Solid-state imaging device and imaging system
A solid-state imaging device including a plurality of pixels including a photoelectric conversion portion, a charge holding portion accumulating a signal charge transferred from the photoelectric conversion portion, and a floating diffusion region to which the signal charge of the charge holding portion is transferred, wherein the photoelectric conversion portion includes a first semiconductor region of a first conductivity type, and a second semiconductor region of a second conductivity type formed under the first semiconductor region, the charge holding portion includes a third semiconductor region of the first conductivity type, and a fourth semiconductor region of the second conductivity type formed under the third semiconductor region, and a p-n junction between the third semiconductor region and the fourth semiconductor region is positioned deeper than a p-n junction between the first semiconductor region and the second semiconductor region.
1. A solid-state imaging device comprising:
a plurality of pixels each of which includes:
a photoelectric conversion portion which photoelectrically converts incident light to generate a signal charge of a first polarity;
a charge holding portion that accumulates the signal charge transferred from the photoelectric conversion portion; and
a floating diffusion region to which the signal charge of the charge holding portion is transferred, wherein:
the photoelectric conversion portion includes a first semiconductor region of a first conductivity type including carriers of a second polarity as a majority carrier, and a second semiconductor region of a second conductivity type including carriers of the first polarity as a majority carrier formed under the first semiconductor region,
the charge holding portion includes a third semiconductor region of the first conductivity type, and a fourth semiconductor region of the second conductivity type formed under the third semiconductor region, and
a p-n junction between the third semiconductor region and the fourth semiconductor region is positioned deeper than a p-n junction between the first semiconductor region and the second semiconductor region.
2. The solid-state imaging device according to claim 1 , wherein the photoelectric conversion portion further has a fifth semiconductor region which is formed in contact with an end of the first semiconductor region at a side of the charge holding portion, and has a lower impurity concentration than the first semiconductor region.
3. The solid-state imaging device according to claim 2 , further comprising:
a transistor which controls a transfer of the signal charge from the photoelectric conversion portion to the charge holding portion,
wherein the fifth semiconductor region extends to a region below a gate electrode of the transistor.
4. The solid-state imaging device according to claim 1 , wherein the charge holding portion further has a fifth semiconductor region of the second conductivity type, which is arranged in a vicinity of an end of the third semiconductor region at a side of the floating diffusion region.
5. The solid-state imaging device according to claim 4 , further comprising:
a transistor which controls a transfer of the signal charge from the charge holding portion to the floating diffusion region,
wherein the fifth semiconductor region extends to a region below a gate electrode of the transistor.
6. The solid-state imaging device according to claim 1 , wherein the charge holding portion further has a fifth semiconductor region of the second conductivity type, which is arranged in a vicinity of an end of the third semiconductor region at a side of the photoelectric conversion portion.
7. The solid-state imaging device according to claim 6 , further comprising:
a transistor which controls a transfer of the signal charge from the photoelectric conversion portion to the charge holding portion,
wherein the fifth semiconductor region extends to a region below a gate electrode of the transistor.
8. The solid-state imaging device according to claim 1 , wherein an area of the charge holding portion is larger than an area of the photoelectric conversion portion.
9. The solid-state imaging device according to claim 1 , wherein the charge holding portion further has a fifth semiconductor region of the first conductivity type, which is formed in contact with a bottom of the fourth semiconductor region.
10. The solid-state imaging device according to claim 1 , further comprising:
a transistor which controls a transfer of the signal charge from the photoelectric conversion portion to the charge holding portion,
wherein a gate electrode of the transistor extends to an upper part of the charge holding portion.
11. An imaging system comprising:
the solid-state imaging device according to claim 1 ; and
an optical system which forms an object image on the solid-state imaging device.
12. A solid-state imaging device comprising:
a plurality of pixels each of which includes:
a photoelectric conversion portion which photoelectrically converts incident light to generate a signal charge of a first polarity;
a charge holding portion that accumulates the signal charge transferred from the photoelectric conversion portion; and
a floating diffusion region to which the signal charge of the charge holding portion is transferred, wherein:
the photoelectric conversion portion includes a first semiconductor region of a first conductivity type including carriers of a second polarity as a majority carrier, and a second semiconductor region of a second conductivity type including carriers of the first polarity as a majority carrier formed under the first semiconductor region,
the charge holding portion includes a third semiconductor region of the first conductivity type, and a fourth semiconductor region of the second conductivity type formed under the third semiconductor region, and
the third semiconductor region has a higher impurity concentration than the first semiconductor region.
13. The solid-state imaging device according to claim 12 , wherein the photoelectric conversion portion further has a fifth semiconductor region which is formed in contact with an end of the first semiconductor region at a side of the charge holding portion, and has a lower impurity concentration than the first semiconductor region.
14. The solid-state imaging device according to claim 13 , further comprising:
a transistor which controls a transfer of the signal charge from the photoelectric conversion portion to the charge holding portion,
wherein the fifth semiconductor region extends to a region below a gate electrode of the transistor.
15. The solid-state imaging device according to claim 12 , wherein the charge holding portion further has a fifth semiconductor region of the second conductivity type, which is arranged in a vicinity of an end of the third semiconductor region at a side of the floating diffusion region.
16. The solid-state imaging device according to claim 15 , further comprising:
a transistor which controls a transfer of the signal charge from the charge holding portion to the floating diffusion region, wherein
the fifth semiconductor region extends to a region below a gate electrode of the transistor.
17. The solid-state imaging device according to claim 12 , wherein the charge holding portion further has a fifth semiconductor region of the second conductivity type, which is arranged in a vicinity of an end of the third semiconductor region at a side of the photoelectric conversion portion.
18. The solid-state imaging device according to claim 17 , further comprising:
a transistor which controls a transfer of the signal charge from the photoelectric conversion portion to the charge holding portion, wherein
the fifth semiconductor region extends to a region below a gate electrode of the transistor.
19. The solid-state imaging device according to claim 12 , wherein an area of the charge holding portion is larger than an area of the photoelectric conversion portion.
20. The solid-state imaging device according to claim 12 , wherein the charge holding portion further has a fifth semiconductor region of the first conductivity type, which is formed in contact with a bottom of the fourth semiconductor region.
21. The solid-state imaging device according to claim 12 , further comprising:
a transistor which controls a transfer of the signal charge from the photoelectric conversion portion to the charge holding portion,
wherein a gate electrode of the transistor extends to an upper part of the charge holding portion.
22. An imaging system comprising:
the solid-state imaging device according to claim 12 ; and
an optical system which forms an object image on the solid-state imaging device.