Imaging Device Pixel Electrode Overlap for Light Leakage Suppression
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Solution Overview
Problem
In imaging devices employing the global shutter method, light leakage into charge accumulation regions leads to parasitic light reception sensitivity, causing image quality deterioration due to false signals from photoelectric conversion occurring when the shutter is not open.
Innovation Solution
The imaging device is designed with a semiconductor substrate, featuring first and second pixels with photoelectric converters and charge accumulation regions, where the area of the second electrode is greater than the fourth electrode, and both charge accumulation regions overlap with the second electrode in plan view, reducing light leakage and parasitic light reception sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding film is provided between adjacent lower electrodes to suppress light leakage, then image quality deteriorates less, but device complexity increases
Solution Approach 1:
The patent extracts the light-shielding function from a separate film layer and integrates it into the lower electrode structure itself. By making the lower electrode extend further laterally, it naturally blocks light from reaching adjacent charge accumulation regions, eliminating the need for additional light-shielding films and reducing overall device complexity.
Solution Approach 2:
The lower electrode is given dual functionality: it serves both as an electrical connection element and as a light-shielding structure. This multi-functional design eliminates the need for separate light-shielding components, resolving the contradiction between light leakage suppression and device complexity.
2Use of energy by moving object
If the area of photoelectric converters is increased to improve light reception, then sensitivity increases, but light leakage into charge accumulation regions increases
Solution Approach 1:
The patent addresses the light leakage problem by transitioning to a three-dimensional spatial arrangement. By stacking the photoelectric converter above the charge accumulation region and using lateral extension of lower electrodes, it creates vertical and horizontal separation that prevents light from reaching adjacent charge regions while maintaining large photoelectric converter area for high sensitivity.
Solution Approach 2:
The lower electrodes are extended locally in specific directions to block light paths to adjacent charge accumulation regions, while the photoelectric converters maintain their large area for optimal light reception. This localized structural modification addresses light leakage without compromising overall sensitivity.
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 effectively reduces photoelectric conversion of leaked light in charge accumulation regions, thereby suppressing image quality deterioration and parasitic light reception sensitivity.
Implementation Method 1
a first photoelectric converter configured to convert incident light into charge
Data Source
AI summary
An imaging device including a semiconductor substrate; a first pixel including a first photoelectric converter configured to convert incident light into charge, and a first diffusion region in the semiconductor substrate, configured to electrically connected to the first photoelectric converter and a second pixel including a second photoelectric converter, configured to convert incident light into charge, and a second diffusion region in the semiconductor substrate, configured to electrically connected to the second photoelectric converter, wherein an area of the first photoelectric converter is greater than an area of the second photoelectric converter in a plan view, both the first diffusion region and the second diffusion region overlap with the first photoelectric converter in the plan view, and neither the first diffusion region nor the second diffusion region overlaps with the second photoelectric converter in the plan view.