Selective Laser Crystallization for OLED Amorphous Silicon

Solution Overview

Problem

The maintenance expenses for generating a laser beam in conventional crystallization methods for organic light-emitting display devices are high due to the need to crystallize large areas, which decreases productivity and increases costs.

Innovation Solution

Implementing a method where the laser generator is selectively turned on and off during crystallization, allowing for full crystallization in areas requiring high electron mobility, such as the circuit area, and selective crystallization in the pixel area, where only specific portions need high electron mobility, like TFTs, to maximize laser efficiency and reduce costs.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If the laser generator is continuously operated to crystallize the entire substrate area, then complete crystallization is achieved, but maintenance expenses increase and productivity decreases

Engineering Contradiction:

Improvecrystallization completenessVSAvoidmanufacturing efficiency

Core Design Contradiction:

ReliabilityVSProductivity

Solution Approach 1:

The patent applies local quality by differentiating crystallization requirements across different substrate regions. The circuit area undergoes full crystallization to ensure high electron mobility for TFT operation, while the pixel area uses selective crystallization only where needed (channel, storage, emission areas). This localized approach maintains necessary crystallization quality while reducing overall laser usage and maintenance costs.

Inventive Principle:

Principle #3Local quality

Solution Approach 2:

The substrate is segmented into distinct functional areas (circuit area and pixel area) with different crystallization requirements. The circuit area is fully crystallized to support TFT functionality, while the pixel area receives selective crystallization only in specific regions. This segmentation allows optimized laser application that balances crystallization completeness with manufacturing efficiency.

Inventive Principle:

Principle #1Segmentation

2Manufacturing precision

If the laser beam width is reduced to improve precision, then crystallization precision improves, but the area to be crystallized increases proportionally

Engineering Contradiction:

Improvecrystallization precisionVSAvoidtotal crystallization area

Core Design Contradiction:

Manufacturing precisionVSArea of stationary object

Solution Approach 1:

The patent applies local quality by differentiating crystallization requirements across different substrate regions. The circuit area undergoes full crystallization to ensure high electron mobility for TFT operation, while the pixel area uses selective crystallization only where needed (channel, storage, emission areas). This localized approach maintains necessary crystallization quality while reducing overall laser usage and maintenance costs.

Inventive Principle:

Principle #3Local quality

3Ease of manufacture

If amorphous silicon is used in the activation layer, then deposition is simpler, but electron mobility is insufficient for high-performance TFTs

Engineering Contradiction:

Improvedeposition simplicityVSAvoidelectron mobility

Core Design Contradiction:

Ease of manufactureVSReliability

Solution Approach 1:

The patent changes the physical state parameter of silicon from amorphous to polycrystalline in specific regions through selective laser crystallization. The activation layer is deposited as amorphous silicon and then selectively crystallized in the channel, storage, and emission areas to form polycrystalline silicon with high electron mobility. This parameter change enables high-performance TFT operation while maintaining manufacturing feasibility.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies local quality by differentiating crystallization requirements across different substrate regions. The circuit area undergoes full crystallization to ensure high electron mobility for TFT operation, while the pixel area uses selective crystallization only where needed (channel, storage, emission areas). This localized approach maintains necessary crystallization quality while reducing overall laser usage and maintenance costs.

Inventive Principle:

Principle #3Local quality

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 approach reduces laser maintenance expenses and improves productivity by efficiently using the laser for crystallization, while maintaining the necessary high electron mobility in critical areas, thus enhancing the overall efficiency of the organic light-emitting display device manufacturing process.

Implementation Method 1

a laser beam L that is not processed is emitted from a light source and passes through an attenuator (not shown) so that intensity of energy of the laser beam L is controlled, and the controlled laser beam L is irradiated through the focusing lens 92

Methodology Applied

Scientific EffectLaser heating: Laser

Implementation Method 2

an a-Si layer is deposited on the buffer layer and crystallized with the application of a laser beam to the deposited a-Si layer

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Data Source

PatentUS8575601B2Organic light-emitting display device and method of manufacturing the same

Publication Date: 2013.11.05 SAMSUNG DISPLAY CO LTD

AI summary

Disclosed is a method of manufacturing an organic light-emitting display device capable of improving efficiency of a laser generator used for crystallization of amorphous silicon. The method crystallizes amorphous silicon selectively to provide an organic light-emitting display device that includes channel area of a pixel contains polycrystalline silicon and storage area of the pixel contains amorphous silicon.