Image Sensor Grid Structure Refractive Index Optimization
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Solution Overview
Problem
Existing image sensors, particularly those using backside illumination technology, face challenges in achieving high-quality image signals due to optical cross talk and light leakage, which affect signal strength and overall image quality.
Innovation Solution
The implementation of a grid structure with specific refractive index layers and partition walls surrounding filter units in the image sensor, where the refractive index of the first partition wall is less than that of the second, minimizes optical cross talk and guides more light to the filter units, enhancing signal strength and image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a grid structure with partition walls is introduced to reduce optical cross talk, then image quality is improved, but device complexity increases
Solution Approach 1:
The grid structure divides the sensor surface into discrete regions using partition walls, isolating adjacent filter units to prevent optical cross talk. Each partition wall creates a physical barrier that segments the light paths, ensuring that light from one filter unit does not interfere with adjacent units, thereby improving image quality through spatial segmentation.
Solution Approach 2:
The partition walls are strategically positioned only at critical interfaces between filter units where optical cross talk occurs, rather than uniformly across the entire sensor. This localized approach provides the necessary isolation where needed while minimizing the overall structural complexity and material usage.
2Reliability
If the refractive index of partition walls is reduced to guide light to filter units, then signal strength is improved, but manufacturing precision requirements increase
Solution Approach 1:
The refractive index of the partition walls is specifically optimized to be lower than that of the filter units, creating a refractive index gradient that naturally guides light toward the filter units. This parameter change in the material properties enables passive light guidance without requiring additional active components, improving signal strength while maintaining manufacturability through standard material selection.
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 improves the signal-to-noise ratio and quantum efficiency, reducing optical cross talk by up to 5% and increasing signal strength, resulting in enhanced image quality and sensitivity.
Implementation Method 1
The refractive index of the first partition wall is less than the refractive index of the second partition wall... a portion of the light entering the grid structure is guided to the filter units
Data Source
AI summary
An image sensor includes a sensing layer, a number of filter units, and a grid structure. The filter units are disposed on the sensing layer. The grid structure is disposed on the sensing layer and surrounding each of the filter units. The grid structure includes a first partition wall disposed on the sensing layer and located between two adjacent filter units, and a second partition wall disposed on the first partition wall located between the two adjacent filter units. The refractive index of the first partition wall is less than the refractive index of the second partition wall.