Image Sensor Fence Structure Width Optimization
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Solution Overview
Problem
As pixel size decreases in image sensors, sensitivity loss and color mixing due to crosstalk between adjacent pixels become significant issues, particularly in low illuminance conditions, and maintaining optical characteristics becomes challenging with the reduced volume ratio of isolation structures.
Innovation Solution
An image sensor design featuring a color filter array with a fence structure having varying widths between adjacent filters, and an isolation structure with varying widths between light sensing cells, both tailored to specific filter types, to minimize crosstalk and maintain optical efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is reduced to increase pixel density, then high resolution is achieved, but sensitivity decreases and color mixing increases due to crosstalk
Solution Approach 1:
The patent applies local quality by making the isolation structure width variable rather than uniform. Specifically, the isolation structure has a first width between red and green filters, and a second width between green and blue filters, with the ratio between first and second widths being 1:1.2 to 1:1.5. This localized differentiation optimizes crosstalk reduction for each color combination while maintaining overall sensitivity.
Solution Approach 2:
The patent changes the geometric parameter of the isolation structure width to resolve the contradiction. By adjusting the width ratio between different color filter pairs (1:1.2 to 1:1.5), the patent optimizes the balance between reducing crosstalk (improving reliability) and maintaining pixel density (preserving resolution).
2Measurement precision
If pixel size is reduced to increase pixel density, then high resolution is achieved, but crosstalk between adjacent cells increases causing color mixing
Solution Approach 1:
The patent addresses crosstalk by implementing local quality through differentiated isolation structure widths. The first width between red-green filters and the second width between green-blue filters are specifically optimized with a ratio of 1:1.2 to 1:1.5, providing targeted crosstalk reduction for each color interface while maintaining high pixel density.
Solution Approach 2:
The isolation structure serves as an intermediary element between adjacent color filters. By positioning this structure with optimized width ratios (1:1.2 to 1:1.5) at different color interfaces, the patent effectively mediates and reduces crosstalk between adjacent pixels without compromising resolution.
3Measurement precision
If isolation structure volume is reduced due to miniaturization, then pixel density increases, but optical characteristics deteriorate
Solution Approach 1:
The patent changes the isolation structure width parameters to maintain optical characteristics despite miniaturization. By setting the width ratio between first and second isolation structures to 1:1.2 to 1:1.5, the patent optimizes light isolation effectiveness while accommodating reduced overall dimensions for higher pixel density.
Solution Approach 2:
The patent applies local quality by differentiating isolation structure widths at different color filter interfaces. This localized optimization ensures that optical characteristics are maintained through targeted isolation where needed most, rather than uniform reduction across all structures.
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 effectively reduces crosstalk and sensitivity loss, enhancing image sensor performance in low illuminance conditions while maintaining optical characteristics by adjusting the fence and isolation structure widths according to the specific characteristics of adjacent filters and pixels.
Implementation Method 1
The fence structure may include a material having a first refractive index lower than a second refractive index of each of the plurality of filters
Data Source
AI summary
An image sensor includes a sensor substrate including a plurality of light sensing cells configured to sense light, and a color filter array provided on the sensor substrate. The color filter includes a plurality of filters provided to respectively face the plurality of light sensing cells to filter light of different wavelengths and a fence structure configured to separate the plurality of filters from each other. A width of the fence structure may have a plurality of different values according to types of two filters provided adjacent to each other with the width interposed therebetween. Crosstalk between adjacent cells may be reduced by the image sensor.