Tilted Grid Structure for Image Sensor Light Collection
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Solution Overview
Problem
Image sensors face challenges in maintaining image quality due to shading variation, which increases as pixel size decreases and chief ray angles increase, leading to differences in light incidence across the pixel array, affecting overall image quality.
Innovation Solution
The implementation of a grid structure within the image sensor that is tilted according to the chief ray angles of unit pixels in the pixel array, with a multilayer structure and metal material composition, to improve light collection efficiency and prevent crosstalk between adjacent pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If pixel size is decreased to increase pixel density, then image sensor resolution is improved, but shading variation increases and light collection efficiency deteriorates
Solution Approach 1:
The patent applies local quality by varying the grid structure configuration across different regions of the pixel array. Specifically, pixels at different locations (corner, edge, center) have different grid patterns and orientations tailored to their specific chief ray angles, optimizing light collection for each local region while maintaining high resolution
Solution Approach 2:
The patent introduces dynamic adaptation by making the grid structure characteristics (orientation, pattern, density) variable according to the chief ray angle at each pixel location. This dynamic configuration allows the system to adapt to changing light incidence angles across the sensor array, compensating for shading effects in smaller pixels
2Adaptability or versatility
If chief ray angle increases at pixel edges, then wider field of view is achieved, but light incidence variation and shading increase
Solution Approach 1:
The patent implements local quality by assigning different grid orientations and patterns to pixels based on their location in the array. Corner pixels have grids oriented for 45-degree chief ray angles, edge pixels for 30-degree angles, and center pixels for vertical incidence, thereby optimizing light collection for each local field of view region
Solution Approach 2:
The patent applies preliminary action by pre-configuring the grid structure at each pixel location according to the expected chief ray angle before light enters the sensor. This predetermined optimization ensures that light collection is maximized for the specific field of view angle at each pixel position
3Measurement precision
If grid structure is added to improve light collection, then quantum efficiency increases, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent applies segmentation by dividing the pixel array into distinct regions (corner, edge, center) with different grid configurations. This segmentation allows complex grid patterns to be applied only where needed, rather than uniformly across the entire array, reducing overall manufacturing complexity while maintaining high quantum efficiency
Solution Approach 2:
The patent uses composite materials by combining the grid structure with the pixel electrode and other sensor layers. The grid is formed as part of the electrode structure using conductive materials, integrating multiple functions into a composite component that reduces the number of separate manufacturing steps
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 solution enhances shading variation, increases quantum efficiency, and reduces light loss by optimizing light incidence across the pixel array, thereby improving image quality, especially at the edges of the sensor.
Implementation Method 1
the grid structure is tilted for respective chief ray angles of the unit pixels according to location in the pixel array
Implementation Method 2
refractive indexes of the multiple layers of the light transmission member may be the same. Each of the multiple layers of the light transmission member may include an insulating material, and wherein the multiple layers of the light transmission member having different refractive indexes are stacked such that each of the multiple layers has a larger refractive index toward the photoelectric conversion element
Implementation Method 3
a substrate including photoelectric conversion elements for a plurality of unit pixels
Data Source
AI summary
An image sensor includes a substrate including photoelectric conversion elements for a plurality of unit pixels, which are two-dimensionally arranged in a pixel array; a light transmission member on the substrate; a grid structure in the light transmission member and having multiple layers; and a light collection member on the light transmission member, wherein the grid structure is tilted for respective chief ray angles of the plurality of unit pixels according to locations of the plurality of unit pixels in the pixel array.