Composite Imaging Element Back Illumination Sensitivity
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Solution Overview
Problem
Current imaging devices face challenges in achieving high sensitivity due to the limitations of front illumination type imaging elements, where light is blocked by circuits, and composite imaging elements with superposed pixels face issues with light attenuation and inadequate sensitivity, especially when using color filters.
Innovation Solution
A composite imaging element is designed with a first back illumination type imaging element and a second front illumination type imaging element, where the first imaging element receives light without color filters and the second imaging element has a micro-lens and color filters to optimize light collection and conversion, allowing for improved sensitivity and reduced color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of moving object
If a front illumination type imaging element is used with circuits formed along the boundary of the opto-electrical conversion part, then the light receiving surface area can be maximized, but light is blocked by the mask and circuit, reducing the open ratio to about 60% at best
Solution Approach 1:
The patent inverts the conventional front illumination structure to a back illumination structure, where light enters through the back surface of the semiconductor substrate rather than the front. This allows light to reach the opto-electrical conversion part without being blocked by circuits and masks formed on the front surface, thereby increasing the open ratio while maintaining maximum light receiving surface area.
2Measurement precision
If the pixel count of the imaging element is increased without changing the size, then the resolution is improved, but the surface area per opto-electrical conversion part decreases, reducing sensitivity
Solution Approach 1:
The patent utilizes the third dimension (depth) by implementing a back illumination structure with a removed or thinned substrate, allowing light to approach the opto-electrical conversion part from the rear. This dimensional change enables more efficient light utilization, maintaining high sensitivity even when pixel density is increased, thus resolving the trade-off between resolution and sensitivity.
3Reliability
If a back illumination imaging element is used to increase sensitivity, then light reaches the opto-electrical conversion part more efficiently, but a silicon dioxide protective layer is required between the color filter and opto-electrical conversion part
Solution Approach 1:
The patent extracts or removes the silicon substrate in back illumination imaging elements, creating a light-receiving surface that directly exposes the opto-electrical conversion part. This eliminates the need for complex protective film structures between color filters and the conversion part, as light enters from the back without passing through the substrate that would require protection.
4Use of energy by moving object
If multiple imaging elements are superposed to improve light utilization efficiency, then opto-electrical conversion is enhanced, but light attenuation occurs and sensitivity remains inadequate
Solution Approach 1:
The patent inverts the illumination direction to back illumination, allowing light to enter the superposed imaging element structure without being blocked by front surface circuits and masks. This enables more light to reach the opto-electrical conversion parts in each layer, reducing attenuation and improving overall sensitivity in composite imaging element configurations.
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 enhances the sensitivity of both imaging elements by maximizing light reception and minimizing color mixing, enabling the capture of high-quality images with improved color reproducibility, particularly in capturing blue light, which is often attenuated in traditional systems.
Implementation Method 1
a first opto-electrical conversion part configured to receive light with a first basic color and a second basic color different from the first basic color and convert light received by the first opto-electrical conversion part into a first electrical signal
Implementation Method 2
a second opto-electrical conversion part configured to receive light emitted from the first opto-electrical conversion part and convert light received by the second opto-electrical conversion part into a second electrical signal
Implementation Method 3
the second imaging element has a micro-lens and color filters to optimize light collection and conversion
Implementation Method 4
the second imaging element has a micro-lens and color filters to optimize light collection and conversion
Data Source
AI summary
A composite imaging element is provided that includes a first imaging element and a second imaging element. The first imaging element has a plurality of first opto-electrical conversion parts, a first light receiving surface, and a first circuit part. The first opto-electrical conversion parts are configured to receive light with a first basic color and a second basic color different from the first basic color. The first opto-electrical conversion parts are also configured to convert light received by the first opto-electrical conversion parts into a first electrical signal. The first light receiving surface is formed by the first opto-electrical conversion parts. The first circuit part transmits the first electrical signal. The second imaging element has a plurality of second opto-electrical conversion parts and a second circuit part. The second opto-electrical conversion parts receive light emitted from the first opto-electrical conversion parts.