Image Sensor Phase Detection Pixel with Off-Center Electrode Slit
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Solution Overview
Problem
Conventional image pickup devices with organic photoelectric conversion films and phase difference detection pixels suffer from light leakage through slits in the lower electrode, leading to noise and color mixture, which affects image quality and autofocus precision.
Innovation Solution
The image pickup device incorporates a lower electrode section that is unevenly divided to avoid the center of the incident light, with a transparent upper electrode and a reflective lower electrode, and optionally includes a light-shielding section to prevent light leakage, allowing for precise phase difference detection and improved image signal generation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the lower electrode is provided with a slit at the optical center, then light can pass through to reach the PD for phase difference detection, but noise and color mixture are generated due to light leakage
Solution Approach 1:
The lower electrode is divided into multiple segments (first lower electrode section and second lower electrode section) with a slit positioned away from the optical center. This segmentation allows light to pass through for phase difference detection while preventing excessive light leakage that causes noise and color mixture.
Solution Approach 2:
The slit is positioned at a specific location away from the optical center rather than uniformly distributed. This local positioning optimizes the balance between allowing sufficient light for phase difference detection and minimizing light leakage-induced noise and color mixture in different regions of the pixel.
2Device complexity
If the PD is omitted to simplify the structure, then device complexity is reduced, but light leaks from the slit to the lower layer side generating noise
Solution Approach 1:
The lower electrode is segmented into multiple sections with a strategically positioned slit, enabling the structure to function without requiring a separate PD layer while still controlling light leakage to minimize noise generation.
Solution Approach 2:
The slit that could potentially cause light leakage and noise is strategically positioned away from the optical center, converting what could be a harmful feature into a beneficial design that enables simplified structure while controlling noise through optimized light path management.
3Ease of manufacture
If the lower electrode is uniformly divided, then manufacturing is simplified, but the center of incident light is not avoided leading to noise generation
Solution Approach 1:
The lower electrode is divided asymmetrically with the slit positioned away from the optical center rather than uniformly. This asymmetric design prevents the center of incident light from aligning with the slit, reducing light leakage and noise while remaining manufacturable.
Solution Approach 2:
The electrode division is optimized locally by positioning the slit away from the optical center, creating different properties in different regions: the central region maintains light concentration for efficient photoelectric conversion while peripheral regions have the slit for phase difference detection without excessive leakage.
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 inhibits noise and color mixture, enhancing the sensitivity and separation ratio of pixel outputs, enabling high-precision image plane phase difference autofocus and improved image quality.
Implementation Method 1
a first photoelectric conversion section that generates an electric charge in response to incident light
Implementation Method 2
the upper electrode section including a member that transmits light
Implementation Method 3
the lower electrode section including a member that reflects light
Data Source
AI summary
The present disclosure relates to an image pickup device that enables inhibition of occurrence of color mixture or noise, and an electronic apparatus. The image pickup device of the present disclosure includes an image plane phase difference detection pixel for obtaining a phase difference signal for image plane phase difference AF. The image plane phase difference detection pixel includes: a first photoelectric conversion section that generates an electric charge in response to incident light; an upper electrode section that is one of electrodes disposed facing each other across the first photoelectric conversion section, the upper electrode section being formed on an incident side of the incident light on the first photoelectric conversion section; and a lower electrode section that is another of the electrodes disposed facing each other across the first photoelectric conversion section, the lower electrode section being formed on an opposite side of the incident side of the incident light on the first photoelectric conversion section, the lower electrode section being multiple-divided at a position that avoids a center of the incident light. The present disclosure is applicable to image sensors.