Imaging Device Separation Region Control Electrode
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Solution Overview
Problem
Conventional imaging devices using the pupil division phase difference method for focus detection face issues such as reduced light efficiency and accuracy due to electrode placement on the light incident side, leading to variations in pupil division performance among devices and reduced focus detection accuracy caused by optical crosstalk and variations in film thickness.
Innovation Solution
An imaging device with a light receiving unit on a semiconductor substrate featuring two photoelectric conversion elements and a separation region, where a separation region control electrode on the second surface side adjusts the potential barrier between the elements, minimizing crosstalk and optimizing pupil division performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an electrode is provided on the light incident side of the photoelectric conversion element to control the potential barrier, then the pupil division performance can be adjusted, but the light receiving efficiency is reduced due to scattering and absorption of incident light
Solution Approach 1:
The electrode is moved from the light incident side (first surface) to the opposite side (second surface) of the photoelectric conversion element. This inversion of the electrode position eliminates the direct interference with incident light while maintaining the ability to control the potential barrier in the separation region through voltage application.
Solution Approach 2:
The control electrode is positioned in a different spatial dimension (on the second surface rather than the first surface), allowing it to exert electrical control over the separation region without occupying the optical path. This dimensional separation resolves the conflict between electrical control functionality and optical transmission efficiency.
2Ease of manufacture
If the film thickness of the photoelectric conversion element varies during production, then manufacturing cost is reduced, but the amount of optical crosstalk between divided photoelectric conversion elements varies, leading to variations in pupil division performance
Solution Approach 1:
The invention introduces a controllable electrical parameter (voltage applied to the separation region control electrode) that can compensate for variations in physical parameters (film thickness). By adjusting the voltage, the potential barrier height can be optimized to maintain consistent pupil division performance despite manufacturing variations in photoelectric conversion element thickness.
Solution Approach 2:
The system enables feedback-based correction of manufacturing variations. The separation region control electrode allows for post-manufacturing adjustment and optimization of the potential barrier, providing a means to compensate for and correct variations in film thickness that occur during production, thereby ensuring consistent performance across manufactured devices.
3Measurement precision
If conventional voltage control of the divided portion is used to correct charge crosstalk, then some crosstalk adjustment is achieved, but light receiving efficiency and accuracy are still significantly reduced
Solution Approach 1:
The light-blocking electrode is extracted and removed from the light incident side, eliminating the source of light scattering and absorption. The electrode function is separated from the optical path, allowing incident light to reach the photoelectric conversion elements without interference while electrical control of the separation region is maintained through the repositioned electrode on the second surface.
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 enhances the accuracy and consistency of focus detection by controlling the charge crosstalk rate and pupil division performance, reducing variations among devices and improving the overall focus detection precision.
Implementation Method 1
a separation region control electrode disposed on the second surface side of the separation region and configured to control a potential of the separation region
Implementation Method 2
each of the pixels has at least two photoelectric conversion elements
Data Source
AI summary
An imaging device suitable for focus detection of a pupil division phase difference method includes: a light receiving unit provided on a first surface side of a semiconductor substrate and having a plurality of pixels arranged in a two-dimensional form; and a read-out circuit provided on a second surface side of the semiconductor substrate opposite to the first surface side and configured to read signals from the pixels. Each of pixels has at least two photoelectric conversion elements and a separation region which is a region between the two photoelectric conversion elements and a separation region control electrode arranged on the second surface side of the separation region and configured to control a potential of the separation region.