Solid-State Imaging Device Pixel Cell Segmentation
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Solution Overview
Problem
In CMOS-type solid-state imaging devices, achieving simultaneous exposure and signal accumulation across all pixels while maintaining a small pixel pitch is challenging due to the need for shared circuits and increased signal lines, which complicates the fabrication and control of micro-bumps for electrical connections between substrates.
Innovation Solution
The design incorporates a solid-state imaging device with a first substrate containing photoelectric conversion elements and a second substrate with output circuits, where connection parts are strategically positioned to facilitate equal distances and clearances between pixel cells, allowing for simultaneous exposure and signal accumulation across multiple pixels, reducing chip area and noise by sharing circuit elements and using analog memories with greater capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If micro-bumps are used to connect first substrate and second substrate, then electrical connection between substrates is achieved, but fabrication difficulty increases when pixel pitch is small
Solution Approach 1:
The pixel array is divided into multiple pixel cells, with connection parts strategically positioned at specific regions (e.g., corners or edges) of each pixel cell. This segmentation allows micro-bumps to be placed only at these specific locations rather than under every pixel, significantly reducing fabrication difficulty while maintaining electrical connection reliability.
2Area of stationary object
If circuits are shared by multiple pixels, then chip area is reduced, but device complexity increases
Solution Approach 1:
Multiple pixels share common circuit elements such as readout circuits, amplifiers, and connection parts. By merging these functions into shared components located at pixel cell boundaries or common regions, the chip area is reduced while the complexity is managed through systematic design patterns.
Solution Approach 2:
The connection parts and circuit elements are designed to serve multiple pixels simultaneously. For example, a single connection part may handle signals from multiple pixels, and shared circuits perform functions for entire pixel cells or arrays, reducing overall device complexity through multi-functionality.
3Reliability
If connection parts are positioned to allow equal distances between pixel cells, then simultaneous exposure and signal accumulation is enabled, but clearance requirements increase
Solution Approach 1:
Connection parts are positioned at specific asymmetric locations within pixel cells (such as corners or specific edges) rather than centrally. This asymmetric positioning allows for equal distances between adjacent connection parts of neighboring pixel cells, enabling simultaneous exposure and signal accumulation while optimizing the use of available clearance space.
4Measurement precision
If pixel pitch is reduced, then resolution is improved, but micro-bump fabrication becomes more difficult
Solution Approach 1:
By segmenting the pixel array into multiple pixel cells with connection parts positioned at specific regions, the effective pitch for micro-bump placement becomes larger than the pixel pitch. This allows high-resolution pixel arrays (small pixel pitch) to be fabricated with micro-bumps at coarser intervals, resolving the contradiction between resolution and fabrication difficulty.
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 enables efficient signal processing and noise reduction, improving image quality by allowing simultaneous exposure and accumulation across all pixels while maintaining a small pixel pitch and reducing chip area and noise interference.
Implementation Method 1
signal charges generated by photoelectric conversion units
Data Source
AI summary
A solid-state imaging device generates signals by photoelectric conversion elements included in a first substrate in which circuit elements of a plurality of pixels are arranged. The solid-state imaging device outputs, from the plurality of pixels via output circuits, the signals that are generated by the photoelectric conversion elements and are via connection parts that electrically connect the first substrate with a second substrate, the output circuits being included in the second substrate.