Solid-state imaging device and manufacturing method thereof

• US 20050253044A1
• Filed: 05/03/2005
• Published: 11/17/2005
• Est. Priority Date: 05/11/2004
• Status: Active Grant

• Current Assignee: Collabo Innovations, Inc. (Wi-LAN Inc.)
• Original Assignee: Panasonic Corporation (Panasonic Holdings Corporation)
• Inventors: Kuriyama, Toshihiro
• Granted Patent: US 7,760,251 B2
• Time in Patent Office: Days
• US Class Current: 250/208.100
• CPC Class Codes: H01L 27/14812 Special geometry or disposition of pixel-elements, address lines or gate-electrodes
• CPC Class Codes: H04N 23/555 for picking-up images in sites, inaccessible due to their dimensions or hazardous conditions, e.g. endoscopes or borescopes

Abstract

The present invention aims to provide a solid-state imaging device that enables miniaturization of camera while maintaining the level of electrostatic damage resistance in the solid-state imaging device, and includes: an imaging unit 100 that transfers signal charge generated by performing photoelectric conversion on incident light, converts the signal charge into an electric signal, and outputs the electric signal as an image signal; and a peripheral circuit portion 110 which includes: a signal electrode pad 111; a power supply electrode pad 112; and a protection circuit 113 that has diodes 320 and 330 placed in opposition, and that discharges static electricity entering from the exterior, to the power supply electrode pad 112.

Claims

1. A solid-state imaging device comprising:

an imaging unit which includes a photoelectric conversion unit operable to photo-electrically convert incident light into signal charge, and is operable (i) to transfer the signal charge generated by said photoelectric conversion unit, (ii) to convert the signal charge into an electric signal, and (iii) to output the electric signal as an image signal;

a protection circuit that protects said imaging unit from static electricity; and

a power supply electrode pad that supplies said imaging unit with power,

wherein said protection circuit discharges static electricity entering from outside, to said power supply electrode pad.

2. The solid-state imaging device according to claim 1,

wherein said imaging unit is operable to transfer the signal charge, using a pulse having a voltage level of positive or negative, and

the power supply electrode pad is supplied with power having a level equal to or higher than the positive voltage of the pulse.

3. The solid-sate imaging device according to claim 2, further comprising

a signal electrode pad for input and output of signal,

wherein said protection circuit includes a first diode, and

a cathode of said first diode is connected to said power supply electrode pad while an anode of said first diode is connected to said signal electrode pad.

4. The solid-state imaging device according to claim 3,

wherein said protection circuit further includes a second diode, and

a cathode of said second diode is connected to the cathode of said first diode while an anode of said second diode is connected to a ground.

5. The solid-state imaging device according to claim 4,

wherein said signal electrode pad is supplied with a pulse to be used for transferring signal charge.

6. The solid-state imaging device according to claim 5,

wherein said protection circuit is formed in a semiconductor substrate of first conductivity type, and

in a part where said protection circuit is formed, the semiconductor substrate includes:

a first region of second conductivity type, which is formed in an upper part of the semiconductor substrate, the second conductivity type being a type opposite to the first conductivity type;

a second region of first conductivity type, which is formed in a surface portion of said first region and is connected to said power supply electrode pad; and

a third region of second conductivity type, which is formed in a surface portion of said second region and is connected to said signal electrode pad.

7. The solid-state imaging device according to claim 6,

wherein a plurality of said first diodes are connected in parallel, and

a plurality of said third regions are formed in island shape in the surface portion of said second region.

8. The solid-state imaging device according to claim 7,

wherein said solid-state imaging device has an electronic shatter function to forcibly discharge the signal charge generated by said photoelectric conversion unit,

wherein, in the part where said protection circuit is formed, the semiconductor substrate includes a fourth region of second conductivity type, which is formed below said second region within said first region, and

said fourth region has an impurity concentration higher than an impurity concentration of said first region.

