ALD Encapsulation for LED Mirror Diffusion

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Solution Overview

Problem

Optoelectronic semiconductor chips, particularly light-emitting diode chips, face challenges in maintaining long lifetime due to susceptibility of metal mirror layers to diffusion, electromigration, and moisture, which can reduce reflectivity and efficiency.

Innovation Solution

An optoelectronic semiconductor chip is designed with a semiconductor body, a metallic mirror layer for radiation reflection, and an ALD encapsulation layer to protect against moisture and atmospheric gases, ensuring the mirror layer's integrity and radiation transparency.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Illumination intensity

If a metallic mirror layer is used for radiation reflection, then reflectivity is improved, but susceptibility to diffusion and electromigration worsens

Engineering Contradiction:

ImprovereflectivityVSAvoidsusceptibility to diffusion and electromigration

Core Design Contradiction:

Illumination intensityVSReliability

Solution Approach 1:

A barrier layer is introduced as an intermediary between the metallic mirror layer and the surrounding environment. This barrier layer prevents direct contact between the metal and atmospheric gases, thereby stopping diffusion and electromigration processes while preserving the mirror layer's high reflectivity properties.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The mirror structure is transformed from a single metallic layer into a composite structure consisting of multiple layers including the metallic mirror layer and protective barrier layers. This composite structure combines the high reflectivity of metal with the protective properties of barrier materials, resolving the contradiction between performance and reliability.

Inventive Principle:

Principle #40Composite materials

2Illumination intensity

If a metallic mirror layer is used for radiation reflection, then reflectivity is improved, but oxidation in moist environment worsens

Engineering Contradiction:

ImprovereflectivityVSAvoidoxidation in moist environment

Core Design Contradiction:

Illumination intensityVSObject-affected harmful factors

Solution Approach 1:

A protective barrier layer serves as an intermediary between the metallic mirror layer and the moist environment. This barrier layer blocks atmospheric gases and moisture from reaching the metal surface, preventing oxidation while allowing the mirror layer to maintain its high reflectivity.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

A thin, sacrificial protective layer is applied over the metallic mirror layer. This layer is designed to provide immediate protection against oxidation and can be easily replaced if needed, while the expensive metallic mirror layer remains protected underneath.

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

3Reliability

If encapsulation layer is added to protect mirror layer, then reliability is improved, but device complexity worsens

Engineering Contradiction:

Improveprotection against diffusion and moistureVSAvoidnumber of layers

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

A thin film encapsulation layer is applied over the metallic mirror layer. This thin protective shell provides comprehensive protection against diffusion, moisture, and oxidation without significantly increasing device complexity or thickness. The thin film approach maintains structural simplicity while delivering reliable protection.

Inventive Principle:

Principle #30Flexible shells and thin films

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 ALD encapsulation layer provides reliable protection against moisture and maintains high reflectivity, leading to increased efficiency and extended lifespan of the optoelectronic semiconductor chip by preventing material diffusion and absorption of electromagnetic radiation.

Implementation Method 1

an ALD encapsulation layer to protect against moisture and atmospheric gases

Methodology Applied

Scientific EffectPhysical containment: Physical Containment

Implementation Method 2

a first mirror layer, which is intended for reflection of the electromagnetic radiation

Methodology Applied

Scientific EffectReflection: Reflection

Implementation Method 3

an active region intended for generating electromagnetic radiation... when the semiconductor body is supplied with electricity, the electromagnetic radiation is generated

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS9761770B2Optoelectronic semiconductor chip encapsulated with an ALD layer and corresponding method for production

Publication Date: 2017.09.12 OSRAM OLED

AI summary

An optoelectronic semiconductor chip includes a semiconductor body with an active region provided for generating electromagnetic radiation, a first mirror layer provided for reflecting the electromagnetic radiation, a first encapsulation layer formed with an electrically insulating material, and a carrier provided for mechanically supporting the first encapsulation layer, the first mirror layer and the semiconductor body. The first mirror layer is arranged between the carrier and the semiconductor body. The first encapsulation layer is arranged between the carrier and the first mirror layer. The first encapsulation layer is an ALD layer.