Buried Electrode LED Die Layout for Better Light Extraction

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Solution Overview

Problem

Light emitting dies with vertical electrodes face challenges in light extraction efficiency due to partially blocked light and non-accessible electrodes, which limits their performance in solid state lighting devices.

Innovation Solution

The design incorporates a light emitting die with a buried electrode configuration, where the first electrode is spaced apart from the second electrode, allowing for improved light extraction efficiency and accessible electrodes for easier connection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If vertical electrodes are used in light emitting dies, then current spreading is improved, but light extraction efficiency deteriorates due to electrode blocking

Engineering Contradiction:

Improvecurrent spreadingVSAvoidlight extraction efficiency

Core Design Contradiction:

ReliabilityVSLoss of energy

Solution Approach 1:

The device is segmented into multiple functional layers: the light emitting die with vertical electrodes, a reflective layer, and a transparent encapsulant. This segmentation allows each component to perform its specific function optimally - the vertical electrodes provide current spreading, the reflective layer redirects blocked light, and the transparent encapsulant allows light extraction, thereby resolving the contradiction between current spreading and light extraction efficiency

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The solution moves from a two-dimensional planar electrode configuration to a three-dimensional vertical electrode configuration. The electrodes extend through the thickness of the light emitting die, enabling current to spread in the vertical dimension while light extraction is maintained through the transparent encapsulant, thus resolving the contradiction between current spreading and light extraction

Inventive Principle:

Principle #17Another dimension (Dimensionality change)

2Reliability

If vertical electrodes are used in light emitting dies, then current spreading is improved, but electrode accessibility deteriorates

Engineering Contradiction:

Improvecurrent spreadingVSAvoidelectrode accessibility

Core Design Contradiction:

ReliabilityVSEase of operation

Solution Approach 1:

The device structure is segmented such that the light emitting die with vertical electrodes is mounted on a substrate, and the encapsulant is applied over the entire structure. This segmentation allows the vertical electrodes to maintain their current spreading function while becoming accessible through the encapsulant, resolving the contradiction between current spreading and electrode accessibility

Inventive Principle:

Principle #1Segmentation

Solution Approach 2:

The transparent encapsulant acts as an intermediary that provides a protective and accessible interface for the vertical electrodes. It allows external connections to be made to the electrodes while maintaining their vertical configuration for optimal current spreading, thus resolving the contradiction between current spreading and electrode accessibility

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If lateral electrodes are used in light emitting dies, then electrode accessibility is improved, but light extraction efficiency deteriorates due to electrode coverage

Engineering Contradiction:

Improveelectrode accessibilityVSAvoidlight extraction efficiency

Core Design Contradiction:

Ease of operationVSLoss of energy

Solution Approach 1:

Instead of placing electrodes laterally on the light emitting surface (which blocks light), the electrode configuration is inverted to vertical, extending through the die thickness. This inversion allows light extraction to occur through the transparent encapsulant rather than being blocked by lateral electrodes, while maintaining accessibility through the encapsulant interface

Inventive Principle:

Principle #13The other way round (Inversion)

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 configuration enhances light extraction efficiency by preventing electrode coverage over the N-type GaN and allows for accessible electrodes, simplifying external connections and reducing production complexity.

Implementation Method 1

an active region configured to emit light in response to an applied electrical voltage

Methodology Applied

Scientific EffectElectroluminescence: Electroluminescence

Data Source

PatentUS20250072170A1Solid state lighting devices with accessible electrodes and methods of manufacturing

Publication Date: 2025.02.27 MICRON TECHNOLOGY INC

AI summary

Various embodiments of light emitting dies and solid state lighting (“SSL”) devices with light emitting dies, assemblies, and methods of manufacturing are described herein. In one embodiment, a light emitting die includes an SSL structure configured to emit light in response to an applied electrical voltage, a first electrode carried by the SSL structure, and a second electrode spaced apart from the first electrode of the SSL structure. The first and second electrode are configured to receive the applied electrical voltage. Both the first and second electrodes are accessible from the same side of the SSL structure via wirebonding.