Image Sensor Storage Node and Transfer Transistor Design
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Solution Overview
Problem
Image sensors face challenges in reducing noise and improving the mobility of electric charge, particularly in shared pixel structures where semiconductor and organic photoelectric conversion layers are used, leading to inefficiencies in signal transmission and power consumption.
Innovation Solution
The design incorporates a storage node and a transfer transistor corresponding to an organic photoelectric conversion layer, with a specific configuration that includes a first organic photoelectric conversion layer, a floating diffusion region, a storage node with a bias signal electrode, and a transfer transistor with a transfer control signal gate, allowing for precise signal transmission and reduced noise by improving charge mobility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a shared structure with semiconductor and organic photoelectric conversion layers is used, then device integration is improved, but noise increases and charge mobility deteriorates
Solution Approach 1:
The patent divides the photoelectric conversion system into separate semiconductor and organic photoelectric conversion layers, each with dedicated transfer transistors and storage nodes. This segmentation isolates the charge transfer paths, preventing noise interference between different photoelectric conversion materials while maintaining high integration benefits.
2Measurement precision
If transfer transistors are added for organic photoelectric conversion layer, then signal transmission precision is improved, but device complexity increases
Solution Approach 1:
The patent merges the transfer transistor structures for both semiconductor and organic photoelectric conversion layers into a shared configuration where transfer gates and control circuits are combined. This merging approach maintains precise signal transmission for each layer while reducing the overall transistor count and device complexity compared to completely separate transfer paths.
3Speed
If charge mobility is improved in organic photoelectric conversion layer, then signal transmission is enhanced, but power consumption increases
Solution Approach 1:
The patent optimizes the organic photoelectric conversion layer parameters including material composition, layer thickness, and interface characteristics to enhance charge mobility. Simultaneously, the transfer transistor gate voltages and operating conditions are adjusted to achieve efficient charge transfer at lower power consumption levels, balancing speed and energy usage through parameter optimization.
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 enhances the precision of signal transmission to the floating diffusion region, reduces noise, and minimizes power consumption by storing and transmitting optical signals efficiently, thereby improving the reliability and performance of the image sensor.
Implementation Method 1
each pixel region of a unit pixel region may include a semiconductor photoelectric conversion layer, and the unit pixel region may share an organic photoelectric conversion layer
Data Source
AI summary
An image sensor includes a first organic photoelectric conversion layer on a base layer, a floating diffusion region in the base layer, a first storage node including a first electrode layer, which is configured to receive a bias signal, a first portion of a first semiconductor layer which includes a semiconductor material, and a first portion of a first dielectric layer. The first dielectric layer extends between the first electrode layer and the first semiconductor layer. The first storage node is electrically connected to the first organic photoelectric conversion layer. The image sensor includes a first transfer transistor including the first dielectric layer, the first semiconductor layer, and a first transfer gate electrode which is configured to receive first transfer control signal. The first transfer transistor has a first end electrically connected to the first storage node and a second end electrically connected to the floating diffusion region.