Pixel Electrode Overlap in Stacked Imaging Device Light Leakage
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Solution Overview
Problem
Imaging devices using CMOS technology face issues with light leakage into charge detection circuits, leading to false signals and degraded image quality, particularly in stacked-type imaging devices where light can enter the charge accumulation region during exposure, causing parasitic light sensitivity and phenomena like rolling shutter distortion and flash band effects.
Innovation Solution
The imaging device incorporates a photoelectric converter with a photoelectric conversion layer and pixel electrodes arranged in a specific configuration, where the distance between adjacent pixel electrodes is minimized to prevent light leakage, using a counter electrode and insulating films to block light from reaching the charge detection circuit, thereby reducing parasitic light sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a light-shielding film is formed on the charge accumulator to block light leakage, then light shielding performance is improved, but device complexity and manufacturing complexity increase
Solution Approach 1:
The patent transitions from a planar light-shielding film to a three-dimensional stacked structure where the photoelectric conversion layer is positioned above the charge detection circuit. This vertical stacking in the third dimension eliminates the need for additional light-shielding films, as the photoelectric conversion layer itself blocks light from reaching the charge detection circuit while maintaining a compact form factor.
Solution Approach 2:
The patent integrates the light-shielding function into the photoelectric conversion layer structure itself, merging the photoelectric conversion function and light shielding function into a single integrated component. This eliminates the need for separate light-shielding films and reduces overall device complexity.
2Object-affected harmful factors
If the distance between pixel electrode and first electrode is minimized in plan view, then light leakage is reduced, but manufacturing precision requirements increase
Solution Approach 1:
Instead of reducing the planar distance between electrodes, the patent uses vertical stacking to achieve light isolation. The photoelectric conversion layer is positioned in the third dimension above the charge detection circuit, creating effective light blocking without requiring tight lateral spacing between electrodes, thus reducing manufacturing precision requirements.
Solution Approach 2:
The patent introduces an insulating film as an intermediary layer between the pixel electrode and the first electrode. This insulating film provides both electrical isolation and additional light blocking, allowing for larger spacing between conductive electrodes while still preventing light leakage and reducing parasitic capacitance.
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 light leakage, reducing false signals and improving image quality by minimizing parasitic light sensitivity, allowing for sharper and more accurate image capture, especially in scenarios with varying illuminance or fast-moving subjects.
Implementation Method 1
a photoelectric converter which converts light into a signal charge
Data Source
AI summary
An imaging device includes a pixel, the pixel including a photoelectric converter which converts light into a signal charge and a charge detection circuit which detects the signal charge. The photoelectric converter includes a photoelectric conversion layer having a first surface and a second surface opposite to the first surface, a pixel electrode on the first surface, a first electrode adjacent to the pixel electrode on the first surface, the first electrode being electrically conductive to the photoelectric conversion layer, and a counter electrode on the second surface, the counter electrode facing the pixel electrode and the first electrode. A shortest distance between the pixel electrode and the first electrode in a plan view is smaller than a shortest distance between the pixel electrode and the first electrode.