Phase Difference Pixel Layout for More Accurate Imaging Sensors
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The detection accuracy of phase difference in imaging elements decreases due to the arrangement of structures not contributing to photoelectric conversion, such as through electrodes, between pixels when using a common on-chip lens for pupil split, leading to increased errors in phase difference detection.
Innovation Solution
An imaging element configuration where individual on-chip lenses are used for each pixel, and the charge transfer units of phase difference pixels are arranged in a region between the common on-chip lens and individual on-chip lens, excluding the region where the common on-chip lens is arranged, to minimize the influence of charge transfer units on light collection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If a common on-chip lens is used for pupil split in phase difference pixels, then light collection efficiency is improved, but detection accuracy of phase difference decreases due to structures not contributing to photoelectric conversion
Solution Approach 1:
The patent resolves the contradiction by transitioning from a two-dimensional planar arrangement to a three-dimensional stacked architecture. The charge transfer unit is moved from the same layer as the photoelectric conversion unit to a different layer (stacked position), allowing it to be positioned in a region that does not overlap with the common on-chip lens. This vertical separation enables the lens to collect light effectively while the charge transfer unit processes charges without interfering with the optical path, thus maintaining both light collection efficiency and phase difference detection accuracy.
2Ease of operation
If through electrodes are arranged between pixels for charge transfer, then charge transfer function is achieved, but output difference of image signals increases leading to detection errors
Solution Approach 1:
The patent applies the stacking principle to reposition the charge transfer unit in a different layer from the photoelectric conversion unit. This vertical separation allows the charge transfer unit to be strategically placed in a region that does not interfere with the common on-chip lens's light collection area. By moving the charge transfer unit to a stacked position, the patent eliminates the need for through electrodes that would otherwise obstruct the optical path and cause signal output differences, thereby maintaining image signal consistency while preserving charge transfer functionality.
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 reduces the output difference of image signals between phase difference pixels, thereby decreasing errors in phase difference detection and improving detection accuracy.
Implementation Method 1
an on-chip lens arranged for each pixel and configured to individually collect the incident light; a common on-chip lens arranged in common for the plurality of phase difference pixels and configured to collect the incident light in common
Implementation Method 2
a photoelectric conversion unit configured to perform photoelectric conversion in accordance with incident light
Data Source
Figure 1
Figure 2
Figure 3
AI summary
An error is reduced in phase difference detection of an imaging element including a phase difference pixel configured by arranging an on-chip lens in common for a pair of pixels. The imaging element includes a pixel, an individual on-chip lens, a plurality of phase difference pixels, a common on-chip lens, and a pixel circuit. The pixel includes a photoelectric conversion unit configured to perform photoelectric conversion in accordance with incident light, and a charge transfer unit configured to transfer a charge generated by the photoelectric conversion. The individual on-chip lens is arranged for each pixel and individually collects incident light. The phase difference pixels each include the photoelectric conversion unit and the charge transfer unit, and are arranged adjacent to each other to detect a phase difference. The common on-chip lens is arranged in common for the plurality of phase difference pixels and collects incident light in common. The pixel circuit is formed in a semiconductor substrate and generates an image signal on the basis of a transferred charge. The charge transfer units of the plurality of phase difference pixels are arranged in a region between the common on-chip lens and the individual on-chip lens.