Image Sensor Pixel Isolation for Accurate Phase Detection
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Solution Overview
Problem
Existing imaging devices face challenges in maintaining image quality due to information loss during phase difference detection, which affects the accuracy of autofocus functions.
Innovation Solution
The imaging device incorporates a semiconductor substrate with a matrix arrangement of imaging elements, including pixels with a photoelectric conversion section, separation sections, and on-chip lenses, along with diffusion regions and element separation walls to enhance phase difference detection accuracy while minimizing information loss.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If phase difference detection pixels are provided separately on the light receiving surface, then phase difference detection function is achieved, but information loss occurs leading to deterioration of captured image
Solution Approach 1:
The imaging element is divided into multiple pixels within a predetermined unit region, with separation sections and element separation walls creating distinct regions. This segmentation allows different pixels to serve different functions (imaging vs. phase difference detection) while maintaining physical separation to prevent information loss.
Solution Approach 2:
Different regions within the imaging element are assigned different properties: some pixels are optimized for imaging while others are optimized for phase difference detection. The separation sections and diffusion regions create local electrical and optical property differences that enable each region to perform its specific function effectively.
2Productivity
If interpolation is performed on pixel information, then captured image can be generated, but image quality deteriorates due to information loss
Solution Approach 1:
The patent extracts the phase difference detection function from the imaging function by providing separate pixels for each purpose. This extraction eliminates the need for interpolation to compensate for missing information, as both imaging pixels and phase difference detection pixels coexist and contribute their respective information without one needing to infer from the other.
3Measurement precision
If separation sections and element separation walls are provided, then phase difference detection accuracy improves, but device complexity increases
Solution Approach 1:
The separation sections and element separation walls are integrated into the semiconductor substrate manufacturing process, combining multiple functions (electrical separation, optical separation, and structural support) into unified structures. This merging reduces overall device complexity compared to implementing separate systems for each function.
Solution Approach 2:
The element separation walls and separation sections serve multiple functions simultaneously: they provide electrical isolation between pixels, optical separation to prevent light crosstalk, and structural definition for the predetermined unit regions. This multi-functionality reduces the need for additional dedicated structures.
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 improves the accuracy of phase difference detection while preventing image deterioration, allowing for more precise autofocus and better image capture.
Implementation Method 1
a plurality of imaging elements that are arrayed in a matrix in a first direction and a second direction on the semiconductor substrate and perform photoelectric conversion on incident light
Implementation Method 2
a first diffusion region provided in the semiconductor substrate around the first element separation wall and the separation section and containing impurities of a second conductivity type having a conductivity type opposite to the first conductivity type
Data Source
AI summary
There is provided an imaging device including a semiconductor substrate and a plurality of imaging elements that are arrayed in a matrix in a first direction and a second direction on the semiconductor substrate and perform photoelectric conversion on incident light. Each of the plurality of imaging elements includes a plurality of pixels that are provided in a predetermined unit region of the semiconductor substrate to be adjacent to each other and contains impurities of a first conductivity type, a separation section that separates the plurality of pixels, two first element separation walls that are provided along two first side surfaces extending in the second direction of the predetermined unit region to pierce through at least a part of the semiconductor substrate, and a first diffusion region provided in the semiconductor substrate around the first element separation wall and the separation section and containing impurities of a second conductivity type.