Imaging Element Dual Electrode Charge Collection Architecture
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Solution Overview
Problem
Current image sensors face challenges in miniaturization and sensitivity due to the need for multiple charge accumulation regions in semiconductor substrates and the inefficiency of signal charge collection, which reduces photoelectric conversion area and increases manufacturing costs.
Innovation Solution
The imaging element features a photoelectric conversion layer with a first electrode collecting negative signal charges and a second electrode collecting positive signal charges, both positioned on the side opposite to the light incident surface, eliminating the need for multiple charge accumulation regions and reducing coupling capacitance, thereby enhancing sensitivity and allowing for miniaturization.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple charge accumulation regions including p-type and n-type semiconductors are formed in a semiconductor substrate, then both electrons and holes can be detected as signal charges, but the device size increases and manufacturing complexity increases
Solution Approach 1:
The patent transitions from a planar substrate-based charge accumulation structure to a three-dimensional stacked structure where the photoelectric conversion layer is positioned above the substrate with electrodes on the opposite surface. This dimensional change eliminates the need for multiple charge accumulation regions in the substrate while maintaining dual charge detection capability.
Solution Approach 2:
The invention extracts the charge accumulation function from the semiconductor substrate and relocates it to a separate photoelectric conversion layer positioned above the substrate. This separation allows the substrate to focus on signal processing while the photoelectric conversion layer handles charge generation and accumulation, simplifying the overall structure.
2Productivity
If the photoelectric conversion layer is sandwiched between a pair of electrodes, then charge collection is efficient, but the photoelectric conversion region is reduced
Solution Approach 1:
The patent positions both electrodes on the same surface of the photoelectric conversion layer (the surface opposite to the light incident surface) rather than sandwiching the layer between electrodes. This dimensional reconfiguration allows light to incident on one surface while charges are collected at the opposite surface, maximizing the photoelectric conversion area.
Solution Approach 2:
The invention segments the charge collection function into two separate electrodes (first electrode for electrons, second electrode for holes) positioned side-by-side on the same surface, rather than using a single sandwiched electrode structure. This segmentation allows independent optimization of electron and hole collection paths.
3Device complexity
If one charge is utilized as signal while the other is discharged, then the structure is simple, but sensitivity is reduced
Solution Approach 1:
The patent combines the detection of both electrons and holes as useful signal charges by providing separate collection electrodes for each charge type. Instead of discarding one charge type, both are captured and utilized, effectively merging two detection channels into a single imaging element to enhance sensitivity.
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 enlarges the photoelectric conversion region, improves sensitivity, and reduces manufacturing complexity and costs by eliminating the need for multiple charge accumulation regions, while also enhancing charge-voltage conversion efficiency.
Implementation Method 1
a photoelectric conversion layer; a first electrode that collects a negative signal charge generated in the photoelectric conversion layer; and a second electrode that collects a positive signal charge generated in the photoelectric conversion layer
Data Source
AI summary
An imaging element according to an embodiment of the present disclosure includes: a photoelectric conversion layer; a first electrode that collects a negative signal charge generated in the photoelectric conversion layer; and a second electrode that collects a positive signal charge generated in the photoelectric conversion layer. Each of the first electrode and the second electrode is provided on side opposite to a light incident surface of the photoelectric conversion layer.