Stacked Imaging Element Charge Storage for Blooming Control

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Solution Overview

Problem

The charge generated by photoelectric conversion in imaging elements can flow into adjacent elements, leading to blooming and degradation of image quality in conventional stacked imaging elements.

Innovation Solution

The imaging element incorporates a charge storage electrode separated from the first electrode by an insulating layer, with specific design features such as potential differences, narrower and thicker regions, and higher dielectric constants to control charge movement and storage, preventing charge flow into adjacent elements.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a conventional stacked imaging element structure is used, then multiple photoelectric conversion units can be stacked to capture different color wavelengths, but charge generated by photoelectric conversion flows into adjacent elements causing blooming and image quality degradation

Engineering Contradiction:

Improvecolor wavelength capture capabilityVSAvoidcharge flow into adjacent elements

Core Design Contradiction:

Adaptability or versatilityVSObject-affected harmful factors

Solution Approach 1:

An insulating layer is introduced as an intermediary between adjacent photoelectric conversion units. This insulating layer acts as a barrier that prevents charge carriers generated in one photoelectric conversion unit from flowing into adjacent units, thereby eliminating the blooming effect while maintaining the stacked structure's color capture capability

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The photoelectric conversion layer is divided into multiple independent photoelectric conversion units, each responsible for capturing specific color wavelengths. By segmenting the continuous photoelectric conversion layer into discrete units separated by insulating layers, charge confinement is achieved within each unit while maintaining the overall stacked architecture

Inventive Principle:

Principle #1Segmentation

2Reliability

If photoelectric conversion units are stacked to eliminate demosaicing and false colors, then image quality should improve, but charge storage control becomes difficult leading to blooming

Engineering Contradiction:

Improveimage quality without demosaicingVSAvoidcharge storage control mechanism

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent transitions from planar charge storage to three-dimensional charge storage by stacking photoelectric conversion units vertically. Each unit has its own charge storage region, allowing independent charge management in the vertical dimension. This dimensional change enables better charge confinement and control while maintaining the benefits of stacked architecture for eliminating demosaicing

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

3Use of energy by moving object

If the photoelectric conversion layer is made thicker to improve light absorption, then photoelectric conversion efficiency increases, but charge diffusion to adjacent elements increases causing blooming

Engineering Contradiction:

Improvephotoelectric conversion efficiencyVSAvoidcharge diffusion

Core Design Contradiction:

Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The thick photoelectric conversion layer is segmented into multiple thinner photoelectric conversion units separated by insulating layers. Each unit maintains sufficient thickness for effective light absorption while the insulating layers prevent charge diffusion between units. This segmentation allows the system to achieve both high photoelectric conversion efficiency and effective charge confinement

Inventive Principle:

Principle #1Segmentation

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 prevents charge transfer to adjacent elements, maintaining image quality by fully depleting the charge storage portion and attracting charges to the designated electrode, thereby reducing kTC noise and blooming.

Implementation Method 1

when light enters the photoelectric conversion layer, photoelectric conversion is performed

Methodology Applied

Scientific EffectPhotoelectric conversion: Photovoltaic Effect

Implementation Method 2

a charge storage electrode arranged apart from the first electrode and arranged to face the photoelectric conversion layer through an insulating layer

Methodology Applied

Scientific EffectElectrical insulation: Dielectric

Data Source

PatentUS20250338655A1Imaging element, stacked imaging element, and solid-state imaging apparatus

Publication Date: 2025.10.30 SONY SEMICON SOLUTIONS CORP

AI summary

An imaging element includes a photoelectric conversion unit including a first electrode 11, a photoelectric conversion layer 13, and a second electrode 12 that are stacked, in which the photoelectric conversion unit further includes a charge storage electrode 14 arranged apart from the first electrode 11 and arranged to face the photoelectric conversion layer 13 through an insulating layer 82, and when photoelectric conversion occurs in the photoelectric conversion layer 13 after light enters the photoelectric conversion layer 13, an absolute value of a potential applied to a part 13C of the photoelectric conversion layer 13 facing the charge storage electrode 14 is a value larger than an absolute value of a potential applied to a region 13B of the photoelectric conversion layer 13 positioned between the imaging element and an adjacent imaging element.