Electrowetting Device InZnO Electrode Dielectric Layer

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Solution Overview

Problem

Existing electrowetting devices face challenges in achieving sufficient breakdown voltage while being driven at low voltages, particularly when using silicon nitride layers on indium oxide-tin oxide electrodes, due to defects caused by crystallization of the ITO layer during production.

Innovation Solution

The electrowetting device incorporates a dielectric layer with a silicon nitride layer formed directly on an indium oxide-zinc oxide layer, which is thermally stable and less prone to crystallization, and includes a layered structure with silicon nitride layers of varying hydrogen concentrations to enhance breakdown voltage and adhesiveness, while being driven at low voltages.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Use of energy by moving object

If the thickness of the dielectric layer is reduced to increase voltage application efficiency, then voltage application efficiency is improved, but breakdown voltage is lowered causing leak failure

Engineering Contradiction:

Improvevoltage application efficiencyVSAvoidbreakdown voltage

Core Design Contradiction:

Use of energy by moving objectVSReliability

Solution Approach 1:

The patent employs a composite dielectric layer structure consisting of multiple silicon nitride layers with different hydrogen concentrations (e.g., first SiN layer with higher hydrogen concentration, second SiN layer with lower hydrogen concentration). This composite structure allows the dielectric layer to maintain thin thickness for voltage efficiency while achieving high breakdown voltage through the synergistic properties of different material compositions. The varying hydrogen concentrations create different electrical properties within the composite structure, preventing leak failures.

Inventive Principle:

Principle #40Composite materials

Solution Approach 2:

The patent applies local quality by creating silicon nitride layers with spatially varying hydrogen concentrations. The first SiN layer (closer to the electrode) has a different hydrogen concentration than the second SiN layer (closer to the hydrophobic layer). This local variation in material properties allows different regions of the dielectric layer to perform different functions: the lower hydrogen concentration region provides high breakdown voltage, while the overall thin structure maintains voltage application efficiency.

Inventive Principle:

Principle #3Local quality

2Ease of manufacture

If a silicon nitride layer is formed on an ITO electrode to create a dielectric layer, then device structure is formed, but defect density increases due to ITO crystallization during production

Engineering Contradiction:

Improvedevice structure formationVSAvoiddefect density

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the material parameter of the electrode from conventional ITO (indium tin oxide) to InZnO (indium zinc oxide). This material substitution fundamentally alters the thermal stability characteristics, preventing crystallization defects that occur with ITO during subsequent production processes. The InZnO material maintains amorphous structure at higher temperatures, eliminating the root cause of defect formation when silicon nitride layers are formed on the electrode.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the potential harm of thermal processing (which causes ITO crystallization and defects) into a benefit by using InZnO material that is specifically designed to resist crystallization. The thermal processes that would normally create defects in ITO-based devices instead serve to densify and stabilize the InZnO structure without causing harmful crystallization, thereby improving device reliability.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

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 significantly reduces defect density and improves breakdown voltage, enabling the electrowetting device to operate effectively with reduced leakage failures and improved adhesiveness, thus achieving better performance compared to previous technologies.

Implementation Method 1

a dielectric layer formed on the plurality of first electrodes

Methodology Applied

Scientific EffectDielectric: Dielectric

Implementation Method 2

a first hydrophobic layer formed on the dielectric layer

Methodology Applied

Scientific EffectHydrophobe: Hydrophobe

Implementation Method 3

Electrowetting is a phenomenon in which, when an electric field is applied to a liquid droplet that is arranged on a hydrophobic layer provided on an electrode, a contact angle of the squid droplet with respect to the dielectric layer is changed

Methodology Applied

Scientific EffectElectrowetting: Electrowetting

Data Source

PatentUS11577245B2Electrowetting device

Publication Date: 2023.02.14 SHARP KK

AI summary

An electrowetting device includes a first substrate, a plurality of first electrodes formed on the first substrate, a dielectric layer formed on the plurality of first electrodes, a first water-repellent layer formed on the dielectric layer, a second substrate, a second electrode formed on the second substrate, and a second water-repellent layer formed on the second electrode. The first substrate and the second substrate are arranged with a gap between the first water-repellent layer and the second water-repellent layer. The first electrode includes an indium oxide-zinc oxide layer, the dielectric layer includes a silicon nitride layer, and the silicon nitride layer is formed directly on the indium oxide-zinc oxide layer.