Pixel having two semiconductor layers, image sensor including the pixel, and image processing system including the image sensor

• US 20070069258A1
• Filed: 09/21/2006
• Published: 03/29/2007
• Est. Priority Date: 09/29/2005
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Ahn, Jung-Chak
• Granted Patent: US 7,671,435 B2
• Time in Patent Office: Days
• US Class Current: 257/290
• CPC Class Codes: H01L 27/14612 involving a transistor
• CPC Class Codes: H01L 27/14634 Assemblies, i.e. Hybrid structures
• CPC Class Codes: H01L 27/14636 Interconnect structures
• CPC Class Codes: H01L 27/1464 Back illuminated imager structures
• CPC Class Codes: H01L 27/14643 Photodiode arrays; MOS imagers

Abstract

An image sensor having pixels that include two patterned semiconductor layers. The top patterned semiconductor layer contains the photoelectric elements of pixels having substantially 100% fill-factor. The bottom patterned semiconductor layer contains transistors for detecting, resetting, amplifying and transmitting signals charges received from the photoelectric elements. The top and bottom patterned semiconductor layers may be separated from each other by an interlayer insulating layer that may include metal interconnections for conducting signals between devices formed in the patterned semiconductor layers and from external devices.

Claims

1. An image sensor comprising:

a first patterned semiconductor layer;

a second patterned semiconductor layer;

and an interlayer insulating layer interposed between the first patterned semiconductor layer and the second patterned semiconductor layer;

a photoelectric element formed in the second patterned semiconductor layer; and

at least one transistor formed in the first patterned semiconductor layer.

2. The image sensor as set forth in claim 1, wherein the at least one transistor formed in the first patterned semiconductor layer is electrically connected to the photoelectric element and sensing signal charges generated in the photoelectric element.

3. The image sensor as set forth in claim 1, wherein the photoelectric element is a photodiode comprising:

an N-type region formed in the second patterned semiconductor layer; and

a P-type region in the second patterned semiconductor layer.

4. The image sensor as set forth in claim 3, wherein the P-type region envelops the N-type region.

5. The image sensor as set forth in claim 1, further comprising:

first and second charge collection regions formed in the second and first semiconductor patterns respectively, electrically connected to each other, for accepting the signal charges generated in the photoelectric element,

wherein the at least one transistor is electrically connected to the first and second charge collection regions.

6. The image sensor as set forth in claim 5, wherein the at least one transistor electrically connected to the first and second charge collection regions comprises:

a first transistor for sensing signal charges of the first and second charge collection regions; and

a second transistor for resetting signal charges of the first and second charge collection regions;

wherein the first and second transistors are electrically connected to each other through a common drain,

wherein a gate of the first transistor is electrically connected to the first and second charge collection regions, and

wherein the first charge collection region acts as a source of the second transistor.

7. The image sensor as set forth in claim 6, further comprising:

a transfer gate formed in the second patterned semiconductor layer for transferring the signal charges to the second charge collection region from the photoelectric element.

8. The image sensor as set forth in claim 5, further comprising:

a transfer gate formed in the second patterned semiconductor layer for transferring the signal charges from the photoelectric element to the first and second charge collection regions.

9. The image sensor as set forth in claim 1, wherein the photoelectric element is a diode comprising:

an N-type region formed in the second patterned semiconductor layer; and

a P-type region formed in the second patterned semiconductor layer and formed to envelop the N-type region

10. The image sensor as set forth in claim 9, wherein the second charge collection region is formed in the P-type region apart from the N-type region.

11. The image sensor as set forth in one of claim 1, further comprising a color filter formed directly on the second patterned semiconductor layer.

12. An image sensor comprising:

a first patterned semiconductor layer;

a second patterned semiconductor layer;

an interlayer insulating layer interposed between the first patterned semiconductor layer and the second patterned semiconductor layer;

a photoelectric element formed in the second patterned semiconductor layer; and

a transfer gate formed in the second patterned semiconductor layer for transferring signal charges from the photoelectric element to a second charge collection region in the first patterned semiconductor layer.

13. The image sensor as set forth in claim 12, wherein the photoelectric element is a diode comprising:

an N-type region formed in the second patterned semiconductor layer; and

a P-type region formed in the second patterned semiconductor layer enveloping the N-type region, and

wherein a first charge collection region is further formed in the second patterned semiconductor layer being spaced away from the N-type region, the first charge collection region being electrically connected to the second charge collection region.

14. The image sensor as set forth in claim 12, further comprising:

a first charge collection region formed in the second patterned semiconductor layer and electrically connected to the second charge collection region;

a source follower gate formed in the first pattered semiconductor layer and electrically connected to the first and second charge collection regions;

first source and drain regions formed in the first patterned semiconductor layer at both sides of the source follower gate; and

a reset gate formed in the first patterned semiconductor layer between the first drain region and the first charge collection region.

15. The image sensor as set forth in one of claims 14, wherein the interlayer insulating layer includes first and second interlayer insulating layers;

wherein the first charge collection region is electrically connected to the second charge collection region by;

a first contact plug penetrating the first interlayer insulating layer and electrically connected to the second charge collection region;

a local conductive pattern formed on the first interlayer insulating layer and electrically connected to the first contact plug; and

a second contact plug penetrating the second interlayer insulating layer and electrically connecting the first charge collection region with the local conductive pattern.

16. The image sensor as set forth in claim 15, wherein the local conductive pattern is electrically connected to a third contact plug that penetrates the first interlayer insulating layer and is connected to the source follower gate.

17. The image sensor as set forth in claim 14, wherein the interlayer insulating layer includes metal interconnections for applying bias voltages to the transfer and reset gates.

18. The image sensor as set forth in claim 14, further comprises:

a second drain region formed in the first semiconductor pattern; and

a selection gate formed in the first semiconductor pattern between the second drain region and the first source region.

19. The image sensor as set forth in claim 18, wherein the interlayer insulating layer includes a metal interconnection for applying a bias voltage to the selection gate.

20. The image sensor as set forth in claim 12, further comprises a color filter formed directly on the second patterned semiconductor layer.

23. The image processing system as set forth in claim 19, wherein the photoelectric element is a diode comprising:

an N-type region formed in the second patterned semiconductor layer; and

a P-type region formed in the second patterned semiconductor layer enveloping the N-type region.

21. An image sensor comprising:

a pixel including;

a photoelectric element formed in a second patterned semiconductor layer; and

at least one transistor formed in a first patterned semiconductor layer electrically connected to the photoelectric element, the first patterned semiconductor layer being electrically insulated from the second patterned semiconductor layer.

22. An image processing system comprising:

a processor; and

an image sensor operatively connected to the processor,

wherein the image sensor comprises a plurality of pixels,

wherein each pixel comprises;

a photoelectric element formed in a second patterned semiconductor layer; and

at least one transistor formed in a first patterned semiconductor layer and electrically connected to the photoelectric element, the first patterned semiconductor layer being spaced apart from the second patterned semiconductor layer.