Image Sensor Fence Pattern for Pixel Crosstalk Isolation
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Solution Overview
Problem
Current image sensors face challenges in preventing crosstalk between pixel regions, which affects image quality due to the lack of effective light management and separation between color filters.
Innovation Solution
The implementation of a fence pattern with a first fence pattern having a narrower bottom surface and a wider top surface, along with a second fence pattern, between adjacent color filters, enhances light incidence and reduces crosstalk by physically and optically separating the color filters, while a protective layer covers the fence pattern to maintain structural stability and light absorption.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional fence pattern with uniform width is used between color filters, then the structure is simple and easy to manufacture, but crosstalk between pixel regions occurs and light incidence is reduced
Solution Approach 1:
The patent applies asymmetry by designing the fence pattern with a trapezoidal cross-section where the top width is greater than the bottom width. This asymmetric geometry provides enhanced crosstalk prevention at the top where color filters are located, while maintaining manufacturing feasibility through a single patterning process that forms the tapered structure naturally.
Solution Approach 2:
The patent transitions from a two-dimensional uniform fence pattern to a three-dimensional tapered structure by varying the width in the vertical dimension. This dimensional change allows the fence pattern to provide both mechanical support and optical isolation functions more effectively, reducing crosstalk while accommodating the color filters above.
2Reliability
If a wider fence pattern is used to prevent crosstalk, then crosstalk is reduced, but the amount of incident light on pixel regions decreases
Solution Approach 1:
The patent applies local quality by varying the fence pattern width at different heights - narrower at the bottom to minimize light blockage and wider at the top to maximize crosstalk prevention. This localized optimization ensures that each section of the fence pattern performs its function most effectively without compromising overall system performance.
3Reliability
If the fence pattern width varies significantly, then crosstalk is minimized, but manufacturing precision requirements increase
Solution Approach 1:
The patent uses a moderate width variation ratio (top width 1.1-1.5 times the bottom width) that provides sufficient crosstalk prevention without requiring extreme manufacturing precision. This partial action approach achieves adequate performance improvement with realistic fabrication tolerances, avoiding the need for overly complex multi-step patterning processes.
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 increases the amount of incident light on each pixel region, improves image quality by minimizing crosstalk, and enhances the structural stability of the image sensor.
Implementation Method 1
Each of the pixels includes a photodiode. The photodiode serves to convert incident light into electrical signals.
Data Source
AI summary
An image sensor includes: a substrate having a first surface and a second surface that are opposite to each other; a plurality of color filters on the substrate; a fence pattern between adjacent color filters of the plurality of color filters; and a protective layer between the substrate and the plurality of color filters, wherein the protective layer covers the fence pattern. The fence pattern includes: a first fence pattern having a first bottom surface and a first top surface that are opposite to each other; and a second fence pattern on the first top surface of the first fence pattern. A width at the first bottom surface of the first fence pattern is less than a width of the second fence pattern, and the protective layer covers a sidewall of the first fence pattern.