Blue Laser Crystallized TFT Structure for Foldable Display Reliability

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Solution Overview

Problem

Existing thin film transistors used in flexible display devices face challenges in maintaining characteristics and preventing substrate damage when bent or folded, as current crystallization methods can lead to heat diffusion and surface protrusions.

Innovation Solution

A thin film transistor with a polysilicon semiconductor layer crystallized using a blue laser scan, featuring a buffer layer and specific electrode configurations, which prevents substrate damage and maintains performance even after repeated bending or folding.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If conventional crystallization methods are used, then polysilicon can be formed, but heat diffusion occurs and substrate surface protrusions are generated causing substrate damage

Engineering Contradiction:

Improvesubstrate integrityVSAvoidheat diffusion and surface protrusions

Core Design Contradiction:

ReliabilityVSObject-affected harmful factors

Solution Approach 1:

The patent replaces conventional thermal crystallization methods with blue laser beam crystallization. The blue laser beam provides localized, precise energy delivery that crystallizes the semiconductor layer without causing widespread heat diffusion. This substitution of the crystallization mechanism eliminates the harmful thermal effects that previously damaged the substrate while maintaining polysilicon formation.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The blue laser beam crystallization method applies energy locally and selectively to the semiconductor layer regions requiring crystallization. This localized treatment prevents heat from diffusing to surrounding areas and causing substrate damage or surface protrusions, while still achieving the necessary polysilicon crystallization in the target regions.

Inventive Principle:

Principle #3Local quality

2Adaptability or versatility

If the display device is bent or folded, then flexibility is achieved, but transistor characteristics deteriorate with conventional crystallization

Engineering Contradiction:

ImproveflexibilityVSAvoidtransistor characteristics

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent replaces conventional thermal crystallization with blue laser beam crystallization to produce polysilicon with superior crystalline structure. This substitution results in transistors that maintain stable characteristics even after repeated bending and folding operations, enabling flexible display devices without compromising device reliability.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Reliability

If blue laser scan crystallization is used, then substrate damage is prevented and transistor characteristics are maintained, but manufacturing process complexity increases

Engineering Contradiction:

Improvetransistor characteristics and substrate integrityVSAvoidmanufacturing process complexity

Core Design Contradiction:

ReliabilityVSEase of manufacture

Solution Approach 1:

The patent replaces conventional thermal crystallization equipment with blue laser beam crystallization equipment. While this substitution improves transistor characteristics and prevents substrate damage, it does introduce manufacturing process complexity. The blue laser system requires precise control and specialized equipment, representing a trade-off between enhanced device reliability and manufacturing complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 solution ensures that the thin film transistor's characteristics are not deteriorated, and the flexible substrate is not damaged, with minimal change in threshold voltage after 30,000 folding operations, maintaining the display device's quality and performance.

Implementation Method 1

crystallized by a blue laser scan

Methodology Applied

Scientific EffectLaser heating: Heating

Implementation Method 2

The semiconductor layer may be crystallized by full melting, partial melting, or may be a solid phase

Methodology Applied

Scientific EffectMelting: Melting

Implementation Method 3

crystallized by a blue laser scan

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS12176353B2Thin film transistor including crystallized semiconductor, display device including the same, manufacturing method of the same, and method for crystallizing semiconductor

Publication Date: 2024.12.24 ADRC CO KR

AI summary

A thin film transistor according to an exemplary embodiment includes: a substrate; a semiconductor layer disposed on the substrate and including a channel region, and an input region and an output region disposed on both sides of the channel region and doped with an impurity; a buffer layer disposed between the substrate and the semiconductor layer; a control electrode overlapping the semiconductor layer; a gate insulation layer disposed between the semiconductor layer and the control electrode; and an input electrode connected to the input region and an output electrode connected to the output region, wherein the semiconductor layer includes polysilicon and is crystallized by a blue laser scan.