9. The solid-state imaging device according to claim 8,

wherein said photoelectric conversion unit is formed in the semiconductor substrate, and

in the part where said photoelectric conversion unit is formed, the semiconductor substrate includes:

said first region of second conductivity type, which is formed in an upper part of the semiconductor substrate;

a fifth region of first conductivity type, which is formed in the surface portion of said first region; and

a sixth region of second conductivity type, which is formed in a surface portion of said fifth region.

10. The solid-state imaging device according to claim 9,

wherein in the part where said protection circuit is formed, the semiconductor substrate further includes, a seventh region of second conductivity type, which is formed in a surface portion of said third region, and

said sixth and seventh regions are formed by doping said regions with the same impurity and under the same condition as applied to said fifth and third regions.

11. The solid-state imaging device according to claim 10, further comprising

a first wiring that connects said protection circuit and said power supply electrode pad;

a second wiring that connects said imaging unit and said power supply electrode pad;

wherein said first and second wirings are separately wired.

12. The solid-state imaging device according to claim 10,

wherein said power supply electrode pad is made up of a first electrode pad and a second electrode pad,

said first wiring is connected to said first electrode pad, and

said second wiring is connected to said second electrode pad.

13. The solid-state imaging device according to claim 6,

wherein said solid-state imaging device has an electronic shatter function to forcibly discharge the signal charge generated by said protection circuit,

in the part where said protection circuit is formed, the semiconductor substrate further includes a fourth region of second conductivity, which is formed below said second region within said first region, and

said fourth region has an impurity concentration higher than an impurity concentration of said first region.

14. The solid-state imaging device according to claim 6,

wherein said photoelectric conversion unit is formed in the semiconductor substrate, and

in the part where said photoelectric conversion unit is formed, the semiconductor substrate includes:

a first region of second conductivity type, which is formed in an upper part of the semiconductor substrate;

a fifth region of first conductivity type, which is formed on the surface portion of said first region; and

a sixth region of second conductivity type, which is formed on a surface portion of said fifth region.

15. The solid-state imaging device according to claim 3,

wherein said signal electrode pad is supplied with a pulse to be used for transferring signal charge.

16. The solid-state imaging device according to claim 3,

wherein said protection circuit is formed in a semiconductor substrate of first conductivity type, and

in a part where said protection circuit is formed, the semiconductor substrate includes:

a first region of second conductivity type, which is formed in an upper part of the semiconductor substrate, the second conductivity type being a type opposite to the first conductivity type;

a second region of first conductivity type, which is formed in a surface portion of said first region and is connected to said power supply electrode pad; and

a third region of second conductivity type, which is formed in a surface portion of said second region and is connected to said power supply electrode pad.

17. The solid-state imaging device according to claim 1, further comprising

a signal electrode pad for input and output of signal,

wherein said protection circuit includes a first diode, and

a cathode of said first diode is connected to said power supply electrode pad while an anode of said first diode is connected to said signal electrode pad.

18. The solid-state imaging device according to claim 1, further comprising

a first wiring that connects said protection circuit and said power supply electrode pad;

and

a second wiring that connects said imaging device and said power supply electrode pad,

wherein said first and second wirings are separately wired.

19. A method of manufacturing a solid-state imaging device,

wherein the solid-state imaging device (i) includes:

a photoelectric conversion unit that performs photoelectric conversion on incident light; and

a protection circuit, and (ii) has an electronic shatter function to forcibly discharge signal charge generated by the photoelectric conversion unit, and

said method comprises;

forming a first region of second conductivity type in an upper part of a semiconductor substrate of first conductivity type, the second conductivity type being a type opposite to the first conductivity type;

forming, in a part where the protection circuit is formed within the semiconductor substrate, a second region of the first conductivity type in a surface portion of said first region; and

forming a third region of second conductivity type below the second region within the first region, the third region having an impurity concentration higher than an impurity concentration of the first region,

wherein the second and third regions are formed by doping the respective regions with impurities of first and second conductivity types respectively, using the same mask.

20. The method according to claim 19, further comprising:

forming, in a part where the photoelectric conversion unit is formed within the semiconductor substrate, a fourth region of first conductivity type in a surface portion of the first region; and

forming a fifth region of second conductivity type in a surface portion of the fourth region.