Array Substrate With Hydrogen Buffer Layer For Stable TFT Integration

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Solution Overview

Problem

Low-temperature polysilicon thin film transistors (LTPS-TFTs) suffer from high leakage currents and unstable threshold voltage, while metal oxide TFTs are sensitive to external environments and have unstable threshold voltage, making it difficult to achieve high PPI and stable gray scale display. Additionally, manufacturing both on the same substrate is challenging due to hydrogen supplementation issues that can cause short circuits.

Innovation Solution

An array substrate is designed with a polysilicon thin film transistor and a metal oxide thin film transistor on the same base substrate, using an interlayer dielectric layer to supply hydrogen and a buffer layer to block hydrogen, preventing hydrogen ions from reaching the metal oxide layer and reducing oxygen defects, thereby stabilizing both types of transistors and preventing short circuits.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If an interlayer dielectric layer capable of supplying hydrogen is used to improve polysilicon transistor stability, then hydrogen supplementation is achieved, but hydrogen ions may reach the metal oxide layer causing short circuits

Engineering Contradiction:

Improvepolysilicon transistor stabilityVSAvoidhydrogen ion damage to metal oxide layer

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

A buffer layer is introduced as an intermediary component between the interlayer dielectric layer and the metal oxide active layer. This buffer layer selectively blocks hydrogen ions from the interlayer dielectric layer from reaching the metal oxide layer, while allowing the interlayer dielectric layer to continue supplying hydrogen to the polysilicon active layer for stability improvement.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The structure is segmented into distinct functional layers: the interlayer dielectric layer for hydrogen supplementation, the buffer layer for hydrogen ion blocking, and the metal oxide active layer protected from hydrogen damage. This segmentation allows each layer to perform its specific function without interfering negatively with adjacent layers.

Inventive Principle:

Principle #1Segmentation

2Adaptability or versatility

If both LTPS-TFT and metal oxide TFT are manufactured on the same substrate, then integration is achieved, but manufacturing complexity increases due to conflicting hydrogen requirements

Engineering Contradiction:

Improvetransistor integrationVSAvoidmanufacturing process complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Different regions of the device structure are given different properties: the interlayer dielectric layer has hydrogen-supplying properties for the polysilicon region, while the buffer layer provides hydrogen-blocking properties to protect the metal oxide region. This local differentiation of material properties enables co-manufacturing of both transistor types on the same substrate without process conflicts.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If metal oxide TFT is used to reduce cost, then manufacturing cost decreases, but threshold voltage stability deteriorates due to environmental sensitivity

Engineering Contradiction:

Improvemanufacturing costVSAvoidthreshold voltage stability

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The buffer layer is positioned beforehand to cushion and block harmful hydrogen ions from reaching the metal oxide active layer. This preventive measure protects the metal oxide TFT from environmental sensitivity and threshold voltage instability, ensuring reliable operation while maintaining the cost advantages of metal oxide semiconductor technology.

Inventive Principle:

Principle #11Beforehand cushioning (Prior cushioning)

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 improves the stability and conductivity of polysilicon transistors and reduces leakage currents in metal oxide transistors, enhancing display performance by preventing short circuits and improving electron mobility and threshold voltage uniformity.

Implementation Method 1

an interlayer dielectric layer and a first buffer layer between the first active layer and the second active layer, wherein the interlayer dielectric layer is capable of supplying hydrogen

Methodology Applied

Scientific EffectHydrogen diffusion: Diffusion

Implementation Method 2

the first buffer layer is capable of blocking hydrogen

Methodology Applied

Scientific EffectHydrogen blocking: Diffusion Barrier

Data Source

PatentUS10748938B2Array substrate, method of manufacturing the same and display device

Publication Date: 2020.08.18 BOE TECHNOLOGY GROUP CO LTD

AI summary

an array substrate, a method of manufacturing the array substrate, and a display device are provided. The array substrate includes: a base substrate; a first thin film transistor and a second thin film transistor on the base substrate, wherein the first thin film transistor comprises a first active layer, the second thin film transistor comprises a second active layer, and the second active layer is on a side of the first active layer away from the base substrate; and an interlayer dielectric layer and a first buffer layer between the first active layer and the second active layer, wherein the interlayer dielectric layer is capable of supplying hydrogen and the first buffer layer is capable of blocking hydrogen.