Method and apparatus for proximate CMOS pixels

• US 20060146158A1
• Filed: 12/30/2004
• Published: 07/06/2006
• Est. Priority Date: 12/30/2004
• Status: Active Grant

• Current Assignee: RE Secured Networks LLC
• Original Assignee: Imperium (IP) Holdings Incorporated
• Inventors: Mann, Richard, Bencuya, Selim, Toros, Zeynep
• Granted Patent: US 7,635,880 B2
• Time in Patent Office: Days
• US Class Current: 348/308
• CPC Class Codes: H01L 27/14603 Special geometry or disposition of pixel-elements, address-lines or gate-electrodes
• 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: H01L 27/14689 MOS based technologies
• CPC Class Codes: H04N 25/616 involving a correlated sampling function, e.g. correlated double sampling [CDS] or triple sampling
• CPC Class Codes: H04N 25/626 Reduction of noise due to residual charges remaining after image readout, e.g. to remove ghost images or afterimages
• CPC Class Codes: H04N 25/63 applied to dark current
• CPC Class Codes: H04N 25/77 Pixel circuitry, e.g. memories, A/D converters, pixel amplifiers, shared circuits or shared components

Abstract

An improved CMOS sensor integrated circuit is disclosed, along with methods of making the circuit and computer readable descriptions of the circuit.

Claims

1. An image sensor integrated circuit, comprising:

a plurality of photodetectors generating electrons excited by incident photons, each of the plurality of photodetectors including;

an n-type region receiving the electrons excited by the energy of the photons;

a plurality of nodes, wherein each of the plurality of photodetectors has a corresponding node of the plurality of nodes;

a plurality of transfer devices controlling a transfer of the electrons from said each of the plurality of photodetectors to the corresponding node, each of the plurality of transfer devices including;

a first terminal coupled to the n-type region of one of the plurality of photodetectors;

a second terminal coupled to one of the plurality of nodes; and

a control terminal receiving the control signal, wherein the transfer of the electrons occurs between the first terminal and the second terminal in response to a control signal of sufficient value applied to the control terminal;

a first plurality of p-type regions having a first p-type concentration stronger than a background concentration, wherein each of the first plurality of p-type regions has a lateral shape surrounding multiple photodetectors of the plurality of photodetectors;

a second plurality of p-type regions having a second p-type concentration stronger than the first p-type concentration;

a plurality of reset devices in the second plurality of p-type regions, wherein each of the plurality of nodes has a corresponding reset device of the plurality of reset devices, and said each of the plurality of nodes is reset when the corresponding reset device is active;

row and column circuitry; and

a plurality of signal devices coupling the plurality of nodes to the row and column circuitry.

2. The circuit of claim 1, wherein the n-type region includes:

a first n-type region receiving the electrons excited by the energy of the photons; and

a second n-type region adjacent to the first region, wherein a difference in n-type concentration between the first n-type region and the second n-type region causes electrons to move from the first region to the second region.

3. The circuit of claim 1, wherein the n-type region of the plurality of photodetectors is at a first range of depths, and the first plurality of p-type regions is at a second range of depths includes a subrange of depths shallower than the first range of depths.

4. The circuit of claim 1, wherein the plurality of reset devices and the plurality of signal devices are positioned in the second plurality of p-type regions.

5. The circuit of claim 1, wherein the second plurality of p-type regions is formed by two boron implants.

6. The circuit of claim 1, wherein the second plurality of p-type regions is formed by a first boron implant and a second boron implant, wherein the first boron implant has a first energy range of 40 to 60 keV and a first dose range of 1.5×

10¹² to 2.0×

10¹² atoms/cm², and the second boron implant has a second energy range of 180 to 220 keV and a second dose range of 1.0×

10¹² atoms/cm² to 1.4×

10¹² atoms/cm².

7. The circuit of claim 1, wherein the first plurality of p-type regions isolates the multiple photodetectors from each other.

8. The circuit of claim 1, wherein the first plurality of p-type regions isolates the multiple photodetectors from other photodetectors of the plurality of photodetectors.

9. The circuit of claim 1, wherein each of the plurality of transfer devices includes a body connecting the first terminal and the second terminal such that the control terminal controls the transfer of the electrons between the first terminal and the second terminal through the body, and a dielectric between the control terminal and the body, the dielectric satisfying a lifetime specification of the image sensor integrated circuit when the control signal is applied with the channel formed, the dielectric failing the lifetime specification of the image sensor integrated circuit if the control signal is applied with at least one of the first terminal and the second terminal at a ground voltage of the image sensor integrated circuit.

10. The circuit of claim 1, wherein the plurality of signal devices includes a plurality of row select transistors coupled to the row and column circuitry and a plurality of source follower transistors coupled to the plurality of nodes.

11. The circuit of claim 1, wherein the plurality of photodetectors is a plurality of photodiodes.

12. The circuit of claim 1, wherein each measurement of the total of the photons is corrected by correlated multiple sampling with a prior measurement of the total of the photons.

