Solid-state image pickup device and device driving control method for solid-state image pickup

• US 7,271,835 B2
• Filed: 09/04/2003
• Issued: 09/18/2007
• Est. Priority Date: 09/18/2002
• Status: Active Grant

• Current Assignee: Sony Corporation (Sony Group Corp.)
• Original Assignee: Sony Corporation (Sony Group Corp.)
• Inventors: Iizuka, Tetsuya, Ueno, Takahisa
• Primary Examiner(s): Ometz; David
• Assistant Examiner(s): Nguyen; Luong T.
• Application Number:
  US10/655,156
• Publication Number:
  US 20040051801A1
• Time in Patent Office: 1,475 Days
• Field of Search: None
• US Class Current: 348/314
• CPC Class Codes: H01L 27/14609 Pixel-elements with integrated switching, control, storage or amplification elements scanning details of imagers (circuitry of solid-state image sensors H04N25/00); circuitry of imagers H04N25/70
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers
• CPC Class Codes: H04N 25/623 by evacuation via the output or reset lines
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components
• CPC Class Codes: H04N 25/771 comprising storage means other than floating diffusion

Abstract

Disclosed herein is a solid-state image pickup device including: a plurality of unit pixels each having: a charge generating section for generating a charge, a charge storage section for storing the charge generated by the charge generating section, a transfer gate section disposed between the charge generating section and the charge storage section for transferring the charge generated by the charge generating section to the charge storage section, and a pixel signal generating section for generating a pixel signal corresponding to the charge stored in the charge storage section; an unnecessary charge discharging gate section in each the unit pixel, switchable to block a flow of an unnecessary charge that is generated in the charge generating section and does not contribute to image formation, according to height of an electric barrier; and an unnecessary charge drain section disposed on an opposite side of the unnecessary charge discharging gate section from the charge generating section for receiving the unnecessary charge swept out of the charge generating section through the unnecessary charge discharging gate section.

Claims

1. A solid-state image pickup device comprising:

a plurality of pixels, each pixel having at least;

a charge generating section for generating a charge,

a charge storage section for storing said charge generated by said charge generating section,

a transfer gate disposed between said charge generating section and said charge storage section, for transferring said charge generated by said charge generating section to said charge storage section, and

a pixel signal generating section for generating a pixel signal corresponding to said charge stored in said charge storage section;

an unnecessary charge discharging gate in each pixel disposed on an opposite side of said charge generating section from said charge storage section, switchable to selectively allow discharge of an unnecessary charge that is generated in said charge generating section; and

an unnecessary charge drain section disposed on an opposite side of said unnecessary charge discharging gate from said charge generating section, for receiving said unnecessary charge.

2. The solid-state image pickup device as claimed in claim 1,

wherein said transfer gate transfers said charge generated by said charge generating section to said charge storage section simultaneously in each one of the plurality of said pixels.

3. The solid-state image pickup device as claimed in claim 1,

wherein said pixel signal generating section comprises:

a charge injection section into which said charge generated by said charge generating section is injected,

a readout gate for controlling injection of said charge into said charge injection section,

a detecting element for detecting a change in potential of said charge injection section,

a reset drain section for receiving said charge injected into said charge injection section, and

a reset gate for resetting the potential of said charge injection section by discharging said signal charge injected into said charge injection section to said reset drain section.

4. The solid-state image pickup device as claimed in claim 3, wherein said charge injection section also serves as said charge storage section.

5. The solid-state image pickup device as claimed in claim 1, further comprising a driving control unit for driving control of said unnecessary charge discharging gate of said pixel,

wherein said driving control unit controls the height of an electric barrier at said unnecessary charge discharging gate by changing a magnitude of a voltage applied to said unnecessary charge discharging gate at a predetermined timing.

6. The solid-state image pickup device as claimed in claim 5,

wherein said driving control unit effects control to change the magnitude of the voltage applied to said unnecessary charge discharging gate such that an electric barrier created by said unnecessary charge discharging gate is high during a time of charge accumulation, and the electric barrier is low during a period other than said time of charge accumulation.

