Tantalum Dioxide Anti-Diffusion Layer for Low-Resistance Gate Electrodes

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Solution Overview

Problem

In the manufacturing of large-size displays, the high resistance of molybdenum or molybdenum/aluminum-neodymium alloys used in gate electrodes leads to nonuniform current distribution, while low-resistance materials like copper or aluminum have poor adhesion and can diffuse into the active layer at low temperatures, affecting device performance.

Innovation Solution

A tantalum dioxide anti-diffusion layer is prepared at normal temperature using a tantalum sulfate solution with a graphite electrode, controlling pH and voltage to form a tantalum dioxide film that prevents diffusion, ensuring effective adhesion and conductivity.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If low-resistance material (copper or aluminum) is used for gate electrode, then electrical conductivity is improved, but adhesion to substrate and semiconductor deteriorates

Engineering Contradiction:
Improveelectrical conductivityVSAvoidadhesion
Core Design Contradiction:
ReliabilityVSStrength

Solution Approach 1:

The patent introduces an anti-diffusion layer as an intermediary between the low-resistance gate electrode material and the substrate/semiconductor. This intermediate layer solves the adhesion problem while allowing the copper or aluminum gate electrode to maintain its electrical conductivity, thus resolving the contradiction between conductivity and adhesion.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent employs a composite structure consisting of the low-resistance material (copper or aluminum) combined with an anti-diffusion layer. This composite material approach allows the system to simultaneously achieve the electrical conductivity benefits of copper/aluminum and the adhesion properties of the anti-diffusion layer.

Inventive Principle:
Principle #40Composite materials

2Reliability

If low-resistance material (copper or aluminum) is used for gate electrode, then electrical conductivity is improved, but diffusion into active layer occurs at low temperature

Engineering Contradiction:
Improveelectrical conductivityVSAvoiddiffusion into active layer
Core Design Contradiction:
ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The anti-diffusion layer serves as a protective intermediary between the low-resistance gate electrode material and the active layer. It prevents diffusion of copper or aluminum atoms into the active layer at low temperatures while allowing the gate electrode to function with high electrical conductivity.

Inventive Principle:
Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent converts the potential harmful effect of low-resistance material diffusion into a beneficial outcome by introducing the anti-diffusion layer. The layer that would otherwise be a barrier is transformed into a protective element that enables the use of low-resistance materials without their harmful diffusion effects.

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

3Reliability

If PVD or CVD method is used to prepare anti-diffusion layer, then anti-diffusion performance is improved, but manufacturing complexity and energy consumption increase

Engineering Contradiction:
Improveanti-diffusion performanceVSAvoidmanufacturing process complexity
Core Design Contradiction:
ReliabilityVSDevice complexity

Solution Approach 1:

The patent replaces the complex PVD or CVD processes with a simpler electrochemical deposition method. This substitution reduces manufacturing complexity and energy consumption while maintaining effective anti-diffusion performance, as the electrochemical process occurs at normal temperature and uses straightforward electrolytic solutions.

Inventive Principle:
Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent changes the processing parameters from high-temperature PVD/CVD conditions to normal temperature electrochemical deposition. This parameter change simplifies the manufacturing process and reduces energy consumption while achieving the same anti-diffusion function through a different mechanism.

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 method effectively prevents diffusion of metal ions, maintains electrical conductivity, and reduces energy consumption by avoiding high-temperature processes, thereby improving display device performance and reducing capital investment.

Implementation Method 1

placing the conductive base and a cathode in a tantalum sulfate solution taking the conductive base as an anode, and forming a tantalum oxide anti-diffusion layer on the conductive base after energizing

Methodology Applied
Scientific EffectElectrochemical deposition: Electrodeposition

Implementation Method 2

an anti-diffusion layer must be prepared on the low-resistance material... tantalum dioxide (TaO2) with good anti-diffusion performance is usually selected to prepare an anti-diffusion layer

Methodology Applied
Scientific EffectDiffusion barrier: Diffusion Barrier

Data Source

PatentEP2993691B1Anti-diffusion layer and preparation method, thin film transistor, array substrate and display device
Publication Date: 2020.01.01 BOE TECHNOLOGY GROUP CO LTD
  • EP2993691B1 patent drawingFigure 1

AI summary

An anti-diffusion layer, a preparation method thereof, a thin-film transistor (TFT), an array substrate and a display device are provided, involve the display device manufacturing field and can resolve problem that a high atmosphere temperature is need in process of preparing a tantalum dioxide anti-diffusion layer by PVD or CVD, which causes the gate electrode to volatilize and affect the performance of a display device. The method for preparing the anti-diffusion layer comprises: placing a conductive base (1) and a cathode (4) in a tantalum sulfate solution (3), taking the conductive base (1) as an anode, and forming a tantalum dioxide anti-diffusion layer on the conductive base (1) after energizing.