and

the holding unit is provided between the plurality of pixels provided in the second direction and holds the signals output to the signal line.

10. The image sensor according to claim 1 , wherein

the plurality of pixels are provided between a surface on which the light is incident and the holding unit.

11. The image sensor according to claim 1 , further comprising:

a semiconductor layer having the plurality of pixels; and

a wiring layer which is formed on a surface of the semiconductor layer opposite to a surface of the semiconductor layer on which the light is incident and where the holding unit is provided.

12. The image sensor according to claim 1 , wherein:

the holding unit has a capacitance formed by conductors.

13. An image-capturing apparatus comprising:

the image sensor according to claim 1 , and

an image generation unit that generates image data based on the signal caused by the electric charge of the image sensor.

14. The image sensor according to claim 1 , wherein:

the first wiring is provided between the plurality of pixels and the holding unit.

15. The image sensor according to claim 1 , wherein:

the output unit has an accumulation unit that accumulates the electric charge converted by the photoelectric conversion unit, a transfer unit that transfers the electric charge to the accumulation unit, and a reset unit that resets the electric charge accumulated in the accumulation unit.

16. The image sensor according to claim 15 , wherein:

the noise signal is a signal at a time of resetting the electric charge accumulated in the accumulation unit.

17. The image sensor according to claim 1 , wherein:

the holding unit is stacked on the photoelectric conversion unit on the side opposite to the one side of the substrate.

18. The image sensor according to claim 1 , further comprising:

a first layer having the photoelectric conversion unit and the output unit; and

a second layer stacked on the first layer and having the holding unit.

19. The image sensor according to claim 1 , further comprising:

an accumulation unit that accumulates the electric charge; and

a reset unit that resets the electric charge accumulated in the accumulation unit, wherein:

the noise holding unit holds a signal at a time of resetting the electric charge accumulated in the accumulation unit by the reset unit.