Image sensors with photoelectric films
View Patent ↗An image sensor with an organic photoelectric film for converting light into charge may be provided. The image sensor may include an array of image sensor pixels. Each image sensor pixel may include a charge-integrating pinned diode that collects photo-generated charge from the photoelectric film during an integration period. An anode electrode may be coupled to an n+ doped charge injection region in the charge-integrating pinned diode and may be used to convey the photo-generated charge from the photoelectric film to the charge-integrating pinned diode. Upon completion of a charge integration cycle, a first transfer transistor gate may be pulsed to move the charge from the charge-integrating pinned diode to a charge-storage pinned diode. The charge may be transferred from the charge-storage pinned diode to a floating diffusion node for readout by pulsing a gate of a second charge transfer transistor.
1. An image sensor pixel array having at least one pixel circuit, wherein the at least one pixel circuit comprises:
an organic photoelectric film configured to convert incident photons into photo-generated charge;
a charge-integrating pinned diode configured to collect the photo-generated charge;
a conductive electrode electrically coupled between the organic photoelectric film and the charge-integrating pinned diode, wherein the conductive electrode is configured to convey the photo-generated charge to the charge-integrating pinned diode, wherein the conductive electrode has first and second opposing sides; and
an n+ type doped charge injector region formed in the charge-integrating pinned diode, wherein the n+ type doped charge injector region is directly connected to the conductive electrode, wherein the charge injector region is configured to receive the photo-generated charge from the conductive electrode and to input the photo-generated charge into the charge-integrating pinned diode, wherein the organic photoelectric film is formed on the first side of the conductive electrode, and wherein the n+ type doped charge injector region is formed on the second side of the conductive electrode.
2. The image sensor pixel array defined in claim 1 wherein the at least one pixel circuit further comprises a charge storage pinned diode.
3. The image sensor pixel array defined in claim 2 wherein the at least one pixel circuit further comprises a charge transfer gate configured to transfer the photo-generated charge from the charge-integrating pinned diode to the charge storage pinned diode.
4. The image sensor pixel array defined in claim 3 wherein the at least one pixel circuit further comprises a floating diffusion node.
5. The image sensor pixel array defined in claim 4 wherein the at least one pixel circuit further comprises an additional charge transfer gate configured to transfer the photo-generated charge from the charge storage pinned diode to the floating diffusion node.
6. The image sensor pixel array defined in claim 1 wherein the at least one pixel circuit further comprises an anti-blooming structure coupled to the charge-integrating pinned diode and wherein the anti-blooming structure is configured to control the saturation level associated with the at least one pixel circuit.
7. The image sensor pixel array defined in claim 6 wherein the anti-blooming structure comprises an anti-blooming reset transistor and an anti-blooming charge drain, and wherein the anti-blooming reset transistor is configured to remove the photo-generated charge from the charge-integrating pinned diode.
8. The image sensor pixel array defined in claim 1 wherein the image sensor pixel array is operable in a global shutter mode.
9. The image sensor pixel array defined in claim 1 , wherein the charge-integrating pinned diode includes p+ type doped regions and an n type doped region, and wherein the p+ type doped regions and the n type doped region combine to form a potential well for collecting the injected charge from the n+ type doped charge injector region.
10. The image sensor pixel array defined in claim 9 , wherein the n+ type doped charge injector region has a higher doping concentration than the n type doped region and wherein the n type doped region is in direct contact with the p+ type doped regions and the n+ type doped charge injector region.
11. The image sensor pixel array defined in claim 1 , wherein the charge-integrating pinned diode comprises an n type doped region, and wherein the n+ type doped charge injector region is surrounded on at least three sides by the n type doped region.
12. A system, comprising:
a central processing unit;
memory;
input-output circuitry; and
an imaging device, wherein the imaging device comprises a pixel array having at least one pixel circuit, the at least one pixel circuit comprising:
an organic photoelectric film configured to convert incident photons into photo-generated charge,
a charge-integrating pinned diode configured to collect the photo-generated charge,
a conductive electrode electrically coupled between the organic photoelectric film and the charge-integrating pinned diode, wherein the conductive electrode is configured to convey the photo-generated charge to the charge-integrating pinned diode, and
an n+ type doped charge injector region formed in the charge-integrating pinned diode, wherein the n+ type doped charge injector region is directly connected to the conductive electrode, wherein the charge injector region is configured to receive the photo-generated charge from the conductive electrode and to input the photo-generated charge into the charge-integrating pinned diode, wherein the charge-integrating pinned diode comprises an n type doped region, and wherein the n+ type doped charge injector region is surrounded on at least three sides by the n type doped region.
13. The system defined in claim 12 wherein the at least one pixel circuit further comprises a charge storage pinned diode and a charge transfer transistor configured to transfer the photo-generated charge from the charge-integrating pinned diode to the charge storage pinned diode.
14. The system defined in claim 13 wherein the at least one pixel circuit further comprises a floating diffusion node and an additional charge transfer gate configured to transfer the photo-generated charge from the charge storage pinned diode to the floating diffusion node.
15. The system defined in claim 14 wherein the at least one pixel circuit further comprises an anti-blooming reset transistor and an anti-blooming charge drain coupled to the charge-integrating pinned diode and configured to control the saturation level associated with the at least one pixel circuit.
16. The system defined in claim 12 , wherein the conductive electrode has first and second opposing sides, wherein the organic photoelectric film is formed on the first side of the conductive electrode, and wherein the n+ type doped charge injector region and the n type doped region are formed on the second side of the conductive electrode.
17. An image sensor pixel array having at least one pixel circuit, wherein the at least one pixel circuit comprises:
an organic photoelectric film configured to convert incident photons into photo-generated charge;
a p type epitaxial layer;
a charge-integrating pinned diode formed in the p type epitaxial layer that is configured to collect the photo-generated charge, wherein the charge-integrating pinned diode comprises an n type doped region that is surrounded on at least three sides by the p type epitaxial layer and at least one p+ type doped region that is formed in the n type doped region;
a conductive electrode electrically coupled between the organic photoelectric film and the charge-integrating pinned diode, wherein the conductive electrode is configured to convey the photo-generated charge to the charge-integrating pinned diode and wherein the conductive electrode has first and second opposing sides; and
an n+ type doped charge injector region formed in the charge-integrating pinned diode, wherein the n+ type doped charge injector region is surrounded on at least three sides by the n type doped region, wherein the n+ type doped charge injector region is directly connected to the conductive electrode, wherein the charge injector region is configured to receive the photo-generated charge from the conductive electrode and to input the photo-generated charge into the charge-integrating pinned diode, wherein the organic photoelectric film is formed on the first side of the conductive electrode, and wherein the n+ type doped charge injector region is formed on the second side of the conductive electrode.
18. The image sensor pixel array defined in claim 17 , wherein the at least one p+ type doped region is surrounded on at least two sides by the n type doped region.
19. The image sensor pixel array defined in claim 17 , wherein the conductive electrode has a first portion that is formed above at least one inter-level oxide layer and that extends parallel to the organic photoelectric film and wherein the conductive electrode has a second portion that is perpendicular to the first portion that extends through the at least one inter-level oxide layer to directly contact the n+ type doped charge injector region.
20. The image sensor pixel array defined in claim 19 , wherein an optical shielding layer is formed in the at least one inter-level oxide layer.