Silicon Carbide Seed Crystal Bonding for Cost Reduction
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Solution Overview
Problem
The high cost of manufacturing silicon carbide crystals is attributed to the expensive, high-quality silicon carbide seed crystals required for crystal growth, which are typically one-time consumables and produced in ultra-high temperature and pressure environments with slow growth rates.
Innovation Solution
A silicon carbide seed crystal is constructed using a combination of two silicon carbide substrates with a metal layer and adhesion layers that easily form silicides, allowing for bonding of a secondary substrate with a high-quality substrate to reduce costs while maintaining high-quality crystal growth, utilizing materials like titanium, tantalum, or chromium for adhesion and silver, aluminum, or gold for the metal layer.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If high-quality silicon carbide substrates are used for crystal growth, then crystal quality is improved, but manufacturing cost increases
Solution Approach 1:
The invention divides the seed crystal into two separate silicon carbide substrates: a first substrate providing mechanical support and a second substrate providing the crystal growth surface. This segmentation allows each substrate to be optimized independently - the second substrate can be high-quality for crystal growth while the first substrate can be lower-cost, thereby reducing overall manufacturing cost while maintaining crystal quality.
Solution Approach 2:
The invention creates a composite seed crystal structure by bonding two silicon carbide substrates together with different functional characteristics. The composite structure combines the mechanical properties of the first substrate with the crystal growth properties of the second substrate, achieving both cost reduction and high crystal quality.
2Ease of manufacture
If conventional single substrate seed crystals are used, then structure is simple, but cost reduction is limited
Solution Approach 1:
By segmenting the seed crystal into two substrates with distinct functions, the invention enables cost reduction through selective quality optimization while accepting increased structural complexity. The multi-layer structure allows different substrates to serve different purposes, reducing overall cost despite added complexity.
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 configuration enables the growth of high-quality silicon carbide crystals at reduced costs by utilizing a secondary substrate with lower impurities and defects, ensuring minimal contamination and maintaining structural integrity under high-temperature conditions.
Implementation Method 1
the material of the first adhesion layer has a property of easily forming silicide with silicon
Implementation Method 2
the material of the metal layer has a property of easily diffusing and reacting with silicon carbide
Implementation Method 3
the material of the metal layer has a property of easily diffusing and reacting with silicon carbide
Data Source
AI summary
A silicon carbide seed crystal includes a first silicon carbide substrate, a second silicon carbide substrate, a metal layer, and a first adhesion layer. The first silicon carbide substrate has a carbon surface and a silicon surface opposite to each other; the second silicon carbide substrate has a carbon surface and a silicon surface opposite to each other, in which the carbon surface of the second silicon carbide substrate is a surface utilized for crystal growth. The metal layer is disposed between the silicon surface of the second silicon carbide substrate and the silicon surface of the first silicon carbide substrate, and the first adhesion layer is disposed between the silicon surface of the first silicon carbide substrate and the metal layer, in which a material of the first adhesion layer has a property of easily forming silicide with silicon.