Epitaxy Substrate Ring Protrusion Stress Management
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Solution Overview
Problem
The challenge in epitaxial growth is achieving uniformity and reducing cracks in the epitaxial layer due to uneven temperature distribution and stress caused by large radius of curvature, leading to poor quality of the semiconductor layer.
Innovation Solution
An epitaxy substrate with a ring-shaped protrusion on its edge and an aluminum nitride layer, where the substrate thickness is between 625 μm and 1000 μm, and the aluminum nitride layer thickness is between 1 nanometer and 100 nanometers, enhancing stress tolerance and temperature uniformity, and optionally including a buffer layer with a superlattice material to improve lattice matching.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the substrate has a large radius of curvature, then the substrate can accommodate large-area epitaxial growth, but the stress increases and temperature distribution becomes uneven
Solution Approach 1:
The substrate edge is segmented into multiple ring-shaped protrusions that divide the continuous edge into discrete stress-management zones. Each protrusion acts as an independent stress relief feature, allowing the large substrate area to maintain structural integrity while distributing stress locally at each protrusion site.
Solution Approach 2:
The ring-shaped protrusions create local structural variations at the substrate edge, where the protruding portions have different mechanical properties compared to the flat substrate area. This local quality change allows stress to be managed at specific locations without affecting the overall substrate integrity or reducing the usable growth area.
2Area of stationary object
If the substrate has a large radius of curvature, then the substrate can support large-area epitaxial layers, but the film thickness uniformity deteriorates
Solution Approach 1:
The ring-shaped protrusions segment the substrate edge into multiple zones that can independently manage thermal stress. This segmentation allows each protrusion region to maintain optimal temperature conditions for uniform film growth, preventing the temperature gradients that would otherwise cause thickness variations across the large substrate area.
Solution Approach 2:
The protrusions modify the local thermal parameters at the substrate edge by creating additional heat dissipation pathways. This changes the temperature distribution pattern, ensuring that even large-area substrates maintain sufficient temperature uniformity across the epitaxial growth zone to achieve consistent film thickness.
3Productivity
If the substrate has a large radius of curvature, then the substrate can accommodate large-scale production, but the epitaxial layer quality deteriorates due to increased cracks
Solution Approach 1:
The ring-shaped protrusions act as segmented stress relief features distributed around the substrate edge. Each protrusion serves as an independent crack-arresting element, allowing the substrate to maintain high structural reliability even as the overall substrate area and production scale increase.
Solution Approach 2:
The protrusions are pre-formed on the substrate before epitaxial growth, providing beforehand cushioning against the thermal stress that will develop during the growth process. This preventive measure ensures that cracks do not form during epitaxial layer formation, maintaining high product reliability at scale.
4Manufacturing precision
If the aluminum nitride layer thickness is increased, then the lattice matching improves, but the manufacturing complexity increases
Solution Approach 1:
The patent identifies and implements the optimal thickness parameter range (1 nm to 100 nm) for the aluminum nitride layer, where this specific parameter range achieves sufficient lattice matching between the substrate and epitaxial layer. By establishing this precise parameter window, the solution balances lattice matching requirements with manufacturing simplicity, avoiding the need for excessively thick layers that would increase process 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
This configuration results in an epitaxial layer with improved uniformity of film thickness and reduced cracks, with the bow of the substrate and epitaxial layer within acceptable limits, enhancing the overall quality of the epitaxial layer formed.
Implementation Method 1
an aluminum nitride layer, where the substrate thickness is between 625 μm and 1000 μm, and the aluminum nitride layer thickness is between 1 nanometer and 100 nanometers, enhancing stress tolerance and temperature uniformity
Implementation Method 2
the substrate has a ring-shaped protrusion on the edge of the second surface... the stress is correspondingly increased due to the large radius of curvature... the epitaxial layer formed can have improved quality
Implementation Method 3
the buffer layer includes a superlattice material... the lattice of the buffer layer is between the lattice of the aluminum nitride layer and the lattice of the gallium nitride epitaxial layer
Implementation Method 4
Epitaxial growth refers to the technology of growing new crystals on a substrate (such as a wafer) to form a semiconductor layer
Data Source
AI summary
An epitaxy substrate including a substrate and an aluminum nitride layer is provided. The substrate has a first surface and a second surface opposite to each other. The substrate has a ring-shaped protrusion on the edge of the second surface. The aluminum nitride layer is disposed on the first surface of the substrate. An epitaxial wafer structure is also provided.