OLED Pixel Electrode Patterning Without Shadow Masks

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Solution Overview

Problem

Existing methods for fabricating display devices struggle to achieve high resolution, high display quality, high contrast, and high reliability, particularly due to inaccuracies in forming EL layers using shadow masks, which lead to reduced aperture ratios and non-uniform patterns.

Innovation Solution

A method involving the formation of EL layers without a shadow mask, utilizing dry and wet etching techniques to create separate EL and sacrificial layers over pixel electrodes, allowing for precise patterning and integration of minute light-emitting elements, with etching processes optimized to maintain uniform thickness and minimize non-emitting regions.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Ease of manufacture

If shadow masks are used to form light-emitting elements, then manufacturing process is simplified, but manufacturing precision deteriorates due to deviations and reduced aperture ratios

Engineering Contradiction:

Improvemanufacturing process simplicityVSAvoidaperture ratio and positioning accuracy

Core Design Contradiction:

Ease of manufactureVSManufacturing precision

Solution Approach 1:

The patent divides the light-emitting element formation process into multiple sequential steps: first forming a sacrificial film pattern, then depositing EL films in separate steps for different pixels. This segmentation eliminates the need for shadow masks while achieving precise positioning, resolving the contradiction between manufacturing simplicity and precision.

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The patent performs preliminary actions by first forming sacrificial film patterns that define pixel boundaries before depositing EL films. This preliminary structuring enables precise EL film placement without shadow masks, improving manufacturing precision while maintaining process simplicity.

Inventive Principle:

Principle #10Preliminary action

2Manufacturing precision

If resolution is increased to achieve higher display quality, then display quality improves, but manufacturing complexity increases

Engineering Contradiction:

Improvedisplay resolutionVSAvoidmanufacturing process complexity

Core Design Contradiction:

Manufacturing precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical shadow mask system with a chemical deposition process guided by sacrificial film patterns. This substitution enables high-resolution EL film formation without the complexity of aligning and positioning shadow masks, resolving the contradiction between resolution and manufacturing complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Productivity

If aperture ratio is increased to reduce non-light-emitting regions, then display efficiency improves, but manufacturing precision requirements increase

Engineering Contradiction:

Improvelight-emitting area efficiencyVSAvoidlayer thickness and spacing control

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent uses sacrificial films as intermediary structures that define pixel boundaries and guide EL film deposition. These intermediaries enable precise control of layer thickness and spacing while maximizing aperture ratio, as the sacrificial films can be formed with high precision using standard photolithography techniques.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 enables display devices with resolutions exceeding 500 ppi, high aperture ratios, and improved contrast by reducing non-emitting regions, achieving clear and efficient light emission without the need for pseudo-improvement methods like PenTile arrangement.

Implementation Method 1

The first EL film and the second EL film are etched by dry etching

Methodology Applied

Scientific EffectDry etching: Plasma

Implementation Method 2

the first sacrificial layer and the second sacrificial layer are removed by wet etching

Methodology Applied

Scientific EffectWet etching: Solvation

Data Source

PatentUS12615913B2Method for fabricating display device including forming pixel electrode, el layer, and sacrificial layer

Publication Date: 2026.04.28 SEMICON ENERGY LAB CO LTD

AI summary

A method for fabricating a display device that easily achieves higher resolution is provided. A display device having both high display quality and high resolution is provided. A first EL film is formed over a first pixel electrode and a second pixel electrode; a first sacrificial film is formed to cover the first EL film; the first sacrificial film and the first EL film are etched to expose the second pixel electrode and to form a first EL layer over the first pixel electrode and a first sacrificial layer over the first EL layer; and the first sacrificial layer is removed. The first EL film and the second EL film are etched by dry etching, and the first sacrificial layer is removed by wet etching.