Display Substrate Barrier Layers for Hydrogen-Stable Oxide TFTs

Resolve Bottlenecks,
Find Innovative SolutionsGenerate Solutions

Solution Overview

Problem

The integration of high-mobility and low-leakage current thin film transistors in display substrates, particularly in OLED devices, is compromised due to hydrogen sensitivity of metal oxide active layers, leading to performance degradation from hydrogen diffusion during manufacturing.

Innovation Solution

Incorporating barrier layers made of light-absorbing materials like molybdenum oxide or molybdenum oxide with neodymium and tantalum on either side of the metal oxide active layers to block hydrogen and light, ensuring the second thin film transistor's stability and performance.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If a metal oxide thin film transistor is provided in the display substrate to achieve low leakage current, then the leakage current is reduced, but the metal oxide active layer becomes sensitive to hydrogen diffusion which adversely affects transistor performance

Engineering Contradiction:

Improveleakage currentVSAvoidhydrogen diffusion

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A barrier layer made of light-absorbing material is introduced as an intermediary between the metal oxide active layer and the hydrogen environment. This barrier layer mediates the interaction by blocking hydrogen diffusion while allowing the metal oxide transistor to maintain its low leakage current characteristic.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The light-absorbing property of the barrier layer material is utilized to convert the harmful effect of light exposure into a beneficial protective function. The same property that allows the layer to absorb light also enables it to block hydrogen diffusion, turning an optical characteristic into a dual protective mechanism.

Inventive Principle:

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

2Reliability

If barrier layers are added to protect the metal oxide active layer from hydrogen diffusion, then the electrical reliability is improved, but the device structure becomes more complex

Engineering Contradiction:

Improveelectrical reliabilityVSAvoidstructure complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The barrier layer is designed to perform multiple functions simultaneously: it blocks hydrogen diffusion, absorbs light to prevent photo-induced effects, and serves as a protective interface. This multi-functionality reduces the need for additional separate protective structures, thereby limiting the increase in device complexity.

Inventive Principle:

Principle #6Universality (Multi-functionality)

Solution Approach 2:

The barrier layer material is selected with specific optical parameters (light absorption characteristics) that enable it to perform multiple protective functions. By changing the material parameters to have high light absorption, the layer achieves both optical protection and hydrogen blocking in a single structure.

Inventive Principle:

Principle #35Parameter changes

3Object-affected harmful factors

If the barrier layer material is made of light absorbing material, then hydrogen diffusion and light exposure are blocked, but the manufacturing process becomes more difficult

Engineering Contradiction:

Improvehydrogen diffusion and light exposureVSAvoidmanufacturing process

Core Design Contradiction:

Object-affected harmful factorsVSEase of manufacture

Solution Approach 1:

The barrier layer utilizes composite material properties, combining light absorption characteristics with hydrogen blocking capability. This composite approach allows a single layer to address multiple protection needs while using established material systems that can be integrated into existing manufacturing processes.

Inventive Principle:

Principle #40Composite materials

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 barrier layers effectively prevent hydrogen and light from affecting the metal oxide active layers, enhancing the electrical reliability and stability of the display substrate by blocking ion diffusion and light irradiation, thus maintaining optimal transistor performance.

Implementation Method 1

hydrogen may diffuse into the active layer of the second thin film transistor, adversely affecting the active layer of the second thin film transistor

Methodology Applied

Scientific EffectHydrogen diffusion: Diffusion

Implementation Method 2

the first barrier layer and/or the second barrier layer are made of a light absorbing material

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS20230307466A1Display substrate and manufacturing method thereof, and display device

Publication Date: 2023.09.28 BOE TECHNOLOGY GROUP CO LTD

AI summary

The present disclosure provides a display substrate, a manufacturing method thereof, and a display device. The display substrate comprises a base substrate, and a first thin film transistor and a second thin film transistor formed on the base substrate, wherein a first active layer of the first thin film transistor is made of low-temperature polysilicon, and a second active layer of the second thin film transistor is made of a metal oxide. The display substrate further comprises a first barrier layer on a side of the second active layer close to the base substrate and a second barrier layer on a side of the second active layer away from the base substrate. The orthographic projection of the second active layer onto the base substrate falls within the orthographic projections of the first barrier layer and the second barrier layer onto the base substrate.