Stacked Imaging Element Charge Storage Electrode Noise Control

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Solution Overview

Problem

The existing imaging elements face challenges in completely depleting the photoelectric conversion units, leading to increased kTC noise, worsened random noise, and degraded image quality.

Innovation Solution

The proposed imaging element includes a photoelectric conversion unit with a charge storage electrode and a transfer control electrode, allowing for complete depletion of the charge storage portion and improved noise control.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If charges are directly stored in the floating diffusion layer without complete depletion, then the structure is simple, but kTC noise increases and image quality deteriorates

Engineering Contradiction:

Improveimage qualityVSAvoidphotoelectric conversion unit structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The photoelectric conversion unit is segmented into multiple independent components: photoelectric conversion layer, charge storage electrode, transfer control electrode, and floating diffusion layer. This segmentation allows complete depletion of charges from the photoelectric conversion layer before storage, reducing kTC noise while maintaining manageable structural complexity through modular design.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

A charge storage electrode is introduced as an intermediary between the photoelectric conversion layer and the floating diffusion layer. This intermediary component enables complete charge depletion and transfer control, improving image quality by reducing noise, while the added complexity is offset by the systematic organization of the charge transfer pathway.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Object-affected harmful factors

If a charge storage electrode and transfer control electrode are added, then complete depletion and noise control are achieved, but device complexity increases

Engineering Contradiction:

ImprovekTC noise and random noiseVSAvoidelectrode structure

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

The charge storage function is extracted as a separate electrode component distinct from the floating diffusion layer. This extraction allows independent optimization of charge storage and transfer control functions, effectively reducing noise while organizing the increased device complexity into functional modules with clear responsibilities.

Inventive Principle:

Principle #2Taking out (Extraction)

Solution Approach 2:

The transfer control electrode introduces dynamic control capability to the charge transfer process. By enabling active control of charge transfer timing and completeness, the system achieves superior noise reduction performance while the dynamic control mechanism is systematically integrated into the electrode structure.

Inventive Principle:

Principle #15Dynamics

3Measurement precision

If charges are not completely depleted from the photoelectric conversion unit, then the structure remains simple, but random noise worsens and sensitivity decreases

Engineering Contradiction:

Improvecharge detection accuracyVSAvoidcharge transfer control structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The charge storage electrode and transfer control electrode are positioned and configured to enable preliminary complete depletion of charges from the photoelectric conversion layer before charge storage. This preliminary action ensures maximum charge detection accuracy while the structured electrode arrangement manages the complexity of the charge transfer control mechanism.

Inventive Principle:

Principle #10Preliminary action

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 suppresses the occurrence of kTC noise, random noise, and image quality degradation, while enabling high controllability of charge transfer and maintaining sensitivity.

Implementation Method 1

An imaging element using an organic semiconductor material for a photoelectric conversion layer can photoelectrically convert a specific color (wavelength band)

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS20250126379A1Imaging element, stacked-type imaging element, and solid-state imaging apparatus

Publication Date: 2025.04.17 SONY SEMICON SOLUTIONS CORP

AI summary

There is provided an imaging element includes a photoelectric conversion unit that includes a first electrode, a photoelectric conversion layer, and a second electrode, in which the photoelectric conversion unit further includes a charge storage electrode that has an opposite region opposite to the first electrode via an insulating layer, and a transfer control electrode that is opposite to the first electrode and the charge storage electrode via the insulating layer, and the photoelectric conversion layer is disposed above at least the charge storage electrode via the insulating layer.