LED Electrode Barrier Structure for Al-Gold Diffusion Control
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Solution Overview
Problem
Conventional light-emitting diodes (LEDs) face issues with electromigration in aluminum electrodes under high temperature and humidity, leading to short circuits, and the use of gold as a covering layer reduces reflectivity and light-emitting performance.
Innovation Solution
A light-emitting device with a laminated structure featuring a first and second electrode, where the first electrode includes a reflection layer, an electrically conductive layer, and an intermediate layer with a barrier layer composed of repeating paired platinum layers, which prevents miscibility between aluminum and gold, thereby enhancing reliability and performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If gold is used as an upper layer to cover the aluminum electrode, then electromigration is reduced and reliability is improved, but the reflectivity of the aluminum layer is reduced and light-emitting performance deteriorates
Solution Approach 1:
The patent introduces an intermediate layer between the aluminum reflection layer and the gold electrically conductive layer. This intermediate layer acts as a mediator that prevents direct contact between aluminum and gold, thereby preventing miscibility while allowing both layers to fulfill their respective functions. The intermediate layer includes a barrier layer with repeating paired layer units (e.g., titanium nitride and platinum) that create diffusion barriers, stopping gold atoms from migrating into the aluminum layer and maintaining aluminum's reflectivity.
Solution Approach 2:
The electrode structure uses a composite multi-layer configuration consisting of aluminum reflection layer, intermediate barrier layer, and gold conductive layer. Each layer is composed of specific materials with distinct properties: aluminum for high reflectivity, titanium nitride and platinum for barrier properties, and gold for electrical conductivity. This composite structure combines the advantages of each material while mitigating their disadvantages through proper layering.
2Quantity of substance
If aluminum is used as the electrode material, then electrical conductivity is good and cost is low, but electromigration occurs easily under high temperature and humidity leading to short circuits
Solution Approach 1:
The patent applies beforehand cushioning by introducing the intermediate barrier layer in advance to protect the aluminum layer from future electromigration damage. The barrier layer with repeating paired layer units (titanium nitride and platinum) is deposited before the gold layer, creating a protective cushion that prevents gold atoms from penetrating into the aluminum layer under high temperature and humidity conditions, thereby preventing short circuits before they can occur.
3Reliability
If a thick platinum layer is used in the barrier layer, then prevention of miscibility between aluminum and gold is improved, but manufacturing complexity and material cost increase
Solution Approach 1:
The patent segments the barrier layer into repeating paired layer units instead of using a single thick layer. The barrier layer consists of multiple alternating layers of titanium nitride and platinum (e.g., TiN/Pt/TiN/Pt structure), where each pair forms a diffusion barrier. This segmentation achieves effective miscibility prevention through multiple thin layers rather than one thick layer, reducing material usage and simplifying manufacturing while maintaining or improving barrier effectiveness.
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 solution effectively prevents miscibility between aluminum and gold, improving the reliability and light-emitting performance of the LED by maintaining reflectivity and reducing the risk of short circuits.
Implementation Method 1
The intermediate layer includes a barrier layer which has a plurality of repeating paired layer units. The plurality of repeating paired layer units include at least two repeating paired layer units that are referred to as a first repeating paired layer unit, and a second repeating paired layer unit. Each of the first repeating paired layer unit and the second repeating paired layer unit includes a platinum layer.
Data Source
AI summary
A light-emitting device includes a light-emitting laminated structure, a first electrode, and a second electrode. The first electrode has a reflection layer, an intermediate layer, and an electrically conductive layer. The intermediate layer includes a barrier layer having a first repeating paired layer unit and a second repeating paired layer unit, each of which has a platinum layer. The first repeating paired layer unit is closer to the electrically conductive layer than the second repeating paired layer unit, and a thickness of the platinum layer of the first repeating paired layer unit is greater than a thickness of the platinum layer of the second repeating paired layer unit.