Diffusion Barrier Layer for LED Reflective Reliability
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Solution Overview
Problem
Light emitting devices face issues with degradation of reflectance, electrical characteristics, and light emission efficiency due to diffusion of constituent atoms from bonding layers into reflective layers, leading to potential peeling off of diffusion barrier layers under thermal stress.
Innovation Solution
A light emitting device design incorporating a diffusion barrier layer interposed between the reflective layer and bonding layers, preventing atom diffusion and localized to minimize peeling risks, with specific thickness and material choices to enhance reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a diffusion barrier layer is added to prevent atom diffusion, then reliability is improved, but device complexity increases
Solution Approach 1:
A diffusion barrier layer is introduced as an intermediary between the bonding layer and the reflective layer. This barrier layer prevents constituent atoms from the bonding layer from diffusing into the reflective layer, thereby maintaining reflectance and electrical characteristics without requiring fundamental changes to the existing device structure.
Solution Approach 2:
The diffusion barrier layer is constructed using composite material structures, including combinations such as Ti/Ni, Ti/Pt, Ti/W, or Ti/ Ru, where each layer provides specific functions. The Ti layer serves as a diffusion barrier while the Ni, Pt, W, or Ru layers provide additional protective and conductive properties, creating a multi-functional composite structure that enhances reliability.
2Reliability
If the diffusion barrier layer is made thicker to prevent diffusion, then reliability is improved, but manufacturing precision requirements increase
Solution Approach 1:
The thickness of the diffusion barrier layer is optimized to specific parameter ranges: the Ti layer is controlled at 5-50 nm and the Ni/Pt/W/Ru layer at 50-200 nm. These parameter specifications balance diffusion prevention effectiveness with manufacturability, ensuring that the barrier is thick enough to prevent atom diffusion but thin enough to be manufactured with standard precision capabilities.
3Device complexity
If bonding layers are placed directly on reflective layer, then device complexity is reduced, but reflectance degrades due to atom diffusion
Solution Approach 1:
The diffusion barrier layer acts as a protective intermediary between the bonding layer and the reflective layer, preventing direct contact and atom diffusion. This maintains the high reflectance of the reflective layer (such as Al or Ag) while still allowing the bonding layer to provide necessary electrical and mechanical functions, thus preserving optical performance without significantly increasing device complexity.
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 degradation of reflectance, electrical characteristics, and light emission efficiency, ensuring high reliability by restricting atom diffusion and reducing peeling risks through strategic layer placement and material selection.
Implementation Method 1
a diffusion barrier layer locally interposed between the reflective layer and the second bonding layer
Data Source
AI summary
A light emitting device includes a substrate; a light emitting structure disposed on the substrate; a first insulation layer disposed on the light emitting structure; a second insulation layer disposed on the first insulation layer; a first electrode and a second electrode electrically connected to the light emitting structure; a first pad electrically connected to the first electrode; and a second pad electrically connected to the second electrode.