Fully Depleted Charge Transfer Path for Flicker Mitigation
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Solution Overview
Problem
Conventional imaging systems suffer from image artifacts due to moving objects, flickering lighting, and objects with changing illumination, as well as low dynamic range issues, leading to artifacts such as missing parts of objects, edge color artifacts, and object distortion.
Innovation Solution
The implementation of imaging pixels with a fully depleted charge transfer path and additional features like interconnect layers and storage diodes, which enable improved charge transfer and mitigation of flicker artifacts, allowing for high dynamic range and high frame rate operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional imaging systems are used, then device complexity is low, but image quality deteriorates due to artifacts from moving objects, flickering lighting, and low dynamic range
Solution Approach 1:
The pixel is divided into multiple specialized regions: a photodiode for charge generation, a transfer diode for charge transport, and a floating diffusion region for signal readout. This segmentation allows each region to be optimized for its specific function, improving overall image quality while managing complexity through functional specialization.
Solution Approach 2:
A transfer diode is introduced as an intermediary component between the photodiode and floating diffusion region. This transfer diode acts as a mediator that moves generated charge to the readout region, enabling improved charge transfer efficiency and reducing artifacts from moving objects and flickering lighting.
2Reliability
If conventional charge transfer paths are used, then device complexity is low, but noise and artifacts increase due to incomplete charge transfer
Solution Approach 1:
The transfer diode serves as an intermediary that facilitates complete and efficient charge transfer from the photodiode to the floating diffusion region. This intermediary structure ensures that all generated charge is collected, reducing noise and artifacts while maintaining a relatively simple overall device architecture.
Solution Approach 2:
The charge transfer path is designed with specific electrical parameters optimized for complete charge collection. By adjusting and optimizing parameters such as diode doping concentrations and junction depths, the system achieves full charge transfer efficiency without requiring overly complex structures.
3Productivity
If simple pixel structures are used, then manufacturing is easier, but dynamic range and frame rate performance deteriorate
Solution Approach 1:
The pixel structure is segmented into specialized regions that can be independently optimized for high-speed operation. The transfer diode and floating diffusion region are designed to enable rapid charge transfer and readout, supporting high frame rates while maintaining manufacturability through standard semiconductor fabrication processes.
Solution Approach 2:
The pixel design incorporates dynamic charge transfer capabilities that enable rapid response to changing light conditions. The transfer diode allows for fast charge movement, and the floating diffusion region enables quick signal readout, together supporting high frame rate operation essential for capturing moving objects and flickering lighting conditions.
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 solution reduces noise and artifacts caused by moving objects and flickering lighting, while enabling high-quality image capture with minimized distortion and improved exposure control, even in scenes with varying illumination.
Implementation Method 1
Each pixel includes a photosensitive layer that receives incident photons (light) and converts the photons into electrical charge
Data Source
AI summary
An imaging pixel may have a fully depleted charge transfer path between a pinned photodiode and a floating diffusion region. A pinned transfer diode may be coupled between the pinned photodiode and the floating diffusion region. The imaging pixel may be formed in upper and lower substrates with an interconnect layer coupling the upper substrate to the lower substrate. The imaging pixel may include one or more storage diodes coupled between the transfer diode and the floating diffusion region. The imaging pixel may be used to capture high dynamic range images with flicker mitigation, images synchronized with light sources, or for high frame rate operation.