Charge transfer device

Abstract

A gate electrode region of a junction transistor in a signal charge-voltage converter is allowed to have a structure that a gentle potential gradient is formed without generation of a potential barrier. Thus, it is possible to readily realize a signal charge-voltage converter which is high in S/N ratio without generation of reset noise and is excellent in signal charge-voltage conversion efficiency.

Description

BRIEF DESCRIPTION OF THE INVENTION

FIG. 1 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a first embodiment of the present invention;

FIG. 2 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the first embodiment, in a direction perpendicular to a charge transfer direction;

FIG. 3 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the first embodiment, in a direction parallel with the charge transfer direction;

FIG. 4 shows potential distribution in electron transfer performed by the charge transfer device according to the first embodiment;

FIG. 5 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a second embodiment of the present invention;

FIG. 6 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the second embodiment, in a direction parallel with a charge transfer direction;

FIG. 7 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a third embodiment of the present invention;

FIG. 8 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the third embodiment, in a direction perpendicular to a charge transfer direction;

FIG. 9 shows potential distribution in signal conversion performed by the charge transfer device according to the third embodiment;

FIG. 10 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a fourth embodiment of the present invention;

FIG. 11 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the fourth embodiment, in a direction perpendicular to a charge transfer direction;

FIG. 12 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a fifth embodiment of the present invention;

FIG. 13 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the fifth embodiment, in a direction perpendicular to a charge transfer direction;

FIG. 14 shows potential distribution in signal conversion performed by the charge transfer device according to the fifth embodiment;

FIG. 15 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a sixth embodiment of the present invention;

FIG. 16 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the sixth embodiment, in a direction perpendicular to a charge transfer direction;

FIG. 17 shows potential distribution in signal conversion performed by the charge transfer device according to the sixth embodiment;

FIG. 18 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a seventh embodiment of the present invention;

FIG. 19 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the seventh embodiment, in a direction perpendicular to a charge transfer direction;

FIG. 20 shows potential distribution in signal conversion performed by the charge transfer device according to the seventh embodiment;

FIG. 21 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to an eighth embodiment of the present invention;

FIG. 22 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the eighth embodiment, in a direction parallel with a charge transfer direction;

FIG. 23 is a plan view schematically illustrating a signal charge-voltage converter in a charge transfer device according to a ninth embodiment of the present invention;

FIG. 24 is a sectional view illustrating the signal charge-voltage converter in the charge transfer device according to the ninth embodiment, in a direction parallel with a charge transfer direction; and

FIG. 25 is a plan view schematically illustrating a signal charge-voltage converter in a conventional charge transfer device.

Claims

1. A charge transfer device comprising: a semiconductor substrate;a horizontal transfer CCD transferring received signal charge in a horizontal direction;a signal charge-voltage converter converting the signal charge transferred from the horizontal transfer CCD into a signal voltage; anda reset drain discharging the signal charge,the horizontal transfer CCD, the signal charge-voltage converter and the reset drain being formed on the semiconductor substrate while adjoining to each other, whereinthe signal charge-voltage converter includes:a first conductive type first diffusion layer selectively formed on a surface of the semiconductor substrate;a second conductive type first diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with one of ends of the first conductive type first diffusion layer;a second conductive type second diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with the other end of the first conductive type first diffusion layer;a first gate electrode entirely formed over the first conductive type first diffusion layer, the second conductive type first diffusion layer and the second conductive type second diffusion layer with a first insulating film interposed therebetween;a second gate electrode formed at one of ends of the first gate electrode and on the first insulating film with a second insulating film interposed therebetween; anda third gate electrode formed at the other end of the first gate electrode and on the first insulating film with the second insulating film interposed therebetween, andthe first conductive type first diffusion layer extends to a portion located immediately below one of the second and third gate electrodes.

2. The charge transfer device according to claim 1, wherein the first conductive type first diffusion layer extends to portions located immediately below both the second and third gate electrodes.

3. A charge transfer device comprising: a semiconductor substrate;a horizontal transfer CCD transferring received signal charge in a horizontal direction;a signal charge-voltage converter converting the signal charge transferred from the horizontal transfer CCD into a signal voltage; anda reset drain discharging the signal charge,the horizontal transfer CCD, the signal charge-voltage converter and the reset drain being formed on the semiconductor substrate while adjoining to each other, whereinthe signal charge-voltage converter includes:a first conductive type first diffusion layer selectively formed on a surface of the semiconductor substrate;a second conductive type first diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with one of ends of the first conductive type first diffusion layer;a second conductive type second diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with the other end of the first conductive type first diffusion layer;a first gate electrode entirely formed over the first conductive type first diffusion layer, the second conductive type first diffusion layer and the second conductive type second diffusion layer with a first insulating film interposed therebetween;a second gate electrode formed at one of ends of the first gate electrode and on the first insulating film with a second insulating film interposed therebetween, the second gate electrode having a triangular notch formed at a center thereof adjoining to the first gate electrode; anda third gate electrode formed at the other end of the first gate electrode and on the first insulating film with the second insulating film interposed therebetween,the end of the first conductive type first diffusion layer is formed into a triangular shape corresponding with the triangular notch of the second gate electrode, andthe triangular notch of the second gate electrode has a side face opposing that of the triangular end of the first conductive type first diffusion layer in parallel, with the first insulating film interposed therebetween.

