Back-illuminated type solid-state imaging device
View Patent ↗A back-illuminated type solid-state imaging device is provided in which an electric field to collect a signal charge (an electron, a hole and the like, for example) is reliably generated to reduce a crosstalk. The back-illuminated type solid-state imaging device includes a structure 34 having a semiconductor film 33 on a semiconductor substrate 31 through an insulation film 32 , in which a photoelectric conversion element PD that constitutes a pixel is formed in the semiconductor substrate 31 , at least part of transistors 15, 16 , and 19 that constitute the pixel is formed in the semiconductor film 33 , and a rear surface electrode 51 to which a voltage is applied is formed on the rear surface side of the semiconductor substrate 31.
1. A back-illuminated type solid-state imaging device comprising:
a semiconductor layer on a front surface side of a semiconductor substrate with an insulation film between them;
a photoelectric conversion element that constitutes a pixel in said semiconductor substrate, the photoelectric conversion element including a charge accumulation portion, the charge accumulation portion includes a plurality of impurity regions and a high impurity region formed directly between the plurality of impurity regions;
at least part of transistors that constitute said pixel are included in said semiconductor film; and
a rear surface electrode on the rear surface side of said semiconductor substrate to which a negative voltage is applied, the rear surface electrode being transparent,
wherein,
a semiconductor layer of an opposite conduction type to the charge accumulation portion of said photoelectric conversion element is formed in a portion of the semiconductor substrate under said insulation film, and
a semiconductor layer of an opposite conduction type to a charge accumulation portion of said photoelectric conversion element is formed in the semiconductor substrate under said insulation film.
2. The back-illuminated type solid-state imaging device according to claim 1 , wherein:
the semiconductor substrate is a high resistance substrate, and
the transistors include a reset transistor, an amplifier transistor, and a selector transistor.
3. The back-illuminated type solid-state imaging device according to claim 2 , wherein a source of the reset transistor is connected to the photoelectric conversion element.
4. The back-illuminated type solid-state imaging device according to claim 3 , wherein:
the electrically floating semiconductor layer is connected between the photoelectric conversion element and the source of the reset transistor, and
the source of the reset transistor is connected to a gate of the amplifier transistor.
5. The back-illuminated type solid-state imaging device according to claim 4 , wherein
a drain of the reset transistor is connected to a power wiring and
a gate of the reset transistor is connected to reset wiring through which a reset pulse is received.
6. The back-illuminated type solid-state imaging device according to claim 5 , wherein:
a drain of the amplifier transistor is connected to the power wiring, and
a source of the amplifier transistor is connected to a drain of the selector transistor.
7. The back-illuminated type solid-state imaging device according to claim 6 , wherein:
a selector wiring is connected to a gate of the selector transistor,
a source of the selector transistor is connected to a vertical signal line,
a gate of a load transistor is connected to the vertical signal line, and
a gate of the load transistor is connected to a load wiring.
8. The back-illuminated type solid-state imaging device according to claim 2 , wherein the reset transistor resets a signal charge of the electrically floating semiconductor layer by discharging the signal charge of the electrically floating semiconductor layer into power wiring.
9. The back-illuminated type solid-state imaging device according to claim 2 , wherein:
source-drain regions of the reset transistor, the amplifier transistor, and
the selector transistor are of formed in the charge accumulation region, the charge accumulation region is of n-type.
10. The back-illuminated type solid-state imaging device according to claim 1 , wherein the semiconductor layer of the opposite conduction type is of p-type.
11. The back-illuminated type solid-state imaging device according to claim 9 , wherein:
the p-type semiconductor layer has an impurity concentration of approximately 10 18 cm −3 , and
an impurity concentration of the high resistance substrate is between 10 12 cm −3 and 10 15 cm −3 .
12. The back-illuminated type solid-state imaging device according to claim 1 , wherein the negative voltage is applied to generate a large electric field to collect photoelectrons into the charge accumulation portion.