Pixel array and image sensor including the same

• US 8,895,936 B2
• Filed: 01/03/2012
• Issued: 11/25/2014
• Est. Priority Date: 01/26/2011
• Status: Active Grant

• Current Assignee: DB HiTek Co., Ltd.
• Original Assignee: Dongbu HiTek Co., Ltd. (DB HiTek Co., Ltd.)
• Inventors: Ha, Man Lyun, Lee, Ju Il, Choi, Sun
• Primary Examiner(s): Porta, David
• Assistant Examiner(s): FEIN, ABRA S
• Application Number:
  US13/342,437
• Publication Number:
  US 20120187304A1
• Time in Patent Office: 1,057 Days
• Field of Search: 250/370.01
• US Class Current: 250/370.01
• 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 27/14625 Optical elements or arrangements associated with the device
• CPC Class Codes: H01L 27/14627 Microlenses
• CPC Class Codes: H04N 25/778 comprising amplifiers shared between a plurality of pixels, i.e. at least one part of the amplifier must be on the sensor array itself

Abstract

A pixel array and an image sensor including the pixel array having improved sensitivity and can drive pixels with high resolution, according to embodiments. In embodiments, a pixel array may include a plurality of pixels having a pixel area and a logic area. The pixel array may include at least one of: (1) A photoelectric conversion unit in the pixel area of each of the pixels. (2) A pixel-area transistor disposed at a side of the photoelectric conversion unit in the pixel area. (3) A metal-0 layer on the pixel-area transistor. (4) A metal-1 layer on and/or over the metal-0 layer. (5) A light reception unit on and/or over the metal-1 layer, with the metal-1 layer being the top metal layer in the pixel area.

Claims

1. A pixel array comprising a plurality of pixels and having a pixel area and a logic area, each pixel comprising:

a photoelectric conversion unit in the pixel area;

pixel-area transistors in the pixel area adjacent to the photoelectric conversion unit and comprising a reset transistor, a drive transistor, and a select transistor;

a first metal layer interconnecting the pixel area transistors, wherein the first metal layer comprises a reset signal, a select signal, a first gate connection connecting a gate of the select transistor to the select signal, and a second gate connection connecting a gate of the reset transistor to the reset signal;

a second metal layer over the first metal layer, wherein the second metal layer is an uppermost metal layer of the pixel area; and

a light reception unit over the second metal layer,

wherein no metal layer exists between the second metal layer and the light reception unit, and no metal layer exists between the first metal layer and the second metal layer.

2. The pixel array according to claim 1, wherein the first metal layer electrically connects the pixel area transistors of adjacent ones of the pixels.

3. The pixel array according to claim 1, wherein the first metal layer has a thickness of about 500 Å

to about 2,000 Å

.

4. The pixel array according to claim 3, wherein the photoelectric conversion unit comprises a first photodiode and a second photodiode, the pixel area transistors comprise a first transfer transistor, a second transfer transistor, the reset transistor, and the select transistor, and the first metal layer comprises:

a first metal interconnection connecting each gate of the first transfer transistor;

a second metal interconnection connecting each gate of the select transistor;

a third metal interconnection connecting each gate of the second transfer transistor; and

a fourth metal interconnection connecting each gate of the reset transistor.

5. The pixel array according to claim 4, wherein each pixel comprises a floating diffusion area shared by the first and second photodiodes.

6. The pixel array according to claim 5, wherein the first and second transfer transistors are electrically connected to the floating diffusion area via the first or second metal layer.

7. The pixel array according to claim 3, wherein the photoelectric conversion unit comprises first and second photodiodes, the pixel area transistors comprise a first transfer transistor, a second transfer transistor, a third transfer transistor, a fourth transfer transistor, the reset transistor, and the drive transistor, and the first metal layer comprises:

a first metal interconnection connecting each gate of the first transfer transistor;

a second metal interconnection connecting each gate of the second transfer transistor;

a third metal interconnection connecting each gate of the third transfer transistor;

a fourth metal interconnection connecting each gate of the fourth transfer transistor; and

a fifth metal interconnection connecting each gate of the reset transistor.

8. The pixel array according to claim 1, wherein no metal layer exists between the second metal layer and the light reception unit, and no metal layer exists between the first metal layer and the second metal layer.

9. The pixel array according to claim 1, wherein the first metal layer functions as a global interconnection (GIC) for electrically connecting the pixel area transistors.

10. The pixel array according to claim 1, wherein an output of the select transistor is connected to the second metal layer.

11. An image sensor comprising:

a pixel array comprising a plurality of pixels and having a pixel area and a logic area wherein each of the pixels comprises;

a photoelectric conversion unit in the pixel area;

pixel-area transistors in the pixel area adjacent to the photoelectric conversion unit and comprising a reset transistor, a drive transistor, and a select transistor;

a first metal layer interconnecting the pixel area transistors, wherein the first metal layer connects (i) a gate of the select transistor to a corresponding select driver and (ii) a gate of the reset transistor to a corresponding reset driver;

a second metal layer over the first metal layer, wherein the second metal layer comprises a drive signal and a third gate connection connecting a gate of the drive transistor to the drive signal, and the second metal layer is an uppermost metal layer of the pixel area; and

a light reception unit over the second metal layer,

wherein no metal layer exists between the second metal layer and the light reception unit, and no metal layer exists between the first metal layer and the second metal layer.

12. The image sensor according to claim 11, further comprising:

a first pixel gate driver at one side of the pixel array; and

a second pixel gate driver at another side of the pixel array.

13. The image sensor according to claim 11, further comprising a readout IC under a pixel chip including the pixel array, and the readout IC is electrically connected with the pixel array.

14. The image sensor according to claim 13, further comprising a through via making contact with the second metal layer of the pixel array and electrically connected with the readout IC.

15. The image sensor according to claim 11, wherein the first metal layer electrically connects the pixel area transistors of adjacent ones of the pixels.

16. The image sensor according to claim 11, wherein the first metal layer has a thickness of approximately 500 Å

to approximately 2,000 Å

.

17. The image sensor according to claim 11, wherein the photoelectric conversion unit comprises a first photodiode and a second photodiode, the pixel area transistors comprise a first transfer transistor, a second transfer transistor, the reset transistor, and the select transistor,

wherein the first metal layer comprises:

a first metal interconnection connecting each gate of the first transfer transistor;

a second metal interconnection connecting each gate of the select transistor,

a third metal interconnection connecting each gate of the second transfer transistor; and

a fourth metal interconnection connecting each gate of the reset transistor.

18. The image sensor according to claim 17, wherein each pixel comprises a floating diffusion area shared by the first and second photodiodes.

19. The image sensor according to claim 18, wherein the first and second transfer transistors are electrically connected to the floating diffusion area via the first or second metal layer.

20. The image sensor according to claim 11, wherein the pixel array comprises a first transfer transistor, a second transfer transistor, a third transfer transistor, and a fourth transfer transistor,

wherein the first metal layer comprises:

a first metal interconnection connecting each gate of the first transfer transistor;

a second metal interconnection connecting each gate of the second transfer transistor;

a third metal interconnection connecting each gate of the third transfer transistor;

a fourth metal interconnection connecting each gate of the fourth transfer transistor; and

a fifth metal interconnection connecting each gate of the reset transistor.