GaN Epitaxial Groove Structure for Lower Dislocation Density
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Solution Overview
Problem
The existing methods for growing GaN-based materials on Al2O3 substrates using MOCVD technology result in high dislocation densities, which hinder the development of high-voltage resistant GaN-based power devices and long-lasting GaN-based LEDs.
Innovation Solution
A method involving the formation of patterned mask layers and controlled epitaxial growth to create grooves in the first GaN epitaxial layer, followed by lateral growth of subsequent epitaxial layers, effectively blocking dislocation extension and reducing dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If GaN-based materials are grown on Al2O3 substrates using traditional MOCVD epitaxial equipment, then the manufacturing process is simple and widely applicable, but the dislocation density of the GaN-based materials is high (about 1-3E8/cm³)
Solution Approach 1:
The patent divides the epitaxial growth process into multiple stages: first growing a GaN buffer layer, then forming patterned AlN layers with grooves, and finally growing subsequent GaN layers. This segmentation allows dislocations to be confined and blocked at specific interfaces, reducing overall dislocation density in the final GaN layer.
Solution Approach 2:
The patent introduces a vertical dimension by creating grooves that extend into the buffer layer and forming patterned mask layers at different depths. This three-dimensional structure enables dislocation blocking at multiple levels, transforming the traditional two-dimensional planar growth into a controlled three-dimensional architecture that effectively reduces dislocation density.
2Reliability
If the dislocation density of GaN-based materials is reduced to manufacture higher voltage resistant power devices, then the device performance improves, but the epitaxial growth process becomes more complex
Solution Approach 1:
The patent performs preliminary actions by first growing a GaN buffer layer and then forming patterned AlN mask layers with grooves before growing the final GaN layer. This preliminary structuring creates dislocation blocking interfaces in advance, ensuring that when the final GaN layer is grown, dislocations are already confined and blocked, resulting in high-quality material suitable for high-voltage devices.
Solution Approach 2:
The patent applies local quality by creating patterned regions with different properties: the AlN mask layers provide dislocation blocking in specific areas, while the grooves create localized regions for controlled growth. This localized structuring allows dislocation management in critical areas without requiring complete restructuring of the entire epitaxial process.
3Manufacturing precision
If patterned mask layers and controlled epitaxial growth are used to reduce dislocation density, then the material quality improves, but the manufacturing process complexity increases
Solution Approach 1:
The patent makes the AlN mask layers serve multiple functions: they act as etch masks during groove formation, serve as dislocation blocking barriers, and function as templates for subsequent GaN layer growth. This multi-functionality reduces the need for separate process steps, making the complex process more manageable while achieving high material quality.
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 significantly reduces the dislocation density of the GaN-based materials, thereby enhancing the performance and reliability of GaN-based semiconductor devices, particularly for high-voltage applications and extended LED lifespan.
Implementation Method 1
etching the first group-III-nitride epitaxial layer to form one or more grooves with the patterned first mask layer as a mask
Implementation Method 2
laterally growing and forming a second group-III-nitride epitaxial layer by performing a first epitaxial growth on the first group-III-nitride epitaxial layer
Implementation Method 3
growing and forming a third group-III-nitride epitaxial layer on the second group-III-nitride epitaxial layer and the patterned first mask layer by performing a second epitaxial growth
Data Source
AI summary
A group-III-nitride structure and a manufacturing method thereof are provided. In the manufacturing method, one or more grooves are formed by etching a first group-III-nitride epitaxial layer with a patterned first mask layer as a mask; then a second mask layer is formed at least on one or more bottom walls of the one or more grooves, and a first epitaxial growth is performed on the first group-III-nitride epitaxial layer to laterally grow and form a second group-III-nitride epitaxial layer with the second mask layer as a mask, where the one or more grooves are filled with the second group III-nitride epitaxial layer; a second epitaxial growth is then performed on the second group-III-nitride epitaxial layer to grow and form a third group-III-nitride epitaxial layer on the second group-III-nitride epitaxial layer and the patterned first mask layer.