Single Crystal Body Reorientation via Selective Material Removal
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Solution Overview
Problem
The manufacturing of high-quality single crystal substrates, particularly for nitride semiconducting materials like GaN, faces challenges due to lattice mismatch with foreign substrates, leading to stress and defectivity, and there is a need for methods to improve the crystallographic orientation of these substrates for better semiconductor applications.
Innovation Solution
A method and apparatus for crystallographically reorienting single crystal bodies by characterizing their orientation, calculating misorientation angles, and removing material from specific surfaces using x-ray diffraction and grinding processes to change the crystallographic orientation, allowing for the creation of non-parallel surfaces and reducing misorientation angles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If epitaxial growth of semiconducting materials is performed on foreign substrate materials, then semiconductor devices can be manufactured, but lattice mismatch causes stresses and defectivity in the overlying semiconductor materials layer
Solution Approach 1:
The patent applies parameter changes by modifying the crystallographic orientation parameters of the substrate through selective material removal. By changing the orientation angle of the substrate surface relative to the crystallographic axes, the patent optimizes the lattice match between the foreign substrate and the epitaxially grown semiconductor layer, thereby reducing misfit dislocations and improving layer quality while maintaining manufacturability
Solution Approach 2:
The patent implements preliminary action by performing crystallographic characterization and orientation adjustment of the substrate before epitaxial growth. The misorientation angle is calculated and corrected in advance through selective material removal, ensuring that the substrate is properly prepared before the semiconductor layer is deposited, thus preventing defect formation during growth
2Area of stationary object
If large surface area substrates are produced, then more semiconductor devices can be manufactured, but maintaining high quality and proper crystallographic orientation becomes more difficult
Solution Approach 1:
The patent applies local quality by performing localized material removal at specific regions of the substrate surface. Rather than uniformly processing the entire large substrate, the invention selectively removes material from specific areas to adjust crystallographic orientation, allowing different regions to have optimized local orientations that accommodate the large overall substrate area while maintaining high precision
Solution Approach 2:
The patent replaces traditional mechanical orientation adjustment methods with a combination of x-ray diffraction characterization and controlled material removal. This substitution enables precise measurement and adjustment of crystallographic orientation on large substrates without relying on mechanical alignment methods that become less effective at larger scales
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 high-quality single crystal substrates with reduced misorientation angles, improving the viability of semiconductor applications by enhancing the crystallographic orientation and reducing defects, thus facilitating the use of larger surface area substrates like sapphire.
Implementation Method 1
a x-ray gun directed at the stage and a x-ray detector positioned to detect x-rays diffracted from the single crystal body
Data Source
AI summary
A method of changing the crystallographic orientation of a single crystal body is disclosed that includes the steps of characterizing a crystallographic orientation of the single crystal body and calculating a misorientation angle between a select crystallographic direction of the single crystal body and a projection of the crystallographic direction along a plane of a first exterior major surface of the single crystal body. The method further includes removing material from at least a portion of the first exterior major surface to change the misorientation angle.