Image Sensor Pixel Layout for Edge Dark Current Suppression
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Solution Overview
Problem
In solid-state image pickup devices, dark current at the outermost circumference of the pixel array region and at the boundary between effective pixel and OPB regions leads to image quality degradation due to blooming effects, necessitating the use of many ineffective pixels, which increases chip area and cost.
Innovation Solution
Incorporating voltage application pixels with a fixed voltage on the outermost circumference or between effective and OPB pixels, and using a PN junction-free or MIS structure at the processed portion end face to suppress dark current, along with capacitive elements and changeover controlling units to adjust voltage and capacitance based on the environment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If many ineffective pixels are used to avoid dark current influence, then image quality is improved, but chip area and cost increase
Solution Approach 1:
The patent applies parameter changes by dynamically adjusting the voltage applied to pixels based on their location and operational conditions. Specifically, a reduced voltage is applied to pixels on the outermost circumference and boundary pixels during integration periods when dark current suppression is critical, thereby suppressing dark current without requiring additional ineffective pixels, thus maintaining image quality while reducing chip area
Solution Approach 2:
The patent implements dynamics by making the voltage application flexible and adaptive rather than fixed. The voltage to each pixel is dynamically controlled based on its position in the array and the current integration period, allowing the system to optimize performance in real-time and suppress dark current effects without permanently sacrificing pixel functionality, thereby avoiding the need for extra ineffective pixels
2Reliability
If many ineffective pixels are used to prevent blooming influence, then image quality is improved, but cost increases
Solution Approach 1:
The patent uses parameter changes by adjusting the voltage level applied to pixels based on their susceptibility to blooming. Boundary pixels and outermost pixels have their voltage reduced during critical integration periods, dynamically suppressing blooming effects without requiring additional ineffective pixels or complex hardware modifications, thereby reducing manufacturing cost while maintaining image quality
3Device complexity
If fixed voltage is applied to all pixels, then circuit simplicity is maintained, but dark current increases at boundary pixels
Solution Approach 1:
The patent applies local quality by implementing different voltage levels for different pixel locations rather than a uniform voltage across all pixels. Pixels on the outermost circumference and boundary pixels receive reduced voltage during integration periods when dark current suppression is critical, while other pixels maintain normal voltage levels. This localized approach suppresses dark current at problematic locations without unnecessarily complicating the overall circuit design
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 approach effectively reduces dark current, minimizes ineffective pixels, and enhances image quality by preventing blooming and reducing chip area and fabrication costs.
Implementation Method 1
pixels each including a photoelectric conversion unit having one of a chemical semiconductor, amorphous silicon, germanium, a quantum dot photoelectric conversion film and an organic photoelectric conversion film
Data Source
AI summary
A solid-state image pickup device includes a pixel array region in which pixels each including a photoelectric conversion unit having one of a chemical semiconductor, amorphous silicon, germanium, a quantum dot photoelectric conversion film and an organic photoelectric conversion film are disposed two-dimensionally in rows and columns. The pixel array region has a voltage application pixel on an outermost circumference of the pixel array region or on the outer side with respect to an effective pixel region of the pixel array region, the voltage application pixel being one of the pixels to which a fixed voltage is normally applied. The present technology can be applied, for example, to a solid-state image pickup device and so forth.