Group III Nitride Substrate Chemical Lift-Off via N-Polar Cavities
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Solution Overview
Problem
The challenge lies in manufacturing high-quality non-polar or semi-polar Group III nitride substrates with low defects, as existing methods like laser lift off are costly and complicated, and chemical lift off processes often damage the substrate, especially when trying to separate substrates of larger diameters suitable for commercialization.
Innovation Solution
A method involving forming a first Group III nitride layer, followed by a second layer with cavities through lateral growth, and then a third layer, where at least a partial thickness of the second layer is chemically etched to separate the third layer, which can be used as a substrate, ensuring at least one region of the inner surface of the cavities is N-polar, facilitating the use of chemical lift off for substrate separation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a chemical lift off process is used to separate the grown Group III nitride layer from the heterogeneous substrate, then the manufacturing cost is reduced and the process is simplified compared to laser lift off, but the substrate is damaged especially when separating larger diameter substrates
Solution Approach 1:
The patent applies local quality by creating N-polar regions specifically at the inner surfaces of cavities within the Group III nitride layer, while the rest of the layer maintains its structural integrity. This localized N-polarization enables chemical etching at specific locations without damaging the entire substrate, resolving the contradiction between ease of manufacture and substrate reliability.
Solution Approach 2:
The patent segments the Group III nitride layer by forming cavities that extend from the substrate interface toward the surface. These cavities create discrete N-polar regions that can be selectively etched, allowing the substrate to be separated into manageable sections rather than attempting to lift off the entire large-diameter substrate at once, thus preventing damage.
2Stability of the object's composition
If non-polar or semi-polar Group III nitride crystals are grown on heterogeneous substrates, then the polarity-related problems are solved, but the defect density increases which lowers quantum efficiency
Solution Approach 1:
The patent applies preliminary action by forming cavities and N-polar regions in the Group III nitride layer before final substrate separation. This pre-structuring allows for controlled chemical etching that removes defective regions near the substrate interface while preserving the high-quality crystal structure grown on the non-polar or semi-polar surface, thus reducing defect density while maintaining charge neutrality.
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 enables the production of non-polar or semi-polar Group III nitride substrates with reduced defects, allowing for the use of a chemical lift off process effectively, even for larger substrates, thereby mitigating the limitations of polar nitrides and enhancing substrate quality for applications like LEDs and laser diodes.
Implementation Method 1
subjecting at least a partial thickness of the second Group III nitride layer to chemical etching, thus obtaining the separated third Group III nitride layer
Implementation Method 2
forming a second Group III nitride layer having one or more cavities provided therein on the first Group III nitride layer using lateral growth
Data Source
AI summary
The non-polar or semi-polar group III nitride layer disclosed in a specific example of the present invention can be used for substrates for various electronic devices, wherein problems of conventional polar group III nitride substrates are mitigated or solved by using the nitride substrate of the invention, and further the nitride substrate can be manufactured by a chemical lift-off process.