4. The charge transfer device according to claim 3, wherein the third gate electrode has a triangular notch formed at a center thereof adjoining to the first gate electrode,the end of the first conductive type first diffusion layer is formed into a triangular shape corresponding with the triangular notch of the third gate electrode, andthe triangular notch of the third gate electrode has a side face opposing that of the triangular end of the first conductive type first diffusion layer in parallel, with the first insulating film interposed therebetween.

5. A charge transfer device comprising: a semiconductor substrate;a horizontal transfer CCD transferring received signal charge in a horizontal direction;a signal charge-voltage converter converting the signal charge transferred from the horizontal transfer CCD into a signal voltage; anda reset drain discharging the signal charge,the horizontal transfer CCD, the signal charge-voltage converter and the reset drain being formed on the semiconductor substrate while adjoining to each other, whereinthe signal charge-voltage converter includes:a first conductive type first diffusion layer selectively formed on a surface of the semiconductor substrate;a first conductive type second diffusion layer formed at a deep portion of the semiconductor substrate so as to come into contact with the first conductive type first diffusion layer;a second conductive type first diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with one of ends of the first conductive type first diffusion layer and to come into contact with the first conductive type second diffusion layer formed immediately therebelow;a second conductive type second diffusion layer formed so as to come into contact with an end of the second conductive type first diffusion layer opposite to an end coming into contact with the first conductive type first diffusion layer;a second conductive type third diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with an end of the first conductive type first diffusion layer opposite to the end coming into contact with the second conductive type first diffusion layer and to come into contact with the first conductive type second diffusion layer formed immediately therebelow;a second conductive type fourth diffusion layer formed so as to come into contact with an end of the second conductive type third diffusion layer opposite to the end coming into contact with the first conductive type first diffusion layer;a first conductive type third diffusion layer formed on the surface of the semiconductor substrate so as to come into contact with the second conductive type first diffusion layer, the second conductive type second diffusion layer, the second conductive type third diffusion layer and the second conductive type fourth diffusion layer and to come into contact with the first conductive type second diffusion layer formed immediately therebelow; anda gate electrode entirely formed over the second conductive type first diffusion layer, the second conductive type second diffusion layer, the second conductive type third diffusion layer and the second conductive type fourth diffusion layer with an insulating film interposed therebetween.

6. The charge transfer device according to claim 1, wherein the first conductive type diffusion layer is a p-type diffusion layer and the second conductive type diffusion layer is an n-type diffusion layer.

7. The charge transfer device according to claim 2, wherein the first conductive type diffusion layer is a p-type diffusion layer and the second conductive type diffusion layer is an n-type diffusion layer.

8. The charge transfer device according to claim 3, wherein the first conductive type diffusion layer is a p-type diffusion layer and the second conductive type diffusion layer is an n-type diffusion layer.

9. The charge transfer device according to claim 4, wherein the first conductive type diffusion layer is a p-type diffusion layer and the second conductive type diffusion layer is an n-type diffusion layer.

10. The charge transfer device according to claim 5, wherein the first conductive type diffusion layer is a p-type diffusion layer and the second conductive type diffusion layer is an n-type diffusion layer.

11. The charge transfer device according to claim 1, wherein the first conductive type diffusion layer is an n-type diffusion layer and the second conductive type diffusion layer is a p-type diffusion layer.

12. The charge transfer device according to claim 2, wherein the first conductive type diffusion layer is an n-type diffusion layer and the second conductive type diffusion layer is a p-type diffusion layer.

13. The charge transfer device according to claim 3, wherein the first conductive type diffusion layer is an n-type diffusion layer and the second conductive type diffusion layer is a p-type diffusion layer.

14. The charge transfer device according to claim 4, wherein the first conductive type diffusion layer is an n-type diffusion layer and the second conductive type diffusion layer is a p-type diffusion layer.

15. The charge transfer device according to claim 5, wherein the first conductive type diffusion layer is an n-type diffusion layer and the second conductive type diffusion layer is a p-type diffusion layer.