Plasmonic Color Filter Elements for Image Sensors
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Solution Overview
Problem
Conventional imaging pixels with color filter elements suffer from wider than desired transmission profiles and cross-talk issues due to the use of organic materials, which affect the accuracy of color filtration and image capture.
Innovation Solution
The implementation of plasmonic color filter elements with metal layers and strategically arranged openings, along with metal walls to reduce cross-talk, allows for precise wavelength transmission and minimizes interference between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional organic color filter elements are used, then the imaging pixel can be manufactured with existing processes, but the transmission profile becomes wider than desired and cross-talk occurs between adjacent pixels
Solution Approach 1:
The patent changes the material parameter from organic dye to metal layer, fundamentally altering the optical properties. The metal layer's plasma frequency and electron density parameters enable narrowband transmission at specific wavelengths, resolving the cross-talk issue while maintaining manufacturing feasibility through sputtering or evaporation processes
Solution Approach 2:
The invention creates a composite structure combining metal layers with dielectric materials (such as silicon dioxide or silicon nitride). This composite approach allows the metal to provide narrowband wavelength selection while the dielectric layers control the optical field distribution, achieving both accurate color filtration and reduced cross-talk between adjacent pixels
2Manufacturing precision
If conventional color filter elements are used, then the structure remains simple, but the transmission profile width exceeds the desired narrow bandwidth
Solution Approach 1:
The patent exploits the quantum mechanical parameter of plasma frequency in metal layers, which naturally produces narrowband optical transmission. By controlling the metal layer thickness and material composition, precise wavelength selection is achieved without requiring complex multi-layer interference structures, thus maintaining structural simplicity while improving transmission precision
3Manufacturing precision
If metal layers are introduced to narrow transmission profile, then color filtration accuracy improves, but manufacturing complexity increases
Solution Approach 1:
The patent replaces the chemical dye deposition process with physical vapor deposition (PVD) methods such as sputtering or evaporation. This substitution allows precise control of metal layer thickness at the nanometer scale, achieving narrowband transmission with standard semiconductor manufacturing equipment, thus improving color filtration accuracy while maintaining ease of manufacture
Solution Approach 2:
The invention changes the manufacturing parameter from chemical concentration control to physical thickness control. By precisely controlling the metal layer thickness (typically 5-50 nanometers) during deposition, the transmission wavelength and bandwidth are directly controlled, providing accurate color filtration through a well-established physical process rather than chemical synthesis
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 solution enhances the accuracy of color filtration, reduces cross-talk, and maintains a high fill factor, thereby improving the dynamic range and quantum efficiency of image sensors without sacrificing performance.
Implementation Method 1
The color filter element may include a metal layer having a plurality of openings and metal walls extending above an upper surface of the metal layer. The plasmonic color filter elements transmit a narrow profile of wavelengths
Data Source
AI summary
Image sensors may include plasmonic color filter elements that transmit specific wavelengths of incident light. Each plasmonic color filter element may be interposed between a respective microlens and photosensitive area. The plasmonic color filter elements may be formed from a metal layer such as gold, silver, platinum, aluminum, or copper and may have a pattern of openings in the metal layer that is designed to allow transmission of a certain type of light. To prevent cross-talk between adjacent pixels having plasmonic color filter elements, metal walls may be interposed between adjacent plasmonic color filter elements. The metal walls may extend above the upper surface of the metal layer that forms the plasmonic color filter elements. The metal walls may run around the periphery of each plasmonic color filter element.