Image Sensor Pixel Array Grid Layout for Crosstalk Reduction
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Solution Overview
Problem
Image sensing devices face a deterioration in signal-to-noise ratio (SNR) due to crosstalk components, particularly spectral crosstalk, spatial crosstalk, and electrical crosstalk, which are exacerbated by limitations in color filters and air grid structures, especially at long wavelengths.
Innovation Solution
The implementation of a multi-pixel array structure with a metal grid along the edge of the blue pixel array and an air grid in the inner areas of all pixel arrays, specifically using a barrier metal layer, a metal layer, and a capping layer for the metal grid, and a barrier metal layer, a supporting layer, an air layer, and a capping layer for the air grid, to minimize crosstalk between blue, green, and red color filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If color filters are used to separate wavelengths, then spectral crosstalk is reduced, but manufacturing complexity and cost increase
Solution Approach 1:
The patent extracts the spectral crosstalk problem from the color filter layer and addresses it separately using the metal grid structure. Instead of relying solely on color filters to handle all crosstalk, the metal grid specifically extracts and reflects long wavelength light, allowing color filters to focus on other wavelength separations and reducing overall manufacturing complexity.
Solution Approach 2:
The patent replaces the reliance on complex color filter systems with a simpler metal grid reflective structure for handling long wavelength crosstalk. This substitution uses optical reflection physics rather than complex filter material science, simplifying the manufacturing process while effectively reducing spectral crosstalk.
2Productivity
If pixel arrays are placed closer together to increase density, then productivity is improved, but crosstalk between adjacent arrays increases
Solution Approach 1:
The patent addresses the crosstalk problem by adding a new dimensional approach - using reflective metal grids that operate in the optical path dimension rather than just the spatial separation dimension. This allows pixel arrays to be placed closer together while the metal grid reflects long wavelength light before it can cause crosstalk, effectively adding a new dimension to the crosstalk mitigation strategy.
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 reduces crosstalk components, thereby enhancing the signal-to-noise ratio (SNR) by minimizing green crosstalk at blue light wavelengths and blue crosstalk at green light wavelengths, leading to improved image sensing performance.
Implementation Method 1
a metal grid arranged along an edge of the first pixel array such that the metal grid is disposed between the plurality of color filters in the first pixel array and a plurality of color filters in another pixel array adjacent to the first pixel array
Implementation Method 2
an air grid formed between the blue color filters
Data Source
AI summary
Disclosed are image sensing devices. In some implementations, an image sensing device may include a plurality of pixel arrays including first, second, and third pixel arrays, wherein each pixel array comprises a plurality of color filter, and the first pixel array includes a metal grid arranged along an edge of the first pixel array such that the metal grid is disposed between the plurality of color filters in the first pixel array and a plurality of color filters in another pixel array adjacent to the first pixel array, wherein the color filters in the first pixel array are blue color filters.