13. A method of fabricating an image sensor integrated circuit having a plurality of photodetectors using energy of photons reaching the plurality of photodetectors to excite electrons;

a plurality of nodes, each of the plurality of photodetectors having a corresponding node of the plurality of nodes;

a plurality of transfer devices each with a first terminal coupled to one of the plurality of photodetectors, a second terminal coupled to the corresponding node, and a control terminal causing a transfer of the electrons from the first terminal to the second terminal in response to receiving a control signal of sufficient value;

a plurality of reset devices, each of the plurality of nodes having a corresponding reset device of the plurality of reset devices, and said each of the plurality of nodes is reset when the corresponding reset device is active; and

a plurality of signal devices coupling the plurality of nodes to row and column circuitry;

the method comprising;

implanting a first plurality of p-type regions having a first p-type concentration stronger than a background concentration;

implanting a second plurality of p-type regions having a second p-type concentration stronger than the first p-type concentration;

implanting an n-type region for each of the plurality of photodetectors positioned such that each of the first plurality of p-type regions has a lateral shape surrounding multiple photodetectors of the plurality of photodetectors, the n-type region receiving the electrons excited by the energy of the photons;

depositing the control terminal for each of the plurality of transfer devices;

implanting the plurality of nodes, wherein each of the plurality of photodetectors has a corresponding node of the plurality of nodes where the electrons are measured prior to removal; and

implanting at least one n+ terminal for each of the plurality of transfer devices,

wherein said method forms row and column circuitry on the image sensor integrated circuit accessing the plurality of nodes, and said method forms the plurality of reset devices in the second plurality of p-type regions.

14. The method of claim 13, wherein said method forms the plurality of reset devices and the plurality of signal devices in the second plurality of p-type regions.

15. The method of claim 13, wherein said depositing the control terminal for the plurality of transfer devices includes depositing the control terminal for the plurality of reset devices and the plurality of signal devices.

16. The method of claim 13, wherein said implanting at least one n+ terminal includes implanting the n+ terminals of the plurality of signal devices, and the plurality of reset devices.

17. The method of claim 13, wherein implanting the n-type region includes:

implanting a first n-type region receiving the electrons excited by the energy of the photons; and

implanting a second n-type region adjacent to the first region, wherein a difference in n-type concentration between the first n-type region and the second n-type region causes electrons to move from the first region to the second region.

18. The method of claim 13, wherein the n-type region of the plurality of photodetectors is at a first range of depths, and the second plurality of p-type regions is at a second range of depths includes a subrange of depths shallower than the first range of depths.

19. The method of claim 13, wherein the second plurality of p-type regions is formed by two boron implants.

20. The method of claim 13, wherein the second plurality of p-type regions is formed by a first boron implant and a second boron implant, the first boron implant has a first energy range of 40 to 60 keV and a first dose range of 1.5×

10¹² to 2.0×

10¹² atoms/cm², and the second boron implant has a second energy range of 180 to 220 keV and a second dose range of 1.0×

10¹² atoms/cm² to 1.4×

10¹² atoms/cm².

21. The method of claim 13, wherein the first plurality of p-type regions isolates the multiple photodetectors from each other.

22. The method of claim 13, wherein the first plurality of p-type regions isolates the multiple photodetectors from other photodetectors of the plurality of photodetectors.

23. The method of claim 13, wherein each of the plurality of transfer devices includes a body connecting the first terminal and the second terminal such that the control terminal controls the transfer of the electrons between the first terminal and the second terminal through the body, and a dielectric between the control terminal and the body, the dielectric satisfying a lifetime specification of the image sensor integrated circuit when the control signal is applied with the channel formed, the dielectric failing the lifetime specification of the image sensor integrated circuit if the control signal is applied with at least one of the first terminal and the second terminal at a ground voltage of the image sensor integrated circuit.

24. The method of claim 13, wherein the plurality of signal devices includes a plurality of row select transistors coupled to the row and column circuitry and a plurality of source follower transistors coupled to the plurality of nodes.

25. The method of claim 13, wherein the plurality of photodetectors is a plurality of photodiodes.

26. The method of claim 13, wherein each measurement of the total of the photons is corrected by correlated multiple sampling with a prior measurement of the total of the photons.

27. A computer readable description of an image sensor integrated circuit comprising:

a plurality of photodetectors generating electrons excited by incident photons, each of the plurality of photodetectors including;

an n-type region receiving the electrons excited by the energy of the photons;

a plurality of nodes, wherein each of the plurality of photodetectors has a corresponding node of the plurality of nodes;

a plurality of transfer devices controlling a transfer of the electrons from said each of the plurality of photodetectors to the corresponding node, each of the plurality of transfer devices including;

a first terminal coupled to the n-type region of one of the plurality of photodetectors;

a second terminal coupled to one of the plurality of nodes; and

a control terminal receiving the control signal, wherein the transfer of the electrons occurs between the first terminal and the second terminal in response to

a control signal of sufficient value applied to the control terminal;

a first plurality of p-type regions having a first p-type concentration stronger than a background concentration, wherein each of the first plurality of p-type regions has a lateral shape surrounding multiple photodetectors of the plurality of photodetectors;

a second plurality of p-type regions having a second p-type concentration stronger than the first p-type concentration;

a plurality of reset devices in the second plurality of p-type regions, wherein each of the plurality of nodes has a corresponding reset device of the plurality of reset devices, and said each of the plurality of nodes is reset when the corresponding reset device is active;

row and column circuitry; and

a plurality of signal devices coupling the plurality of nodes to the row and column circuitry.