GaN Epitaxial Wing Structure for Wide Low-Defect Device Layers
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Solution Overview
Problem
Existing techniques for forming GaN layers on heterogeneous substrates, such as silicon or sapphire, result in high defect densities and deteriorated device characteristics due to threading dislocations, and struggle to create device layers with a wide width.
Innovation Solution
A semiconductor substrate design featuring a template substrate with aligned seed and growth suppression regions, allowing for Epitaxial Lateral Overgrowth (ELO) to form a first semiconductor part with a wing portion having a width-to-thickness aspect ratio of 5.0 or more, reducing defect density and improving flatness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a GaN layer is formed on a heterogeneous substrate, then a semiconductor device can be manufactured, but threading dislocations are generated at the interface resulting in high defect density
Solution Approach 1:
The invention segments the growth process into two distinct stages: initial vertical growth on the heterogeneous substrate to establish crystal orientation, followed by lateral overgrowth on a release layer to form the final device layer. This segmentation allows the device layer to be formed away from the defective substrate interface, reducing threading dislocation density while maintaining manufacturability
Solution Approach 2:
A release layer is introduced as an intermediary between the heterogeneous substrate and the GaN layer. This release layer serves as a temporary substrate during initial growth, then allows the GaN layer to be released and transferred to form the final device structure, eliminating direct contact between the device layer and the defective substrate interface
2Area of stationary object
If a device layer with wide width is formed using existing techniques, then device functionality is improved, but the formation process becomes difficult and defect density increases
Solution Approach 1:
The invention transitions from vertical growth to lateral overgrowth, utilizing the lateral dimension to expand the device layer width. By growing the GaN layer laterally on the release layer rather than vertically on the substrate, wide-width device layers can be formed with reduced defect density, as the lateral growth occurs away from the problematic substrate interface
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
Enables the formation of a device layer with a wide width and high crystallinity, minimizing defects and suppressing material overflow to the back surface, thereby enhancing the quality and reliability of semiconductor devices.
Implementation Method 1
Epitaxial Lateral Overgrowth (ELO) to form a first semiconductor part with a wing portion having a width-to-thickness aspect ratio of 5.0 or more
Data Source
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AI summary
Provided are a template substrate including a first seed region and a growth suppression region aligned in a first direction, and a first semiconductor part located above the template substrate. The first semiconductor part includes a first base portion located on the first seed region, and a first wing portion connected to the first base portion and facing the growth suppression region via a first void space. The first wing portion includes a wing end located above the growth suppression region. In the first void space, a ratio of a width in the first direction with respect to a thickness under the wing end is 5.0 or more.