Shield Electrode Suppresses Pseudo Signals in Solid-State Image Pickup Device
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Solution Overview
Problem
Conventional solid-state imaging apparatuses suffer from electrostatic coupling between adjacent lower electrodes, leading to the generation of pseudo signals, which deteriorate image quality due to varying signal outputs across pixels, especially with miniaturization, where the ratio of pseudo signals to original signals increases, affecting color resolution and image quality.
Innovation Solution
A solid-state imaging apparatus with a shield electrode having a fixed potential is introduced, extending through the gap between adjacent lower electrodes, ensuring all electrodes are equally affected by electrostatic coupling, thereby suppressing the generation of different pseudo signals and maintaining consistent signal output.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the gap between adjacent lower electrodes is reduced to at most 3 μm to prevent afterimage, then afterimage is suppressed, but electrostatic coupling between adjacent lower electrodes increases, generating pseudo signals that deteriorate image quality
Solution Approach 1:
A shield electrode is introduced as an intermediary element positioned between adjacent lower electrodes. This shield electrode has a fixed potential and is electrically insulated from the lower electrodes, serving as a mediator that blocks electrostatic coupling between adjacent lower electrodes while allowing the gap between them to remain narrow for afterimage suppression
Solution Approach 2:
The shield electrode is maintained at a fixed potential, creating an equipotential region between adjacent lower electrodes. This equipotential condition prevents potential differences from developing between adjacent electrodes, thereby eliminating the electrostatic coupling that generates pseudo signals
2Manufacturing precision
If miniaturization of pixels is pursued to increase resolution, then image resolution is improved, but the ratio of pseudo signals to original signal charges increases, deteriorating image quality
Solution Approach 1:
The shield electrode acts as a protective intermediary that isolates adjacent lower electrodes from each other's electrostatic influence. This isolation becomes increasingly important as pixels are miniaturized, preventing pseudo signal generation that would otherwise dominate the weaker signal charges from smaller pixels
Solution Approach 2:
The shield electrode is positioned in advance between adjacent lower electrodes to prevent electrostatic coupling before it can occur. By establishing this protective barrier beforehand, the system proactively counteracts the tendency for pseudo signal generation that becomes more pronounced with pixel miniaturization
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 solution effectively prevents the deterioration of image quality by ensuring all lower electrodes generate the same amount of pseudo signals, correcting signal output values and improving image fidelity, even with narrow gaps between adjacent electrodes.
Implementation Method 1
a photoelectric conversion film 950 formed on the lower electrodes 930
Implementation Method 2
each pair of adjacent lower electrodes may be affected by an electrostatic coupling that is generated therebetween due to a difference in potential
Data Source
AI summary
A solid-state imaging apparatus having a plurality of pixels, comprising: a substrate; a wiring layer formed on the substrate and including an insulating film and a plurality of wires; a plurality of lower electrodes formed on the wiring layer in one-to-one correspondence with the plurality of pixels; a photoelectric conversion film formed covering the plurality of lower electrodes; a light-transmissive upper electrode formed on the photoelectric conversion film; and a shield electrode extending through a gap between each pair of adjacent lower electrodes among the plurality of lower electrodes, the shield electrode having a fixed potential and being electrically insulated from the plurality of lower electrodes.