Multi-Layer Anti-Reflective Image Sensor Wavelength Optimization
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Solution Overview
Problem
Conventional image sensors face challenges in maximizing light sensitivity due to reflection issues, which affect the efficiency of light transmission across different wavelengths.
Innovation Solution
The implementation of a multi-layer anti-reflection layer structure comprising SiO2, Si3N4, and heat-treated SiON layers with specific refractive indices and thicknesses, strategically positioned over color sensing pixels to minimize light reflection and enhance transmission across various wavelengths.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a conventional single-layer anti-reflection layer is used, then the manufacturing process is simple, but light transmission efficiency is insufficient across different wavelengths
Solution Approach 1:
The anti-reflection layer is divided into three distinct sub-layers (first, second, and third sub-layers) with different refractive indices and thicknesses. Each sub-layer targets specific wavelength ranges, with the first sub-layer (lower refractive index) optimizing for long wavelengths and the third sub-layer (higher refractive index) optimizing for short wavelengths, thereby segmenting the anti-reflection function across multiple specialized layers
Solution Approach 2:
Different regions of the anti-reflection layer are assigned different material properties and thicknesses to optimize performance for different wavelengths. The first sub-layer has a thickness of 50-150 nm for long wavelength optimization, while the third sub-layer has a thickness of 10-50 nm for short wavelength optimization, creating local quality variations to address different spectral requirements
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 significantly increases light sensitivity by optimizing light transmission rates for both short and long wavelengths, thereby improving the overall performance of image sensors.
Implementation Method 1
Conventional image sensors face challenges in maximizing light sensitivity due to reflection issues, which affect the efficiency of light transmission across different wavelengths
Implementation Method 2
the first layer has a first refractive index, the second layer has a second refractive index greater than the first refractive index, and the third layer has a third refractive index greater than the second refractive index
Data Source
AI summary
An anti-reflective image sensor and method of fabrication are provided, the sensor including a substrate; first color sensing pixels disposed in the substrate; second color sensing pixels disposed in the substrate; third color sensing pixels disposed in the substrate; a first layer disposed directly on the first, second and third color sensing pixels; a second layer disposed directly on the first layer overlying the first, second and third color sensing pixels; and a third layer disposed directly on portions of the second layer overlying at least one of the first or second color sensing pixels, wherein the first layer has a first refractive index, the second layer has a second refractive index greater than the first refractive index, and the third layer has a third refractive index greater than the second refractive index.