Shared-Pixel Image Sensor IPO Barrier for Charge Overflow Control
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
There is a need for image sensors with a simplified manufacturing process that maintains stable electrical characteristics in shared pixel structures, particularly as pixel sizes are miniaturized and integration increases across various applications.
Innovation Solution
The image sensor design incorporates a substrate with a floating diffusion region, multiple photodiodes, and an inter-pixel overflow (IPO) barrier that overlaps the floating diffusion region vertically, providing a simplified process while ensuring stable electrical characteristics through the IPO barrier's contact with each photodiode and its positioning to prevent charge overflow and enhance full well capacity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If pixel sizes are miniaturized and integration increases, then image sensors can be used in more applications with higher integration, but manufacturing complexity increases and stable electrical characteristics become harder to secure
Solution Approach 1:
The IPO barrier is merged with the photodiode structure by forming the IPO barrier within the same semiconductor region as the photodiode, eliminating the need for separate barrier structures and reducing manufacturing steps while maintaining electrical isolation functionality
Solution Approach 2:
The IPO barrier serves multiple functions: it prevents charge overflow between adjacent pixels, maintains electrical isolation, and is formed using the same doping process as the photodiode itself, making the structure universally applicable to shared pixel designs without adding process complexity
2Productivity
If pixel sizes are miniaturized, then more pixels can be integrated, but maintaining stable electrical characteristics becomes more difficult
Solution Approach 1:
The IPO barrier is locally positioned at the boundary regions between adjacent photodiodes, providing electrical isolation exactly where needed while leaving the central sensing regions of each pixel unaffected, thus maintaining stable electrical characteristics in miniaturized pixels
Solution Approach 2:
The IPO barrier acts as an intermediary structure between adjacent photodiodes, preventing direct electrical interaction and charge overflow while allowing each photodiode to maintain its independent electrical characteristics even at reduced pixel sizes
3Reliability
If IPO barrier is positioned to overlap floating diffusion region, then charge overflow is prevented and full well capacity increases, but device structure becomes more complex
Solution Approach 1:
The IPO barrier achieves three-dimensional overlap with the floating diffusion region by extending in the vertical direction, preventing charge overflow through vertical electrical isolation while maintaining a simple planar footprint that does not increase lateral device complexity
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 design allows for increased full well capacity and improved sensitivity and color quality in image sensors, even with reduced pixel sizes, by preventing local saturation and allowing for efficient electron accumulation across photodiodes, thus maintaining excellent sensitivity and color fidelity.
Implementation Method 1
image sensors that acquire images and convert the acquired images into electrical signals
Data Source
AI summary
An image sensor includes a substrate having a sensing area, a floating diffusion region arranged in the sensing area, a plurality of photodiodes arranged around the floating diffusion region in the sensing area, and an inter-pixel overflow (IPO) barrier in contact with each of the plurality of photodiodes, the IPO barrier overlapping the floating diffusion region in a vertical direction at a position vertically spaced apart from the floating diffusion region within the sensing area.