Diamond-Silicon Carbide Composite Substrate for Crack-Free CVD Growth
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Solution Overview
Problem
The challenge lies in growing thick, crack-free diamond films on substrates with minimal stress, as existing methods face issues with delamination, cracking, and the integration of diamond with substrates due to significant differences in physical and chemical properties, limiting their industrial applications.
Innovation Solution
A multilayer substrate comprising a diamond layer and a composite layer of diamond and silicon carbide, optionally with silicon, where the diamond layer is grown using chemical vapor deposition (CVD) with strong sp3 carbon-carbon bonding, reducing stress and enabling large geometric dimensions without delamination or cracking.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If thick diamond films are grown on substrates, then the diamond layer thickness increases, but stress and cracking occur
Solution Approach 1:
The patent uses a composite substrate structure consisting of a base substrate combined with an intermediate layer of silicon carbide and diamond particles. This composite structure allows the diamond layer to be grown thicker while reducing stress through the compliant intermediate layer, which accommodates thermal expansion differences between the substrate and diamond.
Solution Approach 2:
The intermediate layer of silicon carbide and diamond particles acts as a mediator between the base substrate and the thick diamond film. This intermediate layer reduces the direct thermal stress transmission from the substrate to the diamond film, enabling thicker diamond growth without cracking.
2Ease of manufacture
If diamond is grown on conventional substrates, then the diamond layer can be formed, but delamination occurs due to property differences
Solution Approach 1:
The intermediate layer of silicon carbide and diamond particles serves as a mediator that improves adhesion between the base substrate and the diamond film. This intermediate layer has properties intermediate between the substrate and diamond, creating stronger bonds and preventing delamination.
Solution Approach 2:
The composite intermediate layer combines silicon carbide and diamond particles to create a material with enhanced adhesion properties. This composite structure provides both mechanical strength and chemical compatibility, ensuring reliable bonding of the diamond film to the substrate.
3Reliability
If high-quality single crystal diamond is used, then material properties are excellent, but availability and size are limited
Solution Approach 1:
The patent uses a disposable or replaceable base substrate that can be easily replaced if damaged. This allows the use of smaller, more abundant substrate materials instead of requiring large, rare single crystal diamond, while still achieving excellent material properties through the diamond film growth.
Solution Approach 2:
The patent segments the diamond structure into a thin film layer grown on a composite intermediate layer, rather than requiring a single large crystal. This segmentation allows the use of smaller diamond crystals or particles that can be aggregated to form the functional diamond layer, increasing availability and size options.
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 solution achieves a diamond layer with low stress, allowing for thicker, crack-free films suitable for mechanical, thermal management, and optical applications, enhancing durability and thermal conductivity while maintaining chemical inertness.
Implementation Method 1
a diamond layer and a composite layer of diamond and silicon carbide, and, optionally, silicon... where the diamond layer is grown using chemical vapor deposition (CVD)
Implementation Method 2
diamond layer is grown using chemical vapor deposition (CVD) with strong sp3 carbon-carbon bonding
Data Source
AI summary
A multilayer substrate includes a diamond layer CVD grown on a composite layer. The composite layer includes particles of diamond and silicon carbide and, optionally, silicon. A loading level (by volume) of diamond in the composite layer can be ≥ 5 %; ≥ 20 %; ≥ 40 %; or ≥ 60 %. The multilayer substrate can be used as an optical device; a detector for detecting radiation particles or electromagnetic waves; a device for cutting, drilling, machining, milling, lapping, polishing, coating, bonding, or brazing; a braking device; a seal; a heat conductor; an electromagnetic wave conductor; a chemically inert device for use in a corrosive environment, a strong oxidizing environment, or a strong reducing environment, at an elevated temperature, or under a cryogenic condition; or a device for polishing or planarization of other devices, wafers or films.