Color Filter Grid Sidewalls for Image Sensor Sensitivity Balance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Image sensing devices face challenges in correcting sensitivity differences between color filters, particularly between blue and green, and red and green filters, which can affect image representation due to varying light sensitivity and fabrication errors.
Innovation Solution
The implementation of a grid structure with asymmetric sidewalls between color filters, where the sidewalls adjacent to green filters have a rounded profile and those adjacent to red and blue filters have a vertical profile, to reduce light incidence and correct sensitivity differences by inducing scattered reflection, thereby reducing the amount of light passing through green filters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If green color filters are used to capture light, then green light sensitivity is improved, but sensitivity differences between color filters increase due to higher light sensitivity
Solution Approach 1:
The patent applies local quality by creating different grid structures adjacent to different color filters. Specifically, green color filters are surrounded by grid structures with first widths, while red and blue color filters are surrounded by grid structures with second widths. This local differentiation compensates for the inherently higher light sensitivity of green filters by providing greater light blocking around them, thereby achieving uniform sensitivity across all color filters.
Solution Approach 2:
The patent employs asymmetry by intentionally designing the grid structure widths to be different based on the color filter type. The asymmetric design provides wider grid structures (greater light blocking) around green filters compared to red and blue filters, directly counteracting the asymmetric sensitivity characteristics of the color filters themselves and achieving balanced color response.
2Reliability
If grid structures are added between color filters, then light blocking and sensitivity correction are improved, but device complexity increases
Solution Approach 1:
The patent merges the grid structure formation with the existing color filter fabrication process. The grid structures are formed as part of the same semiconductor manufacturing sequence, integrating the sensitivity correction function into the standard pixel array fabrication without requiring separate processing steps, thereby minimizing the increase in device complexity.
Solution Approach 2:
The grid structures serve multiple functions: they provide electrical isolation between adjacent pixels, mechanical support for the color filter layer, and light blocking for sensitivity correction. This multi-functionality reduces the need for additional separate components, thereby limiting the increase in device complexity while achieving sensitivity correction.
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 design effectively reduces sensitivity differences between color filters, improving image representation by minimizing light flow through green filters and enhancing the implementation of high dynamic range (HDR) in image sensing devices.
Implementation Method 1
The grid structure may include a first grid structure arranged in contact with the first color filter and configured to have a first width, and a second grid structure arranged in contact with the second color filters and configured to have a second width smaller than the first width. The first grid structure has asymmetric sidewalls.
Data Source
AI summary
An image sensing device includes a semiconductor substrate, a plurality of photoelectric conversion elements supported by the semiconductor substrate, each photoelectric conversion elements configured to generate an electrical signal corresponding to incident light by performing a photoelectric conversion of the incident light, a plurality of color filters disposed over the semiconductor substrate to filter incident light to be received by the photoelectric conversion elements, each color filter configured to allow light having a specific color to pass therethrough, and a grid structure disposed between the color filters and structured to include asymmetric sidewalls that are shaped based on colors of adjacent color filters.