CMOS Pixel Separation Structure for Uniform Color Mixing
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Solution Overview
Problem
Conventional CMOS image sensors experience non-uniform color mixing due to light scattering between photodiodes, leading to inaccurate phase difference detection and reduced image quality.
Innovation Solution
A solid-state imaging element with a matrix arrangement of light-receiving pixels, each comprising a pair of photoelectric conversion units, a first separation region surrounding them, a second separation region between them, and a third separation region extending from the light incident surface to the middle of the semiconductor layer, which helps in scattering light differently and reducing color mixing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If light is caused to be incident on a pair of photodiodes from the same on-chip lens to detect phase difference, then phase difference detection capability is improved, but non-uniform color mixing occurs due to light scattering in the separation region
Solution Approach 1:
The separation region is divided into a first separation region extending from the light incident surface to a first depth, and a second separation region extending from the light incident surface to a second depth different from the first depth. This segmentation creates multiple zones with different light scattering characteristics, allowing differentiated control of light paths to reduce non-uniform color mixing while maintaining phase difference detection capability
Solution Approach 2:
Different regions of the separation structure are given different properties by varying the depth of the separation regions. The first separation region and second separation region have different depths, creating local variations in light scattering intensity. This allows specific areas to handle light differently, reducing non-uniform color mixing while preserving the overall phase difference detection function
2Manufacturing precision
If a separation region is disposed between photodiodes to reduce color mixing, then color mixing is reduced, but light scattering occurs leading to non-uniform color mixing
Solution Approach 1:
The separation region is segmented into multiple depth zones (first separation region and second separation region with different depths). This segmentation allows light to be scattered differently at different depths, converting the harmful uniform scattering effect into a controlled multi-zone scattering pattern that reduces non-uniform color mixing
Solution Approach 2:
The depth parameter of the separation regions is varied to change light scattering characteristics. By setting the first depth and second depth to different values, the light scattering intensity and pattern are modified across different zones, transforming the harmful scattering effect into a beneficial controlled scattering pattern
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
The solution improves the non-uniformity of color mixing and enhances the separation ratio between photodiodes, resulting in better phase difference detection and image quality.
Implementation Method 1
the incident light may be largely scattered in a separation region disposed between the pair of photodiodes
Data Source
AI summary
A solid-state imaging element (1) according to the present disclosure includes a plurality of light-receiving pixels (11) arranged in a matrix inside a semiconductor layer (20). The light-receiving pixel (11) includes a pair of photoelectric conversion units, a first separation region (24), a second separation region (25), and a third separation region (26). The pair of photoelectric conversion units are disposed adjacent to each other. The first separation region (24) is disposed so as to surround the pair of photoelectric conversion units and is disposed so as to penetrate the semiconductor layer (20). The second separation region (25) is disposed between the pair of photoelectric conversion units and is disposed so as to penetrate the semiconductor layer (20). The third separation region (26) is disposed in a region surrounded by the first separation region (24) and is disposed from a light incident surface (20a) of the semiconductor layer (20) to a middle of the semiconductor layer (20).