Flexible Array Substrate Shielding Layout for Laser Lift-Off Yield

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Solution Overview

Problem

The existing manufacturing process of flexible array substrates for AMOLED displays faces issues with contamination and yield loss due to the softening of rigid substrates under high temperatures during laser lift-off, leading to mura defects and contamination of the light-shielding layer.

Innovation Solution

A flexible array substrate design where a light-shielding layer is placed between the flexible substrate and the thin film transistor, absorbing the laser light energy and preventing contamination, with additional barrier layers and buffer layers to prevent metal ion diffusion and enhance TFT characteristics.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If laser lift-off is used to remove the rigid substrate, then the flexible array substrate can be obtained, but the rigid substrate softens under high temperature causing contamination and mura defects

Engineering Contradiction:

Improveoutput rateVSAvoidcontamination and mura defects

Core Design Contradiction:

ProductivityVSObject-affected harmful factors

Solution Approach 1:

A light-shielding layer is introduced as an intermediary component between the rigid substrate and the flexible array substrate. This layer absorbs laser light energy during the lift-off process, preventing the rigid substrate from softening and contaminating the flexible substrate. The light-shielding layer acts as a mediator that protects the sensitive flexible substrate from the harmful thermal effects while enabling the necessary laser processing to occur.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The invention converts the harmful laser light energy that causes substrate softening into a beneficial protective mechanism. By positioning the light-shielding layer to absorb the laser energy, the harmful thermal effect is redirected to protect rather than damage the flexible substrate. The layer that would normally be damaged by laser exposure instead becomes the protective element.

Inventive Principle:

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

2Object-affected harmful factors

If the light-shielding layer is placed close to the flexible substrate to block laser light, then contamination is prevented, but metal ions may diffuse into the TFT channel region

Engineering Contradiction:

Improvecontamination preventionVSAvoidleakage current

Core Design Contradiction:

Object-affected harmful factorsVSReliability

Solution Approach 1:

A buffer layer is introduced as a second intermediary component between the light-shielding layer and the thin film transistor. This buffer layer serves dual functions: it maintains the protective positioning of the light-shielding layer close to the flexible substrate, and simultaneously acts as a barrier to prevent metal ion diffusion from the light-shielding layer into the TFT channel region. The buffer layer mediates between the need for effective laser shielding and the need to protect TFT electrical characteristics.

Inventive Principle:

Principle #24Intermediary (Mediator)

3Reliability

If multiple barrier layers are added to prevent metal ion diffusion, then TFT reliability is improved, but the device structure becomes more complex

Engineering Contradiction:

Improveleakage current suppressionVSAvoidlayer structure

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The buffer layer is designed to perform multiple functions simultaneously: it acts as a barrier layer to prevent metal ion diffusion, provides mechanical support, and facilitates the positioning of the light-shielding layer. By making the buffer layer multi-functional, the invention achieves effective protection against leakage currents without proportionally increasing device complexity. The same structural element serves multiple protective and structural roles.

Inventive Principle:

Principle #6Universality (Multi-functionality)

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 design improves product yield and output rate by preventing contamination and mura defects, ensuring high-resolution and high-quality displays by effectively blocking laser light and inhibiting leakage currents.

Implementation Method 1

a light-shielding layer which is between the first flexible substrate and the thin film transistor, in which an orthographic projection of the light-shielding layer on the first flexible substrate covers an orthographic projection of a channel region of the thin film transistor on the first flexible substrate

Methodology Applied

Scientific EffectLight absorption: Absorption (EM radiation)

Data Source

PatentUS11830886B2Flexible array substrate, manufacturing method thereof and display device

Publication Date: 2023.11.28 BOE TECHNOLOGY GROUP CO LTD

AI summary

A flexible array substrate, a manufacturing method thereof and a display device are provided. The flexible array substrate includes: a first flexible substrate with a first surface; a thin film transistor on the first surface; and a light-shielding layer between the first flexible substrate and the thin film transistor. An orthographic projection of the light-shielding layer on the first flexible substrate covers an orthographic projection of a channel region of the thin film transistor on the first flexible substrate.