7. The solid-state image pickup device as claimed in claim 6,

wherein said driving control unit sets the magnitude of said voltage such that the electric barrier under said unnecessary charge discharging gate is higher in height than an electric barrier under said transfer gate during a period of transfer of said charge from said charge generating section to said charge storage section, and such that the electric barrier under said unnecessary charge discharging gate is lower in height than the electric barrier under said transfer gate during a major part of a period other than said time of charge accumulation.

8. The solid-state image pickup device as claimed in claim 6,

wherein said driving control unit sets the magnitude of said voltage such that the electric barrier under said unnecessary charge discharging gate during said time of charge accumulation is higher in height than an electric barrier under said transfer gate during said time of charge accumulation.

9. The solid-state image pickup device as claimed in claim 1,

wherein said unnecessary charge discharging gate is in a state of storing a charge of an opposite conduction type from said charge generated by said charge generating section at a channel surface under said unnecessary charge discharging gate during a time when said unnecessary charge discharging gate is in an off state.

10. The solid-state image pickup device as claimed in claim 1,

wherein said transfer gate is in a state of storing a charge of an opposite conduction type from said charge generated by said charge generating section at a channel surface under said transfer gate during a time when said transfer gate is in an off state.

11. The solid-state image pickup device as claimed in claim 3,

wherein said readout gate is in a state of storing a charge of an opposite conduction type from said charge generated by said charge generating section at a channel surface under said readout gate during a time when said readout gate is in an off state.

12. The solid-state image pickup device as claimed in claim 3,

wherein said reset gate is in a state of storing a charge of an opposite conduction type from said charge generated by said charge generating section at a channel surface under said reset gate during a time when said reset gate is in an off state.

13. The solid-state image pickup device as claimed in claim 1,

wherein said transfer gate has an electrode to which a pulse signal for driving control of said transfer gate is applied, said charge storage section has an electrode to which a pulse signal for driving control of said charge storage section is applied, and said transfer gate electrode and said storage gate electrode are formed as a common single-gate electrode;

and

a voltage potential difference is formed in a part corresponding to said transfer gate electrode and said storage gate electrode.

14. A driving control method for a solid-state image pickup device, said method comprising the steps of:

providing a solid-state image pickup device including a plurality of pixels, each pixel having at least;

a charge generating section for generating a charge,

a charge storage section for storing charge,

a transfer gate section disposed between said charge generating section and said charge storage section, for transferring said charge generated by said charge generating section to said charge storage section, and

a pixel signal generating section for generating a pixel signal corresponding to said charge stored in said charge storage section;

providing an unnecessary charge discharging gate section in each pixel disposed on an opposite side of said charge generating section from said charge storage section, switchable to selectively allow discharge of an unnecessary charge that is generated in said charge generating section;

providing an unnecessary charge drain section disposed on an opposite side of said unnecessary charge discharging gate section from said charge generating section, for receiving said unnecessary charge;

turning off said unnecessary charge discharging gate section during a time of charge accumulation, and

turning on said unnecessary charge discharging gate section during a period other than said time of charge accumulation.

15. The driving control method as claimed in claim 14,

wherein a well for said charge is formed with said charge generating section at a center of the well by turning off said unnecessary charge discharging gate section and said transfer gate section prior to said time of charge accumulation.

16. The driving control method, as claimed in claim 14,

wherein prior to said charge accumulation, said charge generating section is reset by discharging said charge accumulated in said charge generating section to at least one of said charge storage section and said unnecessary charge discharging gate section.

17. The driving control method as claimed in claim 14,

wherein said charge accumulated in said charge generating section at said time of charge accumulation is transferred to said charge storage section by turning on said transfer gate section, and said unnecessary charge discharging gate section is turned on after a start of transfer of the charge.

18. The driving control method as claimed in claim 17,

wherein said transfer gate section is turned off after the transfer of said charge to said charge storage section.

19. The driving control method as claimed in claim 14,

wherein said charge storage section is reset by discharging a charge stored in said charge storage section prior to transfer of said accumulated signal charge from the charge generating section to said charge storage section.

20. The driving control method as claimed in claim 14,

wherein control is effected such that a charge well is formed with said charge generating section at a center of the charge well when said unnecessary charge discharging gate section is in an on state.