Imaging Pixel Structure Using Low-Refraction Regions Against Color Mixing
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Solution Overview
Problem
In imaging devices, such as digital and video cameras, color mixing between pixels is a significant issue that affects image quality, and existing technologies have not adequately addressed this problem.
Innovation Solution
The implementation of an imaging device with a semiconductor substrate, a photoelectric conversion unit, a color filter, an intermediate layer, and a low refraction region between the color filter and the intermediate layer, where the low refraction region has a refractive index lower than the color filter, to reflect light and reduce color mixing between pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light incident from the back surface is allowed to reach photoelectric conversion units, then photoelectric conversion efficiency is improved, but color mixing between adjacent pixels occurs due to light leakage
Solution Approach 1:
The patent divides the semiconductor substrate into isolated pixel regions using pixel separation walls that extend from the back surface to the front surface. This segmentation physically partitions the substrate into discrete pixel units, preventing light from leaking between adjacent pixels while maintaining efficient light reception at each pixel location.
Solution Approach 2:
The patent applies different refractive indices to different regions: the pixel separation walls use materials with refractive indices of 1.4-2.0, while low refraction regions with refractive indices of 1.0-1.3 are formed in specific areas. This local variation in optical properties enables precise control of light paths, reflecting stray light away from adjacent pixels while allowing direct light to reach photoelectric conversion units.
2Object-generated harmful factors
If pixel separation structures are added to suppress color mixing, then color mixing is reduced, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent combines multiple functions into the pixel separation walls: they provide both electrical isolation between pixels and optical isolation through refractive index differences. Additionally, the low refraction regions are integrated into the existing pixel separation structure rather than being separate components, reducing overall device complexity while achieving effective color mixing suppression.
Solution Approach 2:
The patent introduces low refraction regions as intermediary structures between the pixel separation walls and the color filters. These intermediary regions with refractive indices of 1.0-1.3 act as optical mediators that reflect stray light away from adjacent pixels, providing an additional mechanism for color mixing suppression without requiring complete redesign of the pixel separation structure.
3Object-generated harmful factors
If pixel separation walls are formed to isolate pixels, then color mixing is suppressed, but manufacturing precision requirements increase
Solution Approach 1:
The patent employs composite material structures where pixel separation walls are formed using materials with specific refractive indices (1.4-2.0) that differ from both the semiconductor substrate and the low refraction regions (1.0-1.3). This composite approach creates multiple refractive index interfaces that work together to reflect and block stray light, providing robust color mixing suppression even with variations in manufacturing precision.
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 color mixing between pixels, enhancing image quality by improving light incident efficiency and reducing leakage of light between adjacent pixels.
Implementation Method 1
light traveling to an adjacent pixel can be reflected at the interface between the color filter and the low refraction region and the interface between the intermediate layer and the low refraction region
Data Source
AI summary
Provided is an imaging device capable of further suppressing color mixing between pixels. The imaging device includes: a semiconductor substrate provided with a photoelectric conversion unit for each of pixels two-dimensionally arranged; a color filter provided for each of the pixels on the semiconductor substrate; an intermediate layer provided between the semiconductor substrate and the color filter; and a low refraction region provided between the pixels by separating at least the color filter and the intermediate layer for each of the pixels, the low refraction region having a refractive index lower than a refractive index of the color filter.