Stacked Image Sensor Wavelength Detection
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Solution Overview
Problem
Conventional image sensors face challenges in efficiently detecting lights with different wavelengths, leading to limitations in operation speed and integration density, and often require additional components like color filters and micro lenses.
Innovation Solution
The image sensor employs a multi-layered structure with floating diffusion parts, storage nodes, and photoelectric conversion parts stacked on the substrate, allowing for simultaneous detection of lights with different wavelengths using a single transfer gate, eliminating the need for color filters and micro lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional image sensors use single-layer photoelectric conversion structure, then fabrication is simpler, but detection capability for different wavelengths is limited and requires additional components like color filters and micro lenses
Solution Approach 1:
The patent transitions from a planar single-layer photoelectric conversion structure to a vertical multi-layer stacked structure. By stacking multiple photoelectric conversion parts (first, second, and third layers) at different heights on the substrate, the system gains the ability to detect different wavelengths of light simultaneously without requiring additional lateral components like color filters and micro lenses.
Solution Approach 2:
The photoelectric conversion function is segmented into multiple independent layers, where each layer (first, second, third photoelectric conversion parts) is responsible for detecting specific wavelength ranges. This segmentation allows each layer to be optimized for particular wavelengths while maintaining overall system simplicity by eliminating the need for separate color filter assemblies.
2Measurement precision
If conventional image sensors use multiple components (color filters, micro lenses) for wavelength detection, then detection accuracy improves, but operation speed decreases and integration density is reduced
Solution Approach 1:
The patent merges the wavelength detection function into the photoelectric conversion layers themselves rather than using separate color filters and micro lenses. By integrating wavelength-specific detection capabilities directly into the stacked photoelectric conversion parts, the system achieves both high detection precision and fast operation speed, as the merged structure eliminates signal processing delays associated with multiple discrete components.
Solution Approach 2:
Each photoelectric conversion layer serves multiple functions: it acts as both the photoelectric conversion element and the wavelength-specific detection filter. The first layer detects a first wavelength, the second layer detects a second wavelength, and the third layer detects a third wavelength, allowing each component to be universal in its dual role as converter and spectral selector, thereby improving both precision and speed.
3Adaptability or versatility
If conventional image sensors use additional components like color filters and micro lenses, then wavelength detection capability improves, but fabrication complexity and cost increase
Solution Approach 1:
The patent employs vertical stacking of photoelectric conversion layers along the height dimension rather than arranging color filters and micro lenses in the lateral plane. This vertical integration simplifies fabrication by using standard semiconductor layering techniques, reducing the need for complex alignment and assembly processes required for multiple discrete optical components.
Solution Approach 2:
The patent uses composite material structures where each photoelectric conversion layer is composed of materials optimized for specific wavelength ranges. The first, second, and third photoelectric conversion parts utilize different semiconductor materials or material compositions that inherently provide wavelength-selective detection, eliminating the need for separate color filter materials and simplifying the overall fabrication process.
4Productivity
If conventional image sensors use traditional pixel structure, then manufacturing is easier, but cross-talk between pixels occurs and integration density is limited
Solution Approach 1:
The patent utilizes the vertical dimension by stacking photoelectric conversion layers at different heights, allowing pixels to be closely packed in the lateral plane without increasing cross-talk. The vertical separation of detection layers combined with precise optical path control enables high integration density while maintaining pixel isolation, as each layer's detection region is spatially separated from adjacent pixels both laterally and vertically.
Solution Approach 2:
The patent segments the photoelectric conversion function into vertically separated layers with distinct detection regions. Each photoelectric conversion part (first, second, third layers) has a defined active area that is spatially segmented from adjacent pixels, preventing cross-talk while enabling higher integration density through efficient use of the vertical space above each pixel location.
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 operation speed and integration density while preventing cross-talk between pixels, reducing fabrication complexity and cost.
Implementation Method 1
the photoelectric conversion parts absorb lights with different wavelengths and generate electric charges from the absorbed lights
Data Source
AI summary
An image sensor may include a substrate including a plurality of unit pixel regions and having first and second surfaces facing each other. Each of the unit pixel regions may include a plurality of floating diffusion parts spaced apart from each other in the substrate, storage nodes provided in the substrate to be spaced apart from and facing the floating diffusion parts, a transfer gate adjacent to a region between the floating diffusion parts and the storage nodes, and photoelectric conversion parts sequentially stacked on one of the first and second surfaces. Each of the photoelectric conversion parts may include common and pixel electrodes respectively provided on top and bottom surfaces thereof and each pixel electrode may be electrically connected to a corresponding one of the storage nodes.