Amorphous Oxide Electrode UV Absorption in Imaging Sensors

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Solution Overview

Problem

Existing imaging elements face challenges with increased dark current and in-plane unevenness due to ultraviolet light exposure during manufacturing, and previous solutions have not effectively addressed these issues while simplifying the manufacturing process.

Innovation Solution

A stacked structure with a second electrode made of amorphous oxide containing zinc and tungsten, which is transparent and electrically conductive, providing absorption characteristics and reducing ultraviolet light exposure to the light-receiving layer.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a transparent electrode made of ITO is used, then electrical conductivity and transparency are achieved, but ultraviolet light passes through to the light receiving layer causing increased dark current and in-plane unevenness

Engineering Contradiction:

Improvedark current suppressionVSAvoidultraviolet light exposure to light receiving layer

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

An amorphous oxide layer is introduced as an intermediary between the ITO transparent electrode and the light receiving layer. This intermediate layer absorbs ultraviolet light while allowing visible light to pass through, preventing UV damage to the light receiving layer without compromising the electrode's transparency and conductivity functions.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The electrode structure is formed as a composite of multiple materials: ITO (indium tin oxide) providing electrical conductivity and transparency, combined with an amorphous oxide layer (such as silicon oxide, germanium oxide, or tin oxide) that provides ultraviolet absorption. This composite structure simultaneously achieves conductivity, transparency, and UV protection.

Inventive Principle:

Principle #40Composite materials

2Reliability

If ultraviolet absorbing units are added to block ultraviolet light, then afterimage characteristics improve, but the manufacturing process becomes complicated and time-consuming

Engineering Contradiction:

Improveafterimage characteristicsVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The ultraviolet absorption function is merged with the transparent electrode structure itself. The amorphous oxide layer is formed as part of the electrode assembly process using existing manufacturing techniques, combining the electrode formation and UV absorption layer creation into a single integrated process rather than adding separate absorbing units.

Inventive Principle:

Principle #5Merging (Combining)

Solution Approach 2:

The amorphous oxide layer serves multiple functions simultaneously: it acts as a transparent conductive electrode material, provides ultraviolet absorption to protect the light receiving layer, and improves afterimage characteristics. This multi-functionality eliminates the need for separate dedicated UV absorbing components.

Inventive Principle:

Principle #6Universality (Multi-functionality)

3Reliability

If the second electrode is made thicker to improve ultraviolet absorption, then dark current suppression improves, but visible light transmission decreases reducing quantum efficiency

Engineering Contradiction:

Improvedark current suppressionVSAvoidquantum efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The thickness of the amorphous oxide layer is precisely controlled within the range of 1 nm to 100 nm. This parameter optimization ensures sufficient ultraviolet absorption while maintaining high visible light transmission. The specific thickness range balances UV protection and visible light transparency to achieve both dark current suppression and high quantum efficiency.

Inventive Principle:

Principle #35Parameter changes

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

The solution effectively suppresses ultraviolet light reaching the light-receiving layer, reducing dark current and improving afterimage characteristics while maintaining a simple manufacturing process and enhancing quantum efficiency.

Implementation Method 1

the second electrode includes an amorphous oxide comprising at least one of zinc and tungsten... absorption characteristics of 20% or more at a wavelength of 300 nm

Methodology Applied

Scientific EffectUltraviolet absorption: Absorption (EM radiation)

Implementation Method 2

a light receiving layer (a photoelectric conversion layer) is sandwiched by two electrodes

Methodology Applied

Scientific EffectPhotoelectric conversion: Photoelectric Effect

Data Source

PatentUS11374138B2Imaging element, solid state imaging device, and electronic device having an amorphous oxide electrode comprising tungsten

Publication Date: 2022.06.28 SONY GROUP CORP

AI summary

There is provided imaging devices and methods of forming the same, including a stacked structure body including a first electrode, a light-receiving layer formed on the first electrode, and a second electrode formed on the light-receiving layer, where the second electrode comprises an amorphous oxide comprising at least one of zinc and tungsten, and where the second electrode is transparent and electrically conductive and has absorption characteristics of 20% or more at a wavelength of 300 nm.