Plasmonic Color Filter Structure for Thin Miniaturized Image Sensors
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Solution Overview
Problem
The miniaturization of display apparatus and image sensor pixels has led to challenges in reducing the thickness of color filters while maintaining effective light transmission and color expression, as existing technologies struggle to efficiently tune the central wavelength and bandwidth of transmitted light for blue, green, and red colors.
Innovation Solution
A color filter design incorporating a metal array buried in multiple dielectric layers with varying refractive indices and thickness ratios, utilizing plasmonic resonance modes to adjust the transmission wavelength band and achieve a full width at half maximum of 50 nm or more, allowing for a thickness of 400 nm or less, suitable for miniaturized pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of the color filter is reduced to enable miniaturization, then the pixel size can be reduced, but the light transmission efficiency and color expression deteriorate
Solution Approach 1:
The patent changes the physical parameters of the color filter by introducing a metal array with specific dimensions (width 10-50 nm, length 50-200 nm) and spacing (10-50 nm) within the dielectric layers. By adjusting these parameters, the optical properties are tuned to achieve high light transmission efficiency in the visible range (400-700 nm) while maintaining a reduced overall thickness of 400 nm or less, thus resolving the contradiction between miniaturization and light transmission efficiency
Solution Approach 2:
The patent employs a composite structure consisting of multiple dielectric layers (with different refractive indices such as SiO2 with n=1.46 and TiO2 with n=2.5) combined with a metal array (using materials like Al, Ag, or Au). This composite material system enables enhanced optical performance through interference and plasmonic effects, allowing the thin color filter to maintain high light transmission and color expression despite reduced thickness
2Volume of moving object
If the thickness of the color filter is reduced, then miniaturization is achieved, but the bandwidth control and central wavelength tuning become difficult
Solution Approach 1:
The patent achieves bandwidth control and central wavelength tuning by adjusting geometric parameters of the metal array structure. Specifically, varying the metal element width (10-50 nm), length (50-200 nm), and spacing (10-50 nm) allows precise control over the transmission spectrum. The ratio of dielectric layer thicknesses (d1/d and d2/d between 0.1-0.9) further enables tuning of the central wavelength to match blue (450-495 nm), green (495-520 nm), and red (620-750 nm) color ranges, simplifying bandwidth control despite reduced thickness
3Illumination intensity
If multiple dielectric layers with different refractive indices are used to tune wavelength, then color expression is improved, but the manufacturing process becomes more complex
Solution Approach 1:
The patent applies local quality by assigning different refractive indices to specific dielectric layers to optimize optical performance for different color channels. The first dielectric layer (with higher refractive index like TiO2, n=2.5) and second dielectric layer (with lower refractive index like SiO2, n=1.46) are strategically positioned to create constructive interference at desired wavelengths. This localized optimization of material properties enables precise color expression while maintaining a relatively simple layered manufacturing process
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 solution enables efficient tuning of the central wavelength and bandwidth for blue, green, and red colors, ensuring high transmittance and full width at half maximum, making it suitable for miniaturized image sensors and electronic apparatuses while maintaining a thin profile.
Implementation Method 1
In a first plasmonic resonance mode occurring between the first dielectric layer and each of the plurality of metal elements, the central wavelength of a transmission wavelength band of light may be tuned to a wavelength of any one of blue color, green color, or red color. In a second plasmonic resonance mode occurring between the second dielectric layer and each of the plurality of metal elements, transmitted light may have a full width at half maximum of 50 nm or more.
Data Source
AI summary
Disclosed is a color filter according to an example embodiment, an image sensor, and an electronic apparatus having the image sensor. The color filter includes a first dielectric layer, a second dielectric layer on the first dielectric layer, and a plurality of metal elements buried in both of the first dielectric layer and the second dielectric layer in lateral contact with each of the first dielectric layer and the second dielectric layer.