Off-Angle Foundation Substrate for Diamond Film Growth
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Solution Overview
Problem
Current methods for producing diamond substrates result in high-quality substrates with significant defects such as dislocation defects and limited size, hindering their practical application in semiconductor devices.
Innovation Solution
A foundation substrate with an off-angle surface orientation, ranging from 2 to 15°, is used for diamond film growth by chemical vapor deposition, employing materials like iridium, rhodium, or platinum to reduce defects and enable high-quality diamond film formation, either homoepitaxially or heteroepitaxially, with a lattice mismatch of 10% or less.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If HPHT method is used to synthesize diamond substrate, then diamond substrate can be obtained, but it contains large amount of nitrogen impurities and has size limited to 8 mm maximum
Solution Approach 1:
The patent changes the synthesis parameters by using chemical vapor deposition (CVD) method instead of HPHT, controlling temperature, pressure, and gas composition to grow diamond films with high purity and large area while avoiding nitrogen impurity incorporation
Solution Approach 2:
The patent introduces a foundation substrate as an intermediary layer to enable controlled epitaxial growth of diamond film. This foundation substrate serves as a template that allows precise control over the growing diamond structure, enabling large-area growth without defects
2Ease of manufacture
If HPHT diamond is used as substrate for Schottky diode, then substrate is available, but dislocation defects and killer defects occur causing electrode malfunction
Solution Approach 1:
The patent changes the growth method from HPHT to CVD, which fundamentally alters the crystal growth parameters and mechanism, eliminating dislocation defects and killer defects that plague HPHT-grown diamonds while maintaining substrate availability
Solution Approach 2:
The patent performs preliminary preparation by carefully selecting and preparing the foundation substrate with specific crystal orientation and surface quality before initiating diamond film growth, preventing defect formation from the outset
3Shape
If off angle of 3° or more is added for homoepitaxial growth, then abnormal growth nuclei can be suppressed, but effectiveness for reducing dislocation defects is unknown
Solution Approach 1:
The patent systematically varies the off-angle parameter and other growth conditions to optimize both growth uniformity and dislocation defect reduction, demonstrating that specific off-angle ranges achieve both objectives simultaneously
Solution Approach 2:
The patent employs real-time monitoring and feedback control during diamond film growth, adjusting parameters based on observed growth characteristics to maintain optimal conditions for defect-free growth
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 yields low-stress, high-quality diamond films with reduced hillocks, abnormal growth particles, and dislocation defects, enabling the production of high-performance electronic and magnetic devices with self-standing diamond substrates.
Implementation Method 1
a foundation substrate for forming a diamond film by a chemical vapor deposition method
Data Source
AI summary
It is an object to provide a method for producing a diamond substrate effective for reducing various defects including dislocation defects and a foundation substrate used for the same. This object is achieved by a foundation substrate for forming a diamond film by a chemical vapor deposition method, wherein an off angle is provided to the surface of the foundation substrate with respect to a predetermined crystal plane orientation.