Solid-State Image Sensor Edge Pixels for Dark Current Control
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Solution Overview
Problem
In solid-state image pickup devices, particularly those using chemical semiconductors like InGaAs, dark current issues at the interface of the photoelectric conversion unit lead to image quality degradation, especially at the outermost pixels and boundary regions, necessitating ineffective pixels to prevent blooming, which increases chip area and cost.
Innovation Solution
The implementation of charge emitting pixels and specific pixel structures that keep the reset transistor on or short-circuit the reading out circuit at the outermost circumference and OPB regions to prevent dark current flow, combined with antireflection layers and high concentration N-type layers to manage charge accumulation and prevent blooming.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If many ineffective pixels are provided at the outermost circumference and boundary regions, then dark current influence and blooming are suppressed, but chip area increases and fabrication cost increases
Solution Approach 1:
The patent applies local quality by providing ineffective pixels only at specific locations (outermost circumference and boundary regions between effective pixel region and OPB region) where dark current and blooming occur, rather than uniformly across the entire sensor. This localized approach suppresses dark current influence where it matters most while minimizing the total area occupied by ineffective pixels.
Solution Approach 2:
The patent extracts and removes the harmful ineffective pixels from the sensor structure by precisely defining their location only at the outermost circumference and boundary regions. This extraction eliminates the need for extensive ineffective pixel regions while maintaining image quality, thereby reducing chip area.
2Reliability
If many ineffective pixels are provided to prevent blooming influence on OPB pixels, then image quality is maintained, but fabrication cost increases
Solution Approach 1:
The patent implements local quality by concentrating ineffective pixels only at the boundary regions where they are most needed to prevent blooming influence on OPB pixels. This localized placement reduces the total number of ineffective pixels required compared to uniform distribution, thereby reducing fabrication complexity and cost.
Solution Approach 2:
The patent applies partial action by providing ineffective pixels only where necessary (at boundary regions) rather than excessively across the entire sensor array. This partial approach maintains sufficient protection against blooming while minimizing the number of ineffective pixels, thus reducing fabrication cost.
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 suppresses dark current and blooming, minimizing ineffective pixels, reducing chip area, and lowering fabrication costs while maintaining image quality.
Implementation Method 1
antireflection layers and high concentration N-type layers to manage charge accumulation
Implementation Method 2
a first substrate that forms a photoelectric conversion unit... InGaAs is used as a photoelectric conversion unit
Data Source
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AI summary
The present technology relates to a solid-state image pickup device that can suppress dark current thereby to suppress picture quality degradation. 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.