Air Void Structures in Semiconductor Fabrication
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Solution Overview
Problem
Existing semiconductor fabrication methods for forming air voids are inefficient, unstable, and time-consuming, often requiring ex-situ processes that lead to growth interruptions and non-uniformity, particularly when using III-V materials like GaN on foreign substrates with large lattice mismatches.
Innovation Solution
The method involves forming a first semiconductor layer with a group III material and a second group III material on a substrate, creating air voids by adjusting temperature and gas flow conditions during epitaxial growth using MOCVD or MBE processes, allowing for the growth of epitaxial layers with embedded air voids of controlled size and density, enabling uninterrupted and efficient semiconductor layer formation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If ex-situ processes are used to form air voids, then air voids can be formed, but the process becomes time-consuming and causes growth interruptions
Solution Approach 1:
The patent incorporates air void formation directly into the epitaxial growth process by controlling temperature and gas flow conditions during growth, rather than performing air void formation as a separate ex-situ step. This preliminary integration eliminates growth interruptions and reduces total fabrication time while maintaining stable air void formation.
Solution Approach 2:
The patent merges the air void formation process with the epitaxial growth process into a single integrated operation. By combining these previously separate processes, the method eliminates the time loss associated with growth interruptions and achieves both air void formation and layer growth simultaneously.
2Reliability
If ex-situ processes are used to form air voids, then air voids can be formed, but the process becomes complex and unstable
Solution Approach 1:
The patent merges the air void formation process with the epitaxial growth process into a single integrated operation. By combining these previously separate processes, the method eliminates the complexity and instability associated with multiple process steps while maintaining stable air void formation.
Solution Approach 2:
The epitaxial growth process itself provides the conditions necessary for air void formation through controlled temperature and gas flow parameters. The system uses its own inherent capabilities to achieve air void formation without requiring additional external processing steps, thereby reducing overall process complexity.
3Ease of manufacture
If foreign substrates with large lattice mismatches are used, then substrate availability is improved, but threading dislocations increase
Solution Approach 1:
The patent employs air void structures that modify the stress distribution and lattice matching parameters at the interface between the foreign substrate and the III-V material layers. By changing the physical parameters of the interface region through air void incorporation, the method reduces threading dislocation formation while maintaining the ease of using foreign substrates.
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 allows for the formation of semiconductor layers with embedded air voids that enhance light extraction efficiency in LEDs and facilitate the bulk production of freestanding GaN substrates, improving the quality and efficiency of semiconductor devices.
Implementation Method 1
forming a first semiconductor layer comprising a first group III material and a second group III material on a substrate; forming a second semiconductor layer on the first semiconductor layer. In some embodiments, the second semiconductor layer may include an epitaxial layer of a group III-V material.
Implementation Method 2
the process for epitaxial growth of the group III-V material may include a metal organic chemical vapor deposition (MOCVD) process.
Implementation Method 3
the process for epitaxial growth of the group III-V material may include a molecular beam epitaxy (MBE) process.
Implementation Method 4
removing at least the portion of the second group III material from the first semiconductor layer may include flowing a gas flow including hydrogen in the processing chamber.
Data Source
AI summary
Aspects of the disclosure provide for mechanisms for forming air voids for semiconductor fabrication. In accordance with some embodiments, a method for forming air voids may include forming a first semiconductor layer including a first group III material and a second group III material on a substrate; forming a plurality of air voids in the first semiconductor layer by removing at least a portion of the second group III material from the first semiconductor layer; and forming a second semiconductor layer on the first semiconductor layer. The second semiconductor layer may include an epitaxial layer of a group III-V material. In some embodiments, the first group III material and the second group III material may be gallium and indium, respectively.