Organic Photoelectric Conversion Layer Image Sensor Architecture
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Solution Overview
Problem
Image sensors with silicon photoelectric conversion regions face sensitivity degradation due to reduced light absorption areas as pixel size decreases, leading to current leakage and reset noise issues.
Innovation Solution
Replacing the silicon photoelectric conversion region with an organic photoelectric conversion region, which includes a substrate with a transmission gate electrode, a storage node, and an organic photoelectric conversion layer, with a cover insulating layer that overlaps the storage node to prevent current leakage and reduce noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is decreased, then the resolution is improved, but the light absorption area decreases leading to sensitivity degradation
Solution Approach 1:
The patent introduces a vertical stacking architecture where the photodetector, transfer gate, and storage node are arranged in three dimensions. This allows the light absorption area to extend vertically while maintaining small pixel footprint, thereby improving resolution without sacrificing sensitivity. The stacked configuration enables independent optimization of horizontal pixel density and vertical light absorption path.
Solution Approach 2:
The patent implements a nested structure where the storage node is positioned beneath the transfer gate, which in turn is positioned beneath the photodetector. This nested arrangement allows multiple functional elements to occupy overlapping horizontal spaces, maximizing the use of vertical space and maintaining large light absorption area even in small pixels.
2Productivity
If the transmission gate electrode directly contacts the semiconductor layer, then the charge transfer efficiency is improved, but current leakage increases
Solution Approach 1:
The patent introduces an insulating layer as an intermediary between the transmission gate electrode and the semiconductor layer. This insulating layer prevents direct contact that would cause current leakage, while still allowing efficient charge transfer through its conductive properties or proximity coupling mechanism.
Solution Approach 2:
The patent applies different material properties to different regions: the transmission gate electrode has conductive properties for charge transfer, while the insulating layer has insulating properties to prevent leakage. This local differentiation of material qualities allows simultaneous achievement of efficient charge transfer and leakage prevention.
3Quantity of substance
If the storage node is directly exposed, then the charge storage capacity is improved, but reset noise increases due to parasitic fields
Solution Approach 1:
The patent introduces a cover insulating layer as an intermediary that surrounds or covers the storage node. This insulating layer acts as a shield that blocks parasitic electric fields from reaching the storage node, thereby reducing reset noise while allowing the storage node to maintain its full charge storage capacity.
Solution Approach 2:
The cover insulating layer is positioned in advance around the storage node to provide protective cushioning against parasitic fields. This preemptive shielding prevents the harmful effects of electric field interference before they can affect the stored charges.
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
The organic photoelectric conversion region enhances sensitivity and reduces current leakage and reset noise, improving the overall performance of the image sensor by effectively absorbing light and transmitting charges without parasitic field interference.
Implementation Method 1
an organic photoelectric conversion layer on an upper surface of the semiconductor layer and an upper surface of the first cover insulating layer
Data Source
AI summary
An image sensor includes a substrate including a first surface and a second surface, a first transmission gate electrode on the first surface of the substrate, a storage node on the first surface of the substrate and including a first storage gate electrode isolated from direct contact with the first transmission gate electrode, a dielectric layer on the first storage gate electrode, and a semiconductor layer on the dielectric layer. The image sensor may include a first cover insulating layer on the semiconductor layer and vertically overlapping the first transmission gate electrode, and an organic photoelectric conversion layer on an upper surface of the semiconductor layer and an upper surface of the first cover insulating layer.