LED Ohmic Contact Structure With Diffusion Blocking Layer
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Solution Overview
Problem
Current LED chip packaging using flip chip technology often results in voids at the ohmic contact, leading to electrode detachment and deep metal diffusion that affects the reliability and optoelectronic performance of the chips.
Innovation Solution
A light-emitting device with an epitaxial structure, a diffusion blocking layer, an ohmic contact layer, and electrodes, where the diffusion blocking layer prevents excessive metal diffusion during high-temperature fusion, enhancing electrical conduction and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high-temperature fusion is used to form ohmic contact, then electrical conduction is improved, but metal diffusion into the semiconductor region becomes too deep causing leakage
Solution Approach 1:
A diffusion blocking layer comprising a GaInP layer and an AlInP layer is introduced between the metal electrode and the semiconductor region. This intermediary layer prevents metal atoms from diffusing into the semiconductor during high-temperature fusion while still allowing ohmic contact to be formed, thus resolving the contradiction between achieving good electrical conduction and preventing harmful metal diffusion.
Solution Approach 2:
The diffusion blocking layer is constructed as a composite structure with two distinct layers: a GaInP layer and an AlInP layer. Each layer has specific material properties that contribute to blocking metal diffusion while maintaining electrical conductivity. The composite structure provides superior performance compared to a single-layer approach.
2Reliability
If high-temperature fusion is used to form ohmic contact, then electrical conduction is improved, but voids are formed at the contact interface leading to electrode detachment
Solution Approach 1:
The multi-layer diffusion blocking structure (GaInP layer + AlInP layer) creates a more uniform and compliant interface during the high-temperature fusion process. This composite structure distributes thermal stress more evenly and prevents void formation, thereby maintaining both good electrical conduction and strong electrode connection without detachment.
Solution Approach 2:
By changing the material composition and layer structure at the interface, the thermal and mechanical properties of the contact region are optimized. The diffusion blocking layers have intermediate properties between the metal electrode and semiconductor, reducing thermal mismatch and preventing void formation during high-temperature processing.
3Reliability
If diffusion blocking layer is added to prevent metal diffusion, then reliability is improved, but device structure becomes more complex
Solution Approach 1:
The diffusion blocking layers serve as intermediary layers that are seamlessly integrated into the existing device architecture. While they do add structural elements, these layers are positioned at the interface region and can be incorporated into the existing epitaxial growth process, minimizing additional manufacturing complexity while providing significant reliability improvements.
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 deep metal diffusion, improves electrode connection, and enhances the overall reliability and optoelectronic performance of the light-emitting device by using a diffusion blocking layer to control the thickness of the metal interface, reducing voids and leakage.
Implementation Method 1
The diffusion blocking layer is disposed on a surface of the first semiconductor layer opposite to the active layer
Implementation Method 2
Electrodes in the LED chips are usually made of metals or metal alloy materials, which are fused at high temperature to form an ohmic contact with a semiconductor region
Data Source
AI summary
A light-emitting includes an epitaxial structure, a diffusion blocking layer, an ohmic contact layer, a first electrode, and a second electrode. The epitaxial structure includes a first semiconductor layer, an active layer, and a second semiconductor layer disposed sequentially in such order. The diffusion blocking layer is disposed on a surface of the first semiconductor layer opposite to the active layer. The ohmic contact layer is disposed on a surface of the diffusion blocking layer opposite to the first semiconductor layer. The first electrode is disposed on a surface of the ohmic contact layer opposite to the diffusion blocking layer and is electrically connected to the first semiconductor layer. The second electrode is disposed on a surface of the second semiconductor layer adjacent to the active layer and is electrically connected to the second semiconductor layer. A method for manufacturing the light-emitting device is also provided.