Organic EL Device Fabrication via Selective Insulating Layer Etching

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Solution Overview

Problem

The existing fabrication methods for organic EL devices face challenges in preventing unintentional parasitic light emission due to steps formed at the periphery of pixel regions, which complicates the process and reduces the light emission area, as they require light-shielding films to mitigate this issue.

Innovation Solution

A method involving the formation of a third insulating layer with different etching rates for the second insulating layer, allowing for planarization without the need for additional light-shielding films, by using a precursor insulating layer and chemical mechanical polishing, ensuring a flat surface and adjusted thicknesses for each pixel region, thereby preventing parasitic light emission.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a transparent conductive film is formed on the anode to vary the light path length according to colors, then the brightness and color reproducibility are improved, but steps are formed along the periphery of pixel regions causing parasitic light emission

Engineering Contradiction:

ImprovebrightnessVSAvoidparasitic light emission

Core Design Contradiction:

Illumination intensityVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by forming the second insulating layer with different thicknesses in different pixel regions (first pixel region vs second pixel region) to achieve color-specific light path lengths. The layer has a first thickness in the first pixel region and a second thickness in the second pixel region, allowing each region to be optimized for its specific color emission while maintaining a flat upper surface to prevent parasitic light emission.

Inventive Principle:

Principle #3Local quality

2Object-affected harmful factors

If a light-shielding oxide film is formed to cover the step portion, then parasitic light emission is prevented, but the fabrication process becomes complicated and the light emission-capable region is reduced

Engineering Contradiction:

Improveparasitic light emissionVSAvoidfabrication process complexity

Core Design Contradiction:

Object-affected harmful factorsVSDevice complexity

Solution Approach 1:

Instead of adding a light-shielding film to cover steps (conventional approach), the patent inverts the approach by making the second insulating layer itself have a flat upper surface through selective thickness control. This eliminates the need for additional light-shielding films while maintaining prevention of parasitic light emission, thereby simplifying the fabrication process.

Inventive Principle:

Principle #13The other way round (Inversion)

3Object-affected harmful factors

If a light-shielding film is formed along the periphery of pixel regions, then parasitic light emission is prevented, but the light emission-capable region for each color is reduced

Engineering Contradiction:

Improveparasitic light emissionVSAvoidlight emission-capable region

Core Design Contradiction:

Object-affected harmful factorsVSArea of stationary object

Solution Approach 1:

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 simplifies the fabrication process, eliminates the need for light-shielding films, and enhances the reliability of the organic EL device by ensuring a flat surface and optimized light path lengths for each pixel region, reducing parasitic light emission and improving display quality.

Implementation Method 1

removing the third insulating layer in a first pixel region by etching the third insulating layer; the first insulating layer is slower in the rate at which the layer is removed by the etching than the third insulating layer

Methodology Applied

Scientific EffectEtching:

Implementation Method 2

planarizing an upper surface of the precursor insulating layer

Methodology Applied

Scientific EffectChemical mechanical polishing:

Implementation Method 3

first-color light being resonated between the first reflection film and the first counter electrode; second-color light being resonated between the second reflection film and the second counter electrode

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS8956898B2Fabrication method for organic EL device

Publication Date: 2015.02.17 SEIKO EPSON CORP

AI summary

The fabrication method for an organic EL device according to the invention includes: forming a third insulating layer on a first insulating layer; removing the third insulating layer in a first pixel region by etching the third insulating layer; forming a second insulating layer that has different thicknesses in a first pixel and a second pixel and has a flat first surface by forming a precursor insulating layer to continuously cover a first reflection film and a second reflection film and then planarizing an upper surface of the precursor insulating layer; and forming a first pixel electrode and a second pixel electrode on the first surface of the second insulating layer. The first insulating layer is slower in the rate at which the layer is removed by etching than the third insulating layer.