Silicon-Doped Aluminum Nitride Buffer Layer for LED Strain Management
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Solution Overview
Problem
The lattice constant difference between substrates and semiconductor layers in LED epitaxy manufacturing leads to epitaxy defects, and the use of aluminum nitride as a buffer layer results in high dislocation density, surface roughness, and cracking due to high activity and low surface mobility of aluminum atoms.
Innovation Solution
A composite substrate with an aluminum nitride layer doped with silicon to regulate residual stress, having a film thickness less than 3.5 μm and a defect density of less than 5×10^9/cm², and a strain release layer with Al1-xGaxN material doped with silicon to manage compressive strain, is used to improve the quality of the semiconductor layers.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If an aluminum nitride layer is used as the buffer layer, then the lattice constant difference between substrate and semiconductor layer is reduced, but high dislocation density, high surface roughness, and cracking occur due to high activity and low surface mobility of aluminum atoms
Solution Approach 1:
The patent changes the chemical composition parameter of the aluminum nitride layer by doping it with silicon. This parameter change modifies the physical and chemical properties of the layer, reducing aluminum atom activity and improving surface mobility, thereby preventing cracking and reducing dislocation density while maintaining lattice constant matching.
Solution Approach 2:
The patent creates a composite material system by combining aluminum nitride with silicon dopant. This composite approach allows the buffer layer to simultaneously achieve good lattice matching with the substrate and improved structural integrity through the synergistic effects of the aluminum nitride-silicon composite system.
2Reliability
If silicon is doped in the aluminum nitride layer, then residual stress is regulated and defect density is reduced, but doping process complexity increases
Solution Approach 1:
The patent introduces silicon doping as a parameter change in the aluminum nitride layer composition. This single parameter modification achieves multiple benefits including residual stress regulation, defect density reduction, and improved surface quality, while the doping process can be integrated into existing epitaxial manufacturing workflows.
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 approach reduces defect density and surface roughness, enhancing the crystallization quality and light extraction efficiency of the LED by minimizing lattice mismatch-induced strain and improving epitaxial growth.
Implementation Method 1
Silicon is doped in the aluminum nitride layer to regulate residual stress
Implementation Method 2
Silicon is doped in the aluminum nitride layer to regulate residual stress
Data Source
AI summary
A composite substrate including a substrate, a buffer layer, and a strain release layer. The buffer layer is disposed on the substrate is provided. The strain release layer is disposed on the buffer layer, wherein the buffer layer is between the substrate and the strain release layer. A material of the strain release layer includes Al1-xGaxN, where 0≤x<0.15. The strain release layer is doped with silicon to release a compressive strain due to the buffer layer. A concentration of silicon doped in the strain release layer is greater than 1019 cm−3. A defect density of the strain release layer is less than or equal to 5×109/cm2. A light-emitting diode is also provided.