Image Sensor Crosstalk Reduction via Refractive Index Gradients
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Solution Overview
Problem
Current image sensing devices face challenges in reducing crosstalk between neighboring imaging pixels, which affects the accuracy and quality of optical image conversion into electrical signals.
Innovation Solution
The image sensing device incorporates a substrate with photoelectric conversion elements, grid structures with air layers and color filters of higher refractive index, and a lens layer with an even higher refractive index to minimize crosstalk by optimizing the structural characteristics of the light transmission layer, ensuring that light is focused on intended pixels while preventing it from reaching adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light transmission layers are used to guide light to photoelectric conversion elements, then light collection efficiency is improved, but crosstalk between neighboring pixels increases
Solution Approach 1:
The patent applies local quality by creating spatial variations in refractive index within the light transmission layer. Different regions (neighboring pixel regions versus target pixel regions) have different optical properties - specifically, the first refractive index in neighboring regions and a second refractive index in target regions, allowing light to be locally directed to the correct photoelectric conversion elements while preventing crosstalk
Solution Approach 2:
The patent changes the refractive index parameter of the light transmission layer material to resolve the contradiction. By using a material with a refractive index that satisfies a specific relationship with the substrate layer's refractive index, the patent achieves both improved light collection efficiency and reduced crosstalk between neighboring pixels
2Object-affected harmful factors
If the refractive index of the light transmission layer is increased to reduce crosstalk, then crosstalk is reduced, but light collection efficiency decreases
Solution Approach 1:
The patent optimizes the refractive index parameter by establishing a specific mathematical relationship between the refractive index of the light transmission layer and the substrate layer. This parameter optimization allows the system to achieve both reduced crosstalk and maintained light collection efficiency, resolving the trade-off between these two competing requirements
Solution Approach 2:
The patent implements local quality by differentiating refractive index values between neighboring pixel regions and target pixel regions within the light transmission layer, enabling selective light guidance that reduces crosstalk while preserving light collection efficiency for the intended photoelectric conversion elements
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 effectively reduces crosstalk between neighboring pixels, enhancing the accuracy and quality of image conversion by ensuring that light is directed to the intended photoelectric conversion elements and preventing it from reaching undesired neighboring pixels.
Implementation Method 1
a lens layer disposed over the grid structures and the color filters such that part of the lens layer fills top portions of the spaces between the grid structures, the lens layer having a higher refractive index than the color filters
Implementation Method 2
a substrate layer in which an array of photoelectric conversion elements is formed to convert incident light into electric signals
Data Source
AI summary
An image sensing device includes a substrate layer in which an array of photoelectric conversion elements is formed, grid structures disposed over the substrate layer to divide space above the substrate into different sensing regions, each grid structure including an air layer, color filters formed to fill bottom portions of spaces between the grid structures, the color filters having a higher refractive index than the air layer, and a lens layer disposed over the grid structures and the color filters such that part of the lens layer fills top portions of the spaces between the grid structures, the lens layer having a higher refractive index than of the color filters.