Stacked Imaging Element Charge Storage for Low-Noise Global Shutter
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Solution Overview
Problem
In imaging elements, the charges generated in the photoelectric conversion units are difficult to completely deplete, leading to increased kTC noise, random noise, and deteriorated image quality due to differences in charge storage and transfer mechanisms between different photoelectric conversion units.
Innovation Solution
Incorporating a charge storage electrode separated from the first electrode by an insulating layer, allowing for complete charge depletion and storage in the photoelectric conversion layer, and implementing a driving method that applies specific potentials to manage charge transfer and storage, enabling global shutter functionality and reduced noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If charges are stored directly in floating diffusion layers without intermediate storage electrodes, then the structure is simple, but complete charge depletion becomes difficult leading to increased kTC noise and random noise
Solution Approach 1:
The patent introduces intermediate charge storage electrodes between the photoelectric conversion layer and the floating diffusion layer. This segmentation allows charges to be stored in discrete locations (photoelectric conversion layer, charge storage electrode, floating diffusion layer) rather than directly in the floating diffusion layer, enabling complete charge depletion and reducing kTC noise while maintaining manageable structural complexity through modular design.
2Adaptability or versatility
If different photoelectric conversion units use different charge storage mechanisms, then each unit can be optimized for its specific function, but charge transfer and resetting become unsynchronized leading to deteriorated image quality
Solution Approach 1:
The patent applies the same charge storage mechanism (charge storage electrode with insulating layer) to all photoelectric conversion units (first, second, and third types). This creates equipotential conditions for charge transfer and resetting across all units, enabling synchronized operation and preventing image quality deterioration while still allowing each unit to be optimized for its specific photoelectric conversion function.
3Device complexity
If charges are not completely depleted from photoelectric conversion units, then the storage mechanism is simpler, but kTC noise and random noise increase reducing image quality
Solution Approach 1:
The patent introduces charge storage electrodes as intermediary elements between the photoelectric conversion layer and the floating diffusion layer. These intermediaries enable complete charge depletion by providing a controlled transfer path, thereby reducing kTC noise and random noise while maintaining a relatively simple overall structure through the use of standard semiconductor fabrication processes.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration effectively suppresses kTC noise and random noise, improving image quality by ensuring complete charge depletion and simultaneous resetting of all imaging elements, enabling a global shutter function.
Implementation Method 1
a photoelectric conversion layer 15 made of an organic material
Data Source
AI summary
An imaging device is provided. The imaging device may include a substrate having a first photoelectric conversion unit and a second photoelectric conversion unit at a light-incident side of the substrate. The second photoelectric conversion unit may include a photoelectric conversion layer, a first electrode, a second electrode above the photoelectric conversion layer, a third electrode, and an insulating material between the third electrode and the photoelectric conversion layer, wherein a portion of the insulating material is between the first electrode and the third electrode.