Single-Crystal CVD Diamond Growth on High-Dislocation Substrates
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Solution Overview
Problem
Existing methods for growing large area single crystal CVD synthetic diamond face challenges such as high dislocation density, impurity incorporation from non-diamond substrates, and process parameter limitations, which hinder applications like low birefringence optical windows.
Innovation Solution
A process for growing single crystal CVD diamond on a single crystal diamond substrate with a high dislocation density, involving controlled CVD synthesis conditions including temperature, power density, and gas composition to achieve a crack-free thickness of at least 0.5 mm, minimizing substrate contamination and dislocation density.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional HPHT or CVD methods are used to grow diamond crystals, then diamond material can be produced, but the crystals exhibit significant impurity inclusions and structural defects that limit optical transmission and overall quality
Solution Approach 1:
The patent applies preliminary action by pre-coating the diamond crystal seed with a buffer layer of cubic boron nitride (c-BN) before initiating diamond growth. This pre-preparation step creates a controlled interface that prevents impurity incorporation and structural defects during subsequent crystal growth, thereby improving crystal quality without significantly increasing manufacturing complexity
Solution Approach 2:
The patent introduces cubic boron nitride (c-BN) as an intermediary buffer layer between the substrate and the diamond crystal. This intermediary layer acts as a protective interface that eliminates impurity inclusions and structural defects during diamond growth, achieving high-quality crystals while maintaining feasible manufacturing processes
2Productivity
If high pressure and high temperature conditions are applied to grow diamond crystals, then diamond material can be formed, but the process requires complex equipment and cannot produce large single-crystal diamonds greater than 3 carats
Solution Approach 1:
The patent replaces the conventional HPHT mechanical pressure system with a chemical vapor deposition process using a buffer layer approach. This substitution allows diamond crystals greater than 3 carats to be grown as single crystals without requiring the complex high-pressure equipment, thereby increasing productivity while reducing device complexity
Solution Approach 2:
The patent changes the growth parameters by using chemical vapor deposition at controlled temperatures and pressures with a c-BN buffer layer, rather than maintaining extreme HPHT conditions throughout the process. This parameter change enables growth of larger single-crystal diamonds while simplifying the equipment requirements
3Manufacturing precision
If conventional diamond growth methods are used, then diamond crystals can be produced, but they exhibit birefringence and lack the optical clarity required for fine jewelry applications
Solution Approach 1:
The patent applies preliminary action by pre-coating the diamond crystal seed with a buffer layer of cubic boron nitride (c-BN) before initiating diamond growth. This pre-preparation step creates a controlled interface that prevents impurity incorporation and structural defects during subsequent crystal growth, thereby improving crystal quality without significantly increasing manufacturing complexity
Solution Approach 2:
The patent introduces cubic boron nitride (c-BN) as an intermediary buffer layer between the substrate and the diamond crystal. This intermediary layer acts as a protective interface that eliminates impurity inclusions and structural defects during diamond growth, achieving high-quality crystals while maintaining feasible manufacturing processes
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
The process produces high-quality, crack-free single crystal CVD diamond suitable for various applications, reducing dislocation density and impurity incorporation, enabling broader industrial use.
Implementation Method 1
a catalyst particle used to grow a diamond crystal
Implementation Method 2
coating the diamond crystal seed with a buffer layer of cubic boron nitride (c-BN) prior to growth of the diamond crystal
Data Source
Figure 1~2
Figure 3~4
AI summary
A method of manufacturing synthetic diamond material using a chemical vapour deposition process, and a diamond obtained by such a method are described. The method comprises providing a freestanding synthetic single crystal diamond substrate wafer having a dislocation density of at least 107 cm-2. The synthetic single crystal diamond substrate wafer is located over a substrate holder within a chemical vapour deposition reactor. Process gases are fed into the reactor, the process gases including a gas comprising carbon. Crack-free synthetic diamond material is grown on a surface of the single crystal diamond substrate wafer at a temperature of at least 900°C to a thickness of at least 0.5 mm and with lateral dimensions of at least 4 mm by 4 mm.