Hexagonal Seed Crystal Substrate for Nitride Growth
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Solution Overview
Problem
There is a need for a technique to increase the diameter of substrates for crystal growth while maintaining the quality of nitride crystal substrates, particularly for large-diameter substrates exceeding 2 inches, as existing methods face challenges in achieving high-quality substrates with minimal defects and uniformity.
Innovation Solution
A substrate for crystal growth is created by arranging multiple seed crystal substrates in a disc shape with parallel main surfaces and adjacent lateral surfaces in contact, forming a honeycomb pattern with rotational symmetries, using a regular hexagonal planar shape for the substrates, and employing a specific arrangement and adhesive technique to ensure uniformity and strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If a single large-diameter substrate for crystal growth is used, then the productivity and uniformity of nitride crystal substrate manufacturing are improved, but it becomes difficult to manufacture high-quality substrates with minimal defects and uniform crystal structure
Solution Approach 1:
The invention divides a large-diameter substrate for crystal growth into multiple smaller seed crystal substrates arranged in a honeycomb pattern. Each seed crystal substrate has a diameter of 2 inches or less and maintains high crystal quality. By segmenting the large substrate into multiple high-quality small substrates, the invention achieves both large overall diameter (improving productivity) and maintains manufacturing precision of individual crystal regions.
Solution Approach 2:
The invention merges multiple high-quality small-diameter seed crystal substrates into a single large-diameter substrate structure. The seed crystal substrates are arranged in a honeycomb pattern with their main surfaces parallel and adjacent lateral surfaces in contact, creating a unified large substrate that exhibits improved overall productivity while preserving the high crystal quality of constituent parts.
2Length of stationary object
If multiple small substrates are arranged to form a large substrate, then the diameter and productivity are increased, but the uniformity of crystal structure and reduction of off-angle variation become challenging
Solution Approach 1:
The invention applies local quality by ensuring that each seed crystal substrate in the honeycomb arrangement maintains its own high-quality crystal structure with controlled off-angle variation (±0.15° or less). By optimizing the local crystal quality of individual substrates and their arrangement orientation, the invention achieves uniform overall crystal structure across the large-diameter substrate while maintaining local structural integrity.
3Strength
If seed crystal substrates are arranged with adjacent lateral surfaces in contact, then the structural strength and durability are improved, but the manufacturing complexity and alignment precision requirements increase
Solution Approach 1:
The invention utilizes the asymmetric hexagonal crystal structure of the seed crystal substrates to simplify the arrangement process. The honeycomb pattern naturally arises from the hexagonal geometry, where adjacent substrates contact at specific lateral surfaces. This asymmetric geometric approach simplifies the alignment process compared to symmetric arrangements, as the hexagonal shape provides natural alignment cues that reduce manufacturing complexity while maintaining structural strength.
Data Source
AI summary
There is provided a substrate for crystal growth used for a vapor phase growth of a crystal, wherein a plurality of seed crystal substrates made of a group III nitride crystal are arranged in a disc shape, so that their main surfaces are parallel to each other and adjacent lateral surfaces are in contact with each other; and the plurality of seed crystal substrates constituting at least a portion other than a peripheral portion of the substrate for crystal growth respectively has a main surface whose planar shape is a regular hexagon, and a honeycomb pattern obtained by matching the seed crystal substrates has two or more symmetries, when the substrate for crystal growth is rotated once, with an axis passing through a center of a main surface of the substrate for crystal growth and orthogonal to the main surface as a central axis.