Asymmetric Pixel Layout for Image Sensor Crosstalk Reduction
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Solution Overview
Problem
In image sensing apparatuses, crosstalk occurs due to varying incident angles of light, reducing image quality, and existing technologies have not sufficiently addressed the suppression of crosstalk caused by electric charge generated by photoelectric conversion, especially in layouts with translational symmetry.
Innovation Solution
The image sensing system employs a quadrilateral pixel layout with specific conductivity-type semiconductor regions for photoelectric conversion and isolation, where the distances between accumulation and isolation regions are optimized to reduce crosstalk, and the layout relationships between pixels are asymmetrical to minimize crosstalk differences across the image sensing region.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If pixels are arranged with translational symmetry in the entire image sensing region, then the layout is regular and easy to manufacture, but the amount of crosstalk varies between directions of incident light leading to reduced image quality
Solution Approach 1:
The patent applies asymmetry by making the pixel layout asymmetric with respect to the intermediate line. Specifically, the arrangement of pixels and their associated structures (such as microlenses and color filters) differs between the first region and the second region divided by the intermediate line. This asymmetric configuration ensures that crosstalk characteristics become uniform across different incident light directions, resolving the contradiction between manufacturing ease and crosstalk uniformity.
2Object-affected harmful factors
If isolation regions are placed closer to the photoelectric conversion portion, then crosstalk suppression is improved, but the distance constraints become more difficult to satisfy uniformly across all pixels
Solution Approach 1:
The patent applies local quality by allowing different pixels to have different isolation region configurations based on their specific locations and incident light angles. Instead of enforcing a uniform isolation region distance for all pixels, the patent optimizes the isolation region placement locally for each pixel or region, ensuring that crosstalk suppression requirements are met while simplifying overall layout constraints.
3Device complexity
If the image sensing region uses a non-telecentric optical system, then the structure is simpler, but incident angles of light vary across the pixel array causing directional crosstalk differences
Solution Approach 1:
The patent compensates for the asymmetric incident light angles caused by the non-telecentric optical system by implementing an asymmetric pixel layout. The pixel arrangement and associated structures are deliberately made asymmetric with respect to the intermediate line to counterbalance the angular variations, ensuring uniform crosstalk characteristics across the entire image sensing region while maintaining optical system simplicity.
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 suppresses crosstalk and reduces the variation in crosstalk across the image sensing region, improving image quality by optimizing the distances and positions of semiconductor regions within the pixels.
Implementation Method 1
a photoelectric conversion portion that converts incident light into signal electric charge
Data Source
AI summary
A distance between a first accumulation region of a first pixel and a first isolation region is larger than a distance between the first accumulation region and a second isolation region, and a distance between a second accumulation region of a second pixel and a third isolation region is larger than a distance between the second accumulation region and a fourth isolation region.