Multilayered Charge Holding Films for Dark Current Control
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Solution Overview
Problem
Conventional solid-state imaging devices generate brighter images than actual due to dark current, which is not effectively controlled by existing fixed charge layers, leading to inaccurate image capture.
Innovation Solution
A solid-state imaging device with a multilayered fixed charge layer structure, where the second charge holding film has a higher oxygen concentration than the first, effectively increasing the amount of electric charges held, thereby enhancing the control of dark current generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a fixed charge layer is formed above the light receiving unit, then dark current generation is controlled, but the amount of electric charges held is insufficient for reliable control
Solution Approach 1:
The fixed charge layer is divided into multiple charge holding films (first charge holding film and second charge holding film) with different oxygen concentrations. Each film segment contributes to charge holding capacity, with the high-oxygen concentration second film providing enhanced charge holding ability to reliably control dark current.
Solution Approach 2:
Different regions of the fixed charge layer are given different oxygen concentrations to optimize local charge holding properties. The second charge holding film with higher oxygen concentration is positioned to provide superior charge holding capacity where needed most for dark current control.
2Reliability
If the amount of electric charges in the fixed charge layer is increased, then dark current control is improved, but image accuracy may be compromised due to excessive charge accumulation
Solution Approach 1:
The oxygen concentration parameter is varied across different charge holding films to optimize charge holding capacity. By controlling oxygen concentration rather than simply increasing layer thickness or charge density, the patent achieves improved dark current control while maintaining image accuracy through precise parameter management.
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
The multilayered structure significantly reduces dark current, resulting in more accurate and reliable image capture by increasing the amount of electric charges that can be held in the fixed charge layer, leading to clearer and less blurry images.
Implementation Method 1
concentration of oxygen in the second charge holding film is higher than concentration of oxygen in the first holding film
Implementation Method 2
the positive electric charges in the light receiving unit are accumulated at the upper surface of the light receiving unit, because the negative electric charge in the fixed charge layer attracts the positive electric charge
Implementation Method 3
the light receiving unit performs a photoelectric conversion of an incident light
Data Source
AI summary
A solid-state imaging device according to embodiments of the present disclosure includes a light receiving unit, a first charge holding film, and a second charge holding film. The light receiving unit converts the incident light to an electric current. The first charge holding film is formed above the light receiving unit and holds electric charges. The second charge holding film is formed on the first charge holding film and holds electric charges. Further, concentration of oxygen in the second charge holding film is higher than concentration of oxygen in the first charge holding film.